Single Phase Grid Tied PV System Modeling and Control with Low Voltage Ride Through Capability

Solar energy generation and its integration with the utility grid is gaining importance with the increasing trend towards distributed generation systems but is also causing problems for the grid in terms of stability and protection. Disconnection of a distributed PV system from the grid due to anti-islanding protection in under voltage conditions may lead to a more drop in the grid voltage that can cause more distributed PV systems to disconnect, thus leading to a huge cascaded failure. To avoid this condition, ancillary service like low voltage ride through is being used in countries like China, Germany and Italy, that avoids disconnection of PV inverters for normally occurring voltage dips in the grid and have reactive power injection capability for dynamic grid support. This study presents a model of a 3500W single-phase grid tied PV system connected to a 240V Vrms grid. Low voltage ride through control using peak current control has been implemented and the operation principle has been tested via simulations in MATLAB/Simulink. Three different scenarios having voltage sags of different amplitudes have been generated keeping the PV generation constant and the working of the algorithm is verified via the German grid code. The results show that the implemented method is effective to provide voltage support in under voltage conditions with a satisfactory performance based on the grid requirement.