Graded underground pumped-storage hydropower in coal mine, construction and using methods

A method of constructing graded underground pumped-storage hydropower in a coal mine, comprising:

• confirming a position and a number of one or more underground reservoirs based on geological conditions of a mine, and roof and floor conditions of a working face;
• confirming a width of a protective coal pillar between a production roadway and the working face based on a mine pressure behavior law, and planning a mining sequence;
• after confirming the position of the one or more underground reservoirs, confirming a position of a hydraulic turbine room on one side of an underground reservoir in this layer, and excavating a pedestrian roadway to the hydraulic turbine room through the rock strata from the production roadway;
• performing a constructional backfill mining on the coal mine based on the confirmed position of the underground reservoir, and when coal resources are mined to form the underground reservoir, it is backfilled to form a backfill column as required;
• excavating an upward water conveyance passageway and a downward water conveyance passageway between the hydraulic turbine room and the underground reservoir on each layer;
• excavating a second water pipeline between the hydraulic turbine room among layers;
• excavating a first water pipeline between a surface reservoir and a first layer hydraulic turbine room;
• there is no requirement to construct a downward water conveyance passageway in the underground reservoir at a lowest layer;
• arranging sluice gates at both ends of the first water pipeline, the second water pipeline, the upward water conveyance passageway and the downward water conveyance passageway;
• and
• performing an anti-leakage treatment on a goaf to prevent water body leakage, thus obtaining a graded underground pumped-storage hydropower system.