Voltage Control Using Smart Transformer for Increasing Photovoltaic Penetration in a Distribution Grid

Uncertainty and variation of power generation through photovoltaic (PV) sources are major challenges for their integration with the distribution grid. Voltage rise and voltage drop issues limit the increase in PV penetration and loading level, respectively. It is important to maintain voltage levels within specified limits of grid code for providing long life, more efficiency, and good performance of consumer equipment while ensuring that the PV power generation is not curtailed. In this paper, a voltage control method for the smart transformer (ST) is proposed to improve voltage profile in the distribution network. Voltage control capability for ST is added through the method of switching among three setpoints based on the voltage. The proposed method is compared with the conventional method of switching between two setpoints based on current. The proposed method provides better voltage profile in the distribution network as compared to conventional method. Performance indicators are developed to understand the impact of voltage control methods on the system voltage profile. Proposed voltage control method is tested on a CIGRE low voltage residential distribution network.