Can someone throw light on this matter with regards to voltage stability? We can consider a situation where a generator starts generating more Active Power. To my understanding, the generator voltage E should increase, but how exactly are the load end voltages affected?
Hello Neelotpal,
Please see the attached picture, I hope it helps. One more thing, it is not necessary that E changes when P changes, as E is regulated by the generator excitation system.
Samundra
Hey thanks, even my master thesis is on grid integration of renewanles. But what you shared here, i have a few doubts about that?
Shouldn't it be like Vs = I(R+jX) + V2 ?
Ah no, i got it, but its probably a printing mistake. I guess it should be
V2 = -I(R+jX) + Vs , right?
Neelotpal Majumdar Yes, small error. Please recommend my answer if you find it useful.
Hey, thanks man this was helpful. I always knew that currents would increase because active power generation increases, but i couldn't relate it to the equation P = (EV/X)*sin(d) . But this equation is for power at load end, i guess?
That equation is for sending end, the receiving end power would be your expression minus the line real power loss.
Another way is to use the following equation to find the power at the load end neglecting the line resistance:
P=(V1V2/x )sin (0-d) =-(V1V2/x)sind
Hello Neelotpal,
Voltage stability is a very local problem. Therefore, how load voltage is affected generrally depends on the electrical proximity of generation (you can use elements of the power flow Jacobian matrix dP/dV and dQ/dV for obtaining this "proximity"). It also varies if generator are operated at transmission or distribution level. Normally, voltage is barely affected by active power flow at transmission systems, however, active power generation can strongly support load voltages at distribution system.
Marcos.
Thanks Marcos. Yes, thats true. I do know about the Jacobian matrices.
I just wanted to get a clear idea of the equation that shows how load voltage may vary with generation in a simple 2 or 3 bus system like Samundra Gurung presented.
The same cannot be applied in a multi bus system, because in order to keep the load and generation in balance, the increase or decrease of generation must be compensated by the slack, as a result it will depend on proximity, just like you said.
Hello Neeltopal,
Increasing the active power will cause higher voltage drop across the transmission and/or distribution lines.
Assuming the generator regulates the voltage at its electrical terminals to be constant, the load voltage will decrease with an increase in the active power due to the increased voltage drop across the lines. The amount of voltage drop depends on the impedance of the lines and the location of the load increase and the location of the rest of the loads in the network.
Please find a book Power System Stability and Control, from Prabha Kundur. There you have everything.
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