Inter-phase short circuit and single-phase grounding comprehensive protection method for small-current grounding power system

Abstract

The invention discloses an inter-phase short circuit and single-phase grounding comprehensive protection method for a small-current grounding power system. Firstly, a protection device collects three phases of current and zero-sequence voltage and calculates break variables of each phase of current and the zero-sequence voltage in real time; then, whether the break variables of the phases of current exceed a threshold is detected, if the break variables of the phases of current exceed the definite value, it is judged that an inter-phase short circuit fault exists, and a stage current protection procedure is started; otherwise, whether the break variable of the zero-sequence voltage exceeds the threshold is detected, if the break variable of the zero-sequence voltage exceeds the definite value, it is judged that a single-phase grounding fault exists, and a single-phase grounding line selection procedure is started. The method integrates an inter-phase short circuit protection function and a small-current grounding line selection function, tripping is quickly and reliably conducted when the inter-phase short circuit fault happens, and a line can be accurately selected and a warning signal is sent out when single-phase grounding happens to the small-current grounding system. When the protection method is used, people only need to configure one inter-phase short circuit and single-phase grounding comprehensive protection device at the front end of each led-out line and do not need to arrange a small-current grounding line selection device independently any more, and protection configuration is effectively simplified.

Description

technical field [0001] The invention belongs to the field of power systems, relates to the field of relay protection of power systems, and in particular relates to a comprehensive protection method for phase-to-phase short-circuit and single-phase grounding of a small-current grounding power system. Background technique [0002] In the medium and low voltage distribution network, each outgoing line is usually equipped with a staged current protection device. When a phase-to-phase short-circuit fault occurs, an obvious short-circuit current will flow through the protection installation. Determine if the fault is in or out of the zone, and quickly remove the fault within the zone. [0003] In order to improve the operation reliability of the power system, the medium and low voltage distribution network in my country usually adopts the low current grounding operation mode. When a single-phase grounding fault occurs on a certain line, there will be no obvious fault current. At ...

AI Technical Summary

Problems solved by technology

However, each substation must be equipped with a separate line selection device, which not only increases the construction cost, but also makes the operation and maintenance more complicated

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