Microgrid protection method and system based on current polarity comparison

Abstract

The present disclosure relates to a microgrid protection method and system based on current polarity comparison. Wherein, the method includes: configuring the unit protection module at the branch line of the microgrid and the access point of the distributed power supply; calculating the phase difference between the pre-fault current and the fault component current of the unit protection module respectively, and according to the preset phase difference range, calculating the polarity of the unit protection module; calculating the polarity product of adjacent unit protection modules, and when the polarity product is a preset value, it is judged that there is a fault between the adjacent unit protection modules; The control circuit breaker of the adjacent unit protection module whose polarity product is a preset value is cut off, so as to realize the isolation of the fault section and complete the protection of the microgrid. Based on the polarity comparison of unit protection modules in the micro-grid, the present disclosure realizes rapid location of grid faults only by using current information, and has a simple structure and strong applicability.

Description

technical field [0001] The present disclosure relates to the field of power electronics, in particular, to a method and system for protecting a micro-grid based on current polarity comparison. Background technique [0002] Micro-Grid refers to a small power generation and distribution system composed of distributed power sources, energy storage devices, energy conversion devices, loads, monitoring and protection devices, etc. The proposal of microgrid aims to realize the flexible and efficient application of distributed power, and solve the problem of grid connection of distributed power with a large number and various forms. The development and extension of microgrids can fully promote the large-scale access of distributed power sources and renewable energy, and realize the highly reliable supply of various energy forms for loads. Smart grid transition. [0003] Now the AC microgrid protection method faces the following difficulties: 1. There is a bidirectional short-circ...

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Problems solved by technology

[0003] Now the AC microgrid protection method faces the following difficulties: 1. There is a bidirectional short-circuit current inside the microgrid, and protection is needed to judge the fault direction; Adaptively judge the fault state; 3. The topology of the microgrid will change with the change of the operation mode, and the protection needs to be applicable to different topologies; 4. In the current low-voltage network, many nodes only install current transformers, and No voltage transformer is configured, and a protection method that only uses current information needs to be constructed

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