CN108365628B - Three-phase photovoltaic grid-connected inverter non-impact current grid-connected control method - Google Patents

Three-phase photovoltaic grid-connected inverter non-impact current grid-connected control method Download PDF

Info

Publication number
CN108365628B
CN108365628B CN201810216669.2A CN201810216669A CN108365628B CN 108365628 B CN108365628 B CN 108365628B CN 201810216669 A CN201810216669 A CN 201810216669A CN 108365628 B CN108365628 B CN 108365628B
Authority
CN
China
Prior art keywords
grid
voltage
phase
connected inverter
inverter
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Active
Application number
CN201810216669.2A
Other languages
Chinese (zh)
Other versions
CN108365628A (en
Inventor
徐亚飞
黄敏
方刚
卢进军
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Goodwe Technologies Co Ltd
Original Assignee
Goodwe Technologies Co Ltd
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Goodwe Technologies Co Ltd filed Critical Goodwe Technologies Co Ltd
Priority to CN201810216669.2A priority Critical patent/CN108365628B/en
Publication of CN108365628A publication Critical patent/CN108365628A/en
Priority to PCT/CN2018/120027 priority patent/WO2019174331A1/en
Application granted granted Critical
Publication of CN108365628B publication Critical patent/CN108365628B/en
Active legal-status Critical Current
Anticipated expiration legal-status Critical

Links

Images

Classifications

    • 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
    • H02J3/1807—Arrangements for adjusting, eliminating or compensating reactive power in networks using series compensators
    • H02J3/1814—Arrangements for adjusting, eliminating or compensating reactive power in networks using series compensators wherein al least one reactive element is actively controlled by a bridge converter, e.g. unified power flow controllers [UPFC]
    • 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
    • H02J3/26—Arrangements for eliminating or reducing asymmetry in polyphase 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
    • H02J3/381—Dispersed generators
    • 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
    • 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
    • Y02E40/10—Flexible AC transmission systems [FACTS]
    • 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
    • Y02E40/50—Arrangements for eliminating or reducing asymmetry in polyphase networks

Landscapes

  • Engineering & Computer Science (AREA)
  • Power Engineering (AREA)
  • Inverter Devices (AREA)
  • Supply And Distribution Of Alternating Current (AREA)

Abstract

The invention relates to a non-impact current grid-connected control method for a three-phase photovoltaic grid-connected inverter, which comprises the following steps: before the three-phase photovoltaic grid-connected inverter is switched on, acquiring the line voltage of the grid side and the line voltage of the inversion side of the three-phase photovoltaic grid-connected inverter to obtain driving pulses required by the three-phase photovoltaic grid-connected inverter for grid voltage feedforward current inner loop decoupling control; when the difference between the D-axis voltage component of the grid side of the three-phase photovoltaic grid-connected inverter and the D-axis voltage component of the inversion side is smaller than a preset D-axis threshold value, and the difference between the Q-axis voltage component of the grid side and the Q-axis voltage component of the inversion side is smaller than a preset Q-axis threshold value and the duration time is longer than a set first time threshold value, a grid-side relay of the three-phase photovoltaic grid-connected inverter is closed, and closing and grid connection are completed. The invention solves a series of problems of reduced service life of components caused by existence of grid-connected impact current, overlarge leakage current caused by impact on a power grid and the like, and is compatible with triangular and star-shaped power grids.

Description

Three-phase photovoltaic grid-connected inverter non-impact current grid-connected control method
Technical Field
The invention belongs to the technical field of grid-connected photovoltaic power generation, particularly relates to a three-phase grid-connected photovoltaic inverter, and provides a grid-connected control strategy without impulse current.
Background
With the rapid development of photovoltaic power generation technology, more and more photovoltaic grid-connected inverters are connected to a power grid. Before the grid connection of the photovoltaic grid-connected inverter, an impulse current exists at the moment when the grid-connected relay is closed due to the fact that a potential difference exists between two ends of the grid-connected relay (as shown in fig. 4). The impact current generally exceeds the rated current, the service life of the grid-connected relay is greatly reduced, and the problems of fluctuation of the grid voltage, false triggering of the leakage protector and the like can be caused.
For the impact current, there are two main current solutions:
(1) and detecting the closing response time of the grid-connected relay, and closing the relay at the zero crossing point according to the current power grid voltage phase. Due to the fact that the relay is closed and bounces, the relay closing response time calculation has deviation, the closing moment is caused to fluctuate at the zero crossing point of the power grid voltage, and the impact current still exists.
(2) And detecting the phase voltage of the power grid in real time, working in an off-grid mode before closing the relay to output an inverter voltage with the same phase and amplitude as the power grid, and switching to a grid-connected mode after switching on. The method has the advantages that the switching process is complex, the switching time is difficult to determine, and in addition, the problem that phase voltage sampling cannot be connected to a triangular power grid exists.
Therefore, the existing method cannot well solve the problem of impact current when the photovoltaic grid-connected inverter is connected to the grid.
Disclosure of Invention
The invention aims to provide a three-phase photovoltaic grid-connected inverter non-impact current grid-connected control method which can solve the problem of impact current when a photovoltaic grid-connected inverter is connected.
In order to achieve the purpose, the invention adopts the technical scheme that:
a three-phase photovoltaic grid-connected inverter non-impact current grid-connected control method is used for realizing grid connection of a three-phase photovoltaic grid-connected inverter, and the three-phase photovoltaic grid-connected inverter non-impact current grid-connected control method comprises the following steps: before the three-phase photovoltaic grid-connected inverter is switched on, acquiring a line voltage at the power grid side and a line voltage at the inversion side of the three-phase photovoltaic grid-connected inverter, and calculating according to the line voltage at the power grid side and the line voltage at the inversion side of the three-phase photovoltaic grid-connected inverter to obtain a D-axis voltage component Ud _ grid and a Q-axis voltage component Uq _ grid of the voltage at the power grid side of the three-phase photovoltaic grid-connected inverter in a DQ synchronous rotating coordinate system and a D-axis voltage component Ud _ inverter and a Q-axis voltage component Uq _ inverter of the voltage at the inversion side of the three-phase photovoltaic grid-connected inverter in the DQ synchronous rotating coordinate system, so as to obtain a driving pulse required by carrying out power grid voltage feedforward current inner loop decoupling control on the three-phase photovoltaic grid-connected inverter, and carrying out power grid voltage feedforward current inner loop decoupling control on the three-phase photovoltaic grid-connected inverter through the driving pulse; when the difference value between a D-axis voltage component Ud _ grid of the voltage on the power grid side of the three-phase photovoltaic grid-connected inverter in a DQ synchronous rotation coordinate system and a D-axis voltage component Ud _ invert of the voltage on the inversion side in the DQ synchronous rotation coordinate system is smaller than a preset D-axis threshold Ud _ close, and the difference value between a Q-axis voltage component Uq _ grid of the voltage on the power grid side of the three-phase photovoltaic grid-connected inverter in the DQ synchronous rotation coordinate system and a Q-axis voltage component Uq _ invert of the voltage on the inversion side in the DQ synchronous rotation coordinate system is smaller than a preset Q-axis threshold Uq _ close and the duration time is longer than a set first time threshold T1, closing a grid-side relay of the three-phase photovoltaic grid-connected inverter to complete grid-closing.
Preferably, the D-axis voltage component Ud _ grid and the Q-axis voltage component Uq _ grid of the grid-side voltage of the three-phase photovoltaic grid-connected inverter in the DQ synchronous rotation coordinate system, and the D-axis voltage component Ud _ invert and the Q-axis voltage component Uq _ invert of the inversion-side voltage of the three-phase photovoltaic grid-connected inverter in the DQ synchronous rotation coordinate system are calculated by the following steps:
step a 1: according to
Ur_grid＝(2*Urs_grid+Ust_grid)/3
Us_grid＝(Ust_grid-Urs_grid)/3
Ut_grid＝-(Ur_grid+Us_grid)
Ur_invert＝(2*Urs_invert+Ust_invert)/3
Us_invert＝(Ust_invert-Urs_invert)/3
Ut_invert＝-(Ur_invert+Us_invert)
Calculating an R phase voltage Ur _ grid, an S phase voltage Us _ grid and a T phase voltage Ut _ grid at the power grid side of the three-phase photovoltaic grid-connected inverter, and an R phase voltage Ur _ inverter, an S phase voltage Us _ inverter and a T phase voltage Ut _ inverter at the inverter side; urs _ grid is the RS line voltage of the power grid side of the three-phase photovoltaic grid-connected inverter, Ust _ grid is the ST line voltage of the power grid side of the three-phase photovoltaic grid-connected inverter, Urs _ inverter is the RS line voltage of the inversion side of the three-phase photovoltaic grid-connected inverter, and Ust _ inverter is the ST line voltage of the inversion side of the three-phase photovoltaic grid-connected inverter;
step a 2: calculating a Grid _ phase of a power Grid side of the three-phase photovoltaic Grid-connected inverter;
step a 3: calculating a D-axis voltage component Ud _ Grid and a Q-axis voltage component Uq _ Grid of the voltage on the power Grid side of the three-phase photovoltaic Grid-connected inverter under a DQ synchronous rotation coordinate system according to an R-phase voltage Ur _ Grid, an S-phase voltage Us _ Grid and a T-phase voltage Ut _ Grid of the power Grid side of the three-phase photovoltaic Grid-connected inverter and a phase Grid _ phase of the power Grid side; and calculating a D-axis voltage component Ud _ invert and a Q-axis voltage component Uq _ invert of the voltage on the inverting side of the three-phase photovoltaic Grid-connected inverter under a DQ synchronous rotation coordinate system according to the R-phase voltage Ur _ invert, the S-phase voltage Us _ invert, the T-phase voltage Ut _ invert and the Grid-phase on the power Grid side of the three-phase photovoltaic Grid-connected inverter.
Preferably, the Grid _ phase of the Grid side of the three-phase photovoltaic Grid-connected inverter is obtained through a three-phase-locked loop algorithm.
Preferably, the driving pulse required for performing power grid voltage feedforward current inner loop decoupling control on the three-phase photovoltaic grid-connected inverter is obtained through the following steps:
step b 1: performing proportional integral control on a difference value between a D-axis voltage component Ud _ grid of the voltage of the power grid side of the three-phase photovoltaic grid-connected inverter in a DQ synchronous rotation coordinate system and a D-axis voltage component Ud _ inverter of the voltage of the inversion side in the DQ synchronous rotation coordinate system to output a reference Id _ ref of a D-axis current inner ring; performing proportional integral control on a difference value between a Q-axis voltage component Uq _ grid of the voltage on the power grid side of the three-phase photovoltaic grid-connected inverter in a DQ synchronous rotation coordinate system and a Q-axis voltage component Uq _ inverter of the voltage on the inversion side in the DQ synchronous rotation coordinate system to output a reference Iq _ ref of a Q-axis current inner ring;
step b 2: calculating a D-axis current component Id and a Q-axis current component Iq of the current on the inverting side of the three-phase photovoltaic Grid-connected inverter under a DQ synchronous rotation coordinate system according to the three-phase current and the phase Grid _ phase on the inverting side of the three-phase photovoltaic Grid-connected inverter;
step b 3: carrying out proportional integral control on a difference value of a D-axis current component Id of current on an inverter side of the three-phase photovoltaic grid-connected inverter in a DQ synchronous rotation coordinate system and a reference Id _ ref of the D-axis current inner ring to obtain a D-axis output current Id _ out; performing proportional integral control on a difference value of a Q-axis current component Iq of current on an inverter side of the three-phase photovoltaic grid-connected inverter in a DQ synchronous rotation coordinate system and a reference Iq _ ref of the Q-axis current inner ring to obtain a Q-axis output current Iq _ out;
step b 4: according to
UD＝Ud_grid+Id_out-Iq*W*L
UQ＝Uq_grid+Iq_out-Id*W*L
Calculating the three-phase photovoltaic grid-connected inverterD-axis voltage U required for carrying out decoupling control on voltage feedforward current inner loop of power gridDAnd Q-axis voltage UQWherein W is the angular frequency of the power grid, and L is the inductance of the inverter inductor;
step b 5: d-axis voltage U required for carrying out power grid voltage feedforward current inner loop decoupling control on three-phase photovoltaic grid-connected inverterDAnd Q-axis voltage UQCarrying out inverse Park conversion to obtain UαAnd UβTo U, to UαAnd UβPerforming anti-Clarke transformation to obtain a modulation voltage UA、UB、UCTo the modulation voltage UA、UB、UCSPWM modulation is carried out to obtain the required driving pulse.
Preferably, the first time threshold T1 is 100 ms.
Preferably, when the holding time after closing the grid-side relay of the three-phase photovoltaic grid-connected inverter reaches a preset second time threshold T2, the three-phase photovoltaic grid-connected inverter is switched to a normal grid-connected mode.
Preferably, the second time threshold T2 is 100 ms.
Due to the application of the technical scheme, compared with the prior art, the invention has the following advantages: the invention provides a grid-connected control strategy without impulse current aiming at the problem of overlarge impulse current of the photovoltaic grid-connected inverter at the grid-connected time, solves a series of problems of component service life reduction caused by the existence of grid-connected impulse current, overlarge leakage current caused by the impact of a power grid and the like, and is compatible with a triangular power grid and a star-shaped power grid by adopting line voltage sampling.
Drawings
Fig. 1 is a primary side loop and a control topology schematic diagram of an inverter of the three-phase photovoltaic grid-connected inverter non-impact current grid-connected control method.
Fig. 2 is a flow schematic diagram of a three-phase photovoltaic grid-connected inverter non-impact current grid-connected control method of the invention.
Fig. 3 is an effect schematic diagram of the three-phase photovoltaic grid-connected inverter non-impact current grid-connected control method of the invention.
Fig. 4 is a schematic diagram of the inrush current existing at the moment when the grid-connected relay is closed.
Detailed Description
The invention will be further described with reference to examples of embodiments shown in the drawings to which the invention is attached.
The first embodiment is as follows: as shown in the attached drawings 1 and 2, the method for controlling the three-phase photovoltaic grid-connected inverter without impact current comprises the following steps: before the three-phase photovoltaic grid-connected inverter is switched on, acquiring a line voltage at the power grid side and a line voltage at the inversion side of the three-phase photovoltaic grid-connected inverter, and calculating according to the line voltage at the power grid side and the line voltage at the inversion side of the three-phase photovoltaic grid-connected inverter to obtain a D-axis voltage component Ud _ grid and a Q-axis voltage component Uq _ grid of the voltage at the power grid side of the three-phase photovoltaic grid-connected inverter in a DQ synchronous rotating coordinate system and a D-axis voltage component Ud _ inverter and a Q-axis voltage component Uq _ inverter of the voltage at the inversion side of the three-phase photovoltaic grid-connected inverter in the DQ synchronous rotating coordinate system, so as to obtain a driving pulse required by carrying out power grid voltage feedforward current inner loop decoupling control on the three-phase photovoltaic grid-connected inverter, and carrying out power grid voltage feedforward current inner loop decoupling control on the three-phase photovoltaic grid-connected inverter through the driving pulse; when the difference value between a D-axis voltage component Ud _ grid of the voltage on the power grid side of the three-phase photovoltaic grid-connected inverter in a DQ synchronous rotation coordinate system and a D-axis voltage component Ud _ inverter of the voltage on the inversion side in the DQ synchronous rotation coordinate system is smaller than a preset D-axis threshold Ud _ close, the difference value between a Q-axis voltage component Uq _ grid of the voltage on the power grid side of the three-phase photovoltaic grid-connected inverter in the DQ synchronous rotation coordinate system and a Q-axis voltage component Uq _ inverter of the voltage on the inversion side in the DQ synchronous rotation coordinate system is smaller than a preset Q-axis threshold Uq _ close, and the duration time is longer than a set first time threshold T1, a grid-side relay of the three-phase photovoltaic grid-connected inverter is closed, and closing and grid connection are completed.
The three-phase photovoltaic grid-connected inverter non-impact current grid-connected control method is specifically realized by the following steps:
step 1: after the three-phase photovoltaic grid-connected inverter Is electrified and before the three-phase photovoltaic grid-connected inverter Is switched on, acquiring the line voltage of the grid side and the line voltage of the inversion side of the three-phase photovoltaic grid-connected inverter, and acquiring the three-phase current of the grid side of the three-phase photovoltaic grid-connected inverter at the same time, wherein the three-phase current comprises R-phase current Ir _ grid of the grid side, S-phase current IS _ grid of the grid side and T-phase current It _ grid of the grid side.
The three-phase photovoltaic grid-connected inverter is connected to the power grid, the triangular power grid does not have N lines, phase voltage cannot be obtained, and the line voltage is used for control so as to be compatible with the triangular power grid and the star power grid.
Generally, the line voltage of the grid side of the three-phase photovoltaic grid-connected inverter comprises an RS line voltage Urs _ grid of the grid side, an ST line voltage Ust _ grid of the grid side, and a TR line voltage Utr _ grid of the grid side; the line voltage of the inversion side of the three-phase photovoltaic grid-connected inverter comprises an RS line voltage Urs _ inverter of the inversion side, an ST line voltage Ust _ inverter of the inversion side and a TR line voltage Utr _ inverter of the inversion side. In this embodiment, due to the adopted calculation method, only the RS line voltage Urs _ grid on the grid side, the ST line voltage Ust _ grid on the grid side, the RS line voltage Urs _ inverter on the inverter side, and the ST line voltage Ust _ inverter on the inverter side need to be obtained.
Step 2: calculating to obtain a D-axis voltage component Ud _ grid and a Q-axis voltage component Uq _ grid of the voltage of the power grid side of the three-phase photovoltaic grid-connected inverter in a DQ synchronous rotation coordinate system and a D-axis voltage component Ud _ inverter and a Q-axis voltage component Uq _ inverter of the voltage of the inversion side of the three-phase photovoltaic grid-connected inverter in the DQ synchronous rotation coordinate system through the following steps:
step a 1: according to
Ur_grid＝(2*Urs_grid+Ust_grid)/3
Us_grid＝(Ust_grid-Urs_grid)/3
Ut_grid＝-(Ur_grid+Us_grid)
Ur_invert＝(2*Urs_invert+Ust_invert)/3
Us_invert＝(Ust_invert-Urs_invert)/3
Ut_invert＝-(Ur_invert+Us_invert)
And calculating an R phase voltage Ur _ grid, an S phase voltage Us _ grid and a T phase voltage Ut _ grid on the power grid side of the three-phase photovoltaic grid-connected inverter, and an R phase voltage Ur _ inverter, an S phase voltage Us _ inverter and a T phase voltage Ut _ inverter on the inverter side.
Step a 2: and the phase-locked loop on the relay power Grid side of the three-phase photovoltaic Grid-connected inverter starts to work, and the Grid _ phase on the power Grid side of the three-phase photovoltaic Grid-connected inverter is obtained through calculation of a three-phase-locked loop algorithm.
Step a 3: a phase-locked loop on the relay Grid side of the three-phase photovoltaic Grid-connected inverter calculates a D-axis voltage component Ud _ Grid and a Q-axis voltage component Uq _ Grid of the voltage on the Grid side of the three-phase photovoltaic Grid-connected inverter under a DQ synchronous rotation coordinate system according to an R-phase voltage Ur _ Grid, an S-phase voltage Us _ Grid and a T-phase voltage Ut _ Grid of the Grid side of the three-phase photovoltaic Grid-connected inverter and a Grid-phase voltage Uq _ phase of the Grid side; and calculating a D-axis voltage component Ud _ invert and a Q-axis voltage component Uq _ invert of the voltage on the inverting side of the three-phase photovoltaic Grid-connected inverter under a DQ synchronous rotation coordinate system according to the R-phase voltage Ur _ invert, the S-phase voltage Us _ invert, the T-phase voltage Ut _ invert and the Grid-phase on the power Grid side of the three-phase photovoltaic Grid-connected inverter.
And step 3: the method comprises the following steps of obtaining a driving pulse required for carrying out power grid voltage feedforward current inner loop decoupling control on the three-phase photovoltaic grid-connected inverter, and thus carrying out power grid voltage feedforward current inner loop decoupling control on the three-phase photovoltaic grid-connected inverter by using the driving pulse:
step b 1: performing proportional integral control on a difference value between a D-axis voltage component Ud _ grid of a voltage on a power grid side of the three-phase photovoltaic grid-connected inverter in a DQ synchronous rotation coordinate system and a D-axis voltage component Ud _ inverter of a voltage on an inversion side in the DQ synchronous rotation coordinate system to output a reference Id _ ref of a D-axis current inner ring; and performing proportional integral control on a difference value between a Q-axis voltage component Uq _ grid of the voltage on the power grid side of the three-phase photovoltaic grid-connected inverter in a DQ synchronous rotation coordinate system and a Q-axis voltage component Uq _ inverter of the voltage on the inversion side in the DQ synchronous rotation coordinate system, and outputting to obtain a reference Iq _ ref of a Q-axis current inner ring.
Step b 2: the phase-locked loop on the relay power Grid side of the three-phase photovoltaic Grid-connected inverter calculates a D-axis current component Id and a Q-axis current component Iq of current on the inversion side of the three-phase photovoltaic Grid-connected inverter in a DQ synchronous rotating coordinate system according to three-phase current (R-phase current Ir _ Grid on the power Grid side, S-phase current Is _ Grid on the power Grid side and T-phase current It _ Grid on the power Grid side) on the inversion side of the three-phase photovoltaic Grid-connected inverter and phase Grid _ phase. The above step b1 and step b2 can reverse the front-to-back order.
Step b 3: carrying out proportional integral control on a difference value of a D-axis current component Id of current on an inversion side of the three-phase photovoltaic grid-connected inverter in a DQ synchronous rotation coordinate system and a reference Id _ ref of a D-axis current inner ring to obtain a D-axis output current Id _ out; and performing proportional integral control on the difference value of a Q-axis current component Iq of the current on the inverter side of the three-phase photovoltaic grid-connected inverter in a DQ synchronous rotation coordinate system and a reference Iq _ ref of a Q-axis current inner ring to obtain a Q-axis output current Iq _ out.
Step b 4: according to
UD＝Ud_grid+Id_out-Iq*W*L
UQ＝Uq_grid+Iq_out-Id*W*L
Calculating D-axis voltage U required for carrying out power grid voltage feedforward current inner loop decoupling control on three-phase photovoltaic grid-connected inverterDAnd Q-axis voltage UQWherein W is the angular frequency of the power grid, and L is the inductance of the inverter inductor.
Step b 5: d-axis voltage U required for carrying out power grid voltage feedforward current inner loop decoupling control on three-phase photovoltaic grid-connected inverterDAnd Q-axis voltage UQCarrying out inverse Park conversion to obtain UαAnd UβTo U, to UαAnd UβPerforming anti-Clarke transformation to obtain a modulation voltage UA、UB、UCTo the modulation voltage UA、UB、UCSPWM modulation is carried out to obtain the required driving pulse. And performing power grid voltage feedforward current inner loop decoupling control on the three-phase photovoltaic grid-connected inverter by using the driving pulse.
And 4, step 4: and a CPU of the three-phase photovoltaic grid-connected inverter detects and compares a difference value of a D-axis voltage component Ud _ grid of a voltage on the power grid side of the three-phase photovoltaic grid-connected inverter in a DQ synchronous rotating coordinate system and a D-axis voltage component Ud _ invert of a voltage on the inverting side in the DQ synchronous rotating coordinate system, and a difference value of a Q-axis voltage component Uq _ grid of the voltage on the power grid side of the three-phase photovoltaic grid-connected inverter in the DQ synchronous rotating coordinate system and a Q-axis voltage component Uq _ invert of the voltage on the inverting side in the DQ synchronous rotating coordinate system.
When the difference between a D-axis voltage component Ud _ grid of the voltage on the power grid side of the three-phase photovoltaic grid-connected inverter in a DQ synchronous rotation coordinate system and a D-axis voltage component Ud _ inverter of the voltage on the inversion side in the DQ synchronous rotation coordinate system is smaller than a preset D-axis threshold Ud _ close, and the difference between a Q-axis voltage component Uq _ grid of the voltage on the power grid side of the three-phase photovoltaic grid-connected inverter in the DQ synchronous rotation coordinate system and a Q-axis voltage component Uq _ inverter of the voltage on the inversion side in the DQ synchronous rotation coordinate system is smaller than a preset Q-axis threshold Uq _ close and the duration is longer than a set first time threshold T1 (for example 100ms), a grid-side relay of the three-phase photovoltaic grid-connected inverter is closed, and the grid connection is completed. No inrush current is generated at this time as shown in fig. 3.
And 5: when the holding time reaches a preset second time threshold T2 (for example, 100ms) after closing the grid-side relay of the three-phase photovoltaic grid-connected inverter, switching the three-phase photovoltaic grid-connected inverter to the normal grid-connected mode (for example, in fig. 3, the grid-connected switching can be completed by directly switching the current inner loop reference setting without pulse sealing).
In summary, the general core idea of the scheme is as follows: the method comprises the steps of obtaining line voltage information of two ends of a grid-connected relay before the grid-connected relay is switched on, carrying out closed-loop inversion on a voltage with an amplitude value and a phase equal voltage according to a grid-side voltage, then switching on the relay, using the same control strategy before and after the relay is switched on, wherein the control strategy is power grid voltage feedforward current inner loop decoupling control, and the difference before and after the relay is switched on is current inner loop current reference setting.
The method mainly comprises four parts: (1) the phase locking part: the phase lock is mainly used for locking the Grid _ phase of the power Grid voltage and carrying out DQ conversion on the inverter side voltage, the power Grid side voltage and the power Grid current according to the Grid _ phase; (2) an amplitude adjusting section: performing closed-loop regulation on the D-axis voltage Ud _ inverter output by the inverter according to the power grid D-axis voltage Ud _ grid in a DQ coordinate system; (3) a phase adjusting section: performing closed-loop regulation on Q-axis voltage Ud _ inverter output by the inverter according to power grid Q-axis voltage Uq _ grid in a DQ coordinate system; (4) a relay closing part: when the CPU detects that the difference values of D-axis components Ud _ grid, Ud _ inverse, Q-axis components Uq _ grid and Uq _ inverse of voltages at two ends of the relay under a DQ synchronous rotating coordinate system are respectively smaller than thresholds Ud _ close and Uq _ close for more than 100ms, the network side relay is closed, the time after the relay is closed lasts for 100ms to ensure that the relay is completely closed, and the normal network connection mode is switched.
The method uses a line voltage sampling mode, is suitable for triangular and star-shaped power grids, uses a power grid voltage feedforward current inner loop decoupling control strategy for inversion control, can adapt to various weak power grids with power grid voltage distortion, keeps the control strategies consistent before and after grid connection to avoid current impact caused by control strategy switching, and achieves the aim of grid connection of a grid-connected inverter without impact current, as shown in figure 3.
The above embodiments are merely illustrative of the technical ideas and features of the present invention, and the purpose thereof is to enable those skilled in the art to understand the contents of the present invention and implement the present invention, and not to limit the protection scope of the present invention. All equivalent changes and modifications made according to the spirit of the present invention should be covered within the protection scope of the present invention.

Claims (6)

1. A three-phase photovoltaic grid-connected inverter non-impact current grid-connected control method is used for realizing grid connection of the three-phase photovoltaic grid-connected inverter and is characterized in that: the three-phase photovoltaic grid-connected inverter non-impact current grid-connected control method comprises the following steps: before the three-phase photovoltaic grid-connected inverter is switched on, acquiring a line voltage at the power grid side and a line voltage at the inversion side of the three-phase photovoltaic grid-connected inverter, and calculating according to the line voltage at the power grid side and the line voltage at the inversion side of the three-phase photovoltaic grid-connected inverter to obtain a D-axis voltage component Ud _ grid and a Q-axis voltage component Uq _ grid of the voltage at the power grid side of the three-phase photovoltaic grid-connected inverter in a DQ synchronous rotating coordinate system and a D-axis voltage component Ud _ inverter and a Q-axis voltage component Uq _ inverter of the voltage at the inversion side of the three-phase photovoltaic grid-connected inverter in the DQ synchronous rotating coordinate system, so as to obtain a driving pulse required by carrying out power grid voltage feedforward current inner loop decoupling control on the three-phase photovoltaic grid-connected inverter, and carrying out power grid voltage feedforward current inner loop decoupling control on the three-phase photovoltaic grid-connected inverter through the driving pulse; when the difference between a D-axis voltage component Ud _ grid of the voltage at the power grid side of the three-phase photovoltaic grid-connected inverter in a DQ synchronous rotation coordinate system and a D-axis voltage component Ud _ invert of the voltage at the inversion side in the DQ synchronous rotation coordinate system is smaller than a preset D-axis threshold Ud _ close, and the difference between a Q-axis voltage component Uq _ grid of the voltage at the power grid side of the three-phase photovoltaic grid-connected inverter in the DQ synchronous rotation coordinate system and a Q-axis voltage component Uq _ invert of the voltage at the inversion side in the DQ synchronous rotation coordinate system is smaller than a preset Q-axis threshold Uq _ close and the duration is longer than a set first time threshold T1, closing a grid-side relay of the three-phase photovoltaic grid-connected inverter to complete grid-connection and closing;
the method comprises the following steps of obtaining driving pulses required for carrying out power grid voltage feedforward current inner loop decoupling control on the three-phase photovoltaic grid-connected inverter:
step b 1: performing proportional integral control on a difference value between a D-axis voltage component Ud _ grid of the voltage of the power grid side of the three-phase photovoltaic grid-connected inverter in a DQ synchronous rotation coordinate system and a D-axis voltage component Ud _ inverter of the voltage of the inversion side in the DQ synchronous rotation coordinate system to output a reference Id _ ref of a D-axis current inner ring; performing proportional integral control on a difference value between a Q-axis voltage component Uq _ grid of the voltage on the power grid side of the three-phase photovoltaic grid-connected inverter in a DQ synchronous rotation coordinate system and a Q-axis voltage component Uq _ inverter of the voltage on the inversion side in the DQ synchronous rotation coordinate system to output a reference Iq _ ref of a Q-axis current inner ring;
step b 2: calculating a D-axis current component Id and a Q-axis current component Iq of the current on the inverting side of the three-phase photovoltaic Grid-connected inverter under a DQ synchronous rotation coordinate system according to the three-phase current and the phase Grid _ phase on the inverting side of the three-phase photovoltaic Grid-connected inverter;
step b 3: carrying out proportional integral control on a difference value of a D-axis current component Id of current on an inverter side of the three-phase photovoltaic grid-connected inverter in a DQ synchronous rotation coordinate system and a reference Id _ ref of the D-axis current inner ring to obtain a D-axis output current Id _ out; performing proportional integral control on a difference value of a Q-axis current component Iq of current on an inverter side of the three-phase photovoltaic grid-connected inverter in a DQ synchronous rotation coordinate system and a reference Iq _ ref of the Q-axis current inner ring to obtain a Q-axis output current Iq _ out;
step b 4: according to
UD＝Ud_grid+Id_out-Iq*W*L
UQ＝Uq_grid+Iq_out-Id*W*L
Calculating D-axis voltage U required for carrying out power grid voltage feedforward current inner loop decoupling control on the three-phase photovoltaic grid-connected inverterDAnd Q-axis voltage UQWherein W is the angular frequency of the power grid, and L is the inductance of the inverter inductor;
step b 5: d-axis voltage U required for carrying out power grid voltage feedforward current inner loop decoupling control on three-phase photovoltaic grid-connected inverterDAnd Q-axis voltage UQCarrying out inverse Park conversion to obtain UαAnd UβTo U, to UαAnd UβPerforming anti-Clarke transformation to obtain a modulation voltage UA、UB、UCTo the modulation voltage UA、UB、UCSPWM modulation is carried out to obtain the required driving pulse.
2. The three-phase photovoltaic grid-connected inverter non-impact current grid-connected control method according to claim 1, characterized in that: calculating a D-axis voltage component Ud _ grid and a Q-axis voltage component Uq _ grid of the voltage of the power grid side of the three-phase photovoltaic grid-connected inverter in a DQ synchronous rotation coordinate system, and a D-axis voltage component Ud _ inverter and a Q-axis voltage component Uq _ inverter of the voltage of the inversion side of the three-phase photovoltaic grid-connected inverter in the DQ synchronous rotation coordinate system by the following steps:
step a 1: according to
Ur_grid＝(2*Urs_grid+Ust_grid)/3
Us_grid＝(Ust_grid-Urs_grid)/3
Ut_grid＝-(Ur_grid+Us_grid)
Ur_invert＝(2*Urs_invert+Ust_invert)/3
Us_invert＝(Ust_invert-Urs_invert)/3
Ut_invert＝-(Ur_invert+Us_invert)
Calculating an R phase voltage Ur _ grid, an S phase voltage Us _ grid and a T phase voltage Ut _ grid at the power grid side of the three-phase photovoltaic grid-connected inverter, and an R phase voltage Ur _ inverter, an S phase voltage Us _ inverter and a T phase voltage Ut _ inverter at the inverter side; urs _ grid is the RS line voltage of the power grid side of the three-phase photovoltaic grid-connected inverter, Ust _ grid is the ST line voltage of the power grid side of the three-phase photovoltaic grid-connected inverter, Urs _ inverter is the RS line voltage of the inversion side of the three-phase photovoltaic grid-connected inverter, and Ust _ inverter is the ST line voltage of the inversion side of the three-phase photovoltaic grid-connected inverter;
step a 2: calculating a Grid _ phase of a power Grid side of the three-phase photovoltaic Grid-connected inverter;
step a 3: calculating a D-axis voltage component Ud _ Grid and a Q-axis voltage component Uq _ Grid of the voltage on the power Grid side of the three-phase photovoltaic Grid-connected inverter under a DQ synchronous rotation coordinate system according to an R-phase voltage Ur _ Grid, an S-phase voltage Us _ Grid and a T-phase voltage Ut _ Grid of the power Grid side of the three-phase photovoltaic Grid-connected inverter and a phase Grid _ phase of the power Grid side; and calculating a D-axis voltage component Ud _ invert and a Q-axis voltage component Uq _ invert of the voltage on the inverting side of the three-phase photovoltaic Grid-connected inverter under a DQ synchronous rotation coordinate system according to the R-phase voltage Ur _ invert, the S-phase voltage Us _ invert, the T-phase voltage Ut _ invert and the Grid-phase on the power Grid side of the three-phase photovoltaic Grid-connected inverter.
3. The three-phase photovoltaic grid-connected inverter non-impact current grid-connected control method according to claim 2, characterized in that: and obtaining the Grid _ phase of the power Grid side of the three-phase photovoltaic Grid-connected inverter through a three-phase-locked loop algorithm.
4. The three-phase photovoltaic grid-connected inverter non-impact current grid-connected control method according to claim 1, characterized in that: the first time threshold T1 is 100 ms.
5. The three-phase photovoltaic grid-connected inverter non-impact current grid-connected control method according to claim 1, characterized in that: and when the holding time reaches a preset second time threshold T2 after the grid-side relay of the three-phase photovoltaic grid-connected inverter is closed, switching the three-phase photovoltaic grid-connected inverter into a normal grid-connected mode.
6. The three-phase photovoltaic grid-connected inverter non-impact current grid-connected control method according to claim 5, characterized in that: the second time threshold T2 is 100 ms.
CN201810216669.2A 2018-03-12 2018-03-12 Three-phase photovoltaic grid-connected inverter non-impact current grid-connected control method Active CN108365628B (en)

Priority Applications (2)

Application Number Priority Date Filing Date Title
CN201810216669.2A CN108365628B (en) 2018-03-12 2018-03-12 Three-phase photovoltaic grid-connected inverter non-impact current grid-connected control method
PCT/CN2018/120027 WO2019174331A1 (en) 2018-03-12 2018-12-10 Impact-current-free grid-connected control method for three-phase photovoltaic grid-connected inverter

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
CN201810216669.2A CN108365628B (en) 2018-03-12 2018-03-12 Three-phase photovoltaic grid-connected inverter non-impact current grid-connected control method

Publications (2)

Publication Number Publication Date
CN108365628A CN108365628A (en) 2018-08-03
CN108365628B true CN108365628B (en) 2022-01-14

Family

ID=63000417

Family Applications (1)

Application Number Title Priority Date Filing Date
CN201810216669.2A Active CN108365628B (en) 2018-03-12 2018-03-12 Three-phase photovoltaic grid-connected inverter non-impact current grid-connected control method

Country Status (2)

Country Link
CN (1) CN108365628B (en)
WO (1) WO2019174331A1 (en)

Families Citing this family (11)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN108365628B (en) * 2018-03-12 2022-01-14 固德威技术股份有限公司 Three-phase photovoltaic grid-connected inverter non-impact current grid-connected control method
CN109217376B (en) * 2018-10-12 2020-07-07 西安许继电力电子技术有限公司 Synchronous switching-on control method of subway brake feedback converter
CN109557491B (en) * 2018-12-17 2021-11-09 江苏固德威电源科技股份有限公司 Three-phase voltage sampling correction method and inverter applying same
CN109946599B (en) * 2019-03-28 2021-08-27 爱士惟新能源技术(江苏)有限公司 Method and device for detecting relay before grid connection of photovoltaic three-phase inverter and storage medium
CN110957763A (en) * 2019-12-30 2020-04-03 国网陕西省电力公司安康供电公司 Two-stage type photovoltaic grid-connected power generation system and control method thereof
CN112671032A (en) * 2020-12-14 2021-04-16 广西电网有限责任公司电力科学研究院 Grid-connected steady-state starting method and device for photovoltaic power generation system
CN112731874B (en) * 2020-12-21 2022-05-20 深圳市海浦蒙特科技有限公司 Power-off shutdown control method and device for industrial control equipment
CN113162111B (en) * 2021-03-30 2022-05-31 中国能源建设集团华中电力试验研究院有限公司 Method and system for reducing reactive impact in power plant grid connection process
CN114513011B (en) * 2022-02-21 2022-08-30 西南交通大学 Grid-connected control method of flexible traction power supply system based on satellite communication mode
CN114567014B (en) * 2022-04-29 2022-07-15 武汉大学 Flexible change-over switch with voltage supporting function and control method thereof
CN115776130B (en) * 2022-12-29 2024-02-02 北京索英电气技术股份有限公司 Off-grid switching method, energy storage converter, energy storage system and power system

Citations (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN104218605A (en) * 2014-08-28 2014-12-17 天津大学 Non-impact-current grid connection method for three-phase voltage source grid-connected inverters

Family Cites Families (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN102780414B (en) * 2012-01-13 2014-12-24 广东志成冠军集团有限公司 Device and method for inhibiting inrush starting current for large-power grid-connected inverter
CN102723727B (en) * 2012-04-27 2014-10-29 江苏吉泰科电气股份有限公司 Grid connection control method of double-fed wind-driven generator
CN105811751B (en) * 2014-12-29 2018-08-14 国家电网公司 A kind of unlock startup control method of flexible direct-current transmission converter
CN106655270B (en) * 2016-12-29 2019-06-18 华中科技大学 Inhibit the control method of three-phase LCL type grid-connection converter rectification inrush current
CN106655272B (en) * 2017-01-16 2018-12-04 湖南大学 Inhibit failure temporary impact current mode virtual synchronous inverter and its control method
CN108365628B (en) * 2018-03-12 2022-01-14 固德威技术股份有限公司 Three-phase photovoltaic grid-connected inverter non-impact current grid-connected control method

Patent Citations (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN104218605A (en) * 2014-08-28 2014-12-17 天津大学 Non-impact-current grid connection method for three-phase voltage source grid-connected inverters

Also Published As

Publication number Publication date
CN108365628A (en) 2018-08-03
WO2019174331A1 (en) 2019-09-19

Similar Documents

Publication Publication Date Title
CN108365628B (en) Three-phase photovoltaic grid-connected inverter non-impact current grid-connected control method
Ochs et al. A method of seamless transitions between grid-tied and stand-alone modes of operation for utility-interactive three-phase inverters
CN110048455B (en) Droop control inverter with weak grid fault ride-through capability and control method thereof
US20170047862A1 (en) Steady state control method for three-phase double-mode inverter
CN111416393A (en) Virtual synchronous generator fault current suppression method based on self-adaptive virtual impedance
CN103645404A (en) Micro-grid islanding detection method
CN110231545B (en) Island detection method and reference current extreme value calculation method for alternating current-direct current series-parallel power grid
CN111769591A (en) Double-mode combined control method for multi-inverter system based on double split transformers
CN112104000A (en) Novel double-closed-loop linear active disturbance rejection control method for energy storage grid-connected inverter
CN110098640B (en) Low-voltage ride through control method and device of photovoltaic grid-connected system
CN107196327B (en) Feedforward control method for restraining power oscillation of modular voltage source type converter valve
CN101702583A (en) Method for controlling direct-drive wind power generation convertor
CN112448388A (en) Control method of power conversion and supply system based on parallel connection of intelligent soft switch and interconnection switch
CN111245277B (en) Grid-connected inverter starting method, photovoltaic power generation system and terminal equipment
CN108462197B (en) Starting control method and device for flexible direct-current transmission converter valve
CN112018804A (en) AC-DC hybrid micro-grid coupling inverter cascade control implementation method
CN110445406B (en) Dual-mode smooth transition control method of PWM rectifier
CN104218605A (en) Non-impact-current grid connection method for three-phase voltage source grid-connected inverters
CN111669041A (en) Slow start control method for high-power high step-up ratio direct current converter
CN105790295A (en) Grid fault non-communication ride-through control method for double-end flexible direct current power transmission system
Ochs et al. A technique for voltage-source inverter seamless transitions between grid-connected and standalone modes
CN116316697A (en) Dynamic stability enhancement control method of grid-connected converter under weak current network asymmetric short circuit fault
CN113131506B (en) Fixed turn-off angle control method and stabilizer for inhibiting subsequent commutation failure of LCC-HVDC system
Marin et al. Influence of the ICFF decoupling technique on the stability of the current control loop of a grid-tied VSC
CN115224724A (en) Three-phase grid-connected connection method of energy storage system with filter capacitor

Legal Events

Date Code Title Description
PB01 Publication
SE01 Entry into force of request for substantive examination
SE01 Entry into force of request for substantive examination
CB02 Change of applicant information

Address after: 215000 No. 90, Zijin Road, high tech Zone, Suzhou, Jiangsu

Applicant after: Goodway Technology Co.,Ltd.

Address before: 215163 No. 189 Kunlun mountain road, hi tech Zone, Suzhou, Jiangsu

Applicant before: JIANGSU GOODWE POWER SUPPLY TECHNOLOGY Co.,Ltd.

CB02 Change of applicant information
GR01 Patent grant
GR01 Patent grant