Quasi-Stationary Implementation of Virtual Admittance Controller for Voltage Support from Distributed Generation

The presence of distributed energy sources in distribution networks has been steadily increasing in the past few years, causing important changes in the voltage profiles. For this reason, distributed generators are expected to contribute to the voltage regulation. Recently, novel controllers have been proposed that emulate the dynamic properties of an electrical admittance and support voltage through simultaneous use of active and reactive power. However, these controllers can suffer from poor dynamic performance and can even cause instabilities. In this paper, the quasi-stationary approximation of the differential operator is implemented on a virtual admittance based, voltage supporting controller of a distributed generator. This results in a new controller implementation that presents improved dynamic operation and avoids resonance-triggered instabilities. The dynamic and quasi-stationary controller implementations are compared by using dynamic analyses for different parameter selection. Simulation results from Matlab and its SimPowerSystems toolbox are used to validate the contributions of this work.