PASSIVE-ACTIVE CONTROL OF POWER FLOW IN AN ISOLATION SYSTEM MOUNTED ON FLEXIBLE FOUNDATIONS

A general model of flexible isolation systems which involves both the passive and active control factors is established by inserting actuators into an passive isolation system. And the power flow transmission function in such a system as with multi disturbance, multi mounts, passive isolators and actuators is deduced. By means of the numerical simulation method, the influence of actuators on power flow transmission characteristic is studied. And as a conclusion, the passive active synthetic control strategy of power flow is summarized.

General Model to Predict Power Flow Transmitted into Laminated Beam Bases in Flexible Isolation Systems

For estimating the vibration transmission accurately and performing vibration control efficiently in isolation systems, a novel general model is presented to predict the power flow transmitted into the complicate flexible bases of laminated beams. In the model, the laminated beam bases are simulated by the first-order shear deformation laminated plate theory, which is relatively simple and economic but accurate in predicting the vibration solutions of flexible isolation systems with laminated beam bases in comparison with classical laminated beam theories and higher order theories. On the basis of the presented model, substructure technique and variational principle are employed to obtain the governing equation of the isolation system and the power flow solution. Then, the vibration characteristics of the flexible isolation systems with laminated bases are investigated. Several numerical examples are given to show the validity and efficiency of the presented model. It is concluded that the presented model is the extension of the classical one and it can obtain more accurate power flow solutions.

POWER FLOW ANALYSIS FOR A NEW ISOLATION SYSTEM-FLEXIBLE FLOATING RAFT

A new model for a raft isolation system is proposed, in which the raft supports two ma- chines on a flexible foundation via a series of isolators. The interaction between the flexible floating raft and the non-rigid foundation is studied by the novel approach of power flow. The power flow input and transmitted in the complicated compound system are then formulated in closed forms, in which the coupling between the raft and the foundation is considered . The effect of the raft flexibili- ty on power flow spectra is also revcaled. This study shows that it may lead to an overoptimistic evaluation to the effectiveness of the raft isolation when simplifying the raft to an ideal rigid struc- ture. Thereby, the reliable estimation and effective design for raft isolation system are provided.

PASSIVE-ACTIVE CONTROL OF A FLEXIBLE ISOLATION SYSTEM

Passive-active control of a flexible isolation system is investigated from the viewpoint of power flow. Dynamic transfer equations of the system are deduced based on a matrix method which uses mobility or impedance representations of three substructures: the source of vibration, the receiver and the mounting system which connects the source to the receiver. The cancellation of axial input forces to the receiver is considered as the active control strategy and its effects are discussed. The results of the study show that the strategy adopted herein can effectively reduce the power transmitted to the receiver.

A NEW MODELING METHOD FOR MACHINE-FOUNDATION COUPLING SYSTEM AND ITS APPLICATION TO THE CONTROL OF POWER FLOW

A new concept, namely, the equivalent mobility matrix of coupling subsystem is proposed, and the corresponding threesubsystem coupling progressive approach is explored. With the new efficient approach presented, the complexity in dealing with a more complicated dynamic coupling system is greatly reduced. The new modeling method is then combined with the theory of power flow to investigate the dynamics of the overall non rigid isolation system from the viewpoint of energy. The interaction between the resilient machine of its main modes and the resonant behavior of the flexible foundation on power flow transmission is studied. Taking a machine tool mounted on a multi story working plant as an example, the dynamic characteristics of the machine foundation coupling system are analyzed, and their effects on power flow transmission are revealed under various service frequency bands. Some advisable control strategies and the design principle for machinery mounted on flexible structure are proposed.

Analysis of vibration and frequency transmission of high speed EMU with flexible model

When the operation speed of the high-speed train increases and the weight of the carbody becomes lighter,not only does the sensitivity of the wheel/rail contact get higher,but also the vibration frequency range of the vehicle system gets enlarged and more frequencies are transmitted from the wheelset to the carbody.It is important to investigate the vibration characteristics and the dynamic frequency transmission from the wheel/rail interface to the carbody of the high-speed electric multi-uint（EMU）.An elastic highspeed vehicle dynamics model is established in which the carbody,bogieframes,and wheelsets are all dealt with as flexible body.A rigid high-speed vehicle dynamics model is set up to compare with the simulation results of the elastic model.In the rigid vehicle model,the carbody,bogieframes and wheelsets are treated as rigid component while the suspension and structure parameters are the same as used in the elastic model.The dynamic characteristic of the elastic high speed vehicle is investigated in time and frequency domains and the di ff erence of the acceleration,frequency distribution and transmission of the two types of models are presented.The results show that the spectrum power density of the vehicle decreases from the wheelset to the carbody and the acceleration transmission ratio is approximately from 1%to 10%for each suspension system.The frequency of the wheelset rotation is evident in the vibration of the flexible model and is transmitted from the wheelset to the bogieframe and to thecarbody.The results of the flexible model are more reasonable than that of the rigid model.A field test data of the high speed train are presented to verify the simulation results.It shows that the simulation results are coincident with the field test data.

Solving Optimal Power Flow Using Modified Bacterial Foraging Algorithm Considering FACTS Devices

In this paper, a new Modified Bacterial Foraging Algorithm (MBFA) method is developed to incorporate FACTS devices in optimal power flow (OPF) problem. This method can provide an enhanced economic solution with the use of controllable FACTS devices. Two types of FACTS devices, thyristor controlled series compensators (TCSC) and Static VAR Compensator (SVC) are considered in this method. The basic bacterial foraging algorithm (BFA) is an evolutionary optimization technique inspired by the foraging behavior of the E. coli bacteria. The strategy of the OPF problem is decomposed in two sub-problems, the first sub-problem related to active power planning to minimize the fuel cost function, and the second sub-problem designed to make corrections to the voltage deviation and reactive power violation based in an efficient reactive power planning of multi Static VAR Compensator (SVC). The specified power flow control constraints due to the use of FACTS devices are included in the OPF problem. The proposed method decomposes the solution of such modified OPF problem into two sub problems’ iteration. The first sub problem is a power flow control problem and the second sub problem is a modified Bacterial foraging algorithm (MBFA) OPF problem. The two sub problems are solved iteratively until convergence. Case studies are presented to show the effectiveness of the proposed method.

柔性互联输配一体化电网有损潮流的精细化建模及应用

多端柔性互联输配一体化电网内部的运行方式复杂、网损特性差异显著,导致传统一刀切的网损补偿方法难以准确刻画网损的实际情况,影响了输(配)电交直流有损潮流模型的应用潜力和输配边界潮流的一致性。为此,该文提出一种基于双层定点迭代的精细化有损潮流模型。针对网损补偿方法不准确的问题,综合考虑网络类型、数据属性和物理特征等因素,为输、配电网及交、直流电网的精准有损潮流分析建立了差异化的网损补偿模型。针对输配边界潮流的不一致问题,将输配一体化有损潮流建模为一个双层定点迭代问题,并采用主从分裂法实现协同求解。在多个算例中分析了不同有损潮流模型的性能差异及其原因,讨论了所提模型在求解精度、收敛速度和计算效率等方面的优势,验证了所提模型在不同控制方式和优化目标下的鲁棒性和通用性。

周期桁架结构设计及振动特性分析

为解决船舶动力系统低频振动噪声问题,本文基于声子晶体局域共振理论,设计了一种带周期振子桁架式浮筏结构。利用有限元法和Bloch理论,分析了周期振子桁架产生带隙的原因,讨论了振子质量、安装形式和桁架结构参数对带隙特性的影响规律,设计了周期振子桁架振动特性试验,探究了桁架结构振动传递特性。结果表明:振子质量越大,带隙宽度增加,胞元尺寸越大,带隙带宽减小;振子排列方式对带隙特性影响较小,增加振子数量,宽带特性显著;采用振子间隔安装方式,相较全安装方式,带隙特性变化较小,可有效减少振子数量。

挠性接管长度对管路隔振效果影响趋势与试验研究

系统管路是船舶的主要噪声源之一,采用挠性接管是降低管路振动噪声传递的主要手段。为提高挠性接管的隔振效果,开展挠性接管长度对管路系统振动传递影响的理论分析和试验研究。研究表明,加长挠性接管有利于提高管路衰减的振动量级,但对低频段振动衰减效果有限。研究结论对合理选择挠性接管长度和开展管路系统的低噪声设计具有重要意义。

内燃动车组动力包刚柔耦合双层隔振系统动力学建模及参数影响分析

动力包系统为内燃动车组的重要组成部分,其隔振性能直接关系到动车组的运行安全性及乘坐舒适性。针对动力包刚柔耦合双层隔振系统,提出了一种基于子结构频响函数综合的动力包刚柔耦合双层隔振系统建模方法。该方法将动力包系统分为发电机组、散热器机组、公共构架和车体地板子结构,通过2次频响函数综合建立了公共构架B-基础D综合体和机组刚体的频响函数表达式,大大提升了建模效率与计算速度,对工程计算和设计具有重要的价值。通过与ABAQUS软件中有限元频响结果进行对比,验证了该方法的正确性与计算精度。以某型内燃动车组动力包系统为研究对象,利用该建模方法,结合动力包系统实际隔振设计需求,研究了子结构质量比、子结构刚度、子结构阻尼、各级隔振器刚度及阻尼等参数对动力包系统隔振性能的影响规律,为内燃动车组动力包隔振系统设计及优化提供了理论支撑。

舰船复合材料轴振动能量传递特性研究

针对舰船复合材料传动轴减振机理尚不清晰的问题,文中构建了某舰船复合材料轴仿真模型,基于功率流法分析了复合材料轴振动能量传递特性,并在此基础上进一步探究了钢法兰-复合材料刚柔耦合界面匹配参数和轴段内复合材料铺层方式对振动能量传递的影响规律。最后通过复合材料传动轴模态试验和振动传递试验验证了仿真模型的准确性。结论如下:刚柔耦合界面对于振动能量抑制有着显著作用,其振动能量的传递随接触面积的增大而降低,而弹性模量比仅影响传动轴固有频率;随着铺层角度的减小及铺层数量的增加,复合材料轴段隔振性能逐渐增加。

A Novel Location Method for Interline Power Flow Controllers Based on Entropy Theory

As one of the new generation flexible AC transmission systems(FACTS)devices,the interline power flow controller(IPFC)has the significant advantage of simultaneously regulating the power flow of multiple lines.Nevertheless,how to choose the appropriate location for the IPFC converters has not been discussed thoroughly.To solve this problem,this paper proposes a novel location method for IPFC using entropy theory.To clarify IPFC’s impact on system power flow,its operation mechanism and control strategies of different types of serial converters are discussed.Subsequently,to clarify the system power flow characteristic suitable for device location analysis,the entropy concept is introduced.In this process,the power flow distribution entropy index is used as an optimization index.Using this index as a foundation,the power flow transfer entropy index is also generated and proposed for the IPFC location determination study.Finally,electromechanical electromagnetic hybrid simulations based on ADPSS are implemented for validation.These are tested in a practical power grid with over 800 nodes.A modular multilevel converter(MMC)-based IPFC electromagnetic model is also established for precise verification.The results show that the proposed method can quickly and efficiently complete optimized IPFC location and support IPFC to determine an optimal adjustment in the N-1 fault cases.

FACTS技术在电力系统中的应用

柔性交流输电系统(FACTS)建立在电力电子或其他静止型控制器基础之上,通过对电力系统的某个或多个参数进行调节,从而实现电力系统可控的目标,进而增强电力传输能力和系统运行的稳定性。本文对柔性交流输电系统中FACTS控制器的3种类型进行了介绍,对4种典型的FACTS控制器的工作原理、稳态模型以及动态模型进行了研究。从控制电力系统的无功功率和电压、改善低频振荡、提高系统的暂态稳定性等方面,介绍了FACTS控制器在电力系统中的应用。

Power flow transmission influenced by vibration source impedance for a compound system

In this paper we present the effect of vibration source on the power flow transmission in a compound flexible system. Considering the internal impedance of the source, a general model is here proposed, and the generalized transfer equations of the system and the closed form solutions for power flow in the fiexible system are then developed, with which the effects of the source characteristics on power flow transmission are discussed. The investigation shows that when the source and receiver impedances are comparable, substantial error can occur in the power flow estimation if the source is assumed to be an ideal constant force source (CFS)or a constant velocity source (CVS).

Power flow transmission in a coupled flexible system with active executive elements

Based on its prototype of machine-isolator-foundation systems, a theoretical model for dynamic coupled linear system is established, in which both the passive and active control factors are considered. Power flow is used as the cost function to evaluate the isolation effectiveness. And the transmission of vibratory power flow from a vibrating rigid body into a simply supported thin panel through passive isolators and actuators is investigated numerically. The active control strategy is summarized in the conclusion.

基于多目标袋獾算法的含VSC换流器交直流系统最优潮流

针对传统算法易陷入局部最优、参数选取困难,难以对多目标函数统一协调等缺陷,计及不同换流站的控制方式下提出一种基于多目标袋獾优化算法(multipleobjective Tasmaniandeviloptimization,MOTDO)的含电压源换流器(voltage source converter,VSC)交直流系统的最优潮流算法。构建计及换流器损耗的交直流潮流计算模型,以系统最小经济成本、系统最小损耗和线路最小电压偏差为待优化目标,引入惩罚函数建立多目标潮流优化模型;在不同的控制方式下,采用MOTDO算法进行潮流优化,得到完整且均匀分布的帕累托(Pareto)集合并根据评估指标得到Pareto中的最优解;以含多端直流网络的改进型IEEE 30节点系统为例验证MOTDO算法对潮流优化的有效性,为须考虑多目标的交直流混合电网的安全稳定运行提供参考。

局域共振浮筏隔振系统的低频隔振性能研究

为提升浮筏隔振系统的低频隔振性能,提出在筏架表面周期布置局域共振元胞的设计方法,构建局域共振浮筏隔振系统的动力学模型,以系统的输出功率流为评价指标,分析共振元胞对单频和多频振动激励下浮筏隔振系统低频隔振性能的影响.研究表明,在附加振子质量小于筏架质量10%的前提下,能够降低系统的输出功率流幅值30%左右;共振元胞中含不同固有频率的振子时,可以同时降低多个频率处系统的输出功率流.研究结果可为采用局域共振结构提升浮筏隔振系统低频隔振性能提供理论指导.

基于改进拟牛顿法的柔性直流系统潮流算法

针对目前柔性直流输电系统潮流算法存在的雅可比矩阵求解困难、算法效率低等问题,提出了一种基于改进拟牛顿法的交直流系统潮流算法,使用Broyden方法更新每次迭代过程中的雅可比矩阵,避免了雅可比矩阵的重复形成,减少了单步迭代的计算量,同时使用三阶牛顿法的迭代形式,提升了算法的收敛阶数,有效地避免了因拟牛顿法收敛阶数过低而造成的迭代次数增加问题,使得其计算效率相较于传统牛顿法与Broyden方法更有优势。最后,对不同规模的柔性直流输电系统进行潮流计算仿真分析,从交直流潮流结果、控制方式、算法效率、重负荷下的算法性能等方面进行对比分析,结果表明:提出的算法适用于多种算例情况,且具有与传统牛顿法相同的精确性,同时其算法效率相较于传统牛顿法得到了显著的提升,平均计算时间缩减率可以达到26.712%。

基于功率流的复合材料层合板连接节点振动传递特性

[目的]为了研究复合材料层合板连接节点的振动传递特性,提出一种采用有限元功率流法并结合功率流可视化技术的分析方法。[方法]首先,验证用有限元实体单元功率流描述板壳振动的有效性;然后,引入功率流传递率评价指标,提出有限元模型功率流传递率的计算方法,并以导纳功率流法计算结果为参照来验证其有效性;最后,建立嵌入式连接和螺钉连接这2种复合材料层合板的连接模型,计算其功率流传递率曲线和典型功率流矢量图。[结果]对比验证结果表明,2种连接模型的振动传递路径和功率流传递率存在明显差异。[结论]有限元功率流法直观反映了连接结构的振动传递能力及振动能量传递路径,可为复合材料结构设计提供参考。