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Minimising blackouts

Minimising blackouts

29/04/2008 | Channel: Electricity, IT / Technology

By Quentin Grady of Oracle Utilities

Ofgem's launch of a two-year study of the UK power grid has focused new attention on a continuing problem: how to keep power flowing to all customers when storms, an aging infrastructure, and increased demands on the network all threaten to increase blackouts.

Blackouts today
Today's UK customer has only minimal complaints about loss of electricity. That is due in part to utilities' diligence in adding software and equipment to the network to minimise outage duration. Many utilities - especially those in storm-prone regions -
have implemented applications that identify fault location. Their mobile workforce applications direct the right repair crews to the right locations. And distribution management systems increasingly help those crews complete tasks more rapidly without sacrificing safety.

Still, blackouts do occur, forcing customers to live without power for hours at a time.

A new approach
Now utilities have an additional option with which to minimise blackouts. Fault Location, Isolation, and Service Restoration (FLISR)(1) software can automatically:
  • Sense trips (faults) in switches that are monitored and controlled by a SCADA.
  • Identify the faulted section.
  • Isolate the fault.
  • Restore power to customers by automatically switching them to nonfaulted sections of the line.
FLISR does not 'fix' the problem. Utilities must continue to send crews to the site of the fault, where they verify it and make permanent repairs. But customers experience only a brief, momentary outage. From their point of view, the grid has ‘healed itself.’

Is the power grid ready for FLISR?
Many UK powerline networks today already include advanced technologies to improve performance. These include:
  • Fault detection through fault indicators deployed in the engineered feeder network.
  • Feeders with more than one isolation point in their design.
  • Alternative feeds from tie points such that customers can be restored as soon as faulted sections are isolated.
  • Automated analysis of capacity and switching alternatives via:
  • SCADA-controlled devices. Devices controlled by distribution automation.
  • Intelligent Electronic Devices.(2)

FLISR makes these technologies even more efficient and useful. It is not necessary, however, to have all of them in order to reap FLISR benefits. Utilities with nothing more than fault current indication, widely deployed, can garner immediate benefit for operational efficiency by using the FLISR fault location capability.

Benefits
FLISR has a number of benefits:
  • It provides more granular data that improves decision management and minimises the scope of work for field crews for each fault event.
  • It reduces the impact of faults on the operations team's overall responsiveness and performance.
  • It improves the reliability of poorly performing feeders and service areas.
  • It can also improve utilities' performance records by turning what would once have been prolonged outages into short events lasting less than five minutes.
By temporarily restoring power to customers who would otherwise experience a prolonged power outage, FLISR has the clear potential to improve customer satisfaction and minimise economic losses resulting from electrical disruptions. It also has the potential to improve reliability, safety, and restoration speed while at the same time improving the stability of the distribution network under transient conditions (resulting from fault and switching operations).

FLISR is thus a major step forward in the control of active and reactive power flows - a first step toward a self-healing grid. It can make a significant contribution to continuing network reliability as demands on the grid escalate.

For further information please visit:
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Minimising blackouts

1 Fault Location, Isolation, and Service Restoration (FLISR) responds to protection trips of SCADA monitored and controlled switches (i.e. feeder circuit breakers (CB) and downstream reclosers (ACR)). FLISR automatically identifies the faulted section using the telemetered Protection Trip and Fault Indication (FI) flags and then (in Auto Mode) automatically executes the isolation and restoration actions to restore the non-faulted areas de-energized by isolating the fault. In Manual Mode, FLISR will present the isolation and restoration actions for review and execution by the user.

2 The distinction between SCADA and Fully automatic controlled switches in the number of reclosers planned for installation is important. SCADA controlled switches allow for both automation observability and coordinated automatic control. Fully automatic switches do not necessarily allow for automation observability and they also have limitations dealing with off nominal switch positions.