The uniform price algorithm is used for all short-term auctions (day-ahead and within-day). Through this mechanism, the allocation and price of capacity are determined in an open competition among shippers in one bidding round. Shippers bid for a maximum and minimum amount of capacity offering a surcharge. If the sum of all maximum amounts of capacity requested by shippers exceeds the available amount, capacity is allocated giving priority to the shipper(s) who offered the highest surcharge.
a. Shippers place a maximum of ten bids in one bidding round.
b. In their bids, shippers must set a (1) maximum amount of capacity they wish to buy, a (2) minimum amount of capacity they are willing to buy, and a (3) surcharge they wish to pay.
c. If the total sum of maximum requested capacity from all shippers is lower than or equal to the available capacity, all bidders received the maximum amount of capacity they requested at the regulated tariff.
d. If the total sum of maximum requested capacity from all shippers exceeds the available capacity (overdemand), capacity is allocated giving priority to the highest offered surcharge and setting the price by the lowest offered surcharge that receives capacity.
a. Fill Procedure: capacity is allocated giving priority to the shippers who offered the highest surcharges. The final price is, however, set by the bid with the lowest surcharge that receives capacity.
b. Kill Procedure: Just like in the Fill Procedure, capacity is allocated prioritizing the bids with the highest surcharges and setting the price to the lowest offer that receives capacity. However, in this case, one or more bidders requested a minimum amount of capacity, which exceeds the remaining product amount after the highest bidders got their requests. As a result, these bidders are excluded from allocation and other bidders may take their place. It is, therefore, possible that a uniform price auction will end with a surcharge lower than the one offered by a bidder, who has been excluded from allocation due to their unfulfillable minimum request of capacity.
c. Pro-rata Procedure: Just like in the Fill Procedure, capacity is allocated prioritizing the bids with the highest surcharges and setting the price to the lowest offer that receives capacity. In this case, however, after the bidders, who offered the highest surcharge, acquire capacity, two or more bidders offer the same surcharge for the remaining amount. Moreover, their minimum requests are below the total remaining capacity. Therefore, they will receive capacity on a pro-rata basis to avoid discrimination.
d. Underdemand or clearance: If the total sum of all requested maximum capacity is lower than or equal to the available capacity, the product is allocated at the regulated tariff.
Bundled Products: Competition
a. In the case of a network bifurcation, two bundled products are created and marketed simultaneously in different auctions.
b. However, if the maximum capacity of A is lower than the total sum of the capacity of B and C, the two auctions run in the competition until the constraint -- the amount of possible allocation at A -- is resolved.
INITIAL SITUATION: The total sum of all maximum demands exceeds the overall capacity limit of 100. Therefore, the auctions below are in competition.
INTERMEDIATE EVALUATION OF BIDS: First, the auctions are independently evaluated just as in a regular Uniform Price Auction.
a. In auction AC, Shipper 3 requested more capacity than the amount that remains after Shipper 2 receives its capacity (priority due to higher surcharge). Yet, since there is enough remaining capacity, Shipper 3 is not removed.
BID CONSOLIDATION AND RANKING: Then, to resolve the competition, the auctions are simultaneously evaluated.
b. Since Shipper 1 and Shipper 3 have offered the same surcharge and their minimum capacity requests are below the remaining amount, they will receive a pro-rata allocation.
DETERMINATION OF CLEARING PRICE: the clearing price will, as usual, conform to the lowest offered surcharge.