CN106529084A - Construction method for vacuum circuit breaker switch-on transient state simulation model - Google Patents

Abstract

The invention discloses a construction method of a vacuum circuit breaker closing transient simulation model based on PSCAD/EMTDC and C language interface technology. The circuit is equipped in the PSCAD/EMTDC environment, and a custom circuit breaker module is designed, and the PSCAD/EMTDC is used to Interface technology with C language to establish related power system simulation models. In order to simulate the transient process in the closing operation of the vacuum circuit breaker, the invention writes the control sub-function in the C language environment, controls the opening and closing of the circuit breaker model in the test circuit through the PSCAD/EMTDC and C language interface, and simulates the actual operation. The invention considers the pre-breakdown phenomenon in the transient process of closing operation and introduces the dielectric strength recovery characteristic and the high-frequency current arc-extinguishing characteristic curve, and divides the closing process of the vacuum circuit breaker into the first pre-breakdown and the second pre-strike Breakthrough, arc extinguishing recovery and physical closure, and set state judgment flags and state variables in the control logic to determine the transient state of the vacuum circuit breaker, so as to achieve accurate control of the circuit breaker model.

Description

A Construction Method of Closing Transient Simulation Model of Vacuum Circuit Breaker

technical field

The invention relates to the technical field of power system transient simulation, in particular to a method for constructing a vacuum circuit breaker closing transient simulation model based on PSCAD/EMTDC and C language interface technology.

Background technique

Vacuum circuit breakers have the advantages of strong arc extinguishing ability, high reliability, long service life, no fire hazard, suitable for frequent operation, etc., and are widely used in power systems and distribution networks. Different from the ideal state, in the actual operation of the power system, the vacuum circuit breaker often causes the system operation overvoltage due to the phenomenon of pre-breakdown and re-ignition during the opening and closing operation, and the phase-to-phase insulation breakdown of the circuit breaker in the substation, the busbar voltage, etc. Overvoltage accidents such as high-voltage fuse blown seriously threaten the parallel compensation device, endanger the service life of electrical equipment, endanger the insulation of power equipment, and affect the normal operation of the power system. The invention mainly performs simulation analysis on the closing transient state of the vacuum circuit breaker.

In the research and application of power systems, it is usually necessary to perform simulation first and then conduct subsequent experiments or applications. The present invention uses PSCAD/EMTDC, a commonly used simulation software for power systems, which provides a complete programmed and tested simulation model, allows users to build circuits, run simulations, and analyze results in a graphical manner, and can be used for most power system simulations . PSCAD/EMTDC is implemented on FORTRAN language, so FORTRAN has good embedded performance and high operating efficiency, but FORTRAN language has many format restrictions, and when users write large-scale programs, the compilation efficiency is often affected, and the program is given after errors. The error message is not clear, making debugging more difficult. C language has the advantages of rich functions, strong expressive ability, high efficiency of target program, good portability, etc. Therefore, the present invention chooses PSCAD/EMTDC and C language interface technology for simulation research.

The design of this simulation model, as the basis of the research in the field of power system, simulates the pre-breakdown phenomenon that occurs in the actual operation of the vacuum circuit breaker, and can simulate the closing of the circuit breaker in the power system operating state Problems such as overvoltage caused by transient state have certain research and engineering application value.

Contents of the invention

The present invention aims at the deficiencies in the traditional vacuum circuit breaker simulation method, refines the transient process of the vacuum circuit breaker, and proposes a vacuum circuit breaker closing transient simulation model based on PSCAD/EMTDC and C language interface technology The construction method realizes the simulation of the actual working condition of the vacuum circuit breaker model.

In order to achieve the above purpose, the technical solution provided by the present invention is: a method for constructing a transient simulation model for closing a vacuum circuit breaker, comprising the following steps:

1) set up the test circuit comprising power supply, line, circuit breaker and load under PSCAD/EMTDC environment, wherein, described circuit breaker part uses the structure of RLC circuit parallel connection ideal circuit breaker;

2) Build a custom module under the PSCAD/EMTDC environment, and create a C language file outside to write the control function, use the technology of PSCAD/EMTDC and C language interface, use the declaration code from the FORTRAN, digital simulation dynamic subroutine in the custom module DSDYN and digital simulation output subroutine DSOUT call the C language function in the external source file to realize the control of the opening and closing state of the circuit breaker;

3) Analyze the pre-breakdown phenomenon of the actual closing operation of the vacuum circuit breaker, load the voltage at both ends of the circuit breaker and the current data, and calculate the dielectric strength between the contact gaps and the high-frequency current arc-extinguishing ability;

4) Set the state variable of the circuit breaker according to the pre-breakdown process of the actual closing operation of the vacuum circuit breaker, and divide the multiple pre-breakdown into two stages: the first pre-breakdown and the second pre-breakdown, and set the first pre-breakdown Breakthrough, pre-breakdown again, arc extinguishing recovery state and circuit breaker physical closing four state judgment signs;

5) According to the four state judgment signs in step 4), determine the state of the vacuum circuit breaker at the moment, update the state variable of the vacuum circuit breaker, and set the circuit breaker opening and closing signal according to the state variable and output it to the simulation circuit to control the circuit breaker components The opening and closing status of the , the details are as follows:

First, judge the transient state of the vacuum circuit breaker according to the loaded data and state variables, set the corresponding state judgment flags to TRUE and other state judgment flags to FALSE, then update the state variables of the vacuum circuit breaker according to the four state judgment flags, and finally The opening and closing of the circuit breaker is controlled by the new state variable and related signals are output.

In step 1), the test circuit is a single-phase circuit, its line part is an RL series circuit, and its load part is an RLC parallel circuit.

In step 2), the technology of PSCAD/EMTDC and C language interface is used for simulation. Under the simulation environment of PSCAD/EMTDC, a custom module is established and the code is written in the script script of the custom module, and the external source file is called C language function, by using the public array STORI, STOPL, STOPF and self-defined array STOR provided by PSCAD/EMTDC, the data transmission from the PSCAD/EMTDC system to the external C language file is realized, and the data in the C language file is transferred through these arrays Transfer to PSCAD/EMTDC, so as to realize the data transfer between multiple simulation sub-modules of the vacuum circuit breaker model.

In step 3), based on the pre-breakdown transient process, in order to fully study the pre-breakdown process of the actual closing operation of the vacuum circuit breaker and write the control program, the recovery characteristics of the dielectric strength between the contact gaps of the vacuum circuit breaker, the high-frequency current The arc extinguishing characteristics were analyzed as follows:

a. Dielectric strength recovery characteristics

The recovery of the dielectric strength of the vacuum circuit breaker is a very important parameter for analyzing the transient process of the vacuum circuit breaker. From the moment when the contacts of the vacuum circuit breaker start to move, the dielectric strength between the contacts will increase with the distance between the contacts. The reduction starts from the maximum value; considering the fast closing speed of the contacts of the vacuum circuit breaker, it is decided to use a first-order polynomial to simplify the calculation of the dielectric strength U _b of the vacuum circuit breaker at different times:

U _b ＝U _blimit -A(tt _close )-B (1)

Among them, U _blimit is the ultimate dielectric strength of the vacuum circuit breaker, and its value is related to the dielectric material between the contacts of the circuit breaker; A is the closing speed of the contacts; t is the current simulation time; t _close is the contact of the circuit breaker Start action time; B is the dielectric strength constant;

b. High frequency current arc extinguishing characteristics

In the transient analysis of vacuum circuit breaker closing, the arc-extinguishing characteristic of current is a very important research characteristic. The critical value of the current change rate di/dt is used as the arc-extinguishing ability of high-frequency current, and is used as the basis for judging the arc-extinguishing state. Using a first-order polynomial representation:

di/dt=C(tt _close )+D (2)

Among them, C is the rising ratio of the high-frequency current arc-extinguishing ability; D is the high-frequency current arc-extinguishing ability when the contact starts to close.

In step 4), the closing stage of the vacuum circuit breaker is determined by the current and voltage data, dielectric strength recovery and high-frequency current arc extinguishing capability, and the state of the circuit breaker at the previous moment. Assign values to realize the control of the circuit breaker model and simulate the closing process in actual operation.

Compared with the prior art, the present invention has the following advantages and beneficial effects:

1, the emulation model that the present invention builds has used PSCAD/EMTDC and C language interface technology, establishes the vacuum circuit breaker model similar to " black box " model in PSCAD/EMTDC, combines PSCAD/EMTDC component storehouse element to be abundant, allows the user to use Run the simulation in the form of graphics and analyze the results, as well as the characteristics of efficient and flexible C language development, strong compatibility, convenient compilation errors, high program operation efficiency, etc., to better simulate the actual closing transient process.

2. The simulation model constructed by the present invention considers the phenomenon of repeated pre-breakdown of the vacuum circuit breaker during the actual closing process, and logically divides the closing transient state into the first pre-breakdown, the second pre-breakdown, and the shutdown. There are four stages of arc recovery and physical closure. Since the first pre-breakdown in the closing process of a vacuum circuit breaker is generally a power frequency breakdown, and the subsequent multiple pre-breakdowns are high-frequency breakdowns, the first pre-breakdown and subsequent pre-breakdown phenomena are different in characteristics There are obvious differences, so the present invention divides multiple pre-breakdowns into two stages: the first pre-breakdown and the second pre-breakdown; because the arc extinguishing process in the vacuum circuit breaker after the two pre-breakdown stages is similar , so this stage is called the arc-extinguishing recovery state; finally, the dielectric strength drops to zero, physical contact occurs between the contacts of the vacuum circuit breaker, and the vacuum circuit breaker enters the physical closing stage. The custom module determines the state of the vacuum circuit breaker and controls the closing of the ideal circuit breaker model based on the dielectric strength and high-frequency current arc extinguishing ability calculated by the relevant linear polynomial data such as the voltage at both ends of the circuit breaker and the passing current. Simulate the pre-breakdown phenomenon. Therefore, the simulation model constructed by the present invention can more accurately simulate the closing transient process of the vacuum circuit breaker under simulated working conditions.

Description of drawings

Fig. 1 is a flow chart of the present invention based on PSCAD/EMTDC and C language interface technology to build a vacuum circuit breaker closing transient simulation model.

Fig. 2 is a schematic diagram of a single-phase test circuit of the simulation model of the present invention.

Fig. 3 is a structural diagram of a self-defined module of the simulation model of the present invention.

Figure 4 is the simulation result of vacuum circuit breaker closing (0s‐0.04s): the current flowing through the vacuum circuit breaker.

Figure 5 is the simulation result of vacuum circuit breaker closing (0.0175s‐0.0189s): the current flowing through the vacuum circuit breaker.

Figure 6 is the simulation result of vacuum circuit breaker closing (0s‐0.04s): the voltage and dielectric strength at both ends of the vacuum circuit breaker.

Figure 7 is the simulation result of vacuum circuit breaker closing (0.0175s‐0.0189s): the voltage and dielectric strength at both ends of the vacuum circuit breaker.

detailed description

The present invention will be further described below in conjunction with specific embodiments.

As shown in Figure 1, the example construction of the transient simulation model of vacuum circuit breaker closing based on PSCAD/EMTDC and C language interface technology includes the following steps:

1) Establish a basic test circuit in the PSCAD/EMTDC environment, as shown in Figure 2. The test circuit consists of four parts: power supply, circuit breaker, line and load. Among them, the circuit breaker part is composed of a self-contained circuit breaker connected in parallel with an RLC branch circuit, the line part is simplified as an RL series circuit, and the load part is simplified as an RLC parallel circuit.

2) Build a custom module similar to the "black box" model in the PSCAD/EMTDC environment, and create a C language file externally to write the control function, use the technology of PSCAD/EMTDC and C language interface, use the declaration code from the custom module In FORTRAN, the digital simulation dynamic subroutine (DSDYN) and the digital simulation output subroutine (DSOUT) call the C language function in the external source file to realize the control of the opening and closing state of the circuit breaker. The custom module is shown in Figure 3.

3) Analyze the pre-breakdown phenomenon of the actual closing operation of the vacuum circuit breaker, load the voltage at both ends of the circuit breaker, the passing current and other data, and calculate the dielectric strength between the contact gaps and the high-frequency current arc extinguishing ability.

Based on the pre-breakdown transient process, in order to fully study the pre-breakdown process of the actual closing operation of the vacuum circuit breaker and write the control program, the present invention conducts research on the recovery characteristics of the dielectric strength between the contact gaps of the vacuum circuit breaker and the high-frequency current arc extinguishing characteristics. analyzed:

a. Dielectric strength recovery characteristics

The dielectric strength recovery of vacuum circuit breakers is a very important parameter for analyzing the transient process of vacuum circuit breakers. From the moment when the contacts of the vacuum circuit breaker start to act, the dielectric strength between the contacts will decrease from the maximum value as the distance between the contacts decreases. Considering that the contact closing speed of the vacuum circuit breaker is very fast, the present invention approximately uses a first-order polynomial to simplify the calculation of the dielectric strength U _b of the vacuum circuit breaker at different times:

U _b ＝U _blimit -A(tt _close )-B (1)

Among them, U _blimit is the ultimate dielectric strength of the vacuum circuit breaker, and its value is related to the dielectric material between the contacts of the circuit breaker; A is the closing speed of the contacts; t is the current simulation time; t _close is the contact of the circuit breaker Start action time; B is the dielectric strength constant;

b. High frequency current arc extinguishing characteristics

In the transient analysis of vacuum circuit breaker closing, the arc-extinguishing characteristic of current is a very important research characteristic. The critical value of the current change rate di/dt is used as the arc-extinguishing ability of high-frequency current, and is used as the basis for judging the arc-extinguishing state. It can be represented by a first-order polynomial:

di/dt=C(tt _close )+D (2)

Among them, C is the rising ratio of the high-frequency current arc-extinguishing ability; D is the high-frequency current arc-extinguishing ability when the contact starts to close.

4) Set the state variable of the circuit breaker according to the pre-breakdown process of the actual closing operation of the vacuum circuit breaker, and divide the multiple pre-breakdown into two stages: the first pre-breakdown and the second pre-breakdown, and set the first pre-breakdown There are four status judgment flags for breakdown, pre-breakdown again, arc-extinguishing recovery status and physical closing of the circuit breaker. According to relevant parameters, refer to state variables, and assign values to relevant state judgment flags. The closing stage of the vacuum circuit breaker is determined by basic data such as current and voltage, dielectric strength and high-frequency current arc-extinguishing capability, and the state of the circuit breaker at the previous moment. The controller model is used to simulate the closing process in actual operation.

5) According to the four state judgment signs in step 4), determine the state of the vacuum circuit breaker at the moment, update the state variable of the vacuum circuit breaker, and set the circuit breaker opening and closing signal according to the state variable and output it to the simulation circuit to control the circuit breaker components The opening and closing status of the , the details are as follows:

First, judge the transient state of the vacuum circuit breaker according to the loaded data and state variables, set the corresponding state judgment flags to TRUE and other state judgment flags to FALSE, then update the state variables of the vacuum circuit breaker according to the four state judgment flags, and finally The opening and closing of the circuit breaker is controlled by the new state variable and related signals are output.

In step 1), the vacuum circuit breaker model of the present invention is different from the ideal model in which the circuit breaker in the PSCAD/EMTDC component model library is only a switch state switching, but adopts the structure of the RLC circuit parallel connection ideal circuit breaker and simulates the vacuum circuit breaker The pre-breakdown phenomenon that occurs during the closing transient process can be used to observe and analyze the accurate model of the overvoltage condition of the line and load terminals. During the actual closing operation, the current flowing in the system will not change suddenly. According to the law of flux conservation, the inductive elements in the system will hinder the change of current and induce voltage in the circuit, and the faster the current changes, the faster the current changes. The induced voltage value will be larger. Therefore, in order to simulate the pre-breakdown phenomenon in the closing process and the overvoltage at the load end, a new RLC parallel branch is added in this simulation model. The simulation model of the vacuum circuit breaker simulates the transient processes such as pre-breakdown and high-frequency current arc extinguishing in the actual closing process. The test circuit used in this simulation model is a single-phase circuit. When the three-phase operation of the circuit breaker is fully synchronized, the process of analyzing the closing overvoltage can conduct a phase-separated study of the three-phase circuit, so the line system can be studied and analyzed as a single-phase circuit.

In step 2), use the technology of PSCAD/EMTDC and C language interface for simulation. Under the simulation environment of PSCAD/EMTDC, the invention establishes a self-defined module, writes codes in the script script of the self-defined module, and calls the C language function in the external source file. The present invention realizes the data transmission of the PSCAD/EMTDC system to the external C language file by using the public array STORI, STOPL, STOPF and the custom array STOR provided by PSCAD/EMTDC, and transmits the data in the C language file to PSCAD through these arrays /EMTDC, so as to realize the data transmission between multiple simulation sub-modules of the vacuum circuit breaker model.

According to the above steps to establish a simulation model, the voltage at both ends of the circuit breaker and the current flowing through the circuit breaker in the test circuit are shown in Figure 4-Figure 7. The closing signal time set by the vacuum circuit breaker model is 0.0145s. When the vacuum circuit breaker model detects the closing signal, its contacts start to move, the distance between the contacts gradually decreases, and the dielectric strength in the gap decreases accordingly. Small. In this test circuit, the voltage across the vacuum circuit breaker changes sinusoidally with time. When the voltage value at both ends of the circuit breaker is greater than the dielectric strength, the insulation gap will be broken down by the arc and the pre-breakdown phenomenon will occur. As shown in the figure, the time for the first pre-breakdown in this example is 0.0176s, followed by multiple pre-breakdowns, until the vacuum circuit breaker is completely closed at 0.0188s, and the closing is successful. The simulation results of this test circuit can show that the vacuum circuit breaker closing transient simulation model based on PSCAD/EMTDC and C language interface technology can better simulate the multiple pre-breakdown phenomena in actual operation, and has a simulation effect that is more in line with actual working conditions , suitable for other engineering applications.

The above-described embodiments are only preferred embodiments of the present invention, and are not intended to limit the scope of the present invention. Therefore, all changes made according to the shape and principle of the present invention should be covered within the protection scope of the present invention.

Claims (5)

1. a kind of construction method of vacuum circuit breaker combined floodgate Transient simulation model, it is characterised in that comprise the following steps：

1) test circuit comprising power supply, circuit, chopper and load is set up under PSCAD/EMTDC environment, it is wherein, described disconnected Structure of the road device part using rlc circuit ideal chopper in parallel；

2) custom block is built under PSCAD/EMTDC environment, and set up C language file edit control function in outside, profit With PSCAD/EMTDC and the technology of C language interface, using statement code by FORTRAN, Digital Simulation dynamic in custom block Subprogram DSDYN and numeral simulation data subprogram DSOUT call the C language function in external source file, realize that chopper is opened The control of conjunction state；

3) analyze the prebreakdown phenomenon of the actual closing operation of vacuum circuit breaker, loading chopper both end voltage, by current data, Calculate dielectric strength between contact gap to recover and high frequency electric arc-rupturing capacity；

4) circuit-breaker status variable is arranged according to the Preliminary breakdown process of the actual closed procedure of vacuum circuit breaker, and by multiple prebreakdown Divide into first time prebreakdown and two stages of prebreakdown again, first time prebreakdown is set, prebreakdown, blow-out recover shape again State and chopper physics four condition adjudgement marks of combined floodgate；

5) according to step 4) in four condition adjudgement marks determine vacuum circuit breaker status this moment, update vacuum circuit breaker State variable, and chopper folding signal is set according to state variable and opening for control circuit breaker element is exported in artificial circuit Conjunction state, it is specific as follows：

First, the transient period according to residing for loading data and state variable judge vacuum circuit breaker, by corresponding statess judgement symbol Be set to TRUE and other condition adjudgements are masked as FALSE, then vacuum circuit breaker shapes are updated according to four condition adjudgement marks State variable, finally by folding the output correlation signal of new state variable control chopper.

2. the construction method of a kind of vacuum circuit breaker combined floodgate Transient simulation model according to claim 1, it is characterised in that： In step 1) in, the test circuit is single-phase circuit, and its circuit pack is RL series circuits, and its loading section is that RLC is in parallel Circuit.

3. the construction method of a kind of vacuum circuit breaker combined floodgate Transient simulation model according to claim 1, it is characterised in that： In step 2) in, use PSCAD/EMTDC and the technology of C language interface to be emulated, in the simulated environment of PSCAD/EMTDC Under, set up custom block and code is write in the script Script of custom block, call the C language in external source file Function, public array STORI, STOPL provided by using PSCAD/EMTDC, STOPF and self-defined array STOR are realized Data transfer of the PSCAD/EMTDC systems to outside C language file, and the data in C language file are passed by these arrays PSCAD/EMTDC is sent to, so as to realize the data transfer between multiple emulation submodules of vacuum circuit breaker model.

4. the construction method of a kind of vacuum circuit breaker combined floodgate Transient simulation model according to claim 1, it is characterised in that： In step 3) in, based on prebreakdown transient process, it is fully to study the Preliminary breakdown process of the actual closing operation of vacuum circuit breaker simultaneously Control program is write, the dielectric strength recovery characteristics in contacts for vacuum-break switches gap, high frequency electric blow-out characteristic are carried out It is following to analyze：

A. dielectric strength recovery characteristics

The dielectric strength of vacuum circuit breaker is recovered to be a critically important parameter for analyzing vacuum circuit breaker transient process, from vacuum The contact of chopper start action moment rise, the dielectric strength between contact by with contact pitch from reduction from the beginning of maximum Reduce；It is fast in view of the contact closure speed of vacuum circuit breaker, when decision carries out simplifying with a rank multinomial calculating difference Carve dielectric strength U of vacuum circuit breaker_b：

U_b=U_blimit-A(t-t_close)-B (1)

Wherein, U_blimitIt is vacuum circuit breaker limit dielectric strength, the dielectric material between its numerical values recited and contact of breaker has Close；Closing speeds of the A for contact；T is the current emulation moment；t_closeStart movement time for contact of breaker；B is dielectric strength Constant；

B. high frequency electric blow-out characteristic

In vacuum circuit breaker combined floodgate transient analysis, the blow-out characteristic of electric current is a highly important research characteristic, and electric current becomes The marginal value of rate di/dt is also adopted by a single order multinomial as high frequency electric arc-rupturing capacity as blow-out condition adjudgement foundation Formula is represented:

Di/dt=C (t-t_close)+D (2)

Wherein, C is the rising scale of high frequency electric arc-rupturing capacity；High frequency electric arc-rupturing capacity when D starts to close a floodgate for contact.

5. the construction method of a kind of vacuum circuit breaker combined floodgate Transient simulation model according to claim 1, it is characterised in that： In step 4) in, the combined floodgate stage residing for vacuum circuit breaker is recovered and high frequency electric blow-out by current and voltage data, dielectric strength In ability and chopper, status are together decided on a moment, by condition adjudgement mark and state variable assignment, realizing Control to chopper model, simulates the making process in practical operation.