Dynamic reactive current direct control method by doubly-fed wind turbine generator set during grid fault

Abstract

The invention provides a dynamic reactive current direct control method by a doubly-fed wind turbine generator set during a grid fault. The method includes the following steps: a, judging whether a doubly-fed wind turbine generator enters a low voltage ride through mode or not, b, in normal operation, adopting a double closed loop control mode with the power on the outer loop and the current on the inner loop for the wind turbine generator set, c, if a protective action is not triggered during the fault, performing direct current control by the wind turbine generator after the wind turbine generator enters the LVRT mode, and d, if the grid fault causes the overcurrent of a rotor current converter or the overvoltage of a direct current capacitor, after the current converter enters a lockout state, performing protective action by a crowbar to bypass the current converter until the set engaged time is over and a frequency converter is controlled again. The dynamic reactive current direct control technology by the doubly-fed wind turbine generator set during the grid fault can achieve that during the fault, the wind turbine generator set injects a reactive current into a power grid fast and provides voltage support, and helps the wind turbine generator set to achieve low-voltage riding through.

Description

technical field [0001] The invention relates to a control method in the technical field of grid-connected wind turbines in new energy power generation technology, in particular to a method for direct control of dynamic reactive current of doubly-fed wind turbines during grid faults. Background technique [0002] In recent years, with the continuous growth of my country's wind power installed capacity, the proportion of wind power in the power grid has continued to increase, and the problems brought by wind power grid integration to the safe and stable operation of the power system have become more and more serious. In my country's power grid, there have been many large-scale wind turbine off-grid accidents caused by wind turbines not having low-voltage ride-through capability. From January to April 2011, there were more than 30 electrical equipment failures in the wind farms in Jiuquan, Gansu. The accidents caused the voltage of the grid-connected points of each wind farm to...

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Problems solved by technology

There are still some problems in the current research: most of the literature proposes the indirect current control during the fault period, that is, the reactive power is sent through the power control loop and then the current loop control, because the time constant of the power loop is usually the current loop time constant 10 to 100 times of that, there is a certain time delay in dynamic reactive power injection, which affects the rapidity of dynamic reactive power injection

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