Volt-Var Optimization and Reconfiguration: Reducing Power Demand and Losses in a Droop-Based Microgrid

Optimal planning and dispatch for satisfying peak demand are challenging, especially for microgrids with significant penetration of renewable energy. In extreme cases such as weather contingencies, microgrid operators may resort to load shedding. Alternatively, conservation voltage reduction (CVR) can be used to decrease the power and energy demand across the network. In this article, a mixed-integer linear programming problem has been formulated for a droop-based microgrid to implement network-wide CVR along with minimal line losses. For planning purpose, optimal sizing and placement of distributed generators (DG) is performed initially. Afterwards, a day-ahead dispatch is generated for these DGs for a realistic hourly load profile considering residential and industrial loads. Besides, network reconfiguration concept has been explored to boost the demand reduction. Furthermore, the effect of using a constant impedance-current-power (ZIP) load model instead of considering the classic constant impedance load model has been tested. The effectiveness of the proposed optimization has been tested on 33 and 69 bus islanded microgrids. The obtained results demonstrate the accuracy of the proposed planning and dispatch formulation, and validate its utility in reducing the power and energy consumption while attracting very low line losses.