两类逆变侧控制策略对系统电压与直流主回路设计影响

针对高压直流输电工程逆变站通常采用的定关断角与定电压两类控制策略对系统电压与直流主回路设计的影响进行研究。首先从控制系统原理入手,分析了逆变侧定电压与定关断角两种控制策略的逻辑区别;然后利用电力系统分析计算软件PSD-BPA,模拟了换流站投切滤波器分组的实际工况,明确了两种控制策略在系统电压调节特性方面的差异;最后基于某实际高压直流工程的系统条件和运行参数,借助实时数字仿真系统,校核了定电压与定关断角两种控制策略下系统电压的暂态与稳态恢复特性,进一步验证了相关结论。在此基础上,研究并论证了两种控制策略对于直流换流站无功补偿容量、额定空载直流电压等直流主回路设计基本结论以及主要设备参数的影响。

功率硬件在环仿真中功率接口直流电压控制及电容参数设计

作为功率硬件在环(PHIL)仿真中连接数字侧和物理侧仿真的互联装置,功率接口对PHIL仿真系统的稳定性起决定性作用。物理侧负载扰动所引起的直流电压波动是影响功率接口的稳定运行的关键问题之一。针对这一问题,为了提高PHIL仿真系统稳定性,考虑控制时滞,提出一种基于直流输出电流前馈的直流电压改进控制策略,并给出了其前馈系数的参数设计方法。根据变流器交直流侧有功功率平衡关系,利用小信号分析方法,建立了功率接口交直流统一模型,通过该模型分析并证明了所提控制策略在负载小扰动情况下抑制直流电压波动的有效性。提出一种直流电容参数计算方法,并证明前馈控制可以有效地减少直流电容。最后,仿真和实验验证了所提方法的有效性。

车载直流液压举升系统的设计

本文介绍了国内先进的车载直流液压举开系统的设计。重点阐述了该机的基本性能、使用范围、使用特点及其先进性。

现役交流配网XLPE电缆系统改直流运行的基础性方案设计研究

随着柔性直流输电技术的发展,将现役交流XLPE电缆线路改为直流运行以提升传输能力已成为全球关注的热点。以交流配网中典型的单/三芯XLPE电缆(110kV及以下)为例,从主接线形式选择、线芯回路配置、接地方式设计3个方面开展了单/双回路配电线路的直流改造方案设计研究,综合考虑投资成本、供电可靠性、传输容量、工程实用性等方面,系统分析了直流改造的可行性。研究结果可为现役交流配网改直流运行的实际工程应用提供重要参考。

110KV变电所直流系统设计

110kV变电所直流系统是为控制、信号、继电保护、自动装置和事故照明及交流不停电电源装置的供电而设置的,直流系统是保证变电所可靠运行和事故处理安全性的必要设施。直流系统事故往往引起全所停电的恶性循环事故。直流系统的举足轻重作用已被设计部门、生产管理部门和运行部门广为认同。文章就110kV变电所选用阀控式密封铅酸蓄电池的直流系统设计中主要环节进行简述。

高压直流远供在LTE基站设计中的应用指导

随着LTE移动通信技术的发展和全业务经营的开展,分布式基站已成为了网络覆盖建设的主要方式。移动网络建设中分布式组网场景中的电源保障问题对现有的通信电源保障体系提出了新的要求。文中结合应用场景及案例分析阐述了高压直流远供电源系统在移动基站设计中的应用,并从设计角度给出了合理推广的建议。

现役交流XLPE电缆绝缘切片试样的交、直流耐压性能对比

为升级输电线路的传输能力,可将现役交流XLPE电缆线路改为直流运行,但仍缺乏改造方案设计的统一标准或规范。因而对1根投运7年的YJV22-8.7/10 kV-3×185 mm^2电缆进行绝缘环切,在相同条件下对切片试样进行交流及直流电压下的连续和逐级升压击穿试验。结果表明:升压速率为2、0.5、0.1 kV/s的连续升压击穿试验中,升压速率对试样的交流平均击穿场强影响很小,而对直流击穿场强影响较大;时间步长为2、6、15 min的逐级升压试验中,随着时间步长的增加,交流击穿场强略有降低,而直流击穿场强显著增大。随着电压施加时间的增加,交流击穿场强下降,而直流击穿场强反而增大,这导致直/交流击穿场强比值持续增大,由1.33增大至3.73。以击穿场强的95%置信下限值为基础,推导可获得XLPE绝缘试样的交、直流1 h击穿场强分别为89.50 kV/mm及247.55 kV/mm,而反幂定律中的电老化寿命指数拟和值为17和-11.51。在高压短时击穿试验范围内,试样的直流耐压性能随时间变化不符合传统电老化寿命定律,这可能与空间电荷效应的时间依赖性有关,需要后续研究进一步确认;同时也说明基于薄试样、高电压、短时间的击穿试验数据无法有效反映直流绝缘的长期电老化性能,不能直接用于XLPE直流电缆的绝缘结构设计。

基于电力电子调压电路的直流不停电融冰技术

我国冬季出现的输电线路覆冰的情况严重影响电力系统的可靠运行,现有的电力融冰均需停电进行,对系统影响较大。针对这个问题,分析交、直流不停电融冰的原理及可行性,提出一种新型的不停电直流融冰方法,对其电路结构和所需容量进行分析,并建立不停电融冰装置仿真模型,进行原理和功能验证。基于电力电子调压电路的不停电直流融冰装置具有融冰效率高且不影响线路供电的优点。

水冷电机的创新设计

简述对某钢厂特殊环境使用的电机采用水冷的设计方案,起到了很好的冷却效果,给钢厂带来可观的经济效益,对其它钢厂的类似应用也有借鉴意义。

现役交流XLPE电缆绝缘切片试样的交、直流耐压性能对比

为升级输电线路的传输能力,可将现役交流XLPE电缆线路改为直流运行,但仍缺乏改造方案设计的统一标准或规范。因而对1根投运7年的YJV22-8.7/10 kV-3×185 mm^2电缆进行绝缘环切,在相同条件下对切片试样进行交流及直流电压下的连续和逐级升压击穿试验。结果表明:升压速率为2 kV/s、0.5 kV/s、0.1 kV/s的连续升压击穿试验中,升压速率对试样的交流平均击穿场强影响很小,而对直流击穿场强影响较大;时间步长为2 min、6 min、15 min的逐级升压试验中,随着时间步长的增加,交流击穿场强略有降低,而直流击穿场强显著增大。随着电压施加时间的增加,交流击穿场强下降,而直流击穿场强反而增大,这导致直/交流击穿场强比值持续增大,由1.33增大至3.73。以击穿场强的95%置信下限值为基础,推导获得XLPE绝缘试样的交、直流1h击穿场强分别为89.50 kV/mm及247.55 kV/mm,而反幂定律中的电老化寿命指数拟和值为17和-11.51。在高压短时击穿试验范围内,试样的直流耐压性能随时间变化不符合传统电老化寿命定律,这可能与空间电荷效应的时间依赖性有关,需要后续研究进一步确认;同时也说明基于薄试样、高电压、短时间的击穿试验数据无法有效反映直流绝缘的长期电老化性能,不能直接用于XLPE直流电缆的绝缘结构设计。

电机改造 三种知名电机设计,性能极大提升

有时经过时间检验并证明行之有效的电机设计,可以得益于小的改变,也可以改善性能,或开辟新的应用可能性。这里有三个这样的例子,涉及三种类型非常不同的电机。一个是有刷直流电机设计,虽然其结构已经很紧凑,只是功率密度有拐点。

BIPV项目中逆变器的选型要求简析

通过理论模拟和已建电站实际数据的对比,对BIPV项目中逆变器的选用要求做了阐述,总结当前主流逆变器商相关产品的规格,提出了BIPV项目选用逆变器应考虑的因素。并结合实际案例,给出实测数据,对直流输入功率与逆变器额定功率的比例做出量化分析。

Design of a CMOS Current-Adjustable Charge-Pump Circuit Insensitive to Power Supply and Temperature

A CMOS charge-pump circuit with adjustable current is presented.A bandgap voltage reference,a low drop-out regulator,and a capacitive DC-DC voltage-booster are used to generate supply voltage for the current reference.This generated voltage is insensitive to the changes of external power supply voltage and temperature,while the current reference itself is insensitive to temperature.The circuit is designed in 0.18μm 1.8V standard digital CMOS process.The simulated results show that the performance of the circuit is satisfied.

Investigation on a vertical radial flow adsorber designed by a novel parallel connection method

Due to the increasing global demand for industrial gas, the development of large-scale cryogenic air separation systems has attracted considerable attention in recent years. Increasing the height of the adsorption bed in a vertical radial flow adsorber used in cryogenic air separation systems may efficiently increase the treatment capacity of the air in the adsorber. However, uniformity of the flow distribution of the air inside the adsorber would be deteriorated using the height-increasing method. In order to reduce the non-uniformity of the flow distribution caused by the excessive height of adsorption bed in a vertical radial flow adsorber, a novel parallel connection method is proposed in the present work. The experimental apparatus is designed and constructed; the Computational Fluid Dynamics(CFD) technique is used to develop a CFD-based model, which is used to analyze the flow distribution, the static pressure drop and the radial velocity in the newly designed adsorber. In addition, the geometric parameters of annular flow channels and the adsorption bed thickness of the upper unit in the parallelconnected vertical radial flow adsorber are optimized, so that the upper and lower adsorption units could be penetrated by air simultaneously. Comparisons are made between the height-increasing method and the parallel connection method with the same adsorber height. It is shown that using the parallel connection method could reduce the difference between the maximum and minimum radial static pressure drop by 86.2% and improve the uniformity by 80% compared with those of using the height-increasing method. The optimal thickness ratio of the upper and lower adsorption units is obtained as 0.966, in which case the upper and lower adsorption units could be penetrated by air simultaneously, so that the adsorbents in adsorption space could be used more efficiently.

Two types of coaxial self-balancing robots

Two types of coaxial self-balancing robots(CSBR)were proposed,one can be used as a mobile robot platform for parts transporting in unmanned factory or as an inspector in dangerous areas,and the other can be used as a personal transporter ridden in cities.Mechanical designing and control structures as well as control strategies were described and compared in order to get a general way to develop such robots.A state feedback controller and a fuzzy controller were designed for the robot using DC servo motors and the robot using torque motors,respectively.The experiments indicate that the robots can realize various desired operations smoothly and agilely at the velocity of 0.6 m/s with an operator of 65 kg.Furthermore,the robustness of the controllers is revealed since these controllers can stabilize the robot even with unknown external disturbances.

A novel design of power management integrated circuit with 90 plus efficiency used in AC/DC converter

Recently, resonant AC/DC converter has been accepted by the industry. However, the efficiency will be decreased at light load. So, a novel topology with critical controlling mode combined with resonant ones is proposed in this paper. The new topology can correspond to a 90 plus percent of power converting. So,a novel topology of an state of art integrated circuit, which can be used as power management circuit, has been designed based on the above new topology. A simulator which is specifically suitable for the power controller has been founded in this work and it has been used for the simulation of the novel architecture and the proposed integrated circuit.

Optimal design of auxiliary-teeth to solve circulation current reduction of permanent magnet linear synchronous motor

A discontinuity of magnetic circuits according to the end effect is generated in the permanent magnet linear synchronous motor （PMLSM）. Due to the unbalanced back electro-motive force （EMF） and impedance produced, unbalanced current is generated. The cireulatin8 current, which is caused by a decrease in the thrust, is generated by the unbalanced current. The optimal design of auxiliary-teeth at the end of the mover was carried out to solve the unbalance of phase by using design of experiment （DOE）, and compared with the basic model through finite element analysis （FEA）. As a result, the auxiliary-teeth model compensates for the decrease of thrust caused by the unbalanced phase. Also, this model is proven to reduce the detent force by the vibration and noise of the PMLSM and copper loss caused by the circulating current.

电网技术

《超导电力技术及其发展前景》；《超导电力技术的现状和发展趋势》；《远距离大容量特高压输电方案的分析与比较》；《特高压直流输电系统的基本设计要求》；《特高压输电试验线段及相关技术问题的探讨》。

火灾自动报警系统直流供电线路电压损失研究

工业企业的火灾自动报警系统确认火灾发生后,联动开启消防报警设备,警示、引导、组织现场作业人员疏散。直流24V电源供电线路延长后,线路上的电压损失导致直流24V电源供电消防报警设备出现了延迟动作、动作不稳定与拒动作的情况。本文结合工程举例,针对直流24V电源供电线路的电压损失,从直流供电线路设计与直流供电技改进行分析,并提出了工程解决方案。