Investigation of the Effect of Operating Conditions Change on Water Hammer in Hydroelectric Power Plants
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TECHNICAL ARTICLE—PEER-REVIEWED
Investigation of the Effect of Operating Conditions Change on Water Hammer in Hydroelectric Power Plants Go¨khan Kahraman
Submitted: 14 August 2020 ASM International 2020
Abstract Renewable energy sources do not harm the environment, and they contribute greatly to national economies. Hydraulic energy is the leading renewable energy source. Hydraulic energy is used more widely than other renewable energy sources around the world. This situation of hydraulic energy makes it important to solve the faults in hydraulic turbine-generator units. In this study, water hammer impacts have been investigated. This issue is important and can be dangerous in hydroelectric power plants. As a result of the research, the optimum sudden shutdown time of the adjusting wings in the snail is determined by considering the different operating conditions of a hydroelectric power plant. When the turbinegenerator units are operated according to the specified instantaneous shutdown time, they will be protected against the impact of the water hammer pressure and the turbine shaft overspeed. Thus, they will be operated with less risk. Keywords Renewable energy Hydropower Water hammer
Introduction While hydroelectric power plants are operating, they may encounter many faults such as bearing failures, unbalance, stator winding short circuits, excessive cavitation. Such faults are detected with the help of sensors placed in the turbine-generator units. In order to prevent further damage to the unit, the relays connected to these sensors stop the G. Kahraman (&) Faculty of Engineering, Mechanical Engineering Department, Munzur University, 62000 Tunceli, Turkey e-mail: [email protected]
unit by closing the adjustment blades immediately with the signals they send to the speed regulator. In this case, the pressure of the water hammer impacts appears directly in front of the adjustment blades which are closed in the snail. This pressure is very dangerous for hydroelectric power plants because it can cause enormous damage to the pressurized waterway system. There are many studies in the literature about water hammer impact [1–4]. However, it is the first time to minimize the water hammer impact pressure by optimizing the shutdown time of the adjustment blades. Roberts et al. have established a piston crank mechanism to obtain energy from the pressure of the water hammer impact on the pipes [5]. Naik et al. have developed a PID regulator controller with the internal model control (IMC) adjustment method to determine the effect of the water hammer impact in hydroelectric power plants [6]. Kamanbadast et al. have analyzed the pressure of the water hammer impact in a penstock pipe of a hydroelectric power plant by numerical method [7]. Vournas et al. have placed a surge tank on the top and bottom of the turbine in a hydroelectric power plant and simulated the positive and negative water hammer impacts during sudden opening and closing of the turbine adjustment blades [8]. Tijsseling has formed a one-dim
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