MSTOGI-FLL-ROGI Based Frequency Adaptive Control of SyRG DG-SPV-BES with BDC Connected Standalone Microgrid for Remote Areas

Abstract

The frequency of an isolated microgrid (MG) varies with the loading condition based on the droop characteristics of diesel generator (DG) set. Although droop controllers are used to increase or decrease generation to match the loads and to reduce frequency variations, it takes more time as mechanical time constant is more than electrical time constant. The frequency variations cause system instability due to improper active and reactive power flow and degrade the power quality of the system. DG set side power quality problems exist in presence of nonlinear loads. This paper aims to make the system frequency adaptive in islanded condition as well as to mitigate the power quality problems in presence of nonlinear loads and, also, during single phase loads. In this work, a mixed second and third order generalized integrator with frequency locked loop (MSTOGI-FLL) cascaded with reduced order generalized integrator (ROGI) based control is used to eliminate the harmonics and DC offset from the DG voltages and currents, and to make the system frequency adaptive. The standalone system comprises of a single stage solar photovoltaic (SPV) array, a synchronous reluctance generator (SyRG) based DG set and, a battery energy storage (BES) interfaced with a bidirectional converter (BDC). SPV is operated by perturb and observe (P&O) MPPT. The DG set is operated in its fuel economic zone (FEZ). The system performance is analyzed under several dynamic conditions using developed simulink model.