Hello everyone,
I have a question about the park (dq0) transformation of a 3ph voltage vector of an electrical power network. I can't figure out how to deduce the theta angle used in the rotation matrix, in some sources i found that a PLL is necessary to find the (wt) or theta if it's the case can you help me to implement it because it's the first time i discovered it.
Yours sincerely
Use Park transformation to find
the voltage at the generation
Bus.
At this point Use KCL to find the
voltage at every Bus in the
Network. Start with 1 pu for
unknown voltage.
Keep doing this until the
system converge.
Thank you sir Ziad Sobih for your answer ,
my problem is that I want to do a data acquisition of three phase voltage and after that i have to determine the theta angle to make the dq0 (Park) transformation.
With kindest regards
Its a good question and novel technique to find the three phase circuit values. Actually the Direct-Quadrature-Zero (DQZ) transform is made of the Park and Clarke transformation matrices. The Clarke transform converts vectors in the ABC reference frame to the αβγ reference frame. The primary value of the Clarke transform is isolating that part of the ABC-referenced vector which is common to all three components of the vector; it isolates the common-mode component (i.e., the Z component).
The Park transform (named after Robert H. Park) converts vectors in the XYZ reference frame to the DQZ reference frame. The primary value of the Park transform is to rotate the reference frame of a vector at an arbitrary frequency. The Park transform shifts the frequency spectrum of the signal such that the arbitrary frequency now appears as "dc" and the old dc appears as the negative of the arbitrary frequency.
Park trasformation is usually use to find the angle in three phase circuits for easy and feasible calculation, and generally used in motors and industrial machines of three phase system. Three phase voltages and angles of all phases can be calculated easily by Park Transformation.
If you have any query kindly tell me i will help you, bacause i am doing this work in smart and micro grids for three phase circuits. Thanks.
My impression is that it is always necessary to measure at least one other state from the machine in order to calculate the reference angle for the 3ph voltage vectors. The challenge is to find a state that is easy=cheap to measure.
Search "Rotor angle estimation" or "Rotor angle measurement"
In addition to the good answer above by Zia hammed, you could, in case you wish, implement an algorithm to obtain the sine of an angle, I recommend this: https://en.wikipedia.org/wiki/CORDIC
It is easy to implement and very accurate.
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