Analysis method for the influence of circuit breaker opening on the maximum value of PT current and related device

Abstract

The present application discloses an analysis method and related device for the influence of breaker opening on the maximum value of PT current, including: obtaining a plurality of electrical parameters of the power grid system to be analyzed; theoretically analyzing the current relationship at each end of the primary side of the PT according to the ground fault and protection action in the electrical parameters to obtain the first variation law of the current peak value at each end of the primary side of the PT with the breaker opening time; establishing a simulation analysis model of the primary side current of the PT, and simulating and calculating the primary side current of the PT when the breaker opens at different moments in a cycle to obtain the second variation law of the primary side current peak value of the PT with the breaker opening moment; mutually verifying the first variation law and the second variation law to construct the variation law of the primary side current peak value of the PT with the breaker opening moment. Thus, it is possible to efficiently and accurately analyze and verify the variation law of the primary side current peak value of the PT with the breaker opening moment and the breaker opening moment corresponding to the current extreme value.

Description

Technical Field

[0001] This application relates to the field of power technology, and in particular, to an analysis method for the influence of breaker opening on the maximum value of PT current and related devices. Background Art

[0002] A PT (electromagnetic voltage transformer) is a high-voltage device that converts high-voltage electricity in the power grid into low-voltage electricity for easy monitoring and measurement of voltage. Its primary winding is directly connected in parallel to the primary circuit. In a cable distribution network, when the protection of the distribution network fails, the isolated system composed of the PT and the branch line of the cable will have a low-frequency oscillation. During the low-frequency oscillation process, a large current flows through the primary side of the PT, resulting in frequent fuses blowing on the high-voltage side of the PT, which poses a threat to the safe and stable operation of the distribution network. During the low-frequency oscillation process, the breaker opening time has a great influence on the current on the primary side of the PT. In actual situations, the breaker opening time is uncontrollable. Therefore, when calculating and analyzing the current on the primary side of the PT, it is necessary to find out the variation law of the current on the primary side of the PT with different breaker opening times, and in particular, it is very necessary to find out the extreme points of the current on the primary side of the PT.

[0003] Currently, there is no literature studying the influence of the breaker opening time on the current on the primary side of the PT during low-frequency oscillation. Therefore, there is an urgent need for an efficient and accurate simulation analysis method to analyze and verify the variation law of the peak value of the current on the primary side of the PT with the breaker opening time and the breaker opening time corresponding to the extreme value of the peak value of the current on the primary side of the PT. Summary of the Invention

[0004] This application provides an analysis method for the influence of breaker opening on the maximum value of PT current and related devices, enabling efficient and accurate analysis and verification of the variation law of the peak value of the current on the primary side of the PT with the breaker opening time and the breaker opening time corresponding to the extreme value of the peak value of the current on the primary side of the PT.

[0005] In view of this, in the first aspect of this application, an analysis method for the influence of breaker opening on the maximum value of PT current is provided. The method includes:

[0006] Obtain a number of electrical parameters of the power grid system to be analyzed, and the number of the electrical parameters includes: PT wiring type, ground fault, and corresponding protection actions;

[0007] Theoretically analyze the current relationship at each end of the primary side of the PT according to the ground fault and the corresponding protection actions in the electrical parameters, and obtain the first variation law of the peak value of the current at each end of the primary side of the PT with the breaker opening time;

[0008] Establish a simulation analysis model of the primary side current of the PT, calculate the primary side current of the PT when the circuit breaker is opened at different moments within one cycle through the simulation analysis model, and obtain the second variation law of the peak value of the primary side current of the PT with the opening moment of the circuit breaker;

[0009] Mutually verify the first variation law and the second variation law, and construct the variation law of the peak value of the primary side current of the PT with the opening moment of the circuit breaker.

[0010] Optionally, several of the electrical parameters specifically include:

[0011] Power grid structure, line parameters, transformer parameters, PT wiring type, PT excitation characteristics, equivalent power source, equivalent load, ground fault and corresponding protection actions.

[0012] Optionally, the establishment of the simulation analysis model of the primary side current of the PT specifically includes:

[0013] Based on electromagnetic transient simulation software, establish a simulation analysis model of the primary side current of the PT according to several of the electrical parameters.

[0014] Optionally, the calculation of the primary side current of the PT when the circuit breaker is opened at different moments within one cycle through the simulation analysis model specifically includes:

[0015] Obtain an empirical value of the opening time of the circuit breaker according to the ground fault and the corresponding protection action;

[0016] Adopt a time control method, set the opening time of the circuit breaker to vary at equal intervals within one cycle after the empirical value, and simulate and calculate the peak value of the primary side current of the PT at different opening moments of different circuit breakers.

[0017] Optionally, after obtaining the first variation law of the peak current at each end of the primary side of the PT with the opening time of the circuit breaker, it further includes:

[0018] Analyze based on the first variation law to obtain the first opening moment of the circuit breaker corresponding to the maximum value of the primary side current of the PT.

[0019] Optionally, after constructing the variation law of the peak value of the primary side current of the PT with the opening moment of the circuit breaker, it further includes:

[0020] Obtain the opening moment of the circuit breaker corresponding to the maximum value of the primary side current of the PT according to the first opening moment.

[0021] The second aspect of the present application provides an analysis of the influence of circuit breaker opening on the maximum value of PT current. The system includes:

[0022] An acquisition unit, configured to acquire a plurality of electrical parameters of the power grid system to be analyzed, and the plurality of electrical parameters include: PT connection type, ground fault, and corresponding protection actions;

[0023] A theoretical analysis unit, configured to perform theoretical analysis on the current relationship at each end of the primary side of the PT according to the ground fault and the corresponding protection actions in the electrical parameters, and obtain the first variation law of the current peak value at each end of the primary side of the PT with the breaker opening time;

[0024] A simulation analysis unit, configured to establish a simulation analysis model of the current on the primary side of the PT, calculate the current on the primary side of the PT when the breaker opens at different moments within one cycle through the simulation analysis model, and obtain the second variation law of the current peak value on the primary side of the PT with the breaker opening moment;

[0025] A construction unit, configured to mutually verify the first variation law and the second variation law, and construct the variation law of the current peak value on the primary side of the PT with the breaker opening moment.

[0026] Optionally, the simulation analysis unit is specifically configured to:

[0027] Based on electromagnetic transient simulation software, establish a simulation analysis model of the current on the primary side of the PT according to the plurality of electrical parameters;

[0028] According to the ground fault and the corresponding protection actions, obtain an empirical value of the breaker opening time;

[0029] Adopt a time control method to set the breaker opening time to vary at equal intervals within one cycle after the empirical value, and simulate and calculate the current peak value on the primary side of the PT at different opening moments of different breakers, and obtain the second variation law of the current peak value on the primary side of the PT with the breaker opening moment.

[0030] A third aspect of the present application provides an analysis device for the influence of breaker opening on the maximum value of PT current, and the device includes a processor and a memory:

[0031] The memory is configured to store program codes and transmit the program codes to the processor;

[0032] The processor is configured to execute the steps of the analysis method for the influence of breaker opening on the maximum value of PT current as described in the first aspect above according to the instructions in the program codes.

[0033] A fourth aspect of the present application provides a computer-readable storage medium, and the computer-readable storage medium is configured to store program codes, and the program codes are used to execute the analysis method for the influence of breaker opening on the maximum value of PT current as described in the first aspect above.

[0034] As can be seen from the above technical solutions, the present application has the following advantages:

[0035] The present application provides an analysis method for the influence of breaker opening on the maximum value of PT current, including: obtaining several electrical parameters of the power grid system to be analyzed; theoretically analyzing the current relationship at each end of the primary side of the PT according to the ground fault and the corresponding protection action in the electrical parameters, and obtaining the first variation law of the current peak value at each end of the primary side of the PT with the breaker opening time; establishing a simulation analysis model of the primary side current of the PT, calculating the primary side current of the PT when the breaker opens at different moments in a cycle through the simulation analysis model, and obtaining the second variation law of the primary side current peak value of the PT with the breaker opening moment; mutually verifying the first variation law and the second variation law, and constructing the variation law of the primary side current peak value of the PT with the breaker opening moment.

[0036] The present application considers the wiring type of the PT, different fault forms, and the protection strategy of the system, and proposes an analysis method for the variation law of the primary side current peak value of the PT in the isolated system with respect to the breaker opening moment and the breaker opening moment corresponding to the extreme value of the primary side current peak value of the PT after the protection action occurs when a fault occurs in the distribution network. It provides a reference for the calculation and analysis of the primary side current of the PT when low-frequency oscillation occurs in the PT of the isolated system in the distribution network, so that the variation law of the primary side current peak value of the PT with respect to the breaker opening moment and the breaker opening moment corresponding to the extreme value of the primary side current peak value of the PT can be analyzed and verified efficiently and accurately. BRIEF DESCRIPTION OF THE DRAWINGS

[0037] Figure 1 It is a schematic flowchart of an embodiment of an analysis method for the influence of breaker opening on the maximum value of PT current provided in an embodiment of the present application;

[0038] Figure 2 It is a schematic structural diagram of an embodiment of an analysis system for the influence of breaker opening on the maximum value of PT current provided in an embodiment of the present application;

[0039] Figure 3 It is a schematic diagram of the primary side of the PT with VV wiring type and its current reference direction;

[0040] Figure 4 It is a schematic diagram of the voltage phasor relationship of the PT coil (with the system A-phase-to-ground voltage as the reference);

[0041] Figure 5 It is a simplified schematic diagram of the simulation model;

[0042] Figure 6 It is a schematic diagram of the change of the primary side current peak value of the PT when the breaker opens at different moments;

[0043] Figure 7It is a schematic diagram of the voltage of the primary side coil of the PT. Specific implementation manners

[0044] To enable those skilled in the art to better understand the solution of this application, the following will clearly and completely describe the technical solutions in the embodiments of this application with reference to the accompanying drawings in the embodiments of this application. Obviously, the described embodiments are only a part of the embodiments of this application, rather than all the embodiments. Based on the embodiments in this application, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the scope of protection of this application.

[0045] Please refer to Figure 1 , an analysis method for the influence of the opening of a circuit breaker on the maximum value of the PT current provided in the embodiments of this application includes:

[0046] Step 101: Obtain several electrical parameters of the power grid system to be analyzed. The several electrical parameters include: PT wiring type, ground fault, and corresponding protection actions;

[0047] It should be noted that in addition to the PT wiring type, ground fault, and corresponding protection actions, the electrical parameters in this embodiment also include: power grid structure, line parameters, transformer parameters, PT excitation characteristics, equivalent power source, and equivalent load.

[0048] In this embodiment, the 20 kV distribution network in Hengqin New Area is taken as an example; it is determined that the 20 kV distribution network in Hengqin New Area is a double-chain ring structure, all using cable outlets, the model parameters of the cables are determined, and the parameters of the main transformer and distribution transformers are determined; it is determined that the connected PT is in the VV wiring type, as Figure 3 shown, its actual excitation characteristics are determined; the high-voltage side of the main transformer at 220 kV is equivalent, the voltage source amplitude is 220 kV, the equivalent inductance is 0.01016 H, and the load of each distribution transformer is 500 kVA; it is determined that the fault is a single-phase ground fault of phase A, and it is determined that when the protection action occurs, the switches at both sides of the fault switch station are disconnected, and the empirical value of the switch action time is 120 ms after the fault occurs.

[0049] Step 102: Theoretically analyze the current relationship at each end of the primary side of the PT according to the ground fault and the corresponding protection action, and obtain the first variation law of the current peak value at each end of the primary side of the PT with the opening time of the circuit breaker;

[0050] It should be noted that according to the ground fault and the corresponding protection action in step 101, the relationship of the current at each end of the primary side of the PT is analyzed, and the relationship between the PT coil voltage and the system phase A voltage is as Figure 4 shown. Since the current peak value on the primary side of the PT is positively correlated with the PT coil voltage value at the opening moment, the change trend of the maximum value of the PT primary side current with the circuit breaker opening time can be inferred as shown in Table 1.

[0051] Table 1 Relationship between Peak Current and Phase Interval of Phase A Voltage during Circuit Breaker Opening

[0052]

[0053]

[0054] As can be seen from Table 1, when the currents of the two coils have the same sign, the maximum value of the current will appear at the common terminal. There exists such a moment when the voltage values of the PT coils are relatively large and of the same polarity during opening at this moment. The maximum peak value of the current appears at the common terminal at this moment, and this value is larger than the maximum peak values of both Coil 1 and Coil 2. Assuming that the voltage values of the two coils are not much different at the opening moment and the peak currents of the two coils approximately appear at the same moment after opening, it can be known that when the sum of the instantaneous values of the voltages UAB and UAC is the largest at the opening moment, the current at the common terminal will also reach the maximum value. From the phasor diagram, it can be seen that this voltage is in the same phase as the phase A voltage. Therefore, when the circuit breaker is opened at the phase A phase of ±90°, the peak current will reach the maximum, and this peak value appears at the common terminal. Through the above theoretical analysis, the first variation law of the peak current at each end of the primary side of the PT with the opening time of the circuit breaker is obtained.

[0055] Step 103: Establish a simulation analysis model for the current on the primary side of the PT, and calculate the current on the primary side of the PT when the circuit breaker is opened at different moments within one cycle through the simulation analysis model, so as to obtain the second variation law of the peak current on the primary side of the PT with the opening moment of the circuit breaker;

[0056] It should be noted that in this embodiment, the modeling is carried out starting from the 220 kV node, the main transformer turns ratio is 220 / 20 kV, and the double-loop structure of the faulty line is built according to the grid structure as Figure 5 shown. The remaining outgoing lines of the 20 kV bus are simplified as cable lines, distribution transformers and loads. The circuit breaker adopts a time control method, and the equivalent power source, line, circuit breaker, distribution transformer and load are input according to the analysis results in Step 101.

[0057] Based on the established simulation model, the peak current on the primary side of the PT when the circuit breaker is opened at different times is simulated and calculated. Specifically:

[0058] The opening time of the circuit breaker is changed within one cycle after the empirical value, and the peak current on the primary side of the PT at different opening moments of the circuit breaker is simulated and calculated to obtain the variation law of the peak current on the primary side of the PT with the opening moment of the circuit breaker, and the theoretically deduced law is verified.

[0059] In this example, it is set that a single-phase ground fault of phase A occurs at point F4 at 0.1 s, and the opening time of the circuit breaker is changed within the time range of 120 - 140 ms after the fault, with a change interval of 2 ms.

[0060] The peak value of the primary side current of PT7 corresponding to the opening moment of the circuit breaker obtained by simulation is as Figure 6 shown, and the coil voltage of PT7 corresponding to the opening moment of the circuit breaker is as Figure 6 shown.

[0061] Perform quantitative analysis on the scanned points, specifically:

[0062] ① At the moment of 0.2216s: The phase φuA of phase A of the system voltage is 0°, and the phases φuAB and φuAC of the primary side coil voltage of PT are 30° and -30° respectively. At the opening moment of the circuit breaker, the polarities of the primary side coil voltages of PT are opposite, and the coil currents are of the same polarity. Therefore, when the circuit breaker opens at this moment, the maximum value of the current is not at the common terminal but in the two coils;

[0063] ② At the moment of 0.2236s: The phase φuA of phase A of the system voltage is 36°, and the phases φuAB and φuAC of the primary side coil voltage of PT are 66° and 6° respectively. At the opening moment of the circuit breaker, the polarities of the primary side coil voltages of PT are the same, and the coil currents are of the same positive and negative. Therefore, when the circuit breaker opens at this moment, the maximum value of the current is at the common terminal. Among them, the phase of coil 2 is very close to 0°, and the voltage value of coil 2 at the opening moment is very small, so the current of coil 2 is correspondingly very small;

[0064] ② At the moment of 0.2256s: The phase φuA of phase A of the system voltage is 72°, and the phases φuAB and φuAC of the primary side coil voltage of PT are 102° and 42° respectively. At the opening moment of the circuit breaker, the polarities of the primary side coil voltages of PT are the same, and the coil currents are of the same positive and negative. Therefore, when the circuit breaker opens at this moment, the maximum value of the current is at the common terminal;

[0065] ② At the moment of 0.2276s: The phase φuA of phase A of the system voltage is 108°, and the phases φuAB and φuAC of the primary side coil voltage of PT are 138° and 78° respectively. At the opening moment of the circuit breaker, the polarities of the primary side coil voltages of PT are the same, and the coil currents are of the same positive and negative. Therefore, when the circuit breaker opens at this moment, the maximum value of the current is at the common terminal;

[0066] ② At the moment of 0.2296s: The phase φuA of phase A of the system voltage is 144°, and the phases φuAB and φuAC of the primary side coil voltage of PT are 174° and 114° respectively. At the opening moment of the circuit breaker, the polarities of the primary side coil voltages of PT are the same, and the coil currents are of the same positive and negative. Therefore, when the circuit breaker opens at this moment, the maximum value of the current is at the common terminal; The analysis from 0.2316s to 0.2416s is the same.

[0067] The above quantitative analysis verifies the relationship between the peak value of the primary side current of the PT and the opening moment of the circuit breaker (PT coil voltage), that is, there is a positive correlation between the peak value of the primary side current of the PT and the PT coil voltage; from Figure 7 it can be deduced the variation law of the peak value of the primary side current of the PT with the opening moment of the circuit breaker, that is, the second variation law of the peak value of the primary side current of the PT with the opening moment of the circuit breaker is obtained.

[0068] Step 104: Mutually verify the first variation law and the second variation law to construct the variation law of the peak value of the primary side current of the PT with the opening moment of the circuit breaker.

[0069] It should be noted that, as can be seen from the simulation results of step 103, the peak value of the primary side current of the PT approximately varies periodically with the opening moment of the circuit breaker, and its period is half of the power frequency period. From the theoretical analysis in step 102, this is because the variation period of the amplitude of the primary side voltage of the PT is half of the power frequency period. For the PT with V_V connection, when its common terminal is connected to phase A and a fault occurs in phase A, the influence of the circuit breaker opening moment on the primary side current of the PT is shown in Table 1. There is an extreme value grounding or the circuit breaker opening time is approximately when the phase angle of the system phase A voltage is ±90°. Therefore, by constructing the variation law of the peak value of the primary side current of the PT with the opening moment of the circuit breaker, the opening moment of the circuit breaker corresponding to the maximum value of the primary side current of the PT can also be obtained.

[0070] The above is an analysis method for the influence of circuit breaker opening on the maximum value of PT current provided in the embodiments of the present application, and the above is an analysis system for the influence of circuit breaker opening on the maximum value of PT current provided in the embodiments of the present application.

[0071] Please refer to Figure 2 , an analysis system for the influence of circuit breaker opening on the maximum value of PT current provided in the embodiments of the present application, includes:

[0072] An acquisition unit 201, configured to acquire a plurality of electrical parameters of the power grid system to be analyzed, and the plurality of electrical parameters include: PT wiring type, grounding fault, and corresponding protection actions;

[0073] A theoretical analysis unit 202, configured to perform theoretical analysis on the current relationship of each end of the primary side of the PT according to the grounding fault and the corresponding protection action in the electrical parameters, and obtain the first variation law of the peak value of the current of each end of the primary side of the PT with the circuit breaker opening time;

[0074] A simulation analysis unit 203, configured to establish a simulation analysis model of the primary side current of the PT, calculate the primary side current of the PT when the circuit breaker opens at different moments in a cycle through the simulation analysis model, and obtain the second variation law of the peak value of the primary side current of the PT with the opening moment of the circuit breaker;

[0075] The building block 204 is used to mutually verify the first change law and the second change law, and construct the change law of the PT primary side current peak value with respect to the breaker opening time.

[0076] Furthermore, in the embodiments of the present application, an analysis device for the influence of breaker opening on the maximum value of PT current is also provided. The device includes a processor and a memory:

[0077] The memory is used to store program code and transmit the program code to the processor;

[0078] The processor is used to execute the analysis method for the influence of breaker opening on the maximum value of PT current described in the above method embodiments according to the instructions in the program code.

[0079] Furthermore, in the embodiments of the present application, a computer-readable storage medium is also provided. The computer-readable storage medium is used to store program code, and the program code is used to execute the analysis method for the influence of breaker opening on the maximum value of PT current described in the above method embodiments.

[0080] Those skilled in the art can clearly understand that for the convenience and simplicity of description, the specific working processes of the above-described systems and units can refer to the corresponding processes in the foregoing method embodiments and will not be elaborated herein.

[0081] The terms "first", "second", "third", "fourth", etc. in the specification of the present application and the above-mentioned drawings are used to distinguish similar objects and do not necessarily need to be used to describe a specific order or sequence. It should be understood that such used data can be interchanged under appropriate circumstances so that the embodiments of the present application described herein can be implemented in an order other than those illustrated or described herein. In addition, the terms "including" and "having" and any variations thereof are intended to cover non-exclusive inclusion. For example, a process, method, system, product or device that includes a series of steps or units does not necessarily need to be limited to those steps or units clearly listed, but may include other steps or units not clearly listed or inherent to these processes, methods, products or devices.

[0082] It should be understood that in this application, "at least one (item)" means one or more, and "a plurality" means two or more. "And / or" is used to describe the relationship between associated objects and indicates that there can be three relationships. For example, "A and / or B" can mean: only A exists, only B exists, and both A and B exist simultaneously. Here, A and B can be singular or plural. The character " / " generally indicates an "or" relationship between the associated objects before and after. "At least one (item) of the following" or similar expressions refer to any combination of these items, including any combination of single items or plural items. For example, at least one (item) of a, b, or c can mean: a, b, c, "a and b", "a and c", "b and c", or "a and b and c", where a, b, and c can be single or multiple.

[0083] In several embodiments provided in this application, it should be understood that the disclosed systems, devices, and methods can be implemented in other ways. For example, the device embodiments described above are merely illustrative. For example, the division of the units is only a logical function division, and there can be other division methods in actual implementation. For example, multiple units or components can be combined or integrated into another system, or some features can be ignored or not executed. Another point is that the displayed or discussed couplings or direct couplings or communication connections to each other can be through some interfaces, and the indirect couplings or communication connections of devices or units can be in electrical, mechanical, or other forms.

[0084] The units described as separate components may or may not be physically separated, and the components displayed as units may or may not be physical units, that is, they can be located in one place or distributed to multiple network units. Some or all of the units can be selected according to actual needs to achieve the purpose of the solution of this embodiment.

[0085] In addition, the functional units in each embodiment of this application can be integrated into one processing unit, or each unit can exist physically alone, or two or more units can be integrated into one unit. The above integrated units can be implemented in the form of hardware or in the form of software functional units.

[0086] When the integrated unit is implemented in the form of a software functional unit and sold or used as an independent product, it can be stored in a computer-readable storage medium. Based on this understanding, the technical solution of this application, in essence, or the part that contributes to the prior art, or all or part of this technical solution, can be embodied in the form of a software product. This computer software product is stored in a storage medium and includes several instructions for causing a computer device (which may be a personal computer, a server, or a network device, etc.) to execute all or part of the steps of the methods described in various embodiments of this application. The foregoing storage medium includes: various media that can store program codes, such as USB flash drives, mobile hard disks, read-only memories (English full name: Read-Only Memory, English abbreviation: ROM), random access memories (English full name: Random Access Memory, English abbreviation: RAM), magnetic disks, or optical discs.

[0087] As described above, the above embodiments are only used to illustrate the technical solutions of this application, rather than to limit them; although this application has been described in detail with reference to the foregoing embodiments, those of ordinary skill in the art should understand that: they can still modify the technical solutions recorded in the foregoing embodiments, or perform equivalent replacements on some of the technical features; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the spirit and scope of the technical solutions of various embodiments of this application.

Claims

1. An analysis method for the influence of circuit breaker opening on the maximum value of PT current, characterized in that, Including: S1. Obtain several electrical parameters of the power grid system to be analyzed. The several electrical parameters include: PT wiring type, ground fault, and corresponding protection actions; S2. Conduct a theoretical analysis on the current relationship at each end of the primary side of the PT according to the ground fault and the corresponding protection actions, and obtain the first variation law of the current peak value at each end of the primary side of the PT with the opening time of the circuit breaker; S3. Establish a simulation analysis model of the primary side current of the PT. Calculate the primary side current of the PT when the circuit breaker opens at different moments within one cycle through the simulation analysis model, and obtain the second variation law of the primary side current peak value of the PT with the opening moment of the circuit breaker; S4. Mutually verify the first variation law and the second variation law, and construct the variation law of the primary side current peak value of the PT with the opening moment of the circuit breaker; Among them, the first variation law is: the variation period of the primary side voltage amplitude of the PT is half of the power frequency period; the second variation law is: the primary side current peak value of the PT approximately changes periodically with the opening moment of the circuit breaker, and its period is half of the power frequency period; Among them, the calculation of the primary side current of the PT when the circuit breaker opens at different moments within one cycle through the simulation analysis model specifically includes: According to the ground fault and the corresponding protection actions, obtain the empirical value of the opening time of the circuit breaker; Adopt a time control method to set the opening time of the circuit breaker to vary at equal intervals within one cycle after the empirical value, and simulate and calculate the primary side current peak value of the PT at different opening moments of different circuit breakers.

2. The analysis method for the influence of the breaker opening on the maximum value of the PT current according to claim 1, characterized in that The several electrical parameters also include: Power grid structure, line parameters, transformer parameters, PT excitation characteristics, equivalent power source, equivalent load.

3. The analysis method for the influence of breaker opening on the maximum value of PT current according to claim 2, characterized in that, The establishment of the simulation analysis model of the primary side current of the PT specifically includes: Based on electromagnetic transient simulation software, establish a simulation analysis model of the primary side current of the PT according to the several electrical parameters.

4. The analysis method for the influence of the breaker opening on the maximum value of the PT current according to claim 1, wherein, After obtaining the first variation law of the current peak value at each end of the primary side of the PT with the opening time of the circuit breaker, it further includes: Analyze based on the first variation law to obtain the first opening moment of the circuit breaker corresponding to the maximum value of the primary side current of the PT.

5. The analysis method for the influence of the breaker opening on the maximum value of the PT current according to claim 4, characterized in that, After constructing the variation law of the primary side current peak value of the PT with the opening moment of the circuit breaker, it further includes: Obtain the opening moment of the circuit breaker corresponding to the maximum value of the primary side current of the PT according to the first opening moment.

6. An analysis system for the influence of breaker opening on the maximum value of PT current, characterized in that, Including: An acquisition unit for obtaining several electrical parameters of the power grid system to be analyzed. The several electrical parameters include: PT wiring type, ground fault, and corresponding protection actions; A theoretical analysis unit for conducting a theoretical analysis on the current relationship at each end of the primary side of the PT according to the ground fault and the corresponding protection actions in the electrical parameters, and obtaining the first variation law of the current peak value at each end of the primary side of the PT with the opening time of the circuit breaker; A simulation analysis unit for establishing a simulation analysis model of the primary side current of the PT, calculating the primary side current of the PT when the circuit breaker opens at different moments within one cycle through the simulation analysis model, and obtaining the second variation law of the primary side current peak value of the PT with the opening moment of the circuit breaker; A building unit for mutually verifying the first variation law and the second variation law, and building the variation law of the peak value of the primary side current of the PT with respect to the opening moment of the circuit breaker; Wherein, the first variation law is that the variation period of the primary side voltage amplitude of the PT is half of the power frequency period; the second variation law is that the peak value of the primary side current of the PT changes approximately periodically with respect to the opening moment of the circuit breaker, and its period is half of the power frequency period; Wherein, the simulation analysis unit is specifically configured to: Based on the electromagnetic transient simulation software, establish a simulation analysis model of the primary side current of the PT according to a plurality of the electrical parameters; Obtain an empirical value of the opening time of the circuit breaker according to the ground fault and the corresponding protection action; Adopt a time control method to set the opening time of the circuit breaker to vary at equal intervals within one cycle after the empirical value, and simulate and calculate the peak value of the primary side current of the PT at different opening moments of different circuit breakers, so as to obtain the second variation law of the peak value of the primary side current of the PT with respect to the opening moment of the circuit breaker.

7. An analysis device for the influence of the opening of a circuit breaker on the maximum value of PT current, characterized in that, The device includes a processor and a memory: The memory is used to store program codes and transmit the program codes to the processor; The processor is used to execute the analysis method for the influence of the opening of the circuit breaker on the maximum value of the PT current according to the instructions in the program codes in any one of claims 1-5.

8. A computer-readable storage medium, characterized in that, The computer-readable storage medium is used to store program codes, and the program codes are used to execute the analysis method for the influence of the opening of the circuit breaker on the maximum value of the PT current according to any one of claims 1-5.

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