A fuzzy logic based controller for the excitation of a synchronous generator

A Fuzzy Logic Based Controller for the Excitation of a Synchronous Generator Power system stability problems have been the subject of continuing research for years. New types of controllers have been designed and utilized in power systems for better solutions. Among those, fuzzy logic (FL) and artificial neural network based controllers have been getting an increasing interest from the power system researchers. In this study, a mathematical model for the synchronous generator has been derived using dq axis transformation methods, and used in simulation process of excitation system. hi order to include effects of the machine parameters in simulation, a dq axis transformation based model is preferred instead of reduced and linearized small signal models suggested by IEEE. The operating conditions of a utility connected synchronous generator can be separated into two categories. The first one includes large generators that affects the bus voltage, which is required to be controlled. The second one includes small size generators that do not have any effect on the bus voltage but the reactive power. To control the bus voltage of the generator in the first category, a laboratory prototype experimental model has been established such that a small generator is connected to a load bus, consisting of a three-phase resistor and a three-phase induction motor as the loads, instead of the utility in order not to have a fixed terminal voltage. The terminal voltage control for the first type operating mode is obtained by applying both PID and FL based controller for both load types. Only the simulation part has been done for the second operating mode where the synchronous generator has a fixed terminal voltage, which is equal to the utility bus voltage. The simulation is done using both PID and FL controller for this case, as well. The controllers in experimental parts of this study are digitally implemented using a personal computer and a 12 bit PCL 818 data acquisition card with a speed rate of 100 kS/s. The performances, advantages, and disadvantages of PID and FL controllers are compared for this study. Key Words: Synchronous Generator, Excitation Control, Power-Factor Control, Fuzzy Logic Control, PID Control VI