Abstract : This paper briefly introduces the problems existing in the control mode of the original water pumping station system of Dongqing Company. After the transformation by adopting frequency conversion technology, significant economic benefits have been achieved. Keywords : frequency converter; PLC; soft start; AC speed regulation; water pump; energy saving 1 Introduction The adoption of frequency conversion technology for constant pressure water supply is the current trend and direction of industrial control technology development. It can significantly reduce production power consumption, improve the control performance of production machinery and the service life of equipment. Therefore, improving labor productivity and operational quality, and implementing effective automatic control of the entire process can save water resources and electricity. Dongqing Company's power plant has three new water source pumping stations, which are responsible for supplying the company's production and domestic water. These are projects built during the "First Five-Year Plan" period. The original electrical control system is a product of the 1950s. The electrical components are outdated, worn out, and energy-intensive. The production of old-style electrical spare parts is prohibited by the state, and the system can only be barely operated by workers. The drive system is driven by seven 30-75kW squirrel-cage asynchronous motors. All of these motors adopt direct starting. The starting current is approximately 5 to 7 times the rated current, thus posing a significant impact on the power grid. Furthermore, the high starting torque causes substantial mechanical stress, frequently leading to impeller breakage and increased maintenance. Failures in the water supply system directly affect the power grid. Therefore, our company prioritizes energy conservation and consumption reduction. We have made reducing motor energy consumption a primary development direction for lowering product costs. Consequently, we first upgraded the electrical control systems for single and triple water sources, achieving significant energy savings and economic benefits through the adoption of variable frequency speed control technology. [b]2. Pump Variable Frequency Speed ​​Regulation Retrofit Scheme 2.1 Operating Status Before Retrofit[/b] The original pump station system control method was as follows: when adjusting parameters such as flow rate and pressure, workers manually adjusted the outlet valve to make the motor run at rated speed and power frequency, resulting in significant energy loss; manual operation of equipment start-up, shutdown, and load increase/decrease was complex, with low automation, and the limitations of manual control meant that production demands could not be adjusted in a timely manner, failing to meet production requirements; while the original design was based on the maximum load condition, with a certain margin, the actual water consumption fluctuated greatly, i.e., the pipeline pressure fluctuated in the range of 0.2 to 0.42 MPa at different times, resulting in many cases of "overpowered equipment and underpowered vehicles," causing waste of equipment and energy and increasing operating costs. [b][align=center]For details, please click: Application of Variable Frequency Technology in Pump Stations[/align][/b]