A protection method for a new energy AC transmission line

Abstract

The invention discloses a protection method for a new energy AC transmission line, and relates to the field of AC line protection. The method comprises: calculating the amplitude of a first negative sequence compensation voltage at a first measuring point and a second negative sequence compensation voltage at a second measuring point, and if the amplitude exceeds a preset first threshold value, calculating the amplitude ratio between the first negative sequence compensation voltage at the first measuring point and the second negative sequence compensation voltage at the second measuring point; comparing the amplitude ratio with a preset second threshold value to obtain a comparison result, obtaining a fault judgment result of the transmission line according to the comparison result, and protecting the transmission line in a preset manner; when performing corresponding calculations and comparisons based on the negative sequence compensation voltage, without using limited parameters such as current amplitude and current phase, and without using electrical parameters such as resistance, the method has higher sensitivity, can reliably identify the fault of the transmission line after the fault occurs, and effectively isolate the line fault.

Description

Technical Field

[0001] The present invention relates to the field of AC line protection, and more specifically, to a protection method for a new energy AC transmission line. Background Art

[0002] With the increasing consumption of fossil energy and environmental problems, the development and utilization of clean and renewable energy such as wind energy and solar energy are developing rapidly; new energy sites such as wind power and photovoltaics are connected to the traditional AC power grid on a large scale. Due to the uncertainty of clean energy such as wind energy and solar energy, new energy sites such as wind power and photovoltaics cannot be directly connected to the power grid, but need to be connected to the traditional AC power grid through the corresponding grid-connected circuit; among them, the grid-connected method of photovoltaic sites is to convert the electricity generated by photovoltaic cells into industrial frequency AC and inject it into the power grid through an inverter, and the grid-connected method of wind farms is to first use a rectifier to rectify the electricity generated by the wind farm into DC, and then use an inverter to convert the DC into industrial frequency AC and inject it into the power grid.

[0003] At present, current differential protection and distance protection are used to protect the transmission lines. Both current differential protection and distance protection can determine whether the fault occurs on the protected line. However, after the new energy station is connected to the traditional AC power grid via the transmission line, affected by the control strategy of the new energy station itself, after the AC transmission line fails, the fault electrical quantity shows new change characteristics, such as the fault current amplitude is limited and the phase is controlled on the new energy station side, showing weak feedback characteristics, and the harmonic content increases. Therefore, affected by factors such as the limited amplitude and phase control of the fault current on the new energy station side, the sensitivity of the current differential protection decreases, and even causes the current differential protection to refuse to operate. For distance protection, affected by the weak feedback characteristics of the fault current on the new energy station side, the distance protection's ability to resist transition resistance is greatly reduced. Summary of the invention

[0004] The purpose of the present invention is to provide a protection method for a new energy AC transmission line to solve the problems existing in the above-mentioned background technology.

[0005] The above technical objectives of the present invention are achieved through the following technical solutions:

[0006] In a first aspect, an embodiment of the present application provides a method for protecting a new energy AC transmission line, comprising the following steps:

[0007] Monitor the three-phase voltage of a preset first measuring point in the transmission line, and when the voltage change of one or more phases of the three-phase voltage at the first measuring point exceeds a preset range, obtain the three-phase voltage and three-phase current of the first measuring point, and calculate the first compensation voltage of each phase according to the three-phase voltage, current and voltage of the first measuring point;

[0008] The first negative sequence compensation voltage of the first measurement point is calculated by using the three corresponding first compensation voltages of the first measurement point;

[0009] Monitor the three-phase voltage of a preset second measuring point in the transmission line, and when the voltage change of one or more phases in the three-phase voltage of the second measuring point exceeds a preset range, obtain the three-phase voltage and current of the second measuring point, calculate the second compensation voltage of each phase according to the three-phase current and voltage of the second measuring point, and calculate the second negative sequence compensation voltage of the second measuring point using the three second compensation voltages of the three corresponding phases of the second measuring point, wherein the first measuring point and the second measuring point are respectively located on both sides of the transmission line;

[0010] Calculating the amplitude of a first negative sequence compensation voltage at a first measuring point and a second negative sequence compensation voltage at a second measuring point, and if the amplitude exceeds a preset first threshold value, calculating the amplitude ratio between the first negative sequence compensation voltage at the first measuring point and the second negative sequence compensation voltage at the second measuring point;

[0011] The amplitude ratio is compared with a preset second threshold value to obtain a comparison result, a fault judgment result of the transmission line is obtained according to the comparison result, and the transmission line is protected in a preset manner according to the fault judgment result. The fault judgment result includes an asymmetric fault and no fault.

[0012] The beneficial effects of the present invention are as follows: in this scheme, when the three-phase voltage of a preset first measuring point or a second measuring point in a transmission line changes and exceeds a preset range, relevant electrical parameters are calculated, and the first compensation voltage or the second compensation voltage of each phase can be obtained through the current and voltage of each phase in the three-phase electricity, and then the negative-sequence compensation voltage of the first measuring point or the second measuring point is calculated through the first compensation voltage or the second compensation voltage; at the same time, the negative-sequence compensation voltage of the measuring point at the other end of the transmission line is calculated in the same way, and the negative-sequence compensation voltages of the two measuring points are compared to obtain the amplitude, and when the amplitudes of the two exceed the first threshold value, the amplitude ratio of the two is obtained, and whether there is a fault is determined by the size of the amplitude ratio, and when an asymmetric fault occurs, corresponding methods or measures are taken to protect the transmission line, thereby achieving the purpose.

[0013] In this scheme, compared with the traditional current differential protection, when calculating various electrical parameters, limited parameters such as current amplitude and current phase are not used, but corresponding calculations and comparisons are performed based on the negative-sequence compensation voltage. Therefore, this protection method is not affected by the limited current amplitude and controlled current phase, and has higher sensitivity; at the same time, compared with the traditional distance protection, the corresponding calculations and comparisons based on the negative-sequence compensation voltage do not use electrical parameters such as resistance. Therefore, this method will not be affected by the transition resistance, and has more advantages in identifying the grounding fault of the new energy transmission line; after the AC transmission line fails, it is not affected by the new characteristics of the fault electrical quantity, and can reliably identify the fault of the transmission line after the fault occurs, and effectively isolate the line fault.

[0014] Based on the above technical solution, the present invention can also be improved as follows.

[0015] Furthermore, the first compensation voltage of each phase of the three phases at the first measurement point is obtained in the following manner:

[0016]

[0017] In the formula, represents the first compensation voltage of phase A at the first measuring point, represents the first compensation voltage of phase B at the first measurement point, represents the first compensation voltage of phase C at the first measurement point, Respectively represent the voltage values ​​of phase A, phase B, and phase C at the first measurement point, Respectively represent the current values ​​of phase A, phase B, and phase C at the first measurement point, Z set Indicates the preset impedance value, represents the zero-sequence current of the first measuring point, and k represents the zero-sequence current compensation coefficient.

[0018] Furthermore, the second compensation voltage of each of the three phases at the second measurement point is obtained in the following manner:

[0019]

[0020] In the formula, represents the second compensation voltage of phase A at the second measuring point, represents the second compensation voltage of phase B at the second measuring point, represents the second compensation voltage of phase C at the second measuring point, Respectively represent the voltage values ​​of phase A, phase B, and phase C at the second measurement point, Respectively represent the current values ​​of phase A, phase B, and phase C at the second measurement point, Z L Indicates the equivalent impedance value of the transmission line, Z set Indicates the preset impedance value, represents the zero-sequence current of the second measuring point, and k represents the zero-sequence current compensation coefficient.

[0021] Furthermore, the zero-sequence current at the first measuring point or the second measuring point is specifically:

[0022]

[0023] In the formula, represents the zero sequence current, Indicates the current values ​​of phase A, phase B, and phase C at the first measurement point or the second measurement point.

[0024] Furthermore, the zero-sequence current compensation coefficient is specifically:

[0025]

[0026] Wherein, k represents the zero-sequence current compensation coefficient, Z1 represents the positive-sequence impedance of the transmission line, and Z0 represents the zero-sequence impedance of the transmission line.

[0027] Furthermore, the first negative sequence compensation voltage at the first measurement point is specifically:

[0028] in,

[0029] In the formula, represents the first negative sequence compensation voltage at the first measurement point, represents the first compensation voltage of phase A at the first measuring point, represents the first compensation voltage of phase B at the first measurement point, Represents the first compensation voltage of phase C at the first measurement point.

[0030] Furthermore, the second negative sequence compensation voltage at the second measurement point is specifically:

[0031] in,

[0032] In the formula, represents the second negative sequence compensation voltage at the second measurement point, represents the second compensation voltage of phase A at the second measuring point, represents the second compensation voltage of phase B at the second measuring point, Represents the second compensation voltage of phase C at the second measurement point.

[0033] In a second aspect, an embodiment of the present application provides a protection system for a new energy AC transmission line, which is applied to a protection method for a new energy AC transmission line of any one of the first aspects, including:

[0034] A first calculation module is used to monitor the three-phase voltage of a preset first measurement point in the transmission line, and when the voltage change of one or more phases of the three-phase voltage at the first measurement point exceeds a preset range, the three-phase voltage and three-phase current of the first measurement point are obtained, and the first compensation voltage of each phase is calculated according to the three-phase current and voltage of the first measurement point;

[0035] A second calculation module, used for calculating a first negative sequence compensation voltage of the first measurement point by using three corresponding first compensation voltages of the first measurement point;

[0036] A third calculation module is used to monitor the three-phase voltage of a preset second measurement point in the transmission line, and when the voltage change of one or more phases of the three-phase voltage of the second measurement point exceeds a preset range, the three-phase voltage and three-phase current of the second measurement point are obtained, and the second compensation voltage of each phase is calculated according to the three-phase current and voltage of the second measurement point, and the second negative sequence compensation voltage of the second measurement point is calculated using the three corresponding second compensation voltages of the second measurement point, and the first measurement point and the second measurement point are respectively located on both sides of the transmission line;

[0037] a fourth calculation module, configured to calculate the amplitude of the first negative sequence compensation voltage at the first measurement point and the second negative sequence compensation voltage at the second measurement point, and if the amplitude exceeds a preset first threshold value, calculate the amplitude ratio between the first negative sequence compensation voltage at the first measurement point and the second negative sequence compensation voltage at the second measurement point;

[0038] The judgment protection module is used to compare the amplitude ratio with a preset second threshold value to obtain a comparison result, obtain a fault judgment result of the transmission line according to the comparison result, and protect the transmission line in a preset manner according to the fault judgment result. The fault judgment result includes whether an asymmetric fault occurs and whether no fault occurs.

[0039] In a third aspect, an embodiment of the present application provides an electronic device, including 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, a method for protecting a new energy AC transmission line according to any one of the first aspects is implemented.

[0040] In a fourth aspect, an embodiment of the present application provides a non-transitory computer-readable storage medium, which stores computer instructions, and the computer instructions enable a computer to execute a method for protecting a new energy AC transmission line according to any one of the first aspects.

[0041] Compared with the prior art, the present invention has at least the following beneficial effects:

[0042] In the present application, when the three-phase voltage of a preset first measuring point or a second measuring point in a transmission line changes and exceeds a preset range, relevant electrical parameters are calculated, and the first compensation voltage or the second compensation voltage of each phase can be obtained through the current and voltage of each phase in the three-phase electricity, and then the negative-sequence compensation voltage of the first measuring point or the second measuring point is calculated through the first compensation voltage or the second compensation voltage; at the same time, the negative-sequence compensation voltage of the measuring point at the other end of the transmission line is calculated in the same way, and the negative-sequence compensation voltage of the two measuring points is compared to obtain the amplitude, and when the amplitudes of the two exceed the first threshold value, the amplitude ratio of the two is obtained, and the size of the amplitude ratio is used to determine whether a fault exists, and when an asymmetric fault occurs, corresponding methods or measures are taken to protect the transmission line, thereby achieving the purpose.

[0043] In this application, compared with the traditional current differential protection, when calculating various electrical parameters, limited parameters such as current amplitude and current phase are not used. Therefore, this protection method is not affected by the limited current amplitude and the controlled current phase, and has higher sensitivity; and compared with the traditional distance protection, electrical parameters such as resistance are not used. Therefore, this method will not be affected by transition resistance, and has more advantages in identifying grounding faults in new energy transmission lines; after a fault occurs in the AC transmission line, it is not affected by the new characteristics of the fault electrical quantity, and can reliably identify the fault of the transmission line after the fault occurs, and effectively isolate the line fault. BRIEF DESCRIPTION OF THE DRAWINGS

[0044] The drawings described herein are used to provide a further understanding of the embodiments of the present invention, constitute a part of this application, and do not constitute a limitation of the embodiments of the present invention. In the drawings:

[0045] Figure 1 A method flow chart of a protection method in an embodiment of the present invention;

[0046] Figure 2 A schematic diagram of a sending line in an embodiment of the present invention;

[0047] Figure 3 A connection diagram of a protection system in an embodiment of the present invention;

[0048] Figure 4 Schematic diagram of the connection of electronic equipment in an embodiment of the present invention. DETAILED DESCRIPTION

[0049] In order to make the purpose, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Generally, the components of the embodiments of the present invention described and shown in the drawings here can be arranged and designed in various different configurations.

[0050] Therefore, the following detailed description of the embodiments of the present invention provided in the accompanying drawings is not intended to limit the scope of the invention claimed for protection, but merely represents selected embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0051] It should be noted that similar reference numerals and letters denote similar items in the following drawings, and therefore, once an item is defined in one drawing, further definition and explanation thereof is not required in subsequent drawings.

[0052] In the description of the embodiments of the present invention, "plurality" means at least 2.

[0053] Embodiment 1:

[0054] This embodiment provides a protection method for a new energy AC transmission line. Figure 1 As shown, the following steps are included:

[0055] S1, monitor the three-phase voltage of a preset first measuring point in the transmission line. When the voltage change of one or more phases of the three-phase voltage at the first measuring point exceeds a preset range, obtain the three-phase voltage and three-phase current of the first measuring point, and calculate the first compensation voltage of each phase according to the three-phase current and voltage of the first measuring point.

[0056] Among them, according to the monitoring of the three-phase voltage at the first measuring point, when the voltage change of one or several items of the three-phase voltage exceeds a preset range, the preset range can be 10% of the rated voltage. For example, when the voltage of one or several items drops to 90% of the rated voltage, the corresponding electrical parameters of the first measuring point are calculated, that is, the first compensation voltage of each phase of the first measuring point.

[0057] Specifically, the schematic diagram of the transmission line is shown in Figure 2 ,exist Figure 2 In the figure, M represents the first measurement point, N represents the second measurement point, and the outgoing line is MN, Z L Represents the equivalent impedance value between lines MN, which is a known quantity.

[0058] Optionally, the first compensation voltage of each of the three phases at the first measurement point is obtained in the following manner:

[0059]

[0060] In the formula, represents the first compensation voltage of phase A at the first measuring point, represents the first compensation voltage of phase B at the first measurement point, represents the first compensation voltage of phase C at the first measurement point, Respectively represent the voltage values ​​of phase A, phase B, and phase C at the first measurement point, Respectively represent the current values ​​of phase A, phase B, and phase C at the first measurement point, Z set Indicates the preset impedance value, represents the zero-sequence current of the first measuring point, and k represents the zero-sequence current compensation coefficient.

[0061] S2, obtaining a first negative-sequence compensation voltage of the first measuring point by calculation using three first compensation voltages corresponding to the first measuring point three.

[0062] Optionally, the first negative sequence compensation voltage at the first measurement point is specifically:

[0063] in,

[0064] In the formula, represents the first negative sequence compensation voltage at the first measurement point, represents the first compensation voltage of phase A at the first measuring point, represents the first compensation voltage of phase B at the first measurement point, Represents the first compensation voltage of phase C at the first measurement point.

[0065] S3, monitor the three-phase voltage of a preset second measuring point in the transmission line, when the voltage change of one or more phases in the three-phase voltage of the second measuring point exceeds a preset range, obtain the three-phase voltage and current of the preset second measuring point in the transmission line, calculate the second compensation voltage of each phase according to the three-phase current and voltage of the second measuring point, and calculate the second negative-sequence compensation voltage of the second measuring point using the three corresponding second compensation voltages of the second measuring point, the first measuring point and the second measuring point are respectively located on both sides of the transmission line.

[0066] Optionally, the second compensation voltage of each phase of the three phases at the second measurement point is obtained in the following manner:

[0067]

[0068] In the formula, represents the second compensation voltage of phase A at the second measuring point, represents the second compensation voltage of phase B at the second measuring point, represents the second compensation voltage of phase C at the second measuring point, Respectively represent the voltage values ​​of phase A, phase B, and phase C at the second measurement point, Respectively represent the current values ​​of phase A, phase B, and phase C at the second measurement point, Z L Indicates the equivalent impedance value of the transmission line, Z set Indicates the preset impedance value, represents the zero-sequence current of the second measuring point, and k represents the zero-sequence current compensation coefficient.

[0069] Among them, the above Z set is the preset impedance value, which can be set to Z L 80% of the zero-sequence current and the zero-sequence current compensation coefficient can be obtained in the following way.

[0070] Optionally, the zero-sequence current at the first measuring point or the second measuring point is specifically:

[0071]

[0072] In the formula, represents the zero sequence current, Indicates the current values ​​of phase A, phase B, and phase C in the three-phase voltage at the first measurement point or the second measurement point.

[0073] Optionally, the zero-sequence current compensation coefficient is specifically:

[0074]

[0075] Wherein, k represents the zero-sequence current compensation coefficient, Z1 represents the positive-sequence impedance of the transmission line, and Z0 represents the zero-sequence impedance of the transmission line.

[0076] Optionally, the second negative sequence compensation voltage at the second measurement point is specifically:

[0077] in,

[0078] In the formula, represents the second negative sequence compensation voltage at the second measurement point, represents the second compensation voltage of phase A at the second measuring point, represents the second compensation voltage of phase B at the second measuring point, Represents the second compensation voltage of phase C at the second measurement point.

[0079] The calculation method of each electrical parameter of the second measuring point is the same as that of the first measuring point. Then, the second negative sequence compensation voltage of the second measuring point can be obtained by the above method, that is, Figure 2 The second negative sequence compensation voltage at point N.

[0080] S4, calculating the amplitude of the first negative sequence compensation voltage at the first measuring point and the second negative sequence compensation voltage at the second measuring point, and if the amplitude exceeds a preset first threshold value, calculating the amplitude ratio between the first negative sequence compensation voltage at the first measuring point and the second negative sequence compensation voltage at the second measuring point.

[0081] Among them, according to the amplitude of the first negative-sequence compensation voltage at the first measuring point and the second negative-sequence compensation voltage at the second measuring point, if the amplitude is greater than the set threshold value, the next processing flow is entered; if it is less than the first threshold value, the process is terminated; specifically, the threshold value can be taken as 5% of the rated voltage.

[0082] Specifically, the amplitude ratio between the first negative sequence compensation voltage at the first measurement point and the second negative sequence compensation voltage at the second measurement point can be represented by K2, and the calculation formula thereof is as follows: is the first negative sequence compensation voltage at the first measurement point, is the second negative sequence compensation voltage at the second measurement point, such as Figure 2 As shown, the first measuring point is point M, and the second measuring point is point N, that is, the amplitude ratio is the ratio between the first negative sequence compensation voltage at point M and the second negative sequence compensation voltage at point N.

[0083] S5, comparing the amplitude ratio with a preset second threshold value to obtain a comparison result, obtaining a fault judgment result of the transmission line according to the comparison result, and protecting the transmission line in a preset manner according to the fault judgment result, wherein the fault judgment result includes an asymmetric fault and no fault.

[0084] Specifically, by comparing K2 with the set second threshold value, if it is greater than the second threshold value, it is determined that an asymmetric fault has occurred on the protected line, and corresponding methods or measures are taken to protect the transmission line for the asymmetric fault, thereby achieving the purpose; if it is less than the threshold value, it is determined that no fault has occurred on the protected line; among them, considering a certain reliability, the second threshold value can be set to 1.05.

[0085] Embodiment 2:

[0086] The embodiment of the present application provides a protection system for a new energy AC transmission line, which is applied to a protection method for a new energy AC transmission line in any one of the embodiments 1, such as Figure 3 As shown, including:

[0087] The first calculation module is used to monitor the three-phase voltage of a preset first measuring point in the transmission line. When the voltage change of one or more phases of the three-phase voltage at the first measuring point exceeds a preset range, the three-phase voltage and three-phase current of the first measuring point are obtained, and the first compensation voltage of each phase is calculated according to the three-phase current and voltage of the first measuring point.

[0088] The second calculation module is used to calculate the first negative sequence compensation voltage of the first measurement point by using the three first compensation voltages corresponding to the first measurement point three.

[0089] The third calculation module is used to monitor the three-phase voltage of a preset second measuring point in the transmission line. When the voltage change of one phase or more phases in the three-phase voltage of the second measuring point exceeds a preset range, the three-phase voltage and three-phase current of the preset second measuring point in the transmission line are obtained, and the second compensation voltage of each phase is calculated according to the three-phase current and voltage of the second measuring point, and the second negative-sequence compensation voltage of the second measuring point is calculated using the three second compensation voltages corresponding to the second measuring point. The first measuring point and the second measuring point are respectively located on both sides of the transmission line.

[0090] The fourth calculation module is used to calculate the amplitude of the first negative-sequence compensation voltage at the first measuring point and the second negative-sequence compensation voltage at the second measuring point. If the amplitude exceeds a preset first threshold value, the amplitude ratio between the first negative-sequence compensation voltage at the first measuring point and the second negative-sequence compensation voltage at the second measuring point is calculated.

[0091] The judgment protection module is used to compare the amplitude ratio with a preset second threshold value to obtain a comparison result, obtain a fault judgment result of the transmission line according to the comparison result, and protect the transmission line in a preset manner according to the fault judgment result. The fault judgment result includes whether an asymmetric fault occurs and whether no fault occurs.

[0092] Embodiment 3:

[0093] The present application embodiment provides an electronic device, such as Figure 4 As shown, it includes a memory, a processor, and a computer program stored in the memory and executable on the processor. When the processor executes the computer program, a protection method for a new energy AC transmission line of any one of the embodiments 1 is implemented.

[0094] Embodiment 4:

[0095] An embodiment of the present application provides a non-transitory computer-readable storage medium, which stores computer instructions. The computer instructions enable a computer to execute a method for protecting a new energy AC transmission line according to any one of the items in Example 1.

[0096] The specific implementation methods described above further illustrate the objectives, technical solutions and beneficial effects of the present invention in detail. It should be understood that the above description is only a specific implementation method of the present invention and is not intended to limit the scope of protection of the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. A protection method for a new energy AC transmission line, characterized in that: The following steps are involved: The three-phase voltage of a preset first measuring point in the transmission line is monitored. When the voltage change of one or more phases of the three-phase voltage at the first measuring point exceeds a preset range, the three-phase voltage and three-phase current of the first measuring point are obtained. According to the three-phase voltage and three-phase current of the first measuring point, the first compensation voltage of each phase is calculated respectively; the first compensation voltage of each phase of the first measuring point is specifically obtained in the following manner: In the formula, represents the first compensation voltage of phase A at the first measuring point, represents the first compensation voltage of phase B at the first measurement point, represents the first compensation voltage of phase C at the first measurement point, Respectively represent the voltage values ​​of phase A, phase B, and phase C at the first measurement point, Respectively represent the current values ​​of phase A, phase B, and phase C at the first measurement point, Z set Indicates the preset impedance value, represents the zero-sequence current of the first measuring point, k represents the zero-sequence current compensation coefficient; The first negative sequence compensation voltage at the first measuring point is calculated by using the three first compensation voltages corresponding to the three-phase voltage at the first measuring point; Monitor the three-phase voltage of a preset second measuring point in the transmission line, and when the voltage change of one or more phases in the three-phase voltage of the second measuring point exceeds a preset range, obtain the three-phase voltage and three-phase current of the second measuring point, calculate the second compensation voltage of each phase according to the three-phase voltage and three-phase current of the second measuring point, and calculate the second negative sequence compensation voltage of the second measuring point by using three second compensation voltages corresponding to the three-phase voltage of the second measuring point, the first measuring point and the second measuring point are respectively located on both sides of the transmission line; the second compensation voltage of each phase of the second measuring point is specifically obtained by the following method: In the formula, represents the second compensation voltage of phase A at the second measuring point, represents the second compensation voltage of phase B at the second measuring point, represents the second compensation voltage of phase C at the second measuring point, Respectively represent the voltage values ​​of phase A, phase B, and phase C at the second measurement point, Respectively represent the current values ​​of phase A, phase B, and phase C at the second measurement point, Z L Indicates the equivalent impedance value of the transmission line, Z set Indicates the preset impedance value, represents the zero-sequence current of the second measuring point, k represents the zero-sequence current compensation coefficient; the zero-sequence current of the first measuring point or the second measuring point is specifically: In the formula, represents the zero sequence current, Respectively represent the current values ​​of phase A, phase B, and phase C at the first measurement point or the second measurement point; the zero-sequence current compensation coefficient is specifically: In the formula, k represents the zero-sequence current compensation coefficient, Z1 represents the positive-sequence impedance of the transmission line, and Z0 represents the zero-sequence impedance of the transmission line; The amplitudes of the first negative sequence compensation voltage at the first measurement point and the second negative sequence compensation voltage at the second measurement point are calculated. If the amplitudes exceed a preset first threshold value, the amplitude ratio between the first negative sequence compensation voltage at the first measurement point and the second negative sequence compensation voltage at the second measurement point is calculated. The first negative sequence compensation voltage at the first measurement point is specifically: in, In the formula, represents the first negative sequence compensation voltage at the first measurement point, represents the first compensation voltage of phase A at the first measuring point, represents the first compensation voltage of phase B at the first measurement point, Indicates the first compensation voltage of phase C at the first measuring point; The second negative sequence compensation voltage at the second measurement point is specifically: in, In the formula, represents the second negative sequence compensation voltage at the second measurement point, represents the second compensation voltage of phase A at the second measuring point, represents the second compensation voltage of phase B at the second measuring point, Indicates the second compensation voltage of phase C at the second measuring point; The amplitude ratio is compared with a preset second threshold value to obtain a comparison result, a fault judgment result of the transmission line is obtained according to the comparison result, and the transmission line is protected in a preset manner according to the fault judgment result, and the fault judgment result includes an asymmetric fault and no fault.

2. A protection system for a new energy AC transmission line, applied to a protection method for a new energy AC transmission line as claimed in claim 1, characterized in that: include: A first calculation module is used to monitor the three-phase voltage of a preset first measurement point in the transmission line, and when the voltage change of one or more phases of the three-phase voltage at the first measurement point exceeds a preset range, obtain the three-phase voltage and three-phase current of the first measurement point, and calculate the first compensation voltage of each phase according to the three-phase current and voltage of the first measurement point; a second calculation module, configured to calculate a first negative-sequence compensation voltage at a first measurement point by using three corresponding first compensation voltages at the first measurement point; a third calculation module, for monitoring the three-phase voltage of a preset second measurement point in the transmission line, and when the voltage change of one or more phases of the three-phase voltage at the second measurement point exceeds a preset range, obtaining the three-phase voltage and three-phase current at the second measurement point, respectively calculating the second compensation voltage of each phase according to the three-phase current and voltage at the second measurement point, and calculating the second negative sequence compensation voltage of the second measurement point using the three corresponding second compensation voltages of the second measurement point, wherein the first measurement point and the second measurement point are respectively located on both sides of the transmission line; a fourth calculation module, configured to calculate the amplitude of the first negative sequence compensation voltage at the first measurement point and the second negative sequence compensation voltage at the second measurement point, and if the amplitude exceeds a preset first threshold value, calculate an amplitude ratio between the first negative sequence compensation voltage at the first measurement point and the second negative sequence compensation voltage at the second measurement point; A judgment protection module is used to compare the amplitude ratio with a preset second threshold value to obtain a comparison result, obtain a fault judgment result of the transmission line according to the comparison result, and protect the transmission line in a preset manner according to the fault judgment result, wherein the fault judgment result includes an asymmetric fault and no fault.

3. An electronic device, characterized in that: The invention comprises a memory, a processor and a computer program stored in the memory and executable on the processor. When the processor executes the computer program, a protection method for a new energy AC transmission line as claimed in claim 1 is implemented.

4. A non-transitory computer-readable storage medium, characterized in that: The non-transitory computer-readable storage medium stores computer instructions, and the computer instructions enable a computer to execute the protection method for a new energy AC transmission line as claimed in claim 1.

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