Virtual Admittance Control for Providing Voltage Support using Converter Interfaced Generation

The level of penetration of distributed energy sources in distribution networks has been steadily increasing in the recent years causing significant changes and fluctuations in the voltage profiles. For this reason, distributed generators are being asked to participate in the voltage regulation. This task is commonly achieved by applying additional droop controllers to amend the active and reactive power references. However, in weak and resistive grids the coupling between the two powers reduces the efficacy of this approach. In this paper, a controller that emulates the response of an admittance is used to provide voltage support to the distribution network. With this control strategy, voltage support can be provided by taking advantage of the existing coupling. The controller performance is electrically equivalent to an admittance, simplifying the understanding of the proposed concept. The inclusion of power and current restrictions in the control scheme is discussed. Simulations performed in Matlab/Simulink and continuation analysis from Matcont are used to evaluate the contributions of this work.