Control of a PV-Wind Based DC Microgrid With Hybrid Energy Storage System Using Lyapunov Approach and Sliding Mode Control
Tony Thomas, Mahesh K. Mishra, Chandan Kumar, Marco Liserre
Abstract
This paper focuses on the control techniques implemented on a PV-wind based standalone DC microgrid with hybrid storage system. An Enhanced Exponential Reaching Law (EERL) based sliding mode control (SMC) is applied for extraction of maximum power in a Permanent Magnet Synchronous Generator (PMSG) based wind energy system. This reaching law based SMC tracks current reference from the optimum torque MPPT algorithm during different wind speeds and load variations and has a good dynamic response. A combination of battery and supercapacitor is used as the hybrid storage system for providing reliable and continuous power to the load. The supercapacitor absorbs the transient components during disturbances and helps in improving the life of battery. A control method based on the Lyapunov function, which can ensure global asymptotic stability is implemented for the bidirectional converter of battery and supercapacitor. The proposed method maintains the DC link voltage constant during solar, wind and load variations. A detailed analysis of the two control laws is presented. The superiority and efficacy of the proposed control strategies are validated on the DC microgrid system during different operating conditions by simulation studies and by developing an experimental test bench.