Markets, Policy, and Computation

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    Joint Expansion Planning for Natural Gas and Electric Transmission with Endogenous Market Feedbacks
    ( 2018-01-03) Bent, Russell ; Blumsack, Seth ; van Hentenryck, Pascal ; Borraz Sanchez, Conrado ; Backhaus, Scott
    The recent and rapid shift towards the increased use of natural gas for power generation has convinced both power grid operators and regulators that additional coordination between electric power and natural gas transmission is needed to ensure the reliable operation of both systems. We report on an ongoing modeling effort for joint gas-grid expansion planning. We develop a Combined Electricity and Gas Expansion (CEGE) planning model that determines least-cost network expansions for power and gas transmission in a way that endogenizes the effects of expansion decisions on locational costs for electric power and natural gas deliveries. The CEGE model, which leverages recent advances in convex approximations for large-scale nonlinear systems, is illustrated on a new gas-grid test system topologically similar to the Northeastern United States. We show that the CEGE model is computationally tractable, and how the model might be used to jointly plan infrastructures to avoid extreme events such as the coincident gas-electric peaks experienced during the 2014 polar vortex.
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    Market Based Intraday Coordination of Electric and Natural Gas System Operation
    ( 2018-01-03) Rudkevich, Aleksandr ; Zlotnik, Anatoly ; Ruiz, Pablo ; Goldis, Evgeniy ; Beylin, Aleksandr ; Hornby, Richard ; Tabors, Richard ; Backhaus, Scott ; Caramanis, Michael ; Philbrick, Russ
    This paper outlines the design of an intraday market-based mechanism for coordinated scheduling of gas-fired electric generation, intra-day natural gas purchases, sales and deliveries, and underlying pipeline operation. The mechanism is based on an exchange of physical and pricing data between participants in each market, with price formation in both markets being fully consistent with the physics of energy flow. In organized nodal electricity markets, prices are consistent with the physical flow of electric energy in the power grid because the economic optimization used to clear the market accounts for the physics of power flows. In the gas system, the proposed physical operation and pricing will be based on the transient optimization approach that accounts for physical and engineering factors of pipeline hydraulics and compressor station operations. The paper provides theoretical foundations for the market mechanism.
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    The Use of Marginal Energy Costs in the Design of U.S. Capacity Markets
    ( 2018-01-03) Moye, Robert ; Meyn, Sean
    This paper surveys the development of marginal cost theories used in the optimal allocation of scarce resources, and examines the application of these theories to current-day electricity capacity markets. The different approaches in use today to ensure grid reliability and incentivize new resources are examined. Market challenges are surveyed, as well as empirical findings that suggest that current market approaches do not provide proper incentives. We conclude that the so-called "missing money" is not missing because of defects in market designs, or so-called administrative actions---money to incentivize investments is missing due to a misapplication of marginal cost theory.
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    Spurious Critical Points in Power System State Estimation
    ( 2018-01-03) Zhang, Richard ; Lavaei, Javad ; Baldick, Ross
    The power systems state estimation problem computes the set of complex voltage phasors given quadratic measurements using nonlinear least squares (NLS). This is a nonconvex optimization problem, so even in the absence of measurement errors, local search algorithms like Newton / Gauss-Newton can become "stuck" at local minima, which correspond to nonsensical estimations. In this paper, we observe that local minima cease to be an issue as redundant measurements are added. Posing state estimation as an instance of the quadratic recovery problem, we derive a bound for the distance between the true solution and the nearest spurious local minimum. We use the bound to show that critical points of the nonconvex least squares objective become increasing rare and far-away from the true solution with the addition of redundant information.
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    The Estimation of Nodal Power Supply Reliability through the Network Connectivity by Complex Network Method
    ( 2018-01-03) Ren, Hui ; Wu, Yuhuan ; Watts, David ; Jiang, He ; Jiang, Nannan
    The paper studies the reliability of the power system from the perspective of node loads. The reliability of the whole system can be estimated by evaluating the power supply reliability of each node. A measure, "connectivity" observed at load node (Ci), is proposed. Ci is calculated through a recursion equation by evaluating the generation capacity that can be transferred from the further neighbor to the nearest neighbor of load node i. IEEE-30 bus system is taken as a test system. We calculated the index of 7 load nodes at 2 different load levels with different N-1 failures. The test results show that the variation of the index and that of the percentage load shedding at selected load nodes show good consistency.