Improved torque limit control method based on doubly-fed wind turbine generator

Abstract

The invention discloses an improved torque limit control method based on a doubly-fed wind turbine generator. The method comprises the following steps that: when a frequency disturbance accident occurs in a power system after wind power integration, the active output of the doubly-fed wind turbine generator is instantaneously increased, and then the active output is reduced by a quadratic functionof a rotating speed until the difference between the output electromagnetic power of a doubly-fed turbine and the captured mechanical power is close to zero; and then the active power of the doubly-fed wind turbine slowly descends along with time in a slope manner, then is kept constant until the active power is equal to the maximum power tracking output value, and finally returns to the maximumpower tracking control state. According to the invention, the doubly-fed turbine is enabled to have a faster rotating speed recovery speed, the problem of secondary frequency drop can be avoided to the greatest extent, and the lowest frequency drop point can be effectively improved in different frequency responses.

Description

Technical field [0001] The present invention relates to an electromechanical control technology, specifically to a method of controlling the torque limit based on improved doubly fed wind turbine. Background technique [0002] In recent years, variable speed wind turbine (the WTG) double-fed induction generator (the DFIG) as a typical representative of its advanced control performance, the market has become the most widely used wind turbines. The rotor unit is flanked by the inverter to realize variable speed wind turbine control constant frequency, the maximum wind energy capture. However, the power electronic converter allows fan speed and power grid frequency decoupling, its rotor rotational kinetic energy reserves can not effectively release, almost no contribution to the inertia of the power system, which will adversely affect the stability of frequency. So, how to get involved in wind turbine system frequency control is the key to the security and stability maintenance. Cur...

AI Technical Summary

Problems solved by technology

However, since the control process only establishes the active-time relationship, ignoring the changes in rotational speed and mechanical power, it is easy to cause excessive release of rotor kinetic energy

At the same time, the inertial response capability of the fan will weaken as the speed decreases, resulting in insufficient follow-up active power during the frequency recovery process, resulting in a secondary frequency drop phenomenon

When the system frequency drops twice, it will seriously affect the power quality and affect or even destroy the production process of various departments

At the same time, it will cause great harm to the steam turbine in the power plant, causing a significant drop in the output of the thermal power plant's machinery, resulting in a reduction in the output of the generator, a lack of power, a further drop in frequency, and even a frequency collapse.

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