A Novel Positive Sequence Impedance Differential Protection Method for Microgrid

Abstract

The invention discloses a novel positive sequence impedance differential protection method of a microgrid. The method comprises the following steps of acquiring a three-phase current and a three-phase voltage in real time, and further calculating positive sequence impedance at a protection installation position; carrying out calculation of action impedance and braking impedance; judging whether a differential protection region is a fault section or not by a local-side protection device after receiving positive sequence impedance information of an opposite side of the differential protection region through a communication network; and additionally arranging a phase-comparison distance component in a detection blind region subjected to the positive sequence impedance differential protection for identifying a three-phase metal fault. The method can be suitably used for two running states of grid connection and island of the microgrid, the influence of through current and large transition resistance on fault detection during a fault is fully considered, moreover, the method is implemented without the assistance of synchronous signal acquisition and a fault component, the complicated network structure of the microgrid and the problem brought to microgrid protection by variable running states are effectively solved, and the protection selectivity and reliability are ensured.

Description

technical field [0001] The invention relates to the technical field of electric power system relay protection, in particular to a positive-sequence impedance differential protection method suitable for the operating characteristics of a micro-grid. Background technique [0002] The complex network structure and flexible operation characteristics of the microgrid make it difficult for the traditional distribution network protection to operate correctly, and even the direct application of the transmission network protection with superior protection performance to the microgrid also faces challenges. The operation mode of the microgrid is flexible and changeable, and there are obvious differences in the amount of fault electricity under different operation modes. In the island operation state, the amplitude of the short-circuit current is obviously smaller than that in the grid-connected state. It is difficult to guarantee the protection according to the setting principle of the...

AI Technical Summary

Problems solved by technology

The method of the present invention fully considers the impact of the through current and large transition resistance on fault detection during faults, and effectively solves the complex network structure and variable operating status of the microgrid without the aid of synchronous signal acquisition and fault components The problems brought about by microgrid protection ensure the selectivity and reliability of protection

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