Hybridization of battery with pico hydel for frequency regulation of microgrids using synchronverter control

Abstract

Frequency regulation of autonomous microgrids with intermittent renewables is a tedious task, which requires additional support from energy storage systems (ESS). Ideally, the system requires a faster‐acting ESS to arrest the initial frequency deviation and high energy capacity ESS to restore the frequency to its nominal value. Pico hydel energy storage (PHES) is one such high energy capacity ESS developed from the agricultural pumping systems. However, PHES has a slower response and cannot switch rapidly between pumping and generation modes. Hence, this paper incorporates a battery with PHES to achieve a faster dynamic response and absorb high‐frequency power dynamics. Additionally, a frequency regulation strategy with synchronverter control is proposed to mimic synchronous machines, especially to reduce the rate of change of frequency (ROCOF) and frequency nadir. Firstly, a small‐signal modelling approach is proposed, and it was utilized to assess the system stability through eigenvalue analysis. Subsequently, transient simulations were carried out to gauge the performance of the synchronverter strategy with vector control for frequency regulation. As a result, the frequency nadir and ROCOF were substantially reduced with the synchronverter strategy compared to the vector control based on the simulation results.