Comparision of Incremental Conductance with Fuzzy Controller -By ASSR MURTHY

1. COMPARISON OF INCREMENTAL CONDUCTANCE
WITH FUZZY CONTROLLER FOR A PLL LESS
SCHEME FOR GRID INTERFACED PV SYSTEM
By
1. A.Bala Raja Ram, Assistant Professor, Department of EEE, REC(A).
2. Dr.T.Srinivas Sirish, Professor, Department of EEE, GVPCOE(A).
3. M.V.Suresh Kumar, Assistant Professor, Department of EEE, REC(A).
4. A.S.S.R.Muthy, B.tech 3rd year, Department of EEE, REC(A).

2. ACRONYMS
PLL……………...Phase Locked Loop
INC……………….Incremental Conductance
FLC…………….. Fuzzy Logic Controller
MPPT…………….Maximum Power Point Tracking
THD………………Total Harmonic Distortion

3. SYSTEM CONFIGURATION
Grid Voltage and Frequency 230V and 50Hz
Kp and Ki 0.5 and 2.5
Interfacing inductor and ripple filter Li = 6mH, R=5Ω, 1W and C=5µF, 250V
DC-link capacitor 2500µF
Current controlled thresholds for switching ±0.2A
PV array open circuit voltage and short circuit
current
300V and 15A

4. CONTENTS
1) Abstract
2) Motivation
3) Methodology
4) Technique to Eliminate PLL along with its implementation
5) Simulation results
6) Conclusion
7) References

5. ABSTRACT
In modern day’s, necessity of electrical power increased rapid increase in industrial growth.
With this, dependence on conventional energy increased and the depletion of its sources
started, and here renewable energy sources like solar, wind and tidal energy started to act as
alternate energy source and playing a crucial role among which solar is quiet important. The
paper serves two purposes such as extraction of maximum power from a PV. Secondly,
designing a notch filter scheme to eliminate Phase Locked Loop. This filter extracts the real
component of load current which is previously done by PLL. As Phase Locked Loop is
eliminated, system dependence on PI controller tuning decreases and there by dynamic
response and robust nature of system increases. Along with this a fuzzy logic based
Maximum Power Point Tracker (MPPT) is proposed and compared with incremental
conductance type power point tracker.

6. MOTIVATION
• The dependence on PLL for reference current extraction makes the control dependent on
proportional-integral (PI) controller tuning, which reduces the robustness of the system and
deteriorates the dynamic response.
• So a filtering control algorithm is designed to facilitate extraction of the real component of load
current which improves the dynamic response and makes system quite robust also to decrease Total
Harmonic Distortion(THD)
• To compare the incremental Conductance MPPT with Fuzzy Lozic based MPPT.

7. Double-stage single-phase grid connected solar PV system
7
Fig.1 Double stage single phase grid connected solar PV system

8. • The basic concept of Incremental conductance on a PV curve of a solar module is shown in figure. The slope
of the P-V module power curve is zero at The MPP, increasing on the left of the MPP and decreasing on the
Right hand side of the MPP.
P=I*V
𝑑𝑝
𝑑𝑣
= 0 at MPP --------(1)
𝑑𝑝
𝑑𝑣
>0 left of MPP --------(2)
𝑑𝑝
𝑑𝑣
< 0 right of MPP --------(3)
From (1)
𝑑𝑝
𝑑𝑣
= I+V*
𝑑𝑖
𝑑𝑣
= 0 ------(4)
𝑑𝑝
𝑑𝑣
=
−𝑉
𝐼
--------(5) Fig.2 Slope of Incremental Conductance
INCREMENTAL CONDUCTANCE

9. Contd…..
Fig. 3 Flow chart of Incremental Conductance MPPT

10. 10
CONTROL ALGORITHM OF VSC
Fig.4 Control Algorithm of VSC
METHODOLOGY

11. Block diagram of the filtering scheme
Fig5 Block diagram of filter scheme
IMPLEMENTATION AND DESIGN OF THE FILTERING SCHEME
WHICH REPLACES PLL

12. Fig.6 Simulation diagram of single-phase grid connected solar PV system

13. Fig.7 Simulation diagram of boost converter

14. Fig.8 Simulation diagram of control algorithm of VSC

15. Fig.9 simulation diagram of block diagram of filter(PLL less)scheme

16. Fig.10 THD of current injected into the grid
4.23%

17. • One of main disadvantages of Incremental Conductance is
that during rapid irradiance changes, tracking of maximum
power point takes more time and to overcome this Fuzzy
Logic Controller is proposed.
• Fuzzy Logic Controller (FLC) is one branch of the
intelligent control in which the control of FLC is achieved
by adopting human behavior.
• Main advantages of FLC is that it does not require any
complex mathematical calculations and can work using
imprecise input.
• FLC comprises fuzzification process, inference system
rule, and de-fuzzification, as shown in Fig.13
Fig.11 Fuzzy Logic Controller block diagram
FUZZY LOGIC CONTROLLER

18. • While fuzzification is processed, the numerical input
variable is converted into a fuzzy input through the
membership function
• The input variable of fuzzy logic (FL) control includes
error (E) and change of error (dE).
• These variable are processed through inference system and
through some rules which is shown in Fig.
• These condition are done to generate the output of FL.
• The next process is de-fuzzification.
• Here, the output of fuzzy is change in duty cycle (dD).
While de-fuzzification is processed, fuzzy output will be
converted into a numerical output
Table.1 Rules of Fuzzy Logic Controller

19. Fig. 12 Membership functions of Error(E)
Fig.13 Membership functions of Change in Error(dE)

20. Fig. 14 Membership functions of duty cycle(D)

21. Fig.15 THD of current injected into the grid
Simulation results with Fuzzy Logic based MPPT
2.90%

22. Figure below shows the power that is injected into the grid that is the reason why it is in the negative phase
Fig.16 Power that is injected into the grid

23. %THD VALUES WITH
INCREMENTAL CONDUCTANCE TYPE MPPT
%THD VALUES WITH
FUZZY LOGIC CONTROLLER TYPE MPPT
Current
Injected
4.23% 2.90%
Table No.2 Comparison of THD values of grid current and converter current
• By comparing the above table, decrease in ripples and Total Harmonic Distortion can
be seen by using Fuzzy Logic Controller over Incremental conductance Maximum
Power Point Tracking technique.

24. CONCLUSION
• A filter scheme is designed and is used to extract the real component of load current
eliminating the services of PLL.
• Power loss caused due to slow response of system due to usage of Incremental
Conductance can be overcome by using Fuzzy Logic Controller MPPT.

25. REFERENCES
• Sagar Deo, Chinmay Jain, Member, IEEE, and Bhim Singh, Fellow, IEEE “ A
PLL-Less Scheme for Single-Phase Grid Interfaced Load Compensating Solar
PV Generation System” ieee transactions on industrial informatics, vol. 11, no.
3, june 2015
• N. Femia, G. Petrone, G. Spagnuolo, andM. Vitelli, “Optimization of perturb
and observe maximum power point tracking method,” IEEE Trans. Power
Electron., vol. 20, no. 4, pp. 963–973, Jul. 2005.
• Y. Chen and K. Smedley, “Three-phase boost-type grid-connected inverter,”
IEEE Trans. Power Electron., vol. 23, no. 5, pp. 2301–2309, Sep. 2008.
• S. B. Kjaer, J. K. Pedersen, and F. Blaabjerg, “A review of single-phase grid-
connected inverters for photovoltaic modules,” IEEE Trans. Ind. Appl., vol. 41,
no. 5, pp. 1292–1306, Sep./Oct. 2005. 25