Circuit simulation of photovoltaic systems for optimum interface between PV generator and grid

The paper proposes a circuit simulation procedure based on two steps to determine the steady state working points and to analyze the time domain response of a grid-connected PV system. The overall PV generator is modeled with a very compact two-component physical model. A PV generator, constituted by a string of three standard 30 cell modules, connected to the grid by means of a PWM inverter, a decoupling inductor and a low frequency toroidal transformer is used as practical application example. This system is modeled and simulated using both DC and transient analysis with different modulation index values. Simulation outputs are compared with experimental results obtained from an ad hoc designed prototype system showing good agreement. The proposed circuit simulation procedure and models can be useful in assessing design variables as well as in checking novel hardware/software solutions for maximum power point tracking and grid connection.