Fault discrimination method based on virtual current phase comparison for protecting bus bar system

Abstract

The disclosed method includes following steps: according to fixed sampling interval, each branch is sampled. Sampled data are stored in relevant storage area. Processed result is as reference for determining positive or negative branch current. Virtual current and restraint coefficient K of virtual current are calculated. Based on result of calculating restraint coefficient of virtual current, running state of bus is determined. If the calculated result is larger than Kz, then it is indicated that bus system is in fault state; otherwise, the bus is in normal running state or fault occurs out of this region. The method eliminates high-frequency components effectively. The invention raises speed of protection action, suitable to calculate rapid catastrophe variables under ensuring sensitivity and interference killing feature of protection. The method is suitable to each bus system under 750 kV.

Description

technical field [0001] The invention relates to the technical field of electric power system relay protection, in particular to a method for busbar system protection. Background technique [0002] The implementation of "West-to-East Power Transmission" is a major strategy for my country's electric power development. During the "Tenth Five-Year Plan" period, the country will focus on accelerating the construction of power and transmission lines for the southern line of "West-to-East Power Transmission". At present, the development of my country's power grid has formed two major trends: one is to form a long-distance, large-capacity power transmission pattern such as west-to-east power transmission and north-to-south power transmission. The second is to realize the intensive development and interconnection of large regional power grids. In terms of limiting short-circuit current levels, line corridors, transmission capacity, and network security, the existing 500KV highest vo...

AI Technical Summary

Problems solved by technology

Existing busbar protection either uses differential current discrimination, or uses sampling value proportional brake differential, differential current discrimination uses the magnitude of differential current to judge busbar faults, and the magnitude of differential current is less affected by the operating status of the busbar system Large, so the sensitivity is not high

The method of direct sampling value proportional braking is used to judge the bus fault. If there is a high-frequency component in the process of transient fault protection, it will have a relatively large impact on the operating performance. For the 750KV UHV bus system, the possibility of malfunction is greatly increased.

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