Grid-forming wind turbine control method for diode rectifier unit-based offshore wind power transmission system

A grid-forming wind turbine control method for a diode rectifier unit (DRU)-based offshore wind power transmission system, the DRU-based offshore wind power transmission system comprising an offshore wind farm;

• the offshore wind farm comprising a plurality of wind turbine units;
• the grid-forming wind turbine control method being used to control a grid side converter of each of the plurality of wind turbine units;
• and the grid-forming wind turbine control method comprising:
• (1) converting, by an active power controller, a difference between Pwt* and Pwt into a voltage amplitude reference value Uwt*;
• and converting, by a reactive power controller, a difference between Qwt and Qwt* into a frequency f of each of the plurality of wind turbine units;
• wherein Pwt* is an active power reference value of each of the plurality of wind turbine units;
• Qwt* is a reactive power reference value of each of the plurality of wind turbine units;
• Pwt is an actual active power output of each of the plurality of wind turbine units;
• and Qwt is an actual reactive power output of each of the plurality of wind turbine units;
• (2) taking Uwt* as a d-axis voltage reference value ufd*;
• letting a q-axis voltage reference value ufq* be equal to 0;
• converting ufd* into a d-axis modulating voltage reference value uvd* through modulation by using a voltage controller and a current controller in sequence;
• and converting ufq* into a q-axis modulating voltage reference value uvq* through modulation by using the voltage controller and the current controller in sequence;
• and
• (3) subjecting the frequency f of each of the plurality of wind turbine units to integral transformation to obtain a reference phase θ of each of the plurality of wind turbine units;
• subjecting the uvd* and uvq* to coordinate transformation to obtain three-phase modulating voltage reference values uva, uvb and uvc in an abc coordinate system by using the reference phase θ;
• and subjecting the uva, uvb and uvc to pulse width modulation (PWM) to control power switching devices in the grid-side converter of each of the plurality of wind turbine units.