A method to reduce active power loss of doubly-fed induction wind turbine

Abstract

The invention discloses a method for reducing active power loss of a double-fed inductive wind generation set. The double-fed inductive wind generation set comprises a wind turbine, an induction motor, a back-to-back converter and a transformer. The method comprises the following steps: (1) setting the active power scheduling value and a reactive power scheduling value of the double-fed inductive wind generation set; (2) decomposing the active power loss of the double-fed inductive wind generation set; (3) setting reactive power output of a grid-side converter to reduce the active power loss caused by the reactive power output of the double-fed inductive wind generation set; (4) setting a slip ratio of a rotor to reduce the active power loss caused by the active power output of the double-fed inductive wind generation set; (5) the sum of the minimum value of the active power loss caused by the reactive power output and the minimum value of the active power loss caused by the active power output is the minimum power loss of the double-fed inductive wind generation set. The method can reduce the active power loss of the double-fed inductive wind generation set and increases the energy conversion efficiency in the premise that the double-fed inductive wind generation set accepts power grid scheduling.

Description

technical field [0001] The invention relates to an operation control of a wind turbine, in particular to a method for reducing the active power loss of a double-fed induction wind turbine. Background technique [0002] From the perspective of the operation of independent wind turbines, the purpose of control is mostly to pursue the maximum active power output. From the perspective of reducing the active power loss of wind turbines, it is hoped that the smaller the reactive power output, the better. For example, when operating according to the unit power factor, its reactive power output is zero. However, with the continuous increase of wind power grid-connected capacity, in order to increase reactive power support and reduce the demand for active power reserve capacity, variable-speed wind turbines, such as doubly-fed induction motors and direct-drive permanent magnet synchronous motors, are dispatched in the same way as conventional thermal power and hydropower units. Both...

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Problems solved by technology

[0003] For wind power systems with doubly-fed induction wind turbines, the existing research methods for reducing active power loss mostly start from the optimization of conventional grid losses, and reduce the active power loss of the grid by adjusting the active and reactive output of wind turbines, but the conventional grid loss The optimization method does not take into account the active power loss of the wind turbine itself, resulting in a large active loss of the DFIG, increased winding temperature, and low energy conversion efficiency, which reduces the reliability and service life of the DFIG

Moreover, when the wind speed of the wind turbine is low, the active output of the doubly-fed induction wind turbine often does not reach the active power dispatch value, so the doubly-fed induction wind turbine can only return to the maximum power point tracking operation mode, and the optimization method of the conventional power grid loss does not work , cannot effectively reduce the active loss

[0004] In the prior art, under the current wind speed, the wind turbine adopts an optimization algorithm to determine the reactive power output of the grid-side converter of the doubly-fed induction wind turbine and the rotor speed of the wind turbine to reduce the active power loss, but due to the actual The wind speed is uncertain, and the stator voltage of the doubly-fed induction wind turbine changes with the change of the grid operation mode, which leads to complex calculation process and low calculation efficiency of the optimization algorithm

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