Magnetic Field and Operating Performance Analysisof Conical-rotor Permanent Magnet Synchronous Motor

In order to accurately analyze the magnetic field of conical-rotor permanent magnet synchronous motor(CR-PMSM),the effectiveness of two methods was studied on handling of problems concerned with non-uniform distribution of magnetic field along axial direction in CR-PMSM,which were sectional calculation(SC)method and three-dimensional finite element(3-D FE)method.On this basis,the influence of the axial displacement and dq-axis currents on the operating characteristics of axial magnetic force and torque is analyzed by using the 3-D FE model.Analysis results show that the axial magnetic force and torque decrease with the increase of axial displacement of the rotor,and the amplitude regularity of the axial magnetic force is affected by the d-axis current.A prototype machine is fabricated and tested,in order to validate the design theory.

Design and development of a synchronized operation control system for Thomson scattering diagnostic on J-TEXT

A Thomson scattering diagnostic system is under construction at the Joint Texas Experimental Tokamak（J-TEXT）. A 1064 nm Nd：YAG laser with 50 Hz repetition rate is used as the laser source. We have used a software for careful and precise control of the laser through serial communication. A time sequence operating system has been developed to synchronize the laser control and data acquisition system with the central control system（CSS）. The system operates commands from the CSS of J-TEXT and generates triggers for the laser and data acquisition system in the proper sequence. It also measures an asynchronous time value that is needed for accurate time stamping. All functions are served by a field-programmable gate array development platform that is suitable for high-speed data and signal processing applications.Several embedded peripherals, including Ethernet and USB 2.0, provide communication with the CSS and the server.

Retreatment of a patient who presented with synchronous multiple primary colorectal carcinoma: report of a case

It is well known that one-stage resection of synchronous multiple primary colorectal carcinoma is an ideal choice if the patient＇s physical condition is not bad. Detailed examination of the whole intestinal tract is very important for patients with colorectal cancer, which could prevent patients from receiving repeat treatment to a great extent. We present a case report of a patient with synchronous primary colorectal cancer. Because pre-or intra-operative examination is not sufficient at his first consultation, the patient had undergone multiple operations after receiving chemotherapy, radiotherapy and intestinal stent insertion, which results in peritoneal adhesions formation. The preoperative placement of prophylactic ureteral catheters facilitated recognition of ureters in operation that assure the prevention of ureteral injuries. If not aware of the importance of detailed preoperative examination and standardized treatment can lead to wrong treatment as in this case. Prophylactic ureteral catheters might assist in their immediate recognition.

Finite-Control-Set Model Predictive Control of Permanent Magnet Synchronous Motor Drive Systems——An Overview

Permanent magnet synchronous motors(PMSMs)have been widely employed in the industry. Finite-control-set model predictive control(FCS-MPC), as an advanced control scheme, has been developed and applied to improve the performance and efficiency of the holistic PMSM drive systems. Based on the three elements of model predictive control, this paper provides an overview of the superiority of the FCS-MPC control scheme and its shortcomings in current applications. The problems of parameter mismatch, computational burden, and unfixed switching frequency are summarized. Moreover, other performance improvement schemes, such as the multi-vector application strategy, delay compensation scheme, and weight factor adjustment, are reviewed. Finally, future trends in this field is discussed, and several promising research topics are highlighted.

Study on inverter fault-tolerant operation of PMSM DTC

This paper presents an investigation of inverter fault-tolerant operation for a permanent magnet synchronous motor （PMSM） direct torque control （DTC） system under various inverter faults. The performance of a faulty standard 6-switch inverter driven PMSM DTC system is analyzed. To avoid the loss or even disaster caused by the inverter faults, a topology-modified inverter with fault-tolerant capability is introduced, which is reconfigured as a 3-phase 4-switch inverter. The modeling of the 4-switch inverter is then analyzed and a novel DTC strategy with a unique nonlinear perpendicular flux observer and feedback compensation scheme is proposed for obtaining a continuous, disturbance-flee drive system. The simulation and experimental results demonstrate that the proposed inverter fault-tolerant PMSM DTC system is able to operate stably and continuously with acceptable static and pretty good dynamic performance.

A Fault Feature Extraction Model in Synchronous Generator under Stator Inter-Turn Short Circuit Based on ACMD and DEO3S

This paper proposed a new diagnosis model for the stator inter-turn short circuit fault in synchronous generators.Different from the past methods focused on the current or voltage signals to diagnose the electrical fault,the sta-tor vibration signal analysis based on ACMD(adaptive chirp mode decomposition)and DEO3S(demodulation energy operator of symmetrical differencing)was adopted to extract the fault feature.Firstly,FT(Fourier trans-form)is applied to the vibration signal to obtain the instantaneous frequency,and PE(permutation entropy)is calculated to select the proper weighting coefficients.Then,the signal is decomposed by ACMD,with the instan-taneous frequency and weighting coefficient acquired in the former step to obtain the optimal mode.Finally,DEO3S is operated to get the envelope spectrum which is able to strengthen the characteristic frequencies of the stator inter-turn short circuit fault.The study on the simulating signal and the real experiment data indicates the effectiveness of the proposed method for the stator inter-turn short circuit fault in synchronous generators.In addition,the comparison with other methods shows the superiority of the proposed model.

基于柔直控制的南方电网异步联网频率同步运行控制器设计与应用

电网分区异步运行将成为未来南方电网发展趋势,针对分区异步电网间频率失去了同步性和一致性问题,开展分区异步电网频率同步运行控制策略研究,提出了分区异步电网频率同步运行控制器结构,优化确定运行关键控制参数并通过仿真验证其有效性。鲁西柔直工程作为试点实施分区异步电网频率同步运行,现场实施效果表明该控制能够有效保证分区异步运行电网间实际运行中频率的一致性和同步性,且与电网AGC策略具有良好的适配性,实施中未出现两侧电网功率振荡和频率振荡发散情况,有效改善分区电网频率稳定性和提升分区电网间功率的灵活性支援性能,同时也实现全网调频资源的实时、自动共享,推动构建全网统一的调频辅助服务市场。

考虑储能约束的神经网络VSG参数自适应控制策略

虚拟同步发电机(Virtual Synchronous Generator, VSG)控制策略常用于处理高比例新能源并网导致系统惯量、阻尼缺失的问题,储能单元的配置制约着VSG惯量阻尼的设定。首先,建立考虑储能荷电状态(State of Charge, SOC)约束的VSG小信号模型,计算多约束条件下惯量阻尼取值范围。然后,借助径向基函数(Radial Basis Function, RBF)神经网络算法处理连续非线性函数的优点,提出一种计及储能约束的RBF神经网络VSG惯量阻尼自适应控制策略。该策略取频率偏差量和频率变化率为输入,输出为VSG转动惯量,根据二阶系统最优阻尼比确定阻尼系数取值。最后通过Matlab/Simulink仿真验证,结果表明所提计及多约束的VSG自适应控制策略能够快速响应系统频率变化,优化系统动态调节能力;减小直流母线电压跌落,增强系统鲁棒性。

Design of Automatic Quasi-synchronizing Device in Rural Small Hydropower Station

Generator synchronization is an important and frequent operation in rural small hydropower station. In order to ensure that generator can be paralleled in the grid automatically, efficiently, and stably in the rural small hydropower station whose parallel in operation still needs to be accomplished manually. This paper described an automatic quasi-synchronizing device, based on 89C52 Single-chip Microcomputer （SCM）. Its hardware includes three modules and its software is structuralized. The device structure is simple, and its reliability is high and the maintenance is easy. Besides, convenient Human Machine Interface （HMI） makes the parameter setting simple and flexible

Synchronous Construction and Operation of Coal Mine and Power Plant in Mining Area

In accordance with the experience withSynchronous construction of coal mine andpower plant in Yongxia mining area, thispaper discusses the existing issues regardingmine mouth power plant including capital,power grid connection, electricity price for gridconnection, installed capacity generation setselection as well as self- protection of coalindustry. It is regarded that under marketeconomy as long as the benefits of the threesectors of coal, electricity and the local arecomprehensively considered, a suitable waycan be arrived for conl industry to operate electricity business.

CLLC谐振变换器同步整流软开关失效分析与应对

同步整流(SR)是提高CLLC谐振变换器运行效率的有效方法,但由于功率管寄生电容等因素的影响,同步整流存在软开关失效的风险。因此,为同时实现同步整流和软开关,在变换器副边不控整流的基础上,分析了不同运行状态下同步整流软开关的失效原因,以及软开关实现的有效范围。提出了不同运行状态下的同步整流数字控制方法,可在保证实现同步整流软开关的同时,提高同步整流的运行范围,从而保证变换器在不同运行状态下的运行效率。同时,改进了不同运行状态下同步整流开通和关断时刻的计算方法,使得同步整流的控制无需电流传感器和其他额外硬件电路的参与,可应用于原本无同步整流控制相关硬件的双向CLLC谐振变换器中。搭建了实验平台,验证了所提方法的有效性。

不同稳态工况对同步调相机单相短路后暂态温升的影响

同步调相机可在系统故障时为特高压直流换流站提供暂态无功支持,以保持系统电压稳定,防止直流换相失败,但调相机的高无功输出也会导致其温升增加,运行能力受限。系统故障前同步调相机的初始工况是影响其暂态温升和运行能力的一个重要因素,为研究系统低电压时调相机暂态温升与初始工况之间的关系,该文将调相机的电磁场、温度场与电网模型耦合,计算调相机不同稳态工况下的定转子损耗和温度分布;以线路单相短路故障引起的系统低电压为例,研究调相机初始工况对暂态温升的影响。在考虑各结构件最大容许温度的条件下,揭示调相机单相短路持续时间随初始工况的变化规律。研究结果为提升调相机在系统低电压下的暂态运行能力提供技术支持。

泛血管医学时代“脑心同治”手术与展望

“脑心共病”逐渐受到国内外神经外科和心血管内外科医师的重视,并着手开展“脑心同治”手术互为保障,“泛血管医学”概念提出多学科交叉、跨学科整合的研究模式和发展理念。泛血管医学思想对“脑心同治”手术具有重要指导意义,“脑心同治”手术又使“泛血管医学”概念更加完整与深化。现阶段坚持以动脉粥样硬化性疾病为基础进行手术实施设计,“脑心同治”手术将在未来突破传统的颈动脉与冠状动脉同期手术范畴,过渡到以血管重建为中心的发展方向,从外科手术角度扩大“泛血管医学”概念的内涵。

交⁃直⁃交异步系统准同步控制下直流动态功频响应特性分析

经直流输电互联的异步系统通过对直流输电实施附加控制,可实现异步系统的准同步运行,达到实时共享异步系统调频资源的目的。但在准同步控制的工程实践中,不合理的控制结构或参数配置将导致系统出现非预期的功率波动。首先,根据直流准同步附加控制,构建准同步系统的动态功频响应分析模型;然后,基于该模型分析了直流控制参数对功率振荡的影响;进而,分析准同步控制导致的功率波动与传统功角振荡的异同;最后,以准同步实验过程中出现的功率波动为例进行分析验证,提出抑制直流功率波动的建议,并对准同步控制进行了讨论。

永磁同步电机无位置传感器控制技术综述

无位置传感器电机驱动器具有成本低、可靠性高、硬件电路简单以及维护要求少等优势,在学术界和工业应用中受到了越来越多的关注。对适用于零低速域、中高速域以及全速域三种运行范围的多种无位置传感器技术进行了综述。首先,分别对比分析了零低速域和中高速域下各种无位置传感器控制方法的优缺点。其次,梳理和总结了目前全速域运行的切换控制策略。最后,对永磁同步电机无位置控制技术的未来发展趋势进行了展望,并指出了后续研究的关键问题。

人群跳跃荷载时变协同性因子研究

协同性因子是跳跃人群中各单人间动作一致程度的度量指标,是人致结构振动分析中人群跳跃荷载建模的关键参数。现有协同性因子大都是定义在较长时段内的均值参数,其计算依据也是实验室条件下才能获取的地反力或特征点轨迹等,不能准确反映跳跃者个体差异的时变特性,也难以直接应用于实际场景下结构的振动监测。对此,提出了人群跳跃荷载的时变协同性因子,采用计算机视觉中的多目标跟踪技术对跳跃人群进行实时监测,并计算协同性因子。开展了佩戴无线测力鞋垫的多人跳跃实验,通过与实验结果的对比,验证了时变协同性因子的合理性以及多目标跟踪技术的有效性,可用于工程结构的安全运维、人致结构振动分析和人群跳跃时变荷载的模拟。

含跟网型储能的新能源多馈入系统小扰动电压支撑强度分析

储能正常工作时包含充电和放电两种运行模式,导致多储能变流器和多新能源变流器构成的多馈入系统工作点多变,加剧了系统小扰动同步稳定性分析的困难程度。为此,该文聚焦锁相环主导的小扰动同步稳定问题,首先,推导了兼顾储能充/放电运行模式的电网强度评估指标广义短路比,并提出了基于广义短路比及设备临界短路比的系统电压支撑强度分析方法,进而实现了系统小扰动同步稳定裕度的快速评估;然后,探究了跟网型储能变流器的充/放电运行模式对系统小扰动同步稳定裕度的影响规律,并根据矩阵联锁特征值定理论证了跟网型储能变流器工作在充电模式时,系统的小扰动同步稳定裕度高于放电模式;最后,基于仿真算例验证了所提系统小扰动同步稳定性分析方法的有效性。

基于差分运算的望远镜驱动系统非预期故障重构方法

极端环境下的望远镜驱动系统永磁同步电机传感器容易面临非预期故障,导致系统观测性能下降,甚至可能造成望远镜停机。在这种情况下,提出一种用于望远镜驱动系统电流传感器的故障重构方法,主要包含故障检测、隔离和重构等几个方面。其中,故障检测由三阶级联差分运算完成,对不同的故障类型、即使微小故障也能有很好的鲁棒性;决策逻辑电路根据故障检测提供的故障信号flag执行隔离操作;Switches开关根据隔离动作选择合适的电流,以达到故障重构目的。仿真试验表明,该方法从故障状态切换到健康状态是平稳的,且不影响系统的动态性能,确保驱动系统的可靠性和稳定性。

爱尔兰岛高比例新能源电力系统运行经验与启示

随着全球能源转型步伐的加快,世界各国电力系统均大力发展以风电和光伏发电为主的新能源。爱尔兰岛电力系统为岛屿独立同步电网,具有新能源渗透率高、与外部电网交互功率小等特点。经过长期摸索与发展,爱尔兰岛高比例新能源电力系统运行水平处于世界前列,其先进经验对我国新型电力系统建设具有重要借鉴意义。介绍了爱尔兰岛电力工业的概况,分析了爱尔兰岛电力系统的运行情况,探究了爱尔兰岛电力公司为保证高比例新能源电力系统安全高效运行采取的措施,最后总结其对我国新型电力系统建设的经验与启示。