Inertial frequency-modulation drive rotating speed protection control system and method for doubly-fed wind turbine

Abstract

The invention discloses an inertial frequency-modulation drive rotating speed protection control system and method for a doubly-fed wind turbine. A wind speed detection module collects the wind speed, the rotating speed of a fan and the pitch angle parameter. According to a rotating speed protection control link, the real-time captured mechanical wind power of the fan is computed according to information collected by the wind speed detection module, and a loss computing module is connected with the rotating speed protection control link, the loss is subtracted from the real-time captured mechanical wind power; and the obtained computing result is compared with electromagnetic power output by a generator, an input and output power difference caused when the doubly-fed wind turbine participates in system frequency modulation is obtained, the input and output power difference is transmitted to a proportional link and an integration link through a trigger switch, the negative feedback power control quantity is output after the proportional link and the integration link act, and the negative feedback control quantity and an inertial frequency-modulation control signal jointly serve as a frequency modulation additional active power given value. By means of the inertial frequency-modulation drive rotating speed protection control system and method, secondary impact on the system frequency when the doubly-fed wind turbine exits from the frequency modulation can be avoided, and the problem that the power loss is large due to that fact that the rotating speed in the constant rotating speed region is overly lowered is solved.

Description

technical field [0001] The invention relates to an inertial frequency modulation active speed protection control system and method for a double-fed wind power unit. Background technique [0002] The doublyfed-induction generation (DFIG) has the characteristics of high power generation efficiency and small capacity of the frequency converter. However, its power electronic converter realizes maximum power tracking and also eliminates the coupling between the rotor speed and the grid frequency. relationship, the frequency change of the system cannot be damped by releasing or storing the kinetic energy of the rotor like a traditional synchronous generator. From the perspective of the whole system, the moment of inertia of the wind turbine based on the DFIG unit is zero. In the initial stage of power grid load disturbance, the inertia of the system directly affects the rate of change of frequency, and the reduction of inertia will significantly weaken the frequency dynamic respon...

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Problems solved by technology

[0002] The doublyfed-induction generation (DFIG) has the characteristics of high power generation efficiency and small capacity of the frequency converter. However, its power electronic converter realizes maximum power tracking and also eliminates the coupling between the rotor speed and the grid frequency. relationship, the system frequency change cannot be damped by releasing or storing the kinetic energy of the rotor like a traditional synchronous generator. From the perspective of the whole system, the moment of inertia of the wind turbine based on the DFIG unit is zero

In the initial stage of power grid load disturbance, the inertia of the system directly affects the rate of change of frequency, and the reduction of inertia will significantly weaken the frequency dynamic response characteristics of the system, resulting in excessive frequency fluctuations after the system encounters load disturbance, which does not meet the requirements of power grid guidelines

[0003] In order to reduce the influence of DFIG unit connection on the frequency stability of the grid, the improvement methods that utilize the frequency regulation capability of wind turbines are mainly divided into two categories: one method is to reduce the normal working efficiency of the generator through overspeed or pitch change to obtain a backup The capacity participates in the system's primary frequency regulation load-shedding control method. Although the load-shedding control method can obtain spare capacity, it reduces the economic benefits of the wind turbine during normal operation, and the uncertainty of wind speed prediction has a greater impact on the reserve capacity of the wind turbine. , so the scope of application is small; the other is to use the kinetic energy stored in the rotor for short-term frequency modulation, and to simulate the inertial frequency modulation control of the characteristics of synchronous generators. Compared with traditional synchronous generators, DFIG units have greater mechanical inertia and speed can be adjusted Larger range can theoretically simulate more inertia

[0004] However, the known fixed speed limit speed protection method does not take into account the influence of wind speed conditions on the frequency regulation capability of the wind turbine and the secondary fluctuation of the system frequency caused by the wind turbine exiting frequency regulation.

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