Multi-area frequency-constrained unit commitment of renewable energy power systems with induction machine load

The increasing penetration rate of renewable energy sources (RES) brings great challenges to the frequency security of power systems. The traditional frequency-constrained unit commitment (FCUC) generally uses the center of inertia (COI) frequency index to characterize the frequency security of power system, ignoring a large number of induction machines (IMs) inertia support on the load side, which not only underestimates the security risk but also increases the operating cost. In this paper, a frequency-constrained unit commitment (FCUC) model considering load inertia of IMs is established from regional perspective. On the basis of the model, it is formulated as a mixed integer nonlinear programming (MINLP) problem. Then, the novel Benders decomposition algorithm is proposed to decompose the original MINLP problem into a master problem and a subproblem. The subproblem performs a frequency dynamic security check on the master problem, thereby enhancing the frequency security of the optimal solution obtained from the master problem. The case study demonstrates that the proposed FCUC model can significantly reduce operating costs and can reflect both the frequency safety and the inertia level of IMs in unit commitment scheduling.