Control method for enhancing asymmetrical fault ride-through capability of wind power system

Abstract

The invention discloses a control method for increasing asymmetrical fault ride-through capability of a wind power system. In the method, a super capacitance energy storage system is assessed between a machine side rectifier and a net side inverter on the basis of the prior art. On the control aspect, besides the control for the machine side rectifier and the net side inverter, the control for a super capacitance energy storage system is additionally provided in the method. Through controlling the coordination of the machine side rectifier and the net side inverter, a unit can realize the maximum wind energy tracking, grid-connected active and reactive power adjusting and grid-connected three-phase current symmetry and the stability of the voltage for a direct-current busbar between the machine side rectifier and the net side inverter when a power grid is normal is assured. The additionally provided super capacitance energy storage system is further controlled, the voltage stability of the direct-current busbar of the unit while the power grid has asymmetrical faults is assured, especially the grid-connected three-phase current symmetry is assured and the double power frequency ripple wave of the voltage of the direct-current busbar while the power grid has asymmetrical faults is removed so that the asymmetrical fault ride-through capability of the wind power system is enhanced.

Description

technical field [0001] The invention relates to a wind power system of a grid-connected direct-drive permanent magnet synchronous wind power generating set, and a control method for improving its ride-through capability when an asymmetrical fault occurs. Background technique [0002] Electricity generated by wind power (wind power) is green energy. Except for very small wind turbines, wind turbines are first integrated into the grid, and then supply power to users through the grid. With the continuous increase of grid-connected wind power capacity, its impact on the grid cannot be ignored. Therefore, the grid code requires that the wind power system will not run off-grid under the specified range of grid faults. Therefore, how to ensure that the wind power system will not be disconnected from the grid during the grid fault period, that is, to ensure that it "passes through" the grid fault period, has become an important issue unique to the wind power system. Among the curr...

AI Technical Summary

Problems solved by technology

Those skilled in the art know that the double power frequency ripple contained in the DC voltage still has a certain degree of adverse effect on the safe operation of the back-to-back converter

The practice of "choosing the latter in the two aspects of eliminating the double-frequency ripple of the DC voltage and maintaining the symmetry of the three-phase current" in this prior art is just that "the lesser of two evils" cannot be done.

Images