What is the difference between phasor measurement unit (PMU) blocks in Simulink?

Hello,

I would like to know the following regarding the PMU functionality (IEEE Std C37.118) recently implemented in MATLAB/Simulink.

1. What is the basic algorithm inside this block - https://www.mathworks.com/help/physmod/sps/powersys/ref/pmupllbasedpositivesequence.html?s_tid=srchtitle (PMU (PLL-Based, Positive-Sequence))? Does it follow the P or M Class filter paradigm defined in C37.118?
2. There seems to be one other PMU block introduced in R2020a: https://www.mathworks.com/help/releases/R2020a/physmod/sps/ref/phasormeasurementunitpmuthreephase.html (Phasor Measurement Unit (PMU, Three-Phase)). I cannot find any information on this block's algorithm either.

Generally, both of them only output positive sequence phasors.

Could anyone please tell me which one is preferred?

Thank you.

Answer 1

[Joel Van Sickel]

Hello Igor,

if you want more specifics on the implementation of the algorithm, much of it is availabling from within Simulink. If you right click the block, you will see a menu item labelled "mask". This will have an expanding menu that has the option to look under the mask. Then you can view exactly how the algorithm was implemented. Alternatively, you can use the shorcut ctrl + "u".

Regards,

Joel

[Igor]

Thank you, Joel.

Yes, I am aware of this opportunity.

However, I suspect none of these blocks strictly follows the IEEE C37.118 standard (in terms of the M and P class separation, for instance).

In our simulations, the second block did not seem to work at all. We tried it out on two different power system models. Actually, four phasor computation options were considered: the two PMU-like blocks mentioned above along with both "Phasor" and "Discrete phasor" in PowerGUI. It turned out that "Discrete phasor" produced a good enough result, while the three other options failed. The PMU (PLL-Based, Positive-Sequence) block (the one introduced in 2017) is ok but takes a long time to "settle" after a disturbance.