Imperfections in Coordinating Facility Ratings between Operations, Planning and Maintenance

Transcription

1 Imperfections in Coordinating Facility Ratings between Operations, Planning and Maintenance Nicholas Klemm Western Area Power Administration Rocky Mountain Region March 2012

2 Organizational Overview Western is one of the federal power marketing agencies Market federal hydro power in the western U.S. RMR covers Colorado, Wyoming and parts of Nebraska Registered as a BA and TO with NERC/WECC 5400 miles of transmission lines 60+ substations Operating voltages of 345-kV, 230-kV and 115-kV

3 What are facility ratings? Ratings of the terminal and line or transformer circuit equipment which determine the ability to transfer power across that circuit Ratings of equipment could be based on: Thermal rating of the equipment Degradation of insulation Annealing or tempering Separation of connections Clearance to ground or other objects Physical loading (e.g. ice loading)

4 Terminal Equipment Power Transformers Power Circuit Breakers Disconnect Switches Wave Traps Bushing CT s Metering CT s Protective Relay Settings Secondary current carrying circuits

5 Terminal Equipment Items to consider Rating Factors (RF) of CT s RMR strives not to rely on RF Ring bus or multiple breaker applications Do you rate the terminals based on the ring closed or broken?

6 Conductor loading NESC clearances Lines Need to determine the line design temperature Develop seasonal ratings and emergency ratings PRC utilizes 4-hour seasonal ratings 15-minute emergency ratings

7 Basic Process Flow Planning Design Maintenance Operations

8 Planning Responsibilities Study and identify future system needs Study existing system capacity Maintain spreadsheet of circuit and equipment ratings Determine circuit ratings Request increased circuit capacities

9 Design Responsibilities On new construction, design equipment to standards Line conductor thermal ratings Typical breaker/switch ratings 2,000 amp rating for 230-kV yards 1,200 amp rating for 115-kV yards

10 Maintenance Responsibilities Ensure that equipment is installed per design Increase CT ratios/relay settings as needed to meet desired circuit ratings Replace or modify terminal equipment to meet desired circuit ratings Add or modify line structures to meet desired circuit ratings

11 Operations Responsibilities Utilize the proper circuit ratings Develop loading alarms based upon the published ratings Notify Planning and Maintenance of real time loading issues that need to be corrected

12 NERC/WECC Compliance FAC Standards PRC Relay Loadability Facility Ratings Alert

13 FAC Standards FAC Develop ratings of equipment limiting element Describe the methodology Include normal and emergency ratings Consider design criteria and external conditions FAC Establish ratings (solely or jointly) Communicate those ratings

14 PRC Loadability In general, phase elements of relays must be set to 150% of circuit ampacity at 0.85 per unit voltage and 30 power angle Applies to all circuits (lines and transformers) operated at 200-kV and above Applies to designated circuits (by the PC) operated between 100-kV and 200-kV

15 PRC Loadability Relays must be set accordingly prior to increasing a circuit rating (200-kV and above) This needs to be coordinated carefully with Planning and Operations

16 Facility Ratings Alert All spans of BES transmission lines need to be checked for proper clearances Actual clearances must agree with design values used to determine line ampacity ratings IEEE 738 uses a line design conductor temperature Discrepancies may result in a reduction of circuit rating or require physical changes to the circuit

17 Processes Planning must clearly communicate the circuit ratings being used to both Maintenance and Operations Circuits must not be re-rated until all maintenance work is complete, including loadability relay settings Once circuit is re-rated, all entities must be notified

18 Entities requiring notification Planning Operations Real time studies Maintenance SCADA/Metering Affected foreign utilities WECC RC (Bulk Power Transmission Paths)

19 Tracking Process RMR using tracking and notification software application User inputs a notification for new equipment rating Process s all affected parties Requires a sign-off from each party Includes an internal representative for notification of foreign entities Is an after the fact process

20 Other methods of communication Verbal Easily forgotten No permanent record s May not include all the affected parties Can be archived for records Maintenance Inventory System Not always updated Data not always populated

21 Challenges Accurate record keeping of existing equipment data and ratings Planning Spreadsheets Prints Maintenance Inventory System Transformer and Transmission Line data Circuit ratings Seasonal 4-hour ratings 15 minute emergency ratings

22 Challenges Proper notification of new ratings Relay settings and other modifications need to happen first prior to new rating being published Sharing the new rating with other functional groups once any maintenance work is complete Coordinating new ratings with foreign entities

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28 Questions?