Direct-drive fan high-penetration improved control based on virtual synchronization technology

Abstract

The invention provides an improved control scheme for increasing the controllability of the GSC by dynamically adjusting the voltage of a DC bus during high voltage penetration, aiming at solving the problems that the transient overvoltage of a power grid easily causes that the grid-side converter of a direct-driven fan reaches the upper limit of the AC voltage regulation, so that the AC / DC power coupling oscillation is caused, and the instability or overvoltage generator tripping protection is caused. According to active control, the VSG technology is improved, a power compensation item is designed, system frequency support is added externally, and bus voltage fluctuation is reduced internally; reactive control is based on industrial standards, and voltage recovery is supported by injecting reactive current into a power grid. The improved control effectively improves the fault continuous ride-through capability of the unit, improves the power generation efficiency and the electric energy quality of the fan, and improves the system stability.

Description

technical field [0001] The invention relates to the field of inverter control for distributed power generation micro-grids, in particular to an improved high-throughput control of direct-drive wind turbines based on virtual synchronization technology. Background technique [0002] The effective consumption of large-scale wind power often requires a high-voltage external transmission system. However, in a typical large-capacity new energy delivery project, the sending end system has a certain electrical distance from the main grid, and the capacity of the nearby supporting thermal power units is insufficient, making it a "weak support" grid characteristic. [0003] A power grid with such characteristics, when various faults occur, is likely to cause large fluctuations in frequency and voltage, and trigger wind turbines to go off-grid, and even cause chain reactions in serious cases, causing blackouts. The design of the fan fault ride-through strategy helps to enhance the uni...

AI Technical Summary

Problems solved by technology

Although the research results of improving the fault ride-through capability from the perspective of the system station are relatively rich, the actual feasibility is insufficient. Therefore, it is necessary to fully develop and improve the reactive power support capability of the wind turbine itself.

[0004] The transient overvoltage of the power grid will easily cause the grid-side converter to reach its upper limit of AC voltage regulation, resulting in AC-DC power coupling oscillation, causing instability or overvoltage shutdown protection

For transient overvoltages, in addition to the hazards of breaking down devices or triggering off-grid, the fault will also affect the GSC's ability to control output active and reactive power, and easily cause AC-DC coupled power oscillations

Affected by the modulation method and the DC bus voltage, there is an upper limit for the voltage amplitude of the AC side of the GSC When the transient overvoltage reaches , it will exceed the controllable range of the GSC; if the GSC control strategy remains unchanged, on the one hand, the DC side U dc On the one hand, the unit power factor output of the AC side is maintained, which may easily cause AC-DC power coupling oscillation, and then become unstable and off-grid

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