1. Interconnection of AES With The Grid
And
Its Considerations
Emad-Eldin Mohamed-Ahmed
Supervisor: Dr. Tan Chee Wei

2. AES: Alternative Energy Source EPS: Electrical Power Supply (Grid)
Abbreviations
AES: Alternative Energy Source
EPS: Electrical Power Supply (Grid)
PCC: Point of Common Coupling

3. Islanding
AES continues to energize a portion of the area EPS that has been isolated fro the rest of the area EPS
Up stream Breaker
Fuse
Automatic Sectionalizing Switch
Manual

4. Islanding

5. Interconnection of AES with EPS
The interconnection system is the means by which an AES unit connects electrically with the outside Electric Power System (EPS). It can also provide monitoring, control, metering, and dispatch of the AES unit.

6. Power conversion and conditioning Protection functions

7. Functions Autonomous and semiautonomous functions and operations
AES and load controls.
Ancillary services.
voltage support, regulation, operating reserve, and backup supply.
Communications.
Communications allow the AES and local loads to interact and operate as part of a larger network of power systems or micro-grids.
Metering. The metering function allows billing for AES energy production and local loads
Net Metering
FiT

8. Interconnection Technologies
Synchronous Interconnection
Induction Interconnection
Inverter Interconnection

9. Standards And Codes
IEEE 1547
NFPA 70
UL 1741, 1008, 2200

10. Considerations of Interconnection
Voltage Regulation
Maintain approximately constant voltage to users
Machines Efficiency.
Integration with Area EPS Grounding
It is defined by its isolation or lack of isolation from adjacent grounding systems.

11. Considerations of Interconnection
Synchronization
To synchronize an AES with an area EPS.
Isolation
A readily accessible, lockable, visible-break isolation should be located between the area EPS and the AES.
These switches provide visible isolation points to allow for safe work practices.
Disconnect switches should be strategically installed to permit disconnection from all sources.

12. Considerations of Interconnection
Response to Voltage Disturbance

13. Considerations of Interconnection
Response to Frequency Disturbance
When generation is matched inadequately with system load, the area EPS frequency will decline.
System operator seeks to match load quickly with available generation.
Under-frequency relays are installed on the distribution system to shed load automatically to stabilize operations.

14. Considerations of Interconnection
Disconnection for Faults
The AES should have, as a minimum, an interrupting device that is:
Of sufficient capacity to interrupt maximum available fault current at its location
Sized to meet all applicable ANSI and IEEE standards
Installed to meet all local, state, and federal codes

15. Considerations of Interconnection
Loss of Synchronism
Result of islanding
Transient during reclosing
Phase angle separation magnitude across the isolation

16. Considerations of Interconnection
Feeder Reclosing Coordination
The AES is designed to cease energizing the area EPS before the reclosing event.
The Re-closer is designed to delay reclosing event until AES has ceased energizing the area EPS
The AES is controlled to ensure that the voltage phase-angle separation magnitude across the islation is less than one fourth of a cycle when the reclosing event occurs
The The Re-closer is controlled to ensure that the voltage phase-angle separation magnitude across the islation is less than one fourth of a cycle when the reclosing event occurs
The AES capacity is less than 33% of the minimum load in the feeder.

17. Considerations of Interconnection
DC Injection
Dc injection produces a dc offset in the basic power system waveform
The increased half cycle voltage has the potential to increase saturation of magnetic components (transformers).
This saturation causes increased power system distortion.

18. Considerations of Interconnection
Voltage Flicker
The AES has the potential of creating the flicker in voltage
AES should not create objectionable flicker for other customers on the area EPS.

19. Considerations of Interconnection
Harmonics

20. Considerations of Interconnection
Unintentional Islanding Protection
Undesired for an AES
Safety and Power Quality Problems (area EPS and Local Loads)
Repair Operations: Pose a threat
Repair Operations: Delay of Service Restoration
Prevention
Limit AES installed capacity
Reverse Power Protection at PCC
Active anti islanding method (inverter based)

21. Thank You