Statechart Models of MPPT Controller for a Photo-Voltaic System in Co-Simulation Environment

Abstract

MPPT(Maximum Power Point Tracking) algorithm plays a vital role in the operation of a photovoltaic system and hence its implementation is significant. Two MPPT algorithms namely Perturb & Observe and Incremental Conductance, are widely used. In the present work, an attempt is made to model the two widely used MPPT algorithms using Statecharts. Statecharts, which are a combination of Finite State Machine or State Transition Diagram, depth (or insideness), broadcast communication and orthogonality, are a method of modelling real-time systems that require precision in aspects of timing and output. In this paper, statechart models of Perturb & Observe(P&O) and Incremental Conductance algorithms have been developed using the graphical programming approach, LabVIEW Statechart Module. The developed statechart models can be used in any host application of LabVIEW, including FPGA targets (online or simulated FPGA targets) and can also be communicated to circuit models in Multisim environment. Accurate analysis of a P-V system would require a mixed-signal simulation. To achieve this, in the present work, National Instruments (NI) Multisim has been used for modelling of the analog circuitry and NI LabVIEW has been used for effective development and implementation of control algorithm to the model built in Multisim. P-V array behaviour with a boost converter has been modelled in NI Multisim, which is co-simulated with NI LabVIEW. To the same system, the developed statechart models of P&O and Incremental Conductance methods are interfaced for tracking MPP of the PV array. Results have been presented with and without statechart MPPT controller, in varying irradiances and load conditions.