Penetration of solar photovoltaic (PV) power into the electricity grid
is increasing due to the advancement and cost reduction in power
electronic devices, many incentive programmes introduced by
government and advantages such as environment friendly
behaviour, low maintenance cost [1–4] etc. The most important
aims in grid-connected large PV system are to reduce cost,
improve efficiency and reliability of both the PV panels and
converters [5, 6]. To achieve these, single-stage three-phase
dc-to-ac power converter system is the best choice.
For single-stage grid-connected PV system, mainly four control
schemes: namely, grid synchronisation, current control, voltage
control and maximum power point tracking (MPPT) [7] are
implemented. As the power and current characteristics of PV
module are non-linear, the MPPT controller becomes prominent
part of the PV power generation system to maximise the utilisation
of PV module. Also, the PV power depends on the atmospheric
temperature and solar irradiations which vary with time. Therefore,
it is necessary to develop an effective algorithm for MPPT, which
should continuously monitor the terminal voltage and current, to
match with the corresponding MPP values. For large PV system,
the array is constructed by the combination of several PV modules
and they are exposed to larger area. Non-uniform irradiation
condition creates, sometimes, unavoidable partially shaded
conditions (PSCs) in PV array as some parts of array receive less
intensity of sunlight.