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1.
The primary focus of this study is to investigate the control strategies of a hybrid system used in hydraulic excavators. First, the structure and evaluation target of hybrid hydraulic excavators are analyzed. Then the dynamic system model including batteries, motor and engine is built as the simulation environment to obtain control results. A so-called multi-work-point dynamic control strategy, which has both closed-loop speed PI （proportion integral） control and direct torque control, is proposed and studied in the simulation model. Simulation results indicate that the hybrid system with this strategy can meet the power demand and achieve better system stability and higher fuel efficiency. 相似文献
2.
CUI Yu-long LIU Hong WANG Jing-qin SUN Shu-guang 《浙江大学学报(A卷英文版)》2007,8(3):416-421
This paper first discusses the operating principle of instantaneous reactive power theory. Then, the theory is introduced into shunt active power filter and its control scheme is studied. Finally, Matlab/Simulink power system toolbox is used to simulate the system. In the simulation model, as the most common harmonic source, 3-phase thyristor bridge rectifier circuit is constructed. The simulation results before and after the shunt active filter was switched to the system corresponding to different firing angles of the thyristors are presented and analyzed, which demonstrate the practicability and reliability of the proposed shunt active filter scheme. 相似文献
3.
To implement structural hybrid simulation independent of the control system of any testing equipment in civil engineering, an external command control approach is put forward. Several setup technologies and the corresponding API approaches are investigated to simultaneously combine numerical simulation with physical testing. Hybrid program technology is put forward and described in detail, using Visual C++ program to effectively and accurately control testing equipment and MATLAB program to implement numerical simulation with easy extension. The control program of testing equipment and numerical simulation program are integrated by calling MATLAB engine in Visual C++. A hybrid simulation about a full-scale six-story masonry structure is carried out. The testing results manifest that the external command control approach has the versatility because of simple hardware connection and control program independent on control software of testing equipment; powerful program function of Visual C++ and flexible program of MATLAB are integrated by hybrid program technology; hybrid simulation system provides a realistic and cost-effective testing platform that enables earthquake engineer researchers to accurately and efficiently capture the seismic performance of large or complex structures without having to carry out physical testing of the entire structure. 相似文献
4.
This paper proposes an analysis and a direct power control （DPC） design of a wind turbine driven doubly-fed induction generator （DFIG） under unbalanced network voltage conditions. A DFIG model described in the positive and negative synchronous reference frames is presented. Variations of the stator output active and reactive powers are fully deduced in the presence of negative sequence supply voltage and rotor flux. An enhanced DPC scheme is proposed to eliminate stator active power oscillation during network unbalance. The proposed control scheme removes rotor current regulators and the decomposition processing of positive and negative sequence rotor currents. Simulation results using PSCAD/EMTDC are presented on a 2-MW DFIG wind power generation system to validate the feasibility of the proposed control scheme under balanced and unbalanced network conditions. 相似文献
5.
The growth and evolution of the knowledge network in supply chain can be characterized by dynamic growth clustering and non-homogeneous degree distribution.The networks with the above characteristics are also known as scale-free networks.In this paper,the knowledge network model in supply chain is established,in which the preferential attachment mechanism based on the node strength is adopted to simulate the growth and evolution of the network.The nodes in the network have a certain preference in the choice of a knowledge partner.On the basis of the network model,the robustness of the three network models based on different preferential attachment strategies is investigated.The robustness is also referred to as tolerances when the nodes are subjected to random destruction and malicious damage.The simulation results of this study show that the improved network has higher connectivity and stability. 相似文献
6.
An important feature of the traffic in mobile networks is burstiness. Drawbacks of conventional power control algorithms for time division duplex （TDD）-code division multiple access （CDMA） systems are analyzed. A joint power control algorithm based on service factor is presented to address the TDD-CDMA mobile services in the burst mode according to the Markov modulated Bernoulli process. The joint power control equation is derived. A function model is developed to verify the new algorithm and evaluate its performance. Simulation results show that the new power control algorithm can estimate interference strength more precisely, speed up convergence of power control, and enhance power efficiency and system capacity. It is shown that the proposed algorithm is more robust against link gain changes, and outperforms the reference algorithms. 相似文献
7.
Voltage source converter high-voltage direct current （VSC-HVDC） is a new power transmission technology pref- erable in small or medium power transmission. In this paper we discuss a new control system based on space vector modulation （SVM） without any voltage line sensors. Using direct power control （DPC） SVM and a new double synchronous reference frame phase-locked loop （DSRF-PLL） approach, the control system is resistant to the majority of line voltage disturbances. Also, the system response has accelerated by using a feed forward power decoupled loop. The operation of this control strategy was verified in a SIMULINK/MATLAB simulation environment. To validate this control system, a 5 kV.A prototype system was constructed. Compared to the original controllers, the current total harmonic distortion （THD）, the active and reactive deviations and the DC voltage overshoot were lowered by 2.5%, 6.2% and 8%, respectively. The rectifier power factor in the worst condition was 0.93 and the DC voltage settling time was 0.2 s. 相似文献
8.
A novel energy-regenerative active suspension (NEAS) system was designed to solve the problem of low energy recovery efficiency caused by frequent alternation of energy-recovery mode and active-control mode in a traditional energy-regenerative active suspension (TEAS) system. The energy recovery and active control could be implemented simultaneously in the NEAS. The transforming processes and the corresponding computational formulas of power conversion in the NEAS were provided. The simulation results show that the performances of energy recovery of the NEAS are improved, and the self-sustaining of power supply for the NEAS can be realized. 相似文献
9.
On maximum power point tracking control strategy for variable speed constant frequency wind power generation 总被引：1，自引：0，他引：1
WU Guo-qing NI Hong-jun WU Guo-xiang ZHOU Jing-ling Zhu Wei-nan MAO Jing-feng CAO Yang 《重庆大学学报(英文版)》2010,9(1):21-28
Based on the characteristic of AC-excited variable speed constant frequency （VSCF） wind power generation, the vector control technique was applied in a doubly fed induction generator （DFIG）. Maximum wind energy or maximum output power point can be tracked by decoupling control of active power and reactive power. The research result shows that the net power of generation system delivered to grid in maximum wind energy tracking mode is not the most. We presented a novel maximum power point tracking （MPPT） control strategy by analyzing the DFIG mathematic model and power relations which delivered the maximum power to the grid. The maximum power point could be tracked automatically without measuring wind speed in the control strategy and the control was independent of optimal turbine power curve, which had excellent dynamic and static performances and robustness. Simulation and experimental results testify the accuracy and validity of the control strategy. 相似文献
10.
This paper presents a control strategy of a hybrid fuel cell/battery distributed generation （HDG） system in distribution systems. The overall structure of the HDG system is given, dynamic models for the solid oxide fuel cell （SOFC） power plant, battery bank and its power electronic interfacing are briefly described, and controller design methodologies for the power conditioning units and fuel cell to control the power flow from the hybrid power plant to the utility grid are presented. To distribute the power between the fuel cell power plant and the battery energy storage, a neuro-fuzzy controller has been developed. Also, for controlling the active and reactive power independently in distribution systems, the current control strategy based on two fuzzy logic controllers has been presented. A Matlab/Simulink simulation model is developed for the HDG system by combining the individual component models and their controllers. Simulation results show the overall system performance including load-following and power management of the HDG system. 相似文献
11.
LIU Cheng-ze ZHU Xin-jian 《浙江大学学报(A卷英文版)》2006,7(11):1878-1885
INTRODUCTION Proton Exchange Membrane Fuel Cell (PEMFC) is being rapidly developed in recent years because of its compact structure, light weight, low working temperature and rapid startup characteristics. But its E-I characteristic curve reveals its decreasing per- formance when confronted with suddenly increasing power demand, and high cost also restrains the ap- plication of the fuel cell. So the hybrid power scheme is the most suitable selection presently. Most of researches on fu… 相似文献
12.
针对很多无线供电应用场合需要保持输出电压恒定的需求,提出了一种高频逆变器前动态调压的恒压输出控制方法。以LCL-S型感应耦合电能传输系统为研究对象,通过阻抗分析法建模,发现通过元器件的参数配置,可使系统输入阻抗为纯阻性,减少无功分量,同时逆变器开关管实现了零电流开通与关断,但此时系统输出电压并不恒定。针对分析结果提出基于模糊自适应PI控制算法的逆变前动态调压控制的恒压输出控制方案,最后搭建了仿真实验平台和实验样机证明了分析结果的正确和控制方案的有效。 相似文献
13.
杨建湘 《广西梧州师范高等专科学校学报》2014,(2):143-146
介绍了一种用于织物表面处理常压低温等离子体电源的工作原理及控制方法。根据纺织物表面处理工艺要求,高压电源采用前级PWM控制Buck电路DC／DC变换,后级H桥逆变经变压器升压结构产生稳定、均匀、柔和的低温等离子体。自动调节以计算机为控制单元,利用传感器技术实现自动控制,提高电源的可靠性。实际应用等离子体高频高压电源在纺织材料中的结果表明：该技术在提高了电源效率的同时,快速有效地抑制浪涌电压和峰值电流,改善了纺织材料表面处理的性能。 相似文献
14.
赖学江黄森炜廖洪毅曹智校陈清云 《福建工程学院学报》2021,(4):372-377
以深圳某办公楼为例,探讨冰蓄冷空调系统运行策略的优化。采用鸿业全年负荷计算及能耗分析软件(HY-EP)进行全年动态负荷模拟,对冷负荷的负荷率进行分析。在选定冰蓄冷系统后,基于模拟结果和地区的峰谷平电价的特点,采用了基于全年动态负荷结果分析预测和结合前一天的负荷作为当日的负荷预测,将全年逐日运行策略简化为4 种设备的运行方案,控制较为容易实现,且需要增加的初投资较少,是结合冰蓄冷系统与全年动态负荷模拟技术的创新应用。 相似文献
15.
GUO Chuang-xin ZHAO Bo 《浙江大学学报(A卷英文版)》2006,7(4):615-622
INTRODUCTION The reactive power dispatch is aimed at mini- mizing the active power loss in the transmission network by allocating the reactive power generation under several security constraints. The reactive power dispatch problem has significant influence on secure and economic operation of power systems. The reac- tive power generation affects the overall generation cost via transmission loss. A procedure which allo- cates the reactive power generation so as to minimize the transmissio… 相似文献
16.
基于MATCONT的电力系统电压稳定分岔及控制仿真试验 总被引：1，自引：0，他引：1
介绍了电力系统ODE模型中引起电压失稳的常见分岔类型及分岔控制的基本概念;运用基于Matlab的数值分岔分析软件MATCONT对一个经典单机—动态负荷系统进行了分岔分析,验证了PQ动态负荷模型系统存在着鞍结分岔(SNB)现象,而RL动态负荷模型系统并无分岔现象产生.为延迟PQ动态负荷模型系统的鞍结分岔点,在原系统中引入了线性状态反馈控制和SVC控制两种分岔控制方法.MATCONT仿真结果显示,这两种控制方法均能够有效延迟鞍结分岔,从而提高系统的电压稳定性,并可通过选择合理的反馈控制器增益及SVC增益获得理想的分岔控制效果. 相似文献
17.
钟宇明 《深圳职业技术学院学报》2012,11(3):13-17
与经典的PID控制器不同,模糊控制不需要获取系统精确的数学模型．根据系统的要求,设计模糊控制器,以给定参考电压与实际电压之间的偏差及其微分作为输入,通过合理的推理规则,得到占空比输出,去控制开关管的开关时间．论述了模糊控制器的详细设计过程,以及在MATLAB中建立仿真模型的过程．仿真结果表明系统具有较好的稳态和动态性能． 相似文献
18.
许胜辉 《武汉职业技术学院学报》2013,12(1):84-89
针对风力发电并网的优化问题。提出了三相电压源脉冲宽度调制（PWM）逆变器的定向矢量控制技术,并设计了数字控制的变换器一逆变器系统。给出了该变换器和逆变器的数学模型。提出了一种定向矢量控制的方案来实现对风能并网的控制策略。为了检验该系统的动态性能。采用MATLAB7／SIMULINK程序进行了仿真。仿真结果表明,提出的控制系统模型在不同的干扰下都展现出其良好的性能。 相似文献
19.
葛廷友 《南宁职业技术学院学报》2010,15(3):94-97
SVC在实际应用当中主要的作用是对电力系统中的电压进行控制,同时,SVC还可以控制系统的稳定性。TCR是晶闸管型SVC的最重要组成部件之一,它的投入对系统电压的稳定起到重要的作用。就SVC装置中TCR装置的投入,对系统母线电压的影响进行仿真研究。 相似文献
20.
HU Jia-bing HE Yi-kang 《浙江大学学报(A卷英文版)》2006,7(10):1757-1764
INTRODUCTION Due to concerns about emissions from fossil fuels and the depletion of fossil fuel resources, re- newable energy systems are becoming a topic of great interest and investment in the world. In particular, wind energy has been the subject of much recent research and development. In order to overcome the problems associated with fixed-speed wind-turbine system and to maximize the wind energy capture, many new wind farms will employ wind turbines based on Doubly-Fed Induction Ge… 相似文献