1,720,990 research outputs found
Increasing the region of attraction in DC microgrids
No full textBased on the port-Hamiltonian framework, this paper proposes a novel control scheme for stabilising the voltage in DC networks affected by (i) unknown ZIP-loads, i.e., nonlinear loads consisting of the parallel combination of constant impedance (Z), current (I) and power (P) load types, and (ii) unknown (but bounded) time-varying disturbances. Differently from the results existing in the literature, where restrictive (sufficient) conditions on the load parameters, voltage trajectory and voltage reference are assumed to be satisfied, this is the first paper (to the best of our knowledge) proposing a controller that relaxes such conditions and guarantees the exponential stability of the desired equilibrium point, whose region of attraction can be increased by simply tuning the control gains. In the case the network is affected by unknown time-varying disturbances, local input-to-state stability (l-ISS) is ensured. Furthermore, if non-ideal P-loads are considered, excluding the unrealistic possibility that the load absorbs infinite current when the voltage approaches zero, the aforementioned stability results hold globally.(c) 2023 The Author(s). Published by Elsevier Ltd. This is an open access article under the CC BY license (http://creativecommons.org/licenses/by/4.0/)
Event-triggered variable structure control
No full textThis paper presents a novel variable structure control (VSC) algorithm of event-triggered (ET) type, capable of dealing with a class of nonlinear uncertain systems. By virtue of its ET nature, the algorithm can be used as the kernel of a robust networked control system. The design objective is indeed to reduce the number of transmissions over the network. The proposed ET-VSC also guarantees appropriate robustness properties, even in the presence of delayed transmissions. It is theoretically analysed, proving that the sliding variable associated with the controlled system results in being ultimately confined into a boundary layer of prescribed amplitude. As a consequence, it is proved that the state of the considered uncertain nonlinear system is ultimately bounded as well. Moreover, a lower bound for the time elapsed between consecutive triggering events is provided, which excludes the notorious Zeno behaviour. Finally, the designed ET-VSC control scheme is satisfactorily assessed in simulation
Decentralized Temperature and Storage Volume Control in Multiproducer District Heating
No full textModern district heating technologies have a great potential to make the energy sector more flexible and sustainable due to their capabilities to use energy sources of varied nature and to efficiently store energy for subsequent use. Central control tasks within these systems for the efficient and safe distribution of heat refer to the stabilization of overall system temperatures and the regulation of storage units state of charge. These are challenging goals when the networked and nonlinear nature of district heating system models is taken into consideration. In this letter, for district heating systems with multiple, distributed heat producers, we propose a decentralized control scheme to provably meet said tasks stably
Distributed passivity-based control of DC microgrids
No full textIn this paper, we propose a new distributed passivity-based control strategy for Direct Current (DC) microgrids. The considered DC microgrid includes Distributed Generation Units (DGUs) sharing power through resistive-inductive distribution lines. Each DGU is composed of a generic DC energy source that supplies an unknown load through a DC-DC buck converter. The proposed control scheme exploits a communication network, the topology of which can differ from the topology of the physical electrical network, in order to achieve proportional (fair) current sharing using a consensus-like algorithm. Moreover, the proposed distributed control scheme regulates the average value of the network voltages towards the corresponding desired reference, independently of the initial condition of the controlled microgrid. Convergence to a desired steady state is proven and satisfactorily assessed in simulations
Advanced and optimization based sliding mode control: theory and applications
Full text linkA compendium of the authors' recently published results, this book discusses sliding mode control of uncertain nonlinear systems, with a particular emphasis on advanced and optimization based algorithms. The authors survey classical sliding mode control theory and introduce four new methods of advanced sliding mode control. They analyze classical theory and advanced algorithms, with numerical results complementing the theoretical treatment. Case studies examine applications of the algorithms to complex robotics and power grid problems. Advanced and Optimization Based Sliding Mode Control: Theory and Applications is the first book to systematize the theory of optimization based higher order sliding mode control and illustrate advanced algorithms and their applications to real problems. It presents systematic treatment of event-triggered and model based event-triggered sliding mode control schemes, including schemes in combination with model predictive control, and presents adaptive algorithms as well as algorithms capable of dealing with state and input constraints. Additionally, the book includes simulations and experimental results obtained by applying the presented control strategies to real complex systems
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
A Novel Control-Oriented Cell Transmission Model Including Service Stations on Highways
Full text linkIn this paper, we propose a novel model that describes how the traffic
evolution on a highway stretch is affected by the presence of a service
station. The presented model enhances the classical CTM dynamics by adding the
dynamics associated with the service stations, where the vehicles may stop
before merging back into the mainstream. We name it CTMs. We discuss its
flexibility in describing different complex scenarios where multiple stations
are characterized by different drivers' average stopping times corresponding to
different services. The model has been developed to help design control
strategies aimed at decreasing traffic congestion. Thus, we discuss how
classical control schemes can interact with the proposed \gls{CTMs}. Finally,
we validate the proposed model through numerical simulations and assess the
effects of service stations on traffic evolution, which appear to be
beneficial, especially for relatively short congested periods.Comment: This work is submitted to the 61st IEEE CDC 202
Output Consensus Control for Linear Port-Hamiltonian Systems
Full text linkIn this paper, we study output consensus of coupled linear port-Hamiltonian systems on graphs in the presence of constant disturbances, where couplings are allowed to be both static and dynamic. Utilizing port-Hamiltonian structures, we present dynamic controllers achieving output consensus where the consensus values are determined by the disturbances. Finally, the utility of the proposed controller is illustrated by applying it to current sharing of DC microgrids
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