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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]

Due to the fast growth in wireless communication technologies and current demands of communication, there is a need for new network designs. Software-defined networking may solve the problems in the wireless network architectures. In this respect, it is a systematic literature analysis concerning SDN concepts in wireless networks, focused on network virtualization, centralized control, and dynamic resource management. The study shows that SDN improves performance, flexibility, and management of wireless networks; thus, centralized control and network virtualization enhance flexibility and performance. Dynamic resource management leads to better allocation, load balancing, and classy QoS. The process of deployment for wireless SDN is complex. Some of the constraints that impede the implementation of SDN include spectrum, scalability, and security. Some future research includes spectrum-aware SDN, scalable SDN architectures, secure SDN frameworks, and efficient QoS management. The challenges given and the research directions may enable SDN to revolutionize wireless networks in terms of performance enhancement, scalability, and better resource utilization. It is through this thorough literature study that the pros and cons of SDN in wireless networks are brought to the fore, paving the way for future improvements of infrastructure in wireless communications. [ABSTRACT FROM AUTHOR]

Peer-to-peer interconnection of households having on-site batteries, multi-port converters and solar panels to form a multi-port converter-enabled solar DC nano-grid is an emerging approach for providing affordable energy access in rural areas. Battery charge and discharge losses, distribution losses and converter losses are significant problem when operating such nano-grids. This paper presents a centralized control algorithm that can help address the power loss problem. The proposed algorithm uses a new problem formulation where the power loss problem is formulated as a two-stage convex optimization problem. The first stage of the optimization problem is an optimal battery dispatch problem for determining optimal battery charge and discharge currents. The second stage is an optimal current flow problem for determining optimal distribution voltages which corresponds to the optimal battery currents. Simulation results of the nano-grid show that the proposed algorithm can minimize the nano-grid power losses while facilitating the power exchange between the households. The proposed algorithm is suitable for small nano-grids where privacy of households is not a concern. In Part II of this paper we propose a distributed control algorithm that preserves the privacy of the households especially where the size of the nano-grid is large. [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]

This paper provides a detailed discussion on the implementation and effect of CHN Energy dispatching system in Xinshuo Railway. The successful deployment of this system has achieved a deep integration of CTC system and the dispatch information system, allowing them to operate in a unified manner, and improving the efficiency of transportation organization. To ensure the stability and safety of the system, potential safety risks of CTC system are thoroughly analyzed, and improvement strategies and preventive measures are proposed. In the practical application of the system, the problems are analyzed, and specific solutions and suggestions are put forward. Finally, the future development of the system in Xinshuo Railway is prospected, including centralized control, integrated interlocking, and modernized communication, etc. [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]

This paper proposes a Logic-Based Traffic Flow Control algorithm (LB-TFC) for integrated control of Ramp Metering (RM) installations and Variable Speed Limits (VSLs) in order to reduce traffic jams created at bottlenecks. LB-TFC estimates, for each control time step, the number of vehicles that should be held back or released by the control measures (i.e. the VSLs and the RM rates) in order to avoid the capacity drop (maximizing the outflow of the bottleneck). Afterwards, based on the resulting estimated number of vehicles, the VSLs and/or the RM rates are increased or decreased in a pre-specified order. In order to avoid or reduce traffic breakdowns, the proposed controller (LB-TFC) anticipates the future evolution of the bottleneck density by using a feed-forward structure. As a result, the performance of the controller is very efficient and similar to the one obtained with an optimal controller while the implementation of the controller (with an almost instantaneous computation time) and the tuning of the parameters are easy. In the second part of this work, published in a separate paper (‘Part 2: Simulation and Comparison’), LB-TFC is simulated, analyzed and compared for two freeways (one synthetic network and one stretch of the ring-road freeway SE-30 in Seville, Spain). [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]

Copyright of Railway Signalling & Communication Engineering is the property of Railway Signalling & Communication Engineering and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

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

Copyright of Railway Signalling & Communication Engineering is the property of Railway Signalling & Communication Engineering and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

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]

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]

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]

In this paper, we consider the impact of cyber attacks on voltage regulation in distribution systems when a number of photovoltaic (PV) systems are connected. We employ a centralized control scheme that utilizes voltage measurements from sectionizing switches equipped with sensors. It is demonstrated that if measurements are falsified by an attacker, voltage violation can occur in the system. However, by equipping the control with a detection algorithm, we verify that the damage can be limited especially when the number of attacked sensors is small through theoretical analysis and simulation case studies. In addition, studies are made on attacks which attempt to reduce the output power at PV systems equipped with overvoltage protection functions. Further discussion is provided on how to enhance the security level of the proposed algorithm. [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]

Airports are the most resource-constrained components of the air transportation system. This paper addresses the problems of increased flight delays and aircraft fuel consumption through the integrated control of airport arrival and departure operations. Departure operations are modeled using a network abstraction of the airport surface. Published arrival routes to airports are synthesized to form a realistic model of arrival airspace. The proposed control framework calculates the optimal times of departure of aircraft from the gates, as a function of the arrival and departure traffic as well as airport characteristics such as taxiway layout and gate capacity. The integrated control formulation is solved using dynamic programming, which allows calculation of policies for real-time implementation. The advantages of the proposed methodology are illustrated using simulations of Boston’s Logan International Airport. [ABSTRACT FROM PUBLISHER]

In Wi-Fi HaLow networks, sensors can transmit data only after the link set-up procedure (LSP). After a power outage or when a swarm of sensors appears in an Internet of Things network, all of them contend for the channel to set up links with the access point. For thousands of sensors the LSP can last for hours. However, it can be shortened with advanced LSP coordination algorithms. We show that the best standard-compatible solution found in the literature leaves a gap between the achievable link set-up time and the estimated lower bound. In this paper, we design and evaluate an adaptive solution to control the LSP that fills in this room for improvement and provides significant gains against the existing algorithms. [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]

In small microgrids and individual branches of a bulk electrical grid, the aggregate electrical load can contain significant and frequent peaks caused by large individual loads. These peaks can reduce overall system efficiencies if generation resources, e.g., diesel generators, are dispatched based on peak demand. This problem is particularly severe in military forward operating base (FOB) microgrids, in which the load profile is dominated by environmental control units (ECUs) that operate under thermostatic control. Leveraging the intrinsic energy storage capabilities associated with large loads such as these ECUs and coordinating their operations across neighboring facilities provides an opportunity to reduce peak demand while maintaining system performance. Using a military FOB microgrid as a use case, this paper presents two direct load control (DLC) algorithms for coordinating ECU operations and reducing peak demand. This coordinated control is demonstrated through simulations and field tests at the U.S. Army’s Base Camp Integration Laboratory using novel controller hardware. Both simulation and field tests indicate that the DLC algorithms can reduce peak loads by 25% or more without sacrificing thermal comfort. [ABSTRACT FROM AUTHOR]

This paper proposes a new load current sharing control strategy for dc microgrid (MG). It adopts the piecewise linear formation to adaptively assign droop gains to balance the load sharing accuracy with the deviation of bus voltage. Communication among the distributed units is unnecessary for the proposed operation. The approach is considered as a comprehensive solution to deal with the unbalanced performance in dc MG for different load levels. The balancing performance is shown by comparing with the traditional linear droop control and the latest nonlinear droop gain solution. The study is proceeded by the in-depth analysis of both steady state and system dynamics with simulation support. The claimed advantage is finally verified by both simulation and experimental evaluations. [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]

For a hybrid ac/dc microgrid (MG), bidirectional interlinking converters (BICs) enable flexible power interactions between ac and dc subgrids. In each subgrid, power sharing among diversified sources has been effectively realized by droop controllers. These power sharing concepts can also be extended to BIC applications. This paper proposes a distributed power management strategy (DPMS) for multi-paralleled BICs in the hybrid MG to avoid the overstress of a single BIC. In this strategy, each BIC is assigned with a well-devised localized distributed controller (LDC) which generates the respective power reference for the BIC. By using the LDC, BICs are allowed to exchange information with one another in the distributed communication graph. The power interactions between ac and dc subgrids can be proportionally allocated to BICs based on their different power ratings in a full distributed manner. Then the system reliability and scalability are significantly improved. Meanwhile, accurate global power sharing among all ac and dc sources in the MG would be accordingly attained. Considering the communication time delay involved in BICs, a small signal model is derived to predict the maximum tolerable delay of the studied system. The validities of the proposed DPMS and delay stability analyses are verified by a controller hardware-in-loop experimental platform. [ABSTRACT FROM AUTHOR]

On-line vehicle dispatching rules are widely used in many facilities such as warehouses and manufacturing facilities to control vehicles' movements. Single-attribute dispatching rules, which dispatch vehicles based on only one parameter, are usually used. However, multi-attribute dispatching rules prove to be better in general. In this paper, we study the impact of reassigning moving vehicles on some good dispatching rules, both single- and multi-attribute, in the literature. Results suggest that reassigning moving-to-park vehicles has a significant positive effect on reducing the average load waiting time. We evaluate the dispatching rules' performance using the experimental design of a real-life case study. The performance criteria are: minimizing the average load waiting time, keeping the maximum load waiting time as short as possible and utilizing better vehicles. The results show that the combined dispatching rules which integrates multi-attribute dispatching and vehicle reassignment yields the best performance overall. [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 focuses on the decentralized optimal control algorithm for distribution management system by considering distribution network as coupled microgrids. Based on the autonomous control model of each single microgrid, coordinated information and strategies among different microgrids are used to decrease the operating cost of distributed generation, improve the efficiency of the distributed storages utilization, and reduce the complexity of distribution network operation. The optimal control problem of microgrids is modeled as a decentralized partially-observable Markov decision process (DEC-POMDP), and a coordinated dynamic programming algorithm is used to solve the problem by introducing a look-head dual multiplier mechanism as decentralized control signals from centralized information. The performances of this algorithm and the impacts of different coordinated information are discussed by some study cases in the end of this paper. [ABSTRACT FROM PUBLISHER]

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]

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]

In this paper, a centralized control strategy for low-voltage networks is proposed, aiming to coordinate the droop characteristics of the distributed renewable energy sources. The main objectives are the overvoltage mitigation and the optimal network operation in terms of maximum power injection and uniform power curtailment. The distinct features of the proposed method are the incorporation of droop-based control techniques into the conventional optimal power flow formulation and the use of the sensitivity theory as a means to significantly decrease the computational burden. The validity of the developed method is justified using a genetic algorithm, while extensive comparisons with conventional centralized and decentralized control strategies indicate its superior performance in the operation of low-voltage networks. [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]

This paper proposes a distributed algorithm for coordination of flywheel energy storage matrix system (FESMS) cooperated with wind farm. A simple and distributed ratio consensus algorithm is proposed to solve FESMS dispatch problem. The algorithm is based on average consensus for both undirected and unbalanced directed graphs. Average consensus is guaranteed in unbalanced digraphs by updating the weight matrix with both its row sums and column sums being 1. Simulation examples illustrate the effectiveness of the proposed control method. [ABSTRACT FROM PUBLISHER]