23 problems
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Distinct convergence rates for scenario generation and Fleming–Viot rare-event sampling
The two approaches are scenario generation and rare-event sampling with Fleming–Viot biasing for robust stochastic programming; let the number of scenarios tend to infinity, and co…
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Conjecture on the superiority of successive branch reduction for larger mixed-integer nonlinear SDNR problems
A stochastic distribution network reconfiguration (SDNR) problem is a mixed-integer nonlinear optimization problem whose constraints and decision variables include binary switch va…
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Hiskens's complementary impasse-surface avoidance conjecture for static loads
Let be the set of load buses, with and denoting the active-power load parameters and and denoting the reactive-power load parameters…
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Hiskens's impasse-surface avoidance conjecture for static-load power systems
Suppose Assumption 1 and Assumption 2 hold. Consider a differential-algebraic equation system with all loads purely static. Let denote the generator buses and the…
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Hiskens's generic impasse-surface avoidance conjecture for power-system DAEs
Let a power-system differential-algebraic equation model satisfy the assumptions used in the paper, and let the condition obtained for the specific four-bus system be given. Hisken…
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Generalization of the approach to large-dimensional power flow systems
The two-bus power flow system uses the load parameter and the associated maximization formulation to identify a maximal saddle-node bifurcation point. Generalization conjecture. Th…
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The challenge of transitioning from synchronous-machine-dominated to grid-forming-converter-dominated grids
A synchronous machine (SM) is a conventional generator, while a grid-forming converter (GFC) is a power converter that can establish the grid voltage and frequency. Consider a tran…
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Combined linear optimization conjecture for inertia and primary control
Combined linear optimization conjecture. For an abrupt power loss, the optimal placement of a fixed total amount of inertia and primary control that minimizes is ob…
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The state-variation conjecture for probing-grid Jacobians
State-variation conjecture. Probing the grid to effect larger state variations across should yield smaller condition numbers for…
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The adjacency-polytope conjecture for power flow equations
Let be a graph with , and let be the system of algebraic load flow equations in the variables , where…
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Tightened voltage stability index approximation bound
Let a power distribution network have one slack bus and PQ loads, and let it be described by the relaxed branch flow model. In the voltage stability region, set … where…
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Conjecture on the cause of differing computational scaling in the Polish and 30-bus models
Scaling-performance conjecture. The better performance observed in the 30-bus model may be related either to the greater density of the Polish system, which requires linearizing a…
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Conjecture on further loss reduction through judicious distributed control design
Consider distributed averaging control for secondary frequency regulation in a microgrid, where the communication graph and controller parameters may have degrees of freedom beyond…
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Approximate AC power-flow feasibility is in NP
Consider an approximate version of the lossless AC power-flow feasibility system in which the equation … is replaced by … where is part of the input. Approximate feasi…
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Exactness of the sufficient infeasibility test
Let the sufficient infeasibility test cited in the source be a test that guarantees power-flow infeasibility but is not asserted there to be necessary, and suppose the convex appro…
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Power-flow solutions in the convexity domain
Let the convexity domain be the domain on which the energy function is convex, and let the power-flow equations be the equations defining power-flow solutions. Convexity-domain exi…
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Stable power-flow solutions in the principal region
Let the principal region be the region enclosed by the Principal Singular Surface for a lossless power network, and call a power-flow solution stable when it is dynamically stable.…
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The normal-operating-conditions conjecture for SDP relaxation exactness in OPF
Normal-operating-conditions conjecture. Under normal operating conditions, the SDP relaxation is tight.
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Multiple-bifurcation explanation for higher nullity in power-flow dual matrices
Let be the matrix in the dual formulation of the power-flow optimization, and consider systems for which … The multiple-bifurcation explanation conjecture. Similar exp…
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Coincident-bifurcation conjecture for the nullity of the power-flow dual matrix
Let denote the minimum slack-bus voltage, and let be the matrix in the dual formulation of the power-flow optimization. Suppose that more than two so…
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Separated-bifurcation conjecture for the nullity of the power-flow dual matrix
Let denote the minimum slack-bus voltage, and let be the matrix in the dual formulation of the power-flow optimization. Suppose the minimum slack-bus…
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Bifurcation-location conjecture for the nullity of the power-flow dual matrix
Let be the matrix in the dual formulation of the power-flow optimization, and let the controlled voltages be decreased so that solutions of the power-flow equations me…
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Conjecture on insignificant instance-to-instance fluctuations in typical power-system regimes
Let instances of the system, differing for example in their configurations of load, be drawn from a reasonable distribution representing a typical regime, such as a morning of an o…