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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. [Copyright &y& Elsevier]

This paper proposes a novel inertia-enhanced distributed control method to complement the inertia of microgrids. The rate of change of frequency (RoCoF) and the rate of change of voltage (RoCoV) are employed in this paper to quantify the frequency inertia and voltage inertia, respectively. Then, a fully distributed algorithm with constrained changing rates is proposed. By bounding the changing rates of frequency and voltage during the consensus control, the algorithm can address the consensus problem while enhancing the inertia of microgrids. Compared with most inertia control methods, the proposed method can utilize the reserve power of scattered DGs to supply inertia. Besides, it performs better under disturbances and delays than conventional distributed control methods. The effectiveness of the proposed method is validated by several cases in MATLAB/Simulation and a hardware experiment. [ABSTRACT FROM AUTHOR]

In DC distribution networks, the uncertainties of renewable energies and loads cause frequent voltage fluctuations. In this paper, a voltage regulation strategy based on the combined coordination of centralized optimal control (COC) and adaptive droop control (ADC) is proposed for droop-controlled DC distribution networks. In the COC strategy, the operation reference power of voltage source converters (VSCs) is optimized using the bus injection power measurements to improve the voltage profile and balance the power loading rates of different VSCs. The VSC capacity margin constraint is established to ensure that the capacity margin of each VSC is sufficient to cope with the unexpected fluctuation of loads and renewable energies. Then, an ADC strategy is adopted to handle voltage fluctuation between adjacent two COCs. In the ADC strategy, the operation reference power of the VSCs is further adjusted to recover the voltages. The voltage regulation is achieved based on the relationship among the VSC voltages and the minimum/maximum voltages of the whole network, which does not depend on the information of each nodal voltage and thus real-time network communication is avoided. The simulation results show that the proposed voltage regulation strategies can effectively improve the voltage profile under various uncertain environments. [ABSTRACT FROM AUTHOR]

Volt/VAr Optimization (VVO) is becoming increasingly crucial in distribution management systems with renewable sources that require setting their reactive power in coordination with legacy voltage and reactive power control devices. This paper presents a VVO method that operates in complex variables based on the Wirtinger calculus; it employs a penalty method that keeps voltage magnitudes and controller parameters within limits together with a probabilistic rounding technique for handling switched device variables. The complex variable implementation permits using the compensation technique when solving the Karush-Kuhn Tucker (KKT) system, thus achieving a significant speedup due to limiting the number of linear system factorizations. The proposed method is contrasted with a classical VVO implementation employing discrete coordinate search from the current operating point and an enhanced version that uses sensitivity information. Numerical results on distribution networks having up to 3147 nodes show that the proposed method is significantly faster than classical methods and gives operating points free of voltage magnitude violations and lower power loss. [ABSTRACT FROM AUTHOR]

This paper presents a complete wave-to-wire approach to the modeling of wave energy farms. It captures all the main peculiarities of such applications, from the variability of sea waves to the issues related to the grid integration of a multi-MW wave farm, including the hydrodynamic modeling of wave energy converters (WECs). The paper specifically discusses the different levels of control of a wave farm and their integration and coordination. These are crucial to meet the power quality requirements at the point of common coupling (PCC) and ensure the efficiency of the power transfer from the waves to the main electric grid. A specific real-time technique for the centralized control of a wave farm is also proposed, which is exemplified with reference to the PCC voltage control in the real test case of bimep. Critical cases of weaker grids are also considered to extend the validity of the analysis. [ABSTRACT FROM PUBLISHER]

Purpose – The purpose of this paper is to provide a hybrid adaptive impedance-leader-follower control algorithm for multi-arm coordination manipulators, which is significant for dealing with the problems of kinematics inconsistency and error accumulation of interactive force in multi-arm system. Design/methodology/approach – This paper utilized a motion mapping theory in Cartesian space to establish a centralized dynamic leader-follower control algorithm which helped to reduce the possibility of kinematics inconsistency for multiple manipulators. A virtual linear spring model (VLSM) was presented based on a recognition approach of characteristic marker. This paper accomplished an adaptive impedance control algorithm based on the VLSM, which took into account the non-rigid contact characteristic. Experimentally demonstrated results showed the proposed algorithm guarantees that the motion and interactive forces asymptotically converge to the prescribed values. Findings – The hybrid control method improves the accuracy and reliability of multi-arm coordination system, which presents a new control framework for multiple manipulators. Practical implications – This algorithm has significant commercial applications, as a means of controlling multi-arm coordination manipulators that could serve to handle large objects and assemble complicated objects in industrial and hazardous environment. Originality/value – This work presented a new control framework for multiple coordination manipulators, which can ensure consistent kinematics and reduce the influence of error accumulation, and thus can improve the accuracy and reliability of multi-arm coordination system. [ABSTRACT FROM AUTHOR]

Distributed control is the most popular control strategy for controlling numerous slave devices. However, the performance of slave devices is hard to improve because the control algorithm is handled by the commercial slave devices. Therefore, this paper proposes a hybrid control structure that follows the concept of centralized control strategy and handles part of the control loop on the master computer in a distributed control system through EtherCAT fieldbus. In this study, different advanced control methods such as robust control and learning control were applied to handle the position control loop of a scanning mirror system in a selective laser melting (SLM) system with stringent demand of position error around 40 µm based on EtherCAT fieldbus. By designing a proper controller, the experiment results showed that the tracking performance was significantly improved. The tracking error dropped by about 80% after the proposed hybrid control structure was applied. By applying the proposed hybrid control structure, one can improve the high-performance-requirement devices, while reducing the calculation burden of the master computer for other low-performance-requirement devices by retaining the benefit of distributed control. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM PUBLISHER]

This paper proposes an optimal control algorithm through lateral displacement and yaw angle in curved road of shallow-depth subway systems. In the case of the surface transportation, which has recently been introduced, curved driving performance is required for the downtown. The existing research works are the main research theme of the lateral displacement restoration control, but there is a limit to smooth operation when the curve is run only by receiving the lateral information. However, when the yaw angle displacement information is obtained, it is possible to consider the turning angle of the vehicle while the vehicle is driving in a curved road. However, it is difficult to control because the change of yaw angle is more sensitive than lateral drift. Therefore, this paper suggests an algorithm that uses yaw angle displacement control. The validity and usefulness of the proposed control algorithm is verified by experimental results using a small-scale bogie system. [ABSTRACT FROM AUTHOR]

This paper presents a control of the parallel operation of diode rectifier based high-voltage direct current (DR-HVDC) and voltage source converter based HVDC (VSC-HVDC) links. The two links are connected to offshore wind farms (OWFs). The VSC-HVDC controls the voltage and frequency of the offshore AC-grid needed for the OWFs start-up. The proposed grid forming control is based on controlling the OWFs voltage by controlling the active power balance at the VSC-HVDC AC-bus. When the OWFs inject more power than a certain active power reference established for the VSC-HVDC, the OWFs voltage increases and the DR-HVDC starts conducting. Then, the offshore voltage automatically accommodates the required value for transmitting the OWFs power through the DR-HVDC link while the system frequency is controlled by the VSC-HVDC through satisfying the reactive power balance. The power transmitted through the VSC-HVDC can be set by adjusting the corresponding power command while the DR-HVDC will automatically close the power balance. The main advantage of the proposed control system is that the VSC-HVDC can be sized just to support the system energization; while once the OWFs are in operation, the DR-HVDC will be loaded automatically. Simulation results verify the proposed control system. [ABSTRACT FROM AUTHOR]

The discrete coordinate-descent algorithm is a practical approach that is currently used in centralized Volt/VAr Control (VVC) implementations, mainly due to its good performance and speed for real-time applications. Its viability is however challenged by the increasing number of distributed generation that contribute to the VVC solution, in addition to the conventional transformer taps and switched capacitors. This paper presents the exact computation of sensitivity factors that speed up the discrete coordinate-descent implementation, by significantly reducing the number of forward/backward substitutions in the current injection power flow method; the speed up is achieved without affecting the control setting quality of the original implementation. The optimality of the discrete coordinate-descent solutions is investigated by computing the gaps relative to mixed-integer linear programming set-points, derived from a polyhedral reformulation of the VVC problem. The sensitivity-based discrete coordinate-descent algorithm is tested starting from two initial points, the default one given by the current control set-points, and a continuous solution obtained from a linear approximation of the VVC problem. Numerical results on networks with up to 3145 nodes show that the sensitivity-based approach significantly improves the runtime of the discrete coordinate-descent algorithm, and that the linear programming initialization leads to VVC solutions with gaps relative to the mixed-integer set-points that are less than 0.5%. [ABSTRACT FROM PUBLISHER]

With dramatically increased data traffic, the traditional low-frequency (LF) wireless local area networks (WLAN) are facing several difficulties, particularly, limited available spectrum resources and low network efficiency. While the use of millimeter-wave (mmWave) could bring more spectrum, WLAN in high-frequency (HF) suffers poor reliability. In addition, the current distributed WLAN architecture and the coupled data and control planes lead to inefficient management and poor performance with increased network scale, which cannot meet the stringent requirements from diverse applications. In overcoming these difficulties, the control plane and data plane decoupled network architecture and sub-6 GHz and mmWave dual-band cooperation are considered to be the critical solutions to improve the system performance in 5th-Generation (5G) and beyond networks. Therefore, to improve the throughput and reliability of the future WLAN, we propose a control plane and data plane decoupled WLAN architecture in this paper that supports both sub-6 GHz and mmWave based on the existing control plane and data plane decoupled WLAN concept. Furthermore, new multi-beam transmission and sub-6 GHz and mmWave dual-band cooperation mechanisms are developed to improve the throughput and reliability in our proposed WLAN architecture. Performance analysis and simulation show that with the multi-beam transmission and sub-6 GHz and mmWave dual-band cooperation mechanisms in our proposed WLAN architecture, throughput and reliability are both significantly improved when compared with the traditional distributed WLAN architecture and operation mechanism. [ABSTRACT FROM AUTHOR]

Supercapacitor energy storage systems (ESS) play a significant role in light rail vehicles LRV with no need for overhead lines and the pantograph. As the ESS of LRV demand short charging time and high-power supply, it is crucial to achieve the rapid energy balancing for series-connected supercapacitor modules of the ESS. To address this issue, this paper proposes a distributed control scheme for state-of-energy (SoE) balancing of supercapacitor modules. In order to provide the sufficient balancing current, the push–pull converter is introduced to transfer the energy among supercapacitor modules in the low working voltage. Then, the distributed SoE balancing strategy is proposed by regulating the balancing circuit according to the SoE deviation of neighboring supercapacitor modules. The ESS prototype is built to validate that the proposed strategy can reduce the balancing time and improve the energy balancing efficiency. [ABSTRACT FROM AUTHOR]

This paper takes advantage of wide-area measurements to propose a centralized nonlinear controller that acts on power system stabilizers (PSSs), to cooperatively increase the damping of problematic small-signal oscillations all over the system. Details are given to utilize existing stabilizers while causing minimum changes to the equipment and warranting improvement, or at least no detriment, of current system behavior. A set of gains is designed by linear state feedback control to respond to representative system conditions, and these are coordinated with an equal number of decision trees in charge of scheduling by switching. The resulting nonlinear controller is implemented on a model that resembles the characteristics of the Central American System, exemplifying its feasibility to be applied in large systems. The effect of time delay in the control loop is assessed, and the limits for tolerance to latency in this application are determined. [ABSTRACT FROM AUTHOR]

The abundant use of solar energy in Indonesia has the potential to become electrical energy in a microgrid system. Currently the use of renewable energy sources (RESs) in Indonesia is increasing in line with the reduction of fossil fuels. This paper proposes a new microgrid DC configuration and designs a centralized control strategy to manage the power flow from renewable energy sources and the load side. The proposed design uses three PV arrays (300 Wp PV module) with a multi-battery storage system (MBSS), storage (200 Ah battery). Centralized control in the study used an outseal programmable logic controller (PLC). In this study, the load on the microgrid is twenty housing, so that the use of electrical energy for one day is 146.360 Wh. It is estimated that in one month it takes 4.390.800 Wh of electrical energy. The new DC microgrid configuration uses a hybrid configuration, namely the DC coupling and AC coupling configurations. The results of the study show that the DC microgrid hybrid configuration with centralized control is able to alternately regulate the energy flow from the PV array and MBSS. The proposed system has an efficiency of 98% higher than the previous DC microgrid control strategy and configuration models. [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 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 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]

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]

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]

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]

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]

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]

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]

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]

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.

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.

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. [ABSTRACT FROM AUTHOR]