High voltage regulators

[Morquea]

Hi

Question : Does a volatage regulator for 69kV line can could be used for a 120kV and vice versa? Does a auto-regulator on a line supplying 10MW would be affected and/or need to be change if we rise to 20MW.

Link about high-voltage regulators would be appreciated.

Project : Mining site developpement

Context : The utility had provides options for to supply power for a mining site in developpment. The total expected load is 20MW. They showed an option for 69kV wich was rejected and a option for 120kV wich was prefered.
However, environmental impact studies still need to be conduct before autorizing the use of 120kV. In the mean time, the utility offer to supply with 69kV on a line built for 120kV and they told use that they will use auto-regulator to cope with voltage drop. We should during that period build the temporary construction complex needed the develop the mining site. The power needed for this phase is 10 MW.
Once the normal mining operations begin, the utility should be able to provide the 120kV for a 20MW loads.
Finally, I'v been asked if the distributor would have to change is regulator to supply at 120kV and if we could stay at 69kV instead once the full 20MW is in operation.
I'm lacking knowledge to give a proper answer. So I told my coworker to simply ask the utility guys about it.

However, I would like to know more about high voltag-regulators and I don't have success with google

Thanks



Danny Garant, ing.jr
Groupe Stavibel Inc.

http://www.stavibel.qc.ca

 

[jghrist]

Either you or the utility will need to install a dual voltage transformer or change out the 69 kV transformer with a 120 kV transformer in the future.

It sounds to me like the utility needs the regulator only at 69 kV because of higher voltage drop on the line when operating at 69 kV. When they change to 120 kV, they will have less voltage drop and probably won't need a regulator.

 

[QBplanner]

Could you provide more information about the load supply.
Ex. the distance from POI to your mining site. the POI fault level.

We have a system supplying 28MVA load at the end of 130KM 69kV redial line.

69kV system should handle 20MW load if the line length is within 80km unless you have some large motors.

 

[Morquea]

The distance between the distribution sustations and the mining site is 75 km.
The fault level at the end of the line would be 250MVA @ 120kV and 115MVA @ 69kV. They allowed a 3% maximum voltages sags from motor starting. So, 500MW is about the largest motor power allowed @ 69kV.
But, actually, the project contain a 4200HP motor. It won't respect the voltage sags limit.

Danny Garant, ing.jr
Groupe Stavibel Inc.

http://www.stavibel.qc.ca

 

[QBplanner]

3% voltage sag approximate 3%*115=3.45MVA Assuming 7 Times inrush, 0.49MVA motor should be the case.
However, you may want to consider VFD drives to minimize the motor inrush. As long as you meet motor inrush requirements, I don't think that is an issue anymore.
I have no ideas the cost difference between 75KM 120kV line and 69kV line. But in the ultility I work here, it would be double.-Line,Transformer,Line terminal including CBs or disconnects.
With Var compensation at the end of the line to keep certain power factor, 20MW is not a problem for 69kV line. Dont' know why the utilities asked 120kV voltage level.
I guess their distribution sub is 120/25/12kV?? instead of 69/25/12kV?? If SO, you may require a good study to find out which interconnection provide you the most Eco. and Tec. feasible solution.
Regards,