Research On Modeling Of High Coupled Split Reactor For Fault Current Limiter

With the rapid increase of power system load,the short-circuit current in load-intensive areas has approached or even exceeded the interrupting capacity of the circuit breaker.Installing fault current limiter(FCL)based on high coupled split reactor(HCSR)is a reliable and economical short-circuit current limiting measure.Due to the complicated structure of HCSR,when FCL changes from current sharing to current limiting state(by opening fast switches inside FCL),the k Hz-level transient voltages may threaten the insulation between terminals of HCSR and the insulation of fast switches.In order to study the above process by electromagnetic transient simulation,it is necessary to establish a four-port wideband model of HCSR.Therefore,this paper studys the specific modeling method of HCSR for FCL,and simulates the transient process of a 500 kV FCL by establishing a 500 kV HCSR model.Firstly,starting from the winding structure of HCSR,the winding equivalent circuit is established.On this basis,the method suitable for calculating high-frequency admittance parameters of HCSR in 1 k Hz-1 MHz is obtained.To verify the calculation method,high-frequency admittance parameters of a HCSR prototype are calculated and measured.The comparisons of the calculation and measurement results verify the correctness of the calculation method.This calculation method lays the foundation for the modeling of HCSR.Secondly,by studying the realization method of each modeling step,the specific modeling method of HCSR is obtained.Based on the calculation methods of low-frequency and high-frequency admittance parameters,the admittance parameter matrices of HCSR in working frequency band(10 Hz-1 MHz)are obtained by parameter integration.The parameter matrices are fitted by vector fitting and passive correction.And by the frequency dependent network equivalent component in PSCAD,the equivalent circuit is established,which means the modeling is completed.Using this modeling method,the HCSR prototype is modeled.To verify the model,admittance parameters of the model and the prototype are compared,and time-domain characteristics of the model are simulated.The comparison and simulation results prove the correctness of the prototype model and the modeling method.Finally,by the modeling method,a 500 kV HCSR in design stage is modeled.Based on this model,the transient simulation of a 500 kV FCL is carried out.When different short-circuit faults occur,the transient processes of the FCL changing from current sharing to current limiting state are simulated.The transient voltages between terminals of the HCSR and the transient recovery voltages of the fast switches are obtained,which provide a reference for design and selection of the 500 kV HCSR and the fast switches.