Header Reasonableness Test RT 007/11 Balhannah & Uraidla 66 / 33 kv Substations RT 007-11 Balhannah and Uraidla - Final Draft Page 1 of 8
DISCLAIMER The purpose of this document is to inform customers, Interested Parties, Registered Participants and solution providers of the outcome of the application of the Reasonableness Test to the network constraint of overload of the Balhannah and Uraidla substations. This document is not intended to be used for other purposes, such as making decisions to invest in generation, transmission or distribution capacity. This document has been prepared using information provided by, and reports prepared by, a number of third parties. While care was taken in the preparation of the information in this paper, and it is provided in good faith, ETSA Utilities accepts no responsibility or liability for any loss or damage that may be incurred by any person acting in reliance on this information or assumptions drawn from it. This Reasonableness Test has been prepared in accordance with section 3 of ESCOSA Guideline 12 Demand Management for Electricity Distribution Networks for the purpose of consulting with Registered Participants, Interested Parties and customers regarding a potential network augmentation. The Reasonableness Test has been prepared with consideration for pertinent information provided by a number of third parties. It contains assumptions regarding, among other things, economic growth and load forecasts that, by their nature, may or may not prove to be correct. ETSA Utilities advises that anyone proposing to use this information should verify its reliability, accuracy and completeness before committing to any course of action. ETSA Utilities makes no warranties or representations as to its reliability, accuracy and completeness and ETSA Utilities specifically disclaims any liability or responsibility for any errors or omissions or not. It is important to note that ETSA Utilities as Distribution Network Service (DNSP) provider can only consider benefits available to the DNSP in evaluating the viability of Demand Management initiatives, e.g. transmission benefits, the possibility of reducing spot market prices and wider benefits like reducing green house gasses have not been considered. Page 2 of 8
GUIDELINE 12 REASONABLENESS TEST Constraints on the Balhannah and Uraidla 66/33kV Substations 1. CURRENT SUPPLY ARRANGEMENT The Balhannah 66/33kV Substation is an injection point into the Eastern Hills 33,000kV (33 kv) electricity distribution system. The substation is operated at 66kV stepped down to 33kV and has three 33kV line exits that supply the local 33kV system. There are approximately 10,200 customers in the surrounding areas supplied from the Balhannah Substation. Balhannah Substation consists of two 12.5MVA 66/33kV transformers and one 7.5MVA 66/33kV transformer. The Balhannah Substation has a normal cyclic summer rating of 30.3MVA, and a firm delivery capacity of 23.3MVA in 2013/14. At Balhannah, the measured demand in 2010/11 was 20.1MVA, and the forecast demand in 2013/14 is 26.8 MVA. The Balhannah Substation is forecasted to be overloaded under contingency conditions in summer 2013/14. Uraidla 66/33kV Substation consists of one 25MVA 66/33kV transformer. The Uraidla Substation has a firm delivery capacity of 17.8MVA in 2013/14. At Uraidla, the measured demand in 2010/11 was 17.7MVA, and the forecast demand in 2013/14 is 21MVA. The Uraidla 33kV Substation is forecasted to be overloaded under contingency conditions in summer 2013/14. The overall supply arrangement for the Balhannah and Uraidla 33kV network is shown in Figure 1 below. Figure 1: Balhannah Area Electricity Supply System Page 3 of 8
2. FORECAST LOAD AND CAPACITY The load type at Balhannah and Uraidla 33kV substations contain a strong contribution from residential and to a lesser extent commercial/retail sites. During hot weather in the summer months, residential air conditioning contributes a significant proportion to the peak load. The peak load is forecast to increase at a rate of approximately 5.4% per annum at Balhannah and approximately 3.1% per annum at Uraidla. The winter peak load is not expected to grow faster than the summer peak. Figure 2: Load versus capacity Balhannah Substation. Figure 3: Load versus capacity Uraidla Substation. Page 4 of 8
3. LOAD CHARACTERISTICS Balhannah and Uraidla 33kV substations experiences high loads for short periods of summer during heat wave events. The peak load curve for Balhannah Substation (figure 4.1), experienced on 29 January 2009 shows that high loads occur between 4pm and 10pm, as could be expected for air-conditioning loads. Figure 4.1: Balhannah 33kV Daily Load Curve (29 January 2009) Figure 4.2: Balhannah 33kV Load Duration for 1/4/2008 to 1/4/2009 Page 5 of 8
The peak load curve for Uraidla 33kV Substation (figure 5.1), experienced on 31 January 2011 shows that high loads occur between 4pm and 10pm, as could be expected for air-conditioning loads. Figure 4.1: Uraidla 33kV Daily Load Curve (31 January 2011) Figure 5.2: Uraidla 33kV Load Duration for 1/11/2010 to 1/11/2011 Page 6 of 8
4. NETWORK UPGRADE OPTIONS To prevent the forced shedding of load at peak times, the capacity in the areas surrounding Balhannah and Uraidla must be increased. Two network augmentation options exist to address the constraint: Upgrade Hahndorf Substation with a new 66/33kV transformer and construct a new 4km, 33kV Line to supply Mylor, Aldgate and Verdun thereby offloading Balhannah; or Upgrade Balhannah and Uraidla 33kV substations. The preferred solution, when the net present cost, timing and effectiveness of related upgrade projects is considered, is to upgrade the Hahndorf Substation with a new 66/33kV transformer and establish a new 4km 33kV line. The indicative cost for this project is $7,000,000. This preferred solution has an additional benefit in that it reduces load on the existing 66kV Line between Mt Barker and Balhannah substations. The non preferred option to upgrade Balhannah Substation would result in the existing 66kV Line from Mt Barker to Balhannah becoming overloaded in 2014. This would then require the construction of a new 9.7km 66kV Line from Mt Barker. 5. DEMAND MANAGEMENT ANALYSIS 5.1 Required Demand Management Characteristics At peak load times the load profile of Balhannah and Uraidla substations are dominated by residential air-conditioning and to a lesser extent commercial and retail sites. Peak loads can be expected at the substation during summer when maximum temperatures greater than 38 C over several days are experienced. The Balhannah load forecast in 2013/14 is 26.8 MVA, during peak load conditions, up to 3.5 MVA of load remain unsupplied for up to 8 hours for the loss of a single transformer. This means that more than 1,330 customers would need to be shed for up to 8 hours for a transformer outage at peak load time. This peak is expected between Noon and 8pm. The Uraidla load forecast in 2013/14 is 21.0 MVA, during peak load conditions, up to 3.2 MVA of load remain unsupplied for up to 8 hours for the loss of a single transformer. This means that more than 9,080 customers would need to be shed for up to 8 hours for a transformer outage at peak load time. This peak is expected between Noon and 8pm. In addition, in the event of a loss of the 66kV Line from Mt Barker Connection Point which supplies both Balhannah and Uraidla Substations, limited alternate 66kV supply exists from the Southern Suburbs Network to supply this load. 5.2 Demand Management Value The following table indicates the amount of load reduction required in each year and the available $/kva amount available to make Demand Management viable. To allow for oversubscription in order to guarantee the load reduction required, a range of deferral benefit values are provided. The stated benefits also include an allowance to cover administrative costs. Year Table 1 $ per kva available for Demand Management Load Reduction Required (kva) Typical number of Days at Risk $/kva available per year for DM 2013/14 3,500 7 75 125 2014/15 4,800 10 60 100 2015/16 6,200 24 50 85 Page 7 of 8
5.3 Demand Management Options Considered Various Demand Management technologies were considered to determine their viability to assist in reducing the demand in the constrained area. These DM options were evaluated for both technical feasibility as well as cost effectiveness. 5.3.a Standby diesel generators Establish contracts with customers who have standby diesel generators on their premises and utilise the generators at peak load times or install peak lopping generators at Balhannah Substation to reduce load at peak times. This option is unviable there are not enough large customers with standby diesel generators to make this option feasible. 5.3.b Install power factor correction This option is not technically feasible as there are not enough large customers supplied by the Balhannah substation to make power factor correction viable. 5.3.c Retrofit commercial lighting with efficient lighting. Upgrade existing commercial fluorescent lighting to T5 lighting. Based on the upgrade of a 400W fluorescent bank with a 2x 80W efficient bank provides the equivalent lumen output. The demand saving per bank is 240W. The estimated cost for this option is $2,500/kVA. Significant disruption to the customer while the retrofit is carried out can be expected, which may influence the number of willing participants. 5.3.d Peak load control direct load control Direct load control technology may be available where tripping many small air conditioning units supplied from a single distribution transformer can be performed. Recent experiences have shown the costs to range from $300 to $800/kVA. 5.3.e Peak load control curtailable load Establishing a contract with one or more large customer s involving turning power supply off to part of their business or shifting load to off peak times was investigated. There is no suitable customer with a load large enough to individually impact the network identified for this option in this case. 5.3.f Residential compact fluorescent lamp (CFL) program This option was deemed not relevant due to peak load conditions occurring in daylight hours. Load contribution from residential housing lighting during daylight hours is believed to be minimal. 5.3.g Thermal storage systems A recent installation at a suitable site revealed a saving in load of 150kVA. The expected cost for this type of installation ranges from $1,000-1,600/kVA. Smaller scale installations have also been trialled, and are still very much in the development stage (More expensive per kva). 5.3.h Energy Storage Use of energy storage technology such as flow batteries is typically in the order of $6000 per kva. 6. CONCLUSION Based on the Demand Management options considered it is not possible that sufficient Demand Management could be implemented to achieve a demand reduction to make project deferral via either of the aforementioned methods technically or economically viable. The constraint on the Balhannah and Uraidla 33kV substations has failed the Reasonableness Test and a Request for Proposal (RFP) will not be issued. Page 8 of 8