This document discusses control and operation of grid-connected photovoltaic systems. It covers microgrid configurations including DC-coupled, AC-coupled, and hybrid-coupled systems. It also discusses power conditioning units like inverters, and their topologies such as centralized, string, and multi-string inverters. Finally, it summarizes standards and regulations for connecting photovoltaic systems to the electric grid, including IEEE 1547a and guidelines from the Central Electricity Authority of India.

1. Control and Operation
of Grid-Connected Photovoltaic Systems
Presented by
Dr. P. K. Sahu
(Assoccciate Professor)
School of Electrical Engg., KIIT Deemed to be University,
Bhubaneswar
1

2. • Introduction to Microgrid
• Power conditioning Units
• Standards and Regulation
• DC-DC Power processing Stages
• DC-AC Power Processing Stages
• Current control Techniques
• Conclusion
Contents

3. Microgrid Configuration
1

4. Hybrid Energy System Configuration
17
Hybrid Renewable
Energy System
DC-Coupled Systems AC-Coupled Systems
Hybrid-Coupled
Systems

5. DC-Coupled Systems
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• DC-DC power processing stage may or may not required
• Each string has its own inverter
• Individual MPPT for each string
• Power processing part converts ac- dc

6. AC-Coupled Systems
19

7. Hybrid-Coupled Systems
20

8. • PV array
o A number of PV modules
o Cables and protection devices
o Structure (to support and to expose the module for maximum light
capture)
• Power conditioning units
o Stand-alone plants
o Matches the array output to the load requirements
o Manages the storage system
o Grid-connected plants
o Convert the dc array output to standard ac power
o Fit the PV array output to the grid
o Control the quality of the energy supplied to the grid
(distortion and power factor correction)
PV Power Systems Components
2
Chapter-1

9. • Welll suited for
o Remote site
o Reliability is paramount (signaling)
o Simplicity required (remote houses, schools)
o Transportability (navigation laps, laptop computers)
o Intermittent power acceptable (fans, pumps)
Standalone PV System
3
Chapter-1

10. Grid-Connected PV System
• System that is connected to a large independent grid (typically
public) and feeds power into that grid
• The electricity demand is met by the system and the excess is
fed directly to the grid
• Inverter is required to convert dc electricity to ac
• Used in high voltage electricity generation – 600-1000V
(buildings, residential rooftops, solar farms)
4
Chapter-1

11. Power Conditioning Units
• Essential part for the integration of DG units to achieve high
efficiency and performance in power systems;
• Two main tasks:
o dc to ac conversion
o voltage boost if necessary
Topologies of PV Inverters
• Centralized Inverters
• String Inverters
• Multi-string Inverters
• AC modules & AC cell technology
5
Chapter-1

12. Centralized Inverters
• Application in three-phase PV systems
• Power ranging from 100 MW
• Connection of the modules to a dc bus
• Voltage high enough to avoid the use of transformers or boost
converters
• High power losses
6
Chapter-1

13. String Inverters
• Small domestic applications
• Power ranging from 0.5kW to 10 kW
• Reduced version of centralized inverter
• Very flexible configuration
• increases the overall efficiency
7
Chapter-1

14. Multi-String Inverters
• Each PV module is interfaced by its own dc/dc converter
and then connected to an inverter
• Further development of the string inverter
• Further enlargements of the PV plant are easily done because
of the
dc/dc converters
• Reduced power losses
• Lack of redundancy and scalability for grid connection 8
Chapter-1

15. AC Modules
• Complex topology
• Power ranging from 150-300W
• Small-scale residential applications
• DC/AC inverter modules
• Each module unit has independent functions
• High efficiency and flexible design
9
Chapter-1

16. Existing Inverter Topologies in GPV System
Based on power processing stages
• Single-stage inverter
• Dual stage inverter
• Three stage inverter
Power Decoupling
Power decoupling is generally obtained by using an electrolytic capacitor.
PV
g c c
2
P
C
V V



10
Chapter-1

17. Types of Grid Interfaces
Inverters operating in CSI
Standard full-bridge VSI
Half-bridge diode-clamped VSI
11
Chapter-1

18. Challenges in Renewable Integration
• Intermittent generation dependent on season, weather and other
parameters-Power balancing
• Voltage and frequency control; most of these sources do not have
reactive power generation.
• The sudden generation loss can lead to transient angle and voltage
instability.
• Stability issue more challenging due to inertialess generation,e.g.solar.
• Power Quality issues-Harmonics, flicker, under voltage ride through
capability
• Power management and Maximum power point tracking.
12

19. Grid Standard
• Challenges on Grid due to increased
penetration of solar PV
• Frequency regulation
• Voltage regulation
• Peak load / uncertainties – Load and Source
• LVRT / HVRT
• IEEE Std 1547a™-2014 (Amendment to IEEE Std 1547™-2003)
• Central Electricity Authority – Technical Standard for Connectivity
to Grid
• Regulations 2007 and Amendment in 2013
• Draft amendments in 2016 13
Chapter-1

20. IEEE 1547a - 2014
• IEEE Standard for Interconnecting Distributed Resources with Electric
Power Systems
• IEEE Std 1547a™-2014 (Amendment to IEEE Std 1547™-2003)
• Major Changes:
• EPS – Electric Power System; DR – Distributed Resources
14

21. IEEE 1547a - 2014
15

22. IEEE 1547a - 2014
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23. IEEE 1547a - 2014
17

24. IEEE 1547a - 2014
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25. CEA – Technical Standards for Connectivity to Grid
• Central Electricity Authority – Technical Standard for Connectivity to
Grid
• Regulations 2007 and Amendment in 2013
• Proposed draft amendments in 2016
19

26. CEA – Technical Standards for Connectivity to Grid
1

27. CEA – Technical Standards for Connectivity to Grid
1

28. CEA – Technical Standards for Connectivity to Grid
1

29. CEA – Technical Standards for Connectivity to Grid
1