Ac excitation synchronous condenser and control method thereof

A control method for the AC excitation synchronous condenser, comprising:

• S1:
• obtaining a corresponding reactive power command Q* from the superior command or the local control according to a preset working mode;
• S2:
• obtaining a rotating speed command ω*r according to information about a frequency of the local power grid and a motor speed;
• S3:
• obtaining a rotor reactive current command I*rq according to deviation between a measured reactive power of the local power grid and the reactive power command;
• S4:
• obtaining a rotor active current command I*rd according to deviation between a measured rotating speed of the AC-excitation induction machine and the rotating speed command;
• S5:
• limiting and allocating the dynamic active current command and reactive current command according to the capacity of the full-controlled AC excitation converter, and obtaining an excitation voltage command for the full-controlled AC excitation converter, so that the full-controlled AC excitation converter performs independent excitation of the AC-excitation induction machine;
• and
• S6:
• calculating an active current command for the grid-side converter according to deviation between a measured DC bus voltage and the DC bus voltage command, and obtaining a control voltage command for the grid-side converter, so as to maintain the stability of the DC bus voltage, so that it is ensured that the full-controlled AC excitation converter has sufficient excitation control capability.