Simulation on TRV characteristics and limiting methods of series compensated UHV lines

Summary

Accompanying with the development of UHV power grid in China, it is imperative that compensation of high degree should be employed to increase the transmission capacity and to improve the transient stability of the network which leads difficulties to line circuit breakers when breaking short circuits. Higher transient recovery voltage (TRV) will occur due to the trapped charge on series capacitor, which can greatly exceed the current standards of 1 100 kV circuit breakers and consequently lead to a higher probability of breaking failure. In this paper, a simulation platform on series compensated UHV line was established by PSCAD/EMTDC according to typical electrical parameters of Chinese UHV girds and a radial 4-source network recommended by CIGRE. TRVs in various breaking conditions have been simulated. Simulation results showed that the maximum peak value of TRV and rate of rise of recovery voltage (RRRV) in 40% or higher compensated transmission lines exceed the current standards for UHV circuit breakers when clearing 3LG faults. Thus, measures should be taken to restrict the TRV level in series compensated UHV transmission lines. Common measures to limit TRV, such as installing paralleled resistor or MOV to the circuit breaker, scattered installing the series capacitors at both ends of the transmission lines, and forced fast bypassing of series capacitors have been simulated and discussed in this paper. It is found that by these measures TRV level can be decreased to some extent. However, methods mentioned above are mostly not effective enough and the TRV peak and RRRV are still in excess of standards under certain breaking conditions. Thus, new TRV suppressing strategies should be adopted to resolve the TRV problem in highly compensated UHV transmission lines. Otherwise, the testing TRV standards of circuit breakers should be renewed and UHV circuit breaker with higher TRV endurance should be developed.

Additional informations

Authors

Siderakis Kiriakos, Müller Matthias, Mikropoulos Panteli, Katsarakis Nikolaos, Ma Qiyan, Han Ya'nan, Wang Song