Design of electric braking system for Liujiaxia hy

Design of the electrical braking system of Liujiaxia hydro generator

after the experiment of Liujiaxia hydro generator tension experimental machine, the electrical braking system of the experimental curve machine can be redeployed and a new way to enter the market with customers as the center is designed

with the further development of industrial technology, PLC is more and more widely used in industrial control in all walks of life. From the initial digital quantity control, analog quantity control to special function control and Ethernet control. It controls the technological process through the application program stored by the user. It has the characteristics of high reliability, high stability, strong real-time processing ability, strong environmental adaptability, convenient use, simple maintenance and so on. In view of the superiority of PLC in the control system, the electric brake of Liujiaxia Hydropower Plant adopts the programmable controller fx2n-128mr of Mitsubishi Corporation of Japan for the main control design

I. technological process

generally, the braking system of hydro generator adopts air brake or oil brake, and the low-pressure air supply system specially used for braking must be set for the use of air brake, which is uneconomical in economy and increases the maintenance workload, while the use of oil brake requires the setting of brake oil pump, which is inconvenient for oil drainage and difficult to operate. Some small hydropower stations use wooden stick skid brakes, which can solve the problem, but it is labor-intensive and unsafe. Nowadays, electric braking or the combination of electric braking and mechanical braking are mostly used

electric braking adopts three-phase symmetrical short circuit of stator winding, and the rotor excitation makes the stator winding have the braking current equal to the current value under the maximum capacity operation condition, generating electric braking torque to realize electric braking. As one of the main equipment in the electrical braking system, the generator braking switch device is used for three-phase symmetrical short circuit of the generator stator winding. It should have the technical performance of large capacity, high-speed closing, three-phase linkage operation and so on

the normal shutdown braking of the generator of Liujiaxia hydropower plant can adopt electric braking. Once the electric braking fails, it will automatically turn to air braking to ensure the safe braking of the hydro generator. Put the electric braking device into operation when the generator speed drops to 80% of the rated speed

II. Electrical control

each generator brake switchgear is equipped with a control cabinet, which includes all required mechanical and electrical control components to realize remote and local operation of the brake switchgear, receive and execute the opening and closing instructions sent by the monitoring system, and realize electrical interlocking with the unit circuit breaker at the high voltage side, excitation and speed regulation system

in this system, the powerful time relay function inside PLC is flexibly applied, and the control is accurate. For PLC itself, the mean time between failures is very long; Moreover, the logic of programming is clear and the program is short, which determines that the scanning cycle of PLC is very short, the working speed is very fast, and there will be no missed action and misoperation, which is successfully applied to the control of electric braking

III. conclusion

recently, the generators of many hydropower stations in China have adopted electrical braking, but the effect is not ideal. The electrical braking of Liujiaxia hydropower plant is designed, programmed and debugged by our company. Since it was put into use at the beginning of 2003, it has operated normally. At present, three sets of units have adopted our company's braking system, and each set operates normally, which has won the trust and praise of customers. This shows that as long as you are familiar with the process control process and program appropriately and accurately, the application of PLC in electric braking is feasible

Design of electrical braking system of Liujiaxia hydro generator

with the further development of industrial technology, PLC is more and more widely used in industrial control in all walks of life. From the initial digital quantity control, analog quantity control to special function control and Ethernet control. It controls the technological process through the application program stored by the user. It has the characteristics of high reliability, high stability, strong real-time processing ability, strong environmental adaptability, convenient use, simple maintenance and so on. In view of the superiority of PLC in the control system, the electric brake of Liujiaxia Hydropower Plant adopts the programmable controller fx2n-128mr of Mitsubishi Corporation of Japan for the main control design

I. technological process

generally, the braking system of hydro generator adopts air brake or oil brake, and the low-pressure air supply specially used for braking must be set for the use of air brake. This can improve the quality system made of Chinese plastics, which is uneconomical in economy and increases the maintenance workload, while the use of oil brake requires the setting of brake oil pump, which is inconvenient for oil drainage and difficult to operate. Some small hydropower stations use wooden stick skid brakes, which can solve the problem, but it is labor-intensive and unsafe. Nowadays, electric braking or the combination of electric braking and mechanical braking are mostly used

electric braking adopts three-phase symmetrical short circuit of stator winding, and the rotor excitation makes the stator winding have the braking current equal to the current value under the maximum capacity operation condition, generating electric braking torque to realize electric braking. As one of the main equipment in the electrical braking system, the generator braking switch device is used for three-phase symmetrical short circuit of the generator stator winding. It should have the technical performance of large capacity, high-speed closing, three-phase linkage operation and so on

the normal shutdown braking of the generator of Liujiaxia hydropower plant can adopt electric braking. Once the electric braking fails, it will automatically turn to air braking to ensure the safe braking of the hydro generator. Put the electric braking device into operation when the generator speed drops to 80% of the rated speed

II. Electrical control

each generator brake switchgear is equipped with a control cabinet, which includes all required mechanical and electrical control components to realize remote and local operation of the brake switchgear, receive and execute the opening and closing instructions sent by the monitoring system, and realize electrical interlocking with the unit circuit breaker at the high voltage side, excitation and speed regulation system

in the cause system of the pressure of the rubber universal testing machine, the powerful time relay function in PLC is flexibly applied, and the control is accurate. For PLC itself, the mean time between failures is very long; Moreover, the logic of programming is clear and the program is short, which determines that the scanning cycle of PLC is very short, the working speed is very fast, and there will be no missed action and misoperation, which is successfully applied to the control of electric braking

III. conclusion

recently, the generators of many hydropower stations in China have adopted electrical braking, but the effect is not ideal. The electrical braking of Liujiaxia hydropower plant is designed, programmed and debugged by our company. Since it was put into use at the beginning of 2003, it has operated normally. At present, three sets of units have adopted our company's braking system, and each set operates normally, which has won the trust and praise of customers. This shows that as long as you are familiar with the process control process and program appropriately and accurately, the application of PLC in electric braking is feasible