Wind power converter switching frequency control method, module, and power generation system
A technology of wind power converters and control methods, which is applied in the field of power electronics, and can solve problems such as low reliability, large changes to installed units, and complicated control parameter switching procedures.
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Embodiment 1
[0075] figure 2 A wind power generation system 200 according to an embodiment of the present invention is schematically shown. Please refer to figure 1 and figure 2 , the wind power generation system 200 includes a wind generator 201 and a converter, the stator winding of the wind generator is coupled to the power grid 205 through the stator main contactor 203 and the main circuit breaker 204, and the rotor winding of the wind generator is coupled to the converter . The converter includes a machine-side converter 211, a grid-side converter 212 and a control device 213. The machine-side converter 211 is connected to the DC side of the grid-side converter 212 to form a back-to-back connection. The fuse and the grid-side main contactor are coupled to the stator winding, and the electric energy generated by the stator winding and the rotor winding is transmitted to the grid. The operation mechanism of the wind power generation system does not involve the focus of the inventi...
Embodiment 2
[0094] Due to the fluctuation of the rotational speed near the synchronous rotational speed, it may cause the modulation voltage U of the AC side port of the machine side converter. x Frequent fluctuations above and below 0.5 will cause the above two modulation wave adjustment methods to switch repeatedly. During the switching process, pulse loss may be caused and the current will be distorted. In this embodiment, a common mode component is injected into the modulation voltage output by loop control (eg, torque control), so that most of the modulation voltages are raised to above or below 0.5 as a whole to avoid frequent switching.
[0095] In order to solve this problem, it is necessary to inject a common mode component into the above scheme, so that most of the modulation voltages are raised to above or below 0.5 as a whole. The modulation voltage section (sector) judgment is performed, and the amplitude of the modulation voltage in multiple consecutive switching cycles is a...
Embodiment 3
[0106] Please refer to Figure 7-9, after adopting the technical solution of the embodiment of the present invention, the switching frequency of the wind power converter is reduced to 1 / 3 of the original switching frequency.
[0107] When operating speed n and synchronous speed n 0 The difference between them is less than a predetermined threshold (eg 0.01), adjust the modulation voltage U x , to judge the modulation voltage section (sector), and adjust the amplitude of the modulation voltage in three consecutive switching cycles according to the judgment result, and finally reduce the switching frequency to 1 / 3 of the original switching frequency.
[0108] As shown in Table 3 below, when 0x ≤1 / 3, U x Located in section1, adjust the amplitude of the modulation voltage to 3U x or 0 to get the adjusted modulation voltage U * x ; when 1 / 3x ≤2 / 3, U x Located in section2, adjust the amplitude of the modulation voltage to 3U x -1, 0 or 1 to get the adjusted modulation voltage...
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