The water turbine is a turbomachinery in the fluid machinery. As early as around 100 BC, the prototype of the water turbine, the water wheel, was born. At that time, the main function was to drive machinery for grain processing and irrigation. The water wheel, as a mechanical device that uses water flow as power, has developed into the current water turbine, and its application scope has also been expanded. So where are modern water turbines mainly used?
Turbines are mainly used in pumped storage power stations. When the load of the power system is lower than the basic load, it can be used as a water pump to use the excess power generation capacity to pump water from the downstream reservoir to the upstream reservoir to store energy in the form of potential energy; when the system load is higher than the basic load, it can be used as a hydraulic turbine , generates electricity to regulate peak loads. Therefore, the pure pumped storage power station cannot increase the power of the power system, but it can improve the operating economy of thermal power generating units and improve the overall efficiency of the power system. Since the 1950s, pumped storage units have been widely valued and developed rapidly in countries around the world.
Most of the pumped storage units developed in the early stage or with high water head adopt the three-machine type, that is, they are composed of a generator motor, a water turbine and a water pump in series. Its advantage is that the turbine and the water pump are designed separately, which can each have higher efficiency, and the unit rotates in the same direction when generating electricity and pumping water, and can quickly convert from power generation to pumping, or from pumping to power generation. At the same time, the turbine can be used to start the unit. Its disadvantage is that the cost is high and the power station investment is large.
The blades of the runner of the oblique flow pump turbine can be rotated, and it still has good operating performance when the water head and load change. However, due to the limitation of hydraulic characteristics and material strength, by the early 1980s, its net head was only 136.2 meters. (Japan’s Takagen First Power Station). For higher heads, Francis pump turbines are required.
The pumped storage power station has upper and lower reservoirs. Under the condition of storing the same energy, increasing the lift can reduce the storage capacity, increase the speed of the unit, and reduce the project cost. Therefore, the high-head energy storage power station above 300 meters has developed rapidly. The Francis pump-turbine with the highest water head in the world is installed in the Baina Basta Power Station in Yugoslavia. year into operation. Since the 20th century, hydropower units have been developing in the direction of high parameters and large capacity. With the increase of thermal power capacity in the power system and the development of nuclear power, in order to solve the problem of reasonable peak regulation, in addition to vigorously developing or expanding large-scale power stations in major water systems, countries around the world are actively building pumped-storage power stations, resulting in rapid development of pump-turbines.
As a power machine that converts the energy of water flow into rotating mechanical energy, a hydro turbine is an indispensable part of a hydro-generator set. Nowadays, the problem of environmental protection is becoming more and more serious, and the application and promotion of hydropower, which uses clean energy, is increasing. In order to make full use of various hydraulic resources, tides, plain rivers with very low drop and even waves have also attracted widespread attention, resulting in the rapid development of tubular turbines and other small units.
Post time: Mar-23-2022
