Research On Rotor Cooling Mode Of Large Pumped Storage Generator

The units features of thermal and nuclear power generator has determined that it is more suitable to run at a steady capacity.Since electricity is not fit for storage,and as power consumption fluctuates everyday and with every season,there is a rise and fall in electric load and as a result a negative impact on power grid and power generator.Pumped-storage power station is by far the most economical and powerful of its kind.It can store power by pumping water from lower reservoir to high level reservoir when power grid load is low.On the other hand,when the load is high,it can generate electricity with the potential energy stored in the upper reservoirs,thus relieve power grid pressure.Pumped storage power station can improve the efficiency of thermal power station and nuclear power plant,stabilize the cycle and voltage of the power network,and can be used as a backup machine for frequency modulation and phase modulation.Recently developed pumped storage units are high-speed and large-capacity power generation motors.Their diameter is small,and because of its size,the rotor current density is relatively high,and per unit loss is huge.These undoubtedly increase the burden of the generator motor cooling system.Since the generator motor starts frequently and must meet the requirements of conversion of operating conditions,the cooling system design has been subject to certain restrictions.Thus one of the difficulties of the motor is to develop a ventilation cooling system with fan.This thesis combined the development of Dunhua,Chang Longshan,and Yangjiang generator motor,and designed a comprehensive test platform which integrated simulation design,power supply,measurement,control technology and fluid-solid analysis.The whole system included the tested magnetic pole,yoke,stator,cooler and other model devices,test systems,air supply systems and power supply systems.Based on one to one ratio with the real machine,the model was designed with 1/4 circumference of the real machine,which contains three poles.The test current was determined according to the size of rated field current,and the capacity of silicon-controlled rectifier and voltage regulator in Dunhua,Changlongshan,Yangjiang and other power generation motor.The power is supplied from the 380 V AC through the voltage regulator(0-650V)to the transformer(1:15)in silicon-controlled rectifier power supply system to reduce voltage power supply,and then the direct current is tested through silicon-controlled rectifier.Measurement and control system consists of hardware and software,which can achieve data collection,analysis and display,and under the control of the system,the frequency of the inverter could be adjusted remotely so that the fan can provided the required air volume in the specified speed range.On the test platform,the two kinds of field coils,single-side ventilation and double-sided ventilation,were used as the test subjects.The temperature rise test was carried out under various rotor current and air flow conditions,and the heat dissipation capability of the two kinds of field coils was obtained.From the test results,the effect of double-sided ventilation on the total air volume was small,the average temperature of the poles was 5K lower than that of single-sided ventilation,and the average temperature of the pole coil was better than that of single-side ventilation.From these three aspects,the double-sided ventilation of the rotor magnetic pole ventilation was more conducive to the cooling of the pumped storage rotor.On the basis of the experiment,the average temperature rise of rotor coil under the rated condition in Yangjiang generator motor is calculated.