If you have two regions of different frequency and amplitude, the best solution is the use of HVDC lines between the two regions.

If not you can use the other FACTS (UPFC, statcom and others ...) but you have to adapt the amplitude and the phase of the line voltage with those of the regions.

What do you mean by different frequency between two generators? Can you  better clarify your question?

For regions where the electrical frequency is different i.e one region has 50 Hz standard while the other has  60 Hz (scenario of two countries), we make use of HVDC. The advantage of HVDC is the interconnecting converters that allow conversion from AC to DC; hence isolating the two regions of different standards. 

Is there one generator for each area? is there islanding operating mode? are there microgrids? what is your system? if one think to installe HVDC system for the sole purpose of adapting frequency, what about a cost of this proposal ?

Dear Boudebbouz, I think what his question is that you have multiple generators in a region and there has to be a mechanism through FACTS to connect to another region which might be working on different frequency. Just like connecting Eastern Japan with Western Japan which has different working electrical frequencies. For this HVDC is the best possible solution. Even if the system frequencies are same, HVDC is much more cost effective rather than having 3 phase transmission lines e.g. between inter-continental connection like between USA and Canada. The reason of being cost effectiveness is pretty straight forward; consider the cost of 2 wire transmission lines and 3 wire transmission lines. 

Dear Syed 

did you have reference paper related to connected two generators with a different frequencies  

Dear Hasan,

HVDC is actually not part of my research bu there are many case studies for this system that are deployed. You may actually need to go over them first before you try simulating the system. 

Dear  Syed A. Raza;

I believe that the cost estimate is very important for deciding on the feasibility of this type of project. The HVDC connection is not only 2 wire transmission lines but also very expensive converters. If we are dealing with networks of several thousand of MW and hundreds of kV, i would be in full agreement with you. But in the general case, a very careful tecnico-economic study is very recommended. As attachment,  you find a good report related to IFAA 2000 and the corresponding cost.

Best regards.

I agree with you. I was just giving a hint towards cost reduction. The converters will definitely have their cost. It will also depend upon the technology that is to be used. The cooling units for these converters will definitely have their cost also. Besides all these, the criteria which needs most attention is the distance that needs to be covered by the HVDC system. The longer the distance for the HVDC lines, it will definitely be more economical compared to nominal AC transmission lines. 

Hello,

I can add one important thing about HVDC lines, if HVDCs based on VSC are used, the results can be further improved by PWM techniques and the size of filters used for harmonic filtering can be reduced.

It is the normal practice to usevHVDC transmission or HVDC back to back between two areas of different frequency.  Even this will require FACT devices for reactive balance on both sides. 

I am not very clear about your second point. Phase angle difference is a must for power flow even though voltage magnitudes can be the same.

Obviously in case where there is both variations. is mag and angle. FACT devices can have a positive impact in controlling power flow between two areas.

CHER Hasan Abumeteir

You can use the facts to control power as follows:

1- different frequency between two generators. VSC HVDC OR HVDC

2- same mag. and phase angle between two generators. VSC HVDC OR UPFC

3- different mag. and phase angle between two generators. VSC HVDC OR UPFC

if you want study more about facts, i offer this book for study

FACTS CONTROLLERS IN POWER TRANSMISSION AND DISTRIBUTION

K. R. Padiyar

and I think UPFC is the the most complete of facts, but their price is very expensive.