Frequency Stabilization of Solar Thermal-Photovoltaic Hybrid Renewable Power Generation Using Energy Storage Devices

Isolated hybrid power systems (HPSs) with coordinated control of renewable energy sources (RESs) and energy storage devices (ESDs) with appropriate control techniques are studied in this paper for load frequency stabilization. The solar thermal power generation and photovoltaic systems are used as the primary source of generation in the designed test systems. The ESDs used are double-layer capacitor (DLC), ultra-capacitor (UC) and compressed air energy storage as per the designed test system to effectively supply insufficient energy of power generation in a short time. In the designed test system, it is assumed that UC transfers energy to the load side during adequate insolation. Whenever the same may not meet the load demand, DLC provides power to meet the remaining load demand. In one of the designed test systems, load frequency characteristics of the HPS model are carried out with high-voltage direct current link feeding to isolated load. The contribution of this work is the hybridization of RESs with ESDs with appropriate controller and applied control strategy. In the studied system, a proportional-integral-derivative controller is employed and its parameters are tuned by a nature-inspired moth flame optimization technique. The system dynamic performance with different operating conditions is carried out. Both the qualitative and the quantitative aspects show better performance of HPS models under study using the proposed technique.