CN109167371B - Virtual inductive reactance regulator for realizing reactive power sharing of parallel inverter and control method - Google Patents
Virtual inductive reactance regulator for realizing reactive power sharing of parallel inverter and control method Download PDFInfo
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- CN109167371B CN109167371B CN201811275002.6A CN201811275002A CN109167371B CN 109167371 B CN109167371 B CN 109167371B CN 201811275002 A CN201811275002 A CN 201811275002A CN 109167371 B CN109167371 B CN 109167371B
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Classifications
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- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02J—CIRCUIT ARRANGEMENTS OR SYSTEMS FOR SUPPLYING OR DISTRIBUTING ELECTRIC POWER; SYSTEMS FOR STORING ELECTRIC ENERGY
- H02J3/00—Circuit arrangements for ac mains or ac distribution networks
- H02J3/18—Arrangements for adjusting, eliminating or compensating reactive power in networks
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- H02J3/382—
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- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02J—CIRCUIT ARRANGEMENTS OR SYSTEMS FOR SUPPLYING OR DISTRIBUTING ELECTRIC POWER; SYSTEMS FOR STORING ELECTRIC ENERGY
- H02J2203/00—Indexing scheme relating to details of circuit arrangements for AC mains or AC distribution networks
- H02J2203/20—Simulating, e g planning, reliability check, modelling or computer assisted design [CAD]
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- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02J—CIRCUIT ARRANGEMENTS OR SYSTEMS FOR SUPPLYING OR DISTRIBUTING ELECTRIC POWER; SYSTEMS FOR STORING ELECTRIC ENERGY
- H02J3/00—Circuit arrangements for ac mains or ac distribution networks
- H02J3/38—Arrangements for parallely feeding a single network by two or more generators, converters or transformers
- H02J3/388—Islanding, i.e. disconnection of local power supply from the network
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- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
- Y02E40/00—Technologies for an efficient electrical power generation, transmission or distribution
- Y02E40/30—Reactive power compensation
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Abstract
A virtual inductive reactance regulator for realizing reactive power equipartition of parallel inverters and a control method thereof are provided. The virtual inductance regulator consists of a subtracter, an integrator and an adder. The input of the subtracter is the reactive power output by the inverter and the rated reactive power which should be output by the inverter, and the absolute error of the reactive power is output; the input of the integrator is the absolute error of reactive power, and the self-adaptive part of the virtual inductive reactance is output; the input of the adder is the output of the integrator and the reference virtual inductance, and the virtual inductance is output. The virtual inductive reactance regulator is arranged in a local controller of the inverter, and the local controller and the central controller are interconnected through a low-bandwidth communication line. The invention introduces virtual inductive reactance into each inverter of the low-voltage micro-grid and installs the virtual inductive reactance regulator additionally, adopts reactive power to regulate the magnitude of the virtual inductive reactance, does not need to measure line impedance parameters to achieve line impedance matching, realizes reactive power balance control, does not need extra communication wires between the inverters, and reserves the plug-and-play characteristic of the micro-grid inverter.
Description
Field of the art
The invention belongs to the technical field of micro-grids, relates to reactive power balance distribution when inverters under an island of a low-voltage micro-grid run in parallel, and particularly relates to a virtual inductive reactance regulator for realizing reactive power balance of the inverters in parallel and a control method.
(II) background art
In recent years, a large amount of renewable energy sources are connected into a power grid in the form of a distributed power source, and a micro-grid has been attracting attention because of increasing the permeability of the distributed power source and increasing the reliability of new energy power supply. In the island operation process of the micro-grid, no reference of voltage and frequency is provided for the large grid, and the parallel inverter provides voltage and frequency for the whole grid, so that the inverter influences the electric energy quality of the micro-grid to a great extent. The traditional droop control is a key technology for stably operating the micro-grid in an island mode by adjusting the amplitude and frequency of the output voltage of the inverter to equally divide load power, and has the advantage of plug and play. The conventional droop control considers that the equivalent line impedance of the inverter is inductive, however, in an actual micro-grid, a low-voltage transmission line is generally adopted, the equivalent line impedance is mainly resistive, and if the conventional droop control is still adopted, serious power coupling is caused, so that the operation efficiency of the system is reduced. The virtual impedance method can be used for realizing power decoupling, so that the traditional droop control is still applicable. The line impedance is often mismatched, so that the output voltage difference of the inverter occurs, and a small voltage difference causes a larger reactive power sharing error to cause reactive circulation of the system, which increases system loss and reduces power quality.
Many scholars at home and abroad propose an improvement method: by designing the inverter output impedance to be resistive to reduce power coupling, this approach requires an effective value loop to compensate for the over-gain phenomenon due to the lack of integration terms, which increases the complexity of the system and is not suitable for practical applications; the virtual impedance technology is adopted to match the output impedance of the inverter with the rated capacity, so that reactive power sharing errors can be reduced, and the method needs to detect line impedance parameters, which is a very troublesome and non-operational problem; the reactive power is equally divided by detecting the voltage drop caused by the line impedance and compensating the voltage drop into a power control strategy, and the method has the limitation that compensation parameters are required to be obtained in grid connection before island operation.
(III) summary of the invention
Based on the defects existing in the prior art, the invention aims to provide an improved sagging control technology based on virtual inductive reactance, aiming at the problems of serious power coupling and larger reactive power sharing error caused by the fact that the line impedance of a low-voltage micro-grid is resistive and the line impedance is poor. By adopting the virtual inductive reactance regulator and the control method for realizing reactive power sharing of the parallel inverter, power decoupling and line impedance difference elimination can be realized without detecting line impedance parameters, the advantages of droop control are maintained, reactive power is accurately distributed according to the droop coefficient, and the stability of the micro-grid island in operation is ensured.
The basic idea of the invention is as follows: since low-voltage transmission lines are generally adopted in the micro-grid, the equivalent line impedance of the parallel inverter is mainly resistive, and if the traditional droop control is still adopted, serious power coupling is caused, so that the operation efficiency of the system is reduced. The condition for realizing reactive power sharing is that the equivalent line impedance is matched with the rated output power of the inverter, however, the line impedance is often not matched, the condition for realizing reactive power sharing is difficult to be satisfied, the output voltage difference of the parallel inverters is generated, and the reactive power cannot be distributed accurately. By introducing the reference virtual inductance, the equivalent output impedance of the inverter basically presents the sensitivity at the fundamental frequency (the frequency is 50 Hz), and the equivalent circuit impedance can be designed to be the sensitivity if the reference virtual inductance with a decisive function is introduced, so that the power decoupling is realized, and the traditional droop is still suitable for the environment of the low-voltage microgrid. And the virtual inductance regulator is additionally arranged in the local controller, the output reactive power of the inverter is adopted to regulate the magnitude of the virtual inductance, the line impedance difference is eliminated, the line impedance parameter is not required to be detected, the output voltage difference of the inverter can be reduced, and the power sharing is realized.
The aim of the invention is achieved by the following technical scheme:
the virtual inductive reactance regulator is arranged in a local controller of each inverter of the parallel circuit of the low-voltage micro-grid inverter, and the local controller is interconnected with the micro-grid central controller through a low-bandwidth communication line.
The local controller collects the output voltage u of the inverter to which it is connected o Output current i o And obtaining reactive power Q through power calculation, and transmitting the reactive power Q to the central controller through a low-bandwidth communication line.
The micro-grid central controller collects total reactive power Q total And send to the local controller, which receives the total reactive power Q total For calculating the rated reactive power Q which the inverter should output * 。
The virtual inductance regulator consists of a subtracter, an integrator and an adder.
The subtracter consists of a resistor R 1 ～R 4 Operational amplifier A 1 The input is the reactive power Q output by the inverter and the rated reactive power Q to be output by the inverter * The output is the reactive power difference (Q-Q * )；
The integrator is composed of a resistor R 5 Capacitor C and operational amplifier A 2 Is formed by the input of reactive power difference (Q-Q * ) Adaptive part with virtual inductive reactance outputm is the integrator coefficient;
the adder is composed of a resistor R 6 ～R 9 Operational amplifier A 3 The input is a reference virtual inductance X * And an output section of the integrator outputting as a virtual inductance X v 。
Virtual inductance X output by adder v The expression of (2) is:
wherein s is a Law transformation complex variable operator;
reference virtual inductance X * The equivalent circuit impedance of the inverter is ensured to be inductive, and power decoupling is realized.
Rated reactive power Q to be output by the inverter * The specific expression of (2) is:
wherein k is qe_i 、k qe_j Respectively are provided withReactive power-voltage amplitude droop coefficient, Q for ith and jth inverters i * The rated reactive power to be output by the i-th inverter is indicated.
The control method of the virtual inductive reactance regulator for realizing reactive power sharing of the parallel inverter is adopted: introducing reference virtual inductance X * After the equivalent circuit impedance of the inverter is inductive, a virtual inductive reactance regulator is additionally arranged in a local controller, the output reactive power of the inverter is adopted to regulate the magnitude of the virtual inductive reactance, the circuit impedance difference is eliminated, the circuit impedance parameter is not required to be detected, the output voltage difference of the inverter is reduced, and the power sharing is realized:
the method comprises the following steps:
step 1: the local controller obtains reactive power Q through power calculation and transmits the reactive power Q to the central controller through a communication line;
step 2: by adding reference virtual inductive reactance X * Designing the equivalent circuit impedance of the inverter to be inductive;
step 3: the central controller collects the total reactive power Q total Local controllers sent to each inverter, the local controllers based on Q total Calculating rated reactive power Q to be output by inverter * ；
Step 4: the virtual reactance adjuster of claim 1 obtaining a virtual reactance X with an adaptive section v ；
Step 5: combining X in the step 4 v And sag control is carried out to obtain reference voltage of the output voltage of the inverter, and the output voltage and reactive power of the inverter are regulated through voltage and current double-loop control, so that the inverters share the load.
Step 1 further comprises:
step 1-1: the local controller collects the output voltage u of the inverter o Output current i o ，i o Transformed into i by dq coordinate d 、i q ；
Step 1-2: the inverter output voltage u collected by the local controller is used for controlling the power supply o Phase-shifted by 90 DEG and output current i of inverter o The multiplication results in an instantaneous active power p,inverter output voltage u o And inverter output current i o The instantaneous reactive power Q is obtained through multiplication, the instantaneous active power P and the instantaneous reactive power Q respectively pass through a low-pass filter to obtain average active power P and average reactive power Q, and the frequency omega and the amplitude U of the output voltage of the inverter are obtained through droop control droop ，U droop Transformed into U by dq coordinate droop-d 、U droop-q 。
The expression of the reference voltage difference in the step 5 is:
wherein the method comprises the steps ofFor outputting the voltage reference value->Is included in the (c) dq component of the (c).
The invention has the positive effects that:
(1) The virtual inductive reactance is introduced to realize power decoupling, so that the traditional droop formula can still be used in a low-voltage micro-grid, the reactive power is adopted to adjust the magnitude of virtual impedance, the line impedance can be matched without measuring the line impedance parameter, the accurate distribution of the reactive power is realized, and the power quality is improved.
(2) The central controller in the invention is only interconnected with each inverter, and the inverters are not connected by a communication line, so that the plug-and-play characteristic of the inverters is maintained.
(3) The invention can cope with the condition of abrupt load change, and can equally divide the load power when the load power is changed greatly, so that the amplitude and the frequency of the output voltage of the inverter are maintained in the rated state, and the reliability of power supply is increased.
(IV) description of the drawings
Fig. 1 is a diagram showing a conventional parallel circuit configuration of two inverters.
Fig. 2 is a simplified circuit model of two parallel inverters.
Fig. 3 is a power calculation and droop control block diagram.
Fig. 4 is a schematic diagram of the output voltage after introducing the reference virtual inductance.
Fig. 5 is a bode plot of the equivalent output impedance of the inverter after the reference virtual inductance is introduced.
Fig. 6 is a circuit diagram of a virtual reactance regulator of the present invention.
Fig. 7 is a block diagram showing the overall structure of a local controller in which a virtual reactance adjuster is installed according to the present invention.
Fig. 8-a is a graph of active power simulation results using a conventional droop control method.
Fig. 8-b is a graph of reactive power simulation results using a conventional droop control method.
FIG. 8-c is a graph showing the simulation results of the output voltage when the conventional droop control method is used.
FIG. 9-a is a graph showing the results of active power simulation using the control method of the present invention.
Fig. 9-b is a graph of reactive power simulation results when the control method of the present invention is used.
FIG. 9-c is a graph showing the simulation results of the output voltage when the control method of the present invention is used.
In the figure, 1: local controllers 1,2: local controllers 2,3: common bus, 4: communication line, 5: central controller, 6: power calculation module, 7: droop control module, 8: virtual inductive reactance adjustor, 9: voltage and current double-loop control module, 10: PWM driving module S 1 -S 6 : inverter switching tube, a: before introducing a reference virtual inductive reactance, B: after the reference virtual inductance is introduced.
(fifth) detailed description of the invention
The invention is described in further detail below with reference to the drawings and the detailed description. The following examples are illustrative of the invention and are not intended to limit the scope of the invention.
FIG. 1 is a diagram showing a conventional parallel circuit configuration of two inverters, V dc Direct current(s) generated by distributed power supply 1 -s 6 Is an inverter switching tube, L f 、C f Filter inductance and filter capacitance, i Li Is the inductor current of the ith inverter, i oi For the output current of the ith inverter, u oi For the output current voltage of the ith inverter, Z linei For the line impedance of the ith inverter, the inverters are connected via the line impedance to a common bus to which a load Z is also connected load . Local controller gathers i Li 、u oi 、i oi And interacts information with the central controller via the low bandwidth communication line.
FIG. 2 is a simplified circuit model of two inverters connected in parallel, Z i Equivalent line impedance of inverter i (i=1, 2), i.e. the sum of inverter output impedance and line impedance, R i 、X i Z is the corresponding resistance and inductance load Is the load. U (U) i ∠φ i For the inverter output voltage, i i To output current, V pcc Is the voltage of an alternating current bus, phi i For the phase angle difference of the two.
From fig. 2, it can be calculated that the relationship between the reactive power and the line impedance when the equivalent line impedance is inductive is:
fig. 3 is a power calculation module and droop control module in a local controller. The inverter output voltage u collected by the local controller is used for controlling the power supply o Phase-shifted by 90 DEG and output current i of inverter o Multiplication to obtain instantaneous active power p and inverter output voltage u o And inverter output current i o The instantaneous reactive power Q, P and Q are obtained by multiplication and respectively pass through a low-pass filter to obtain average active power P and average reactive power Q, the low-pass filter shown in fig. 4 is an expression in a frequency domain, wherein T is a filter time constant, and s is a pull-type conversion complex variable; p, Q obtaining omega and U by droop control equation droop 。
The droop control equation is:
ω＝ω 0 -k pω P (2)
U droop ＝U 0 -k qe Q (3)
another expression for bringing formula (3) into formula (1) to obtain reactive power is:
it can be seen that the condition for the reactive power to be equally divided is that the equivalent line impedance matches the inverter power rating.
FIG. 4 is a diagram of introducing a reference virtual inductance L v * The virtual inductance L is a voltage and current double-loop control block diagram v * Virtual inductive reactance X * The difference between them is a Laplacian, sL v * ＝X * The method comprises the steps of carrying out a first treatment on the surface of the G(s) and Z o (s) the output voltage gain before introducing the reference virtual inductance and the equivalent output impedance of the inverter, respectively; t (T) 0 The filter time constant of the low-pass filter is adopted, and the high-frequency noise interference can be effectively avoided by adding the low-pass filter; the inverter output voltage expression after the reference virtual inductance is introduced can be obtained from fig. 5 as follows:
the equivalent impedance expression of the inverter after the reference virtual inductance is introduced is shown as follows:
fig. 5 is a bode diagram of the equivalent output impedance of the inverter before and after the reference virtual inductance is introduced, which is obtained according to the formula (6), and it can be seen that the equivalent output impedance of the inverter after the reference virtual inductance is introduced basically exhibits an inductance at the fundamental frequency (the frequency is 50 Hz) and has the same value as the reference virtual inductance introduced, and it can be seen that the equivalent line impedance can be designed to be an inductance if a reference virtual inductance having a decisive role is introduced, so as to realize power decoupling.
Fig. 6 is a circuit diagram of the virtual reactance regulator of the present invention, which is composed of three parts of a subtracter, an integrator and an adder. Resistor R 1 ～R 4 Operational amplifier A 1 A subtracter is formed, and the input of the subtracter is the reactive power Q output by the inverter and the rated reactive power Q to be output by the inverter * Output reactive power difference (Q-Q * ) The method comprises the steps of carrying out a first treatment on the surface of the Resistor R 5 Capacitor C and operational amplifier A 2 An integrator is formed, the input of which is the reactive power difference (Q-Q * ) Adaptive part for outputting virtual inductancem is the integrator coefficient; resistor R 6 ～R 9 Operational amplifier A 3 An adder is formed, the input of which is the reference virtual inductance X * And an output section of the integrator outputting the virtual inductance X v 。
The virtual inductive reactance X v The expression of (2) is:
fig. 7 is a block diagram of the overall structure of the local controller, and as can be seen from fig. 7, the main steps of the present invention for realizing reactive power sharing are:
(1): the local controller collects the output voltage u of the inverter o Output current i o Inductor current i L And obtaining average active power P and average reactive power Q through power calculation, and transmitting the Q to a central controller through a communication line.
(2): p, Q in step (1) is subjected to droop control to obtain the frequency omega and the amplitude U of the output voltage of the inverter droop ，U droop Transformed into U by dq coordinate droop-d 、U droop-q I in step 1 o Transformed into i by dq coordinate d 、i q 。
(3): by adding reference virtual inductive reactance X * The inverter equivalent line impedance is designed to be inductive.
(4): the central controller will collect all reactive power (Q 1 、Q 2 ....Q n ) Adding up to obtain the total reactive power Q total And send to each inverter, each inverter receives the total reactive power by adopting the receiver and multiplies the total reactive power by the corresponding coefficient to obtain the rated reactive power Q which each inverter should output * The expression can be listed as:
k in qe_i 、k qe_j Reactive power-voltage amplitude droop coefficients for the ith and jth inverters respectively,rated reactive power to be output for the ith inverter.
(5): q in the step (1) and X in the step (3) * And Q in step (4) * Into the virtual inductance regulator shown in FIG. 6, a virtual inductance X with an adaptive part is calculated v The expression is formula (7).
(6): output current i in step (2) o Is of the dq component i of (2) d 、i q And virtual inductance X in step (5) v Multiplying to calculate the compensation value v of the reference value of the output voltage of the inverter vir-d 、v vir-q The expression is:
(7): component U of the output voltage in step (2) droop-d 、U droop-q Subtracting the compensation values v of the inverter output voltage reference values in step (6), respectively vir-d 、v vir-q Obtaining an inverter output voltage reference value, and combining the inductance current i acquired in the step (1) L Through voltage,Current double-loop control is carried out to obtain PWM modulation wave D and PWM driving is carried out, and finally an inverter switching tube s is controlled 1 -s 6 And (3) switching on and switching off, and regulating the output voltage and reactive power of the inverters to ensure that the inverters share the load.
The inverter output voltage reference value is:
according to the invention, a simulation model for parallel operation of two inverters of a low-voltage micro-grid is built on a Matlab/Simulink software platform. The simulation model comprises two inverters with the same capacity, and the two inverters are connected in parallel through different line impedances to supply power to a load together, and simulation parameters are listed in table 1.
TABLE 1
Example (1):
both inverters adopt traditional droop control, and only supply power for the load 1 within 0-1 s: the active power and the reactive power of the load 1 are respectively 8kW and 10kVar, the load 2 is put into power supply at the 1 st s, the load 2 is cut off at the 2 nd s, and the system is restored to be the load 1 only after being stabilized. The active and reactive power of the load 2 is 8kW and 8kVar respectively.
Fig. 8 is a simulation result of the output voltage of the active power and reactive power inverter obtained when the conventional droop control is adopted.
As can be seen from the active power simulation result diagram shown in FIG. 8-a, even though the conventional droop control can better divide active power equally, the time for dividing equally is longer, 0.4s is needed, and the operation efficiency is low; as shown in FIG. 8-b, comparing one phase of the output voltages of two inverters, it can be seen that the voltage difference between the output voltages of the inverters is larger due to the difference of the line impedance, and the smaller voltage difference can cause larger reactive power sharing error, as shown in FIG. 8-c, Q is the same when the system is stably operated after the load is suddenly changed 1 The relative error of (C) is-33.7%, Q 2 Phase of (2)The error for this was 30.2%.
Example (2):
the virtual inductive reactance is calculated by the virtual inductive reactance regulator for power decoupling and line impedance difference elimination by the two inverters, and the switching of the load is the same as the example (1).
See fig. 9-a-9-c.
The inverter output voltage, active power and reactive power simulation results obtained by adopting the control method of the invention. In the figure, it can be seen that the virtual inductive reactance is introduced to realize power decoupling, eliminate the equivalent line impedance difference between the two inverters, and compared with the transition time for realizing the average division of active power in fig. 8-a, the transition time is shortened, only 0.14s is needed, the output voltage difference between the two inverters is obviously reduced, the reactive power average division effect is obviously improved, and the Q is the same as that of the inverters before and after load mutation in stable operation 1 、Q 2 The relative error of (2) is within + -2%.
Claims (6)
1. A virtual inductive reactance regulator for realizing reactive power sharing of parallel inverters is characterized in that:
the virtual inductive reactance regulator (9) is arranged in a local controller of each inverter of the low-voltage micro-grid inverter parallel circuit, and the local controller is interconnected with the micro-grid central controller (5) through a low-bandwidth communication line (4);
the micro-grid central controller collects total reactive power Q total And send to the local controller, which receives the total reactive power Q total For calculating the rated reactive power Q which the inverter should output * ；
The virtual inductance regulator (9) is a virtual inductance setter and consists of a subtracter, an integrator and an adder;
the subtracter consists of a resistor R 1 ～R 4 Operational amplifier A 1 The input is the reactive power Q output by the inverter and the rated reactive power Q to be output by the inverter * The output is the reactive power difference (Q-Q * )；
The integrator is composed of a resistor R 5 Capacitor C and operational amplifier A 2 Is formed by the input of reactive power difference (Q-Q * ) Adaptive part with virtual inductive reactance outputm is the integrator coefficient;
the adder is composed of a resistor R 6 ～R 9 Operational amplifier A 3 The input is a reference virtual inductance X * And an output section of the integrator outputting as a virtual inductance X v ；
Virtual inductance X output by the adder v The expression of (2) is:
wherein s is a Law transformation complex variable operator;
rated reactive power Q to be output by the inverter * The specific expression of (2) is:
wherein k is qe_i 、k qe_j Reactive power-voltage amplitude droop for ith and jth inverters, respectively
Coefficient, Q i * The rated reactive power to be output by the i-th inverter is indicated.
2. The virtual reactance regulator of claim 1, characterized by: the local controller collects the output voltage u of the inverter to which it is connected o Output current i o And obtaining reactive power Q through power calculation, and transmitting the reactive power Q to the central controller through a low-bandwidth communication line.
3. The virtual reactance regulator of claim 1, characterized by: the reference virtual inductance X * Is used for ensuringThe equivalent circuit impedance of the inverter is inductive, so that power decoupling is realized.
4. A control method of a virtual inductive reactance regulator for realizing reactive power sharing of parallel inverters according to claim 1, characterized in that: adding reference virtual inductance X * After the equivalent circuit impedance of the inverter is inductive, a virtual inductive reactance regulator is additionally arranged in a local controller, the output reactive power of the inverter is adopted to regulate the magnitude of the virtual inductive reactance, the circuit impedance difference is eliminated, the circuit impedance parameter is not required to be detected, the output voltage difference of the inverter is reduced, and the power sharing is realized:
the method comprises the following steps:
step 1: the local controller obtains reactive power Q through power calculation and transmits the reactive power Q to the central controller through a communication line;
step 2: by adding reference virtual inductive reactance X * Designing the equivalent circuit impedance of the inverter to be inductive;
step 3: the central controller collects the total reactive power Q total Local controllers sent to each inverter, the local controllers based on Q total Calculating rated reactive power Q to be output by inverter * ；
Step 4: the virtual reactance adjuster of claim 1 obtaining a virtual reactance X with an adaptive section v ；
Step 5: combining X in the step 4 v And sag control is carried out to obtain reference voltage of the output voltage of the inverter, and the output voltage and reactive power of the inverter are regulated through voltage and current double-loop control, so that the inverters share the load.
5. The control method for realizing reactive power sharing of parallel inverters according to claim 4, wherein: the step 1 further comprises:
step 1-1: the local controller collects the output voltage u of the inverter o Output current i o ，i o Transformed into i by dq coordinate d 、i q ；
Step 1-2: the book is put intoInverter output voltage u collected by ground controller o Phase-shifted by 90 DEG and output current i of inverter o Multiplication to obtain instantaneous active power p and inverter output voltage u o And inverter output current i o Phase (C)
Multiplying to obtain instantaneous reactive power q, respectively passing through low-pass filter
Obtaining average active power P and average reactive power Q, and obtaining the frequency omega and amplitude U of the output voltage of the inverter through droop control droop ，U droop Transformed into U by dq coordinate droop-d 、U droop-q 。
6. The control method for realizing reactive power sharing of parallel inverters according to claim 4, wherein: the expression of the reference voltage in the step 5 is as follows:
wherein the method comprises the steps ofFor outputting the voltage reference value->Is included in the (c) dq component of the (c).
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| CN201811275002.6A CN109167371B (en) | 2018-10-29 | 2018-10-29 | Virtual inductive reactance regulator for realizing reactive power sharing of parallel inverter and control method |
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| CN113991759A (en) * | 2021-10-16 | 2022-01-28 | 内蒙古电力(集团)有限责任公司内蒙古电力科学研究院分公司 | Reactive power distribution method for voltage source type inverter under weak communication condition |
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