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.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 ...Show More
Abstract: It is well known that governors of turbines, moving synchronous machines are responsible to maintain the rotation of the rotor of the generator constant and then the electric frequency constant, independently of the changes of electric loads connected to the power electric net. This paper treats about the origin and necessity of the permanent and transitory speedoops in the control mash of a governor. First, we develop the historical background origin of a governor. The basic controls actions are studied, and the analogic circuits related, using operational amplifiers. Then, as an easier way, the author uses an analogic generic PID governor to explain how the permanent speedroop is needed to set the power delivered by a hydraulic turbine (Francis) and then the transitory speedroop. Additional control signal as Power Joint Control and Automatic Generation Control-AGC are introduced. As a suggestion, a simple analogic Power Joint Control circuit example, using operational amplifier 741 is given, but not tested in a workbench. The using of the Automatic Control Generation-AGC, a supplementary control, is introduced because of the necessity to correct the frequency deviations. It is also given a simple circuit example of AGC, not tested in a workbench. This paper ends with an analogic retrofit of a governor of Francis turbine of decade of 1960 of 180 MW using analogic electronic. The author employs IC 741 operational amplifier. Prior simulations of the Laplace’s model of the governor were made using Matlab-Simulink. Because of the little acquisition time of the available oscilloscope, the author made a transformation in the original Laplace model that reduced the step response time by a factor of 20 but the methodology and know-how to make an analogic retrofit was conquered. The governor was built and tested in a workbench. The hydraulic circuit was simulated with 741 amp ops. The electronic simulation corresponded to the mathematics simulations showing the success of the analogic retrofit. The physical space needed by the equipment was reduced from the size of a refrigerator to a size of a shoe box. Although an analogic retrofit is considered obsolete today, the analogic retrofit has robustness, and it is cheaper.Abstract: It is well known that governors of turbines, moving synchronous machines are responsible to maintain the rotation of the rotor of the generator constant and then the electric frequency constant, independently of the changes of electric loads connected to the power electric net. This paper treats about the origin and necessity of the permanent and t...Show More
