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State quantity differential protection method for distribution network with distributed generation

A distributed power supply and differential protection technology, applied in emergency protection circuit devices, electrical components, etc., can solve problems such as refusal to operate, difficult to set, and difficult to set protection

Active Publication Date: 2017-06-13
CHINA SOUTHERN POWER GRID COMPANY +1
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

However, the access of DG to the distribution network also brings new problems and challenges to the protection of the distribution network
After DG is connected to the distribution network, the impact on the original distribution network protection includes: 1) The original distribution network protection is based on the traditional radial distribution network configuration. After DG is connected to the distribution network, the distribution network It has become a multi-source network with two-way flow of power. The impact of DG access on the original protection is manifested as boosting current, external current (drawing current) and reverse current; 2) The output of DG has intermittent and random fluctuations , the protection is not easy to adjust after DG access
Therefore, the access of DG changes the fault current distribution of the distribution network and the basic conditions of the original distribution network protection configuration, so that the original distribution network protection may refuse to operate or malfunction, and the protection is not easy to set

Method used

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  • State quantity differential protection method for distribution network with distributed generation
  • State quantity differential protection method for distribution network with distributed generation
  • State quantity differential protection method for distribution network with distributed generation

Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0049] Embodiment 1, for the intelligent distributed implementation scheme, DG is connected to the busbar and / or DG T is connected to the distribution network on the line, such as Figure 6 As shown, the state quantity differential protection method of the distributed power distribution network of the present invention includes the following steps:

[0050] 1. The line protection terminal determines the state quantity characteristics of the protection element (boundary switch) connected to it, and sends it to the line protection terminals of other boundary switches in the protection area through the communication network, and receives the transmission from the line protection terminals of other boundary switches state quantity characteristics. If the line protection terminal detects that the voltage transformer PT of the boundary node connected to it is disconnected, it will generate a "PT disconnection alarm" signal, and send the "PT disconnection alarm" signal to the line pr...

Embodiment 2

[0054] Embodiment 2, for the regional centralized implementation scheme, there is a distribution network where DG is connected to the busbar and / or DG T is connected to the line, and there is a regional protection master station connected to the communication network of each line protection terminal, and each line protection terminal Send the state quantity characteristics of the protection element (boundary switch) connected to it to the area protection master station, and the area protection master station judges the protection area where the fault is located according to steps 2 to 4 of Embodiment 1, and sends the instruction for the protection action exit To the line protection terminal of the node in this area, the protection action exits.

[0055] The protection method of the medium-voltage distribution network in the prior art generally uses the current quick break as the main protection, and the third-stage overcurrent protection as the backup protection.

[0056] Howe...

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Abstract

The invention discloses a state variable differential protection method for a power distribution network accessing to a distributed power supply with an aim to solve the technical problem about effective protection of the power distribution network with the distributed power supply connected therein. The state variable differential protection method includes that a line protection terminal judges state variable characteristics of a boundary switch of nodes connected with the line protection terminal, the state variable characteristics are shared with the line protection terminal of the boundary switch in the power distribution network via a communication network, boundary nodes are under the overcurrent state, fault location is in a protection area, and an action exit is protected. Compared with the prior art, the state variable differential protection method has the advantages that a power distribution network line is divided into a plurality of areas by the aid of a line switch, a section switch, a load switch and other switches, one of the area is taken as a protecting object, the fault in the area is judged by generated overcurrent fault sate and the fault location, the action exit is protected, and the power distribution network accessing to the distributed power supply is effectively protected.

Description

technical field [0001] The invention relates to a protection method for a medium-voltage distribution network in an electric power system, in particular to a differential protection method including a distributed power supply connected to a distribution network. Background technique [0002] Distributed generation (DG) is a new type of electric energy, including photovoltaic power generation system, wind power generation system, micro gas turbine power generation system, etc. Distributed power generation technology has a series of advantages such as environmental protection and economy, and can well meet people's requirements for power safety, stability and economic environmental protection. It has attracted widespread attention and has been gradually promoted and developed. However, the access of DG to the distribution network also brings new problems and challenges to the protection of the distribution network. After DG is connected to the distribution network, the impact...

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): H02H7/26
Inventor 刘年文安魏承志黄维芳李正红金鑫杨颖安姜超叶志锋许永军
Owner CHINA SOUTHERN POWER GRID COMPANY