Question:
This problem set requires MATLAB or other software.
- If any of the algorithms below reaches a point where it oscillates three times around the MPP (i.e., it crosses the MPP back and forth three times at the same points), you can stop the simulation and report your results.
Problem #1 - Incremental Conductance MPPT Method.
An ideal PV panel model can be used to understand the operation of the P&O method. Let the panel parameters be n=1, T = 300K, IL = 3A, and Io = 10-10A.
a) Plot the I-V and P-V curves of the panel.
b) Based on the I-V and P-V curves, what are the theoretical MPP, VMPP, and IMPP?
c) Using a step size of ΔV = 0.1V, and starting at VPV = 0V, implement the incremental conductance algorithm in a manner similar to the flowchart. Find the two values of VPV around which the oscillation occurs.
d) Repeat part (c) for a step ΔV = 0.01V.
Problem #2 - Conventional vs. Adaptive Par MPPT Method
Using the same PI/ panel described in problem #1:
a) Implement the P&O methbd with a step ΔV = 1V and starting at VpV = 0V. Find the two values of VP around which the oscillation occurs.
b) Adapting ΔV when the method starts to oscillate around the MPP provides less oscillations and less steady-state error of tracking the MPP. It is of interest to reduce ΔV by 50% of its previous value as follows: Every time the operating point crosses the MPP to its right side and returns to the left side, i.e., when the operating point is back on the left side, adaptation should take place by basically setting ΔV to 50% of its previous value. Once ΔV reaches 0.01 V or less. you do not have to reduce it any further. Find the two values of VPV around which the oscillation occurs.
Problem #3 - Dynamic Simulation of a Simple PV System
It is desired to build a dynamic simulation of a simple PV system where d 1W panel feeds a current sink through a boost converter. Assuming the boost convener is ideal, you do not have to use circuit blocks to simulate the system: the boost converter input-output voltage relationship is a simple equation dependent on the duty ratio D, and the current sink has a constant value of 0.2A. The PS' panel model from the paper referenced below should be used including the series resistance. Your system should implement the P&O algorithm to find the MPP.
a) Plot the panel P-V and I-V curves for T=301.18K and λ = G (irradiance) -1000 W/m2.
b) Plot the pane] P-V and I-V curvets. for T=301.18K and G = 500 W/m2.
c) Simulate the system in Simulink and find the MPP, VMPP, and IMPP for T = 301.18K and 01000 W/m2.You can stop the simulation after the system performs 10 oscillations around the MPP. Use a duty ratio step size of 1%. Show the stepping action in the PV panel voltage and power.
d) Simulate the system under the same conditions as part (c), but after the system oscillates 10 times around the MPP. drop G to 500 W/m2 and observe convergence to the new MPP. Find the new MPP, VMPP, and IMPP. Show the stepping action in the PV panel voltage and power before and after the change in G.