A Unit Commitment-Enabled Low-Order Approximator for High-Order Power Grid Frequency Dynamics

Frequency response analysis under disturbance plays an important role in power system security awareness. However, massive high-order components, as well as discrete variables such as unit commitment (UC), induce immense challenges in analyzing frequency security. To conquer this barrier, a low-order frequency response approximator that adapts to UC is proposed. At the outset, first-order dynamics are applied to model governor responses, such that an average system frequency (ASF) approximator lays the first stone. Then, a module that approximates UC impacts is introduced in the ASF model. Finally, by modelling parameter identification of the ASF as a optimization problem, genetic algorithm is used to enable an precise equivalent low-order ASF for real-world high-order frequency dynamics. The numerical study on a provincial power grid in southwest China verified accuracy and universality of proposed method.