An Exact Method for Computing the Delay Margin for Power System Using Sweeping Test

The time delay is unavoidable in a power system and it degrades the performance of the system or even destabilizes the system. Determining the maximum delay margin is crucial for power system operators. In this paper, we introduce a precise method for delay margin computation. The method is based on converting the transcendental characteristic equation into a frequency dependent equation. The crossing frequencies are determined using the spectral radius which results in exact delay margin values. A single-machine infinite bus power system is selected as a simple case study. The validity of the proposed method has been proved through comparing with the most recent research work. The effects of the gain of the exciter, the mechanical power of the generator and the generator damping on the delay margin are studied. The delay margin decreases with increasing the gain of the exciter and the generator mechanical output. While the delay margin has negative trend for small values of the damping and positive trend for large damping values.