A new MAF based αβEPMAFPLL for grid connected RES with improved performance under grid faults

Diversifying the role of renewable energy sources (RES) and in particular, the role of the grid side converter (GSC) has gained a lot of attention recently. This is a result of the need for more advanced built-in control systems that facilitate support of the grid during abnormal conditions. Distributed renewable generation can provide auxiliary support if GSC controllers are suitably developed and designed. To this end, the control of GSC relies significantly on the fast and accurate extraction of grid voltage phase angle. In addition, the control system must respond fast, be accurate during transient events and present low computational burden to the GSC which must perform a lot of other peripheral tasks. The phase angle extraction is done using phase-locked loop (PLL) algorithm and its response is critical under off-nominal grid conditions such as grid faults, frequency variations etc. Moving average filter (MAF) based PLL techniques provide a better option, however, in some cases these techniques are inaccurate. The work presents a new MAF based PLL that is faster, accurate under any grid disturbances and with significantly improved transient response. The improved performance of proposed αβEPMAFPLL is validated through simulation and experimental results.