A Method and an Algorithm for Implementing Relay Protection of 6(20)/0.4 kV Step-down Transformer Substations

Abstract

The article discusses a method and an algorithm for implementing the protection system for a 6(20)/0.4 kV transformer substation, using which its reliable operation is secured regardless of the grid configuration and operation mode and the operation parameters of higher-level electrical installations. The proposed method makes it possible to clear any fault in the 0.4 kV network with minimal time delays. To this end, it is necessary to supplement the 0.4 kV network with current transformers (if they are not available) and forward the algorithm control output to the circuit breaker tripping coils. To ensure short-range backup protection, the circuit breakers protective functions remain in operation. Based on the existing electrical network, the approximate pickup parameters of the proposed method are pointed out, and recommendations for their optimization are given. Various contingencies in the 0.4 kV electrical network are considered to verify the correct functioning of the proposed relay protection method and algorithm.