A brief review of SP Energy Networks' application of a new substation-based disturbance recorder and the benefits it is bringing.
What is a sub.net monitor?
A sub.net monitor is a substation-based multifunction disturbance recorder. Connected to voltage and current transformers and auxiliary contacts from protection relays and switchgear, a sub.net monitor can assess various elements of power system performance, process that information at site and send event reports to individual users by email. It can do this in around three minutes.
SP Energy Networks (SPEN) is installing sub.net monitors across its network of primary substations in lower Scotland and North Wales to reduce outage times and asset risk across its network. The rollout represents a multimillion-pound investment from the DNO, but early indications show that financial, operational and service returns will be ample.
Supplied by Irish technology company eMS, the monitors record and analyse fault events and link these to the network map. They enable early indication of 11kV fault locations, confirm that overhead line protection or automation schemes are functioning properly and can determine if circuit breaker operating times are within acceptable limits. They can also help address a range of full range of power quality phenomenon, according to SP Energy Network’s IFI Annual Report for 2008-2009 when the DNO reported on trials of the technology.
SP Energy Networks identified three ‘sticky’ breakers on its network during sub.net trials and by intervening before these breakers were called on in the event of an actual fault, it is estimated the DNO has saved £500k. Another key benefit was the identification of transient faults using impedance maps.
Sub.net monitor EMS Sub.net monitor at SP Energy Networks substation
Useful info:
• SP Energy Network’s rollout of sub.net monitors represents a multi-million-pound investment
• The rollout began in late 2015 and is ongoing
• The effectiveness of the sub.net monitoring technology in addressing network challenges was proven in a £130,000 collaborative Innovation Funding Incentive (IFI) project
• Slow or sticky circuit breakers are recognised across power network operators as a problem due to their tendency to increase interruptions to supply for customers. This is because a slow breaker will allow a fault to escalate in the network
• Over the course of the IFI project during which SP Energy Networks trialled the sub.net monitor, the technology is thought to have progressed from a technology readiness level of six to eight
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