CN112949062B - Short-circuit protection analysis method and short-circuit test method for urban rail transit traction system - Google Patents
Short-circuit protection analysis method and short-circuit test method for urban rail transit traction system Download PDFInfo
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Abstract
The invention provides a short-circuit protection analysis method and a short-circuit test method for an urban rail transit traction system. The analysis method comprises the following steps: according to a main circuit of a system in short circuit fault, an equivalent circuit model is built under a simulation environment; setting different short-circuit working conditions according to parameters influencing short-circuit current during short-circuit fault; determining the selection of electrical measurement quantity and the position of a measurement point according to the action characteristics of each stage of protection device; after the parameters of the equivalent circuit model are set according to the short-circuit working condition, simulating through the equivalent circuit model according to the electric parameters of the traction power supply system and the short-circuit working condition parameters to obtain a short-circuit current waveform; and calculating the action time of each stage of protection according to the short-circuit current waveform and the setting value of the protection device, and outputting a simulation result with a protection action time sequence. The invention can simulate the short-circuit fault of each working condition under the simulation and test environment, measure the short-circuit current, calculate each protection action time sequence and verify the reasonability of the design of the traction system.
Description
Technical Field
The invention belongs to the technical field of rail transit traction power supply, and particularly relates to a short-circuit protection analysis method and a short-circuit test method for an urban rail transit traction system.
Background
The most common fault in the urban rail transit traction power supply system is a direct-current side short-circuit fault, when the short-circuit fault occurs, the fault can be removed by configuring a relay protection device, and the train operation is not influenced to the greatest extent. The urban rail transit system relay protection is divided into a network side and vehicle-mounted protection, the network side protection mainly comprises circuit breakers and micro-machine comprehensive protection which are installed in traction substations, and the vehicle-mounted protection generally comprises vehicle-mounted high-speed circuit breakers and fuses.
However, the relay protection and the vehicle-mounted protection device of the conventional traction power supply system are designed independently, so that the override action of the protection device, namely the short-circuit fault on the train, is easily caused, and the vehicle-mounted protection device is removed, but actually the network side protection device acts simultaneously, so that the fault range is expanded to a power transmission line and a traction substation by the vehicle, and the normal power supply and the normal operation of other vehicles on the section of the line are influenced. Therefore, to realize the safety and reliability of the urban rail transit traction power supply system and the train traction system, the reliability and sensitivity of the relay protection must be ensured. The modeling simulation analysis of the short-circuit fault of the traction power supply system and the train traction system is a basic condition which is necessary for the equipment model selection and the relay protection setting of the traction system.
At present, most of researches on urban rail short-circuit faults are carried out on a power supply system side, and a system analysis, simulation and test method on a traction system side is lacked. Therefore, it is urgently needed to provide a short-circuit fault protection modeling simulation and short-circuit test method, which studies short-circuit fault protection by taking a traction system as a power utilization side, jointly analyzes a power supply side and the power utilization side, simulates short-circuit current when a vehicle has short-circuit fault under different working conditions in simulation and test environments, calculates the action time sequence of a vehicle side protection device and a network side protection device according to the short-circuit fault protection, and tests the rationality of the design selection of the short-circuit protection device of the urban rail traction system and the rationality of a power supply system protection setting value, thereby ensuring the safety and the reliability of a rail transit traction power supply system.
Disclosure of Invention
The invention provides a short-circuit protection analysis method and a short-circuit test method for an urban rail transit traction system, which aim at the technical problems, and the method comprises the steps of firstly simulating vehicle short-circuit faults of various working conditions in a simulation environment, measuring short-circuit current, calculating the action time sequence of protection devices of the urban rail traction system and a power supply system according to the short-circuit faults, and verifying the effectiveness and the accuracy of the action of the protection devices; and then, carrying out a short-circuit test by referring to the simulation result in a test environment, verifying the simulation result, checking the accuracy of the simulation result, completing a type test required by a relevant standard, verifying the reasonability of the design of the traction system and the reasonability of the relay protection setting of the traction power supply system, and carrying out auxiliary analysis if a fault occurs in the running period of the line.
In order to achieve the purpose, the invention provides a short-circuit protection analysis method for an urban rail transit traction system, which comprises the following steps:
short-circuit fault modeling step: according to a main circuit of a system in short circuit fault, an equivalent circuit model is built under a simulation environment;
short circuit working condition setting: setting different short-circuit working conditions according to parameters influencing short-circuit current during short-circuit fault;
a measurement setting step: determining the selection of electrical measurement quantity and the position of a measurement point according to the action characteristics of each level of protection devices of power supply system side protection and vehicle-mounted protection;
short circuit simulation analysis step: after the parameters of the equivalent circuit model are set according to the short-circuit working condition, simulating through the equivalent circuit model according to the electric parameters of the traction power supply system and the short-circuit working condition parameters to obtain a short-circuit current waveform;
an action time sequence calculation step: calculating the action time of each stage of protection according to the short-circuit current waveform and the setting value of the protection device;
and (3) simulation result output step: and outputting a simulation result with a protective action time sequence according to the short-circuit current waveform and the action time.
Preferably, the equivalent circuit model includes two traction substation models and a line equivalent impedance model and a vehicle model between the two traction substation models.
Preferably, the short-circuit fault modeling step includes:
a traction substation model building step: the traction substation model comprises a system equivalent power supply, a traction transformer, a rectifier and cable equivalent impedance;
line equivalent impedance model: the system comprises a traction network equivalent impedance, a steel rail equivalent impedance and a ground impedance of the steel rail;
the vehicle model is as follows: the vehicle cable short-circuit simulation system comprises a vehicle cable equivalent impedance, a filter reactor, a support capacitor and a simulation short-circuit point module.
Preferably, the traction substation model is modeled based on actual power supply parameters, short circuit capacity, parameters and structures of a transformer, and electrical parameters of rectifier and cable equivalent impedance; the ground resistance of the steel rail is set according to an actual measured value; the analog short-circuit point module is composed of a circuit breaker controlled by a door signal.
Preferably, in the short-circuit working condition setting step, the parameters influencing the short-circuit current during the short-circuit fault include power supply modes of the two traction substation models, positions of the vehicle models and positions of the simulation short-circuit point modules;
the power supply modes comprise a double-side power supply mode and a single-side power supply mode;
the position of the vehicle model comprises a near-end short circuit and a far-end short circuit when the short circuit fault occurs;
dividing short-circuit faults on the vehicle into a filter reactor front short circuit and a filter reactor rear short circuit through the position of the analog short-circuit point module;
different short-circuit working conditions are set according to the power supply modes of the two traction substation models, the positions of the vehicle models and the positions of the simulation short-circuit point modules.
Preferably, in the bilateral power supply mode, the distance between the vehicle model and one traction substation model is approximately zero, the distance between the vehicle model and the other traction substation model is equal to the length of a power supply section line of the two traction substation models, and the distance between the vehicle model and one traction substation model is equal to the distance between the vehicle model and the other traction substation model; in the unilateral power supply mode, the distance between a near-end short circuit, namely a vehicle model, and a traction substation model supplied with power is approximately zero, and the distance between a far-end short circuit, namely the vehicle model, and the traction substation model supplied with power is equal to the length of a power supply section line.
Preferably, in the measurement setting step, the main protection type of the power supply system side protection comprises large-current tripping protection and current rise rate protection, and the current change rate are selected as measurement quantities at the outlet side of the traction substation model; the protection device of the vehicle-mounted protection comprises a vehicle-mounted fuse and a vehicle-mounted high-speed circuit breaker, wherein the integral value of the current and the square of the current to the time is selected as a measurement quantity on the incoming line side of the vehicle-mounted fuse, and the current is selected as a measurement quantity on the incoming line side of the high-speed circuit breaker.
The invention also provides a short circuit test method for the rail transit traction system, which comprises the following steps:
a test preparation step: selecting a test section, carrying out model selection and parameter setting on a traction substation, a traction network, a test vehicle and each level of protection devices according to a simulation result obtained by a short-circuit protection analysis method, and estimating the influence of various short-circuit working conditions on a traction system according to the simulation result to select a test working condition;
installing and wiring the test tool: the direct current network is powered off, and installation and wiring of the test testing equipment and the short circuit closing tool are completed;
the operation step of the traction system: supplying power by direct current to ensure normal work of an auxiliary power supply system, working of a charger, charging of a traction system support capacitor and pulse blocking of a traction inverter;
short circuit test: closing a short circuit closing high-speed circuit breaker in the short circuit closing tool, confirming the action condition of each protection device, and recording test data;
and a test finishing step, namely, the direct current network is powered off, the conditions of all protection devices are checked, the short circuit closing test tool and the test testing equipment are removed, the test vehicle and the traction substation are restored to a normal working state, and then power supply is restored.
Preferably, the test testing equipment is configured and wired according to the electrical quantity to be measured on the power supply system side and the electrical quantity to be measured on the vehicle, and comprises a current sensor, a high-voltage differential probe, a low-inductance shunt, an oscilloscope and a conditioning circuit.
Preferably, in the step of installing and wiring the test tool, the short circuit closing tool comprises a movable trolley and control equipment, and the movable trolley is provided with a short circuit closing high-speed circuit breaker, a protective cover of the short circuit closing high-speed circuit breaker, a shunt and other equipment; the control equipment is used for controlling the action of the closing high-speed circuit breaker.
Preferably, the wiring of the short-circuit closing tool is carried out according to the selected test short-circuit working condition, and the wiring comprises that one end of the short-circuit closing high-speed circuit breaker is connected with a steel rail, and the other end of the short-circuit closing high-speed circuit breaker is connected to the front end of the filter reactor or the rear end of the filter reactor.
Preferably, in the test preparation step, when the selected test section working condition is the single-side power supply mode, one traction substation is disconnected.
Preferably, in the test preparation step, when the selected test short-circuit working condition corresponds to different positions of the test vehicle, the distance between the test vehicle and the two traction substations can be changed.
Preferably, in the test preparation step, the traction substation is replaced by an equivalent direct-current power supply, and the traction grid is replaced by a variable resistor and a variable reactor, the test vehicle is a simulation test vehicle, and the simulation test vehicle comprises a fuse, a circuit breaker, a filter reactor, a support capacitor and a traction inverter and is used for performing a short-circuit test when line test conditions are limited.
Compared with the prior art, the invention has the advantages and positive effects that:
1. when short-circuit fault modeling is carried out, the short-circuit protection analysis method comprehensively considers the operation principle and the electrical parameters of an actual power supply system and a vehicle, considers the position of the vehicle on the line and the position of a short-circuit point on the vehicle when an actual fault occurs, can complete fault simulation tasks under various short-circuit working conditions, and has accurate and reliable simulation results.
2. The short-circuit protection analysis method provided by the invention realizes the calculation of the action time sequence of each protection device when the traction system is in short-circuit fault according to the short-circuit current obtained by simulation and the setting value of each protection device, provides a basis for the model selection and parameter setting of the protection devices, and provides a reference for the design of a short-circuit test.
3. The short circuit test method provided by the invention can be used for carrying out a short circuit test on an actual line, can be used for acquiring reliable test data, can be used for verifying the accuracy of a simulation result, can also be used for verifying the action reliability of a protection device, and provides reference for the design of an urban rail traction system.
4. The invention combines short circuit simulation and test to form a set of complete simulation-test scheme, can perform auxiliary analysis and verification on the design prototype of the traction system, can complete the type test required by relevant standards, can perform reproduction and auxiliary analysis on the short circuit fault of the actual urban rail line, and fills the industrial blank.
5. The short circuit test method provided by the invention can be used for carrying out a short circuit test in a laboratory and carrying out a test when the test condition of the line is limited, thereby avoiding damage to urban rail equipment and influence on normal operation of the line.
Drawings
The accompanying drawings, which are included to provide a further understanding of the invention and are incorporated in and constitute a part of this application, illustrate embodiment(s) of the invention and together with the description serve to explain the invention without limiting the invention. In the drawings:
FIG. 1 is a flow chart of a short-circuit protection analysis method according to an embodiment of the present invention;
FIG. 2 is a diagram of an overall topology structure of an equivalent circuit model according to an embodiment of the present invention;
FIG. 3 is a diagram of a model structure of a traction substation according to an embodiment of the present invention;
FIG. 4 is a diagram of a line impedance model according to an embodiment of the present invention;
FIG. 5 is a topological structure diagram of a vehicle model according to an embodiment of the present invention;
FIG. 6 is a timing diagram illustrating a short circuit current-protection operation according to an embodiment of the present invention;
FIG. 7 is a schematic diagram illustrating a short circuit position-protection operation timing sequence according to an embodiment of the present invention;
FIG. 8 is a flowchart of a short circuit test method according to an embodiment of the present invention;
FIG. 9 is a schematic diagram of a short circuit test according to an embodiment of the present invention;
FIG. 10 is a schematic diagram of a short circuit test according to another embodiment of the present invention.
In the above figures: 1. the vehicle-mounted high-speed circuit breaker reaches tripping current; 2. completing the breaking of the vehicle-mounted high-speed circuit breaker; 3. di/dt + Δ I action exit; 4. di/dt + Δ T action exit; 5. the on-board fuse begins to blow.
Detailed Description
For better understanding of the above technical solutions, the following detailed descriptions are provided with reference to the accompanying drawings and specific embodiments.
The invention provides a short-circuit protection analysis method for an urban rail transit traction system, and referring to fig. 1, fig. 1 is a flow chart of the short-circuit protection analysis method, and specifically comprises the following steps:
s11, short-circuit fault modeling: according to a main circuit of a system in short circuit fault, an equivalent circuit model is built under a simulation environment;
s12, short-circuit working condition setting: setting different short-circuit working conditions according to parameters influencing short-circuit current during short-circuit fault;
s13, measurement setting: determining the selection of electrical measurement quantity and the position of a measurement point according to the action characteristics of each level of protection devices of power supply system side protection and vehicle-mounted protection;
s14, short circuit simulation analysis: after the parameters of the equivalent circuit model are set according to the short-circuit working condition, simulating through the equivalent circuit model according to the electric parameters of the traction power supply system and the short-circuit working condition parameters to obtain a short-circuit current waveform;
s15, an action sequence calculation step: calculating the action time of each stage of protection according to the short-circuit current waveform and the setting value of the protection device;
s16, simulation result output step: and outputting a simulation result with a protective action time sequence according to the short-circuit current waveform and the action time.
Specifically, referring to fig. 2, in the event of a short-circuit fault, the equivalent circuit model of the main circuit of the traction power supply system includes two traction substation models, and a line equivalent impedance model and a vehicle model between the two traction substation models. When a short-circuit fault occurs in a certain power supply section of a vehicle in an actual line, short-circuit current is mainly provided by two traction substations closest to the vehicle, and short-circuit current provided by other traction substations far away from the vehicle on the line is smaller, so that only two left and right traction substation models of the short-circuit section can be established in simulation analysis. The short-circuit current flows through the traction substation, the traction net, the vehicle short-circuit point and the steel rail and then flows back to the traction substation to form a loop.
Referring to fig. 3 to 5, in the above embodiment, the short-circuit fault modeling step S11 includes:
modeling a traction substation model: referring to fig. 3, the traction substation model includes system equivalent power, traction transformer, rectifier and cable equivalent impedance; the traction substation model is modeled based on actual power supply parameters, short circuit capacity, parameters and structures of a traction transformer, and electrical parameters of rectifier and cable equivalent impedance.
Specifically, the system equivalent power supply is a three-phase voltage source, and power supply parameters and short-circuit capacity are set according to actual medium-voltage network parameters; the traction transformers and the rectifiers are respectively arranged into two groups, one group of traction transformers and the rectifiers are connected in series and then connected with the other group of traction transformers and the rectifiers which are connected in series in parallel, and a system equivalent power supply is connected with the traction transformers; the traction transformer is a three-winding transformer, the frequency of the traction transformer is 50Hz, and electrical parameters such as transformation ratio, primary and secondary winding impedance, excitation impedance, winding connection mode and the like are set according to actual transformer parameters; the rectifier is a three-phase bridge inverter circuit, and the electrical parameters of the rectifier are set according to actual parameters. The cable equivalent impedance model is a pi-type equivalent circuit, and the electrical parameters are set according to actual parameters.
Line equivalent impedance model: reference is made to fig. 4, which includes the traction network equivalent impedance, the rail equivalent impedance, and the rail to ground impedance. Specifically, the equivalent impedance of the traction network and the equivalent impedance of the steel rail are determined by the relative position between the position of the vehicle and the traction substation model, the impedance values are obtained by calculating the distance between the relative positions multiplied by the unit length impedance, and the unit length impedance of the traction network and the steel rail and the ground impedance value of the steel rail are set according to actual measurement values.
The vehicle model is as follows: referring to fig. 5, the vehicle-mounted short-circuit protection circuit includes a vehicle cable equivalent impedance, a filter reactor, a support capacitor and a simulation short-circuit point module, and a first current collector obtains current and sequentially passes through the first vehicle cable equivalent impedance, the filter reactor, the support capacitor and a second vehicle cable equivalent impedance to a second current collector. The analog short-circuit point module is connected with the support capacitor in parallel or connected with the filter reactor and the support capacitor in parallel; the simulation short-circuit point module is used for simulating a short-circuit fault behind a filter reactor and a short-circuit fault in front of the filter reactor on an actual vehicle, and in the embodiment, the simulation short-circuit point module preferably consists of a breaker controlled by a door signal, the breaker is in a normally open state, and the breaker is controlled to be closed to simulate the short-circuit fault in a specific time period. Specifically, the vehicle model is used for simulating a short-circuit loop on the actual vehicle side when a short-circuit fault occurs, the supporting capacitor, the filter reactor and the cable are arranged according to actual values.
Further, in the short-circuit condition setting step S12, the parameters affecting the short-circuit current when the short-circuit fault occurs include power supply modes of the two traction substation models, positions of the vehicle models, and positions of the simulation short-circuit point modules. Specifically, when a short-circuit fault of an urban rail traction power supply system occurs, two main factors influencing a short-circuit current are as follows: (1) Electrical parameters of the traction substation, including voltage class and short circuit capacity; and (2) the equivalent impedance from the short-circuit point to the traction substation. Therefore, in a simulation environment, when the parameters of the equivalent power supply side of the system are not changed, the total impedance value from the short circuit point to the traction substation model determines the size and the change rate of the short circuit current. If the short-circuit point is behind the filter reactor, the total impedance mainly comprises the equivalent impedance of the line from the vehicle model to the traction substation model and the filter reactance. Therefore, except for the filter reactor, the size of the equivalent impedance of the line, namely the distance from the traction substation models on two sides when the vehicle model is in short circuit, directly influences the short-circuit current. Considering the influence of the filter reactor on the short-circuit current, the short-circuit fault occurring on the vehicle is divided into a filter reactor front short circuit and a filter reactor rear short circuit.
In summary, in the simulation environment, the parameters affecting the short-circuit current when the short-circuit fault occurs have the following three types:
(1) The power supply modes of the two traction substation models comprise a bilateral power supply mode and a unilateral power supply mode, the two traction substation models are both connected into the equivalent circuit model in the bilateral power supply mode, and one traction substation model is required to be deleted in the unilateral power supply mode;
(2) The position of the vehicle model comprises a near-end short circuit and a far-end short circuit when the short circuit fault occurs;
(3) Simulating the position of a short-circuit point module, and dividing short-circuit faults on the vehicle into a filter reactor front short circuit and a filter reactor rear short circuit through the position of the short-circuit point module;
and integrating the power supply modes of the two traction substations, the positions of the vehicle models and the positions of the simulation short-circuit point modules, and setting different short-circuit working conditions by considering two extreme conditions of a near-end short circuit and a far-end short circuit.
TABLE 1 typical short-circuit conditions
Referring to table 1, the short-circuit conditions listed in table 1 cover the maximum and minimum values of the steady-state value of the short-circuit current and the maximum and minimum values of the current change rate, which may occur, and can comprehensively reflect the short-circuit condition of the power supply interval.
In the above embodiment, in the bilateral power supply mode, the distance between the near-end short circuit, that is, the vehicle model, and one traction substation model is approximately zero, the distance between the near-end short circuit and the other traction substation model is equal to the length of the power supply interval line between the two traction substation models, and the distance between the far-end short circuit, that is, the vehicle model, and one traction substation model is equal to the distance between the far-end short circuit and the other traction substation model; in the unilateral power supply mode, the distance between a near-end short circuit, namely a vehicle model, and a traction substation model supplied with power is approximately zero, and the distance between a far-end short circuit, namely the vehicle model, and the traction substation model supplied with power is equal to the length of a power supply section line.
Further, in the measurement setting step S13, the main protection type of the side protection of the power supply system includes a large current trip protection and a current rise rate protection, and the current change rate are selected as measurement quantities at the outlet side of the traction substation model; the protection device of the vehicle-mounted protection comprises a vehicle-mounted fuse and a vehicle-mounted high-speed circuit breaker, wherein the integral value of the current and the square of the current to the time is selected as a measurement quantity on the wire inlet side of the vehicle-mounted fuse, and the current is selected as a measurement quantity on the wire inlet side of the high-speed circuit breaker.
Specifically, when the traction system is short-circuited, the power supply system side relay protection, the vehicle-mounted fuse and the vehicle-mounted high-speed circuit breaker act to cut off the short-circuit current. The selection and analysis method of the protection action characteristics, the measurement quantity and the measurement points corresponding to each protection device is as follows:
(1) Power supply system side protection: the main protection type of the power supply side corresponding to the short-circuit fault is di/dt + delta I, di/dt + delta T and large-current tripping. When the current change rate di/dt reaches a set value, the protection of di/dt + delta I, di/dt + delta T is started, short-circuit current increment delta I and time increment delta T are detected, and when the delta I or the delta T reaches a set value and the di/dt is not smaller than a set return value in the period, the breaker trips; and when the current value reaches a high-current tripping set value, the circuit breaker trips. Therefore, the measuring position is located on the outgoing line side of the traction substation model, the protection acts according to time, current change rate and current change amount, and the current change rate are selected as the measuring amount.
(2) And (3) vehicle-mounted fuse: the device is positioned on the wire inlet side of a vehicle, a corresponding simulation model measuring point is arranged behind a current collector according to the installation position of an actual vehicle-mounted fuse, the fusing time of the vehicle-mounted fuse is closely related to the characteristic of the front arc I2t of the vehicle-mounted fuse, and therefore the current measuring point of the vehicle-mounted fuse is used for measuring the current and the integral value of the square of the current to the time.
(3) Vehicle-mounted high-speed circuit breaker: the current measuring point of the vehicle-mounted high-speed circuit breaker is arranged on the wire inlet side of the high-speed circuit breaker, and the current amplitude detected by the vehicle-mounted high-speed circuit breaker reaches a set value to act for tripping, so that the current value can be selected according to the measured quantity. And when the short-circuit current reaches the setting value of the vehicle-mounted high-speed circuit breaker, the vehicle-mounted high-speed circuit breaker starts protection action.
Further, in the simulation result output step S16, a simulation result having a protection operation timing is output based on the short-circuit current waveform and the operation time, and the simulation result is output in the form of a graph, a table, or a report. The simulation result can reflect the action time sequence of the short-circuit, the power supply system side and the traction system side protection of the vehicle model under different short-circuit working conditions, and specifically refer to fig. 6 and 7. Fig. 6 is a schematic diagram of a short-circuit current-protection operation timing sequence, and fig. 6 is a schematic diagram of a short-circuit position-protection operation timing sequence. In the abscissa of fig. 7, the first arrow line and the last arrow line represent the action time of each stage of protection device under the bilateral power supply mode, and the vehicle model is under the short-circuit condition of the short circuit at the near end, that is, when the distance from the vehicle model to one traction substation is approximately 0 and the distance from the vehicle model to the other traction substation is equal to the line length of the power supply interval; the third arrow line on the abscissa represents the action time of each stage of protection device under the short-circuit working condition of the vehicle model under the bilateral power supply mode and the far-end short circuit; the second and third arrowhead lines represent the action time of each stage of protection device under the short-circuit working condition that the vehicle model is at other positions when the short-circuit fault occurs. With the continuous increase of the short-circuit current, the action time sequence of each stage of protection device is that the vehicle-mounted high-speed circuit breaker reaches a tripping current 1, the vehicle-mounted high-speed circuit breaker completes breaking 2, a di/dt + delta I action outlet 3, a di/dt + delta T action outlet 4 and a vehicle-mounted fuse starts to fuse 5 in sequence.
In conclusion, the short-circuit protection analysis method provided by the invention simulates the short-circuit faults of vehicles under various working conditions in a simulation environment, measures the short-circuit current, calculates the action time sequences of the urban rail traction system and the traction power supply system protection device according to the short-circuit current, verifies the effectiveness and accuracy of the action of the vehicle-mounted protection device, can provide suggestions for the reasonability of the design of the traction power supply system, and can be used for fault recurrence and reason analysis means to assist in analysis when the short-circuit fault occurs in an actual line.
The invention also provides a short circuit test method for a rail transit traction system, and referring to fig. 8, fig. 8 is a flowchart of the short circuit test method, which includes the following steps:
s21, a test preparation step: selecting a test section, carrying out model selection and parameter setting on a traction substation, a traction network, a test vehicle and each level of protection devices according to a simulation result obtained by a short-circuit protection analysis method, and estimating the influence of various short-circuit working conditions on a traction system according to the simulation result to select a test working condition;
s22, mounting and wiring of the test tool: the direct current network is powered off, and installation and wiring of the test testing equipment and the short circuit closing tool are completed;
s23, traction system operation: supplying power by a direct current network to ensure that an auxiliary power supply system works normally, enabling a charger to work, enabling a traction system to support a capacitor to charge, and locking a traction inverter pulse;
s24, short circuit test: closing a short circuit closing high-speed circuit breaker in the short circuit closing tool, confirming the action condition of each protection device, and recording test data;
and S25, completing the test, namely cutting off the power of the direct current network, checking the conditions of all protection devices, removing the short-circuit closing test tool and the test equipment, restoring the test vehicle and the traction substation to normal working states, and then restoring power supply.
The short-circuit test method is used for a short-circuit test of a rail transit traction system, and is used for verifying a simulation result of the short-circuit protection analysis method, verifying the simulation accuracy, completing a type test required by a relevant standard, and verifying the reasonability of the design of the traction system and the reasonability of the relay protection setting of the traction power supply system. Specifically, in the test preparation step S21, a test section is selected, and a test section rail area and a test site are cleared and blocked; and the test vehicle is correspondingly stopped at a preset position according to the selected test working condition, the test short-circuit working condition is selected by predicting the influence of various short-circuit working conditions on the traction system according to the simulation result, and the test short-circuit working condition which can be borne by each device and the protection device is selected for testing.
In the above embodiment, in the step S22 of installing and wiring the test tool, the test testing device performs configuration and wiring according to the electrical quantity to be measured at the power supply system side and the electrical quantity to be measured at the test vehicle, and includes a current sensor, a high-voltage differential probe, a low-inductance shunt, an oscilloscope, and a conditioning circuit.
Specifically, the electrical quantity to be measured at the power supply system side comprises feeder line voltage and current and the action condition of protection at the power supply system side, and the electrical quantity to be measured by the test vehicle comprises current and terminal voltage of a vehicle-mounted fuse; the current and terminal voltage of the vehicle-mounted high-speed circuit breaker; drawing the inverter inlet wire current and terminal voltage; and the action time sequences of the vehicle-mounted fuse, the vehicle-mounted high-speed circuit breaker and the short circuit closing high-speed circuit breaker are determined. The electric quantity measurement is mainly realized by a current sensor, a high-voltage differential probe, a low-inductance current divider, an oscilloscope and a conditioning circuit, and the equipment selection and configuration thinking is as follows:
(1) And determining corresponding measuring points of all electrical quantities according to the installation position of the protection device. The current measuring point is connected with the low-inductance shunt in series at a position with a fixed low-inductance shunt condition, otherwise, the current sensor is used for measuring the current. The voltage measuring point measures voltage by using a high-voltage differential probe; the protection device time sequence is tested by connecting the auxiliary contact signals of the protection devices into an oscilloscope. Illustratively, the auxiliary contact outputs a digital quantity signal, and the auxiliary contact signals of all the protection devices are connected into the same oscilloscope. When the protection devices act, the output level of the auxiliary contacts changes, namely the level changes from low level to high level or from high level to low level, and the oscilloscope reads the level changes to determine the action sequence of each protection device. The oscilloscope only displays and records the waveform of the output signal of each auxiliary contact, and the waveform is combined with other measured electrical quantities to jointly analyze the action sequence of the protection device.
(2) And determining the maximum value of the short-circuit current of the measuring point possibly occurring under various short-circuit working conditions according to the simulation result.
(3) And setting redundancy multiplying power according to the maximum value of the short-circuit current of the measuring point which possibly occurs, and selecting the current sensor and the current divider with corresponding measuring range and size.
(4) And special signal shielding cables and signal conditioning tools are manufactured according to parameters of the sensors and the shunt, so that the stability of each electrical measurement quantity is ensured.
Preferably, in the short circuit test step S24, the recorded test data are the electrical quantity tested by the test testing equipment and the action timing sequence of each protection device recorded by the oscilloscope, and the recorded electrical quantity can be visually compared with the electrical quantity obtained by simulation.
Furthermore, in the step S22 of installing and wiring the test tool, the short circuit closing tool includes a movable trolley and a control device, the movable trolley is provided with a short circuit closing high-speed circuit breaker and a protective cover, a shunt and other devices, and the control device is used for controlling the action of the closing high-speed circuit breaker; the wiring of the short circuit closing tool is carried out according to the selected test short circuit working condition, and the wiring comprises that one end of the short circuit closing high-speed circuit breaker is connected with a steel rail, and the other end of the short circuit closing high-speed circuit breaker is connected to the front end of the filter reactor or the rear end of the filter reactor.
Specifically, referring to fig. 9, in the test preparation step S21, when the test short-circuit working condition is the bilateral power supply mode, the traction substation a and the traction substation B on both sides of the vehicle need to be tested to supply power simultaneously, and when the test short-circuit working condition is the unilateral power supply mode, the traction substation on one side needs to be disconnected; when the selected test short-circuit working condition corresponds to the positions of different test vehicles, the distance between the test vehicle and the two traction substations can be changed, and therefore short-circuit tests of different test short-circuit working conditions are carried out. After the short circuit closing high-speed circuit breaker is closed, short-circuit current flows out of a positive pole of a DC1500V of the traction substation, sequentially flows through a traction net, a current collector, a vehicle-mounted fuse, the vehicle-mounted high-speed circuit breaker, the short circuit closing high-speed circuit breaker and a steel rail, and finally flows back to a negative pole of the DC1500V of the traction substation to form a loop.
Furthermore, the short-circuit test method in the above embodiment is applied to an actual line, and a relatively accurate and reliable test result can be obtained, but the short-circuit test has certain danger, and may damage urban rail equipment, which affects normal operation of the line.
Therefore, as another preferred embodiment, in the test preparation step S21, the equivalent dc power supply replaces the traction substation, the variable resistor and the variable reactor replace the traction network, and the simulation test vehicle replaces the test vehicle, wherein the simulation test vehicle includes a fuse, a circuit breaker, a filter reactor, a support capacitor, and a traction inverter, and different positions of the test vehicle are simulated by adjusting impedance values of the variable resistor and the variable reactor.
Specifically, referring to fig. 10, in the above embodiment, the traction substation is replaced by an equivalent dc power supply, the equivalent dc power supply is a dc power supply capable of achieving the short-circuit capacity and the voltage system of the urban rail power supply system, and the power supply system side, that is, the dc network side test equipment is an equivalent dc power supply and a dc switch cabinet; a variable resistor and a variable reactor connected by an equivalent direct current power supply replace a traction network, and the impedance of the traction network is equivalent to the impedance of the traction network and the impedance of a steel rail between a test vehicle and a traction substation on an actual circuit; the test vehicle is replaced by a simulation test vehicle, and the simulation test vehicle comprises a fuse, a circuit breaker, a filter reactor I, a supporting capacitor I and a traction inverter I. The method comprises the following steps that a fuse, a circuit breaker, a filter reactor I and a traction inverter I are traction tested equipment, the traction tested equipment and a supporting capacitor I are connected according to the same topological structure as an actual line test vehicle, and in an exemplary step S22 of installing and connecting of a test tool, the installation and connection of the test equipment and a short circuit closing tool are consistent with a short circuit test of an actual line; in the test completion step S25, the dc network is powered off, the conditions of the protection devices are checked, and the short circuit closing test tool and the test equipment, the dc network side test equipment, the traction tested equipment, and the like are removed. In this embodiment, the configuration and the installation wiring of the short circuit closing tool and the type selection and configuration of each test device and each tested device are consistent with the short circuit test of the actual line. The method comprises the steps that a test vehicle needs to measure the electric quantity and the electric quantity measuring point to be consistent with the electric quantity and the electric quantity measuring point of the test vehicle for an actual line short circuit test, the electric quantity to be measured on the direct current network side is the terminal voltage and the current of a direct current switch cabinet and the action condition of direct current network side protection, and the action condition is tested through an oscilloscope. The remaining test steps of the short circuit test are identical to the actual line short circuit test steps. This embodiment is used for carrying out the short circuit test when the circuit test condition is limited, can go on in the laboratory, has avoided the short circuit test of actual circuit to cause the harm to city rail equipment, influences the normal operation of circuit.
The above description is only a preferred embodiment of the present invention, and not intended to limit the present invention in other forms, and any person skilled in the art may apply the above modifications or changes to the equivalent embodiments with equivalent changes, without departing from the technical spirit of the present invention, and any simple modification, equivalent change and change made to the above embodiments according to the technical spirit of the present invention still belong to the protection scope of the technical spirit of the present invention.
Claims (12)
1. The short-circuit protection analysis method for the urban rail transit traction system is characterized by comprising the following steps of:
short-circuit fault modeling step: according to a main circuit of a system in short circuit fault, an equivalent circuit model is built under a simulation environment;
short circuit working condition setting: different short-circuit working conditions are set according to parameters influencing the short-circuit current during the short-circuit fault, wherein the parameters influencing the short-circuit current during the short-circuit fault comprise power supply modes of two traction substation models, positions of vehicle models and positions of simulation short-circuit point modules; the power supply mode comprises a double-side power supply mode and a single-side power supply mode, wherein two traction substation models are connected into the equivalent circuit model in the double-side power supply mode, and one traction substation model is deleted in the single-side power supply mode; the position of the vehicle model comprises a near-end short circuit and a far-end short circuit when short circuit faults occur; dividing short-circuit faults on the vehicle into a filter reactor front short circuit and a filter reactor rear short circuit through the position of the analog short-circuit point module;
a measurement setting step: determining the selection of electrical measurement quantity and the position of a measurement point according to the action characteristics of each stage of protection devices of power supply system side protection and vehicle-mounted protection, wherein the main protection types of the power supply system side protection comprise large-current tripping protection and current rise rate protection, and the current change rate are selected as the measurement quantity on the outlet side of a traction substation model; the protection device of the vehicle-mounted protection comprises a vehicle-mounted fuse and a vehicle-mounted high-speed circuit breaker, wherein the current and the integral value of the square of the current to the time are selected as measurement quantities on the wire inlet side of the vehicle-mounted fuse, and the current is selected as the measurement quantities on the wire inlet side of the high-speed circuit breaker;
short circuit simulation analysis: after the parameters of the equivalent circuit model are set according to the short-circuit working condition, simulating through the equivalent circuit model according to the electric parameters of the traction power supply system and the short-circuit working condition parameters to obtain a short-circuit current waveform;
an action sequence calculation step: calculating the action time of each stage of protection according to the short-circuit current waveform and the setting value of the protection device;
and (3) simulation result output step: and outputting a simulation result with a protective action time sequence according to the short-circuit current waveform and the action time.
2. The urban rail transit traction system short-circuit protection analysis method according to claim 1, wherein the equivalent circuit model comprises two traction substation models and a line equivalent impedance model and a vehicle model between the two traction substation models.
3. The urban rail transit traction system short-circuit protection analysis method according to claim 2, wherein the short-circuit fault modeling step comprises:
a traction substation model building step: the traction substation model comprises a system equivalent power supply, a traction transformer, a rectifier and cable equivalent impedance;
line equivalent impedance model: the system comprises a traction network equivalent impedance, a steel rail equivalent impedance and a ground impedance of the steel rail;
the vehicle model is as follows: the vehicle cable short-circuit simulation system comprises a vehicle cable equivalent impedance, a filter reactor, a support capacitor and a simulation short-circuit point module.
4. The urban rail transit traction system short-circuit protection analysis method according to claim 3, wherein the traction substation model is modeled based on actual power supply parameters, short-circuit capacity, parameters and structures of traction transformers, and electrical parameters of rectifier and cable equivalent impedance; the ground resistance of the steel rail is set according to an actual measured value; the analog short-circuit point module is composed of a circuit breaker controlled by a door signal.
5. The urban rail transit traction system short-circuit protection analysis method according to claim 1, wherein in the bilateral power supply mode, a distance between a near-end short-circuit vehicle model and one traction substation model is approximately zero, a distance between the near-end short-circuit vehicle model and the other traction substation model is equal to a power supply interval line length between the two traction substation models, and a distance between a far-end short-circuit vehicle model and one traction substation model is equal to a distance between the far-end short-circuit vehicle model and the other traction substation model; in the unilateral power supply mode, the distance between the vehicle model, namely the near-end short circuit, and the traction substation model supplied with power is approximately zero, and the distance between the vehicle model, namely the far-end short circuit, and the traction substation model supplied with power is equal to the line length of a power supply interval.
6. A short circuit test method is used for a rail transit traction system and is characterized by comprising the following steps:
a test preparation step: selecting a test section, performing model selection and parameter setting on a traction substation, a traction network, a test vehicle and all levels of protection devices according to a simulation result obtained by a short-circuit protection analysis method, and selecting a test short-circuit working condition according to the simulation result to estimate the influence of various short-circuit working conditions on a traction system, wherein the short-circuit protection analysis method is the urban rail transit traction system short-circuit protection analysis method of any one of claims 1~5;
installing and wiring the test tool: the direct current network is powered off, and installation and wiring of the test testing equipment and the short circuit closing tool are completed;
the operation steps of the traction system are as follows: supplying power by a direct current network to ensure that an auxiliary power supply system works normally, enabling a charger to work, enabling a traction system to support a capacitor to charge, and locking a traction inverter pulse;
short circuit test: closing a short-circuit closing high-speed circuit breaker in the short-circuit closing tool, confirming the action condition of each protection device, and recording test data;
and the test completion step comprises the steps of cutting off the power of the direct current network, checking the conditions of all the protection devices, removing the short circuit closing test tool and the test equipment, restoring the test vehicle and the traction substation to normal working states, and then restoring power supply.
7. The short circuit test method of claim 6, wherein the test equipment is configured and wired according to the electrical quantity to be measured on the power supply system side and the electrical quantity to be measured on the vehicle, and comprises a current sensor, a high-voltage differential probe, a low-inductance shunt, an oscilloscope and a conditioning circuit.
8. The short circuit test method according to claim 6, wherein in the step of installing and wiring the test tooling, the short circuit closing tooling comprises a movable trolley and control equipment, and the movable trolley is provided with a short circuit closing high-speed circuit breaker, a protective cover thereof, a shunt and other equipment; the control equipment is used for controlling the action of the closing high-speed circuit breaker.
9. The short circuit test method of claim 8, wherein the wiring of the short circuit closing tool is performed according to the selected test short circuit condition, and the wiring comprises that one end of the short circuit closing high-speed circuit breaker is connected with a steel rail, and the other end of the short circuit closing high-speed circuit breaker is connected to the front end of the filter reactor or the rear end of the filter reactor.
10. The short circuit test method of claim 6, wherein in the test preparation step, when the selected test short circuit condition is a single-side power supply mode, a traction substation is disconnected.
11. The short circuit test method of claim 6, wherein in the test preparation step, the distance between the test vehicle and the two traction substations can be changed when the selected test short circuit condition corresponds to the position of the test vehicle.
12. The short circuit test method according to claim 6, wherein in the test preparation step, the traction substation is replaced by an equivalent direct current power supply, the traction network is replaced by a variable resistor and a variable reactor, and the test vehicle is a simulation test vehicle including a fuse, a circuit breaker, a filter reactor, a support capacitor, and a traction inverter for performing a short circuit test when a line test condition is limited.
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| CN113486541B (en) * | 2021-09-08 | 2021-11-23 | 中铁电气化勘测设计研究院有限公司 | Simulation method of urban rail direct-current power supply system based on train safety distance and voltage |
| CN113771630B (en) * | 2021-09-24 | 2023-08-25 | 中车长春轨道客车股份有限公司 | Urban railway vehicle grounding protection circuit |
| CN116679236B (en) * | 2023-06-01 | 2024-05-17 | 中铁一局集团电务工程有限公司 | LSM-based subway contact network short-circuit impedance and short-circuit simulation test method and system |
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