2results about How to "Does not affect operating efficiency" patented technology

This invention discloses a control method for improving the transient stability of doubly-fed induction generator (DFIG) wind turbine systems connected to the grid, belonging to the fields of wind power grid connection technology and power system stability control technology. First, a reduced-order model of the system is established to accurately reflect the dynamic behavior during low-voltage ride-through. Based on this model, the attraction domain boundary and maximum power angle constraint are obtained, and then adaptive current reference control is proposed: the rotor d-axis current limit is calculated based on the maximum power angle constraint and the grid voltage, and compared with the original reference generated by maximum power point tracking. The smaller value is taken as the command to achieve adaptive limiting of the rotor current. Simultaneously, transient pitch collaborative control is proposed: the rotor speed is monitored in real time, and when the speed exceeds the safe upper limit, a transient load reduction power command is calculated and the pitch angle is rapidly increased to reduce mechanical torque. This invention can significantly enhance the fault ride-through capability and grid-connected operation reliability of DFIG wind turbines during transient processes such as voltage dips.

The invention provides a temperature control system and method for process liquid and semiconductor wet processing equipment. The temperature control system comprises a constant-temperature water unit, a first temperature control unit and a second temperature control unit, a flow path of the process liquid sequentially flows through the first temperature control unit and the second temperature control unit, and a water outlet of the constant-temperature water unit is connected with inlets of heat exchange channels of the two temperature control units in parallel so as to achieve two-stage temperature adjustment of the process liquid. According to the technical scheme, coarse adjustment and fine adjustment control over the temperature of the process liquid is achieved mainly through a two-stage temperature control framework with the process liquid connected in series and the constant-temperature water connected in parallel, and the accuracy and stability of the temperature of the process liquid in the wet process can be guaranteed. Moreover, the temperature control operation is continuously carried out, and generally, the temperature control operation does not occupy extra process takt time, so that the operation efficiency of wet processing is not influenced.