K系数变压器

GRACE_HE

现在越来越多的用户提到一个K系数的概念，不知道那位高人对这个有没有深入了解，大家来讨论一下啊

jeff201099

我设计过好多K-Factor变压器，你先看看下面的资料，如果有问题，再提出来
There are two methods for calculating K-Factor.
1. UL Method
2. Normalized Method
The UL method, based on the transformer’s rated root-mean-square (rms) current, is
generally used when rms current is measured. The UL method is defined as follows:
K=SIh(pu)2 h2
h=1
where:
h = harmonic order
Ih(pu) = rms current of the harmonic expressed as a per unit of the rated rms
transformer current
The normalized method is based on the load’s fundamental current. Harmonic
measurements are often taken with a harmonic analyzer. A majority of harmonic
analyzers output harmonics as per unit values related to the fundamental current.
Therefore, the normalized method would be used. The normalized method is defined
as follows:
K= Sfh
2 h2/ Sfh
2
h=1 h=1
fh = fundamental current in per unit (the 1st harmonic = 100%)
An example of the two methods for the same harmonic spectrum of data follows. For
the example assume that measurements were taken to obtain Ih(pu).
UL Method
Harmonic Ih(pu)
(measured) Ih(pu)2 h2 Ih(pu)2 h2
1 0.72 0.52 1 0.52
3 0.52 0.27 9 2.43
5 0.31 0.10 25 2.40
7 0.25 0.06 49 3.06
9 0.15 0.02 81 1.82
11 0.07 0.00 121 0.59
13 0.05 0.00 169 0.42
K-Factor= 11.24
Normalized Method
Harmonic fh(pu) fh(pu)2 h2 fh(pu)2 h2
1 1.00 1.00 1 1.00
3 0.72 0.52 9 4.69
5 0.43 0.19 25 4.63
7 0.35 0.12 49 5.91
9 0.21 0.04 81 3.52
11 0.10 0.01 121 1.14
13 0.07 0.00 169 0.82
1.88 21.71
K-Factor= 21.71/1.88 = 11.54
4 4
4
Both methods will yield approximately the same answer. A K-Factor of 11 is
calculated. Therefore, the next available K-Factor of 13 would be chosen.
Table 3 lists the available K-Factor rated transformers.
Table 3
Available K-Factor Transformers for Dry-type Transformers
K-Factor Comments and Typical Applications
1 Normal Transformer for sinusoidal load applications with a
harmonic factor less than 0.05
4 Welders and induction heaters, HID and Fluorescent lighting,
Solid state controls
9 Not readily available or usually specified
13 Telecommunications equipment, Classrooms and Health Care
Facilities
20 Data Processing Equipment, Adjustable Speed Drives
30 Extended Range
40 Extended Range
50 Extended Range

GRACE_HE

谢谢2楼的回复。
我也看了一些怎么计算K系数的方法，我就是比较关心知道了K系数是多少，变压器应该降容多少使用，或者是增容多少设计，我看到一些计算降容多少的公式里面有个Pecr的数值，这个值是怎么算啊

zwd8812

2楼的您好，能否具体讲解一下K系数的一些设计思路，如磁密和电流密度的取值，硅钢片的材料是有取向还是无取向，初次级间是否需加屏蔽层？谢谢！

三毛

2楼是高手啊,如果有设计实例就好了.