Grid interfaced solar photovoltaic system using ZA-LMS based control algorithm

Abstract

Renewable energy sources such as solar photovoltaic can meet increasing energy demand in countries where there is sufficient availability of sun light. Intermittent nature of this kind of renewable energy sources demands a control which can handle fast dynamics of the system. This paper presents a grid coupled solar photovoltaic (SPV) system which includes solar photovoltaic array, incremental conductance based MPPT and boost converter. Grid integration of SPV array is performed using three phase voltage source converter (VSC) controlled with a fast and robust control algorithm. A Zero Attracting Least Mean Square (ZA-LMS) based controller is proposed to generate reference grid currents. These currents are compared along with sensed grid currents to generate switching pulses for three phase VSC. The proposed system is used to feed real power demand of load along with power quality refinement features such as suppression of harmonics, maintaining grid current at unity power factor and balancing of loads. Performance of the ZA-LMS controller is compared with conventional controllers such as normalized least mean square (NLMS) and dq0 frame theory. These controllers are compared for various characteristics concerning weight convergence, mathematical complexity, computational burden on real time controller and harmonic compensation. Proposed controller is implemented using dSPACE 1104 and tested on developed laboratory prototype of grid connected VSC working as shunt active power filter. Performance of the controller is observed and verified for steady state and dynamic load conditions.