A Voltage Control Optimization for Distribution Networks with DG and MicroGrids

Abstract

In general, DG is not subject to a centralized dispatch and reactive power generation is usually restricted by operation rules defined by the DSOs. With the growth of DG and microgrids in distribution networks, the development of voltage control functionalities for these units needs to be investigated. This requires a new operation philosophy to exploit reactive power generation capability of DG and microgeneration with the objective of optimizing network operation: minimize active power losses and maintain voltage profiles within adequate margins. This implies that DG should adjust their reactive power generation, i.e. supply an ancillary service of voltage and reactive power control. In addition to the growth in DG penetration, microgeneration is expected to develop considerably and contribute to the implementation of efficient voltage control schemes. For this new scenario, a hierarchical voltage control scheme must be implemented, using communication and control possibilities that will be made available for microgrid operation. Technical advantages and feasibility of this operation philosophy are investigated in this chapter by analyzing the impact of the proposed control procedures on distribution networks. In addition, the identification of control action needs is assessed by solving an optimization problem, where voltage profiles are improved and active power losses minimized, subject to a set of technical constraints. The solution for this problem is obtained using