Variable speed constant frequency control method after grid connection of wind driven generator set

Abstract

The invention relates to a variable speed constant frequency control method after grid connection of a wind driven generator set, which comprises the following steps: when the wind speed changes, a wind wheel torque is changed, and the mechanical torque of a speed regulation motor shaft is also correspondingly changed; the torque current of a speed regulation motor is changed so as to change the electromagnetic torque of the speed regulation motor and make the electromagnetic torque balanced with the mechanical torque of the speed regulation motor; when the torque current of the speed regulation motor is changed to a certain extent, the corresponding electromagnetic torque is computed, and an optimum rotating speed corresponding to the electromagnetic torque is determined; the optimum rotating speed value is used as a new set value to regulate the speed of the speed regulation motor; and when a wind wheel achieves a rated rotating speed, the speed regulation motor stops working. According to the invention, only the speed regulation reference of variable speed constant frequency control is changed from the rotation speed of a power generator into the torque of the speed regulation motor, the variable speed constant frequency operation requirement of the power grid friendly type wind driven generator set is met, the reliable operation of the wind driven generator set is realized, and grid-connected operation stability is improved, so the method is suitable for being used and popularized.

Description

technical field [0001] The invention relates to a control method of a wind power generating set, in particular to a control method of variable speed and constant frequency after the wind power generating set with a variable speed ratio gear box speed regulating front end is connected to the grid. Background technique [0002] As the scale of grid-connected wind farms and the proportion of wind turbine capacity in the power grid continue to increase, in order to achieve reliable grid connection of large-scale wind farms and maintain the stability of the power system, the grid-connected requirements for wind turbines will become more and more demanding. Harsh. These requirements include low voltage ride through, voltage waveform distortion, and the supporting capacity of the reactive power of the unit, etc. At present, the main grid-connected models in the domestic wind power market are double-fed and direct-drive wind turbines. Although these two wind turbines have adopted s...

AI Technical Summary

Problems solved by technology

[0005] In wind turbines without speed regulation front end, such as double-fed wind turbines, before reaching the rated power, when the wind speed changes, the speed of the wind rotor also changes, so the speed of the generator also changes accordingly. At this time, by real-time detection of the speed of the generator , and adjust the generator torque according to the measured speed, so that the generator can run on the optimal power curve; and for friendly wind turbines such as wind turbines with a variable speed ratio gearbox speed control front end, the wind rotor speed, There is a one-to-one correspondence between the speed of the speed-regulating motor and the speed of the synchronous generator. After the wind turbine is connected to the grid, the synchronous generator always runs at the synchronous speed. When the wind speed changes, the speed of the wind rotor does not change before the speed-regulating motor operates Any change, which makes the speed regulation motor has no basis for speed regulation, that is, the speed cannot be used as the trigger condition for the variable speed and constant frequency adjustment of the entire wind turbine