In a power grid lacking conventional power sources for black-start

adopting wind farm as a black-start power source is a meaningful effort. The lack of frequency support caused by the decoupling of wind turbine speed from the main system frequency can be avoided in the virtual inertia control mode

thus the frequency stability can be efficiently enhanced. A new cooperative frequency control strategy is introduced based on the adaptability analysis of conventional virtual inertia strategies in the black start scenario. Firstly

based on a practical project

a back-start method for wind farms is proposed by adopting diesel generator as a matched support power supply with small capacity

and the main problems and process of wind farm black-start are analyzed. Secondly

through the flexible switching of additional power loop control and tracking curve switching control at different start stages

and supplemented by regulating frequency response strategy involved pitch angle

a cooperative frequency control strategy based on the virtual inertia theory is proposed. Finally

the results of the simulation using PSCAD show the rationality and advantage of the proposed strategy.