Method for determining regulation range of pumping power of three-machine pumped storage unit

An apparatus for regulating pumping power of a three-machine pumped storage unit, the three-machine pumped storage unit comprising a generator, a water pump, and a hydraulic turbine, a main shaft of the generator having one end connected to the water pump and the other end connected to the hydraulic turbine, the apparatus comprising:

• a processor and a memory storing instructions that, when executed by the processor, cause the processor to perform the following steps;
• determining an allowable regulation range of the pumping power of the three-machine pumped storage unit, wherein,
• obtaining a first parameter set of pumping measurement parameters for characterizing the three-machine pumped storage unit, wherein the first parameter set comprises a gravitational acceleration, a water head, an inflow, power absorbed by a power grid, and a design efficiency of a pumped storage power station,
• determining a pumping process efficiency based on the gravitational acceleration, the water head, the inflow, and the power absorbed by the power grid, wherein the pumping process efficiency is obtained when the generator, the water pump, and the hydraulic turbine in the three-machine pumped storage unit operate simultaneously,
• determining a first relational expression based on the pumping process efficiency and the design efficiency of the pumped storage power station, wherein the first relational expression reflects a relationship between the pumping process efficiency and the design efficiency of the pumped storage power station;
• establishing a second relational expression based on the first relational expression, wherein the second relational expression characterizes power of the hydraulic turbine;
• determining a third relational expression based on the power absorbed by the power grid and the second relational expression, wherein the third relational expression reflects a first regulation range of the power absorbed by the power grid during pumping by the three-machine pumped storage unit;
• and
• determining a fourth relational expression based on the third relational expression, wherein the fourth relational expression reflects the allowable regulation range of the pumping power of the three-machine pumped storage unit;
• wherein, the first relational expression is
• gH(Ppηp/gH−Pt(gHηt))/Pp−Pt)≥ηpower station;
• where gH(Ppηp/gH−Pt(gHηt))/Pp−Pt) represents the pumping process efficiency, ηpower station represents the design efficiency of the pumped storage power station, g represents the gravitational acceleration;
• H represents the water head;
• Pp represents of a power of the water pump, ηp represents weighted average efficiency of the water pump, ηt represents weighted average efficiency of the hydraulic turbine;
• the second relationship is Pt≤(Ppηp−APp)/(1/ηt−ηpower station);
• the third relational expression is
• Pm≥Pp−(Ppηp−ηpower stationPp)/(1/ηt−ηpower station);
• Pm represents the first regulation range of the power absorbed by the power grid during pumping by the three-machine pumped storage unit;
• the fourth relational expression is
• Pp−(Ppηp−ηpower stationPp)/(1/ηt−ηpower station)≤Pm≤Pp;
• during pumping operation, operating the water pump and the hydraulic turbine simultaneously,
• opening ball valves at an upstream part of the water pump,
• opening ball valves of the hydraulic turbine are opened to a certain degree according to a power requirement, and
• regulating the pumping power of the three-machine pumped storage unit within the allowable regulation range.