Impact of Drivetrain on Wind Farm VAR Control - Upwind

UPWIND
reactance (Xgrid). The ratio Kp/Ki is chosen to cancel the reactive power control loop time
constant Tq. This can be interpreted as follows:
K p
= Tq
(5.4)
K i
K
i
=
T
var
1
⋅ X
grid
(5.5)
The wind farm VAR controller parameters are shown in Table 4-6. The system response to a
step change <strong>of</strong> the reference voltage at the POI (Vrfg) is shown in Figure 4-10 with all WTGs
in service and in Figure 4-11 with half <strong>of</strong> the WTGs in service. Vreg is the regulated voltage at
the POI and Vt is the WTG terminal voltage. With all WTGs connected, the step voltage
magnitude was 0.015 pu where it was 0.01 pu with half <strong>of</strong> the WTGs in service so that the
WTG reactive power does not exceed the machine maximum limit. A reasonable time
response (settling time <strong>of</strong> the order <strong>of</strong> a few seconds) <strong>of</strong> the POI voltage with the desired time
constant was obtained.
Table 4-6 Wind VAR control loop parameters with static excitation system
SCR Tvar (sec) Ki Kp
20 3 6.66 3.33
5 3 1.66 0.833
3 3 1.0 0.5
Deliverable D5.9.1 45