Method for improving stability of hydroelectric generating set

Hydropower Energy Science to Improve the Stability of Hydrogenerator Sets Li Huang Liu Weiya Tianjin Electric Drive Design Institute, Tianjin 300180, the impact of water pressure fluctuations. Experiments show that this is an effective way to improve the stability of the shaft extension and flow unit.

1 Basic situation Compared with the vertical axial flow unit, the shaft-through tubular hydro-generator unit has the advantages of simple structure, civil engineering workload, large turbine flow and high hydraulic efficiency. Its generator is placed outside the flow channel and solved. Due to the small diameter of the runner, it is difficult to arrange the bulb tubular turbine generator. The unit is a fulcrum structure. That is, the turbine has 1 fulcrum and the generator has two fulcrums. The joint structure, the thrust bearing is located close to the generator, and is combined with the front fulcrum of the generator. The radial thrust bearing radial thrust bearing hairpin machine and the 5-way bearing share a basic base, which passes through the base of the tail water flow passage. And the anchor bolts transmit the static and dynamic loads to the side piers, and the equipment at the bottom of the plant is dense, including the main governor collecting tank draining chestnuts and machine side disks, etc., making full use of the plant area. This model is conducive to the development and utilization of low-head large-flow water energy resources. Shaxikou Hydropower Plant is located in Xixi, a tributary of Minjiang River in Fujian Province, on the outskirts of Nanping City. It is a small machine of No. 5 machine. It is a fixed-shaft axial-flow turbine generator set. The turbine runner has a diameter of 1.81. Design head 171. The flow rate is 24.38, the rated speed is 3751, and the generator output is 3.5 rivers. It is the largest high-capacity shaft-through tubular hydro-generator unit in China. The unit is equipped with Tianjin Electric Transmission Design and Research Institute, and the 1.15500 feed programmable controller turbine Governor.

Before the water heater unit was filled with water, the detailed test of the governor was carried out according to the test procedure of the turbine governor and the hydraulic device. The result is the governor speed dead zone 0.03; the hydraulic manual state servo swing value 25 The relative value is 012, which is excellent in performance. However, after the unit is filled with water, whether it is manual no-load condition or grid-connected load condition, the phenomenon that the servomotor swings greatly occurs, the servomotor swing value is greater than 2 5, and the manual air-loaded condition unit frequency swing value is greater than 2 Pressure, automatic no-load condition The unit frequency swing value drops to about 1.2 pressure, and the load rejection process is normal. The technical conditions of the turbine governor and the weir device are specified in the working conditions of the small and medium-sized turbine governor. 2 In the manual no-load condition, the turbine generator set speed swing value does not exceed 0.3, and the water flow inertia time constant and the machine 1 ratio of inertia time constant + person 0.4. inertia time constant of anti-occupation unit is not small corpse 4 Shaxikou hydropower plant's shaft-through tubular hydro-generator set does not meet the requirements of this working condition, its water flow inertia time The ratio of the constant is 0.55, while the pilot is used to the constant, the inter-constant is only 2.538. Turbine governor. The technical condition of the oil pressure device also stipulates that the manual no-load transfer violation value is greater than the specified value, and the relative value of the automatic no-load speed swing shall not be greater than the relative value of the manual no-load speed swing. The test results show that the relative value of the automatic no-load speed swing of Unit 5 of Shaxikou Hydropower Plant is only 60 of the relative value of manual no-load speed swing, which meets the requirements of national standards. However, due to the large swing of the no-load speed and the difficulty of grid connection, it will bring + to the transport hall.

2 Water pressure pulsation affects the operation stability of the unit. Due to the advantages of simple structure, civil engineering, small-scale turbine over-flow fire and hydraulic efficiency, the shaft-through tubular hydro-generator unit has been widely used in low-head hydropower plants in recent years. . However, the size of the generator is limited by the distance between the centerline of the unit and the draft tube because the tail water flow of the unit is relatively small, and the size of the generator is limited by the size of the bulb body. The unit flywheel torque is small, that is, the unit time constant is small, and the 7 undercurrent inertia time constant is large relative to the unit inertia time, which easily leads to poor frequency stability of the tubular turbine generator set. The 5 units of Shaxi Hydropower Plant were rebuilt and installed on the old building. Due to the limited construction conditions, the diversion channel is tortuous, and there are 90 horizontal turns after lateral water inflow, and then the conventional diversion pipe and shaft through-flow type. The hydro-generator machine, in the vicinity of the Shui Shui Pass, describes the lower part of the tail stern that has been removed, such as blocking the low wall, forcing the tail water flow to change, and the flow channel is especially special. This special water diversion system and the above-mentioned shaft extension The characteristics of the flow turbine generator set and some other factors lead to poor running stability of the unit. After the unit was put into operation, the radial vibration of the main shaft oscillating water machine chamber and the water pressure pulsation of the 41 water system were tested. The result shows that the water pressure pulsation double price is 0.018,1 before the runner; the water pressure pulsation is larger after the runner, the maximum reaches the double peak 0.123 right, and the minimum value is also 0.05, which is the design of the water head 70 and 30. The water diversion system is so large. Water pressure pulsation will inevitably lead to deterioration of unit operating stability.

3 Increase the capacity of the relay. Weaken the principle of continuous flow of water pressure pulsating foot 1 , the pulsation of water spurs in the machine hunger will inevitably lead to the change of the flow direction of the 7-foot turbine guide vane, so that the water torque of the guide vane changes, that is, the load force of the vane relay. Even if the input signal speed and speed of the governor are given to the opening degree and the parameter setting is unchanged, the force balance state of the servomotor is destroyed due to the change of the load force of the servomotor, and the servomotor is caused by the new load. sport. Regardless of the adjustment, the device is in the automatic state or the swaying state, and the relay is remotely moved through the feedback link to make the main pressure-activated activity hide as the corresponding difference, the pressure curve of the main pressure regulating valve of 1. However, the load force of the servomotor is randomly changed, and the water pressure pulsation time changes. If the surface of the relay is a special relay! When the chamber pressure is the closing pressure of the household relay, and the load force of the vane servo is changed, the balance of the servo load can be obtained from the pressure curve of the main pressure regulating valve, and the balance is required to establish a new balance. The pressure valve is changed in the position of the suction chamber and it is the slope of the closed cavity pressure curve. From the above formula, it can be seen that the change value of the piston position of the main pressure regulating valve is proportional to the amplitude of the change of the force of the vane relay, and is inversely proportional to the blood volume of the servomotor. In the turbine governing system, due to the feedback link, the main pressure regulating valve is controlled by the feedback of the servomotor. If the input signal is unchanged, the position change of the piston of the main pressure regulating valve is proportional to the swinging amount of the servomotor. Regardless of the station automatic state or manual state, the connection will inevitably lead to the unit speed swing; in the grid-connected power generation condition, the relay will not only cause the displacement of the servo due to the change of the network frequency, but also the relay due to the water pressure fluctuation of the unit flow channel. The change in the load of the occupant causes the servo to oscillate.

Or increase the relay of the piston and smash. The working oil pressure of the factory 0150000 is 3.74.03, which increases the working oil pressure by the pressure source of the hydropower plant; increases the piston area of ​​the relay, and is limited by the building conditions. It is not used to switch to the large electro-hydraulic governor. Possible; after research, it is proposed that under the condition of the original governor installation size, the capacity of the servomotor will be redesigned and manufactured by the Tianjin Electric Transmission Design Institute from the experimental results of the 50 4 experimental results, and the 17500 programmable step-edge turbine-type turbine governor. The governor adopts a programmable controller as the core, and replaces the electro-hydraulic converter with a stepping motor cam mechanism. This oil-free motor is converted, the corner is small, and the electro-hydraulic servo system composed of several islands is caused by the island pollution. Respond to the problem, and the governor has less fuel consumption under normal working conditions, the number of starts and stops of the oil pump is small, and the maintenance workload is reduced. The touch is used as a man-machine, and the 232 is used for communication with the position machine. Limited and two-stage closing device.

After your 150000 governor, perform the pre-watering adjustment test, and measure the governor speed dead zone=0.03. In the automatic state, the servomotor swing value is less than 025, the coffee is the same as the original governor. After filling the water, the machine is smashed. The speed swing value of my working condition is swaying. 2. Under the automatic no-load condition, the speed swing value is 0.5 pressure, which will reach 0. Fujian Electric Power Test Institute, Shaxikou Unit 5 stability test, 1998.

The speed swing value is reduced by 1312, and the rest of the performance is in line with the technical requirements of the turbine governor and the hydraulic device.

As a result, the new governor of the version was replaced by 50,000, and the peripheral gear was successful. It achieved the modified eyepiece and increased the capacity of the vane relay. It was more ideal for weakening the water pressure pulsation after the runner. In addition, the new governor replaces the electro-hydraulic converter with a stepper motor cam mechanism, and there is no resistance to oil pollution, the reliability is greatly improved, and the oil filter and the hand are not required to be automatically switched. Simple structure. Easy to maintain.

19652.21997, Hydraulic turbine governor and hydraulic device test acceptance procedures 8. Beijing China Standard Press, 1997.

19652.997, Technical requirements for turbine governor and hydraulic device 8. Beijing China Standard Press, 1997.

Fu Zhian, Feng Jiayu. Concrete face rockfill 1. Wuhan Huazhong University of Science and Technology Press, 1993.

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