Electrical Model and Structure Parameters of a new 500kV current limiting device

In order to solve the problem of short-circuit current exceeding the standard in the development of 500kV power grid, a new current limiting device based on high coupled split reactor and parallel circuit breaker is adopted, which can realize the function of equalizing the current of circuit breaker in steady-state operation and limiting current of circuit breaker in transient fault. Due to the introduction of an additional circuit breaker and a high coupling reactor in the current limiting device, there is a large transient voltage in the break of the circuit breaker and in the coupling coil when the fault occurs. In this paper, the overvoltage distribution in the new current limiting device is studied. Firstly, the basic structure of HCSR and the topological structure of main circuit are introduced, and the calculation formulas of coupling reactor and distributed capacitance are deduced. Then, the steady-state current sharing and transient current limiting processes of the parallel circuit breakers are described, and the technical effects of the current sharing process are analyzed and deduced. Last, this paper focuses on the analysis of the operation circuit in the current limiting process, and makes a theoretical analysis and a brief derivation of the current and overvoltage in the breaking process of two circuit breakers with different actions.