| The temperature of the generator pit changes with the hydroelectric load. Especially during the flood period, the hydroelectric generator is always in overload state so that the heat losses of the generator’s stator and rotor will be larger than that of rated load state which leads to the temperature rises. Therefore, the cooling water flow of the air-cooler should regulate automatically with the generator load in order to keep the temperature of all parts within the allowance under all kinds of load.The temperature control system of the hydraulic generator air-cooler includes temperature collecting and cooling flow regulation. At present, the temperature measuring element of the hydraulic generator air-cooler still applies traditional thermal resistance which disadvantages are that the analog signal is easy to be disturbed during transmission which leads to measure error and affect the control effect of the air-cooler exit air temperature. On the other hand, the manual mode is still in used in cooling flow regulation. Because of the lag of the temperature regulation, and the air-coolers mutual influence between each other, it leads to difficult to manually regulate for operators, and need long time to operate, affect the unit stable operation. Therefore, reformation and design of generator’s air-cooler temperature control system is performed in this thesis.DS18B20 is employed by this temperature control system to measure the air-cooler outlet air temperature, and analog signal is instead by digital signal in order to enhance the anti-interference ability during signal transmission. Transmission cancel of analog signal to digital signal can not only obtain more accurate temperature measuring but also can promote the hydroelectric power plant’s digital development. Electric regulation valve is employed by the actuator which to realize the temperature automatic control. Controller with self-tuning control strategy is optimized to realize temperature self-tuning and obtain more excellent control performance of the system.Laboratory test results show that: controller based on self-tuning control strategy can automatically adjust the opening of electric regulation valve with the obvious changes of the temperature and ensure the air-cooler outlet temperature within the permission scope, which achieves the anticipated effect. The design can be applied in the hydroelectric power plant that it has positive significance for the digital construction of hydroelectric power plant and the water and energy conservation. |
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