2. Flow of Presentation
MG & DG
Features & Significance
Effects of Islanding
Methods of detection of Islanding
Micro Turbine model
Wind Turbine model
Micro Grid model
Published Journal Paper
Production of large power & transmitting it through
long distances at high voltages.
Up gradation of old transmission lines not possible in
Micro Grid is a new concept raised to balance load-
Reducing line losses.
Serves load effectively & efficiently.
Power system reliability is maintained.
4. Micro Grid & Distributed
• Small scale decentralized generating technologies that are
connected to the power grid are referred to as Distributed
• Micro-grid (MG) concept assumes a cluster of loads and micro-
sources operating as a single controllable system that provides both
power and heat to its local area.
• Central generating plant
continues to provide most of
the power to the grid, the
distributed resources meet
the peak demands of local
distribution feeder lines or
5. Features & Significance
• Micro sources are placed at customers sites/ Distributed generations
located close to the loads.
• Not centrally dispatched.
• Reduces the flows in transmission and distribution circuits & line
losses are reduced.
• Effective power transfer.
• Serve load efficiently.
• Power system reliability is maintained.
• Power quality is improve.
• Voltage profile of the system is also improved.
Islanding refers to the condition in which a distributed
generation (DG) continues to power a location even though electrical
grid power from the electric utility is no longer present.
the supply line becomes an "island" with power surrounded by a
"sea" of unpowered lines.
IEEE 1547-2003 standard stipulates a maximum delay of 2 seconds
for detection of an unintentional island and all DGs ceasing to
energize the distribution system.
Safety concerns: if an island forms, repair crews may be faced with
unexpected live wires
End-user equipment damage: customer equipment could be damaged
if operating parameters differ greatly from the norm.
Ending the failure: Reclosing the circuit onto an active island may
cause problems with the utility's equipment, or cause automatic
reclosing system to fail to notice the problem.
Hence because of these, distributed generators must detect islanding
and immediately stop producing power; this is referred to as anti-
8. Methods for detection of Islanding
• Under Voltage
• Under frequency
• Rate of change of frequency
• Voltage phase jump detection
• Harmonic detection
• Negative sequence current injection
• Impedance measurement
• Slip mode frequency shift
9. Wavelet Transform
Wavelet transformation (WT) is one of the most powerful signal
processing tool & also one of the most popular of the time-frequency-
The fundamental idea of wavelet transforms is that the transformation
should allow only changes in time extension, but not shape.
WT uses the scaled and offset forms of limited time period, irregular
and asymmetric signal pieces, which is called the “mother wavelet“.
The basic concept in wavelet transform (WT) is to select an
appropriate wavelet function “mother wavelet” and then perform
analysis using shifted and dilated versions of this wavelet.
WT divides a signal into small pieces.
The WT uses short windows at high frequencies and long windows at
Detection of Islanding by negative sequence component
method in which the existence of any disturbances in the
voltage signal found at point of common coupling (PCC).
Voltage signals are being used as the input signals for the
11. Literature Survey
The main philosophy of detecting an islanding situation is
to monitor the DG output parameters and system
parameters and/ and decide whether or not an islanding
situation has occurred from change in these parameters.
In this by negative sequence component method in which
the existence of any disturbances in the voltage signal
found at point of common coupling (PCC) we can detect
Voltage signals are being used as the input signals for the
12. This research involves modeling and detection of Islanding
condition for different fault conditions in Micro-grid. The
modeling and simulation of Wind turbine system, micro turbine
system & SOFC Distributed Generations connected to main
utility grid has been done in this work.
Negative sequence component method is the main condition in
which the existence of any disturbances in the voltage signal
found at point of common coupling (PCC) is of main concern.
Therefore, voltage signals of the negative sequence component
found at PCC has been considered in this thesis work for
analysis towards efficacious detection of islanding.
Voltage signals derived from PCC are being used as the input
signals for the wavelet analysis.
13. SOFC model (Solid oxide fuel
Fuel Cells offer :
To obtain AC current, the
equipment should have power
conditioning equipment to handle
DC to AC conversion and current,
voltage, and frequency control.
14. Micro Turbine model
Micro turbines (MTs) are
small high-speed gas
Advantages of Micro
Strong fuel adaptability
Low fuel consumption
rate Low noise
Low pollution emission
Low maintenance cost
No water-cooled system
15. Wind Turbine Model
Wind turbines are packaged systems that include a rotor, a
generator, turbine blades, and a drive or a coupling device.
The rotor extracts kinetic energy from the wind passing it and
converts it into mechanical torque and the generating system
converts this torque into electricity.
16. Initially the output rotor speed is zero and at 1 second it starts
increasing to 20 m/s and further remains constant with respect to time
range of 10 seconds. The output power initially remains zero and
gradually decreases for a short span and further increases to remain
19. Phase voltage waveform during Islanding
The voltage along the source bus(Vabc_B120), across the Vabc_B25 and
Vabc_B575 and the rated voltage are shown below respectively for a L-L-L-G
fault [transition time: 0.3-0.4], with C.B. transition time [0.3-0.4]
In this work, modeling of components of a MG
system has been successfully done.
The proposed technique investigates the negative
sequence component of voltage, current for
islanding detection in distributed generations.
Wavelet transform is used to process the
negative sequence voltage and current signals.
The fault condition is detected at 4 seconds due
to which the circuit breaker trips and the fault
condition continues for 4.2 seconds after which
the system is restored back to the normal
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