1. Borah Mitigators Remedial Action Scheme for the Borah West Path Sponsored by: IDAHO POWER Team Members: Kyle Jones Mark Magee Jason Rippee

2. Project Background Idaho Power wants to add to a remedial action scheme for the Borah West Path, located in Southern Idaho. This revised scheme is to include the impact of ambient temperature changes to the system (to increase the ampacity of the lines). Re-vamp the mitigation scheme of the system based on an increase in transmission current for ambient temperatures below nominal. Idaho Power wants to add to a remedial action scheme for the Borah West Path, located in Southern Idaho. This revised scheme is to include the impact of ambient temperature changes to the system (to increase the ampacity of the lines). Re-vamp the mitigation scheme of the system based on an increase in transmission current for ambient temperatures below nominal.

3. Deliverables Simulation of the modified scheme in Power World 11 Simulation of the modified scheme in Power World 11 Provide a set of options for mitigation to the customer that provide an increase in load capacity/transmission capability. Provide a set of options for mitigation to the customer that provide an increase in load capacity/transmission capability. Maximize power transfer across Southern Idaho for all conditions (ie. lines faulted or lines outages) Maximize power transfer across Southern Idaho for all conditions (ie. lines faulted or lines outages)

4. Insights to the Problem The first slide demonstrates the current limit conditions used on the Borah West Path. The first slide demonstrates the current limit conditions used on the Borah West Path. The second slide gives a flow chart of what remedial action is to be taken for the limits exceeded. The second slide gives a flow chart of what remedial action is to be taken for the limits exceeded. The third slide shows the remedial action to be taken for each set of Borah West and Midpoint East transfer levels. The third slide shows the remedial action to be taken for each set of Borah West and Midpoint East transfer levels.

5. Midpoint East flow, MW (pre-disturbance) 1 st Bridger Unit to trip (MW) 2nd Bridger Unit to trip (MW) W/ 1 unit trip = A = 1929 - 6.64*degC + 0.45 * 1 st unit MW Calculated Borah West limits W/ 2 unit trips = B = 1929 – 6.64*degC + 0.45 * (1 st + 2 nd unit MW) W/ 1 unit trip &bypass both series caps = Ac = 1293 -3.93*degC + 0.2384 * 1 st unit MW + 0.484 * Midpoint East flow (MW) W 2 unit trip & bypass both series caps = Bc = 1293 – 3.93*degC + 0.2384 * (1 st + 2 nd unit MW) +0.484*Midpoint East flow (MW) W/ 1 unit trip &bypass 1 series cap = A C/2 = A + (Ac-A)/2 W/ 2 unit trip &bypass 1 series cap = B C/2 = B + (Bc-B)/2 where Ta = actual ambient temperature in deg C ( Summer time - 2005)

6. Is BW > ~1100MW yes no No action taken Midpoint East scheme will trip 1 Bridger Unit Is A C/ 2 > A ? Critical Outage has occurred: Kinport – Midpoint and Borah – Adelaide – Midpoint #1 or #2 345kV lines No action taken no yes Is BW > A yes No action taken no Is BW > A C/ 2 Bypass Burns Series Capacitor no No action taken yes Is BW > A C no Bypass Midpoint Series Capacitor No action taken Is BW > B C no Trip 2 nd Unit @ Bridger yes No action taken yes Initiate Bridger Redispatch or / and load curtailment to eliminate overloads on remaining Borah – Adelaide – Midpoint 345kV line and AMFLS – Adelaide and AMFLS – Plst Valley 138kV lines X33 Is BW > A No action taken yes no X33

8. Needs Analysis The Borah West Path has some of its elements reach their thermal limit following the loss of critical transmission lines. Compensating for thermal effects will increase the load carrying capacity in lines and may avoid dropping loads during peak demand. The Borah West Path has some of its elements reach their thermal limit following the loss of critical transmission lines. Compensating for thermal effects will increase the load carrying capacity in lines and may avoid dropping loads during peak demand. Provide a mitigation scheme for the case of N-1 and N-2 conditions, which means we need to mitigate single line and double line losses. Provide a mitigation scheme for the case of N-1 and N-2 conditions, which means we need to mitigate single line and double line losses.

9. Constraints Keep voltage deviation after one line loss below 5% of the normal operating voltage, and below 10% for a two line loss. Keep voltage deviation after one line loss below 5% of the normal operating voltage, and below 10% for a two line loss. Under normal conditions conductor temperatures should not exceed 80 degrees Celsius. Under normal conditions conductor temperatures should not exceed 80 degrees Celsius. Outage conditions should not exceed 90 degrees Celsius for more than 15 minutes. Outage conditions should not exceed 90 degrees Celsius for more than 15 minutes. In order of importance: In order of importance: 1) Avoid tripping Generators at all cost! ( lots of money) 2) Avoid dropping loads. 3) Avoid shorting series capacitors (not that big of deal). Utilize thermal capabilities if possible. Utilize thermal capabilities if possible.

10. Project Learning Learn how thermal limits are related to the ampacity of the lines using IEEE standard publication 738-1993. Learn how thermal limits are related to the ampacity of the lines using IEEE standard publication 738-1993. The ratio of the new ampacity to the old ampacity is proportional to the sqrt(new temp rise/ old temp rise) The ratio of the new ampacity to the old ampacity is proportional to the sqrt(new temp rise/ old temp rise)

11. Questions?