Grid-Connected MPPT Control for MG Operating under Partially Shaded Condition - Intelligent Computing for Sustainable Energy and Environment - page 46

Grid-Connected MPPT Control for MG Operating
under Partially Shaded Condition

Xuemei Zheng * , Chun Wang, and Yi Ren

School of Electrical Engineering and Automation,
Harbin Institute of Technology, Harbin, China
[e-mail]

Abstract. This paper investigates the control performance of a physical
configuration of a microgrid, integrated with photo-voltaic (PV) arrays, battery
energy storage systems, and variable loads. The main purpose is to achieve
optimal control under grid connected for this microgrid. In order to improve the
conversion efficiency of PV arrays under partially shading conditions (PSC),
we use a maximum power point tracking (MPPT) algorithm developed by Ji et
al [11] based on analyzing the P-V and I-V output characteristics under PSC.
Then, a voltage source inverter based on swoop control is used to control the
MG connection to the grid in order to get the maximum power to the grid. Both
simulation and experimental results confirm that the proposed method can
achieve optimal grid-connected control of the MG system.

Keywords: PV array, Partial Shading Condition, MPPT algorithm, Droop
control, Microgrid.

1 Introduction

The ever-increasing demand for low-cost energy and growing concern about
environmental issue has generated enormous interest in the utilization of the
nonconventional energy sources such as the solar energy. The freely and abundantly
available solar energy can be easily converted into electrical energy using
photovoltaic (PV) cells. A PV source has the advantage of low maintenance cost,
absence of moving/ rotating parts, and pollution-free energy conversion process.
However, a major drawback of PV source is its ineffectiveness during the nights or
low insolation periods or during partially shaded conditions (PSC). These drawbacks
notwithstanding, the PV systems have emerged as one of the most popular
alternatives to conventional energy because it is a environmental source.
A major challenge in use of PV is posed by its nonlinear current-voltage (I-V)
characteristics, which result in a unique maximum power point (MPPT) on its power-
voltage (P-V) curve. The matter is further complicated due to the dependence of these
characteristic on solar insolation and temperature. As these parameters vary
continuously, MPPT also varies. Considering the high initial capital cost of a PV
* The paper is supported by the Natural Science Foundation of HeiLongJiang Province of
China (E200918).