Centralized voltage control for distribution networks with embedded PV systems

This paper proposes a centralized control methodology for optimizing nodal voltages of distribution networks by acting on the reactive power produced by PV-inverters. Control actions are centrally evaluated in real-time by solving a constrained dynamic optimization problem aimed at minimizing the voltage deviation from a reference value. The solution of this problem is obtained by adopting an algorithm operating in the continuous time domain based on a fast artificial dynamic system involving the sensitivity theory. By this approach the controller is able to promptly respond to any change in the system operating point, allowing its adoption in the continuous time domain. However, it must be considered that the injection of the reactive power provided by PV-inverters entails greater conduction and switching losses, causing a reduction in the active power output, thus implying less incomings. As a consequence, these additional operating costs have been analyzed and evaluated in order to establish an economic compensation mechanism able to guarantee fair reimbursement to PV generators engaged in this regulation service. Computer simulations performed on an MV distribution system, demonstrate the effectiveness of the proposed control scheme under different operating conditions, confirming its ability to control the network in real-time.