285 / 2022-03-15 03:05:34

The Evaluation Method for the Breaking Capacity of Circuit Breakers Based on the KEMA Arc Model Combined With Circuit Simulation

Circuit Breakers; Breaking Capacity; the KEMA Arc Model

With the development of smart grid and UHV grid, the physical form and operation characteristics of power grid have experienced significant changes. Consequently, many high-voltage circuit breakers face the problem that the time constant of the DC component of the short-circuit current exceeds the standard time constant with the increased X/R value of the power system. It not only affects the reliability of the circuit breaker, but also poses a potential threat to the safe and stable operation of the system. Therefore, it is essential to check the breaking capacity of the circuit breaker whose DC component exceeds the standard to ensure its normal operation.

Therefore, this paper establishes a black-box arc simulation model, and proposes a method of adapting the KEMA arc model combined with circuit simulation to evaluate whether the existing circuit breaker can break the short-circuit current with a time constant greater than the standard time constant in the actual power system. The method will determine the critical parameters of the KEMA arc model according to the rated breaking capacity of the circuit breaker, and then use the model to simulate the actual short-circuit current breaking, and predict the breaking of the circuit breaker when the time constant of the DC component of the short-circuit current increases.

In this paper, the 330 kV/63 kA circuit breaker in Shapotou Substation is taken as an example to evaluate the actual short-circuit breaking capacity of the circuit breaker based on the KEMA arc model simulation method. The results show that when the influence of the DC component is not considered in the rated breaking of the circuit breaker, the critical arc parameters obtained by the simulation cannot break the actual short-circuit current containing the DC component. When the DC component is increased by 20% in the rated breaking capacity, the power of the gas arc increases, so the heat dissipation power constant of the arc is two orders of magnitude larger than that without considering the DC component, and the time constant is reduced by two orders of magnitude. The simulation results show that the critical arc parameters at this time can successfully break the actual current containing the DC component. That is, the simulation method of the KEMA arc model can check the ability of the high-voltage AC circuit breaker of the power system to break asymmetric short-circuit currents with high DC components, ensure the reliable breaking of the high-voltage AC circuit breaker, and improve the stability of the power system.