i am building a photvoltaic maximum power tracking algorithm i have oscillations on the controller output duty cycle but in the same time i have a stable power response canany one suggest a solution for the controller output oscillations
Dear Ayman
do you have a load connected to your system ? and what type of load ? these can be the cause for resonances. do you know the frequency of the oscillations ? If you say the output is stable, do you mean DC output ? Let us know then we can see if we can assist.
i mean the output power has low oscillations despite that the duty cycle has high oscillations it changes between .5 and .6 it is not stable i implemented a Perturb and observe control algorithm the duty cycle moves around .01 + or - the duty cycle
i am using a resistance to model the load i don't know the frequency of the oscillations
Dear Ayman
thank you for response, sounds very interesting and I am interested in assisting if I can. Is your control system not perhaps a pulse width modulation PWM duty cycle control, ie do the oscillations look like square waves perhaps ?
If so, the PWM signal is just a fancy way to control the voltage level of the control signal of the solar MPPT tracker up or down. To over simplify, the more oscillations (higher frequency) the higher the avarage voltage level of the control signal. The less oscilations (the lower the frequency), the lover the average voltage level of the control signal.
This Researchgate discussion on Perturb and Observe control may be interesting also:
https://www.researchgate.net/post/what_are_Advantages_Disadvantages_of_Perturb_and_Observe_MPPT_technique
let us know if this is the case in your electronics or solar tracker micro-processor control.
Regards, Gerro
Dear Ayman... When the perturbation value of the P&O MPPT controller is +/-0.01 then, the duty cycle oscillation also be 0.01 say 0.5 to 0.51/0.49. The controller must give you the duty cycle with +/- 0.01 after reaching the steady state. As I understand, the PWM controller comes after the duty cycle. i.e, the duty cycle is the input to the PWM control for pulse generation.. The model you are talking here is Simulation model or hardware??
Hello,
I though the oscillation caused by the step of P&O MPPT algorithm.
It's normal, the oscillation is depending on two factors: the first factor is sampling frequency and the second factor is the step size of MPPT control.
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