Automatic analysis method for high voltage ride through test result of photovoltaic inverter

Abstract

The invention relates to the technical field of power system automation, and provides a photovoltaic inverter high-voltage ride-through test result automatic analysis method, which comprises the following steps: reading high-voltage ride-through test data of a photovoltaic inverter, firstly judging single and continuous high-voltage ride-through faults, classifying the single high-voltage ride-through faults into three-phase faults and two-phase faults, and carrying out fault analysis on the three-phase faults and the two-phase faults; no-load test data are further calculated, and if the no-load test data are qualified, the voltage drop depth, the drop duration, the reactive current response time, the reactive current duration, the reactive current exit time and the active power fluctuation of the load data are further calculated; performing no-load test data on the continuous high voltage ride through, and further judging whether load test data is off-grid if the no-load test data is qualified; and if not, automatically storing the test waveform and the calculation result in word, and otherwise, outputting that the test waveform and the calculation result are unqualified. The automatic analysis of the high-voltage ride-through test result of the photovoltaic inverter is accurately realized, and the test waveform and the calculation result are automatically stored in the word.

Description

Technical Field

[0001] The invention relates to the technical field of power system automation, and in particular to an automatic analysis method for high voltage ride-through test results of a photovoltaic inverter. Background Art

[0002] With the construction of new power systems, the installed capacity of new energy sources is increasing, and the voltage stability requirements of the power grid are getting higher and higher. In addition, GB / T 19964-2024 "Technical Regulations for Access of Photovoltaic Power Stations to Power Systems", GB / T 40594-2021 "Technical Guidelines for Power System Grid-Source Coordination", GB / T 37408-2019 "Technical Requirements for Photovoltaic Power Generation Grid-connected Inverters", NB / T10324-2019 "Technical Regulations for High Voltage Ride Through Detection of Photovoltaic Power Stations" and other national standards and industry standards require that photovoltaic inverters must carry out single and continuous high voltage ride through tests. The test point voltage requirements are 115%, 120%, 125%, and 130%Un, and no-load and load high voltage ride through tests for three-phase and two-phase faults are required. The load test is divided into high-power and low-power conditions. Each voltage drop point must be tested continuously at least twice under each condition.

[0003] The standard requires that the results of the high voltage ride-through test be analyzed, but currently it is only based on manual calculation of test data. After the field test is completed, the test results need to be analyzed in a timely manner to facilitate the next step of work; there are many field test conditions, and it takes 4 days to manually complete the high voltage ride-through test data analysis of a photovoltaic inverter. As a result, after the field data collection is completed, it takes at least 4 days to proceed to the next step, which seriously affects the next step of work. In some parts of my country, the irradiance of photovoltaic power stations is unstable, the output fluctuates greatly, the test window period is short, and the long test result analysis time has aggravated the test cycle. Summary of the invention

[0004] The purpose of the present invention is to solve the deficiencies of the prior art and to provide a method for automatically analyzing the high voltage ride through test results of a photovoltaic inverter, so as to automatically and quickly carry out the high voltage ride through result analysis of the photovoltaic inverter.

[0005] In order to achieve the above object, the present invention adopts the following technical solutions:

[0006] A method for automatically analyzing high voltage ride-through test results of a photovoltaic inverter comprises the following steps:

[0007] Step 1, reading the high voltage ride-through test results of the photovoltaic inverter based on field testing, hardware-in-the-loop electromagnetic transient simulation or non-real-time electromagnetic transient simulation, the test results including the instantaneous values ​​of voltage and current on the high voltage side or low voltage side of the photovoltaic inverter step-up transformer;

[0008] Step 2, calculating the effective value of the high voltage ride through test result of the photovoltaic inverter;

[0009] Step 3, distinguishing single and continuous high voltage ride through test results based on the line voltage of the fundamental positive sequence component;

[0010] Step 4: classify the single high voltage ride through test data into three-phase fault and two-phase fault; the three-phase fault and two-phase fault ride through test data are based on the active power P before the voltage rises. 前1 , P 前2 The judgment is divided into no-load test data and load test data, active power P 前1 , P 前2 Greater than 0.05 times the rated active power is the load test data, active power P 前1 , P 前2 Less than or equal to 0.05 times the rated active power is the no-load test data;

[0011] Step 5: Calculate the voltage rise value and duration of the three-phase fault no-load test data. If the voltage rise value and duration meet the standard requirements, the no-load test data is output as qualified, otherwise it is output as unqualified; determine whether the three-phase fault load test data is off-grid, if it is off-grid, it is judged as unqualified, otherwise the voltage rise value U is further calculated based on the fundamental positive sequence line voltage. swell1 Duration t swell1 , calculate the reactive current response time t res1 , reactive current duration t last1 , reactive current exit time t ree1 , calculate the active power drop depth P dip1 If t res1 Greater than 30ms, or t ree1 If it is greater than 30ms, the output is unqualified, otherwise it is judged that P dip1 Is it greater than 0.9 times P 前1 , P dip1 ≥0.9P 前1 , the test waveform and calculation results are automatically stored in the word document; dip1 <0.9P 前1 , calculate the active power recovery time t re1 , if t re1 ≤40ms, the test waveform and calculation results are automatically stored in a word document, otherwise the output is unqualified;

[0012] Step 6: Calculate the voltage rise value and duration for the two-phase fault no-load test data. If the voltage rise value and duration meet the standard requirements, the no-load test data is output as qualified, otherwise it is output as unqualified; determine whether the two-phase fault load test data is off-grid, if it is off-grid, it is judged as unqualified, otherwise the voltage rise value U is further calculated based on the fundamental line voltage.swell2 Duration t swell2 , calculate the reactive current response time t res2 , reactive current duration t last2 , reactive current exit time t ree2 , calculate the active power drop depth P dip2 ; Judge P dip2 Is it greater than 0.9 times P 前2 , P dip2 ≥0.9P 前2 , the test waveform and calculation results are automatically stored in the word document; dip2 <0.9P 前2 , calculate the active power recovery time t re2 , if t re2 ≤40ms, the test waveform and calculation results are automatically stored in a word document, otherwise the output is unqualified;

[0013] Step 7: Calculate the continuous high voltage ride through test data based on the active power P before the voltage rises. 前3 The judgment is divided into no-load test data and load test data, active power P 前3 Greater than 0.05 times the rated active power is the load test data, active power P 前3 Less than or equal to 0.05 times the rated active power is the no-load test data; Step 8, calculate the voltage rise value and duration for the continuous high voltage ride through no-load test data. If the voltage rise value and duration meet the standard requirements, the no-load test data is output as qualified, otherwise the output is unqualified; for the continuous high voltage ride through load test data, determine whether it is off-grid. If it is off-grid, it is determined as unqualified, otherwise the test waveform and calculation results are automatically stored in a word document.

[0014] Preferably, in step 2, full-wave FFT is used to calculate the fundamental phase voltage, line voltage and line voltage of the fundamental positive sequence component, active power, active current, reactive power and reactive current effective value.

[0015] Preferably, in step 3, the high voltage ride-through data includes single high voltage ride-through and continuous high voltage ride-through test data, and the single high voltage ride-through test condition includes 115% to 130% Un, and the continuous high voltage ride-through test condition includes a low-high voltage ride-through test: 0% Un-130% Un, or two or more consecutive high-high voltage ride-through tests 130% Un-~130% Un tests.

[0016] Preferably, in steps 5, 6 and 8, the single high voltage ride through and continuous high-high voltage ride through no-load test data are determined with reference to GB / T 19964 standard, with a voltage deviation of ±3% and a duration deviation of ±20ms, specifically:

[0017] Voltage rise per unit value U swell :1.15±0.03,Duration t swell :10000±20ms;

[0018] Voltage rise per unit value U swell :1.2±0.03,Duration t swell :10000±20ms;

[0019] Voltage rise per unit value U swell :1.25±0.03,Duration t swell :1000±20ms;

[0020] Voltage rise per unit value U swell :1.3±0.03,Duration t swell :500±20ms;

[0021] The continuous low-high voltage ride-through no-load test data is judged according to GB / T 19964 standard. The voltage drop deviation is ±5%, the voltage rise deviation is ±3%, and the duration deviation is ±20ms. Specifically:

[0022] Voltage drop amplitude U dip :0.0+0.05,duration t dip :150±20;

[0023] Voltage increase amplitude U swell :1.30±0.03,Duration t swell :500±20.

[0024] Preferably, in step 4, the fault classification method is specifically:

[0025] Calculate the average fundamental phase voltage U of phases A, B, and C before the voltage drops avg ; Calculate the fundamental phase voltage average value U of phases A, B, and C respectively Aavg , U Bavg , U Cavg ; Set the judgment threshold △U to 0.4;

[0026] The judgment method is:

[0027] If U Aavg -U avg >△U and U Bavg -U avg >△U and U Cavg -U avg >△U, it is ABC phase fault;

[0028] If U Aavg -Uavg >△U and U Bavg -U avg >△U and U Cavg -U avg <△U, it is AB phase fault;

[0029] If U Aavg -U avg >△U and U Bavg -U avg <△UAndU Cavg -U avg >△U, it is an AC phase fault;

[0030] If U Aavg -U avg <△UAndU Bavg -U avg >△U and U Cavg -U avg >△U, it is a BC phase fault;

[0031] An ABC phase fault is a three-phase fault, and an AB phase fault, an AC phase fault, and a BC phase fault are two-phase faults.

[0032] Preferably, in steps 5 and 6, the test result calculation process is as follows:

[0033] S1, voltage rise value U swell1 , U swell2 is: the per unit value after the voltage rises and stabilizes;

[0034] S2, voltage rise duration t swell1 ,t swell2 is: t Uend -t Ustart ;

[0035] Among them, t Ustart is the time when the voltage increase process is completed, t Uend is the moment when the voltage starts to recover; the standard deviation of the fundamental positive sequence line voltage or fundamental phase voltage is calculated respectively. After the voltage rises to 1.1Un and before the voltage drops to 1.1Un, the moment when the standard deviation is less than 0.003 is the moment when the voltage rise process is completed; at the moment when the voltage rise process is completed t Ustart During the period from the beginning of the voltage recovery to the end of the voltage drop to 1.1Un, the first time point when the standard deviation is greater than 0.003 is the time when the voltage begins to recover.

[0036] S3, reactive current response time t res1 ,t res2 is: t Iqstart -t 1.1start ;

[0037] Among them, t Iqstart Indicates the time when the reactive current absorbed by the PV inverter continues to be greater than 90% of the reactive current injection reference value; t 1.1start Indicates the moment when the voltage rises to 1.1Un;

[0038] The reference value of reactive current injection is: 1.5*(U swell -1.1)*I n , where I n The rated current of the photovoltaic inverter, and the maximum reactive current does not exceed 1.05I n ;

[0039] S4, reactive current duration t last1 ,t last2 is: t Iqend -t Iqstart ;

[0040] Among them, t Iqend Indicates the end time when the reactive current absorbed by the PV inverter continuously exceeds 90% of the reactive current injection reference value;

[0041] S5, reactive current exit time t ree1 ,t ree2 is: t Iqtuichu -t Iqend ;

[0042] Among them, t Iqtuichu Indicates that the reactive current increment is exited, that is, t Iqend After the moment, the moment when the reactive current standard deviation is less than 0.003 is the moment when the reactive current increment exits;

[0043] S6, active power recovery time t re1 ,t re2 is: t Pend -t Uend ;

[0044] Among them, t Pend Indicates the time point when the active power recovers to the value under the current light, t Uend It means that after the voltage starts to recover, the time point when the active power standard deviation is less than 0.003 is the time point when the active power recovers to the current light level.

[0045] Preferably, in step (1), the high voltage ride-through test results of the photovoltaic inverter based on field testing, hardware-in-the-loop electromagnetic transient simulation or non-real-time electromagnetic transient simulation are read, including the instantaneous values ​​of voltage and current on the high voltage side or low voltage side of the photovoltaic inverter step-up transformer.

[0046] The present invention discloses a method for automatically analyzing high voltage ride-through test results of a photovoltaic inverter, which has the following beneficial effects.

[0047] The present invention realizes efficient automatic analysis without manual calculation, and can process the high voltage ride-through test results of photovoltaic inverters in batches, shortening the analysis time from 4 days to 1 hour, and automatically generating and storing detailed results including fundamental line voltage, active and reactive power, etc. The phase voltage average value comparison method is used to determine the fault type, and the no-load and load test data analysis results are performed for three-phase faults and two-phase faults respectively. At the same time, the standard deviation method is used to identify the key time points for active power recovery and reactive current exit, thereby improving the accuracy of the analysis. The method is applicable to various high voltage ride-through tests, and the results are not affected by voltage changes and power size, and has the advantages of high efficiency and high accuracy. BRIEF DESCRIPTION OF THE DRAWINGS

[0048] Figure 1 It is a flow chart of a method for automatically analyzing high voltage ride through test results of a photovoltaic inverter according to the present invention;

[0049] Figure 2 This is a schematic diagram of the test result calculation and determination of the present invention;

[0050] Figure 3 This is a waveform diagram of the test results of the photovoltaic inverter 130%Un three-phase no-load high voltage ride-through in Application Example 1 of the present invention;

[0051] Figure 4 This is a waveform diagram of the high voltage ride-through test result of the photovoltaic inverter 130%Un three-phase load in Application Example 1 of the present invention;

[0052] Figure 5 This is a summary diagram of the test results of the 125%Un two-phase no-load high voltage ride-through of the photovoltaic inverter of Application Example 2 of the present invention;

[0053] Figure 6 This is a summary diagram of the high voltage ride-through test results of the photovoltaic inverter 125%Un two-phase load of application example 2 of the present invention;

[0054] Figure 7 This is a summary diagram of the continuous no-load high voltage ride-through test results of the photovoltaic inverter of Application Example 3 of the present invention;

[0055] Figure 8 This is a summary diagram of the continuous load high voltage ride through test results of the photovoltaic inverter of Application Example 3 of the present invention; DETAILED DESCRIPTION

[0056] The technical solutions in the embodiments of the present invention will be described clearly and completely below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, rather than all the embodiments.

[0057] In the description of the present invention, it is necessary to understand that the terms "upper", "lower", "front", "back", "left", "right", "top", "bottom", "inside", "outside", etc., indicating the orientation or position relationship are based on the orientation or position relationship shown in the drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation on the present invention.

[0058] The high voltage ride-through test results of photovoltaic inverters are mainly calculated manually. This embodiment of the present invention provides an automatic analysis method for the high voltage ride-through test results of photovoltaic inverters. The automatic analysis method for the high voltage ride-through test results of photovoltaic inverters does not rely on manual calculations, and can automatically, batch-wise and efficiently complete the high voltage ride-through test results of photovoltaic inverters, and automatically store the test waveforms and calculation results in a word.

[0059] like Figure 1 and Figure 2 As shown, a method for automatically analyzing high voltage ride-through test results of a photovoltaic inverter comprises the following steps:

[0060] Step 1, reading the high voltage ride-through test results of the photovoltaic inverter based on field testing, hardware-switching electromagnetic transient simulation or non-real-time electromagnetic transient simulation; preferably, in step (1), the high voltage ride-through test results of the photovoltaic inverter based on field testing, hardware-switching electromagnetic transient simulation or non-real-time electromagnetic transient simulation are read, including the instantaneous values ​​of voltage and current on the high voltage side or low voltage side of the photovoltaic inverter step-up transformer.

[0061] Step 2, calculating the effective value of the high voltage ride through test result of the photovoltaic inverter;

[0062] Preferably, in step 2, full-wave FFT is used to calculate the fundamental phase voltage, line voltage and line voltage of the fundamental positive sequence component, active power, active current, reactive power and reactive current effective value.

[0063] Step 3, distinguishing single and continuous high voltage ride through test results based on the line voltage of the fundamental positive sequence component;

[0064] Preferably, in step 3, the high voltage ride-through data includes single high voltage ride-through and continuous high voltage ride-through test data, and the single high voltage ride-through test condition includes 115% to 130% Un, and the continuous high voltage ride-through test condition includes a low-high voltage ride-through test: 0% Un-130% Un, or two or more consecutive high-high voltage ride-through tests 130% Un- to 130% Un tests.

[0065] Step 4: classify the single high voltage ride through test data into three-phase fault and two-phase fault; the three-phase fault and two-phase fault ride through test data are based on the active power P before the voltage rises. 前1 , P 前2 The judgment is divided into no-load test data and load test data, active power P 前1 , P 前2 Greater than 0.05 times the rated active power is the load test data, active power P 前1 , P 前2 Less than or equal to 0.05 times the rated active power is the no-load test data;

[0066] Preferably, in step 4, the fault classification method is specifically as follows:

[0067] Calculate the average fundamental phase voltage U of phases A, B, and C before the voltage drops avg ; Calculate the fundamental phase voltage average value U of phases A, B, and C respectively Aavg , U Bavg , U Cavg ; Set the judgment threshold △U to 0.4;

[0068] The judgment method is:

[0069] If U Aavg -U avg >△U and U Bavg -U avg >△U and U Cavg -U avg >△U, it is ABC phase fault;

[0070] If U Aavg -U avg >△U and U Bavg -U avg >△U and U Cavg -U avg <△U, it is AB phase fault;

[0071] If U Aavg -U avg >△U and U Bavg -U avg <△UAndU Cavg -U avg >△U, it is an AC phase fault;

[0072] If U Aavg -U avg <△UAndU Bavg -U avg >△U and U Cavg -U avg >△U, it is a BC phase fault;

[0073] An ABC phase fault is a three-phase fault, and an AB phase fault, an AC phase fault, and a BC phase fault are two-phase faults.

[0074] Step 5, calculate the voltage rise value and duration of the three-phase fault no-load test data. If the voltage rise value and duration meet the standard requirements, the no-load test data is output as qualified, otherwise the output is unqualified; determine whether the three-phase fault load test data is off-grid, if off-grid, it is judged as unqualified, otherwise further calculate the voltage rise value Uswell1 and duration tswell1 based on the fundamental positive sequence line voltage, calculate the reactive current response time tres1, the reactive current duration tlast1, the reactive current exit time tree1, and calculate the active current drop depth Pdip1; if tres1 is greater than 30ms, or tree1 is greater than 30ms, then the output is unqualified, otherwise determine whether Pdip1 is greater than 0.9 times P before 1, Pdip1 ≥ 0.9P before 1, then automatically store the test waveform and calculation results in a word document; Pdip1 < 0.9P before 1, calculate the active recovery time tre1, if tre1 ≤ 40ms, then automatically store the test waveform and calculation results in a word document, otherwise the output is unqualified;

[0075] Step 6, calculate the voltage rise value and duration for the two-phase fault no-load test data. If the voltage rise value and duration meet the standard requirements, the no-load test data is output as qualified, otherwise the output is unqualified; determine whether the two-phase fault load test data is off-grid, if off-grid, it is judged as unqualified, otherwise further calculate the voltage rise value Uswell2 and duration tswell2 based on the fundamental line voltage, calculate the reactive current response time tres2, the reactive current duration tlast2, the reactive current exit time tree2, and calculate the active current drop depth Pdip2; determine whether Pdip2 is greater than 0.9 times P before 2, Pdip2 ≥ 0.9P before 2, then automatically store the test waveform and calculation results in a word document; Pdip2 < 0.9P before 2, calculate the active recovery time tre2, if tre2 ≤ 40ms, then automatically store the test waveform and calculation results in a word document, otherwise the output is unqualified; Step 7, for the continuous high voltage ride-through test data based on the active power P before the voltage rise 前 The judgment is divided into no-load test data and load test data, active power P 前3 Greater than 0.05 times the rated active power is the load test data, active power P 前3 Less than or equal to 0.05 times the rated active power is the no-load test data;

[0076] Preferably, in steps 5 and 6, the test result calculation process is as follows:

[0077] S1, voltage rise value U swell1 , Uswell2 is: the per unit value after the voltage rises and stabilizes;

[0078] S2, voltage rise duration t swell1 ,t swell2 is: t Uend -t Ustart ;

[0079] Among them, t Ustart is the time when the voltage increase process is completed, t Uend is the moment when the voltage starts to recover; the standard deviation of the fundamental positive sequence line voltage or fundamental phase voltage is calculated respectively. After the voltage rises to 1.1Un and before the voltage drops to 1.1Un, the moment when the standard deviation is less than 0.003 is the moment when the voltage rise process is completed; at the moment when the voltage rise process is completed t Ustart During the period from the beginning of the voltage recovery to the end of the voltage drop to 1.1Un, the first time point when the standard deviation is greater than 0.003 is the time when the voltage begins to recover.

[0080] S3, reactive current response time t res1 ,t res2 is: t Iqstart -t 1.1start ;

[0081] Among them, t Iqstart Indicates the time when the reactive current absorbed by the PV inverter continues to be greater than 90% of the reactive current injection reference value; t 1.1start Indicates the moment when the voltage rises to 1.1Un;

[0082] The reference value of reactive current injection is: 1.5*(U swell -1.1)*I n , where I n The rated current of the photovoltaic inverter, and the maximum reactive current does not exceed 1.05I n ;

[0083] S4, reactive current duration t last1 ,t last2 is: t Iqend -t Iqstart ;

[0084] Among them, t Iqend Indicates the end time when the reactive current absorbed by the PV inverter continuously exceeds 90% of the reactive current injection reference value;

[0085] S5, reactive current exit time t ree1 ,t ree2 is: t Iqtuichu -t Iqend ;

[0086] Among them, tIqtuichu Indicates that the reactive current increment is exited, that is, t Iqend After the moment, the moment when the reactive current standard deviation is less than 0.003 is the moment when the reactive current increment exits;

[0087] S6, active power recovery time t re1 ,t re2 is: t Pend -t Uend ;

[0088] Among them, t Pend Indicates the time point when the active power recovers to the value under the current light, t Uend It means that after the voltage starts to recover, the time point when the active power standard deviation is less than 0.003 is the time point when the active power recovers to the current light level.

[0089] Step 8, calculate the voltage rise value and duration of the continuous high voltage ride through no-load test data. If the voltage rise value and duration meet the standard requirements, the no-load test data is output as qualified, otherwise it is output as unqualified; judge whether the continuous high voltage ride through load test data is off-grid, if off-grid, it is judged as unqualified, otherwise the test waveform and calculation results are automatically stored in a word document.

[0090] Preferably, in steps 5, 6, and 8, the single high voltage ride through and continuous high-high voltage ride through no-load test data are determined according to GB / T 19964 standard, with a voltage deviation of ±3% and a duration deviation of ±20ms, specifically:

[0091] Voltage rise per unit value U swell :1.15±0.03,Duration t swell :10000±20ms;

[0092] Voltage rise per unit value U swell :1.2±0.03,Duration t swell :10000±20ms;

[0093] Voltage rise per unit value U swell :1.25±0.03,Duration t swell :1000±20ms;

[0094] Voltage rise per unit value U swell :1.3±0.03,Duration t swell :500±20ms;

[0095] The continuous low-high voltage ride-through no-load test data is judged according to GB / T 19963 standard. The voltage drop deviation is ±5%, the voltage rise deviation is ±3%, and the duration deviation is ±20ms. Specifically:

[0096] Voltage drop amplitude U dip :0.0+0.05,duration t dip :150±20;

[0097] Voltage increase amplitude U swell :1.30±0.03,Duration t swell :500±20.

[0098] Application Example 1

[0099] The 130%Un high voltage ride-through test results of a photovoltaic inverter with a rated active power of 3.15MW and a rated voltage of 35kV are automatically analyzed. The fundamental phase voltage, line voltage and line voltage of the fundamental positive sequence component, active power, active current, reactive power and reactive current effective value are calculated using full-wave FFT; based on the line voltage of the fundamental positive sequence component, it is screened as a single high voltage ride-through test; then it is screened as a three-phase fault according to the fundamental phase voltage, and divided into no-load test data and load test data according to the active power before the voltage rises; among them, the waveform of the photovoltaic inverter 130%Un three-phase no-load high voltage ride-through test result is as follows Figure 3 As shown, the voltage rise value U swell1 130.76%Un, duration t swell1 The test result waveform of the photovoltaic inverter 130%Un three-phase load high voltage ride-through is as follows: Figure 4 As shown in the figure, the PV inverter is not disconnected from the grid during the high voltage ride-through period, and the voltage rise value U is calculated. swell1 124.83%Un, duration t swell1 is 526.56ms, calculate the reactive current response time t res1 is 15.31ms, duration t last1 533.59ms, exit time t ree1 5.63ms; reactive current response time t res1 Less than 30ms, exit time t ree1 Less than 30ms, the active power during the fault is 99% of the power before the fault, and the result meets the requirements. The fundamental line voltage and the fundamental positive sequence component of the line voltage, active power, reactive power, active current, reactive current and calculation results are output in a word document.

[0100] The test results of 130%Un high voltage ride-through of the photovoltaic inverter under all working conditions are shown in Table 1:

[0101] Table 1 Summary of 130%Un high voltage ride-through test results of photovoltaic inverters

[0102]

[0103]

[0104] Application Example 2

[0105] The 125%Un high voltage ride-through test results of a photovoltaic inverter with a rated active power of 3.15MW and a rated voltage of 35kV are automatically analyzed. The fundamental phase voltage, line voltage and line voltage of the fundamental positive sequence component, active power, active current, reactive power and reactive current effective value are calculated using full-wave FFT; based on the line voltage of the fundamental positive sequence component, it is screened as a single high voltage ride-through test; then it is screened as a two-phase fault according to the fundamental phase voltage, and divided into no-load test data and load test data according to the active power before the voltage rises; among them, the waveform of the photovoltaic inverter 125%Un two-phase no-load high voltage ride-through test result is as follows Figure 5 As shown, the voltage rise value U swell1 124.64%Un, duration t swell1 The test result waveform of the photovoltaic inverter 125%Un two-phase load high voltage ride-through is as follows: Figure 6 As shown in the figure, the PV inverter is not disconnected from the grid during the high voltage ride-through period, and the voltage rise value U is calculated. swell1 123.17%Un, duration t swell1 The time duration is 1014ms. The standard does not require asymmetric faults to provide reactive current to support voltage recovery, and the reactive current has not reached the calculated reference value, so reactive current response calculation is not performed. The active power during the fault is 99% of the power before the fault, and the result meets the requirements. The fundamental line voltage and fundamental positive sequence component of the line voltage, active power, reactive power, active current, reactive current and calculation results are output in a word document.

[0106] The test results of 125%Un high voltage ride-through of the photovoltaic inverter under all working conditions are shown in Table 2:

[0107] Table 2 Summary of 125%Un high voltage ride-through test results of photovoltaic inverters

[0108]

[0109] Application Example 3

[0110] The high voltage ride-through test results of a photovoltaic inverter with a rated active power of 3.15MW and a rated voltage of 35kV are automatically analyzed. The fundamental phase voltage, line voltage and line voltage of the fundamental positive sequence component, active power, active current, reactive power and reactive current effective value are calculated using full-wave FFT. Based on the line voltage of the fundamental positive sequence component, continuous high voltage ride-through test is selected. According to the active power before the voltage rises, the data is divided into no-load test data and load test data. Among them, the waveform of the photovoltaic inverter continuous no-load high voltage ride-through test result is as follows: Figure 7 As shown, the voltage drop depth U dip1 0.005%Un, duration t dip1 is 164ms, the voltage rise value is U swell1 128.27%Un, duration t swell1 It is 517ms, which meets the requirements; the waveform of the photovoltaic inverter continuous load high voltage ride-through test result is as follows Figure 8 As shown in the figure, the PV inverter is not disconnected from the grid during the continuous high voltage ride-through period, and the voltage drop depth U is calculated. dip1 0.12%Un, duration t dip1 is 157ms, the voltage rise value is U swell1 127.39%Un, duration t swell1 The time taken for the fundamental wave line voltage and the fundamental wave positive sequence component line voltage, active power, reactive power, active current, reactive current and calculation results are output to a word document.

[0111] The above are only preferred specific embodiments of the present invention, but the protection scope of the present invention is not limited thereto. The substitution may be a substitution of a part of the structure, device, method step, or a complete technical solution. Any equivalent replacement or change according to the technical solution and the inventive concept of the present invention shall be covered within the protection scope of the present invention.

Claims

1. A method for automatically analyzing high voltage ride-through test results of a photovoltaic inverter, characterized in that: The steps include: Step 1, reading the high voltage ride-through test results of the photovoltaic inverter based on field testing, hardware-in-the-loop electromagnetic transient simulation or non-real-time electromagnetic transient simulation, the test results including the instantaneous values ​​of voltage and current on the high voltage side or low voltage side of the photovoltaic inverter step-up transformer; Step 2, calculating the effective value of the high voltage ride through test result of the photovoltaic inverter; Step 3, distinguishing single and continuous high voltage ride through test results based on the line voltage of the fundamental positive sequence component; Step 4: classify the single high voltage ride through test data into three-phase fault and two-phase fault; the three-phase fault and two-phase fault ride through test data are based on the active power P before the voltage rises. 前1 , P 前2 The judgment is divided into no-load test data and load test data, active power P 前1 , P 前2 Greater than 0.05 times the rated active power is the load test data, active power P 前1 , P 前2 Less than or equal to 0.05 times the rated active power is the no-load test data; Step 5: Calculate the voltage rise value and duration of the three-phase fault no-load test data. If the voltage rise value and duration meet the standard requirements, the no-load test data is output as qualified, otherwise it is output as unqualified; determine whether the three-phase fault load test data is off-grid, if it is off-grid, it is judged as unqualified, otherwise the voltage rise value U is further calculated based on the fundamental positive sequence line voltage. swell1 Duration t swell1 , calculate the reactive current response time t res1 , reactive current duration t last1 , reactive current exit time t ree1 , calculate the active power drop depth P dip1 If t res1 Greater than 30ms, or t ree1 If it is greater than 30ms, the output is unqualified, otherwise it is judged that P dip1 Is it greater than 0.9 times P 前1 , P dip1 ≥0.9P 前1 , the test waveform and calculation results are automatically stored in the word document; dip1 <0.9P 前1 , calculate the active power recovery time t re1 , if t re1 ≤40ms, the test waveform and calculation results are automatically stored in a word document, otherwise the output is unqualified; Step 6: Calculate the voltage rise value and duration for the two-phase fault no-load test data. If the voltage rise value and duration meet the standard requirements, the no-load test data is output as qualified, otherwise it is output as unqualified; determine whether the two-phase fault load test data is off-grid, if it is off-grid, it is judged as unqualified, otherwise the voltage rise value U is further calculated based on the fundamental line voltage. swell2 Duration t swell2 , calculate the reactive current response time t res2 , reactive current duration t last2 , reactive current exit time t ree2 , calculate the active power drop depth P dip2 ; Judge P dip2 Is it greater than 0.9 times P 前2 , P dip2 ≥0.9P 前2 , the test waveform and calculation results are automatically stored in the word document; dip2 <0.9P 前2 , calculate the active power recovery time t re2 , if t re2 ≤40ms, the test waveform and calculation results are automatically stored in a word document, otherwise the output is unqualified; Step 7: Calculate the continuous high voltage ride through test data based on the active power P before the voltage rises. 前3 The judgment is divided into no-load test data and load test data, active power P 前3 Greater than 0.05 times the rated active power is the load test data, active power P 前3 Less than or equal to 0.05 times the rated active power is the no-load test data; Step 8, calculate the voltage rise value and duration of the continuous high voltage ride through no-load test data. If the voltage rise value and duration meet the standard requirements, the no-load test data is output as qualified, otherwise it is output as unqualified; judge whether the continuous high voltage ride through load test data is off-grid, if off-grid, it is judged as unqualified, otherwise the test waveform and calculation results are automatically stored in a word document.

2. The method for automatically analyzing the results of a photovoltaic inverter high voltage ride through test according to claim 1, characterized in that: In step 2, full-wave FFT is used to calculate the fundamental phase voltage, line voltage and line voltage of the fundamental positive sequence component, active power, active current, reactive power and reactive current effective value.

3. The method for automatically analyzing the results of a photovoltaic inverter high voltage ride through test according to claim 1, characterized in that: In step 3, the high voltage ride-through data includes single high voltage ride-through and continuous high voltage ride-through test data, and the single high voltage ride-through test condition includes 115%~130%Un, and the continuous high voltage ride-through test condition includes a low-high voltage ride-through test: 0%Un-130%Un, or two or more consecutive high-high voltage ride-through tests 130%Un-~130%Un tests.

4. The method for automatically analyzing the results of a photovoltaic inverter high voltage ride through test according to claim 1, characterized in that: In steps 5, 6 and 8, the single high voltage ride through and continuous high-high voltage ride through no-load test data are determined according to GB / T 19964 standard, with a voltage deviation of ±3% and a duration deviation of ±20ms, specifically: Voltage rise per unit value U swell :1.15±0.03,Duration t swell :10000±20ms; Voltage rise per unit value U swell :1.2±0.03,Duration t swell :10000±20ms; Voltage rise per unit value U swell :1.25±0.03,Duration t swell :1000±20ms; Voltage rise per unit value U swell :1.3±0.03,Duration t swell :500±20ms; The continuous low-high voltage ride-through no-load test data is judged according to GB / T 19964 standard. The voltage drop deviation is ±5%, the voltage rise deviation is ±3%, and the duration deviation is ±20ms. Specifically: Voltage drop amplitude U dip :0.0+0.05,duration t dip :150±20; Voltage rise amplitude U swell :1.30±0.03,Duration t swell :500±20.

5. The method for automatically analyzing the results of a photovoltaic inverter high voltage ride through test according to claim 1, characterized in that: In step 4, the fault classification method is specifically as follows: Calculate the average fundamental phase voltage U of phases A, B, and C before the voltage drops avg ; Calculate the fundamental phase voltage average value U of phases A, B, and C respectively Aavg , U Bavg , U Cavg ; Set the judgment threshold △U to 0.4; The judgment method is: If U Aavg -U avg >△U and U Bavg -U avg >△U and U Cavg -U avg >△U, it is ABC phase fault; If U Aavg -U avg >△U and U Bavg -U avg >△U and U Cavg -U avg <△U, it is AB phase fault; If U Aavg -U avg >△U and U Bavg -U avg <△U and U Cavg -U avg >△U, it is an AC phase fault; If U Aavg -U avg <△U and U Bavg -U avg >△U and U Cavg -U avg >△U, it is a BC phase fault; An ABC phase fault is a three-phase fault, and an AB phase fault, an AC phase fault, and a BC phase fault are two-phase faults.

6. The method for automatically analyzing the results of a photovoltaic inverter high voltage ride through test according to claim 1, characterized in that: In steps 5 and 6, the test result calculation process is as follows: S1, voltage rise value U swell1 , U swell2 is: the per unit value after the voltage rises and stabilizes; S2, voltage rise duration t swell1 ,t swell2 is: t Uend -t Ustart ; Among them, t Ustart is the time when the voltage increase process is completed, t Uend is the moment when the voltage starts to recover; the standard deviation of the fundamental positive sequence line voltage or fundamental phase voltage is calculated respectively. After the voltage rises to 1.1Un and before the voltage drops to 1.1Un, the moment when the standard deviation is less than 0.003 is the moment when the voltage rise process is completed; at the moment when the voltage rise process is completed t Ustart During the period from the beginning of the voltage recovery to the end of the voltage drop to 1.1Un, the first time point when the standard deviation is greater than 0.003 is the time when the voltage begins to recover. S3, reactive current response time t res1 ,t res2 is: t Iqstart -t 1.1start ; Among them, t Iqstart Indicates the time when the reactive current absorbed by the PV inverter continuously exceeds 90% of the reactive current injection reference value; t 1.1start Indicates the moment when the voltage rises to 1.1Un; The reference value of reactive current injection is: 1.5*(U swell -1.1)*I n , where I n The rated current of the photovoltaic inverter, and the maximum reactive current does not exceed 1.05I n ; S4, reactive current duration t last1 ,t last2 is: t Iqend -t Iqstart ; Among them, t Iqend Indicates the end time when the reactive current absorbed by the PV inverter continues to be greater than 90% of the reactive current injection reference value; S5, reactive current exit time t ree1 ,t ree2 is: t Iqtuichu -t Iqend ; Among them, t Iqtuichu Indicates that the reactive current increment is exited, that is, t Iqend After the moment, the moment when the reactive current standard deviation is less than 0.003 is the moment when the reactive current increment exits; S6, active power recovery time t re1 ,t re2 is: t Pend -t Uend ; Among them, t Pend Indicates the time point when the active power recovers to the value under the current light, t Uend It means that after the voltage starts to recover, the time point when the active power standard deviation is less than 0.003 is the time point when the active power recovers to the current light level.

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