1. Data required for turbine selection
Before selecting a turbine, in addition to understanding the local hydropower construction policies, the following data and parameters should be collected:
1.1. Water conservancy and hydropower planning and parameters related to the scale of the power station: understand the hydrology, geology, river development methods, reservoir regulation performance, power station type and hub layout of the basin where the hydropower station is located.
Master the head and flow characteristic parameters, such as maximum head, minimum head, average head, design head, maximum flow, average flow, installed capacity and the elevation of the power station and the water level flow relationship curve downstream of the power station.
1.2. Data of the power system: such as the capacity of the power system, load conditions, user nature, the role and status of the designed power station in the system, and the system's requirements for the designed power station.
1.3. Technical data of turbine products: such as turbine model spectrum data, parameters and performance, technical data of similar power stations, etc.
1.4. Local construction and transportation conditions.
2.1 Principles of turbine selection
The principle followed in turbine selection is: select turbines with good performance and small size under the conditions of meeting the output requirements of the hydropower station and adapting to the parameters of the hydropower station (head and flow).
The so-called good performance includes two aspects: good energy performance and good cavitation resistance. Good energy performance requires high efficiency of the turbine. Not only is the maximum efficiency of the turbine high, but also its average efficiency is high when the head and load change. For this reason, a turbine with a gentle curve change should be selected as far as possible within the range of the hydropower station head change. Good cavitation resistance means that the cavitation coefficient of the selected turbine should be small, which can ensure the stable and reliable operation of the unit.
To make the turbine size small, a turbine with a high specific speed should be selected as far as possible. A turbine with a high specific speed has a high speed and a small runner diameter. For this reason, when calculating the turbine selection, a unit speed equal to or slightly higher than the optimal unit speed should be used, and the value should use the maximum unit flow recommended in the model spectrum table to fully utilize the water flow capacity of the turbine and reduce the size of the turbine.
In addition to the above basic principles, the selection of turbines should also consider the easy supply, small transportation difficulties, and convenient construction and installation of the selected units, so as to shorten the construction period of the hydropower station as much as possible and strive for early power generation.
3. Turbine selection content
The procedure for turbine selection is basically to first formulate several possible options, calculate the kinetic energy economic indicators of each option and compare them, and finally determine the best option through optimization. For each option, the main contents of turbine selection are:
3.1. Select the number of units and the capacity of each unit;
3.2. Select the model and installation method of the turbine;
3.3. Determine the runner diameter and speed of the turbine;
3.4. Determine the maximum allowable suction height and installation elevation of the turbine;
3.5. Draw the comprehensive operating characteristic curve of the turbine (generally provided by the manufacturer);
3.6. Determine the form and size of the volute and tailwater pipe;
3.7. Select the governor and hydraulic device.
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