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Traditional networks rely on aggregate routing and decentralized control to achieve scalability. On the contrary, software-defined networks achieve near optimal network performance and policy-based management through per-flow routing and centralized control, which, however, face scalability challenge due to: 1) limited ternary content addressable memory and on-die memory for storing the forwarding table and 2) per-flow communication/computation overhead at the controller. This paper presents a novel hybrid switching (HS) design, which integrates traditional switching and software-defined networking (SDN) switching for the purpose of achieving both scalability and optimal performance. We show that the integration also leads to unexpected benefits of making both types of switching more efficient under the hybrid design. We also design the general optimization framework via HS and propose an approximation algorithm for load-balancing optimization as a case study. Testing and numerical evaluation demonstrate the superior performance of HS when comparing with the state-of-the-art SDN design. [ABSTRACT FROM AUTHOR]

Reconstitution of control architecture creates a great challenge for distributed drive electric vehicles (DDEV), due to the emergence of a new distributed driving strategy. To this end, a novel distributed control architecture is proposed in this paper for integrated control of active front steering (AFS) system and direct yaw moment (DYC) system. First, a multi-agent system (MAS) is employed to construct a general framework, where AFS and DYC act as agents that work together to improve vehicle lateral stability and simultaneously reduce workloads of drivers during path tracking. The cooperative control strategies of two agents are obtained through Pareto-optimality theory to ensure optimal control performance of AFS and DYC. Then, on the basis of dynamic interaction between agents, terminal constraints, including terminal cost function and terminal input with local static feedback, are designed to guarantee the asymptotic stability of the close-loop system. Finally, virtual simulations are conducted to evaluate the proposed controller. The results indicate that the proposed control architecture can effectively preserve vehicle stability and reduce workloads of drivers, especially for the inexperienced driver. Furthermore, the hardware-in-loop (HIL) test results also demonstrate the feasibility of the proposed controller. [ABSTRACT FROM AUTHOR]

In this paper, an optimal consensus-based event-triggered control strategy is proposed to coordinate multiple distributed energy resources (DERs) in a dc microgrid. In the proposed control strategy, the average bus voltage restoration and the proportional current sharing are integrated by transforming the coordinated control problem into an optimization problem. The proposed solution enhances the resilience of the controller strategy in extreme events with uncertain initial states. Accordingly, the proposed control strategy provides a sampled-data-based event-triggered mechanism considering the limited availability of communication resources, which reduces communication burdens and avoids Zeno behaviors. The sufficient conditions are demonstrated using the Lyapunov–Krasovskii functional method for maintaining the stability of the proposed control strategy. Several case studies are presented using the PSCAD/EMTDC platform and the results are discussed to validate the effectiveness of the proposed control strategy for enhancing the dc microgrid resilience. [ABSTRACT FROM AUTHOR]

This paper proposes an envelope control framework for four-wheel independently actuated autonomous ground vehicle (AGV) to regulate it on desired path and simultaneously control it to the driving limits. The envelope control framework is achieved based on the integrated control of active front-wheel steer and direct yaw-moment control. In a speed controller, the G-G diagram is used to describe the driving limits on each path segment. The desired traction and braking force is calculated according to the G-G diagram and desired path. In a path-following controller, a feedforward–feedback lateral controller is designed to calculate the desired steering angle to follow the desired path. In a yaw-moment controller, the β–r phase portraits are utilized to describe the handling limits. The yaw-moment controller aims at keeping the AGV from losing stability in limit driving, which is calculated through a sliding mode controller and provided by the independent motors actuation. Through an independent driving technique, the tyre cornering stiffness is estimated online based on the predefined Magic Formula model to improve the controller's robustness. An autonomous Formula Student racecar developed by the authors is used as testbed. The autonomous driving experiments on racetrack validate the efficiency of the proposed controller. [ABSTRACT FROM PUBLISHER]

This paper introduces the development and implementation of a ball mill grinding circuit simulator, NEUSimMill. Compared to the existing simulators in this field which focus on process flowsheeting, NEUSimMill is designed to be used for the test and verification of grinding process control system including advanced control system such as integrated control. The simulator implements the dynamic ball mill grinding model which formulates the dynamic responses of the process variables and the product particle size distribution to disturbances and control behaviors as well. First principles models have been used in conjunction with heuristic inference tools such as fuzzy logic and artificial neural networks: giving rise to a hybrid intelligent model which is valid across a large operating range. The model building in the simulator adopts a novel modular-based approach which is made possible by the dynamic sequential solving approach. The simulator can be initiated with connection to a real controller to track the plant state and display in real-time the effect of various changes on the simulated plant. The simulation model and its implementation is verified and validated through a case of application to the design, development, and deployment of optimal setting control system. [ABSTRACT FROM AUTHOR]

Coordinated regulation for the outputs from renewable energy sources is an appealing issue in future smart grid. This paper presents a distributed control strategy for multiple photovoltaic generators (PVs), which makes all the PVs have the same reserve ratio with respect to their maximum available power, but also makes their aggregated output support power network by providing power regulation service within the power limit. In addition, an estimation method is proposed to get the maximum available power of PV. The proposed control strategy is nearly center-free, i.e., there is no centralized station which collects the output of each PV and sends the power command to each PV, and only uses local communication networks (CNs) to avoid expensive sometimes unreliable, long distance communications. Simulation results based on the IEEE standard 123-bus distribution system are presented and discussed, illustrating the effectiveness of the proposed control strategy. [ABSTRACT FROM PUBLISHER]

This paper addresses the control problem of heterogeneous vehicle platoons subject to disturbances and modeling errors. The objective is to guarantee spatial-geometry constraints of vehicles in a platoon. We deal with the case where a predecessor-leader following (PLF) communication topology is used and heterogeneous vehicle dynamics is subject to disturbances. To estimate the lumped disturbance, the technique of unknown input proportional multiple-integral (PMI) observer is employed such that both the state and the disturbance are simultaneously estimated. Moreover, tube-based model predictive control (TMPC) is used and the corresponding control law is composed of a feed-forward term, a feedback term, and a disturbance compensation term. The gains in the integrated control strategy are optimized by utilizing the particle swarm optimization (PSO) algorithm with an H∞ performance index of an augmented error system. It is proved that the deviations between the actual system and the nominal system are bounded in a robustly positively invariant (RPI) set, that is, the main objective is guaranteed. With the proposed control strategy, simulations and comparisons are carried out. We can see that the control performance of the proposed strategy is significantly improved while the computational time is reduced compared with existing methods. [ABSTRACT FROM AUTHOR]

The conveyance of steel-plates is one of the potential uses of the magnetic levitation technology in industry. However, the electromagnetic levitation systems inherently show nonlinear feature and are unstable without an active control. Well-known U-shaped or E-shaped electromagnets cannot provide redundant levitation with multiple degrees of freedom. In this paper, to achieve the full redundant levitation of the steel plate, a quadruple configuration of U-shaped electromagnets has been proposed. To resolve the issue of instability and attain more robust levitation, a centralized control algorithm based on a modified PID controller (I-PD) is designed for each degree of freedom by using the Manabe canonical polynomial technique. The model of the system is carried out using electromechanical energy conversion principles and verified by 3-D FEM analysis. An experimental bench is built up to test the system performance under trajectory tracking and external disturbance excitation. The results confirm the effectiveness of the proposed system and the control approach to obtain a full redundant levitation even in case of disturbances. The paper demonstrates the feasibility of the conveyance of steel plates by using the quadruple configuration of U-shaped electromagnets and shows the merits of I-PD controller both in stabilization and increased robust levitation. [ABSTRACT FROM AUTHOR]

The coordinated operation of distributed energy resources such as storage and generation units and also loads is required for the reliable operation of an islanded microgrid. Since in islanded microgrids the storage units are commonly responsible for regulating the voltage amplitude and frequency in the local power system, the coordination should consider safe operating limits for the stored energy, which prevents fast degradation or damage to the storage units. This paper proposes a centralized control architecture, applicable for local area power systems such as a small-scale microgrid. The centralized architecture is based on three supervisory control tasks which consider: active power curtailment of generation for avoiding overcharge of the storage units, load shedding actions for preventing deep discharge of the storage units, and equalization of the state of charge (SoC) among distributed storage systems for avoiding uneven degradation. The proposed equalization method has proved to be effective for equalizing the SoC of distributed energy storage systems and for ensuring uniform charge/discharge ratios regardless of differences in the capacity of the storage units. Additionally, the strategy is complemented with an optimal scheduling of load connection, which minimizes the connection and disconnection cycles of the loads within a time horizon of 24 h. The proposed architecture is verified experimentally in a lab-scale prototype of a microgrid, which has real communication between the microgrid and the central controller. [ABSTRACT FROM AUTHOR]

This paper proposes a systematic approach to balance the active power between photovoltaic generators (PVs) and loads in autonomous microgrids. To achieve this, a distributed algorithm is designed to estimate the power difference between generation and consumption, then a finite-time consensus protocol is introduced to regulate the outputs of all the PVs in a cooperative and timely fashion, and the frequency deviation caused by active power unbalance can be compensated as well. In particular, the proposed distributed estimation and secondary control strategy is completely distributed and center-free in the sense that each PV and load are both self-organizing and global-awareness with only local communication, no centralized monitors are needed. Simulations on the standard IEEE 37-bus network are presented to verify the effectiveness of the proposed strategy. [ABSTRACT FROM AUTHOR]

This paper presents a class of centralized and decentralized adaptive fault tolerant control (FTC) for N-interconnected subsystems which can make up a global system coupling. An integrated model for the combined dynamics of two interconnected subsystems is developed which provides an ideal frame work for the design of centralized and distributed FTC controllers. The additive FTC schemes obtained consist of an on-line estimation of faulty parameters for overall interconnected system and N-interconnected subsystems. Then, the estimated parameters are used to compute the feedback controller gains. The fault estimation and compensation is handled in this paper using the Singular Values Decomposition (SVD). Many strong points of the different architecture of FTC techniques are noted such as the possibility of making appropriate selection of control schemes based on specific representations (overall interconnected system/distributed Nsubsystems coupling) of plant, as well as the facility of implementation by distributed processing FTC approach and some characteristics to realize improved performance of decentralized control. Numerical and simulation results are provided to demonstrate the effectiveness of the proposed fault tolerant controls. [ABSTRACT FROM AUTHOR]

This paper presents autonomous control algorithms for electrical loads like HVAC (Heating, Ventilation, and Air Conditioning) systems. These algorithms permit a load to become “aware” of the operation of neighboring loads using nonintrusive measurements of the utility voltage. Analogous to the way a good driver is aware of neighboring cars while driving, loads can use this information to become “self-driving.” For HVAC systems, this permits maintaining occupant comfort while simultaneously reducing bulk peak electrical demand. Electric energy consumption for each load occurs on a schedule, interleaved with the operation of neighboring units. The algorithms are demonstrated here using simulation models developed from nonintrusive load monitoring (NILM) data collected from the microgrid of a US Army forward operating base (FOB). The general approach, however, can be applied in many other venues, e.g., to minimize peak load on distribution transformers in a section of the conventional utility. [ABSTRACT FROM AUTHOR]

Low-frequency high-voltage ac transmission scheme has recently been proposed as an alternative approach for bulk power transmission. This paper proposes a multi-period optimal power flow (OPF) for a multi-frequency HVac transmission system that interconnects both conventional 50/60-Hz and low-frequency grids using back-to-back converters with a centralized control scheme. The OPF objective is to minimize system losses by determining the optimal dispatch for generators, shunt capacitors, and converters. The OPF constraints include the operational constraints of all HVac grid and converter stations. The resulting mixed-integer nonlinear programing problem is solved using a proposed framework based on the predictor-corrector primal-dual interior-point method. The proposed OPF formulation and solution approach are verified using a multi-frequency HVac transmission system that is modified from the IEEE 57-bus system. The results with the optimal dispatch from the proposed method during a simulated day show a significant loss reduction and an improved voltage regulation compared to those when an arbitrary dispatch is chosen. [ABSTRACT FROM AUTHOR]

In recent years, the continuous growth of grid-integrated wind power generation causes reduction in the inertia of power system, which deteriorates primary frequency regulation (PFR) of grid. Therefore, wind farms (WFs) are recommended to operate at deloaded condition, rather than maximum power point, to provide sufficient primary reserve for improvement of the PFR. To improve PFR, the droop control uses this reserve and the inertia support emulates stored kinetic energy from the rotor of wind turbines. In this paper, a distributed synchronized control (DSC) technique is proposed which uses optimum power share ratio (PSR) and the frequency of each WF at the point of common coupling to calculate the droop. The optimum PSR is based on the ratio of primary reserve at the WF and required change in rotor speed for the WF. An iterative method is proposed to obtain the PSR of each WF. To reduce delay effect on proposed DSC performance, the synchronized droop varies differently with increasing communication delays. The effectiveness of proposed DSC is tested in WF integrated 39-bus New England system and compared with distributed Newton method. The performance of proposed DSC is verified for different false data injection scenarios. [ABSTRACT FROM AUTHOR]

Purpose - The purpose of this article is to study how two different managerial environments of the state-controlled economy in Belarus - "private small business management" and "state or privatized large enterprise management" - influence middle managers' implementation of decisions. Two kinds of data are analyzed: "should" option or presented data, and "would" option or managers' preferred in reality option of activity. Design/methodology/approach - The research was completed in two stages: survey research based on open-ended questions and face-to-face structured interviews based on the principle of controllable projection. A total of 193 decisions are analyzed. Findings - Managers of large and state enterprises should present an appearance of active tactics, but in reality they would prefer tactics of delay or no-action. Managers of small private businesses should present all varieties of tactics except a tactic of inaction. In reality, they would prefer to act directly, or less often, to wait or not act at all. Research limitations/implications - The effect of other organizational factors than the size and form of ownership should be subjects of future research. The comparison of decision implementation tactics of mid-level managers in large and small organizations, in state-owned and private companies in countries with different economies should also be studied. Practical implications - The findings of this paper have managerial implications for companies willing to open subsidiaries or establish partnership with enterprises from countries with a state-controlled economy. Originality/value - The paper is original research that proves the influence of the business environment and characteristics of a company on a middle manager's behavior. [ABSTRACT FROM AUTHOR]

This paper describes the derivation of dynamical models for mobile robots using system-identification methods and shows how such models can be used in the control of autonomous devices. Unlike traditional approaches that are based on the system physics alone, in this paper, an autoregressive model structure is derived from the physics of the process, and its parameters are estimated using real input and output data. From the resulting model, efficient control can be obtained for centralized and remotely controlled robots (typically externally observed) with little or no local ‘intelligence,’ thus overcoming many of the severe shortcomings presented by such systems. System dead time is one example of a serious problem that can be efficaciously minimized by using the model as an online predictor. Several experimental results using small differential-driven robots are included to demonstrate the applicability and robustness of the suggested procedure in actual real-world scenarios. [ABSTRACT FROM AUTHOR]

A new communication strategy for decentralized control of paralleled multi-inverter systems is introduced in this paper. The proposed strategy utilizes the common mode signal's circuit in the paralleled system as a channel of communication between individual inverters. Source voltage synchronization for paralleled inverters is presented to demonstrate its effectiveness. One inverter module acts as a source and a synchronized signal is sent by means of frequency modulation in this channel to all other modules via the common mode current. Each module will then receive and transform the signal to be used as a synchronized voltage command for individual inverters. The approach enables synchronization in the paralleled multi-inverter system and the method is not affected by external factors such as load change, output voltage variation, and different types of loads. The principle of operation, performance of the proposed strategy, as well as the experimental evaluation with three single-phase paralleled inverters are discussed and presented in this paper. [ABSTRACT FROM AUTHOR]

In this paper, a single-stage solution for solar photovoltaic (PV) pumping system using a dual-inverter fed open-end winding induction motor drive is presented. The three-level dual-inverter requires a low PV bus voltage compared with its conventional three-level counterpart. This could avoid large string of PV modules and helps in reducing the voltage rating of the capacitors and semiconductor devices used in the system. This may further help in reduction of cost of the system. The proposed single-stage system is operated using an integrated control algorithm, which includes the maximum power point tracking (MPPT), the $V/f$ control, and the sample-averaged zero-sequence elimination (SAZE) pulsewidth modulation (PWM) technique. While the MPPT algorithm ensures the extraction of maximum power from the PV source, the $V/f$ control improves the motor pump performance. Furthermore, the zero-sequence current is avoided by the SAZE PWM algorithm. Thus, the integrated control algorithm improves the overall performance of the system. Furthermore, this paper also presents the details of system design and analysis of its dynamic behavior during transient environmental conditions. The performance of the system is verified using MATLAB simulation and hardware prototype. [ABSTRACT FROM PUBLISHER]

This paper formulates sufficiency-type linear-output feedback decentralized closed-loop stabilization conditions if the continuous-time linear dynamic system can be stabilized under linear output-feedback centralized stabilization. The provided tests are simple to evaluate, while they are based on the quantification of the sufficiently smallness of the parametrical error norms between the control, output, interconnection and open-loop system dynamics matrices and the corresponding control gains in the decentralized case related to the centralized counterpart. The tolerance amounts of the various parametrical matrix errors are described by the maximum allowed tolerance upper-bound of a small positive real parameter that upper-bounds the various parametrical error norms. Such a tolerance is quantified by considering the first or second powers of such a small parameter. The results are seen to be directly extendable to quantify the allowed parametrical errors that guarantee the closed-loop linear output-feedback stabilization of a current system related to its nominal counterpart. Furthermore, several simulated examples are also discussed. [ABSTRACT FROM AUTHOR]

In this research, the objective is using 4 quadrotors in a group to carry out a certain weighted load. The load is connected by cables to each quadrotor. The equations of motion of the quadrotors are considered completely and without simplification. Unlike other researches, to express the relationship between the load and the quadrotors, the ropes are considered as springs, so they are pulled out and retracted during the mission. Formation control design and path tracking by the group is done by using feedback linearization control. Control protocol design is presented in two structure, centralized, and decentralized. Unlike other papers, in decentralized structure, there is no information communication between the agents to reduce the communication costs. The mission of the group is defined as the quadrotors first pick off the load from the ground and, then, track the desired path to reach the target point. When the load reaches the target point, the quadrotors should put the load on the ground and, then, land themselves. Cutting the cable of one of the quadrotors is applied to the system as a fault and in addition to providing a method to detect its occurrence, the performance of the centralized controller is checked in this situation. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

Cloud computing has been empowered with the introduction of Software-Defined Networking (SDN) which enabled dynamic controllability of cloud network infrastructure. Despite the increasing popularity of studies for joint resource optimization in the cloud environment with SDN technology, the realization is still limited for developing integrated management platform providing a simultaneous controllability of computing and networking infrastructures. In this paper, we propose SDCon, a practical platform developed on OpenStack and OpenDaylight to provide integrated manageability for both resources in cloud infrastructure. The platform can perform VM placement and migration, network flow scheduling and bandwidth allocation, real-time monitoring of computing and networking resources, and measuring power usage of the infrastructure with a single platform. We also propose a network topology aware VM placement algorithm for heterogeneous resource configuration (TOPO-Het) that consolidates the connected VMs into closely connected compute nodes to reduce the overall network traffic. The proposed algorithm is evaluated on SDCon and compared with the results from the state-of-the-art baselines. Results of the empirical evaluation with Wikipedia application show that the proposed algorithm can effectively improve the response time while reducing the total network traffic. It also shows the effectiveness of SDCon to manage both resources simultaneously. [ABSTRACT FROM AUTHOR]

Many benefits can be achieved through the implementation of a Microgrid controller, such as minimized cost, reduction in peak power, power smoothing, greenhouse gas emission reduction, and increased reliability of service. However, most Microgrid controllers found in the literature and in the industry optimize a single objective, which either exacerbates or does not solve the problems with integrating a high penetration of renewable energy. This paper presents a methodology of formulating a multiobjective optimization (MOO) so that each objective is quantified through valuation functions that can be specific to every Microgrid. The proposed approach attains a Pareto-optimal solution by directly comparing the quantified valuation functions and solving as if it were a single-objective optimization (SOO) problem. Three cases of controllers are presented and compared: 1)a base case system with no controller; 2)an SOO that optimizes the cost of energy; and 3)an MOO that optimizes five identified benefits. Results show that the proposed controller can mitigate the negative impacts of volatile generation to levels below that of the system load. [ABSTRACT FROM PUBLISHER]

Current link state routing is based on routing decisions made through distributed interactions among routers. Link state is disseminated by means of flooding, which possesses a few limitations, such as excessive message overhead and network-wide computation. Thus, we propose LSC, an extended link state routing protocol with centralized control, in this paper to address this problem. In LSC, link state advertisements (LSAs) are communicated between a centralized element (CE) and a forwarding engine (FE) rather than traditional flooding. Multiple CEs form a separate control network as a representation of the control plane. Through this control network, LSAs are disseminated to FEs in a determinate manner. We also propose a signaling protocol for independent path convergence in the control network, as well as a routing control algorithm to prevent unnecessary routing updates in the forwarding network. We implement a prototype LSC and evaluate its performance. Our experiments show that with the use of real topologies, LSC can accelerate network convergence and reduce message overhead compared with OSPF. Moreover, LSC is robust because having multiple CEs can prevent the occurrence of a single point of failure. LSC also scales well with network size by adding additional CEs to share in the processing load. [ABSTRACT FROM AUTHOR]

This paper presents a method for the real-time management of electric vehicles (EVs) charging processes. The proposed method aims to limit the peak load and to increase the number of rechargeable EVs with respect to the scenario in which no coordination action is performed, while achieving given constraints on the power distribution system. The approach is based on a tight interaction between a scheduling algorithm and a power-flow evaluation procedure. The scheduling algorithm finds the best charging periods for each EV. The power flow procedure checks the achievement of electrical constraints and evaluates the operational parameters of the grid. Simulations are carried out on a real electricity distribution system of a medium-sized Italian city. The results show that the proposed approach increases the number of rechargeable EVs up to 33%. At the same time, the peak load is reduced by 25%. The scheduling algorithm requires an average of 50 ms to evaluate each charge request on an ordinary computer, therefore allowing its use in real-time conditions. [ABSTRACT FROM PUBLISHER]

Monitoring is an important concept in network management as it helps network operators to determine the behavior of a network and the status of its components. Traffic engineering, quality of service, and anomaly detection also depend on monitoring for decision making. Software-defined networking (SDN) is becoming increasingly popular for network provision and management tasks. This paper surveys the tasks and challenges associated with SDN, providing an overview of SDN monitoring developments. Several design concepts, research directions, and open issues are also discussed. [ABSTRACT FROM AUTHOR]

Distributed generators have been widely used in modern power systems, and microgrids are becoming a key concept for the integration of multiple distributed generators and clusters of loads with great efficiency and high system reliability. In a microgrid, the control strategy is one of the most important issues. Various control schemes have been proposed to achieve the cooperation of distributed generators in a microgrid. This paper surveys cooperative control strategies for multiple distributed generators in DC microgrids. The three popular coordinated control strategies are presented: decentralized control, centralized control, and distributed control. The advantages and drawbacks of the control strategies are compared. Some intelligent control methods such as fuzzy logic control and neural network approaches are also briefly introduced in the context of microgrids. Further research trends and challenges in this area are also discussed. [ABSTRACT FROM AUTHOR]

Photovoltaic Distributed Generation (PV-DG) produces some technical, commercial, and regulatory challenges in distribution systems. The most important technical challenge are the overvoltages produced by a high PV-DG penetration, which modifies the voltage profiles along the network and disturbs the operation of conventional voltage regulation devices. Extensive research has been carried out using various regulation devices under different control schemes to mitigate this impact. This paper presents a review of the literature dedicated to mitigate these overvoltage problems, proposing the classification and definition of regulation devices and control schemes used. [ABSTRACT FROM AUTHOR]

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 proposes an algorithm to obtain better results in the integrated control by reflecting the characteristics of the individual control of the front wheel and the rear wheel of tram systems. In the case of the surface transportation, which has recently been introduced, severely curved driving performance is required for the downtown. It is possible to decrease the curve radius and to improve the performance of the straight driving with the individual torque control. Therefore, the individual torque control performance of the motor is the most important point of the surface transportation. The front and rear wheels have different torque characteristics, and the length of the bogie during curve travel also affects these results. This system is more controllable than the system with 1Controller 4Motor (1C4M) in the form of 2C4M with the front and rear wheels being individually controlled, allowing more precise control because of its higher degree of freedom. Because of this individually controlled characteristic, it is possible to control more precisely in the integrated control considering the characteristics of the front wheel and the characteristics of the rear wheel. The validity of the proposed control algorithm is verified by experimental results using a small-scale bogie system. [ABSTRACT FROM AUTHOR]

The power system is presently experiencing vital changes: it is advancing from a centralized structure to a decentralized one, primarily because of the enormous advancement of distributed renewable energy sources, so future power system obliges new control strategies. These systems must have the capacity to withstand new requirements, for example, the exceedingly disseminated nature, the irregularity of renewable energy sources and the restricted data transfer capacity for communications. Multi agent systems (MAS) have attributes that meet these prerequisites. A certain degree of distributed or collective intelligence can be accomplished through the connection of these agents with one another, participating or contending to achieve their objectives. This paper introduces outline of the fundamental ideas of MAS and its different platforms. Also, it provides a comprehensive survey on the power system applications in which MAS technique has been applied. For each power system application, technical details are also discussed. [ABSTRACT FROM AUTHOR]

Advanced microgrid (MG) is a likely model for reaching the goal of 100% renewable grid. A complete advanced MG control must steer the power flow in grid-connected mode; regulate voltage/frequency in islanded mode; and perform power sharing among distributed energy resources (DERs) in both modes. Power-based control (PBC) is a well-known centralized control capable of achieving these three targets. A serious disadvantage of usual MG structures using PBC approach is the existence of a single centralized grid-forming converter to form the islanded MG. Centralized grid-forming converter is a single point of failure, which reduces the capability of the MG expansion, and it is an expensive element for the MG. This paper proposes a MG control strategy using an improved centralized control together with a droop-based power-loop in distributed voltage-controlled mode (VCM) converters to allow the MG to operate in both modes, without a centralized grid-forming converter and critical islanding detection. Moreover, the new approach considers single- and three-phase DERs, controlled in VCM or current-controlled mode, and DERs with self-imposed limits, characterizing a heterogeneous MG. Real-time hardware-in-the-loop setup is used to test the proposed control strategy in several operating conditions considering ten heterogeneous DERs. Results show grid power flow control, power sharing, unbalance compensation, voltage/frequency restoration, and smooth transitioning between operating modes without critical islanding detection. • Precise grid power flow control. • Multiple grid-forming converters. • Proportional power sharing among heterogeneous distributed-energy resources. • Islanded operation with voltage and frequency restoration. • Smooth transitioning between operating modes without critical islanding detection. [ABSTRACT FROM AUTHOR]

This paper presents an integrated control strategy to achieve fast start-up and enable wide input frequency operation in a three-phase six-switch power factor correction (PFC) converter. Limiting the inrush current with simultaneously minimizing the start-up time is achieved by implementing a nonlinear compensator in the voltage control loop. In addition, the concerning issues regarding unity PFC operation with an accurate reference tracking in a system with wide input frequency variation (typical for more-electric-aircraft) are resolved by a second-order compensator integrated with a state-feedback controller in the current loop. For a proof-of-concept verification, a hardware prototype of 6 kW, three-phase six-switch PFC is developed and tested with the proposed integrated control strategy in a wide source frequency range (360–800 Hz) ac input that shows perfect unity power factor operation throughout. Both the start-up time and inrush current are reduced to < \text50\% of their values in conventional PI compensation. [ABSTRACT FROM AUTHOR]

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 (DR) mechanisms. Since DR 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 1-h-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. [ABSTRACT FROM PUBLISHER]

This paper presents a centralized control system that coordinates parallel operations of different distributed generation (DG) inverters within a microgrid. The control design for the DG inverters employs a new Model Predictive Control algorithm that allows faster computational time for large power systems by optimizing the steady-state and the transient control problems separately. An overall energy management system is also implemented for the microgrid to coordinate load sharing among different DG units during both grid-connected and islanded operations. The design concept of the proposed control system is evaluated through simulation studies under different test scenarios. The impact of the increased penetration of DG units on the distribution grid is also investigated using the proposed microgrid. The simulation results show that the operations of the DG units within the microgrid can be coordinated effectively under the proposed control system to ensure stable operation of the overall microgrid. [ABSTRACT FROM PUBLISHER]

This paper presents an integrated model and its solution algorithm for freeway corridor control during incident management. With a parallel arterial as the detour route, the proposed model aims at producing the optimal diversion rates from the freeway mainline to relieve the congestion at the incident segment and concurrently adjust signal timings at the arterial intersections to best accommodate the detour traffic. Different from previous studies, the presented model and algorithm have the following two critical features: 1) modeling explicitly the evolution of detour traffic along the ramps and surface streets with a set of dynamic network flow formulations to capture the local bottlenecks caused by demand surge due to diversion operations and to properly set the responsive signal timing plans and 2) developing a multiobjective optimization framework to maximize the utilization of the available corridor capacity via detour operations but not to incur excessive congestion on the arterials and ramps. This study employs a genetic algorithm (GA)-based heuristic to efficiently yield the reliable solution, depending on the decision maker's preference. Extensive numerical tests on a segment along the I-95 corridor with its neighboring arterials have demonstrated the potential of the developed model for integrated freeway corridor control. [ABSTRACT FROM PUBLISHER]

Wireless sensor networks utilize large numbers of wireless sensor nodes to collect information from their sensing terrain. Wireless sensor nodes are battery-powered devices. Energy saving is always crucial to the lifetime of a wireless sensor network. Recently, many algorithms are proposed to tackle the energy saving problem in wireless sensor networks. In these algorithms, however, data collection efficiency is usually compromised in return for gaining longer network lifetime. There are strong needs to develop wireless sensor networks algorithms with optimization priorities biased to aspects besides energy saving. In this paper, a delay-aware data collection network structure for wireless sensor networks is proposed. The objective of the proposed network structure is to minimize delays in the data collection processes of wireless sensor networks. Two network formation algorithms are designed to construct the proposed network structure in a centralized and a decentralized approach. Performances of the proposed network structure are evaluated using computer simulations. Simulation results show that, when comparing with other common network structures in wireless sensor networks, the proposed network structure is able to shorten the delays in the data collection process significantly. [ABSTRACT FROM PUBLISHER]

The efficiency of the current centralized air-traffic management is limited. A next-generation air transportation system should allow airplanes (manned and unmanned) to change their flight paths during the flight without approval from a centralized en route control. Such a scheme requires decentralized peer-to-peer conflict detection and collision-avoidance processes. In this paper, two cooperative (negotiation-based) conflict-resolution algorithms are presented: iterative peer-to-peer and multiparty algorithms. They are based on high-level flight-plan variations using evasion maneuvers. The algorithms work with a different level of coordination autonomy, respect realistic assumptions of imprecise flight execution (integrating required navigation performance), and work in real time, where the planning and plan-execution phases interleave. Both algorithms provide a resolution in a 4-D domain (3-D space and time). The proposed algorithms are evaluated experimentally, and their quality is studied in comparison with a state-of-the-art agent-based method—the satisficing game theory algorithm. [ABSTRACT FROM PUBLISHER]

In recent years, distributed generation, as clean natural energy generation and cogeneration system of high thermal efficiency, has increased due to the problems of global warming and exhaustion of fossil fuels. Many of the distributed generations are set up in the vicinity of the customer, with the advantage that this decreases transmission losses. However, output power generated from natural energy, such as wind power, photovoltaics, etc., which is distributed generation, is influenced by meteorological conditions. Therefore, when the distributed generation increases by conventional control techniques, it is expected that the voltage change of each node becomes a problem. Proposed in this paper is the optimal control of distribution voltage with coordination of distributed installations, such as the load ratio control transformer, step voltage regulator (SVR), shunt capacitor, shunt reactor, and static var compensator. In this research, SVR is assumed to be a model with tap changing where the signal is received from a central control unit. Moreover, the communication infrastructure in the supply of a distribution system is assumed to be widespread. The genetic algorithm is used to determine the operation of this control. In order to confirm the validity of the proposed method, simulations are carried out for a distribution network model with distributed generation (photovoltaic generation). [ABSTRACT FROM AUTHOR]

In this paper, an integrated approach combining offline precomputation of optimal candidate paths with online path retrieval and dynamic adaptation is proposed for a dynamic navigation system in a centralized system architecture. Based on a static traffic data file, a partially disjoint candidate path set is constructed prior to the trip using a heuristic link weight increment method. This method satisfies reasonable path constraints that meet the drivers' preferences, as well as alternative path constraints, that limit the joint failure probability for candidate paths. The characteristics of the proposed algorithm are the following: 1) The response time for online navigation demand is nearly linear with network size and less dependent on system load; 2) the veracity of the pretrip route plan based on the static data file is improved by taking travel time reliability into account; and 3) system optimization can be approximated without sacrificing driver preferences. The algorithm is tested on randomly generated road networks, and the numerical results show the efficiency of the approach [ABSTRACT FROM PUBLISHER]

Tens and hundreds of thousands of disturbances occur annually in modern power systems. The overwhelming majority of them are eliminated by relay protection devices and other automatic systems and by the actions of the dispatching personnel. A small fraction of the emergencies (tens of cases in such large power interconnections as those in the United States and Canada, Europe, and the United Power System (UPS) of Russia) result in significant system failures, sometimes of a cascading nature. They are consequences of unusual primary disturbances, failures of automatic emergency control systems, protection device malfunctions, and errors by personnel, but do not cause extreme consequences for the power system and the consumers. Of these, only some rare failures--blackouts--become catastrophes with severe long-term consequences for the national economies and population. Recent blackouts in North America, Europe, Russia, and other countries require specialists once again to pay closer attention to the blackout phenomenon. It is often believed that the philosophy of preventing blackouts should be based on dispatching personnel training, wide-area system visibility, and better computer models for the analysis of the stability and security of power systems. The authors of this paper also think that in emergency situations of a cascading nature, automatic emergency control systems should play a major role. A confirmation for this statement is the fact that from 1975 to 2005 there were no blackouts in the UPS of Russia (where automatic emergency control systems are widely used). At the same time, the Moscow blackout demonstrated that the growing problems in the Russia's UPS (such as aging equipment and load growth) made it also vulnerable to major blackouts. This stresses again that the electrical power industry faces common global problems and that a global effort, cooperation, and exchange of the best practices are needed to prevent blackouts. This paper describes the Russian principles and systems of dispatch and emergency control--a multilevel defense system protecting the Russian power grefid from developing cascade failures. [ABSTRACT FROM AUTHOR]

Aggregate thermostatically controlled loads (TCLs) are good candidates for providing load following services in power systems. This paper is concerned with the modeling, evaluation, and control problems of a population of heterogeneous TCLs. Specifically, the heterogeneous population is divided into multiple homogeneous clusters and each cluster, i.e., TCL aggregator, is modeled by an approximated three-input single-output state space model. Here, the aggregators serve as a bridge connecting the load utility and the terminal TCLs, which have their own decision makers and are responsible for aggregate estimation and command issuing. And aggregate evaluation is carried out for the aggregator so as to provide the aggregate regulation capacities and ramping rates, which is useful for setting of the reference power trajectory. Based on the established control model, we furthermore propose a hierarchical centralized control algorithm for a bus load utility to regulate all TCLs inside it so as to provide load following service, while not affecting the customers’ comfort levels. Finally, simulation results with respect to a common bus load are provided to demonstrate the effectiveness of the proposed aggregate modeling and the centralized load following strategy. [ABSTRACT FROM AUTHOR]

This paper presents a decentralized, mode-adaptive (DMA) guidance law for a Hamiltonian-based controller of an $N$-source, dc microgrid. Droop control is commonly used for decentralized control of microgrids. Unfortunately, droop control lacks the ability to autonomously adapt to the addition or removal of a source without the augmentation of an outer-loop controller. Centralized control methods provide solutions to these limitations, as well as providing the ability to globally optimize the system. To their detriment, centralized control methods are not scalable, and require system-wide information to be funneled through a central controller yielding a single point of failure. The DMA power apportionment scheme presented here aims to reduce the gap between droop control and centralized control by providing a method that can operate autonomously in the event of source and bus load fluctuations as well as reduce communication requirements of centralized control and, thus, increase resiliency and scalability. After development of the DMA, its performance is compared to the centrally controlled optimal exergy destruction power apportionment strategy, as well as a Hamiltonian-based droop control strategy. Finally, it is shown that for a sufficiently large number of converters supplying a microgrid, the presented decentralized, mode-adaptive strategy provides an efficient and practical alternative to both droop control and centralized control schemes. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

The paper raises the issue of controlling rural low voltage microgrids in an optimal manner. The impact of different criterion functions, related to the amount of energy exchanged with the distribution system operator network, the level of active power losses, the amount of energy generated by different energy sources and the value of financial performance measures regarding the microgrid operation, on the choice of operating points for devices suggested by the optimization algorithm has been analyzed. Both island and synchronous microgrid operation modes are being considered. We propose two variants of the optimization procedure: the first one is based on the particle swarm optimization algorithm and centralized control logic, and the second one takes advantage of the decentralized approach and Monte Carlo methods. A comparison of the simulation results for two sample rural microgrids, obtained for different objective functions, microgrid operation modes and optimization procedure variants, with the use of prepared algorithm implementations, has been provided. The results show that the proper choice of an objective function can have a crucial impact on the optimization algorithm’s behavior, the choice of operating points and, as a consequence, on microgrid behavior as well. The choice of the proper form of the objective function is the responsibility of the person in charge of both the microgrid itself and its operation. This paper can contribute towards making correct decisions in this area. Generally, slightly better results have been achieved for the centralized control mode of operation. Nevertheless, the results also suggest that in many cases the approach based on distributed logic can return results that are better or sufficiently close to the ones provided by the centralized and more sophisticated approach.

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.