A Calculation Method for Overspeed Off-grid Critical Time of Doubly-fed Wind Turbines

Abstract

The invention relates to a computing method for double-fed wind power unit overspeed off-grid critical time. The computing method is characterized in that the method is started with setting up an electromechanical transient mathematic model after a DFIG is disturbed, the effects on the electromechanical transient of the factors such as the initial operation conditions, disturbance intensity and Crowbar protection motions of the DFIG are analyzed, the conditions reaching overspeed protection motions of a DFIG unit are deduced, and a wind power unit off-grid living example in a certain wind power field is analyzed through the provided method, and the wind power unit with the overspeed protection motions is correctly recognized according to the calculated time from acceleration to overspeed protection motion fixed values of rotors of all units. The computing method has the advantages of being simple and rapid in computing, high in evaluation accuracy and application value, wide in on-line application prospect and the like.

Description

technical field [0001] The invention relates to the field of overspeed off-grid of double-fed wind turbines, and proposes a calculation method for the critical time of overspeed off-grid of double-fed wind turbines. The method analyzes the off-grid instance of a wind turbine group in a wind farm, and according to the calculated The time for the rotor to accelerate to the overspeed protection action setting value correctly identifies the wind turbine with overspeed protection action. Background technique [0002] With the rapid development of global wind power, China has planned eight 10 million-kilowatt wind power bases, and has now become the country with the largest installed capacity in the world. Serious safety issues have brought impact to the connected power grid. Ensuring the safe operation of wind turbines has become the focus of attention of power companies and scientific researchers, which is of great significance. [0003] There are many causes of large-scale win...

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Problems solved by technology

[0003] There are many causes of large-scale wind turbine off-grid accidents. Traditional research mainly focuses on the analysis of the electromagnetic transient process of wind turbines caused by grid voltage sag disturbances and the problem of low voltage ride through. In fact, crowbar protection is mainly used in wind power inverters. In the low-voltage ride-through technology of the inverter, it is used on the rotor side of the wind turbine to bypass the rotor-side converter. Although the Crowbar protection action protects the operation safety of the rotor-side converter during the electromagnetic transient process, its action Finally, the original torque balance condition of the double-fed wind turbine is broken, and the electromechanical transient process is triggered. If a new torque balance can be established in the subsequent electromechanical transient process, the speed of the double-fed wind turbine can be stabilized; If the new torque balance cannot be achieved, the doubly-fed wind turbine still has the risk of overspeeding and off-grid

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