Water pump turbines are mainly used in pumped storage power plants. When the load of the power system is lower than the basic load, it can be used as a water pump, utilizing excess power generation capacity to pump water from downstream reservoirs to upstream reservoirs and store energy in the form of potential energy; When the system load is higher than the base load, it can be used as a water turbine to generate electricity to regulate peak loads. Therefore, pure pumped storage power plants cannot increase the electricity consumption of the power system, but can improve the operational economy of thermal power generation units and improve the overall efficiency of the power system. Since the 1950s, pumped storage units have been widely valued and rapidly developed in various countries around the world.
Most of the early developed or high head pumped storage units used a three unit type, consisting of a generator motor, water turbine, and water pump in series. Its advantage is that the water turbine and water pump are designed separately, which can each have high efficiency. Moreover, the rotation direction of the unit during power generation and pumping is the same, which can quickly switch from power generation to pumping, or from pumping to power generation. At the same time, a water turbine can be used to start the unit. Its drawbacks are high cost and high investment in power plants.
The blades of the diagonal flow
pump turbines runner can rotate and still have good operating performance under changes in water head and load. However, due to limitations in hydraulic characteristics and material strength, by the early 1980s, its maximum water head was only 136.2 meters (Kogen First Power Station in Japan). For higher water heads, a mixed flow
pump turbine is required. The pumped storage power station has two reservoirs, upper and lower. Under the condition of storing the same energy, increasing the head can reduce the storage capacity, increase the unit speed, and reduce engineering costs. Therefore, the development of high head energy storage power stations above 300 meters is rapid. The mixed flow
pump turbines with the highest water head in the world is installed at the Baynabashta Power Station in Yugoslavia, with a single unit power of 315 megawatts and a water turbine head of 600.3 meters; The water pump has a head of 623.1 meters and a speed of 428.6 revolutions per minute, and was put into operation in 1977.
Since the 20th century, hydroelectric units have been developing towards high parameters and large capacity. With the increase of thermal capacity in the power system and the development of nuclear power, in order to solve the problem of reasonable peak shaving, countries around the world are actively building pumped storage power stations in addition to vigorously developing or expanding large-scale power stations in major water systems, and
pump turbines have thus developed rapidly.
In order to fully utilize various hydraulic resources, tidal, low drop plain rivers, and even waves have also attracted widespread attention, leading to the rapid development of tubular turbines and other small units.
