Control Structures Implementation to Allow High Penetration of a VSC within an Isolated Power System

Abstract

Abstract : Recently, the increasing occurrence of power instability caused by alternative energy sources has attracted the possibility of implementing Energy Storage System (ESS), capable of supplying the energy necessary to improve the energy quality within the grid. Therefore, the attention of researchers has been drawn on the behaviour that has the connection of the ESS, based on internal controllers such as Virtual Synchronous Machine (VSM) and a Classical Control Cascade (CCC), for different ESS power ranges. In this context, this paper deals with the implementation of an ESS represented by a Voltage Source Converter (VSC) employing control techniques of VSM and CCC simulated in PScad environment in three cases: in the first case, the power system in the steady-state is seen during the description of the controls; in the second case, the power system in the presence of a fault; in the third case, the power system with a load at the PCC. Finally, a fusion CCC-VSM using a grid impedance estimator is implemented with different current reference controls considering Short Circuit Ratio (SCR) values that represent the weak and robust grid