Single-phase overlapping sequence setting method for reducing power frequency fault component distance protection misoperation rate in AC-DC system

A technology of AC and DC systems and fault components, applied in emergency protection circuit devices, emergency protection devices with automatic disconnection, parameter calibration/setting, etc., can solve problems such as commutation failure of DC systems, sudden changes in electrical quantities, etc.

Active Publication Date: 2016-09-21
KUNMING UNIV OF SCI & TECH
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

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Problems solved by technology

Compared with the pure AC system in the traditional power system, the AC-DC power system will produce more electrical characteristics during faults, such as faults in the AC system may cause commutation failure

Method used

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  • Single-phase overlapping sequence setting method for reducing power frequency fault component distance protection misoperation rate in AC-DC system
  • Single-phase overlapping sequence setting method for reducing power frequency fault component distance protection misoperation rate in AC-DC system
  • Single-phase overlapping sequence setting method for reducing power frequency fault component distance protection misoperation rate in AC-DC system

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Experimental program
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Effect test

Embodiment 1

[0218] Embodiment 1, a single-phase coincidence sequence setting method for reducing the misoperation rate of power frequency fault component distance protection in AC and DC systems, the specific steps are:

[0219] (1) The system is running normally

[0220] 1) Form a node admittance matrix under normal operation;

[0221] The method of forming the admittance matrix Y is as follows:

[0222] The order of the admittance matrix is ​​equal to the number of nodes in the power system network, the number of nodes is denoted as n, and the number of non-zero elements in the off-diagonal elements of each row of the admittance matrix is ​​equal to the number of ungrounded branches connected to the corresponding node; the admittance matrix Each diagonal element, that is, the self-admittance Y of each node ii Equal to the sum of the admittances of the branches connected to the corresponding node:

[0223] The mutual admittance Y of each off-diagonal element of the admittance matrix...

Embodiment 2

[0361] Example 2, in the Southern Power Grid in 2015, the Guangdong Power Grid has dense DC drop points, and the selection is as follows figure 1 The grid in northern Guangdong with three DC feed-in shown is the research object. Take Huadu Zhitong and the Huadu side of the 500kV AC line as an example. Huadu-Tonghe 500kV AC line Huadu side 0-cycle single-phase fault occurred, 5-cycle line head-end circuit breaker tripped, 10-cycle line end circuit breaker tripped.

[0362] When the 50-cycle Huadu side recloses first, the positive-sequence, negative-sequence, and zero-sequence voltage fault components and current fault components of each AC line protection are first calculated using the dual-port theory, and then the a, b, c of each protection are calculated using the symmetrical component method The three-phase voltage fault component and current fault component, and finally according to the power frequency fault component criterion, the measured impedance of the power frequen...

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Abstract

The invention relates to a single-phase overlapping sequence setting method for reducing a power frequency fault component distance protection misoperation rate in an AC-DC system, belonging to the electric power system protection technical field. The method employs a symmetrical component method to calculate the positive sequence and negative voltage and current at two ports, employs a superposition principle to respectively calculate the positive sequence, negative sequence, zero sequence voltage and current fault component of each node according to the voltage of each node, three sequence voltages of the two ports, and the positive sequence, negative sequence and zero sequence voltage fault component of the two ports, and calculates the three-phase voltage and current fault component of each node according to the symmetrical component method. The method calculates the measurement impedance of each distance protection power frequency fault component based on each phase voltage, current phase fault component and fault point voltage before faults. Accordingly, the measurement impedance of each protection power frequency fault component under two reclosing sequences is calculated, and an overlapping sequence corresponding to the greater measurement impedance of a power frequency fault component is selected as an optimized overlapping scheme. A lot of results show that the method has good effects.

Description

technical field [0001] The invention relates to a single-phase coincidence sequence setting method for reducing the misoperation rate of power frequency fault component distance protection in an AC and DC system, and belongs to the technical field of power system protection. Background technique [0002] In the AC-DC system, the commutation failure of the converter is one of the most common faults in the DC system. Commutation failure not only affects the safe and stable operation of the DC system, but also affects the incorrect action of the protection characteristics in the AC system at the receiving end. With the construction and operation of many DC transmission projects in my country's power system, the AC and DC power grid has gradually formed in our country. Compared with the pure AC system in the traditional power system, the AC and DC power system will produce more electrical characteristics when faults occur. For example, a fault in the AC system may cause commuta...

Claims

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Application Information

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IPC IPC(8): H02H3/00
CPCH02H3/006
Inventor 孙士云束洪春韩军强陈春敏安德超
Owner KUNMING UNIV OF SCI & TECH
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