CN114499260A - Common-ground five-level single-phase photovoltaic inverter and control method thereof - Google Patents

Common-ground five-level single-phase photovoltaic inverter and control method thereof Download PDF

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CN114499260A
CN114499260A CN202210028118.XA CN202210028118A CN114499260A CN 114499260 A CN114499260 A CN 114499260A CN 202210028118 A CN202210028118 A CN 202210028118A CN 114499260 A CN114499260 A CN 114499260A
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switch tube
voltage
switched capacitor
photovoltaic inverter
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郭斌
张欣
马皓
李雨泽
葛小海
金思聪
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Zhejiang University ZJU
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    • 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
    • H02M7/5387—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 in a bridge configuration
    • H02M7/53871—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 in a bridge configuration with automatic control of output voltage or current
    • 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
    • H02J3/16—Circuit arrangements for ac mains or ac distribution networks for adjusting voltage in ac networks by changing a characteristic of the network load by adjustment of reactive power
    • 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
    • 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
    • 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
    • H02M1/00—Details of apparatus for conversion
    • H02M1/08—Circuits specially adapted for the generation of control voltages for semiconductor devices incorporated in static converters
    • H02M1/088—Circuits specially adapted for the generation of control voltages for semiconductor devices incorporated in static converters for the simultaneous control of series or parallel connected semiconductor devices
    • 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
    • H02M1/00—Details of apparatus for conversion
    • H02M1/32—Means for protecting converters other than automatic disconnection
    • 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
    • H02J2300/00—Systems for supplying or distributing electric power characterised by decentralized, dispersed, or local generation
    • H02J2300/20—The dispersed energy generation being of renewable origin
    • H02J2300/22—The renewable source being solar energy
    • H02J2300/24—The renewable source being solar energy of photovoltaic origin

Abstract

The invention discloses a common-ground five-level single-phase photovoltaic inverter based on a switched capacitor and a control method thereof2Is a bidirectional switch. The photovoltaic cathode of the inverter is directly connected with the negative end of the power grid; switch tube S1，S2And S3Form a half-bridge T-type three-level circuit, and connect with the DC power supplyThe flow side split capacitors are connected. Switch tube S4And S5The emitter of the filter is connected with one end of the filter, and the collector of the filter is respectively connected with two ends of the switch capacitor; diode D1Anode and switch tube S5The collector is connected with the cathode, and the cathode is connected with the negative end of the power grid. The five-level inverter topology provided by the invention has fewer switching devices and has the reactive power regulation capability and the self-balancing capability of the voltage of the switched capacitor. Because the photovoltaic negative pole is directly connected with the negative end of the power grid, zero leakage current can be realized. By the proposed midpoint voltage balance control strategy, active balancing of the midpoint voltage is achieved.

Description

Common-ground five-level single-phase photovoltaic inverter and control method thereof
Technical Field
The invention relates to the technical field of power electronics and the field of photovoltaic new energy power generation, in particular to a common-ground five-level single-phase photovoltaic inverter based on a switched capacitor and a neutral point balance control method thereof.
Background
With the increasing exhaustion of fossil energy reserves such as petroleum, coal, natural gas and the like in the world and the environmental problems caused by the combustion of fossil energy, the search and development of new replaceable clean energy has become a key point of worldwide attention. Because solar energy resources are abundant and widely distributed, photovoltaic power generation becomes one of the most effective means for solving the energy problem at the present stage. The advantages of cleanness, safety, long service life, small maintenance and the like of photovoltaic power generation are recognized as the most important and most active new energy in the twenty-first century, and the development of the photovoltaic industry is one of the best ways for solving the contradiction between energy crisis, economic development and environmental protection in all energy consumption countries.
With the increasing demand of new energy power generation and the continuous development of power electronic technology, photovoltaic power generation develops towards high efficiency, high power density and medium and high voltage. Multilevel inverters (MLIs) have been widely used in photovoltaic power generation due to their high output power quality, low switching device stress, and high system power density. However, the conventional multi-level inverter based on the midpoint clamp, the cascade H-bridge and the flying capacitor requires a large number of semiconductor devices and a large number of direct-current power supplies, which results in a complicated circuit structure and increases the difficulty and cost of system control. The multi-level inverter based on the switched capacitor can output multi-level by combining the capacitor element and the switching tube, and has the advantages of few required devices, high efficiency, simple control and the like.
However, the current multi-level photovoltaic inverter based on the switched capacitor has the problems of large leakage current, lack of reactive power regulation capability, unbalanced midpoint voltage and the like.
In order to solve the problems, a switched capacitor type multi-level topology with reactive power regulation and leakage current suppression and a neutral voltage balance control strategy need to be further researched.
Disclosure of Invention
In order to solve the problems, the invention provides a common-ground five-level single-phase photovoltaic inverter topology and a midpoint voltage balance control strategy based on a switched capacitor. The topology has good leakage current suppression and reactive power regulation capacity, and voltage self-balancing of the switched capacitor can be realized without an additional hardware circuit. In order to realize the automatic balance of the midpoint voltage on the direct current side, a simple midpoint voltage balance control strategy is provided.
In order to achieve the purpose, the technical scheme of the invention is as follows:
in a first aspect, a switched capacitor-based common ground type five-level single-phase photovoltaic inverter topology is disclosed, which includes:
comprises two split capacitors C on the DC side1And C2Five switching tubes S1-S5A switched capacitor C3A diode D1And a network side filter Lg；
Switch tube S1，S2And S3A half-bridge T-shaped three-level circuit is formed and is connected with the direct current side split capacitor;
switch tube S4And S5The emitter of the filter is connected with one end of the filter, and the collector of the filter is respectively connected with two ends of the switch capacitor;
diode D1Anode and switch tube S5The collector is connected with the cathode, and the cathode is connected with the negative end of the power grid.
Furthermore, the five switching tubes are all switching tubes with anti-parallel diodes;
further, the switch tube S1、S3、S4、S5Is a one-way switch tube, a switch tube S2Is a bidirectional switch tube;
further, a switch tube S1、S2、S3Operating at high frequency, switching tube S4、S5Operating in a fundamental frequency state;
further, the photovoltaic cathode of the inverter is directly connected with the negative end of the power grid.
Furthermore, except for the zero crossing of the output voltage, only the switching states of the two switching tubes change when switching between two adjacent states.
Further, the switched capacitor voltage can be balanced over a power frequency cycle without any additional sensors and ancillary circuitry.
In a second aspect, a neutral point voltage balance control method of a five-level transformerless single-phase photovoltaic inverter based on a switched capacitor is disclosed;
sampling data in the middle point voltage balance control working process, wherein the data in the middle point voltage balance control working process comprises voltages v of two split capacitorsc1And vc2Grid-connected current ig；
Performing double frequency trap on the difference value of the two split capacitors to obtain the average value of the midpoint voltage
Figure BDA0003465361750000031
Obtaining a direct current component of a grid-connected current
Figure BDA0003465361750000032
The error signal passes through a PI controller to control a switch tube S2On and off;
finally, the expression for the midpoint voltage error signal is:
Figure BDA0003465361750000033
wherein
Figure BDA0003465361750000034
Is the midpoint average error voltage, Gpi(s) is a PI controller, which can be obtained from the above formula
Figure BDA0003465361750000035
Positive/negative, the right part of the above formula is positive/negative, and thus
Figure BDA0003465361750000036
The zero can be converged in a limited time, and the midpoint voltage balance is realized.
The invention has the beneficial effects that: the five-level common-ground single-phase photovoltaic inverter based on the switched capacitor and the neutral point voltage balance control method thereof are provided, the problem of leakage current in the traditional multi-level inverter based on the switched capacitor is solved, reactive power regulation and voltage self-balancing of the switched capacitor are realized, and meanwhile, the neutral point voltage balance is actively realized through a simple control strategy; the inverter topology structure only comprises five switching tubes, three capacitors and a network side filter; only three switching tubes work in a high-frequency state, and except for the zero-crossing position of output voltage, when switching between two adjacent states, the switching states of only two switching tubes are changed, so that the system has high efficiency.
Drawings
Fig. 1 is a schematic diagram of a topology of a five-level single-phase photovoltaic inverter according to an embodiment of the present invention.
Fig. 2 is a current flow diagram of mode one of a five-level single-phase photovoltaic inverter according to an embodiment of the present invention, wherein arrows represent grid current and switched capacitor charging current paths.
Fig. 3 is a current flow diagram of mode two of a five-level single-phase photovoltaic inverter according to an embodiment of the present invention, wherein arrows represent grid current and switched capacitor charging current paths.
Fig. 4 is a current flow diagram of mode three of a five-level single-phase photovoltaic inverter according to an embodiment of the present invention, wherein arrows represent the grid current and the switched capacitor charging current paths, respectively.
Fig. 5 is a current flow diagram of mode four of a five-level single-phase photovoltaic inverter of an embodiment of the present invention, wherein the arrows represent the grid current and switched capacitor charging current paths.
Fig. 6 is a current flow diagram of mode five of a five-level single-phase photovoltaic inverter of an embodiment of the present invention, wherein arrows represent grid current and switched capacitor charging current paths.
Fig. 7 is a current flow diagram of mode six of a five-level single-phase photovoltaic inverter of an embodiment of the present invention, wherein the arrows represent the grid current and switched capacitor charging current paths.
FIG. 8 is a modulation waveform of a five-level single-phase photovoltaic inverter according to an embodiment of the present invention;
FIG. 9 is a modulation logic for a five-level single-phase photovoltaic inverter of an embodiment of the present invention;
fig. 10 is an overall control block diagram of a five-level single-phase photovoltaic inverter of an embodiment of the present invention;
FIG. 11 shows the grid voltage, current, output voltage, and capacitance C of a five-level single-phase photovoltaic inverter according to an embodiment of the present invention1And C2Voltage simulation waveforms of (1);
fig. 12 is an experimental waveform diagram of the grid voltage, output voltage, current and dc side voltage of a five-level single-phase photovoltaic inverter according to an embodiment of the present invention;
fig. 13 is an experimental waveform diagram of the grid voltage, current, output voltage and dc-side voltage of the five-level single-phase photovoltaic inverter according to the embodiment of the present invention when the grid current leads the grid voltage by 30 °;
fig. 14 is an experimental waveform diagram of the grid voltage, the current, the output voltage and the dc side voltage of the five-level single-phase photovoltaic inverter according to the embodiment of the present invention when the grid current lags the grid voltage by 30 °.
Detailed Description
The following detailed description of embodiments of the present invention is provided in connection with the accompanying drawings and examples. The following examples are intended to illustrate the invention but are not intended to limit the scope of the invention.
As shown in figure 1, the common ground type five-level single-phase photovoltaic inverter topology based on the switched capacitor comprises two split capacitors at the direct current side,Five switching tubes, a switching capacitor, a diode and a network side filter, wherein the switching tube S2Is a bidirectional switch. The photovoltaic cathode of the inverter is directly connected with the negative end of the power grid; switch tube S1，S2And S3And a half-bridge T-shaped three-level circuit is formed and is connected with the direct current side split capacitor. Switch tube S4And S5The emitter of the filter is connected with one end of the filter, and the collector of the filter is respectively connected with two ends of the switch capacitor; diode D1Anode and switch tube S5The collector is connected with the cathode, and the cathode is connected with the negative end of the power grid.
Switch tube S1、S3And a bidirectional switch tube S2Operating at high frequency, switching tube S4、S5Operating in a fundamental frequency state; because the photovoltaic cathode is directly connected with the negative end of the power grid, the parasitic capacitance of the photovoltaic panel is directly bypassed, and the leakage current is theoretically zero; the switched capacitor voltage can be balanced over a power frequency cycle without any additional sensors and ancillary circuitry.
The working modes of the five-level single-phase photovoltaic inverter are as follows:
the first mode is as follows:
as shown in FIG. 2, the port output voltage is v in the first operation modedcAt this time, the switch tube S1、S4Conducting, switching tube S2、S3、S5And turning off, wherein the flow direction of the positive half cycle current is as follows: s1→S4→ electric network → C2→C1→S1The flow direction of the negative half-cycle current is as follows: s1→C1→C2→ electric network → S4→S1Or C3→D1→ electric network → S4→C3At this time, the switched capacitor is in a charged state.
Mode two:
as shown in FIG. 3, the port output voltage is v in the second mode of operationdc/2, switching tube S at this time2And S4Conducting, switching tube S1、S3、S5And turning off, wherein the flow direction of the positive half cycle current is as follows: s4→ electric network → C2→S2→S4The flow direction of the negative half-cycle current is as follows: s2→C2→ electric network → S4→S2The switched capacitor voltage is unchanged at this time.
Mode three:
as shown in fig. 4, the output voltage of the port in the third working mode is 0, and the switching tube S is turned on or off at this time3、S4Conducting, switching tube S1、S2、S5And turning off, wherein the flow direction of the positive half cycle current is as follows: s4→ electric network → S3→S4The flow direction of the negative half-cycle current is as follows: s3→ electric network → S4→S3The switched capacitor voltage is unchanged at this time.
And a fourth mode:
as shown in fig. 5, the output voltage of the port in the fourth working mode is 0, and the switching tube S is turned on or off at this time1、S5Conducting, switching tube S2、S3、S4And turning off, wherein the flow direction of the positive half cycle current is as follows: s. the5→D1→ electric network → S5The flow direction of the negative half-cycle current is as follows: s. the1→C1→C2→ electric network → S5→C3→S1At this time, the switched capacitor is in a charged state.
A fifth mode:
as shown in FIG. 6, the port output voltage under the fifth working mode is-vdc/2, switching tube S at this time2、S5Conducting, switching tube S1、S3、S4And turning off, wherein the flow direction of the positive half cycle current is as follows: s. the2→C2→ electric network → S5→C3→S2The flow direction of the negative half-cycle current is as follows: c2→S2→C3→S5→ electric network → C2At this time, the switched capacitor is in a discharge state.
A sixth mode:
as shown in FIG. 7, the port output voltage under the sixth working mode is-vdcAt this time, the switch tube S3、S5Conducting, switching tube S1、S2、S4And turning off, wherein the flow direction of the positive half cycle current is as follows: s3→ electric network → S5→C3→S3The flow direction of the negative half-cycle current is as follows: s3→C3→S5→ electric network → S3At this time, the switched capacitor is in a discharge state.
The summary of the working modes of the common-ground five-level single-phase photovoltaic inverter based on the switched capacitor is shown in table 1.
Table 1: working mode of five-level inverter
Figure BDA0003465361750000061
As shown in fig. 8, two carrier signals vcr1And vcr2And a modulated wave signal | vrefAnd | is used for generating a signal to control the on and off of the switch tube.
As shown in fig. 9, the switching function of the switching tube is:
Figure BDA0003465361750000062
wherein v iscom1And vcom2The two carriers are represented by "×" and "+" respectively, and logical or is represented by "N", which represents that the modulation wave is in the negative half cycle, i.e. N is 1 when the modulation wave is in the negative half cycle.
As shown in fig. 10, the control unit includes a voltage outer loop in which a conventional PI controller is employed to regulate the dc voltage and a current inner loop in which a voltage reference is generated by a maximum power point tracking algorithm. In the current loop, the reference output current magnitude is generated by a voltage loop, the phase information of which is obtained by a Phase Locked Loop (PLL). In order to achieve zero steady state error tracking and fast dynamic response of the grid current, a proportional-integral-resonant (PIR) controller is employed in the current loop.
In order to ensure that the midpoint voltage is zero, midpoint voltage level balance control is added.
As can be derived from fig. 1, the midpoint voltage expression is:
the average signal expression for the midpoint voltage is:
Figure BDA0003465361750000071
wherein
Figure BDA0003465361750000072
And
Figure BDA0003465361750000073
is C1、C2The average voltage of the capacitor,
Figure BDA0003465361750000074
is the average voltage of the mid-point,
Figure BDA0003465361750000075
is S2The duty cycle of (a) is,
Figure BDA0003465361750000076
is the average current of the power grid.
As shown in (3), the duty ratio d is ideally the same2And the grid current igSymmetric in positive and negative half cycles, no dc bias. Therefore, the midpoint voltage may be naturally balanced. In practical application, however, factors such as parameter mismatch of power modules, difference of power modules, asymmetry of driving pulses and the like are considered.
Assuming there is a small signal perturbation at the midpoint:
Figure BDA0003465361750000077
wherein
Figure BDA0003465361750000078
And
Figure BDA0003465361750000079
is the midpoint voltage and S2To balance the midpoint voltage, the duty cycle may be configured to:
Figure BDA00034653617500000710
wherein G ispi(s) is a PI controller, where the midpoint voltage can be expressed as:
Figure BDA00034653617500000711
according to (5), when
Figure BDA00034653617500000712
Positive/negative, the right part of (5) is positive/negative, and thus
Figure BDA00034653617500000713
Can converge to zero within a limited time.
As shown in fig. 11, it can be seen that after the midpoint voltage balance control strategy is adopted, the midpoint average voltage error quickly converges to zero, and the effectiveness of the midpoint voltage balance control strategy is verified.
As shown in fig. 12, the proposed transformer-less five-level single-phase photovoltaic inverter based on switched capacitors and the modulation and control method thereof can stably output high-quality voltage and current, and the THD is 3.7% and is lower than the limit value of IEEE standard 5%.
When the grid current leads or lags the grid voltage as shown in fig. 13 and 14, the THD of the grid-connected current is low, and the five-level single-phase photovoltaic inverter has reactive power regulation capability.
Finally, the method of the present invention is only a preferred embodiment and is not intended to limit the scope of the present invention. Any modification, equivalent replacement, or improvement made within the spirit and principle of the present invention should be included in the protection scope of the present invention.

Claims (8)

1. The utility model provides a five single-phase photovoltaic inverter topological structure of level of type altogether based on switched capacitor which characterized in that: comprises two split capacitors on the DC sideC1And C2Five switching tubes S1-S5A switched capacitor C3A diode D1And a network side filter LgSaid switch tube S1，S2And S3A half-bridge T-shaped three-level circuit is formed and connected with a direct current side split capacitor, and the switching tube S4And S5The emitter of the diode D is connected with one end of the filter, the collector of the diode D is respectively connected with two ends of the switch capacitor1Anode and switch tube S5The collector is connected with the cathode, and the cathode is connected with the negative end of the power grid.
2. The switched capacitor based five-level common ground single-phase photovoltaic inverter topology structure of claim 1, characterized in that: the five switching tubes S1-S5All are switch tubes with anti-parallel diodes.
3. The switched capacitor based five-level common ground single-phase photovoltaic inverter topology structure of claim 1, characterized in that: the switch tube S1Switch tube S3Switch tube S4Switch tube S5Is a one-way switch tube, a switch tube S2Is a bidirectional switch tube.
4. The switched capacitor based five-level common ground single-phase photovoltaic inverter topology structure of claim 1, characterized in that: switch tube S1、S2、S3Operating at high frequency, switching tube S4、S5And working in a power frequency state.
5. The switched capacitor based five-level common ground single-phase photovoltaic inverter topology structure of claim 1, characterized in that: and the photovoltaic cathode of the inverter is directly connected with the cathode of the power grid.
6. The switched capacitor based five-level common ground single-phase photovoltaic inverter topology structure of claim 1, characterized in that: in a power frequency period, no additional sensor and auxiliary circuit are needed, and the voltage of the switch capacitor realizes self-balancing.
7. The switched capacitor-based five-level single-phase photovoltaic inverter topology structure is characterized in that the switching states of only two switching tubes are changed when switching between two adjacent states except for the zero crossing of the output voltage.
8. The method for controlling the midpoint voltage balance of the switched-capacitor-based common-ground five-level single-phase photovoltaic inverter topology structure is characterized by comprising the following steps of:
step 1: sampling DC input two split capacitors C1And C2Voltage v ofc1And vc2Grid-connected current ig；
Step 2: for two split capacitors C1And C2The voltage is subjected to difference and then passes through a double-frequency wave trap to obtain the average value of the midpoint voltage error
Figure FDA0003465361740000021
And step 3: obtaining a direct current component of a grid-connected current
Figure FDA0003465361740000022
And 4, step 4: and multiplying the error signal by a sign function of a direct current component after the error signal passes through a PI controller so as to obtain a compensation part of the midpoint voltage balance control, wherein the expression of the compensation part is as follows:
Figure FDA0003465361740000023
wherein
Figure FDA0003465361740000024
Are respectively a switch tube S2Of the duty cycle and the amount of change in the midpoint voltage error, Gpi(s) is a PI controller, sign () is a sign function;
and 5: superimposing the acquired compensation part on the switching tube S2The steady duty ratio of (2) to (3) to realize the balance control of the midpoint voltage.
CN202210028118.XA 2022-01-11 2022-01-11 Common-ground five-level single-phase photovoltaic inverter and control method thereof Pending CN114499260A (en)

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CN116014820A (en) * 2023-03-28 2023-04-25 南昌科晨电力试验研究有限公司 Asymmetric fault low-voltage ride-through control method and system based on super capacitor
CN116885926A (en) * 2023-09-08 2023-10-13 广州三晶电气股份有限公司 Dynamic setting method and device for current loop proportion control parameters

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* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN116014820A (en) * 2023-03-28 2023-04-25 南昌科晨电力试验研究有限公司 Asymmetric fault low-voltage ride-through control method and system based on super capacitor
CN116014820B (en) * 2023-03-28 2023-08-29 南昌科晨电力试验研究有限公司 Asymmetric fault low-voltage ride-through control method and system based on super capacitor
CN116885926A (en) * 2023-09-08 2023-10-13 广州三晶电气股份有限公司 Dynamic setting method and device for current loop proportion control parameters
CN116885926B (en) * 2023-09-08 2023-12-22 广州三晶电气股份有限公司 Dynamic setting method and device for current loop proportion control parameters

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