engleski

Selection of station surge arresters for control of slow-front overvoltages on compact lines

Compact upgraded lines have shorter clearances compared to standard lines of the same voltage level, so they require the use of efficient techniques to reduce overvoltages in order to avoid phase to ground or phase to phase flashovers. The use of station arresters with a low protection level at the terminals of the line might be the best solution for the reduction of the slow-front overvoltages (SFO) due to energization or reclosing of the line. This low protection level requires the use of arresters whose rated voltage should be selected very carefully regarding the level of the temporary overvoltages (TOV) that could appear in the system. The paper is analyzing the feasibility of using station arresters subjected to TOV because of their lower rated voltage. These surge arresters are installed at both terminals of a compact line upgraded from 225 kV to 400 kV and are aiming at reducing some SFO. The energy stresses of station surge arresters were studied for different network configurations, short circuit currents, types of faults and rated voltages of arresters. These configurations combine the effect of load shedding, Ferranti effect and earth fault. The methodology and modelling of elements to perform the study is described in the paper. The parametric study was conducted analyzing the energy stressing the arrester versus: the protective level of the surge arresters ; the level of TOV ; the duration of TOV. Simulations were performed on simple configurations, using the EMTP-RV software, with surge arresters of rated voltages 342 kV and 330 kV, energy class 4.

TOV; Ferranti effect; earth fault; selection of station surge arrester; energy stress; compact upgraded line; EMTP-RV

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