电压源换流器实时多速率仿真研究

当前,高频换流器实时仿真在仿真精度和仿真灵活性上难以兼顾.为此采用了基于FPGA+PC的实时多速率协同仿真方法,全面展示了多速率协同仿真系统的仿真原理,以及硬件设计与实现.在30 kHz/50 kHz三相两电平逆变算例仿真的研究中,呈现了换流器建模、算例模型分割和电路求解器实现.以离线精确模型为基准,将多速率协同仿真平台与PC实时仿真平台的实验结果从仿真波形、仿真误差及实时性方面进行比较.结果表明,在开关频率50 kHz以下多速率仿真的速率转换误差收敛,电磁暂态仿真欧式范数误差达到1％左右,仿真平台仿真步长达到500 ns.该方法提高了高频换流器实时仿真精度、减小了仿真步长,为高性能协同仿真平台的设计提供了参考.     

配电网络故障及继电保护系统动态闭环数字仿真

讨论配电网络故障及继电保护的系统仿真方法.针对配电网络故障仿真的特殊要求和现有仿真方法的不足,重点针对消弧线圈、电流互感器、保护继电器分别建立仿真模块,形成实用的故障暂态仿真模型.基于ATP/EMTP平台,开发仿真软件,实现对故障发生、识别和隔离的动态仿真.仿真结果验证了仿真模型和软件的正确性.该仿真模型为配电网保护系统原理及其暂态性能分析和配电网的故障隔离过程模拟提供了实用的工具.     

复杂电力设备多学科协同/虚拟仿真的关键技术

针对复杂电力设备结构复杂,所涉及的学科众多,系统仿真难度大的特点,将复杂设备多学科协同仿真引入电力设备系统仿真领域,提出了复杂电力设备的多学科协同/虚拟仿真平台的体系结构.该体系结构支持分布的异构的仿真工具和模型进行跨领域交互仿真.研究分析了多学科协同/虚拟仿真的部分关键技术,包括电力一体化模型、多学科知识集成、多学科仿真工具集成和仿真资源库技术.运用COM/DCOM、数据库和网络技术建立了多学科协同/虚拟仿真平台的技术体系结构,使得参与系统仿真的不同学科领域的仿真工具都能够获得所需要的其它学科的约束条件和仿真结果,并使得参与仿真的专家在虚拟场景中观察可视化的仿真结果.     

永磁直驱风电机组硬件在环实时仿真方法分析

基于RT-LAB仿真平台,分别搭建了永磁直驱风电机组的CPU仿真模型和CPU+FPGA仿真模型,对比了两种模型的差异,介绍了状态空间节点(SSN)算法、普约维奇方法及其提升仿真效率的原理,并就产生的不同仿真步长,对比分析了其对仿真结果的影响.定量研究了模型产生的接口延时,确定了接口延时与仿真器、仿真步长间的关系.仿真结...     

基于高层体系结构的电力市场分布交互仿真

简要介绍了建模与仿真领域中解决仿真系统重用性和互操作性问题的高层体系结构,提出电力市场分布交互仿真的概念,分析了仿真部件间的信息交互和同步问题.在高层体系结构国际标准下,以日前电力市场为例,通过改造和重用某些既有的仿真资源,设计、实现并验证了原型仿真系统,指出采用高层体系结构开发电力市场仿真系统的优点.电力市场原型仿真系统的实现,证实这一新型仿真体系结构在电力系统仿真领域的适用性.     

储能变流器功率模组的优化设计及散热仿真分析

功率模组作为储能变流器的核心单元,其散热问题引起了广泛的关注.以某500kW 储能变流器的功率模组为研究对象,从物理模型、风机选型、散热器设计、热仿真分析等方面详细介绍了功率模组的散热系统.建立了仿真模型,通过仿真计算优化了散热器的结构参数,并分析了功率模组的散热特性,最后通过试验数据和仿真计算对比, 验证了基于数值仿真的可靠性.该研究有效提升了选型的精确度,缩短了散热器设计周期,对后续的功率模组热仿真分析和优化具有重要的指导意义.     

电力系统移频电磁暂态仿真原理及应用综述

高效、精确的电磁暂态仿真是支撑电力系统运行和控制的关键技术.为了解决传统电磁暂态仿真中速度和精度之间的矛盾,提出了移频电磁暂态仿真方法.文中对移频电磁暂态仿真理论的关键技术进行梳理并对其中存在的部分问题进行分析.首先,介绍移频电磁暂态仿真的原理.然后,依次对移频电磁暂态仿真中的3个关键点进行分析,包括复数信号的构造方法、移频变换的具体形式、移频仿真的模型及其特点.接着,对移频电磁暂态仿真技术应用的研究现状进行了介绍.最后,讨论了现有移频电磁暂态仿真中存在的部分关键问题.     

立式电机定、转子虚拟样机建模与仿真研究

基于Pro/Engineer建立了某型号的大功率电机的实体模型和虚拟样机模型.在MSC.PATTERN/NASTRAN环境下,利用有限元方法进行了电机整机的动力学仿真、应力应变仿真和模态仿真,得到了电机两端轴承的力学状态、系统的多阶固有振动频率、振型以及应力、应变、位移等参数值,通过应变测试实验验证了仿真结果.根据仿真结果,分析了电机的危险位置和振型.结果表明现有电机的结构基本满足设计要求,同时给出了电机结构的优化方案,为同类产品的开发和改进提供了参考.     

发电机采用数模混合仿真的微型动模试验系统

基于当前动模、数字仿真遇到的问题,搭建了基于数模混合发电机的微型动模试验系统.数字、物理混合仿真的发电机采用了功率在环技术,结合了物理仿真和实时数字仿真的优点,更接近现实的试验,实时运算可反复修改,减少测试验证周期.发电机采用数模混合仿真的微型动模试验系统,可实现电力系统的低电压、小电流、微功率的物理模拟,减少了测试准备时间、验证周期和测试成本,有效提高了电力系统仿真建模、验证研究的技术水平.     

串联混合型有源电力滤波器的仿真研究

通过建立混合系统的单相等效电路图,分析了串联混合型电力滤波器的补偿特性,并且给出了无源滤波器的参数设计、耦合变压器的参数设计、输出滤波器的设计及有源滤波器主电路的选择.利用MATLAB构建了仿真模型,给出了仿真参数,得到了仿真结果.仿真结果表明了串联混合型有源电力滤波器理论分析的正确性.     

带串联补偿故障限流器的仿真和实验

采用短路电流限制器(FCL)快速限制短路电流是提高系统稳定性和断路器开断能力的有效方法之一。文中研究了一种具有串联补偿作用的FCL模型——由补偿电容和旁路电感并联后与限流电感串联而成。正常情况下，由电容和限流电感对线路进行串联补偿；发生故障时，根据短路电流的大小控制门极可关断晶闸管的导通角，改变投入的限流电抗，达到限流目的。用MATLAB对馈线短路的仿真及采用单片机控制方案的单相实验结果表明，该限流器限流效果良好。     

Studies on thrust characteristics of high‐thrust spiral motor

Linear actuators are used in various industrial applications. Conventional linear actuators are a combination of a rotational motor and a ball screw, a hydraulic actuator, or a linear motor. However, these actuators have some demerits. This paper proposes a spiral motor (SPRM) that comprises a helical stator and a helical mover. Owing to its helical structure, the SPRM can be expected to show better performance compared to the conventional linear actuator. A stator and a mover are shown in Figs. 1 and 2, respectively. Helical motion is obtained by this motor and only linear motion is extracted by canceling rotational motion at the end effector. There are two types of SPRMs. One has no ball screw on the output axis, while the other has a ball screw. The former can be used in a direct drive system. However, the gap between the stator and the mover should be controlled because the motor is a magnetic levitation system without a ball screw. Further, the motor requires two three‐phase inverters. The other motor is easy to control because it does not require gap control. However, the motor is inferior to the first motor with regard to position control since the friction in this motor is larger. In this study, a prototype of the SPRM is developed. The prototype constructed is a motor with a ball screw. In this motor, the stator and mover are made of block cells. The stator block is shown in Fig. 3 and the mover block is shown in Fig. 4. The prototype of the SPRM shown in Fig. 5, is developed by using these two blocks. An experiment is conducted to examine the driving of the SPRM. The experimental result is shown in Fig. 6. From this result, it is evident that comprising a helical stator and a helical mover can generate linear motion. Another experiment is conducted for measuring the thrust characteristic of the motor. The result obtained is shown in Fig. 7. From the figure, the thrust constant of the spiral motor, K_f, is obtained as 538.0 N/A. © 2011 Wiley Periodicals, Inc. Electr Eng Jpn, 177(2): 58–64, 2011; Published online in Wiley Online Library ( wileyonlinelibrary.com ). DOI 10.1002/eej.21168     

分叉理论与Matcont在含FACTS装置的电力系统电压稳定性分析中的应用研究

随着非线性科学理论研究的发展,分叉理论作为研究非线性系统的新方法被引入电压稳定研究中。简要介绍了分叉的基本概念和主要分叉点类型,然后以基于Matlab的分叉分析软件包Matcont为工具,应用分叉理论,对典型的不含FACTS装置和含FACTS装置进行电压稳定的分析。最后重点对Matcont得出的数据进行了详细的分析,研究发现,通过添加FACTS装置,可以有效减少分叉点数量,增加负荷极限,从而提高了系统电压稳定性。     

基于高频重构信号与Bayes-XGBoost的低压电弧故障辨识方法研究

针对低压配电系统中单个用电负载支路串联电弧故障辨识困难的问题,提出一种基于高频重构信号和Bayes-XGBoost的低压电弧辨识方法。首先,搭建多支路、多负载类型的低压电弧故障真型实验平台,并采集相关数据。其次,基于故障前后主线路电流高频信号变化规律,提出信号微弱变化叠加法重构故障有效信号。最后,建立适用于单个负载支路电弧故障辨识的XGBoost模型,并采用Bayes算法对模型多个超参数进行优化。实验结果表明,所提方法在多种工况下对单个负载支路电弧故障具有较高的辨识准确率。与6种主流故障分析方法对比,所提方法在精度、训练速度和泛化能力等方面展现出了显著的优越性,有利于实现低压配电系统单个负载支路电弧故障的可靠辨识。     

双流制机车变压器绕组复用电抗器对直流母线电压稳定性的影响

为减少双流制机车体积和重量,直流工作制式下牵引变压器二次侧绕组充当平波电抗器即为其中一项关键技术。二次侧绕组接线方式不同时,其等效电感值可能非线性,这将对直流母线电压稳定性造成重要影响。针对该问题,首先将变压器当作普通电感,建立起双流制机车直流供电模式下系统等效电路,并运用小信号分析法对牵引变压器复用平波电抗器时直流母线电压的稳定性进行了分析;然后在牵引变压器二次侧绕组正串与反串两种不同接线方式下,提出了小信号模型下对应电感值的计算方法,以此得到变压器复用平波电抗器时对直流母线电压稳定性的影响,整个分析求解过程对多流制或双流制机车的研发与应用具有很好的指导作用。     

基于深度特征融合网络的风电机组行星齿轮箱故障诊断方法

行星齿轮箱是风电机组中的重要部件,对风电机组的安全可靠运行具有重要意义。为此,提出一种基于深度特征融合网络的行星齿轮箱故障诊断方法,用于实现变速工况、样本不足和强噪声场景下的故障诊断。首先将原始信号扩展到多个特征域。其次利用多维堆栈稀疏自编码器提取各域特征。最后针对传统Softmax分类器对融合信息分类能力不足的问题,提出基于竞争粒子群算法优化的回声状态网络进行特征融合并输出诊断结果。经多场景不同故障诊断方法对比实验,所提方法在行星齿轮箱变速工况下分类效果良好,并对训练样本的减少和外界噪声有很强的鲁棒性。     

An Energy-efficient Switching Scheme with Reduced Switching Transients for a Wind-driven Induction Generator

This article presents a scheme for improving the power output of grid-connected induction generator commonly used in wind energy conversion systems. Generally, the stator of the induction generator is connected in a star with a line voltage of √3 times the rated winding voltage to reduce the line current and, hence, conductor size. To extend the generating operation over a wider speed range, delta-star switchable stator windings are also in vogue. In such cases, the stator is star connected in the lower speed range and switched to a delta connection above a threshold speed. In this study, a new switching scheme is proposed wherein the stator coils are always connected in a star, while the stator is connected to different voltages in low- and high-speed conditions. At low wind speeds, nominal winding voltage is applied to the stator, whereas at higher speeds, the stator applied voltage is √3 times higher than the rated winding voltage. The efficacy of the scheme is demonstrated experimentally with a suitable microcontroller-based switching arrangement. Typical results indicate an increase in output with reduced switching transients. A case study on a 3-Φ, 50-kW induction generator is presented to emphasize the performance improvement with the proposed scheme.     

Rotor oscillation damping of a stepping motor by sliding mode control

Stepping motors are used mainly in OA and FA systems due to the merits of their digital driving behavior using switching devices. They are driven by closed‐loop control in systems where special performance such as prevention of out‐of‐synchronism or a high‐speed drive is required. It is well known that rotor oscillation is one of the principal problems in the switched drive of a stepping motor, and nowadays several methods for damping this oscillation have been suggested in which the switching sequence is changed in some manner. In such methods, the excitation time of the stator windings must be tuned appropriately, or the effect of damping is insufficient and oscillation may be even amplified in some circumstances. To resolve this problem, adaptive methods for tuning of the excitation time have been developed. However, they suffer the disadvantage that they require a tuning period for the excitation time to attain the optimal value at the beginning of control or when the machine parameters are varied by changing the driving condition. The authors have developed a new method for rotor oscillation damping of a stepping motor in a closed‐loop system. It is based on a sliding mode control technique and is designed to be robust to variation of rotor inertia which significantly affects the oscillatory characteristic. In this method, a lower‐order dynamical model, obtained by reaching a sliding mode where the angle‐torque characteristic of the motor is bound to a certain linear function, is made non‐oscillatory by pole assignment over a certain region of varying rotor inertia. Applying this method to an experimental system, rotor oscillation is damped excellently in the cases of single‐step and low‐speed multi‐step drive. On the other hand, it is shown deceleration is needed near the last step in the case of a high‐speed drive. © 1998 Scripta Technica, Electr Eng Jpn, 126(1): 42–51, 1999     

基于仿真对象的控制开发平台设计

针对控制工程中现场需要在线频繁调整控制策略、调试不便且工期紧张的问题,设计了对控制系统在实验室进行离线仿真测试的通用开发平台。平台硬件由控制计算机、PLC、数据采集卡和仿真计算机组成,平台软件主要由MATLAB和Win CC组成,在MATLAB中建立实际控制对象的模型后在Win CC中编写控制算法,离线测试达到控制目标后将控制计算机部分以及PLC转移到控制现场,缩短现场调试时间的同时提高了控制系统的可靠性。     

"自控变频同步电机"系统中的交流电机是箝位电动机

针对直流电动机中电枢磁动势的轴线位置由电刷决定的特征,提出了箝位概念,指出自控变频乃是箝位效应的直接后果。对作为电机类型名称的"同步"一词之含义作了明确地阐述,同步电动机是无箝位电动机,稳定运行的同步电动机内频率与本机转速之间的因果关系是以恒定的频率为因。直流电动机是箝位电动机,箝位效应使直流电动机中频率与转速的因果关系颠倒成以易变的转速为因,直流电动机具有优良的控制性能以及无振荡的特性都与箝位的存在密切相关。"自控变频同步电机"系统中的电动机应是交流箝位电动机,而不是同步电动机。