【作者】 程利军；

【导师】 杨奇逊；

【作者基本信息】 华北电力（北京）大学 ， 电力系统及其自动化， 2001， 博士

【摘要】 微机继电保护装置工作在电磁环境极其恶劣的变电站中，其电磁兼容水平、可靠性等因素对电力系统的安全、稳定极其重要。一方面，微机保护装置已经突破常规继电器的概念，正向计算机化，网络化，智能化，保护、控制、测量和数据通信一体化发展，使计算机硬件、软件设计越来越复杂，致使装置对电磁骚扰具有更明显的敏感性和脆弱性；另一方面，变电站综合自动化已完成“面向间隔(对象)设计”的重大转变，“保护下放”模式逐渐被电力系统认可并加以推广，使位于开关场内的继电保护装置比主控制室内继电保护所遭受的传导性骚扰及辐射性骚扰强许多，微机保护装置的电磁兼容问题变得十分突出。 快速瞬变脉冲群骚扰由于上升时间快、持续时间短、能量低、重复频率高对微机继电保护装置的影响是显著的。本文系统地研究了瞬变骚扰源的机理、特性以及瞬变骚扰在微机保护装置内部的传输途径；定量地分析了瞬变骚扰对微机继电保护各个组成部分的影响，并提出微机保护装置抑制瞬变骚扰的措施。论文主要研究的内容及取得的成果有： 1 提出快速瞬变脉冲群的中心频率为70MHz。指出快速瞬变脉冲群骚扰对微机保护装置的影响以“传导”方式为主，并建立“电路”模型。提出一种以示波器为辅助工具，定量分析微机继电保护系统抗扰度的方法，摆脱了“盲目”的探索，使微机保护装置抗扰度研究进入了“可视化”阶段。 2 提出微机继电保护系统的辅助激励量端口、输入激励量端口、输入端口、外壳端口、输出端口、通讯端口的高频瞬变骚扰传输模型及机理，并用大量试验结果来验证这些模型。指出直流回路、交流电流/电压回路、通信回路及开关量输入回路是快速瞬变脉冲群骚扰进入微机保护装置内部并影响数字系统的主要途径。微机保护装置硬件设计时，对这些回路必须采取抑制措施。 3 提出在5V、+/-15V、24V弱电电源回路中，通过增加适用于弱电系统滤波器、EMI片状滤波器以及在弱电电源端加入电容器等措施，可以有效地抑制瞬变骚扰对数字系统的影响。指出铁氧体磁环/磁珠对交流电流/电压回路、通信回路的共模瞬变骚扰有较好的抑制作用。此外通过改变原副方绕组的布置以及采用双层屏蔽等技术减小辅助变流器/变压器原、副方绕组的耦合电容也能够抑制共模瞬变骚扰。这些措施已经应用在四方公司新一代微机保护装置中，取得了较好的效果。 4 指出微机保护装置的直流电源、通信等回路需要设置抑制浪涌冲击的过电压保护器件，如气体放电管、压敏电阻、抑制二极管等。 5 提出在快速瞬变骚扰的作用下，光耦器件将产生“瞬时饱和”现象，并提出解决方案。瞬变骚扰从直流电源、交流电流、电压端口施加时，即使开关量输入没有任何信号，光耦器件的输出一直存在电平跌落、再恢复的过程，该过程伴随着每一个瞬变脉冲，相当于光耦器件已经导通，影响开关量输入的正确性。同时，用于其它回路的光耦器件，如串行口、开关量输出等回路也存在上述现象。光耦器件“瞬时饱和”现象是普遍存在的，对微机保护装置影响较大。 6 研究单片机芯片内异步串行通信(UART)的通信机理，发现快速瞬变脉冲群骚申请华北电力大学工学博士学位 扰对异步串行通信系统影响较大，不能保证信息的正确传输，因此这种通信方 式不能很好地满足快速、精确的实时控制的要求。 7 解决了四方公司微机保护装置电磁兼容方面的疑难问题： CSL164B微机线路保护由于软件、硬件的原因造成“采样报告”出错； CSL216微机线路保护由于串行通信由于处理不当致使保护动作软压板被 改写，造成故障时保护拒动； 瞬变骚扰致使串行口发送、接收出错，造成分布式微机母线保护装置“通信 异常”； 由于信号继电器绝缘水平较差、扁平电缆信号布置不当以及接线出错，造成 四方公司微机保护装置绝缘性能较差。更多还原

【Abstract】 The microprocessor based prot8ctive reIay works in serious eIectromagneticenvironment of the substations. Its immunity IeveI and reliabiIity is moreimportant to the safe and reliable operation of the power systems. Themicroprocessor based prot8Ctive relay has exceeded the concept of the traditionaIproteCtive reIay. The trends for the microprocessor based protective relay are thecomputerization, artilicial intelligence, netWorking, the integration of protective relay,control & measuring and data communication technologies. The computer hardwareand software design has been more compIicated. On the Dther hand, theBay-Oriented Design techniques have wideIy been adopted in power systems. TheconduCted and radiat6d distuthance to the proteCtive reIay decentraIized instaltationin switChyard are much more int6nse. Above aII, the microprocessor based proteCtiverelay is more susceptibIe and frangibIe to eIeCtromagnetic compatibiIity.The eleCtrical fast transient l burst (EFT) is a f8st, repetitive waveforrn withenergy content only on the order of tens to hundreds of milIijoules. The EFTs mayhave infIuence on the dependabiIity and security of the numericaI prot6ctions, andcause the apparatus under functioning or over funCtioning. ln this paper, theinterf6rence coupling mechanisms and the propagation path and the methods forensuring EMC have been anaIyzed.Studying the frequency spectra of the EFT wavefOrm, we can conclude that thetransient below 100MHz is the main parts. When the EFTS enter the microprocessorbased pfoteCtive reIay, the conduCted coupling diSturbance is main, and theconduCted circuit modeIs are established. The digitaI oscilloscope is empIoyed toanaIyze the immunity of the microprocessor based proteCtive reIay quantitativeIy asan auxiIiary tooI. This method makes the EMC research visibIe.The circuit modeIs that the EFTs propagation path through power supply port,input port, encIosure port, output port, functional earth port and communication portof the microprocessor based protective reIay are discribed. A great deaI of tests showthat the power suppIy circuit, the AC current and voItage circuit, communicationand the binary input circuit are the main routes for transient.The filter, three-terminal chip capacitor and the capacitor can be used in the lowvoItage power suppIy circuit(5V. +l-15V and 24V) to restrain the EFTs affecting thedigital system. The ferrites can be used in AC current and voltage circuit andcommunication circuit, because they absorb the transient energy effectively.Furthermore, changing the arrangement of the primary winding coil and the secondarywinding coil and using the double screen fOr auxiliary current and voItage transfOrmercan be adopted to ’induce the common mode transient. These methods abovementioned have been successfully applied in the newly microprocessor basedprotective relay of Sifang Coporation, and have been proved better.A particuIar probiem with opto-coupIers is found that high leveI, but short transientcan coupie into the base of the receiving phototransistor and cause its saturation. lt isca1Ied "Transient Saturation". This saturation wiII effect on opto-couplers’ isolation anddigitaI inputs’ vaIidity The solution for opto-couplers’ saturation is put fotward in thispaper.lt is pointed out that layout the transient suppressors for surges in power suppIypQrt and communication signaI line of protective reIay, such as varistors(voItagedependant resistors),zeners and spark gaps(gas discharge tubes) is necessary.The asynchronous seriaI I/O (UART) mode in the embedded microprocessor isdiscussed. lt is proved that the messages through the UART interface are not vaIidityduring EFT test. So the asynchronous seriaI l/O (UART) mechanism is not satisfied tothe demand for high speed, accurate and reaI-time controI applications, especia[ly thenumerical busbar protection.Many EMC problems in the numericaI protection apparatus of Si fang Corporationhave been soIved in this paper, and many heIpful concIusions for irnproving the EMCleveI of the numericaI protections have been dra更多还原