A comprehensive protection method for microgrid based on improved search protection and differential protection

Abstract

The invention relates to a microgrid comprehensive protection method based on improved search protection and differential protection. The method comprises steps that firstly, a bus voltage is monitored, and a feeder line is started to search main protection when the bus voltage drops obviously or obvious positive sequence, negative sequence and zero sequence voltages appear in a bus, the feeder line search main protection adopts a protection method for searching the phase difference between a bus positive sequence voltage component and each feeder line positive sequence current component, thirdly, on the basis of feeder line search main protection, in combination with differential protection, tie line phase differential protection and backup protection are designed, and the comprehensive protection strategy is formed. The method is advantaged in that safety of each bus, each tie line and each feeder line can be effectively protected when the micro-grid fails, and reliability of the micro-grid is enhanced, the comprehensive protection method does not depend on the fault current with small amplitude in the microgrid, and can accurately and effectively identify the fault position andcut off a fault feeder line, and the method is suitable for various working conditions such as a symmetric fault, an asymmetric fault and a communication fault, and has relatively high reliability.

Description

technical field [0001] The invention relates to the technical field of power system protection, in particular to a micro-grid comprehensive protection method based on improved search protection and differential protection. Background technique [0002] As a way to popularize new energy, microgrid effectively organizes various distributed power sources, energy storage devices, loads, etc., and solves a series of problems such as difficult control of distributed power sources and power supply in remote areas. The microgrid can not only run in parallel with the large power grid, but also operate as an island in an off-grid state. However, there are differences between the microgrid and the traditional distribution network in terms of power characteristics and operation modes. [0003] After the distribution network is connected to the microgrid with distributed power generation, the short-circuit current, voltage and power flow of the grid-connected point system are affected t...

AI Technical Summary

Problems solved by technology

The differential current detection method based on full current can effectively detect single-phase ground faults, but cannot identify phase-to-phase faults and three-phase symmetrical faults

The method of identifying the fault area based on the fault current can adaptively adjust the fault search path according to the fault situation, but the structural adaptability is poor

Wide-area protection also includes the method of calculating the system in real time and selecting system impedance, adjusting the setting value, and judging the type of fault, but this method is too dependent on communication devices, and has relatively high requirements for real-time data and fault tolerance

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