Coordinated Voltage Control in LV Distribution Systems using OLTC and BESS

Voltage control is an important operational requirement for efficient and reliable operation in distribution systems. The accelerated proliferation of Solar Photo-Voltaics (SPV) in distribution networks, has resulted in voltage fluctuations in the distribution system. This is due to the high R/X ratio in Low Voltage (LV) distribution network that leads to strong coupling between active power and voltage. This paper thus proposes coordinated control of voltage in LV distribution systems by On-Load Tap Changer (OLTC) and Battery Energy Storage Systems (BESS) so as to mitigate the issue of voltage rise/ drop. The objectives are to operate the slow-acting OLTC in the presence of fast-acting BESS and reduce the stress on battery charging/ discharging. This leads to increase in battery life and reduced operation of OLTC, which helps in utility asset optimization in terms of both the OLTC and BESS. In the proposed scheme, OLTC tap operation is based on the weighted average of the bus voltages. The feasibility of the proposed approach is demonstrated on a modified IEEE 13 node distribution system which is simulated in MATLAB/Simulink. Simulation results verify the proposed coordination voltage control scheme.