This paper proposes a multi-input muti-output control strategy for dispatchable power electronic based distributed energy resources (DERs) in islanded mode operation of microgrids. The controller is ...designed based on the dq model of the DER unit. Cascade, feedforward, and internal model control principle, incorporating the theory of integral control and repetitive controller, are used. The proposed controller regulates the voltage at the output of DERs under any load (balanced, unbalanced, and harmonic) variation and/or fault condition. The stability of the closed-loop system has been investigated. Enhanced phase-locked loop (EPLL) is used to determine the system variables in the dq frame under unbalanced (and balanced) operating conditions. The structure of the EPLL is further modified to regulate the microgrid frequency and a stability analysis of proposed frequency control loop is presented. The performance of the proposed controller is verified through test case studies, carried out on an autonomous microgrid with single and multiple DER units.
This paper presents a conceptual design for a plant-wide autonomous operation system that uses artificial intelligence techniques. The autonomous operation system has the power and ability to perform ...the control functions needed for the emergency operation of a nuclear power plant (NPP) with reduced operator intervention. This paper discusses the emergency operation and level of automation in an NPP and presents the design requirements for an autonomous emergency operation system (A-EOS). Then, an architecture that consists of several modules is proposed, with descriptions of the functions. Finally, this paper introduces a prototype of the suggested autonomous system that integrates the authors’ previous works.
During intravascular interventional surgery, the 3D surgical navigation system can provide doctors with 3D spatial information of the vascular lumen, reducing the impact of missing dimension caused ...by digital subtraction angiography (DSA) guidance and further improving the success rate of surgeries. Nevertheless, this task often comes with the challenge of complex registration problems due to vessel deformation caused by respiratory motion and high requirements for the surgical environment because of the dependence on external electromagnetic sensors. This article proposes a novel 3D spatial predictive positioning navigation (SPPN) technique to predict the real-time tip position of surgical instruments. In the first stage, we propose a trajectory prediction algorithm integrated with instrumental morphological constraints to generate the initial trajectory. Then, a novel hybrid physical model is designed to estimate the trajectory's energy and mechanics. In the second stage, a point cloud clustering algorithm applies multi-information fusion to generate the maximum probability endpoint cloud. Then, an energy-weighted probability density function is introduced using statistical analysis to achieve the prediction of the 3D spatial location of instrument endpoints. Extensive experiments are conducted on 3D-printed human artery and vein models based on a high-precision electromagnetic tracking system. Experimental results demonstrate the outstanding performance of our method, reaching 98.2% of the achievement ratio and less than 3 mm of the average positioning accuracy. This work is the first 3D surgical navigation algorithm that entirely relies on vascular interventional robot sensors, effectively improving the accuracy of interventional surgery and making it more accessible for primary surgeons.
This paper delves into the application of vibration-based energy harvesting to power environmental sensor nodes, a critical component of modern data collection systems. These sensor nodes play a ...crucial role in structural health monitoring, providing essential data on external conditions that can affect the health and performance of structures. We investigate the feasibility and efficiency of utilizing piezoelectric vibration energy harvesters to sustainably power environmental wireless sensor nodes on the one hand. On the other hand, we exploit different approaches to minimize the sensor node's power consumption and maximize its efficiency. The investigations consider various sensor node platforms and assess their performance under different voltage levels and broadcast frequencies. The findings reveal that optimized harvester designs enable real-time data broadcasting with short intervals, ranging from 1 to 3 s, expanding the horizons of environmental monitoring, and show that in case the system includes a battery as a backup plan, the battery's lifetime can be extended up to 9 times. This work underscores the potential of vibration energy harvesting as a viable solution for powering sensor nodes, enhancing their autonomy, and reducing maintenance costs in remote and challenging environments. It opens doors to broader applications of sustainable energy sources in environmental monitoring and data collection systems.
Accurate control of long-range motion at the molecular scale holds great potential for the development of ground-breaking applications in energy storage and bionanotechnology. The past decade has ...seen tremendous development in this area, with a focus on the directional operation away from thermal equilibrium, giving rise to tailored man-made molecular motors. As light is a highly tunable, controllable, clean, and renewable source of energy, photochemical processes are appealing to activate molecular motors. Nonetheless, the successful operation of molecular motors fueled by light is a highly challenging task, which requires a judicious coupling of thermal and photoinduced reactions. In this paper, we focus on the key aspects of light-driven artificial molecular motors with the aid of recent examples. A critical assessment of the criteria for the design, operation, and technological potential of such systems is provided, along with a perspective view on future advances in this exciting research area.
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•A self-contained NMR spectrometer based on System-on-Chip.•Hardware tuning capabilities are implemented in the custom analog front-end.•NMR pulse sequence optimization using ...high-level programming on System-on-Chip.•Self-optimization for temperature compensation and automatic sample monitoring.
This paper describes the development of a portable and self-optimizing NMR spectrometer based on a miniaturized custom analog front-end and a System-on-Chip (SoC)-based digital back-end. The SoC integrates a field-programmable gate array (FPGA) fabric with a hard processor running a Linux operating system, thus enabling fully-autonomous operation without the need for an external computer. In the proposed approach, data captured by the FPGA fabric during regular operation is transported to the hard processor using an integrated on-chip bus for further processing. The processed results are then used to automatically estimate parameter values that optimize a suitable cost function, such as signal-to-noise ratio (SNR) per unit time. Finally, the optimized values of both electrical and NMR-related tuning parameters (e.g., preamplifier gain and frequency response, pulse length and amplitude, operating frequency, etc.) are programmed back into the front-end and back-end hardware. Experimental NMR results from various samples in a ∼0.1 T permanent magnet are presented to verify the operation of the proposed spectrometer. These demonstrate on-board Laplace inversion and automated frequency tuning to compensate for temperature changes. Preliminary 14N NQR results are also presented.
Blackstart of DFIG-based Windfarm Maina, Duncan Kaniaru; Sanjari, Mohammad Javad; Nair, Nirmal-Kumar C.
2019 IEEE Power & Energy Society General Meeting (PESGM),
2019-Aug.
Conference Proceeding
Increased penetration of DFIG-based windfarms demand their use not only in normal operating conditions but also in restorative conditions, if wind is forecasted to be available. This paper explores ...the possibility of starting DFIG-based windfarms in preparation of network restoration. Analysis of DFIG starting with the help of a diesel generator set is provided. The windfarm substation is assumed to be composed of a diesel gen-set, synchronous condenser and a dump load. Pitch control, different from the one used during high wind speeds, is modeled and incorporated in this scheme to control speed of rotor during switching on of RSC and stator resynchronisation to the grid. Results, from simulation in MATLAB/SIMULINK, show successful starting of DFIG windfarm by use of a standby diesel generator set. Also, the speed of rotor is controlled to achieve the required speed at any stage of the starting process.
•New configuration of a microgrid – introduction of new microgrid interface unit.•Sizing oriented control strategy – folded droop to limit the size of interface unit.•Decentralized cooperation – ...seamless transitions of a microgrid with multiple converters.•Improved reliability – all-local-measurement based operational strategy for an expanded microgrid.
A new control scheme is proposed for microgrids to enable seamless switching between islanded mode and grid-connected mode in this paper. Utilizing a specially designed interface unit as the interface device, a systematic control strategy is proposed to enable a smooth and autonomous transition from grid-connected to islanded and vice-versa. With the proposed scheme, the need for high-speed communication is eliminated despite of the change of operational mode. To make this happen, a folded droop scheme is proposed to enable autonomous frequency support for paralleled converters in the microgrid and a coordinating strategy is then proposed to enable autonomous re-synchronization with the main grid as well. The control scheme proposed are validated with a benchmark microgrid model of parallel- connected converters using MATLAB/SIMULINK. The results show that the proposed control can enable autonomous smooth transitions between modes with reduced power rating in the interface converter unit.
This study presents a novel water cycle algorithm (WCA)-based optimal control strategy with the purpose of obtaining an efficient operation of an autonomous microgrid. The proposed control strategy ...is based on the proportional–integral (PI) controllers, which are optimally designed by the WCA. The optimisation process depends on the simulation-based optimisation approach and the criteria of integral squared error are chosen as an objective function. The control scheme is applied to an autonomous, decentralised, operation of a microgrid with multiple electronically interfaced distributed generation units and their local loads. In the islanded mode, the proposed controller is used to control the voltages of the islanded system despite the microgrid load and topological variability and uncertainties. The frequency of the islanded system is dictated through the use of an internal oscillator. The effectiveness of the proposed controller is compared with that obtained using the genetic algorithm-based PI controller. The validity of the proposed control strategy is extensively checked based on simulation studies in the PSCAD/EMTDC environment under different operating conditions of the microgrid. With the application of the WCA-based optimal PI control scheme, the microgrid operation can be further enhanced.
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