Radio frequency performance of an HVDC converter station AC Switchyard

The propagation of HVDC converter station generated RF signals through a 345 kV AC switchyard to injection on the AC lines has been examined. A one-line analytical model of the AC buses, yard equipment and converter transformers has been formulated based upon measured RF impedances. The calculations were compared with relative measurements of RF line currents as different filter banks were switched in and out. The results indicate that the model will be a promising means of analysis and mitigation of unwanted RF effects.Phase-to-phase coupling and extension of the approach to a three-line model have been considered but absolute RF measurements would be required prior to any definitive assessment.     

高压直流换流站载频噪声滤波器研究

在高压直流(HVDC)输电工程建设中,为了抑制高压直流换流站中的换流器在运行时对交直流输电线路出线产生的载波噪声干扰,有必要在线路中加装交直流载频噪声滤波器(PLC滤波器)。文章在分析了换流站噪声频谱和载波干扰限制值的前提下,扼要介绍了PLC滤波器工作原理,并结合贵广直流工程中肇庆换流站建设项目,阐述了实施的PLC滤波器设计内容,为今后直流国产化工程提供技术参考。     

高压直流换流站设备噪声相干分离技术

在高压直流换流站内很多声源的辐射噪声相互叠加,使得精确测量某一设备的噪声非常困难.在对换流站各设备噪声进行测试分析中,采用振-声相干分析分离方法对交流滤波场的噪声设备进行噪声频谱分离,并对相干分离方法中的分离精度和修正等问题进行讨论.作为实例,分离出了交流滤波场中单台电抗器的噪声和单台电容器的噪声,测量结果表明在对高压直流换流站设备噪声测量时,应用相干分离技术是一种直接可行的测量分析方法.     

直流输电换流站无功功率控制功能设计

直流输电系统无功功率控制的目的是保证交直流系统的无功交换满足系统要求,同时减轻换流站谐波对交直流系统及主设备的危害.实际工程中无功控制主要通过对交流滤波器组等无功单元的投切实现.需要考虑的因素有,交直流系统无功交换的平衡、交流系统稳态电压的限制、基本滤波条件的保证和滤波性能的优化、无功单元投切的均衡性、投切过程对系统的扰动等.直流输电系统的无功控制是一种多目标、多边界条件的复杂控制功能.按照实际工程的要求,对直流输电无功控制功能和策略的设计进行了全面的分析和介绍.     

直流输电换流站无功功率控制功能设计

直流输电系统无功功率控制的目的是保证交直流系统的无功交换满足系统要求,同时减轻换流站谐波对交直流系统及主设备的危害。实际工程中无功控制主要通过对交流滤波器组等无功单元的投切实现。需要考虑的因素有,交直流系统无功交换的平衡、交流系统稳态电压的限制、基本滤波条件的保证和滤波性能的优化、无功单元投切的均衡性、投切过程对系统的扰动等。直流输电系统的无功控制是一种多目标、多边界条件的复杂控制功能。按照实际工程的要求,对直流输电无功控制功能和策略的设计进行了全面的分析和介绍。     

A summary of North American HVDC converter station reliabilityspecifications

Reliability, availability, and maintainability (RAM) specifications that were issued for thyristor-based high-voltage DC (HVDC) converter stations in service in North America are summarized. Twenty project specifications are summarized. A detailed summary by project is shown with specific quantitative requirements categorized. Definitions of terms, representative design principles, and formulae used in calculating RAM parameters contained in existing reliability specifications are presented     

高压直流换流站技术现状与发展

在介绍高压直流换流站技术现状基础上,从电力电子器件、有源滤波器、光电流传感器、控制和保护系统、接线方式等几方面,探讨换流站技术的发展趋势。     

高压直流换流站的关键建站条件

高压直流输电在远距离、大容量输电中发挥着极其重要的作用,合理选择高压直流输电工程换流站站址是优化工程设计、降低工程投资、确保工程安全稳定运行的基础和保证。针对高压直流换流站建站条件不同于交流变电站的特点,就直流场设备污秽外绝缘、环境影响、大件运输和水源条件等方面因素,分析总结换流站站址选择应注意的关键技术要点。     

直流输电系统换流站保护适应性分析及优化方案研究

为防止直流输电系统换流站保护在区外故障下误动作,分析换流站保护的适应性,并提出不影响保护速动性与灵敏性的逆变站保护优化方案。利用最小电压前行波与电压反行波幅值积分比值构造逆变站区内外故障的识别判据,进而考虑逆变站保护与区外交流系统保护在时间上的协调配合,设计逆变站保护在区外故障下的防误动策略。基于PSCAD/EMTDC的仿真结果表明,所提保护优化方案不受故障位置、故障类型、故障初始角、过渡电阻以及噪声干扰的影响。     

A computer program for HVDC converter station RF noise calculations

HVDC converter station operations generate radio frequency (RF) electromagnetic (EM) noise which could interfere with adjacent communication and computer equipment, and carrier system operations. A generic Radio Frequency Computer Analysis Program (RAFCAP) for calculating the EM noise generated by valve ignition of a converter station has been developed as part of a larger project. The program calculates RF voltages, currents, complex power, ground level electric field strength and magnetic flux density in and around an HVDC converter station. The program requires the converter station network to be represented by frequency dependent impedance functions. Comparisons of calculated and measured values are given for an actual HVDC station to illustrate the validity of the program. RAFCAP is designed to be used by engineers for the purpose of calculating the RP noise produced by the igniting of HVDC converter valves     

龙泉换流站直流控制保护系统运行分析

由于运行时间较长以及性能存在一些缺陷,龙泉换流站直流控制保护系统近年来多次发生故障,对电网的运行带来了不利影响。对龙泉换流站直流控制保护系统近几年来的故障情况进行统计,对故障原因进行分析,并指出当前龙泉换流站直流控制保护系统运行维护工作存在的难题。根据分析结果,提出相应的技术改造方案。该技术改造方案不仅可以有效解决龙泉换流站直流控制保护系统存在的缺陷及问题,而且对其他高压直流输电工程的建设和运行维护工作也有较好的参考作用。     

Design of HVDC converter station equipment subject to severeseismic performance requirements

Severe seismic design levels were specified for the upgrading of the HVDC link between the principal islands of New Zealand. A number of novel design solutions were required to fulfil the performance requirements for the electric equipment. The purpose of this paper is to give an overview of design solutions and verification methods in the light of a specification stating performance criteria rather than specific allowables. Modifications to items of high voltage electrical equipment are described that reduce the seismic loads in the equipment and enable standard equipment to be used in areas of high seismicity. The seismic performance is further improved by controlling the eventual collapse mechanism     

Electromagnetic interference and shielding of valve hall in HVDC converter station

The electromagnetic interference (EMI) from the valve hall as an important consideration in the design of high voltage direct current (HVDC) converter stations is analyzed by electromagnetic field numerical method and measurements. By using moment method, the EMI filed strength level as well as radio interference level (RIL) of the valve hall during the normal operation are computed after an antenna model is built for the valve tower. According to the character of EMI obtained, the practical shielding measures for valve hall are discussed to satisfy the relative standards. The test results for the ±500 kV converter station show that both the numerical method and shielding technique used in this paper are practical.     

基于复杂网络理论的直流换流站选址

针对目前换流站位置的确定主要是从工程技术、经济和环境方面考虑且缺少理论分析的问题,从直流换流站选址对整个电力网络结构特性的影响入手,利用复杂网络理论分析不同的选址方案下整个电网所表现出的抗攻击性.通过对不同选址方式进行比较研究,找到电网结构上更坚强的换流站选址方案.得出以网络中度大的节点作为直流输电的连接点,将使得建成后的电网更具有无标度特性,即更坚强.并以IEEE14测试系统分析验证了所提方法的有效性.     

Flashover voltage characteristics of contaminated station insulators under temporary ac overvoltages in the ac system connected with a frequency converter station

According to the recent analysis results of temporary ac overvoltage in the ac system connected with a frequency converter station, large-magnitude over-voltages were confirmed to occur under some special system conditions. Most of the station insulators currently used cannot withstand such overvoltages according to an evaluation based on the data obtained earlier. The necessity of tests to be done to evaluate such performance more accurately was recognized. Both power frequency and switching impulse overvoltage flashover tests were made on contaminated insulators by the method well simulating the natural wetting condition. Switching impulse flashover voltage with the waveshape having a long wavefront time of 2 ms can be well correlated with the flashover voltage characteristics of temporary ac overvoltage. Higher flashover voltage characteristics were obtained by a clean fog test method compared with those obtained by equivalent fog test method.     

System for generating tidal power station with high-voltage frequency converter

The system for generating a tidal power station based on the orthogonal turbine and the high-voltage frequency converter is considered. The generating system operates at a variable rotation frequency of the hydrounit. Mathematical modeling of the operating modes is carried out. Oscillograms of currents and voltages of the generating system of the Kislogubskaya tidal power station with a capacity of 1500 kW are given.     

Insulation of HVDC converter stations

The results of an earlier survey on creepages and clearances in HVDC converter stations are expanded with data from a new survey and on-site interviews at several operating terminals. The changes which have accompanied the development of several additional HVDC transmission systems at higher voltages are illustrated with specific details on external insulation design. A summary of insulation performance and the effectiveness of different maintenance procedures are discussed     

HDVC converter station tests in the 0.1 to 5 MHz frequency

Radiofrequency (RF) quantities in and around an HVDC converter station were measured in the 0.1 to 5 MHz frequency range to provide baseline data for the formulation of a means to predict the RF performance of such stations. Special records were taken at selected points and traverses in the station. The RF voltages of buses were measured and ground-level electric field strength and magnetic flux density measurements were conducted. To obtain the maximum amount of information about a converter pole when it is considered as an RF source, swept frequency (broadband) measurements were selected as the prime records for the analysis of pole performance. The principal source of the RF noise is the firing valve. Additional impedance versus frequency measurements of station components were also performed for undertaking RF modeling of the converter station     

A linearised small-signal model of an HVDC converter for harmonic calculation

In this paper a new method is presented for calculation of the harmonics in the ac current and dc voltage of a six-pulse HVDC converter. Instead of fast Fourier transform, FFT, the Fourier series is used in this method. The HVDC converter is represented by a linearised small-signal model in mixed time- frequency domain in which the effects of on and off states resistances, forward voltage drop, and snubber circuits of the thyristors are taken into account. RL series circuits are used for modeling of the converter transformer and ac system. To validate the method a comparison is made with PSCAD/EMTDC time domain simulation program.     

共换流站双回直流输电工程直流控制系统优化研究

针对溪洛渡右岸电站送电广东直流工程两回直流共起落点、共换流站、直流线路同塔双回并架的工程特点,从系统运行方式、直流控制系统的结构与功能配置等方面和单回直流工程进行分析、比较,在此基础上,进一步研究了双回直流控制系统的分层结构、功能配置以及系统协调控制的原则、策略等。提出了双回直流工程控制系统的硬件配置方案,最终给出了新增两个双极间协调控制功能,采取备用功能和回间隔离等直流控制系统的优化措施。配置方案和优化措施已在实际工程得到应用。该研究对后续该类工程控制保护系统的设计、施工、运行维护方面具有一定的指导意义。