Permanent magnetic direct-driven wind turbine generator set reinforced low-voltage ride through control method on the condition of power grid asymmetrical fault

Abstract

The invention discloses a permanent magnetic direct-driven wind turbine generator set reinforced low-voltage ride through control method on the condition of a power grid asymmetrical fault, wherein the method relates to controlling of a network-side converter and a machine-side converter of the permanent magnetic direct-driven wind turbine generator set. According to the method, based on sufficient consideration for capacity of a converter and operation condition of the set, positive-sequence and negative-sequence dq axis current given instruction of the network-side converter of the permanentmagnetic direct-driven wind turbine generator set are obtained; and furthermore a network-side converter PWM driving signal through spatial vector modulation of the obtained positive-sequence controlvoltage and the negative-sequence control voltage ualphagamma<+><+> and ualphagamma<-><-> and DC bus voltage Udc, so that the permanent magnetic direct-driven wind turbine generator set can suppressvoltage unbalance of a grid connecting point and maximally supply active current to the power grid, thereby remarkably improving low-voltage ride through capability of the permanent magnetic direct-driven wind turbine generator set on the condition of the power grid asymmetrical fault and electric energy quality of the connected power grid.

Description

technical field [0001] The invention relates to wind power generation technology, in particular to an enhanced fault ride-through control method for a permanent magnet direct drive wind turbine under an asymmetric fault in a power grid, and belongs to the technical field of new energy power generation. Background technique [0002] At present, permanent magnet direct drive wind turbines use permanent magnets for excitation, eliminating the need for components with high failure rates such as gearboxes, brushes, and slip rings. They have the advantages of salt spray corrosion resistance, simple structure, and low operating noise. Become one of the mainstream models in the wind power generation system. Since the permanent magnet direct drive wind turbine achieves machine-grid isolation through the full power converter, making full use of the capacity of the full power converter to compensate the voltage at the common point of the wind farm is the main means to improve the fault...

AI Technical Summary

Problems solved by technology

[0005] Literature (1) adopts the dual current loop control strategy under the double synchronous rotating coordinate axis system, or realizes the output of non-negative sequence current to the grid, or realizes that the output active power and the double frequency fluctuation of the DC side bus voltage are effectively suppressed, or realizes the output without There is no fluctuation in power and power, which improves the fault ride-through capability of the permanent magnet direct drive wind power system to a certain extent, but cannot achieve multiple operating objectives at the same time

Document (2) installs an energy storage device on the DC bus of the converter to absorb the 2-fold frequency fluctuation of the DC capacitor and the active power output by the generator to maintain a stable DC bus voltage without fluctuations, and eliminates the output through the grid-side converter. The negative-sequence component of the current or the double-frequency fluctuation of the output power enhances the fault ride-through capability of the wind power system and the power quality of the grid-connected system, but does not fully utilize the capacity of the grid-side converter, and the use of hardware equipment will inevitably increase total system cost

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