基于PLC技术的变频器自动控制研究

Research on frequency converter automatic control based on PLC technology

研究基于PLC技术的变频器自动控制,由电源、编程器、中央处理单元、存储器、输入输出单元和外部设备组成的PLC接收变频器发出指令后分析指令,并利用编程后指令控制变频器。基于变频调速基本原理,具体分析变频器在工频范围调节大于电源频率、工频范围调节小于电源频率、转差频率控制三种情况下变频调速控制方程,利用控制方程实现基于PLC技术的变频器不同工作状态时的自动控制。实验结果表明,将该方法应用于某电动修井机恒功率自动控制系统中,可有效实现系统的变频自动控制,采用该方法控制的修井机恒功率自动控制系统在10天变频工作状态下平均能耗与平均用电量仅为181 J以及1 181 kW·h。

The frequency converter automatic control based on PLC technology is researched in this paper. The PLC composed of the power supply, programmer, CPU(central processing unit), memory, input/output unit and external equipment,receives the instructions sent out by frequency converter,and then analyzes them. The programmed instruction is used to control the frequency converter. The governing equation of variable frequency speed regulation is analyzed according to the basic principles of variable frequency control speed when the frequency converter is used to adjust the supply frequency being larger than the power frequency in power frequency range,the supply frequency being smaller than the power frequency in power frequency range and the slip frequency control. The governing equation is used to realize the frequency converter automatic control(in different working states) based on PLC technology. The experimental results show that the frequency conversion automatic control of the system can be effectively achieved when the proposed method is used in the constant power automatic control system for a certain electric workover rig. The average energy consumption and average electricity consumption of the constant power automatic control system of the workover rig controlled with this method are only 181 J and 1 181 kW·h under the 10-day frequency conversion working condition.