【作者】 王玉峰；

【导师】 邹积岩； 廖敏夫；

【作者基本信息】 大连理工大学 ， 电机与电器， 2007， 博士

【摘要】 在电力系统中，电快速瞬变脉冲群具有上升时间和持续时间短、幅值和重复频率高等特点，其对微机保护装置的干扰长期以来难以克服。我国微机保护装置抗电快速瞬变脉冲群的研究工作刚刚起步，主要集中在如何进行抑制的工程实践上，对电快速瞬变脉冲群的形成、耦合和作用机理缺乏深入的研究。本文结合电磁兼容三要素，研究电力系统中电快速瞬变脉冲群的形成机理和耦合机理以及通过试验研究微机保护装置抗电快速瞬变脉冲群的措施。在电快速瞬变脉冲群形成机理方面首先研究了开关操作时形成电快速瞬变脉冲群的过程。然后，在电力系统电磁暂态仿真软件ATP中建立隔离开关电弧重燃和熄灭的模型，仿真电力系统一次回路中隔离开关切感性负载和容性负载时引起的电快速瞬变脉冲群，进而分析了采取MOV(金属氧化物避雷器)保护、RC保护和相控开关技术等主动防护措施抑制一次回路中的电快速瞬变脉冲群的效果。在二次回路中通过试验研究发现了出口继电器线圈上耦合的电快速瞬变脉冲群电压对微机保护装置的直流电源的影响，进而建立了出口继电器瞬变电路模型。在电磁场有限元仿真软件ANSOFT中，通过仿真研究还得出可减弱出口继电器触点产生的电快速瞬变脉冲群耦合到线圈的电磁屏蔽措施。在电快速瞬变脉冲群耦合机理方面分析了一次回路中形成的电快速瞬变脉冲群耦合到微机保护装置的主要途径，并制定具体的电磁隔离措施：1)在ANSOFT中建立开关柜模型，通过仿真研究如何减弱电快速瞬变脉冲群引起的瞬态电磁场在微机保护装置的外壳上感应出的干扰电压和干扰电流。2)提出应选择转移阻抗小的二次电缆与微机保护装置相连，并且采取多层屏蔽，用增大屏蔽层阻抗的方法减小耦合到屏蔽层的电流。3)在EMPT-ATP中建立电力互感器的电磁单元模型，仿真研究抑制电快速瞬变脉冲群通过电磁式电力互感器从一次回路耦合到二次侧微机保护装置的措施。目前电磁干扰源的量化分析和耦合途径的建模分析研究还不够成熟，本文提出一种应用数据挖掘技术预测与分析变电站中瞬态电磁环境的算法。根据数据挖掘算法生成的评估模型，可以制定电磁干扰抑制策略，改善变电站中的电磁环境。并且依据预测结果，采取空间隔离措施将微机保护装置安装在电磁干扰比较小的位置。在微机保护装置抗电快速瞬变脉冲群能力的研究方面，首先分析了电快速瞬变脉冲群干扰微机保护装置使其出现逻辑混乱、显示不正常、程序跑飞、甚至误动等故障的原因。然后，通过给微机保护装置的外部端口进行电快速瞬变脉冲群抗扰度试验提出并验证了改进的分布式电源、串联铁氧体磁珠、电磁干扰滤波器和并联瞬态抑制二极管等措施。最后，通过使用本文研制的高压重频脉冲电源和组合波发生器，对电站真空度在线监测系统进行电磁抗扰度试验，研究提高其抗电快速瞬变脉冲群和浪涌的能力。目前，国内生产电磁抗扰度试验用信号发生器的厂家不多，主要依赖进口，价格十分昂贵。本文按照国际标准IEC61000-4-4和国家标准GB／T17626.4的要求，设计并研制了一台以开关电源作高压直流电源，以氢闸流管作主电路开关价格低廉的高压重频脉冲电源样机。按照国际标准IEC61000-4-5和国家标准GB／T17626.5的要求，还设计和研制了一台以三电极场畸变开关作主电路开关的成本低廉的组合波发生器样机。测量结果表明，本文研制的高压重频脉冲电源和组合波发生器输出的电磁干扰信号可用于电快速瞬变脉冲群抗扰度试验和浪涌抗扰度试验。更多还原

【Abstract】 EFT/B (Electrical Fast Transient Burst) always interferes with microprocessor protection devices in power system, because it has such features as short rise time, short duration, high amplitude and high repetition rate. Study of anti-jamming of EFT/B is at the beginning in China and concentrated mainly on the Countermeasures in practice. Investigations on the mechanisms of EFT/B forming, coupling and working are still in great demand. Based on the three factors of EMC (Electromagnetic Compatibility), EFT/B’s forming and coupling mechanism are discussed in this paper. And Countermeasures on anti-jamming of EFT/B for microprocessor protection devices are studied through experiments.With regard to EFT/B’s forming mechanism, the process of forming EFT/B caused by a switch operation is studied at first. Then, the restrike and extinction model of a disconnecting switch’s arc is built with EMPT-ATP codes. EFT/B caused by a disconnecting switch’s cutting off inductive or capacitive load is simulated in the primary circuit of power system. Countermeasures of MOV (Metal Oxide Varistor), RC and phase-control switch technology are used to inhibit the primary circuit EFT/B. EFT/B’s forming mechanism in the secondary circuit is studied through experiments. It’s discovered that EFT/B coupled into a relay’s coil interferes with DC power supply of microprocessor protection devices badly. And a model of output relay is built. The method of electromagnetic shielding is simulated to cut off EFT/B’s path from the relay’s contact to its coil with ANSOFT codes.With regard to EFT/B’s coupling mechanism, coupling path of EFT/B in the primary circuit is analyzed and the electromagnetic isolation measures are proposed as follows. Firstly, a model of the switch cabinet is built associated with ANSOFT. Countermeasures to attenuate voltage and current disturbance induced by EFT/B are simulated. Secondly, secondary cables with low transfer impedance are proposed to connect with microprocessor protection devices. Multi-layer electromagnetic shielding and high impedance of shielding layer are proposed to attenuate current induced in the shielding layer. Thirdly, an electromagnetic unit model of transformer is built associated with EMTP-ATP. Countermeasures are simulated to prohibit EFT/B from the primary circuit to the microprocessor protection device through electric voltage and current transformer.The quantitive study of EMI (Electromagnetic Interference) source and its coupling path is still in its primary state now. The algorithm based on data mining technology is first proposed to predict and analyze the electromagnetic environment of a substation. The strategy of anti-jamming measures can be established according to the appraisal model generated from data mining algorithm. Electromagnetic environment can be improved in substations. Besides, the microprocessor protection device can be fixed in the place where the disturbance is at minimum according to the prediction results.With regard to anti-jamming EFT/B of microprocessor protection devices, the reasons for logic confusion, program mistake, display error and malfunction are analyzed when EFT/B interferes with the microprocessor protection device at first. Then, the microprocessor protection device is under EFT/B immunity test. Improved distribution power supply, ferrite core, EMI filter and transient voltage suppressor can be used in the microprocessor protection device to control EFT/B through experiments. Lastly, EFT/B and surge immunity tests are performed on a vacuum on-line condition monitoring system made in laboratory with the EFT/B and surge generators developed in this paper. The system’s immunity level is improved with the Countermeasures.At present, disturbance signal generators for EMC immunity test are mainly imported and are very expensive. An EFT/B generator is designed and made according to the standards of IEC61000-4-4 and GB/T17626.4 in this paper. A switching mode power supply is developed as the high-voltage DC power supply. A hydrogen thyratron is used as the main circuit switch. And the developed EFT/B generator is very cheap. A combination wave generator is also designed and made according to the standards of IEC61000-4-5 and GB/T17626.5. Spark global gap switch with triple electrodes is developed as the main circuit switch. Experimental results show that the output signals of the developed EFT/B generator and combination wave generator can be used in EFT/B and surge immunity test.更多还原