2 Synchronous Generators in parallel connection

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Discussion Overview

The discussion revolves around the analysis of two synchronous generators connected in parallel to supply a specific load. Participants are exploring the calculations related to real power dissipation by each generator, considering parameters such as excitation voltage, power factor, and synchronous reactance. The context includes theoretical and mathematical reasoning related to power equations in electrical engineering.

Discussion Character

  • Homework-related
  • Mathematical reasoning
  • Technical explanation

Main Points Raised

  • One participant computed the reactive power of the load, noting that it equals that of generator G1 since G2 operates at unity power factor.
  • Another participant questioned the real power dissipated by each generator, suggesting that the inquiry is about the real power supplied by each generator.
  • There is a request for clarification on the load voltage per phase and the equations for active and reactive power in relation to the voltages and power angles of both machines.
  • A comment was made regarding the high excitation voltage of G1, indicating a potential concern about insulation quality.
  • One participant proposed a mathematical approach involving equations for current and voltage relationships, suggesting that the current through G1 can be derived from the excitation voltage and synchronous reactance.

Areas of Agreement / Disagreement

Participants have not reached a consensus on the specific real power dissipation by each generator, and multiple viewpoints regarding the calculations and interpretations of the problem remain present.

Contextual Notes

There are unresolved aspects related to the assumptions about the load voltage and the definitions of active and reactive power in this context. The discussion also reflects varying interpretations of the problem statement and the parameters involved.

lonelypancreas
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Homework Statement


Two 3-phase 60-hertz 35-kilovolt synchronous generators (G1 and G2) each have synchronous reactances of j9 ohms per phase with negligible armature resistance. They are connected in parallel to supply a 36-megawatt load at rated voltage and power factor of 0.90 lagging. G1 has an exci-tation voltage of 40 kilovolts line-to-line. G2 is operating at unity power factor. What is the real power dissipated by each generator

Homework Equations


Power Equations

The Attempt at a Solution


I have computed the reactive power of the load which is equal to that of g1 since g2 is in unity power factor. I originally planned to get the current through gen 1 to get its complex power ie S = VI* and V is given already. However further down the drain, I acquire a real power of purely Vars in form (it has an imaginary part only)
 
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lonelypancreas said:
...negligible armature resistance...What is the real power dissipated...
 
lonelypancreas said:
What is the real power dissipated by each generator
I believe they are asking for the real power supplied by each generator.

What is the load voltage (per phase)? What are the equations for active and reactive power in terms of voltages and power angles of both machines?
 
lonelypancreas said:
exci-tation voltage of 40 kilovolts line-to-line.

Wow! That machine has some really great insulation!
 
In my opinion, the equation E1-sqrt(3).I1.jXs=Vg and E2-sqrt(3).I2.jXs=Vg and Itot=I1+I2 it is sufficient in order to find I1=function(E1real+jE1imag) and put E1real^2+E1imag^2=40^2 you can find I1.Note: you have to take into consideration I1=I1.(cosfi-jsinfi).
 

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