Coordinated Control of PV Inverters in Distribution Grid Using Local and Centralized Control

A coordinated control strategy of PV inverters is proposed to keep voltages within the specified limits in distribution grids. The proposed method consists of a local volt-VAr control and a centra coordinating control to manage reactive power outputs of PV inverters efficiently. The local control embedded in the inverter controller is operated based on the local measurements in order to improve the voltage quality. The central coordinating control collects measurements throughout the grid to control the voltages inside limits and coordinate the PV inverters' contributions. In the long term, the aim is then to obtain an optimum distribution of their contributions to voltage quality between the different PV inverters. To this purpose, volt-VAr set-points are sent from a central coordinating control to the local one of PV inverters through communication, forcing them to change their reactive power output based on the local measurement voltage and thereby improving the voltage quality. The effectiveness of the proposed method is demonstrated on an actual Danish grid.