Photovoltaic inverter control method and device, controller, storage medium and photovoltaic power station

Abstract

The invention provides a photovoltaic inverter control method and device, a controller, a storage medium and a photovoltaic power station. The method comprises the steps of determining a corresponding reactive power parameter compensation group according to voltage data when a voltage abrupt change fault occurs in a power grid when it is monitored that the voltage abrupt change fault occurs in the power grid; the reactive power parameter compensation group comprises a plurality of reactive power parameter compensation values arranged according to a time sequence; and from the moment when the power grid recovers from the voltage abrupt change fault, the reactive power parameter compensation group is adopted to compensate the reactive power parameter set value of the photovoltaic inverter at each sampling moment, and the compensated reactive power parameter set value is obtained, so that the reactive power parameter actual value output by the photovoltaic inverter is close to zero, and the reactive power parameter actual value output by the photovoltaic inverter is close to zero. According to the method, the reactive current trailing phenomenon output by the photovoltaic inverter after the sudden change of the power grid is recovered can be eliminated, so that the reactive output response time is shortened, and the stability of the photovoltaic system is improved.

Description

Technical Field

[0001] The present invention relates to the technical field of photovoltaic inverters, and in particular, to a control method, device, controller, storage medium and photovoltaic power station of a photovoltaic inverter. Background Art

[0002] The output power of a photovoltaic power station is intermittent and volatile due to factors such as light intensity and weather conditions, which easily causes grid voltage fluctuations. Through reactive power compensation, a photovoltaic inverter can adjust the reactive power output in real time according to the change of the grid voltage, absorb reactive power when the grid voltage rises, and output reactive power when the grid voltage drops, thereby effectively reducing voltage fluctuations and maintaining the stability of the grid voltage.

[0003] According to the technical regulations for photovoltaic power generation stations connecting to the power system, when a grid fault occurs, the reactive power response time of the photovoltaic inverter needs to be within the standard time. However, when the grid voltage crosses the fault and exits, there will be a tailing phenomenon in the reactive current output by the photovoltaic inverter, resulting in the reactive power response time of the photovoltaic inverter not meeting the corresponding requirements and affecting the stability of the system. Summary of the Invention

[0004] Embodiments of the present invention provide a control method, device, controller, storage medium and photovoltaic power station of a photovoltaic inverter to solve the problem of slow reactive power output response of the photovoltaic inverter.

[0005] In a first aspect, embodiments of the present invention provide a control method of a photovoltaic inverter, which is applied to a photovoltaic power station. The photovoltaic power station includes a photovoltaic inverter and a transformer, and the AC terminal of the photovoltaic inverter is connected to one end of the transformer, and the other end of the transformer is used to connect to the grid. The method includes:

[0006] Judge whether a voltage mutation fault occurs in the grid;

[0007] If it is monitored that the grid has the voltage mutation fault, determine a corresponding reactive power parameter compensation group according to the voltage data when the current voltage mutation fault occurs in the grid; the reactive power parameter compensation group includes a plurality of reactive power parameter compensation values arranged in chronological order;

[0008] Since the moment when the grid recovers from the voltage mutation fault, use the reactive power parameter compensation group to compensate the given value of the reactive power parameter of the photovoltaic inverter at each sampling moment to obtain a compensated given value of the reactive power parameter, so that the actual value of the reactive power parameter output by the photovoltaic inverter approaches zero.

[0009] In a possible implementation manner, the determining a corresponding reactive power parameter compensation group according to the voltage data when the current voltage mutation fault occurs in the grid includes:

[0010] Based on the formula Determine the current voltage mutation depth; where, U s represents the voltage data when the current voltage mutation fault occurs in the power grid, and U limit represents the preset voltage threshold, and K represents the current voltage mutation depth;

[0011] Look up the reactive power parameter compensation group corresponding to the current voltage mutation depth in the first preset compensation table; the first preset compensation table includes the corresponding relationship between the voltage mutation depth and the reactive power parameter compensation group.

[0012] In a possible implementation manner, before determining whether the power grid has a voltage mutation fault, the method further includes:

[0013] For each voltage mutation fault, when the power grid recovers from different voltage mutation depths of the voltage mutation fault, sample the actual values of the reactive power parameters of the photovoltaic inverter within a preset time period after the recovery moment to obtain the corresponding reactive power parameter compensation group;

[0014] Construct the first preset compensation table according to each voltage mutation depth and the corresponding reactive power parameter compensation group.

[0015] In a possible implementation manner, using the reactive power parameter compensation group to compensate the reactive power parameter compensation value at each sampling moment of the photovoltaic inverter to obtain the compensated reactive power parameter compensation value includes:

[0016] Obtain the jump coefficient corresponding to the reactive power parameter compensation group and the compensation coefficient corresponding to each reactive power parameter compensation value;

[0017] Based on the jump coefficient, determine the position of the target compensation value in the reactive power parameter compensation group;

[0018] Multiply each reactive power parameter compensation value in the reactive power parameter compensation group by the corresponding compensation coefficient to obtain the corrected reactive power parameter compensation group;

[0019] Subtract the reactive power parameter given value at the Nth sampling moment after the power grid recovers from the voltage mutation fault from the Nth reactive power parameter compensation value after the target compensation value in the corrected reactive power parameter compensation group to obtain the compensated reactive power parameter given value.

[0020] In a possible implementation manner, before obtaining the jump coefficient corresponding to the reactive power parameter compensation group and the compensation coefficient corresponding to each reactive power parameter compensation value, the method further includes:

[0021] When testing the photovoltaic inverter, obtain the actual set of reactive power parameters within a preset time after the power grid recovers from the target voltage mutation depth of the target voltage mutation fault; the target voltage mutation fault is any voltage mutation fault, and the target voltage mutation depth is any voltage mutation depth;

[0022] According to the first preset compensation table, obtain the reactive power parameter compensation group corresponding to the target voltage mutation depth of the target voltage mutation fault, and use it as the first reactive power parameter compensation group;

[0023] Align the first reactive power parameter actual value of the first reactive power parameter actual set with each reactive power parameter actual value of the first reactive power parameter compensation group in sequence, and calculate the similarity of the overlapping part of the first reactive power parameter actual set and the reactive power parameter compensation group after alignment; the first reactive power parameter actual set is the actual set of reactive power parameters within a preset time after the power grid recovers from the target voltage mutation depth of the target voltage mutation fault;

[0024] Use the reactive power parameter compensation value aligned with the first reactive power parameter actual value in the overlapping part with the highest similarity as the target compensation value;

[0025] Calculate the position difference between the first reactive power parameter compensation value in the first reactive power parameter compensation group and the target compensation value, and use it as the jump coefficient;

[0026] Align the first reactive power parameter actual value of the first reactive power parameter actual set with the target compensation value, and based on each reactive power parameter actual value and the corresponding reactive power parameter compensation value in the first reactive power parameter actual set, calculate the compensation coefficient corresponding to each reactive power parameter compensation value.

[0027] In a possible implementation, the reactive power parameters include reactive current and reactive power.

[0028] In a second aspect, an embodiment of the present invention provides a control device for a photovoltaic inverter, which is applied to a new energy power generation system. The new energy power generation system includes a photovoltaic inverter and a transformer, and the AC terminal of the photovoltaic inverter is connected to one end of the transformer, and the other end of the transformer is used to connect to the power grid; it includes:

[0029] A fault recovery judgment module, configured to judge whether a voltage mutation fault occurs in the power grid;

[0030] A reactive power parameter compensation group acquisition module, configured to, if it is monitored that the power grid has the voltage mutation fault, determine the corresponding reactive power parameter compensation group according to the voltage data when the power grid has the current voltage mutation fault; the reactive power parameter compensation group includes a plurality of reactive power parameter compensation values arranged in chronological order;

[0031] The reactive power parameter given value compensation module is used to compensate the given value of the reactive power parameter of the photovoltaic inverter at each sampling moment by using the reactive power parameter compensation group from the moment when the power grid recovers from the current voltage mutation fault, so as to obtain the compensated given value of the reactive power parameter, and make the actual value of the reactive power parameter output by the photovoltaic inverter approach zero.

[0032] In a third aspect, an embodiment of the present invention provides a controller, which includes a memory, a processor, and a computer program stored in the memory and executable on the processor. When the processor executes the computer program, it implements the steps of the control method of the photovoltaic inverter in any possible implementation manner of the first aspect above.

[0033] In a fourth aspect, an embodiment of the present invention provides a computer-readable storage medium, which stores a computer program. When the computer program is executed by a processor, it implements the steps of the control method of the photovoltaic inverter in any possible implementation manner of the first aspect above.

[0034] In a fifth aspect, an embodiment of the present invention provides a photovoltaic power station, which includes the controller described in the third aspect above.

[0035] An embodiment of the present invention provides a control method, device, controller, storage medium and photovoltaic power station for a photovoltaic inverter. When the voltage mutation fault of the power grid is monitored, the corresponding reactive power parameter compensation group is determined according to the voltage data when the current voltage mutation fault occurs in the power grid; the reactive power parameter compensation group includes a plurality of reactive power parameter compensation values arranged in chronological order; from the moment when the power grid recovers from the voltage mutation fault, the reactive power parameter compensation group is used to compensate the given value of the reactive power parameter of the photovoltaic inverter at each sampling moment, so as to obtain the compensated given value of the reactive power parameter, and make the actual value of the reactive power parameter output by the photovoltaic inverter approach zero. The above method can eliminate the trailing phenomenon of the reactive current output by the photovoltaic inverter after the power grid mutation recovers, thereby shortening the reactive power output response time and improving the stability of the photovoltaic system. Description of the Drawings

[0036] In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the following will briefly introduce the drawings required for use in the embodiments or the description of the prior art. Obviously, the following drawings are only some embodiments of the present invention. For those of ordinary skill in the art, other drawings can be obtained based on these drawings without creative efforts.

[0037] Figure 1 It is a schematic structural diagram of a photovoltaic power station provided by an embodiment of the present invention;

[0038] Figure 2It is a flowchart for implementing the control method of a photovoltaic inverter provided by an embodiment of the present invention;

[0039] Figure 3 It is a schematic structural diagram of a control device of a photovoltaic inverter provided by an embodiment of the present invention;

[0040] Figure 4 It is a schematic structural diagram of a controller provided by an embodiment of the present invention. Detailed implementation manners

[0041] In the following description, for the purpose of illustration rather than limitation, specific details such as specific system structures and technologies are presented to thoroughly understand the embodiments of the present invention. However, those skilled in the art should clearly understand that the present invention can also be implemented in other embodiments without these specific details. In other cases, detailed descriptions of well-known systems, devices, circuits, and methods are omitted to avoid unnecessary details from interfering with the description of the present invention.

[0042] In the description of the specification and the appended claims of the present application, the terms "first", "second", "third", etc. are only used for distinguishing descriptions and cannot be understood as indicating or implying relative importance.

[0043] The reference to "an embodiment" or "some embodiments" etc. in the description of the present application means that a specific feature, structure, or characteristic described in combination with the embodiment is included in one or more embodiments of the present application. Thus, the statements "in an embodiment", "in some embodiments", "in other some embodiments", "in still other embodiments", etc. that appear in different places in this specification do not necessarily refer to the same embodiment, but mean "one or more but not all embodiments", unless otherwise specifically emphasized in other ways. The terms "comprising", "including", "having", and their variants all mean "including but not limited to", unless otherwise specifically emphasized in other ways.

[0044] In addition, the "multiple" mentioned in the embodiments of the present application should be interpreted as two or more.

[0045] To make the purpose, technical solution, and advantages of the present invention clearer, the following will be described through specific embodiments with reference to the accompanying drawings.

[0046] Figure 1 It is a schematic structural diagram of a photovoltaic power station provided by an embodiment of the present invention. As Figure 1 shown, the photovoltaic power station includes photovoltaic modules, a photovoltaic inverter, and a transformer;

[0047] The output terminal of the photovoltaic module is connected to the DC terminal of the photovoltaic inverter, the AC terminal of the photovoltaic inverter is connected to the low-voltage terminal of the transformer, and the high-voltage terminal of the transformer is used to connect to the power grid. Among them, the photovoltaic inverter is a power electronic device that converts the direct current generated by the photovoltaic module into alternating current, and has core functions such as maximum power point tracking (MPPT), grid synchronization, and reactive power compensation.

[0048] When a voltage mutation fault occurs in the power grid, for example, after faults such as high-voltage ride-through, low-voltage ride-through, overvoltage, and undervoltage, the photovoltaic inverter will provide reactive power support for the power grid. For example, during high-voltage ride-through of the power grid, the inverter can offset part of the inductive reactive power by outputting capacitive reactive power (that is, injecting reactive current into the power grid), thereby reducing the power grid voltage; during low-voltage ride-through of the power grid, the photovoltaic inverter needs to absorb inductive reactive power to increase the voltage. When the high- and low-voltage ride-through faults are restored, the photovoltaic inverter needs to quickly reduce the output of the reactive power loop to zero. However, the inventor found that after the high- and low-voltage ride-through control of the photovoltaic inverter, a current tail phenomenon will occur when the high- and low-voltage ride-through faults are restored. After repeated experiments, it is found that the current tail phenomenon will still occur when simulating high- and low-voltage ride-through faults in the power grid when the photovoltaic inverter is not working. Finally, it is determined that this reactive current tail phenomenon is caused by the excitation current output by the transformer during high- and low-voltage ride-through faults. The generation of this excitation current will cause the response time of the photovoltaic inverter during reactive power withdrawal to be too long, unable to meet the standard time requirements.

[0049] Based on the above problems, this embodiment provides a control method for a photovoltaic inverter. After a voltage mutation fault occurs, a set of reactive parameter compensation groups are used to compensate the given value of the reactive parameters for a period of time after the fault is restored, so as to cancel out the trailing reactive current.

[0050] See Figure 2 , which shows the implementation flowchart of the control method for the photovoltaic inverter provided by the embodiment of the present invention, and is described in detail as follows:

[0051] S101: Determine whether a voltage mutation fault has occurred in the power grid.

[0052] In this embodiment, the controller obtains the power grid electrical parameters in real time, where the power grid electrical parameters include the power grid voltage and the power grid power.

[0053] Taking the grid voltage as an example, when the absolute value of the difference between the grid voltage and the preset voltage limit value is greater than the preset voltage difference threshold, it is determined that a voltage mutation fault has occurred in the grid voltage. The preset voltage limit value may include a preset voltage upper limit value and a preset voltage lower limit value within the normal voltage range. When the grid voltage is lower than the preset voltage lower limit value, the difference between the grid voltage and the preset voltage lower limit value is calculated. When the grid voltage is higher than the preset voltage upper limit value, the difference between the grid voltage and the preset voltage upper limit value is calculated. Then, it is determined whether a voltage mutation fault has occurred based on the absolute value of the difference. Among them, the preset voltage upper limit value and the preset voltage lower limit value within the normal voltage range can be the voltage upper limit value and the voltage lower limit value when judging the grid's high and low voltage ride-through faults, or can be the voltage upper limit value and the voltage lower limit value when judging the grid's overvoltage fault and undervoltage fault.

[0054] Specifically, the above voltage value can specifically be the effective voltage value.

[0055] As another embodiment, this embodiment can also, after obtaining the real-time grid voltage, calculate the difference between the grid voltage at the current moment and the grid voltage at the previous moment. If the difference between the grid voltages at the two moments is greater than the preset voltage mutation threshold, it is determined that a voltage mutation fault has occurred in the grid.

[0056] It can be understood that when the grid electrical parameter is the grid power, replacing the grid voltage in the above method with the grid power can also determine whether a voltage mutation fault has occurred in the grid based on the grid power. The specific process will not be elaborated here.

[0057] S102: If it is monitored that the grid has the voltage mutation fault, then according to the voltage data when the grid has the current voltage mutation fault, determine the corresponding reactive parameter compensation group; the reactive parameter compensation group includes a plurality of reactive parameter compensation values arranged in chronological order.

[0058] In this embodiment, if it is monitored that a voltage mutation fault has occurred in the grid, the current trailing phenomenon after the fault recovery caused by different voltage mutation faults is different. Therefore, this embodiment needs to determine the corresponding reactive parameter compensation group according to the voltage data when the grid voltage mutation fault occurs. Taking the current as an example, the reactive parameter compensation group includes a plurality of reactive current compensation values arranged in chronological order.

[0059] In this embodiment, the specific implementation method for determining that the grid has recovered from the voltage mutation fault is as follows:

[0060] If the difference between the grid voltage and the preset voltage limit value is less than the preset voltage difference threshold, it is determined that the grid voltage has recovered from the voltage mutation fault.

[0061] Exemplarily, when an overvoltage or high-voltage ride-through fault occurs in the grid voltage, it is determined that the grid voltage has recovered from the current voltage mutation fault when the absolute value of the difference between the grid voltage and the preset upper voltage limit value is less than the preset voltage difference threshold. When an undervoltage or low-voltage ride-through fault occurs in the grid voltage, it is determined that the grid voltage has recovered from the current voltage mutation fault when the absolute value of the difference between the grid voltage and the preset lower voltage limit value is less than the preset voltage difference threshold.

[0062] Specifically, for any voltage mutation fault, in this embodiment, the reactive current of the photovoltaic inverter at multiple consecutive sampling moments starting from the voltage mutation fault recovery moment can be directly extracted to form a reactive parameter compensation group.

[0063] Specifically, a specific implementation process of the above S102 includes:

[0064] If it is detected that a voltage mutation fault occurs in the grid, obtain the voltage data group during the current voltage mutation fault process of the grid. This voltage data group includes all voltage data from the start moment of the grid voltage mutation fault to the moment when it recovers to normal; and input the voltage data group during the current voltage mutation fault process into the neural network model to obtain the corresponding reactive parameter compensation group.

[0065] Among them, the training process of the neural network model includes:

[0066] Construct a neural network model;

[0067] Collect the voltage data group corresponding to the historical record of each voltage mutation fault, and the reactive current compensation group that can reduce the reactive current at each moment to zero within a period of time after the fault is restored after compensation;

[0068] Use the voltage data group as the training sample and the corresponding reactive current compensation group as the label to train the neural network model until the accuracy of the output result of the neural network model reaches above the preset accuracy, and complete the training of the neural network model.

[0069] The above method for determining the reactive current compensation group through the neural network model can determine the corresponding reactive current compensation group based on the voltage data group during the complete fault process, so as to improve the accuracy of the description of the voltage mutation fault, and further improve the accuracy of the reactive current compensation. At the same time, it can better adapt to the reactive current compensation scenarios of different voltage mutation faults.

[0070] In one embodiment, another specific implementation process of S102 includes:

[0071] Calculate the voltage mutation depth of the current grid voltage mutation fault according to the voltage data during the current grid voltage mutation fault process;

[0072] Input the voltage mutation depth during the current grid voltage mutation fault into the neural network model, and output the corresponding reactive power parameter compensation group; wherein, the neural network model is trained with the voltage mutation depth during the grid voltage mutation fault as the input and the reactive power parameter compensation group that makes the reactive power parameters at each sampling moment drop to zero within a period of time after the grid voltage mutation fault is restored as the output.

[0073] Specifically, to improve the accuracy of reactive power compensation, in this embodiment, the voltage mutation depth corresponding to each grid voltage during the grid voltage mutation fault process can be calculated, and then the maximum voltage mutation depth is selected as the voltage mutation depth corresponding to the current grid voltage mutation fault.

[0074] S103: Starting from the moment when the grid is restored from the voltage mutation fault, use the reactive power parameter compensation group to compensate the given value of the reactive power parameter of the photovoltaic inverter at each sampling moment to obtain the compensated given value of the reactive power parameter, so that the actual value of the reactive power output by the photovoltaic inverter approaches zero.

[0075] In this embodiment, after obtaining the reactive power parameter compensation group, starting from the moment when the grid is restored from the voltage mutation fault, subtract the corresponding reactive power compensation value in the reactive power parameter compensation group from the given value of the reactive power parameter at each sampling moment, so that after being controlled by the compensated given value of the reactive power parameter, the actual value of the reactive power output by the photovoltaic inverter quickly approaches zero.

[0076] As can be seen from the above embodiments, the above method can eliminate the trailing phenomenon of the reactive current output by the photovoltaic inverter after the grid mutation fault is restored, thereby shortening the reactive power output response time and improving the stability of the photovoltaic system.

[0077] In a possible implementation manner, the specific implementation process of S102 includes:

[0078] Based on the formula Determine the current voltage mutation depth; wherein, U s Represents the voltage data when the current voltage mutation fault occurs in the grid, U limit Represents the preset voltage threshold, and K represents the current voltage mutation depth;

[0079] Search for the reactive power parameter compensation group corresponding to the current voltage mutation depth in the first preset compensation table; the first preset compensation table includes the corresponding relationship between the voltage mutation depth and the reactive power parameter compensation group.

[0080] Specifically, the voltage data when the current voltage mutation fault occurs in the grid can take the most severe value of the mutation fault, such as the maximum voltage in the high-voltage ride-through and overvoltage faults, and the minimum voltage in the low-voltage ride-through and undervoltage faults; it can also take the average value of all voltage data during the process of the current voltage mutation fault occurring in the grid.

[0081] In this embodiment, the specific implementation process of S102 includes:

[0082] Obtain the voltage mutation depth, current distortion rate, and active power drop rate corresponding to the current voltage mutation fault of the power grid;

[0083] Perform weighted summation on the voltage mutation depth, current distortion rate, and active power drop rate corresponding to the current voltage mutation fault of the power grid to determine the fault reference index of the current voltage mutation fault;

[0084] Search for the reactive power parameter compensation group corresponding to the fault reference index of the current voltage mutation fault in the second preset compensation table; the second preset compensation table includes the corresponding relationship between the fault reference index and the reactive power parameter compensation group.

[0085] Specifically, the current distortion rate is the degree to which the current waveform deviates from the sine wave, and can be calculated based on the formula Obtained; where THDI represents the current distortion rate, Ih represents the effective value of the h - th harmonic current, I1 represents the effective value of the fundamental wave current, and n represents the harmonic order.

[0086] The active power drop degree characterizes the degree of active power decline during the power grid fault, and can be calculated based on the formula Obtained, where Kp represents the active power drop degree, Pn represents the rated active power, and Pf represents the active power during the voltage mutation fault.

[0087] After obtaining the voltage mutation depth, current distortion rate, and active power drop degree, perform normalization processing on the three, and then perform weighted summation on the normalized voltage mutation depth, current distortion rate, and active power drop degree to obtain the fault reference index.

[0088] As can be seen from the above embodiments, this embodiment jointly describes the current power grid voltage mutation fault through three different indicators, can accurately distinguish the types of power grid voltage mutation faults, and thus improve the accuracy of the corresponding reactive power parameter compensation group.

[0089] In a possible implementation manner, before S101, the method provided in this embodiment further includes:

[0090] For each voltage mutation fault, when the power grid recovers from different voltage mutation depths of the voltage mutation fault, sample the actual values of the reactive power parameters of the photovoltaic inverter within a preset time period after the recovery moment to obtain the corresponding reactive power parameter compensation group;

[0091] Construct the first preset compensation table according to each voltage mutation depth and the corresponding reactive power parameter compensation group.

[0092] In this embodiment, if the voltage mutation depth corresponding to the current voltage mutation fault is not in the first preset compensation table, the reactive power parameter compensation group corresponding to the closest voltage mutation depth is used as the reactive power parameter compensation group corresponding to the current voltage mutation fault. Alternatively, the interpolation method is used for the first preset compensation table to determine the reactive power parameter compensation group corresponding to the current voltage mutation depth.

[0093] The above method can reduce the data acquisition amount of the first preset compensation table on the basis of ensuring the accuracy of reactive power parameter compensation, thereby improving the adaptability of the first preset compensation table.

[0094] In a possible implementation manner, the specific implementation process of S103 includes:

[0095] S201: Obtain the jump coefficient corresponding to the reactive power parameter compensation group and the compensation coefficients corresponding to each reactive power parameter compensation value;

[0096] S202: Determine the position of the target compensation value in the reactive power parameter compensation group based on the jump coefficient;

[0097] S203: Multiply each reactive power parameter compensation value in the reactive power parameter compensation group by the corresponding compensation coefficient to obtain a corrected reactive power parameter compensation group;

[0098] S204: Subtract the reactive power parameter given value at the Nth sampling moment from the moment when the power grid recovers from the voltage mutation fault from the Nth reactive power parameter compensation value after the target compensation value in the corrected reactive power parameter compensation group to obtain the compensated reactive power parameter given value.

[0099] In this embodiment, since the reactive power parameter compensation groups corresponding to different photovoltaic inverter devices may be slightly different, in this embodiment, after the first preset compensation table is determined based on the experimental equipment, when it is used in a new photovoltaic power station, first, each reactive power parameter compensation group in the first preset compensation table is adaptively corrected. That is, the alignment of the initial time and amplitude is performed. Among them, the jump coefficient is a parameter characterizing the offset of the starting position of the reactive power parameter compensation group. The target compensation value represents the first reactive power parameter compensation value in the reactive power parameter compensation group that adapts to the current photovoltaic power station. The compensation coefficient is a proportional factor for amplitude correction of each value of the preset reactive power parameter compensation group.

[0100] In addition, since the reactive power parameter compensation groups between some voltage mutation depths are in a multiple relationship, in this embodiment, after there are reactive power parameter compensation groups corresponding to some voltage mutation depths in the first preset compensation table, if the current voltage mutation depth and the known voltage mutation depth are in a known multiple relationship, the compensation coefficient is determined based on the multiple relationship between the existing mutation depth and the current voltage mutation depth, and the reactive power parameter compensation value corresponding to the existing voltage mutation depth is corrected by the compensation coefficient to obtain the reactive power parameter compensation group for the current voltage mutation depth, thereby reducing the data acquisition amount and expanding the adaptability of the first preset compensation table.

[0101] The above method can further expand the adaptability of the first preset compensation table, improve the accuracy of reactive power parameter compensation, avoid the current tailing phenomenon after the grid voltage mutation recovers, and shorten the reactive power response time of the photovoltaic inverter.

[0102] In a possible implementation manner, before S201, the specific implementation process of the above S103 further includes:

[0103] When testing the photovoltaic inverter, obtain the actual reactive power parameter group within a preset time after the grid recovers from the target voltage mutation depth of the target voltage mutation fault; the target voltage mutation fault is any voltage mutation fault, and the target voltage mutation depth is any voltage mutation depth;

[0104] Obtain the reactive power parameter compensation group corresponding to the target voltage mutation depth of the target voltage mutation fault according to the first preset compensation table, and use it as the first reactive power parameter compensation group;

[0105] Align the first reactive power parameter actual value of the first reactive power parameter actual group with each reactive power parameter actual value of the first reactive power parameter compensation group in turn, and calculate the similarity of the overlapping part between the first reactive power parameter actual group and the reactive power parameter compensation group after alignment; the first reactive power parameter actual group is the actual reactive power parameter group within a preset time after the grid recovers from the target voltage mutation depth of the target voltage mutation fault;

[0106] Use the reactive power parameter compensation value aligned with the first reactive power parameter actual value in the overlapping part with the highest similarity as the target compensation value;

[0107] Calculate the position difference between the first reactive power parameter compensation value in the first reactive power parameter compensation group and the target compensation value, and use it as the jump coefficient;

[0108] Align the first reactive power parameter actual value of the first reactive power parameter actual group with the target compensation value, and calculate the compensation coefficient corresponding to each reactive power parameter compensation value based on each reactive power parameter actual value and the corresponding reactive power parameter compensation value in the first reactive power parameter actual group.

[0109] In a possible implementation, the reactive power parameters include reactive current and reactive power.

[0110] As can be seen from the above embodiments, in this embodiment, through a multi-dimensional reactive power compensation strategy, the problem of reactive current tailing of the photovoltaic inverter during the recovery of voltage mutation faults is effectively solved. By constructing a compensation table through off-line testing and dynamically correcting the compensation parameters, a significant reduction in the reactive power response time and an improvement in the compensation accuracy are achieved.

[0111] It should be understood that the magnitudes of the sequence numbers of the steps in the above embodiments do not mean the order of execution. The order of execution of each process should be determined by its function and internal logic, and should not constitute any limitation to the implementation process of the embodiments of the present invention.

[0112] The following is an embodiment of the device of the present invention. For details not described in detail, reference may be made to the corresponding method embodiments above.

[0113] Figure 3 The structural schematic diagram of the control device of the photovoltaic inverter provided by the embodiment of the present invention is shown. For the convenience of description, only the parts related to the embodiment of the present invention are shown and are described in detail as follows:

[0114] As Figure 3 shown, the control device 100 of the photovoltaic inverter includes:

[0115] A fault recovery judgment module 110, configured to judge whether a voltage mutation fault occurs in the power grid;

[0116] A reactive power parameter compensation group acquisition module 120, configured to, if it is monitored that the voltage mutation fault occurs in the power grid, determine a corresponding reactive power parameter compensation group according to the voltage data when the current voltage mutation fault occurs in the power grid; the reactive power parameter compensation group includes a plurality of reactive power parameter compensation values arranged in chronological order;

[0117] A reactive power parameter set value compensation module 130, configured to, starting from the moment when the power grid recovers from the current voltage mutation fault, compensate the reactive power parameter set value of the photovoltaic inverter at each sampling moment by using the reactive power parameter compensation group to obtain a compensated reactive power parameter set value, so that the actual value of the reactive power parameter output by the photovoltaic inverter approaches zero.

[0118] In a possible implementation, the reactive power parameter compensation group acquisition module 120 includes:

[0119] Based on the formula to determine the current voltage mutation depth; where U s represents the voltage data when the current voltage mutation fault occurs in the power grid, U limitVth represents a preset voltage threshold, and K represents the current voltage mutation depth;

[0120] Look up the reactive power parameter compensation group corresponding to the current voltage mutation depth in the first preset compensation table; the first preset compensation table includes the correspondence between the voltage mutation depth and the reactive power parameter compensation group.

[0121] In a possible implementation, the control device 100 of the photovoltaic inverter further includes a preset compensation table construction module, which is used for:

[0122] For each voltage mutation fault, when the power grid recovers from different voltage mutation depths of the voltage mutation fault, sample the actual values of the reactive power parameters of the photovoltaic inverter within a preset duration after the recovery moment to obtain the corresponding reactive power parameter compensation group;

[0123] Construct the first preset compensation table according to each voltage mutation depth and the corresponding reactive power parameter compensation group.

[0124] In a possible implementation, the reactive power parameter given value compensation module 130 includes:

[0125] Obtain the jump coefficient corresponding to the reactive power parameter compensation group and the compensation coefficients corresponding to each reactive power parameter compensation value;

[0126] Based on the jump coefficient, determine the position of the target compensation value in the reactive power parameter compensation group;

[0127] Multiply each reactive power parameter compensation value in the reactive power parameter compensation group by the corresponding compensation coefficient to obtain a corrected reactive power parameter compensation group;

[0128] Subtract the reactive power parameter given value at the Nth sampling moment after the power grid recovers from the voltage mutation fault from the Nth reactive power parameter compensation value after the target compensation value in the corrected reactive power parameter compensation group to obtain the compensated reactive power parameter given value.

[0129] In a possible implementation, the control device 100 of the photovoltaic inverter further includes a correction parameter acquisition module, which is used for:

[0130] When testing the photovoltaic inverter, obtain the actual reactive power parameter group within a preset duration after the power grid recovers from the target voltage mutation depth of the target voltage mutation fault; the target voltage mutation fault is any voltage mutation fault, and the target voltage mutation depth is any voltage mutation depth;

[0131] Obtain the reactive power parameter compensation group corresponding to the target voltage mutation depth of the target voltage mutation fault according to the first preset compensation table, and use it as the first reactive power parameter compensation group;

[0132] Align the first actual reactive parameter value of the first actual reactive parameter group with each actual reactive parameter value of the first reactive parameter compensation group in sequence, and calculate the similarity of the overlapping part between the first actual reactive parameter group and the reactive parameter compensation group after alignment; the first actual reactive parameter group is the actual reactive parameter group within a preset duration after the power grid recovers from the target voltage mutation depth of the target voltage mutation fault.

[0133] Take the reactive parameter compensation value aligned with the first actual reactive parameter value in the overlapping part with the highest similarity as the target compensation value.

[0134] Calculate the position difference between the first reactive parameter compensation value in the first reactive parameter compensation group and the target compensation value, and use it as the jump coefficient.

[0135] Align the first actual reactive parameter value of the first actual reactive parameter group with the target compensation value, and based on each actual reactive parameter value and the corresponding reactive parameter compensation value in the first actual reactive parameter group, calculate the compensation coefficient corresponding to each reactive parameter compensation value.

[0136] In a possible implementation, the reactive parameters include reactive current and reactive power.

[0137] Figure 4 It is a schematic diagram of the terminal provided by an embodiment of the present invention. As Figure 4 shown, the controller 4 of this embodiment includes: a processor 40 and a memory 41. The memory 41 is used to store a computer program 42, and the processor 40 is used to call and run the computer program 42 stored in the memory 41 to execute the steps in the above-mentioned embodiments of the control method of each photovoltaic inverter, such as Figure 2 the steps S101 to S103 shown. Alternatively, the processor 40 is used to call and run the computer program 42 stored in the memory 41 to implement the functions of each module / unit in the above-mentioned device embodiments, such as Figure 3 the functions of the modules 110 to 130 shown.

[0138] Exemplarily, the computer program 42 can be divided into one or more modules / units, and the one or more modules / units are stored in the memory 41 and executed by the processor 40 to complete the present invention. The one or more modules / units can be a series of computer program instruction segments capable of performing specific functions, and these instruction segments are used to describe the execution process of the computer program 42 in the controller 4.

[0139] The controller 4 may be a computing device such as a desktop computer, a notebook, a palm computer, and a cloud server. The controller 4 may include, but is not limited to, a processor 40 and a memory 41. Those skilled in the art can understand that Figure 4 This is only an example of the controller 4 and does not constitute a limitation on the controller 4. It may include more or fewer components than those shown in the figure, or combine some components, or different components. For example, the terminal may further include input / output devices, network access devices, a bus, etc.

[0140] The so-called processor 40 may be a central processing unit (CPU), or may also be other general-purpose processors, digital signal processors (DSPs), application specific integrated circuits (ASICs), field-programmable gate arrays (FPGAs), or other programmable logic devices, discrete gate or transistor logic devices, discrete hardware components, etc. The general-purpose processor may be a microprocessor or the processor may also be any conventional processor, etc.

[0141] The memory 41 may be an internal storage unit of the controller 4, such as the hard disk or memory of the controller 4. The memory 41 may also be an external storage device of the controller 4, such as a plug-in hard disk, a smart media card (SMC), a secure digital (SD) card, a flash card, etc. equipped on the controller 4. Further, the memory 41 may also include both an internal storage unit of the controller 4 and an external storage device. The memory 41 is used to store the computer program and other programs and data required by the terminal. The memory 41 may also be used to temporarily store data that has been output or is to be output.

[0142] Those skilled in the art can clearly understand that, for the convenience and conciseness of description, only the above division of each functional unit and module is used as an example. In actual applications, the above functions can be allocated to different functional units and modules according to needs, that is, the internal structure of the device can be divided into different functional units or modules to complete all or part of the functions described above. Each functional unit and module in the embodiment can be integrated into a processing unit, or each unit can exist physically alone, or two or more units can be integrated into one unit. The above integrated unit can be implemented in the form of hardware or in the form of a software functional unit. In addition, the specific names of each functional unit and module are only for the convenience of mutual distinction and do not limit the protection scope of this application. The specific working processes of the units and modules in the above system can refer to the corresponding processes in the foregoing method embodiments and will not be elaborated here.

[0143] In the above embodiments, the descriptions of the respective embodiments have their own emphases. For the parts not detailed or recorded in a certain embodiment, reference can be made to the relevant descriptions of other embodiments.

[0144] Those of ordinary skill in the art can realize that the units and algorithm steps of each example described in combination with the embodiments disclosed herein can be implemented by electronic hardware, or by a combination of computer software and electronic hardware. Whether these functions are executed in the form of hardware or software depends on the specific application and design constraints of the technical solution. Professional technicians can use different methods to implement the described functions for each specific application, but such implementation should not be considered to exceed the scope of the present invention.

[0145] In the embodiments provided by the present invention, it should be understood that the disclosed device / terminal and method can be implemented in other ways. For example, the device / terminal embodiments described above are only illustrative. For example, the division of the modules or units is only a logical function division. In actual implementation, there can be other division methods. For example, multiple units or components can be combined or integrated into another system, or some features can be ignored or not executed. Another point is that the displayed or discussed coupling or direct coupling or communication connection to each other can be through some interfaces. The indirect coupling or communication connection of the device or unit can be in an electrical, mechanical or other form.

[0146] The unit described as a separate component may or may not be physically separated. The component displayed as a unit may or may not be a physical unit, that is, it can be located in one place, or it can be distributed to multiple network units. Some or all of the units can be selected according to actual needs to achieve the purpose of the solution of this embodiment.

[0147] In addition, in each embodiment of the present invention, each functional unit can be integrated into a processing unit, or each unit can exist physically alone, or two or more units can be integrated into one unit. The above-mentioned integrated unit can be implemented in the form of hardware or in the form of a software functional unit.

[0148] If the integrated module / unit is implemented in the form of a software functional unit and sold or used as an independent product, it can be stored in a computer-readable storage medium. Based on this understanding, all or part of the processes in the above-described embodiment methods of the present invention can also be completed by a computer program instructing related hardware. The computer program can be stored in a computer-readable storage medium. When the computer program is executed by a processor, the steps of the above-described embodiments of the control method of each photovoltaic inverter can be implemented. Among them, the computer program includes computer program code, and the computer program code can be in the form of source code, object code, executable file or some intermediate form, etc. The computer-readable medium can include: any entity or device that can carry the computer program code, recording medium, USB flash drive, mobile hard disk, magnetic disk, optical disc, computer memory, read-only memory (ROM), random access memory (RAM), electrical carrier signal, telecommunication signal, and software distribution medium, etc. It should be noted that the content included in the computer-readable medium can be appropriately increased or decreased according to the requirements of legislation and patent practice in the jurisdiction. For example, in some jurisdictions, according to legislation and patent practice, the computer-readable medium does not include electrical carrier signals and telecommunication signals.

[0149] The above-described embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it; although the present invention has been described in detail with reference to the foregoing embodiments, those of ordinary skill in the art should understand that: they can still modify the technical solutions recorded in the foregoing embodiments, or perform equivalent replacements on some of the technical features; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the spirit and scope of the technical solutions of each embodiment of the present invention, and should all be included in the protection scope of the present invention.

Claims

1. A control method for a photovoltaic inverter, characterized in that: Applied to a photovoltaic power station, the photovoltaic power station includes a photovoltaic inverter and a transformer, and the AC end of the photovoltaic inverter is connected to one end of the transformer, and the other end of the transformer is used to connect to the power grid; the method includes: Determining whether a voltage mutation fault occurs in the power grid; If the voltage mutation fault occurs in the power grid, a corresponding reactive parameter compensation group is determined according to the voltage data of the power grid when the current voltage mutation fault occurs; the reactive parameter compensation group includes a plurality of reactive parameter compensation values ​​arranged in chronological order; From the moment when the power grid recovers from the voltage mutation fault, the reactive parameter compensation group is used to compensate the reactive parameter set value of the photovoltaic inverter at each sampling moment to obtain the compensated reactive parameter set value, so that the actual value of the reactive parameter output by the photovoltaic inverter is close to zero.

2. The control method of the photovoltaic inverter according to claim 1, characterized in that: Determining the corresponding reactive parameter compensation group according to the voltage data when the current voltage mutation fault occurs in the power grid includes: Based on the formula Determine the current voltage mutation depth; where U s Indicates the voltage data when the current voltage mutation fault occurs in the power grid, U limit represents a preset voltage threshold, and K represents the current voltage mutation depth; The reactive parameter compensation group corresponding to the current voltage mutation depth is searched in a first preset compensation table; the first preset compensation table includes a correspondence between the voltage mutation depth and the reactive parameter compensation group.

3. The control method of the photovoltaic inverter according to claim 2, characterized in that: Before determining whether a voltage mutation fault occurs in the power grid, the method further includes: For each voltage mutation fault, when the power grid recovers from different voltage mutation depths of the voltage mutation fault, sampling the actual value of the reactive parameter of the photovoltaic inverter within a preset time after the recovery moment to obtain a corresponding reactive parameter compensation group; The first preset compensation table is constructed according to each voltage mutation depth and the corresponding reactive parameter compensation group.

4. The control method of the photovoltaic inverter according to claim 2, characterized in that: The method of using the reactive parameter compensation group to compensate the reactive parameter compensation value of the photovoltaic inverter at each sampling moment to obtain the compensated reactive parameter compensation value includes: Obtaining the jump coefficient corresponding to the reactive parameter compensation group and the compensation coefficient corresponding to each reactive parameter compensation value; Based on the jump coefficient, determining the position of the target compensation value in the reactive parameter compensation group; Multiplying each reactive parameter compensation value in the reactive parameter compensation group by a corresponding compensation coefficient to obtain a modified reactive parameter compensation group; The reactive parameter given value at the Nth sampling moment from the moment when the power grid recovers from the voltage mutation fault is subtracted from the Nth reactive parameter compensation value after the target compensation value in the modified reactive parameter compensation group to obtain the compensated reactive parameter given value.

5. The control method of the photovoltaic inverter according to claim 4, characterized in that: Before obtaining the jump coefficient corresponding to the reactive parameter compensation group and the compensation coefficient corresponding to each reactive parameter compensation value, the method further includes: When testing the photovoltaic inverter, an actual group of reactive parameters within a preset time after the power grid recovers from a target voltage mutation depth of a target voltage mutation fault is obtained; the target voltage mutation fault is any voltage mutation fault, and the target voltage mutation depth is any voltage mutation depth; Acquire a reactive parameter compensation group corresponding to a target voltage mutation depth of the target voltage mutation fault according to a first preset compensation table, and use the group as a first reactive parameter compensation group; Aligning the first reactive parameter actual value of the first reactive parameter actual group with the reactive parameter actual values ​​of the first reactive parameter compensation group in sequence, and calculating the similarity of the overlapping parts of the first reactive parameter actual group and the reactive parameter compensation group after alignment; the first reactive parameter actual group is a reactive parameter actual group within a preset time after the power grid recovers from the target voltage mutation depth of the target voltage mutation fault; The reactive parameter compensation value in the overlapped portion with the highest similarity that is aligned with the first reactive parameter actual value of the first reactive parameter actual group is used as the target compensation value; Calculating a position difference between the first reactive parameter compensation value in the first reactive parameter compensation group and the target compensation value, and using the difference as the jump coefficient; The first reactive parameter actual value of the first reactive parameter actual group is aligned with the target compensation value, and based on each reactive parameter actual value and the corresponding reactive parameter compensation value in the first reactive parameter actual group, the compensation coefficient corresponding to each reactive parameter compensation value is calculated.

6. The control method of the photovoltaic inverter according to claim 1, characterized in that: Reactive parameters include reactive current and reactive power.

7. A control device for a photovoltaic inverter, characterized in that: Applied to a new energy power generation system, the new energy power generation system includes a photovoltaic inverter and a transformer, and the AC end of the photovoltaic inverter is connected to one end of the transformer, and the other end of the transformer is used to connect to the power grid; the device includes: A fault recovery judgment module is used to judge whether a voltage mutation fault occurs in the power grid; A reactive parameter compensation group acquisition module is used to determine a corresponding reactive parameter compensation group according to voltage data when the current voltage mutation fault occurs in the power grid if the voltage mutation fault is detected in the power grid; the reactive parameter compensation group includes a plurality of reactive parameter compensation values ​​arranged in chronological order; The reactive parameter given value compensation module is used to compensate the reactive parameter given value of the photovoltaic inverter at each sampling moment using the reactive parameter compensation group from the moment when the power grid recovers from the current voltage mutation fault, so as to obtain the compensated reactive parameter given value, so that the actual value of the reactive parameter output by the photovoltaic inverter is close to zero.

8. A controller, characterized in that: It comprises a processor and a memory, wherein the memory is used to store a computer program, and the processor is used to call and run the computer program stored in the memory to execute the control method of the photovoltaic inverter according to any one of claims 1 to 6.

9. A computer-readable storage medium storing a computer program, characterized in that: When the computer program is executed by a processor, the steps of the photovoltaic inverter control method as described in any one of claims 1 to 6 are implemented.

10. A photovoltaic power station, characterized in that: include: A controller as claimed in claim 8.

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