How to Connect 50-Hz Industrial Power to a 60-Hz Utility Grid

The UK and France both have national AC power grids, and these are connected via a subsea high-voltage DC link so as to export/import power in whichever direction is appropriate at any time. The reason for using DC for the link, and AC/DC conversion at each end is that the AC grids of each country are not necessarily synchronised with each other.

As 60Hz and 50Hz are not synchronisable, it could be that a DC link between the two would constitute a similar solution, perhaps?

I think the best solution and most efficient would be a rotary converter unless there is new technology that would make a static more effective.

I would suggest you seek out some professional help as tying in such a system will require more than what you can get from this blog.

GRAY HAIRED OLD GOAT

Dear friend,

Thanks for your reply.

I tried my best to find manufacture of large rotary frequency convertor (RFC) but no positive reply has been so far.

In my country , in one of the fertilizer complex (not mine) they are using rotary convertor ( 4MW, 50hz ,6.6kv motor driving direct coupled Generator 4.3MW ,60hz ,2.4kv ) make Brush Electric UK 15 years old design. But when i contacted Brush they refued to helped me out.

They ABT Larence Scott UK ( Manufactures of large Motors and gererators) but they also refued.

I found too many vendors who make RFC but in small capacity and for low voltage application at consumer utilization level.

Kindly let me know any vendor / manufacturer who can supply Motor GEN set of 6-8 MW capicity ,operating voltage upto 13.8KV or above.

Also please guide me how can i synchronised , motor generator set ( Large synchronous motor driving synchronous Generator ) with grid.

HOW to vary frequency of synchronous motor during sychchorinig process.

Any guide line pl.

was00266

We operate GE Frame 5 units site rated at 21 MW. Was controlled by GE Mark II Speedtronic but I retrofitted and I am now using a third party PLC to run the machines. Other largere Frame 7 machines are controlled by Speedtronic mark VI.

Our system is 60 HZ.

We run in droop on to a grid with a 1500 MW peak.

There is no way you can directly connect the 50 HZ and 60 HZ systems.

The only way to do it is to convert the excess 50HZ power to DC and invert back to 60HZ.

One concern I have though is that you operate one machine in Isoch and one in droop .

Wouldn't that take the isoch machine to base load at times or is your load relatively flat and not significantly variable.

My concern is that if you are at base load and the base loaded machine trips , you may have a plant upset before the backup units picks up the full load?

Wouldn't loadshare be more appropriate for your application ?

1) If there is a DC network in the area you can use a rectifier and connect directly to the DC station.

2)If choosing the cheapest solution, a one way rectifier - 50 Hz inverter would do the job. Thyristor inverter are some of the most used today; power transistor inverter would be more expensive.

A more expensive solution would be having two rectifier - inverter thyristor equipments for both ways circulation of power; I can not offer any frequency converter type, but suitable would be the two way converter as back-up power supply, in case the turbines are turned off.

3) Static

4)DC connection avoids most stability problems encountered in AC systems.

5)no other technical way so far,

WAS

You may have picked this up from the other posts. You can't.

very good assumption. And you're right. Reading the posts reminded me of what I already knew.

Hi Wareagle,

He can do it, without doubt, with solid state systems. I frequently work on marine systems doing this to 150kW and as has been saidthe french and english suppliers send powr each way by the same means. the question is whether it is worth while financially.

It may be better to buy a converter to tie in with one gen set to make up the small balance needed for his plant.

regards

Chas

Thanks for ur able guidance .

WE are trying to work out solution with Static Freq. Convertors. While connecting with grid we have to run our both Gas turbines on Droop Control mode. Now i see following issues and need your guidance:

1) With both (23 MW each) GTs on droop ( in parallel with 2500 MW utility grid) how goveror will respond in case on sudden power swing on grid of severe load / frequency veriation,

2)Can it is possible to run Gas turbine in fixed MW control mode with grid operation. I mean is it possible to fixed the MW set point in MARK-5 control (Applying load limiter) say 18MW for 23MW machine.

3)If yes, how machine would respond if excessive load demands or under frequncy condition will occur on grid. Would the machine try to share the additional load or remain in-different / on fixed MW state.I think Gt will also go in under frequency operation if incoming load veriations are too large or beyond machine capacity.

Pl. reply.

best ragards,

1) You don't have to worry about frequency variations because you are running asynchronous with the grid. The converter can act as a buffer and dampen the grid load variations. The governor will try to maintain the frequency for your loads, it can not do anything about grid variations. The convertes can be adjusted to cut off power transfer in case of grid load/ frequency variations. 2) I'm not in the turbine area, but in a synchronous grid (50 Hz or 60 Hz) I know there are some generators that have almost constant load, and some that are chosen to control the frequency. And those gen dedicated to control the frequency vary their load accordingly. Not all generators participate in frequency control. Again the frequency converter can help you with this. If you run the turbine in constant output, the excess power can be injected into the 2500 MW grid, case in which your load variations will be managed by the grid. 3)The convertes should have this job done and keep the constant output for the turbine. The time response for the covnerter control is far smaller than that for the turbine speed control. I have to say that the converter must be a "smart converter", in the way that it must have installed frequency control. Someone or something must control the frequency for the complex. If not the turbine than it is the converter.This is because you want to keep the turbine in constant output- a good thing. Hope I have answered your questions. Kind regards