Decoupled Piecewise Linear Relaxation for the AC Optimal Power Flow Problem

Power system are witnessing fundamental changes with increasing renewable power generation. It is necessary to further consider voltage and reactive power in the optimal power flow (OPF) problem. OPF based on linear power flow models is efficient and reliable. However, conventional linear OPF methods cannot ensure high solution accuracy especially for reactive power and voltage. Hence, this paper proposes a decoupled piecewise linear relaxation method for the OPF problem. The cosine terms are retained and piecewise relaxed. The results show the proposed method improves the approximation accuracy of reactive power and voltage while the computation burden is still acceptable.