A method and device for controlling a wind power generating set

Abstract

The invention discloses a controlling method and device for a wind generating set. Under the conduction that the measuring rotational speed of generators is larger than a rated rotational speed, and measuring power surpasses rated power, torque is converted into a constant power control mode from a variable parameter PI control mode; under the condition that a variable pitch angle is smaller than an optimal variable pitch angle, and the measuring rotational speed decreases under the rated rotational speed, the torque is converted into the variable parameter PI control mode from the constant power control mode; the variable pitch angle is controlled by adopting a PI control parameter nonlinear adjusting mode; variable pitch control is in activation state within whole normal work speed range. The scheme can realize flexible switch of control states, ensures the stability of generator set operation and power output, adopts variable parameter PI control on the torque, can efficiently enhance torque controlling force in transition section, reduces action frequency and spectrum of the variable pitch in the section, and reduces generating capacity loss and system loading caused by the advanced action of the variable pitch before the wind generating set is in fully loaded running.

Description

technical field [0001] The invention relates to the technical field of control of wind power generators, in particular to a control method and device for wind power generators. Background technique [0002] The current control scheme of variable speed and variable pitch wind turbines is to use maximum power point tracking control to obtain the maximum wind energy at low wind speeds, and to use pitch control to limit wind energy absorption to keep power constant at high wind speeds. More specific implementations use figure 1 method shown. In the figure, the three sections AB-BC-CD are the speed-torque relationship curves below the rated power of the generator. Point A corresponds to the generator reaching the minimum grid-connected speed. Section DE is the speed-torque relationship curve after reaching the rated power of the generator. Point D corresponds to Rated power, the corresponding generator speed is the rated speed. Among them: AB section and CD section use PID con...

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Problems solved by technology

[0003] This method can make the wind turbine set in the optimal Cp control area to obtain the maximum wind energy in the area below the rated power, but it also has the following disadvantages: 1) The control transition between the CD section and the DE section is at the rated power point D, and there is no corresponding transition Because the natural wind conditions exist in turbulent state, when the wind speed fluctuates above and below the rated wind speed, the torque and pitch control will be switched frequently. Since the response speed of the pitch control lags behind the torque control, the two controls are not synchronized, resulting in the speed at Large fluctuations occur up and down, resulting in an impact on the unit; 2) The output power of the generator is the product of the speed and torque. Due to the influence of turbulent wind, the pitch control in the DE section cannot completely maintain the speed at the rated value. The use of constant torque control will cause the output power to change with the change of the generator speed, which will reduce the quality of the generated power; 3) The linear interpolation method used to calculate the parameter values ​​of the variable pitch PI controller in the DE section cannot effectively reflect the nonlinear aerodynamic characteristics of the fan blades. As a result, the followability of the pitch change action with the change of wind speed is reduced, resulting in large fluctuations in the speed of the DE section, and even adverse situations such as overspeed and overload.

This method also has the following disadvantages: when the wind speed changes sharply, the pitch controller in the II and III transition zones participates in the control in advance, although the speed fluctuation and the impact are reduced to a certain extent, but the advance action of the pitch reduces the wind energy absorption loss. At the same time, the advance action of the pitch change in the transition zone II and III will cause the pitch motor to start and stop frequently, thereby increasing the load of the pitch system and affecting the safety of the pitch system

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