Research on frequency inertia response control strategy of SCESS-DFIG system considering variable wind speed

Abstract

The doubly fed induction generator (DFIG) has insufficient capacity to respond to the frequency inertia of the power grid due to the isolation between the rotor kinetic energy and the power grid by the generator-side converter. At the same time, the ‘source’ of the DFIG cannot be as stable as the thermal generator, so sudden changes in the wind speed on the ultra-short time scale can affect the system inertia. In this study, the inertia of a doubly fed wind generator with a super capacitor energy storage system (SCESS-DFIG) is defined from the standpoint of a single machine. Based on fuzzy logic controller, an inertia response control strategy of multi energy coordinated control is proposed. Then the SCESS-DFIG inertia response control strategy under variable wind speed is proposed at the wind field level. Based on the establishment of DFIG, DC bidirectional buck–boost converter, and supercapacitor energy storage unit model, a wind farm with three SCESS-DFIGs is simulated. When the grid frequency is dropped, the effectiveness of the proposed control strategy is verified by simulating their operation under the same rated parameters, different wind speed curves, and different initial voltages of the supercapacitors.

Keywords

• supercapacitors
• energy storage
• power generation control
• fuzzy control
• power grids
• wind turbines
• wind power plants
• power convertors
• asynchronous generators
• rotors
• grid frequency
• different wind speed curves
• SCESS-DFIG system
• variable wind speed
• doubly fed induction generator
• insufficient capacity
• frequency inertia
• power grid
• rotor kinetic energy
• generator-side converter
• thermal generator
• ultra-short time scale
• system inertia
• doubly fed wind generator
• super capacitor energy storage system
• fuzzy logic controller
• multienergy coordinated control
• SCESS-DFIG inertia response control strategy
• wind field level
• DC bidirectional buck–boost converter
• supercapacitor energy storage unit model
• wind farm