Zone-oriented 2-stage distributed voltage control algorithm for active distribution networks

Volt/Var Control (VVC) optimization techniques have been introduced with the prime purpose of keeping the feeder voltages within prescribed limits at a minimum cost and/or reduced system loss. Motivated by the growing inclusion of distributed renewable energy resources; and further, by the speed and convergence limitations of existing tools, this paper proposes a two-stage zone-oriented method to optimally set the volt and var control devices in active distribution systems. The proposed algorithm divides the distribution systems into a number of zones (areas) based on customer type (residential, commercial and industrial end-users). Each zone has its own priorities, characteristics, and requirements. The primary goal is to optimally determine the volt/var control settings within each zone to achieve its own objectives and to meet its unique operational requirements and characteristics.. To efficiently solve the volt/var problem, we propose a novel 2-stage hierarchical distributed algorithm based on cordal relaxation semi-definite programming (SDP) optimal power flow modelling. The proposed solution algorithm is non-iterative and does not require any penalty parameter tuning. The proposed non-iterative solution results in fast convergence, while eliminating the necessity of penalty parameter tuning makes the algorithm less human- and system-dependant. This paper also considers the minimization of voltage regulator movements, an approach which has not been considered before in convex volt/var problem formulation. Several case studies have been presented to demonstrate the effectiveness of the algorithm and to validate its accuracy.