A Metaheuristic Approach for Conservation Voltage Reduction in Unbalanced Active Distribution Networks

Abstract

This work proposes a multi-objective optimization formulation to solve the Conservation Voltage Reduction (CVR) problem for three-phase unbalanced active distribution systems. CVR is a tool deployed for reducing power consumption by exploiting the voltage dependency of loads. Here, the node voltage magnitudes are kept near to its lower limits, as a strategy. Voltage Regulators (VRs), Capacitor Banks (CBs), On- Load Tap Changers (OLTCs), and reactive power output from smart inverters are used to achieve this objective. Along with minimizing the load demand, minimization of the losses is also considered as an objective. Since many of the devices are operated separately across each phase, the grid suffers from increased voltage unbalances. This issue is handled by choosing Voltage Unbalance Factors (VUFs) at all nodes as constraints. Minimization of unbalance current flow in the substation transformer is also added as an objective in the optimization problem to reduce associated ill-effects. The optimization problem solved using Multi-Objective Particle Swarm Optimization (MOPSO), is tested on modified IEEE 13-bus and 34-bus systems. Obtained results show a reduction in losses and demand while ensuring acceptable voltage profiles throughout the feeders. Results show that the load profile and the R/X ratio of the lines profoundly influence the effectiveness of CVR.