What are the two core technologies of wind power generation technology?

One is battery energy storage to ensure electricity usage when there is no wind; The second is to combine wind power generation with other power generation methods (such as diesel engine power generation) to supply electricity to units, villages, or islands; Thirdly, wind power generation is integrated into the conventional power grid for operation, supplying power to the large power grid. A wind farm often installs dozens or even hundreds of wind turbines, which is the main development direction of wind power generation.

The two main components of a wind power generation system are the wind turbine and the generator. The variable pitch control technology and variable speed constant frequency power generation technology of wind turbines are the development trends of wind power generation technology and the core technologies of wind power generation today. Here is a brief introduction to these two aspects.

1. Adjust the pitch distance of the wind turbine

The fan captures wind energy through the impeller and converts it into mechanical torque acting on the hub. Variable pitch adjustment is achieved by changing the angle between the windward side of the blade and the longitudinal axis of rotation, thereby affecting the stress and resistance of the blade, limiting the increase in output power of the fan during strong winds, and maintaining a constant output power. The power output curve of the fan is smoothed through variable pitch adjustment. When the rated wind speed is below, the controller places the angle of attack of the blades near zero degrees without making any changes, which is almost equivalent to constant pitch adjustment. When the rated wind speed is higher than, the variable pitch control structure takes effect, adjusts the blade angle of attack, and controls the output power near the rated value. The starting speed of the variable pitch fan is lower than that of the fixed pitch fan, and the impact stress transmitted during shutdown is relatively relieved. During normal operation, power control is mainly used. In practical applications, power is directly proportional to the cube of wind speed. Smaller changes in wind speed can lead to larger changes in wind energy.

Due to the fact that the impact of the variable pitch distance adjustment wind turbine is much smaller than other wind turbines, it can reduce material utilization and overall weight. Moreover, when the wind speed is low, variable pitch wind turbines can maintain a good angle of attack for the blades, providing better energy output than stall regulated wind turbines and making them more suitable for installation in areas with lower average wind speeds.

Another advantage of variable pitch adjustment is that when the wind speed reaches a certain value, the stall fan must be stopped, and the variable pitch fan can gradually change to the blade no-load full wing expansion mode position to avoid shutdown and increase wind turbine power generation.

The disadvantage of variable pitch adjustment is its sensitivity to gust response. Due to the relatively small power pulsation caused by wind vibration, the variable pitch control fan is relatively large, especially for constant speed wind turbines using variable pitch method, this situation is more obvious. Therefore, it is not required that the response speed of the wind turbine variable pitch system to gusts be fast enough to reduce this phenomenon.

2. Variable speed constant frequency wind turbine generator

AC excited doubly fed generators are commonly used in variable-speed constant frequency wind turbines, which have a structure similar to a winding induction motor, but with slip rings and brushes on the rotor winding. In this way, the rotational speed of the rotor is related to the frequency of excitation. Therefore, the internal electromagnetic relationship of a doubly fed generator is different from that of an asynchronous generator and a synchronous generator, but it has some characteristics of both asynchronous and synchronous generators. AC excitation doubly fed variable speed constant frequency wind turbines can not only achieve variable speed constant frequency by controlling the amplitude, phase, and frequency of AC excitation, but also realize active and reactive power control, and play a role in reactive power compensation for the power grid.