sinewave with zero cross detection track

[danilorj]

Hey guys

do you know anyway of tracking the blue waveform as it is shown in the picture below? I am using a Proportional Ressonant controller with harmonic controller (PRHC) but the problem is that it only tracks a sinusoidal waveform as can be seen by the green waveform shown in the picture, the zero cross interval it does not track. Is there anyway of modifying this PR controller so it can track this waveform or do I have to change all my controller for this?

 

[D.A.(Tony)Stewart]

It depends on what design method you desire, track the middle of the zero crossing deadband or the middle of the asymmetric wave or null DC.

A better question has more details.

 

[danilorj]

Track the middle of the zero cross deadband.

 

[D.A.(Tony)Stewart]

Well the deadband middle is symmetrical but offset in phase so the negative peak is also offset , resulting in DC offset.

details, details missing

 

[danilorj]

but is the PR controller able to track this signal, or do I have to look for an other one?

 

[D.A.(Tony)Stewart]

I dont know, you have not presented any problem yet. So far it is tracking. Hard to say with so few details.

 

[danilorj]

Ok. What I am trying to implement is a active frequency drift method with pulsation chopping factor. In literature is known as AFDPCF. What I am trying to implement is anti-islanding method for a PV distributed source using this. So far so good.
The picture below shows the block diagram.



Look at ig*, this is the current generated by the control using the instantaneous power theory. And the other ig is the inverter current that will track ig*. As you may know the AFDPCF method imposes a perturbation in this ig* current using pulses of chopping fraction, this is what I sent in my first picture. So, to make this useful, the ig current read from the inverter must track this ig* with this perturbation so that when an islanding occurs the frequency of the inverter current is out of the range of the non-detection zone (NDZ). Thus, OFR/UFR can be triggered.