Transient state calculation method and calculation device for new energy equipment offline

Abstract

The invention provides a transient calculation method and a transient calculation device for new energy equipment offline. The method comprises the following steps: acquiring system characteristic data of a power grid system, first characteristic data of the power grid system before the new energy equipment is offline, and second characteristic data of the power grid system after the new energy equipment is offline; according to the system characteristic data, the first characteristic data and the second characteristic data, calculating an off-network correlation constant of the new energy equipment; and determining a transient voltage and / or a transient current after the new energy equipment is offline based on the correlation constant. According to the scheme provided by the invention, the overvoltage and the overvoltage can be quantitatively analyzed theoretically, the conditions for generating the overvoltage and the overcurrent can be divided more comprehensively according to the characteristics of the grid-connected moment, and the influence degree of the conditions can be evaluated.

Description

Technical Field

[0001] The present disclosure belongs to the field of electronic engineering technology, and specifically relates to a transient calculation method for off-grid new energy equipment, a calculation device, an electronic device, a computer-readable storage medium, and a computer program product. Background Art

[0002] As the proportion of renewable energy power generation continues to increase, the impact of renewable energy equipment disconnection on the power grid system is becoming increasingly apparent. When renewable energy equipment is disconnected from the grid, it is easily affected by the operating status of the power grid system and the power electronic equipment on the grid-connected branch. In addition, the analysis of the impedance characteristics of power electronic equipment when renewable energy equipment is disconnected from the grid is complex, making it difficult to accurately assess the impact of renewable energy equipment disconnection on the power grid system. Summary of the invention

[0003] The present invention aims to solve at least one of the technical problems existing in the prior art, and provides a transient calculation method, a calculation device, a computer-readable storage medium and a computer program product that can accurately evaluate the impact of new energy equipment disconnection on the power grid system. The evaluation method provided by the present disclosure can theoretically and quantitatively analyze the amplitude of transient overvoltage and overcurrent, and more comprehensively classify the conditions for generating transient overvoltage and overcurrent according to the characteristics of new energy equipment when disconnecting from the grid, and evaluate the degree of their impact.

[0004] In order to achieve the above-mentioned object, in a first aspect, the present disclosure provides a transient calculation method for a new energy device being disconnected from the grid, the method being applied to a power grid system, the power grid system comprising a new energy device and at least one branch device, the method comprising:

[0005] Acquire system characteristic data of the power grid system, first characteristic data of the power grid system before the new energy equipment is disconnected from the grid, and second characteristic data of the power grid system after the new energy equipment is disconnected from the grid;

[0006] Calculating a related constant of the new energy device being disconnected from the grid according to the system characteristic data, the first characteristic data and the second characteristic data;

[0007] The transient voltage and / or transient current of the new energy equipment after being disconnected from the grid is determined based on the relevant constants.

[0008] In some embodiments, the system characteristic data includes system inductance, system resistance, system voltage amplitude, and system voltage phase angle of the power grid system;

[0009] The first characteristic data includes a first voltage and a first current of the new energy device before the new energy device is disconnected from the grid, and a second voltage and a second current of the branch device before the new energy device is disconnected from the grid;

[0010] The second characteristic data includes a third voltage and a third current of the branch device after the new energy device is disconnected from the grid.

[0011] In some embodiments, the related constants include a current decay time constant and a current integral constant after the new energy device is disconnected from the grid; the calculation of the related constants of the new energy device being disconnected from the grid based on the system characteristic data, the first characteristic data, and the second characteristic data specifically includes:

[0012] Calculating, according to the third voltage and the third current, a third equivalent resistance and a third equivalent inductance of the branch device after the new energy device is disconnected from the grid;

[0013] Calculating the current decay time constant according to the third equivalent resistance, the third equivalent inductance, the system resistance and the system inductance;

[0014] Calculate a first steady-state current of the grid-connected point before the new energy equipment is disconnected from the grid according to the system voltage amplitude, the system resistance, the first voltage, the first current, the second voltage and the second current;

[0015] Calculate the second steady-state current of the grid-connected point after the new energy equipment is disconnected from the grid according to the system voltage amplitude, the system resistance, the third voltage and the third current;

[0016] Calculate a first phase angle between the current and the voltage at the grid connection point before the new energy equipment is disconnected from the grid according to the system inductance, the system resistance, the first voltage, the first current, the second voltage, and the second current;

[0017] Calculating a second phase angle between the current and the voltage at the grid connection point after the new energy equipment is disconnected from the grid according to the system inductance, the system resistance, the third equivalent inductance and the third equivalent resistance;

[0018] The current integral constant is calculated according to the system voltage phase angle, the first phase angle, the second phase angle, the first steady-state current, and the second steady-state current.

[0019] In some embodiments, the related constants also include a voltage integral constant after the new energy device is disconnected from the grid, and the calculation of the related constants of the new energy device being disconnected from the grid based on the system characteristic data, the first characteristic data, and the second characteristic data specifically includes:

[0020] The voltage integral constant is calculated according to the system resistance, the system inductance, the current decay time constant and the current integral constant.

[0021] In some embodiments, the first steady-state current of the grid-connected point before the new energy device is disconnected from the grid is calculated according to the system voltage amplitude, the system resistance, the first voltage, the first current, the second voltage and the second current; specifically includes:

[0022] Calculating a first resistance and a first inductance of the new energy device before the new energy device is disconnected from the grid according to the first voltage and the first current;

[0023] According to the second voltage and the second current, a second resistance and a second inductance of the branch device before the new energy device is disconnected from the grid are calculated;

[0024] According to the first resistance, the first inductance, the second resistance and the second inductance, the equivalent conductance and the equivalent susceptance of the new energy equipment and the branch equipment before the new energy equipment is disconnected from the grid are calculated;

[0025] Based on the equivalent conductance and equivalent susceptance of the new energy device and the branch device, the equivalent resistance and equivalent inductance of the new energy device and the branch device before the new energy device is disconnected from the grid are calculated;

[0026] The first steady-state current is obtained by calculation based on the equivalent resistance and equivalent inductance of the new energy equipment and the branch equipment before the new energy equipment is disconnected from the grid, as well as the system voltage amplitude, the system resistance, and the system inductance.

[0027] In some embodiments, the second steady-state current of the grid-connected point after the new energy device is disconnected from the grid is calculated according to the system voltage amplitude, the system resistance, the third voltage and the third current; specifically includes:

[0028] Calculating, according to the third voltage and the third current, a third equivalent resistance and a third equivalent inductance of the branch device after the new energy device is disconnected from the grid;

[0029] The second steady-state current is calculated according to the system voltage amplitude, the system resistance, the system inductance, and the third equivalent resistance and the third equivalent inductance.

[0030] In some embodiments, determining the transient voltage of the new energy device after it is disconnected from the grid based on the relevant constants specifically includes:

[0031] Calculating a voltage steady-state component after the new energy equipment is disconnected from the grid according to the system inductance, the system resistance, the system voltage amplitude and the system voltage phase angle, the second steady-state current and the second phase angle;

[0032] Calculating a DC voltage attenuation component after the new energy equipment is disconnected from the grid according to the voltage integral constant and the current attenuation time constant;

[0033] The transient voltage of the new energy equipment after being disconnected from the grid is calculated based on the voltage steady-state component and the voltage DC attenuation component.

[0034] In some embodiments, determining the transient current of the new energy device after being disconnected from the grid based on the relevant constant specifically includes:

[0035] Calculating a current steady-state component of the new energy device after it is disconnected from the grid according to the system voltage phase angle, the second steady-state current and the second phase angle;

[0036] Calculating a DC attenuation component of the current after the new energy device is disconnected from the grid according to the current integral constant and the current attenuation time constant;

[0037] The transient current of the new energy equipment after being disconnected from the grid is calculated based on the current steady-state component and the current DC attenuation component.

[0038] In some embodiments, the method further comprises:

[0039] Calculate the difference between the system voltage phase angle and the second phase angle as a first phase difference; and predict the risk of the new energy device being disconnected from the grid based on the current integral constant and the first phase difference; or,

[0040] The system impedance phase angle is calculated according to the system inductance and the system resistance; the difference between the second phase angle and the system impedance phase angle is calculated as the second phase difference; and the risk of the new energy equipment being disconnected from the grid is predicted based on the voltage integral constant and the second phase difference.

[0041] In some embodiments, predicting the risk of the new energy device being off-grid based on the current integral constant and the first phase difference specifically includes:

[0042] If the current integral constant is greater than 0 and the first phase difference is -pi / 2, it is determined that the power grid system has a maximum transient overcurrent risk;

[0043] If the current integral constant is less than 0 and the first phase difference is pi / 2, it is determined that the power grid system has a maximum transient overcurrent risk and the power grid system exhibits a current inversion characteristic.

[0044] In some embodiments, based on the voltage integral constant and the second phase difference, predicting the risk of the new energy device being disconnected from the grid specifically includes:

[0045] If the range of the second phase difference is [pi / 3, 5*pi / 3], it is determined that the risk of transient overvoltage occurring in the power grid system is the first risk;

[0046] If the range of the second phase difference is [0, pi / 3]∪[5*pi / 3, 2*pi], the risk of transient overvoltage occurring in the power grid system is determined to be the second risk;

[0047] If the range of the second phase difference is [2*pi, 7*pi / 3]∪[11*pi / 3, 4*pi], it is determined that the risk of transient overvoltage occurring in the power grid system is the third risk;

[0048] If the range of the second phase difference is [7*pi / 3, 11*pi / 3], the risk of transient overvoltage in the power grid system is determined to be the fourth risk; wherein,

[0049] The first risk is greater than the second risk; the second risk is greater than the third risk; and the fourth risk is greater than the third risk.

[0050] In some embodiments, based on the voltage integral constant and the second phase difference, predicting the risk of the new energy device being disconnected from the grid specifically includes:

[0051] Calculate the difference between the system voltage phase angle and half of the second phase difference, and record it as a third phase difference;

[0052] For the case where the voltage integral constant is greater than 0,

[0053] If the second phase difference is pi and the third phase difference is pi, it is determined that the transient overvoltage of the power grid system reaches a peak value under the first risk; or,

[0054] If the second phase difference is one third of pi or one third of pi, and the third phase difference is pi, it is determined that the transient overvoltage of the power grid system reaches a peak value under the second risk; or,

[0055] If the second phase difference is seven-thirds of pi or eleven-thirds of pi, and the third phase difference is -pi, it is determined that the transient overvoltage of the power grid system reaches a peak value under the third risk; or,

[0056] If the second phase difference is 3 times pi, and the third phase difference is -pi, it is determined that the transient overvoltage of the power grid system reaches a peak value under the fourth risk;

[0057] For the case where the voltage integral constant is less than 0,

[0058] If the second phase difference is pi, and the third phase difference is -pi, it is determined that the transient overvoltage of the power grid system reaches a peak value under the first risk; or,

[0059] If the second phase difference is one third of pi or one third of pi, and the third phase difference is -pi, it is determined that the transient overvoltage of the power grid system reaches a peak value under the second risk; or,

[0060] If the second phase difference is seven-thirds of pi or eleven-thirds of pi, and the third phase difference is pi, it is determined that the transient overvoltage of the power grid system reaches a peak value under the third risk; or,

[0061] If the second phase difference is 3 times of pi, and the third phase difference is pi, it is determined that the transient overvoltage of the power grid system reaches a peak value under the fourth risk.

[0062] In a second aspect, the present disclosure further provides a transient computing device for off-grid new energy equipment, comprising:

[0063] An acquisition module, used to acquire system characteristic data of the power grid system, first characteristic data of the power grid system before the new energy device is disconnected from the grid, and second characteristic data of the power grid system after the new energy device is disconnected from the grid;

[0064] A calculation module, used for calculating the relevant constant of the new energy equipment being off-grid according to the system characteristic data, the first characteristic data and the second characteristic data;

[0065] A determination module is used to determine the transient voltage and / or transient current of the new energy equipment after it is disconnected from the grid based on the relevant constants.

[0066] In some embodiments, the system characteristic data includes system inductance, system resistance, system voltage amplitude, and system voltage phase angle of the power grid system;

[0067] The first characteristic data includes a first voltage and a first current of the new energy device before the new energy device is disconnected from the grid, and a second voltage and a second current of the branch device before the new energy device is disconnected from the grid;

[0068] The second characteristic data includes a third voltage and a third current of the branch device after the new energy device is disconnected from the grid.

[0069] In some embodiments, the related constants include a current decay time constant and a current integral constant after the new energy device is disconnected from the grid; the calculation module includes a first calculation module and a second calculation module, and the second calculation module includes a first sub-calculation module, a second sub-calculation module and a third sub-calculation module, wherein,

[0070] The first computing module is used to perform the following steps:

[0071] Calculating, according to the third voltage and the third current, a third equivalent resistance and a third equivalent inductance of the branch device after the new energy device is disconnected from the grid;

[0072] Calculating the current decay time constant according to the third equivalent resistance, the third equivalent inductance, the system resistance and the system inductance;

[0073] The first sub-calculation module is used to calculate a first steady-state current of the grid connection point before the new energy equipment is disconnected from the grid according to the system voltage amplitude, the system resistance, the first voltage, the first current, the second voltage and the second current;

[0074] The second sub-calculation module is used to calculate the second steady-state current of the grid-connected point after the new energy equipment is disconnected from the grid according to the system voltage amplitude, the system resistance, the third voltage and the third current;

[0075] The third sub-computing module is used to perform the following steps:

[0076] Calculate a first phase angle between the current and the voltage at the grid connection point before the new energy equipment is disconnected from the grid according to the system inductance, the system resistance, the first voltage, the first current, the second voltage, and the second current;

[0077] Calculating a second phase angle between the current and the voltage at the grid connection point after the new energy equipment is disconnected from the grid according to the system inductance, the system resistance, the third equivalent inductance and the third equivalent resistance;

[0078] The current integral constant is calculated according to the system voltage phase angle, the first phase angle, the second phase angle, the first steady-state current, and the second steady-state current.

[0079] In some embodiments, the related constants further include a voltage integral constant after the new energy device is disconnected from the grid, and the calculation module further includes a third calculation module, wherein the third calculation module is used to perform the following steps:

[0080] The voltage integral constant is calculated according to the system resistance, the system inductance, the current decay time constant and the current integral constant.

[0081] In some embodiments, the first submodule is specifically configured to perform the following steps:

[0082] Calculating a first resistance and a first inductance of the new energy device before the new energy device is disconnected from the grid according to the first voltage and the first current;

[0083] According to the second voltage and the second current, a second resistance and a second inductance of the branch device before the new energy device is disconnected from the grid are calculated;

[0084] According to the first resistance, the first inductance, the second resistance and the second inductance, the equivalent conductance and the equivalent susceptance of the new energy equipment and the branch equipment before the new energy equipment is disconnected from the grid are calculated;

[0085] Based on the equivalent conductance and equivalent susceptance of the new energy device and the branch device, the equivalent resistance and equivalent inductance of the new energy device and the branch device before the new energy device is disconnected from the grid are calculated;

[0086] The first steady-state current is obtained by calculation based on the equivalent resistance and equivalent inductance of the new energy equipment and the branch equipment before the new energy equipment is disconnected from the grid, as well as the system voltage amplitude, the system resistance, and the system inductance.

[0087] In some embodiments, the second submodule is specifically configured to perform the following steps:

[0088] Calculating, according to the third voltage and the third current, a third equivalent resistance and a third equivalent inductance of the branch device after the new energy device is disconnected from the grid;

[0089] The second steady-state current is calculated according to the system voltage amplitude, the system resistance, the system inductance, and the third equivalent resistance and the third equivalent inductance.

[0090] In some embodiments, the determination module includes a first determination submodule, wherein:

[0091] The first determining submodule is used to perform the following steps:

[0092] Calculating a voltage steady-state component after the new energy equipment is disconnected from the grid according to the system inductance, the system resistance, the system voltage amplitude and the system voltage phase angle, the second steady-state current and the second phase angle;

[0093] Calculating a DC voltage attenuation component after the new energy equipment is disconnected from the grid according to the voltage integral constant and the current attenuation time constant;

[0094] The transient voltage of the new energy equipment after being disconnected from the grid is calculated based on the voltage steady-state component and the voltage DC attenuation component.

[0095] In some embodiments, the determination module includes a second determination submodule, wherein:

[0096] The second determining submodule is used to perform the following steps:

[0097] Calculating a current steady-state component of the new energy device after it is disconnected from the grid according to the system voltage phase angle, the second steady-state current and the second phase angle;

[0098] Calculating a DC attenuation component of the current after the new energy device is disconnected from the grid according to the current integral constant and the current attenuation time constant;

[0099] The transient current of the new energy equipment after being disconnected from the grid is calculated based on the current steady-state component and the current DC attenuation component.

[0100] In some embodiments, the transient calculation device further includes a prediction module, the prediction module includes a current prediction module and a voltage prediction module, wherein:

[0101] The current module is used to calculate the difference between the system voltage phase angle and the second phase angle as a first phase difference; and predict the risk of the new energy device being disconnected from the grid based on the current integral constant and the first phase difference;

[0102] The voltage prediction module is used to calculate the system impedance phase angle according to the system inductance and the system resistance; calculate the difference between the second phase angle and the system impedance phase angle as the second phase difference; and predict the risk of the new energy equipment being disconnected from the grid based on the voltage integral constant and the second phase difference.

[0103] In some embodiments, the current prediction module is specifically used to perform the following steps:

[0104] If the current integral constant is greater than 0 and the first phase difference is -pi / 2, it is determined that the power grid system has a maximum transient overcurrent risk;

[0105] If the current integral constant is less than 0 and the first phase difference is pi / 2, it is determined that the power grid system has a maximum transient overcurrent risk and the power grid system exhibits a current inversion characteristic, where pi represents pi.

[0106] In some embodiments, the voltage prediction module is specifically configured to perform the following steps:

[0107] If the range of the second phase difference is [pi / 3, 5*pi / 3], it is determined that the risk of transient overvoltage occurring in the power grid system is the first risk;

[0108] If the range of the second phase difference is [0, pi / 3]∪[5*pi / 3, 2*pi], the risk of transient overvoltage occurring in the power grid system is determined to be the second risk;

[0109] If the range of the second phase difference is [2*pi, 7*pi / 3]∪[11*pi / 3, 4*pi], it is determined that the risk of transient overvoltage occurring in the power grid system is the third risk;

[0110] If the range of the second phase difference is [7*pi / 3, 11*pi / 3], the risk of transient overvoltage in the power grid system is determined to be the fourth risk; wherein,

[0111] The first risk is greater than the second risk; the second risk is greater than the third risk; the fourth risk is greater than the third risk, and pi represents pi.

[0112] In some embodiments, the voltage prediction module is further configured to perform the following steps:

[0113] Calculate the difference between the system voltage phase angle and half of the second phase difference, and record it as a third phase difference;

[0114] For the case where the voltage integral constant is greater than 0,

[0115] If the second phase difference is pi and the third phase difference is pi, it is determined that the transient overvoltage of the power grid system reaches a peak value under the first risk; or,

[0116] If the second phase difference is one third of pi or one third of pi, and the third phase difference is pi, it is determined that the transient overvoltage of the power grid system reaches a peak value under the second risk; or,

[0117] If the second phase difference is seven-thirds of pi or eleven-thirds of pi, and the third phase difference is -pi, it is determined that the transient overvoltage of the power grid system reaches a peak value under the third risk; or,

[0118] If the second phase difference is 3 times pi, and the third phase difference is -pi, it is determined that the transient overvoltage of the power grid system reaches a peak value under the fourth risk;

[0119] For the case where the voltage integral constant is less than 0,

[0120] If the second phase difference is pi, and the third phase difference is -pi, it is determined that the transient overvoltage of the power grid system reaches a peak value under the first risk; or,

[0121] If the second phase difference is one third of pi or one third of pi, and the third phase difference is -pi, it is determined that the transient overvoltage of the power grid system reaches a peak value under the second risk; or,

[0122] If the second phase difference is seven-thirds of pi or eleven-thirds of pi, and the third phase difference is pi, it is determined that the transient overvoltage of the power grid system reaches a peak value under the third risk; or,

[0123] If the second phase difference is 3 times of pi, and the third phase difference is pi, it is determined that the transient overvoltage of the power grid system reaches a peak value under the fourth risk.

[0124] In a third aspect, the present disclosure further provides an electronic device, comprising a memory, a processor, and a computer program stored in the memory and executable on the processor, wherein when the processor executes the program, the computing method of the first aspect described above is implemented.

[0125] In a fourth aspect, the present disclosure further provides a computer-readable storage medium storing a computer program for executing the computing method of the first aspect.

[0126] In a fifth aspect, the present disclosure further provides a computer program product, including a computer program / instruction, which implements the steps of the computing method of the first aspect when the computer program / instruction is executed by a processor.

[0127] The present disclosure can calculate the relevant constants of the new energy equipment disconnection based on the steady-state voltage and steady-state current of the new energy equipment and the branch equipment before and after the new energy equipment is disconnected from the grid, and then accurately calculate the transient voltage and transient current generated at the moment when the new energy equipment is disconnected from the grid based on the relevant constants, and can accurately evaluate the impact of overvoltage and overcurrent on the power grid system during the process of the new energy equipment disconnecting from the grid in theory. At the same time, the present disclosure can also evaluate the impact of the new energy equipment disconnection from the grid based on the calculated relevant constants. The evaluation method can more comprehensively divide the conditions for generating overvoltage and overcurrent according to the characteristics of the disconnection moment, so that the evaluation result is more accurate, thereby more accurately evaluating its impact. BRIEF DESCRIPTION OF THE DRAWINGS

[0128] In order to more clearly illustrate the embodiments of the present disclosure or the technical solutions in the prior art, the drawings required for use in the description of the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present disclosure. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0129] Figure 1 A schematic diagram of an equivalent circuit of a new energy equipment grid connection point provided by an embodiment of the present disclosure;

[0130] Figure 2 A flowchart of a transient calculation method for a new energy device off-grid provided in an embodiment of the present disclosure;

[0131] Figure 3 A flowchart of another transient calculation method provided by an embodiment of the present disclosure;

[0132] Figure 4 A flowchart of another transient calculation method provided by an embodiment of the present disclosure;

[0133] Figure 5 A transient computing device for off-grid new energy equipment provided in an embodiment of the present disclosure;

[0134] Figure 6 A transient computing device for off-grid new energy equipment is provided in an embodiment of the present disclosure. DETAILED DESCRIPTION

[0135] In order to enable those skilled in the art to better understand the technical solution of the present invention, the present invention is further described in detail and completely in conjunction with the accompanying drawings and specific implementation methods. Obviously, the described embodiments are only part of the embodiments of the present disclosure, rather than all the embodiments. Based on the embodiments in the present disclosure, all other embodiments obtained by ordinary technicians in the field without making creative work are within the scope of protection of the present disclosure.

[0136] In a first aspect, an embodiment of the present disclosure provides a transient calculation method for a new energy device being disconnected from the grid. The calculation method can be applied to a power grid system, which includes a new energy device and at least one branch device.

[0137] Specifically, the whole of the power system consisting of substations and transmission and distribution lines of various voltages is called the power grid system, which includes three units: substation, transmission, and distribution. The task of the power grid system is to transmit and distribute electric energy and change the voltage. In the power grid system, new energy equipment usually refers to equipment related to renewable energy power generation, which can include but is not limited to the following:

[0138] Wind turbine: equipment that converts wind energy into electrical energy, including onshore wind power and offshore wind power equipment.

[0139] Photovoltaic power generation equipment: Equipment that uses solar panels to convert sunlight into electrical energy.

[0140] Energy storage equipment: such as battery energy storage systems, used to store excess electrical energy for use in case of emergency.

[0141] It should be noted that the branch equipment in the power grid system can also be a type of new energy equipment, and of course it can also be other power equipment, and this disclosure does not limit this. In order to distinguish the equipment to be disconnected from the power grid system from other equipment, this disclosure refers to the equipment to be disconnected from the power grid system as new energy equipment, and other equipment except the new energy equipment to be disconnected from the power grid as branch equipment. This disclosure aims to study the impact of new energy equipment on the operation of the power grid system before and after it is disconnected.

[0142] Figure 1 This is a schematic diagram of an equivalent circuit of a new energy equipment grid connection point provided by an embodiment of the present disclosure. Figure 1 As shown, R x With wL x The branch where it is located can represent the new energy equipment to be disconnected from the grid, where R x Indicates the resistance of new energy equipment, L x represents the inductance of new energy equipment, w represents the speed at the power frequency; R d1 With wL d1 The branch road 、 R d2 With wL d2 The branch road is...R dm With wL dm The branches where they are located represent multiple branch devices of the power grid system. dm Indicates the resistance of the mth branch device, L dm Represents the inductance of the mth branch device, and m is a positive integer. The power grid system provided by the embodiment of the present disclosure includes at least one branch device, that is, m is a positive integer greater than or equal to 1. Rs represents the system resistance of the power grid system, Ls represents the system inductance of the power grid system, Um*sin(wt+α) represents the system voltage of the power grid system, Um is the system voltage amplitude, α is the system voltage phase angle, and w is the speed at the power frequency, which is generally taken as 314.

[0143] It should be noted that in the embodiment of the present disclosure, it is assumed that the power grid system is not affected by the operation of the new energy equipment before and after the new energy equipment is disconnected from the grid. That is, in the embodiment of the present disclosure, the system resistance Rs, system inductance Ls, system voltage amplitude Um and system voltage phase angle α of the power grid system are constant by default.

[0144] Figure 2 The present invention provides a flow chart of a transient calculation method for a new energy device disconnected from the grid. Figure 2 As shown, the transient calculation method includes steps S1 to S3, specifically including:

[0145] S1. Obtain system characteristic data of the power grid system, first characteristic data of the power grid system before the new energy equipment is disconnected from the grid, and second characteristic data of the power grid system after the new energy equipment is disconnected from the grid.

[0146] Specifically, the system characteristic data of the power grid system refers to parameter data that is not affected by the disconnection of new energy equipment from the grid and remains constant during the operation of the power grid system. Optionally, the system characteristic data may include the system inductance Ls, system resistance Rs, system voltage amplitude Um and system voltage phase angle α of the power grid system. It should be noted that the system inductance mentioned in the present disclosure refers to the equivalent inductance of the power grid system, and the system voltage refers to the equivalent voltage of the power grid system.

[0147] The first characteristic data and the second characteristic data refer to parameter data that change during the operation of the power grid system due to the disconnection of new energy equipment from the grid, wherein the first characteristic data refers to the parameter data of the power grid system before the new energy equipment is disconnected from the grid, and the second characteristic data refers to the parameter data of the power grid system after the new energy equipment is disconnected from the grid.

[0148] In some embodiments, the first characteristic data includes a first voltage and a first current of the new energy device before the new energy device is disconnected from the grid, and a second voltage and a second current of the branch device before the new energy device is disconnected from the grid.

[0149] Specifically, the first voltage and the second voltage are both steady-state voltages, and the first current and the second current are both steady-state currents. Before the new energy device is disconnected from the grid, the waveform of the first voltage of the new energy device is: U x0 *sin(wt+α x0 ); The waveform of the first current is Among them, U x0 is the amplitude of the first voltage, I x0 is the amplitude of the first current, α x0 is the first voltage phase angle, is the phase angle between the first voltage and the first current.

[0150] This disclosure assumes that there is only one branch device at the grid connection point. Before the new energy equipment is disconnected from the grid, the waveform of the second voltage of the branch device (other branches at the grid connection point of the new energy equipment) is: U d0 *sin(wt+α d0 ), the waveform of the second current is: Among them, U d0 is the amplitude of the second voltage, I d0 is the amplitude of the second current, α d0 is the second voltage phase angle, is the phase angle between the second voltage and the second current. It is understandable that if there are multiple branch devices in the power grid system, the multiple branch devices can be aggregated into one branch device according to the impedance characteristics, and then the second voltage and second current of the branch device are calculated. Among them, the second voltage refers to the equivalent voltage of each branch device of the power grid system before the new energy device is disconnected from the grid, and the second current refers to the equivalent current of each branch device of the power grid system before the new energy device is disconnected from the grid.

[0151] In some embodiments, the second characteristic data includes a third voltage and a third current of the branch device after the new energy device is disconnected from the grid.

[0152] Specifically, the third voltage is a steady-state voltage, and the third current is a steady-state current. This disclosure assumes that there is only one branch device at the grid connection point. After the new energy device is disconnected from the grid, the waveform of the third voltage of the branch device (other branches at the grid connection point of the new energy device) is: U d *sin(wt+α d ), the waveform of the third current is: Among them, U d is the amplitude of the third voltage, I d is the amplitude of the third current, α d is the third voltage phase angle, It is the phase angle between the third voltage and the third current. It is understandable that if there are multiple branch devices in the power grid system, the multiple branch devices can be aggregated into one branch device according to the impedance characteristics, and then the third voltage and the third current of the branch device are calculated. Among them, the third voltage refers to the equivalent voltage of each branch device of the power grid system after the new energy device is disconnected from the grid, and the third current refers to the equivalent current of each branch device of the power grid system after the new energy device is disconnected from the grid.

[0153] S2. Calculate the relevant constants of the new energy equipment being disconnected from the grid according to the system characteristic data, the first characteristic data and the second characteristic data.

[0154] Specifically, the related constant is calculated based on the first characteristic data and the second characteristic data before and after the new energy equipment is disconnected from the grid. Therefore, the related constant can characterize the changes in the power grid system before and after the new energy equipment is disconnected from the grid.

[0155] S3. Determine the transient voltage and / or transient current of the new energy equipment after it is disconnected from the grid based on relevant constants.

[0156] Among them, transient voltage and transient current will be generated at the moment when new energy equipment is disconnected from the grid.

[0157] Optionally, the related constant may include the current decay time constant T after the new energy device is disconnected from the grid a , at least one of the current integration constant C and the voltage integration constant M, and the transient voltage and / or transient current can be calculated based on the relevant constants.

[0158] According to the embodiments of the present disclosure, the relevant constants of the new energy equipment being disconnected from the grid can be calculated based on the steady-state voltage and steady-state current of the new energy equipment and the branch equipment before and after the new energy equipment is disconnected from the grid. Furthermore, the transient voltage and transient current generated at the moment the new energy equipment is disconnected from the grid can be accurately calculated based on the relevant constants, and the impact of overvoltage and overcurrent on the power grid system during the process of the new energy equipment being disconnected from the grid can be accurately evaluated theoretically.

[0159] Figure 3 A flowchart of another transient calculation method provided by an embodiment of the present disclosure.

[0160] In some embodiments, the related constants include the current decay time constant T after the new energy device is disconnected from the grid a and the current integration constant C.

[0161] like Figure 3 As shown, step S2, calculating the relevant constants of the new energy equipment being off-grid according to the system characteristic data, the first characteristic data and the second characteristic data, includes S21 to S27, specifically including:

[0162] S21. Calculate, based on the third voltage and the third current, a third equivalent resistance and a third equivalent inductance of the branch device after the new energy device is disconnected from the grid.

[0163] Specifically, the amplitude U of the third voltage can be determined according to the third voltage and the third current obtained in step S1. d , the amplitude of the third current I d , and the third voltage phase angle α d .

[0164] Calculate the third resistance R of the branch equipment after the new energy equipment is disconnected from the grid d : R d =U d / I d *cos(α d ), the third inductor L d :L d =U d / I d *sin(α d ) / w, where w is the speed at the industrial frequency, which is generally taken as 314. The third resistor and the third inductor are the equivalent resistance and equivalent inductance of each branch device after the new energy equipment is disconnected from the grid.

[0165] S22. Calculate the current decay time constant according to the third equivalent resistance, the third equivalent inductance, the system resistance, and the system inductance.

[0166] Specifically, after the new energy equipment is disconnected from the grid, the current decay time constant T a=T a =(L s +L d ) / (R s +R d ) is set, and the unit is s.

[0167] It is understandable that the current decay time constant may also be calculated in other ways, and the present disclosure does not limit this.

[0168] S23. Calculate a first steady-state current of the grid-connected point of the new energy equipment before it is disconnected from the grid according to the system voltage, the system resistance, the first voltage, the first current, the second voltage, and the second current.

[0169] In some embodiments, step S23 includes S231 to S235, specifically including:

[0170] S231. Calculate, based on the first voltage and the first current, a first resistance and a first inductance of the new energy device before the new energy device is disconnected from the grid.

[0171] Specifically, the amplitude U of the first voltage can be determined according to the first voltage and the first current obtained in step S1. x0 , the amplitude of the first current I x0 , and the first voltage phase angle α x0 .

[0172] Calculate the first resistance R of the new energy equipment before it is disconnected from the grid x0 : R x0 =U x0 / I x0 *cos(α x0 ), the first inductor L x0 :L x0 =U x0 / I x0 *sin(α x0 ) / w.

[0173] S232. Calculate, based on the second voltage and the second current, a second resistance and a second inductance of the branch device before the new energy device is disconnected from the grid.

[0174] Specifically, the amplitude U of the second voltage can be determined according to the second voltage and the second current obtained in step S1. d0 , the amplitude of the second current I d0 , and the second voltage phase angle α d0 .

[0175] Calculate the second resistance R of the new energy equipment before it is disconnected from the grid d0 : R d0 =Ud0 / I d0 *cos(α d0 ), the second inductor I d0 :L d0 =U d0 / I d0 *sin(α d0 ) / w.

[0176] S233. Calculate, based on the first resistance, the first inductance, the second resistance, and the second inductance, the equivalent conductance and equivalent susceptance of the new energy equipment and the branch equipment before the new energy equipment is disconnected from the grid.

[0177] Specifically, before the new energy equipment is disconnected from the grid, the equivalent conductance G of the new energy equipment and the branch equipment is pcc0 For: G pcc0 =R d0 / (R d0 *R d0 +w*w*L d0 *L d0 )+R x0 / (R x0 *R x0 +w*w*L x0 *L x0 );

[0178] Before the new energy equipment is disconnected from the grid, the equivalent electrical susceptance of the new energy equipment and the branch equipment is B pcc0 For: B pcc0 =-w*L d0 / (R d0 *R d0 +w*w*L d0 *L d0 )-w*L x0 / (R x0 *R x0 +w*w*L x0 *L x0 ).

[0179] S234. Based on the equivalent conductance and equivalent susceptance of the new energy device and the branch device, calculate the equivalent resistance and equivalent inductance of the new energy device and the branch device before the new energy device is disconnected from the grid.

[0180] Specifically, according to the equivalent admittance Y of the new energy equipment and branch equipment before the new energy equipment is disconnected from the grid pcc0 : Y pcc0 =G pcc0 +j*B pcc0 ; and the equivalent impedance Z of the new energy equipment and the branch equipment before the new energy equipment is disconnected from the grid pcc0 :Z pcc0=R pcc0 +j*w*L pcc0 =1 / Y pcc0 ; It can be calculated that before the new energy equipment is disconnected from the grid, the equivalent resistance of the new energy equipment and the branch equipment is R pcc0 =G pcc0 / (G pcc0 *G pcc0 +B pcc0 *B pcc0 ), the equivalent inductance is L pcc0 =-B pcc0 / (G pcc0 *G pcc0 +B pcc0 *B pcc0 ) / w. Wherein, w is the speed at the working frequency, and j is the imaginary unit.

[0181] S235. Calculate the first steady-state current according to the equivalent resistance and equivalent inductance of the new energy equipment and the branch equipment before the new energy equipment is disconnected from the grid, as well as the system voltage, the system resistance, and the system inductance.

[0182] Specifically, before the new energy equipment is disconnected from the grid, the first steady-state current I m0 for:

[0183] I m0 =U m / sqrt((R s +R pcc0 )*(R s +R pcc0 )+w*w*(L s +L pcc0 )*(L s +L pcc0 )).

[0184] Returning to S23, after executing S23, executing S24, calculating the second steady-state current of the grid-connected point after the new energy equipment is disconnected from the grid according to the system voltage, the system resistance, the third voltage and the third current.

[0185] Specifically, step S24 of calculating the second steady-state current of the grid-connected point after the new energy equipment is disconnected from the grid includes S241-S242, which specifically includes:

[0186] S241, calculating the third equivalent resistance and the third equivalent inductance of the branch device after the new energy device is disconnected from the grid according to the third voltage and the third current. Similar to the above step S21, calculating the third resistance R of the branch device after the new energy device is disconnected from the grid d : R d =U d / I d*cos(α d ), the third inductor L d :L d =U d / I d *sin(α d ) / w.

[0187] S242: Calculate the second steady-state current according to the system voltage, the system resistance, the system inductance, and the third equivalent resistance and the third equivalent inductance.

[0188] Specifically, after the new energy equipment is disconnected from the grid, the second steady-state current I m for:

[0189] I m =U m / sqrt((R s +R d )*(R s +R d )+w*w*(L s +R d )*(L s +R d )).

[0190] Return to S24. After executing S24, continue to execute S25 to calculate the first phase angle between the current and voltage at the grid connection point before the new energy equipment is disconnected from the grid according to the system inductance, the system resistance, the first voltage, the first current, the second voltage and the second current.

[0191] Specifically, first refer to step S234, and calculate the equivalent resistance R between the new energy device and the branch device before the new energy device is disconnected from the grid according to the first voltage, the first current, the second voltage and the second current. pcc0 and equivalent inductance L pcc0 ; Then based on the equivalent resistance R of the new energy equipment and the branch equipment before the new energy equipment is disconnected from the grid pcc0 and equivalent inductance L pcc0 , and the system inductance L s , the system resistance R s Calculate the first phase angle between the current and voltage at the grid connection point before the new energy equipment is disconnected from the grid System impedance phase angle

[0192] S26. Calculate a second phase angle between the current and the voltage at the grid connection point after the new energy equipment is disconnected from the grid according to the system inductance, the system resistance, the third equivalent inductance and the third equivalent resistance.

[0193] Specifically, after the new energy equipment is disconnected from the grid, the second phase angle between the current and voltage at the grid connection point is

[0194] S27. Calculate the current integral constant according to the system voltage phase angle, the first phase angle, the second phase angle, the first steady-state current, and the second steady-state current.

[0195] Specifically, the current integration constant C is the DC attenuation constant in the grid-connected point current expression (described in detail below), where α is the system voltage phase angle.

[0196] In some embodiments, step S3, determining the transient voltage of the new energy device after being disconnected from the grid based on the relevant constant, includes steps S31 to S33, specifically including:

[0197] S31. Calculate a steady-state component of the voltage after the new energy equipment is disconnected from the grid according to the system inductance, the system resistance, the system voltage amplitude and the system voltage phase angle, the second steady-state current and the second phase angle.

[0198] Among them, the steady-state component of voltage after the new energy equipment is disconnected from the grid is U s1 The expression of (t)

[0199] S32. Calculate a DC voltage attenuation component after the new energy equipment is disconnected from the grid according to the voltage integral constant and the current attenuation time constant.

[0200] Among them, the voltage DC attenuation component expression is

[0201] S33. Calculate the transient voltage of the new energy equipment after it is disconnected from the grid according to the steady-state voltage component and the DC attenuation voltage component.

[0202] Among them, after the new energy equipment is disconnected from the grid, the grid connection point voltage expression is U s (t) = U s1 (t)+U s2 (t), U s1 (t) is the steady-state component of voltage, U s2 (t) is the voltage DC attenuation component.

[0203] In some embodiments, step S3, determining the transient current of the new energy device after disconnecting from the grid based on the relevant constant, and steps S34 to S36 specifically include:

[0204] S34. Calculate a steady-state component of the current after the new energy equipment is disconnected from the grid according to the system voltage phase angle, the second steady-state current and the second phase angle.

[0205] Among them, the steady-state component of the current after the new energy equipment is disconnected from the grid is I s1 The expression of (t) is:

[0206] S35. Calculate the DC attenuation component of the current after the new energy equipment is disconnected from the grid according to the current integral constant and the current attenuation time constant.

[0207] Among them, the DC attenuation component I s2 The expression of (t) is:

[0208] S36. Calculate the transient current of the new energy equipment after it is disconnected from the grid based on the steady-state voltage component and the DC attenuation component of the current.

[0209] Among them, the transient current I of the new energy equipment after disconnection from the grid s The expression of (t) is I s (t) = I s1 (t)+I s2 (t), I s1 (t) is the steady-state component of current, I s2 (t) is the DC decay component of the current.

[0210] In the embodiment of the present disclosure, according to the steady-state voltage and steady-state current of the new energy equipment and the branch equipment before and after the new energy equipment is disconnected from the grid, the relevant constants of the new energy equipment disconnecting from the grid can be calculated, and then according to the relevant constants, the transient voltage and transient current generated at the moment when the new energy equipment is disconnected from the grid can be accurately calculated, and the impact of overvoltage and overcurrent on the power grid system during the process of the new energy equipment disconnecting from the grid can be accurately evaluated theoretically. Specifically, the calculation method of transient overvoltage and overcurrent provided by the present disclosure, after obtaining data such as the system equivalent impedance, the system equivalent voltage amplitude and phase, the voltage and current characteristics of the new energy equipment and the branch equipment, etc., the corresponding data is brought into the corresponding expressions mentioned above in the present disclosure for calculation, and the relevant constants for calculating overvoltage and overcurrent when the new energy equipment is disconnected from the grid can be obtained. Further, the calculation expressions of overvoltage and overcurrent proposed in the present disclosure can be obtained by bringing in relevant constants and setting the grid connection time, that is, the formula equations for the relevant overvoltage and overcurrent can be obtained. The transient calculation method provided by the present disclosure is not affected by the operating state of the branch circuit equipment. Both the inductive and capacitive states of the power electronic equipment can participate in the calculation, and it is possible to analyze the impact caused by disconnection from the grid when multiple branch circuit equipment are in operation.

[0211] In order to further evaluate the impact of transient overvoltage and overcurrent, the present disclosure can also perform risk prediction on the impact of new energy equipment being disconnected from the grid by calculating relevant constants based on the system characteristic data, the first characteristic data and the second characteristic data.

[0212] Figure 4 A flowchart of another transient calculation method provided by an embodiment of the present disclosure. Figure 4 As shown, the method includes not only S1 to S3, but also S41 to S42, specifically including:

[0213] S41, calculating the system voltage phase angle α and the second phase angle The difference between the current integral constant C and the first phase difference is used as the first phase difference; and the risk of the new energy device being disconnected from the grid is predicted based on the current integral constant C and the first phase difference. That is, the present disclosure can also predict the risk of the new energy device being disconnected from the grid based on the related constants of the transient overcurrent.

[0214] In some embodiments, S41 specifically includes: if the current integral constant is greater than 0 and the first phase difference is -pi / 2, it is determined that the power grid system has a maximum transient overcurrent risk; if the current integral constant is less than 0 and the first phase difference is pi / 2, it is determined that the power grid system has a maximum transient overcurrent risk and the power grid system exhibits a current inversion feature. Wherein, pi is pi, which can also be written as π.

[0215] That is, when the current integral constant C>0, the first phase difference When C<0, the first phase difference At this time, the power grid system has the maximum transient overcurrent risk, and the power grid system presents the current reverse characteristic. When the above conditions are not met, the risk of transient overcurrent in the power grid system is relatively small.

[0216] S42, according to the system inductance L s With the system resistance R s , calculate the system impedance phase angle Right now Calculate the second phase angle The phase angle of the system impedance The difference between Based on the voltage integral constant M and the second phase difference The risk of the new energy equipment being disconnected from the grid is predicted. That is, the present disclosure can also predict the risk of the new energy equipment being disconnected from the grid based on the related constants of transient overvoltage.

[0217] In some embodiments, S42 specifically includes: if the range of the second phase difference is [pi / 3, 5*pi / 3], then the risk of transient overvoltage occurring in the power grid system is determined to be a first risk; if the range of the second phase difference is [0, pi / 3]∪[5*pi / 3, 2*pi], then the risk of transient overvoltage occurring in the power grid system is determined to be a second risk; if the range of the second phase difference is [2*pi, 7*pi / 3]∪[11*pi / 3, 4*pi], then the risk of transient overvoltage occurring in the power grid system is determined to be a third risk; if the range of the second phase difference is [7*pi / 3, 11*pi / 3], then the risk of transient overvoltage occurring in the power grid system is determined to be a fourth risk; wherein, the first risk is greater than the second risk; the second risk is greater than the third risk; the fourth risk is greater than the third risk.

[0218] In some embodiments, S42 specifically further includes: calculating a difference between the system voltage phase angle and one-half of the second phase difference, recorded as a third phase difference;

[0219] For the case where the voltage integral constant is greater than 0, if the second phase difference is pi and the third phase difference is pi, it is determined that the transient overvoltage of the power grid system reaches a peak value under the first risk; if the second phase difference is one-third of pi or one-third of five of pi, and the third phase difference is pi, it is determined that the transient overvoltage of the power grid system reaches a peak value under the second risk; if the second phase difference is seven-thirds of pi or eleven-thirds of pi, and the third phase difference is -pi, it is determined that the transient overvoltage of the power grid system reaches a peak value under the third risk; if the second phase difference is 3 times of pi and the third phase difference is -pi, it is determined that the transient overvoltage of the power grid system reaches a peak value under the fourth risk.

[0220] For the case where the voltage integral constant is less than 0, if the second phase difference is pi and the third phase difference is -pi, it is determined that the transient overvoltage of the power grid system reaches a peak value under the first risk; if the second phase difference is one-third of pi or one-third of five of pi, and the third phase difference is -pi, it is determined that the transient overvoltage of the power grid system reaches a peak value under the second risk; if the second phase difference is seven-thirds of pi or eleven-thirds of pi, and the third phase difference is pi, it is determined that the transient overvoltage of the power grid system reaches a peak value under the third risk; if the second phase difference is 3 times of pi and the third phase difference is pi, it is determined that the transient overvoltage of the power grid system reaches a peak value under the fourth risk.

[0221] In other words, if the voltage integral constant M>0, the second phase difference When the second phase difference is When M>0, the second phase difference When the second phase difference Or the second phase difference When M>0, the second phase difference The risk of transient overvoltage in the power grid system is reduced. Or the second phase difference When M>0, the second phase difference The risk of transient overvoltage in the power grid system increases. This is the peak value of the transient overvoltage in this case.

[0222] If M<0, the second phase difference When the second phase difference is When , this is the peak value of transient overvoltage in this case. If M<0, the second phase difference When the second phase difference Or the second phase difference When , this is the peak value of transient overvoltage in this case. If M<0, the second phase difference The risk of transient overvoltage in the power grid system is reduced. Or the second phase difference When M>0, the second phase difference The risk of transient overvoltage in the power grid system increases. This is the peak value of the transient overvoltage in this case.

[0223] The solution provided by the embodiment of the present disclosure can calculate the relevant constants of the new energy equipment off-grid according to the system characteristic data, the first characteristic data and the second characteristic data, including the current integral constant C, the voltage integral constant M, and the second phase angle System impedance phase angle According to the current integral constant C, voltage integral constant M, and the second phase angle after the new energy equipment is disconnected from the grid System impedance phase angle The impact of transient overvoltage and overcurrent during the off-grid process of new energy equipment can be evaluated without calculating the specific values ​​of transient overvoltage and overcurrent, which simplifies the process of evaluating the impact of off-grid of new energy equipment and improves the accuracy and efficiency of the evaluation. At the same time, the disclosed embodiment can also more comprehensively divide the conditions for generating overvoltage and overcurrent according to the characteristics of the grid-connected moment, and evaluate the degree of their impact, so that the impact of off-grid of new energy equipment can be evaluated more precisely and accurately.

[0224] On the second aspect, based on the same inventive concept, the disclosed embodiment also provides a transient computing device for off-grid new energy equipment.

[0225] Figure 5 A transient computing device for off-grid new energy equipment is provided in an embodiment of the present disclosure. Figure 6 Another transient computing device for off-grid new energy equipment provided by the embodiment of the present disclosure. Figure 5-6 As shown, the computing device 100 includes: an acquisition module 30 , a computing module 40 and a determination module 50 .

[0226] The acquisition module 30 is used to acquire system characteristic data of the power grid system, first characteristic data of the power grid system before the new energy device is disconnected from the grid, and second characteristic data of the power grid system after the new energy device is disconnected from the grid;

[0227] The calculation module 40 is used to calculate the relevant constants of the new energy equipment being off-grid according to the system characteristic data, the first characteristic data and the second characteristic data;

[0228] The determination module 50 is used to determine the transient voltage and / or transient current of the new energy equipment after it is disconnected from the grid based on the relevant constants.

[0229] In some embodiments, the system characteristic data includes the system inductance, system resistance, system voltage amplitude and system voltage phase angle of the power grid system; the first characteristic data includes the first voltage and the first current of the new energy device before the new energy device is disconnected from the grid, the second voltage and the second current of the branch device before the new energy device is disconnected from the grid; the second characteristic data includes the third voltage and the third current of the branch device after the new energy device is disconnected from the grid. In some embodiments, the related constants include the current decay time constant and the current integral constant after the new energy device is disconnected from the grid, and the calculation module 40 includes a first calculation module 41 and a second calculation module 42.

[0230] The first calculation module 41 is used to calculate the current decay time constant, wherein the first calculation module 41 is specifically used to perform the following steps:

[0231] According to the third voltage and the third current, the third equivalent resistance and the third equivalent inductance of the branch device after the new energy device is disconnected from the grid are calculated; according to the third equivalent resistance, the third equivalent inductance, the system resistance and the system inductance, the current decay time constant is calculated.

[0232] The second calculation module 42 is used to calculate the current integral constant, wherein the second calculation module 42 includes a first sub-calculation module 421 , a second sub-calculation module 422 and a third sub-calculation module 423 .

[0233] The first sub-calculation module 421 is used to calculate the first steady-state current of the grid-connected point before the new energy equipment is disconnected from the grid according to the system voltage amplitude, the system resistance, the first voltage, the first current, the second voltage and the second current.

[0234] The second sub-calculation module 422 is used to calculate the second steady-state current of the grid-connected point after the new energy equipment is disconnected from the grid according to the system voltage amplitude, the system resistance, the third voltage and the third current.

[0235] The third sub-computing module 423 is used to perform the following steps:

[0236] A first phase angle between the current and voltage at the grid-connected point before the new energy equipment is disconnected from the grid is calculated based on the system inductance, the system resistance, the first voltage, the first current, the second voltage, and the second current; a second phase angle between the current and voltage at the grid-connected point after the new energy equipment is disconnected from the grid is calculated based on the system inductance, the system resistance, the third equivalent inductance, and the third equivalent resistance; and the current integral constant is calculated based on the system voltage phase angle, the first phase angle, the second phase angle, the first steady-state current, and the second steady-state current.

[0237] In some embodiments, the related constants also include the voltage integral constant after the new energy equipment is disconnected from the grid. The calculation module 40 includes not only a first calculation module 41 and a second calculation module 42, but also a third calculation module 43. The third calculation module 43 is specifically used to calculate the voltage integral constant based on the system resistance, the system inductance, the current decay time constant and the current integral constant.

[0238] In some embodiments, when calculating the first steady-state current, the first sub-calculation module 421 is specifically used to calculate the first resistance and the first inductance of the new energy device before the new energy device is disconnected from the grid according to the first voltage and the first current; calculate the second resistance and the second inductance of the branch device before the new energy device is disconnected from the grid according to the second voltage and the second current; calculate the equivalent conductance and the equivalent susceptance of the new energy device and the branch device before the new energy device is disconnected from the grid according to the first resistance, the first inductance, the second resistance and the second inductance; calculate the equivalent resistance and the equivalent inductance of the new energy device and the branch device before the new energy device is disconnected from the grid based on the equivalent conductance and the equivalent susceptance of the new energy device and the branch device; calculate the first steady-state current according to the equivalent resistance and the equivalent inductance of the new energy device and the branch device before the new energy device is disconnected from the grid, as well as the system voltage amplitude, the system resistance, and the system inductance.

[0239] In some embodiments, when calculating the second steady-state current, the second sub-calculation module 422 is specifically used to calculate the third equivalent resistance and the third equivalent inductance of the branch device after the new energy device is disconnected from the grid based on the third voltage and the third current; and calculate the second steady-state current based on the system voltage amplitude, the system resistance, the system inductance, and the third equivalent resistance and the third equivalent inductance.

[0240] In some embodiments, the determination module 50 includes a voltage determination module 51, which is specifically used to calculate the steady-state component of the voltage after the new energy device is disconnected from the grid based on the system inductance, the system resistance, the system voltage amplitude and the system voltage phase angle, the second steady-state current and the second phase angle; calculate the DC attenuation component of the voltage after the new energy device is disconnected from the grid based on the voltage integral constant and the current decay time constant; and calculate the transient voltage after the new energy device is disconnected from the grid based on the steady-state voltage component and the DC voltage attenuation component.

[0241] In some embodiments, the determination module 50 includes a current determination module 52, which is specifically used to calculate the steady-state component of the current after the new energy device is disconnected from the grid based on the system voltage phase angle, the second steady-state current and the second phase angle; calculate the DC attenuation component of the current after the new energy device is disconnected from the grid based on the current integral constant and the current decay time constant; and calculate the transient current of the new energy device after it is disconnected from the grid based on the steady-state component of the current and the DC attenuation component of the current.

[0242] In some embodiments, the computing device 100 includes not only an acquisition module 30, a calculation module 40 and a determination module 50, but also a prediction module 60 for predicting the risk of the new energy equipment being disconnected from the grid.

[0243] In some embodiments, the prediction module 60 includes a current prediction module 62, which is specifically used to calculate the difference between the system voltage phase angle and the second phase angle as a first phase difference; and predict the risk of the new energy equipment being disconnected from the grid based on the current integral constant and the first phase difference.

[0244] Specifically, if the current prediction module 62 determines that the current integral constant is greater than 0 and the first phase difference is -pi / 2, it determines that the power grid system has a maximum transient overcurrent risk; if the current prediction module 62 determines that the current integral constant is less than 0 and the first phase difference is pi / 2, it determines that the power grid system has a maximum transient overcurrent risk and the power grid system exhibits a current reversal characteristic.

[0245] In some embodiments, the prediction module 60 includes a voltage prediction module 61, which is specifically used to calculate the system impedance phase angle based on the system inductance and the system resistance; calculate the difference between the second phase angle and the system impedance phase angle as the second phase difference; and predict the risk of the new energy equipment being disconnected from the grid based on the voltage integral constant and the second phase difference.

[0246] Specifically, if the voltage prediction module 61 determines that the range of the second phase difference is [pi / 3, 5*pi / 3], the risk of transient overvoltage in the power grid system is determined to be the first risk; if the range of the second phase difference is [0, pi / 3]∪[5*pi / 3, 2*pi], the risk of transient overvoltage in the power grid system is determined to be the second risk; if the range of the second phase difference is [2*pi, 7*pi / 3]∪[11*pi / 3, 4*pi], the risk of transient overvoltage in the power grid system is determined to be the third risk; if the range of the second phase difference is [7*pi / 3, 11*pi / 3], the risk of transient overvoltage in the power grid system is determined to be the fourth risk; wherein, the first risk is greater than the second risk; the second risk is greater than the third risk; the fourth risk is greater than the third risk.

[0247] In some embodiments, the voltage prediction module 61 is specifically used to calculate the difference between the system voltage phase angle and one-half of the second phase difference, recorded as the third phase difference; for the case where the voltage integral constant is greater than 0, if the voltage prediction module 61 determines that the second phase difference is pi, and the third phase difference is pi, it is determined that the transient overvoltage of the power grid system reaches a peak value under the first risk; if the voltage prediction module 61 determines that the second phase difference is one-third of pi or one-fifth of pi, and the third phase difference is pi, it is determined that the transient overvoltage of the power grid system reaches a peak value under the second risk; if the voltage prediction module 61 determines that the second phase difference is seven-thirds of pi or eleven-thirds of pi, and the third phase difference is -pi, it is determined that the transient overvoltage of the power grid system reaches a peak value under the third risk; if the voltage prediction module 61 determines that the second phase difference is 3 times of pi, and the third phase difference is -pi, it is determined that the transient overvoltage of the power grid system reaches a peak value under the fourth risk.

[0248] For the case where the voltage integral constant is less than 0, if the voltage prediction module 61 determines that the second phase difference is pi and the third phase difference is -pi, it is determined that the transient overvoltage of the power grid system reaches a peak value under the first risk; if the voltage prediction module 61 determines that the second phase difference is one-third of pi or one-third of five of pi, and the third phase difference is -pi, it is determined that the transient overvoltage of the power grid system reaches a peak value under the second risk; if the voltage prediction module 61 determines that the second phase difference is one-third of pi or one-eleventh of pi, and the third phase difference is pi, it is determined that the transient overvoltage of the power grid system reaches a peak value under the third risk; if the voltage prediction module 61 determines that the second phase difference is 3 times of pi, and the third phase difference is pi, it is determined that the transient overvoltage of the power grid system reaches a peak value under the fourth risk.

[0249] It can be understood that the specific details of the computing device provided in the embodiment of the present disclosure can refer to the specific details of the computing method embodiment of the first aspect mentioned above, and will not be repeated here.

[0250] The computing device provided in the embodiment of the present disclosure can calculate the relevant constants of the new energy equipment being disconnected from the grid based on the steady-state voltage and steady-state current of the new energy equipment and the branch equipment before and after the new energy equipment is disconnected from the grid, and then accurately calculate the transient voltage and transient current generated at the moment the new energy equipment is disconnected from the grid based on the relevant constants, and can theoretically accurately evaluate the impact of overvoltage and overcurrent on the power grid system during the process of the new energy equipment being disconnected from the grid.

[0251] At the same time, the calculation device provided in the embodiment of the present disclosure can also calculate the relevant constants of the new energy equipment off-grid according to the system characteristic data, the first characteristic data and the second characteristic data, including the current integral constant C, the voltage integral constant M, and the second phase angle System impedance phase angle According to the current integral constant C, voltage integral constant M, and second phase angle of the new energy equipment after it is disconnected from the grid System impedance phase angle The impact of transient overvoltage and overcurrent during the off-grid process of new energy equipment is evaluated without calculating the specific values ​​of transient overvoltage and overcurrent, which simplifies the process of evaluating the impact of off-grid operation of new energy equipment and improves the accuracy and efficiency of the evaluation. The disclosed embodiment can also more comprehensively divide the conditions for generating overvoltage and overcurrent according to the characteristics of the grid-connected moment, and evaluate the degree of their impact, so that the impact of off-grid operation of new energy equipment can be evaluated more precisely and accurately.

[0252] In a third aspect, an embodiment of the present disclosure further provides an electronic device, comprising a memory, a processor, and a computer program stored in the memory and executable on the processor, wherein when the processor executes the computer program, the method described in any one of the first aspects is implemented.

[0253] In a fourth aspect, an embodiment of the present disclosure further provides a computer-readable storage medium, wherein the computer-readable storage medium stores a computer program of the method described in any one of the first aspects above.

[0254] In a fifth aspect, an embodiment of the present disclosure further provides a computer program product, comprising a computer program / instructions, which, when executed by a processor, implement the steps of any one of the methods described in the first aspect above.

[0255] Those skilled in the art will appreciate that the embodiments of the present disclosure may be provided as methods, systems, or computer program products. Therefore, the present disclosure may take the form of a complete hardware embodiment, a complete software embodiment, or an embodiment combining software and hardware. Moreover, the present disclosure may take the form of a computer program product implemented on one or more computer-usable storage media (including but not limited to disk storage, CD-ROM, optical storage, etc.) containing computer-usable program code.

[0256] The present disclosure is described with reference to the flowcharts and / or block diagrams of the methods, devices (systems), and computer program products according to the embodiments of the present disclosure. It should be understood that each process and / or box in the flowchart and / or block diagram, as well as the combination of the processes and / or boxes in the flowchart and / or block diagram, can be implemented by computer program instructions. These computer program instructions can be provided to a processor of a general-purpose computer, a special-purpose computer, an embedded processor, or other programmable data processing device to generate a machine, so that the instructions executed by the processor of the computer or other programmable data processing device generate instructions for implementing the processes in the flowchart and / or block diagram. Figure 1 A process or multiple processes and / or boxes Figure 1 A device that provides the functions specified in a block or multiple blocks.

[0257] These computer program instructions may also be stored in a computer-readable memory capable of directing a computer or other programmable data processing device to operate in a specific manner, so that the instructions stored in the computer-readable memory produce an article of manufacture comprising an instruction device, which implements the process Figure 1 A process or multiple processes and / or boxes Figure 1 A function specified in one or more boxes.

[0258] These computer program instructions can also be loaded onto a computer or other programmable data processing device so that a series of operating steps are executed on the computer or other programmable device to produce a computer-implemented process, thereby providing instructions for implementing the process. Figure 1 A process or multiple processes and / or boxes Figure 1 The steps for the functions specified in one or more boxes.

[0259] The present disclosure uses specific embodiments to illustrate the principles and implementation methods of the present disclosure. The description of the above embodiments is only used to help understand the method of the present disclosure and its core idea. At the same time, for those skilled in the art, according to the idea of ​​the present disclosure, there will be changes in the specific implementation methods and application scope. In summary, the content of this specification should not be understood as a limitation on the present disclosure.

Claims

1. A transient calculation method for off-grid disconnection of new energy equipment, characterized in that: The method is applied to a power grid system, the power grid system includes a new energy device and at least one branch device, and the method includes: Acquire system characteristic data of the power grid system, first characteristic data of the power grid system before the new energy equipment is disconnected from the grid, and second characteristic data of the power grid system after the new energy equipment is disconnected from the grid; Calculating a related constant of the new energy device being disconnected from the grid according to the system characteristic data, the first characteristic data and the second characteristic data; The transient voltage and / or transient current of the new energy equipment after being disconnected from the grid is determined based on the relevant constants.

2. The method according to claim 1, characterized in that: The system characteristic data includes system inductance, system resistance, system voltage amplitude and system voltage phase angle of the power grid system; The first characteristic data includes a first voltage and a first current of the new energy device before the new energy device is disconnected from the grid, and a second voltage and a second current of the branch device before the new energy device is disconnected from the grid; The second characteristic data includes a third voltage and a third current of the branch device after the new energy device is disconnected from the grid.

3. The method according to claim 2, characterized in that The related constants include a current decay time constant and a current integral constant after the new energy device is disconnected from the grid; the related constants of the new energy device disconnecting from the grid are calculated according to the system characteristic data, the first characteristic data and the second characteristic data, specifically including: Calculating, according to the third voltage and the third current, a third equivalent resistance and a third equivalent inductance of the branch device after the new energy device is disconnected from the grid; Calculating the current decay time constant according to the third equivalent resistance, the third equivalent inductance, the system resistance, and the system inductance; Calculate a first steady-state current of the grid-connected point before the new energy equipment is disconnected from the grid according to the system voltage amplitude, the system resistance, the first voltage, the first current, the second voltage and the second current; Calculate the second steady-state current of the grid-connected point after the new energy equipment is disconnected from the grid according to the system voltage amplitude, the system resistance, the third voltage and the third current; Calculate a first phase angle between the current and the voltage at the grid connection point before the new energy equipment is disconnected from the grid according to the system inductance, the system resistance, the first voltage, the first current, the second voltage, and the second current; Calculating a second phase angle between the current and the voltage at the grid connection point after the new energy equipment is disconnected from the grid according to the system inductance, the system resistance, the third equivalent inductance and the third equivalent resistance; The current integral constant is calculated according to the system voltage phase angle, the first phase angle, the second phase angle, the first steady-state current, and the second steady-state current.

4. The method according to claim 3, characterized in that: The related constants also include a voltage integral constant after the new energy device is disconnected from the grid. The related constants of the new energy device disconnecting from the grid are calculated according to the system characteristic data, the first characteristic data and the second characteristic data, and specifically include: The voltage integral constant is calculated according to the system resistance, the system inductance, the current decay time constant and the current integral constant.

5. The method according to claim 3, characterized in that: The step of calculating the first steady-state current of the grid-connected point before the new energy equipment is disconnected from the grid according to the system voltage amplitude, the system resistance, the first voltage, the first current, the second voltage and the second current specifically includes: Calculating a first resistance and a first inductance of the new energy device before the new energy device is disconnected from the grid according to the first voltage and the first current; According to the second voltage and the second current, a second resistance and a second inductance of the branch device before the new energy device is disconnected from the grid are calculated; According to the first resistance, the first inductance, the second resistance and the second inductance, the equivalent conductance and the equivalent susceptance of the new energy equipment and the branch equipment before the new energy equipment is disconnected from the grid are calculated; Based on the equivalent conductance and equivalent susceptance of the new energy device and the branch device, the equivalent resistance and equivalent inductance of the new energy device and the branch device before the new energy device is disconnected from the grid are calculated; The first steady-state current is obtained by calculation based on the equivalent resistance and equivalent inductance of the new energy equipment and the branch equipment before the new energy equipment is disconnected from the grid, as well as the system voltage amplitude, the system resistance, and the system inductance.

6. The method according to claim 4, characterized in that The step of calculating the second steady-state current of the grid-connected point after the new energy equipment is disconnected from the grid according to the system voltage amplitude, the system resistance, the third voltage and the third current specifically includes: Calculating, according to the third voltage and the third current, a third equivalent resistance and a third equivalent inductance of the branch device after the new energy device is disconnected from the grid; The second steady-state current is calculated according to the system voltage amplitude, the system resistance, the system inductance, and the third equivalent resistance and the third equivalent inductance.

7. The method according to claim 6, characterized in that Determining the transient voltage of the new energy equipment after it is disconnected from the grid based on the relevant constants specifically includes: Calculating a voltage steady-state component after the new energy equipment is disconnected from the grid according to the system inductance, the system resistance, the system voltage amplitude and the system voltage phase angle, the second steady-state current and the second phase angle; Calculating a DC voltage attenuation component after the new energy equipment is disconnected from the grid according to the voltage integral constant and the current attenuation time constant; The transient voltage of the new energy equipment after being disconnected from the grid is calculated based on the voltage steady-state component and the voltage DC attenuation component.

8. The method according to claim 6, characterized in that Determining the transient current of the new energy equipment after it is disconnected from the grid based on the relevant constants specifically includes: Calculating a current steady-state component of the new energy device after it is disconnected from the grid according to the system voltage phase angle, the second steady-state current and the second phase angle; Calculating a DC attenuation component of the current after the new energy device is disconnected from the grid according to the current integral constant and the current attenuation time constant; The transient current of the new energy equipment after being disconnected from the grid is calculated based on the current steady-state component and the current DC attenuation component.

9. The method according to claim 4, characterized in that The method further comprises: Calculating the difference between the system voltage phase angle and the second phase angle as a first phase difference; and predicting the risk of the new energy device being disconnected from the grid based on the current integral constant and the first phase difference; or, Calculating a system impedance phase angle according to the system inductance and the system resistance; Calculating a difference between the second phase angle and the system impedance phase angle as a second phase difference; Based on the voltage integral constant and the second phase difference, the risk of the new energy equipment being off-grid is predicted.

10. The method according to claim 9, characterized in that The predicting the risk of the new energy equipment being off-grid based on the current integral constant and the first phase difference specifically includes: If the current integral constant is greater than 0 and the first phase difference is -pi / 2, it is determined that the power grid system has a maximum transient overcurrent risk; If the current integral constant is less than 0 and the first phase difference is pi / 2, it is determined that the power grid system has a maximum transient overcurrent risk and the power grid system exhibits a current inversion characteristic, where pi represents pi.

11. The method according to claim 9, characterized in that Predicting the risk of the new energy equipment being disconnected from the grid based on the voltage integral constant and the second phase difference specifically includes: If the range of the second phase difference is [pi / 3, 5*pi / 3], it is determined that the risk of transient overvoltage occurring in the power grid system is the first risk; If the range of the second phase difference is [0, pi / 3]∪[5*pi / 3, 2*pi], the risk of transient overvoltage occurring in the power grid system is determined to be the second risk; If the range of the second phase difference is [2*pi, 7*pi / 3]∪[11*pi / 3, 4*pi], it is determined that the risk of transient overvoltage in the power grid system is the third risk; If the range of the second phase difference is [7*pi / 3, 11*pi / 3], the risk of transient overvoltage in the power grid system is determined to be the fourth risk; wherein, The first risk is greater than the second risk; the second risk is greater than the third risk; the fourth risk is greater than the third risk, and pi represents pi.

12. The method according to claim 11, characterized in that Based on the voltage integral constant and the second phase difference, predicting the risk of the new energy equipment being disconnected from the grid specifically includes: Calculate the difference between the system voltage phase angle and half of the second phase difference, and record it as a third phase difference; For the case where the voltage integral constant is greater than 0, If the second phase difference is pi and the third phase difference is pi, it is determined that the transient overvoltage of the power grid system reaches a peak value under the first risk; or, If the second phase difference is one third of pi or one third of pi, and the third phase difference is pi, it is determined that the transient overvoltage of the power grid system reaches a peak value under the second risk; or, If the second phase difference is seven-thirds of pi or eleven-thirds of pi, and the third phase difference is -pi, it is determined that the transient overvoltage of the power grid system reaches a peak value under the third risk; or, If the second phase difference is 3 times pi, and the third phase difference is -pi, it is determined that the transient overvoltage of the power grid system reaches a peak value under the fourth risk; For the case where the voltage integral constant is less than 0, If the second phase difference is pi, and the third phase difference is -pi, it is determined that the transient overvoltage of the power grid system reaches a peak value under the first risk; or, If the second phase difference is one third of pi or one third of pi, and the third phase difference is -pi, it is determined that the transient overvoltage of the power grid system reaches a peak value under the second risk; or, If the second phase difference is seven-thirds of pi or eleven-thirds of pi, and the third phase difference is pi, it is determined that the transient overvoltage of the power grid system reaches a peak value under the third risk; or, If the second phase difference is 3 times of pi, and the third phase difference is pi, it is determined that the transient overvoltage of the power grid system reaches a peak value under the fourth risk.

13. A transient computing device for off-grid new energy equipment, characterized in that: The computing device is applied to a power grid system, the power grid system includes a new energy device and at least one branch device, and the device includes: An acquisition module, used to acquire system characteristic data of the power grid system, first characteristic data of the power grid system before the new energy device is disconnected from the grid, and second characteristic data of the power grid system after the new energy device is disconnected from the grid; A calculation module, used for calculating the relevant constant of the new energy equipment being off-grid according to the system characteristic data, the first characteristic data and the second characteristic data; A determination module is used to determine the transient voltage and / or transient current of the new energy equipment after it is disconnected from the grid based on the relevant constants.

14. The device according to claim 13, characterized in that The system characteristic data includes system inductance, system resistance, system voltage amplitude and system voltage phase angle of the power grid system; The first characteristic data includes a first voltage and a first current of the new energy device before the new energy device is disconnected from the grid, and a second voltage and a second current of the branch device before the new energy device is disconnected from the grid; The second characteristic data includes a third voltage and a third current of the branch device after the new energy device is disconnected from the grid.

15. The device according to claim 14, characterized in that The related constants include the current decay time constant and the current integral constant of the new energy equipment after being disconnected from the grid; the calculation module includes a first calculation module and a second calculation module, and the second calculation module includes a first sub-calculation module, a second sub-calculation module and a third sub-calculation module, wherein, The first computing module is used to perform the following steps: Calculating, according to the third voltage and the third current, a third equivalent resistance and a third equivalent inductance of the branch device after the new energy device is disconnected from the grid; Calculating the current decay time constant according to the third equivalent resistance, the third equivalent inductance, the system resistance, and the system inductance; The first sub-calculation module is used to calculate a first steady-state current of the grid connection point before the new energy equipment is disconnected from the grid according to the system voltage amplitude, the system resistance, the first voltage, the first current, the second voltage and the second current; The second sub-calculation module is used to calculate the second steady-state current of the grid-connected point after the new energy equipment is disconnected from the grid according to the system voltage amplitude, the system resistance, the third voltage and the third current; The third sub-computing module is used to perform the following steps: Calculate a first phase angle between the current and the voltage at the grid connection point before the new energy equipment is disconnected from the grid according to the system inductance, the system resistance, the first voltage, the first current, the second voltage, and the second current; Calculating a second phase angle between the current and the voltage at the grid connection point after the new energy equipment is disconnected from the grid according to the system inductance, the system resistance, the third equivalent inductance and the third equivalent resistance; The current integral constant is calculated according to the system voltage phase angle, the first phase angle, the second phase angle, the first steady-state current, and the second steady-state current.

16. The device according to claim 15, characterized in that The related constants also include the voltage integral constant of the new energy equipment after it is disconnected from the grid, and the calculation module also includes a third calculation module, wherein the third calculation module is used to perform the following steps: The voltage integral constant is calculated according to the system resistance, the system inductance, the current decay time constant and the current integral constant.

17. The device according to claim 15, characterized in that The first sub-computing module is specifically used to perform the following steps: Calculating a first resistance and a first inductance of the new energy device before the new energy device is disconnected from the grid according to the first voltage and the first current; According to the second voltage and the second current, a second resistance and a second inductance of the branch device before the new energy device is disconnected from the grid are calculated; According to the first resistance, the first inductance, the second resistance and the second inductance, the equivalent conductance and the equivalent susceptance of the new energy equipment and the branch equipment before the new energy equipment is disconnected from the grid are calculated; Based on the equivalent conductance and equivalent susceptance of the new energy device and the branch device, the equivalent resistance and equivalent inductance of the new energy device and the branch device before the new energy device is disconnected from the grid are calculated; The first steady-state current is obtained by calculation based on the equivalent resistance and equivalent inductance of the new energy equipment and the branch equipment before the new energy equipment is disconnected from the grid, as well as the system voltage amplitude, the system resistance, and the system inductance.

18. The device according to claim 16, characterized in that The second sub-computing module is specifically used to perform the following steps: Calculating, according to the third voltage and the third current, a third equivalent resistance and a third equivalent inductance of the branch device after the new energy device is disconnected from the grid; The second steady-state current is calculated according to the system voltage amplitude, the system resistance, the system inductance, and the third equivalent resistance and the third equivalent inductance.

19. The transient computing device according to claim 18, characterized in that: The determination module includes a voltage determination module, wherein the voltage determination module is used to perform the following steps: Calculating a voltage steady-state component after the new energy equipment is disconnected from the grid according to the system inductance, the system resistance, the system voltage amplitude and the system voltage phase angle, the second steady-state current and the second phase angle; Calculating a DC voltage attenuation component after the new energy equipment is disconnected from the grid according to the voltage integral constant and the current attenuation time constant; The transient voltage of the new energy equipment after being disconnected from the grid is calculated based on the voltage steady-state component and the voltage DC attenuation component.

20. The device according to claim 18, characterized in that The determination module includes a current determination module, wherein the current determination module is used to perform the following steps: Calculating a current steady-state component of the new energy device after it is disconnected from the grid according to the system voltage phase angle, the second steady-state current and the second phase angle; Calculating a DC attenuation component of the current after the new energy device is disconnected from the grid according to the current integral constant and the current attenuation time constant; The transient current of the new energy equipment after being disconnected from the grid is calculated based on the current steady-state component and the current DC attenuation component.

21. The device according to claim 16, characterized in that The transient calculation device further includes a prediction module, which includes a current prediction module and a voltage prediction module, wherein: The current prediction module is used to calculate the difference between the system voltage phase angle and the second phase angle as a first phase difference; and predict the risk of the new energy device being disconnected from the grid based on the current integral constant and the first phase difference; The voltage prediction module is used to calculate the system impedance phase angle according to the system inductance and the system resistance; calculate the difference between the second phase angle and the system impedance phase angle as the second phase difference; and predict the risk of the new energy equipment being disconnected from the grid based on the voltage integral constant and the second phase difference.

22. The device according to claim 21, characterized in that The current prediction module is specifically used to perform the following steps: If the current integral constant is greater than 0 and the first phase difference is -pi / 2, it is determined that the power grid system has a maximum transient overcurrent risk; If the current integral constant is less than 0 and the first phase difference is pi / 2, it is determined that the power grid system has a maximum transient overcurrent risk and the power grid system exhibits a current inversion characteristic, where pi represents pi.

23. The device according to claim 21, characterized in that The voltage prediction module is specifically used to perform the following steps: If the range of the second phase difference is [pi / 3, 5*pi / 3], it is determined that the risk of transient overvoltage occurring in the power grid system is the first risk; If the range of the second phase difference is [0, pi / 3]∪[5*pi / 3, 2*pi], the risk of transient overvoltage occurring in the power grid system is determined to be the second risk; If the range of the second phase difference is [2*pi, 7*pi / 3]∪[11*pi / 3, 4*pi], it is determined that the risk of transient overvoltage in the power grid system is the third risk; If the range of the second phase difference is [7*pi / 3, 11*pi / 3], the risk of transient overvoltage in the power grid system is determined to be the fourth risk; wherein, The first risk is greater than the second risk; the second risk is greater than the third risk; the fourth risk is greater than the third risk, and pi represents pi.

24. The device according to claim 23, characterized in that The voltage prediction module is further configured to perform the following steps: Calculate the difference between the system voltage phase angle and half of the second phase difference, and record it as a third phase difference; For the case where the voltage integral constant is greater than 0, If the second phase difference is pi and the third phase difference is pi, it is determined that the transient overvoltage of the power grid system reaches a peak value under the first risk; or, If the second phase difference is one third of pi or one third of pi, and the third phase difference is pi, it is determined that the transient overvoltage of the power grid system reaches a peak value under the second risk; or, If the second phase difference is seven-thirds of pi or eleven-thirds of pi, and the third phase difference is -pi, it is determined that the transient overvoltage of the power grid system reaches a peak value under the third risk; or, If the second phase difference is 3 times pi, and the third phase difference is -pi, it is determined that the transient overvoltage of the power grid system reaches a peak value under the fourth risk; For the case where the voltage integral constant is less than 0, If the second phase difference is pi, and the third phase difference is -pi, it is determined that the transient overvoltage of the power grid system reaches a peak value under the first risk; or, If the second phase difference is one third of pi or one third of pi, and the third phase difference is -pi, it is determined that the transient overvoltage of the power grid system reaches a peak value under the second risk; or, If the second phase difference is seven-thirds of pi or eleven-thirds of pi, and the third phase difference is pi, it is determined that the transient overvoltage of the power grid system reaches a peak value under the third risk; or, If the second phase difference is 3 times of pi, and the third phase difference is pi, it is determined that the transient overvoltage of the power grid system reaches a peak value under the fourth risk.

25. An electronic device comprising a memory, a processor, and a computer program stored in the memory and executable on the processor, characterized in that: When the processor executes the computer program, the method according to any one of claims 1 to 12 is implemented.

26. A computer-readable storage medium, characterized in that: The computer-readable storage medium stores a computer program for executing the method according to any one of claims 1 to 12.

27. A computer program product comprising a computer program / instructions, characterized in that When the computer program / instructions are executed by a processor, the steps of the method according to any one of claims 1 to 12 are implemented.

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