What is Anti-Islanding? | BCJ Controls | Solar Relay - PowerPoint PPT Presentation

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What is Anti-Islanding? | BCJ Controls | Solar Relay

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Anti-Islanding is a type of electrical protection for embedded generators such as grid connected solar, wind or diesel. It ensures the generator disconnects electrical supply to the grid in the event of a blackout. Anti-Islanding protection exists to protect personnel and equipment connected the grid in the occurrence of a fault or maintenance. – PowerPoint PPT presentation

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Title: What is Anti-Islanding? | BCJ Controls | Solar Relay


1
What Is Anti-Islanding?
  • Why do we need Anti-Islanding Protection?

2
What is Anti-Islanding?
  • Anti-Islanding is a type of electrical protection
    for embedded generators such as grid connected
    solar, wind or diesel. It ensures the generator
    disconnects electrical supply to the grid in the
    event of a blackout. Anti-Islanding protection
    exists to protect personnel and equipment
    connected the grid in the occurrence of a fault
    or maintenance.

3
Why do we need Anti-Islanding Protection?
  • Islanding can be dangerous to utility workers,
    who may not realize that a circuit is energized,
    and it may prevent automatic re-connection of
    devices. For that reason, inverters must detect
    islanding and immediately stop producing power
    this is referred to as anti-islanding protection.

4
Why do we need Anti-Islanding Protection?
  • The most common example of islanding is a grid
    supply that has solar panels attached to it. In
    the case of a blackout, the solar panels will
    continue to deliver power as long as the sun is
    shining. In this case, the supply line is an
    island with power, surrounded by a sea, or
    void of unpowered lines.

5
Why do we need Anti-Islanding Protection?
  • For this reason, solar inverters that are
    designed to supply power to the grid are
    generally required to have some sort of automatic
    anti-islanding protection in them. In intentional
    islanding, the installation disconnects from the
    grid, and forces the inverter to power the local
    circuit. This is often used as a backup system.

6
How to detect Islanding?
  • Grid-interactive inverters are required to
    produce AC power that matches the existing power
    presented on the grid. In particular, the
    voltage, frequency and synchronize phases of the
    feed it connects to.

7
How to detect Islanding?
  • An installation with an array of solar panels and
    inverters attached convert the varying DC current
    provided by the panels into AC power that matches
    the grid supply. If the grid is disconnected, the
    voltage on the grid line would be expected to
    drop to zero, a clear indication of a service
    interruption.

8
How to detect Islanding?
  • However, when the houses load matches the output
    of the panels at the instant of the grid
    interruption, the panels can continue supplying
    power, which is used up by the houses load. In
    this case there is no obvious indication of an
    interruption.

9
How to detect Islanding?
  • Even when usage and production are matched, the
    failure of the grid will result in additional
    transient signals, there will almost always be a
    short decrease in line voltage, which will
    indicate a potential fault. Such events can also
    be caused by normal events, like the DOL (Direct
    On-Line) starting of a large electric motor.

10
How to detect Islanding?
  • Ways to detect islanding without a large number
    of false trips is the subject of considerable
    research. Each way has some threshold that needs
    to be met before a state is considered to be a
    signal of grid interruption, which leads to a
    protection blind spot in the range of conditions
    where a real grid failure will be filtered out.

11
CONTACT US
(02) 9534 8465 contact_at_bcjcontrols.com.au
12
VISIT US
  • www.bcjcontrols.com.au
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