Voltage regulation through optimal reactive power dispatching in active distribution networks

This paper presents a non-linear, constrained optimisation problem whose solution is used to optimally dispatch dispersed generators connected to a MV distribution network where an advanced voltage regulation system is implemented in order to allow a higher penetration of dispersed generation (DG) with respect to traditional procedures. In this context, DG active and reactive power output control is coordinated with voltage regulation in order to avoid nodal under/overvoltages that are likely to occur in distribution networks with traditional voltage control systems due to a significant presence DG. The proposed optimization procedure aims at minimising an objective function given by the sum of the costs that distribution network operators incur to perform voltage regulation (the costs are, typically, related to network power losses, local generation and shunt capacitors banks reactive power production, reactive power imported by the HV network). The control variables are the HV/MV transformer OLTC position and the power output of the reactive power sources connected to the network. The application of the optimisation procedure to a MV distribution network is also presented and the results are discussed in terms of potential global savings for the DNO in carrying out network voltage regulation.