Determination of worst case line energization overvoltages

An optimization methodology, is presented, for the automatic determination of the maximum transient overvoltage due to transmission line energization. The approach is based upon digital simulations of the electromagnetic phenomena, and uses a modified version of the Hooke and Jeeves direct search nonlinear optimization method, specially adapted to the particular characteristics of the problem, for the determination of the closing times of the circuit breaker poles which cause the maximum transient line energization overvoltage. Results are presented for the application of the proposed technique to different test cases, including transmission lines from 115 kV to 765 kV from the Venezuelan electric system. The overall method is shown to be accurate and reliable.