Screening For Non-Network Options
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Screening For Non-Network Options Sussex Inlet Zone Substation - Asset Renewal Project Endeavour Energy April 2018
CONTACT If you have any comments or enquiries regarding this report or wish to submit your ideas regarding possible demand reducing initiatives please send to the following email and addressed to Manager Asset Strategy and Planning: consultation@endeavourenergy.com.au
TABLE OF CONTENTS
1 INTRODUCTION .................................................................................................................... 1
2 NETWORK REQUIREMENTS .............................................................................................. 2
2.1 SUBSTATION ASSETS ............................................................................................... 2
2.1.1 33/11KV POWER TRANSFORMERS ........................................................... 3
2.1.2 33KV EQUIPMENT ....................................................................................... 3
2.1.3 11KV SWITCHYARD..................................................................................... 3
2.1.4 AUXILIARY TRANSFORMERS .................................................................... 4
2.1.5 METERING CUBICLE ................................................................................... 4
2.1.6 CONTROL BUILDING ................................................................................... 4
2.2 CONCLUSION – BASIS FOR THE RETIREMENT DECISION .................................... 4
2.3 DEMAND FORECAST ................................................................................................. 4
2.4 LOAD TRANSFER CAPABILITY ................................................................................ 5
2.5 LOAD AND ENERGY AT RISK REVIEW .................................................................... 6
3 NETWORK RENEWAL OPTIONS ........................................................................................ 6
3.1 PREFERRED OPTION ................................................................................................ 8
4 NON-NETWORK OPTION INVESTIGATION ....................................................................... 8
4.1 DEFERRAL OF THE RETIREMENT DECISION .......................................................... 8
4.2 REDUCTION IN ASSET REQUIREMENTS USING A NON-NETWORK OPTION ....... 9
5 NON-NETWORK OPTION OBJECTIVE ............................................................................... 9
5.1 LOAD REDUCTION POTENTIAL ................................................................................ 9
5.1.1 PERMANENT DEMAND REDUCTION.......................................................... 9
5.1.2 ALTERNATIVE SOURCE OF ELECTRICITY .............................................. 10
5.2 CHARACTERISTICS OF DEMAND REDUCTION ..................................................... 10
6 NON-NETWORK OPTIONS ................................................................................................ 11
6.1 OPTION 1 - EMBEDDED GENERATION CONNECTED AT 11KV ............................ 12
6.2 OPTION 2 - EMBEDDED GENERATION AT LOW VOLTAGE.................................. 13
6.3 OPTION 3 - DEMAND REDUCTION BEHIND THE METER ...................................... 13
6.4 NON-NETWORK OPTION SUMMARY ...................................................................... 14
7 FINANCIAL EVALUATION ................................................................................................. 14
8 CONCLUSION ..................................................................................................................... 15
9 CONSULTATION ................................................................................................................. 15
9.1 SUBMISSIONS REQUESTED ................................................................................... 159.2 ENQURIES ................................................................................................................ 15
10 RECOMMENDATION .......................................................................................................... 15
APPENDIX A - SUSSEX INLET ZONE SUBSTATION SINGLE LINE DIAGRAM ........................ 16
ii | Screening for Non Network Options – Sussex Inlet ZS Asset Renewal1 INTRODUCTION This Screening Test Report has been prepared by Endeavour Energy in accordance with the requirements of clauses 5.17.4 of the National Electricity Rules (NER). The purpose of this report is to explore the feasibility of non-network options to address the network limitation created by the retirement of the Sussex Inlet Zone Substation (ZS) 11kV busbar and associated structures. A planning review has identified that the 11kV busbar and associated structures are suffering from corrosion damage and have reached the end of their life with an increasing risk of failure. Failure will cause the complete loss of supply from the substation and therefore the project to renew Sussex Inlet is a “reliability corrective action” (refer NER clause 5.10.2- reliability corrective action). Further, the substation contains a single bus-section isolator which cannot be maintained without a complete outage of the substation and the design and condition of these assets create safety issues for electricity workers required to do work on or near them. Therefore, the purpose of this project is to consider options for the substation to provide for the renewal of assets which have reached the end of their effective service lives to ensure the ongoing safe and reliable operation of the substation. Options that were considered for the substation include: Do nothing; Non-network options including demand management strategies; Construction of a new outdoor 11kV busbar; Construction of a new control building with indoor 11kV switchgear; and Construction of a new control building with indoor 33kV and 11kV switchgear. The existing outdoor 11kV busbar is shown in Figure 1 FIGURE 1 – SUSSEX INLET ZONE SUBSTATION 11KV BUSBAR The development of this screening report and the investigation of associated non-network solutions for Sussex Inlet ZS is in accordance with the Regulatory Investment Test for Distribution (RIT-D) process. 1 | Screening for Non Network Options – Sussex Inlet ZS Asset Renewal
This screening report includes the following:
The basis of the decision to retire the assets that have reached the end of their serviceable life;
Timing and level of the network load at risk associated with the retirement of Sussex Inlet ZS and
any other associated network limitations;
An overview of the feasible network option(s);
The potential to remove the load at risk/network limitation by implementing a non-network solution;
and
The objectives for a successful Demand Management (DM) program.
This non-network option screening test is a result of the network limitation created by the retirement of
network assets that have reached the end of their effective service lives.
This report explores the use of a range of non-network options to replace the functionality of the 11kV
busbar at Sussex Inlet ZS to allow for the retirement of the busbar and associated structures. The
conclusion of the non-network option investigation for the Sussex Inlet ZS asset replacement is stated in
Section 8. Endeavour will approach the non-network services market with a Non-Network Options
Report where there is the possibility of reducing the cost of network supply and identifying a lower cost
alternative to the like-for-like replacement of the retired assets or where it may be possible to avoid or
defer the retirement decision.
2 NETWORK REQUIREMENTS
Sussex Inlet ZS is a rural 33kV/11kV zone substation supplied from West Tomerong Transmission
Substation via Tomerong ZS. The substation is located in The Springs Road outside of the township of
Sussex Inlet in an industrial/commercial area. There is also a residential development taking place on
the opposite side of The Springs Road which will eventually extend to directly opposite the substation.
The substation is equipped with two 33/11kV 15 MVA power transformers. There are two circuit
breakers in the 33kV transformer bays which were manufactured in 2005. The substation also includes
an outdoor 11kV switchyard which contains four reclosers which were manufactured between 2001 and
2004. The substation was established in 1968 and is therefore, apart from the more recent assets, 49
years in age.
2.1 SUBSTATION ASSETS
Table 1 below shows the age (in 2018) of the various assets at Sussex Inlet ZS.
As indicated in Table 1, the age of the substation equipment is varied, ranging from new to 50 years.
Further, the written down value of the substation in July 2017 was $1.76 million.
TABLE 1 – ASSET AGE
Asset age
Asset category Asset details
(years)
33/11kV Power Transformers 2 x 15MVA 47
Support structures 5-50
33kV Switchgear
2 x CBs 12
Support structures 50
11kV switchgear 1 x reclosers 16
3 x reclosers 14
Protection relays Numerical transformer protection 5
SCADA MD1000 RTU 12
2 | Screening for Non Network Options – Sussex Inlet ZS Asset RenewalAsset age
Asset category Asset details
(years)
Isolators, Busbars and switchyard structures Aluminium, copper and galvanised steel 5
Control building Sheet metal shed 31
2.1.1 33/11KV POWER TRANSFORMERS
There is insufficient space between the power transformers to provide adequate protection to the other
transformer in the event of a fire in one of the transformers. Accordingly, it is proposed that a fire wall
should be constructed between the two power transformers as part of this project.
2.1.2 33KV EQUIPMENT
The 33kV busbars are of outdoor design. The two isolators SX14 and SX24 (refer Appendix A) were
installed in 2013 on new support structures and are in good condition. There is also a 33kV busbar
support in each of the transformer bunds. The support in Transformer No. 1 bund is a steel reinforced
concrete structure while the support in Transformer No. 2 bund is a painted steel structure. Both are
suffering from corrosion damage. The structure in Transformer No. 1 bund is experiencing spawling of
the concrete which has exposing the reinforcing steel. The steel in both structures is experiencing
rusting which is impacting its structural integrity. Continuous degradation may also lead to mechanical
failure and outages of the transformer bays and leading to reliability and supply security issues.
Therefore these supports should be replaced in the short term
2.1.3 11KV SWITCHYARD
11KV BUSBARS, ISOLATORS AND SUPPORTS
The 11kV busbar is located outdoors and was established in 1968. The 11kV steel support structures
are showing significant signs of corrosion over substantial areas and particularly at welds and bolts and
the structure footings. This corrosion has also caused some degree of metal loss of the footings and
other locations and affects the structural integrity of the busbar. Therefore, there is an increasing risk of
mechanical failure leading to potential loss of supply from the substation for extended periods of time
resulting in reliability issues.
Further, due to safety clearance constraints, maintenance of 11kV bus section isolator SXA7 requires
an outage of the entire substation. Sussex Inlet ZS’s distribution network is isolated with only two 11kV
feeder ties of limited capacity to the surrounding zone substations therefore limiting the opportunities to
maintain supply to customers during maintenance on the isolator. As a result, the isolator is in poor
condition with an increased risk of mechanical failure should it be required to be operated.
In addition, there are no transformer circuit breakers to isolate the switchyard from the transformers and
therefore when switching isolators in the switchyard there is a risk of an arc-flash incident. Therefore,
the 11kV switchyard presents a safety issue for operators and for workers that are required to carry out
switching for maintenance or rearrangement of the 11kV network in an emergency.
Maintenance on the feeder isolators, transformer isolators and power transformers are conducted by
transferring the substation load onto one bus-section through 11kV distribution switches and taking an
outage of the other bus-section to conduct maintenance on all equipment in that section. This is
currently achievable given the existing low demand on the substation. However if the load increases in
the future this method it will become unworkable. Further, the congested layout of the 11kV busbar with
minimal clearances and poor layout heightens the risk that an error could be made during maintenance
or an emergency situation resulting in an arc-flash or electrical safety incident.
3 | Screening for Non Network Options – Sussex Inlet ZS Asset RenewalThese issues are a problem with the design of the busbar arrangement and therefore it is recommended that replacement with a new busbar with appropriate safety clearances and safe standardised layout be considered. 2.1.4 AUXILIARY TRANSFORMERS The primary auxiliary supply is provided by an 11kV/415V 25kVA transformer manufactured in 1968 which is located on the 11kV busbar. Backup supply is from a 33kV/415V 63kVA transformer which is located in the 33kV Transformer No. 2 bay. The 33kV/415V unit appears to be in reasonable condition, However, the 11kV/415kV unit is suffering from significant corrosion damage and should be replaced in the short-term. 2.1.5 METERING CUBICLE The metering equipment is located in an outdoor cubicle between the two power transformers. The cubicle exterior and internal panels are severely rusted jeopardising the integrity of the metering equipment. Therefore, it is recommended that this cubicle is replaced in the short term. 2.1.6 CONTROL BUILDING The control building was built in 1987 and houses the protection and control equipment. It is of a domestic sheet-metal garage design and is built on a concrete slab. The roof is suffering from corrosion and there is damage to the internal roof sarking. The building is also subjected to flooding during storms. Further, the building has poor sealing and ventilation and provides poor protection for the control equipment which it houses. Therefore, the building should be renewed in the short term. 2.2 CONCLUSION – BASIS FOR THE RETIREMENT DECISION The evaluation of the asset condition has highlighted the safety and reliability risks associated with the current assets. Endeavour Energy believes that this projects meets the criterion of being a reliability corrective action, as detailed in the National Electricity Rules (NER) based on the fact that if nothing were done the substation would not be able to maintain supply to customers and therefore would not meet the requirements of Schedule 5.1 of the NER. Further, the safety risks presented by these assets in their present condition are in excess of the “as low as reasonably practicable” levels required under the Work Health and Safety Act 2011 (NSW) which compels Endeavour Energy to retire the assets. As a result of the risk assessment it is recommended that action be taken to address the risks presented by: The outdoor 11kV switchyard; The control building. The 33kV support structures in the transformer bunds; and The issue of fire segregation between the power transformers. 2.3 DEMAND FORECAST The firm capacity of the two power transformers at Sussex Inlet ZS is currently 15 MVA compared to a current summer peak demand of 7.5 MVA and a winter peak of 5.9 MVA. These peak demands are forecast to increase modestly for the next 10 years reaching 8.0 MVA in summer and 6.4 MVA in winter (with a 50% probability of being exceeded (POE)) by the end of the forecast period. This is due to a residential development to the east of the substation which is currently expanding. Therefore, the existing transformers have adequate capacity for the 10 year forecast demand period. The 50% PoE summer and winter demand forecasts for Sussex ZS are shown in Table 2 below. 4 | Screening for Non Network Options – Sussex Inlet ZS Asset Renewal
TABLE 2 – SUSSEX INLET ZS SUMMER AND WINTER FORECAST
Item Actual Forecast (50% POE)
2015 2016 2017 2018 2019 2020 2021 2022 2023 2024 2025 2026 2027
Summer
4.9 5.2 7.5 8.0 8.0 8.0 8.0 8.0 7.9 7.9 7.9 7.9 7.9
Forecast (MVA)
Winter Forecast
5.2 6.1 5.9 6.0 6.3 6.3 6.3 6.3 6.3 6.3 6.3 6.3 6.4
(MVA)
2.4 LOAD TRANSFER CAPABILITY
Sussex Inlet ZS currently supplies four 11kV feeders. Two of the four 11kV feeders are tied to 11kV
feeders from the adjacent zone substations of Tomerong and Yatte Yattah as shown in Figure 2 below.
Sussex Inlet ZS is 21.6 km from Tomerong ZS and 27.6 km from Yatte Yattah ZS. Tomerong and Yatte
Yattah ZS’s 11kV networks do not have the capacity to offload Sussex Inlet ZS on a permanent basis.
This is due to the distances involves and the lack of alternative 11kV feeder connections to provide
back-up under planned and un-planned outages. Consequently, no permanent transfer capacity is
available.
FIGURE 2 – SUSSEX INLET ZONE SUBSTATION (ZS) 11KV LAYOUT
5 | Screening for Non Network Options – Sussex Inlet ZS Asset Renewal2.5 LOAD AND ENERGY AT RISK REVIEW
The above demand forecast shows the level of demand reduction required to retire the Sussex Inlet ZS
and avoid this project, being 8.0 MVA. This represents the load at risk that needs to be targeted by a
non-network option.
An analysis of the energy at risk and expected unserved energy was conducted to determine the value
of expected unserved energy. This analysis usually involves an assessment of the probability of failure
and the consequence in the event of failure including the expected outage duration and expected
unserved energy. These factors form the basis of probabilistic planning and the timing for network
limitation investigations. However, for the Sussex Inlet Zone Substation asset renewal project the
retirement of the 11kV busbar will result in the total loss of capacity from the substation and not a partial
replacement accompanied with a reduction in capacity. To reflect this, the probably of failure is set to
one and the total load is not supplied.
Further, this analysis usually uses the value of customer reliability (VCR) to determine the value of
expected unserved energy. However, for this project, a nominal retail tariff of $0.30 per kWhr is used as
this represents the value a retail customer will pay for normal supply and what a non-network option will
be expected to charge the customer to provide supply from an alternative source.
The base case (do nothing option) results in unserved energy values as shown in Table 3. The figures
represent a weighted average of 30% and 70% of the expected unserved energy figures for the 10%
PoE and 50% PoE maximum demand forecasts respectively.
TABLE 3 – BASE CASE RISK EXPOSURE
Energy at risk Hours at risk pa Expected unserved Value of expected
Year
(MWh) annual energy (MWh) unserved energy ($M)
2018/19 28,400 8,760 28,400 $11.5
2019/20 49,700 8,760 49,700 $14.9
2020/21 62,900 8,760 62,900 $18.9
2021/22 72,400 8,760 72,400 $21.7
3 NETWORK RENEWAL OPTIONS
The network renewal options considered to address the asset and network needs identified at Sussex
Inlet Zone Substation include:
1. Refurbishment of the existing 11kV busbar;
2. Construction of a new outdoor 11kV busbar;
3. Construction of a new control building with indoor 11kV switchgear; and
4. Construction of a new control building with indoor 33kV and 11kV switchgear.
Option 1 proposes to maintain the existing 11kV switchyard arrangement and to address the bus-
isolator issues by installing a bus-section circuit breaker bay cabled to the ends of the two bus sections
making the existing bus-section isolator redundant.
The 11kV transformer bays could also be modified to include circuit breakers. This will allow all
equipment in the arrangement to be effectively maintained and provide operational flexibility to run the
substation with a solid 11kV busbar as required.
The corrosion of the busbar support structures would be repaired by cutting out the corroded sections
and welding in new sections and by paint treatment. The 11kV/415V auxiliary transformer would also be
replaced.
6 | Screening for Non Network Options – Sussex Inlet ZS Asset RenewalWhilst this option is technically feasible, this short-term patch-up approach does not address the safety
risks presented by the poor clearances and congested design of the existing 11kV busbar arrangement.
Accordingly, it is not considered that this option reduces the risks posed by the substation to as low as
reasonably practicable (ALARP) and therefore this option is not considered to be sufficiently adequate
to warrant further assessment.
The three remaining network options which warrant further assessment, along with their estimated
costs, are summarised in Table 4 below.
TABLE 4 – REDEVELOPMENT OPTIONS
Option Redevelopment works
Option 2 - Construct a new outdoor11kV busbar to the south of the existing busbar;
New outdoor 11kV Install 2 x TX breakers, 1 x bus-section breaker and 4 x 11kV feeder breakers;
busbar Install a new 11kV padmount auxiliary transformer;
Construct a small new control building;
Install new protection and control and metering equipment in the new control building;
Install a new SCADA RTU in the new control building;
Install a new station battery in the new control building;
Replace the two corroded 33kV support structures;
Install fire walls between and beside the two power transformers;
Demolish and remove the existing 11kV busbar and metering cubicle ;
Demolish and remove the existing control building including existing protection and
control and auxiliary equipment.
Option 3 – Construct a new control building on the southern side of the existing switchyard;
New 11kV control Install a new 11kV switchboard with 2 x TX breakers, 1 x bus-section breaker and 4 x
11kV feeder breakers (and space for a further 4) in the new building;
building
Install a new 11kV auxiliary padmount transformer;
Install new protection and control equipment and metering in the new control building;
Install a new SCADA RTU in the new control building;
Install a new duplicated station battery and dc system in the new control building;
Replace the two corroded 33kV support structures;
Install fire walls between and beside the two power transformers;
Demolish and remove the existing 11kV switchyard and metering cubicle;
Demolish and remove the existing control building including existing protection and
control and auxiliary equipment.
Option 4 – Construct a new control building to the south of the existing switchyard;
New indoor 33kV Install a new 33kV switchboard with 2xTX breakers, 1 x bus-section breaker and 1x
substation 33kV feeder breakers (and space for an additional breaker);
Install a new 11kV switchboard with 2xTX breakers, 1 x bus-section breaker and 4 x
11kV feeder breakers (and space for a further 4) in the new building;
Install a new 11kV auxiliary padmount transformer;
Install new protection and control equipment in the new control building;
Install a new SCADA RTU in the new control building;
Install a new duplicated station battery and dc system in the new control building;
Cable the 33kV feeder into the new switchboard;
Install fire walls between and beside the two power transformers;
Demolish and remove the existing 11kV switchyard, metering cubicle and 33kV
structures;
Demolish and remove the existing control building including existing protection and
control and auxiliary equipment.
7 | Screening for Non Network Options – Sussex Inlet ZS Asset RenewalTable 5 below provides a summary of the three viable network options in terms of initial capital costs,
future capital costs and ongoing risk costs. The net present cost shows the cost-benefit position of each
option over the longer term and is used to select the lowest cost approach to addressing the network
need.
TABLE 5 – PRESENT COST OF OPTIONS
Initial cost All costs Estimated year Present cost
Proposed works
($M) ($M) of expenditure ($M)
Option 2
Initial redevelopment works 5.59 5.59 2018 - 2021 5.59
Future indoor 33kV redevelopment 6.61 2033 3.45
Safety risk of workers coming within clearances 0.21 per
2018-2033 2.30
of the 11kV busbars and associated switchgear year
Total present cost 11.34
Option 3
Initial redevelopment works 5.79 5.79 2018 - 2021 5.79
Future indoor 33kV redevelopment 5.81 2033 3.03
Safety risk of the outdoor 11kV is eliminated by
- - -
installing indoor vacuum switchgear
Total present cost 8.82
Option 4
Initial redevelopment works 7.98 7.98 2018 - 2021 7.98
Future indoor 33kV redevelopment 3.86 2033 2.01
Safety risk of the outdoor 11kV is eliminated by
- - -
installing indoor vacuum switchgear
Total present cost 9.99
3.1 PREFERRED OPTION
Option 2 addresses the principal renewal needs of the substation at the lowest initial cost while Option 3
provides improved safety and ongoing operation and maintenance outcomes compared to Option 2 at a
marginally higher initial cost. Option 4 provides further improved safety but at a significantly higher cost
than both options 2 and 3.
However, Option 3 provides the lowest net present cost taking into account the cost of the proposed
works and the risk costs addressed and therefore is the recommended network option to address the
renewal needs at Sussex Inlet Zone Substation.
4 NON-NETWORK OPTION INVESTIGATION
There are two distinct decisions made when analysing end-of-life asset replacement. The first being the
retirement decision and the second being the options to address the network limitation created by the
retirement decision. Both decisions may require a non-network option investigation to determine if there
is a lower cost option that provides a superior net benefit to all those who produce or consume energy in
the national market.
4.1 DEFERRAL OF THE RETIREMENT DECISION
The decision to retire the 11kV busbar and associated structures is based on the project being classified
as a reliability corrective action. However, the premise of the deferral of the retirement decision is that
assets that are approaching the end of their lives are able to have their lives extended as a result of a
reduction in demand or that the degradation of the asset is reversible with demand reduction.
8 | Screening for Non Network Options – Sussex Inlet ZS Asset RenewalIn some cases this may be the case however, the Sussex Inlet ZS 11kV busbar and associated structures are physically damaged and unaffected by the level of demand. Consequently, a non-network option will not alter the decision to retire the affected assets and this option is discounted. 4.2 REDUCTION IN ASSET REQUIREMENTS USING A NON-NETWORK OPTION The replacement of the 11kV busbar and associated structures is the preferred network option to address the network limitation created by the retirement decision at Sussex Inlet ZS. Consideration has also been given to reducing the extent of the replacement 11kV busbar assets in combination with a non-network option which reduces the demand on the substation. However, the standard replacement 11kV circuit breakers, busbars and associated structures have capacity in excess of what is required at Sussex Inlet ZS and therefore there is no material cost benefit in reducing the demand on the busbars. Likewise, the substation has its current configuration of two power transformers, two 11kV busbar sections and four 11kV feeder circuit breakers to provide adequate reliability to the connected customers and therefore there is nil scope to reduce the substation to a simpler configuration without sacrificing reliability performance. 5 NON-NETWORK OPTION OBJECTIVE The objective of a Non-Network Option is to provide sufficient demand reduction to meet the requirements detailed in the non-network option analysis and to ultimately allow for the retirement of Sussex Inlet ZS. To achieve this, the demand reduction must target the entire supply area of Sussex Inlet ZS and allow for the future growth of demand in that area. A secure supply or demand reduction of 8.0 MVA needs to be achieved by 2020 which is the expected retirement date for the substation. A similar level of reliability as provided by the network option will also need to be provided. 5.1 LOAD REDUCTION POTENTIAL There are currently 3,200 residential customers and 272 business customers supplied from Sussex Inlet ZS. The summer and winter peak demand occurs at 18:00 hours indicating that the peak demand is predominantly due to the residential load with business customers making only a minor contribution. Feasible non-network options must either permanently remove the demand or supply the existing demand by alternative means or a combination of both. Suggested options for the two types of non- network options are listed below: Permanent Demand Reduction: Energy efficiency; and Fuel substitution. Alternative Source of Electricity: Micro embedded generation; Large scale embedded generation; Small scale energy storage; and Large scale energy storage. 5.1.1 PERMANENT DEMAND REDUCTION Permanent demand reduction generally involves working with customers and offering solutions that permanently avoids the use of electricity. Options that reduce the amount of electricity consumed will still require a network to supply electricity or an alternative source of electricity to be produced. This source may be within the household, such as solar panels or back-up diesel generation. Alternative 9 | Screening for Non Network Options – Sussex Inlet ZS Asset Renewal
sources of electricity that are centrally produced will still require an electricity network to distribute the
energy.
5.1.2 ALTERNATIVE SOURCE OF ELECTRICITY
As mentioned above, an alternative source of electricity may be in the form of behind the meter
embedded generation, a centralised large scale energy source or embedded generation connected to
the LV or 11kV network. In all cases there will need to be sufficient capacity available to allow the
substation to be removed.
Behind the meter energy will need to be coupled with sufficient energy storage to cope with low energy
production times and/or have an alternative form of energy production. A centralised system will need
to be located in the vicinity of the existing 11kV network for distribution purposes. It will also require a
substation to transform and distribute the electricity produced. This may also require energy storage
and/or an alternative form of energy production to ensure adequate reliability of the supply.
A successful long-term non-network option will also need to consider potential future load increases.
5.2 CHARACTERISTICS OF DEMAND REDUCTION
Currently the Sussex Inlet ZS supply area is predominantly rural residential in nature. The summer and
winter load profiles are shown in Figures 3 and 4 below. Both the summer and winter profiles peak
around 18:00 hours indicating a predominantly residential load type. The Sussex Inlet area has
traditionally experienced its peak demand during holiday periods. This is confirmed by the summer peak
occurring between Christmas day and New Year’s Day and the winter peak occurring on the Sunday of
the Queen’s Birthday June long weekend.
FIGURE 3 –SUSSEX INLET ZS SUMMER LOAD PROFILE
Sussex Inlet ZS - 30 December 2016
8 40
7 35
6 30
5 25
Degrees
MVA
4 20
3 15
2 10
Load Profile
1 5
Temperature
0 0
22:00
3:00
10:00
11:00
12:00
13:00
14:00
15:00
16:00
17:00
18:00
19:00
20:00
21:00
23:00
0:00
1:00
2:00
4:00
5:00
6:00
7:00
8:00
9:00
Time
To enable permanent removal of Sussex Inlet ZS the peak demand of 8.0 MVA needs to be targeted.
The base load is between 2.0 and 2.5 MVA with the mid-season peak demands varying between 3.0
and 4.0 MVA. Peak demands occur during cold weather in winter and hot weather in summer. High
peak demands occur when the extreme weather conditions coincide with holiday periods. This is
demonstrated in Figure 5 below.
10 | Screening for Non Network Options – Sussex Inlet ZS Asset RenewalFIGURE 4 –SUSSEX INLET ZS WINTER LOAD PROFILE
Sussex Inlet ZS - 12 June 2016
6 25
5
20
4
15
Degrees
MVA
3
10
2
Load Profile 5
1
Temperature
0 0
10:00
11:00
12:00
13:00
14:00
15:00
16:00
17:00
18:00
19:00
20:00
21:00
22:00
23:00
1:00
8:00
0:00
2:00
3:00
4:00
5:00
6:00
7:00
9:00
Time
FIGURE 5 –SUSSEX INLET ZS ANNUAL LOAD PROFILE
Sussex Inlet ZS - Annual Load Profile 2016
8
7
6
5
MVA
4
3
2
1
Load Profile
0
Time
6 NON-NETWORK OPTIONS
Three non-network option scenarios utilising embedded generation to replace the substation have been
assessed to test whether their costs are broadly comparable to the proposed network option which
would indicate that they may be feasible. The non-network options include:
1) Generation at a single point connected to the 11kV network to effectively replace the zone
substation;
2) Generation distributed at multiple locations in the LV network to effectively replace the zone
substation, the 11kV network and each distribution substation; and
3) Generation behind the meter at each customer premises to give at customer a stand-alone
power supply.
11 | Screening for Non Network Options – Sussex Inlet ZS Asset RenewalDemand reduction on its own has not been considered as a feasible option as it will not avoid the need
to replace the 11kV busbar and associated structures. Demand reduction may be considered in
conjunction with an embedded generation option to reduce the level of generation but has not been
costed as part of the analysis.
6.1 OPTION 1 - EMBEDDED GENERATION CONNECTED AT 11KV
This option includes embedded generation at a single location on the 11kV network to supply the entire
load of Sussex Inlet ZS to allow the removal of the substation entirely.
To ensure a reliable supply for a peak demand of 8.0 MVA there will need to be a certain level of
redundancy of generation. There is no natural gas available at Sussex Inlet ZS and therefore the
readily available sources of generation include:
diesel generators;
solar photo-voltaic cells with battery storage and backup generators;
solar thermal with process heat or battery storage and backup generators;
wind generators with back-up generators; and/or
a combination of all the above.
There are many possible combinations of the above approaches but for the purposes of testing
feasibility the most straightforward solution using diesel generators has been assessed. This option
includes:
3 x 4 MVA diesel generators to provide a level of redundancy for the peak demand of 8.0 MVA;
and
An 11kV busbar to distribute the generation to the existing four 11kV feeders and to provide
protection systems for the feeders.
To ensure frequency stability the 11kV network supplied from the embedded generation would remain
interconnected with the 11kV system supplied from the surrounding Tomerong and Yatte Yattah zone
substations. However, as noted above, no permanent load transfer capacity to these substations is
available.
The estimated costs of the assets required for this option are shown in Table 6 below.
It is assumed that the diesel generators have a life of 20 years in this situation and use on average 3.2
million litres of fuel per year to service the average demand on the substation of 2.53 MVA.
The diesel fuel costs are based on the simplified assumption of 7kWhr generation per litre of diesel at a
cost of $1.20 per litre. Actual costs may differ but these assumptions are considered to be adequate to
give an initial view of the likely feasibility of these options.
TABLE 6 – 11KV EMBEDDED GENERATION COST SUMMARY
Present cost
Establishment cost Running cost
Plant Quantity (over 25 years)
($M) ($M pa)
($M)
A B
Diesel generation 3 x 4 MVA 8.4 4.0 66.7
11kV busbar with 4 x
Substation 5.0 - 5.0
circuit breakers
Totals 13.4 4.0 71.7
Note A: Based on the average diesel supply and set-up cost for large scale systems of $700 per kVA.
Note B: Based on 2.53 MVA average, 24hr per day at $1.20/litre + nominal 2% maintenance costs
This option has an initial cost of $13.4 million and ongoing fuel costs, maintenance costs and generator
replacement costs contributing to a present cost over 25 years of $71.7 million.
12 | Screening for Non Network Options – Sussex Inlet ZS Asset RenewalThere are a range of other options using combinations of renewable generation sources and storage
systems which are likely to give reduced operating costs compared to the option estimated. However,
the initial investment costs are also likely to be significantly higher.
6.2 OPTION 2 - EMBEDDED GENERATION AT LOW VOLTAGE
This option includes the installation of embedded generation in the low voltage network supplied by
Sussex Inlet ZS. For simplicity it is assumed that each 11kV LV distribution substation is replaced with
a generator of similar capacity to supply the customers connected to the low voltage network from that
distribution substation. There are 150 distribution substations supplied by Sussex Inlet ZS and therefore,
assuming sufficient diversity is available at the low voltage substation level and taking average values,
150 x 53kVA generators will be required.
In this simplistic assessment which ignores a range of key issues including:
Provision of a site and security for each generator;
Provision of redundancy and back-up supply;
Maintaining frequency;
Noise issues associated with running the generators 24 hours a day in residential areas;
Process for re-fuelling and maintenance;
Decommissioning of the 11kV network;
Reduced maintenance costs by not having an 11kV network; and
Each embedded generator effectively running as an island and disconnected from the grid.
It is assumed that the diesel generators in this situation have a life of 10 years and on average use 4.9
million litres of fuel each year to supply the 2.53 MVA average demand of the substation as noted in
Option 1.
The cost summary for this option is shown in Table 7 below.
TABLE 7 – LOW VOLTAGE EMBEDDED GENERATION SUMMARY
25 Year present
Establishment cost Running cost
Plant Quantity cost
($M) ($M per annum)
($M)
A
Diesel generation 150 x 53kVA 6.4 5.1 86.8
Note A: Based on a $42,000 cost per unit including site and connection costs and generators being replaced every 10 years.
6.3 OPTION 3 - DEMAND REDUCTION BEHIND THE METER
This option includes a stand-alone power supply for each of the 3,200 residential and 272 business
customers supplied from Sussex Inlet ZS. The after diversity maximum demand across the board for
these customers is 2.3kVA. However, in its simplest form this option assumes that all customers are
stand-alone and therefore there is no diversity applicable. On this basis the demand for each customer
is assumed to be 6.8kVA on average and therefore this option requires either 3,472 x 10kVA diesel
generators or 3,472 x solar systems with PV panels, batteries and a small backup diesel generator. A
generalised cost of the solar PV based stand-alone system is $50,000 which includes 7kW solar PV,
30kWhr battery and 3.6kVA diesel generator.
The two sub options of diesel generation and solar PV based system have been evaluated and are
summarised in Tables 8 and 9 below.
13 | Screening for Non Network Options – Sussex Inlet ZS Asset RenewalTABLE 8 – STAND ALONE CUSTOMER POWER SUPPLIES BY DIESEL GENERATOR
Establishment cost Running cost 25 year present cost
Plant Quantity
($M) ($M per annum) ($M)
Customer diesel A
3,472 x 10kVA 6.9 5.5 171
generators
Note A: Based on $8,000 per customer and generators being replaced every 7 years.
TABLE 9 – STAND ALONE CUSTOMER POWER SUPPLIES BY SOLAR PV/BATTERY SYSTEM
Establishment cost Running cost 25 year present cost
Plant Quantity
($M) ($M per annum) ($M)
Stand Alone 3,472 x Stand A
208 0.49 294
systems Alone systems
Note A: Based on 7kW PV, 30kWhr battery, 3.6kVA generator - $50,000 per customer.
6.4 NON-NETWORK OPTION SUMMARY
A summary of the non-network option costs is shown in Table 10 below.
TABLE 10 – SUMMARY OF NETWORK AND NON-NETWORK OPTION COSTS
Present cost Cost per kVA
Option Non-network option description
($M) ($)
1 11kV embedded generation 72 9,000
2 LV embedded generation 87 10,875
3a Behind the meter customer stand-alone supply (generator) level 171 21,375
Behind the meter customer stand-alone supply (solar PV
3b 294 36,750
system)
- Preferred Network Option 8.8 1,100
7 FINANCIAL EVALUATION
Endeavour Energy is required to ensure investments in the distribution network are prudent and that the
preferred option provides the optimum economic value while achieving the required supply outcomes.
Endeavour Energy’s financial incentive payments for the implementation of demand management
initiatives are based in this instance on the value of avoiding the replacement Sussex Inlet ZS. This
amount is $5.8 million (Network Option 3) in initial costs with a net present cost of $8.8 million. If the
replacement of the substation were avoided Endeavour Energy would need to dismantle, remove and
remediate the zone substation site. The cost of this is estimated to be $0.3 million giving a net available
funding of $5.5 million. A further substantial cost may be required to remove the sub-transmission
feeders that currently supply the substation should this be required.
The demand reduction required to permanently defer installing the replacement capacity is 8.0 MVA.
With a contribution from Endeavour Energy of $8.8 million this equates to $1,100/kVA as a once off
payment for permanent demand reduction. Alternative energy sources and similar non-network
proposals would need to be able to distribute the energy into the 11kV network and maintain appropriate
levels of reliability and quality supply and fund all on-going operating and maintenance costs for
perpetuity. Comparison costs for alternative options are shown in Table 10.
14 | Screening for Non Network Options – Sussex Inlet ZS Asset Renewal8 CONCLUSION Four non-network solutions which use different approaches to providing an alternative source of electricity to avoid the replacement of Sussex Inlet Zone Substation 11kV busbar and associated equipment have been broadly assessed to determine if there is a likelihood of them being feasible. The present costs of these four options range from $72 million to $294 million all of which far exceed the present cost of the preferred network option of $8.8 million. The 11kV embedded generation option requires the establishment of a substation to transform and distribute the electricity. Given that the purpose of the project is to avoid replacing an 11kV busbar and associated equipment, this option effectively replicates parts of the existing Sussex Inlet ZS but at a higher cost than the proposed replacement works and therefore is not feasible. Apart from the high cost, embedded generation at the low voltage level presents significant risks associated with establishing 150 generation units distributed throughout the residential and rural areas with subsequent noise, maintenance, security and fuel transportation issues. For these reasons this option is considered not to be feasible. Behind the meter alternative sources of electricity will require every household and business to agree to implement this option within their premises to enable the removal of Sussex Inlet ZS. This is seen as not being practical to implement. Furthermore, the overall cost is orders of magnitude higher than the proposed network solution. Therefore, as a result of the Demand Management Feasibility Study Endeavour Energy has concluded that there are no non-network options which will be feasible to avoid the need to replace the 11kV busbar and associated structures at Sussex Inlet ZS. 9 CONSULTATION 9.1 SUBMISSIONS REQUESTED Endeavour Energy seeks written submissions from market participants and interested parties in relation to the conclusion and recommendation outlined in this document or any other comments or enquiries regarding this report. 9.2 ENQURIES All submissions and enquiries regarding this document should be directed to Endeavour Energy’s Manager Asset Strategy and Planning at consultation@endeavourenergy.com.au. 10 RECOMMENDATION It is recommended not to proceed with further investigations of non-network options to avoid the need to replace the 11kV busbar and associated structures at Sussex Inlet ZS and to proceed with the preferred network option. 15 | Screening for Non Network Options – Sussex Inlet ZS Asset Renewal
APPENDIX A - SUSSEX INLET ZONE SUBSTATION SINGLE LINE DIAGRAM 16 | Screening for Non Network Options – Sussex Inlet ZS Asset Renewal
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