A Research On Crude Oil Dehydration Power Supply With Alternate Current Rectangle-wave Based On PLC

At present, with the oilfield going into high water cut stage, moisture of crude oil has increased, the level of oil-water emulsion has greatly deteriorated, all of these cases lead to a substantial increase of difficulty in dehydration. In this circumstance, conventional dehydration power supply which output sinusoidal waveform at 50Hz gradually expose some defects like electric instability, low efficiency of dehydration, serious consumption of power. So, at present, conventional dehydration power supply can no longer well positioned to meet production needs. In addition, common microcomputer control mode needs much cumbersome design on hardware, software and anti-jamming to answer the complex condition of dehydration. So, it is of great significance towards dehydration work in developing power supply with both high efficiency and high degree of automation.In order to solve the above problems faced by oilfield, this paper analysed the fundamental mechanism of electric dehydration, and proposed the research on power supply with rectangular wave. The power that controlled by efficient industrial and automation component PLC output pulsed electric field with voltage amplitude, frequency and duty cycle adjusted enabling dehydration work run in the best status.In the design of main circuit, this paper analyzed and selected the structure of circuit program. Components mentioned in rectification and filter circuit, voltage regulation circuit, rectangular wave generating circuit, surge protection and detection circuit in the main circuit are designed and choused. In PLC control circuit, this paper determined the overall structure of the hardware based on the requirements of system, presented the type and hardware of the PLC system, and designed control circuit of voltage amplitude, frequency, duty cycle based on SG3525 chip. Besides, it also introduced the design of PWM signal driving circuit and protection circuit. PLC controlling software designed two work modes including manual operation and automatic control. Under automatic control, the procedure had a real-time detection of dehydration current which can rapidly controlled by adjusting the output voltage to ensure stable operation of the electric field.In order to solve the man-machine interaction problems of PLC better, this equipment used touch panel technology. According to the actual application, this paper choused type eviewMT4500T, and set the software and hardware communication status between PLC and touch panel. Man-machine interface set several function interfaces which lead to intuitive and natural operation such as boot welcome, the system parameter settings, manual/automatic work, dehydration process animation, historical trends, fault alarm, rights management, instructions etc.Finally, both hardware and software of the power equipment were debugged. Laboratory experiments and field application showed that this power equipment can run safely and reliably. Moisture content of the cleaned oil ratio meets the national standards with a clear oil-water interface. Besides, it has a significant effect on energy saving.