CN113419195A - Electronic anti-islanding protection testing device and method for photovoltaic grid-connected inverter - Google Patents

Electronic anti-islanding protection testing device and method for photovoltaic grid-connected inverter Download PDF

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CN113419195A
CN113419195A CN202110310084.9A CN202110310084A CN113419195A CN 113419195 A CN113419195 A CN 113419195A CN 202110310084 A CN202110310084 A CN 202110310084A CN 113419195 A CN113419195 A CN 113419195A
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power
voltage
output
load
grid
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郭金智
宋新利
刘阳
张兆广
李海雨
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Chengde Power Supply Co of State Grid Jibei Electric Power Co Ltd
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Chengde Power Supply Co of State Grid Jibei Electric Power Co Ltd
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    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
    • G01R31/00—Arrangements for testing electric properties; Arrangements for locating electric faults; Arrangements for electrical testing characterised by what is being tested not provided for elsewhere
    • G01R31/50—Testing of electric apparatus, lines, cables or components for short-circuits, continuity, leakage current or incorrect line connections
    • G01R31/56—Testing of electric apparatus
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
    • G01R19/00—Arrangements for measuring currents or voltages or for indicating presence or sign thereof
    • G01R19/165—Indicating that current or voltage is either above or below a predetermined value or within or outside a predetermined range of values
    • G01R19/16566—Circuits and arrangements for comparing voltage or current with one or several thresholds and for indicating the result not covered by subgroups G01R19/16504, G01R19/16528, G01R19/16533
    • G01R19/16576—Circuits and arrangements for comparing voltage or current with one or several thresholds and for indicating the result not covered by subgroups G01R19/16504, G01R19/16528, G01R19/16533 comparing DC or AC voltage with one threshold
    • G01R19/1658—AC voltage or recurrent signals

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Abstract

An electronic anti-islanding protection testing device and method for a photovoltaic grid-connected inverter are disclosed, wherein the electronic anti-islanding device is connected in series between the photovoltaic grid-connected inverter to be tested and a large power grid, energy is absorbed from the power grid side to stabilize direct-current side voltage, an input side is inverted to form a voltage source, the photovoltaic grid-connected inverter to be tested detects the voltage source with stable frequency and then tracks the voltage in real time to output, a calculation module in a load simulator samples and obtains the actual power value output by the photovoltaic grid-connected inverter to be tested, a power instruction calculation module calculates and obtains a power reference value to be regulated, then an input side self-adaptive PI controller regulates to obtain a simulated R, L, C load to be matched with the power output by the photovoltaic grid-connected inverter to be tested, after the power is matched, the power flow of the photovoltaic grid-connected inverter to be tested flows to the electronic anti-islanding input side, the output side feeds energy back to the power grid through a four-quadrant control strategy, the automatic test of the anti-islanding protection function of the photovoltaic grid-connected inverter is realized.

Description

Electronic anti-islanding protection testing device and method for photovoltaic grid-connected inverter
Technical Field
The invention relates to a photovoltaic grid-connected inverter technology, in particular to an electronic anti-islanding protection testing device and method for a photovoltaic grid-connected inverter.
Background
In recent years, distributed new energy power generation keeps a continuously increasing situation by virtue of economy and effectiveness, and the access of the distributed new energy power generation to a power distribution network also brings a series of problems to a power grid, wherein 'islanding' is one of the most widely researched subjects at present. Once islanding occurs, problems such as personal safety, power quality, protection against malfunction, etc. may be caused. According to the requirements of relevant national standards, an inverter is incorporated into a power distribution network with the voltage level of 10KV and below and has the function of anti-islanding protection. And if the power supply of the power grid is interrupted, the grid-connected inverter stops supplying power to the power grid within 2s and sends out an alarm signal at the same time.
At present, with the maturity of a photovoltaic grid-connected inverter technology, a plurality of island detection algorithms are developed, and are roughly classified into two categories: passive and active. The passive detection technology is used for judging an island based on whether parameters such as detection voltage, frequency, active power, reactive power and the like exceed limits, and has the main advantages that the island cannot be influenced on the quality of electric energy, but a large detection blind area exists; the active detection technology is characterized in that disturbance quantities are injected into amplitude values, frequency, phases and the like of current of the inverter, and related parameters of grid-connected points are changed to judge the island state when an island occurs. The anti-islanding protection of the photovoltaic grid-connected inverter mainly adopts an adjustable parallel RLC analog load to carry out laboratory test, and the test method is not only complex in test flow, but also strict in test condition requirements. Moreover, the device has the advantages of large volume, high manufacturing cost, complex operation, long consumed time, large consumption of electric energy and incapability of meeting the requirements of energy conservation and environmental protection.
Disclosure of Invention
In order to overcome the defects of the prior art, the invention aims to provide an electronic anti-islanding protection testing device and method for a photovoltaic grid-connected inverter, RLC loads are simulated by using a power electronic technology, a rectifying-inverting circuit with a back-to-back structure is adopted in the anti-islanding protection testing device, high-precision real-time matching with power of the photovoltaic grid-connected inverter to be tested can be realized, simulation parameter resistors R, inductors L and capacitors C are automatically generated, deviation percentages of active power, reactive power and rated values are intelligently calculated, automatic testing of an anti-islanding protection function of the photovoltaic grid-connected inverter is realized, the limitation defect of the traditional testing is overcome, the testing precision is improved, and the testing process is standardized.
In order to achieve the purpose, the technical scheme of the invention is as follows:
an electronic anti-islanding protection testing device for a photovoltaic grid-connected inverter comprises an input side filter, a load analog converter between an input side and a direct current side, an intermediate direct current bus, a grid-connected converter between the direct current side and an output side filter;
the load analog converter simulates a variable RLC load and is used for an anti-islanding protection test experiment of a test equipment grid-connected inverter; the load analog converter comprises: the device comprises a calculation module, a voltage phase-locked loop module, an input side adaptive PI controller and a PWM control module;
the calculation module acquires voltage and current information of an input side, and active power and reactive power output by the photovoltaic inverter to be measured and equivalent load information of a resistor R, an inductor L and a capacitor C are obtained after calculation.
The voltage phase-locked loop module acquires voltage on the input side to obtain frequency and voltage amplitude information output by the photovoltaic inverter to be tested, and the frequency and voltage amplitude information and RLC parameters are input into the power instruction calculation module together to obtain reference values of active power and reactive power; and comparing the reference values of the active power and the reactive power with the real values of the active power and the reactive power output by the calculation module, and following the power output by the photovoltaic inverter to be detected through the adjustment of the input side adaptive PI controller.
The PWM control module generates a driving signal of an inverter circuit in the device.
And the capacitor connected with the direct current bus in parallel supports the stability of direct current voltage.
The grid-connected converter between the direct current side and the output side comprises an output side PI controller, an inverter circuit driving signal control module and a four-quadrant control module;
the output side PI controller is responsible for adjusting the voltage of the direct current side, so that the voltage of the direct current side of the device is stabilized at a preset value of 650V; the four-quadrant module is responsible for acquiring voltage and current signals of an output side, and d-axis and q-axis voltage and current values under a synchronous rotation dq coordinate system are obtained through calculation; and comparing the signal value output by the output side PI controller with the d-axis voltage and q-axis voltage and current values output by the four-quadrant module, and inputting the signal value into the inverter circuit driving signal control module to obtain a driving signal of the inverter circuit.
The testing method based on the testing device comprises the following steps: the electronic anti-islanding device is connected between a photovoltaic grid-connected inverter to be detected and a large power grid in series, an input side is connected to an alternating current side of the photovoltaic inverter to be detected, an output side is connected to the large power grid, energy is absorbed from the power grid side to stabilize direct current side voltage, after the direct current side voltage is stabilized, the input side is inverted to form a voltage source, the photovoltaic grid-connected inverter to be detected tracks the voltage output in real time after detecting the voltage source with stable frequency, an actual power value output by the photovoltaic grid-connected inverter to be detected is obtained by sampling of a calculation module in a load simulator, a power reference value to be regulated is obtained by calculation of a power instruction calculation module, then adjustment is carried out by an input side self-adaptive PI controller to obtain a simulated R, L, C load to be matched with power output by the photovoltaic inverter to be detected, after power matching, power flow of the photovoltaic grid-connected inverter to be detected flows to the electronic anti-islanding, and the output side feeds energy back to the power grid through a four-quadrant control strategy.
The calculation module in the load simulator has the functions of:
when the photovoltaic inverter to be tested carries out island detection, the electronic anti-island device firstly operates as an alternating current voltage source, and the photovoltaic inverter not to be tested outputs voltage with stable amplitude and frequency; simultaneously real-time detecting the active and reactive powers input by the equipment, and calculating the required mode in real time according to the active power, the reactive power, the output voltage and the required quality factorThe parameters of the load resistor R, the load inductor L and the load capacitor C are called as resonance quality factor Q according to the ratio of the inductive reactance and the resistance R at resonancef:
Figure BDA0002989286060000041
Figure BDA0002989286060000042
Substituting formula (2) into formula (1) to obtain:
Figure BDA0002989286060000043
the analog resistance R is obtained by the ratio of the output voltage to the power:
Figure BDA0002989286060000044
the analog reactance L is derived from equation (1):
Figure BDA0002989286060000045
the reactive power is obtained by subtracting the inductive power from the capacitive power:
Figure BDA0002989286060000051
Figure BDA0002989286060000052
the analog capacitance C can be obtained from equations (6) and (7):
Figure BDA0002989286060000053
the output power of the on-site photovoltaic grid-connected inverter changes along with factors such as illumination, so that the numerical values of the load resistor R, the load inductor L and the load capacitor C also change, after receiving an island mode instruction command, the calculation module calculates the parameters of the simulated load resistor R, the load inductor L and the load capacitor C in real time according to the formulas (4), (5) and (8), calculates the output voltage through self-adaptive fuzzy PI regulation, and meets the island detection experiments of load matching and other requirements in the experimental standard.
The power instruction calculation module in the load simulator has the functions of:
collecting three-phase voltage U on alternating current bus at input side of electronic anti-islanding protection devicea、Ub、UcCalculating the amplitude and frequency of the voltage, and calculating the active instruction P in real time through a power instruction calculation module according to the RLC load parameters to be simulated*And idle instruction Q*。
Setting an active power command
P*＝U2/R (9)
Wherein U is the voltage of the output side of the inverter, and the resistor R is an analog resistor;
reactive power command
Q*＝U2×2πf×C-U2/(2πf×L) (10)
Wherein, U is the voltage of the output side of the inverter, and the capacitor C and the reactance L are analog capacitors and reactances.
Feedback active power calculation:
P＝ud×id+uq×iq (11)
and (3) feedback reactive power calculation:
Q＝ud×iq-uq×id (12)
wherein u isd、uqD-axis and q-axis voltages, i, calculated for real-time detectiond、iqThe calculated d-axis and q-axis currents are detected in real time.
The input side adaptive PI controller has the functions of:
the self-adaptive fuzzy PI controller is based on the conventional PI control and adopts the fuzzy reasoning idea to calculate the error e and the error change rate ecAs two input quantities of the fuzzy controller, pair kp、kiTwo parameters are set in real time to meet different input error quantities e and error change rates ec。
Firstly, setting according to experience value
Figure BDA0002989286060000061
Then the correction value deltak is obtained by fuzzy reasoningp、ΔkiObtaining the optimum k from the empirical value and the correction valuepAnd kiSee equation (13).
Figure BDA0002989286060000062
In the above formula
Figure BDA0002989286060000063
Being a classical PI parameter of the system, Δ kp、ΔkiThe adjustment value obtained for fuzzy reasoning.
The PID parameters are adjusted in real time by using fuzzy rules through output variables u (t) of the fuzzy controller, see formulas (14) and (15), so that the PID parameters are optimized, and the self-adaptive fuzzy PID control structure is shown in figure 3.
Δe(t)＝e*(t)-e(t) (14)
Figure BDA0002989286060000064
In the above formula kpIs a proportionality coefficient, kiIs an integral coefficient.
The invention has the advantages that:
1) the electronic anti-islanding protection testing device adopting the power electronic full-control type switching device and the power electronic current transformation technology can absorb or send active power and reactive power, simulate and replace RLC parallel loads, and also feed back functional quantity to a power grid, thereby avoiding a great deal of energy waste and conforming to the concept of building an environment-friendly and resource-saving society;
2) compared with the RLC loads of the same type, the size and the weight of the device are smaller than the actual RLC loads, the modular design technology is adopted, the device can be freely combined in parallel, the testing requirements of different power grades are met, and the use is flexible and convenient. The device does not need large-area plants, greatly reduces the labor intensity of testers and is convenient for field test;
3) the adjustment is flexible, the time for completing the test is short, and compared with the traditional RLC load, the matching power needs to be manually adjusted, so that the experimental preparation time is saved;
4) the device only consumes the energy of the direct current power supply, the inverter to be tested and the energy loss in the equipment, thereby greatly reducing the power grid capacity required by the experiment;
5) by adopting the power electronic technology, the load adjustment in a mechanical mode is abandoned, the service life of the experimental equipment is prolonged, and the maintenance cost of the experimental equipment is reduced.
Drawings
Fig. 1 is an electronic anti-islanding protection test system.
Fig. 2 is an anti-islanding protection test control strategy.
FIG. 3 is an adaptive fuzzy PID control structure.
Fig. 4 is an electronic anti-islanding protection test system model built in the PSCAD.
Fig. 5 is a load analog converter circuit configuration.
Fig. 6 is a voltage phase locked loop module.
Fig. 7 is a PWM control module.
Fig. 8 shows a grid-connected converter circuit configuration.
Fig. 9 is a dc voltage waveform diagram.
Fig. 10 is a resistance value obtained in the calculation block.
Figure 11 shows the inductance values obtained in the calculation block.
Fig. 12 is the capacitance values obtained in the calculation block.
Fig. 13 is a comparison graph of an actual output active power waveform of the photovoltaic grid-connected inverter to be tested and an active instruction obtained by the power instruction calculation module.
Fig. 14 is a comparison graph of the actual output reactive power waveform of the photovoltaic grid-connected inverter to be tested and the reactive power command obtained by the power command calculation module.
Detailed Description
The present invention will be described in detail with reference to the accompanying drawings.
Referring to fig. 1 and 2, an electronic anti-islanding protection testing device for a photovoltaic grid-connected inverter comprises an input side filter, a load analog converter between an input side and a direct current side, an intermediate direct current bus, a grid-connected converter between the direct current side and an output side, and an output side filter; fig. 4 is an overall circuit diagram of the electronic anti-islanding protection testing device for the photovoltaic grid-connected inverter built in the PSCAD according to fig. 1, wherein the photovoltaic grid-connected inverter to be tested, the load analog converter and the grid-connected converter all adopt custom modules PV _ module1, recitifier 1 and inverter2, and the large power grid adopts a 35kV ideal voltage source and is replaced by a 35kV/0.4kV step-down transformer.
The load analog converter simulates a variable RLC load and is used for an anti-islanding protection test experiment of a test equipment grid-connected inverter; the load analog converter comprises: the device comprises a calculation module, a voltage phase-locked loop module, an input side adaptive PI controller and a PWM control module; the specific circuit structure of the module is shown in fig. 5, signals of the photovoltaic grid-connected inverter to be tested enter the input side of the load analog converter through signal sources AC1_ a, AC1_ b and AC1_ c, and output signals DC1_ a and DC1_ b are output to the large capacitor on the direct current side.
The calculation module acquires voltage and current information of an input side, and active power and reactive power output by the photovoltaic inverter to be measured and equivalent load information of a resistor R, an inductor L and a capacitor C are obtained after calculation.
As shown in fig. 6, the voltage phase-locked loop module acquires the voltage at the input side to obtain the frequency and voltage amplitude information output by the photovoltaic inverter to be tested, and inputs the frequency and voltage amplitude information and the RLC parameters into the power instruction calculation module together to obtain the reference values of the active power and the reactive power; and comparing the reference values of the active power and the reactive power with the real values of the active power and the reactive power output by the calculation module, and following the power output by the photovoltaic inverter to be detected through the adjustment of the input side adaptive PI controller.
The PWM control module is responsible for generating a driving signal of an inverter circuit in the device, and outputs the driving signal of the IGBT by a modulation method as shown in fig. 7. The waveform modulated wave signal Ua _ out which is expected to be output is compared with the carrier signal carrier, and the on-off control is carried out on the switching element in the circuit at the intersection point of the two waves, so that the pulse with the width being in direct proportion to the amplitude of the modulated signal can be obtained.
The capacitors connected in parallel with the dc bus of the middle stage support the stabilization of the dc voltage, as shown in the left block diagram portion of fig. 8.
The grid-connected converter between the direct current side and the output side comprises an output side PI controller, an inverter circuit driving signal control module and a four-quadrant control module; referring to fig. 8, a subject circuit model of a grid-connected converter is shown.
The output side PI controller is responsible for adjusting the voltage of the dc side to stabilize the dc side voltage of the device at a preset value of 600V, as shown in fig. 9, a dc measurement voltage waveform obtained by simulation; the four-quadrant module is responsible for acquiring voltage and current signals of an output side, and d-axis and q-axis voltage and current values under a synchronous rotation dq coordinate system are obtained through calculation; and comparing the signal value output by the output side PI controller with the d-axis voltage and q-axis voltage and current values output by the four-quadrant module, and inputting the signal value into the inverter circuit driving signal control module to obtain a driving signal of the inverter circuit.
The testing method based on the testing device comprises the following steps: the electronic anti-islanding device is connected between a photovoltaic grid-connected inverter to be detected and a large power grid in series, an input side is connected to an alternating current side of the photovoltaic inverter to be detected, an output side is connected to the large power grid, energy is absorbed from the power grid side to stabilize direct current side voltage, after the direct current side voltage is stabilized, the input side is inverted to form a voltage source, the photovoltaic grid-connected inverter to be detected tracks the voltage output in real time after detecting the voltage source with stable frequency, an actual power value output by the photovoltaic grid-connected inverter to be detected is obtained by sampling of a calculation module in a load simulator, a power reference value to be regulated is obtained by calculation of a power instruction calculation module, then adjustment is carried out by an input side self-adaptive PI controller to obtain a simulated R, L, C load to be matched with power output by the photovoltaic inverter to be detected, after power matching, power flow of the photovoltaic grid-connected inverter to be detected flows to the electronic anti-islanding, and the output side feeds energy back to the power grid through a four-quadrant control strategy.
The calculation module in the load simulator has the functions of:
when the photovoltaic inverter to be tested carries out island detection, the electronic anti-island device firstly operates as an alternating current voltage source, and the photovoltaic inverter not to be tested outputs voltage with stable amplitude and frequency; simultaneously, real-time detecting active power and reactive power input by equipment, calculating parameters of a load resistor R, a load inductor L and a load capacitor C to be simulated in real time according to the active power, the reactive power, the output voltage and the required quality factor, and referring to the resonance quality factor Q according to the ratio of the inductance to the resistance R during resonancef:
Figure BDA0002989286060000111
Figure BDA0002989286060000112
Substituting formula (2) into formula (1) to obtain:
Figure BDA0002989286060000113
the analog resistance R is obtained by the ratio of the output voltage to the power:
Figure BDA0002989286060000114
the analog reactance L is derived from equation (1):
Figure BDA0002989286060000115
the reactive power is obtained by subtracting the inductive power from the capacitive power:
Figure BDA0002989286060000116
Figure BDA0002989286060000117
the analog capacitance C can be obtained from equations (6) and (7):
Figure BDA0002989286060000118
the output power of the on-site photovoltaic grid-connected inverter changes along with factors such as illumination, so that the numerical values of the load resistor R, the load inductor L and the load capacitor C also change, after receiving an island mode instruction command, the calculation module calculates the parameters of the simulated load resistor R, the load inductor L and the load capacitor C in real time according to the formulas (4), (5) and (8), calculates the output voltage through self-adaptive fuzzy PI regulation, and meets the island detection experiments of load matching and other requirements in the experimental standard. Referring to fig. 10, the resistance value R calculated by the module is 0.66 Ω, the inductance value L calculated by the module is 1.014H, referring to fig. 11, and the capacitance value C calculated by the module is 10 μ F, referring to fig. 12.
The power instruction calculation module in the load simulator has the functions of:
collecting three-phase voltage U on alternating current bus at input side of electronic anti-islanding protection devicea、Ub、UcCalculating the amplitude and frequency of the voltage, and calculating the active instruction P in real time through a power instruction calculation module according to the RLC load parameters to be simulated*And idle instruction Q*。
Setting an active power command
P*＝U2/R (9)
Wherein U is the voltage of the output side of the inverter, and the resistor R is an analog resistor;
reactive power command
Q*＝U2×2πf×C-U2/(2πf×L) (10)
Wherein, U is the voltage of the output side of the inverter, and the capacitor C and the reactance L are analog capacitors and reactances.
Feedback active power calculation:
P＝ud×id+uq×iq (11)
and (3) feedback reactive power calculation:
Q＝ud×iq-uq×id (12)
wherein u isd、uqD-axis and q-axis voltages, i, calculated for real-time detectiond、iqThe calculated d-axis and q-axis currents are detected in real time.
Referring to fig. 13, an active power waveform Ppv (blue line) actually output by the photovoltaic grid-connected inverter to be tested is shown, and a green line waveform is an active instruction value calculated in the power instruction calculation module.
Referring to fig. 14, a reactive power waveform Ppv (blue line) actually output by the photovoltaic grid-connected inverter to be tested, and a green line waveform is a reactive power instruction value calculated in the power instruction calculation module, and as can be seen from fig. 12 and 13, the two are very consistent, which illustrates that the device simulates the power matching situation.
The input side adaptive PI controller has the functions of:
the self-adaptive fuzzy PI controller is based on the conventional PI control and adopts the fuzzy reasoning idea to calculate the error e and the error change rate ecAs two input quantities of the fuzzy controller, pair kp、kiTwo parameters are set in real time to meet different input error quantities e and error change rates ec。
Firstly, setting according to experience value
Figure BDA0002989286060000131
A value ofThen obtaining a corrected value delta k through fuzzy reasoningp、ΔkiObtaining the optimum k from the empirical value and the correction valuepAnd kiSee equation (13).
Figure BDA0002989286060000132
In the above formula
Figure BDA0002989286060000133
Being a classical PI parameter of the system, Δ kp、ΔkiThe adjustment value obtained for fuzzy reasoning.
The PID parameters are adjusted in real time by using fuzzy rules through output variables u (t) of the fuzzy controller, see formulas (14) and (15), so that the PID parameters are optimized, and the self-adaptive fuzzy PID control structure is shown in figure 3.
Δe(t)＝e*(t)-e(t) (14)
Figure BDA0002989286060000134
In the above formula kpIs a proportionality coefficient, kiIs an integral coefficient.

Claims (7)

1. An electronic anti-islanding protection testing device for a photovoltaic grid-connected inverter is characterized by comprising an input side filter, a load analog converter between an input side and a direct current side, an intermediate direct current bus, a grid-connected converter between the direct current side and an output side filter;
the load analog converter simulates a variable RLC load and is used for an anti-islanding protection test experiment of a test equipment grid-connected inverter; the load analog converter comprises: the device comprises a calculation module, a voltage phase-locked loop module, an input side adaptive PI controller and a PWM control module;
the calculation module acquires voltage and current information of an input side, and active power and reactive power output by the photovoltaic inverter to be measured and equivalent load information of a resistor R, an inductor L and a capacitor C are obtained after calculation;
the voltage phase-locked loop module acquires voltage on the input side to obtain frequency and voltage amplitude information output by the photovoltaic inverter to be tested, and the frequency and voltage amplitude information and RLC parameters are input into the power instruction calculation module together to obtain reference values of active power and reactive power; the active power and reactive power reference values are compared with the real active power and reactive power values output by the calculation module, and the power output by the photovoltaic inverter to be detected is followed through the adjustment of the input side adaptive PI controller;
and the PWM control module is responsible for generating a driving signal of an inverter circuit in the device.
2. The device for testing the electronic anti-islanding protection of the photovoltaic grid-connected inverter according to claim 1, wherein a capacitor connected in parallel with the direct-current bus supports the stability of direct-current voltage.
3. The electronic anti-islanding protection testing device for the photovoltaic grid-connected inverter according to claim 1, wherein the grid-connected converter between the direct current side and the output side comprises an output side PI controller, an inverter circuit driving signal control module and a four-quadrant control module;
the output side PI controller is responsible for adjusting the voltage of the direct current side, so that the voltage of the direct current side of the device is stabilized at a preset value of 650V; the four-quadrant module is responsible for acquiring voltage and current signals of an output side, and d-axis and q-axis voltage and current values under a synchronous rotation dq coordinate system are obtained through calculation; and comparing the signal value output by the output side PI controller with the d-axis voltage and q-axis voltage and current values output by the four-quadrant module, and inputting the signal value into the inverter circuit driving signal control module to obtain a driving signal of the inverter circuit.
4. The testing method of the electronic anti-islanding protection testing device for the photovoltaic grid-connected inverter according to claim 1, is characterized by comprising the following steps: the electronic anti-islanding device is connected between a photovoltaic grid-connected inverter to be detected and a large power grid in series, an input side is connected to an alternating current side of the photovoltaic inverter to be detected, an output side is connected to the large power grid, energy is absorbed from the power grid side to stabilize direct current side voltage, after the direct current side voltage is stabilized, the input side is inverted to form a voltage source, the photovoltaic grid-connected inverter to be detected tracks the voltage output in real time after detecting the voltage source with stable frequency, an actual power value output by the photovoltaic grid-connected inverter to be detected is obtained by sampling of a calculation module in a load simulator, a power reference value to be regulated is obtained by calculation of a power instruction calculation module, then adjustment is carried out by an input side self-adaptive PI controller to obtain a simulated R, L, C load to be matched with power output by the photovoltaic inverter to be detected, after power matching, power flow of the photovoltaic grid-connected inverter to be detected flows to the electronic anti-islanding, and the output side feeds energy back to the power grid through a four-quadrant control strategy.
5. The method for testing electronic anti-islanding protection of the photovoltaic grid-connected inverter according to claim 4, wherein a calculation module in the load simulator has functions specifically as follows:
when the photovoltaic inverter to be tested carries out island detection, the electronic anti-island device firstly operates as an alternating current voltage source, and the photovoltaic inverter not to be tested outputs voltage with stable amplitude and frequency; simultaneously, real-time detecting active power and reactive power input by equipment, calculating parameters of a load resistor R, a load inductor L and a load capacitor C to be simulated in real time according to the active power, the reactive power, the output voltage and the required quality factor, and referring to the resonance quality factor Q according to the ratio of the inductance to the resistance R during resonancef:
Figure FDA0002989286050000031
Figure FDA0002989286050000032
Substituting formula (2) into formula (1) to obtain:
Figure FDA0002989286050000033
the analog resistance R is obtained by the ratio of the output voltage to the power:
Figure FDA0002989286050000034
the analog reactance L is derived from equation (1):
Figure FDA0002989286050000035
the reactive power is obtained by subtracting the inductive power from the capacitive power:
Figure FDA0002989286050000036
Figure FDA0002989286050000037
the analog capacitance C can be obtained from equations (6) and (7):
Figure FDA0002989286050000038
the output power of the on-site photovoltaic grid-connected inverter changes along with factors such as illumination, so that the numerical values of the load resistor R, the load inductor L and the load capacitor C also change, after receiving an island mode instruction command, the calculation module calculates the parameters of the simulated load resistor R, the load inductor L and the load capacitor C in real time according to the formulas (4), (5) and (8), calculates the output voltage through self-adaptive fuzzy PI regulation, and meets the island detection experiments of load matching and other requirements in the experimental standard.
6. The method for testing electronic anti-islanding protection of the photovoltaic grid-connected inverter according to claim 4, wherein the power instruction calculation module in the load simulator has functions specifically as follows:
collecting three-phase voltage U on alternating current bus at input side of electronic anti-islanding protection devicea、Ub、UcCalculating the amplitude and frequency of the voltage, and calculating the active instruction P in real time through a power instruction calculation module according to the RLC load parameters to be simulated*And idle instruction Q*；
Setting an active power command
P*＝U2/R (9)
Wherein U is the voltage of the output side of the inverter, and the resistor R is an analog resistor;
reactive power command
Q*＝U2×2πf×C-U2/(2πf×L) (10)
Wherein U is the voltage of the output side of the inverter, and the capacitor C and the reactance L are analog capacitors and reactances;
feedback active power calculation:
P＝ud×id+uq×iq (11)
and (3) feedback reactive power calculation:
Q＝ud×iq-uq×id (12)
wherein u isd、uqD-axis and q-axis voltages, i, calculated for real-time detectiond、iqThe calculated d-axis and q-axis currents are detected in real time.
7. The method for testing electronic anti-islanding protection of the photovoltaic grid-connected inverter according to claim 4, wherein the input-side adaptive PI controller specifically has the following functions:
the self-adaptive fuzzy PI controller is based on the conventional PI control and adopts the fuzzy reasoning idea to calculate the error e and the error change rate ecAs two input quantities of the fuzzy controller, pair kp、kiTwo parameters are adjusted in real time to meet different input error quantities e andrate of change of error ec；
Firstly, setting according to experience value
Figure FDA0002989286050000051
Then the correction value deltak is obtained by fuzzy reasoningp、ΔkiObtaining the optimum k from the empirical value and the correction valuepAnd kiSee equation (13);
Figure FDA0002989286050000052
in the above formula
Figure FDA0002989286050000053
Being a classical PI parameter of the system, Δ kp、ΔkiAn adjustment value obtained for fuzzy reasoning;
the PID parameters are set in real time by using fuzzy rules through output variables u (t) of the fuzzy controller, see formulas (14) and (15), so that the PID parameters are optimal, and the self-adaptive fuzzy PID control structure is shown in figure 3;
Δe(t)＝e*(t)-e(t) (14)
Figure FDA0002989286050000054
in the above formula kpIs a proportionality coefficient, kiIs an integral coefficient.
CN202110310084.9A 2021-03-23 2021-03-23 Electronic anti-islanding protection testing device and method for photovoltaic grid-connected inverter Pending CN113419195A (en)

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Cited By (4)

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Publication number Priority date Publication date Assignee Title
CN113933648A (en) * 2021-09-27 2022-01-14 国网河北省电力有限公司电力科学研究院 Power distribution network relay protection vector checking and action logic checking test device and method
CN114256872A (en) * 2021-12-03 2022-03-29 合肥科威尔电源系统股份有限公司 Alternating current source control method, device, equipment and medium with island test function
CN116500370A (en) * 2023-06-29 2023-07-28 苏州精实智能装备有限公司 Island testing method and device for photovoltaic inverter
CN117783757A (en) * 2024-02-23 2024-03-29 山东华天电气有限公司 Modularized simulation device and control method thereof

Non-Patent Citations (1)

* Cited by examiner, † Cited by third party
Title
徐在德: "光伏并网逆变器电子防孤岛保护测试装置及其应用", 《电力自动化设备》 *

Cited By (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN113933648A (en) * 2021-09-27 2022-01-14 国网河北省电力有限公司电力科学研究院 Power distribution network relay protection vector checking and action logic checking test device and method
CN114256872A (en) * 2021-12-03 2022-03-29 合肥科威尔电源系统股份有限公司 Alternating current source control method, device, equipment and medium with island test function
CN116500370A (en) * 2023-06-29 2023-07-28 苏州精实智能装备有限公司 Island testing method and device for photovoltaic inverter
CN116500370B (en) * 2023-06-29 2023-10-27 苏州精实智能装备有限公司 Island testing method and device for photovoltaic inverter
CN117783757A (en) * 2024-02-23 2024-03-29 山东华天电气有限公司 Modularized simulation device and control method thereof
CN117783757B (en) * 2024-02-23 2024-05-14 山东华天电气有限公司 Modularized simulation device and control method thereof

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