Abstract: In Hunan Province Nanjindu Hydropower Station, the monitoring system of the bulb tubular hydraulic generator set was replaced by the PLC monitoring system. After this, based on original differtential pressure flow measurement method, various hydraulic parameters were readjusted and recalibrated; a complementary measure for flow calculation was added; the effective flow calculation formulas were established; in the design of programs for analog data collecting, calculating and monitoring, the local PLC control penel and the touch screen of monitor and control general system (MCGS) of the unit were used sufficiently. Finally, the realtime monitoring of flow of the hydraulic turbine was realized.

Key words: progammable logic controller (PLC), differential pressure transducer, flow, analog variable, monitor and control general system (MCGS)