What is the difference between p-q and d-q reference frame in control of VSC?
Hi Mahmoud,
Haven't heard of a p-q frame before. I suppose you mean alpha-beta frame. Ok, so assuming it's a question on alpha-beta and d-q frames, here's my two bucks:
alpha-beta is a stationary frame. We know that the AC side voltage/current pulsates at 60Hz. Hence, if you describe your current phasor in alpha-beta coordinates, you'll notice that the alpha-beta components of your current is time-varying (even though you have a constant amplitude current). The current phasor is described by i = i_0 exp(j(wt+phi)), where i_alpha = i_0 cos(wt+phi) and i_beta = i_0 sin(wt+phi). If you are designing your controllers in alpha-beta coordinates, you must design a reference tracking controller at 60Hz.
On the other hand, d-q is a rotating coordinate system and rotates at w = 60Hz. Thus the quantities described in d-q coordinates are fixed (constant) for a constant amplitude signal. d-q gives you an advantage to design controllers for low-frequency tracking (since the quantities are described as DC quantities in this frame). However, this comes at a constant of synchronizing your d-q reference frame with the AC frequency. This requires additional techniques such as PLL.
Dear Mahmoud,
Please see a question posed through ResearchGate by Muhammed Fasil in Oct. 8, 2015 here is folowing link :
-Difference between application of alpha-beta and dq0 transformation ...
https://www.researchgate.net/.../Difference_between_application_o...
Also see a link and attached files in topics.
-Performance Analysis of a Voltage Source Converter (VSC) based ...
ljs.academicdirect.org/A15/033_046.htm
-VSC-Based HVDC Link - MATLAB & Simulink - MathWorks
https://www.mathworks.com › ... › Power Electronics
Best regards
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