method and protection device for avoiding protection malfunction caused by DC voltage offset

Abstract

The invention discloses a method and protection device for avoiding protection malfunction caused by a DC voltage offset. The method includes a step S1 of monitoring, by the protection device, the operation state of primary equipment and the DC voltage offset of an outlet relay; a step S2 of determining the sequence of the primary equipment fault and the DC voltage offset fault detected by the protection device, executing the step S3 if the primary equipment fault is detected firstly, or executing the step S4 if the DC voltage offset fault is detected firstly; a step S3 of starting, by the protection device, a protection outlet circuit, wherein a DC blocking module in the circuit is always in an on state; and a step S4 of starting, by the protection device, a DC offset blocking outlet circuit, wherein a DC offset blocking module in the protection outlet circuit is in an off state. The method solves the protection malfunction caused by the DC voltage offset, and guarantees that, when the DC voltage offset and a power grid short-circuit fault occurs one after another, a protection tripping outlet is completely unaffected by the blocking circuit.

Description

Technical field [0001] The invention belongs to the field of relay protection, and relates to a method and a protection device for preventing protection from misoperation caused by a DC voltage offset. Background technique [0002] The DC system of the substation provides DC power for protection, standby automatic switching, stability control, and measurement and control devices. It is one of the most important public equipment. Both DC grounding and DC parasitics will cause the DC voltage to shift, which may cause protection to malfunction, which is a major safety hazard leading to power outages. [0003] DC grounding and DC parasitic defects often occur. The statistical data of a large regional power grid in the past three years shows that these two types of defects account for 13% of the total secondary loop defects. In particular, DC voltage offsets caused by DC grounding and DC parasitics have led to multiple power outages. Therefore, it is of vital significance to study the...

AI Technical Summary

Problems solved by technology

[0009] The technical problem to be solved by the embodiments of the present invention is to provide a method and protection device for preventing protection maloperation caused by DC voltage offset, and to solve the problem of major safety hazards caused by DC voltage offset causing protection malfunction and power failure accidents

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