CN112630686A - Method and system for identifying single-phase earth fault line of urban rail medium-voltage system - Google Patents

Method and system for identifying single-phase earth fault line of urban rail medium-voltage system Download PDF

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CN112630686A
CN112630686A CN202011631820.2A CN202011631820A CN112630686A CN 112630686 A CN112630686 A CN 112630686A CN 202011631820 A CN202011631820 A CN 202011631820A CN 112630686 A CN112630686 A CN 112630686A
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branch line
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王海军
冯洪高
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Nanjing Institute of Railway Technology
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Abstract

本发明公开了一种城轨中压系统单相接地故障线路识别方法及系统，方法步骤包括：实时测量零序电压和零序电流；将各个零序电流以及零序电压发送至每一个功率方向识别装置；由各个功率方向识别装置分别计算各个分支线路的实时零序功率，并判断各个分支线路的实时零序功率的方向，若某个实时零序功率方向为分支线路流向母线，则该分支线路存在单相接地故障。该城轨中压系统单相接地故障线路识别方法及系统利用各个功率方向识别装置实时计算零序功率，并在判断零序功率的方向为分支线路流向母线时识别出该分支线路存在单相接地故障，从而便于快速地将发生单相接地故障的分支线路从母线上断开，维持其他分支线路的正常运行。

Figure 202011631820

The invention discloses a method and system for identifying a single-phase grounding fault line of an urban rail medium voltage system. The method steps include: measuring zero-sequence voltage and zero-sequence current in real time; sending each zero-sequence current and zero-sequence voltage to each power direction Identification device; each power direction identification device calculates the real-time zero-sequence power of each branch line respectively, and judges the direction of the real-time zero-sequence power of each branch line. The line has a single-phase ground fault. The single-phase grounding fault line identification method and system of the urban rail medium voltage system utilizes each power direction identification device to calculate the zero-sequence power in real time, and recognizes that the branch line has single-phase grounding when the direction of the zero-sequence power is judged to be the branch line flowing to the bus. Therefore, it is convenient to quickly disconnect the branch line with a single-phase ground fault from the bus, and maintain the normal operation of other branch lines.

Figure 202011631820

Description

Method and system for identifying single-phase earth fault line of urban rail medium-voltage system
Technical Field
The invention relates to a single-phase earth fault line identification method and a single-phase earth fault line identification system, in particular to a single-phase earth fault line identification method and a single-phase earth fault line identification system for an urban rail medium-voltage system by adopting an earth transformer.
Background
In the conventional power system, as shown in fig. 3, T1 is a power supply transformer, A, B, C is a three-phase bus, F1, F2, … …, Fn-1, and Fn are lead wires, C01, C02, … …, C0n-1, and C0n are zero-sequence capacitors to ground of the corresponding lines, Rf is a single-phase grounded transition resistor, X0 is a zero-sequence impedance of a grounded transformer, and RN is a grounded current-limiting resistor.
When the system runs normally, the ABC three phases are balanced and symmetrical, so that the current flowing through the grounding capacitor is relatively small, and the system does not have serious harm to the insulation of the system and the safe operation of equipment. Once the system is earthed in a single phase, the voltage of the same phase connected with the bus is limited to be fault voltage, and the power network is seriously operated in a non-full phase, so that the fault line is determined and tripped in time in a short time, and the reliability and the safety of the system are significant.
Disclosure of Invention
The purpose of the invention is as follows: the method and the system for identifying the single-phase earth fault line of the urban rail medium-voltage system can identify and judge whether each branch line on the bus has the single-phase earth fault, so that the branch line with the single-phase earth fault can be conveniently and quickly disconnected from the bus, and the normal operation of other branch lines is maintained.
The technical scheme is as follows: the invention relates to a method for identifying a single-phase earth fault line of an urban rail medium-voltage system, which comprises the following steps:
step 1, installing a voltage transformer on a bus to measure zero sequence voltage in real time, and installing a zero sequence current transformer on each branch line of the bus to measure zero sequence current in real time;
step 2, correspondingly sending each zero sequence current to each power direction identification device, and sending the zero sequence voltage measured in real time to each power direction identification device;
and 3, respectively calculating the real-time zero sequence power of each branch line by each power direction identification device, judging the direction of the real-time zero sequence power of each branch line, and if a certain real-time zero sequence power direction is a branch line flow direction bus, determining that the branch line has a single-phase earth fault.
As a further scheme of the method, the method also comprises the following steps:
and 4, the power direction identification device sends an opening signal to the circuit breaker on the corresponding branch line with the single-phase earth fault, so that the branch line is disconnected from the bus.
As a further development of the method, the power direction detection device is a power direction relay and/or a microcomputer protection device.
The invention also provides a single-phase earth fault line identification system of the urban rail medium-voltage system, which comprises a voltage transformer, each zero-sequence current transformer and each power direction identification device;
the voltage transformer is used for being installed on a bus and measuring the zero sequence voltage of the bus in real time;
each zero sequence current transformer is used for being respectively installed on each branch line of the bus and measuring the zero sequence current of each branch line in real time;
each power direction identification device is electrically connected with a voltage transformer and is used for acquiring the zero sequence voltage of the bus;
each power direction identification device is also electrically connected with each zero sequence current transformer respectively and is used for acquiring the zero sequence current of each branch circuit;
each power direction identification device is used for calculating the real-time zero sequence power of each branch line according to the zero sequence voltage and each zero sequence current, judging the direction of the real-time zero sequence power of each branch line, and sending a turn-off signal that a single-phase earth fault exists in the branch line if a certain real-time zero sequence power direction is that the branch line flows to the bus.
As a further scheme of the system, the system also comprises various circuit breakers;
each circuit breaker is used for being respectively connected in series on each branch line and is used for controlling the on-off of each branch line according to the turn-off signal;
each power direction recognition device is also electrically connected with each circuit breaker respectively, and is used for sending a turn-off signal to the corresponding circuit breaker when judging that the single-phase earth fault exists.
As a further development of the system, the power direction detection device is a power direction relay and/or a microcomputer protection device.
Compared with the prior art, the invention has the beneficial effects that: the method comprises the steps of utilizing each power direction identification device to calculate zero sequence power in real time, and identifying that a branch line has a single-phase earth fault when the direction of the zero sequence power is judged to be that the branch line flows to a bus, so that the branch line with the single-phase earth fault can be conveniently and quickly disconnected from the bus, and the normal operation of other branch lines is maintained.
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FIG. 1 is a schematic diagram of a signal acquisition architecture of the present invention;
FIG. 2 is a schematic diagram of the operation of the present invention;
FIG. 3 is a prior art electrical power system architecture;
fig. 4 is a single-phase zero-sequence current system diagram of a power system in the prior art.
Detailed Description
The technical solution of the present invention is described in detail below with reference to the accompanying drawings, but the scope of the present invention is not limited to the embodiments.
In the existing power system, as shown in fig. 3 and 4, F1, F2, … …, Fn-1, Fn are lead-out lines, C01, C02, … …, Cn-1, Cn are zero-sequence capacitors to ground of corresponding lines, I01, I02, … …, I0n-1, I0n, I0N are zero-sequence capacitors to ground of corresponding lines, Rf is a transition resistor of single-phase grounding, X0 is zero-sequence impedance of a grounding transformer, RN is a grounding current-limiting resistor, and Vf is a virtual zero-sequence voltage source. According to the characteristics of the ordered components, only the zero sequence power of the fault line flows to the bus, and the rest zero sequence power flows out of the bus, so that the direction of the zero sequence power can be used for determining the fault line.
Example 1:
as shown in fig. 1 and 2, the method for identifying the single-phase earth fault line of the urban rail medium-voltage system disclosed by the invention comprises the following steps:
step 1, installing a voltage transformer on a bus to measure zero sequence voltage in real time, and installing a zero sequence current transformer on each branch line of the bus to measure zero sequence current in real time;
step 2, correspondingly sending each zero sequence current to each power direction identification device, and sending the zero sequence voltage measured in real time to each power direction identification device;
and 3, respectively calculating the real-time zero sequence power of each branch line by each power direction identification device, judging the direction of the real-time zero sequence power of each branch line, and if a certain real-time zero sequence power direction is a branch line flow direction bus, determining that the branch line has a single-phase earth fault.
The method comprises the steps of utilizing each power direction identification device to calculate zero sequence power in real time, and identifying that a branch line has a single-phase earth fault when the direction of the zero sequence power is judged to be that the branch line flows to a bus, so that the branch line with the single-phase earth fault can be conveniently and quickly disconnected from the bus, and the normal operation of other branch lines is maintained.
As a further scheme of the method, the method also comprises the following steps:
and 4, the power direction identification device sends an opening signal to the circuit breaker on the corresponding branch line with the single-phase earth fault, so that the branch line is disconnected from the bus.
And the power direction recognition device is used for linkage control with the corresponding circuit breaker, so that the branch line is timely disconnected from the bus when the single-phase earth fault is recognized, and the normal operation of other branch lines is maintained.
As a further development of the method, the power direction detection device is a power direction relay and/or a microcomputer protection device. The power direction relay and the microcomputer protection device can be installed at the same time, and the operation reliability of the method can be ensured.
As shown in fig. 1 and 2, the single-phase earth fault line identification system of the urban rail medium-voltage system disclosed by the invention comprises: the power direction identification device comprises a voltage transformer, each zero sequence current transformer and each power direction identification device;
the voltage transformer is used for being installed on a bus and measuring the zero sequence voltage of the bus in real time;
each zero sequence current transformer is used for being respectively installed on each branch line of the bus and measuring the zero sequence current of each branch line in real time;
each power direction identification device is electrically connected with a voltage transformer and is used for acquiring the zero sequence voltage of the bus;
each power direction identification device is also electrically connected with each zero sequence current transformer respectively and is used for acquiring the zero sequence current of each branch circuit;
each power direction identification device is used for calculating the real-time zero sequence power of each branch line according to the zero sequence voltage and each zero sequence current, judging the direction of the real-time zero sequence power of each branch line, and sending a turn-off signal that a single-phase earth fault exists in the branch line if a certain real-time zero sequence power direction is that the branch line flows to the bus.
As a further scheme of the system, the system also comprises various circuit breakers;
each circuit breaker is used for being respectively connected in series on each branch line and is used for controlling the on-off of each branch line according to the turn-off signal;
each power direction recognition device is also electrically connected with each circuit breaker respectively, and is used for sending a turn-off signal to the corresponding circuit breaker when judging that the single-phase earth fault exists.
As a further development of the system, the power direction detection device is a power direction relay and/or a microcomputer protection device. The power direction relay and the microcomputer protection device can be installed at the same time, and the operation reliability of the system can be ensured.
As noted above, while the present invention has been shown and described with reference to certain preferred embodiments, it is not to be construed as limited thereto. Various changes in form and detail may be made therein without departing from the spirit and scope of the invention as defined by the appended claims.

Claims (6)

1.一种城轨中压系统单相接地故障线路识别方法，其特征在于，包括如下步骤：1. a method for identifying a single-phase ground fault line of an urban rail medium voltage system, is characterized in that, comprises the steps: 步骤1，在母线上安装电压互感器来实时测量零序电压，在母线的各个分支线路上安装零序电流互感器来实时测量零序电流；Step 1, install a voltage transformer on the bus to measure the zero-sequence voltage in real time, and install a zero-sequence current transformer on each branch line of the bus to measure the zero-sequence current in real time; 步骤2，将各个零序电流对应发送至各个功率方向识别装置，将实时测量的零序电压发送至每一个功率方向识别装置；Step 2, correspondingly send each zero-sequence current to each power direction identification device, and send the zero-sequence voltage measured in real time to each power direction identification device; 步骤3，由各个功率方向识别装置分别计算各个分支线路的实时零序功率，并判断各个分支线路的实时零序功率的方向，若某个实时零序功率方向为分支线路流向母线，则该分支线路存在单相接地故障。Step 3, the real-time zero-sequence power of each branch line is calculated by each power direction identification device, and the direction of the real-time zero-sequence power of each branch line is judged. If a certain real-time zero-sequence power direction is that the branch line flows to the bus, then the branch line The line has a single-phase ground fault. 2.根据权利要求1所述的城轨中压系统单相接地故障线路识别方法，其特征在于，还包括如下步骤：2. The method for identifying a single-phase ground fault line in an urban rail medium voltage system according to claim 1, further comprising the steps of: 步骤4，功率方向识别装置向对应的且存在单相接地故障的分支线路上的断路器发送断开信号，使得该分支线路从母线上断开。Step 4: The power direction identification device sends a disconnection signal to the circuit breaker on the corresponding branch line with the single-phase ground fault, so that the branch line is disconnected from the bus. 3.根据权利要求1所述的城轨中压系统单相接地故障线路识别方法，其特征在于，功率方向识别装置为功率方向继电器和/或微机保护装置。3 . The method for identifying a single-phase ground fault line in an urban rail medium voltage system according to claim 1 , wherein the power direction identification device is a power direction relay and/or a microcomputer protection device. 4 . 4.一种城轨中压系统单相接地故障线路识别系统，其特征在于，包括电压互感器、各个零序电流互感器以及各个功率方向识别装置；4. A single-phase ground fault line identification system for an urban rail medium voltage system, characterized in that it comprises a voltage transformer, each zero-sequence current transformer and each power direction identification device; 电压互感器用于安装在母线上，对母线的零序电压进行实时测量；The voltage transformer is used to install on the busbar to measure the zero-sequence voltage of the busbar in real time; 各个零序电流互感器用于分别安装在母线的各个分支线路上，对各个分支线路的零序电流进行实时测量；Each zero-sequence current transformer is used to install on each branch line of the busbar, and measure the zero-sequence current of each branch line in real time; 各个功率方向识别装置均与电压互感器电连接，用于获取母线的零序电压；Each power direction identification device is electrically connected to the voltage transformer for obtaining the zero-sequence voltage of the bus; 各个功率方向识别装置还分别各个零序电流互感器电连接，用于获取各个分支线路的零序电流；Each power direction identification device is also electrically connected to each zero-sequence current transformer, so as to obtain the zero-sequence current of each branch line; 各个功率方向识别装置用于根据零序电压以及各个零序电流计算各个分支线路的实时零序功率，并判断各个分支线路的实时零序功率的方向，若某个实时零序功率方向为分支线路流向母线，则发出该分支线路存在单相接地故障的关断信号。Each power direction identification device is used to calculate the real-time zero-sequence power of each branch line according to the zero-sequence voltage and each zero-sequence current, and determine the direction of the real-time zero-sequence power of each branch line, if a real-time zero-sequence power direction is a branch line If it flows to the bus, it will send a shutdown signal that there is a single-phase ground fault in the branch line. 5.根据权利要求4所述的城轨中压系统单相接地故障线路识别系统，其特征在于，还包括各个断路器；5. The single-phase-to-ground fault line identification system of an urban rail medium-voltage system according to claim 4, further comprising each circuit breaker; 各个断路器用于分别串联在各个分支线路上，用于根据关断信号对各个分支线路进行通断控制；Each circuit breaker is used to be connected in series on each branch line, and is used to control the on-off of each branch line according to the shutdown signal; 各个功率方向识别装置还分别与各个断路器电连接，用于在判断出存在单相接地故障时，将关断信号发送至对应的断路器。Each power direction identification device is also electrically connected to each circuit breaker, and is used for sending a shutdown signal to the corresponding circuit breaker when it is determined that there is a single-phase grounding fault. 6.根据权利要求4所述的城轨中压系统单相接地故障线路识别系统，其特征在于，功率方向识别装置为功率方向继电器和/或微机保护装置。6 . The single-phase-to-ground fault line identification system of an urban rail medium voltage system according to claim 4 , wherein the power direction identification device is a power direction relay and/or a microcomputer protection device. 7 .
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Application publication date: 20210409