PQ-Based Local Voltage Regulation for Highly Resistive Radial Distribution Networks

Modern distributed energy resources (DER) consisting of energy storage coupled with a voltage source converter (VSC) provides flexible and dynamic operations in active and reactive power quadrants. These technologies present significant opportunities to provide distribution network support instead of traditional approaches if effective controls are in place. Although voltage regulation using reactive power is typical, active power is more effective at manipulating voltage in highly resistive distribution networks. This paper proposes a local controller that regulates VSC terminal voltage and allows fast switching of the VSC power factor output, with minimized disturbance on the terminal voltage. This improves the effectiveness of the VSC in managing voltage in highly resistive distribution networks using both active and reactive power and provides a strategy to manage upstream power flow. The approach uses gain equations derived from the voltage sensitivity to power injection and the point on wave switching in the stationary reference frame. The control strategy is verified through detailed simulation in MATLAB/Simulink using a modified IEEE 4-node test feeder, including performance during a switched load, DER disturbance and controller interaction via voltage droop. The small-signal model and stability analysis of the proposed approach is also presented.