Adaptive and Coordinated Volt/Var Optimization for Unbalanced Active Distribution Networks of Multiple Voltage Levels

Increasing penetration of intermittent distributed generations (DGs) raises great challenge to distribution volt/var management. Coordinated volt/var control by emerging DGs and traditional devices (e.g. capacitors, on-load tap changers (OLTCs) etc.) is essential. However, existing coordinated volt/var control studies are mainly based on day-ahead load and generation forecasts, fixed optimization weights, balanced configuration and single-voltage level, leading to unreasonable control solutions. Based on the increasing availability of bi-way information and communication infrastructures, a real-time coordinated volt/var control strategy with adaptive optimization weights for integrated 3-wire MV and 4-wire LV radial distribution networks is proposed. By coordinating the traditional MV delta switched capacitors and the emerging LV distributed PV inverters, operation performance including network losses, voltage balance and magnitude profiles, as well as operation costs of capacitors and PV inverters are simultaneously optimized. To effectively and efficiently solve the proposed distribution optimal power flow problem, an improved direct load flow combined with a modified particle swarm optimization method is employed. Finally, detailed simulations on a real Australian distribution network over 24 hours are performed to prove the feasibility, effectiveness and superiority of the proposed adaptive and coordinated volt/var optimization strategy. © 2018, Power System Technology Press. All right reserved.