Damping of SSR Oscillations of Series Compensated Power System Connected to Two-Stage P-V Controlled PV Power Plant

This paper shows that a two-stage Power-Voltage controlled (P-V controlled) aggregated photovoltaic (PV) power plant, which is connected at the terminal of the synchronous generator, has the capability to control the terminal voltage of the PV power plant and the synchronous generator of first IEEE benchmark model (IEEE-FBM) within the permissible limits according to the grid code requirements and, simultaneously, damp out all the four torsional modes at the critical degree of compensations during three phase faults. The Voltage-Sourced Inverter (VSI) of the PV array has four functions: 1) Converting DC to AC power, 2) controlling and limiting the dc voltage of the VSI, 3) regulating the terminal ac voltage of VSI and consequently the terminal voltage of the aggregated PV power plant and 4) damping out all unstable SSR oscillations by introducing a damping controller in the ac terminal voltage controller. Time domain simulations, using PSCAD, are performed to demonstrate the ability of the P-V controlled PV power plant to perform the mentioned functions at different degrees of series compensation and PV penetration power.