Abstract: In the frequency variation speed-regulation system,the high frequency harmonic current leads to distortion power N,and the power factor of the system,the input power factor of the invertor,is calculated by the ratio of the active power to the apparent power or by the consine of the angle included between fudamental harmonic current and source voltage.The calculation usually results in a deviation from the actual power factor.This paper gives.a new concept of the power quadrangle made up of S,P,Q and N,presenting the formula to calculate the actual power factor,demonstrating the numerical value relation among actual,total and displacement power factor.The conclusion in this paper has been proved by the field data measured from the oil transferring system with frequency variation speed-regulation in Daqing No.2 Oil Plant.

Key words: frequency variation speed-regulation system, harmonic, distortion power, power factor, power quadrangle, field data

摘要： 功率因数是十分重要的电气参数之一.在变频调速系统中,由于高次谐波电流的影响,将产生畸变功率N,因而系统功率因数即变频器输入端的功率因数,采用有功功率P与视在功率S的比来确定,或用基波电流与电源电压夹角的余弦来确定,均存在偏差.本文提出了由S、P、Q和N构成的功率四边形的新概念,给出了实际功率因数的计算公式;确定了实际功率因数、总功率因数和位移因数之间的大小关系.并利用大庆采油二厂变频调速输油系统的实测现场数据,证实了本文的结论.

关键词: 变频调速系统, 谐波, 畸变功率, 功率因数, 功率四边形, 现场数据