1. Transformer Asset Management
Selwyn Braver
Dynamic Ratings Pty Ltd
Melbourne, Australia
April 20, 2017

2. Overview Equipment Categories Collecting the Data
Gauges
Electronic Temperature Monitors (ETM)
Transformer Management Systems (TMS)
Collecting the Data
Temperatures: Methods of measurement
Converting Data to Information
Getting the Right Information to the Right People
Converting Information into Benefits
April 20, 2017

3. Changing Environment
Utilities have entered an era where cost and competitiveness are business drivers
The capacity in existing assets must be driven harder than in the past without loss of customer service or reliability
Networks have expanded and become more difficult to operate
Asset Managers, Planners, Operators and Maintenance staff need better tools - management based on facts, not assumptions
The environment in which we work is becoming increasingly more complex. Not only from a technical perspective, but also due to financial and regulatory pressures.
Engineers operating in electricity utilities are facing different issues from the past.
Some of the major issues are:
Cost competitiveness is becoming increasingly important.
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As a utility, we cannot afford to lower our standards of customer service and reliability of supply and yet at the same time we MUST drive the assets which we have harder. In other words, we want to use our existing expensive assets (like transformers) for longer and to their full capacity.
We need to manage our assets better and know more about their operating history.
Because we are loading our transformers higher than ever before in day to day operations, our networks are becoming harder to operate and our previous experience of the operating life of assets on the network will have to be re-examined.
Everyone involved in operating the network will need better tools if we are going to drive the assets harder and return better results for our shareholders and stakeholders.
Importantly as well, all the major players the planners, operators and maintenance staff must be running the network process with the same strategies. It would be far from ideal if the planners in the utility were utilising highly sophisticated computer models for the rating of transformers and the operators of the network had the relatively unsophisticated tools of the past. For example they may have no tools at all or perhaps a simple analogue or two from a SCADA system.
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April 20, 2017

4. Justification for Online Control & Monitoring
Increase the availability and capacity of power transformers
Redirection of time and/or operational based maintenance to condition based maintenance
Asset and life management
Failure cause analysis
April 20, 2017

5. Benefits of TMS
Major cost savings possible by deferring plant upgrades-achieved using dynamic rating to work assets harder
Further large cost savings by reducing risk and frequency of unplanned outages, achieved using dynamic rating and condition monitoring together to avoid plant failures, expensive repairs, loss of revenue
April 20, 2017

6. Benefits (cont)
Longer life of assets, achieved by reliability centred maintenance based on condition monitoring
Reduced maintenance costs, avoiding unnecessary maintenance inherent in fixed interval scheduling
Objective data for planning
Insurance premium reductions
April 20, 2017

7. Equipment Categories: Gauges
Temperatures
April 20, 2017

8. TMS TEMPERATURE MONITOR VS CONVENTIONAL WTI OTI
April 20, 2017

9. Electronic Temp Monitoring (ETM) “Basic”
Temperatures
April 20, 2017

10. Electronic Temp Monitoring (ETM) “Advanced”
Temperatures
Cooling System
LTC Monitoring
April 20, 2017

11. Transformer Management System (TMS)
Temperatures
Cooling System
LTC Monitoring/Control
Load Monitoring
Connection to other IEDs
April 20, 2017

12. Evolution of Transformer Controls
Control House
Control
Alarms
Communications
Temp
Expert
Software
Protocol
Converters
Data
Logging
Event
Recording
Temp
LTC
Control
Oil
Level
Condition Monitoring
LTC
Monitoring
DGA
Moisture
Direct
Winding
Temp
Other
Monitoring
Input
LTC
Paralleling
Sudden
Pressure
April 20, 2017

13. Overview of TMS Integrated microprocessor-based system with:
Dynamic Rating - real time thermal limit predictive loading capacity-real time aging
Monitoring -data acquisition & storage of all data for the entire transformer
Operating data: volts, amps, watts, vars, tap position, temperatures - ambient, oil and winding hot spot, etc
Condition monitoring probes - DGA, water in oil, bushing and OLTC condition
Control –Voltage(OLTC) and Cooling
Communication –Web server(at sub or LAN / WAN), IU, SCADA, modem, TCP/IP, DNP 3.0, Modbus
April 20, 2017

14. Converting Data into Information
Dynamic Transformer Rating 60
2 Hr Overload 50 FA 40 FA 30 OA
OA/ FA/FA = 30/40/50 (ONAN/ONAF/ONAF)
PTLoad (software to calculate overload)
DRMCC is specifically tuned to each transformer, as apposed to an average transformer of same value.
Actual ambient is measured.
Top oil temp is monitored.
DRMCC will automatically derate loading if a cooling bank/pump/fan motor is lost.
Thermal Model
Tuned to this specific S/N Transformer
Ambient
Actual Ambient
Top Oil Temp
Starting Top Oil Temp
Cooling System Health
Fans/pumps/breakers/contactors
April 20, 2017

15. April 20, 2017

16. What is Dynamic Rating? Real-time on-line calculation of loadability
Based on thermal model (modified IEC / IEEE) Guide for Loading Mineral-Oil-Immersed Transformers IEEE C57.91,IEC354
Transformer thermal parameters from design or test
Retrofits, thermal model from recorded site data and mathematical modeling
Uses measured ambient & top oil temperatures, tap position & load current
Can typically enable 20% increased loading with reduced risk and number of outages
April 20, 2017

17. Collecting the Data Data typically collected LTC (OLTC) Top Oil Temp
Position
Temperature
LTC Motor Current
Oil Level
Sudden Pressure
Vacuum Bottle Fail
Filter clogged/excessive pressure
The following if equipment fitted
DGA
Dissolved Moisture, MIO
Direct Winding Temperatures
Bushing PF
Partial Discharge
Top Oil Temp
Winding Hot Spot (if fibre probes)
Load
Amps per phase
Voltage
Ambient Temperature
Cooling Status
Operating Status
Amp Draw
Contactor Operation
Control Switch Positions
Alarm Contacts & Ancillaries
Sudden Pressure
Pressure Relief
Main Tank Oil Level
Nitrogen Pressure
April 20, 2017

18. Converting Data into Information
Information typically calculated/determined
Alarm Contacts & Ancillaries
Oil Leak
Nitrogen Leak
LTC (OLTC)
Time Since Last Through Neutral
LTC Delta T
LTC Counter Total
LTC Counter Per Tap Position
LTC Contact Wear (I Squared)
LTC Drive System Fail
Filter clogged/excessive pressure
Internal Transformer Problem/Threshold monitoring
DGA
Dissolved Moisture, MIO
Direct Winding Temperatures
Bushing PF
Partial Discharge
Winding Hot Spot (for all windings)
Forecasted Temperatures
Ultimate WHS
Ultimate Top Oil Temp
Insulation Loss of Life
Dynamic Rating
Max Load
Max Time
“What If”
Load
Amps*
Voltage*
Watts
Vars
Cooling Status
Cooling Efficiency Problem
Fan or Pump Fail
Contactor Fail
Control Switch Not In Auto
April 20, 2017

19. Accurate WHS Determination
Methods of Winding Hot Spot (WHS) Measurement
Simulated (inaccurate, local EM or analog measurement)
Calculated (via DRMCC using the customized thermal model)
Direct Measurement (fibre probes in coordination with DRMCC)
The DRMCC “calculated” and the “direct measurement” methods complement each other in specific conditions
April 20, 2017

20. Insulation Aging Rate
April 20, 2017

21. Cooling System Features
Cooling Control
- dynamic predictive control of the operation of fans and pumps
Cooling System Monitoring
Continuously confirms operation of each fan and pump.
Cooling System Exercise
Exercises cooling system and checks the operation of fans & pumps.
Run Hour Meter for Each Cooling Stage
Ensures equal mechanical wear on all fans/pumps.
April 20, 2017

22. Voltage Control Modes Independent Master Follower-(fibre optic comms)*
Circulating Current-(fibre optic comms)*
VAr Sharing
Reverse Reactance
SCADA control and SCADA set points
*between transformers/DRMCCs
April 20, 2017

23. Gathering Downstream Data, Storage, Interpretation & Communication
Condition Monitoring Equipment
-DGA
-MIO
-PD
-Tan Delta
-Fibre optic temperature

24. Getting the Right Information to the Right People
Connect to the front with serial cable using terminal server.
Connect to the LAN/WAN with ethernet using internet explorer
Connect to SCADA using DNP, or Modbus using RS-232, RS-485 or fiber
Other options: Modem (Pacificorp has an installation in UT monitored from OR via modem).
Wireless from Xformer to control room.
April 20, 2017

25. SUGGESTED SCENARIO Management Substation Environment April 20, 2017
SCADA Control centre
Utility intranet
Control room F
ibre optic cable
and Comms
Retrofit cubicle
Transformer
Condition sampling device
Management
Environment
April 20, 2017

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28. April 20, 2017

29. Benefits of TMS
Major cost savings possible by deferring plant upgrades-achieved using dynamic rating to work assets harder
Further large cost savings by reducing risk and frequency of unplanned outages, achieved using dynamic rating and condition monitoring together to avoid plant failures, expensive repairs, loss of revenue
April 20, 2017

30. Benefits (cont)
Longer life of assets, achieved by reliability centred maintenance based on condition monitoring
Reduced maintenance costs, avoiding unnecessary maintenance inherent in fixed interval scheduling
Objective data for planning
Insurance premium reductions
April 20, 2017