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Unit Commitment and Economic Dispatch (UCED) with combined cycle (CC) units and AC power flow is an important problem to be solved by ISOs. The problem is difficult because of complicated transitions in CC units and highly non-linear AC power flows. Currently, to solve the problem, transitions among CC states are simplified and AC power flow is approximated with DC power flow. However, the resulting...
Many important problems in power systems, including unit commitment and economic dispatch (UCED), are modeled as MILP problems which are computationally intensive. Such problems can often be viewed as subsystems coupled by system-wide constraints. These structures have been efficiently exploited by surrogate Lagrangian relaxation and branch-and-cut to solve UCED problems with combined cycle units...
Combined cycle (CC) units are efficient because heat from combustion turbines is not wasted but is used for steam turbines. However, when state transitions are followed, CC units complicate the unit commitment and economic dispatch (UCED) problem. While branch-and-cut has been successful in solving UCED problems without considering CC units, transitions in one such unit affect the entire problem....
Most ISOs in the US minimize the total bid cost and then settle the market based on locational marginal prices. Minimizing the total bid cost, however, may not lead to maximizing the social welfare. Studies indicate that for energy only, payment cost minimization (PCM) leads to reduced payments for a given set of bids, and the “hockey-stick” bidding a less likely to occur. Since co-optimization of...
Current U.S. electricity markets select supply bids by using a bid cost minimization (BCM) auction mechanism but then settle the payments based on locational marginal prices (LMPs). The resulting payments can be significantly higher than the minimized bid costs. An alternative payment cost minimization (PCM) mechanism aiming to minimize the total payments has been discussed. Studies on single product...
Many optimization problems that frequently arise and have been extensively used in practice are modeled as linear mixed-integer programming problems. Among the many of such problems are transportation and assignment problems. In such problems, constraints that couple decision variables can be viewed as hyperplanes in their respective spaces. These hyperplanes frequently intersect at different angles...
In the current U.S. electricity market, supply bids are selected to minimize the bid costs, but are then paid at the marginal price, leading to significantly higher payments than the minimized bid costs. This gives rise to the “payment cost minimization” mechanism, which minimizes payments directly. We previously presented the “objective switching” method to solve single-product payment cost minimization...
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