αβ-MDSC-MFLL Control with Positive Sequence Extraction and DC Offset Rejection for a Grid-Tied Solar PV-BES Based Power Conversion System

The nonlinear loads demean the system power quality leading to increased ohmic losses and shorter equipment lifespan. To mitigate power quality challenges, this work proposes a multiple delayed signal cancellation filter with 15 layers and unit delay factor (MDSC ¹ 15) for improved power quality of a grid-tied solar power conversion system (SPCS) equipped with a battery energy storage (BES). The control attenuates all integral positive sequence harmonic components from 2 ^nd to 30 ^th harmonics excluding positive sequence 16 ^th harmonic. It also eliminates integral negative sequence harmonic components from 1 ^st to 28 ^th harmonics excluding negative sequence 14th harmonic, including 0 Hz DC component, without the need of additional prefilters cascaded to the filter. A modified frequency locked loop (MFLL) is incorporated to make the MDSC ¹ 15 adaptive to the varying grid frequency and make it immune to phase angle jump and frequency fluctuations in the grid voltages. The MDSC ¹ 15-MFLL improves the power quality of SPCS during grid adversities and load current irregularities. Performance of MDSC ¹ 15-MFLL is validated in MATLAB during several dynamic test cases and compared with other delay-based controls to ensure better performance and commitment to the IEEE std. 519 during operation of SPCS.