Collegial control for mode transfer of solar photovoltaic-battery system

Abstract

This work presents a collegial control for the objective of microgrid synchronization with improved power quality injection. The solar photovoltaic and battery based three-phase microgrid utilizes coordinated operation between improved adaptive control and frequency estimator for reducing harmonic impact due to non-linear nature of local consumer loads. The grid feeding control is based on improved adaptive logarithmic difference technique. This adaptive algorithm is used to feed good power quality currents despite of the consumer loads associated across the common coupling point. The control strategy provided is more robust and has better convergence rate than its predecessor due to the variable step-size employed for fundamental component extraction. Frequency estimation is performed using a feed-forward enabled second-order generalized-integrator (FFE-SOGI) frequency-locked-loop (FLL) technique. The feed-forward term procured from the quadrature and direct components of the SOGI, enhances FLL loop performance. It gives stable estimation and effective system performance during frequency deviations. This allows transient-free operating mode transitions of microgrid. Proposed control schemes are validated through test results on an experimental setup.