Control of Three-Phase Grid Integrated Multiple Solar Photovoltaic Arrays-BES Based Microgrid

摘要

This work presents a three-phase grid integrated multiple solar photovoltaic (PV) arrays-battery energy storage (BES) with a bidirectional converter based microgrid (MG) system. Two solar PV arrays with an individual incremental conductance (InC) maximum power point (MPP) tracking technique for the maximum power extraction in an economical and efficient single stage configuration are integrated to an independent DC link of main voltage source converter (VSC) and ancillary VSC. These VSCs relate to individual nonlinear loads, at the point of common coupling (PCC) and are connected in parallel, which facilitate the MG expansion to transfer active power to the grid, and to enhance the reliability and performance of MG system in off-grid mode. The main VSC works with the current control, in usual conditions in the grid interactive mode and at the occurrence of some faults or interruption in the grid, main VSC switches over to the voltage control in an off-grid mode. The utilization of power electronics switch ensures the fast and transient free transition operation between these two modes of main VSC. A buck-boost converter is connected with BES at the DC link of main VSC, which manages the charging and discharging process of it in accordance to base and peak load demands, correspondingly and maintains voltage for MPP tracking at its DC link. The voltage control for main VSC, maintains the frequency and voltage at PCC, hence distributes a reliable and continual power to loads and provides voltage for the ancillary VSC, to work with current control. The current control for both VSCs utilizes the PV array power feed-forward constituent to improve system’s dynamic performance and to improve the power quality issues i.e. harmonics current mitigation and correction of power factor. The system’s performance is observed satisfactory for steady state and dynamic scenarios like, solar insolation change, load unbalance and is validated with MATLAB / SIMULINK.