This document discusses dual mode control of a grid-connected photovoltaic system using maximum power point tracking (MPPT) and constant power generation (CPG) control. It first introduces distributed generation and photovoltaic systems, and describes how MPPT algorithms like perturb and observe are used to extract maximum power from PV panels. For high PV penetration scenarios where PV generation exceeds load demand, CPG control modifies the MPPT algorithm to limit power output to a set point. Simulation results show the system operating in MPPT mode and CPG mode under varying irradiance conditions, and successfully regulating power fed into the grid.

1. DUAL MODE CONTROL OF
GRID CONNECTED PHOTOVOLTAIC SYSTEM
Prepared By:
Ravindra B. Kuhada
M.E. 3rd (160310707005)
Electrical Engineering Department
L. E. College, Morbi
LUKHDHIRJI ENGINEERING COLLEGE,
MORBI
Theme of Title: Distributed Generation
Guided By:
Prof. B. B. Parmar
Assistant Professor
Electrical Engineering Department
L. E. College, Morbi
Co-Guided By:
Dr. M. H. Pandya
Associate Professor
Electrical Engineering Department
L. E. College, Morbi
L. E. COLLEGE, MORBI 1

2. Flow of Presentation
❖Distributed Generation
❖Photovoltaic Systems
❖Maximum Power Point Tracking
❖High PV penetration
❖Constant Power Generation
❖Simulation Work
❖References
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3. DISTRIBUTED GENERATION
➢ It is small scale generation typically ranging from 3KW to 10MW installed on a
power system close to the end user to provide alternating power supply.
➢ Renewable energy sources are inexhaustible and are renewed by nature itself.
➢ Photovoltaic (PV) power generation is one of the most promising renewable energy
technologies.
Distributed
Generation
System
Reliability
Ancillary
services
Lower
Capital
cost
Reduce
pressure
Produce
zero
pollutant
Power
Reliability
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4. Why Solar PV ?
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➢ Pollution free, no fossil fuels, no moving part.
➢ Directly converted into electrical energy by solar PV modules.
Fig. 1 Photovoltaic system

5. PHOTOVOLTAIC SYSTEMS
Fig.3 Effect of Solar Irradiation on P-V curveFig.2 Effect of Temperature on P-V curve
G=1000W/m2
G=500W/m2
G=200W/m2
T=00C
T=250C
T=750C
VoltageVoltage
Power
Power
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➢ Non linear characteristics (environmental condition-irradiation level and
temperature)
➢ PV output power is inversely proportional to the Temperature and Directly
proportional to the Solar Irradiation.

6. Modelling of a Photovoltaic System
I = IL – ID –
𝑉 𝐷
𝑅 𝑠ℎ
ID = Io (𝑒 ൗ
𝑉 𝐷
𝑎𝑉 𝑡 – 1)
Vt = Τ𝑁𝑠 𝑘𝑇 𝑞
Where, IL = Current generated by Photons
Rs = Series resistances of the module
Rsh = Parallel resistances of the module
ID =diode current
VD = diode voltage
a = ideality factor,
Io = reverse saturation current,
Vt = thermal voltage
Ns = no. of cells in series,
k = Boltzmann constant,
T = cell temperature
q = electron charge
Fig. 3 Solar PV Cell

7. MAXIMUM POWER POINT TRACKING[2]
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Fig.6 Equivalent circuit
z=r+jx
Load
Z=R+jX
E i
Current
Voltage
Fig.5 I-V Curve of PV System
❖ Maximum Power Transfer Theorem[1]
➢ It has a unique operating point where it
produce the maximum power output.
PMPP
Voltage (V)
Power(W)
Fig.4 Power curve for MPPT
➢ MPP is varied by duty cycle of DC-DC- converter.
2. Review of Maximum Power Point Tracking Techniques for Photovoltaic System,(global journal)2016

8. PERTURB & OBSERVE METHOD[2]
START
MEASURE V(k), I(k)
P(m)=V(k)*I(k)
P(k)>P(k-1)
V(k)>V(k-1) V(k)>V(k-1)
D=D- D D=D+ D D=D+ D D=D- D
YES
YES YES
NO
NO NO
RETURN
P(K)-P(k-1)=0
NO
YES
Fig.7 - MPPT-P&O ALGORITHM
➢Simple, accurate and very easy to
implement.
➢If in duty cycle, the step change is
large, then it has high tracking speed.
➢Step change in duty cycle is small, it
gives high accuracy result.
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9. HIGH PV PENETRATION
➢ Exceeding of PV generation from Grid power transfer capacity by
such an amount as it adversely affect the grid performance.
Sr.
No.
Power Generation Vs
Load Demand
Load Supply
1 Ppv = Pload By only PV generation
2 Ppv < Pload By Both PV and Grid
3 Ppv > Pload
By PV generation and excess power
feed into grid
CASES
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❖ What is High PV Penetration?

10. PROBLEM DEFINITION
➢ When load demand is more than PV generation, then to extract
maximum power from PV panel MPPT is used.
➢ But when the PV generation is more than load demand, DSO has to
expand transmission and distribution line or energy storage device is
required.
➢ Expand to transmission/ distribution line or
➢ Reduce PV installation
Is this a viable Option ? - No
THEN WHAT IS THE BEST ATLERNATIVE ?
➢ In NZ, the typical 4kW solar panel system will generate around 140%
of a Home’s average daily power needs in Summer, but only 30% in
winter. L. E. COLLEGE, MORBI 10

11. 11
Power
Time
Plimit
Energy Yield
Ppv
PMPP
(Available Power)
t0 t1 t2 t3 t4
1 2 3 4 5
Fig. 8 Operation region during a day
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CONSTANT POWER GENERATION[4]
Ppv ={
PMPPT, when Ppv < Plimit
Plimit, when Ppv > Plimit
➢ The actual power production can be
expressed as:
➢ CPG control is by modifying the MPPT
algorithm at the PV inverter level.
4. Constant power generation of photovoltaic systems considering the distributed grid capacity(APEC),2014

12. Constant Power Generation[4]
Fig. 9 Constant Power Generation Control Algorithm [3]
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Increase D
Decrease D
Voltage
Decrease D Increase D
MPPP
Power
Plimit
Ppv ={ PMPPT, when Ppv < Plimit
Plimit, when Ppv > Plimit

13. START
MEASURE V(k), I(k) &
SET Plimit
P(m)=V(k)*I(k)
P(k)>Plimit
P(k)>P(k-1) P(k)>P(k-1)
V(k)>V(k-1) V(k)>V(k-1) V(k)>V(k-1)V(k)>V(k-1)
D=D+ D D=D- D D=D- D D=D+ D D=D+ D D=D- D D=D- D D=D+ D
YES
YES
YES YES
YES
YES
NO
NO
NO NO NO
NO
NO
RETURN
Flow chart of Constant Power Generation[4]
Fig. 10 Flow chart of CPG, with P&O algorithm
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MPPT CPG
D ↑ D ↓
Voltage
MPPP
Power
Plimit
D ↓ D ↑

14. MPPT/CPG
ControlPlimit
Inverter
Control
Load
°C
PV Panels
Cpv
L
Boost
Converter
ipv vpv PWMb
Cdc
vdc
vdc
Full
-
Bridge
Inverter
LCL filter
PWMinv
Grid
Linv Lg
Cf
vg
ig
Zg
*
LINE DIAGRAM OF GRID CONNECTED PV SYSTEM
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Load
Vnom=400 V
fnom =50 Hz
L: 7.74 mH
C: 1.28 μF
L: 4.85 mHC=10 mFC=5 mF L = 7.056 mH
Series = 6
Parallel = 2
Pmax =3357.912 W
SPWM/Unit Template
Carrier Wav freq = 80kHz
Ref. signal freq = 50 Hz
Fig. 11 line diagram of grid connected PV system

15. Control Scheme for Synchronization
➢ Unit Template[8,9]
Fig. 12 Block diagram of Unit Template method
Fig.L. E. College, Morbi 15
PI
regulator
Peak Value Estimator
(VM)
iS*
isa*
isb*
isc*
VDC
VDC*
va
vb
vc
+-
ub
uc
ua

16. ➢ Unit Template[7]
Iloss = VDCref - VDC
Peak Value estimator VM = [ Τ2
3 (Vsa
2 + Vsb
2 + Vsc
2)] Τ1
2
Unit vector of voltage US = Τ𝑉 𝑆
𝑉 𝑀
Reference Current = IM x US
(1)
(2)
(3)
(4)
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17. Simulation Work
Fig. 13 MATLAB/Simulink diagram for varying irradiance and constant temperature for MPPT-CPG modeL. E. College, Morbi 17

18. Fig. 15 Irradiance of PV Vs TimeL. E. College, Morbi 18
Fig. 14 Duty cycle Vs Time

19. MPPT mode
200 X 8 = 1600
CPG mode
125 X 16.1 = 2012.5 Fig. 17 PV Voltage Vs Time
Fig. 16 PV Current Vs Time
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3 kW supplied by PV and 2 kW controlled by CPG
1.6 kW supplied by PV and 1.6 kW controlled by MPPT
Fig. 18 PV Output Power Vs Time

20. Fig. 20 Inv output Voltage Vs Time
Fig. 19 Inv output Current Vs Time
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21. Fig. 21 MATLAB/Simulink diagram for Constant Irradiance and constant temp for MPPT mode with grid connected PV system
Simulation Diagram for Grid connected PV system
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22. Fig. 22 MATLAB/Simulink diagram for unit template method and hysteresis band controller
Simulation Diagram of Unit template method
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23. L. E. College, Morbi 23
Fig. 24 PV Power Vs Time
Fig. 23 Duty cycle Vs Time

24. L. E. College, Morbi 24
Fig. 25 Three phase PCC Voltages (V) v/s Time (s)
Fig. 26 Three phase PCC Currents (A) v/s Time (s)

25. L. E. College, Morbi 25
Fig.27 Power at PCC (W) v/s Time (s)
Fig. 28 Grid Power (W) v/s Time (s)
Fig. 29 Load Power (W) v/s Time (s)

26. Fig. 30 MATLAB/Simulink diagram for Varying Irradiance and constant temp for CPG algorithm with grid connected PV system
Simulation Diagram for Grid connected PV system
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27. Fig. 31 MATLAB/Simulink diagram for unit template method and hysteresis band controller
Simulation Diagram of Unit template method
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28. Fig. 32 Change in Irradiance(W/m2) v/s Time (s)
Fig. 33 Duty cycle v/s Time (s)
Fig. 34 PV Power (W) vs Time (s)

29. Fig. 35 Power at PCC (W) v/s Time (s)
Fig. 36 Grid Power (W) v/s Time (s)
Fig. 37 Load Power (W) v/s Time (s)

30. Fig. 38 Three phase PCC Voltages (V) v/s Time (s)
Fig. 39 Three phase PCC Currents (A) v/s Time (s)

31. REFERENCES
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1) Electrical Circuit Theory and Technology(3rd) by John Bird.
2) Rahila Abdul-Kalaam, S.M. Muyeen and Ahmed Al-Durra, “Review of Maximum Power Point
Tracking Techniques for Photovoltaic System” in Global Journal of Control Engineering and
Technology, 2016, 2, 8-18
3) Y. Yang, F. Blaabjerg, H. Wang, and M. G. Simoes, "Power control flexibilities for grid-
connected multi-functional photovoltaic inverters," IET Renewable Power Generation, vol. 10,
pp. 504-513, 2016.
4) Y. Yang, F. Blaabjerg, and H. Wang, "Constant power generation of photovoltaic systems
considering the distributed grid capacity," in 2014 IEEE Applied Power Electronics Conference
and Exposition-APEC 2014, 2014, pp. 379-385.
5) Sangwongwanich, Ariya, Yongheng Yang, Frede Blaabjerg, and Huai Wang. "Benchmarking of
constant power generation strategies for single-phase grid-connected photovoltaic systems."
IEEE Transactions on Industry Applications (2017).

32. L. E. COLLEGE, MORBI 32
6) A. Sangwongwanich, Y. Yang, and F. Blaabjerg, "High-performance constant power generation
in grid-connected PV systems," IEEE Transactions on Power Electronics, vol. 31, pp. 1822-1825,
2016.
7) B. Singh, A. Chandra, and K. Al-Haddad, Power quality: problems and mitigation techniques:
John Wiley & Sons, 2014.
8) A. Jeraldine viji*, T. Aruldoss Albert Victoire** A comparative study of 3Φ SAPF with Different
reference current generation, CEAI, Vol.16, No.4 pp. 99-106, 2014.
9) D.Prathyusha , P.Venkatesh , “Power Quality improvement of a three phase four wire system
using UPQC”, International Research Journal of Engineering and Technology (IRJET), Volume:
02 Issue: 04 | July-2015
REFERENCES

33. L. E. COLLEGE, MORBI 33
THANK YOU

34. L. E. College, Morbi 34
Fig. phase Inverter

35. L. E. College, Morbi 35
Fig. SPWM technique

36. L. E. College, Morbi 36
Voltage
Power
P(k-1)
P(k)
V(k) V(k-1)V(k)V(k-1)
D ↑ D ↓
MPPT mode
Voltage
Power
P(k)
P(k-1)
D ↑
D ↓
V(k)V(k-1)V(k) V(k-1)
Plimit
Plimit

37. L. E. College, Morbi 37
CPG mode
Voltage
Power
P(k-1)
P(k)
V(k) V(k-1)V(k)V(k-1)
D ↑D ↓
Voltage
Power
D ↑
D ↓
V(k)V(k-1)V(k) V(k-1)
P(k-1)
P(k)
PlimitPlimit
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