A Fault Tolerant Method for Open Circuit Faults of Permanent Magnet Direct Drive Wind Power System Converters

Abstract

The invention discloses an open-circuit fault tolerance method for a permanent magnet direct-drive wind power generation system converter. The method comprises the following steps: setting current Park vector characteristic reference values for various phases of a converter for fault tolerance in advance; acquiring current Park vectors of various phases of the converter for fault tolerance, and determining absolute values of current Park vector phases; sequentially carrying out derivation and absolute value determination on the obtained absolute values to obtain measured current Park vector characteristic values; and for each phase of the converter for fault tolerance, judging whether the measured current Park vector characteristic value of the phase exceeds the current Park vector characteristic reference value or not, if so, judging that the phase is in an open-circuit fault, and carrying out fault tolerance control aiming at the fault phase with the open-circuit fault for fault tolerance. The open-circuit fault tolerance method has the advantages of good robustness, high fault diagnosis accuracy, high fault diagnosis speed, good fault tolerance performance and high system stability.

Description

technical field [0001] The invention relates to a wind power generation system converter, in particular to an open-circuit fault tolerance method for a permanent magnet direct drive type wind power generation system converter. Background technique [0002] The converter is the core component and vulnerable link of the permanent magnet direct drive wind power generation system (PMSG), and IGBT open circuit faults occur from time to time. There are generally two stabilizing capacitors connected between the DC bus of the generator-side converter and the grid-side converter. [0003] The existing open-circuit fault tolerance method for the permanent magnet direct-drive wind power generation system converter has the following disadvantages: (1) The existing fault diagnosis technology uses the park vector amplitude as the fault diagnosis variable, and the identification algorithm is complex and the real-time performance is poor. Suitable for online detection. And the park vector...

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Problems solved by technology

[0003] The existing open-circuit fault tolerance method for the permanent magnet direct-drive wind power generation system converter has the following disadvantages: (1) The existing fault diagnosis technology uses the park vector amplitude as the fault diagnosis variable, and the identification algorithm is complex and the real-time performance is poor. Suitable for online detection

And the park vector amplitude is used as the diagnostic variable, the characteristics of the fault diagnosis variable are not obvious, and it is easily affected by external disturbances such as sudden changes in wind speed and grid voltage drops, and the robustness is poor; (2) Existing fault-tolerant converters mostly use In the way of phase redundancy, the faulty bridge arm is replaced by the spare bridge arm. Because the cost of the IGBT is higher than that of the bidirectional thyristor, the use of the spare bridge arm increases the hardware cost of the system; (3) The existing three-phase four-switch converter topology Since the midpoint of the two busbar capacitors is used for power supply, the voltage of the control busbar is constant, and the charging and discharging states of the capacitors are opposite, which will inevitably cause the voltage imbalance of the two busbar capacitors

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