Electricity Asset Management Plan 2019-2029
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Vector Limited://
〖 SAIDI 〗 _unplanned is the sum of daily unplanned SAIDI values in the assessment period, where if any daily value of unplanned SAIDI is greater than the SAIDI Unplanned Boundary Value then the daily value equals the SAIDI Unplanned Boundary Value.
The SAIDI Unplanned Boundary Value is calculated in accordance with the Commerce Commission process. This limit is set to 3.374 minutes per day for the current regulatory period (1 April 2015 to 31 March 2020).
All of Vector’s interruption data is held in our HV Spec database which is used to calculate and report on SAIDI performance. Supply interruptions are identified by the Supervisory Control and Data Acquisition (SCADA) system or through calls to the Customer Excellence team. Once faults have been resolved by the FSP, details of interruptions are logged in HV Spec. The customer interruptions are updated as supply is restored, with SAIDI calculated for each step in the restoration process. Where faults are identified through the Customer Excellence team, details are also captured in Siebel and linked back to HV Spec. SAIDI is measured on a monthly and annual basis to inform asset management practises. For regulation purposes, SAIDI is reported to the Commerce Commission on an annual basis. SAIDI reporting to the Commerce Commission is subject to an external audit. The SAIDI target is set by the Commerce Commission’s regulatory determination every 5 years. It is largely based on the average SAIDI performance over a 10-year historical reference period. The process for setting this target is specified in the DPP.
DESCRIPTION
RY15
RY16
RY17
RY18
Customer interruptions performance
128.5
117.0
173.6
226.2
Table 2-11 SAIDI
Remote Safety Isolations One of the most significant causes for the SAIDI performance in RY18 exceeding the current DPP target was from the application of Vector’s new Remote Safety Isolation policy for public reporting of low or downed lines. Unfortunately, most public reported downed lines relate to non-Vector assets which results in spurious isolations relating to Chorus or Auckland Transport assets. However, this can only be confirmed post an on-site inspection. For RY18 remote safety isolations contributed approximately 30 SAIDI minutes. Of the different causes for SAIDI this cause is the most significant when compared to the Reference Period. Planned works The other significant cause for the SAIDI performance in RY18 was the impact of Planned Works for the period. For RY18 planned SAIDI contributed approximately 50 minutes of total SAIDI, more than eight times the impact to what was allowed for in the Reference Period (six minutes). This cause is the largest contributor to Vector’s accumulated SAIDI for RY18. Third-Party Damage In RY18 the impact of Third-Party Damage was significant. The SAIDI impact of Third-Party Damage was 33 minutes, almost double the impact assumed in the Reference Period of 17 minutes. In RY18 Vector experienced 28 minutes of SAIDI because of vehicle damage to Vector’s network assets, generally referred to as car v pole incidents. The SAIDI from car v pole incidents in RY2018 eclipse the tolerance provided for in the Reference Period for Third-Party Damage which captures other causes such as “dig-ins”. Overhead asset incidents In RY18 overhead (OH) asset incidents was a major cause of SAIDI. Vector has a large and extensive OH network with long routes through remote and bush vegetated areas which means that OH asset incidents are a significant contributor of faults for the distribution network. The impact of OH asset SAIDI is approximately 16 minutes higher for RY18 when compared to the Reference Period. The largest contributing cause in RY18 to the OH asset related SAIDI was conductor incidents. Underground asset incidents In RY18 underground (UG) asset incidents also had a higher SAIDI than the Reference Period. The UG asset SAIDI for RY18 was approximately 11 minutes higher than the Reference Period allowance. A higher volume of cable faults was the reason for this increase. This cause contributed 26 minutes of SAIDI for RY18. Determining the location of cables faults and their repair are quite time consuming especially in highly built up areas.
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