Electricity Asset Management Plan 2019-2029
209
Vector Limited://
sections of the network. The ability to operate 11 kV network switching devices decreases outage times because it negates the requirement for operating personnel to drive from switch to switch. Data and communications between the EOC and the communications modules on 11 kV network switches are via the Conitel protocol and VHF analogue radio. The VHF radio system has reached its end of life and the Conitel protocol is obsolete and firmware and software cannot be updated. Intermediate protocol convertors are required and this has resulted in loss of information and loss of SCADA visibility in the EOC of the status of 11 kV switches. Furthermore, the 2G cellular network does not provide sufficient coverage and there is a need to upgrade the 2G network. Generally, there is a need to replace the communications system and controllers to existing 11 kV pole mounted network switches in Vector’s 11 kV overhead distribution network. The WAN for SCADA in the northernmost region of Vector’s supply area consists of digital microwave radio communications links. The system provides voice over IP and data communications. The existing digital microwave radio WAN consists of a star configured network with very limited redundancy and if the digital mobile radio link between the Albany Heights repeater station in the northern suburbs and the Kraacks Hill repeater station further north in the rural precincts should fail, the northernmost region will be without SCADA visibility and reliant on field staff to switch the network. It must be noted that the upper reaches of our network is also the area in which we recently completed two large BESS’, at Warkworth South and in Snells Beach, that requires reliable communications with sufficient bandwidth. This places even more importance on the requirement to have robust and redundant SCADA connectivity and communications in place to optimize the use of the battery storage systems in the network. There is a need to address the limitations of the northern WAN to ensure reliable network visibility, robust communications channels and control from the SCADA master station. There are implications to SAIDI and health and safety if this is not addressed as the non-visibility of the network leads to longer restoration times, with switching needing to be undertaken by field staff rather than remote control. The RTU located at our zone substations provide an essential part of the SCADA system to collect status information from site and allow remote control of plant at site. The maximum anticipated life of an RTU is 20 years. As an RTU approaches end of life, reliability suffers, requiring more frequent maintenance. Also, older RTUs are no longer supported by suppliers and spares are difficult to get hold of. When an RTU fails, situational awareness of what is happening at site is lost, so EOC is unable to receive updates of events from the site or remotely control equipment. Hence, the controller is unable to effectively respond to any emerging contingency. Coincidental failure of RTUs across a number of sites will exacerbate the situation.
TARGETED OUTCOMES
CUSTOMER EXPERIENCE
SAFETY
RELIABILITY
RESILIENCE
OPERATIONAL EFFICIENCY
CYBER SECURITY AND PRIVACY
OPTIONS CONSIDERED Options to address the need identified above have been assessed and are summarised in the following table.
DESCRIPTION
DISCUSSION OF OPTION
ESTIMATED COST (NPV IF APPLICABLE)
STATUS
Option 1: Do nothing
A do-nothing approach means that SCADA and line differential protection will be reliant on a failing population of 60s vintage copper pilot cables with insufficient bandwidth for the requirements of the future. Ultimately failures of these secondary devices will convert to failures of the primary network and loss of supply to customers. This in turn will result in poor SAIFI and SAIDI indices. There are implications to the H&S of field crews as well without remote visibility of zone substations and switches in the field. This will lead to longer restoration times because of manual switching undertaken by field staff rather than remote control. Selecting this option will remove the risks associated with the ‘Do nothing’ option. It will ensure a communications
Rejected
Option 2: Undertake staged and scheduled programmes of work to replace WAN
$11.47M Selected
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