A multi-scale low-wear fit method to reduce the number of switching times of doubly-fed fan crowbar

Abstract

The invention discloses a multi-scale and low-through cooperation method for reducing the number of double-fed fan crowbar switching times. First, the voltage of the grid-connected point of the double-fed fan is monitored in real time, and whether the rotor current will exceed the limit is estimated to determine the control strategy. Then, in the control link of the rotor-side converter, switch to the low voltage ride-through control strategy that comprehensively considers the time scale and current scale. This strategy strictly follows the requirements of wind power grid-connected regulations. Finally, switch back to the space vector control strategy in time or choose to cut off the fan according to the recovery of the grid-connected point voltage. The method of the present invention can effectively improve the low-voltage ride-through ability of the doubly-fed fan, reduce the number of switching times of the crowbar, and prevent the fan from absorbing a large amount of reactive power from the system during the crowbar input, which is very important for ensuring the voltage stability of the power system. significance.

Description

technical field [0001] The invention belongs to the field of electric power systems, relates to the field of stability of electric energy transmitted outside the grid of a doubly-fed wind farm, and in particular relates to a multi-scale low-wearing matching method for reducing the number of switching times of a doubly-fed fan crowbar. Background technique [0002] At present, the doubly-fed asynchronous wind power system stands out due to its advantages such as wide speed regulation range, independent adjustment of active and reactive power, and small required excitation frequency converter capacity, occupying most of the wind power market share. However, the doubly-fed fan is sensitive to grid faults because the stator is directly connected to the grid; and the rotor is indirectly connected to the grid through the converter, making the electromagnetic transient process after the fault very complicated. After the voltage drops, the doubly-fed wind turbine will have the trans...

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Problems solved by technology

[0003] In order to solve the above-mentioned problem that the wind field is difficult to meet the low-voltage ride-through standard due to the complex fault characteristics of the doubly-fed fan, the present invention proposes a multi-scale low-voltage ride-through matching method that reduces the number of switching times of the doubly-fed fan crowbar. Under the premise of not damaging the converter, use the upper limit of the over-excitation of the converter as much as possible to improve the low-voltage ride-through capability of the fan and reduce the number of crowbar switching

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