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The Journal of Engineering 2018年第13期2017卷 2438-2443页

作者： Yibin Liu Deliang Liang Qingshan Wang Qixu Chen Zhe Liang State Key Laboratory of Electrical Insulation and Power Equipment Xi'an Jiaotong University Xi'an People's Republic of China

Hybrid distribution transformer (HDT) has a powerful controllability, which is a quite significant device for the intelligentisation of the future distribution network. A practical circuit topology of HDT is proposed, and the mathematical model in static three-phase coordinates is established, and then the grid current and load voltage control systems are built with proportional–integral (PI) controllers; thus, the sinusoidal grid current, unity power factor and steady load voltage can be realised. To decrease the steady-state error, the compound control systems are established, for which the feed-forward of control-winding voltage, load current, convert-side winding current and grid voltage are added into the grid current and load voltage control system. A simple method for setting the PI controller parameters based on the frequency response of the closed-loop system and the bode diagram of the open-loop system is proposed. Finally, the simulation results show the effectiveness of the compound control system.

关键词： power factor PI control load regulation voltage control electric current control power transformers open-loop system bode diagram closed-loop system frequency response convert-side winding current control-winding voltage compound control systems steady load voltage unity power factor sinusoidal grid current PI controllers proportional-integral controllers load voltage control systems grid current control systems static three-phase coordinates mathematical model circuit topology distribution network HDT control system analysis hybrid distribution transformer

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On an Optimal Production-Inventory Plan for a Closed loop Supply Chain

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IFAC-PapersOnLine 2017年第1期50卷 4987-4993页

作者： Salviano O. Andres F. Center for Information Technology Renato Archer Brazil National Institute of Informatics101-8430 Japan

Middle and long-term inventory-production plans have deserved interest of managers of supply chains since the 80’s. However, from 90’s to now, to plan a reverse channel has been also an important business practice. This paper deals with such an issue. In this way, a chance constraint, stochastic quadratic problem subject to linear discrete-time inventory-production systems is formulated. The objective of this problem is to meet the demand for a single product, which can be manufactured from a forward channel and/or remanufactured (refurbished) from a backward channel. The demand fluctuation is a random variable, with mean and standard-deviation known over time. On the other hand, the return rate is assumed deterministic, but with some periods of delay over the planning horizon. The random nature of demand fluctuation affects the variability of serviceable inventory variable in the sense of its variance increases over periods of planning horizon. In order to mitigate such variability, a feedback gain, which relates remanufactured/refurbished rate to serviceable inventory level, is considered. This gain is obtained from a minimum variance problem. As a result, an optimal plan is developed from an equivalent Mean Value problem that has constraints regulated by the gain. Through a simple example, it will be shown that the open-loop optimal plan obtained with problem's constraints fixed by optimal gain has a better performance than the optimal plan provided without such a gain. © 2017

关键词： minimum variance open-loop system optimization reverse logistics supply chain

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On an Optimal Production-Inventory Plan for a Closed loop Supply Chain.

On an Optimal Production-Inventory Plan for a Closed Loop Su...

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20th World Congress of the International-Federation-of-Automatic-Control (IFAC)

作者： Salviano, Oscar Andres, Frederic Ctr Informat Technol Renato Archer Amarais Brazil Natl Inst Informat Tokyo 1018430 Japan

Middle and long-term inventory-production plans have deserved interest of managers of supply chains since the 80's. However, from 90's to now, to plan a reverse channel has been also an important business practice. This paper deals with such an issue. In this way, a chance constraint, stochastic quadratic problem subject to linear discrete-time inventory-production systems is formulated. The objective of this problem is to meet the demand for a single product, which can be manufactured from a forward channel and/or remanufactured (refurbished) from a backward channel. The demand fluctuation is a random variable, with mean and standard-deviation known over time. On the other hand, the return rate is assumed deterministic, but with some periods of delay over the planning horizon. The random nature of demand fluctuation affects the variability of serviceable inventory variable in the sense of its variance increases over periods of planning horizon. In order to mitigate such variability, a feedback gain, which relates remanufactured/refurbished rate to serviceable inventory level, is considered. This gain is obtained from a minimum variance problem. As a result, an optimal plan is developed from an equivalent Mean Value problem that has constraints regulated by the gain. Through a simple example, it will be shown that the open-loop optimal plan obtained with problem's constraints fixed by optimal gain has a better performance than the optimal plan provided without such a gain. (C) 2017, IFAC (International Federation of Automatic Control) Hosting by Elsevier Ltd. All rights reserved.

关键词： minimum variance open-loop system optimization supply chain reverse logistics

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Simplification of the zinc-sulfur-iodine thermochemical cycle for the production of H₂ and CO

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INTERNATIONAL JOURNAL OF HYDROGEN ENERGY 2016年第1期41卷 94-103页

作者： Zhang, Yanwei Nie, Tingting Qiu, Kunzan Zhou, Junhu Wang, Zhihua Liu, Jianzhong Cen, Kefa Zhejiang Univ State Key Lab Clean Energy Utilizat Hangzhou 310027 Peoples R China

In this paper, three simplification plans for the zinc-sulfur-iodine thermochemical cycle are designed, namely the open-loop system, the five-step cycle, and the electrochemical cycle. Parameters for each simplified cycle are presented. Thermal efficiency is regarded as the evaluation criterion of the whole system, and thermal balance for each cycle is investigated. Results show that the variation of thermal load for the whole system is the primary reason for changes in thermal efficiency. Thermal efficiency of the open-loop system is improved to 57% under proper operating conditions, and concentrated H2SO4 with a mass fraction of 92.5 wt% is output. As for the electrochemical cycle, its thermal efficiency almost keeps the same with the original one, since study on its critical factor, the electrochemical Bunsen reaction, is not enough. What's more, chemical processes of the five-step and electrochemical cycle are simplified drastically by comparing to the original one. (C) Copyright 2015, Hydrogen Energy Publications, LLC. Published by Elsevier Ltd. All rights reserved.

关键词： ZnSI thermochemical cycle open-loop system Five-step cycle Electrochemical Bunsen reaction Thermal efficiency

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Threshold models in time series analysis-Some reflections

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JOURNAL OF ECONOMETRICS 2015年第2期189卷 485-491页

作者： Tong, Howell Univ London London Sch Econ & Polit Sci London WC2A 2AE England

In this paper, I reflect on the developments of the threshold model in time series analysis since its birth in 1978, with particular reference to econometrics. (C) 2015 Elsevier B.V. All rights reserved.

关键词： All-step-ahead prediction Asymmetry Bayesian decision Business cycle Catastrophe Conditionally heteroscedastic autoregressive models with thresholds GARCH model Hidden Markov chain Hysteresis Jump resonance Markov switching model Mis-specified model Mixture of distributions Non-likelihood approach Nonlinear unit root Non-stationarity open-loop system Panel threshold model Positive-valued time series Smooth threshold autoregressive models Splines Stochastic volatility Structural breaks Threshold autoregressive models Threshold moving average models Threshold principle Threshold unit root Volatility Wrong model

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Nonlinear Controller Design and Stability Analysis under Power Management of Autonomous PV systems 22

Nonlinear Controller Design and Stability Analysis under Pow...

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22nd Mediterranean Conference on Control and Automation (MED)

作者： Krommydas, Konstantinos F. Alexandridis, Antonio T. Univ Patras Elect & Comp Engn Dept Rion 26500 Greece

ISBN: (纸本)9781479959013

A stable controller and power management design for an autonomous photovoltaic (PV) system that includes battery storage devices is proposed in this paper. Both the PV and the storage system are interfaced to a dc load, each via a dc/dc boost power electronic converter. To proceed with the system stability analysis, the complete nonlinear dynamic model of the composite system is developed by taking into account the PV source, battery and converters dynamics. It is shown that the open-loop system has the passivity property, which is preserved in the closed-loop form by suitably designing proportional-integral controllers for the duty-ratio inputs of the power converters. Based on this property, a new sequential method is developed that provides a Lyapunov function capable to prove input-to-state stability (ISS) for the closed-loop system. The ISS property is finally combined with an appropriate power management strategy to guarantee stable operation of the complete autonomous PV system. Simulation results under two different scenarios verify the theoretical analysis and the good performance of the system.

关键词： DC-DC power convertors Lyapunov methods PI control closed loop systems control system analysis nonlinear control systems photovoltaic power systems DC-DC boost power electronic converter ISS property Lyapunov function autonomous PV systems autonomous photovoltaic system closed-loop form input-to-state stability nonlinear controller design open-loop system power management proportional-integral controllers stability analysis Asymptotic stability Batteries Closed loop systems Stability analysis Vectors Voltage control

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Design and implementation of decoupled compensation for a twin rotor multiple-input and multiple-output system

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IET CONTROL THEORY AND APPLICATIONS 2013年第2期7卷 282-289页

作者： Pradhan, Jatin Kumar Ghosh, Arun IIT Bhubaneswar Sch Elect Sci Bhubaneswar 751013 Orissa India

This study achieves compensation of a physical twin rotor multiple-input and multiple-output system in two steps: (i) input-output decoupling its transfer function model, obtained by linearising its non-linear model around an operating point, using an open-loop, minimal precompensator and (ii) effecting 2-degree of freedom single-input and single-output (SISO) compensations for the resulting SISO-decoupled units. While step (i) ensures decoupling in the responses, the other performances (such as robustness, tracking, disturbance rejection, etc.) can be achieved using SISO compensations in step (ii) above. The performances of the compensated system in respect of decoupling, loop robustness and disturbance rejection are verified through simulations and experiments. The results are also compared with the existing ones.

关键词： compensation control system synthesis MIMO systems nonlinear control systems open loop systems transfer functions loop robustness disturbance rejection SISO-decoupled units single-input and single-output compensations 2-degree of freedom minimal precompensator open-loop system operating point nonlinear model transfer function model input-output decoupling twin rotor multiple-input and multiple-output system decoupled compensation

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Power Feasibility of a Low Power Consumption Solar Tracker

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Procedia Environmental Sciences 2013年 17卷 494-502页

作者： Salsabila Ahmad Suhaidi Shafie Mohd Zainal Abidin Ab Kadir Department of Electrical & Electronics Engineering Universiti Putra Malaysia 43400 Serdang Selangor Malaysia Department of Electrical System Engineering Universiti Malaysia Perlis 02600 Arau Perlis Malaysia Centre of Excellence for Renewable Energy Universiti Malaysia Perlis 01000 Kangar Perlis Malaysia Advanced Institute of Technology Universiti Putra Malaysia 43400 Serdang Selangor Malaysia

This paper discusses on the generated power and the power consumption of an open-loop time and date based sun positioning solar collector system under three weather conditions; sunny and clear day, cloudy day and heavy overcast and rainy day under Malaysian tropical climate at location E100°11’, N6°26’, The two-axes tracking system used a Programmable Logic Controller (PLC) to maneuver a photovoltaic solar module based on 10° altitude angle tracking and 1° azimuth angle tracking. The daily percentage of power consumed during a clear and sunny day from the tracking motors and controller is 0.05% and 5.84%, respectively. Overall, the system consumed 5.89% of the total generated power.

关键词： Dual-axes Solar tracking open-loop system

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Anti-Sway system for Ship-to-Shore Cranes

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STROJNISKI VESTNIK-JOURNAL OF MECHANICAL ENGINEERING 2012年第5期58卷 338-344页

作者： Raubar, Edvin Vrancic, Damir Jozef Stefan Inst Ljubljana Slovenia

All ship-to-shore cranes hoisting mechanisms are made of a load attached to the trolley by means of a hoisting rope. In the process of loading and unloading the ship, the trolley moves the load along the boom from ship to shore and vice versa. During movement, the hoisting mechanism structure causes swinging of the load around vertical position. Load swing increases the loading/unloading time and increases the probability of collisions with other objects, like a nearby container, an iron construction for disposal of material (e.g. bunker), etc. Swinging of the load cannot be avoided, but can be radically reduced by using appropriate anti-sway systems. The paper derives a non-linear and linearized dynamic model of the crane load based on parameters of Panamax ship-to-shore crane in the Port of Koper. The responses of three open-loop anti-sway systems are compared together on the aforementioned dynamic model. Simulation results show that all three systems reduce load swing significantly, but only the systems based on zero-vibration-derivative and zero-vibration-derivative-derivative methods completely satisfy the given requirements.

关键词： ship-to-shore crane load oscillation anti-sway system open-loop system

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An open-loop control system of three-phase AC motor based on DSP

An open-loop control system of three-phase AC motor based on...

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IEEE International Conference on Networking, Sensing and Control

作者： Zhou, Sanqi Jiang, Daming Li, Denghua Beijing Jiao Tong Univ Sch Elect & Informat Engn Beijing 100044 Peoples R China Beijing Informat Technol Inst Dept Informat & Telecommun Engn Beijing Peoples R China

ISBN: (纸本)9781424416851

The U/f-constant (Voltage/Frequency equals to constants) control strategy of three-phase AC motor was studied. SPWM (Sinusoidal Pulse Wave Modulation) algorithm was employed to design the open-loop speed control system of three-phase AC motor and implement through programming on DSP (Digital Signal Processor), TMS320F2812. The test results showed that the output signal of the control system is characteristic of sine wave with small harmonic wave, the rotor speed agreed well with the theoretical value. The purpose of precise speed control in the system can be achieved in range of 20-70Hz.

关键词： DSP U/f-constant control strategy SPWM open-loop system three-phase AC motor

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