FOSMC Control Mechanism For Solar and Battery based Microgrid System

Abstract

This work presents the performance of fractional order sliding mode control (FOSMC) for a microgrid system (MG) consisting of solar and a battery feeding different loads. The proposed controller is used to track effectively the desired output voltage during changeover from solar to battery system. Using state space model of a voltage source inverter (VSI), the control input is obtained. The maximum power from the Solar PV system is harnessed using Perturb and Observe (P&O) MPPT algorithm. To step up the voltage of 200 V generated from the PV panel to 400 V as input to the 2.5 kVA rated VSI, a boost converter is utilized. PWM switching pulses are generated to the IGBT switches operating at 10 kHz for effective tracking of the reference load voltages. A 2.5 kW 0.8 pf lagging load and a single phase diode bridge rectifier as non-linear load is considered to be fed from the MG system. The controller s performance in terms of steady state error, total harmonic distortion (THD), settling time is studied during the system operation. A comparison with the classical SMC is observed through its control energy is also presented. The control energy required in FOSMC for a stable system operation is 8 times less than that of SMC is realized. It is observed that FOSMC performs well with less steady state error of 1.32 %, THD of 0.135 % and settling time of 0.16 ms. Simulations are performed in PSCADv4.6.