What Is a Pump Rate?

The overall efficiency of a pumped storage power station is also called "total efficiency of a pumped storage power station", which is the product of the pumping efficiency and the power generation efficiency of the power station. Pumping efficiency refers to the efficiency of the energy storage process, which is the product of the efficiency of the transformer, pump, motor and pressure water pipe. Power generation efficiency is the product of the efficiency of pressure water pipes, turbines, generators and transformers. The comprehensive efficiency of large-scale pumped storage power stations is 0.75 ~ 0.77. ^[1]

Pumped storage power stations are composed of buildings such as an upper reservoir, a water delivery system, a factory building with an organic group, and a lower reservoir. The upper reservoir of a pumped-storage power station is an engineering facility that stores stored water. The pumped water can be stored in the reservoir during periods of low load on the grid, and the reservoir can be used to generate electricity during peak periods of load. The water delivery system is an engineering facility that transports water. In the pump mode (pumping), the water from the lower reservoir is sent to the upper reservoir. In the turbine mode (power generation), the water discharged from the upper reservoir is transmitted to the lower reservoir through the plant. The workshop is a place for storing important mechanical and electrical equipment such as energy storage units and electrical equipment, and it is also the center of power plant production. Whether the pumped storage power station completes basic functions such as pumping and power generation, or plays important roles such as frequency modulation, phase modulation, load climbing and emergency standby, it is completed by the mechanical and electrical equipment in the plant. The lower reservoir of a pumped storage power station is also an engineering facility for storing water. It can meet the needs of pumping during low-load periods, and it can store water for power generation and release during peak periods.

Pumped-storage power stations can produce peak power, that is, the energy from the non-peak load period is converted into the peak load period. In order to achieve this, the energy must undergo two special exchanges, and losses will inevitably occur during the conversion process. However, the amount of electrical energy lost can be compensated from the highest quality improvement. Therefore, when designing a pumped storage power station, the economic impact of these two factors must be fully considered. ^[2]

The pumped electricity of a pumped storage power station will generate the amount of electricity produced by Taiko, that is, there is an energy loss when the energy conversion is realized. During a cyclic operation, the ratio of the product of the working efficiency of the water delivery system, turbine, generator, and main transformer under the power generation condition to the product of the working efficiency of the main transformer, motor, pump, and water delivery system under the pumping condition is called pumping. The comprehensive efficiency of a storage power station is an important indicator of its technical and economic characteristics. During the design, if the comprehensive efficiency of the pumped storage power station is required to be determined more accurately, it should be calculated and determined according to the engineering layout characteristics of the power station, the operating characteristic curve of the unit used and the operation mode of the power station in the power grid. For a pumped storage power station that has been running, the ratio of the amount of electricity generated to the amount of pumped electricity is often used to indicate its overall efficiency. The general efficiency of pumped storage power stations is generally 0.65 ~ 0.75. Large pumped storage power stations are mostly above 0.70, and pumped storage power stations with excellent conditions can reach 0.78.

Pumped storage power stations using reversible units, because the unit has to take into account two operating conditions, its high efficiency area is relatively narrow, compared with the four-machine, three-machined pumped storage power stations, the overall efficiency is generally lower . However, the use of reversible units can save equipment and reduce investment. The advantages are still outstanding. With the continuous improvement of the unit design and manufacturing level, its overall efficiency has been greatly improved. ^[3]

Maximum efficiency depends on the design and manufacture of the machine, the capacity of the unit, the head, the method used to transfer water to or from the power station, and a number of other factors.

Changes in traffic or power grid load

Efficiency is usually expressed in two limits. However, under various operating conditions, due to changes in flow or power network load, the unit is rarely able to operate at the operating point corresponding to the highest efficiency, so the time for these extreme efficiencies to appear is short. Even if the unit can run continuously under full load, due to the manufacture of the machine and the benefit of taking care of the partial load, the maximum efficiency cannot be achieved.

Inlet and waterway loss

Head loss occurs at the water inlet and in the water channel, that is, the loss of the water delivery process due to pipeline factors, such as head loss at the pipeline, loss at the inlet and outlet, loss on the pollution barrier, loss on the friend and special sections Wait. ^[4]

1. When designing, it is best to make the machine reach the highest efficiency when it is running as a pump or turbine, not under full load, but under 70 ~ 80% load;

2. During the needle setting and construction, attention should be paid to the anti-seepage problem of the upper pond, and the leakage loss should be reduced as much as possible. This is also beneficial to the stability of the pool walls and embankments, but also necessary for other structural conditions.

3. When designing the water channel and water inlet, try to reduce the water head loss in these two parts as much as possible, such as optimizing the design of the pollution barrier to reduce the loss caused by pollution. ^[4]