Electricity Asset Management Plan 2019-2029
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Vector Limited://
factor to performance of the service level in RY18. This change was undertaken to meet the heightened expectations of the community for health and safety. It is also a practice that was undertaken in response to the enactment of the HSWA.
TARGET Target under development following review of isolation for safety policy impact.
2.5 RESILIENCE We are committed to ensuring that we prepare our network and our customers to not only adapt to changing conditions but also to withstand and recover rapidly from a disruptive event. We are deploying new network solutions such as microgrids, that will improve supply resilience in vulnerable areas. At the same time, as the uptake of customer-owned distributed energy resources (such as solar energy, battery solutions and electric vehicles) increase with time, these resources together with network solutions will play a critical role in improving the overall network and its resilience to customers. We call this concept Shared-Resilience. DEFINITION Vector uses a probabilistic approach to security of supply standards (SoSS) which set out Vector’s performance expectations in relation to restoration targets following planned and unplanned equipment outages. We prepare a demand forecast that is used to assess the performance of the network against the SoSS service level. The SoSS performance assessment is based on the demand forecast for the Symphony scenario described in Section 1. Appendix 10 sets out the forecast for RY19 onwards. Based on this demand forecast, we can anticipate the implication on the network Security of Supply, by essentially comparing asset capacity against demand and determining risks and shortfalls in the network. MEASUREMENT SoSSs are defined in terms of N-x where x is the number of coincident outages that can occur during times of high demand without extended loss of supply to customers. Security levels are also defined by the time allowed to restore supply after an asset failure. The security of supply strategy and standards aim to provide customers with an acceptable reliability of supply at an acceptable cost. This means balancing economic and service level risks appropriately. 2.5.1 PERFORMANCE AGAINST OUR SECURITY OF SUPPLY STANDARD (SOSS) SERVICE LEVEL
SoSSs and restoration targets are categorised by the particular asset failure (e.g. zone substations, distribution feeders), the load at risk and by the asset location (e.g. CBD and urban).
This service level metric captures the number of breaches of the SoSS, (should no investment be made). It is another key metric used to establish the reliability and availability of the network and is used to justify expenditure on the network as part of our annual planning cycle. The number of SoSS breaches are forecast on an annual basis. Table 2-10 shows the forecast number of security of supply breaches in accordance with the definitions of this service level metric should no investment be made. It should be noted that for SoSS distribution feeder breaches, the forecast number of breaches is only accurate to FY22 as 11 kV reinforcements projects are only identified one or two years in advance. Section 5 lists the projects needed to mitigate the security of supply breaches. These projects may address more than one breach.
CLAUSE
RY20
RY21
RY22
RY23
RY24
RY25
RY26
RY27
RY28
RY29
CBD substation and subtransmission Zone substation and subtransmission (non-CBD) Distribution feeders (11 kV or 22 kV)
1
2
4
2
1
3
2
1
4
4
3
2
6
4
5
2
1
1
2
Total
5
8
7
3
7
3
5
5
3
4
Table 2-9 Security of supply breaches forecast, should no investment be made
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