CN113131507A - Novel DPB photovoltaic inverter reactive power modulation control method - Google Patents
Novel DPB photovoltaic inverter reactive power modulation control method Download PDFInfo
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- CN113131507A CN113131507A CN201911419941.8A CN201911419941A CN113131507A CN 113131507 A CN113131507 A CN 113131507A CN 201911419941 A CN201911419941 A CN 201911419941A CN 113131507 A CN113131507 A CN 113131507A
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- reactive power
- photovoltaic inverter
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- power modulation
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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
- H02J3/38—Arrangements for parallely feeding a single network by two or more generators, converters or transformers
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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
- H02J3/18—Arrangements for adjusting, eliminating or compensating reactive power in networks
- H02J3/1821—Arrangements for adjusting, eliminating or compensating reactive power in networks using shunt compensators
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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
- H02J3/38—Arrangements for parallely feeding a single network by two or more generators, converters or transformers
- H02J3/46—Controlling of the sharing of output between the generators, converters, or transformers
- H02J3/48—Controlling the sharing of the in-phase component
-
- 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
- H02J3/38—Arrangements for parallely feeding a single network by two or more generators, converters or transformers
- H02J3/46—Controlling of the sharing of output between the generators, converters, or transformers
- H02J3/50—Controlling the sharing of the out-of-phase component
-
- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02M—APPARATUS FOR CONVERSION BETWEEN AC AND AC, BETWEEN AC AND DC, OR BETWEEN DC AND DC, AND FOR USE WITH MAINS OR SIMILAR POWER SUPPLY SYSTEMS; CONVERSION OF DC OR AC INPUT POWER INTO SURGE OUTPUT POWER; CONTROL OR REGULATION THEREOF
- H02M7/00—Conversion of ac power input into dc power output; Conversion of dc power input into ac power output
- H02M7/42—Conversion of dc power input into ac power output without possibility of reversal
- H02M7/44—Conversion of dc power input into ac power output without possibility of reversal by static converters
- H02M7/48—Conversion of dc power input into ac power output without possibility of reversal by static converters using discharge tubes with control electrode or semiconductor devices with control electrode
- H02M7/53—Conversion of dc power input into ac power output without possibility of reversal by static converters using discharge tubes with control electrode or semiconductor devices with control electrode using devices of a triode or transistor type requiring continuous application of a control signal
- H02M7/537—Conversion of dc power input into ac power output without possibility of reversal by static converters using discharge tubes with control electrode or semiconductor devices with control electrode using devices of a triode or transistor type requiring continuous application of a control signal using semiconductor devices only, e.g. single switched pulse inverters
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- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02B—CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO BUILDINGS, e.g. HOUSING, HOUSE APPLIANCES OR RELATED END-USER APPLICATIONS
- Y02B70/00—Technologies for an efficient end-user side electric power management and consumption
- Y02B70/10—Technologies improving the efficiency by using switched-mode power supplies [SMPS], i.e. efficient power electronics conversion e.g. power factor correction or reduction of losses in power supplies or efficient standby modes
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- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
- Y02E10/00—Energy generation through renewable energy sources
- Y02E10/50—Photovoltaic [PV] energy
- Y02E10/56—Power conversion systems, e.g. maximum power point trackers
-
- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- 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
- Y02E40/30—Reactive power compensation
Abstract
The invention belongs to the technical field of intelligent power grid control, and particularly relates to a novel DPB photovoltaic inverter reactive power modulation control method. The control method aims at controlling the duty ratio of the DPB inverter by utilizing the SiC switch device and the reactive current loop in the reactive power modulation interval process, so that the DPB grid-connected photovoltaic inverter has the functions of reactive power support and compensation, can accept the dispatching of a superior power grid or realize the function of a virtual synchronous machine, and meets the construction requirement of an intelligent power grid.
Description
Technical Field
The invention belongs to the technical field of intelligent power grid control, and particularly relates to a novel DPB photovoltaic inverter reactive power modulation control method.
Background
Distributed single-phase photovoltaic grid-connected power generation systems are widely popularized in recent years, and the penetration ratio and the consumption rate of distributed renewable energy sources in a power grid are continuously improved. When a large number of distributed power sources are connected to a power grid, frequency and voltage disturbances of the power grid can be caused. In order to obtain higher power quality, relevant standards such as IEEE 1547, IEC 61727, VDE 4105 and the like specify a power grid access point, and the grid-connected photovoltaic inverter is required to have a relevant function of reactive compensation, even to accept the function of dispatching a superior power grid or realizing a virtual synchronous machine, so as to meet the construction requirement of the smart power grid.
The transformer-free isolated photovoltaic inverter has the advantages of small size, low cost, high efficiency, light weight and the like, and is generally applied to distributed single-phase inverters. The basic principle of the transformer-free topology is that an independent follow current loop is formed during follow current, and the voltage of the photovoltaic array is decoupled from the power grid, so that an extremely low common-mode voltage change rate can be obtained, and the leakage current generated by the capacitance of the photovoltaic array to the ground is greatly reduced. Currently, the topologies such as H5, HERIC and H6 are more applied.
The DPB (Dual-parallel-buck) is a novel single-phase transformerless photovoltaic grid-connected inverter topology, can only operate under a unit power factor in a traditional modulation and control mode, and cannot meet related requirements of a smart grid.
Disclosure of Invention
In order to solve the defects of the prior art, the invention aims to provide a novel DPB photovoltaic inverter reactive power modulation control method; the idea of the scheme is as follows: aiming at the DPB inverter, a control method for reactive power modulation of the DPB inverter is provided by utilizing a SiC switch device and a reactive current loop control method in the reactive power modulation interval process.
In order to achieve the above object, the present invention provides a novel DPB photovoltaic inverter reactive power modulation control method, which includes the following steps:
1) in the active power modulation stage, if (v > 0, i > 0) or (v < 0, i < 0);
2) operating the switching devices S1 and S2 at high frequency;
3) the switching device S3 and the switching device S4 work alternately at power frequency and low speed;
4) the current stored by the inductor L2 and the inductor L3 is modulated in a sine law, and when the current reaches 0, the current is commutated;
5) if (v > 0, i > 0) is converted to (v < 0, i > 0), or (v < 0, i < 0) is converted to (v > 0, i < 0), the DPB photovoltaic inverter enters a reactive power modulation phase;
6) and the on-off of the switching devices S2 and S1 is controlled, so that a residual circuit in the inductor generates electromotive force, and reactive power modulation control is realized.
Preferably, the switching devices S1 and S2 are SiC switching devices, and the switching devices S3 and S4 are conventional IGBT devices.
Compared with the prior art, the invention has the beneficial effects that:
1) under the working condition of unit power factor, the invention can realize flexible reactive power output of any power factor.
2) The invention has the reactive power supporting and compensating functions, so that the single-phase inverter can participate in the flexible dispatching of the power grid.
Drawings
Fig. 1 is a flowchart of a method of a novel reactive power modulation control method for a DPB photovoltaic inverter according to the present invention;
fig. 2 is a circuit topology diagram of a single-phase two-stage DPB photovoltaic inverter of the present invention;
FIG. 3 is a current working loop diagram of a reactive modulation interval for converting a DPB photovoltaic inverter from (v > 0, i > 0) to (v < 0, i > 0);
FIG. 4 is a current freewheeling loop diagram of a reactive modulation interval for the DPB photovoltaic inverter to change from (v > 0, i > 0) to (v < 0, i > 0);
FIG. 5 is a current working loop diagram of a reactive modulation interval for converting the DPB photovoltaic inverter from (v < 0, i < 0) to (v > 0, i < 0);
FIG. 6 is a reactive modulation interval current freewheeling loop diagram for the DPB photovoltaic inverter when the DPB photovoltaic inverter is converted from (v < 0, i < 0) to (v > 0, i < 0).
Detailed Description
To further understand the structure, characteristics and other objects of the present invention, the following detailed description is given with reference to the accompanying preferred embodiments, which are only used to illustrate the technical solutions of the present invention and are not to limit the present invention.
Firstly, as shown in fig. 1, fig. 1 is a flowchart of a method of a novel reactive power modulation control method for a DPB photovoltaic inverter according to the present invention; the control method comprises the following steps:
1) in the active power modulation stage, if (v > 0, i > 0) or (v < 0, i < 0);
2) operating the switching devices S1 and S2 at high frequency;
3) the switching device S3 and the switching device S4 work alternately at power frequency and low speed;
4) the current stored by the inductor L2 and the inductor L3 is modulated in a sine law, and when the current reaches 0, the current is commutated;
5) if (v > 0, i > 0) is converted to (v < 0, i > 0), or (v < 0, i < 0) is converted to (v > 0, i < 0), the DPB photovoltaic inverter enters a reactive power modulation phase;
6) and the on-off of the switching devices S2 and S1 is controlled, so that a residual circuit in the inductor generates electromotive force, and reactive power modulation control is realized.
The working principle is as follows: according to the reactive power modulation control method of the DPB single-phase photovoltaic grid-connected inverter, in an active power modulation stage (namely (v is more than 0, i is more than 0) and (v is less than 0, i is less than 0)), the modulation control method is the same as that of a traditional method, namely S1 and S2 work at high frequency, S3 and S4 work alternately at power frequency and low speed, and when the current stored in the inductors L2 and L3 is modulated to 0 according to a sine law, commutation is carried out. During the reactive power modulation phase (i.e., (v < 0, i > 0) and (v > 0, i < 0)), the residual circuit in the inductor generates electromotive force by controlling the on-off of the SiC switch devices S1 and S2. Due to the presence of the clamping diode and the parallel diode, the electromotive force is clamped to the UPV. At this time, the voltage can be expressed as:
wherein u isg＝Umsinωt，ig＝Imsinωt，UmIs the peak voltage value, ImAnd omega is the angular frequency of the grid voltage.
During the reactive power modulation phase (i.e., (v < 0, i > 0) and (v > 0, i < 0)), the duty cycle d2 of S2 is:
the obtained reference command is a segmented discontinuous waveform, and the duty ratio output is realized through a PWM (pulse-width modulation) mode, so that the on-off of the SiC switch tube S2 is controlled.
Further, as shown in fig. 2, fig. 2 is a circuit topology diagram of the single-phase two-stage DPB photovoltaic inverter of the present invention; ignoring the previous stage boost circuit, the DPB inverters S1, S2 are SiC switching devices, and S3, S4 are normal IGBT devices. In the conventional modulation mode, when the grid voltage is in a positive half cycle, in the working phase, the path of the current is C (+) → S3 → single-phase grid → L3 → S2 → C (-); in the freewheeling stage, the freewheeling path is L3 → D2 → S3 → single-phase grid. When the grid voltage is in a negative half cycle, in the working stage, the path of the current is C (+) → S4 → single-phase grid → L2 → S1 → C (-); in the freewheeling stage, the freewheeling path is L2 → D1 → S4 → single-phase grid. Among them, SiC switching devices are used for S1 and S2, and conventional IGBT devices are used for S3 and S4.
In addition, as shown in fig. 3, fig. 3 is a current working loop diagram of a reactive modulation interval for converting the DPB photovoltaic inverter from (v > 0, i > 0) to (v < 0, i > 0); taking the reactive power modulation stage of converting (v > 0, i > 0) to (v < 0, i > 0) as an example, in the working stage, the path of the current is L3 → S2 → S1(D) → L2 → the single-phase power grid.
In addition, as shown in fig. 4, fig. 4 is a current freewheeling loop diagram of the reactive modulation interval when the DPB photovoltaic inverter is converted from (v > 0, i > 0) to (v < 0, i > 0); taking the reactive power modulation phase of changing from (v > 0, i > 0) to (v < 0, i > 0) as an example, in the freewheeling phase, the path of the current is L3 → D2 → C (+) → C (-) → S1(D) → L2 → single-phase grid.
In addition, as shown in fig. 5, fig. 5 is a reactive modulation interval current working circuit diagram of the DPB photovoltaic inverter converted from (v < 0, i < 0) to (v > 0, i < 0); taking the reactive power modulation stage of converting (v < 0, i < 0) into (v > 0, i < 0) as an example, in the working stage, the path of the current is L3 → D2 → C (+) → C (-) → S1(D) → L2 → single-phase power grid.
In addition, as shown in fig. 6, fig. 6 is a circuit diagram of the reactive modulation interval current free-wheeling when the DPB photovoltaic inverter is changed from (v < 0, i < 0) to (v > 0, i < 0); taking the reactive power modulation phase of converting from (v < 0, i < 0) to (v > 0, i < 0) as an example, in the freewheeling phase, the path of the current is L3 → D2 → C (+) → C (-) → S1(D) → L2 → single-phase grid.
Finally, the novel reactive power modulation control method for the DPB photovoltaic inverter has the following specific technical characteristics:
compared with the working condition of working at a unit power factor, the novel DPB single-phase photovoltaic inverter reactive power modulation control method can realize flexible reactive power output of any power factor, has reactive support and compensation functions, and enables the single-phase inverter to participate in flexible dispatching of a power grid.
It should be noted that the above summary and the detailed description are intended to demonstrate the practical application of the technical solutions provided by the present invention, and should not be construed as limiting the scope of the present invention. Various modifications, equivalent substitutions, or improvements may be made by those skilled in the art within the spirit and principles of the invention. The scope of the invention is to be determined by the appended claims.
Claims (2)
1. The invention provides a novel DPB photovoltaic inverter reactive power modulation control method which is characterized by comprising the following steps:
1) in the active power modulation stage, if (v > 0, i > 0) or (v < 0, i < 0);
2) operating the switching devices S1 and S2 at high frequency;
3) the switching device S3 and the switching device S4 work alternately at power frequency and low speed;
4) the current stored by the inductor L2 and the inductor L3 is modulated in a sine law, and when the current reaches 0, the current is commutated;
5) if (v > 0, i > 0) is converted to (v < 0, i > 0), or (v < 0, i < 0) is converted to (v > 0, i < 0), the DPB photovoltaic inverter enters a reactive power modulation phase;
6) and the on-off of the switching devices S2 and S1 is controlled, so that a residual circuit in the inductor generates electromotive force, and reactive power modulation control is realized.
2. The control method according to claim 1, wherein the switching devices S1 and S2 are SiC switching devices, and the switching devices S3 and S4 are conventional IGBT devices.
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| CN201911419941.8A CN113131507A (en) | 2019-12-31 | 2019-12-31 | Novel DPB photovoltaic inverter reactive power modulation control method |
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| CN201911419941.8A CN113131507A (en) | 2019-12-31 | 2019-12-31 | Novel DPB photovoltaic inverter reactive power modulation control method |
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| CN113131507A true CN113131507A (en) | 2021-07-16 |
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Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN116961018A (en) * | 2023-09-18 | 2023-10-27 | 锦浪科技股份有限公司 | Flyback micro inverter system and working method thereof |
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2019
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Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN116961018A (en) * | 2023-09-18 | 2023-10-27 | 锦浪科技股份有限公司 | Flyback micro inverter system and working method thereof |
| CN116961018B (en) * | 2023-09-18 | 2023-12-12 | 锦浪科技股份有限公司 | Flyback micro inverter system and working method thereof |
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