This document describes a constant power generation (CPG) control technique for grid-connected photovoltaic (PV) systems using a unit vector template (UVT) method. The CPG control modifies the maximum power point tracking (MPPT) algorithm to limit PV power output to the grid during periods of high solar generation. This helps reduce issues caused by high PV penetration without needing to expand transmission lines or add energy storage. The UVT method is used for synchronization and current control of the inverter. Simulation results are presented showing the CPG control limiting PV power fed to the grid while meeting load demand. In conclusion, the CPG-UVT control is an effective method to control active power flow from PV systems and

1. CPG-UVT BASED GRID CONNECTED PV SYSTEM
Author:
Ravindra B. Kuhada
Electrical Engineering Department
L. E. College, Morbi
International Conference on
Power, Control and Communication Infrastructure 2019
Program Session: Integration of Renewable Energy Sources / Electric Vehicles
Co-Author:
Prof. B. B. Parmar
Assistant Professor
Electrical Engineering Department
L. E. College, Morbi
Co-Author:
Dr. M. H. Pandya
Associate Professor
Electrical Engineering Department
L. E. College, Morbi
LUKHDHIRJI ENGINEERING COLLEGE, MORBI
Organized By
Institute of Infrastructure, Technology, Research And Management, Ahmedabad

2. Flow of Presentation
❖Photovoltaic Systems
❖Maximum Power Point Tracking
❖High PV penetration
❖Constant Power Generation
❖Unit Template Method
❖Simulation Work
❖References
CPG-UVT based Grid Connected PV System 2

3. PHOTOVOLTAIC SYSTEMS
Fig. Effect of Solar Irradiation on P-V curveFig. 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
CPG-UVT based Grid Connected PV System 3
➢ 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.

4. MAXIMUM POWER POINT TRACKING
CPG-UVT based Grid Connected PV System 4
Fig. Equivalent circuit
z=r+jx
Load
Z=R+jX
E i
Current
Voltage
Fig. I-V Curve of PV System
❖ Maximum Power Transfer Theorem
➢ It has a unique operating point where it
produce the maximum power output.
PMPP
Voltage (V)
Power(W)
Fig. Power curve for MPPT
➢ MPP is varied by duty cycle of DC-DC- converter.

5. 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
CPG-UVT based Grid Connected PV System 5
❖ What is High PV Penetration?

6. 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 ?
➢ 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.
CPG-UVT based Grid Connected PV System 6

7. 7
Power
Time
Plimit
Energy Yield
Ppv
PMPP
(Available Power)
t0 t1 t2 t3 t4
1 2 3 4 5
Fig. Operation region during a day
CPG-UVT based Grid Connected PV System
CONSTANT POWER GENERATION
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.

8. Constant Power Generation
Fig. Constant Power Generation Control Algorithm
CPG-UVT based Grid Connected PV System 8
Increase D
Decrease D
Voltage
Decrease D Increase D
MPPP
Power
Plimit
Ppv ={ PMPPT, when Ppv < Plimit
Plimit, when Ppv > Plimit

9. Control Scheme for Synchronization
➢ Unit Vector Template
Fig. Block diagram of Unit Template method
CPG-UVT based Grid Connected PV System 9
PI
regulator
Peak Value Estimator
(VM)
iS*
isa*
isb*
isc*
VDC
VDC*
va
vb
vc
+-
ub
uc
ua

10. ➢ Unit Vector Template
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)
CPG-UVT based Grid Connected PV System 10
Isa
*
Ia
+
_
NOT
PV
INVERTER
Isb
*
Ib
+
_
NOT
Isc
*
Ic
+
_
NOT
GATE PULSES
GATE PULSES
Actual Currents
Reference
Currents

11. 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
CPG-UVT based Grid Connected PV System 11
Load
Vnom=400 V
fnom =50 Hz
Load = 1 kW
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
Unit Vector Template

12. Change in Irradiance(W/m2) v/s Time (s)
Duty cycle v/s Time (s)
PV Power (W) vs Time (s)
CPG-UVT based Grid Connected PV System 12

13. Power at PCC (W) v/s Time (s)
Grid Power (W) v/s Time (s)
Load Power (W) v/s Time (s)CPG-UVT based Grid Connected PV System 13

14. Three phase PCC Voltages (V) v/s Time (s)
Three phase PCC Currents (A) v/s Time (s)
CPG-UVT based Grid Connected PV System 14

15. Conclusion
CPG-UVT based Grid Connected PV System 15
➢ An advanced control technique(CPG) is implemented to control active
power flow by limiting the maximum feed of PV power into the grid
which is used to reduce high PV penetration issue and Constant Power
Generation control is only modifying by MPPT algorithm.
➢ Because of CPG control, PV installation is not required to reduce and save
extra transmission/distribution line and energy storage devices.

16. REFERENCES
CPG-UVT based Grid Connected PV System 16
1) Ackermann, T., G. Andersson, and L. Söder. " Distributed generation: a definition," Electric Power System
Research, vol. 57, pp: 195-204." (2001).
2) Renewable Energy industry in India, https://www.ibef.org/industry/renewable-energy.aspx.
3) R. Abdul-Kalaam, S. Muyeen, and A. Al-Durra, "Review of Maximum Power Point Tracking Techniques for
Photovoltaic System," Global Journal of Control Engineering and Technology, vol. 2, pp. 8-18, 2016.
4) M. A. G. De Brito, L. Galotto, L. P. Sampaio, G. d. A. e Melo, and C. A. Canesin, "Evaluation of the main
MPPT techniques for photovoltaic applications," IEEE transactions on industrial electronics, vol. 60, pp.
1156-1167, 2013.
5) Yang, Yongheng, Frede Blaabjerg, and Huai Wang. "Constant power generation of photovoltaic systems
considering the distributed grid capacity." In Applied Power Electronics Conference and Exposition (APEC),
2014 Twenty-Ninth Annual IEEE, pp. 379-385. IEEE, 2014.
6) Sangwongwanich, Ariya, Yongheng Yang, and Frede Blaabjerg. "High-performance constant power
generation in grid-connected PV systems." IEEE transactions on Power Electronics 31, no. 3 (2016): 1822-
1825.

17. REFERENCES
CPG-UVT based Grid Connected PV System 17
7) 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 54, no. 1 (2018): 447-457.
8) Sangwongwanich, Ariya, Yongheng Yang, and Frede Blaabjerg. "Sensorless reserved power control strategy
for two-stage grid-connected photovoltaic systems." In Power Electronics for Distributed Generation
Systems (PEDG), 2016 IEEE 7th International Symposium on, pp. 1-8. IEEE, 2016.
9) Singh, Bhim, Ambrish Chandra, and Kamal Al-Haddad. Power quality: problems and mitigation techniques.
John Wiley & Sons, 2014.
10) 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.
11) Patel, Ashish, and Pradyumn Chaturvedi. "Performance of SRF-UVTG based UPQC DG for integration of
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18. CPG-UVT based Grid Connected PV System 18
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