Retrofit of a Governor Electronic-Analogic of a Francis Turbine of 180 MW of Decade of 1960 Using Microcontroller Arduino Due

Abstract

This paper describes the retrofit of a governor electronic-analogical of a Francis turbine of a synchronous generator of the decade of 1960. The author has many years of experience in maintenance in governors of hydroelectric power plants including excitation systems. Governors are responsible to maintain constant the frequency of a power electric net. The original model of the governor in question was obtained in local field tests, not related in this paper. In this retrofit, time constants were maintained to respect the original project and avoid hydraulic harmful and dangerous transitory problems. The original continuous model of the governor was simplified toa a second order model. The second order continuous model was emulated to a discrete system. The difference equation was created and microcontroller Arduino Due was programming. The digital controller produced, was syntonized to cancel the mathematical function of the servomotor, to reduce the grade of the resulted system obtaining a second order system. The hydraulic part of the governor was simulated using 741 operational amplifiers. During the tests in the workbench the author burned two Arduino’s electronic cards so it was necessary to create the electronic interface between Arduino and the 741 amp op including over and under voltage protection. The complete set was successfully tested in workbench. The mathematical models were priory simulated with Matlab-Simulink and there were the corresponding electronic simulations in workbench that confirmed the results. This retrofit solution, using Arduino Due, is of low cost compared to traditional manufacturers.