Jawwad,

Difficult to say without knowing details of the cable parameters, the exact nature of the on-shore grid that you are working with, and the wind generator configuration and controls.

I would suggest an eigenvalue analysis of the complete network to see how the specific length of the off-shore connecting cable affects them.

With best wishes.

-Sanjay

Thank you for your response.

I used the standard ABB XLPE Sea cable, 300Sq.mm. secondly, full scale converter wind turbine model is used for analysis. For simplicity in analysis, i used single model of wind turbine 5MW but in parallel machine configuration.

I did the compete eigenvalue analysis. I found no influence on local area mode while the inter-area mode is positively influenced.

Hi Jawwad,

Thanks for the details, but I dare say that it is still like a needle in a haystack !!

I am sending you one interpretation, but frankly this is only a guess - you need to actually check in your simulation/eigen-analysis if what I am guessing is correct ort not. It goes something like this:

You have made the cable inadvertently so long, that the distributed capacitance of the XLPE is overcompensating the effect of distributed inductance. So when you lengthen the cable beyond a point, the wind generator is "tied better" to the on-shore network.

An easy way to check whether I am correct or only gabbing is to "replace" the ABB cable by something of lower per length capacitance (say, an OHT line !) in your simulation. If the inter-area mode worsens by making this "hypothetical" change, then my interpretation is correct - otherwise not !!

Please let me know how it goes !!

Cheers !

-Sanjay

Hi Prof. Roy,

I am really very thankful for your kind and prompt response.

I tried with different cables from the power factory library as well as the cable you mentioned. In all cases inter-area mode is positively influenced.

For further verification, i simulated the eigenvalue analysis with different cable lengths, starting from 1Km to 25Km but the trend remains same.

Please see in the attached picture.

Hi Jawwad,

Most probably it IS the cable capacitance.

Could you try replacing the connection with an overhead (OHT) line ? That would clinch it, like I said earlier.

-Sanjay