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

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.