Method and system for quickly judging fault voltage ride-through capability of photovoltaic power station

Abstract

The present invention provides a method and system for quickly judging the fault voltage ride-through capability of a photovoltaic power station, and relates to the field of photovoltaic power generation technology. The method includes setting initial parameters according to the installed conditions of a photovoltaic array; selecting the fault voltage type and fault phase to be judged; judging the off-grid state of the photovoltaic array according to the operation data of the photovoltaic array; judging the ride-through state of the photovoltaic array according to the operation data of the photovoltaic array; determining the assessment voltage change rate according to the ride-through state and the fault phase of the photovoltaic array; calculating the dynamic reactive current increment and the dynamic reactive current rise time of the photovoltaic array; and calculating the dynamic reactive current proportional coefficient of the photovoltaic array according to the assessment voltage change rate and the dynamic reactive current increment. The system includes: a collector, a processor, a display and a memory. The present invention not only speeds up the calculation time of key test indicators, but also improves the efficiency of on-site testing, and is of great significance for accelerating the verification of whether a photovoltaic power station has the fault voltage ride-through capability.

Description

Technical Field

[0001] The present invention relates to the technical field of photovoltaic power generation, and in particular to a method and system for quickly judging the fault voltage ride-through capability of a photovoltaic power station. Background Art

[0002] Photovoltaic grid connection refers to the connection of solar cell arrays or photovoltaic power stations to the power grid to provide power supply.

[0003] As photovoltaic power generation accounts for an increasing proportion of electric energy, the impact of photovoltaic power generation systems on the power grid can no longer be ignored. On the one hand, photovoltaic power generation systems are usually connected to the power grid in a large-scale centralized access manner. When a fault occurs in the power grid and causes the voltage at the grid connection point to drop, once a photovoltaic power station is disconnected from the grid on a large scale, it may cause the collapse of the grid voltage and frequency, seriously affecting the safe and stable operation of the grid. Therefore, large-scale photovoltaic power stations must have low voltage ride-through capabilities. On the other hand, my country's power system structure is complex, and some areas have ultra-high voltage direct current transmission systems. Various types of faults in the DC system will cause transient high voltage phenomena. If a large photovoltaic power station does not have high voltage ride-through capabilities, it will cause a large-scale disconnection of the photovoltaic power station, which may cause the collapse of the grid voltage and frequency, seriously affecting the safe and stable operation of the grid.

[0004] The national standard GB / T 19964-2024 "Technical Regulations for Photovoltaic Power Station Access to the Power System" and the industry standards NB / T32005-2013 "Technical Regulations for Low Voltage Ride-Through Detection of Photovoltaic Power Stations" and NB / T 10324-2019 "Technical Regulations for High Voltage Ride-Through Detection of Photovoltaic Power Stations" clearly stipulate that photovoltaic power stations should have low voltage ride-through capabilities and high voltage ride-through capabilities, and require the acceptance of this function through on-site tests. However, the fault voltage ride-through capability test of photovoltaic power stations is an emerging business. At present, there are many stations to be put into operation, and the testing task is heavy. Therefore, a method for quickly judging the test results is of great significance to accelerate the verification of whether a photovoltaic power station has the fault voltage ride-through capability. Summary of the invention

[0005] The present invention aims to at least solve the technical problem in the prior art that there is a lack of a method for quickly determining the fault voltage ride-through capability of a photovoltaic power station.

[0006] To this end, a first aspect of the present invention provides a method for quickly determining the fault voltage ride-through capability of a photovoltaic power station.

[0007] A second aspect of the present invention provides a system for quickly determining the fault voltage ride-through capability of a photovoltaic power station.

[0008] The present invention provides a method for quickly judging the fault voltage ride-through capability of a photovoltaic power station, comprising:

[0009] Set initial parameters according to the installed capacity of the photovoltaic array;

[0010] Select the fault voltage type and fault phase to be determined;

[0011] According to the operation data of the photovoltaic array, the off-grid state of the photovoltaic array is judged, and the off-grid state includes off-grid and on-grid;

[0012] Determine the ride-through state of the photovoltaic array according to the operation data of the photovoltaic array, wherein the ride-through state includes high voltage ride-through, low voltage ride-through and no ride-through;

[0013] Determine the test voltage change rate according to the ride-through state and fault phase of the photovoltaic array; the test voltage is a line voltage or a phase voltage;

[0014] Calculate the dynamic reactive current increment and dynamic reactive current rise time of the photovoltaic array according to the symmetry conditions of the photovoltaic array;

[0015] Taking into account the symmetry conditions and fault conditions of the photovoltaic array, the dynamic reactive current proportional coefficient of the photovoltaic array is calculated according to the assessment voltage change rate and dynamic reactive current increment.

[0016] The method for quickly judging the fault voltage ride-through capability of a photovoltaic power station according to the above technical solution of the present invention may also have the following additional technical features:

[0017] In the above technical solution, the initial parameters include the rated capacity, voltage level, high voltage ride-through threshold value and low voltage ride-through threshold value of the photovoltaic array.

[0018] In the above technical solution, the fault voltage types include high voltage ride through and low voltage ride through, and the fault phases include phase A, phase B and phase C.

[0019] In the above technical solution, the operation data of the photovoltaic array includes phase voltage, line voltage, positive sequence voltage, negative sequence voltage, reactive current, positive sequence reactive current, negative sequence reactive current and active power.

[0020] In the above technical solution, judging the off-grid status of the photovoltaic array according to the operation data of the photovoltaic array includes:

[0021] When the active power is less than 0 and lasts for at least two seconds, the off-grid state of the PV array is judged to be off-grid, otherwise it is not off-grid.

[0022] In the above technical solution, judging the ride-through state of the photovoltaic array according to the operation data of the photovoltaic array includes:

[0023] If the positive sequence voltage per unit value meets , it is judged that the photovoltaic array enters the high voltage ride-through state;

[0024] If the positive sequence voltage per unit value meets , it is judged that the photovoltaic array enters the low voltage ride-through state;

[0025] If the positive sequence voltage per unit value meets , then the photovoltaic array is judged to be in a non-crossing state;

[0026] in, Indicates the per unit value of positive sequence voltage; Indicates the high voltage crossing threshold; Indicates the low voltage crossing threshold.

[0027] In the above technical solution, the determination of the test voltage change rate according to the ride-through state and the fault phase of the photovoltaic array includes:

[0028] Determine the test voltage according to the off-grid state, ride-through state and fault phase of the photovoltaic array;

[0029] Among them, when the ride-through state is high voltage ride-through, if the fault phases determined are phase A, phase B and phase C, the test voltage is any line voltage;

[0030] When the ride-through state is high voltage ride-through, if the fault phases are determined to be phase A and phase B, or phase B and phase C, or phase A and phase C, the test voltage is the line voltage corresponding to the fault;

[0031] When the ride-through state is low voltage ride-through, if the fault phases are determined to be phase A, phase B and phase C, the test voltage is any line voltage;

[0032] When the ride-through state is low voltage ride-through, if the fault phases are determined to be phase A and phase B, or phase B and phase C, or phase A and phase C, the test voltage is the line voltage corresponding to the fault;

[0033] When the ride-through state is low voltage ride-through, if the fault phase is determined to be phase A, phase B or phase C, the test voltage is the phase voltage corresponding to the fault;

[0034] Calculate the test voltage change rate according to the determined test voltage;

[0035] Among them, when the test voltage is the line voltage:

[0036]

[0037] When the test voltage is phase voltage:

[0038]

[0039] in, Indicates the rate of change of the voltage under test. Represents the steady-state value of line voltage, Indicates the line voltage value corresponding to the voltage mutation moment, represents the steady-state value of phase voltage, Indicates the phase voltage value corresponding to the moment of voltage mutation, U Indicates the voltage level of the PV array.

[0040] In the above technical solution, the calculation of the dynamic reactive current increment and the dynamic reactive current rise time of the photovoltaic array according to the symmetry condition of the photovoltaic array includes:

[0041] When the three-phase symmetrical voltage of the photovoltaic array increases or decreases:

[0042] Dynamic reactive current increment The calculation method is:

[0043]

[0044] Dynamic reactive current rise time The calculation method is:

[0045]

[0046] in, Indicates the steady-state value of reactive current; Indicates the moment of voltage mutation The corresponding reactive current value; Indicates that the dynamic reactive current increment changes to The time corresponding to the time;

[0047] When an asymmetric voltage rise or drop occurs in the PV array, it is necessary to calculate separately according to the positive sequence and negative sequence;

[0048] Among them, the positive sequence dynamic reactive current increment The calculation method is:

[0049]

[0050] Negative sequence dynamic reactive current increment The calculation method is:

[0051]

[0052] Positive sequence dynamic reactive current rise time The calculation method is:

[0053]

[0054] Negative sequence dynamic reactive current rise time The calculation method is:

[0055]

[0056] in, Indicates the steady-state value of positive sequence reactive current; Positive sequence reactive current corresponding to the moment of voltage mutation; Indicates the steady-state value of negative sequence reactive current; Negative sequence reactive current corresponding to the moment of voltage mutation; Indicates that the positive sequence dynamic reactive current increment changes to The time corresponding to the time; Indicates that the negative sequence dynamic reactive current increment changes to The corresponding moment.

[0057] In the above technical solution, the symmetry condition and fault condition of the photovoltaic array are considered, and the dynamic reactive current proportional coefficient of the photovoltaic array is calculated according to the voltage change rate and the dynamic reactive current increment, including:

[0058] Dynamic reactive current proportional coefficient when a three-phase symmetrical voltage drop occurs in a photovoltaic array The calculation method is:

[0059]

[0060] in, Indicates the rate of change of the voltage under test. Indicates rated current;

[0061] Dynamic reactive current proportionality coefficient when asymmetric voltage drops occur in photovoltaic arrays The calculation method is:

[0062]

[0063] in, Indicates the per unit value of positive sequence voltage;

[0064] Dynamic reactive current proportional coefficient when three-phase symmetrical voltage rise occurs in photovoltaic array The calculation method is:

[0065] .

[0066] A photovoltaic power station fault voltage ride-through capability rapid judgment system provided by the present invention is applied to the photovoltaic power station fault voltage ride-through capability rapid judgment method described in any one of the above technical solutions, and the system comprises:

[0067] Collector, used to obtain initial parameters and operating data of the photovoltaic array;

[0068] A processor, used to determine the off-grid state and ride-through state of the photovoltaic array, calculate the assessment voltage change rate, calculate the dynamic reactive current increment and dynamic reactive current rise time of the photovoltaic array, and calculate the dynamic reactive current proportional coefficient of the photovoltaic array;

[0069] A display, at least for displaying the output result of the processor;

[0070] The memory is used to store the data acquired by the collector and the output results of the processor.

[0071] In summary, due to the adoption of the above technical features, the beneficial effects of the present invention are:

[0072] A method and system for quickly judging the fault voltage ride-through capability of a photovoltaic power station designed in the present invention are suitable for quickly judging the fault voltage ride-through capability of a photovoltaic power station, can be effectively applied to the calculation of field test results, and have a high accuracy rate of the calculation results. This not only speeds up the calculation time of key test indicators, but also improves the efficiency of field testing, and is of great significance for accelerating the verification of whether a photovoltaic power station has the fault voltage ride-through capability.

[0073] Additional aspects and advantages of the present invention will become apparent from the following description or may be learned by practice of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0074] The above and / or additional aspects and advantages of the present invention will become apparent and easily understood from the description of the embodiments in conjunction with the following drawings, in which:

[0075] Figure 1 is a flow chart of a method for quickly determining fault voltage ride-through capability of a photovoltaic power station according to an embodiment of the present invention;

[0076] Figure 2 It is a control strategy flow chart of a method for quickly judging fault voltage ride-through capability of a photovoltaic power station according to an embodiment of the present invention;

[0077] Figure 3 It is a module diagram of a system for quickly judging the fault voltage ride-through capability of a photovoltaic power station according to an embodiment of the present invention. DETAILED DESCRIPTION

[0078] In order to more clearly understand the above-mentioned purpose, features and advantages of the present invention, the present invention is further described in detail below in conjunction with the accompanying drawings and specific embodiments. It should be noted that the embodiments of the present application and the features in the embodiments can be combined with each other without conflict.

[0079] In the following description, many specific details are set forth to facilitate a full understanding of the present invention. However, the present invention may also be implemented in other ways different from those described herein. Therefore, the protection scope of the present invention is not limited to the specific embodiments disclosed below.

[0080] Refer to the following Figures 1 to 3 The following describes a method and system for quickly determining the fault voltage ride-through capability of a photovoltaic power station according to some embodiments of the present invention.

[0081] Some embodiments of the present application provide a method for quickly determining the fault voltage ride-through capability of a photovoltaic power station.

[0082] like Figure 1 and Figure 2 As shown, the first embodiment of the present invention proposes a method for quickly judging the fault voltage ride-through capability of a photovoltaic power station, which mainly includes the steps of setting initial parameters, selecting the type of fault voltage to be judged, importing test data, calculating indicators and outputting results, and quickly judging the fault voltage ride-through capability of a photovoltaic power station through a convenient and fast calculation method. Specifically, the method includes steps S1-S7.

[0083] S1. Setting initial parameters according to the installed capacity of the photovoltaic array; specifically, the initial parameters include the rated capacity, voltage level, high voltage ride-through threshold value and low voltage ride-through threshold value of the photovoltaic array.

[0084] S2. Select the fault voltage type and fault phase to be determined; wherein the fault voltage type includes high voltage ride through and low voltage ride through, and the fault phase includes phase A, phase B, and phase C. This step is used to preset the fault voltage type to be determined.

[0085] S3. According to the operation data of the photovoltaic array, the off-grid state of the photovoltaic array is determined, and the off-grid state includes off-grid and on-grid. When the photovoltaic array is off-grid, it means that the current fault state has exceeded the ride-through capability of the photovoltaic array and cannot operate normally; if the photovoltaic array is not off-grid, step S4 can be performed.

[0086] S4. According to the operation data of the photovoltaic array, the ride-through state of the photovoltaic array is determined, and the ride-through state includes high voltage ride-through, low voltage ride-through and no ride-through. The next step is entered only after ensuring that the photovoltaic array has high voltage ride-through or low voltage ride-through. If no ride-through occurs, there is no need to perform subsequent steps, and the result indicating that no ride-through occurs can be directly output.

[0087] S5. Determine the test voltage change rate according to the ride-through state and the fault phase of the photovoltaic array; the test voltage is a line voltage or a phase voltage.

[0088] S6. Calculate the dynamic reactive current increment and dynamic reactive current rise time of the photovoltaic array according to the symmetry condition of the photovoltaic array.

[0089] S7. Considering the symmetry conditions and fault conditions of the photovoltaic array, the dynamic reactive current proportional coefficient of the photovoltaic array is calculated based on the assessment voltage change rate and dynamic reactive current increment.

[0090] It should be noted that the order of the above steps S1-S7 is not fixed and can be adjusted as needed, and different steps can also be performed at the same time.

[0091] In some embodiments, the operation data of the photovoltaic array includes phase voltage, line voltage, positive sequence voltage, negative sequence voltage, reactive current, positive sequence reactive current, negative sequence reactive current and active power. The operation data of the photovoltaic array can be saved in data.xls format, and each type of data is recorded in a column.

[0092] In some embodiments, step S3 determines the off-grid status of the photovoltaic array, including:

[0093] When the active power P is less than 0 and the duration T of this state is at least two seconds, that is, When the photovoltaic array is off-grid, it is judged that the off-grid state of the photovoltaic array is off-grid, and "the photovoltaic array is off-grid" is output; otherwise, it is not off-grid, and the process goes to step S4.

[0094] In some embodiments, step S4 determines the ride-through state of the photovoltaic array, including:

[0095] If the positive sequence voltage per unit value meets , it is determined that the photovoltaic array has entered a high voltage ride-through state, and the process goes to step S5.

[0096] If the positive sequence voltage per unit value meets , it is determined that the photovoltaic array has entered a low voltage ride-through state, and the process goes to step S5.

[0097] If the positive sequence voltage per unit value meets , the PV array is judged to be in the non-ride-through state and the output is “the PV array has not entered the high / low voltage ride-through”.

[0098] in, Indicates the per unit value of positive sequence voltage; Indicates the high voltage crossing threshold; Indicates the low voltage crossing threshold.

[0099] In some embodiments, determining the assessment voltage change rate according to the ride-through state and the fault phase of the photovoltaic array in step S5 includes:

[0100] Determine the test voltage according to the off-grid state, ride-through state and fault phase of the photovoltaic array;

[0101] When the ride-through state is high voltage ride-through, if the fault phases are determined to be phase A, phase B, and phase C, the test voltage is any line voltage, that is, the line voltage U AB , U BC , U CA Any set of data columns in the test voltage is used for determination;

[0102] When the ride-through state is high voltage ride-through, if the fault phases are determined to be phase A and phase B, or phase B and phase C, or phase A and phase C, the test voltage is the line voltage corresponding to the fault; for example, when the fault phases are phase A and phase B, the line voltage U AB To test the voltage; when the fault phase is phase B and phase C, select the line voltage U BC As the test voltage.

[0103] When the ride-through state is low voltage ride-through, if the fault phases are determined to be phase A, phase B and phase C, the test voltage is any line voltage;

[0104] When the ride-through state is low voltage ride-through, if the fault phases are determined to be phase A and phase B, or phase B and phase C, or phase A and phase C, the test voltage is the line voltage corresponding to the fault; for example, when the fault phases are phase A and phase C, select line voltage U CA As the test voltage.

[0105] When the ride-through state is low voltage ride-through, if the fault phase is determined to be phase A, phase B or phase C, the reference voltage is the phase voltage corresponding to the fault; for example, if the fault phase is phase B, the reference voltage is the phase voltage U B .

[0106] Calculate the test voltage change rate according to the determined test voltage;

[0107] Among them, when the test voltage is the line voltage, the three / two-phase voltage rises / drops:

[0108]

[0109] When the test voltage is the phase voltage, a single-phase voltage drop occurs:

[0110]

[0111] in, Indicates the rate of change of the voltage under test. Represents the steady-state value of line voltage, Indicates the line voltage value corresponding to the moment of voltage mutation, represents the steady-state value of phase voltage, Indicates the phase voltage value corresponding to the moment of voltage mutation, U Indicates the voltage level of the PV array.

[0112] In a specific embodiment, the differential method is used to determine the voltage mutation time, and the new differential sequence is obtained by applying the following formula to the selected entire test voltage data series: ΔV To identify the voltage mutation point, when ΔV ≥0.1 When , it is considered that the voltage changes.

[0113]

[0114] in, Indicates the change between consecutive test voltages. represents the test voltage value at time t, Indicates the test voltage value at the moment before time t.

[0115] In a specific embodiment, a statistical analysis method is used to determine the voltage steady state. From the moment of voltage mutation, n data points are used as a sliding window, and the standard deviation σ1 of each window is calculated. When the standard deviation σ1 of 10 consecutive windows is ≤ 0.05 kV, the voltage is considered to have entered a steady state. The calculation method of the standard deviation of each window is:

[0116]

[0117] in, Indicates each voltage value in the window; Represents the average value of the voltage in the window; n represents the number of voltage values ​​in the window, n ≤10.

[0118] In some embodiments, step S6 calculates the dynamic reactive current increment and the dynamic reactive current rise time of the photovoltaic array according to the symmetry condition of the photovoltaic array, including:

[0119] When the three-phase symmetrical voltage of the photovoltaic array increases or decreases:

[0120] Dynamic reactive current increment The calculation method is:

[0121]

[0122] Dynamic reactive current rise time The calculation method is:

[0123]

[0124] in, Indicates the steady-state value of reactive current; Indicates the moment of voltage mutation The corresponding reactive current value; Indicates that the dynamic reactive current increment changes to The corresponding moment;

[0125] When an asymmetric voltage rise or drop occurs in the PV array, it is necessary to calculate separately according to the positive sequence and negative sequence;

[0126] Among them, the positive sequence dynamic reactive current increment The calculation method is:

[0127]

[0128] Negative sequence dynamic reactive current increment The calculation method is:

[0129]

[0130] Positive sequence dynamic reactive current rise time The calculation method is:

[0131]

[0132] Negative sequence dynamic reactive current rise time The calculation method is:

[0133]

[0134] in, Indicates the steady-state value of positive sequence reactive current; Positive sequence reactive current corresponding to the moment of voltage mutation; Indicates the steady-state value of negative sequence reactive current; Negative sequence reactive current corresponding to the moment of voltage mutation; Indicates that the positive sequence dynamic reactive current increment changes to The time corresponding to the time; Indicates that the negative sequence dynamic reactive current increment changes to The corresponding moment.

[0135] In some embodiments, in step S7, the symmetry condition and fault condition of the photovoltaic array are considered, and the dynamic reactive current proportional coefficient of the photovoltaic array is calculated according to the assessment voltage change rate and the dynamic reactive current increment, including:

[0136] Dynamic reactive current proportional coefficient when a three-phase symmetrical voltage drop occurs in a photovoltaic array The calculation method is:

[0137]

[0138] in, Indicates the rate of change of the voltage under test. Indicates rated current;

[0139] Dynamic reactive current proportionality coefficient when asymmetric voltage drops occur in photovoltaic arrays The calculation method is:

[0140]

[0141] in, Indicates the per unit value of positive sequence voltage;

[0142] Dynamic reactive current proportional coefficient when three-phase symmetrical voltage rise occurs in photovoltaic array The calculation method is:

[0143] .

[0144] After the above calculations, the calculation results of the output assessment voltage increase / decrease percentage, dynamic reactive current rise time, and dynamic reactive current proportional coefficient can be used to analyze and judge the fault voltage ride-through capability of the photovoltaic power station. For example, each parameter can be compared with its set threshold value. When it meets the threshold requirements, it has excellent fault ride-through capability.

[0145] In a specific embodiment, the disclosed method is used for a certain grid-connected photovoltaic power station to quickly determine the fault voltage ride-through capability of the photovoltaic power station, and the specific steps are as follows.

[0146] The first step is to set the initial parameters of the calculation module, including the rated capacity P of the photovoltaic array. N =2925kW, voltage level U=35kV, high voltage ride-through threshold value U HV_pu =1.10, low voltage crossing threshold value U LV_pu =0.90.

[0147] Step 2: Select the voltage fault type as low voltage ride through and the fault phases as phase A and phase B.

[0148] Step 3: Import the running data data.xls and read the key data columns including line voltage U AB , positive sequence voltage U1, negative sequence voltage U2, positive sequence reactive current I Q1 , negative sequence reactive current I Q2 , active power P.

[0149] Step 4: If P≤0 does not appear in the active power P data column, it is determined that the PV array is not disconnected from the grid.

[0150] Step 5: Positive sequence voltage per unit value , it is determined that the PV array has entered low voltage ride-through.

[0151] Step 6: From the selection of the fault phase, we know that the test voltage is the line voltage. Select U AB As the calculation data of reference voltage.

[0152] The percentage of voltage reduction is: .

[0153] Step 7: Calculate the dynamic reactive current increment and dynamic reactive current rise time:

[0154] Positive sequence reactive current increment: ;

[0155] Negative sequence reactive current increment: ;

[0156] Positive sequence dynamic reactive current rise time ;

[0157] Negative sequence dynamic reactive current rise time .

[0158] Step 9: Dynamic reactive current proportional coefficient is:

[0159]

[0160] Step 10. After the calculation is completed, the results are output. Based on the output results, the fault voltage ride-through capability of the photovoltaic power station can be intuitively evaluated.

[0161] The second embodiment of the present invention provides a photovoltaic power station fault voltage ride-through capability rapid judgment system, which is applied to the photovoltaic power station fault voltage ride-through capability rapid judgment method described in the above embodiment, such as Figure 3 As shown, the system includes: a collector, a processor, a display, a memory and an input terminal.

[0162] The collector is used to obtain initial parameters and operating data of the photovoltaic array. In other embodiments, the data to be set can also be input through the input terminal; the processor is used to determine the off-grid state and ride-through state of the photovoltaic array, calculate the assessment voltage change rate, calculate the dynamic reactive current increment and dynamic reactive current rise time of the photovoltaic array, and calculate the dynamic reactive current proportional coefficient of the photovoltaic array; the display is used to display the processing process and output results of the processor, and can also be used for interface control by the operator; the memory is used to store the data obtained by the collector and the output results of the processor.

[0163] It should be noted that it should be understood that the division of the various modules in the above device is only a division of logical functions. In actual implementation, they can be fully or partially integrated into one physical entity, or physically separated. Moreover, these modules can be all implemented in the form of software calling through processing elements; they can also be all implemented in the form of hardware; some modules can also be implemented in the form of software calling through processing elements, and some modules can be implemented in the form of hardware.

[0164] The processing element described here can be an integrated circuit with signal processing capability. In the implementation process, each step of the above method or each module can be completed by an integrated logic circuit of hardware in the processor element or an instruction in software form.

[0165] The above-mentioned processor can be a general-purpose processor, including a central processing unit, a network processor, etc.; it can also be a digital signal processor, an application-specific integrated circuit, a field programmable gate array or other programmable logic device, a discrete gate or transistor logic device, or a discrete hardware component.

[0166] In this specification, the schematic representations of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described can be combined in any one or more embodiments or examples in a suitable manner.

[0167] Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the protection scope of the present invention.

Claims

1. A method for quickly judging the fault voltage ride-through capability of a photovoltaic power station, characterized in that: include: Set initial parameters according to the installed capacity of the photovoltaic array; Select the fault voltage type and fault phase to be determined; According to the operation data of the photovoltaic array, the off-grid state of the photovoltaic array is judged, and the off-grid state includes off-grid and on-grid; Determine the ride-through state of the photovoltaic array according to the operation data of the photovoltaic array, wherein the ride-through state includes high voltage ride-through, low voltage ride-through and no ride-through; Determine the test voltage change rate according to the ride-through state and fault phase of the photovoltaic array; the test voltage is a line voltage or a phase voltage; Calculate the dynamic reactive current increment and dynamic reactive current rise time of the photovoltaic array according to the symmetry conditions of the photovoltaic array; Considering the symmetry conditions and fault conditions of the photovoltaic array, the dynamic reactive current proportional coefficient of the photovoltaic array is calculated according to the voltage change rate and dynamic reactive current increment; Wherein, judging the off-grid status of the photovoltaic array according to the operation data of the photovoltaic array includes: When the active power is less than 0 and lasts for at least two seconds, the grid-off status of the photovoltaic array is judged to be off-grid, otherwise it is not off-grid; The step of determining the ride-through state of the photovoltaic array according to the operation data of the photovoltaic array includes: If the positive sequence voltage per unit value meets , it is judged that the photovoltaic array enters the high voltage ride-through state; If the positive sequence voltage per unit value meets , it is judged that the photovoltaic array enters the low voltage ride-through state; If the positive sequence voltage per unit value meets , then the photovoltaic array is judged to be in a non-crossing state; in, Indicates the per unit value of positive sequence voltage; Indicates the high voltage crossing threshold; Indicates the low voltage crossing threshold; The step of determining the voltage change rate according to the ride-through state and the fault phase of the photovoltaic array includes: Determine the test voltage according to the off-grid state, ride-through state and fault phase of the photovoltaic array; Among them, when the ride-through state is high voltage ride-through, if the fault phases determined are phase A, phase B and phase C, the test voltage is any line voltage; When the ride-through state is high voltage ride-through, if the fault phases are determined to be phase A and phase B, or phase B and phase C, or phase A and phase C, the test voltage is the line voltage corresponding to the fault; When the ride-through state is low voltage ride-through, if the fault phases are determined to be phase A, phase B and phase C, the test voltage is any line voltage; When the ride-through state is low voltage ride-through, if the fault phases are determined to be phase A and phase B, or phase B and phase C, or phase A and phase C, the test voltage is the line voltage corresponding to the fault; When the ride-through state is low voltage ride-through, if the fault phase is determined to be phase A, phase B or phase C, the test voltage is the phase voltage corresponding to the fault; Calculate the test voltage change rate according to the determined test voltage; Among them, when the test voltage is the line voltage: When the test voltage is phase voltage: in, Indicates the rate of change of the voltage under test. Represents the steady-state value of line voltage, Indicates the line voltage value corresponding to the voltage mutation moment, represents the steady-state value of phase voltage, Indicates the phase voltage value corresponding to the moment of voltage mutation, U Indicates the voltage level of the photovoltaic array; The step of calculating the dynamic reactive current increment and the dynamic reactive current rise time of the photovoltaic array according to the symmetry condition of the photovoltaic array includes: When the three-phase symmetrical voltage of the photovoltaic array increases or decreases: Dynamic reactive current increment The calculation method is: Dynamic reactive current rise time The calculation method is: in, Indicates the steady-state value of reactive current; Indicates the moment of voltage mutation The corresponding reactive current value; Indicates that the dynamic reactive current increment changes to The corresponding moment; When an asymmetric voltage rise or drop occurs in the PV array, it is necessary to calculate separately according to the positive sequence and negative sequence; Among them, the positive sequence dynamic reactive current increment The calculation method is: Negative sequence dynamic reactive current increment The calculation method is: Positive sequence dynamic reactive current rise time The calculation method is: Negative sequence dynamic reactive current rise time The calculation method is: in, Indicates the steady-state value of positive sequence reactive current; Positive sequence reactive current corresponding to the moment of voltage mutation; Indicates the steady-state value of negative sequence reactive current; Negative sequence reactive current corresponding to the moment of voltage mutation; Indicates that the positive sequence dynamic reactive current increment changes to The corresponding moment; Indicates that the negative sequence dynamic reactive current increment changes to The corresponding moment; The method of considering the symmetry condition and fault condition of the photovoltaic array and calculating the dynamic reactive current proportional coefficient of the photovoltaic array according to the voltage change rate and the dynamic reactive current increment includes: Dynamic reactive current proportional coefficient when a three-phase symmetrical voltage drop occurs in a photovoltaic array The calculation method is: in, Indicates the rate of change of the voltage under test. Indicates rated current; Dynamic reactive current proportionality coefficient when asymmetric voltage drops occur in photovoltaic arrays The calculation method is: in, Indicates the per unit value of positive sequence voltage; Dynamic reactive current proportional coefficient when three-phase symmetrical voltage rise occurs in photovoltaic array The calculation method is: 。 2. The method for quickly judging the fault voltage ride-through capability of a photovoltaic power station according to claim 1 is characterized in that: The initial parameters include the rated capacity, voltage level, high voltage ride-through threshold value and low voltage ride-through threshold value of the photovoltaic array.

3. The method for quickly judging the fault voltage ride-through capability of a photovoltaic power station according to claim 2 is characterized in that: The fault voltage types include high voltage ride through and low voltage ride through, and the fault phases include phase A, phase B, and phase C.

4. The method for quickly judging the fault voltage ride-through capability of a photovoltaic power station according to claim 3 is characterized in that: The operation data of the photovoltaic array includes phase voltage, line voltage, positive sequence voltage, negative sequence voltage, reactive current, positive sequence reactive current, negative sequence reactive current and active power.

5. A photovoltaic power station fault voltage ride-through capability rapid judgment system, characterized in that: A method for quickly determining fault voltage ride-through capability of a photovoltaic power station according to any one of claims 1 to 4, the system comprising: Collector, used to obtain initial parameters and operating data of the photovoltaic array; A processor, used to determine the off-grid state and ride-through state of the photovoltaic array, calculate the assessment voltage change rate, calculate the dynamic reactive current increment and dynamic reactive current rise time of the photovoltaic array, and calculate the dynamic reactive current proportional coefficient of the photovoltaic array; A display, at least for displaying the output result of the processor; The memory is used to store the data acquired by the collector and the output results of the processor.

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