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Transformer Load Monitoring

Transformer Load Monitoring. Status Report and Benefits Summary 7/13/00. Ameren-UE – where they were. Home grown application to predict transformer loads based on interval data from data recorders installed at 200 different locations based on customer segment.

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Transformer Load Monitoring

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  1. Transformer Load Monitoring Status Report and Benefits Summary 7/13/00

  2. Ameren-UE – where they were • Home grown application to predict transformer loads based on interval data from data recorders installed at 200 different locations based on customer segment. • TLM data from the predictive algorithms set purchasing practices and construction guidelines. • 2 years ago, Ameren-UE was considering improving the predictions from their TLM program due to suspicions that the system was overbuilt.

  3. Ameren-UE – where they were • Options to improve TLM output: • Increase sample size – significant cost vs. unknown benefit • Use daily metering reading data – significant development task vs. unknown benefit • Ameren-UE expected benefit through lower capital expenditures. • CellNet suggested SLS concept after discussions with distribution engineers and management.

  4. Ameren-UE – what they achieved • Prototype one district of 50,000 meters and manually review data. • Results of prototype: • Identified 10+ overloaded transformers • Identified transformer/meter mismatches in AM/FM • Determined that TLM predictions were 70% too high • Preliminary results were declared a success and implementation plans for the full service were initiated with a goal to complete prior to Summer, 1998

  5. Ameren-UE – what they achieved • Over 20 snapshots retrieved for both summer and winter peaks • Immediate benefits in reduced capital budgets, improved customer service and reduced outages: • 20% savings in capital purchases of transformers ($12 million annual budget reduced to below $10 million) due to purchase of smaller transformers. • By no longer purchasing transformers with CSP option is saving $100 per transformer. • Re-use of larger transformers to compensate for material shortages have reduced customer down time • Identification of 250+ overloaded transformers resulted in reduced outages and lower labor costs • Longer term benefits through change in purchasing standards and “poor man’s SCADA”.

  6. Ameren-UE – future plans • Poor man’s SCADA • Ameren-UE intends to push the SLS capability to the rural area where substations are not automated. • Snapshot information will first be used to analyze circuit and transformer loads. • More regular information (weekly?, daily) will be obtained to monitor un-automated substations. • Selective application of SLS • Ameren-UE would like to begin using the load information by substation, circuit, etc. to analyze their system for phase imbalances, before and after reconfiguration activities and line loss studies.

  7. Other CellNet Users – Status and Plans • KCPL • KCPL has no transformer monitoring and uses simple sizing guidelines. Overloaded transformers are addressed in response to low voltage and outage conditions reported by the customers. • KCPL has been trying to implement a distribution engineers workstation for the last few years with no success. • KCPL wants to implement SLS soon as they believe the benefits are tremendous (“We don’t need to build a business case”). • KCPL is limited by their AM/FM at this point as the transformer to meter binding is only about 75% accurate. • NSP • NSP has no plans for implementing SLS due to IT resources and lack of focus in the DA area.

  8. Other CellNet Users – Status and Plans • PSE • PSE has a home-grown algorithm which analyzes the monthly meter reads to identify overloaded transformers. PSE uses simple sizing guidelines to determine transformer sizes upon install. • PSE is planning to implement SLS within a year as they feel that the low failure rate of their transformers indicates an overbuilt system. • PSE also does not require a business case (“It’s a no brainer”) to justify SLS.

  9. General Business Case • 20% reduction in annual capital budget allocated to transformer purchases • $100 per transformer reduction as CSP option is no longer required. • 50% reduction in transformer inspections (assume 5% of population is inspected at $50 per inspection) • Reduced customer outage due to overloaded transformer (one-time benefit based on 0.25% of transformers) • Improved transformer/meter connectivity (one-time benefit).

  10. System Load Snapshot • The SLS application utilizes the TOU capability of the CellNet system. • Not available for any meter on a TOU billing rate. (May not be available for any meter on a demand rate as well, but this is a process issue as opposed to a technical issue). • Limited to 3 configurable intervals and two different “seasons” • Default configuration is 4:00-5:00PM, 5:00-6:00PM and 6:00-7:00PM during Summer and 5:00-6:00AM, 6:00-7:00AM and 7:00-8:00AM during Winter. • Any three intervals which are a multiple of 5 minutes can be used.

  11. System Load Snapshot • Operation • PPL identifies a peak day, or day of interest, for which snapshot information is required. • PPL notifies service provider by 8:00 AM on the day following the day of interest. • Service provider provides ASCII file two days after notification with MeterID, TransformerID, kWh in each of the three intervals, and a flag to indicate the reliability of the data for each meter.

  12. System Load Snapshot • Limitations and Issues • 20 to 30% of the data provided will have a flag indicating potential missing or incomplete data. • PPL must provide accurate transformer to meter binding information to service provider. • The service provider conducts the read for SLS data in the afternoon after the regular billing meter read has completed. Consequently, more than a few SLS requests in a month affects the service provider’s ability to use the system for other purposes (both maintenance and non-PPL revenue applications). • The SLS application has the result of swamping the distribution engineer with data. The first set of data is very important as it is the first detailed look at the overall system loading. PPL needs to ensure that adequate resources are available for the analysis of this data.

  13. Summary • SLS benefits are clear to all current CellNet system users. • Status of AM/FM systems and the accurate binding of transformer to meter is the gating item to implementation. • 20% annual savings in capital budget with other softer benefits are conservatively achievable. • Other benefits beyond transformer load monitoring are apparent, but not validated.

  14. Transformer Monitoring – Misc. • Most of the interviewees did not see value in metering at the transformer beyond theft and outage management. • Both PSE and Ameren-UE used 1% theft in their business cases and feel that the preliminary analyses justify a higher theft number. • Metering at the transformer would significantly improve their business case for theft as the percentage identified would increase to almost 100% and the percentage recoverable would increase as well. • Reliable outage detection and restoration notification at the transformer was seen as a huge benefit by all of the people interviewed. Each said that they could build a viable business case on reliable data. • Metering the transformer for volts, amps and power factor was not seen as a large benefit and most viewed this as “too much information”.

  15. Contacts • Larry Rushing – Manager for Distribution Engineering • (314) 554-2412

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