Impact of Large-Scale PV-BESS on Dynamics of Power System Oscillatory Modes

The target of zero carbon emission from electric power generation results in the replacement of fossil-based energy generation by renewable sources. The increase of power electronically interfaced photovoltaic (PV) power plants into power systems causes severe stability problems due to lack of inertia and damping effect. The battery energy storage systems (BESS) at PV stations can be controlled by a virtual inertia controller (VIC) to provide virtual inertia and damping support while smoothing the power fluctuations of PV power plant. As BESS with VIC mimics the characteristics of a synchronous generator, the influence of BESS on low-frequency electro-mechanical oscillations (LEO) is significant. This research paper investigates the probabilistic distribution of power systems LEOs for various controller gain of VIC and stochastic variation of solar irradiance under the influence of phase-locked loop (PLL) dynamics. The modal interaction of PLL and virtual inertia controller with power system oscillatory modes are investigated by stochastic eigenvalue analysis using Monte Carlo simulation approach.