Design of Non-contact On-load Automatic Regulating Voltage Transformer

At present, an automatic-mechanic contact tap-changer is widely used in power system, but it can not frequently operate. In addition, arc will occur when the switch changes. In order to solve these two problems, this paper presented an automatic on-load voltage-regulating distributing transformer which employed non-contact solid-state relay as tap-changer, and mainly introduced its structure, basic principal, design method of each key link and experimental results. Laboratory simulation experiments informed that the scheme was feasible. It was a smooth and effective experiment device, which was practical in application.

Online Fault Monitoring of On-Load Tap-Changer Based on Voiceprint Detection

The continuous operation of On-Load Tap-Changers (OLTC) is essential for maintaining stable voltage levels in power transmission and distribution systems. Timely fault detection in OLTC is essential for preventing major failures and ensuring the reliability of the electrical grid. This research paper proposes an innovative approach that combines voiceprint detection using MATLAB analysis for online fault monitoring of OLTC. By leveraging advanced signal processing techniques and machine learning algorithms in MATLAB, the proposed method accurately detects faults in OLTC, providing real-time monitoring and proactive maintenance strategies.

Research on the Differential Protection Algorithm of Multi-Tap Special Transformer

Compared with conventional transformers, the rectiformer is special in connection mode, which is multi-tap and not equipped with the differential protection. In this paper, the differential protection algorithm for Multi-tap special transformer was derived. The regulating methods for the rectiformer were studied first, and then the rectiformer model of one electrolytic aluminium plant was built by PSCAD/EMTDC, characteristics of the rectiformer bank were also analyzed. The algorithm was derived on the basis of the per-unit system, and the processing methods of the regulating transformer’s tap position information were proposed. Finally, a contrast of differential protection algorithm between the multi-tap special transformer and the conventional transformer was made.

State coordinated voltage control in an active distribution network with on-load tap changers and photovoltaic systems

Decreasing costs and favorable policies have resulted in increased penetration of solar photovoltaic(PV)power generation in distribution networks.As the PV systems penetration is likely to increase in the future,utilizing the reactive power capability of PV inverters to mitigate voltage deviations is being promoted.In recent years,droop control of inverter-based distributed energy resources has emerged as an essential tool for use in this study.The participation of PV systems in voltage regulation and its coordination with existing controllers,such as on-load tap changers,is paramount for controlling the voltage within specified limits.In this work,control strategies are presented that can be coordinated with the existing controls in a distributed manner.The effectiveness of the proposed method was demonstrated through simulation results on a distribution system.

State Space Modeling and Implementation of a New Transformer Based Multilevel Inverter Topology with Reduced Switch Count

This paper presents a new transformer based multilevel inverter, with a novel pulse width modulation scheme to achieve seven-level inverter output voltage. The proposed inverter switching pattern consists of three fundamental frequency sinusoidal reference signals with an offset value, and one high frequency triangular carrier signal. This switching scheme has been implemented using an 8-bit Xilinx SPARTAN-3E field programmable gate array based controller. In addition, the state space model of the proposed inverter is developed. The significant features of the proposed topology are: reduction of the power switch count and the gate drive power supply unit, the provision of a galvanic isolation between load and sources by a centre tap transformer. An exhaustive comparison has been made of the existing multilevel inverter topologies and the proposed topology. The performances of the proposed topology with resistive, resistive-inductive loads are simulated in a MATLAB environment and validated experimentally on a laboratory prototype.

基于ETAP仿真的国外发电厂主变压器有载调压分接头选择研究

发电厂主变压器分接头的选择研究、接入点的电压水平的合理确定,对宏观系统电压的调整以及对区域无功电力的平衡具有重要的意义。国内工程主变压器分接头选择已很成熟,但国外工程还需根据外方特殊要求合理选择变压器分接头。以某国外工程为例,应用ETAP软件进行了变压器分接头选择计算,主变压器留有备用分接头,变比选择为(225±10×1.5%)/20,计算结果可以很好地满足母线电压和发电机组出力的要求。

拟南芥 CPK10双元 TAP 载体的构建及原生质体表达

为了研究拟南芥CPK10发挥功能的分子机理,通过PCR扩增克隆了CPK10基因,将该基因连接到带有FLAG和HA标签的双元串联亲和层析载体上,构建成p CM1307-3FLAG-3HA-CPK10植物表达载体,进而通过PEG介导转化拟南芥野生型原生质体,表达约10 h,通过Western Blotting检测融合有FLAG和HA标签的CPK10蛋白的表达情况,结果显示,可以分别利用FLAG抗体和HA抗体特异检测到CPK10蛋白的条带。融合蛋白的成功表达,为进一步通过串联亲和纯化技术(TAP)筛选CPK10的互作蛋白奠定基础。

On the Performance Analysis of One Tap Equalizers in Oversampled OFDM Systems

Oversampling is commonly encountered in orthogonal frequency division multiplexing (OFDM) systems to ease various performance characteristics. In this paper, we investigate the performance and complexity of one tap zero-forcing (ZF) and minimum mean-square error (MMSE) equalizers in oversampled OFDM systems. Theoretical analysis and simulation results show that oversampling not only reduces the noise at equalizer output but also helps mitigate ill effects of spectral nulls. One tap equalizers therefore yield improved symbol-error-rate (SER) performance with the increase in oversampling rate, but at the expense of increased system bandwidth and modest complexity requirements.

基于ETAP仿真的大型储能电站计算分析与设计优化

介绍大连某全钒液流电池储能电站(100MW)应用ETAP软件进行潮流计算、短路电流计算、谐波仿真计算,对储能电站进行系统设计:通过潮流计算,合理选择各级变压器容量、阻抗、变比、变压器分接头,潮流分析模块还可以进行无功平衡分析;进行最大短路电流计算,合理选择主要导体和设备;对整个工程进行ETAP谐波仿真后,更合理地设计储能电站的厂用电系统接线,减少谐波污染。

双芯移相变压器在主动配电网电压和潮流调控中的应用分析

双芯移相变压器可以有效控制线路电压和潮流,优化潮流分布,提高电网电能质量。针对分布式电源的高比例接入造成的主动配电网电压波动和偏差问题,以及对潮流大小、方向和均衡度的影响,文章研究了双芯移相变压器的拓扑结构和工作原理;然后分析了串联变压器和励磁变压器的具体结构和作用,梳理了移相变压器分别应用于电压调节和潮流控制时的档位控制策略;最后基于MATLAB/Simulink建立了详细的仿真模型,研究了双芯移相变压器的电压调节效果,并对双线路并联、两路电源并联供电、多路电源并联供电三种应用场景下的潮流控制效果作了比较。仿真结果表明,双芯移相变压器可以在有限的档位内将线路电压控制在允许范围;与双线路并联、多路电源并联供电应用场景相比,两路电源并联供电时的潮流均衡效果最好,潮流偏差最小,本研究为双芯移相变压器的广泛应用提供了参考。

基于有载分接开关通用动力学模型的电气时序特性分析

有载分接开关是特高压直流输电工程中换流变压器的重要部件,其结构复杂且有严格的切换动作时序要求,电气时序不合理极易产生电弧烧蚀失效等问题,进而影响输电工程的安全运行。针对有载分接开关动力学模型构建缺乏通用性与电气时序特性影响规律不明晰问题,基于能量法提出了有载分接开关通用切换动力学模型构建方法,研究了切换过程中能量转换关系与各部分能量损耗计算方法;以一类有载分接开关为例,将其通用动力学模型与软件仿真结果对比表明,两者角速度曲线相吻合,电气切换时序相对误差均小于2.01%,验证了通用模型构建方法的正确性;其次,通过与实验进行对比,发现两者角位移与角速度曲线趋势一致;此外,研究了有载分接开关系统关键参数对电气切换特性影响规律,整体切换时间随着驱动力矩增大而减小,随着转动惯量增大而增大,呈指数关系,且受主触头机构(main contact,MC)切换位置影响较显著;关键电气时序受驱动力矩、转动惯量影响较大,且真空触头机构V1、V2切换时间与V1、V2切换位置呈线性关系,V1-过渡触头机构Z1间隔时间与V2-过渡触头机构Z2间隔时间同时受V1、Z1与V2、Z2切换位置调控。

基于频率响应分析的变压器分接开关故障诊断方法

为了准确诊断电力变压器分接开关故障类型,提出一种基于频率响应分析的变压器分接开关故障诊断方法;利用Simulink仿真工具提出并设计电气等效电路模型,针对结焦、点蚀2种常见分接开关故障,利用频率响应分析特征曲线分析变压器分接开关的物理故障敏感性,对开路端对端、短路端对端和绕组间电感和电容进行实验测试。结果表明:使用频率响应分析测量值可以准确识别变压器分接开关触头结焦、点蚀故障,结焦会对利用开路的电路端到端、短路端到端、电容绕组和电感绕组4种不同测量配置得出的频率响应分析特征造成显著影响,但点蚀故障的影响仅在电感绕组配置中出现。

混合型有载调压变压器拓扑结构及控制策略研究

针对传统有载调压变压器存在功能单一、动态特性差等问题,结合工频变压器高效可靠和电力电子变换器易于控制的优点,提出了一种混合型有载调压变压器拓扑结构。通过增加背靠背变换器,并设计相应控制策略,实现了有载调压变压器连续调压和无功补偿的功能;提出一种串联电压补偿方法,实现了对负载的故障保护。最后,分别基于MATLAB仿真软件和实验平台搭建了混合型有载调压变压器实验模型,仿真和实验结果验证了所提拓扑结构和控制策略的正确性和有效性。

特高压直流换流变压器分接头自动再同步控制策略

特高压输电技术承载着新能源远距离输送的重要任务,是助力“双碳目标”达成的有力支撑,然而,受新能源上网功率波动的影响,特高压直流输电系统中送电端换流变压器分接头动作次数频繁,严重影响换流变压器使用寿命。为减少分接头动作次数,文中建立了直流输电电流、晶闸管触发角及分接头档位等关键影响因子之间的数学关系,在分析现有分接头控制策略不足的基础上,提出面向特高压直流输电系统的同极换流变压器分接头自动再同步控制策略。以雁淮特高压直流输电系统为例,通过数学推导及MATLAB/Simulink仿真,对传统策略和改进策略进行对比。结果表明所提策略有效降低分接头动作次数,提升特高压直流输电系统运行质效。

基于Transformer的有载分接开关故障诊断研究

针对传统网络捕捉有载分接开关声纹特征之间联系不充分导致故障诊断准确率低的问题,提出了基于Transformer神经网络的有载分接开关故障诊断方法。首先采用梅尔频率倒谱系数提取有载分接开关声纹特征,以降低有载分接开关声纹样本的数据维度。然后利用Transformer充分捕捉声纹特征之间的联系并实现有载分接开关故障诊断。实验结果表明,基于Transformer对有载分接开关传动轴松动、触头磨损、卡涩和连挡故障诊断的准确率高达97.5%,并一定程度缩短了诊断的时间。

考虑配电变压器变比误差的配电网多断面联合状态估计

量测配置薄弱一直是困扰配电网状态估计精度的重要原因。台区智能融合终端的广泛应用丰富了量测配置,并使配电网状态估计范围延伸到配电变压器低压侧,客观上对配电变压器参数的准确性提出了更高的要求。配电变压器数量多,参数维护工作量大,参数准确性目前仍难以得到有效保证,变比参数错误是导致配电网状态估计精度低的关键因素。利用配电变压器普遍采用无载调压抽头、变比变化频率较低的特点,提出考虑配电变压器变比误差的配电网多断面联合状态估计方法。通过建立直角坐标系下基于二次型的配电网多断面联合状态估计模型,并采用正交变换法求解,实现对配电变压器变比的准确估计。IEEE 33节点修正系统及某实际配电网的算例分析结果表明,所提方法能够对配电变压器变比给出较为准确的估计,有助于及时发现并修正变比参数错误,减轻参数维护工作量,提升配电网状态估计精度。

Erosion Characteristics of Oil-immersed On-load Tap Changer Contacts Under Varying Contact Speeds and Pressures

With the growing demand for precise voltage adjustment and reactive regulation,the frequent operation of on-load tap changers(OLTCs)in oil-immersed systems has led to increased erosion of switch contacts by arcs during the switching process.This erosion causes significant wear on the contacts,thereby reducing their lifespan.Therefore,the present study aims to investigate the behavior and mechanism of arc erosion on contact surfaces in oil-immersed OLTCs.To achieve this,a self-designed friction and wear test device for OLTC contacts was utilized to conduct experiments at various sliding speeds and contact pressures.Additionally,finite element analysis was employed to validate the experimental results regarding the influence of sliding speed on arc energy.The surface morphology of the contacts was observed using an optical microscope.The findings revealed that as the sliding speed increased,the arc energy,arc initiation rate,and contact resistance initially exhibited an upward trend,then decreased,and eventually increased again.The minimum values were observed at a sliding speed of 90 mm/s.Moreover,the arc energy,arc initiation rate,and contact resistance decreased gradually as the contact pressure increased.After reaching a contact pressure of 1.5 N,the variation in the arc energy stabilized.At lower contact pressures,arc erosion dominated the wear on the contact surface.However,at higher contact pressures,the wear transitioned from predominantly arc erosion to a combination of mechanical wear and arc erosion.In summary,experimental and analytical investigations provided insights into the effects of sliding speed and contact pressure on the behavior of arc erosion,contact resistance,and surface damage of OLTC contacts in oil-immersed systems.

基于优化TQWT及孪生SVM的有载分接开关机械故障诊断

为进一步提高有载分接开关(on-load tap changer,OLTC)机械状态监测的准确性,文中基于优化品质因数可调小波变换(tunable quality wavelet transform,TQWT)对OLTC切换过程中的振动信号进行了分析。即使用人工鱼群算法(artificial fish swarm algorithm,AFSA)基于分解余量与整体正交系数研究了TQWT的优化分解方法,计算得到了OLTC振动信号的多个子序列,构建了基于优化孪生支持向量机(twin support vector machine,TWSVM)的OLTC机械故障诊断模型。对某CM型OLTC正常与典型机械故障下振动信号的分析结果表明,所提优化TQWT分解方法有效提高了OLTC振动信号分解结果的准确性。相对于其他诊断模型,所构建AFSA-TWSVM的OLTC机械故障诊断模型分类效果好且收敛速度更快。

高压输变电变压器真空有载分接开关的运维分析和检修策略

本文中作者分析了变压器真空有载分接开关的技术优势、技术难度和运行问题。基于有载分接开关运行中的问题,提出了真空有载开关维护检修的必要性和检修策略,可为今后的研究工作提供一定的指导和借鉴。