If never allowing auto-reclose, fault-finding must be carried out after the breaker opens, which is laborious and time-consuming. This in turn causes disruption to supply, and risks reputational damage to the operator, as well as penalties for lost customer minutes.

If always allowing auto-reclose, the operator risks reclosing onto a permanent cable fault (perhaps multiple times), causing significant damage to local assets. In severe cases, the damage can be catastrophic, exposing risk to life as well as fatal damage to critical assets in the surrounding network, leading to further outage time.

In reality, an operator will rely on a policy that lies somewhere between these two options. For instance, permitting auto-reclose on circuits where the cable is a small percentage of the total line length. However, a reliance on this policy does nothing to mitigate the risks and assumptions of either approach.

Our solution

MCP is a cost-effective and sophisticated protection solution that enable operators to never reclose on a permanent fault, and therefore safely auto-reclose on transient faults.

The solution draws on Synaptec’s DES technology to inform protection systems if there is a fault in the cable section.

The passive sensing solution offers operators many unique benefits, including:

• Passive sensors – As the sensors use the existing optical fibre in the cable network, they require no control power, data networks or ongoing maintenance, so can easily be installed and left at numerous, remote locations.
• Simple infrastructure – One interrogator in the control rack can instrument many locations up to 60 km from substation, either in series or in parallel.

• Resilient – Our technology is immune to environmental factors such as temperature
  or electromagnetic interference.
• Compliant – It is standards-compliant and digital-ready, and so can be used with both legacy and digital substation equipment.
• Cyber secure – With only analogue optical signals in the fibre beyond the substation fence.
• Millisecond response – Each measurement is synchronised within one microsecond, and is processed to inform the protection response in sub-cycle timescales. This means that if a cable fault is identified, an AR block signal is issued long before the breaker even opens.

• Compatible with communication protocols – No additional data networking required as system is compatible with conventional relays, and streams Sampled Values and GOOSE messages for IEC 61850 / IEC 61869 systems.
• Simple set-up – Commissioning is done centrally, with industry-leading configuration tools to enable a streamlined experience.
• Easily connects – Sensors are compatible with industry standard CTs at any level, allowing any circuit to be addressed across transmission and distribution.

How it works

Passive sensors

Synaptec’s passive sensors combine industry-standard instrument transformers with Distributed Electrical Sensing (DES) technology to enable remote circuits to be instrumented without complex infrastructure.

The Passive Secondary Converter (PSC), an optical sensor, connects to the secondary circuit of an industry-standard CT at the cable sealing ends, where the overhead line and underground cable connect.

Interrogators

Back in the substation, which could be up to 60 km away, a single DES Interrogator is installed in the control rack, which instruments each
sensor location.

Using industry-standard algorithms such as 87L differential current protection logic and ANSI 50G earth overcurrent, depending on requirements, the system instantly detects when a fault has occurred on the cable zone, and informs the protection response.

On detection of a cable fault, the DES Interrogator will instantly communicate an auto-reclose blocking signal to the main protection system.
The system therefore enables discrete auto-reclose to be permitted or blocked, depending on whether the fault has been detected in the underground cable section.

This is all done within milliseconds, well in advance of the breaker even opening, keeping the network safe and secure.

Multi-zone protection for complex topologies

Mixed Circuits are only one example of how our technology can improve protection schemes. The solution is flexible to support a number of topologies, as one Interrogator can instrument multiple sections in series or in parallel.

Sectors we support