FINAL REPORT GREEN SQUARE ZONE ADDITIONAL TRANSFORMER

Transcription

1 FINAL REPORT GREEN SQUARE ZONE ADDITIONAL TRANSFORMER 31 st May 2010 Disclaimer This document has been prepared and made available solely for information purposes and consultation under the National Electricity Rules. It has been prepared with all due care and skill for the purposes of the National Electricity Rules and nothing in this document can be or should be taken as a recommendation in respect of any possible investment. This document does not purport to contain all of the information that a prospective investor or participant or potential participant in the NEM, or any other person or interested parties may require. In preparing this document, it is not possible nor is it intended for EnergyAustralia to have regard to the investment objectives, financial situation and particular needs of each person who reads or uses this document. In all cases, anyone proposing to rely on or use the information in this document should independently verify and check the accuracy, completeness, reliability and suitability of that information and the reports and other information relied on by EnergyAustralia in preparing this document, and should obtain independent and specific advice from appropriate experts or other sources. Accordingly, Energy Australia make no representations or warranty as to the accuracy, reliability, completeness or suitability for particular purposes of the information in this document other than for the regulatory purposes of the National Electricity Rules. EnergyAustralia and its employees, agents and consultants shall have no liability (including liability to any person by reason of negligence or negligent misstatement) for any statements, opinions, information or matter (expressed or implied) arising out of, contained in or derived from, or for any omissions from, the information in this document, except insofar as liability under any New South Wales and Commonwealth statute cannot be excluded

2 TABLE OF CONTENTS EXECUTIVE SUMMARY INTRODUCTION Purpose and Scope Background IDENTIFICATION OF NEED FOR AUGMENTATION Applied Service Standard Subtransmission Substations (Urban/Non-Urban) Zone Substations and Overhead Lines (Urban/Non-Urban) Underground Sub-transmission Cables (Urban/Non-Urban) Description of Network Constraints Capacity Issues at Green Square Zone Substation Asset Condition Issues Applicable National Electricity Rules Requirements OPTIONS Demand Management Installation of a 3 rd transformer at Green Square zone substation ECONOMIC ANALYSIS OF OPTIONS CONCLUSION APPENDIX A ECONOMIC ANALYSIS OF BASE CASE...10 Page 2 of 10

3 EXECUTIVE SUMMARY This paper has been prepared to report on the assessment of options for the compliance of the Green Square load area within EnergyAustralia s Eastern Suburbs electricity supply network, in accordance with clause (h) of the National Electricity Rules (the Rules). The work proposed by this report involves augmentation expenditure of under $10 million and is regarded by the Rules as a new small dual-function network asset. Accordingly, EnergyAustralia has not previously consulted on this project. The Green Square Zone additional transformer is classified as a dual-function asset under Chapter 6 of the National Electricity Rules (rules). The rules (clauses and 5.6.6) requires that, where analysis indicates that any relevant technical limits of a distribution system will be exceeded, the Distribution Network Service Provider must notify any affected Registered Participants of these limitations and the expected time for corrective action and consult with affected Registered Participants and interested parties on possible options to address the projected limitations. The timing of the proposed work is primarily driven by the need to address upcoming load constraint and would thus be regarded as a reliability augmentation project. Substantial load growth in the Green Square load area has resulted in a capacity constraint at Green Square 132/11kV zone substation (ZS). To ensure a safe and reliable electricity supply for existing customers, EnergyAustralia is providing additional capacity to meet forecast load demands and mitigate energy at risk. The provision of additional capacity is required to meet network performance requirements set by EnergyAustralia in accordance with Schedule 5.1 of the Rules. This report covers the following issues: Section 1 of the paper provides a description of the Green Square load area. Section 2 presents EnergyAustralia s service standards for the area and describes, in detail, the nature of the load growth in the area, the issues affecting the supply network in the area and the need for augmentation of supply to the area. Section 3 outlines the possible options to address the issues affecting the supply network including options for supply system development. A build and a non-build option are described: Demand Management Installation of a 3 rd transformer at Green Square ZS Section 4 presents the results of economic analysis of the supply side options considered. Section 5 concludes that the most cost effective strategy within the regulatory test is the option of Installation of a 3 rd transformer at Green Square ZS. EnergyAustralia s recommended action is to upgrade Green Square ZS by installing a 3rd transformer at an estimated cost of $3.95 million. This recommendation is made based on the least cost test to provide additional capacity for the upcoming load constraint. Page 3 of 10

4 1. INTRODUCTION 1.1. Purpose and Scope This Final Report has been prepared to meet the requirements of clause (h) of the Rules and to advise registered participants and interested parties on specific development work proposed by EnergyAustralia for its Eastern Suburbs electricity supply area. It includes: A discussion of supply system limitations identified by EnergyAustralia that have led to the necessity of identifying possible options for augmentation of the distribution network in the area; A discussion of the service standard that has been adopted for planning purposes; A description of options identified for development of the electricity supply in the area; and A detailed cost effectiveness analysis of each of these options, carried out in accordance with the requirements of the regulatory test Background The Eastern Suburbs load area extends from Surry Hills in the north-west, south to Bunnerong North and west as far as Marrickville. The Eastern Suburbs network is supplied from the inner metropolitan transmission network at Surry Hills Sub-transmission Substation (STS), Bunnerong STS and from TransGrid s Beaconsfield West Bulk Supply Point (BSP). It includes 132kV and 33kV assets and with twenty substations, it is one of the largest network areas in EnergyAustralia s franchise area. Page 4 of 10

5 Figure 1 below is a geographic diagram of the Eastern Suburbs area. Figure 1: Eastern Suburbs Load Area Green Square 132/11kV ZS is located in the central portion of the Eastern Suburbs supply area and is currently supplied by Beaconsfield West BSP. Figure 2 below indicate the schematic overview of the area. Figure 2: System Diagram around Green Square Zone Substation Page 5 of 10

6 2. IDENTIFICATION OF NEED FOR AUGMENTATION 2.1. Applied Service Standard EnergyAustralia is required to comply with service standards that are specified in the Design, Reliability and Performance Licence Conditions (Licence Conditions), which were imposed on NSW distributors by the Minister for Energy on 1 October The design planning criteria are specified in Schedule 1 of the Licence Conditions and reliability standards are specified in Schedules 2 and 3. For existing network, a distributor must be as compliant as practicable with these requirements by 1 July 2014 and fully compliant by 1 July All new network elements must comply with these requirements. The service standards that are applicable to a consideration of supply constraints affecting the Green Square load area are summarised below. For further details refer to the Licence Conditions or to EnergyAustralia s Network Management Plan Subtransmission Substations (Urban/Non-Urban) With all elements in service, the thermal capacity is required to meet at least 115% of forecast demand. For a failure of a single critical element (i.e. N-1 conditions) within a subtransmission substation, the forecast demand is not to exceed the thermal capacity. Recovery of load should be within one minute Zone Substations and Overhead Lines (Urban/Non-Urban) With all elements in service, the thermal capacity is required to meet at least 115% of forecast demand. Following a failure of a single critical element (i.e. N-1 conditions), the network must be designed to recover supply within one minute for systems supplying >10MVA, and otherwise, within best practice repair times. For systems that supply >10MVA, the forecast demand of a zone substation or overhead feeder network may exceed the N-1 capacity for up to 1% of the year i.e. a total aggregate time of 88 hours per annum, up to a maximum of 20% above the N-1 capacity Underground Sub-transmission Cables (Urban/Non-Urban) The forecast demand of an underground feeder network may not exceed the N-1 capacity at any time Description of Network Constraints Load Forecast EnergyAustralia has previously published details of its load forecasts and the timing of loads exceeding technical limits of the system in its Annual Electricity System Development Review. The load forecast includes committed spot loads and normal levels of load growth. The timing of the constraint for Green Square ZS is shown below and is based on the forecast projected from the summer 2008/09 and winter 2009 actual loads Capacity Issues at Green Square Zone Substation Green Square Zone Substation is forecast to exceed its licence capacity by 5.6 MVA in summer 2011/12 and 17.5 MVA in summer 2012/13. Diagram below shows the load forecast of Green Square Zone Substation. Page 6 of 10

7 Green Square Zone Substation (based on actuals from Summer 2008/09 & Winter 2009) Actuals Forecast MVA Year Winter Load Winter Limit Summer Load Summer Limit '04 '05 '06 '07 '08 '09 '10 '11 '12 '13 '14 '15 '16 Actual Forecast Winter Load Limit Summer 03/04 04/05 05/06 06/07 07/08 08/09 09/10 10/11 11/12 12/13 13/14 14/15 15/16 Load Limit (Note: Green Square ZS was commissioned in November 2005.) Asset Condition Issues 11kV compound switchgear at neighbouring Mascot Zone has been prioritised for replacement by The 33kV HSL feeders 328, 332, 360, and 337 between Bunnerong STSS and Mascot Zone are required to be replaced. Feeder 337 is planned for retirement by Feeders 328,332 & parts of 360 are to be replaced before Reconstruction of Mascot Zone to 132/11kV is driven primarily by condition of 11kV switchgear. The replacement will also address the 33kV cable condition issues. Significant 11kV load transfer from Mascot to Green Square is required to facilitate the reconstruction of Mascot Zone. The proposed completion date of Mascot Zone reconstruction is planned to be December Page 7 of 10

8 2.3. Applicable National Electricity Rules Requirements Green Square ZS and its associated transformers are classified as dual-function system assets by the National Electricity Rules (the Rules). The proposed development strategy for the Green Square ZS involves expenditure of less than $10 million which is regarded by the Rules as a small dual-function network asset. The new capacity provided by the proposed work will be used to address upcoming load constraint and would thus be considered a growth driven augmentation. EnergyAustralia has analysed the cost-effectiveness and feasibility of a range of options to resolve the load constraint at Green Square ZS. 3. OPTIONS EnergyAustralia has identified four Area Plan strategies for the Eastern Suburbs load area. The transformer installation project at Green Square is common across all analysed supply strategies. In accordance with this, a build and a non-build option were considered, these two options are described below Demand Management A Demand Management screening test was carried out in November 2009, investigating for any demand management solution to defer the 3rd transformer installation at Green Square ZS. The Demand Management screening test concluded that the 3rd transformer installation at Green Square ZS could not be cost effectively deferred due to the level of load growth at the Green Square load area Installation of a 3 rd transformer at Green Square zone substation This option involves installation of the 3rd 50MVA transformer in Green Square ZS, which will increase its license capacity to 126MVA. The total capital cost of this work is estimated to be $3.95M, with a NPC of $3.86M. This project is expected to be completed by summer 2011/12, hence enabling compliance in summer 2011/ ECONOMIC ANALYSIS OF OPTIONS An economic analysis has been carried out for the period 2009/10 to 2018/19. It involves the comparison of options by carrying out a Net Present Costs (NPC) analysis. An economic analysis of base case is shown in Appendix A. Four supply strategies were identified and analysed for the Eastern Suburbs load area. This project of installing a 3rd transformer is common across all four supply strategies in the Eastern Suburbs load area as per the 2009 to 2014 Regulatory Determination, and there is no other viable alternative option. Page 8 of 10

9 Sensitivity analysis of the base case was considered, however it is not presented due to the fact that there is only one viable option, and this option is common to all strategies. 5. CONCLUSION EnergyAustralia intends to upgrade Green Square ZS by installing a 3rd transformer at an estimated cost of $3.95M. The transformer installation project at Green Square is common across all four supply strategies in the Eastern Suburbs load area. There is no other viable alternative option. This work is forecast to be completed by Oct This service availability date may change if the project is affected by circumstances beyond EnergyAustralia's control, such as changes in the timing of customer load increases or other issues such as: delays in the approval process, equipment supply difficulties, unforeseen technical constraints, acts of God, and industrial action. Page 9 of 10

10 6. APPENDIX A ECONOMIC ANALYSIS OF BASE CASE Discount Rate 8.5% NPC ($k) Total ($k) 2009/ / / / / / / / / /2019 3rd Tx at Green Square 3,642 3, , O&M Total 3,863 3, , Note: The estimates are based on 2009/10 real dollars ($k) Page 10 of 10