Voltage out-of-limit suppression method and device, storage medium and equipment

Abstract

The invention discloses a voltage out-of-limit suppression method and device, a storage medium and equipment. The method comprises the following steps: acquiring an electromagnetic transient model and a lightning arrester model; the electromagnetic transient model is optimized according to actual measurement data and an initial model of the first phase-shifting transformer; the lightning arrester model simulates switch overvoltage based on the piecewise linear model, a lightning arrester and a second phase-shifting transformer, and the lightning arrester is connected with the second phase-shifting transformer; the parameters of the electromagnetic transient model and the lightning arrester model are combined, a virtual lightning arrester and a virtual phase-shifting transformer are constructed, the virtual phase-shifting transformer is used for suppressing analog power frequency overvoltage, and the virtual lightning arrester is used for suppressing analog switch overvoltage; and controlling a lightning arrester and a second phase-shifting transformer in the power system according to the equivalent circuit model. According to the invention, the efficiency of voltage out-of-limit suppression is improved, and the problem that the reactance of the phase-shifting transformer cannot be effectively utilized to suppress voltage out-of-limit in the prior art is solved.

Description

Technical Field

[0001] The present invention relates to the field of voltage over-limit suppression, and in particular to a voltage over-limit suppression method, device, storage medium and equipment. Background Art

[0002] As a new type of flexible AC transmission system control equipment, the phase-shifting transformer can effectively solve the problems of uneven power flow distribution and electromagnetic circulating current faults in the power grid, and has good application prospects in improving the transmission capacity and utilization rate of the power grid. However, my country currently has relatively insufficient experience in the actual engineering application of phase-shifting transformers, and most studies are still in the stage of modeling, parameter calculation, feasibility analysis and scheme evaluation. When the power system is operating normally, the main function of the phase-shifting transformer is to control the power flow, but when the system has a voltage over-limit problem, the power flow control scheme will no longer be applicable. In addition, for controllable phase-shifting transformers, the overvoltage tolerance of its power electronic devices is relatively limited, and overvoltage may threaten power electronic devices and even the phase-shifting transformer itself. The impedance of the phase-shifting transformer connected to the line is different at different gears, so that the phase-shifting transformer has a certain ability to suppress voltage over-limit faults. At present, some research has been conducted on the application of phase-shifting transformers in actual power grids, but most of them focus on power flow calculation and control strategies, and do not consider the impact of system voltage over-limit after installing phase-shifting transformers. These effects make the existing technology unable to effectively use the reactance of the phase-shifting transformer to suppress voltage over-limit. Summary of the invention

[0003] The present invention provides a voltage over-limit suppression method, device, storage medium and equipment to solve the problem in the prior art that the reactance of a phase-shifting transformer cannot be effectively utilized to suppress voltage over-limit.

[0004] In a first aspect, the present application provides a voltage over-limit suppression method, comprising:

[0005] Obtain electromagnetic transient model and arrester model;

[0006] The electromagnetic transient model is obtained by optimizing the initial electromagnetic transient model based on actual measurement data and the first phase-shifting transformer; the lightning arrester model is obtained by simulating the switch overvoltage based on the piecewise linear model, the lightning arrester and the second phase-shifting transformer, and the lightning arrester is connected to the second phase-shifting transformer;

[0007] Combining the various parameters of the electromagnetic transient model and the arrester model to construct a virtual arrester and a virtual phase-shifting transformer; wherein the virtual phase-shifting transformer is used to suppress simulated power frequency overvoltage; and the virtual arrester is used to suppress simulated switch overvoltage;

[0008] According to the equivalent circuit model, the lightning arrester and the second phase-shifting transformer in the power system are controlled.

[0009] The present application can achieve effective suppression of power frequency overvoltage and switch overvoltage in the power system by acquiring and optimizing the electromagnetic transient model and the arrester model. First, the optimization of the electromagnetic transient model is based on the actual measurement data and the characteristics of the phase-shifting transformer, which ensures that the model accurately simulates and predicts the power frequency overvoltage in the power grid. Secondly, the arrester model uses a piecewise linear model to simulate the switch overvoltage, which improves the stability and accuracy of the model under complex power grid conditions. Combining the parameters of these two models, the equivalent circuit model obtained can combine the advantages of both, on the one hand, using the characteristics of the phase-shifting transformer to suppress the power frequency overvoltage, and on the other hand, using the characteristics of the arrester to suppress the switch overvoltage. The use of this comprehensive model not only improves the efficiency of voltage over-limit suppression, but also enhances the adaptability and reliability of the power system in the face of different overvoltage situations, so as to solve the problem that the reactance of the phase-shifting transformer cannot be effectively used to suppress the voltage over-limit in the prior art.

[0010] As a preferred embodiment of the first aspect, the electromagnetic transient model is obtained by optimizing the initial electromagnetic transient model based on actual measurement data and the first phase-shifting transformer, specifically:

[0011] Obtain actual measurement data, transformer rated parameters, structural information and material properties;

[0012] An initial electromagnetic transient model is constructed according to rated parameters, structural information and material properties of the transformer;

[0013] According to the actual measurement data, simulation is performed on the initial electromagnetic transient model, and parameters of the initial electromagnetic transient model are corrected to obtain a first electromagnetic transient model;

[0014] The first electromagnetic transient model is optimized according to the first phase-shifting transformer to obtain an electromagnetic transient model.

[0015] In this preferred embodiment, the electromagnetic transient model obtained by the present application through this process can provide an accurate prediction of the behavior of the phase-shifting transformer in the power system because it is constructed and optimized based on actual measurement data and detailed transformer characteristics. First, by collecting the actual rated parameters, structural information and material properties of the transformer, the close correspondence between the initial model and the actual device is ensured. Subsequently, the initial model is simulated and parameter corrected using actual measurement data to further improve the accuracy of the model, so that the first electromagnetic transient model can more realistically reflect the performance of the transformer under various working conditions. Finally, the first model is optimized according to the characteristics of the phase-shifting transformer, and the obtained electromagnetic transient model can not only accurately simulate the power frequency overvoltage, but also effectively predict and suppress these overvoltage events. Therefore, the use of this optimized model can improve the stability and safety of the power system, reduce equipment damage and power outages caused by overvoltage, thereby improving the reliability and economic benefits of the entire power network.

[0016] As a preferred embodiment of the first aspect, the first electromagnetic transient model is optimized according to the phase-shifting transformer to obtain the electromagnetic transient model, which is specifically:

[0017] According to the electromagnetic transient program, the phase-shifting transformer is simulated at different access positions of the line of the first electromagnetic transient model to obtain simulation results at different access positions;

[0018] The different access positions include the line head end, the line and the line end; the simulation results of the different access positions include the power frequency overvoltage simulation results caused by asymmetric grounding faults and the power frequency overvoltage simulation results caused by load shedding;

[0019] The first electromagnetic transient model is optimized according to the simulation results of the different access positions to obtain an electromagnetic transient model.

[0020] In this preferred embodiment, the present application performs detailed electromagnetic transient simulation on the phase-shifting transformer at different access positions (head end, on the line and end) of the power line, and can obtain accurate simulation results of power frequency overvoltage caused by various asymmetric ground faults and load shedding conditions. The present application performs targeted optimization on the first electromagnetic transient model to obtain a more accurate and reliable electromagnetic transient model. This optimized model can more accurately predict and simulate the suppression effect of the phase-shifting transformer on voltage over-limit in actual power grid operation, enhance the adaptability and stability of the power grid in the face of different faults and operating conditions, and thus improve the safety and reliability of the power system. Through this method, the voltage over-limit suppression strategy can be more effectively designed and implemented, reducing potential equipment damage and power outage risks, and ensuring the continuity and stability of power supply.

[0021] As a preferred embodiment of the first aspect, the arrester model is obtained by simulating switch overvoltage according to a piecewise linear model, an arrester and a second phase-shifting transformer, and the arrester is connected to the second phase-shifting transformer, specifically:

[0022] According to the electromagnetic transient program, the arrester and the second phase-shifting transformer are simulated for switching overvoltage in a piecewise linear model to obtain the arrester model;

[0023] Wherein, the lightning arrester is connected to the power supply side and the load side of the second phase-shifting transformer.

[0024] In this preferred embodiment, the present application first uses an electromagnetic transient program to simulate the switching overvoltage of a transformer equipped with a metal oxide lightning arrester. Through this simulation, the response characteristics of the lightning arrester under different conditions can be obtained, and a piecewise linear model is established accordingly, which can simulate the performance of the lightning arrester in actual power grid operation. The beneficial effect of this piecewise linear model is that it simplifies the calculation process and improves the stability and calculation efficiency of the model by decomposing complex nonlinear characteristics into multiple linear intervals. This model can effectively simulate the role of the lightning arrester in limiting the switching overvoltage, thereby improving the safety and reliability of the power system when facing the operating overvoltage. In addition, the piecewise linear model also helps to optimize the design and parameter selection of the lightning arrester, so that it can better adapt to the protection requirements of the power system, and further enhance the stability and safety of the power system.

[0025] In a second aspect, the present application provides a voltage over-limit suppression device. The voltage over-limit suppression device includes an acquisition module, a construction module and a control module;

[0026] The acquisition module is used to obtain the electromagnetic transient model and the arrester model;

[0027] The electromagnetic transient model is obtained by optimizing the initial electromagnetic transient model based on actual measurement data and the first phase-shifting transformer; the lightning arrester model is obtained by simulating the switch overvoltage based on the piecewise linear model, the lightning arrester and the second phase-shifting transformer, and the lightning arrester is connected to the second phase-shifting transformer;

[0028] The construction module is used to combine the various parameters of the electromagnetic transient model and the arrester model to construct a virtual arrester and a virtual phase-shifting transformer; wherein the virtual phase-shifting transformer is used to suppress the simulated power frequency overvoltage; and the virtual arrester is used to suppress the simulated switch overvoltage;

[0029] The control module is used to control the lightning arrester and the second phase-shifting transformer in the power system according to the equivalent circuit model.

[0030] This device uses three modules to divide the work and coordinate the work to better suppress the voltage through the phase-shifting transformer. This application can achieve effective suppression of power frequency overvoltage and switch overvoltage in the power system by obtaining and optimizing the electromagnetic transient model and the arrester model. First, the optimization of the electromagnetic transient model is based on the actual measurement data and the characteristics of the phase-shifting transformer, which ensures that the model accurately simulates and predicts the power frequency overvoltage in the power grid. Secondly, the arrester model uses a piecewise linear model to simulate the switch overvoltage, which improves the stability and accuracy of the model under complex power grid conditions. Combining the parameters of the two models, the equivalent circuit model obtained can combine the advantages of both. On the one hand, the characteristics of the phase-shifting transformer are used to suppress the power frequency overvoltage, and on the other hand, the characteristics of the arrester are used to suppress the switch overvoltage. The use of this comprehensive model not only improves the efficiency of voltage over-limit suppression, but also enhances the adaptability and reliability of the power system in the face of different overvoltage conditions, so as to solve the problem that the reactance of the phase-shifting transformer cannot be effectively used to suppress the voltage over-limit in the prior art.

[0031] As a preferred embodiment of the second aspect, the electromagnetic transient model is obtained by optimizing the initial electromagnetic transient model based on actual measurement data and the first phase-shifting transformer, specifically:

[0032] Obtain actual measurement data, transformer rated parameters, structural information and material properties;

[0033] An initial electromagnetic transient model is constructed according to rated parameters, structural information and material properties of the transformer;

[0034] According to the actual measurement data, simulation is performed on the initial electromagnetic transient model, and parameters of the initial electromagnetic transient model are corrected to obtain a first electromagnetic transient model;

[0035] The first electromagnetic transient model is optimized according to the first phase-shifting transformer to obtain an electromagnetic transient model.

[0036] In this preferred embodiment, the electromagnetic transient model obtained by the present application through this process can provide an accurate prediction of the behavior of the phase-shifting transformer in the power system because it is constructed and optimized based on actual measurement data and detailed transformer characteristics. First, by collecting the actual rated parameters, structural information and material properties of the transformer, the close correspondence between the initial model and the actual device is ensured. Subsequently, the initial model is simulated and parameter corrected using actual measurement data to further improve the accuracy of the model, so that the first electromagnetic transient model can more realistically reflect the performance of the transformer under various working conditions. Finally, the first model is optimized according to the characteristics of the phase-shifting transformer, and the obtained electromagnetic transient model can not only accurately simulate the power frequency overvoltage, but also effectively predict and suppress these overvoltage events. Therefore, the use of this optimized model can improve the stability and safety of the power system, reduce equipment damage and power outages caused by overvoltage, thereby improving the reliability and economic benefits of the entire power network.

[0037] As a preferred embodiment of the second aspect, the first electromagnetic transient model is optimized according to the phase-shifting transformer to obtain the electromagnetic transient model, which is specifically:

[0038] According to the electromagnetic transient program, the phase-shifting transformer is simulated at different access positions of the line of the first electromagnetic transient model to obtain simulation results at different access positions;

[0039] The different access positions include the line head end, the line and the line end; the simulation results of the different access positions include the power frequency overvoltage simulation results caused by asymmetric grounding faults and the power frequency overvoltage simulation results caused by load shedding;

[0040] The first electromagnetic transient model is optimized according to the simulation results of the different access positions to obtain an electromagnetic transient model.

[0041] In this preferred embodiment, the present application performs detailed electromagnetic transient simulation on the phase-shifting transformer at different access positions (head end, on the line and end) of the power line, and can obtain accurate simulation results of power frequency overvoltage caused by various asymmetric ground faults and load shedding conditions. The present application performs targeted optimization on the first electromagnetic transient model to obtain a more accurate and reliable electromagnetic transient model. This optimized model can more accurately predict and simulate the suppression effect of the phase-shifting transformer on voltage over-limit in actual power grid operation, enhance the adaptability and stability of the power grid in the face of different faults and operating conditions, and thus improve the safety and reliability of the power system. Through this method, the voltage over-limit suppression strategy can be more effectively designed and implemented, reducing potential equipment damage and power outage risks, and ensuring the continuity and stability of power supply.

[0042] As a preferred embodiment of the second aspect, the arrester model is obtained according to a piecewise linear model, an arrester and a second phase-shifting transformer simulating a switch overvoltage, and the arrester is connected to the second phase-shifting transformer, specifically:

[0043] According to the electromagnetic transient program, the arrester and the second phase-shifting transformer are simulated for switching overvoltage in a piecewise linear model to obtain the arrester model;

[0044] Wherein, the lightning arrester is connected to the power supply side and the load side of the second phase-shifting transformer.

[0045] In this preferred embodiment, the present application first uses an electromagnetic transient program to simulate the switching overvoltage of a transformer equipped with a metal oxide lightning arrester. Through this simulation, the response characteristics of the lightning arrester under different conditions can be obtained, and a piecewise linear model is established accordingly, which can simulate the performance of the lightning arrester in actual power grid operation. The beneficial effect of this piecewise linear model is that it simplifies the calculation process and improves the stability and calculation efficiency of the model by decomposing complex nonlinear characteristics into multiple linear intervals. This model can effectively simulate the role of the lightning arrester in limiting the switching overvoltage, thereby improving the safety and reliability of the power system when facing the operating overvoltage. In addition, the piecewise linear model also helps to optimize the design and parameter selection of the lightning arrester, so that it can better adapt to the protection requirements of the power system, and further enhance the stability and safety of the power system.

[0046] In a third aspect, the present application provides a computer-readable storage medium, the computer-readable storage medium including a stored computer program, wherein when the computer program is executed, the device where the computer-readable storage medium is located is controlled to execute a voltage over-limit suppression method as described. Its beneficial effect is the same as the voltage over-limit suppression method provided in the first aspect of the present application.

[0047] In a fourth aspect, the present application provides a terminal device, comprising a processor, a memory, and a computer program stored in the memory and configured to be executed by the processor, wherein when the processor executes the computer program, any one of the voltage over-limit suppression methods described in the first aspect is implemented. BRIEF DESCRIPTION OF THE DRAWINGS

[0048] Figure 1 : A schematic diagram of a flow chart of an embodiment of a voltage over-limit suppression method provided by the present application;

[0049] Figure 2 : A structural schematic diagram of an embodiment of the main circuit topology of the voltage over-limit suppression device for the phase-shifting transformer provided by the present application;

[0050] Figure 3: A structural schematic diagram of an embodiment of a thyristor voltage regulation topology structure in a phase-shifting transformer provided in the present application;

[0051] Figure 4 : A structural schematic diagram of an embodiment of a 500kV ultra-high voltage transmission line connection equipped with a phase-shifting transformer provided in the present application;

[0052] Figure 5 : A structural schematic diagram of an embodiment of the relationship between the phase shifting transformer gear position, phase shifting angle and the secondary winding connection of the parallel transformer provided by the present application;

[0053] Figure 6 : A schematic structural diagram of an embodiment of a voltage over-limit suppression device provided in the present application. DETAILED DESCRIPTION

[0054] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. 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.

[0055] Embodiment 1

[0056] Please refer to Figure 1 , which is a voltage over-limit suppression method provided by an embodiment of the present invention.

[0057] In this embodiment, the process of the voltage over-limit suppression method in this application is described in detail through steps S01-S03.

[0058] S01: Obtain electromagnetic transient model and lightning arrester model.

[0059] Among them, the electromagnetic transient model is obtained by optimizing the initial electromagnetic transient model based on the actual measurement data and the first phase-shifting transformer; the lightning arrester model is obtained by simulating the switch overvoltage based on the piecewise linear model, the lightning arrester and the second phase-shifting transformer, and the lightning arrester is connected to the second phase-shifting transformer, that is, the main topology structure corresponding to the voltage over-limit suppression method described in the present application is obtained, and the main topology structure is as follows Figure 2 shown.

[0060] As a preferred embodiment of the first embodiment, the electromagnetic transient model is obtained by optimizing the initial electromagnetic transient model based on actual measurement data and the first phase-shifting transformer, specifically:

[0061] Obtain actual measurement data, transformer rated parameters, structural information and material properties;

[0062] An initial electromagnetic transient model is constructed according to rated parameters, structural information and material properties of the transformer;

[0063] More specifically, the initial electromagnetic transient model consists of two parts: a series transformer and an excitation transformer. Both are three-phase double-winding transformers with input terminals SA, SB, SC and output terminals LA, LB, LC. The primary winding of the transformer is directly connected in series with the transmission line, and the middle tap is connected to the primary side of the excitation transformer. The secondary winding is connected in a triangle and is interconnected with the secondary side of the excitation transformer. The windings on both sides of the excitation transformer are star-connected with the neutral point grounded. The secondary winding consists of three coils with a turns ratio of 1:3:9, and the access method is controlled by a thyristor circuit. Each part of the coil of the secondary winding of the excitation transformer is controlled by a bridge circuit composed of four groups of reverse-parallel thyristors, such as Figure 3 As shown. Each thyristor is turned on when the voltage passes through zero, and the control circuit has three switch configurations, namely, thyristor group S1, S4 is turned on and the rest are turned off to output a forward voltage, thyristor group S2, S3 is turned on and the rest are turned off to output a reverse voltage, and thyristor group S1, S3 or S2, S4 is turned on and the rest are turned off to output zero voltage. There are 27 situations in the combination of different switch states of the three coils, that is, 27 gears.

[0064] Furthermore, the initial electromagnetic transient model requires the design of the overall parameters of the transformer. Since the specific requirements and actual conditions of different power systems vary greatly, it is impossible to give an accurate design method for the overall parameter design. We can only summarize the general design ideas and principles, that is, consider the case where the module corresponding to this application is installed on a high-voltage double-circuit transmission line, such as Figure 4 shown.

[0065] ① Impedance design: Considering the three factors of loss and operation stability, phase shift angle influence, and short-circuit current limitation, the impedance range of the double-core symmetrical phase-shifting transformer is designed according to the actual needs of the system;

[0066] ② Rated phase shift angle design: Taking the active power loss of the line and the power transmission limit as the constraint conditions, the active power calculation formula of the transmission line is as follows:

[0067]

[0068] Find the variable when it reaches the maximum value The value of is taken as the rated phase shift angle, where and are the sending end voltage and the receiving end voltage respectively, is the designed reactance, X is the equivalent reactance of the line, θ is the difference between the voltage phase angles and at both ends of the transmission line, is the difference between the phase angles of the voltages at both ends of the phase shifter;

[0069] ③ Capacity design: First, the transmission capacity of the phase shifter is determined with the optimal transmission power of the transmission line as the goal. Then, considering the investment cost and benefits, the nonlinear optimization method is used to optimize the transmission capacity. The basic expression is:

[0070] C total =C 1 -C 2 ,

[0071] Among them C total Represents the final total revenue, C 1 represents the investment cost, which is a nonlinear function with capacity as a variable, including research and development costs, installation costs, transportation costs, maintenance costs, etc. 2 is the expected revenue, which is a nonlinear function of capacity as a variable related to electricity price and service life;

[0072] ④ Rated voltage and current: The rated voltage is generally the rated voltage level of the installed transmission line, and the rated current is obtained by the designed rated voltage and capacity.

[0073] The first electromagnetic transient model is optimized according to the first phase-shifting transformer to obtain an electromagnetic transient model.

[0074] More specifically, it is necessary to collect the rated parameters, structural information and material properties of the transformer; use electromagnetic transient simulation software to build its equivalent circuit model based on the structure of the transformer; set key parameters such as winding inductance and resistance; use simulation tools to run electromagnetic transient analysis and observe the response of the transformer under different working conditions. Compare the simulation results with the actual measurement data and calibrate the model parameters to improve the model accuracy.

[0075] In this preferred embodiment, the electromagnetic transient model obtained by the present application through this process can provide an accurate prediction of the behavior of the phase-shifting transformer in the power system because it is constructed and optimized based on actual measurement data and detailed transformer characteristics. First, by collecting the actual rated parameters, structural information and material properties of the transformer, the close correspondence between the initial model and the actual equipment is ensured. Subsequently, the initial model is simulated and parameter corrected using actual measurement data to further improve the accuracy of the model, so that the first electromagnetic transient model can more realistically reflect the performance of the transformer under various working conditions, and the effectiveness of the electromagnetic transient model is verified through simulation examples, such as Figure 5 As shown. Finally, the first model is optimized according to the characteristics of the phase-shifting transformer, and the resulting electromagnetic transient model can not only accurately simulate power frequency overvoltages, but also effectively predict and suppress these overvoltage events. Therefore, the use of this optimization model can improve the stability and safety of the power system, reduce equipment damage and power outages caused by overvoltage, and thus improve the reliability and economic benefits of the entire power network.

[0076] As a preferred embodiment of the first embodiment, the first electromagnetic transient model is optimized according to the phase-shifting transformer to obtain the electromagnetic transient model, which is specifically:

[0077] According to the electromagnetic transient program, the phase-shifting transformer is simulated at different access positions of the line of the first electromagnetic transient model to obtain simulation results at different access positions;

[0078] The different access positions include the line head end, the line and the line end; the simulation results of the different access positions include the power frequency overvoltage simulation results caused by asymmetric grounding faults and the power frequency overvoltage simulation results caused by load shedding;

[0079] The first electromagnetic transient model is optimized according to the simulation results of the different access positions to obtain an electromagnetic transient model.

[0080] As a preferred embodiment of the first embodiment, the first electromagnetic transient model is optimized according to the phase-shifting transformer to obtain the electromagnetic transient model, which is specifically:

[0081] According to the electromagnetic transient program, the phase-shifting transformer is simulated at different access positions of the line of the first electromagnetic transient model to obtain simulation results at different access positions;

[0082] The different access positions include the line head end, the line and the line end; the simulation results of the different access positions include the power frequency overvoltage simulation results caused by asymmetric grounding faults and the power frequency overvoltage simulation results caused by load shedding;

[0083] The first electromagnetic transient model is optimized according to the simulation results of the different access positions to obtain an electromagnetic transient model.

[0084] More specifically, the different access locations include the line head end, the line and the line end, specifically:

[0085] Phase-shifting transformers installed on power lines can effectively suppress power-frequency overvoltages caused by single-phase grounding short circuits. The equivalent reactance of the phase-shifting transformer can reduce the grounding coefficient during single-phase faults. As the gear of the phase-shifting transformer increases, the grounding coefficient of the line under a single-phase grounding fault decreases, thereby enhancing the suppression effect. The phase-shifting transformer installed at the end of the line will make the voltage drop more significant due to its proximity to the fault point; when the phase-shifting transformer is installed at the head end, the suppression ability is relatively weak due to its distance from the fault point. It should be noted that the maximum power-frequency overvoltage usually occurs when the phase-shifting transformer is not installed, so there is no need to take additional suppression measures for the phase-shifting transformer.

[0086] When the phase-shifting transformer is connected to the line, the power frequency overvoltage caused by load shedding will be higher. When the phase-shifting transformer is installed at the end of the line, the circuit breaker will be disconnected, which will hardly affect the line overvoltage. When the phase-shifting transformer is installed at the head end, although the power frequency overvoltage is slightly higher than the former, its value can still meet the safety requirements of the power grid.

[0087] More specifically, the power frequency overvoltage simulation results caused by the asymmetric grounding fault and the power frequency overvoltage simulation results caused by load shedding are specifically:

[0088] In view of the power frequency overvoltage problem caused by asymmetric grounding faults, it is very important to study the impact of phase-shifting transformers on transmission lines. Asymmetric short circuit faults are a common type of fault in power systems. When a single-phase or two-phase ground short circuit occurs, the generation of zero-sequence current will cause power frequency overvoltage in the healthy phase, especially single-phase grounding faults are the most common.

[0089] Assume that a ground fault occurs on phase A. That is, use the DC electromagnetic transient calculation program to set a ground fault on phase A. Set the fault points to the beginning and end of the line respectively, and calculate the single-phase short-circuit power frequency overvoltage.

[0090] The symmetrical component method can be used in combination with the composite sequence network model for analysis. The non-fault phase voltage boost calculation formula is:

[0091] U B =U C =K W E,

[0092]

[0093] Positive sequence equivalent reactance of phase-shifting transformer:

[0094]

[0095] By tap position:

[0096]

[0097] It can be seen that the absolute value of the phase shift transformer gear position is proportional to the equivalent positive sequence impedance. The zero-sequence impedance value of the phase shifter is proportional to the positive sequence reactance when the configuration is 0. is equal to a constant value, that is:

[0098]

[0099] Phase shifting transformer Less than 1, and as the phase-shifting transformer gear increases, Therefore, the addition of the phase-shifting transformer reduces the line X 0 / X 1value, thereby reducing the grounding coefficient during single-phase fault and suppressing the increase of power frequency overvoltage.

[0100] Through the above analysis and simulation results, it can be concluded that the installation of phase shifters has a significant impact on power frequency overvoltage. Its introduction will increase the effective length of the transmission line, change the resonant characteristics of the system, and may lead to an increase in power frequency overvoltage. Specifically, the access of the phase shifter enhances the charging capacitor effect of the system, which may lead to an increase in the overvoltage multiple. At the same time, when load shedding or short circuit faults occur, its presence will also significantly increase the overvoltage amplitude, especially in the case of single-phase grounding faults. In addition, the installation position of the phase shifter, such as at the beginning or end of the line, will directly affect the degree of its enhancement of the capacitor effect, thereby having different degrees of influence on the power frequency overvoltage.

[0101] More specifically, regarding the power frequency overvoltage problem caused by load shedding, this application studies the impact of phase-shifting transformers on transmission lines. When studying power frequency overvoltage, "load shedding during normal power transmission" and "load shedding due to single-phase grounding of the line" are usually used as conditions for determining power frequency overvoltage in the power grid, and the factors that affect power frequency overvoltage in different situations are also different.

[0102] Under normal transmission line conditions, the main factors affecting the increase of power frequency overvoltage caused by load shedding are as follows:

[0103] ① The power flow of the line before load shedding, especially the scale of reactive power flow;

[0104] ②The capacity of the power supply;

[0105] ③Line length.

[0106] Connecting a phase-shifting transformer to a line is equivalent to increasing the line length, and the power frequency overvoltage multiple increases. In normal operation, the phase-shifting transformer will increase the power frequency overvoltage caused by load shedding, and as the gear of the phase-shifting transformer increases, the overvoltage multiple will also increase.

[0107] When the phase-shifting transformer is installed at the end of the line, after the circuit breaker is disconnected, the capacitive current no longer flows through the series transformer, so the phase-shifting transformer has less impact on the line overvoltage; when the phase-shifting transformer is installed at the beginning of the line, the capacitive effect will be aggravated, resulting in a greater power frequency overvoltage multiple. According to simulation measurements, the maximum overvoltage value is 1.154, which meets the requirements of GB / T50064-2014 "Design Specifications for Overvoltage Protection and Insulation Coordination of AC Electrical Installations".

[0108] After the phase-shifting transformer is connected to the transmission line, the overvoltage caused by fault load shedding becomes more obvious, with the maximum overvoltage reaching 1.358, but still lower than the 1.4 times limit value specified in GB / T50064-2014.

[0109] In this preferred embodiment, the present application performs detailed electromagnetic transient simulation on the phase-shifting transformer at different access positions (head end, on the line and end) of the power line, and can obtain accurate simulation results of power frequency overvoltage caused by various asymmetric ground faults and load shedding conditions. The present application performs targeted optimization on the first electromagnetic transient model to obtain a more accurate and reliable electromagnetic transient model. This optimized model can more accurately predict and simulate the suppression effect of the phase-shifting transformer on voltage over-limit in actual power grid operation, enhance the adaptability and stability of the power grid in the face of different faults and operating conditions, and thus improve the safety and reliability of the power system. Through this method, the voltage over-limit suppression strategy can be more effectively designed and implemented, reducing potential equipment damage and power outage risks, and ensuring the continuity and stability of power supply.

[0110] As a preferred embodiment of the first embodiment, the arrester model is obtained according to the piecewise linear model, the arrester and the second phase-shifting transformer simulating the switch overvoltage, and the arrester is connected to the second phase-shifting transformer, specifically:

[0111] According to the electromagnetic transient program, the arrester and the second phase-shifting transformer are simulated for switching overvoltage in a piecewise linear model to obtain the arrester model;

[0112] Wherein, the lightning arrester is connected to the power supply side and the load side of the second phase-shifting transformer.

[0113] More specifically, the nonlinear voltage-current discharge characteristics were first modeled using a set of fitting exponentials. The nonlinear equations in the electromagnetic transient program were then solved using the Newton-Raphson iteration format. The results showed that the arrester exponential model had numerical convergence problems under certain network conditions of the electromagnetic transient program statistical simulation. In order to ensure the smooth completion of the statistical simulation, a piecewise linear model was used. The accuracy of the piecewise model was also confirmed by comparing the respective results with the exponential model of the arrester. After solving the numerical convergence problem of the arrester nonlinear model, a series of switching operations were simulated using the electromagnetic transient program.

[0114] In this preferred embodiment, the present application first uses an electromagnetic transient program to simulate the switching overvoltage of a transformer equipped with a metal oxide lightning arrester. Through this simulation, the response characteristics of the lightning arrester under different conditions can be obtained, and a piecewise linear model is established accordingly, which can simulate the performance of the lightning arrester in actual power grid operation. The beneficial effect of this piecewise linear model is that it simplifies the calculation process and improves the stability and calculation efficiency of the model by decomposing complex nonlinear characteristics into multiple linear intervals. This model can effectively simulate the role of the lightning arrester in limiting the switching overvoltage, thereby improving the safety and reliability of the power system when facing the operating overvoltage. In addition, the piecewise linear model also helps to optimize the design and parameter selection of the lightning arrester, so that it can better adapt to the protection requirements of the power system, and further enhance the stability and safety of the power system.

[0115] S02: Combining the various parameters of the electromagnetic transient model and the arrester model to construct a virtual arrester and a virtual phase-shifting transformer; wherein the virtual phase-shifting transformer is used to suppress simulated power frequency overvoltage; and the virtual arrester is used to suppress simulated switch overvoltage.

[0116] S03: According to the equivalent circuit model, control the lightning arrester and the second phase-shifting transformer in the power system.

[0117] Furthermore, combined with the reference provided by the voltage suppression effect of the phase-shifting transformer in the power grid in step S02, the lightning arrester described in the present application is controlled to achieve a balance between the switch overvoltage suppression effect and the line overvoltage suppression effect; the comprehensive model combining the phase-shifting transformer and the lightning arrester is further optimized to adjust the voltage suppression effect, and a second phase-shifting transformer is obtained.

[0118] The present application can achieve effective suppression of power frequency overvoltage and switch overvoltage in the power system by acquiring and optimizing the electromagnetic transient model and the arrester model. First, the optimization of the electromagnetic transient model is based on the actual measurement data and the characteristics of the phase-shifting transformer, which ensures that the model accurately simulates and predicts the power frequency overvoltage in the power grid. Secondly, the arrester model uses a piecewise linear model to simulate the switch overvoltage, which improves the stability and accuracy of the model under complex power grid conditions. Combining the parameters of these two models, the equivalent circuit model obtained can combine the advantages of both, on the one hand, using the characteristics of the phase-shifting transformer to suppress the power frequency overvoltage, and on the other hand, using the characteristics of the arrester to suppress the switch overvoltage. The use of this comprehensive model not only improves the efficiency of voltage over-limit suppression, but also enhances the adaptability and reliability of the power system in the face of different overvoltage situations, so as to solve the problem that the reactance of the phase-shifting transformer cannot be effectively used to suppress the voltage over-limit in the prior art.

[0119] Embodiment 2

[0120] Please refer to Figure 6 , which is a voltage over-limit suppression device provided in an embodiment of the present application.

[0121] In this embodiment, the voltage over-limit suppression device includes an acquisition module 10 , a construction module 20 and a control module 30 .

[0122] The acquisition module 10 is used to acquire the electromagnetic transient model and the arrester model.

[0123] Among them, the electromagnetic transient model is obtained by optimizing the initial electromagnetic transient model based on the actual measurement data and the first phase-shifting transformer; the lightning arrester model is obtained by simulating the switch overvoltage based on the piecewise linear model, the lightning arrester and the second phase-shifting transformer, and the lightning arrester is connected to the second phase-shifting transformer, that is, the main topology structure corresponding to the voltage over-limit suppression method described in the present application is obtained, and the main topology structure is as follows Figure 2 shown.

[0124] As a preferred embodiment of the second embodiment, the electromagnetic transient model is obtained by optimizing the initial electromagnetic transient model based on actual measurement data and the first phase-shifting transformer, specifically:

[0125] Obtain actual measurement data, transformer rated parameters, structural information and material properties;

[0126] An initial electromagnetic transient model is constructed according to rated parameters, structural information and material properties of the transformer;

[0127] More specifically, the initial electromagnetic transient model consists of two parts: a series transformer and an excitation transformer. Both are three-phase double-winding transformers with input terminals SA, SB, SC and output terminals LA, LB, LC. The primary winding of the transformer is directly connected in series with the transmission line, and the middle tap is connected to the primary side of the excitation transformer. The secondary winding is connected in a triangle and is interconnected with the secondary side of the excitation transformer. The windings on both sides of the excitation transformer are star-connected with the neutral point grounded. The secondary winding consists of three coils with a turns ratio of 1:3:9, and the access method is controlled by a thyristor circuit. Each part of the coil of the secondary winding of the excitation transformer is controlled by a bridge circuit composed of four groups of reverse-parallel thyristors, such as Figure 3 As shown. Each thyristor is turned on when the voltage passes through zero, and the control circuit has three switch configurations, namely, thyristor group S1, S4 is turned on and the rest are turned off to output a forward voltage, thyristor group S2, S3 is turned on and the rest are turned off to output a reverse voltage, and thyristor group S1, S3 or S2, S4 is turned on and the rest are turned off to output zero voltage. There are 27 situations in the combination of different switch states of the three coils, that is, 27 gears.

[0128] Furthermore, the initial electromagnetic transient model requires the design of the overall parameters of the transformer. Since the specific requirements and actual conditions of different power systems vary greatly, it is impossible to give an accurate design method for the overall parameter design. Only general design ideas and principles can be summarized. That is, consider the case where the module corresponding to this application is installed on a high-voltage double-circuit transmission line, such as Figure 4 shown.

[0129] ① Impedance design: Considering the three factors of loss and operation stability, phase shift angle influence, and short-circuit current limitation, the impedance range of the double-core symmetrical phase-shifting transformer is designed according to the actual needs of the system;

[0130] ② Rated phase shift angle design: Taking the active power loss of the line and the power transmission limit as the constraint conditions, the active power calculation formula of the transmission line is as follows:

[0131]

[0132] Find the variable when it reaches the maximum value The value of is taken as the rated phase shift angle, where and are the sending end voltage and the receiving end voltage respectively, is the designed reactance, X is the equivalent reactance of the line, θ is the difference between the voltage phase angles and at both ends of the transmission line, is the difference between the phase angles of the voltages at both ends of the phase shifter;

[0133] ③ Capacity design: First, the transmission capacity of the phase shifter is determined with the optimal transmission power of the transmission line as the goal. Then, considering the investment cost and benefits, the nonlinear optimization method is used to optimize the transmission capacity. The basic expression is:

[0134] C total =C 1 -C 2 ,

[0135] Among them C total Represents the final total revenue, C 1 represents the investment cost, which is a nonlinear function with capacity as a variable, including research and development costs, installation costs, transportation costs, maintenance costs, etc. 2 is the expected revenue, which is a nonlinear function of capacity as a variable related to electricity price and service life;

[0136] ④ Rated voltage and current: The rated voltage is generally the rated voltage level of the installed transmission line, and the rated current is obtained by the designed rated voltage and capacity.

[0137] The first electromagnetic transient model is optimized according to the first phase-shifting transformer to obtain an electromagnetic transient model.

[0138] More specifically, it is necessary to collect the rated parameters, structural information and material properties of the transformer; use electromagnetic transient simulation software to build its equivalent circuit model based on the structure of the transformer; set key parameters such as winding inductance and resistance; use simulation tools to run electromagnetic transient analysis and observe the response of the transformer under different working conditions. Compare the simulation results with the actual measurement data and calibrate the model parameters to improve the model accuracy.

[0139] In this preferred embodiment, the electromagnetic transient model obtained by the present application through this process can provide an accurate prediction of the behavior of the phase-shifting transformer in the power system because it is constructed and optimized based on actual measurement data and detailed transformer characteristics. First, by collecting the actual rated parameters, structural information and material properties of the transformer, the close correspondence between the initial model and the actual equipment is ensured. Subsequently, the initial model is simulated and parameter corrected using actual measurement data to further improve the accuracy of the model, so that the first electromagnetic transient model can more realistically reflect the performance of the transformer under various working conditions, and the effectiveness of the electromagnetic transient model is verified through simulation examples, such as Figure 5 As shown. Finally, the first model is optimized according to the characteristics of the phase-shifting transformer, and the resulting electromagnetic transient model can not only accurately simulate power frequency overvoltages, but also effectively predict and suppress these overvoltage events. Therefore, the use of this optimization model can improve the stability and safety of the power system, reduce equipment damage and power outages caused by overvoltage, and thus improve the reliability and economic benefits of the entire power network.

[0140] As a preferred embodiment of the second embodiment, the first electromagnetic transient model is optimized according to the phase-shifting transformer to obtain the electromagnetic transient model, which is specifically:

[0141] According to the electromagnetic transient program, the phase-shifting transformer is simulated at different access positions of the line of the first electromagnetic transient model to obtain simulation results at different access positions;

[0142] The different access positions include the line head end, the line and the line end; the simulation results of the different access positions include the power frequency overvoltage simulation results caused by asymmetric grounding faults and the power frequency overvoltage simulation results caused by load shedding;

[0143] The first electromagnetic transient model is optimized according to the simulation results of the different access positions to obtain an electromagnetic transient model.

[0144] As a preferred embodiment of the second embodiment, the first electromagnetic transient model is optimized according to the phase-shifting transformer to obtain the electromagnetic transient model, which is specifically:

[0145] According to the electromagnetic transient program, the phase-shifting transformer is simulated at different access positions of the line of the first electromagnetic transient model to obtain simulation results at different access positions;

[0146] The different access positions include the line head end, the line and the line end; the simulation results of the different access positions include the power frequency overvoltage simulation results caused by asymmetric grounding faults and the power frequency overvoltage simulation results caused by load shedding;

[0147] The first electromagnetic transient model is optimized according to the simulation results of the different access positions to obtain an electromagnetic transient model.

[0148] More specifically, the different access locations include the line head end, the line and the line end, specifically:

[0149] Phase-shifting transformers installed on power lines can effectively suppress power-frequency overvoltages caused by single-phase grounding short circuits. The equivalent reactance of the phase-shifting transformer can reduce the grounding coefficient during single-phase faults. As the gear of the phase-shifting transformer increases, the grounding coefficient of the line under a single-phase grounding fault decreases, thereby enhancing the suppression effect. The phase-shifting transformer installed at the end of the line will make the voltage drop more significant due to its proximity to the fault point; when the phase-shifting transformer is installed at the head end, the suppression ability is relatively weak due to its distance from the fault point. It should be noted that the maximum power-frequency overvoltage usually occurs when the phase-shifting transformer is not installed, so there is no need to take additional suppression measures for the phase-shifting transformer.

[0150] When the phase-shifting transformer is connected to the line, the power frequency overvoltage caused by load shedding will be higher. When the phase-shifting transformer is installed at the end of the line, the circuit breaker will be disconnected, which will hardly affect the line overvoltage. When the phase-shifting transformer is installed at the head end, although the power frequency overvoltage is slightly higher than the former, its value can still meet the safety requirements of the power grid.

[0151] More specifically, the power frequency overvoltage simulation results caused by the asymmetric grounding fault and the power frequency overvoltage simulation results caused by load shedding are specifically:

[0152] In view of the power frequency overvoltage problem caused by asymmetric grounding faults, it is very important to study the impact of phase-shifting transformers on transmission lines. Asymmetric short circuit faults are a common type of fault in power systems. When a single-phase or two-phase ground short circuit occurs, the generation of zero-sequence current will cause power frequency overvoltage in the healthy phase, especially single-phase grounding faults are the most common.

[0153] Assume that a ground fault occurs on phase A. That is, use the DC electromagnetic transient calculation program to set a ground fault on phase A. Set the fault points to the beginning and end of the line respectively, and calculate the single-phase short-circuit power frequency overvoltage.

[0154] The symmetrical component method can be used in combination with the composite sequence network model for analysis. The non-fault phase voltage boost calculation formula is:

[0155] U B =U C =K W E,

[0156]

[0157] Positive sequence equivalent reactance of phase-shifting transformer:

[0158]

[0159] By tap position:

[0160]

[0161] It can be seen that the absolute value of the phase shift transformer gear position is proportional to the equivalent positive sequence impedance. The zero-sequence impedance value of the phase shifter is proportional to the positive sequence reactance when the configuration is 0. is equal to a constant value, namely:

[0162]

[0163] Phase shifting transformer Less than 1, and as the phase-shifting transformer gear increases, Therefore, the addition of the phase-shifting transformer reduces the line X 0 / X 1 value, thereby reducing the grounding coefficient during single-phase fault and suppressing the increase of power frequency overvoltage.

[0164] Through the above analysis and simulation results, it can be concluded that the installation of phase shifters has a significant impact on power frequency overvoltage. Its introduction will increase the effective length of the transmission line, change the resonant characteristics of the system, and may lead to an increase in power frequency overvoltage. Specifically, the access of the phase shifter enhances the charging capacitor effect of the system, which may lead to an increase in the overvoltage multiple. At the same time, when load shedding or short circuit faults occur, its presence will also significantly increase the overvoltage amplitude, especially in the case of single-phase grounding faults. In addition, the installation position of the phase shifter, such as at the beginning or end of the line, will directly affect the degree of its enhancement of the capacitor effect, thereby having different degrees of influence on the power frequency overvoltage.

[0165] More specifically, regarding the power frequency overvoltage problem caused by load shedding, this application studies the impact of phase-shifting transformers on transmission lines. When studying power frequency overvoltage, "load shedding during normal power transmission" and "load shedding due to single-phase grounding of the line" are usually used as conditions for determining power frequency overvoltage in the power grid, and the factors affecting power frequency overvoltage in different situations are also different.

[0166] Under normal transmission line conditions, the main factors affecting the increase of power frequency overvoltage caused by load shedding are as follows:

[0167] ① The power flow of the line before load shedding, especially the scale of reactive power flow;

[0168] ②The capacity of the power supply;

[0169] ③Line length.

[0170] Connecting a phase-shifting transformer to a line is equivalent to increasing the line length, and the power frequency overvoltage multiple increases. In normal operation, the phase-shifting transformer will increase the power frequency overvoltage caused by load shedding, and as the gear of the phase-shifting transformer increases, the overvoltage multiple will also increase.

[0171] When the phase-shifting transformer is installed at the end of the line, after the circuit breaker is disconnected, the capacitive current no longer flows through the series transformer, so the phase-shifting transformer has less impact on the line overvoltage; when the phase-shifting transformer is installed at the beginning of the line, the capacitive effect will be aggravated, resulting in a greater power frequency overvoltage multiple. According to simulation measurements, the maximum overvoltage value is 1.154, which meets the requirements of GB / T50064-2014 "Design Specifications for Overvoltage Protection and Insulation Coordination of AC Electrical Installations".

[0172] After the phase-shifting transformer is connected to the transmission line, the overvoltage caused by fault load shedding becomes more obvious, with the maximum overvoltage reaching 1.358, but still lower than the 1.4 times limit value specified in GB / T50064-2014.

[0173] In this preferred embodiment, the present application performs detailed electromagnetic transient simulation on the phase-shifting transformer at different access positions (head end, on the line and end) of the power line, and can obtain accurate simulation results of power frequency overvoltage caused by various asymmetric ground faults and load shedding conditions. The present application performs targeted optimization on the first electromagnetic transient model to obtain a more accurate and reliable electromagnetic transient model. This optimized model can more accurately predict and simulate the suppression effect of the phase-shifting transformer on voltage over-limit in actual power grid operation, enhance the adaptability and stability of the power grid in the face of different faults and operating conditions, and thus improve the safety and reliability of the power system. Through this method, the voltage over-limit suppression strategy can be more effectively designed and implemented, reducing potential equipment damage and power outage risks, and ensuring the continuity and stability of power supply.

[0174] As a preferred embodiment of the second embodiment, the arrester model is obtained according to the piecewise linear model, the arrester and the second phase-shifting transformer simulating the switch overvoltage, and the arrester is connected to the second phase-shifting transformer, specifically:

[0175] According to the electromagnetic transient program, the arrester and the second phase-shifting transformer are simulated for switching overvoltage in a piecewise linear model to obtain the arrester model;

[0176] Wherein, the lightning arrester is connected to the power supply side and the load side of the second phase-shifting transformer.

[0177] More specifically, the nonlinear voltage-current discharge characteristics were first modeled using a set of fitting exponentials. The nonlinear equations in the electromagnetic transient program were then solved using the Newton-Raphson iteration format. The results showed that the arrester exponential model had numerical convergence problems under certain network conditions of the electromagnetic transient program statistical simulation. In order to ensure the smooth completion of the statistical simulation, a piecewise linear model was used. The accuracy of the piecewise model was also confirmed by comparing the respective results with the exponential model of the arrester. After solving the numerical convergence problem of the arrester nonlinear model, a series of switching operations were simulated using the electromagnetic transient program.

[0178] In this preferred embodiment, the present application first uses an electromagnetic transient program to simulate the switching overvoltage of a transformer equipped with a metal oxide lightning arrester. Through this simulation, the response characteristics of the lightning arrester under different conditions can be obtained, and a piecewise linear model is established accordingly, which can simulate the performance of the lightning arrester in actual power grid operation. The beneficial effect of this piecewise linear model is that it simplifies the calculation process and improves the stability and calculation efficiency of the model by decomposing complex nonlinear characteristics into multiple linear intervals. This model can effectively simulate the role of the lightning arrester in limiting the switching overvoltage, thereby improving the safety and reliability of the power system when facing the operating overvoltage. In addition, the piecewise linear model also helps to optimize the design and parameter selection of the lightning arrester, so that it can better adapt to the protection requirements of the power system, and further enhance the stability and safety of the power system.

[0179] The construction module 20 is used to combine the various parameters of the electromagnetic transient model and the lightning arrester model to construct a virtual lightning arrester and a virtual phase-shifting transformer; wherein the virtual phase-shifting transformer is used to suppress simulated power frequency overvoltage; and the virtual lightning arrester is used to suppress simulated switch overvoltage.

[0180] The control module 30 is used to control the lightning arrester and the second phase-shifting transformer in the power system according to the equivalent circuit model.

[0181] Furthermore, combined with the reference provided by the voltage suppression effect of the phase-shifting transformer in the power grid in the construction module 20, the lightning arrester described in the present application is controlled to achieve a balance between the switch overvoltage suppression effect and the line overvoltage suppression effect; the comprehensive model combining the phase-shifting transformer and the lightning arrester is further optimized to adjust the voltage suppression effect, and a second phase-shifting transformer is obtained.

[0182] This device uses three modules to divide the work and coordinate the work to better suppress the voltage through the phase-shifting transformer. This application can achieve effective suppression of power frequency overvoltage and switch overvoltage in the power system by obtaining and optimizing the electromagnetic transient model and the arrester model. First, the optimization of the electromagnetic transient model is based on the actual measurement data and the characteristics of the phase-shifting transformer, which ensures that the model accurately simulates and predicts the power frequency overvoltage in the power grid. Secondly, the arrester model uses a piecewise linear model to simulate the switch overvoltage, which improves the stability and accuracy of the model under complex power grid conditions. Combining the parameters of the two models, the equivalent circuit model obtained can combine the advantages of both. On the one hand, the characteristics of the phase-shifting transformer are used to suppress the power frequency overvoltage, and on the other hand, the characteristics of the arrester are used to suppress the switch overvoltage. The use of this comprehensive model not only improves the efficiency of voltage over-limit suppression, but also enhances the adaptability and reliability of the power system in the face of different overvoltage conditions, so as to solve the problem that the reactance of the phase-shifting transformer cannot be effectively used to suppress the voltage over-limit in the prior art.

[0183] Embodiment three:

[0184] An embodiment of the present application provides a computer-readable storage medium, wherein the computer-readable storage medium includes a stored computer program, wherein when the computer program is executed, the device where the computer-readable storage medium is located is controlled to execute the voltage over-limit suppression method;

[0185] Wherein, if the voltage over-limit suppression method is implemented in the form of a software functional unit and used as an independent product, it can be stored in a computer-readable storage medium. Based on such an understanding, the present invention implements all or part of the processes in the above-mentioned embodiment method, and can also be completed by instructing the relevant hardware through a computer program. The computer program can be stored in a computer-readable storage medium, and the computer program can implement the steps of the above-mentioned various method embodiments when executed by the processor. Wherein, the computer program includes computer program code, and the computer program code can be in source code form, object code form, executable file or some intermediate form. The computer-readable medium can include: any entity or device capable of carrying the computer program code, recording medium, U disk, mobile hard disk, disk, optical disk, computer memory, read-only memory (ROM, Read-Only Memory), random access memory (RAM, Random Access Memory), electrical carrier signal, telecommunication signal and software distribution medium, etc.

[0186] Embodiment 4

[0187] The present application provides a terminal device, including a processor, a memory, and a computer program stored in the memory and configured to be executed by the processor, and when the processor executes the computer program, any one of the voltage over-limit suppression methods described in Example 1 is implemented.

[0188] The specific embodiments described above further illustrate the purpose, technical solutions and beneficial effects of the present invention. It should be understood that the above description is only a specific embodiment of the present invention and is not intended to limit the scope of protection of the present invention. It is particularly pointed out that for those skilled in the art, any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention should be included in the scope of protection of the present invention.

Claims

1. A voltage over-limit suppression method, characterized in that: include: Obtain electromagnetic transient model and arrester model; The electromagnetic transient model is obtained by optimizing the initial electromagnetic transient model based on actual measurement data and the first phase-shifting transformer; the lightning arrester model is obtained by simulating the switch overvoltage based on the piecewise linear model, the lightning arrester and the second phase-shifting transformer, and the lightning arrester is connected to the second phase-shifting transformer; Combining the various parameters of the electromagnetic transient model and the arrester model to construct a virtual arrester and a virtual phase-shifting transformer; wherein the virtual phase-shifting transformer is used to suppress simulated power frequency overvoltage; and the virtual arrester is used to suppress simulated switch overvoltage; According to the equivalent circuit model, the lightning arrester and the second phase-shifting transformer in the power system are controlled.

2. The voltage over-limit suppression method according to claim 1, characterized in that: The electromagnetic transient model is obtained by optimizing the initial electromagnetic transient model based on actual measurement data and the first phase-shifting transformer, and is specifically: Obtain actual measurement data, transformer rated parameters, structural information and material properties; An initial electromagnetic transient model is constructed according to rated parameters, structural information and material properties of the transformer; According to the actual measurement data, simulation is performed on the initial electromagnetic transient model, and parameters of the initial electromagnetic transient model are corrected to obtain a first electromagnetic transient model; The first electromagnetic transient model is optimized according to the first phase-shifting transformer to obtain an electromagnetic transient model.

3. The voltage over-limit suppression method according to claim 2, characterized in that: The first electromagnetic transient model is optimized according to the phase-shifting transformer to obtain an electromagnetic transient model, which is specifically: According to the electromagnetic transient program, the phase-shifting transformer is simulated at different access positions of the line of the first electromagnetic transient model to obtain simulation results at different access positions; The different access positions include the line head end, the line and the line end; the simulation results of the different access positions include the power frequency overvoltage simulation results caused by asymmetric grounding faults and the power frequency overvoltage simulation results caused by load shedding; The first electromagnetic transient model is optimized according to the simulation results of the different access positions to obtain an electromagnetic transient model.

4. The voltage over-limit suppression method according to claim 1, characterized in that: The arrester model is obtained by simulating the switch overvoltage according to the piecewise linear model, the arrester and the second phase-shifting transformer, and the arrester is connected to the second phase-shifting transformer, specifically: According to the electromagnetic transient program, the arrester and the second phase-shifting transformer are simulated for switching overvoltage in a piecewise linear model to obtain the arrester model; Wherein, the lightning arrester is connected to the power supply side and the load side of the second phase-shifting transformer.

5. A voltage over-limit suppression device, characterized in that: Includes acquisition module, construction module and control module; The acquisition module is used to obtain the electromagnetic transient model and the arrester model; The electromagnetic transient model is obtained by optimizing the initial electromagnetic transient model based on actual measurement data and the first phase-shifting transformer; the lightning arrester model is obtained by simulating the switch overvoltage based on the piecewise linear model, the lightning arrester and the second phase-shifting transformer, and the lightning arrester is connected to the second phase-shifting transformer; The construction module is used to combine the various parameters of the electromagnetic transient model and the arrester model to construct a virtual arrester and a virtual phase-shifting transformer; wherein the virtual phase-shifting transformer is used to suppress the simulated power frequency overvoltage; and the virtual arrester is used to suppress the simulated switch overvoltage; The control module is used to control the lightning arrester and the second phase-shifting transformer in the power system according to the equivalent circuit model.

6. The voltage over-limit suppression device according to claim 5, characterized in that: The electromagnetic transient model is obtained by optimizing the initial electromagnetic transient model based on actual measurement data and the first phase-shifting transformer, and is specifically: Obtain actual measurement data, transformer rated parameters, structural information and material properties; An initial electromagnetic transient model is constructed according to rated parameters, structural information and material properties of the transformer; According to the actual measurement data, simulation is performed on the initial electromagnetic transient model, and parameters of the initial electromagnetic transient model are corrected to obtain a first electromagnetic transient model; The first electromagnetic transient model is optimized according to the first phase-shifting transformer to obtain an electromagnetic transient model.

7. The voltage over-limit suppression device according to claim 6, characterized in that: The first electromagnetic transient model is optimized according to the phase-shifting transformer to obtain an electromagnetic transient model, which is specifically: According to the electromagnetic transient program, the phase-shifting transformer is simulated at different access positions of the line of the first electromagnetic transient model to obtain simulation results at different access positions; The different access positions include the line head end, the line and the line end; the simulation results of the different access positions include the power frequency overvoltage simulation results caused by asymmetric grounding faults and the power frequency overvoltage simulation results caused by load shedding; The first electromagnetic transient model is optimized according to the simulation results of the different access positions to obtain an electromagnetic transient model.

8. The voltage over-limit suppression device according to claim 5, characterized in that: The arrester model is obtained by simulating the switch overvoltage according to the piecewise linear model, the arrester and the second phase-shifting transformer, and the arrester is connected to the second phase-shifting transformer, specifically: According to the electromagnetic transient program, the arrester and the second phase-shifting transformer are simulated for switching overvoltage in a piecewise linear model to obtain the arrester model; Wherein, the lightning arrester is connected to the power supply side and the load side of the second phase-shifting transformer.

9. A computer-readable storage medium, characterized in that: The computer-readable storage medium includes a stored computer program, wherein when the computer program is executed, the device where the computer-readable storage medium is located is controlled to execute the voltage over-limit suppression method according to any one of claims 1 to 4.

10. A terminal device, characterized in that: The method comprises a processor, a memory, and a computer program stored in the memory and configured to be executed by the processor, wherein the processor implements the voltage over-limit suppression method according to any one of claims 1 to 4 when executing the computer program.

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