Alternate solutions to replacing aged static exciter systems

Over the years, many rotating exciters have been replaced for static exciters on synchronous machines. As these replacement static exciters age, much of the analog hardware becomes obsolete and can no longer be supported by the manufacturer, again forcing the replacement of the entire excitation system. For many systems, the power rectifier bridge has proven to be reliable with replacement components for power SCRs and power diodes utilized in the bridge still being accessible. Today, rather than replacing the entire excitation system, another approach is to replace only the analog portion and keep the power rectifier bridge; hence, saving on the overall cost of a replacement rather than the investment of the entire excitation system. This paper will discuss the results of this alternative solution and will demonstrate the improved performance gained by implementing a digital front-end controller into the existing power rectifier bridge/s that can result in substantial cost saving to a project.