An Automatic-Tuning Scheme Based on Fuzzy Logic for Active Power Filter in Wind Farms

This brief proposes a novel scheme based on fuzzy logic for automatically and appropriately adjusting the main control coefficient of a shunt active power filter (SAPF), which is used to efficiently regulate the voltage and current harmonic distortions in the grid with a large offshore wind farm connected. With the scheme, the SAPF can be operated in two different control modes based on the voltage detection method. In the first mode, the SAPF has an objective to control the total harmonic distortion (THD) of grid voltage at the point of common coupling (PCC). In the second mode, the SAPF can reduce the THD of both grid voltage and current at the PCC. In addition, a unique setting module is designed to suitably choose the output scaling factor of the proposed fuzzy logic controller in the scheme; this is to considerably enhance adaptability of the scheme. Limits for the actual current and the control coefficient of the SAPF are also utilized to ensure the safety in operation. Simulations demonstrate that the suggested scheme has good performance in automatically tuning the control coefficient of the SAPF to regulate the THD of grid voltage and current to acceptable values even under unexpected changes in configuration of the grid.