Design of a hybrid PV-fuel cell system with active reactive power control capabilities

The increasing use and integration of renewable energy into the electricity grid has started to have impacts on power system security and stability. Hence, grid integration needs have become a major concern as the share of renewable energy sources in the electricity grid is gradually increasing and replacing conventional power plants. The sudden disconnection of large renewable power plants during outages can lead to problems with power stability, reliability, and overall system operation. Grid codes are rules that developed by transmission system operators to address integration requirements. An important aspect of grid codes is the low voltage ride-through (LVRT) feature. Recent regulations require renewable power systems to remain connected to the grid during faults, providing/frequency support like conventional installations and contributing to grid stability and reliability. Different countries have specific grid code requirements, but overall, the objective is to ensure stable and reliable operation of the power system. In this thesis, Türkiye's LVRT requirements are considered. The fulfillment of LVRT requirements for renewable power plants requires overcoming important issues such as the prevention of overcurrent at the AC side and overvoltage on the DC side of the inverter. In this thesis, a flexible active power control approach using an artificial neural network (ANN) is developed to improve DC voltage stabilization of photovoltaic (PV)- fuel cell (FC) hybrid power system to overcome overcurrent at the AC side during grid faults. A detailed simulation of proposed grid-connected PV-FC hybrid power system is carried out using MATLAB/Simulink to evaluate the performance of the suggested control scheme. The performance of the proposed system is evaluated by subjecting it to symmetric and asymmetric faults in four different fault types to improve the LVRT capabilities of the PV-FC hybrid system. This approach improves DC-link voltage stability and provides consistent voltage levels by limiting voltage deviation to between 12.9 % dip and 10.1 % peak in all fault types.