Converter-Based Solution for Cancellation of Subsynchronous Oscillations in Local Power Grids

Power electronics converters are typically used in microgrids and local power network to interface renewable energy sources, energy-storage systems (ESSs) and loads. In the case of an ESS, its active power capacity can be used to compensate subsynchronous oscillations produced by the massive integration of converter-interfaced applications. However, the control system for the compensation of oscillations is not straightforward and its design requires detailed knowledge of the system dynamics. In this paper, a method is proposed based on a converter-interfaced ESS that cancels out the impact of subsynchronous oscillations originated from wide-area network on a local electricity grid. The method is based on a small-signal model of the local power network. The full system representation will also be used to analyse the maximum singular values (MSV) in order to detect the most unfavourable cases and act upon them. A low-order dynamic model will be derived from the complete state-space representation and used as a compensator. Simulation results from Matlab/Simulink and SimPowerSystems toolbox will be used to demonstrate that the performance of the proposed method and the cancellation of subsynchronous oscillations in the local network.