WEG ECW500, Руководство пользователя

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Functional Description .
48 | ECW500
NOTE!
The LEOC limiter has higher priority over all other limiters.
6.6.3 Excitation Undercurrent Limiter (LEUC)
The LEUC limiter ensures that the synchronous machine does not operate at a point outside its capability curve
(PxQ). Thus, the amount of reactive power absorbed by the machine is limited to the specified value.
The ECW500 allows the customized adjustment of the PxQ curve through the setting of five active power points
versus reactive power as shown in Figure 6.18. The points must follow the sequence shown in the figure,
otherwise an alert will be generated when the regulator is put into operation.
Once enabled, the LEUC limiter will operate at the excitation current, keeping the machine in the PxQ curve
points. The LEUC limiter uses a PI loop independent from the main loop, with specific Kp and Ki gains.
Figure 6.18 Points for configuration of the PxQ curve
The active and reactive power points must be set within the limits given by the parameters 30176 (Pmin), 30172
(Qmin), 30174 (Pmax) and 30170 (Qmax). The active power values are positive and the reactive power values
are negative. In addition, the following criteria must be met:
•
P1 > Pmin;
•
P5 < Pmax;
•
Q1 > Qmin;
•
Q5 < Qmax.
To facilitate setting of the LEUC limiter points the increment / decrement value can be changed through the
multiplier given by parameter 30146. With it you can adjust increments of 0.1kW, 1kW, 10kW, 100kW or 1MW.
A numerical example of the LEUC parameter configuration is shown below.