A novel self-adaptive underfrequency load shedding method based on local measurements

Abstract

This paper puts forwards a novel adaptive underfrequency load shedding method preventing system collapse under severe active-power deficits. The method has advantages over existing self-adaptive schemes in that it can accurately estimate the actual active-power deficit without knowing the system equivalent inertia, system boundary or constructing a control center. The method only measures the local load active-power, local frequency and the rate of change of frequency to obtain the control quantity. The decentralized implementation ensures the high reliability and simplicity of the method. The algorithm theory is strictly derived to show the correctness of the method. The theory analytically confirms that the control accuracy is equal to the existing adaptive ones and that the method outperforms in both flexibility and cost. Based on the theory, the overall control structure is introduced. Simulation results on typical system with various conditions verify the control effectiveness and adaptability when compared with commonly used under-frequency load shedding schemes in China.