Grid-Forming Control for A Novel Doubly Fed Induction Wind-Storage Generator

The doubly fed induction wind generator with grid-forming control is usually equipped with energy storage battery. However, energy storage battery requires an additional converter to connect to the DFIG system in the traditional topology, which increases costs and power loss. In order to solve this problem, energy storage battery is directly connected to the midpoint of the negative DC bus of the rotor-side converter in the novel doubly fed induction wind-storage generator. Energy storage battery power can be controlled by regulating the radio of positive and negative small vectors in the modulation of the rotor-side converter. Due to that the output power of the wind turbine is difficult to respond to the frequency fluctuation of the grid under the maximum power point tracking (MPPT) control, a collaborative grid-forming control strategy where the DFIG always works in the MPPT state is proposed based on that the DC bus voltage is controlled by energy storage battery. The DC bus voltage regulation capability of energy storage battery is discussed. The effectiveness of the proposed grid-forming control strategy for the novel doubly fed induction wind-storage generator is validated by simulation results.