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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 presents a non-contact three-point bending device based on magnetic levitation technology, in which a specimen can be bent while being levitated. As the levitated object needs to withstand an increasing bending load in levitated state, this requires the control system to have a strong robustness. Therefore, a centralized sliding mode controller (CSMC) was proposed for the levitation. Furthermore, based on CSMC, an adaptive centralized sliding mode controller with the bending load as scheduling variable (ACSMC), which is the novelty of this paper, were proposed to deal with the disturbance caused by the bending load. Simulation results demonstrated that ACSMC has good robustness to three typical bending loads, i.e., ramp load, sine load, step load. Finally, experiments were conducted and experiment results demonstrated that ACSMC allows the device to withstand ramp bending load, sine bending load and step bending load up to 50 N. [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]

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]

In this paper, a cascade control structure with the modified Smith delay compensator for controlling nonsquare MIMO process is proposed. The proposed structure is designed with two disturbance estimators and a setpoint tracking controller. The estimators reject the disturbances in the forward path. These estimators also take part in delay compensation. The design of setpoint tracking controllers and disturbance estimators uses simple mathematical calculations as compared to the conventional IMC-based controllers. In the proposed design, Grey wolf optimization technique has been used to optimize the predictor. The closed-loop system produces the desired servo and regulatory response. The internal stability and robustness of the proposed MIMO cascade control structure have been analyzed. An example of a physical process has been included to illustrate the novelty of the proposed control strategy over multivariable PID controllers in terms of the time-domain performance and delay compensation. query Please check the edit made in the article title. [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]

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]

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]

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]

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 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]

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]

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 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]

Considering the load balancing needs in edge computing network, this paper proposed a scheduling scheme based on centralized control. This scheme decided which nodes to deploy edge computing module firstly, then considered users' data and requests, minimized the average end-to-end delay of traffic through scheduling while meeting the load balancing constraints. The evaluation results indicate that the number of edge computing nodes and the load balancing level of computing and network resources may affect the average end-to-end delay of traffic. Selecting a small number of suitable nodes as edge computing nodes and making the load balancing level of computing and network resources appropriate can effectively reduce the average end-to-end delay. [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]

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]

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]

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 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]

This paper compares traditional local voltage control strategy with coordinated, optimization-based ones in low voltage (LV) distribution systems with photovoltaics and battery energy storage systems. Optimization-based strategies are formulated within a model predictive control (MPC) framework. Three strategies based on MPC are proposed and implemented, namely, centralized, decentralized and distributed MPC. The formulated strategies for voltage control are compared in a case study using a modified CIGRÉ European 3-area low-voltage network. Results indicate that decentralized MPC gives a better voltage profile in the network when compared to local voltage control strategy, since the latter inherently fails to maintain voltages of buses in the network not connected to photovoltaics or battery storage system within limits. Centralized MPC strategy is able to provide the optimal voltage profile across the network but utilizes 13 % higher reactive power from the control devices to achieve this when compared to decentralized MPC. The latter performs well as long as the reactive power reserves within an area is sufficient but faces drawbacks similar to that of local voltage control strategy when the reactive reserves are completely exhausted. Distributed MPC utilizes 1.3 % higher amount of reactive power reserves compared to centralized MPC in order to provide a network voltage profile similar to that of the latter while also yielding architectural advantages of decentralized MPC. [ABSTRACT FROM AUTHOR]

Aiming at the reasonable placement and efficient use of response data in the content centric network (CCN) , this paper proposed a cooperative caching and routing scheme based on local centralized control (CRLCC). Along the content delivery path, it determined the subsystem which had the biggest caching gain by matching labels in data packets. In subsystems, the proposed scheme selected the optimal placement according to available cache space of nodes and content activity. When a content was requested, this scheme looked for the requested content by combining local content placement with route forwarding. Simulation results show that this scheme can achieve higher cache hit ratio and hop reduction ratio, and make the cache distribution among nodes more uniform. [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]

Residential heating, ventilation and air conditioning (HVAC) systems usually employ on/off controllers to regulate the temperature. Generally, there is no supervisory controller which can use the weather forecast and electricity time of use (TOU) price information to reduce the overall operating cost of the equipment. Lack of a supervisory controller results in higher operating costs of the HVAC system. In this paper, a model predictive control (MPC) based supervisory controller is designed to shift the heating and cooling load of a house to off-peak hours. Supervisory MPC generates the temperature set-points trajectory for on/off controllers. The approach was verified through extensive experiments in an experimental archetype house. By employing the supervisory controller with variable set-points 16% cost savings were obtained when compared to the fixed zone temperature set-points at 25 °C. More significant savings of about 50% were seen when MPC-based centralized controller was compared with the fixed zone temperature set-points of 24 °C. [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]

The traditional model predictive control (MPC) design strategy heavily depends on the discritization of the non-linear model of DC/DC power converters to approximate the direct current (DC) microgrid system model. The system model does not includes the whole information of the physical implementation of the system. Assumptions have been made to add the model and sensor uncertainties in the system model to form a model with fully physical information that enables its solution through the linear kalman filtering method (LKFM). Due to the unbounded of the DC bus voltage estimation error, the instability of the LKFM during transient response increases exponentially. To standardize the MPC model and ensure bounded the DC bus voltage estimation error, a centralized controller design for DC bus voltage estimation error constrained is proposed in this paper. The proposed system model is constructed from DC/DC power converters and then translated into a deterministic model. Through measurements and time updates, the LKFM has been employed to estimate the DC bus voltage. The linear quadratic regulator is used for stabilizing the DC bus voltage estimation and current sharing error between DC/DC power converters. During a transient response, an integral action is utilized to close the loop and eliminate an error in DC bus voltage. A feedback control rule of the DC bus voltage estimation and a Riccati equation have been used to develop the proposed controller. Finally, the proposed approach was validated using Simulink, the Hardware-in-the-loop laboratory, and compared with conventional control approaches. Moreover, the LKFM's stability was examined using exponential stability criteria. [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]

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]

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 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 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 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]

Abstract: This paper addresses the problem of centralized optimization of an interconnected power system partitioned into several regions controlled by different transmission system operators (TSOs). It is assumed that those utilities have agreed to transferring some of their competencies to a centralized control center, which is in charge of setting the control variables in the entire system to satisfy every utility’s individual objective. This paper proposes an objective method for centralized optimization of such multi-TSO power systems, which relies on the assumption that each TSO has a real-valued optimization function focusing on its control area only. This method is illustrated on the IEEE 118 bus system partitioned into three TSOs. It is applied to the optimal reactive power dispatch problem, where the control variables are the voltage settings for generators and compensators. After showing that the method has some properties of fairness, namely freedom from envy, efficiency, accountability, and altruism, we emphasize its robustness with respect to certain biased behavior of the different TSOs. [Copyright &y& Elsevier]

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]

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]

Microgrids are envisioned as one of the most suitable alternatives for the integration of distributed generation units in the utility grid, as they efficiently combine generation, energy storage and loads in the same distribution network. In this context, hybrid ac/dc microgrids are arising as an interesting approach as they combine the advantages of ac and dc networks and do not require excessive modifications in the distribution network. However, they require more complex control strategies as they need to control the ac and dc networks and the interface power converter simultaneously. This paper identifies and analyses the control strategies that can be implemented in hybrid microgrids for an adequate power management in grid-tied and islanded modes of operation. The review is focused on hierarchical controls as they are the most extended approach in the literature. A classification has been elaborated, which covers the three main levels of hierarchical control strategies (primary, secondary and tertiary). Each of the levels has been independently studied in order to provide a comprehensive analysis of the alternatives found in the literature. The future trends related to this topic show that a higher research effort is required regarding the control of the interface device and the ancillary services that the management strategy must provide—e.g. blackstart, transition between islanded and grid-connected modes of operation, interconnection of microgrids, etc. [ABSTRACT FROM AUTHOR]

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

The potential of plug-in (hybrid) electric vehicles (PHEVs) to participate in power system control, via the vehicle-to-grid program, is increasing rapidly. In several recent studies, PHEVs are employed to participate in system frequency regulation; however, no attention has been paid to the impact of single-phase connection of these distributed energy sources. This paper addressed the use of PHEVs to stabilize the frequency in microgrids and/or weak grids which lack enough inertia considering the single-phase nature and communication delays. Small-signal analysis is used to evaluate the performance of both droop and virtual inertia control methods, and show how time delay of a centralized control could impact system stability. Advantages and disadvantages of distributed control are studied, and a new method based on a combination of both centralized and distributed control is proposed to mitigate the impact of asymmetrical virtual inertia while it allows the utilization of all available PHEVs for active power however asymmetric they are. Time-domain simulations are used to verify the analytical studies. [ABSTRACT FROM AUTHOR]

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]

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

• A high-speed data acquisition system was designed based on PXI Express. • The software adopts Visual Studio development environment and Visual C# language. • The system is integrated into the HL-2A centralized control system based on EPICS. • The Epics C# application was developed to realize the remote control under EPICS. • The system can work stably at 10KSps sampling rate. In order to meet the increasing experimental requirements of HL-2A tokamak device discharge and improve the integration of HL-2A host centralized control system, this paper designs a high-speed data acquisition system based on PXI Express. In order to enable the fast acquisition system to be integrated into the HL-2A host centralized control system under the EPICS platform for centralized control and management, it mainly describes how to realize the communication between fast acquisition signal system based on C# and the upper layer OPI through the PON network under the EPICS platform. The data acquisition system hardware adopts PXIe-based chassis, embedded controller and high-speed synchronous acquisition card, which has the advantages of good mechanical encapsulation, high modularity and high sampling rate. The software adopts a measurement and control system development platform based on Microsoft. NET platform, Visual Studio development environment and Visual C# language. In this paper, the Epics C# library was studied, the EPICS Server application was developed and the remote control of the state and parameters in HL-2A host engineering system was realized. The system runs stably in the HL-2A device 2018 experiment. The result shows that the system can work stably at 10KSps sampling rate, which can better meet the needs of the device operation. This work completed the basic framework of the HL-2A Tokamak host centralized control system. And the technology and method can provide reference for the design of the next-generation device HL-2 M host centralized control system of the, laying a good foundation. [ABSTRACT FROM AUTHOR]

• A new structure is presented for the centralized control of hybrid microgrids. • Improve system stability by modeling and analysis of all system state variables. • Recovery of voltage and frequency system in islanded condition and load changes. • Using bidirectional interface converter to improve voltage and frequency stability. • Comparison of centralized and decentralized control to reduce system fluctuations. In this paper, based on the nonlinear controller, a new structure is presented for centralized control of hybrid microgrids. In the proposed model, AC and DC buses are used to connect AC and DC sources and loads respectively. A bidirectional interface converter (BIC) is provided for the electrical and control connection of these two buses. Here, based on the generalized backstepping method (GBM), a new method is presented for integrated and simultaneous controlling of AC bus frequency and DC bus voltage. The advantages of this method are the centralized control of the hybrid microgrid, taking into account the dynamics of the whole system and the interaction of its state variables with each other. Harmonized and optimal exchange of power and precise regulation of control signals in this structure has led to improved stability and thus improved system performance. The comparative results of centralized and decentralized control show the efficiency of the proposed model to reduce fluctuations and improve the stability of the system. [ABSTRACT FROM AUTHOR]