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In the present work, the problem of controlling recipe transitions in a paper-making process is addressed, in order to avoid paper breakage and reduce paper waste. A decoupling control scheme is proposed, based on the control of speed differences between contiguous motors. This guarantees smooth and fast transitions of all the motor speeds along the production line. A front-tracking scheme is also employed, in order to adapt the recipe change to the actual plant conditions. A simulation model has been constructed and validated for a real industrial paper-making plant, and the effectiveness of the proposed control algorithm has been tested by means of simulation.

The paper discusses the prospects for the development and implementation of centralized ground traffic control systems at airports. The automatic control system can only work if there is accurate data on the location of mobile objects, which include both vehicles involved in the maintenance of aircraft and the aircraft themselves. In order to develop and test software for any specific centralized control system, the emulation mode should be used, in which the simulation model of the airport transport network works in conjunction with the real control software. In this case, one of the main functions of the simulation model is the generation of data streams that appropriately reflect the processes of movement of objects in the transport network of a specific airport. The paper describes a universal simulation program that allows one to simulate precisely described scenarios for the process in a transport network, which necessitates decision-making at the level of a centralized control system. The movement of objects in the model is accompanied by the recording of their coordinates in the Digital Twin. In this way, real streams of measurement data from various systems for determining the position of moving objects are modeled and stored.

This paper presents a centralized force/position controller for a heavy object manipulation in a multi-manipulator cooperative system. System dynamics of cooperative manipulating tasks comes from complex interaction of the object with robot manipulators and the environment. In this paper, focussing on the interaction effects in the system as well as by noting the role of imposed kinematics and force constraints, manipulator coordination and minimizing internal forces a pre-designed impedance behaviour between manipulator end effectors and the object is developed. The stability of the feedback system is then presented through passivity theorem and simulation results are finally provided with three manipulators handling the object supporting the relevance of the theoretical results.

This paper presents a uniform control strategy for the bidirectional ac/dc interlinking converter (BIC) in hierarchical controlled hybrid microgrid. The uniform control strategy unifies different control structures for multifunctional BIC in terms of power management, ac and dc voltage support. With the unified control structure, various triggering mechanisms for BIC mode-switch are not compulsory in response to the relevant scenario changes in the power network. Therefore, the negative consequences, such as unsmooth transition and system collapse due to the inaccurate or slower mode switch, can be avoided. Moreover, the uniform control strategy is also applicable for the hierarchical controlled hybrid microgrid, whose control architecture is typically comprised of the centralized and decentralized levels. This enables the communication fault ride-through capability and the impact from the communication failures can thus be mitigated. To sum up the above two features, the proposed control strategy is able to provide a smooth operation for the BIC without control mode switch in the event of unintentional scenario changes in power or communication network. To verify the validity of the proposed uniform control strategy, the controller hardware-in-the-loop experimental results have been provided in this paper. NRF (Natl Research Foundation, S’pore)

This paper deals with the design problem of multivariable Proportional-Integral-Derivative (PID) controllers for square and stable multivariable processes when a linear margin at the Nyquist plot is considered as robustness specification for each closed loop. A tuning method is developed based on the new concept of equivalent loop transfer function, which is proposed for centralized control and allows an independent design for each loop considering the interactions with the other loops through an iterative procedure. For the k-th loop, the PID parameters of the k-th column of the control matrix are calculated in each iteration by a linear programming optimization that maximizes the integral gains while fulfilling the robustness specification and achieving static decoupling. The method uses a frequency response array as representation of the process, which allows its applicability to systems with multiple time delays without requiring model reductions or approximations. The effectiveness of the method is illustrated by means of two simulation examples with dimensions $2 \times 2$ and $3 \times 3$ . Comparisons with other centralized control methodologies show that the proposed approach achieves similar or greater performance and a remarkable better disturbance rejection response.

The development of distributed energy resources in distribution networks has created a new concept called microgrids. Their control is one of the main development issues that must be addressed before any implementation process. In this paper, a comprehensive literature review of the main hierarchical control algorithms such as centralized, decentralized, and distributed, with a focus on the secondary level, with an emphasis on their main strengths and weaknesses are discussed and compared. Microgrid communication infrastructures allow the use of different control schemes for the secondary control layer which is given the importance of secondary control over the stable and reliable performance of microgrids, and the lack of comprehensive reference for researchers. Also, provides a literature review on current key issues regarding microgrid secondary control strategies with respect to communication network challenges. The issue of secondary control is discussed with a focus on challenges such as time delays. Also Distributed control methods at the secondary level to reduce the use of the communication network and subsequently reduce communication network delays are discussed.

Distributed, consensus-based algorithms have emerged as a promising approach for the coordination of distributed energy resources (DER) due to their communication, computation, privacy and reliability advantages over centralized approaches. However, state-of-the-art consensus-based algorithms address the DER coordination problem in independent time periods and therefore are inherently unable to capture the time-coupling operating characteristics of flexible demand (FD) and energy storage (ES) resources. This paper demonstrates that state-of-the-art algorithms fail to converge when these time-coupling characteristics are considered. In order to address this fundamental limitation, a novel consensus-based algorithm is proposed which includes additional consensus variables. These variables express relative maximum power limits imposed on the FD and ES resources which effectively mitigate the concentration of the FD and ES responses at the same time periods and steer the consensual outcome to a feasible and optimal solution. The convergence and optimality of the proposed algorithm are theoretically proven while case studies numerically demonstrate its convergence, optimality, robustness to initialization and information loss, and plug-and-play adaptability.

This paper focuses on the analysis of the particularities of control for multi-agent systems. The design method is based on an optimal control approach which requires the solution of Linear Quadratic Regulator problem (LQR). The characteristics of the two types of control (centralized and distributed) for unmanned aerial vehicles flight formations are highlighted by the case studies. The dynamics of an UAV (Unmanned Aerial Vehicle) is used for the longitudinal motion. The flight formation considered as a case study consists of four identical agents.

The paper describes the concept of a Digital Twin (DT) creation, which could be used as part of a centralized ground traffic control system in the airport’s apron area. The work is focused on the automatic control systems expected in the future, which will completely replace the ground traffic controllers that solve the centralized control’s tasks in our days. It is assumed that the developed DT can be used both at the stage of training the control system and at the stage of its use. A special feature of the proposed DT concept is the clearly formulated principles of the observed process’ time discretization and the space in which the movement of ground vehicles and aircraft occurs. The experimental verification of the developed concept was carried out using a special simulation model designed to generate data streams on the airport’s transport network’s traffic participants’ location.

The increasing installation of controllable Distributed Energy Resources (DERs) in Distribution Networks (DNs) opens up new opportunities for the provision of ancillary services to the Transmission Network (TN) level. As the penetration of smart meter devices and communication infrastructure in DNs increases, they become more observable and controllable with centralized optimization-based control schemes becoming efficient and practical. In this paper, we propose a centralized tractable Optimal Power Flow (OPF)-based control scheme that optimizes the real-time operation of active DNs, while also considering the provision of voltage support as an ancillary service to the TN. We embed in the form of various constraints the current voltage support requirements of Switzerland and investigate the potential benefit of ancillary services provision assuming different operational modes of the DER inverters. We demonstrate the performance of the proposed scheme using a combined HV-MV-LV test system., Comment: 10 pages

This paper provides a review of the research conducted on complex network analysis (CAN) in electric power systems. Moreover, a new approach is presented to find optimal locations for microgrids (MGs) in electric distribution systems (EDS) utilizing complex network analysis. The optimal placement in this paper points to the location that will result in enhanced grid resilience, reduced power losses and line loading, better voltage stability, and a supply to critical loads during a blackout. The criteria used to point out the optimal placement of the MGs were predicated on the centrality analysis selected from the complex network theory, the center of mass (COM) concept from physics, and the recently developed controlled delivery grid (CDG) model. An IEEE 30 bus network was utilized as a case study. Results using MATLAB (MathWorks, Inc., Nattick, MA, USA) and PowerWorld (PowerWorld Corporation, Champaign, IL, USA) demonstrate the usefulness of the proposed approach for MGs placement.

Frequency regulation is important for obtaining higher power supply quality. To our best knowledge, there is no decentralized frequency restoration method for cascaded-type microgrid. This paper proposes a decentralized second frequency control for the cascaded-type microgrid. It only relies on local information to achieve frequency restoration and average power sharing. In addition, the proposed control is suitable for loads with different characteristics. Based on the singularity theory, we provide the control algorithm convergence analysis and control coefficient selection. Finally, the real-time simulation results conducted by RTLAB verify the feasibility of the proposed method.

The paper describes a fully-dispatchable microgrid architecture that features i) the adoption of a master/slave power-based control in the central dispatcher to drive distributed power generators and ii) the connection of a suitable power converter equipped with energy storage, called Utility Interface, at the point of common coupling with the mains. Property i) ensures scalability and capability to drive distributed units at low bit rate and without synchronization or knowledge of grid parameters, thus avoiding the use of information that may be difficult to retrieve. Property ii) allows optimum behavior at the utility terminals, by providing compensation of load unbalance, reduction of harmonic injection, fast reaction to load and line transients, and prompt response to utility demands. In addition, the proposed solution allows plug-and-play integration and full utilization of distributed energy resources, balanced power sharing among distributed generators, and stabilization of voltage profiles. After a presentation of the microgrid architecture, the paper describes the implementation of a robust control strategy providing the above functionalities and its validation in a laboratory-scale microgrid prototype.

This paper presents load frequency control of the 2021 Egyptian power system, which consists of multi-source electrical power generation, namely, a gas and steam combined cycle, and hydro, wind and photovoltaic power stations. The simulation model includes five generating units considering physical constraints such as generation rate constraints (GRC) and the speed governor dead band. It is assumed that a centralized controller is located at the national control center to regulate the frequency of the grid. Four controllers are applied in this research: PID, fractional-order PID (FOPID), non-linear PID (NPID) and non-linear fractional-order PID (NFOPID), to control the system frequency. The design of each controller is conducted based on the novel tunicate swarm algorithm at each operating condition. The novel method is compared to other widely used optimization techniques. The results show that the tunicate swarm NFOPID controller leads the Egyptian power system to a better performance than the other control schemes. This research also presents a comparison between four methods to self-tune the NFOPID controller at each operating condition.

With the rapid advancement of connected and autonomous vehicles (CAV) in terms of testing and usage, the implementation of the autonomous interchange in the real world has become more realistic than before. Since the beginning of the last decade, the concept of autonomous intersection has been developed with slightly different techniques. This paper introduces a next-generation interchange control algorithm (NIC) that deals with service interchange terminals for the CAV with the ability to adjust the dimensions and geometric designs. It proposes six different geometric designs that have been modeled in a simulation software package (VISSIM) to employ the NIC algorithm. The system depicted a real-world scenario of an interchange with a slight modification on the geometric design to provide smoother entry to the interchange terminal. The analysis of the proposed designs in terms of throughput, capacity, delay, and volume-to-capacity (V/C) ratio indicated different performance measurements based on the analyzed traffic movements. Tight turn with one left dedicated turn provided the highest performance, while wide turn with two left shared turns indicated the lowest performance. Both NIC designs demonstrated significantly higher throughputs and significantly lower delays compared to a current traffic signal system. By applying the NIC with the existence of the CAV, the operation of highway interchange can be significantly improved.

This paper proposes an energy management system (EMS) of direct current (DC) microgrid. In order to implement the proposed EMS, the control and operation method of EMS is presented in this work. While most of the studies have individually examined the grid-connected mode used in building and the stand-alone operation mode applicable to the island, the proposed EMS allows it to be used in both grid-connected mode and stand-alone mode with 10 modes. In order to determine each mode in EMS, not only the amount of generated power, load power, and the state of charge (SOC) of the battery, but also the rated power of the energy storage system (ESS) converter that performs charging and discharging operations is additionally considered. Thus, various uncertainties that may occur in the actual DC microgrid environment can be improved. A laboratory-scale DC microgrid is fabricated to conduct experimental validation of proposed EMS. Experiments of DC microgrid with proposed EMS were performed for each mode, and the experiment waveforms of each power conversion device are included in detail.

Active Distribution Networks (DNs) are expected to host an increasing number of Distributed Generators (DGs) and other Distributed Energy Resources (DERs), offering new flexible sources and enabling the provision of ancillary services to system operators. Centralized DER controls that use Optimal Power Flow (OPF) methods necessitate tractable and scalable computational tools that can handle large DNs with satisfactory performance. In this paper, we compare an iterative OPF method against the standard exact AC OPF calculations in terms of the computational effort and solution quality. Furthermore, we highlight the suitability of the selected formulation to offer voltage support (VS) as an ancillary service to the transmission network. The results are demonstrated using a joint medium and low voltage grid, and show that tractable OPF formulations can unlock financial business cases for DNs that can actively participate in VS schemes.

Submitted by Wagner Junior (wagner.junior@unioeste.br) on 2020-03-17T13:15:48Z No. of bitstreams: 2 Paulo_Thiago_de_Godoy_2020.pdf: 5662715 bytes, checksum: f216a0cfe0e0a3c1d7e84a5a749ee397 (MD5) license_rdf: 0 bytes, checksum: d41d8cd98f00b204e9800998ecf8427e (MD5) Made available in DSpace on 2020-03-17T13:15:48Z (GMT). No. of bitstreams: 2 Paulo_Thiago_de_Godoy_2020.pdf: 5662715 bytes, checksum: f216a0cfe0e0a3c1d7e84a5a749ee397 (MD5) license_rdf: 0 bytes, checksum: d41d8cd98f00b204e9800998ecf8427e (MD5) Previous issue date: 2020-02-12 Coordenação de Aperfeiçoamento de Pessoal de Nível Superior - CAPES A microgrid (MG) can operate either connected to the main grid or islanded. When the MG operates in islanded mode, the frequency control is performed through the primary and secondary control. Primary control is responsible for ensuring the stable operation of distributed generations. Secondary control is responsible for frequency and voltage adjustment. The secondary control can be achieved through centralized, distributed or decentralized strategies. The centralized control is the most applied strategy in MGs due to the facility of the control and coordination of the distributed generators. However, the reliability of centralized control strategies is influenced by the proper functioning of the controller and the communication channel. To avoid the reliability problems of the centralized control, this paper proposes a new unified secondary control strategy comprising of centralized and decentralized control, that can capable of maintaining the MG frequency regulation even during control or communication failures. A decentralized load shedding strategy is implemented to assist MR generation and load control. To verify the proposed secondary control, the European low voltage distribution network benchmark MG is implemented in Matlab/Simulink. For the simulations, three scenarios are tested: MG central controller failure, total and partial communication system failures. The experimental results have shown that the proposed secondary control can guarantee the frequency regulation, system stability and can avoid the load shedding even during failures. The proposed strategy proved capable to restore the system to normal control operation after the failures end. However, communication delays influence the response of the proposed strategy, which can cause minor disturbances when switching the operating mode. As Microrredes (MRs) podem operar conectadas ou ilhadas da rede principal. Quando a MR opera no modo ilhado, a frequência e a tensão são mantidas e reguladas através dos controles primário e secundário. O controle primário é responsável por manter a estabilidade dos geradores distribuídos. O controle secundário é responsável por regular a frequência e a tensão da MR nos valores nominais, podendo ser realizado através de estratégias centralizadas, distribuídas ou descentralizadas. As estratégias de controle centralizado são as mais aplicadas em MRs, devido a facilidade de controle e coordenação com os recursos energéticos distribuídos. Contudo, a confiabilidade das estratégias de controle centralizado são influenciadas pelo funcionamento adequado do controlador e do canal de comunicação. De forma a contornar os problemas de confiabilidade do controle centralizado para regulação de frequência, este trabalho propõe uma nova estratégia de controle secundário unificado, composta por ambas as estratégias de controle centralizado e descentralizado, a qual é capaz de manter a regulação de frequência da MR mesmo após falhas de comunicação ou de controle. Ademais, um esquema de alívio de carga descentralizado é implementado para auxiliar o controle de geração e carga da MR. Um método de ajuste dos ganhos do controle secundário é proposto, o qual considera as características da MR, do esquema de alívio de carga e dos canais de comunicação. Para testar a estratégia proposta, a MR CIGRE Benchmark Europeia de baixa tensão é implementada em Matlab/Simulink. São considerados três cenários para as simulações: falha no controlador central, falha total e parcial do canal de comunicação. Os resultados mostraram que a estratégia proposta garante a regulação de frequência, estabilidade do sistema e evita ações desnecessárias do esquema de alívio de carga, até mesmo durante falhas. A estratégia proposta também se mostrou capaz de retornar para o controle normal de operação após o fim da falha. Entretanto, os atrasos de comunicação influenciam na resposta da estratégia proposta, podendo ocasionar pequenas perturbações nas trocas de modos de operação.

Future active distribution grids (ADGs) will incorporate a plethora of Distributed Generators (DGs) and other Distributed Energy Resources (DERs), allowing them to provide ancillary services in grid-connected mode and, if necessary, operate in an islanded mode to increase reliability and resilience. In this paper, we investigate the ability of an ADG to provide frequency control (FC) in grid-connected mode and ensure reliable islanded operation for a pre-specified time period. First, we formulate the operation of the grid participating in European-type FC markets as a centralized multi-period optimal power flow problem with a rolling horizon of 24 hours. Then, we include constraints to the grid-connected operational problem to guarantee the ability to switch to islanded operation at every time instant. Finally, we explore the technical and economic feasibility of offering these services on a balanced low-voltage distribution network. The results show that the proposed scheme is able to offer and respond to different FC products, while ensuring that there is adequate energy capacity at every time step to satisfy critical load in the islanded mode., 10 pages

The vast majority of routing approaches for vehicular ad hoc networks (VANETs) are distributed, which are ineffective to exploit the global networking information and easily lead to local optimum, appearing as sparse connectivity and network congestion. Recently, by combining software-defined network architecture together with VANETs, software-defined VANETs (SDVN) is widely concerned, which shows the benefits of centralized control. In this paper, we propose a hierarchical geography routing protocol for SDVN. First, the protocol divides a large region into multiple small grids according to the geographical location and finds a series of grids with good connectivity based on real-time grid vehicle density and historical vehicle transfer probability between grids. Second, we construct a path cost function with load balancing and keep two paths with minimal costs from the selected grids. Finally, a series of relay nodes on each selected path are filtered for routing according to node utility. Simulation results show that the proposed routing algorithm achieves significant gains in terms of delivery ratio, throughput, average delay, and average hop count compared with several existing routing protocols.

Dynamic smart grid operations require that utilities that incorporate intermittent renewable energy resources provide creative and inclusive solutions to reduce and shift electrical demand. Commercial building HVAC systems have been used as a dispatchable load, but are limited by the lack of interoperability. Increased operability can be achieved using a secure and reliable interconnection device, which can provide direct bidirectional communications between the utility and the building automation system (BAS) controllers. This paper developed and tested a building automation intrusion detection system (BAIDS) that can provide a cyber-secure connection between public and private BAS networks. The BAIDS was used in a hardware-in-the-loop experiment that connected an actual photovoltaic array with a BAS control test bed and a building zone model. The BAIDS device allowed for critical control signals to pass from the public network directly to a fan controller in a BAS private network. At the same time, the BAIDS device provided intrusion detection monitoring to identify malicious activity. The network traffic was evaluated using an adaptive resonance theory (ART) artificial neural network. The ART algorithm was able to learn normal traffic activity on the private and public networks. The algorithm was then used to detect unauthorized attempts to access the interconnection device and a malicious cyber-physical attack on the BAS.

In order to foster increasing shares of renewable generation at distribution level, it is necessary to introduce control strategies to avoid voltage and loading congestions. Control strategies are also needed to facilitate the provision of ancillary services to the transmission grid by distributed resources. Centralized control solutions are often the best choice for an optimal management of distribution networks, but they usually require monitoring vast network areas and many grid nodes, which is frequently unaffordable. For this reason, some portions of the network (i.e. LV nodes) can be operated in an unsupervised way, and the fundamental control functions are operated by generators local controllers. Of course, these controllers also impact on the supervised network portions, therefore centralized architectures should take their (side) effects into account in order to compensate them. This paper analyses the behavior of a real distribution grid with a hybrid control strategy (i.e. where automatic local controllers are implemented in some portions, while some generators and distribution transformers are controlled by the network operator) and compares it to situations in which either central control only or local controllers only are activated.

International audience; SDN is a promising solution for vehicular networks challenges. Distributing the SDN control plane achieved more scalability and performance. However, synchronization between different controllers of network state generates extra-delay that is not suitable with delay-sensitive applications in vehicular networks like emergency services. In this paper, we investigate the e2e (end-to-end) delay in variable density vehicular scenarios with variable number of controllers. Our experiments prove the benefits of using multi-controllers in terms of delay but also the need of the deployment of the effective number according to the vehicular network density.

International audience; The idea of leveraging Software Defined Networking (SDN) in vehicular networks has drawn a lot of attention in the last years. SDN flexibility and programmability brought promising solutions for VANET challenges, namely Quality of Services (QoS) and scalability which are the main characteristics of Internet of Vehicles (IoV). Such networks are characterized by fast topological changes due to their variable dynamicity and density. In fact, SDN decouples control plane and data plane, providing programmability to configure the network. However, based on a single controller, SDN is criticized for not supporting scalability and for decreasing the overall network Quality of service. Using multiple controllers becomes the tendency of recent works to meet the need of large networks. Throughout this paper, we survey the proposed SDN-based architectures for vehicular networks. Considering the control plane impact, centralized or distributed, the QoS improvements brought by theses architectures are studied and criticized in order to derive the suitability of each proposal to resolve the IoV challenges and meet its requirements for the various applications.

This paper presents an applicative study designed to analyze PV power system energy installed at the UVT Campus' energy autonomy. The case study, analyzes the results obtained from the operation of the pilot building of the Institute of Multidisciplinary Research for Science and Technology (ICSTM). This building was designed and built according to worldwide directions in the areas of Near Zero Energy Building (nZeb) and buildings with scientific research laboratories specifics. The particular / specific problem, both at the constructive and installations levels, of great complexity, had been assessed and dimensioned at the level of energy balance with energy input obtained through Building Integrated Photovoltaic's (BIPV) technologies. The experimental results obtained demonstrate the achievement of very high levels of efficiency and economy in 2017 compared to the previous baseline year. Therefore, by consuming more efficiently and improving the PV absorption efficiency, savings of ~7800 Eur / 33% less energy absorbed from the national network (SEN) were achieved.

International audience; In this paper, we propose two cases of study for control reconfiguration of Discrete Event Systems. The main contributions are based on a safe centralized and distributed control synthesis founded on timed properties. In fact, if a sensor fault is detected, the controller of the normal behavior is reconfigured to a timed controller where the timed information replaces the information lost on the faulty sensor. Finally, we apply our contribution to a manufacturing system to illustrate our results and compare between the two frameworks.

Real-time path planning for large, dense grid-based automated guided vehicle (AGV) systems, used for example to sort parcels, is challenging. Most approaches described in the literature are not fast enough for real-time control or are not able to avoid congestion. This paper presents a dynamic approach using a graph-representation of the grid system layout with vertex weights that are updated over time. By means of an extensive discrete-event simulation, we show that the proposed path planning approach significantly increases the throughput compared to existing approaches. Furthermore, it enables the recovery from deadlock situations.

The centralized control of active distribution networks with large penetration of dispersed resources requires algorithms capable of providing network state estimation. Within this context, the measurement of bus voltage synchrophasors provides useful data that increase the observability of the network. The peculiar characteristics of distribution networks, such as feeder impedances, power flows and harmonic distortion, are different from those of transmission networks. Therefore, in order to obtain reasonably low uncertainty levels, Remote Terminal Units (RTU) with specific characteristics need to be developed. The paper presents an algorithm developed for the synchrophasor measurement in active distribution networks together with its implementation into a specific hardware based on a real-time microcontroller. The paper also presents the experimental characterization of the developed RTU by making reference to both single-tone and distorted signals. © 2009 IEEE.

[EN] Borrar Robot soccer offers an adequate domain in order to design and validate architectures for robot-coordination. One classification refers to centralized architectures, which correspond to robot soccer environments with global perception and centralized control of the robots, using only one decision-making system. In this paper it is presented a centralized robot soccer architecture based on roles, where one role is assigned to each player in order to select a specific behaviour depending on game conditions. Roles are assigned using an assignment function, which is activated when the ball changes of the quadrant in the playing field. This strategy has been compared by simulation in games against an opposition team with constant roles, and other team with a hierarchical strategy which assigns roles depending on a tactic previously selected. The results showed a better performance in the team with the role-based, [ES] El fútbol de robots ofrece un entorno adecuado para el diseño y la validación de arquitecturas de sistemas multi-robot. Al clasificar las ligas de fútbol de robots existentes se encuentran ligas con arquitecturas centralizadas que poseen percepción global del entorno y donde los robots son controlados desde un ordenador a través de un único sistema de toma de decisiones. En este artículo se presenta una arquitectura basada en roles para equipos de fútbol de robots con percepción global y control centralizado. En esta arquitectura un rol es seleccionado para cada jugador por medio de una función. A partir de este rol y de las condiciones de juego presentes se selecciona un comportamiento que el jugador deberá ejecutar. La función que es utilizada para la asignación de roles es activada cuando el balón cambia de cuadrante en el campo de juego. La estrategia presentada es comparada en simulación realizando partidos contra un equipo que posee una estrategia de roles constantes y un equipo con una estrategia jerárquica basada en selección de tácticas y posteriormente asignación de roles a partir de la táctica seleccionada. Los resultados mostraron no solo un mejor rendimiento del equipo con la estrategia basada en roles, sino también uniformidad en los comportamientos realizados por los jugadores del equipo durante las transiciones de roles y comportamientos., Jose Guillermo Guarnizo há sido financiado por una beca del Departamento Administrativo de Ciencia, Tecnologia e Innovación COLCIENCIAS, Colombia.

This paper considers the minimization of transmit power in Gaussian parallel interference channels, subject to a rate constraint for each user. To derive decentralized solutions that do not require any cooperation among the users, we formulate this power control problem as a (generalized) Nash equilibrium game. We obtain sufficient conditions that guarantee the existence and nonemptiness of the solution set to our problem. Then, to compute the solutions of the game, we propose two distributed algorithms based on the single user waterfilling solution: The \emph{sequential} and the \emph{simultaneous} iterative waterfilling algorithms, wherein the users update their own strategies sequentially and simultaneously, respectively. We derive a unified set of sufficient conditions that guarantee the uniqueness of the solution and global convergence of both algorithms. Our results are applicable to all practical distributed multipoint-to-multipoint interference systems, either wired or wireless, where a quality of service in terms of information rate must be guaranteed for each link., Comment: Paper submitted to IEEE Transactions on Information Theory, February 17, 2007. Revised January 11, 2008

Demand side management has focused more on centralized control and heavily depends on continuous consumer interaction, often overlooking consumer thermal and visual comfort. Distribution grid management will necessitate the active involvement of new market actors (i.e. prosumers, aggregators, distribution system operators, retailers, etc.), so a holistic approach becomes critical to transform demand into an active element of electricity system management. This paper presents a consumer centric demand flexibility framework, which facilitates the automated, human-centric demand response, minimizes consumer interactions and accommodates various power system ancillary services.

The gradual active load penetration in low voltage distribution grids is expected to challenge their network capacity in the near future. Distribution system operators should for this reason resort to either costly grid reinforcements, use of low voltage boosters, or demand response mechanisms. Since demand response implementation is usually more cost effective, it is the favorable solution to avoid or delay the need for grid reinforcement. To this end, this paper presents a framework for handling grid limit violations, both voltage and current, to ensure a secure and qualitative operation of the distribution grid. This framework consists of two steps, namely a proactive centralized and subsequently a reactive decentralized control scheme. The former is employed to balance the one hour ahead load while the latter aims at regulating the consumption in real-time. In both schemes, fairness in terms of utilization of demand flexibility among the customers is incorporated. It is demonstrated that the proposed methodology aids in keeping the grid status within preset limits while utilizing flexibility from all flexibility participants.

Increasing power electronics controlled distributed generation resources and active loads provide a future distributed system with more controllability as well as challenges to synthesize heterogeneous devices. From system engineering's perspective, control and operation of the future distribution system need more insight into the system architecture of the grid. In this paper, in light of the start-of-the-art control strategies for microgrids which rely on power electronics systems, a grid architecture model for future distribution system is proposed based on microgrid clusters. Both the physical and cyber structures for this architecture are described. Two illustrative examples are presented to explain different control methods that can be adopted in this model to harmonize different devices. This architecture can be used to guide the system design for the smart distribution system.

This paper presents a feasibility study on a waste heat recovery system for heavy-duty truck engines based on organic Rankine cycle (ORC) technology. The elements of novelty of the work are: i) the proposed plant configuration, and ii) the feasibility study that encompasses the whole preliminary design workflow of the system, namely, from the thermodynamic cycle optimization and the components preliminary sizing, to dynamic modelling and the design of a PI-based control system. The conceived ORC turbogenerator employs hexamethyldisiloxane (MM) as working fluid and achieves a maximum rated mechanical power of approximately 5 kW at the design point, corresponding to a truck cruise speed and a Diesel engine power output of 85 km h-1 and 100 kW respectively. Regarding the dynamic performance, the higher response time of the ORC unit compared to that of the Diesel engine makes the adoption of an advanced control system necessary. In particular, the simulation of a PI-based control system shows that it becomes impossible to prevent the thermal decomposition of the working fluid when the engine operates continuously at high power levels. This case study demonstrates the importance for automotive ORC applications of performing the investigation of dynamic performance and control design already in the early design phase.

This paper presents the performance measurements from a comparison between FODA/IBEA and two other satellite access schemes, FEEDERS and DRIFS. The three schemes differ in terms of the scheduling of the channel capacity: i.e. centralized control in FODA/IBEA and distributed in the other two. All these access schemes were designed at CNUCE, where the simulation tool used for the comparison was also developed. FODA/IBEA was developed and tested on several satellites (Olympus, Eutelsat and Italsat), and used in a project of LAN interconnection.* The two distributed control access schemes have been studied and simulated to analyse the behaviour of the capacity assignment algorithm, while the recovery procedures needed for the network stability will be presented in later papers. All the access schemes support an aggregated traffic, and the quality of the data transmission in guaranteed even when the transmitting signal experiences a severe attenuation due to bad atmospheric conditions.

This paper presents a new methodology of multivariable centralized control based on the structure of inverted decoupling. The method is presented for general n × n processes, obtaining very simple general expressions for the controller elements with a complexity independent of the system size. The possible configurations and realizability conditions are stated. Then, the specification of performance requirements is carried out from simple open loop transfer functions for three common cases. As a particular case, it is shown that the resulting controller elements have PI structure or filtered derivative action plus a time delay when the process elements are given by first order plus time delay systems. Comparisons with other works demonstrate the effectiveness of this methodology through the use of several simulation examples and an experimental lab process.

Power system is a large-scale network with a number of components and interconnections for which centralized control becomes cumbersome. For multi-area computations, decentralization is necessary. For implementation of this approach network decomposition becomes an essential task. In this paper the network decomposition problem is solved as an optimization problem using the harmony search (HS) algorithm. To improve the performance of the HS algorithm, a widely used graph bi-partitioning method called Kernighan-Lin (KL) strategy is used in the improvisation process. KL strategy is used in the partitioning of digital and VLSI circuits and is suitable for bi-partitioning networks. The connectivity of the partitioned clusters are checked by means of graph traversal techniques. Simulation are carried out on IEEE Standard systems and found to be very effective in decomposition of the system hierarchically. � 2012 Elsevier B.V. All rights reserved.

Small cell networks are key components in 5G networks to boost the network capacity, improve spectrum and energy efficiency, and enable flexible and new services. Due to the flexible spectrum access among and flexible deployment of small cells, the inter- cell coordination becomes critical for the performance of the network. In this paper, based on the key concept in software defined networking (SDN) for Internet, we first introduce the network graph approach as a tool for the control and coordination among small cells. The network graph is constructed from the abstracted network state information extracted from underlying base stations. It shields the logical centralized control unit from implementation details of the underlying physical layer and thus reduces the control overhead in a centralized solution. We use the network graph for network energy saving in small cell networks, in which network graphs are used to decide the optimal set of small cells in the network. For cells outside this set we can switch them off for energy saving. We propose three types of network graphs with different network state details. Based on these graphs, we formulate the energy saving problem as an integer linear programming (ILP) problem, and propose the practical algorithms to solve the problem. The performance of the algorithms are studied by simulation. It shows the potential of the proposed network graph approach for the inter-cell resource coordination in small cell networks.

With an increasing number of assistive robots operating in human domains, research efforts are being made to design control systems that optimize the efficiency of multi-robot operations. As part of the EU funded RoboEarth project, this paper discusses the design of such a system, where a variety of existing components are selected and combined into one cohesive control architecture. The architecture’s main design principle stems from Radestock’s ‘separation of concerns’, which dictates the separation of software architectures into four disjunct components; coordination, configuration, communication and computation. For the system’s coordinating component a Golog based planning layer is integrated with a custom made execution module. Here, the planning layer selects and parametrizes abstract action plans, where the execution layer subsequently grounds and executes the involved actions. Plans and plan related context are represented in the OWL-DL logics representation, which allows engineers to model plans and their context using first-order logic principles and accompanying design tools. The communication component is established through the RoboEarth Cloud Engine, enabling global system accessibility, secure data transmissions and the deployment of heavy computations in a Cloud based computing environment. We desire these computations, such as kinematics, motion planning and perception, to all run on the Cloud Engine, allowing robots to remain lightweight, the instant sharing of data between robots and other algorithms and most importantly, the reuse of these algorithms for a variety of multi-robot operations. A first design of the system has been implemented and evaluated for its strengths and weaknesses through a basic, but fundamental real-world experiment. ispartof: intelligent Service Robotics vol:9 issue:1 pages:63-77 status: published

This paper presents a new methodology to design multivariable proportional-integral-derivative PID controllers based on decoupling control. The method is presented for general n × n processes. In the design procedure, an ideal decoupling control with integral action is designed to minimise interactions. It depends on the desired open-loop processes that are specified according to realisability conditions and desired closed-loop performance specifications. These realisability conditions are stated and three common cases to define the open-loop processes are studied and proposed. Then, controller elements are approximated to PID structure. From a practical point of view, the wind-up problem is also considered and a new anti-wind-up scheme for multivariable PID controller is proposed. Comparisons with other works demonstrate the effectiveness of the methodology through the use of several simulation examples and an experimental lab process.

In the new era of Ambient Intelligence, wireless sensor networks (WSNs) are seen to bridge the gap between physical world and the Internet, making a large amount of information accessible anywhere, anytime. Over the last few years, WSNs are being developed towards a large number of multimedia streaming applications, e.g. video surveillance, traffic control systems, health monitoring, and industrial process control. WSNs consist of small sensor devices (nodes) that are capable of working unattended, without centralized control, under dynamically changing conditions. However, these devices face important limitations in terms of energy, memory and computational power. The uncontrolled use of limited resources in conjunction with the unpredictable nature of WSNs in terms of traffic load injection, wireless link capacity fluctuations and topology modifications may lead to congestion. Congestion can cause increased packet loss and delay. This paper proposes a bio-inspired congestion control approach for WSNs streaming applications that necessitate controlled performance with graceful degradation. In the proposed approach, congestion in WSNs is prevented (or at least minimized) by regulating the rate of each traffic flow based on the Lotka-Volterra competition model. Performance evaluations reveal that the proposed approach achieves adaptability to changing traffic loads, scalability and fairness among flows, while providing graceful performance degradation as the offered load increases. © 2010 Elsevier B.V. All rights reserved. 33 17 2039 2047 Cited By :20

A robust control of an active magnetic suspension requires an accurate plant model and proper model uncertainties. Moreover, the selection of control design performance weighting functions is not straightforward. In this paper, the design of a centralized H ∞ controller of an active magnetic suspension is considered. Two design approaches are examined: an H ∞ loop-shaping control design procedure and a signal-based H ∞ control. The tuning of the design performance functions is carried out applying a genetic algorithm. The robust stability of the gain-scheduled H ∞ controller is verified in the presence of real parametric and non-parametric frequency-dependent uncertainties. Accurate models of the system and its uncertainties can be obtained using engineering models and frequency response functions of the test-rig. Finally, simulations and experimental results confirm the effectiveness of the signal-based H ∞ approach.

The concept of an all-electric ship, while offering unprecedented advantages from the point of view of efficiency and flexibility of operation, has introduced new challenges in terms of stability and power flow control. The advent of a full power electronics power system has raised new questions from the point of view of system dynamics, particularly when dealing with the new medium-voltage direct current distribution. The overall goal of guaranteeing a secure operation of the power system has brought researchers to consider two main approaches: reducing the dynamics of the large load to operate in a range of dynamics compatible with traditional generation systems, or making the generator set smarter through its power electronics interface. This paper compares these approaches to stable operation, focusing on the latter considered more in line with the progress of technology and in general more appealing.

For more than 20 years it has been a consistent plan by all Danish governments to turn the Danish power production away from fossil fuels towards renewable energy. The result today is that 37% of the total Danish power consumption was covered by mainly wind energy in 2013 aiming at 50% by 2020. Another consequence is the public way of generally thinking green which have led to a national decision of undergrounding not only all of the Danish distribution system but also the future transmission system. These issues initiate the infrastructure constructions of the transmission system i.e. a large amount of overhead lines over 100 kV as well as the new planed transmission lines will be undergrounded; the transfer capacities will be enlarged by upgrading the interconnections. Large amounts of reactive power components will be placed in the system partly for cable compensation and partly for voltage security. Consequently, the ramping speed of the transits in the main corridors via the interconnections is foreseen to be increased. The voltage control based on the present system is thus becoming a challenging objective. This survey paper presents some of the existing AVC systems i.e. system structures, objectives, constraints, algorithms for optimal power flow and some special functions in particular systems, which inspires the concept design of a Danish AVC system to address the future challenges of voltage control. In the concept, the Danish AVC design is based on a centralized control scheme. All the buses are monitored where the voltage magnitudes are maintained continually. The loss minimization including switching cost is the objectives of the AVC system. The reactive power reserves as constraints are taken into account to limit the regulation capabilities of generators. The Day ahead and short-term forecast is to be implemented to reduce the working load of the real time system, as well as to minimize the numbers of switching times of the discrete components. The fallback controllers are to be installed in selected substations to enhance the system reliability and the robustness in case the substation loses the telecommunications to the control center. RPCs will be integrated to the AVC system as normative regulators in the later stage. Distributed generation units can be organized as virtual power plants and participate in voltage control at transmission level. Energinet.dk as the Danish TSO will implement the first stage of the AVC system by 2016.

International audience; The progress in FPGA technology has enabled FPGA-based reconfigurable systems to target increasingly sophisticated applications, which has led to a high control design complexity, resulting in longer design cycles. In this paper, we propose a control design approach for FPGA-based reconfigurable systems aiming at increasing design productivity. This approach is based on a semi-distributed control model that splits different control concerns (monitoring, decision-making and reconfiguration) between autonomous modular controllers and makes use of formalism-oriented design, to decrease the control design complexity and facilitate design verification, reuse and scalability. This model is composed of distributed controllers handling the self-adaptivity of the system reconfigurable regions and a coordinator to respect the system global constraints. To enhance design productivity, the proposed control model is generated automatically using a high-level modeling approach. This approach is based on MDE (Model-Driven Engineering) and the MARTE (Modeling and Analysis of Real-Time and Embedded Systems) standard, allowing to make low-level technical details transparent to designers and to automate code generation from high-level models. Experiments on the generated control systems showed that the proposed semi-distributed control model is more flexible, reusable and scalable than the centralized one, at the cost of a slight increase in required hardware resources.

This paper develops a controller synthesis algorithm for distributed LQG control problems under output feedback. We consider a system consisting of three interconnected linear subsystems with a delayed information sharing structure. While the state-feedback case of this problem has previously been solved, the extension to output-feedback is nontrivial, as the classical separation principle fails. To find the optimal solution, the controller is decomposed into two independent components. One is delayed centralized LQR, and the other is the sum of correction terms based on additional local information. Explicit discrete-time equations are derived whose solutions are the gains of the optimal controller., Comment: Submitted to the 51nd IEEE Conference on Decision and Control, 2012

International audience; Many distribution companies must deliver and pick up goods to satisfy customers. This problem is called the Vehicle Routing Problem with Mixed linehauls and Backhauls (VRPMB) which considers that some goods must be delivered from a depot to linehaul customers, while others must be picked up at backhaul customers to be brought to the depot. This paper studies an enriched version called Heterogeneous fleet VRPMB with Time Windows or HVRPMBTW which has not much been studied in the literature. A Particle Swarm Optimization heuristic (PSO) is proposed to solve this problem. This approach uses and models the social behavior of bird flocking, fish schooling. The adaptation and implementation of PSO search strategy to HVRPMBTW is explained, then the results are compared to previous works (Ant Colony Optimization) and compared also to the high quality solutions obtained by an exact method (solver CPLEX). Good promising results are reported and have shown the effectiveness of the method.

This paper focuses on the design of a linear robust controller for a mechatronic system in the presence of real parametric and non-parametric frequency-dependent uncertainties. An H∞ loop-shaping control design procedure is compared with a signal-based H∞ control. The comparison of the robust controllers is carried out in the context of an active magnetic bearing rotor system. Experimental results demonstrate the better robust stability of the signal-based approach. A genetic algorithm is essential to credible comparison of different design approaches.

This paper focuses on the design of a linear robust controller for a mechatronic system in the presence of real parametric and non-parametric frequency-dependent uncertainties. An H∞ loop-shaping control design procedure is compared with a signal-based H∞ control. The comparison of the robust controllers is carried out in the context of an active magnetic bearing rotor system. Experimental results demonstrate the better robust stability of the signal-based approach. A genetic algorithm is essential to credible comparison of different design approaches.

In this paper, we propose a method for video ads dissemination through a hybrid network consisting of WiFi and cellular networks, in order to provide timely delivery of video ads with preferred content to users according to the users' contexts. In recent years, video download/streaming services for cellular phones have already become popular. Among various video delivery services, a service for disseminating video ads according to the users' contexts is expected to achieve high advertising effects. However, context-aware video ads dissemination will consume large bandwidth since the size of video ad is rather large and the same ad is required at different time from various users. We propose a new video ads dissemination method for mobile terminals which utilizes both WiFi and cellular networks. In the proposed method, a file of video ad is divided into pieces and each node exchanges the pieces with neighbor nodes using WiFi ad hoc communication so that the usage of cellular network is reduced. In order to make the method works effectively for a large number of nodes, we propose an algorithm where mobile nodes autonomously and probabilistically decide their actions without a central control. Through simulations, we confirmed that our method reduces cellular network usage by about 93% compared with a case that all nodes download video ads via cellular network, and works effectively in cases with a large number of nodes and high mobility., PerCom2009 : The Seventh Annual IEEE International Conference on Pervasive Computing and Communications , Mar 16-20, 2009 , Dallas, TX, USA