Comparative Analysis of Stability and Electromagnetic Transient Studies for HVDC Multi-infeed Systems

In previous papers,the authors presented various electromagnetic transient(EMT)results for multi-infeed configurations focusing on possible effects from failures in one link being transferred to others in terms of induced commutation failures(CF),either during the fault events or after fault clearing in the recovery period.However,the AC system networks in these cases were represented by simplified equivalents.Many interesting conclusions arose from these publications without enabling a much-detailed analysis of overall system effects,which is only possible when the network is modeled in full detail.This paper aims at complementing and comparing simulation results on HVDC multi-infeed configurations using both dynamic stability and electromagnetic transient,while establishing some basic proposals for optimal use of both tools.It identifies the limitations from each type of study so that a comprehensive and useful analysis of HVDC multi-infeed systems can be obtained.

信息搜索策略对DCS排险绩效的影响——认知负荷的中介效应研究

为探究在集散式控制系统(distributed control system,DCS)危险排除过程中控制员不同信息搜索策略对排险任务绩效的影响及认知负荷的中介效应,基于虚拟现实技术、皮肤电采样和眼动追踪技术构建模拟DCS工控平台,招募20名相关专业被试参与模拟排险实验并对其认知负荷及排险绩效进行量化,使用眼动轨迹匹配法判断被试的信息搜索模式,研究认知负荷的中介效应及中介机理。研究结果表明:不同信息搜索策略会显著影响任务绩效;认知负荷对该影响的中介效应高达89.66%,表明信息搜索策略主要通过影响认知负荷来间接作用于排险任务绩效,认知负荷越高,任务绩效越低;逻辑系统搜索策略能通过高效图式匹配减少认知资源消耗,显著抑制认知负荷增长,任务绩效表现最佳;空间系统搜索较难抑制认知负荷,任务绩效较差;随机搜索被试认知负荷显著高于其他组,绩效表现最差;此外,不同认知负荷水平下被试的信息搜索策略没有明显转变倾向。研究结果可为DCS控制人员的考核和培训提供理论支撑。

一种基于磁集成的零输入电流纹波可扩展高增益DC-DC变换器

为减小传统DC-DC变换器中存在输入电流纹波大、开关管电压应力高和电压增益低等问题,提出一种基于磁集成的零输入电流纹波可扩展高增益DC-DC变换器。该变换器将磁集成技术与耦合电感纹波抑制技术结合,仅采用一个磁芯元件,既可消除输入电流纹波,又可获得高电压增益,并可形成一系列扩展单元,进一步提升电压增益,减小开关器件的电压应力。详细分析变换器的工作原理、稳态性能、增益扩展、磁集成原理和零输入电流纹波特性。为验证所提变换器相关理论的可行性,搭建一台140 W、24 V/400 V的实验样机,实验结果基本与理论分析一致。

基于谐振型DCX的部分功率调节技术研究综述

以LLC为代表的谐振变换器具有良好的软开关性能以及高效功率传输优势,但是开关频率的改变会使得谐振点发生偏移,效率显著降低,直流变压器(DC transformer, DCX)工作状态虽有利于实现效率优化,但却限制了系统的电压调节范围。此外,传统全功率传输会导致器件应力高,存在效率优化局限。近年来,部分功率传输由于低应力、高效率以及控制简单等优势得到广泛的应用,将谐振变换器与部分功率技术结合,强化优势互补,提高应用价值,已成为目前的研究热点。文中从部分功率传输概念和基本连接形式入手,对基于谐振型DCX的部分功率调节系统结构进行归纳分析,概括为单级式、两级式以及准两级式3种结构类型,讨论分析适用于不同种类结构的变换器拓扑以及控制方式;其次,对目前所实现的部分功率调节系统所能达到的性能指标进行归纳,并对传统两级级联式结构和另外3种部分功率调节结构的器件数量、电压增益以及工作效率进行综合分析对比;最后,对不同结构的优缺点和应用局限性进行总结,并对未来发展趋势展望,为后续研究提供一定的参考。

Hybrid Multi-Infeed Interaction Factor Calculation Method Considering Voltage Regulation Control Characteristics of Voltage Source Converter

Voltage source converter based high voltage direct current(VSC-HVDC)can participate in voltage regulation by flexible control to help maintain the voltage stability of the power grid.In order to quantitatively evaluate its influence on the voltage interaction between VSC-HVDC and line commutated converter based high voltage direct current(LCC-HVDC),this paper proposes a hybrid multi-infeed interaction factor(HMIIF)calculation method considering the voltage regulation control characteristics of VSC-HVDC.Firstly,for a hybrid multi-infeed high voltage direct current system,an additional equivalent operating admittance matrix is constructed to characterize HVDC equipment characteristics under small disturbance.Secondly,based on the characteristic curve between the reactive power and the voltage of a certain VSC-HVDC project,the additional equivalent operating admittance of VSC-HVDC is derived.The additional equivalent operating admittance matrix calculation method is proposed.Thirdly,the equivalent bus impedance matrix is obtained by modifying the alternating current(AC)system admittance matrix with the additional equivalent operating admittance matrix.On this basis,the HMIIF calculation method based on the equivalent bus impedance ratio is proposed.Finally,the effectiveness of the proposed method is verified in a hybrid dual-infeed high voltage direct current system constructed in Power Systems Computer Aided Design(PSCAD),and the influence of voltage regulation control on HMIIF is analyzed.

Multi-objective partition planning for multi-infeed HVDC system

The close proximity and the necessity of coordination between multiple high-voltage direct currents(HVDCs)raise the issue of grid partitioning in multi-infeed HVDC systems.A multi-objective partition strategy is proposed in this paper.Several types of relationships to be coordinated and complemented are analyzed and formulated using quantitative indices.According to the graph theory,the HVDC partition is transformed into a graph-cut problem and solved via the spectral clustering algorithm.Finally,the proposed method is validated for a practical multi-HVDC grid,confirming its feasibility and effectiveness.

HVDC Multi-infeed Analysis of the Brazilian Transmission System and Possible Mitigation Methods

The Brazilian transmission system is facing challenging problems with the distance between its generation areas and consumer centers that will be partly solved by the use of HVDC point-to-point systems.In the near future,the southeast subsystem will have a large amount of power injected through HVDC Systems in multiple points with relatively close electrical proximity.Therefore,the effects of a multi-infeed system are expected to influence the performance and operation of the network.Extensive studies and simulations will play an important role in determining the extension of the interactions among HVDC converters and determine if such interactions cause multiple commutation failures,thus disturbing the dynamic stability of the system.The use of CCC(Capacitor Commutated Converter)HVDC systems will also be assessed and is expected to diminish the need for a strong AC network(high short circuit level)and,therefore,mitigate multi-infeed interactions.The southeast subsystem of the Brazilian Power System currently has four LCC inverters,two of them belong to the Madeira power plant and the other two are from the Itaipu power plant.By the year 2024,four other HVDC systems will be arriving in the same region.This paper discusses the HVDC multi-infeed phenomena regarding the relevance of using synchronous machine models to represent important power plants and the application of mitigation methods regarding the 2020 network model,where six HVDC links will be present.

车辆称重数据远传DCS的系统设计

青岛某再生能源公司为焚烧生活垃圾并发电,建立了1套有2台地磅的车辆自动称重系统,2台计算机读取地磅称重仪表中的数据,通过企业局域网传输到数据库服务器。焚烧发电的控制系统为DCS。在厂区内数据库服务器与DCS相距1.5 km,距离较远。为方便企业远程监控和统计入厂的垃圾量,设计了车辆称重数据远传DCS的系统,由光纤电缆实现通信。基于Modbus-RTU协议,利用Visual basic 6.0在数据库服务器上开发与DCS通信的程序,提取数据库中称重记录的有用信息,通过RS485串口将其远传至DCS。目前该系统已经投入使用,实际运行平稳、可靠,为企业获得政府政策性资金支持提供了数据支持。

Research on the Voltage Interaction of Multi-Infeed HVDC System and Interaction Factor

In multi-infeed HVDC system, the interactions and influences between DC systems AC systems are complex as the electrical distances among DC converter stations which are relatively short. Multi-infeed interaction factor (MIIF) can effectively reflect the interaction among DC systems. The paper theoretically analyzes the impact factors of MIIF like the electrical distances between two DC converter stations and the equivalent impedance of the receiving end AC system. By applying the Kirchhoff’s current law on the inverter AC bus, the paper deduces the analytical expressions for MIIF. From the expression, it is clear how the equivalent impedance of AC system and coupling impedance can affect MIIF. PSCAD simulations validate the effectiveness and the correctness of the proposed expression and some useful conclusions are drawn.

核安全级DCS模拟量输入通道精度分析与设计

目前,国内核安全级DCS模拟量输入通道系统精度计算往往依托模拟量模块的精度数据开展系统级精度符合性计算,而未从设计层面具体分析影响模拟量通道精度的因素及设计方法。针对此问题,结合误差理论采用正向设计思路建立模拟量通道误差分析模型,通过通道关键器件选型和设计,实现通道精度的性能验证。结果表明,建立的误差模型较为准确,对核安全级DCS系统模拟量通道器件选型和设计具有指导意义。

一种RTK单历元整周模糊度快速确定MAXCOM-DC组合算法

本文针对传统的RTK单历元整周模糊度确定主辅频相关法(MAXCOM)观测卫星数增多导致单历元整周模糊度确定效率降低的问题,提出了一种单历元卫星分类筛选处理方法;将单历元所有卫星分类为参考星、主星和辅星,应用MAXCOM算法单历元确定主星整周模糊度和DC算法确定辅星整周模糊度,并提出了一种新的RTK单历元整周模糊度快速确定算法,称为MAXCOM-DC组合算法。对一组BDS-3实测数据900个连续观测历元进行动态定位试验,结果分析表明,MAXCOM-DC组合算法可避免在应用MAXCOM算法时辅星对主星整周模糊度搜索效率的影响,将主星数设为6时,单历元整周模糊度快速确定效率平均提升了98.5%,且单历元模糊度成功率达99.9%。本文为高采样数据单历元RTK快速定位提供了一种新算法。

18万t/a双氧水装置中集散控制系统DCS及兼容SIS与GDS应用

利用国内先进的浙大中控成熟的DCS为软硬件控制平台,将其应用到18万t/a双氧水生产装置中。在阐述系统应用方案的基础上,提出了技术关键点,详述了DCS系统在双氧水装置中控制系统的软、硬件构成和控制方案及组态等。DCS系统软硬件综合调试并投运,整个生产过程稳定、可靠、产品合格率较高,达到了预期设计目标。

Analysis of Commutation Failure in Multi-Infeed HVDC System under Different Load Models

HVDC technology has been widely used in modern power system. On one hand, HVDC has the advantages of economy, high efficiency and strong controllability. While on the other hand, it makes the dynamic characteristics of the power system becoming more and more complex. That puts forward a new challenge to system stability and raises new questions for power system simulation. This paper focuses on the interaction between AC and DC systems, especially the problem of commutation failure caused by AC system fault. Based on the data of China Southern Power Grid, this paper calculates the fault regions that may cause commutation failure and calculates the system critical clearance time under different load models, analyzes the impacts of different load models on commutation failure and the stability of AC/DC hybrid system.

水泥厂DCS系统Com电源短路故障及解决措施

DCS系统对水泥生产线的连续稳定运行起着重要作用,其中Com电源为数字量信号输入提供公共端电压,是确保DCS系统正常运作不可或缺的组件。Com电源短路故障是一种典型的DCS现场电气回路故障,多由现场输入的数字量信号回路对地短路引起,易导致DCS控制柜内Com电源保险熔断,进而造成数字量输入信号丢失。分析了速度开关与跑偏开关、限位开关以及直流电源导致的Com电源短路故障案例,通过采取禁止DCS系统Com电源直接通向生产现场、配置合适额定电流的断路器和增加隔离继电器等措施,有效实现了DCS控制柜内Com电源与生产现场的隔离,降低了DCS系统Com电源短路故障对水泥生产造成的影响,消除了故障隐患,提高了生产线运行的稳定性和连续性,为水泥生产的高效运营提供了坚实保障。

开关电源在安全级DCS中的应用失效研究

针对国产化安全级DCS平台的模拟量调理模块研制过程中,某型国产反激式开关电源曾多次偶发输入端短路失效问题。对该电源内部原理进行剖析,建立故障仿真模型。结合安全级DCS的实际应用场景,对该故障进行定位,明确国产某型反激式开关电源的失效机理,并给出对应的改进优化设计,有效提升国产化安全级DCS平台的可靠性及安全性。

Study on the Application of UHVDC Hierarchical Connection Mode to Multi-infeed HVDC System

随着我国特高压交直流技术的广泛应用，多馈入直流集中落入受端负荷中心将是未来我国电网发展所面临的重要问题。为从电网结构上有效解决多馈入直流系统的问题，提出一种特高压直流分层接入交流电网的方式。研究分层接入方式直流多馈入短路比计算方法的适用性，从理论上对比特高压直流不同接入方式下多馈入直流电网的系统特性，证明特高压直流分层接入方式有助于提高多馈入直流系统的电压支撑能力，引导潮流在1000kV与500kV层级间合理分布。结合国家电网规划，仿真验证了特高压直流分层接入方式的优势。

Synchronization Characterization of DC Microgrid Converter Output Voltage and Improved Adaptive Synchronization Control Methods

This paper deeply introduces a brand-new research method for the synchronous characteristics of DC microgrid bus voltage and an improved synchronous control strategy.This method mainly targets the problem of bus voltage oscillation caused by the bifurcation behavior of DC microgrid converters.Firstly,the article elaborately establishes a mathematical model of a single distributed power source with hierarchical control.On this basis,a smallworld network model that can better adapt to the topology structure of DC microgrids is further constructed.Then,a voltage synchronization analysis method based on the main stability function is proposed,and the synchronous characteristics of DC bus voltage are deeply studied by analyzing the size of the minimum non-zero eigenvalue.In view of the situation that the line coupling strength between distributed power sources is insufficient to achieve bus voltage synchronization,this paper innovatively proposes a new improved adaptive controller to effectively control voltage synchronization.And the convergence of the designed controller is strictly proved by using Lyapunov’s stability theorem.Finally,the effectiveness and feasibility of the designed controller in this paper are fully verified through detailed simulation experiments.After comparative analysis with the traditional adaptive controller,it is found that the newly designed controller can make the bus voltages of each distributed power source achieve synchronization more quickly,and is significantly superior to the traditional adaptive controller in terms of anti-interference performance.

火力发电厂DCS系统设计与PID控制器参数自整定的研究

现阶段,分散控制系统在国内燃煤电厂中得到了大量运用,凭借其卓越的功能优势,逐步代替了常规仪表,显著增强了机组的控制性能,实现了资源的恰当高效运用,把自动化和管理水平推向了新高度。DCS系统具备全面的数据采集、控制、监视、操作和计算能力,通过集中监视、分散控制的模式,显著增强了系统的可靠性与协同工作效率。历经多年迭代与完善,DCS已进化为功能分散、管理统一、构造分明的先进控制系统。此研究聚焦于火电厂的热控改造项目,深入剖析了DCS系统的特性,并基于小型电站锅炉的独特性,在保障系统安全与可靠的前提下,设计并开发了火电厂电脑监控系统。并且,对于PID控制器参数人工整定流程繁琐且时效性不足的问题,此研究对控制器参数的自整定算法实施了探讨。

火电厂热工自动化DCS控制系统的应用探析

火力发电厂是发电的重要场所,而热力系统又是整个发电过程的主体,为确保该系统的稳定和安全运行,需要对 DCS进行高效的控制和管理。为此,论文着重阐述了电站热力自动控制的基本原理,对其组成进行了剖析,并对其应用的优越性进行了探讨。在用电需求日益增加的今天,电站是国内用电的主体,其安全、高效的运行是人们关心的问题。而热工自动化 DCS控制系统是一项以计算机为终端,以互联网技术相连的高级控制技术,利用过程监测的方式,对火力发电厂的各类装置实施高效的控制,使整个生产过程的智能化和自动化控制成为可能,从而在电厂的热力过程中扮演着举足轻重的角色,同时也可以提高热能的利用率,降低运行费用,增强运行的安全。

基于DCS控制系统的工业自动化生产效率优化策略探讨

随着工业生产和自动化技术的飞跃,传统控制系统在提升生产效能及保障安全上遭遇瓶颈,本文聚焦于分布式控制系统(DCS),深入剖析其在推动工业自动化,增强生产力效率方面的策略与优势,文章揭示DCS的内在逻辑与结构特性,通过效能评估指标全面展示自动化生产模型,进一步,采用模拟对比方法,直观展现DCS较传统系统在提升生产效率上的显著优势,有力证明DCS在驱动工业生产效率提升中的核心作用,接着,我们使用案例研究的方式,挖掘了 DCS 控制系统对于提高生产效率具体实施的策略和方法,包括优化生产流程、减少设备故障率、快速响应生产需求等。最后,结合工业4.0背景,展望了 DCS控制系统在未来工业自动化生产中的更大发挥。本文的研究结果将有助于工业生产实践者更好地理解和应用DCS控制系统,从而提高工业自动化生产效率。