What does "Phase jump" mean? 1

[haussys]

Hi everyone,

I got one clarification from one customer:
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The Renewable Power Plant shall be designed to withstand sudden phase jumps of up to 40° at the POC
without disconnecting or reducing its output. The RPP shall after a settling period resume
normal production not later than 5 sec after the operating conditions in the POC have reverted
to the normal operating conditions.
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To my mind this word "phase jump" is not very clear. Does this refer to the voltage angle of the machine?
Any one can help me out and give some clear scenarios how we can face a phase jump?
And what will be the consequence on the turbine or generaor?

BR

 

[cranky108]

In the transmission world, it is possible to have a line, or transformer suddenly fault and disconnect from the transmission grid. The removel of the faulted element would result in an angle change for the voltage on the busses in the area of the now deenergized element. This is what I would assume.

Some of us call this an angular shift with a possibility of a swing condition, or an out-of-step condition.

What would happen is the generator on an affected bus would have to adjust to the new condition, which includes changes in var flow up and down until it settles in to a new steady-state.

The size of angle shift that a generator can handle depends on the size, strength of the magnetic field, and var loading.

 

[haussys]

Hi Cranky108

Thank you very much for your help.
I have some difficulties to interpretate the "voltage angle". Is it called "load angle" also? or is it angle between U & I

So it means to avoid out of step condition the excitation system has to be fast with high forcing ratio.
Could be worth to add a PSS.

 

[LionelHutz]

My interpretation would be that the phases can shift forwards or backwards in time. In other words if the waveform is rising from the negative peak and just reaches 0V the waveform could suddenly shift so the voltage is negative again and once again rises to 0V but 40* later in time.

 

[Bronzeado]

haussys

"Phase jump" is just a suddenly angle shift on system voltage that occurs mainly during a short-circuit in the system.
In general it is comes with a voltage sag.

Please, see attached an example of a "phase jump".

Best Regards,

Herivelto S. Bronzeado
Brasília, Brazil

http://www.linkedin.com/profile/view?id=46319837&trk=tab_pro

 

[haussys]

Dear Bronzeado

Thank you very much for this figure and the explanation however it is now less clear
In the figure what do Vs and Vs represent?

So in such an event what will be the reaction of the generator? What is critical ? and how could we recover from this situation? by using a PSS or High Field forcing AVR or overdesign the generator?

Thanks

 

[Bronzeado]

Dear haussys,

Sorry for confounding you.
vs and vs2 is the system voltage before and after a short-circuit (fault), respectively.

The generator reaction depends on the type of the wind generator. The Wind Power Plant shall be designed to withstand sudden phase jumps (up to 40°) and also voltage sags without disconnecting from the power system.

Best Regards,

Herivelto S. Bronzeado
Brasília, Brazil

http://www.linkedin.com/profile/view?id=46319837&trk=tab_pro