【作者】 武一；

【导师】 杨瑞霞；

【作者基本信息】 河北工业大学 ， 微电子学与固体电子学， 2015， 博士

【摘要】 随着智能电网的发展,电力电子设备得到广泛应用,其发生漏电故障时的漏电电流变得很复杂,在漏电保护理论、检测技术等方面需要解决出现的新问题。论文在分析剩余电流保护技术发展现状的基础上,针对非线性剩余电流检测技术和保护技术开展研究。研究了磁调制式电流检测数学模型,为实现非线性剩余电流传感器设计提供了理论依据。分析了电流型和电压型磁调制式电流传感器的励磁动态特性,推导出被测直流电流信号与磁心中磁场偶次谐波分量之间的数学模型;建立了单磁心电压型磁调制式电流检测模型,证明了通过励磁电流的测量可以实现剩余电流的准确检测;建立了考虑磁滞效应的磁调制式剩余电流传感器励磁分析模型,在正向饱和与负向饱和的临界电流差值相同的条件下,励磁脉冲电压频率及励磁电流的直流分量不受是否考虑磁滞效应的影响,为工程简化计算提供了理论依据;提出了励磁脉冲电压频率自适应控制方法,提高了直流剩余电流检测灵敏度,并降低了励磁电源的功率损耗。研究了剩余电流保护新方法,提高了剩余电流保护的有效性和准确性。分析了脉动剩余电流波形特点,进行半波、90°波、135°波等波形识别,提高了脉动剩余电流保护的准确性和一致性;提出剩余电流变化量保护理论,建立正弦与非正弦下变化量保护模型,克服剩余电流保护动作死区;提出了减少剩余电流保护误动作的方法,包括过负荷电流下剩余电流保护比例制动策略、IT电网漏电故障线路的选择性保护策略。开展了剩余电流保护控制器的硬件设计与软件设计研究。分析了影响磁调制式剩余电流传感器工作特性的因素,通过改变传感器的匝数、励磁电压幅值、反转励磁电流阈值等方法使传感器达到设计要求;根据剩余电流保护范围和要求,设计了磁调制式剩余电流传感器及控制器硬件电路,并进行了软件设计。进行了剩余电流保护控制器的仿真与试验研究。采用Matlab/Similink建立了电压型磁调制式剩余电流传感器的仿真模型,仿真结果与试验结果基本吻合,并验证了理论模型与仿真方法能够指导剩余电流传感器的设计,同时考虑磁滞效应的励磁电流动态过程与实际过程更吻合;进行了剩余电流保护控制器动作特性测试、通讯功能测试和电磁抗干扰试验。更多还原

【Abstract】 With the increasing of power electronic devices, residual current becomes more complicated when electric leakage faults happen. Therefore, it is necessary to solve new problems in protection theory and measuring technology of residual current. Based on the analysis of the development of residual current protection technology, this paper focuses on the study of measuring technology and protection theory of non-linear residual current, which has significant theoretical and application value.The dynamic characteristics of the current-drive and voltage-drive magnetic modulation residual current transformers are analyzed, and a simplified mathematical model is derived to demonstrate the relationship between the measured DC signal and the even order harmonic components of magnetic field in the magnetic core. The residual current detecting model of voltage-drive magnetic modulation transformer with a single magnetic core is built, and it is proved that the residual current can be measured precisely by detecting the excitation current. The analysis model of magnetic modulation current transformer considering magnetic hysteresis has been built. With the same difference between positive saturation threshold current and negative saturation threshold, whether magnetic hysteresis is considered will not influence the frequency of pulsed excitation voltage and the average excitation current. Therefore, it provides a theoretical foundation for the simplified engineering calculation. A self-adaptive control method of excitation voltage frequency is proposed to improve the detecting sensitivity of DC residual current and to reduce the power consumption of the exciting power supply.The new residual current protection methods have been studied. Waveform characteristics of pulsating DC residual currents are analyzed to identify different waveforms, such as half-wave, 90° wave, 135° wave and so on. Various thresholds are proposed for residual current with different waveforms to improve the accuracy and consistency of pulsating DC residual current protection. A residual current protection method based on residual variation is proposed. The protection models for both sinusoidal and non-sinusoidal residual current have been introduced, and the dead zone of residual current protection is overcome. Furthermore, the methods to reduce nuisance tripping are carried out, such as percentage-ratio restraint residual current protection and selective protection in IT power grid.The residual current protection controller is designed. Factors that affect the operating performance of the residual current transformer are analyzed, and the frequency of excitation voltage, average excitation current and detection range of residual current are the main characteristic parameters of the transformer. And several factors, such as varying number of turns, tuning amplitude of pulsed excitation voltage and reversing the exciting current, are taken to make the transformer meet the design requirements. Hardware and software design are carried out according to the range and requirements of residual current protection.The simulation and experimental study of residual current protection controller is conducted. A simulation model of voltage-drive magnetic modulation residual current transformer is built using Matlab/Similink, which includes B-H curve model with magnetic hysteresis taken into consideration, pulsed excitation voltage control circuit model and input-output model. The output characteristics of the residual current transformer are tested, including the dynamic process of excitation voltage and waveform of excitation voltage with input current. The comparison between experimental and simulation results is presented, which proves that the theoretical analysis and simulation model can be used to guide the design of residual current transformer. Furthermore, the dynamic process of excitation current considering magnetic hysteresis is more consistent with the actual changing process. Several tests are conducted, such as the operating characteristics of the residual current protection controller, telecommunicating function and EMC.更多还原