Regulations for the selection of turbines in hydroelectric power plants are very important. Each regulation is formulated to better solve practical problems and is formulated based on actual conditions. Zhongda Consulting will explain the rules for selecting turbines in hydroelectric power plants.
1. The selection of the unit capacity should be based on the determination of the total installed capacity of the hydroelectric power station, taking into account the proportion of the unit capacity in the total working capacity of the power system, the growth rate of the load of the system, arrangement of hydroelectric power station pole, unit and reservoir. Depending on the mode of operation, the rationality of the unit parameters, the technological level of manufacturing the unit and the transportation conditions, etc., different plans are proposed and determined by technical and economic criteria.comparison. When technical and economic indicators are equivalent, a higher capacity unit should be used. The number of units is usually not less than two.
Once the turbine model is selected, the rationality of increasing the generator capacity or improving the power factor operation should be studied based on factors such as operating characteristics of the turbine and the characteristics of the hydraulic kinetic energy.
2. The nominal water height (net height) of the hydraulic turbine should be reasonably selected according to the working mode of the reservoir and the role of the hydropower plant in the power system. When the design water height is close to the minimum or maximum water height of the hydropower plant, its economy and rationality must be demonstrated.
3. The selection of the hydraulic turbine mustadopt a reasonable specific speed according to the working head range, and select a runner with high average efficiency, good cavitation performance and stability.
According to the unit capacity, working head range, operation mode and the complete characteristic curve of the channel model, the main parameters such as channel diameter , the rotation speed and suction height are reasonably selected.
When selecting turbine parameters, it is also necessary to consider the initial low-head operation of the hydropower plant and the special water quality requirements for the turbine .
4. The installation elevation of the turbine should be reasonably selected by technical and economic comparison based on the permitted suction height of the turbine under various working conditions and thecorresponding downstream waste water level. The downstream waste water level should be selected based on the operation mode of the reservoir, the production variation range of the hydropower plant, the initial operation requirements of the hydropower plant, the installation period of unity and changes in the course of the river downstream.
5. The maximum runaway speed of a fixed-blade mixed-flow or axial-flow turbine must be determined based on the maximum net water height of the turbine and the maximum possible opening of the guide vane. For axial flow propeller turbines, the runaway speed must be calculated based on the runaway coefficient without destroying the association relationship. In special cases, it can be calculated based on the escape coefficient when the association relationship is destroyed.
6. When selecting a hydraulic turbinethat, new achievements in turbine manufacturing must be taken into account. The adoption of major new technologies (including types, structures and materials, etc.) must go through scientific testing and generally must be submitted. technical evaluation.
Hydraulic turbines should have anti-cavitation measures. In hydropower plants with sediment-rich rivers, anti-wear measures should be taken for the through parts of the turbines, and the structure should be convenient for maintenance and replacement of wearing parts.
7. For the selected hydraulic turbine, the efficiency guarantee, power guarantee, cavitation guarantee and stable operating range guarantee offered by the manufacturer must be obtained, as well as technical information such as the complete characteristic curve and the functioning. characteristic curve of the modele hydraulic turbine. If necessary, a water wheel supplied by the manufacturer should also be obtained.information necessary to accurately calculate the machine transition process.
8. When the maximum water height is less than 40 m, a reinforced concrete volute with a winding angle of 180° to 225° should be used. When the maximum water height is 40 m and more, a metal volute with an angle of 345° should be used. If a reinforced concrete volute is used, a technical and economic argument must be put forward.
Anti-infiltration measures should be considered for reinforced concrete volutes.
9. The type and size of the impeller volute and suction pipe should be agreed with the manufacturer taking into account the factory layout or other special requirements. If necessary, this should also be determined by model testing.
10. The conical part of the suction tube must be coveredyou of metal. The elbow part of the draft tube can be made of metal cladding or concrete elbow tube based on technical and economic comparison. The immersion depth of the upper edge of the outlet of the curved suction pipe should not be less than 0.5 m.
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