CN102291030A - Method for controlling balance of three-level photovoltaic grid-connected inverter direct current voltage - Google Patents
Method for controlling balance of three-level photovoltaic grid-connected inverter direct current voltage Download PDFInfo
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- CN102291030A CN102291030A CN2011102339685A CN201110233968A CN102291030A CN 102291030 A CN102291030 A CN 102291030A CN 2011102339685 A CN2011102339685 A CN 2011102339685A CN 201110233968 A CN201110233968 A CN 201110233968A CN 102291030 A CN102291030 A CN 102291030A
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Abstract
The invention relates to a method for controlling the balance of a three-level photovoltaic grid-connected inverter direct current (DC) voltage, and the method comprises the following steps of: 1, generating an error regulating quantity according to difference between a positive DC busbar voltage (Vdc1) and a negative DC busbar voltage (Vdc2) by means of proportional integration; 2, multiplying the error regulating quantity respectively by instantaneous values (isa, isb and isc) of a detecting current of a three-phase alternating current (AC) side, wherein the multiplied quantities are respectively an offset quantity of each phase modulating wave; 3, adding the phase modulating waves (usam, usbm and uscm) which are generated by a main controller with the obtained offset quantities to generate new modulating quantities which are used as modulating waves of a first tube and a third tube of three phases (A, B and C), and subtracting the obtained offset quantities from each phase modulating wave respectively to generate novel modulating quantities which are used as modulating waves of a second tube and a fourth tube of the three phases (A, B and C); and 4, transmitting the obtained modulating waves to a PWM (Pulse Width Modulation) unit to generate PWM driving signals for each phase bridge arm switching tube. All of the steps are realized in a DSP (Digital Signal Processor).
Description
Technical field
The present invention relates to a kind of controlling schemes of three-phase photovoltaic grid-connected inverting device, relate in particular to a kind of three-phase three-wire system three-level photovoltaic grid-connected inverter dc-voltage balance method, be applicable to the solar power generation application.
Background technology
Efficient and grid-connected current THD(Total Harmonic distortion, total harmonic distortion) be two indexs of photovoltaic combining inverter most critical.Be generally and obtain littler grid-connected current harmonic content, all take to improve the way of switching frequency, but this must cause inverter losses to increase, overall efficiency reduces.Three-level inverter improves equivalent switching frequency by increasing the output level number, therefore can realize harmonic current output preferably with lower switching frequency.
The diode clamp three-level inverter is the multi-electrical level inverter that is most widely used, and in theory, because three-phase system is symmetrical, diode clamp three-level inverter dc capacitor voltage should be a balance all the time.Yet, because the existence of dead band, device parameters or the like asymmetric factor, feasible current average by clamp diode inflow dc bus mid point is not 0, thereby it is uneven to cause positive direct-current busbar voltage and negative DC bus-bar voltage to occur, if it is not suppressed, the advantage of three level will be lost, when damaging self power device even can cause damage to other devices in the system.
Mainly contain two kinds of methods at present and can solve diode clamp three-level inverter dc capacitor voltage imbalance problem: a kind of SVPWM(Space of being based on Vector Pulse Width Modulation, space vector pulse width modulation), by selecting the small vector of three-level inverter output, thereby change its switching tube ON time, make that the mean value that flows into dc bus mid point electric current is 0, the final dc capacitor voltage balance that realizes, this method is used comparatively extensive, but difficult point is to realize comparatively complexity; Another kind method is based on SPWM(sinusoidal Pulse Width Modulation, sinusoidal pulse width modulation), thereby change switching tube ON time realization dc capacitor voltage balance by in modulating wave, injecting zero sequence voltage component, the advantage of this method is to realize simple, and the residual voltage that injects can not have influence on the output current of diode clamp three-level inverter, and its difficult point is the selection of zero sequence voltage component.
Summary of the invention
Technical problem to be solved: the invention provides a kind of three-phase three-wire system three-level photovoltaic grid-connected inverter DC voltage balance control method at above deficiency, this method is modulated based on SPWM, effectively realize the dc capacitor voltage Balance Control by selecting to inject zero sequence voltage component cleverly, improve photovoltaic DC-to-AC converter efficient, reduce the output voltage current harmonics, reduce switch stress, cost is also lower.
The present invention realizes by the following technical programs: a kind of three-level photovoltaic grid-connected inverter DC voltage balance control method is characterized in that: may further comprise the steps:
The first step: the mode of passing ratio integration, according to the positive direct-current busbar voltage
V Dc1 With negative DC bus-bar voltage
V Dc2 Difference produce the error regulated quantity;
Second step: this error regulated quantity detects the instantaneous value of electric current respectively with the three-phase alternating current side
i Sa , i Sb , i Sc Multiply each other, gained product amount is the amount of bias of each phase modulating wave;
The 3rd step: by each phase modulating wave of master controller generation
u Sam , u Sbm , u Scm With the addition of gained amount of bias, generate the modulating wave of new modulation voltage as ABC three-phase 1 pipe and 3 pipes; Each phase modulating wave and gained amount of bias are subtracted each other, and produce the modulating wave of new modulation voltage as ABC three-phase 2 pipes and 4 pipes;
The 4th step: the modulating wave that obtains is delivered to the PWM drive signal of PWM generating unit generation at each phase brachium pontis switching tube;
Institute is in steps all at DSP, and promptly digital signal processor realizes in the digital signal processor.
Beneficial effect:
The present invention is applied in the diode clamp three-level photovoltaic grid-connected inverter, is used to solve three level combining inverter dc capacitor voltage equilibrium problems.This invention is modulated respectively switching tube then by the zero sequence voltage component of injection in modulating wave with the grid-connected current homophase, thereby changes the switching tube ON time, realizes the dc capacitor voltage balance.This method realizes simple, and good stability does not increase any hardware cost, has higher utility.
Description of drawings
Fig. 1 is the related diode clamp three-level photovoltaic grid-connected inverter of the present invention circuit theory diagrams;
Fig. 2 is the related diode clamp three-level photovoltaic grid-connected inverter of a present invention master-slave control method schematic diagram;
Fig. 3 is the related diode clamp three-level photovoltaic grid-connected inverter of a present invention dc-voltage balance control algolithm schematic diagram.
Embodiment
The present invention is used for the diode clamp three-level photovoltaic grid-connected inverter.Based on diode clamp three-level photovoltaic grid-connected inverter schematic diagram of device such as Fig. 1, this circuit topology is made up of 12 switching tubes, and 4 switching tubes of every phase brachium pontis also directly are incorporated into the power networks by inductance, and line voltage is respectively
v Sa , v Sb , v Sc , grid-connected current is respectively
i Sa , i Sb , i Sc Containing 2 electric capacity in its DC side is respectively
C 1,
C 2, dc capacitor voltage is respectively
V Dc1 , V Dc2 Because the existence of dead band, device parameters or the like asymmetric factor, if do not add control, can there be imbalance in diode clamp three-level photovoltaic grid-connected inverter dc capacitor voltage, can cause device to damage when serious.
The balance control method that the present invention proposes adopts principal and subordinate's control model (as shown in Figure 2), and master controller adopts traditional decoupling zero control algolithm to realize the photovoltaic DC-to-AC converter active current control of being incorporated into the power networks, the output of this controller
u Sam , u Sbm , u Scm Input variable as slave controller; Modulate (as shown in Figure 3) again from the basis that is controlled at master controller output, thereby realize the dc capacitor voltage Balance Control by the ON time that changes each phase brachium pontis switching tube; The output variable of slave controller is delivered to 12 switching tubes as final modulating wave respectively by the PWM generating unit.
The balance control method of carrying by dc capacitor voltage and the alternating current that samples DC side positive and negative busbar voltage is carried out Balance Control, this three-level photovoltaic grid-connected inverter DC voltage balance control method may further comprise the steps:
The first step: the mode of passing ratio integration, according to the positive direct-current busbar voltage
V Dc1 With negative DC bus-bar voltage
V Dc2 Difference produce the error regulated quantity.
Second step: this error regulated quantity detects the instantaneous value of electric current respectively with the three-phase alternating current side
i Sa , i Sb , i Sc Multiply each other, gained product amount is the amount of bias of each phase modulating wave.
The 3rd step: by each phase modulating wave of master controller generation
u Sam , u Sbm , u Scm With the addition of gained amount of bias, generate the modulating wave of new modulation voltage as ABC three-phase 1 pipe and 3 pipes; Each phase modulating wave and gained amount of bias are subtracted each other, and produce the modulating wave of new modulation voltage as ABC three-phase 2 pipes and 4 pipes.
The 4th step: the modulating wave that obtains is sent as the PWM drive signal of the generation of the PWM generating unit among Fig. 2 at each phase brachium pontis switching tube.
In the above-mentioned control method, institute is in steps all at DSP(digital signal processor, digital signal processor) in realize.
The above is the preferred embodiments of the present invention only, is not restricted to the present invention, and for a person skilled in the art, the present invention can have various changes and variation.Within the spirit and principles in the present invention all, any modification of being done, be equal to replacement, improvement etc., all should be included within the claim scope of the present invention.
Claims (1)
1. three-level photovoltaic grid-connected inverter DC voltage balance control method is characterized in that: may further comprise the steps:
The first step: the mode of passing ratio integration, according to the positive direct-current busbar voltage
V Dc1 With negative DC bus-bar voltage
V Dc2 Difference produce the error regulated quantity;
Second step: this error regulated quantity detects the instantaneous value of electric current respectively with the three-phase alternating current side
i Sa , i Sb , i Sc Multiply each other, gained product amount is the amount of bias of each phase modulating wave;
The 3rd step: by each phase modulating wave of master controller generation
u Sam , u Sbm , u Scm With the addition of gained amount of bias, generate the modulating wave of new modulation voltage as ABC three-phase 1 pipe and 3 pipes; Each phase modulating wave and gained amount of bias are subtracted each other, and produce the modulating wave of new modulation voltage as ABC three-phase 2 pipes and 4 pipes;
The 4th step: the modulating wave that obtains is delivered to the PWM drive signal of PWM generating unit generation at each phase brachium pontis switching tube;
Institute is in steps all at DSP, and promptly digital signal processor realizes in the digital signal processor.
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| CN2011102339685A CN102291030A (en) | 2011-08-16 | 2011-08-16 | Method for controlling balance of three-level photovoltaic grid-connected inverter direct current voltage |
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Cited By (8)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN103746584A (en) * | 2014-01-10 | 2014-04-23 | 南京理工大学 | Carrier offset-based control method for mid-point voltage balance of multilevel inverter |
| CN104426407A (en) * | 2013-09-11 | 2015-03-18 | Abb公司 | Method and apparatus for balancing voltages of multi-level inverter DC link |
| CN112187079A (en) * | 2020-10-14 | 2021-01-05 | 河南科技大学 | Single-phase three-level converter system and control method thereof |
| CN112865575A (en) * | 2021-04-13 | 2021-05-28 | 阳光电源股份有限公司 | Inversion control method and application device thereof |
| CN113364314A (en) * | 2021-04-26 | 2021-09-07 | 湖南大学 | Single-stage three-phase 3MPPT type photovoltaic inverter and control strategy thereof |
| WO2022051892A1 (en) * | 2020-09-08 | 2022-03-17 | 华为数字能源技术有限公司 | Three-level inverter and control method and system |
| CN115241926A (en) * | 2022-09-16 | 2022-10-25 | 深圳市首航新能源股份有限公司 | Bus voltage control method, bus balance control method and system |
| CN115622435A (en) * | 2022-12-13 | 2023-01-17 | 麦田能源有限公司 | Control method and device of inverter based on scene observation and inverter system |
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| CN101976967A (en) * | 2010-10-26 | 2011-02-16 | 深圳市盛弘电气有限公司 | Method for controlling balance of three-level inverter and direct current busbar voltage |
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| EP1995860A2 (en) * | 2007-05-25 | 2008-11-26 | General Electric Company | Protective circuit and method for multi-level converter |
| US20090102436A1 (en) * | 2007-10-18 | 2009-04-23 | Gerardo Escobar Valderrama | Controller for the three-phase cascade multilevel converter used as shunt active filter in unbalanced operation with guaranteed capacitors voltages balance |
| CN101599708A (en) * | 2009-06-26 | 2009-12-09 | 华中科技大学 | The method for controlling power balance of DC side of cascaded multilevel inverter |
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Cited By (18)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN104426407A (en) * | 2013-09-11 | 2015-03-18 | Abb公司 | Method and apparatus for balancing voltages of multi-level inverter DC link |
| CN104426407B (en) * | 2013-09-11 | 2017-05-24 | Abb公司 | Method and apparatus for balancing voltages of multi-level inverter DC link |
| CN103746584B (en) * | 2014-01-10 | 2016-02-24 | 南京理工大学 | Based on the multi-electrical level inverter neutral-point voltage balance method of carrier offset |
| CN103746584A (en) * | 2014-01-10 | 2014-04-23 | 南京理工大学 | Carrier offset-based control method for mid-point voltage balance of multilevel inverter |
| WO2022051892A1 (en) * | 2020-09-08 | 2022-03-17 | 华为数字能源技术有限公司 | Three-level inverter and control method and system |
| CN114982121B (en) * | 2020-09-08 | 2023-10-13 | 华为数字能源技术有限公司 | Three-level inverter, control method and system |
| CN114982121A (en) * | 2020-09-08 | 2022-08-30 | 华为数字能源技术有限公司 | Three-level inverter, control method and system |
| CN112187079A (en) * | 2020-10-14 | 2021-01-05 | 河南科技大学 | Single-phase three-level converter system and control method thereof |
| CN112187079B (en) * | 2020-10-14 | 2021-08-06 | 河南科技大学 | Single-phase three-level converter system and control method thereof |
| CN112865575B (en) * | 2021-04-13 | 2022-05-24 | 阳光电源股份有限公司 | Inversion control method and application device thereof |
| US11722072B2 (en) | 2021-04-13 | 2023-08-08 | Sungrow Power Supply Co., Ltd. | Inverter circuit control method and device thereof |
| CN112865575A (en) * | 2021-04-13 | 2021-05-28 | 阳光电源股份有限公司 | Inversion control method and application device thereof |
| CN113364314A (en) * | 2021-04-26 | 2021-09-07 | 湖南大学 | Single-stage three-phase 3MPPT type photovoltaic inverter and control strategy thereof |
| CN113364314B (en) * | 2021-04-26 | 2024-02-06 | 湖南大学 | Single-stage three-phase 3MPPT type photovoltaic inverter and control strategy thereof |
| CN115241926A (en) * | 2022-09-16 | 2022-10-25 | 深圳市首航新能源股份有限公司 | Bus voltage control method, bus balance control method and system |
| CN115241926B (en) * | 2022-09-16 | 2023-02-28 | 深圳市首航新能源股份有限公司 | Bus voltage control method, bus balance control method and system |
| CN115622435A (en) * | 2022-12-13 | 2023-01-17 | 麦田能源有限公司 | Control method and device of inverter based on scene observation and inverter system |
| CN115622435B (en) * | 2022-12-13 | 2023-04-28 | 麦田能源有限公司 | Inverter control method and device based on scene observation and inverter system |
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Application publication date: 20111221 |