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Showing papers on "Control reconfiguration published in 2016"


Journal ArticleDOI
TL;DR: This brief investigates the finite-time control problem associated with attitude stabilization of a rigid spacecraft subject to external disturbance, actuator faults, and input saturation and develops a novel fixed-time sliding mode surface, and the settling time of the defined surface is shown to be independent of the initial conditions of the system.
Abstract: This brief investigates the finite-time control problem associated with attitude stabilization of a rigid spacecraft subject to external disturbance, actuator faults, and input saturation. More specifically, a novel fixed-time sliding mode surface is developed, and the settling time of the defined surface is shown to be independent of the initial conditions of the system. Then, a finite-time controller is derived to guarantee that the closed-loop system is stable in the sense of the fixed-time concept. The actuator-magnitude constraints are rigorously enforced and the attitude of the rigid spacecraft converges to the equilibrium in a finite time even in the presence of external disturbances and actuator faults. Numerical simulations illustrate the spacecraft performance obtained using the proposed controller.

361 citations


Journal ArticleDOI
TL;DR: A reconfiguration scheme, based on higher order sliding mode (HOSM) observer, is proposed in the event of sensor faults/failures to maintain a good control performance and is presented to demonstrate the validity of the proposed fault-detection scheme.
Abstract: This paper investigates the problem of automatic speed tracking control of an electric vehicle (EV) that is powered by a permanent-magnet synchronous motor (PMSM). A reconfiguration scheme, based on higher order sliding mode (HOSM) observer, is proposed in the event of sensor faults/failures to maintain a good control performance. The corresponding controlled motor output torque drives EVs to track the desired vehicle reference speed for providing uninterrupted vehicle safe operation. The effectiveness of the overall sensor fault-tolerant speed tracking control is highlighted when an EV is subjected to disturbances like aerodynamic load force and road roughness using high-fidelity software package CarSim. Experiments with a 26-W, three-phase PMSM are presented to demonstrate the validity of the proposed fault-detection scheme.

315 citations


Journal ArticleDOI
Binbin Li1, Shaolei Shi1, Bo Wang1, Gaolin Wang1, Wei Wang1, Dianguo Xu1 
TL;DR: In this article, a fault diagnosis and tolerant control solution, including the fault detection, fault tolerance, fault localization, and fault reconfiguration, have been proposed to ride through the insulated gate bipolar transistor open-circuit failures.
Abstract: The modular multilevel converter (MMC) is distinguished by its modularity that is the use of standardized submodules (SMs). To enhance reliability and avoid unscheduled maintenance, it is desired that an MMC can remain operational without having to shut down despite some of its SMs are failed. Particularly, in this paper, complete fault diagnosis and tolerant control solution, including the fault detection, fault tolerance, fault localization, and fault reconfiguration, have been proposed to ride through the insulated gate bipolar transistor open-circuit failures. The fault detection method detects the fault by means of state observers and the knowledge of fault behaviors of MMC, without using any additional sensors. Then, the MMC is controlled in a newly proposed tolerant mode until the specific faulty SM is located by the fault localization method; thus, no overcurrent problems will happen during this time interval. After that, the located faulty SM will be bypassed while the remaining SMs are reconfigured to provide continuous operation. Throughout the fault periods, it allows the MMC to operate smoothly without obvious waveform distortion and power interruption. Finally, experimental results using a single-phase scaled-down MMC prototype with six SMs per arm show the validity and feasibility of the proposed methods.

241 citations


Journal ArticleDOI
TL;DR: The proposed integrated design approach using FE and fault compensation within the control system in which the design is achieved by integrating together the FE and FTC controller modules is illustrated through studying the control of an uncertain model of a DC motor.

237 citations


Journal ArticleDOI
TL;DR: In this article, a meta-heuristic cuckoo search algorithm (CSA) inspired from the obligate brood parasitism of some Cuckoo species which lay their eggs in the nests of other birds of other species for solving optimization problems is adapted to simultaneously reconfigure and identify the optimal location and size of DG units in a distribution network.

214 citations


Journal ArticleDOI
TL;DR: In this paper, a mathematical model is devised to minimize daily network losses via applying hourly reconfigurations, which is a mixed integer second-order cone programming problem and is solved via MOSEK solver.
Abstract: Proliferation of renewable energy resources in distribution networks has captured distribution companies' attention towards more active management tools. Thanks to the smart grid paradigm, hourly network reconfiguration, which is still among immature ideas, can bring the activeness required to handle fluctuating output of renewable resources. The aim of this study is to analyze the worthiness of the hourly reconfiguration in the presence of renewable energy resources. For doing so, a mathematical model is devised to minimize daily network losses via applying hourly reconfigurations. The model is a mixed integer second-order cone programming problem and is solved via MOSEK solver. The electrical demand variations as well as renewable power generation fluctuations during a day are taken into account. The proposed method is applied to the Baran 33-bus system and the results including a great deal of sensitivity analyses on key parameters are presented and discussed.

206 citations


Journal ArticleDOI
Zhiqiang Pei1, Yang Yang1, Qiaomei Chen1, Yen Wei1, Yan Ji1 
TL;DR: Hot-pressing shape memory vitrimers lead to multishape memory, multifunctionality, easy reconfiguration, and the possibility of mass production of arbitrary smart structures.
Abstract: Hot-pressing shape memory vitrimers lead to multishape memory, multifunctionality, easy reconfiguration, and the possibility of mass production of arbitrary smart structures.

199 citations


Proceedings ArticleDOI
12 Mar 2016
TL;DR: Heterogeneous Reconfigurable Logic (HRL), a reconfigurable array for NDP systems that improves on both FPGA and CGRA arrays, and achieves 92% of the peak performance of an NDP system based on custom accelerators for each application.
Abstract: The energy constraints due to the end of Dennard scaling, the popularity of in-memory analytics, and the advances in 3D integration technology have led to renewed interest in near-data processing (NDP) architectures that move processing closer to main memory. Due to the limited power and area budgets of the logic layer, the NDP compute units should be area and energy efficient while providing sufficient compute capability to match the high bandwidth of vertical memory channels. They should also be flexible to accommodate a wide range of applications. Towards this goal, NDP units based on fine-grained (FPGA) and coarse-grained (CGRA) reconfigurable logic have been proposed as a compromise between the efficiency of custom engines and the flexibility of programmable cores. Unfortunately, FPGAs incur significant area overheads for bit-level reconfiguration, while CGRAs consume significant power in the interconnect and are inefficient for irregular data layouts and control flows. This paper presents Heterogeneous Reconfigurable Logic (HRL), a reconfigurable array for NDP systems that improves on both FPGA and CGRA arrays. HRL combines both coarse-grained and fine-grained logic blocks, separates routing networks for data and control signals, and uses specialized units to effectively support branch operations and irregular data layouts in analytics workloads. HRL has the power efficiency of FPGA and the area efficiency of CGRA. It improves performance per Watt by 2.2x over FPGA and 1.7x over CGRA. For NDP systems running MapReduce, graph processing, and deep neural networks, HRL achieves 92% of the peak performance of an NDP system based on custom accelerators for each application.

184 citations


Journal ArticleDOI
TL;DR: It is shown that the stability and tracking performances of the closed-loop system can be achieved even in the presence of unknown non linear faults, and the FTC scheme can handle the nonaffine nonlinear faults effectively.
Abstract: This paper studies the fuzzy adaptive output feedback fault-tolerant control (FTC) problem for a class of single-input and single-output uncertain nonlinear systems with time-varying nonaffine nonlinear faults in strict-feedback form. In the design procedure, filtered signals are adopted to circumvent algebraic loop problems on implementing the usual controllers. By using fuzzy logic systems to approximate the unknown nonlinearity effects and changes in model dynamics due to faults, a fuzzy state observer is first presented to estimate the unmeasured states. Based on the online estimating information from the adaptive mechanism, an observer-based dynamic output feedback fault-tolerant controller is designed via the backstepping technique. It is shown that the stability and tracking performances of the closed-loop system can be achieved even in the presence of unknown nonlinear faults. In comparison with the existing approaches, the FTC scheme can handle the nonaffine nonlinear faults effectively. Finally, a simulation example is included to validate the advantages of the proposed approaches.

160 citations


Journal ArticleDOI
TL;DR: This paper investigates fault-tolerant operations of an open-end five-phase drive, i.e., a multiphase machine fed with a dual-inverter supply, and considers and handles inverter switch short-circuit fault.
Abstract: Multiphase machines are well known for their fault-tolerant capability. Star-connected multiphase machines have fault tolerance in an open circuit. For an inverter switch short-circuit fault, it is possible to keep a smooth torque of a permanent magnet synchronous machine if the currents of the faulty phases are determined and their values are acceptable. This paper investigates fault-tolerant operations of an open-end five-phase drive, i.e., a multiphase machine fed with a dual-inverter supply. Inverter switch short-circuit fault is considered and handled with a simple solution. Original theoretical developments are presented. Simulation and experimental results validate the proposed strategy.

158 citations


Journal ArticleDOI
15 May 2016-Energy
TL;DR: In this paper, a multi-objective framework is proposed for simultaneous network reconfiguration and power allocation of DGs (Distributed Generations) in distribution networks, where the uncertainty of loads is modeled using the TFN (Triangular Fuzzy Number) technique.

Journal ArticleDOI
TL;DR: A dynamic reconfiguration technique for real-time scheduling of real- time systems running on uni-processors that provides an increased number of safe execution sequences as compared with the earliest-deadline-first (EDF) scheduling algorithm.
Abstract: Based on the supervisory control theory (SCT) of timed discrete-event systems (TDES), this study presents a dynamic reconfiguration technique for real-time scheduling of real-time systems running on uni-processors. A new formalism is developed to assign periodic tasks with multiple-periods. By implementing SCT, a real-time system (RTS) is dynamically reconfigured when its initial safe execution sequence set is empty. During the reconfiguration process, based on the multiple-periods, the supervisor proposes different safe execution sequences. Two real-world examples illustrate that the presented approach provides an increased number of safe execution sequences as compared with the earliest-deadline-first (EDF) scheduling algorithm.

Journal ArticleDOI
TL;DR: In this paper, a heuristic method based on "uniform voltage distribution based constructive reconfiguration algorithm" (UVDA) is proposed for the simultaneous reconfigureuration and DG siting and sizing.

Journal ArticleDOI
TL;DR: This paper deals with Reconfigurable Cable-Driven Parallel Robots (RCDPRs) whose cable connection points on the base frame can be positioned at a possibly large but discrete set of possible locations.

Journal ArticleDOI
TL;DR: An adaptive fast terminal sliding mode control control law (AFTSMCL) is presented to resolve attitude tracking control problem for rigid spacecraft, which can provide finite-time convergence, strong robustness, and fault-tolerant control.
Abstract: In this paper, an adaptive fast terminal sliding mode control control law (AFTSMCL) is presented to resolve attitude tracking control problem for rigid spacecraft, which can provide finite-time convergence, strong robustness, and fault-tolerant control. Rigorous proof is achieved first. Simulation results are presented to illustrate the effectiveness of presented control law.

Journal ArticleDOI
TL;DR: The results of simulations in CarSim and vehicle experimental tests show the effectiveness of the proposed active fault-tolerant control system in dealing with certain IWM faults.
Abstract: An active fault-tolerant control (AFTC) system is proposed in this paper for electric vehicles with independently driven in-wheel motors (IWMs). It comprises a baseline controller, a set of reconfigurable controllers, a fault detection and diagnosis (FDD) mechanism, and a decision mechanism. The baseline controller, which is actually a passive fault-tolerant controller, is applied to accommodate actuator faults and stabilize the faulty vehicle when the actuator fault occurs. After the fault is detected and estimated by the FDD mechanism, a proper reconfigurable controller is switched ON to achieve optimal postfault performance. Taking advantage of the robust gain-scheduling algorithm, the loss-of-effectiveness and additive faults of the IWMs can be accommodated by the baseline controller, and the estimation error of the FDD mechanism can be tolerated by the reconfigurable controllers. The results of simulations in CarSim and vehicle experimental tests show the effectiveness of this AFTC system in dealing with certain IWM faults.

Journal ArticleDOI
TL;DR: A new stochastic framework based on cloud theory to account the uncertainties associated with multiobjective DFR problem from the reliability point of view is proposed and a new optimization algorithm designated as θ-bat algorithm is proposed in this paper.
Abstract: Distribution feeder reconfiguration (DFR) is a precious operation strategy that can improve the system from different aspects including total cost, reliability, and power quality. Nevertheless, the high complexity of the new smart grids has resulted in much uncertainty in the DFR problem that necessities the use of a sufficient stochastic framework to deal with them. In this way, this paper proposes a new stochastic framework based on cloud theory to account the uncertainties associated with multiobjective DFR problem from the reliability point of view. Cloud theory is constructed based on fuzzy theory and probability idea. In comparison with the Monte Carlo simulation method, cloud models can give more information on the uncertainties associated with the problem. This special aspect of cloud models makes it possible to integrate the fuzziness and randomness of qualitative concepts through the cloud drops and then transforms them to the quantitative model. In order to solve the proposed problem, a fast and powerful optimization technique is required. To deal with this issue, a new optimization algorithm designated as ${\theta }$ -bat algorithm is proposed in this paper. The feasibility and satisfying performance of the proposed method are examined on the 32-bus and 69-bus IEEE distribution test system.

Journal ArticleDOI
TL;DR: The proposed solution is flexible, dynamic, has a high semantic content and considers both virtual product models as well as feedback data from the physical product along its whole lifecycle (digital product twin).

Journal ArticleDOI
TL;DR: In this article, a robust optimization model is proposed for determining the minimum loss network configuration of a distribution system with uncertain load and renewable generation, where the optimal decisions on network configurations and losses are derived in two subsequent steps.
Abstract: Increasing penetration of variable loads and renewable generation will cause the conventional operation strategy of the distribution system to become less certain and effective. This paper presents a method of determining the minimum loss network configuration of a distribution system with uncertain load and renewable generation. A robust optimization model is proposed wherein the optimal decisions on network configurations and losses are derived in two subsequent steps. The first step enforces the radiality constraint before knowing the actual system loads and output level of renewable generation. Power flows are computed next to achieve minimum network losses considering the worst operating conditions over the uncertainty sets. A mixed-integer two-stage robust optimization formulation and a decomposition algorithm in a master-slave structure are proposed to solve the problem. Results of an illustrative example and two test systems are presented to demonstrate the proposed method.

Journal ArticleDOI
TL;DR: Numerical simulations validate the feasibility of reconfigurable spacecraft attitude takeover control with large center of mass shifts and unknown inertia properties and a modified adaptive dynamic inverse controller is proposed to provide global asymptotic stability in the presence of model uncertainties and nonlinearities.
Abstract: Most current research on reconfigurable control system puts emphasis on reconfiguration for adapting to actuator failures. However, the reconfigurable control system is necessitated for spacecraft attitude takeover control in the application of capturing target spacecraft whose fuel is exhausted to extend its operational lifetime by supplying them propulsion, navigation and guidance services. In this scenario, the capture of target spacecraft by space manipulators will cause a large shift in the dynamics of the service spacecraft. Not only do the mass properties change, but also does the thruster configuration. The changes in the mass, center of mass and inertia of the combined spacecraft will cause changes in the equivalent force exerted by each thruster. In this paper, considering the changes of thruster configuration and the control reallocation, a reconfigurable control system is designed for spacecraft attitude takeover control in post-capture of target by space manipulators in order to adapt to changes in the mass properties. The unknown inertia properties of target spacecraft in the system constitute a formidable technical challenge for controller design. Therefore, a modified adaptive dynamic inverse controller is proposed to provide global asymptotic stability in the presence of model uncertainties and nonlinearities. Moreover, by the null-space intersections control reallocation method, the thrust forces of service spacecraft can be redistributed and satisfy some constraints. Numerical simulations validate the feasibility of reconfigurable spacecraft attitude takeover control with large center of mass shifts and unknown inertia properties.

Journal ArticleDOI
TL;DR: The proposed hybrid optimization algorithm combines the concept of fuzzy Pareto dominance with shuffled frog leaping algorithm (SFLA) to recognize optimal nondominated solutions identified by SFLA and significantly increases the convergence speed of the algorithm.
Abstract: With ever increasing deployment of automation and communication systems in smart grids, distribution network reconfiguration is becoming a viable solution for improving the operation of power grids. A novel hybrid optimization algorithm is proposed in this paper that determines Pareto frontiers, as the candidate solutions, for multiobjective distribution network reconfiguration problem. The proposed hybrid optimization algorithm combines the concept of fuzzy Pareto dominance with shuffled frog leaping algorithm (SFLA) to recognize optimal nondominated solutions identified by SFLA. The local search step of SFLA is also customized for power systems application so that it automatically creates and analyzes only the feasible and radial configurations in its optimization procedure, which significantly increases the convergence speed of the algorithm. Moreover, an adaptive reliability-based frog encoding is introduced that supervises the algorithm to concentrate on more reliable network topologies. The performance of the proposed method is demonstrated on a 136-bus electricity distribution network.

Journal ArticleDOI
TL;DR: In this paper, the authors proposed a new formulation for the optimum reconfiguration of islanded microgrid (IMG) systems, in order to minimize the IMG fuel consumption in the operational planning horizon for which islanded operation is planned.
Abstract: This paper proposes a new formulation for the optimum reconfiguration of islanded microgrid (IMG) systems. The reconfiguration problem is casted as a multi-objective optimization problem, in order to: 1) minimize the IMG fuel consumption in the operational planning horizon for which islanded operation is planned; 2) ensure the IMG capability to feed the maximum possible demand by enhancing its voltage instability proximity index taken over all the states at which the islanded system may reside; and 3) minimize the relevant switching operation costs. The proposed problem formulation takes into consideration the system's operational constraints in all operating conditions based on the consideration of the uncertainty associated with renewable resources output power and load variability. Moreover, the proposed formulation accounts for droop controlled IMG special operational characteristics as well as the availability/unavailability of a supervisory microgrid central controller (MGCC). The formulated problem is solved using non-dominated sorting genetic algorithm II (NSGA-II). MATLAB environment has been used to test and validate the proposed problem formulation. The results show that the implementation of appropriate IMG reconfiguration problem formulations will enhance the performance of IMG systems and facilitate a successful integration of the microgrid concept in distribution networks.

Journal ArticleDOI
TL;DR: It is demonstrated that the line losses can be taken into account during the calculation of DT, and the line loss reduction can be realized in a decentralized manner through the DT framework.
Abstract: This paper presents an optimal reconfiguration-based dynamic tariff (DT) method for congestion management and line loss reduction in distribution networks with high penetration of electric vehicles. In the proposed DT concept, feeder reconfiguration (FR) is employed through mixed integer programming when calculating the DT, leading to minimized energy cost and reduced DT as compared with the DT concept without FR. This paper further demonstrates that the line losses can be taken into account during the calculation of DT. As a result, the line loss reduction can be realized in a decentralized manner through the DT framework. Three case studies were conducted to validate the optimal reconfiguration-based DT method for congestion management and line loss reduction in distribution networks.

Journal ArticleDOI
TL;DR: In this article, a mixed-integer second-order conic programming (MISOCP) model is proposed to solve the reconfiguration problem of electrical distribution systems, considering the simultaneous minimization of total active power losses and improvement of customer-oriented reliability indices.

Journal ArticleDOI
TL;DR: This paper proposes a reference framework for network reconfiguration and presents a short survey of some of the most relevant state-of-the-art works in this field, showing how they can be reformulated in this framework.
Abstract: There is a clear trend in camera networks toward enhanced functionality and flexibility, and a fixed static deployment is typically not sufficient to fulfill these increased requirements. Dynamic network reconfiguration helps to optimize the network performance to the currently required specific tasks while considering the available resources. Although several reconfiguration methods have been recently proposed, e.g., for maximizing the global scene coverage or maximizing the image quality of specific targets, there is a lack of a general framework highlighting the key components shared by all these systems. In this paper, we propose a reference framework for network reconfiguration and present a short survey of some of the most relevant state-of-the-art works in this field, showing how they can be reformulated in our framework. Finally, we discuss the main open research challenges in camera network reconfiguration.

Journal ArticleDOI
TL;DR: In this paper, a bidirectional, nonisolated dc-dc converter with several interleaved phases of multilevel modules for dual lowvoltage automotive power systems is presented.
Abstract: In this paper, a bidirectional, nonisolated dc–dc converter with several interleaved phases of multilevel modules for dual low-voltage automotive power systems is presented. Instead of using a two-level stage with short-circuit protection elements, a three-level module in a multiphase structure is proposed to achieve improved fault-tolerance. The dimensioning of the required flying capacitor for multilevel dc–dc converters is described. Further, benefits such as ripple reduction, automatic fault current limitation, and enhanced efficiency are achieved. Moreover, the control strategy for normal operation including the stability of the flying capacitor voltage as well as reconfiguration after semiconductor open- and short-circuit failure for ongoing degraded operation are explained.

Journal ArticleDOI
TL;DR: In this paper, a multi-objective evolutionary algorithm method for distribution feeder reconfiguration with distributed generators (DG) in a practical system is proposed, considering the low inertia constant of DG units in order to take the transient stability of DGs into account.

Journal ArticleDOI
TL;DR: In this paper, the three-phase bus locations and sizes of DG units are determined using sensitivity analysis and nonlinear programming, respectively, and distribution feeders are reconfigured every hour based on the status of time-varying loads, output power from DG units and faults on the network while minimizing the energy loss costs and DG operating costs.
Abstract: Most existing approaches for distribution network reconfiguration assume that the distribution system is (three-phase) balanced and a single-phase equivalent is used. However, distribution feeders are usually unbalanced due to a large number of single-phase loads, nonsymmetrical conductor spacing, and three-phase line topology. This paper builds on our previous work and studies feeder reconfiguration for unbalanced distribution systems with distributed generation (DG). The three-phase bus locations and sizes of DG units are determined using sensitivity analysis and nonlinear programming, respectively, and distribution feeders are reconfigured every hour based on the status of time-varying loads, output power from DG units and faults on the network while minimizing the energy loss costs and DG operating costs. Simulation results show the effectiveness and computational efficiency of the proposed approach.

Journal ArticleDOI
TL;DR: Numerical results show that the proposed methodology is an efficient method for comprehensive cost minimization in distribution systems with distributed generators.
Abstract: In this paper, an efficient methodology is proposed to deal with segmented-time reconfiguration problem of distribution networks coupled with segmented-time reactive power control of distributed generators. The target is to find the optimal dispatching schedule of all controllable switches and distributed generators' reactive powers in order to minimize comprehensive cost. Corresponding constraints, including voltage profile, maximum allowable daily switching operation numbers (MADSON), reactive power limits, and so on, are considered. The strategy of grouping branches is used to simplify the formulated mathematical problem and a hybrid particle swarm optimization (HPSO) method is presented to search the optimal solution. Fuzzy adaptive inference is integrated into basic HPSO method in order to avoid being trapped in local optima. The proposed fuzzy adaptive inference-based hybrid PSO algorithm (FAHPSO) is implemented in VC++ 6.0 program language. A modified version of the typical 70-node distribution network and several real distribution networks are used to test the performance of the proposed method. Numerical results show that the proposed methodology is an efficient method for comprehensive cost minimization in distribution systems with distributed generators.

Journal ArticleDOI
TL;DR: In this paper, a non-dominated Sorting Genetic Algorithm is used to solve the problem of DG allocation and sizing simultaneously to find an optimal condition for distribution network based on operational thresholds and reliability improvements.
Abstract: Optimal performance of power distribution networks greatly depends on network configuration, location and size of distributed generations (DGs) units and storage systems. That is, for different configurations, different optimal locations and sizes of DGs can be found and vice versa. Therefore, the impact of both location and size of DG and network configuration should be considered in the planning process, simultaneously. Also, the presence of storage systems in the distribution system leads to some loads to be supplied even in fault conditions. In this study, distribution system reconfiguration (DSR), for considering network configuration effect that runs in offline mode with constant loads, and optimal DG allocation and sizing problems are studied simultaneously to find an optimal condition for distribution network based on operational thresholds and reliability improvements. Non-dominated Sorting Genetic Algorithm is used to solve these problems simultaneously. Power losses, energy not supplied (ENS) and the costs associated with DG are the objectives that are studied. The method of calculating ENS in DSR problem in the presence of DGs with storage systems is explained and the impact of protective equipment is considered, as well. The proposed approach is applied on different test systems, and its effectiveness is shown in various conditions.