I need know what is the best excitation system? static or brushless? ... and y what is more expensive?

One case, for example:

*) Brushless Excitation, model: Siemens - RG3

**) Static Excitation, model: Basler - ECS 2100 or GE - EX2100

Synchronous Generator general specifications:

Electrical Power: 200 MW

Rated AC Voltage: 16.5 kV

Frecuency: 60 Hz

Rated Power Factor: 0.85

 

It's not as simple as best or worst, or most expensive or least expensive. Excitation systems are designed with many parameters in mind, such as the ability to "ride through" certain types of faults, or not, as the case may be; and to provide voltage support in certain instances. The choice of an excitation system must include many considerations.

As for which is more expensive, it seems from the limited information you provided that you are considering a retrofit of an existing excitation system on an existing machine. If so, what kind of excitation system does it currently have? Would you have to make many modifications to the existing system to install the new exciter, say, adding a rotating diode wheel and rotating exciter to the end of the shaft?

You have not provided enough information to be of much help. And, again--such a decision should always include the design parameters of the machine the excitation system is being chosen for--new or existing. And those parameters can be very different from machine to machine depending on contractual requirements, usage (always or usually connected to a large grid; sometimes powering a smaller "island" load; etc.) and many other operating factors.

The auxiliary equipment supplying the excitation system with its power must also be considered, as must the transformers, switchgear and bus downstream of the generator.

It's not as simple as "best" and "cheapest".

Is it ever?