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Hi there, I am having an issue using PLBVFU1 when network frequency dependence is enabled.

What I am finding is that when I use PLBVFU to cause a frequency disturbance and have frequency dependence switched on, the voltage on the infinite bus varies proportionally to the frequency. For example, if I start Vinf = 1.03 and ramp the frequency from 50 Hz to 47 Hz (6% decrease), the voltage also reduces by 6%, to 0.968. When the frequency returns to nominal, the voltage returns to the original value.

I have verified this on the following two cases and the performance is the same:

1. jconto's working directory (I can't link to it here but it's under the question "Example using PLBVFU1 playback generator") - if I enable frequency dependence then the voltage in the out file is about 0.3% lower the voltage in the plb file while the frequency is low.
2. I setup a case which has only one machine connected to a bus and no other network elements. The same behaviour is shown.

I have attempted to compensate for this by increasing the voltage in the PLB file by the same amount that it decreases in the simulation. However the voltage is still distorted when the frequency is ramping.

Has anyone else come across this bug? Is there a way around it, other than what I have shown above?