A small resistance switching method for single-point ground fault location in multi-terminal DC system

Abstract

The invention provides a small resistance switching method for single-point grounding fault location of a multi-terminal DC system. Sequence voltage criterion logic and DC voltage unbalance criterion logic, the DC control and protection host judges whether a fault has occurred; Step 3: If a single-point ground fault occurs, the DC control and protection host executes the neutral point small resistance switching logic; If no single-point ground fault occurs, return to step 2 to continue judging; step 4: DC control and protection host performs fault location; step 5: DC control and protection host performs fault isolation. This method can quickly identify single-point grounding faults, quickly switch small resistors, and provide a strong guarantee for the DC control and protection host to quickly locate and isolate faults, so as to improve the safety and reliability of the DC system.

Description

technical field [0001] The invention belongs to the technical field of flexible DC power distribution control and protection, and in particular relates to a small resistance switching method for single-point ground fault location in a multi-terminal DC system. Background technique [0002] Each end of the multi-terminal DC system is interconnected by DC lines. When a single-point ground fault occurs in the system, each end will inject fault current into the fault point. If the fault location and isolation cannot be carried out in time, the expansion of the fault range will cause the entire multi-terminal DC System outage or even damage to equipment. Most of the existing 10kV multi-terminal DC systems use a large resistance (3750 ohm) grounding method. When a single-point grounding fault occurs, the fault current is small, and the differential protection cannot meet the requirements for operational reliability, which has a great impact on the safe operation of the system. ha...

AI Technical Summary

Problems solved by technology

[0002] Each end of the multi-terminal DC system is interconnected by DC lines. When a single-point ground fault occurs in the system, each end will inject fault current into the fault point. If the fault location and isolation cannot be carried out in time, the expansion of the fault range will cause the entire multi-terminal DC System outage or even damage to equipment

Most of the existing 10kV multi-terminal DC systems use a large resistance (3750 ohm) grounding method. When a single-point grounding fault occurs, the fault current is small, and the differential protection cannot meet the requirements for operational reliability, which has a great impact on the safe operation of the system. the danger of

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