Electricity Asset Management Plan 2019-2029
204
Vector Limited://
reiterated the importance of the DC systems and correct alarming. DC systems in a number of zone substations, especially some of the older systems, are showing increasing signs of poor health and high probability of failure and a programme of replacement and refurbishment is now needed. Following the incident, a comprehensive assessment was completed on DC systems at all zone substations in Vector’s Northern region. This programme of works will include a comprehensive assessment of DC systems at all zone substations in the Auckland region. The corrective actions identified during the assessments will culminate into a master actions list and scope of works for repair, refurbishment and replacement as the case may require. The objective is to ensure that after completion of this programme of works, DC systems for both the Northern and Auckland regions, will provide the associated alarms to the SCADA master station and meet the functional requirements as per the latest Vector standards for redundancy and the successful operation of protection and other equipment that are reliant on DC systems in zone substations.
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
Failure to assess and subsequently correct potential issues with DC systems and associated SCADA alarms, may result in extended unplanned outage events. Customers will be at risk of extended unplanned events and zone substations will be at risk of serious damage such a fire if DC systems are not brought to the correct level of reliability. Undertaking this programme of works will significantly improve DC Systems’ asset reliability and security of supply to customers and the avoidance of consequent SAIDI risk. A reliable DC system will ensure tripping of circuits as and when required during faults and disturbance and will reduce the risk of serious damage to zone substations. Proper and effective alarming will notify the EOC of any pending issues
Rejected
Option 2: Undertake a scheduled programme of works to complete DC system assessments in the Auckland region and complete all corrective actions in both Auckland and Northern regions
$3.25M Selected
PROPOSED INVESTMENT SUMMARY ($MILLION NOMINAL)
DESCRIPTION
FY20
FY21
FY22
FY23
FY24
FY25
FY26
FY27
FY28
FY29 TOTAL
Auckland DC systems replacement
0.25
0.25
0.25
0.12
0.13
0.12
0.13
0.13
0.12
0.13
1.63
Northern DC systems replacement
0.25
0.25
0.25
0.12
0.13
0.13
0.12
0.13
0.13
0.12
1.63
Total CAPEX
0.50
0.50
0.50
0.24
0.26
0.25
0.25
0.26
0.25
0.25
3.26
REPLACE AUCKLAND LOAD MANAGEMENT PC85 LOAD CONTROLLERS
NEEDS STATEMENT Vector regularly offers into the New Zealand Electricity Market tranches of up to approximately 80 MW of a total available 100 MW controllable hot water load within the Auckland electricity network. This assists with peak power shifting and allows for deferral of CAPEX projects. The 1980’s Plessey/GPT PC85 load controller provides the local and remote SCADA control interface at the 13 Auckland zone substations that have this load management function. A Landis+Gyr power line carrier ripple plant then adds a 475 Hertz signal onto the substation 22 kV and 33 kV subtransmission circuits to signal customers hot water cylinders and
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