Research And Development On Control System Of Step-By-Step Microcomputer Governor Based On PLC

Hydropower turbine governor is one of the most important control equipment in the Hydropower station.the merits of its performance impacts on power quality and safe and reliable operation of the hydropower station. Therefore it's very important to develop high-performance turbine governor.The step-by-step computer governor based on PLC with simplement, strong anti-oil pollution, high positioning accuracy, a small amount of leakage and high reliability advantages, has been widely used. However, there are more microcomputer hardware modules, high price of the driver module and other issues, thus the Step-by-step Computer PLC governor is limited in the small and medium-sized hydropower station.This Paper by Siemens S7-200 PLC as the core, using S7-200PLC's two-way high-speed pulse of the output function, one high-speed pulse-output outputs the pulse into a step motor to control the step motor's speed, by changing the pulse frequency to control the step motor; The other high-speed pulse-output outputs variable duty cycle of the PWM to control the step motor drive voltage. Using software or frequency to boost step motor's drive circuit functions ,it achieved rapid, high-precision step motor driven with the simple pulse amplification circuit, it does not require special or frequency step-up circuit, reducing the the complexity of the hardware circuit.Test results by the programmable / machine servo amplifier system of governor based on PLC showed that: the control system of step-by-step microcomputer governor based on S7-200PLC has high accuracy and good quick-motion. It has more broad prospects in the small and medium-sized hydropower stations.