Recent content by ffp

I I'm not sure I understand what you said. But I still have to calculate the C1 and C2 constants...

Yes, you are right, that was my mistake when typing the statement. Thank you for pointing out. The correct inequity is t<0. I really think the question is missing something now, reading all you guys answers. This is all all we can get, right?

That was a desperate atempt to find the answer. I did it, not knowing it was right (tbh I thought it was wrong). Now I know is definitely wrong. This question is from a public test for a government company in my country. So, it should have been disregarded, right (it wasn't, though).

@Mark44 , yes I provided the complete statement. Had to translate it, because it's not in english, but there is no aditional info...

If you can understand my handwriting, this is how I did it. Until up to the characteristic equation, I believe I got it right. My issue is with the constants calculation. As I posted in OP, I did ##V_i(0)=0## and ##V_i'(0)=0##, but I don't know if this logic is correct. PS: Are...

Ok, I think I got it right now. And no, there is no ##V(t)##, only ##V_0(t)## and ##V_i(t)##, that are the output and input voltage respectively.

It's a multiple choice exercise and I have managed to find the characteristic equation V0(t) which is ##V_0(t)= C_1e^{-t}+C_2e^{-3t}## Initially I thought that it was a non homogeneous ODE, but doing the math for the right part of the equation, I found out that it equals to 0. So, I need help...

Ok, now I'm studying symmetrical components. Im using Stevenson's Power System Analysis book and example 11.9 asks for the zero sequence circuit of the example 6.1 in the same book. Here's the example and the solution: Here's example 6.1, so we can see what is the circuit: Here's the...

Yeah, I'll try to not mix things up. I too feel I'm going in circles, but mostly because I'm not focusing where matters. I was re-reading the thread and I'll try to put what I think as simply as I can. There are 4 scenarios: A.1) generator alone with load gets turbine speed increased...

@anorlunda and @cnh1995 h Thanks a lot for your answers. The explanations about how the grid fix frequency and voltage were useful for understanding. My issue was with the notion that increasing If would change reactive power. That's not intuitive at all. As I was studying induction motors and...

Yes, I have already seen synchronization of parallel generators. How exactly is frequency (speed) and voltage fixed in the grid? I know that, as you said, to connect a new generator in parallel, thyçey have to match frequency (a bit higher before connecting) and voltage. But that doesn't mean...

Thanks for the torque explanation. I have forgoten that in generator mode, there is a torque opposing the rotation and it is proportional to the load, right? About the book, it's Electric Machinery Fundamentals by Chapman. I stopped in this part: I can understand the explanation using the...

Then the torque that is changed by If is the electromagnetic torque, which is opposed to the prime mover?? Wouldn't that mean that increasing If ( and thus EM torque) reduce shaft speed?

Icreasing field current increases Φ (flux), which increases Ea (internal voltage). Increase in voltage increases real power, and I believe that's what you mean by Pgenerator, right? Ok, in this case Pin, which is equal to τ.ω (torque x angular velocity) is also increased by the change in If...

I'm sorry, but i couldn't find the answer. To change the reactive power, the Ea (and thus Vt) have to be lagung or leading in relation to the voltage of the infinite bus, right? Ea is equal to K(constructive constant) x Φ (flux) x ω (angular velocity if shaft).Since the If (field current) is...