Integrating multiple generators to a single system

I am having problems with speed control of 2 synchronous machines. Both consist of a synchronous generator and exciter but one uses a Hydro Turbine governor control block and the other uses a steam turbine governor control block. Individually both machines reach synchronous speed and respond correctly to changes in demand however when I create a system with one of each type of generator synchronous speed drops off completely and does not recover. I noticed the excitation voltage of each generator increases significantly but am unsure as to why this would result in a reduction in speed of the generators.

any help would be greatly appreciated.

Answer 1

[Babak]

In the configuration Parameters dialog box, check the sampling time for all the models. If the sampling time is on "Auto" then MATLAB decides on choosing it which (I think) creates the problem. So, run the two individual models with whatever sampling time you are choosing and try to come up with a fixed sampling time for all the three models. If sampling time in any of the three models (2 individual and 3rd one that has both machines) doesn't match with the other two, the results might be different.