20,217 research outputs found
A Primal-Dual Algorithm for Link Dependent Origin Destination Matrix Estimation
Origin-Destination Matrix (ODM) estimation is a classical problem in
transport engineering aiming to recover flows from every Origin to every
Destination from measured traffic counts and a priori model information. In
addition to traffic counts, the present contribution takes advantage of probe
trajectories, whose capture is made possible by new measurement technologies.
It extends the concept of ODM to that of Link dependent ODM (LODM), keeping the
information about the flow distribution on links and containing inherently the
ODM assignment. Further, an original formulation of LODM estimation, from
traffic counts and probe trajectories is presented as an optimisation problem,
where the functional to be minimized consists of five convex functions, each
modelling a constraint or property of the transport problem: consistency with
traffic counts, consistency with sampled probe trajectories, consistency with
traffic conservation (Kirchhoff's law), similarity of flows having close
origins and destinations, positivity of traffic flows. A primal-dual algorithm
is devised to minimize the designed functional, as the corresponding objective
functions are not necessarily differentiable. A case study, on a simulated
network and traffic, validates the feasibility of the procedure and details its
benefits for the estimation of an LODM matching real-network constraints and
observations
An Optimal and Distributed Method for Voltage Regulation in Power Distribution Systems
This paper addresses the problem of voltage regulation in power distribution
networks with deep-penetration of distributed energy resources, e.g.,
renewable-based generation, and storage-capable loads such as plug-in hybrid
electric vehicles. We cast the problem as an optimization program, where the
objective is to minimize the losses in the network subject to constraints on
bus voltage magnitudes, limits on active and reactive power injections,
transmission line thermal limits and losses. We provide sufficient conditions
under which the optimization problem can be solved via its convex relaxation.
Using data from existing networks, we show that these sufficient conditions are
expected to be satisfied by most networks. We also provide an efficient
distributed algorithm to solve the problem. The algorithm adheres to a
communication topology described by a graph that is the same as the graph that
describes the electrical network topology. We illustrate the operation of the
algorithm, including its robustness against communication link failures,
through several case studies involving 5-, 34-, and 123-bus power distribution
systems.Comment: To Appear in IEEE Transaction on Power System
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