A stochastic-process-based method for assessing frequency regulation ability of power systems with wind power fluctuations

Abstract

The increasing penetration of wind power raises the problem of maintaining grid frequency stability. The purpose of this paper is to quantitatively describe the relationship between wind power fluctuations and grid frequency deviation. The fluctuation characteristics of wind power are analyzed in multi-time scales by wavelet methods. Then, a mathematical model representing wind power fluctuations is established. Using this model and the frequency response transfer function of power system, the frequency deviation can be obtained. A coefficient to measure the frequency regulation ability (FRA) of power system is defined as the ratio of wind power fluctuations to frequency deviations. Based on a series of calculation results of FRA in a two-area power system with large-scale wind power integration, a strategy for deploying appropriate thermal units participating in frequency regulation is proposed. In this strategy, the future frequency deviation of the system can be assessed, which helps operators to adjust the deployment of thermal units reasonably. Case studies show that this strategy can be widely applied in decreasing grid frequency deviation caused by wind power fluctuations.