# how we can consider an "error" to control the reactive power in DFIG

Discussion in 'The Projects Forum' started by sara.ahmadi.27a@gmail.com, Mar 12, 2013.

Feb 21, 2013
10
0
hello every body
in a wound rotor induction machine >>electromagnetic torque(Te) with neglecting of rotor and stator resistor losses is equal to:
(1)Te=Ps/w1=Pr/wslip[1]
{w1:angular speed of stator winding,wslip:angular speed of rotor winding,Ps=instantaneous power received from stator terminals ,Pr=instantaneous power delivered to rotor terminals}
and

(2)
j.[d(wr)/dt]=Tmech+Te[1]
{Tmech:mechanical torque,wr:rotor speed ,in generating, Te<0 ,Tmech>0,in generating, Te>0 ,Tmech<0}

in field oriented control
(3)Te=-3/2*p*Lm/Ls*flux_s_d*irq [2]

{flux_s_d:stator flux (direct axis component),Lm:mutual inductance,Ls:stator inductance,p : pair pole,irq:current of rotor (quadrature axis component)}

from (2) we can consider the "error of rotor speed from a reference speed"as electromagnetic torque,and then from(3) we can consider it as irq
hence we can control the rotor speed with irq

in that article[2]
idr(direct component of rotor current) is considered to control the stator reactive power
i don't know how we can consider an "error" to control the reactive power (similar to control the rotor speed with equation (2))?
note that from another article[3] we have:
(4)Qs=w1(flux_s_d/Ls)*(flux_s_d-Lm*ird)
for the rotor side converter,articles [2],[3] are based on the synchronous reference frame fixed to the stator flux.