为什么Eq是无法测定的？

yizhangsjtu

10# qwertyu01
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Many simple looking questions are worthy interesting discussion. I would like to comments as below and wish any corrections that may come up by anyone here.

' d# ], p6 L* {$ o( A8 HEq is measurable, since Eq=If*Xad=Uf-If*Rf, it can be obtain by measuring the voltage and current on the excitation winding. It is possible especially when the exciter is an individual devices. When using self excitation, it may be hard, but should be possible.

/ B, h, ^/ Y; S  X) |2 t3 u6 xEq'' cannot be measured directly, I mean in the steady state. Eq'' is a sub transient EMF at the internal point of generator winding. I would expect it is cannot be obtain by measurement. Firstly, you cannot access the point inside the winding, second, you don't know the exactly location of the X''d on the entire winding (Xd).
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) {1 C- H5 B8 Q& J! uI wonder if the above answered your question?

yizhangsjtu

Eq' cannot be measured for the similar reason as Eq''.

晓夜寒风

Eq‘代表的是磁通量，
. M- v* H. O( f' m( P/ ~3 |
1 t4 B+ l- }$ [5 S$ ]+ A+ O使用这个量是为了计算。
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+ u: F. R  g# L建议楼主看看夏道止的书

qwertyu01

晓夜寒风 能不能说详细点？讨教了。

qwertyu01

yizhangsjtu 的回答我翻了一下。供大家参考。如有错误，请大家提出。
许多看似简单的问题其实是值得我们怀著兴趣去讨论的。我愿意提出如下的看法，希望论坛中的各位提出修改意见。
Eq是可测的。因为Eq=If*Xad=Uf-If*Rf，那就可从Uf，If间接计算出。尤其是使用励磁机励磁的情况更能方便测出来。当用自励时，可能困难些，但也不是不可能办不到。
8 d" Z) K- {3 j2 v/ FEq''在稳态中是不可测的。Eq''叫次暂态电势，是从发电机内部绕组产生的。我认为它不可测是基于以下两点：1。运行人员不能进入内部绕组测量。2.不可能知道此时此地的X''d 值。
我不知道以上的回答是否解答了你的问题。
感谢yizhangsjtu的回答，若是中文就理解更准确了。我希望能说的更详细些，又提个问题Eq'能测吗？

晓夜寒风

稳态的时候，实际上并不存在Eq''和Eq',但是可以算初值。
在暂态的时候，这两个量代表了d绕组和D绕组的磁通量，是无法直接测量的。
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8 P1 L! g3 ]/ d! }0 Z7 e# \对于Eq，yizhangsjtu  已经说得很清楚了。

beaty2003

这个问题确实有点难，多看电机的书吧

cosmic_tao

不得不赞一下楼主的求实精神！：）

晓夜寒风

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( n6 o2 p. g% L1 z( v, ~“如果无阻尼绕组Eq’就不突变”
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有阻尼绕组，Eq’就会突变吗？
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' f) r. ]. c! }- o4 H/ rEq'不是代表了 励磁绕组的磁链吗？

yizhangsjtu

when 有阻尼绕组,
! f  W+ C3 r! A' W& wEq' is not proportional to any 磁链, therefore it won't have the property of keep constant at t0- and t0+.
* }* ]  Y" r0 S: I+ SYou can refer chapter 4 of Prof. Huang Jiayu's book:
"Basic Equations of Synchronous Generator and it's short circuit analysis".