Main winch retracting and stretching control system of rotary drilling rig and rotary drilling rig

The invention discloses a main winch retracting and stretching control system of a rotary drilling rig, which comprises a first main pump, a second main pump, a main winch motor and a balance valve. Two oil inlets of the main winch motor are communicated with an ascending oil inlet passage and a descending oil inlet passage respectively; the first main pump and the second main pump both provide oil for the ascending oil inlet passage; the first main pump provides oil for the descending oil inlet passage; and the balance valve is arranged between the ascending oil inlet passage and the descending oil inlet passage. The system also comprises a flow converging valve communicating the ascending oil inlet passage with the descending oil inlet passage, wherein the first working oil inlet of the flow converging valve is communicated with the ascending oil inlet passage; the second working oil inlet of the flow converging valve is communicated with the descending oil inlet passage; the control oil inlet of the flow converging valve is communicated with a pilot control loop; and the flow converging valve is arranged between the main winch motor and the balance valve. The invention also discloses the rotary drilling rig.