Auxiliary frequency controllers for the black start of stand-alone systems with predominance of wind generation

摘要

This paper proposes a novel control approach and supplementary controllers to support the black start of stand-alone systems with predominance of wind generation based on fully rated converter. The main purpose of the proposed control approach is to provide auxiliary frequency control during the black start of stand-alone systems. The proposed controllers, based on the signal of the system frequency error, are added to the grid-side and generator-side converters of the wind generation unit. One of the supplementary controllers, which act on the speed reference of the wind turbine, aims to extract kinetic energy from the wind turbine. The second supplementary controller aims to temporarily extract additional electrical energy from the DC link capacitor by acting on the typical control loops of the grid-side converter. The energy extracted from the wind turbine and DC link capacitor is injected into the grid to quickly contribute to the frequency control during the black start of the system. The proposed controllers are coordinately designed by means of a genetic algorithm optimization technique which minimizes the deviations of the frequency and DC link voltage during the controller design process. The proposed operational and control approach has significantly improved the frequency nadir during the restoration process of the stand-alone system.