Appendix E: Modelling and performance evaluation of a stand-alone photovoltaic (PV) plant with maximum power point tracking
Photovoltaic (PV) plants consist of inverter-interfaced PV arrays. The inverter keeps the AC output voltage at the specified level irrespective of solar irradiance E (W/m2) and ambient temperature T (K). The inverters are provided with maximum power point tracking (MPPT) feature that sets the operating point voltage of the array such that maximum power can be extracted from the array. This section discusses the development of a robust and very simple mathematical model of a polycrystalline PV array in MATLAB Simulink that (i) imposes low computational burden on the system, (ii) has low data storage requirement and (iii) can be represented by standard block set of MATLAB Simulink. At the same time, the model can take into account the variation of the PV array output with solar irradiance and ambient temperature by incorporating the MPPT feature. This feature shifts the operating voltage set point of the model to its maximum power voltage so that maximum power can be extracted from it. The model is used to (i) study in detail the performance of the PV array with varying weather and loading conditions, (ii) simulate a stand alone PV plant for studying the effect on load variation on the AC side bus and (iii) develop a simple load-shedding scheme for the PV plant.