CN110752603B - Compound control method of series inverter, storage medium and equipment - Google Patents
Compound control method of series inverter, storage medium and equipment Download PDFInfo
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- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02J—CIRCUIT ARRANGEMENTS OR SYSTEMS FOR SUPPLYING OR DISTRIBUTING ELECTRIC POWER; SYSTEMS FOR STORING ELECTRIC ENERGY
- H02J3/00—Circuit arrangements for ac mains or ac distribution networks
- H02J3/01—Arrangements for reducing harmonics or ripples
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- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02J—CIRCUIT ARRANGEMENTS OR SYSTEMS FOR SUPPLYING OR DISTRIBUTING ELECTRIC POWER; SYSTEMS FOR STORING ELECTRIC ENERGY
- H02J3/00—Circuit arrangements for ac mains or ac distribution networks
- H02J3/12—Circuit arrangements for ac mains or ac distribution networks for adjusting voltage in ac networks by changing a characteristic of the network load
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- Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
- Y02E40/00—Technologies for an efficient electrical power generation, transmission or distribution
- Y02E40/40—Arrangements for reducing harmonics
Abstract
The invention discloses a compound control method, a storage medium and equipment of a series inverter, which comprise the following steps: acquiring load voltage, filter capacitor voltage and inductance current; converting a coordinate system of the load voltage, the filter capacitor voltage and the inductive current to obtain a feedback value of the load voltage, a feedback value of the filter capacitor voltage and a feedback value of the inductive current; performing load voltage outer loop control calculation according to the difference value between the rated load voltage and the load voltage feedback value to obtain a given value of the inductive current inner loop control; performing inductive current inner loop control calculation according to the difference value of the inductive current inner loop control given value and the inductive current feedback value to obtain a filter capacitor voltage inner loop control given value; performing voltage inner loop control calculation according to the difference value of the given value of the filter capacitor voltage inner loop control and the filter capacitor voltage feedback value to obtain compensation voltage; and outputting the compensation voltage as a control signal. By implementing the invention, the compensation of the voltage balance and unbalance drop of the power grid is realized.
Description
Technical Field
The invention relates to the technical field of power electronics, in particular to a compound control method, a storage medium and equipment for series inverters.
Background
With the rapid development of scientific technology, sensitive loads such as high-precision processing and data centers and the like put higher requirements on the power quality of a power grid, and meanwhile, the capacity of a large number of impact and nonlinear power loads is increased, so that the power quality problem of the modern power grid is increasingly prominent.
The existing electric energy quality system improves the voltage fluctuation problems of sudden rise, sudden drop, flicker, harmonic wave and the like of the power grid voltage by series voltage compensation. In an electric energy quality system, a series inverter is generally used as a power grid voltage compensation device, and is generally connected in series between a power grid and an electric load, and the output voltage of the series inverter is superposed with the power grid voltage to ensure the stability of the power supply voltage of the electric load.
However, the randomness of the grid voltage fluctuations, as well as the sensitivity of the electrical load to the grid voltage, require that the series inverter have good dynamic response capabilities. Meanwhile, due to the diversity of the electrical loads, the inductive current often contains certain harmonic waves. The load voltage control method adopted in the prior art can not effectively inhibit the influence of harmonic current on the compensation performance of the system, and even can increase the effect of the harmonic current on the compensation voltage of the system. While the traditional PI control can dynamically track the sudden change of the grid voltage, the capacity of compensating the negative sequence voltage caused by unbalanced fluctuation and the periodic voltage fluctuation caused by nonlinear load is lacked.
Disclosure of Invention
In view of this, embodiments of the present invention provide a composite control method, a storage medium, and a device for a series inverter, so as to solve the technical problems of slow dynamic response speed and poor compensation performance of a load voltage loop control method in the prior art.
The technical scheme provided by the invention is as follows:
a first aspect of an embodiment of the present invention provides a compound control method for a series inverter, where the compound control method includes: acquiring load voltage, filter capacitor voltage and inductance current; transforming the load voltage, the filter capacitor voltage and the inductive current by a coordinate system to obtain a feedback value of the load voltage, a feedback value of the filter capacitor voltage and a feedback value of the inductive current; performing load voltage outer loop control calculation according to the difference value between the rated load voltage and the load voltage feedback value to obtain a given value of inductive current inner loop control; performing inductive current inner loop control calculation according to the difference value between the given value of the inductive current inner loop control and the inductive current feedback value to obtain the given value of the filter capacitor voltage inner loop control; performing voltage inner loop control calculation according to the difference value between the given value of the filter capacitor voltage inner loop control and the filter capacitor voltage feedback value to obtain the compensation voltage of the series inverter; and outputting the compensation voltage of the series inverter as a control signal of the series inverter.
Optionally, performing load voltage outer loop control calculation according to a difference between the rated load voltage and the load voltage feedback value to obtain a given value of the inductive current inner loop control, including: inputting a voltage outer ring controller for calculation according to the difference value of the rated load voltage and the load voltage feedback value to obtain a load voltage outer ring control output value; and calculating according to the load voltage outer ring control output value, the rated load voltage and the load voltage feedback value to obtain the set value controlled by the inductance current inner ring.
Optionally, calculating according to the load voltage outer loop control output value, the rated load voltage, and the load voltage feedback value to obtain the given value of the inductive current inner loop control, including: carrying out proportional operation according to the difference value between the rated load voltage and the load voltage feedback value to obtain a feedforward value of the first load voltage; and performing superposition operation on the feedforward value of the first load voltage and the load voltage outer ring control output value to obtain the set value of the inductive current inner ring control.
Optionally, the calculating of the inductance current inner loop control is performed according to a difference between the given value of the inductance current inner loop control and the inductance current feedback value, so as to obtain the given value of the filter capacitor voltage inner loop control, and the calculating of the inductance current inner loop control includes: and inputting the difference value of the given value of the inductive current inner loop control and the inductive current feedback value into an inductive current inner loop controller for calculation to obtain the given value of the filter capacitor voltage inner loop control.
Optionally, performing voltage inner loop control calculation according to a difference between the given value of the filter capacitor voltage inner loop control and the filter capacitor voltage feedback value to obtain the compensation voltage of the series inverter, including: inputting a difference value of the given value of the voltage inner loop control of the filter capacitor and the voltage feedback value of the filter capacitor into a voltage inner loop controller for calculation to obtain a voltage inner loop control output value of the filter capacitor; and calculating according to the filter capacitor voltage inner loop control output value, the rated load voltage and the load voltage feedback value to obtain the compensation voltage of the series inverter.
Optionally, calculating according to the filter capacitor voltage inner loop control output value, the rated load voltage, and the load voltage feedback value to obtain the compensation voltage of the series inverter, including: carrying out proportional operation according to the difference value between the rated load voltage and the load voltage feedback value to obtain a feedforward value of a second load voltage; and performing superposition operation on the feedforward value of the second load voltage and the voltage inner loop control output value of the filter capacitor to obtain the compensation voltage of the series inverter.
Optionally, when the transformed coordinate system is a two-phase stationary coordinate system, the controller comprises a resonance controller and a repetitive controller.
Optionally, outputting the compensation voltage as a control signal of the series inverter includes: and converting the compensation voltage by a coordinate system to obtain a control signal of the series inverter for outputting.
A second aspect of the embodiments of the present invention provides a computer-readable storage medium, which stores computer instructions for causing a computer to execute a composite control method for a series inverter according to any one of the first aspect and the first aspect of the embodiments of the present invention.
A third aspect of embodiments of the present invention provides a compound control apparatus for a series inverter, including: the control method comprises a memory and a processor, wherein the memory and the processor are connected in communication with each other, the memory stores computer instructions, and the processor executes the computer instructions so as to execute the composite control method for the series inverters according to any one of the first aspect and the first aspect of the embodiments of the present invention.
The technical scheme provided by the invention has the following effects:
according to the composite control method, the storage medium and the equipment for the series inverter provided by the embodiment of the invention, the obtained data is subjected to three closed loop control calculation of the voltage outer loop, the current inner loop and the voltage inner loop, wherein the dynamic tracking of the load voltage can be realized in the control calculation process of the voltage outer loop, the dynamic response speed of the series inverter can be improved in the control calculation process of the current inner loop, and the influence of harmonic current on the compensation performance of a system can be effectively inhibited in the control calculation process of the voltage inner loop. After the multi-closed-loop control calculation, the calculated compensation voltage can be used as a control signal of the series inverter, the composite closed-loop control calculation of the series inverter can eliminate the influence of the fluctuation of the inductive current on the control, inhibit the periodic fluctuation of the load power supply voltage, realize the compensation of the balance and unbalance drop of the power grid voltage, and solve the technical problem that the existing control method cannot inhibit the influence of the harmonic current on the compensation performance of the system.
Drawings
In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the embodiments or the prior art will be briefly described below, and it is obvious that the drawings in the following description are some embodiments of the present invention, and other drawings can be obtained by those skilled in the art without creative efforts.
Fig. 1 is a control block diagram of a compound control method of a series inverter according to an embodiment of the present invention;
fig. 2 is a flowchart of a compound control method of a series inverter according to an embodiment of the present invention;
fig. 3 is a flowchart of a compound control method of a series inverter according to another embodiment of the present invention;
fig. 4 is a flowchart of a compound control method of a series inverter according to another embodiment of the present invention;
fig. 5 is a flowchart of a compound control method of a series inverter according to another embodiment of the present invention;
fig. 6 is a diagram of a test verification structure of a compound control method of a series inverter according to an embodiment of the present invention;
fig. 7 is a diagram of a test verification structure of a compound control method of a series inverter according to another embodiment of the present invention;
fig. 8 is a schematic diagram of a hardware structure of the series inverter compound control device according to the embodiment of the present invention.
Detailed Description
In order to make the objects, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are some, but not all, embodiments of the present invention. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.
The embodiment of the invention provides a compound control method of a series inverter, and a control block diagram of the compound control method is shown in fig. 1. As shown in fig. 2, the compound control method includes the steps of:
step S101: acquiring load voltage, filter capacitor voltage and inductance current; wherein the load voltage can be uLkWhere (k) is a, b, c, the filter capacitor voltage may be represented by uCkWhere (k) is a, b, c, the inductor current may be represented by iLkAnd (k ═ a, b, and c).
Step S102: converting a coordinate system of the load voltage, the filter capacitor voltage and the inductive current to obtain a load voltage feedback value, a filter capacitor voltage feedback value and an inductive current feedback value; specifically, the acquired filter capacitor voltage, load voltage and inductor current are usually variables of a three-phase stationary coordinate system, and coordinate system transformation may be adopted to transform the variables of the three-phase stationary coordinate system to another coordinate system, for example, to a synchronous rotating coordinate system or a two-phase stationary coordinate system, which is not limited in this disclosure.
When the voltage of the three-phase stationary coordinate system is converted into the synchronous rotating coordinate system, the following steps can be performed by using the following formulas (1) to (3):
wherein u isLd,uLqRepresenting the load voltage feedback value, uCd,uCqRepresenting the filter capacitor voltage feedback value, iLd,iLqRepresenting the inductor current feedback value.
When converting the voltage of the three-phase stationary coordinate system to the two-phase stationary coordinate system, equations (4) to (6) may be used:
wherein u isLα,uLβRepresenting the load voltage feedback value, uCα,uCβRepresenting the filter capacitor voltage feedback value, iLα,iLβRepresenting the inductor current feedback value.
Step S103: performing outer loop control calculation according to the difference value between the rated load voltage and the load voltage feedback value to obtain a given value of current inner loop control; in particular, the rated load voltage of the power grid system can be obtained
Rated load voltage
And a load voltage feedback value uLd,uLqMaking a difference, and comparing the difference value of the two
Performing outer loop control calculation to obtain the given value of the inner loop control of the inductive current
Step S104: according to the difference between the given value controlled by the inductance current inner loop and the inductance current feedback valueCarrying out current inner loop control calculation on the value to obtain a given value of filter capacitor voltage inner loop control; specifically, the given value of the inductor current inner loop control calculated in step S103 may be set
And the inductor current feedback value iid,iiqMaking a difference, and comparing the difference value of the two
Performing current inner loop control calculation to obtain the given value of the filter capacitor voltage inner loop control
Step S105: performing voltage inner loop control calculation according to the difference value of the given value of the filter capacitor voltage inner loop control and the filter capacitor voltage feedback value to obtain the compensation voltage of the series inverter; specifically, the given value of the filter capacitor voltage inner loop control calculated in step S104 may be set
And filter capacitor voltage feedback value uCd,uCqMaking a difference, and comparing the difference value of the two
Performing voltage inner loop control calculation to obtain compensation voltage of series inverter
Step S106: will compensate the voltage
And converting variables of the synchronous rotating coordinate system into a three-phase static coordinate system by adopting coordinate system inverse transformation, and outputting the three-phase static coordinate system as a control signal of the series inverter. Specifically, after the compensation voltage of the series inverter is calculated, the compensation voltage may be used as the control of the series inverterThe signal is output. When the series inverter is used as a power grid voltage compensation device, the compensation voltage can be superposed with the power grid voltage, so that the power supply voltage stability of the power load is ensured.
According to the composite control method of the series inverter provided by the embodiment of the invention, the obtained variables are subjected to three closed-loop control calculation of the load voltage outer ring, the inductive current inner ring and the filter capacitor voltage. The voltage outer loop control calculation process can realize dynamic tracking of load voltage, the current inner loop control calculation process can improve the dynamic response speed of the series inverter, and the voltage inner loop control calculation process can effectively inhibit the influence of harmonic current on the compensation performance of the system. After the multi-closed-loop control calculation, the calculated compensation voltage can be used as a control signal of the series inverter, the composite closed-loop control calculation of the series inverter can eliminate the influence of the fluctuation of the inductive current on the control, inhibit the periodic fluctuation of the load power supply voltage, realize the compensation of the balance and unbalance drop of the power grid voltage, and solve the technical problem that the existing control method cannot inhibit the influence of the harmonic current on the compensation performance of the system.
As an optional implementation manner of the embodiment of the present invention, as shown in fig. 1 and 3, step S103 performs load voltage outer loop control calculation according to a difference between a rated load voltage and a load voltage feedback value to obtain a given value of inductance current inner loop control, including the following steps:
step S201: according to rated load voltage
And a load voltage feedback value uLd,uLqDifferential input voltage outer loop controller GL(s) calculating to obtain the load voltage outer ring control output value und,unq(n ═ 1,2, 3); specifically, the difference between the rated load voltage and the feedback value of the load voltage may be respectively input to the plurality of controllers for calculation, so as to obtain a plurality of voltage outer loop control output values und,unq(n ═ 1,2,3), wherein the plurality of controllers can be any two or more of PI controllers, resonance controllers, repetitive controllersThe present invention is not limited thereto.
Among the controllers, the PI controller can form a control deviation according to the difference value, forms a control quantity through a proportional link and an integral link, can be used for dynamic tracking of load voltage, has strong dynamic regulation capacity, and can quickly respond to balance drop of the power grid voltage; the resonance controller can be used for rapidly compensating the unbalanced drop of the power grid voltage and the periodic voltage fluctuation of a specific time; the repetitive controller is based on an internal model principle, describes the characteristics of external signals of the system through an internal model, eliminates the static error existing during the tracking of periodic signals and enables the repetitive controller to have good instruction tracking characteristics. Therefore, the repetitive controller is added in the outer loop control calculation process, the periodic fluctuation of the load voltage caused by the power grid voltage and the nonlinear load can be effectively inhibited, the static error of the load voltage is compensated, the harmonic voltage caused by the nonlinear load is eliminated, and the tracking precision of the series inverter is improved.
Under a synchronous rotating coordinate system, the difference value of the rated load voltage and the feedback value of the load voltage can be respectively input into a PI controller, a resonance controller and a repetitive controller for calculation; in the specific calculation process, the transfer function of the PI controller is
Wherein k ispAnd kiIs an integral control coefficient, and s is a complex frequency domain operator; the transfer function of the resonant controller is
Wherein k isrFor the resonance control coefficient, s is the complex frequency domain operator, omegacIs the angular frequency, omega, of the load voltage0An angular frequency associated with a high gain bandwidth; the transfer function of the repetitive controller is
Wherein k isrIs the resonance control coefficient, s is the complex frequency domain operator, and T is the sampling period.
Rated load voltage
And a load voltage feedback value uLd,uLqThe obtained difference value is input into the PI controller for calculation, and the obtained outer loop control output value can be represented by formula (7).
Rated load voltage
And a load voltage feedback value uLd,uLqThe difference value is input into the resonance controller for calculation, and the obtained outer loop control output value can be represented by formula (8).
Rated load voltage
And a load voltage feedback value uLd,uLqThe obtained outer loop control output value can be expressed by formula (9).
Wherein the content of the first and second substances,
the first-order low-pass filter can further improve the stability of the system.
When the converted coordinate system is a two-phase static coordinate system, the difference value between the rated load voltage and the feedback value of the load voltage can be respectively input into the resonance controller and the repetitive controller for calculation; in the specific calculation process, the transfer function of the resonance controller is
Wherein k isrAnd kpFor the resonance control coefficient, s is the complex frequency domain operator, omegacIs the angular frequency, omega, of the load voltage0An angular frequency associated with a high gain bandwidth; the transfer function of the repetitive controller is
Wherein k isrIs the resonance control coefficient, s is the complex frequency domain operator, and T is the sampling period.
Step S202: controlling the output value u according to the load voltage outer loopnd,unq(n-1, 2,3) rated load voltage
And load voltage feedback value uLd,uLqCalculating to obtain the given value of the inductance current inner ring control
Specifically, a plurality of outer-loop control output values u are obtained through calculationnd,unqAfter (n is 1,2,3), a plurality of voltage outer-loop control output values may be superimposed to obtain an outer-loop control total output value uLdo,uLqo(ii) a Meanwhile, proportional operation is carried out according to the rated load voltage and the load voltage feedback value to obtain a feedforward value u of the first load voltageLLd,uLLq(ii) a Then, the feedforward value u of the first load voltage is usedLLd,uLLqAnd the total output value u of the outer loop controlLdo,uLqoSuperposing to obtain the given value of the inductive current inner loop control
Specifically, in the synchronous rotation coordinate system, the outer loop control total output value may be represented by equation (10).
When proportional operation is performed according to the rated load voltage and the load voltage feedback value, the specific calculation process is expressed by a formula (11),
wherein u isLLd,uLLqRepresenting a first load voltage feed forward value.
After calculating the feedforward value of the first load voltage, calculating the feedforward value u of the first load voltageLLd,uLLqAnd the total output value u of the outer loop controlLdo,uLqoSuperposing to obtain the given value of the inductive current inner loop control
Wherein the feed forward value u of the first load voltage is due to limitations of the outer loop control of the load voltageLLd,uLLqThe dynamic response capability of the series inverter compensation voltage can be effectively improved.
When the converted coordinate system is a two-phase static coordinate system, the given value controlled by the voltage inner loop of the filter capacitor can be calculated by adopting the same calculation process with the synchronous rotating coordinate system.
As an optional implementation manner of the embodiment of the present invention, as shown in fig. 1 and 4, step S104 performs current inner loop control calculation according to a difference between a given value of the inductor current inner loop control and the inductor current feedback value to obtain a given value of the filter capacitor voltage inner loop control, including:
step S301: according to the given value controlled by the inner loop of the inductive current
And the inductor current feedback value iLd,iLqIs inputted to the controller GI(s) calculating to obtain the control output value u of the inner loop of the inductive currentnd,unq(n-4, 5, 6); in particular, the given value of the inductor current inner loop control can be set
And the inductor current feedback value iLd,iLqDifference of (2)
Respectively input into a plurality of controllers for calculation to obtain a plurality of outer ring control output values und,unq(n is 4,5,6), wherein the plurality of controllers may be any two or more of a PI controller, a resonance controller, and a repetitive controller, which is not limited in this respect.
Among the controllers, the PI controller can be used for quickly following a given value controlled by a voltage inner loop of the compensation filter capacitor, so that the dynamic response capability of the series inverter is improved, and particularly the compensation capability of the series inverter on the voltage balance drop of a power grid is improved; the resonance controller can inhibit the periodic voltage fluctuation of specific times caused by load current and system parameters, and enhance the stability of output voltage; the repetitive controller can be used for eliminating static errors and harmonic voltages existing in the compensation voltage of the series inverter and improving the quality of the compensation voltage.
In the synchronous rotating coordinate system, the difference value between the given value controlled by the inductance current inner loop and the inductance current feedback value can be respectively input into the PI controller, the resonance controller and the repetitive controller for calculation. When the converted coordinate system is a two-phase static coordinate system, the difference value between the given value controlled by the inductance current inner loop and the inductance current feedback value can be respectively input into the resonance controller and the repetitive controller for calculation.
Step S302: controlling the output value u according to the inner loop of the inductive currentnd,unq(n is 4,5,6), obtaining the given value of the filter capacitor voltage inner loop control
Specifically, after calculating the plurality of inner loop control output values, the plurality of inner loop control output values u may be calculatednd,unq(n is 4,5 and 6) to obtain the output value of the inductor current inner loop control, namely the given value of the filter capacitor voltage inner loop controlValue of
As an optional implementation manner of the embodiment of the present invention, as shown in fig. 1 and fig. 5, step S105 performs voltage inner loop control calculation according to a difference between a given value of filter capacitor voltage inner loop control and a filter capacitor voltage feedback value to obtain a compensation voltage of a series inverter, including the following steps:
step S401: according to the given value of the voltage inner ring control of the filter capacitor
And filter capacitor voltage feedback value uCd,uCqDifferential input voltage inner loop controller GC(s) calculating to obtain the voltage inner loop control output value u of the filter capacitornd,unq(n ═ 7,8, 9); in particular, the filter capacitor voltage may be given a value
And filter capacitor voltage feedback value uCd,uCqDifference of (2)
Respectively inputting the voltage values into a plurality of controllers for calculation to obtain a plurality of voltage inner ring control output values und,unq(n ═ 7,8,9), where the plurality of controllers may be any two or more of PI controllers, resonance controllers, and repetitive controllers, and the present invention is not limited thereto.
Among the controllers, the PI controller can be used for quickly following a given value controlled by a voltage inner loop, so that the dynamic response capability of the series inverter is improved, and particularly the compensation capability of the series inverter on the voltage balance drop of a power grid is improved; the resonance controller can inhibit the periodic voltage fluctuation of specific times caused by inductive current and system parameters, and enhance the stability of output voltage; the repetitive controller can be used for eliminating static errors and harmonic voltages existing in the compensation voltage of the series inverter and improving the quality of the compensation voltage.
Under the synchronous rotating coordinate system, the difference value between the given value of the filter capacitor voltage inner loop control and the filter capacitor voltage feedback value can be respectively input into the PI controller, the resonance controller and the repetitive controller for calculation. When the converted coordinate system is a two-phase static coordinate system, the difference value between the given value of the filter capacitor voltage inner loop control and the filter capacitor voltage feedback value can be respectively input into the resonance controller and the repetitive controller for calculation.
Step S402: controlling the output value u according to the voltage inner loop of the filter capacitornd,unq(n-7, 8,9) rated load voltage
And load voltage feedback value uLd,uLqCalculating to obtain the compensation voltage of the series inverter
Specifically, after calculating the plurality of inner loop control output values, the plurality of voltage inner loop control output values u may be calculatednd,unq(n is 7,8 and 9) are superposed to obtain a total output value u of the voltage inner loop controlCdo,uCqo(ii) a At the same time, according to the rated load voltage
And a load voltage feedback value uLd,uLqCarrying out proportional operation to obtain a feedforward value u 'of the second load voltage'LLd,u'LLq(ii) a And then feeding forward value u 'of the second load voltage'LLd,u'LLqControlling the total output value u with the voltage inner loopCdo,uCqoSuperposing to obtain the voltage to be compensated of the series inverter
Specifically, when proportional operation is performed according to the rated load voltage and the load voltage feedback value in the synchronous rotating coordinate system, the specific calculation process is expressed by formula (12),
wherein u'LLd,u'LLqA feed forward value representing the second load voltage.
Feeding forward value u 'of second load voltage'LLd,u'LLqAnd inner loop control of total output value uCdo,uCqoSuperposing to obtain the compensation voltage of the series inverter
Wherein, the feedforward value u 'of the second load voltage'LLd,u'LLqThe fluctuation of the load voltage can be effectively inhibited, and the dynamic response of the compensation voltage of the series inverter is improved.
When the converted coordinate system is a two-phase stationary coordinate system, the compensation voltage of the series inverter can be calculated by adopting the same calculation process as that of the synchronous rotating coordinate system.
As an optional implementation manner of the embodiment of the present invention, outputting the compensation voltage as a control signal of the series inverter includes: and converting the compensation voltage by a coordinate system to obtain a control signal of the series inverter for outputting.
Specifically, when the converted coordinate system is a synchronous rotating coordinate system, the obtained compensation voltage in the synchronous rotating coordinate system may be converted into a three-phase stationary coordinate system, and the specific conversion process may adopt formula (13):
wherein the content of the first and second substances,
represents the compensation voltage in the synchronous rotating coordinate system,
representing the compensation voltage in a three-phase stationary frame.
Specifically, when the converted coordinate system is a two-phase stationary coordinate system, the obtained compensation voltage in the two-phase stationary coordinate system may be converted into a three-phase stationary coordinate system, and the specific conversion process may use formula (14):
wherein the content of the first and second substances,
representing the compensation voltage in a two-phase stationary frame,
representing the compensation voltage in a three-phase stationary frame.
Specifically, experimental verification may be performed on the compound control method of the series inverter provided in the embodiment of the present invention. Firstly, a 380V/100kVA series inverter system can be built, and as shown in FIG. 6, the voltage sag device can be used for simulating the voltage balance and unbalance sag of a power grid; the device to be tested is a series inverter; the energy-taking power supply adopts a mode that a voltage regulator is connected with an uncontrollable rectifier bridge to stabilize the direct-current bus voltage of the inverter at 1000V; the load is a resistance cabinet. The series inverter can adopt a single-phase full-bridge structure as shown in the figure, the direct current side is connected to a direct current power supply through a common direct current bus, the filter circuit on the alternating current side adopts an LC structure, and the inverter is connected between a power grid and an electric load in series through a transformer. Wherein the rated line voltage of the electrical load
Switching frequency f of invertersThe filter inductance L is 8kHz, the filter capacitance C is 0.8mH, and the filter capacitance C is 30 uF.
The series inverter system is adopted to carry out a power grid voltage drop compensation test, and according to test results, no matter the output voltage of the voltage sag device generates balance and unbalance drop at any angle, the series inverter can quickly stabilize the power supply voltage of a load at 380V through a composite control method based on double-voltage closed loop and load voltage feedforward, and the composite control method for the series inverter provided by the embodiment of the invention is used for effectively compensating balance and unbalance drop of the power grid voltage and compensation voltage periodic fluctuation generated by load current and system parameters.
An embodiment of the present invention further provides a compound control device for a series inverter, as shown in fig. 8, the compound control device for a series inverter may include a processor 51 and a memory 52, where the processor 51 and the memory 52 may be connected by a bus or in another manner, and fig. 8 takes the connection by the bus as an example.
The processor 51 may be a Central Processing Unit (CPU). The Processor 51 may also be other general purpose processors, Digital Signal Processors (DSPs), Application Specific Integrated Circuits (ASICs), Field Programmable Gate Arrays (FPGAs) or other Programmable logic devices, discrete Gate or transistor logic devices, discrete hardware components, or combinations thereof.
The memory 52, which is a non-transitory computer readable storage medium, may be used to store non-transitory software programs, non-transitory computer executable programs, and modules. The processor 51 executes various functional applications and data processing of the processor by running non-transitory software programs, instructions and modules stored in the memory 52, that is, implements the composite control method of the series inverter in the above method embodiment.
The memory 52 may include a storage program area and a storage data area, wherein the storage program area may store an operating system, an application program required for at least one function; the storage data area may store data created by the processor 51, and the like. Further, the memory 52 may include high speed random access memory, and may also include non-transitory memory, such as at least one magnetic disk storage device, flash memory device, or other non-transitory solid state storage device. In some embodiments, the memory 52 may optionally include memory located remotely from the processor 51, and these remote memories may be connected to the processor 51 via a network. Examples of such networks include, but are not limited to, the internet, intranets, local area networks, mobile communication networks, and combinations thereof.
The one or more modules are stored in the memory 52 and, when executed by the processor 51, perform a compound control method of series inverters as in the embodiment shown in fig. 1-5.
The details of the composite control device of the series inverter can be understood by referring to the corresponding descriptions and effects in the embodiments shown in fig. 1 to fig. 7, and are not described herein again.
It will be understood by those skilled in the art that all or part of the processes of the methods of the embodiments described above can be implemented by a computer program, which can be stored in a computer-readable storage medium, and when executed, can include the processes of the embodiments of the methods described above. The storage medium may be a magnetic Disk, an optical Disk, a Read-Only Memory (ROM), a Random Access Memory (RAM), a Flash Memory (Flash Memory), a Hard Disk (Hard Disk Drive, abbreviated as HDD), a Solid State Drive (SSD), or the like; the storage medium may also comprise a combination of memories of the kind described above.
Although the embodiments of the present invention have been described in conjunction with the accompanying drawings, those skilled in the art may make various modifications and variations without departing from the spirit and scope of the invention, and such modifications and variations fall within the scope defined by the appended claims.
Claims (8)
1. A compound control method for a series inverter, comprising:
acquiring load voltage, filter capacitor voltage and inductance current;
transforming the load voltage, the filter capacitor voltage and the inductive current by a coordinate system to obtain a feedback value of the load voltage, a feedback value of the filter capacitor voltage and a feedback value of the inductive current;
performing load voltage outer loop control calculation according to the difference value between the rated load voltage and the load voltage feedback value to obtain a given value of inductive current inner loop control;
performing inductive current inner loop control calculation according to the difference value between the given value of the inductive current inner loop control and the inductive current feedback value to obtain the given value of the filter capacitor voltage inner loop control;
performing voltage inner loop control calculation according to the difference value between the given value of the filter capacitor voltage inner loop control and the filter capacitor voltage feedback value to obtain the compensation voltage of the series inverter;
outputting the compensation voltage of the series inverter as a control signal of the series inverter;
the method comprises the following steps of carrying out load voltage outer loop control calculation according to a difference value between rated load voltage and the load voltage feedback value to obtain a given value of inductive current inner loop control, wherein the given value comprises the following steps:
inputting a voltage outer ring controller for calculation according to the difference value of the rated load voltage and the load voltage feedback value to obtain a load voltage outer ring control output value;
carrying out proportional operation according to the difference value between the rated load voltage and the load voltage feedback value to obtain a feedforward value of the first load voltage;
and performing superposition operation on the feedforward value of the first load voltage and the load voltage outer ring control output value to obtain the set value of the inductive current inner ring control.
2. The compound control method of the series inverter according to claim 1, wherein the step of performing the inductor current inner loop control calculation according to the difference between the given value of the inductor current inner loop control and the inductor current feedback value to obtain the given value of the filter capacitor voltage inner loop control comprises:
and inputting the difference value of the given value of the inductive current inner loop control and the inductive current feedback value into an inductive current inner loop controller for calculation to obtain the given value of the filter capacitor voltage inner loop control.
3. The compound control method of the series inverter according to claim 2, wherein performing voltage inner loop control calculation according to a difference between a given value of the filter capacitor voltage inner loop control and the filter capacitor voltage feedback value to obtain a compensation voltage of the series inverter comprises:
inputting a difference value of the given value of the voltage inner loop control of the filter capacitor and the voltage feedback value of the filter capacitor into a voltage inner loop controller for calculation to obtain a voltage inner loop control output value of the filter capacitor;
and calculating according to the filter capacitor voltage inner loop control output value, the rated load voltage and the load voltage feedback value to obtain the compensation voltage of the series inverter.
4. The compound control method of the series inverter according to claim 3, wherein the step of calculating the compensation voltage of the series inverter according to the filter capacitor voltage inner loop control output value, the rated load voltage and the load voltage feedback value comprises:
carrying out proportional operation according to the difference value between the rated load voltage and the load voltage feedback value to obtain a feedforward value of a second load voltage;
and performing superposition operation on the feedforward value of the second load voltage and the voltage inner loop control output value of the filter capacitor to obtain the compensation voltage of the series inverter.
5. The compound control method of a series inverter according to any one of claims 1 to 4, wherein the controller includes a resonance controller and a repetitive controller when the transformed coordinate system is a two-phase stationary coordinate system.
6. The compound control method of a series inverter according to claim 1, wherein outputting the compensation voltage as a control signal of the series inverter comprises:
and converting the compensation voltage by a coordinate system to obtain a control signal of the series inverter for outputting.
7. A computer-readable storage medium storing computer instructions for causing a computer to execute the composite control method of a series inverter according to any one of claims 1 to 6.
8. A compound control apparatus of series inverters, comprising: a memory and a processor, the memory and the processor being communicatively connected to each other, the memory storing computer instructions, and the processor executing the computer instructions to perform the method of compound control of series inverters according to any one of claims 1 to 6.
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