05-10-2012, 05:17 PM
Protection of DG
[attachment=35450]
IEEE standards are being developed towards detailed requirements for the integration of DG with the distribution system
IEEE 1547
1- Not cause over-voltages or loss of utility relay coordination
2- Disconnection when no longer operating in parallel with utility
3-Use “utility grade” relays
4-Not cause objectionable harmonics
5-cause loss of synchronization (no objectionable flicker)
Effect of Power electronic
Energy conversion is the most important functional block in installing inverter-based DGs Energy conversion
Also power electronic is used for
Control the power flow from DG to utility grid
Mitigate power quality
Interconnection Transformers
Configuration of interconnection transformer play an important role in the DG connection with the utility each have advantages and disadvantages
One important thing to decide for interconnection transformer is ground connection
Solidly grounded
Ungrounded
Grounded through grounding impedance
Protection Issues with DGs
Short circuit Power and Fault Current Level
Islanding
Communication Based methods
Local measurement methods
Passive methods
Active methods
Reduce reach of impedance relays
Reverse power flow and Voltage Profile
Auto re-closure
Ferro-Resonance
Grounding
Comunication based methods
Based on communication between DG and the utility grid
Power line used as carrier for communication between the DG and utility grid. A continuous signal is transmitted by utility network via the power line
Communication adds also costs to both DG and the grid infrastructure; these methods are not commonly used today
Active methods
Active methods appeared so as to minimize the non-detection zone of islanding detection methods in conditions when generation matches load
active methods inject a small disturbance to the utility grid and based on the grid response decide whether or not an island has formed
The most common active methods are using
Positive feedback inside the DG control
Impedance detection
[attachment=35450]
IEEE standards are being developed towards detailed requirements for the integration of DG with the distribution system
IEEE 1547
1- Not cause over-voltages or loss of utility relay coordination
2- Disconnection when no longer operating in parallel with utility
3-Use “utility grade” relays
4-Not cause objectionable harmonics
5-cause loss of synchronization (no objectionable flicker)
Effect of Power electronic
Energy conversion is the most important functional block in installing inverter-based DGs Energy conversion
Also power electronic is used for
Control the power flow from DG to utility grid
Mitigate power quality
Interconnection Transformers
Configuration of interconnection transformer play an important role in the DG connection with the utility each have advantages and disadvantages
One important thing to decide for interconnection transformer is ground connection
Solidly grounded
Ungrounded
Grounded through grounding impedance
Protection Issues with DGs
Short circuit Power and Fault Current Level
Islanding
Communication Based methods
Local measurement methods
Passive methods
Active methods
Reduce reach of impedance relays
Reverse power flow and Voltage Profile
Auto re-closure
Ferro-Resonance
Grounding
Comunication based methods
Based on communication between DG and the utility grid
Power line used as carrier for communication between the DG and utility grid. A continuous signal is transmitted by utility network via the power line
Communication adds also costs to both DG and the grid infrastructure; these methods are not commonly used today
Active methods
Active methods appeared so as to minimize the non-detection zone of islanding detection methods in conditions when generation matches load
active methods inject a small disturbance to the utility grid and based on the grid response decide whether or not an island has formed
The most common active methods are using
Positive feedback inside the DG control
Impedance detection