Double-timescale distributed voltage control for unbalanced distribution networks based on MPC and ADMM

Chapter 9 proposes a double-timescale distributed voltage control scheme for unbalanced distribution networks (DNs) with distributed generators (DGs) based on model predictive control (MPC) and alternating direction method of multiplier (ADMM). In the slow-timescale control (STC), the actions of on-load tap changer, step voltage regulators, and capacitor banks are optimized to correct long-term voltage deviations. In the fast-timescale control (FTC), the active and reactive power outputs of DGs are optimally coordinated to handle the fast voltage fluctuations. The MPC problems of STC and FTC can be transformed into the standard MINLP problem and the second-order cone programming (SOCP) problem, respectively. A tailored solution method based on McCormick envelopes and branch-and-boundalgorithm is developed to convert the MINLP problem into the SOCP problem, and a distributed control strategy based on ADMM is proposed to efficiently solve these optimization problems. The modified IEEE 123-node system is used to verify the effectiveness of the proposed control scheme as a test system.