What is Utility Islanding Protection? - BCJ Controls | eGauge | Bluelog

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Utility Islanding Protection

• BCJ Controls

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Utility Islanding Protection

• The DNSP - Distributed Network Supply
  Provider/Supply Authority has a variety of
  methods available to it to force systems offline
  in the event of a failure.

BCJ Controls pty. Ltd - 2,17 Lorraine St,
Peakhurst, NSW Australia 2210
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Manual disconnection

• Through the use of signals sent though the power
  lines, or on dedicated comms line. Power line
  carrier communications could be installed in all
  inverters, checking for signals from the utility
  and disconnecting either on command, or if the
  signal disappears. Such a system would be
  reliable, but expensive.

BCJ Controls pty. Ltd - 2,17 Lorraine St,
Peakhurst, NSW Australia 2210
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Automated disconnection

• Most small generators require a manual disconnect
  switch, so at a minimum the utility could send a
  worker to pull them out of service. For large
  sources, you could simply install a dedicated
  phone line to have an operator manually shut down
  the generator. In either case, the manual
  reaction time is likely to be too long.

BCJ Controls pty. Ltd - 2,17 Lorraine St,
Peakhurst, NSW Australia 2210
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Impedance insertion

• To deliberately force a section of the grid into
  a condition that will guarantee the inverters
  disconnect.
• An example is a large bank of capacitors that are
  added to a feeder, left charged up and normally
  disconnected. In the event of a failure, the
  capacitors are switched into the feeder by the
  utility. The capacitors can only supply current
  for a short period, ensuring that the start or
  end of the pulse they deliver will cause enough
  of a change to trip the inverters.

BCJ Controls pty. Ltd - 2,17 Lorraine St,
Peakhurst, NSW Australia 2210
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Impedance insertion

• There is no NDZ for this method of anti-islanding
  protection. The main disadvantage is cost, the
  capacitor bank needs enough capacitance to cause
  changes in voltage that will be detected, this is
  a function of the amount of load on the circuit.
  Large banks would be needed, cost prohibitive on
  the part of the utility.

BCJ Controls pty. Ltd - 2,17 Lorraine St,
Peakhurst, NSW Australia 2210
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Supervisory control and data acquisition (SCADA)

• Anti-islanding protection can be implemented
  through the use of the Supervisory Control and
  Data Acquisition (SCADA) systems already used in
  the utility. An alarm could sound if the SCADA
  system detects power on a line where a failure is
  known to be in progress. This does not affect the
  anti-islanding systems, but could allow any of
  the systems to be quickly implemented.

BCJ Controls pty. Ltd - 2,17 Lorraine St,
Peakhurst, NSW Australia 2210
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BCJ Controls

• At BCJ Controls we produce Secondary Protection
  Switchboards with solar protection relays for
  Commercial Solar over 30kW grid connections.
• BCJ Controls - commercial solar network
  protection unit - switchboard manufacturing
  including protection relay anti-islanding and
  zero export devices. BCJ Controls is a solar
  technology company set up by ex-utility
  industrial sparkies. Between them they have a
  large amount of experience in electrical grid
  protection, as well as dealing with utilities on
  a day-to-day basis.

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www.bcjcontrols.com.au

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