Evaluation of sensitivity based coordinated volt-var control and local reactive power for voltage regulation and power exchange across system boundaries in smart distribution networks

Abstract

This paper presents a hierarchical coordinated volt-var controller (VVC) at medium voltage level for the containment of voltages at the critical nodes in a smart distribution network. VVC finds the optimal set-points for distributed generators and tap position of the transformers in order to contain the voltage at the critical nodes with-in limits and to minimize the total reactive power dispatched. In addition to the voltage regulation, VVC can track reactive power as a reference signal to control the power exchange across system boundaries. The proposed approach is compared with the optimal power flow that requires load flow calculation for each control update. In comparison, VVC is based on a sensitivity matrix based approach that reduces the complexity of the problem. The paper presents separate and combined evaluation of the proposed VVC with reactive power support from inverters at low voltage in order to quantify the combined impacts. The comparison is performed based on the voltage deviation and performance indices, line loading and reactive power exchange at the system boundary. The simulations spanning one year are performed on a synthetic network. The study leads to comprehensive insights into factors influencing the effectiveness of the reactive power control strategies.