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Control and protection method of single-phase ground fault in station of bipolar flexible direct current transmission system

A single-phase ground fault, flexible DC technology, applied in the direction of emergency protection circuit devices, electrical components, etc., can solve problems such as sub-module overvoltage, AC current DC bias, and AC circuit breakers cannot be normally disconnected

Active Publication Date: 2019-03-08
STATE GRID LIAONING ELECTRIC POWER RES INST +2
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

When a single-phase ground fault occurs on the AC busbar in the station, the fault characteristics are the most serious. It will cause the AC current to be biased against the DC, resulting in the failure of the AC circuit breaker to be disconnected normally; even if the converter is blocked, the DC line will continue to charge the bridge arm sub-module , resulting in severe overvoltage of the sub-module

Method used

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  • Control and protection method of single-phase ground fault in station of bipolar flexible direct current transmission system

Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0082] The single-phase ground fault control and protection method in a station of a bipolar flexible direct current transmission system includes the following steps:

[0083] Step 1: Determine whether a single-phase ground fault occurs in the first sending-end voltage source converter, and if so, perform step 2, and switch the first receiving-end voltage source converter to STATCOM operation mode or make the first receiving-end voltage source The converter is in a locked state;

[0084] Step 2: Make all the sub-modules in the first sending-end voltage source converter in a locked state, and trigger the bypass thyristors in the sub-modules to turn on the bypass thyristors;

[0085] Step 3: Make the neutron module of the lower bridge arm that does not have a single-phase ground fault occur in the cut-off state;

[0086] Step 4: Determine whether the current flowing through the first AC circuit breaker at the sending end has a zero-crossing point, if so, perform step 8, otherwi...

Embodiment 2

[0100] The single-phase ground fault control and protection method in a station of a bipolar flexible direct current transmission system includes the following steps:

[0101] Step 1: Determine whether a single-phase ground fault occurs in the first receiving-end voltage source converter, and if so, perform step 2, and switch the first sending-end voltage source converter to STATCOM operation mode or make the first sending-end voltage source The converter is in a locked state;

[0102] Step 2: Make all the sub-modules in the first receiving-end voltage source converter in a locked state, and trigger the bypass thyristors in the sub-modules to turn on the bypass thyristors;

[0103] Step 3: Make the neutron module of the lower bridge arm that does not have a single-phase ground fault occur in the cut-off state;

[0104] Step 4: Determine whether the current flowing through the first receiving-end AC circuit breaker has a zero crossing point, if so, perform step 8, otherwise pe...

Embodiment 3

[0118] The single-phase ground fault control and protection method in a station of a bipolar flexible direct current transmission system includes the following steps:

[0119] Step 1: Determine whether a single-phase ground fault occurs in the second sending-end voltage source converter, and if so, perform step 2, and switch the second receiving-end voltage source converter to STATCOM operation mode or make the second receiving-end voltage source The converter is in a locked state;

[0120] Step 2: Make all the sub-modules in the second sending-end voltage source converter in a locked state, and trigger the bypass thyristors in the sub-modules to turn on the bypass thyristors;

[0121] Step 3: Make the neutron module of the lower bridge arm that does not have a single-phase ground fault occur in the cut-off state;

[0122] Step 4: Determine whether the current flowing through the second AC circuit breaker at the sending end has a zero-crossing point, if so, perform step 8, ot...

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Abstract

The invention provides an in-station single-phase grounding fault control protection method for a bipolar flexible direct current power transmission system. After a voltage source transverter in which an in-station single-phase grounding fault occurs is locked, a lower bridge arm submodule of a non-single phase grounding fault phase is triggered to be a cutoff state again, alternating current direct current bias can be rapidly reduced, and the problem of submodule overvoltage caused by non-fault phase alternating voltage is avoided, thereby reducing fault removing time and overvoltage strain of a transient submodule; and closing a high-speed bypass switch of the lower bridge arm submodule of the non-single phase grounding fault phase can effectively solve the problem of alternating current direct current bias and the problem of submodule overvoltage, thereby guaranteeing normal switching-off of an alternating current circuit breaker, and protecting the transverter to the greatest extent.

Description

technical field [0001] The invention relates to a control and protection method, in particular to a single-phase ground fault control and protection method in a station of a bipolar flexible direct current transmission system. Background technique [0002] Flexible DC transmission technology is a new type of DC transmission technology. A reasonable control and protection strategy determines the safe and stable operation of the flexible DC transmission system. Its flexible application performance makes it have broad application prospects in the fields of urban power grid interconnection, clean energy grid connection, and island power supply. With the increase of transmission capacity and the improvement of power supply reliability, some scholars have proposed bipolar flexible DC transmission system. However, the fault characteristics of the bipolar flexible HVDC transmission system are quite different from those of the single-stage flexible HVDC transmission system. Especial...

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): H02H7/26
CPCH02H7/268
Inventor 周杨贺之渊张艳军庞辉杨杰李强马巍巍那广宇张钊白雪
Owner STATE GRID LIAONING ELECTRIC POWER RES INST
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