Characteristics of Transient Recovery Voltage of Circuit Breakers in UHV AC Half-wavelength Transmission System

Because of the unique characteristics of half-wavelength transmission lines, the transient recovery voltage(TRV) characteristics of the circuit breaker are different from those of the conventional lines when short circuit fault occurs on the line. We established a simulation model of UHV half-wavelength AC transmission system. Moreover, we studied the characteristics of short-circuit current and TRV of circuit breaker during interrupting short-circuit fault at different positions, analyzed the relevant influencing factors, and proposed the limitation measures of TRV. The study results show that the short-circuit current and TRV of circuit breaker for half-wavelength line are greatly affected by the position of the fault. When the ground fault occurs at the remote end of 2 500~3 000 km from the circuit breaker, the short-circuit current of the circuit breaker is high and may exceed the short circuit current during the circuit breaker terminal fault. Also, the TRV peak and the rate of rise of TRV are much higher than the allowable values of the circuit breaker test in the current standard. Metal oxide arrester(MOA) installed along the half-wavelength line helps to reduce the TRV, by suppressing the overvoltage on the line generated by the ground fault. However, the TRV still exceeds the allowable value in some cases. With the measure of opening resistor installed on circuit breaker together with MOA along the line, the TRV can be limited to the allowable value of current standard. © 2018, High Voltage Engineering Editorial Department of CEPRI. All right reserved.