Title: Detecting Power Grid Synchronization Failure on Sensing Frequency or Voltage Beyond Acceptable
1Detecting Power Grid Synchronization Failure on
Sensing Frequency or Voltage Beyond Acceptable
2Detecting Power Grid Synchronization Failure
Introduction
- Synchronization means the minimization of
difference in voltage, frequency and phase angle
between the corresponding phases of the generator
output and grid supply. An alternating current
generator must be synchronized with the grid
prior to connection. It cant deliver the power
unless it is running at same frequency as the
network. - Synchronization must occur before connecting the
generator to a grid. Synchronization can be
achieved manually or automatically. The purpose
of synchronization is to monitor, access, enable,
and automatically take the control action to
prevent the abnormalities of voltage and
frequency.
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3Rules Must Be Followed for Power Grid
Synchronization
Voltage Fluctuation
- When a generator is synchronized with a power
grid. - There is a voltage fluctuation on the
distribution line. - During synchronization the voltage fluctuation
should not exceed 3 at the at the point of
common coupling.
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4Rules Must Be Followed for Power Grid
Synchronization
Synchronization Limits
- The limits allowing for synchronization are.
- Phase angle- /-20 degrees
- Maximum voltage difference 7
- Maximum slip frequency 0.44
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5Rules Must Be Followed for Power Grid
Synchronization
Relays
- For checking the synchronization synch check
relay must be used. - The usage of relays cant apply for induction
generators. - The use of synch check relay is to accept as a
backup during synchronization. - It ensures a generator will not connect to a dead
distribution line.
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6Synchronization of Induction Generators
- Standard motor controllers will be used to
synchronization of induction generators. - Turbine shaft power will be used to mechanically
drive the generators up to synchronization speed. - The speed of the motors depends on supplied
frequency and number of poles on the generators.
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7Synchronization of Synchronous Machines
- For synchronous generators output waveform should
be in phase with the grid voltage waveform. - The rate of change of phase angle between the
grid and the machine (generator) must be within
the specified limits. - Some other rules are variable speed drive
arrangement to maintain a constant output
frequency.
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8Failure of Synchronization
- There are various reasons for failure of power
grid synchronization. - Synchronization circuit may fail for responding
to a received input pulse. - It happens when the received input pulse is
shorted than the sampling period of the
synchronizer. - Then no synchronized representation will take
place. - Synchronization circuit may fail, when the pulse
rate of the input signal is higher than the
synchronization rate of the synchronizer.
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9Synchronization Failures and their Detections
- Generators and some local loads have become
disconnected from main distribution lines due to
some issues. - Due to this there is a reduction in quality of
supply. - It may prevent automatic reconnection of devices.
This is called as islanding. - Islanding must be detected and producing power
must be stopped immediately.
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10Following Hazards May Take Place Due to Islanding
- Line voltages may excessive when distributing
lines and generators are disconnected the line is
not earthed. - Due to Islanding synchronization cant be
maintained. - The fault level contribution from the grid to
sub-station may be lost. - Due to this sufficient current may not be
generated. - The voltage levels may go outside of normal
operating limits, and the quality of supply may
be reduced.
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11Detection Methods of Islanding
- Detection of islanding can be done through active
and passive methods. - Passive methods look for transient events on the
grid. - Active methods will probe the grid by sending
signals from the distribution point of grid. - Loss of Mains Protection (LoM) will be designed
to sense the disconnection of generators. - The blind area is called Non Detection Zone
(NDZ).
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12Which Microcontrollers Are Used in This Project?
- 40 pin 8051 Microcontrollers are used in this
project. - The Microcontroller monitors the under/over
voltage being derived from a set of comparators.
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13Applications of Power Grid Failure Detection
- Lighting is one of the main causes for power
system faults. - The major advantage is detecting the
synchronization failure between generators and
power grid. - When there is an Under/over voltage or under/over
frequency. - The comparator will detect the difference the
actual power and reactive. - If there is no failure of power grid
synchronization then the detectors will give the
zero values.
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14Block Diagram
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15Hardware Requirements
- 8051 series Microcontroller
- LCD
- Op-Amps
- 555 timer
- Crystal
- Resistors
- Capacitors
- Diodes
- Transformer
- Voltage Regulator
- Relay
- Transistors
- Slide Switch
- Lamp
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