Volt/VAR Optimization function with load uncertainty for planning of MV distribution networks

Volt/VAR Optimization (VVO) function is an important element in real time operation of distribution networks and major part of advanced Distribution Management Systems (DMS). From planning prospective, VVO function can be used to optimize reactive power flow in distribution network to recommend the best operating condition for the control equipment in a predefined period of time in future (i.e. 24 hour). The typical objective function of VVO functions are minimizing the total system loss for a certain system load level. VVO function computes the optimized setting for transformer on-load tap changers (OLTC), Voltage Regulators (VR), and Capacitor Banks, while system voltage profile is maintained within its limits. In this paper the objective is to develop a planning VVO engine which can calculate the most probable expected loss of the network for the next 24 hours, and can recommend the best expected operating condition for the control equipment. For the VVO algorithm a full mixed integer linear programming (MILP) model is used to solve the loss objective of VVO problem for a planning application. The load uncertainty is modeled by an ARMA model which can create any arbitrary number of forecasted load scenarios to be used by VVO engine (implemented in a commercial solver GAMS, “General Algebraic Modeling System”). The implemented models have been tested on a real distribution network in southern Sweden and the results are presented.