Multi-scale low-ride-through matching method for reducing the switching times of the doubly-fed wind generator crowbar

Abstract

The invention discloses a multi-scale low-ride-through matching method for reducing the switching times of a doubly-fed wind generator crowbar. Firstly, the grid-connected point voltage of the doubly-fed wind generator is monitored in real time, and whether the current of a rotor is to be out of limit or not is estimated, so as to determine the switching time of a control strategy; then, in the control link of a rotor side converter, a low-voltage ride-through control strategy for comprehensively considering time scale and current scale is switched, wherein the strategy strictly meets the requirements of wind power grid-connected specifications, and is characterized in that the combination of de-excitation control and crowbar protection is carried out; finally, a space vector control strategy is timely switched back according to the recovery condition of the grid-connected point voltage, or the wind generator is removed. By adoption of the method, the low-voltage ride-through capability of the doubly-fed wind generator can be effectively improved, the number of switching times of the crowbar is reduced, and the wind generator is prevented from absorbing a large amount of reactive power from the system during use of the crowbar, thereby playing important practical significance for guaranteeing the voltage stability of the power system.

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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