Abstract
About ten hydroelectric power plants realized from 1970 to 1990 in Romania are confronted with stator overheating. The developed mathematical model analyzes the voltage stability based on modal analysis of the Jacobian matrix, identifying the hazardous modes of variation between voltage and flow rate, correlated with the characteristics of the analyzed generators and their response to these variations. Vulnerable elements in the system for inductive and capacitive modes of operation are identified. In these conditions, hydro generators cannot attend the secondary voltage control, not even for a frequency power dependency control. The elaborated mathematical model was tested at the hydroelectric power plants Gilceag, Mariselu, and Susag with similar functioning conditions. The necessary conditions for stator ventilation and variation of flow hydrodynamic parameters during the operation were established. The theoretical model was tested with an experimental method applied separately for the thermal and ventilation conditions. Some results obtained during the measurements are illustrated and correlated with the theoretical results. The model was tested to prevent the onset instability of voltage drops and accelerated overheating. Finally, some solutions to minimize the stators overheating based on local conditions are recommended.
Highlights
The developed mathematical model analyzes the voltage stability based on modal analysis of the Jacobian matrix, identifying the hazardous modes of variation between voltage and flow rate, correlated with the characteristics of the analyzed generators and their response to these variations
About 20 of them had in their structure similar turbines and generators as functioning parameters, they should operate in different conditions of pressure and flow rate as mentioned [1,2]
Three hydroelectric power plants facing the same problem in operation, the stator overheating, were considered in the present study
Summary
About 20 of them had in their structure similar turbines and generators as functioning parameters, they should operate in different conditions of pressure and flow rate as mentioned [1,2]. After their commissioning, overheating of the generator stator appeared, especially for turbines with a vertical axis. To maintain the function of these hydropower plants, the accumulation lakes were partially emptied, modifying the pressure and flow rate, and the produced energy [3,4]
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
