Control strategy of transformer coupling solid state fault current limiter and its experimental study with capacitance load

In this paper, the control strategy of transformer coupling three phase bridge type solid state fault current limiter (TC-SSFCL) is presented. It is validated in an experimental system. It´s proved that the control strategy ensures TC-SSFCL has excellent control performance and current-limiting effectiveness in its normal startup, operation and current-limiting conditions. Issues faced by TC-SSFCL in a double-side power system are analyzed and solutions are suggested. The series resonance which appears in the test of TC-SSFCL with capacitance load is analyzed in detail. To suppress the resonance, both methods, pre-triggering the SCR bridge and adding a damping resistance in parallel with the coupling transformer, are discussed. The simulation results verify that the proposed strategies for suppressing the resonance are effective.