CN111416371B

CN111416371B - Energy storage control system for series photovoltaic direct current collection system

Info

Publication number: CN111416371B
Application number: CN202010196758.2A
Authority: CN
Inventors: 朱淼; 李修一; 徐莉婷; 蔡旭
Original assignee: Shanghai Jiaotong University
Current assignee: Shanghai Jiaotong University
Priority date: 2020-03-19
Filing date: 2020-03-19
Publication date: 2023-05-23
Anticipated expiration: 2040-03-19
Also published as: CN111416371A

Abstract

The invention provides an energy storage control system for a series photovoltaic direct current collection system, which comprises: the power reference instruction calculation module receives different signal quantities through an input port, and calculates and generates a k group of hybrid energy storage unit total output power reference instruction p through an internal logic algorithm ^* _s‑k And sends the instruction to the instruction decomposition module; the instruction decomposition module performs p according to the internal filtering algorithm ^* _s‑k Real-time decomposition is carried out to generate an original output power reference instruction p of the storage battery in the k group of hybrid energy storage units _batk‑ref Reference command p for original output power of super capacitor in k group of hybrid energy storage units _sck‑ref And sends both to the state of charge management module. The invention can realize the distributed coordination control of a plurality of groups of hybrid energy storage units under the architecture of a series photovoltaic direct current collection system; and the active compensation stabilization of the mismatch power in the series photovoltaic direct current collection system is realized, and the system operation capability under the condition of wide power fluctuation is obviously improved.

Description

Energy storage control system for series photovoltaic direct current collection system

Technical Field

The invention relates to the field of new energy power generation and power electronic system control, in particular to an energy storage control system oriented to a series photovoltaic direct current collection system. And more particularly, to multiple sets of hybrid energy storage control strategies for tandem photovoltaic dc collection systems. Further, the power coordination control and the charge state management of the distributed hybrid energy storage device in the direct current collection type photovoltaic power station are related.

Background

Solar energy has the advantages of wide resource distribution, convenient conversion and utilization and the like, and becomes a main object for developing renewable energy sources at present, and photovoltaic power generation is a main form for developing and utilizing solar energy resources in a large scale. According to local conditions, the development and construction of various types of photovoltaic power generation are promoted, the technical innovation and the healthy development of the photovoltaic industry are promoted, and the development becomes a great strategic requirement in the new energy field of China.

The distribution condition of the illumination resources and the grid morphology of China determine a centralized large-scale photovoltaic power station, which is an important form of future photovoltaic development and utilization. The method is characterized by large-scale construction, large-scale collection, weak synchronous power supply support and high-voltage direct current (HVDC) transmission, and can become an important technical scene for the construction of large-scale photovoltaic power generation bases in the future of China.

On one hand, the system loss and the light discarding behavior must be reduced as much as possible, and the electric energy quality is improved; on the other hand, good operational adaptability under conditions of large random fluctuations in photovoltaic output is required. The traditional photovoltaic power station adopts an alternating current boosting and collecting technology, namely, the output of a photovoltaic array is subjected to MPPT control and a photovoltaic inverter to obtain stable low-voltage three-phase alternating current, and the stable low-voltage three-phase alternating current is connected into a power distribution network through a boosting transformer after being collected through a bus. The scheme mainly has two defects when applied to a large photovoltaic power generation base:

1. The problem of the parallel stability of multiple inverters under weak synchronous support is outstanding, and voltage out-of-limit and wide-frequency-domain oscillation are frequent;

2. the loss of the communication collecting line between stations is large, and the overall efficiency of the system is low;

in order to solve the problems, a photovoltaic direct-current boosting and collecting system can be adopted to construct a large-scale direct-current photovoltaic power generation base. As shown in fig. 1, the low-voltage direct current output by the photovoltaic array is directly pumped up to the voltage level of the direct current distribution network by the photovoltaic direct current boost converter, and after further collection, the direct current is concentrated and inverted by the VSC converter station to be connected into an alternating current power grid or further boosted by the large boost converter station to realize long-distance transmission of the direct current photovoltaic power generation base.

For different application scenarios, the photovoltaic direct current boost collection system can be divided into a "serial type" architecture and a "parallel type" architecture, as shown in fig. 2 and fig. 3, respectively.

In the parallel type collecting system shown in fig. 2, each photovoltaic array firstly realizes MPPT control through a non-isolated DC-DC converter, then is intensively connected in parallel to a low-voltage direct current bus in a station, and then realizes boosting through the isolated DC-DC converter, and further is integrated into a medium-voltage direct current distribution system (or is integrated into a medium-voltage alternating current distribution system through a VSC converter station). The structure can realize power decoupling control between the front-end photovoltaic array and the rear-stage boost converter, has flexible operation mode and strong expandability, and is suitable for small-scale direct-current photovoltaic power stations with complex illumination conditions, relatively concentrated distribution and shorter collection distance.

In the tandem-type collection system shown in fig. 3, each photovoltaic array realizes boost and maximum power tracking (MPPT) control through an isolated DC-DC converter, and a Medium Voltage Direct Current (MVDC) output is obtained by connecting the output sides of the converters in series and is directly incorporated into a direct current distribution system (or is incorporated into a medium voltage alternating current distribution system through a VSC converter station). The structure has the advantages of small collection current, few conversion levels and quick dynamic response, and is suitable for large-scale direct current photovoltaic power stations with large occupied area, good illumination consistency and long collection distance.

In the serial-type collecting system shown in fig. 3, n DC-DC converters constitute an "input independent-output serial-type" topology. Since the output currents of the DC-DC converters are equal, when the output forces of the arrays are balanced, the output voltages of the DC-DC converters are rated values u×o, and there are (u×o=ug/n, where UG is the rated voltage of the grid-side DC bus). When the output of each array is uneven (i.e. internal power mismatch occurs), UG remains constant (supported by the later stage converter), so that each DC-DC converter output voltage will deviate from u×o, part of the converter output voltage will be lower than u×o, and part of the module output voltage will be higher than u×o. Therefore, when the power mismatch is serious, the output voltage of a part of the DC-DC converter exceeds the allowable upper limit, and the corresponding array is forced to exit from the MPPT control, so that the power generation capacity of the system is reduced, and even the system cannot operate normally. The problem is a primary technical problem for restricting engineering application of the tandem photovoltaic direct current collection system.

At present, a certain research is carried out on the problems of operation control and light-storage coordination under the parallel direct current collection system architecture, but the technology for realizing the operation control and light-storage coordination in the serial direct current collection system is not fully researched and ideal results are not yet available.

The following literature is retrieved:

document 1: research on a distributed control method of a plurality of groups of light storage units of a direct-current micro-grid based on a consistency algorithm [ J/OL ]. Chinese motor engineering report:

1-10[2020-01-11].https://doi.org/10.13334/j.0258-8013.pcsee.190444.

summary:

in order to solve the problem of cooperative control among multiple groups of storage battery energy storage units in a distributed direct-current micro-grid, the distributed control based on a consistency algorithm is firstly provided, so that each BSU can distribute power in proportion to the charge state of a battery, and meanwhile, the average value of each bus voltage in the distributed network can be adjusted to be maintained at a rated value. Considering that the distributed voltage control based on the voltage observer can generate steady-state errors due to time delay, an initial value of the observer and the like, a voltage optimization control strategy based on a PI consistency algorithm is further provided, the voltage control problem is converted into an optimization problem, and the optimization target is to ensure that deviation of each bus from a rated value is minimum. The simulation result shows that the steady state value of the provided control strategy can not be influenced by time delay and the initial value of the algorithm integrator, and has higher reliability and robustness.

The technical points are compared: the document researches the problem of coordination control among a plurality of groups of energy storage devices under a parallel photovoltaic direct current grid-connected system, and has a certain objective relation with the scheme in the patent in application scenes and technical ideas. However, the solution described in this document does not take into account the basic features of the tandem photovoltaic direct current collection system and does not have the important function of stabilizing the power mismatch inside the system.

Document 2:

the photovoltaic DC boosting and collecting system improves the power weight layering control strategy [ J ]. High voltage technology, 2019,45 (10): 3247-3255.

In the photovoltaic direct-current boosting and collecting system, when the illumination of the series photovoltaic units is uneven, the unbalanced output voltage of the photovoltaic side cascading boosting converter unit can cause that the Maximum Power Point Tracking (MPPT) control of the photovoltaic module with lower photovoltaic output is difficult to realize by the traditional control strategy. Therefore, a weight layering control strategy based on slope control is provided, and the voltage of the output side of the boost converter is adjusted according to the change of the power weight difference value between the photovoltaic modules, so that the port voltage of the low-output voltage module is increased, and the photovoltaic modules are enabled to operate in an MPPT mode. The principle of the weight layering control strategy and the influence of the duty ratio limitation of the isolated DC/DC converter on MPPT control are analyzed, and the effectiveness of the strategy is verified through MATLAB/Simulink. The result shows that the MPPT working mode of the module with lower power weight can be realized when the irradiation severity is unbalanced by the provided control strategy, the grid-connected output characteristic of the photovoltaic system is improved, and the smooth switching of the control mode is realized. The paper research can provide reference for controlling the photovoltaic direct current boost pooling system.

The technical points are compared: the document researches the problem of operation control strategy of a series-type photovoltaic direct current collecting system under the condition of power mismatch, and proposes a solution, namely, the problem of overvoltage of a DC-DC boost converter caused by internal power mismatch is relieved to a certain extent through downward adjustment of the voltage of a network side direct current bus. However, compared with the scheme disclosed by the patent, the scheme has limited expansion degree on the system operation domain, and cannot support the implementation of light-storage coordination.

The literature [1] proposes a distributed coordination control method for multiple groups of light storage units in a direct-current micro-grid based on a consistency algorithm, and the method can realize voltage regulation and power distribution among multiple energy storage units in an isolated direct-current micro-grid and has a certain reference value for realizing light storage coordination control in a photovoltaic direct-current collection system. However, the method described in this document is only applicable to a photovoltaic direct current collection system with a multi-DC parallel output structure, and cannot directly guide the light-storage coordination operation under a tandem photovoltaic direct current collection system.

The literature [2] proposes a series photovoltaic direct current collection system operation control method considering internal power mismatch phenomenon, which has the core meaning that the network side direct current bus voltage UG of the collection system is dynamically adjusted within a certain range (+ -10%) through a post-stage VSC converter station so as to amplify the MPPT operation area of the system, improve the bearing capacity of the system on internal power mismatch and improve the operation adaptability. The strategy does not consider the light-storage coordination implementation under the serial direct current collection frame, and has limited solving effect on the problem of internal power mismatch. According to the scheme of the literature, the maximum power fluctuation range allowable by a single array on the premise of keeping MPPT operation is about +/-20%, and the reliable operation requirement of a system under short-time extreme working conditions or complex illumination conditions is difficult to meet.

Aiming at the inherent defects of the technical scheme in the document [1] [2], the invention innovatively provides a multi-group distributed hybrid energy storage unit coordinated operation control strategy for a series photovoltaic direct current collection system. The technical scheme realizes the organic integration of series photovoltaic direct current collection and light storage coordination power control, and simultaneously realizes the following two control targets:

1. active compensation stabilization of mismatch power in a collecting system;

2. and the total output power of the collection system is optimally regulated.

The control scheme is described in principle by using the typical system shown in fig. 4 as a technical scene, and the effectiveness of the control scheme is verified through an implementation case under simulation.

Aiming at the actual operation control requirement of a series-type photovoltaic direct current collection system, the patent aims at solving the following problems by combining the defects and shortcomings existing in the prior art:

under the condition of not influencing MPPT control of the front end array, active power balance control of the DC-DC converter in the tandem photovoltaic direct current collection system is realized, and power mismatch is eliminated, so that the operation adaptability of the system under the condition of wide fluctuation of input power is greatly enhanced;

the regulation and control of the integral grid-connected output power of the collecting system are realized by means of a plurality of groups of hybrid energy storage units, the power grid friendliness of the collecting system is improved, and the consumption and the delivery are promoted.

Disclosure of Invention

Aiming at the defects in the prior art, the invention aims to provide an energy storage control system for a series photovoltaic direct current collection system.

According to the invention, an energy storage control system for a series photovoltaic direct current collection system, as shown in fig. 5, comprises:

the power reference instruction calculation module receives different signal quantities through an input port, and calculates and generates a k group of hybrid energy storage unit total output power reference instruction p through an internal logic algorithm ^* _s-k And sends the instruction to the instruction decomposition module;

the instruction decomposition module performs p according to the internal filtering algorithm ^* _s-k Real-time decomposition is carried out to generate an original output power reference instruction p of the storage battery in the k group of hybrid energy storage units _batk-ref Reference command p for original output power of super capacitor in k group of hybrid energy storage units _sck-ref And sends the two to the state of charge management module;

the state of charge management module receives the state of charge SOC of the storage battery in the kth group of hybrid energy storage cells from the respective energy storage devices _batk And the super-capacitance state of charge SOC in the k-th hybrid energy storage unit _sck At the same time combine p received by instruction decomposition module _batk-ref And p is as follows _sck-ref Generating the total state of charge adjustment power of the k group of hybrid energy storage units, and sending the total state of charge adjustment power to a feedback correction module;

The feedback correction module receives the k-group hybrid energy storage unit output power p from the corresponding energy storage converter _s-k And incorporate deltap received by the state of charge management module _s-k Generating the output power p 'of the k-th group of modified hybrid energy storage units in real time according to an internal logic algorithm' _s-k And upload it to the in-station real-time communication system.

Preferably, the power reference instruction calculation module includes: a voltage feedback loop, a power feed-forward loop, and an adder;

the output ends of the voltage feedback loop, the power feedback loop and the power feedforward loop are respectively connected with the 1 st, 2 nd and 3 rd input ends of the adder, and the corresponding variables are respectively: voltage feedback loop reference component p _s-k-ref Power ofFeedback loop reference component p' _s-k-ref Power feed forward loop reference component p' _s-k-ref ；

The output end of the adder is the output end of the power reference instruction calculation module, and the input ends of the voltage feedback loop, the power feedback loop and the power feedforward loop are the input ends of the power reference instruction calculation module.

Preferably, the voltage feedback loop comprises: the device comprises a subtracter, a dead zone link, a PI controller and a saturation limiting link;

subtractor positive input end and constant signal source U _n Connected with each other, wherein U _n For the voltage rated value of each DC-DC boost converter output end, the minus input end of the subtracter is connected with the input end 1 of the power reference instruction calculation module, the output end of the subtracter is connected with the input end of the dead zone link, the output end of the dead zone link is connected with the input end of the PI controller, the output end of the PI controller is connected with the input end of the saturation limiting link, the output end of the saturation limiting link is the output end of the voltage feedback loop, and the output variable is recorded as p _s-k-ref. The specific interval parameters of the PI controller, the dead zone link and the saturation limiting link are preselected.

Preferably, the power feedback loop comprises: the device comprises a signal component accumulator, a first subtracter, a second subtracter, a dead zone link, a PI controller, a saturation limiting link, a first signal channel selection switch S1 and a second signal channel selection switch S2;

the first subtracter negative input end is connected with the power reference instruction calculation module input end 2, the first subtracter positive input end is connected with the output end of the first signal channel selection switch S1, the signal component accumulator input end is connected with the power reference instruction calculation module input end 3, the signal accumulator output end is connected with the second subtracter negative input end, the second subtracter positive input end is connected with the power reference instruction calculation module input end 4, the second subtracter output end is connected with the b input end of the first signal channel selection switch S1, the a input end of the first signal channel selection switch S1 is connected with a zero signal source, the first subtracter output end is connected with the dead zone link input end, the dead zone link output end is connected with the PI controller input end, and the PI controller output end The output end of the saturation limiting link is connected with the b input end of the second signal channel selection switch S2, the a input end of the second signal channel selection switch S2 is connected with a zero signal source, the output end of the second signal channel selection switch S2 is the output end of the power feedback loop, and the output variable is recorded as p' _s-k-ref The control end of the first signal channel selection switch S1 is connected with the input end 5 of the power reference instruction calculation module, and the control end of the second signal channel selection switch S2 is connected with the input end 6 of the power reference instruction calculation module;

the action logic of the first signal channel selection switch S1 and the second signal channel selection switch S2 is: when the control end variable is 0, connecting the signal quantity of the input end a to the output end; otherwise, the b input semaphore is connected to the output.

The specific interval parameters of the PI controller, the dead zone link and the saturation limiting link are preselected.

Preferably, the power feed forward loop comprises: a feedforward instruction calculation unit;

a first input terminal of the feedforward instruction calculation unit is connected with the module input terminal 4 to collect the signal quantity p ^* _station A second input of the feedforward command computation unit is connected to the module input 3 to collect a set of semaphores p _pv-1 ～p _pv-n The output end of the feedforward instruction calculating unit is the output end of the power feedforward loop, and the output variable is recorded as p' _s-k-ref 。

Preferably, the internal structure of the instruction decomposition module includes: butterworth low-pass filter, subtracter;

the input end of the Butterworth low-pass filter is the input end of the instruction decomposition module, the output end of the Butterworth low-pass filter is the first output end of the instruction decomposition module, and the output variable is the original output power reference instruction p of the storage battery in the k group of hybrid energy storage units _batk-ref The positive input end of the subtracter is connected with the input end of the Butterworth low-pass filter, the negative input end of the subtracter is connected with the output end of the Butterworth low-pass filter, the output end of the subtracter is a second output end of the instruction decomposition module, and the output variable isSuper capacitor original output power reference instruction p in k group of hybrid energy storage units _sck-ref ；

The order and band parameters of the butterworth low pass filter are all preselected.

Preferably, the state of charge management module comprises:

the energy storage device operation mode judging module is used for: respectively judging the running states of the storage battery and the super capacitor in the k group of hybrid energy storage units;

a power reference instruction correction module: according to the operation state combination of the storage battery and the super capacitor in the k group of hybrid energy storage units, the original power reference command is respectively corrected, and the state of charge management module needs to generate a control parameter FLAG while correcting the power reference command _rest-k And Δp _s-k ，FLAG _rest-k FLAG for the k-th group of hybrid energy storage unit limited FLAG bits _rest-k After the generation, uploading the generated data to a station-level controller through an intra-station real-time communication system;

Δp _s-k generated according to the following formula:

Δp _s-k ＝p _batk-res +p _sck-res

wherein, the liquid crystal display device comprises a liquid crystal display device,

Δp _s-k the power is adjusted for the total state of charge of the k-th group of hybrid energy storage units.

Preferably, the feedback correction module:

in order to offset the disturbance of the charge and discharge power to the global steady state of the system under the SOC adjustment action of the energy storage device and prevent oscillation, the feedback value of the total output power of the k-th group of hybrid energy storage units is corrected as follows:

p′ _s-k ＝p _s-k -Δp _s-k

p _s-k the total output power of the k-th hybrid energy storage unit;

p' _s-k and uploading the corrected total output power of the k-th group of hybrid energy storage units to an in-station real-time communication system.

Compared with the prior art, the invention has the following beneficial effects:

1. the invention can realize the distributed coordination control of a plurality of groups of hybrid energy storage units under the architecture of a series photovoltaic direct current collection system;

2. the invention can realize the active compensation stabilization of the mismatch power in the series photovoltaic direct current collection system, and obviously improve the system operation capability under the condition of wide power fluctuation;

3. the invention realizes light-storage coordination power control, optimizes the integral grid-connected output power of the station, improves the power grid friendliness of the direct-current photovoltaic power station, and promotes the digestion and the delivery.

Drawings

Other features, objects and advantages of the present invention will become more apparent upon reading of the detailed description of non-limiting embodiments, given with reference to the accompanying drawings in which:

fig. 1 is a schematic diagram of an application concept of a photovoltaic direct current collection system provided by the invention.

Fig. 2 is a schematic structural diagram of a parallel photovoltaic direct current collection system provided by the invention.

Fig. 3 is a schematic structural diagram of a tandem photovoltaic direct current collection system provided by the invention.

Fig. 4 is a schematic diagram of a basic system application scenario of the control strategy provided by the present invention.

Fig. 5 is a schematic diagram of the overall logic structure of the control strategy proposed by the present patent.

Fig. 6 is a schematic diagram of an internal logic structure of a power reference instruction calculation module according to the present invention.

Fig. 7 is a schematic diagram of an internal logic structure of an instruction decomposition module according to the present invention.

Fig. 8 is a schematic diagram of SOC area division modes adopted by the state of charge management module according to the present invention.

Fig. 9 is a schematic diagram of the series output port voltages of each DC-DC boost converter provided by the present invention.

Fig. 10 is a schematic diagram set of power response conditions of each device in a specific hybrid energy storage unit provided by the present invention.

Fig. 11 is a schematic diagram of a power response curve under the action of a station-level power reference command according to the present invention.

Detailed Description

The present invention will be described in detail with reference to specific examples. The following examples will assist those skilled in the art in further understanding the present invention, but are not intended to limit the invention in any way. It should be noted that variations and modifications could be made by those skilled in the art without departing from the inventive concept. These are all within the scope of the present invention.

According to the invention, an energy storage control system for a series photovoltaic direct current collection system comprises:

Specifically, the power reference instruction calculation module includes: a voltage feedback loop, a power feed-forward loop, and an adder;

the output ends of the voltage feedback loop, the power feedback loop and the power feedforward loop are respectively connected with the 1 st, 2 nd and 3 rd input ends of the adder, and the corresponding variables are respectively: voltage feedback loop reference component p _s-k-ref The power feedback loop reference component p' _s-k-ref Power feed forward loop reference component p' _s-k-ref ；

Specifically, the voltage feedback loop includes: the device comprises a subtracter, a dead zone link, a PI controller and a saturation limiting link;

Specifically, the power feedback loop includes: the device comprises a signal component accumulator, a first subtracter, a second subtracter, a dead zone link, a PI controller, a saturation limiting link, a first signal channel selection switch S1 and a second signal channel selection switch S2;

the negative input end of the first subtracter is connected with the input end 2 of the power reference instruction calculation module, the positive input end of the first subtracter is connected with the output end of the first signal channel selection switch S1, the input end of the signal component accumulator is connected with the input end 3 of the power reference instruction calculation module, and the output end of the signal component accumulator is connected with the negative input end of the second subtracter The positive input end of the second subtracter is connected with the input end 4 of the power reference instruction calculation module, the output end of the second subtracter is connected with the b input end of the first signal channel selection switch S1, the a input end of the first signal channel selection switch S1 is connected with a zero signal source, the output end of the first subtracter is connected with the input end of a dead zone link, the output end of the dead zone link is connected with the input end of a PI controller, the output end of the PI controller is connected with the input end of a saturation limiting link, the output end of the saturation limiting link is connected with the b input end of the second signal channel selection switch S2, the a input end of the second signal channel selection switch S2 is connected with the zero signal source, the output end of the second signal channel selection switch S2 is the output end of a power feedback loop, and the output variable is recorded as p' _s-k-ref The control end of the first signal channel selection switch S1 is connected with the input end 5 of the power reference instruction calculation module, and the control end of the second signal channel selection switch S2 is connected with the input end 6 of the power reference instruction calculation module;

Specifically, the power feed forward loop includes: a feedforward instruction calculation unit;

Specifically, the internal structure of the instruction decomposition module includes: butterworth low-pass filter, subtracter;

the input end of the Butterworth low-pass filter is the input end of the instruction decomposition module, and the output end of the Butterworth low-pass filterThe output variable is the original output power reference instruction p of the storage battery in the kth group of hybrid energy storage units for the first output end of the instruction decomposition module _batk-ref The positive input end of the subtracter is connected with the input end of the Butterworth low-pass filter, the negative input end of the subtracter is connected with the output end of the Butterworth low-pass filter, the output end of the subtracter is a second output end of the instruction decomposition module, and the output variable is the reference instruction p of the original output power of the super capacitor in the k group of hybrid energy storage units _sck-ref ；

Specifically, the state of charge management module includes:

Δp _s-k generated according to the following formula:

Δp _s-k ＝p _batk-res +p _sck-res

Specifically, the feedback correction module:

p′ _s-k ＝p _s-k -Δp _s-k

p _s-k the total output power of the k-th hybrid energy storage unit;

The present invention will be described in further detail with reference to the accompanying drawings and preferred examples.

Preferred example 1:

in order to verify the technical scheme provided by the patent, a system model shown in fig. 4 is established based on a MATLAB-Simulink environment, and main basic parameters are shown in table 1.

Table 1 application case main parameters

In the simulation process, the external environment temperature parameter is maintained at 25 ℃, irradiance of each front-end photovoltaic array is adjusted according to the trend shown in table 2, so that the internal power mismatch transient is induced by introducing step change of array irradiance at the moments of t=0.1s and t=0.4s, and effectiveness based on the scheme of the patent is tested. In the time section of t=0.1 s-0.7 s, the irradiance of photovoltaic array #8 drops to zero, aiming at simulating the extreme working condition that individual photovoltaic arrays in the system temporarily exit operation due to faults or overhauls.

TABLE 2 irradiance trend of photovoltaic arrays

As shown in fig. 9, the output forces of PV #1 to #8 are equal before 0.1s, the system operates under uniform conditions, no power mismatch phenomenon exists, and the output voltages of the photovoltaic direct current boost converters are all rated values 3750V. Step changes of different degrees occur to irradiance of each array at the moment of t=0.1s, and rated output voltage is recovered under the power balance control effect of each group of hybrid energy storage devices after the boost converters #1 to #4 experience overvoltage transient (maximum overvoltage amplitude is 27.9V); in contrast, boost converters # 5- #8 recover the rated output voltage after experiencing an under-voltage transient (maximum under-voltage amplitude-41.7V). Step changes of different degrees occur again to irradiance of each array at the moment of t=0.4s, and rated output voltage is recovered after the boost converters #1 to #4 experience under-voltage transient (maximum under-voltage amplitude-47.6V); in contrast, boost converters #5 to #8 recover the rated output voltage after experiencing an overvoltage transient (maximum overvoltage amplitude 40V).

Further, taking the mixed energy storage of the 1 st group and the 8 th group as an example, the power response frequency band decomposition effect and the charge state management effect of the internal energy storage device are observed and verified. As shown in fig. 10a/b, the actual power response curves of the internal energy storage devices of the 1 st group hybrid energy storage and the 8 th group hybrid energy storage are respectively. In particular, to verify the SOC management strategy of the energy storage device, the initial state of charge value socs8|t=0 of the supercapacitor in the 8 th group of hybrid energy storage is set to 0.95 (in the overcharge interval).

As can be seen from fig. 10a, after the power mismatch phenomenon occurs in the system at the time t=0.1 s, the super capacitor and the storage battery in the 1 st group of hybrid energy storage rapidly make power responses under different frequency bands under the adjustment of respective power reference instructions. Specifically, the output power of the super capacitor changes from 0kW to-29 kW (in a charging state) in a short time after t=0.1 s, and the output power of the storage battery is slowly adjusted from 0kW to-10 kW in the same time; the supercapacitor output power was then gradually decayed back to a steady state of 0kW, while the battery charge power continued to increase and eventually reached a new steady state value of-39 kW. Similarly, the supercapacitor output power after time t=0.4 s is changed from 0kW to 55kW (in a discharging state) in a short time, and the battery output power is slowly adjusted from-39 kW to-32 kW (7 kW adjusted in the same direction) in the same time; the super capacitor output power is gradually attenuated and reverts to a 0kW steady state, and the storage battery output power is continuously adjusted and finally reaches a new steady state value of 20kW.

As can be seen from fig. 10b, after the photovoltaic array pv#8 stops generating at time t=0.1 s, the devices in the 8 th group of hybrid energy storage rapidly make power responses in different frequency bands under the adjustment of the respective power reference command. Specifically, the output power of the super capacitor changes from 0kW to 41kW (in a discharging state) within a short time after the time t=0.1 s, and the output power of the storage battery is slowly adjusted from 0kW to 20kW within the same time; the supercapacitor output power was then gradually decayed back to a steady state of 0kW, while the battery discharge power continued to increase and eventually reached a new steady state value of 61kW. However, when the internal power distribution of the system is changed step by step again at the time t=0.4 s and the voltage transient change of the output port of each boost converter is caused, the state of charge of the supercapacitor still cannot be separated from the overcharge interval (socs8|t=0.4s≡0.949), and the psc8-ref is smaller than 0, so that the supercapacitor can be judged to be in the mode II. Therefore, the corresponding state of charge management strategy is triggered, and the power reference instruction is corrected, namely the super capacitor does not bear the power response of the current 8 th group of hybrid energy storage, and is fully transferred to the storage battery to bear. As shown in the graph of fig. 10b, the supercapacitor output power is maintained at the steady state of 0kW after t=0.4 s, and the battery discharge power is forced to undergo a transient reduction process with a magnitude of 11kW to stabilize the boost converter output voltage, and then gradually returns to the steady state value of 61kW (since the total photovoltaic output in the system is unchanged at the steady state before and after t=0.4 s, only the output distribution of each array is changed, so Ps-8 is not changed).

Based on the simulation, a station-level power reference instruction is further added, the total output power optimization and adjustment effect of the system is verified, related parameters are shown in a table 3, and the other parameters maintain the values shown in the table 1.

Table 3 simulation parameters for System output Power adjustment

As shown in fig. 11a, at steady state of t <0.2s, the total output power of each series DC-DC boost converter in the system is about 780kW, and after receiving the station-level power optimization command p×station=500 kW at time t=0.2 s, each group of hybrid energy storage units responds quickly and shifts to a charging state to absorb the remaining photovoltaic output in the system.

As can be obtained from theoretical calculations, ps-i= -35kW (i=1 to 8) at the new steady state; as shown in fig. 11b, the steady-state output power of the 1 st hybrid energy storage unit is-35 kW (actually, the charging state) after a transient process, and the steady-state is borne by the storage battery.

Preferred example 2:

the technical scheme applied by the patent is a multi-group hybrid energy storage unit coordinated operation control strategy for a series photovoltaic direct current collection system. The scheme is a distributed control strategy which can be independently executed by each hybrid energy storage unit, without losing generality, and the specific technical implementation scheme of the k-th hybrid energy storage unit in the series aggregation system is described below by taking the k-th hybrid energy storage unit as an example.

As shown in fig. 5, the control strategy described in this patent may be implemented by four modules, which are respectively a power reference command calculation module, a command decomposition module, a state of charge management module, and a feedback correction module. The control strategy has the function of generating a real-time power reference instruction through calculation (the control strategy takes any one of a plurality of groups of hybrid energy storage (1-n) as an application object, and is generally described as a k-th group hereinafter) so as to control the operation of an energy storage converter corresponding to a storage battery and a super capacitor in a k-th group of hybrid energy storage units.

The basic functions and signal delivery modes of each module in the control strategy are respectively described in the following I-IV.

I. Power reference instruction calculation module

The power reference instruction calculation module receives different signal quantities through the input ports 1-6, calculates and generates a k group of total output power reference instructions (positive discharge and negative charge) p of the hybrid energy storage unit through an internal logic algorithm ^* _s-k And sends it to the instruction decomposition module.

The corresponding semaphores and their physical meanings for the input ports 1-6 are as follows:

port 1 receives u _k Real-time feedback value for the output port voltage of DC-DC boost converter #k;

port 2 receives

The sum of the output powers of the modified hybrid energy storage units from the 1 st group to the n th group (discharging is positive and charging is negative);

Port 3 receives a set of n-component signals, i.e. p _pv-1 ～p _pv-n Output power of the photovoltaic arrays #1 to #n;

port 4 receives p ^* _station A total output power reference instruction of the pooling system is given for the current station level scheduling;

port 5 receives p _con-flag The station-level output power control enables the flag bit, and is issued by the station-level scheduling through the real-time communication system in the station, and when the station-level scheduling issues the effective power reference instruction p ^* _station When it is set to 1, if the station-level scheduling does not issue the effective power reference instruction p ^* _station Setting it to 0;

port 6 accepts p _con-ena For the station-level output power control enabling FLAG bit, the station-level scheduling is based on the limited FLAG bit uploaded by the charge state management module in the 1 st group to the n-th group hybrid energy storage unit control system _rest-1 ～FLAG _rest-n Is set and issued through the intra-station real-time communication system, and the rules are as follows: when FLAG _rest-1 P at all 0 s _con-ena Set to 1, otherwise p _con-ena Set to 0.

The port 1 signal is received from the DC-DC boost converter #k, and the port 2-6 signals are all received from the in-station real-time communication system.

II, instruction decomposition module

The instruction decomposition module performs p according to the internal filtering algorithm ^* _s-k Real-time decomposition is carried out to generate an original output power reference instruction p of the storage battery in the k group of hybrid energy storage units _batk-ref Reference command p for original output power of super capacitor in k group of hybrid energy storage units _sck-ref And sends both to the state of charge management module.

III State of charge management Module

State of charge managementThe module receives the state of charge SOC of the storage battery in the k-th group of hybrid energy storage cells from the corresponding energy storage device _batk And the super-capacitance state of charge SOC in the k-th hybrid energy storage unit _sck At the same time combine p received by instruction decomposition module _batk-ref And p is as follows _sck-ref The control quantity of the following four control quantities is calculated and generated according to the internal logic rule (1) the output power reference instruction p 'after the storage battery in the k group of hybrid energy storage units is corrected' _batk-ref Transmitting the mixed energy storage current to a kth group of mixed energy storage current transformers; (2) the super capacitor in the k group of hybrid energy storage units outputs a power reference instruction p 'after correction' _sck-ref Transmitting the mixed energy storage current to a kth group of mixed energy storage current transformers; (3) state of charge adjustment power Δp for kth hybrid energy storage unit _s-k Sending to a feedback correction module; (4) group k hybrid energy storage unit limited FLAG bit FLAG _rest-k And transmitted to the station-level controller via the intra-station real-time communication system.

IV feedback correction module

Specifically, the internal logic structure and the working principle of each module are described in the following A-D.

A) Internal structure and working principle of power reference instruction calculation module

1) Module internal structure

As shown in fig. 6, the internal structure of the power reference instruction calculation module includes: a voltage feedback loop, a power feed-forward loop, and an adder; the output ends of the voltage feedback loop, the power feedback loop and the power feedforward loop are respectively connected with the 1 st, 2 nd and 3 rd input ends of the adder, and the corresponding variables are respectively: (1) voltage feedback loop reference component p _s-k-ref (2) Power feedback Loop reference component p' _s-k-ref (3) Power feedforward Loop reference component p' _s-k-ref The method comprises the steps of carrying out a first treatment on the surface of the The output end of the adder is the power referenceThe output ends of the command calculation module, the input ends of the voltage feedback loop, the power feedback loop and the power feedforward loop are the input ends (6 total) of the power reference command calculation module.

I. Voltage feedback loop logic structure

The voltage feedback loop includes: subtractor, dead zone link, PI controller and saturation limiting link; wherein: subtractor positive input end and constant signal source U _n Connected with each other, wherein U _n For the voltage rated value of each DC-DC boost converter output end, the minus input end of the subtracter is connected with the module input end 1, the output end of the subtracter is connected with the dead zone link input end, the dead zone link output end is connected with the input end of the PI controller, the output end of the PI controller is connected with the input end of the saturation limiting link, the output end of the saturation limiting link is the output end of the voltage feedback loop, and the output variable is recorded as p _s-k-ref. The specific interval parameters of the PI controller, the dead zone link and the saturation limiting link can be selected according to engineering experience.

Logic structure of power feedback loop

The power feedback loop includes: the device comprises a signal component accumulator, a first subtracter, a second subtracter, a dead zone link, a PI controller, a saturation limiting link, a first signal channel selection switch S1 and a second signal channel selection switch S2; wherein: the first subtracter negative input end is connected with the module input end 2, the first subtracter positive input end is connected with the output end of the first signal channel selection switch S1, the signal accumulator input end is connected with the module input end 3, the signal accumulator output end is connected with the second subtracter negative input end, the second subtracter positive input end is connected with the module input end 4, the second subtracter output end is connected with the b input end of the first signal channel selection switch S1, the a input end of the first signal channel selection switch S1 is connected with a zero signal source, the first subtracter output end is connected with a dead zone link input end, the dead zone link output end is connected with a PI controller input end, the PI controller output end is connected with a saturation limiting link input end, the saturation limiting link output end is connected with the b input end of the second signal channel selection switch S2, the a input end of the second signal channel selection switch S2 is connected with a zero signal source, and the second signal channel selection switch S1 is connected with a zero signal source The output end of the switch S2 is the output end of the power feedback loop, and the output variable is recorded as p' _s-k-ref The control end of the first signal channel selection switch S1 is connected with the module input end 5, and the control end of the second signal channel selection switch S2 is connected with the module input end 6. The action logic of the first signal channel selection switch S1 and the second signal channel selection switch S2 is: when the control end variable is 0, connecting the signal quantity of the input end a to the output end; otherwise, the b input semaphore is connected to the output.

. The specific interval parameters of the PI controller, the dead zone link and the saturation limiting link can be selected according to engineering experience.

III, power feedforward loop logic structure

The power feed forward loop includes: a feedforward instruction calculation unit; wherein: a first input terminal of the feedforward instruction calculation unit is connected with the module input terminal 4 to collect the signal quantity p ^* _station A second input of the feedforward command computation unit is connected to the module input 3 to collect a set of semaphores p _pv-1 ～p _pv-n The output end of the feedforward instruction calculating unit is the output end of the power feedforward loop, and the output variable is recorded as p' _s-k-ref.

2) Principle of operation

I. Principle of operation of a voltage feedback loop

The loop collects and compares the output end voltage u of the DC-DC boost converter #k in real time through the input end _k With the rated value U _n PI control is performed according to the deviation value to form a corresponding reference power component p _s-k-ref The dead zone link is introduced for reducing the frequent action of the hybrid energy storage caused by the small-amplitude disturbance signal, and the saturation limiting link is introduced for ensuring the output component in a proper range.

II, working principle of power feedback loop

The loop compares the corrected total output power of the 1 st group to the n th group of hybrid energy storage units in the whole serial collecting system in real time

Is in steady state with theory under the current working conditionReference value, PI control is performed based on the power deviation value to generate corresponding reference power component p' _s-k-ref And outputs the component to the corresponding input of the module adder under the condition that the system has active power control capability.

The differential working conditions of two layers must be considered in the operation of the loop: (1) whether the station-level dispatching system issues an effective total output power reference instruction p of the collecting system or not ^* _station (2) whether the current collection system has the capability of controlling the total output power by means of a plurality of groups of hybrid energy storage units.

If there is an effective p ^* _station Signal (i.e. p _con-flag =1), the power reference value applied to the positive input of the first subtractor of the loop should be

Otherwise (i.e. p _con-flag =0) to avoid power circulation between the sets of hybrid energy storage cells, the power reference value applied to the positive input of the first subtractor of the loop should be set to zero. This function is achieved by the first signal path selection switch S1.

If the 1 st to nth hybrid energy storage units in the system have power response capability (i.e., p _con-ena =1), the total output power of the system has a degree of freedom of adjustment, and the signal at the output end of the saturation limiting link in the loop can be directly used as the loop output p' _s-k-ref The method comprises the steps of carrying out a first treatment on the surface of the If any of the 1 st to nth hybrid energy storage cells cannot respond in power due to state of charge (i.e., p _con-ena =0), the total output power of the system cannot be further adjusted under the control objective of maintaining the output power balance of each DC-DC boost converter, at which time the loop output p 'should be taken' _s-k-ref And (5) setting zero. This function is achieved by the second signal path selection switch S2.

Specifically, the two signal channel selection switches S1 and S2 in the loop respectively operate in the following modes:

for S1, when p _con-flag When the signal is 0, the signal of the input end a is connected to the output end; when p is _con-flag When the signal is 1, the signal of the input end b is connected to the output end;

for S2, when p _con-ena When the signal is 0, the signal of the input end a is connected to the output end; when p is _con-ena When 1, the signal of the input terminal b is connected to the output terminal.

III, working principle of power feedforward loop

In order to improve the dynamic response of the system, a power feedforward loop is arranged in the module, which is characterized in that the feedforward instruction calculation unit can be used for calculating the real-time input signal p _pv-1 ～p _pv-n And p is as follows ^* _station Calculating the steady-state output power theoretical value of the kth group of hybrid energy storage and taking the steady-state output power theoretical value as a loop output component p' _s-k-ref The corresponding inputs of the module adder are fed.

Specifically, the power feed-forward loop reference component p' _s-k-ref The calculation rule of (2) is as follows

When p is _con-ena When=1:

if p _con-flag With the number of =0

If p _con-flag With =1 then

Wherein p is _pv-k The output power of the photovoltaic array #k; p is p ^* _station And giving a total output power reference instruction of the pooling system for the current station-level scheduling.

When p is _con-ena When=0

MeaningThe limited FLAG bit FLAG uploaded by the hybrid energy storage unit controllers from the 1 st group to the n th group is set _rest-1 ～FLAG _rest-n At least 1 of the mixed energy storage unit numbers are 1, and the mixed energy storage unit numbers with all the limited zone bits being 1 are recorded as a set M, namely

M＝{i|FLAG _rest-i ＝1} (3)

At this time, for the hybrid energy storage unit with power response capability, the power feedforward loop reference component p' thereof " _s-k-ref Can be expressed as

represents the kth group (i.e.)>

) Power feed-forward loop reference component p' of hybrid energy storage unit " _s-k-ref ；p _pv-j The output power of the photovoltaic array #j corresponding to the j-th group (i.e. j epsilon M) of hybrid energy storage units without power response capability; m is the number of elements in the set M.

B) Instruction decomposition module internal structure and working principle

1) Module internal structure

As shown in fig. 7, the internal structure of the instruction decomposition module includes: the input end of the Butterworth low-pass filter is the input end of the instruction decomposition module, the output end of the Butterworth low-pass filter is the first output end of the instruction decomposition module, and the output variable is the original output power reference instruction p of the storage battery in the k group of hybrid energy storage units _batk-ref The positive input end of the subtracter is connected with the input end of the Butterworth low-pass filter, the negative input end of the subtracter is connected with the output end of the Butterworth low-pass filter, the output end of the subtracter is a second output end of the instruction decomposition module, and the output variable is a k group of hybrid energy storage single unitsOriginal output power reference command p of super capacitor in element _sck-ref The order and the frequency band parameters of the Butterworth low-pass filter can be selected according to engineering experience.

2) Principle of operation

Reference command p based on total output power of k-th hybrid energy storage unit ^* _s-k Extracting low-frequency components of the low-frequency components by using a Butterworth low-pass filter as an original output power reference instruction p of a storage battery in a kth group of hybrid energy storage units _batk-ref Meanwhile, the rest medium-high frequency components are used as the reference instruction p of the original output power of the super capacitor in the kth group of hybrid energy storage units _sck-ref .

C) Logic principle of charge state management module

The module aims to establish a state of charge (SOC, the same applies below) management policy that matches the policy application scenario with the dual target control characteristics. In this patent, the SOC dividing manner of the energy storage device shown in fig. 8 is adopted, and the SOC dividing manner is specifically divided into an optimal Zone (Zone 1), a normal Zone (Zone 2), an overcharge Zone (Zone 3) and an overdischarge Zone (Zone 4) according to the SOC value of the energy storage device, so that SOC management optimization control is completed in this module based on the SOC value. SOC shown in FIG. 8 _max For the upper limit of the normal charge state interval of the energy storage device, SOC _min For the lower limit of the normal charge state interval of the energy storage device, SOC _op-max For the upper limit of the optimal charge state interval of the energy storage device, SOC _op-min The lower limit of the optimal state of charge interval of the energy storage device can be selected according to actual engineering requirements and combined with experience.

The specific implementation of the module function is divided into three logic steps, which are respectively briefly described as follows:

1) Logic step one: energy storage device operation mode determination

In the step, the running states of the storage battery and the super capacitor in the k group of hybrid energy storage units are respectively judged. For any energy storage device (storage battery or super capacitor), the running state of the energy storage device can be divided into three modes, namely mode I, mode II and mode III.

I. Battery operation mode determination

For the accumulator, according to the charge stateSOC _batk With the original power reference instruction p _batk-ref The operation mode is determined, and the logic rule is as follows.

1) When any one of the following conditions (1) to (4) is satisfied, it is determined as the modality I

①SOC _batk ∈Zone 1；

②p _batk-ref >0&SOC _batk ∈Zone 3；

③p _batk-ref <0&SOC _batk ∈Zone 4；

④p _batk-ref ≠0&SOC _batk ∈Zone 2；

SOC _batk the state of charge of the storage battery in the k group of hybrid energy storage units;

2) When any one of the following conditions (1) to (2) is satisfied, it is determined as mode II

①p _batk-ref <0&SOC _batk ∈Zone 3；

②p _batk-ref >0&SOC _batk ∈Zone 4；

3) When the following condition is satisfied, it is determined as mode III

II, judging operation mode of super capacitor

For super-capacitors, the SOC is based on their state of charge _sck With the original power reference instruction p _sck-ref And judging the operation mode of the battery, wherein the logic rule is the same as that of the battery, as follows.

①SOC _sck ∈Zone 1；

②p _sck-ref >0&SOC _sck ∈Zone 3；

③p _sck-ref <0&SOC _sck ∈Zone 4；

④p _sck-ref ≠0&SOC _sck ∈Zone 2；

①p _sck-ref <0&SOC _sck ∈Zone 3；

②p _sck-ref >0&SOC _sck ∈Zone 4；

3) When the following condition is satisfied, it is determined as mode III

2) Logic step two: power reference command correction

In the step, according to the operation state combination of the storage battery and the super capacitor in the k group of hybrid energy storage units, the original power reference instruction is respectively corrected so as to keep the safe and stable operation of the system and maintain a good SOC interval. For the two energy storage devices, there may be 3*3 =9 cases (denoted as case 1 to case 9) in which the modes are combined with each other, and the specific logic thereof is as follows.

Further definition of p herein _batk-res Power is regulated for SOC recovery of the storage battery; p is p _sck-res Adjusting power for SOC recovery of the super capacitor; Δp _sk-sc The absolute value of the charge and discharge power when the super capacitor is subjected to SOC recovery adjustment is a positive variable parameter; Δp _sk-bat The absolute value of the charge and discharge power when the storage battery is subjected to SOC recovery adjustment is a positive variable parameter.

Case 1: the storage battery is in a mode I, and the super capacitor is in a mode I

At this time, the storage battery and the super capacitor can normally follow respective power reference instructions without additional correction, namely:

p' _batk-ref is the k groupThe storage battery in the hybrid energy storage unit outputs a power reference instruction after correction;

p _batk-ref for the original output power reference instruction of the storage battery in the k group of hybrid energy storage units

p' _sck-ref Outputting power reference fingers after correcting the super capacitor in the k group of hybrid energy storage units;

p _sck-ref the method comprises the steps that a reference instruction of power is originally output for a super capacitor in a k group of hybrid energy storage units;

p _batk-res power is regulated for SOC recovery of the storage battery;

p _sck-res adjusting power for SOC recovery of the super capacitor;

case 2: the storage battery is in a mode I, and the super capacitor is in a mode II

At this time, the super capacitor cannot execute the power regulation task, in order to ensure the power balance control and the output optimization effect as much as possible, the power reference instruction component born by the super capacitor is transferred to the storage battery for execution, namely, the following correction is performed:

p ^* _s-k A reference instruction for the total output power of the k-th group of hybrid energy storage units;

case 3: the storage battery is in a mode I, and the super capacitor is in a mode III

At this time, the supercapacitor has a condition for executing the SOC optimization operation, and the following correction can be executed:

wherein p is _sck-res The specific expression is as follows:

Δp _sk-sc the absolute value of the charge and discharge power of the super capacitor is a positive variable parameter when the super capacitor is subjected to SOC recovery adjustment

SOC _sck The super-capacitor charge state in the k-th group of hybrid energy storage units;

SoC _op-min representing the lower limit of the optimal state of charge interval of the energy storage device;

SoC _op-max representing the upper limit of the optimal state of charge interval of the energy storage device;

case 4: the storage battery is in a mode II, and the super capacitor is in a mode I

At this time, the storage battery cannot execute the power regulation task, because the super capacitor belongs to the power type energy storage device, the capacity of the super capacitor is relatively small, and the power regulation function is difficult to independently maintain for a long time, so that in order to ensure the safety of equipment, the k-th group of hybrid energy storage is wholly withdrawn from operation at this time, namely, the following correction is performed:

case 5: the storage battery is in a mode II, and the super capacitor is in a mode II

At this time, the storage battery and the super capacitor cannot execute the power regulation task, so that the k-th group of hybrid energy storage is integrally taken out of operation, and the corresponding correction is shown in the same formula (9).

Case 6: the storage battery is in a mode II, and the super capacitor is in a mode III

At this time, the storage battery cannot execute the power regulation task, the kth group of hybrid energy storage does not bear the power regulation task either, but the super capacitor can execute the condition of the SOC optimization action to execute the following correction:

wherein p is _sck-res The specific expression is as in formula (8).

Case 7: the storage battery is in a mode III, and the super capacitor is in a mode I

At this time, the storage battery has the condition of executing the SOC optimization action, and the super capacitor can normally follow the power reference command, so that the following correction can be executed:

wherein p is _batk-res The specific expression is as follows:

Δp _sk-bat the absolute value of the charge/discharge power when the battery is subjected to SOC recovery adjustment is a positive variable parameter.

Case 8: the storage battery is in a mode III, and the super capacitor is in a mode II

At this time, the super capacitor cannot execute the power regulation task, in order to ensure the power balance control and the output optimization effect as much as possible, the power reference instruction component born by the super capacitor is transferred to the storage battery for execution, and the storage battery does not execute the SOC optimization action, and the correction mode is as in the formula (6).

Case 9: the storage battery is in a mode III, and the super capacitor is in a mode III

At this time, both the storage battery and the super capacitor have conditions for performing the SOC optimization operation, and the following correction can be performed:

Wherein p is _batk-res And p is as follows _sck-res The expressions of (2) are shown in the expression (12) and the expression (8), respectively.

2) Logic step three: related control parameter calculation generation

As shown by the overall control logic in FIG. 5, the state of charge management module needs to generate control while correcting the power reference commandParameter FLAG _rest-k And Δp _s-k The specific mode is as follows:

FLAG _rest-k generating rules

Generating according to the 9 combination conditions of the working states of the storage battery and the super capacitor, and when the storage battery is in any one of the

conditions

4, 5 and 6, generating a FLAG _rest-k Set to 1, otherwise FLAG is set _rest-k Set to 0.FLAG _rest-k For the k group of the mixed energy storage unit limited flag bits, the variable is uploaded to a station level controller through an in-station real-time communication system after being generated, and is used for generating a station level output power control enabling flag bit p _con-ena Specific generation rules are as described above.

Δp _s-k Generating rules

Δp _s-k Generated according to the following formula:

Δp _s-k ＝p _batk-res +p _sck-res (14)

D) Feedback correction module

In order to offset the disturbance of the charge and discharge power to the global steady state of the system under the SOC adjustment action of the energy storage device to a certain extent, and prevent oscillation, the feedback value of the total output power of the k-th group of hybrid energy storage units is corrected as follows

p′ _s-k ＝p _s-k -Δp _s-k (15)

p _s-k The total output power of the k-th hybrid energy storage unit;

In the description of the present application, it should be understood that the terms "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," "outer," and the like indicate orientations or positional relationships based on the orientations or positional relationships illustrated in the drawings, merely to facilitate description of the present application and simplify the description, and do not indicate or imply that the devices or elements being referred to must have a specific orientation, be configured and operated in a specific orientation, and are not to be construed as limiting the present application.

Those skilled in the art will appreciate that the systems, apparatus, and their respective modules provided herein may be implemented entirely by logic programming of method steps such that the systems, apparatus, and their respective modules are implemented as logic gates, switches, application specific integrated circuits, programmable logic controllers, embedded microcontrollers, etc., in addition to the systems, apparatus, and their respective modules being implemented as pure computer readable program code. Therefore, the system, the apparatus, and the respective modules thereof provided by the present invention may be regarded as one hardware component, and the modules included therein for implementing various programs may also be regarded as structures within the hardware component; modules for implementing various functions may also be regarded as being either software programs for implementing the methods or structures within hardware components.

The foregoing describes specific embodiments of the present invention. It is to be understood that the invention is not limited to the particular embodiments described above, and that various changes or modifications may be made by those skilled in the art within the scope of the appended claims without affecting the spirit of the invention. The embodiments of the present application and features in the embodiments may be combined with each other arbitrarily without conflict.

Claims

1. An energy storage control system for a series photovoltaic direct current collection system, comprising:

the power reference instruction calculation module receives different signal quantities through an input port, and specifically comprises the following steps: port 1 receives u _k Real-time feedback value for the output port voltage of DC-DC boost converter #k; port 2 receives

The sum of the output powers of the modified hybrid energy storage units from the 1 st group to the n th group (discharging is positive and charging is negative); port 3 receives a set of n-component signals, i.e. p _pv-1 ～p _pv-n Photovoltaic arrays #1 to photovoltaic respectivelyThe output power of array #n; port 4 receives p ^* _station A total output power reference instruction of the pooling system is given for the current station level scheduling; port 5 receives p _con-flag The station-level output power control enables the flag bit, and is issued by the station-level scheduling through the real-time communication system in the station, and when the station-level scheduling issues the effective power reference instruction p ^* _station When it is set to 1, if the station-level scheduling does not issue the effective power reference instruction p ^* _station Setting it to 0; port 6 accepts p _con-ena For the station-level output power control enabling FLAG bit, the station-level scheduling is based on the limited FLAG bit uploaded by the charge state management module in the 1 st group to the n-th group hybrid energy storage unit control system _rest-1 ～FLAG _rest-n Is set and issued through the intra-station real-time communication system, and the rules are as follows: when FLAG _rest-1 P at all 0 s _con-ena Set to 1, otherwise p _con-ena Set to 0, calculate and generate the k group of hybrid energy storage unit total output power reference instruction p through internal logic algorithm ^* _s-k And sends the instruction to the instruction decomposition module;

the state of charge management module receives the state of charge SOC of the storage battery in the kth group of hybrid energy storage cells from the respective energy storage devices _batk And the super-capacitance state of charge SOC in the k-th hybrid energy storage unit _sck At the same time combine p received from instruction decomposition module _batk-ref And p is as follows _sck-ref Generating the total state of charge adjustment power of the k group of hybrid energy storage units, and sending the total state of charge adjustment power to a feedback correction module;

The feedback correction module receives the output power p of the k group of hybrid energy storage units from the corresponding energy storage converter of the output power of the k group of hybrid energy storage units _s-k In combination with a kth hybrid store received by the state of charge management moduleEnergy unit total state of charge regulated power Δp _s-k Generating the output power p 'of the k-th group of modified hybrid energy storage units in real time according to an internal logic algorithm' _s-k And upload it to the in-station real-time communication system.

2. The energy storage control system for a series-oriented photovoltaic direct current collection system of claim 1, wherein the power reference command calculation module comprises: a voltage feedback loop, a power feed-forward loop, and an adder;

3. The energy storage control system for a series-oriented photovoltaic direct current collection system of claim 2 wherein the voltage feedback loop comprises: the device comprises a subtracter, a dead zone link, a PI controller and a saturation limiting link;

4. The energy storage control system for a series-oriented photovoltaic direct current collection system of claim 2 wherein the power feedback loop comprises: the device comprises a signal component accumulator, a first subtracter, a second subtracter, a dead zone link, a PI controller, a saturation limiting link, a first signal channel selection switch S1 and a second signal channel selection switch S2;

The first subtracter negative input end is connected with the input end 2 of the power reference instruction calculation module, the first subtracter positive input end is connected with the output end of the first signal channel selection switch S1, the input end of the signal component accumulator is connected with the input end 3 of the power reference instruction calculation module, the output end of the signal accumulator is connected with the second subtracter negative input end, the second subtracter positive input end is connected with the input end 4 of the power reference instruction calculation module, the second subtracter output end is connected with the b input end of the first signal channel selection switch S1, the a input end of the first signal channel selection switch S1 is connected with a zero signal source, the first subtracter output end is connected with the dead zone link input end, the dead zone link output end is connected with the input end of the PI controller, the output end of the PI controller is connected with the saturation limiting link input end, the output end of the saturation limiting link is connected with the b input end of the second signal channel selection switch S2, the a input end of the second signal channel selection switch S2 is connected with the zero signal source, the output end of the second signal channel selection switch S2 is the output end of the power feedback loop, and the output variable thereof is p%' _s-k-ref The control end of the first signal channel selection switch S1 is connected with the input end 5 of the power reference instruction calculation module, and the control end of the second signal channel selection switch S2 is connected with the input end 6 of the power reference instruction calculation module;

The action logic of the first signal channel selection switch S1 and the second signal channel selection switch S2 is: when the control end variable is 0, connecting the signal quantity of the input end a to the output end; otherwise, connecting the b input end semaphore to the output end;

5. The energy storage control system for a series-oriented photovoltaic direct current collection system of claim 2 wherein the power feed forward loop comprises: a feedforward instruction calculation unit;

6. The energy storage control system for a series photovoltaic direct current collection system according to claim 1, wherein the internal structure of the instruction decomposition module comprises: butterworth low-pass filter, subtracter;

the input end of the Butterworth low-pass filter is the input end of the instruction decomposition module, the output end of the Butterworth low-pass filter is the first output end of the instruction decomposition module, and the output variable is the original output power reference instruction p of the storage battery in the k group of hybrid energy storage units _batk-ref The positive input end of the subtracter is connected with the input end of the Butterworth low-pass filter, the negative input end of the subtracter is connected with the output end of the Butterworth low-pass filter, the output end of the subtracter is a second output end of the instruction decomposition module, and the output variable is the reference instruction p of the original output power of the super capacitor in the k group of hybrid energy storage units _sck-ref ；

7. The series-oriented photovoltaic direct current collection system energy storage control system of claim 1 wherein the state of charge management module comprises:

a power reference instruction correction module: according to the storage battery and the storage battery in the k-th hybrid energy storage unitThe operation state combination of the super capacitor respectively corrects the original power reference command, and the state of charge management module needs to generate a control parameter FLAG while correcting the power reference command _rest-k And Δp _s-k ，FLAG _rest-k FLAG for the k-th group of hybrid energy storage unit limited FLAG bits _rest-k After the generation, uploading the generated data to a station-level controller through an intra-station real-time communication system;

Δp _s-k generated according to the following formula:

Δp _s-k ＝p _batk-res +p _sck-res

8. The energy storage control system for a series photovoltaic direct current collection system of claim 7 wherein the feedback correction module:

p' _s-k ＝p _s-k -Δp _s-k

p _s-k the total output power of the k-th hybrid energy storage unit;