A method for constructing a low-frequency phase-selective circuit breaker opening and restriking arc transient model

Abstract

The present application relates to the technical field of low-frequency phase-selecting circuit breaker, and particularly relates to a method for constructing a tripping arc-reburning transient model of a low-frequency phase-selecting circuit breaker, comprising the following steps: S1, simulation model building: building a simulation model of a self-defined low-frequency phase-selecting circuit breaker; S2, fault type analysis and tripping action determination: analyzing multiple fault types; S3, arc-reburning transient process analysis: analyzing the arc-reburning transient process of the low-frequency phase-selecting circuit breaker during actual tripping; S4, voltage and current constraint condition setting: realizing simulation of arc-reburning; S5, opening and closing logic control module design: designing an opening and closing logic control module; S6, FORTRAN script writing and function realization: realizing the function of tripping and opening of the self-defined low-frequency phase-selecting circuit breaker; S7, simulation circuit building and verification: building a simulation circuit. The present application can effectively avoid the harm caused by arc-reburning by accurately simulating the arc-burning characteristics of the circuit breaker under a low-frequency environment, thereby improving the reliability and safety of the low-frequency phase-selecting circuit breaker.

Description

TECHNICAL FIELD

[0001] The application relates to the technical field of low-frequency phase selection circuit breakers, in particular to a construction method of a low-frequency phase selection circuit breaker tripping arc reignition transient model. BACKGROUND

[0002] In a power system, low-frequency phase selection circuit breakers are widely used in power grid fault handling to ensure system stability and safety. The main function of the low-frequency phase selection circuit breaker is to quickly trip and effectively isolate the fault section when a short circuit or ground fault occurs, preventing the fault from further expanding. With the increasing complexity of the power system, the performance requirements of the low-frequency phase selection circuit breaker under high voltage and complex environmental conditions are increasing. In particular, under low-frequency transmission and high-voltage environments, the performance and arc characteristics of the circuit breaker directly affect the reliability and safety of the power system.

[0003] Existing low-frequency phase selection circuit breakers usually rely on standard electrical models for current and voltage control, but these technologies have many shortcomings in practical applications. For example, the circuit breaker control system in the prior art cannot effectively simulate the arc characteristics under low-frequency environments, which can cause arc reignition during the tripping process of the circuit breaker, increasing the risk of system failure. In addition, the existing methods lack dynamic response capability for different fault types, cannot automatically adjust the tripping strategy according to the fault type, and lack precise modeling of arc extinction capability during the tripping process, thereby affecting the response speed and stability of the circuit breaker.

[0004] The purpose of the present application is to provide a construction method of a low-frequency phase selection circuit breaker tripping arc reignition transient model, which can dynamically adjust the tripping strategy according to different fault types, has good adaptability and universality, and is suitable for different voltage levels and arc extinction medium conditions, significantly improving the stability and operating efficiency of the power system. SUMMARY

[0005] The application provides a construction method of a low-frequency phase selection circuit breaker tripping arc reignition transient model.

[0006] A construction method of a low-frequency phase selection circuit breaker tripping arc reignition transient model, comprising the following steps:

[0007] S1, simulation model building: building a self-defined low-frequency phase selection circuit breaker simulation model in a PSCAD / EMTDC simulation environment, the self-defined low-frequency phase selection circuit breaker simulation model comprising a first branch and a second branch;

[0008] S2, fault type analysis and breaking action determination: analyze various fault types of the flexible low-frequency power transmission system, including three-phase short-circuit fault, two-phase short-circuit fault, two-phase ground short-circuit fault, and single-phase ground short-circuit fault, determine the breaking action of the low-frequency phase selection circuit breaker according to the fault type, including A-phase action, B-phase action, and C-phase action, and set the corresponding control signal;

[0009] S3, analysis of the transient process of the re-arc: analyze the transient process of the re-arc when the low-frequency phase selection circuit breaker is actually broken, including starting breaking, low-frequency arc, low-frequency current cutoff, transient recovery voltage generation, high-frequency arc breakdown, high-frequency current cutoff, and complete arc extinction, and according to the current and voltage characteristics of the transient process of the re-arc, divide it into multiple stages, including starting breaking to low-frequency current cutoff, transient recovery voltage generation, high-frequency current breakdown, and arc extinction;

[0010] S4, voltage and current constraint condition setting: set different voltage and current constraint conditions for each stage of the circuit breaker breaking, and control the opening and closing of the ideal circuit breaker in the second branch of the low-frequency phase selection circuit breaker according to the voltage and current constraint conditions of each stage to realize the simulation of arc re-ignition;

[0011] S5, opening and closing logic control module design: design the opening and closing logic control module of the self-defined low-frequency phase selection circuit breaker re-arc model in the PSCAD / EMTDC simulation environment, which includes external input parameters, internal output parameters, corresponding circuit breaker internal parameters, and parameter setting interface;

[0012] S6, FORTRAN script writing and function implementation: in the script Script of the opening and closing logic control module, write code through FORTRAN language to realize the function of self-defined low-frequency phase selection circuit breaker breaking and closing;

[0013] S7, simulation circuit building and verification: build a simulation circuit to test and verify whether the low-frequency phase selection circuit breaker model can reproduce the arc re-ignition phenomenon in the actual breaking process, realize the function of phase selection breaking, and effectively apply in the flexible low-frequency system.

[0014] Optionally, the first branch is composed of a resistor R, an inductor L, and a capacitor C in series, and the second branch is composed of a single ideal circuit breaker.

[0015] Optionally, the fault type in S2 is determined by analyzing the low-frequency phase selection circuit breaker's two-side voltage U n to ground and the current I line of the circuit in which the low-frequency phase selection circuit breaker is located, and the phase selection function of the circuit breaker is realized by controlling the fault type control signal and the action belief signal.

[0016] Optionally, the input of the opening and closing logic control module of the low-frequency phase-selecting circuit breaker re-arc model in S5 is the voltage U across the low-frequency phase-selecting circuit breaker brk and the current I flowing through the low-frequency phase-selecting circuit breaker brk , and the output is the opening and closing signal of the ideal circuit breaker in the second branch of the low-frequency phase-selecting circuit breaker.

[0017] Optionally, the corresponding internal parameters of the circuit breaker in S5 include the opening time, the low-frequency current interruption and the high-frequency current interruption, the dielectric insulation recovery capability curve, the high-frequency arc extinction capability curve, and the initial state of the low-frequency phase-selecting circuit breaker.

[0018] Optionally, the corresponding internal parameters of the circuit breaker are obtained by analyzing and processing the interrupting current, the dielectric insulation recovery capability, and the high-frequency arc extinction capability.

[0019] Optionally, the interrupting current includes the power frequency interrupting current I lc , the high-frequency interrupting current I hc , the average interrupting current, the combination of the power frequency interrupting current and the high-frequency interrupting current, representing the average level of the current cut off by the circuit breaker during the opening process, and the average interrupting current is represented as:

[0020]

[0021] wherein f is the angular frequency of the current, i is the amplitude of the current, and a and b are parameters determined by the contact material.

[0022] Optionally, the dielectric insulation recovery capability is represented as:

[0023] U=A(t-t0)+B

[0024] wherein U represents the dielectric insulation strength, t is the time, t0 is the time when the contacts start to separate, A is the rising rate of the dielectric insulation recovery strength, and B is the transient recovery voltage of the SF6 low-frequency circuit breaker before the current zero.

[0025] Optionally, the high-frequency arc extinction capability is represented as:

[0026] di / / dt=C(t-t0)+D

[0027] wherein di / dt is the high-frequency arc extinction capability, C is the rising rate of the high-frequency arc extinction capability, and D is the rising rate of the high-frequency arc extinction capability before the contacts separate.

[0028] The beneficial effects of the present application are:

[0029] The present application can effectively avoid the harm caused by arc re-ignition by accurately simulating the arc characteristics of the circuit breaker under low-frequency environment, thereby improving the reliability and safety of the low-frequency phase-selecting circuit breaker.

[0030] The low-frequency phase-selecting circuit breaker of the application can respond to different fault types and accurately control the tripping action, has good adaptability and universality, is suitable for different voltage levels and arc-extinguishing medium conditions, and improves the stability and operation efficiency of the power system. BRIEF DESCRIPTION OF DRAWINGS

[0031] In order to more clearly illustrate the technical solutions in the application or the prior art, the drawings needed to be used in the embodiments or the prior art description will be briefly introduced. Obviously, the drawings in the following description are only a part of the application, and other drawings can be obtained by those skilled in the art without creative effort on the basis of these drawings.

[0032] Figure 1 The figure is a simulation model schematic diagram of the low-frequency phase-selecting circuit breaker of the embodiment of the application.

[0033] Figure 2 The figure is a logic flow schematic diagram of the post-fault phase-selection judgment process of the embodiment of the application.

[0034] Figure 3 The figure is an opening and closing logic control flow schematic diagram of the low-frequency phase-selecting circuit breaker re-arc transient process of the embodiment of the application.

[0035] Figure 4 The figure is a circuit breaker internal parameter setting interface schematic diagram of the embodiment of the application.

[0036] Figure 5 The figure is a three-phase current flowing through the low-frequency phase-selecting circuit breaker of the embodiment of the application.

[0037] Figure 6 The figure is a low-frequency phase-selecting circuit breaker two-end voltage schematic diagram of the embodiment of the application.

[0038] Figure 7 The figure is a low-frequency phase-selecting circuit breaker opening and closing signal schematic diagram of the embodiment of the application.

[0039] Figure 8 The figure is a low-frequency phase-selecting circuit breaker A-phase high-frequency arc current schematic diagram of the embodiment of the application.

[0040] Figure 9 The figure is a low-frequency phase-selecting circuit breaker A-phase transient recovery voltage schematic diagram of the embodiment of the application.

[0041] Figure 10 The figure is a low-frequency phase-selecting circuit breaker A-phase re-arc opening end signal schematic diagram of the embodiment of the application. DETAILED DESCRIPTION

[0042] The application will be described in greater detail in connection with the accompanying drawings and specific embodiments. It should be noted that the embodiments described below are the best modes, preferred modes, and that other alternative modes can be used by those skilled in the art without departing from the application. The drawings are not intended to be detailed illustrations of the application, but are merely included herein as an aid to understanding the application.

[0043] It should be noted that the use of "one embodiment," "an embodiment," "certain embodiments," "certain embodiments," "some embodiments," and the like, in the specification, does not mean that the same feature, structure, or characteristic is in each and every embodiment. Rather, it means that the feature, structure, or characteristic is in at least one embodiment. In addition, it should be understood that the described features, structures, or characteristics can be combined in any suitable manner in other embodiments.

[0044] In general, the terminology used can be understood at least in part from a consideration of the context in which the term is used. For example, the term "one or more" as used herein, depending at least in part upon the context in which the term is used, can be used to describe any feature, structure, or characteristic in a singular sense or can be used to describe combinations of features, structures, or characteristics in a plural sense. Similarly, the term "based on" can be understood as not necessarily intended to convey an exclusive set of factors, but rather can allow for existence of additional factors not expressly described.

[0045] As shown in Figures 1-10 , a method for constructing a low-frequency phase-selective circuit breaker opening and reignition transient model, comprising the following steps:

[0046] Step 1, build a custom low-frequency phase-selective circuit breaker simulation model in the PSCAD / EMTDC simulation environment. The model consists of two branches: Branch 1 is composed of a resistor R, an inductor L, and a capacitor C in series. Its function is to avoid the sudden change of energy storage element voltage and current on both sides of the circuit caused by the opening and closing operation of the low-frequency phase-selective circuit breaker, which can cause meaningless numerical oscillation phenomenon, and to simulate the stray parameters of the circuit breaker. Branch 2 is composed of a single ideal circuit breaker, which controls the on-off of the line. Its control signal is given by the circuit breaker opening and closing logic control module, as shown in Figure 1 .

[0047] Step 2, analyze four typical fault types of flexible low-frequency power transmission system: three-phase short-circuit fault, two-phase short-circuit fault, two-phase ground short-circuit fault, and single-phase ground short-circuit fault. According to the fault type, determine the opening action of the three low-frequency phase-selective circuit breakers: A-phase action, B-phase action, and C-phase action. Set the corresponding control signal as the fault type control signal and the action belief signal, and the judgment process is as shown in Figure 2 .

[0048] Step 3, analyze the low-frequency arc-reburning transient process of the actual breaking of the low-frequency phase-selecting circuit breaker, which is composed of 7 sub-processes: starting breaking, low-frequency arc, low-frequency current cutoff, transient recovery voltage generation, high-frequency arc breakdown, high-frequency current cutoff, and complete arc extinction. According to the current and voltage characteristics of each sub-process, it is divided into 4 stages: starting breaking to low-frequency current cutoff, transient recovery voltage generation, high-frequency current breakdown, and arc extinction.

[0049] Step 4, set different voltage and current constraints for the 4 stages of the circuit breaker breaking, and control the opening and closing of the ideal circuit breaker in the low-frequency phase-selecting circuit breaker branch 2 according to the constraints of each stage to simulate arc reburning. The brief flowchart is as follows Figure 3 .

[0050] Step 5, define the opening and closing logic control module of the low-frequency phase-selecting circuit breaker reburning arc model in the PSCAD / EMTDC simulation environment, including 4 external input parameters and 1 internal output parameter, as well as the corresponding internal parameters of the circuit breaker, and set up the parameter setting interface, as follows Figure 4 .

[0051] Step 6, in the script Script of the opening and closing logic control module, write the code through FORTRAN language to realize the function of the above-mentioned self-defined low-frequency phase-selecting circuit breaker breaking and closing.

[0052] Step 7, on the basis of completing steps 1 to 6, build a complete simulation circuit to test and verify whether the low-frequency phase-selecting circuit breaker model can reproduce the arc reburning phenomenon in the actual breaking process, realize the function of phase-selecting breaking, and effectively apply in the flexible low-frequency system, and verify the rationality and effectiveness of the built model.

[0053] In step 2, the fault type occurring on the low-frequency line where the low-frequency phase-selecting circuit breaker is located is determined according to the voltage U n between the two terminals of the low-frequency phase-selecting circuit breaker to ground after the transient process and the current I line of the line where the low-frequency phase-selecting circuit breaker is located. Through the control of the fault type control signal and the action belief signal, the phase-selecting function of the circuit breaker is realized.

[0054] In step 5, the input of the opening and closing logic control module of the low-frequency phase-selecting circuit breaker reburning arc transient model is the voltage U brk between the two terminals of the low-frequency phase-selecting circuit breaker and the current I brk flowing through the low-frequency phase-selecting circuit breaker, and the output is the opening and closing signal of the ideal circuit breaker in the low-frequency phase-selecting circuit breaker branch 2.

[0055] In step 5, the internal parameters mainly include the breaking moment, low-frequency cutoff and high-frequency cutoff, dielectric insulation recovery capability curve, high-frequency arc extinction capability curve, and low-frequency phase selection circuit breaker initial state. The above parameters can be obtained by analyzing and processing the field test data and circuit breaker equipment parameters, and the main parameters are as follows:

[0056] a. Cut-off current: power frequency cut-off current I lc , high-frequency cut-off current I hc , average cut-off current calculation formula:

[0057]

[0058] Where f is the angular frequency of the current, i is the amplitude of the current, and a and β are parameters determined by the contact material.

[0059] b. Dielectric insulation recovery capability calculation formula:

[0060] U = A(t-t0) + B;

[0061] Where U represents the dielectric insulation strength, t is the time, t0 is the moment when the contact starts to separate, A is the rising rate of dielectric insulation recovery strength, and B is the transient recovery voltage of SF6 low-frequency circuit breaker before current zero.

[0062] c. High-frequency arc extinction capability calculation formula:

[0063] di / dt = C(t-t0) + D;

[0064] Where di / dt is the high-frequency arc extinction capability, C is the rising rate of high-frequency arc extinction capability, and D is the rising rate of high-frequency arc extinction capability before contact separation.

[0065] Model verification:

[0066] Taking a low-frequency phase selection circuit breaker under 220 kV voltage level as an example, a test circuit is built to analyze the voltage and current at both ends of the low-frequency phase selection circuit breaker during breaking, and to verify the rationality and effectiveness of the proposed model.

[0067] The voltage at both ends of the low-frequency phase selection circuit breaker in the test circuit, the current flowing through the low-frequency phase selection circuit breaker, and the low-frequency phase selection circuit breaker's reignition are as follows Figures 5 to 9The low-frequency phase selection circuit breaker model is set to have a breaking time of 0.04 s. When the low-frequency phase selection circuit breaker receives a breaking signal, the circuit breaker fault judgment module starts to operate to determine the phase selection operation. The A-phase low-frequency current first crosses zero, and the A-phase contact starts to separate, and the B-phase and C-phase contacts act later. When the current flowing through the low-frequency phase selection circuit breaker first falls below the low-frequency cut-off current, the transient recovery voltage across the low-frequency phase selection circuit breaker starts to gradually increase. When the transient recovery voltage is greater than the dielectric strength at the moment, the insulation gap will be broken by the arc, resulting in the occurrence of the restriking phenomenon. The time of the first restriking is 0.0412 s. After that, with the change of the dielectric strength between the transient recovery voltage across the low-frequency phase selection circuit breaker and the contact gap, the low-frequency phase selection circuit breaker has multiple breakdowns inside, and the inter-phase restriking has mutual influences. Until 0.11762 s, the contact gap of the low-frequency phase selection circuit breaker is large enough to be broken, and the arcs of the phases are extinguished in sequence, and the breaking is successful.

[0068] Based on the above analysis of the simulation results of the test circuit, it is concluded that the low-frequency phase selection circuit breaker breaking restriking arc transient simulation model can well simulate the restriking phenomenon in the transient process of the low-frequency circuit breaker breaking operation, and can accurately reflect the coupling phenomenon when the three-phase circuit breaker selects the phase.

[0069] The present application encompasses any substitutions, modifications, equivalent methods and schemes made on the essence and scope of the present application. In order for the public to have a thorough understanding of the present application, specific details are described in the following preferred embodiments of the present application, and the present application can also be fully understood without the description of these details to those skilled in the art. In addition, in order to avoid unnecessary confusion to the essence of the present application, well-known methods, processes, procedures, elements and circuits, etc. are not described in detail.

[0070] The above is only the preferred embodiment of the present application, and it should be pointed out that for ordinary skilled in the art, without departing from the principles of the present application, a number of improvements and refinements can also be made, and these improvements and refinements should be considered as the protection scope of the present application.

Claims

1. A method for constructing a transient model of a low-frequency phase-selective circuit breaker's tripping and reignition arc, characterized in that, Includes the following steps: S1. Simulation Model Building: A custom low-frequency phase-selection circuit breaker simulation model is built in the PSCAD / EMTDC simulation environment. The custom low-frequency phase-selection circuit breaker simulation model includes the first branch and the second branch. S2, Fault Type Analysis and Tripping Action Determination: Analyze various fault types in the flexible low-frequency transmission system, including three-phase short-circuit faults, two-phase short-circuit faults, two-phase ground faults, and single-phase ground faults. Determine the tripping action of the low-frequency phase-selective circuit breaker based on the fault type, including A-phase action, B-phase action, and C-phase action, and set the corresponding control signals. S3, Reignition Transient Process Analysis: This analysis examines the reignition transient process during the actual opening of the low-frequency phase-selective circuit breaker, including the start of opening, low-frequency arcing, low-frequency current interruption, transient recovery voltage generation, high-frequency arc breakdown, high-frequency current interruption, and complete arc extinction. Based on the current and voltage characteristics of the reignition transient process, it is divided into multiple stages, including the period from the start of opening to low-frequency current interruption, transient recovery voltage generation, high-frequency current breakdown, and arc extinction. S4, Voltage and Current Constraint Settings: Set different voltage and current constraints for each stage of circuit breaker tripping, and control the opening and closing of the ideal circuit breaker in the second branch of the low-frequency phase-selection circuit breaker according to the voltage and current constraints for each stage to simulate arc reignition. S5, Design of Opening and Closing Logic Control Module: Design an opening and closing logic control module for a custom low-frequency phase-selection circuit breaker re-ignition arc model in the PSCAD / EMTDC simulation environment. The opening and closing logic control module includes external input parameters, internal output parameters and corresponding circuit breaker internal parameters, and parameter setting interface. S6, FORTRAN script writing and function implementation: In the script of the opening and closing logic control module, code is written in FORTRAN language to realize the opening and closing function of the custom low-frequency phase selection circuit breaker; S7, Simulation Circuit Construction and Verification: Build a simulation circuit, test and verify whether the low-frequency phase-selective circuit breaker model can reproduce the arc reignition phenomenon in the actual opening process, realize the phase-selective breaking function, and be applied in a flexible low-frequency system. The fault type in S2 is determined by analyzing the terminal-to-ground voltage U on both sides of the low-frequency phase-selective circuit breaker during the transient process after the fault. n The current I in the line where the low-frequency phase-selective circuit breaker is located line The circuit breaker's phase selection function is achieved by controlling the fault type control signal and the operating phase signal.

2. The method for constructing a transient model of a low-frequency phase-selective circuit breaker's tripping and reignition arc as described in claim 1, characterized in that, The first branch consists of a resistor R, an inductor L, and a capacitor C connected in series, while the second branch consists of a single ideal circuit breaker.

3. The method for constructing a transient model of a low-frequency phase-selective circuit breaker's tripping and reignition arc as described in claim 2, characterized in that, The input to the opening and closing logic control module of the low-frequency phase-selective circuit breaker reignition model in S5 is the voltage U across the low-frequency phase-selective circuit breaker. brk and the current I flowing through the low-frequency phase-selective circuit breaker brk The output is the opening and closing signal of the ideal circuit breaker in the second branch of the low-frequency phase-selective circuit breaker.

4. The method for constructing a transient model of a low-frequency phase-selective circuit breaker's tripping and reignition arc as described in claim 3, characterized in that, The corresponding internal parameters of the circuit breaker in S5 include the opening time, low-frequency current cutting and high-frequency current cutting, dielectric insulation recovery capability curve, high-frequency arc extinguishing capability curve, and initial state of the low-frequency phase-selective circuit breaker.

5. The method for constructing a transient model of a low-frequency phase-selective circuit breaker's tripping and reignition arc as described in claim 4, characterized in that, The corresponding internal parameters of the circuit breaker are obtained by analyzing and processing the interruption current, dielectric insulation recovery capability, and high-frequency arc extinguishing capability.

6. The method for constructing a transient model of a low-frequency phase-selective circuit breaker's tripping and reignition arc as described in claim 5, characterized in that, The cutoff current includes the power frequency cutoff current I. lc High-frequency interruption current I hc By calculating the average breaking current, combining the power frequency breaking current and the high frequency breaking current, it represents the average level of current interrupted by the circuit breaker during the opening process. The average breaking current is expressed as: ； in, It is the angular frequency of the current. It is the amplitude of the current. , These parameters are determined by the contact material.

7. The method for constructing a transient model of a low-frequency phase-selective circuit breaker's tripping and reignition arc as described in claim 6, characterized in that, The dielectric insulation recovery capability is expressed as follows: ； in, Characterizing the dielectric insulation strength, For time, The moment when the contacts begin to separate. The rate of increase of the dielectric insulation recovery strength. This is the transient recovery voltage of the SF6 low-frequency circuit breaker before the current crosses zero.

8. The method for constructing a transient model of a low-frequency phase-selective circuit breaker's tripping and reignition arc as described in claim 7, characterized in that, The high-frequency arc extinguishing capability is expressed as: ； in, C is the high-frequency arc extinguishing capability, D is the rate of increase of the high-frequency arc extinguishing capability before contact separation.

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