Stochastic Subspace Identification Validation of PV Inverter Operation Improvement with Optimally–Tuned Controllers

Recent literature present enhanced operation of power electronics interfaces (PEI) through application of controller heuristic self-tuning techniques in the time-domain. For switch mode Photovoltaic (PV) inverters, this results in optimal adjustment of PEI controller gains, leading to transient energy reduction when PV system is subject to perturbations. In this study, with injecting active power measurements at point of common coupling and during large perturbations in irradiance, an empirical measurement based eigenvector estimation theory i.e. Stochastic Subspace Identification method (SSI) is used to analyze the SSI results in the frequency domain. The PV-VSIs in a grid-connected MW-scale PV plant are operational with manual- and heuristic-tuned controllers, implemented in both stationary and synchronous reference frames. The SSI results in frequency domain are compared with time-domain to conclude the effectuality of the SSI empirical approach in validating improvement in PV inverter operation with heuristic-tuned PV-VSI controllers' parameters in time-domain.