For an electricity distribution utility, the core directive and core revenue stream is the supply of electricity to end customers. Any interruption to that stream of energy causes an economic loss to the utility. Not only does the interruption hurt a utility customer’s meter readings, but regulators apply their own fines and incentives for utilities to improve their reliability. In much of the world, the only economically viable method for electrifying vast swathes of the countryside is overhead distribution, which is inevitably more subject to reliability issues. Thus, the omnipresent question arises, “How do I improve the reliability of my distribution network?”

In our final instalment in the series of Electricity Distribution System Automation (DSA), we explore the relevance of IEC 61850 communications capabilities and how this technology can be applied to achieve reliability gains in the performance of the electricity network. Whilst IEC 61850 is traditionally considered confined to larger substations, IEC 61850 Generic Object Oriented Substation Event (GOOSE) Messaging has niche applications in achieving DSA when applied to distributed pole mounted switchgear.

As we explored centralised automation in our previous edition, the key modus operandi of the system is for all remote Intelligent Electronic Devices to report their status and readings to a centralised automation system, where the automation/switching decisions are made. Centralised automation is essentially the automation of the SCADA control room’s actions, replacing the operators who act on signals from the field with pre-programmed algorithms.

Through our series on implementing the Smart Grid, or electricity Distribution System Automation, we have explored various use cases of Reclosers being deployed to automatically reconfigure the network to isolate faults and restore supply. Fundamentally, the usage of voltage sensing on either side of the interrupting device affords great capability in network automation, as the presence/absence of voltage on a circuit breaker can be used as an automation logic input. Cases which use only voltage sensing for automation schemes are considered communications-free, as no dedicated information sharing is required between devices. These implementations are simple, robust and cost effective, but require an additional close-onto-fault operation. The simple method to resolve the close-onto-fault case is to introduce communications between devices, (which we explored our first case in Distribution Automation II), providing a data link between the reclosers to prevent this close-onto-fault behaviour.

In our last article, Distribution Automation III, we explored the quintessential Ring Mode network design configuration and the automation of switching to isolate faults without the use of communications between the devices. This method of distributed automation relies on sensing voltage presence on either side of the circuit breaker, in this case a Recloser, to determine whether to close to restore power.

In edition one of our series, we covered the fundamental case of automation of the distribution network – a simple Auto-Changeover Scheme using the voltage sensors on either side of a NOJA Power OSM Recloser and some simple control logic to detect what to do. This greatly effective technique allows for automation of power supply changeover for critical loads and provides great reliability when communications infrastructure is not available. Despite the economic value of such a setup, the key drawback was the extra close onto a fault scenario, when the fault is on the load side of the switchgear arrangement.

In our previous instalment in this series on Distribution Network Automation, we covered the simple case of an Auto-Changeover Scheme achieved using Voltage sensing on either side of the circuit breaker. If you missed this edition, you can read it here.

Automation of the electricity distribution grid provides substantial economic benefits for utilities and society. Effective fault location and network restoration can in most cases be converted to an algorithm, enabling the optimisation of network reliability and providing resilience to network faults. The techniques for achieving distribution network automation are varied, and whilst the merits of automation can be lauded as “network modernisation”, carefully considered automation can create genuine returns for utilities.

NOJA Power, in partnership with their South African exclusive distributor RWW Engineering are celebrating the commissioning of their new production facility in South Africa to service the local market for Reclosers.

Switchgear Manufacturer NOJA Power today celebrates the accolade of Best Exhibition Showpiece at the 2019 Coal and Mining Conference in Novokuznetsk Russia for the OSM38 38kV Pole Mounted Autoreclosing Circuit Breaker.