Research on TRV transient characteristics of EHV controllable series compensation line

Affected by the capacitive reactance of the series compensation and the residual voltage of the capacitor, the controllable series complementary line in the event of a short-circuit fault. The transient recovery voltage (TRV) characteristics of the circuit breaker are significantly different from those of conventional lines. To this end, taking the EHV demonstration project line as the background, based on the steady-state working characteristics of the TCR branch, the controllable series compensation simulation model is established. The influence of the thyristor valve on the conduction state of TCSC under the steady-state operation condition of the system is proved. On this basis, a single-phase grounding fault is simulated on the line, combined with the short-circuit current, the influence of the three stages of the circuit breaker opening process on the TRV characteristics is analyzed, and the trend of the TRV peak value is analyzed for different factors such as the time of failure and the distance of the fault. Simulations show that the TCSC operates capacitively with the thyristor valve on 3 times and off 2 times during the frequency cycle and that the DC component of the TCR branch currently has a superimposed effect on the capacitor current when the thyristor valve is on. When the thyristor valve is turned on, the capacitor current is superimposed by the DC component of the TCR branch current. The TRV generated by the circuit breaker in the event of an earth fault on the rear side of the series complementary station is significantly higher than that on the front side, with a peak of up to 1422.21 kV. The results of the study have reference values for the engineering design of EHV transmission lines.