A fuzzy logic controller for stand alone PV systems

The main objective of this work is to improve the reliability of stand-alone PV systems by applying modern nonlinear control techniques to load management. The control technique implemented is based on load priority assignment and a fuzzy controller having two fuzzy variables and five fuzzy sets. The experimental implementation involved both data acquisition and simulation using LabVIEW and Matlab. The controller works in real time and issues enable/disable orders to the individual loads of the system. A new parameter called weighted loss of load probability (WLLP), which is a weighted sum of the LLP of the individual loads, is introduced in this paper to extend the LLP concept to systems where priorities are assigned at the load side. A comparison of the performance of a fuzzy controller systems versus a conventional system is presented showing that significant improvements of WLLP can be achieved by using this control technique.