FOSMC Control Mechanism For Solar and Battery based Microgrid System

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.