Modeling, simulation and hardware implementation of a PV power plant in a distributed energy generation system

Effective interconnection of stochastically variable renewable energy resources like solar PV (photovoltaic) systems to the grid requires meticulous attention to ensure system compatibility, stability and reliability. The operating characteristics of such PV power plants need to become familiar to power systems engineers and operators. Such familiarity can effectively be achieved only via system modeling, simulation and experimental studies. This paper develops models for an integrated PV power plant which comprises PV array, SEPIC (single ended primary inductance converter) converter, bi-directional de-de converter, dc-ac converter, and battery energy storage system using Matlab/Simulink. The models are used for simulation studies to investigate: 1) the response of the system to the ever-changing environmental variables, 2) the ability to track the maximum power point, 3) the role of the battery energy storage in the mitigation of voltage and power oscillations and 4) the role of the inverter in ensuring compliance to the grid requirements. Experimentally, a DSP (digital signal processing) based control system for maximum power point tracking, dc bus voltage regulation, battery charge/discharge control, dc-ac converter control, system synchronization and protection is implemented and used for the validation of the simulation studies. The simulation and experimental results are presented and discussed.