The Power Generator Operation Condition Monitoring And Stator Winding Fault Diagnosis

In the thermal power plant, the safe and stable operation of the generator not only plays an important role in the power generation enterprises, but also affects power supply enterprise and electricity customers. So it is an important task to ensure the safe and stable operation of the generator, which is the main research subject in this paper. So it is necessary to research a system which can diagnose various faults of generator and monitor the running state of generator, and diagnose more than 160 kinds of possible faults of generator, and it is necessary to use the system as an expert for generator.Based on this purpose, we lucubrate stator winding temperature monitoring and fault judging subsystem of expert diagnosis system for generator. In the subsystem, it is pivotal to establish the model of stator winding temperature and make sure the criterion. For this purpose we established a unified mathematical model of the stator winding temperature, and used a large number of field test data and production data to identify this mathematical model in the basis of the unified model. After that we get the unified mathematical model of the generator stator winding which is matched with various situations in the actual producing. But, different parts of generator stator winding temperature are connected with active power, reactive power, stator current, inlet water temperature of stator, cooling air temperature, etc. in the actual producing. The corresponding temperature at the same conditions will be different because of numerous influence factors. So we could not use an operating condition corresponding to a temperature as a criterion for determining temperature fault, and we should use a more accurate criterion. It is more accurate to adopt the dynamic threshold as the criterion of temperature because of the condition above. The dynamic threshold is a corresponding threshold that using mathematical model to calculate the temperature value at each operating condition and giving some margin because of calculation error and measurement equipment error. It is proved by lots of experiments that this decision procedure can improve accuracy, sensitivity, reliability of the monitoring and prevent erroneous judgments well.In addition to the monitoring of generator stator winding, the monitoring of each generator operating parameter is also very important for the safe and stable operation of generator. So a new mathematical model is established base on the traditional ideal generator model. The ideal mathematical model is established on the premise of unsaturation, non-damping, rotor non-alveolar, sinusoidal distribution of air-gap electromagnetic field of generator while the nonlinear influence of some factors such as saturation, damping, rotor alveolar is subsistent during the actual operation of generator. If we consider these factors into the mathematical model, we can find that the central reaction reactance, transient reactance, secondary transient reactance of generator is not a constant, but a actual operation parameter. According to this situation, we established a mathematical model which is suitable for stable and disturbed operation of generator parameters in actual operation. After that we get the curve of voltage, electric current and power angle between the model and actual operation by means of the disturbance experiments, and we find that both curve fitting well, which verifying the high accuracy of the model. The model can be fully used in actual production. While the generator is in the case of the external disturbance, it can be used to monitor various important parameters of generator and ensure the generator operating in a steady-state condition after adjusting, reaching a new equilibrium and realizing safe operation. Not only that, the model can be used to detect the influence of internal fault of generator to the operation parameters, and detect the various parameters of generator with high reliability and sensitivity.