Multi-time-scale Voltage Optimization of Flexible Interconnected Distribution Network with Self-energy Storage

In order to solve the voltage violation problems caused by the high proportional distributed generators (DGs), considering the characteristics of the slow-regulating equipment and the sequential continuity of state of charge (SOC) of energy storage, this paper proposes a multi-time-scale voltage optimization model of the flexible interconnected distribution network with self-energy storage. The day-ahead optimization solves the tap position of the slow-regulating equipment and gives the intra-day power limit range of energy storage. Based on this, the intra-day optimization can calculate the optimal output of energy storage and the ports of voltage source converter based high-voltage direct current (VSC-HVDC) in each period. Based on the detection of voltage violation, the output of each port is adjusted in real time to shorten the duration of over voltage/under voltage. This paper proposes a two-layer solution algorithm to address the mixed-integer non-convex and non-linear optimization model of multi-period coupling. The upper layer uses the dynamic programming method to deal with the problem of full time optimization of energy storage and the integer programming problem of the slow-regulating equipment. The lower layer uses the polyhedron relaxation technology to improve the efficiency of the second-order cone programming algorithm. Finally, actual calculation examples verify the effectiveness of the proposed model and solution method. © 2021 Automation of Electric Power Systems Press.