2,041 research outputs found
Electric Vehicle Charging Station Placement: Formulation, Complexity, and Solutions
To enhance environmental sustainability, many countries will electrify their
transportation systems in their future smart city plans. So the number of
electric vehicles (EVs) running in a city will grow significantly. There are
many ways to re-charge EVs' batteries and charging stations will be considered
as the main source of energy. The locations of charging stations are critical;
they should not only be pervasive enough such that an EV anywhere can easily
access a charging station within its driving range, but also widely spread so
that EVs can cruise around the whole city upon being re-charged. Based on these
new perspectives, we formulate the Electric Vehicle Charging Station Placement
Problem (EVCSPP) in this paper. We prove that the problem is non-deterministic
polynomial-time hard. We also propose four solution methods to tackle EVCSPP
and evaluate their performance on various artificial and practical cases. As
verified by the simulation results, the methods have their own characteristics
and they are suitable for different situations depending on the requirements
for solution quality, algorithmic efficiency, problem size, nature of the
algorithm, and existence of system prerequisite.Comment: Submitted to IEEE Transactions on Smart Grid, revise
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
An Inter-molecular Adaptive Collision Scheme for Chemical Reaction Optimization
Optimization techniques are frequently applied in science and engineering
research and development. Evolutionary algorithms, as a kind of general-purpose
metaheuristic, have been shown to be very effective in solving a wide range of
optimization problems. A recently proposed chemical-reaction-inspired
metaheuristic, Chemical Reaction Optimization (CRO), has been applied to solve
many global optimization problems. However, the functionality of the
inter-molecular ineffective collision operator in the canonical CRO design
overlaps that of the on-wall ineffective collision operator, which can
potential impair the overall performance. In this paper we propose a new
inter-molecular ineffective collision operator for CRO for global optimization.
To fully utilize our newly proposed operator, we also design a scheme to adapt
the algorithm to optimization problems with different search space
characteristics. We analyze the performance of our proposed algorithm with a
number of widely used benchmark functions. The simulation results indicate that
the new algorithm has superior performance over the canonical CRO
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