Photovoltaic power system application using energy stored quasi Z source inverter

Abstract

The quasi-Z-source inverter (QZSI) is a single stage power converter derived from the Z-source inverter topology, employing an impedance network which couples the source and the inverter to achieve voltage boost and inversion. The quasi-Z-source inverter (qZSI) with battery operation can balance the stochastic fluctuations of photovoltaic (PV) power injected to the grid/load. This paper proposes a new topology of the energy-stored qZSI to overcome the discontinuous conduction mode during battery discharge. A new carrier based pulse width modulation (PWM) strategy for the (QZSI) which gives a significantly high voltage gain compared to the traditional PWM techniques is implemented. This technique employs sine wave as both carrier and reference signal, with which the simple boost control for the shoot-through states is integrated to obtain an output voltage boost. The conventional triangular wave carrier used in simple boost control technique is replaced by sine wave, which improves the shoot-through duty ratio for a given modulation index. The conventional perturb and observe maximum power point tracking algorithm is replaced by ANFIS based MPPT algorithm.