Grid Synchronization of Spy-BES DG System using Seamless Control with Power Quality Improvement

This paper presents a robust control for a renewable source SPV (Solar Photovoltaic) based distributed generated (DG) system, which is capable of the smooth transition from an islanded mode (IM) to the grid-connected mode (GCM). The DGS has BDDC (Bidirectional DC-DC converter), SPV array, voltage source converter (VSC), and nonlinear/linear loads. The POI (Point of Interconnection) voltage is maintained through the VSC and peak power extraction from the PV array, is obtained by a BDDC in the GC mode. In GC mode, a robust shrinkage linear complex valued LMS control offers smooth operation while removing the DC offset and harmonics at unbalanced load conditions and improves the power quality. In the grid fault condition, the battery energy storage (BES) is used to operate. This system in the islanded mode of operation for feeding the extra power into it. Moreover, the grid synchronization mode of operation is achieved by the phase-locked loop (PLL) synchronization control. The DGS system with the shrinkage linear complex valued LMS control is validated in MATLAB under the PV variation in irradiance, unbalanced loads and grid voltage distorted conditions.