Vector Control Versus Synchronverter Control of Synchronous Generator in Wind Energy Conversion

This paper presents two control strategies for wind power plants to improve their ancillary services. To achieve these goals, hierarchical control scheme is proposed for the wind turbines: Local and global controls. The local control is used to regulate voltage and frequency according to the state of the wind plant connection point to the grid. For frequency control, two approaches are proposed: the first is based on the conventional frequency droop; the second is inertial, based on power extraction from the wind turbine and generator inertia. The global control (hierarchically superior to the local one and supervised by the power system dispatching) is used to meet the transmission system operator requirements, by ensuring operation with energy reserves or energy curtailment. These local and global controls have been achieved using two strategies: classical vector control and recent synchronverter control. The second strategy is the control based on the concept of synchronverter where the grid side inverter emulates the mathematical model of conventional synchronous generator. The different advanced controls have been implemented and tested. As important results, an improvement of wind plant ancillary services has been achieved and better performances of synchronverter control have been experienced versus classical vector control.