【作者】 李慧；

【导师】 林湘宁；

【作者基本信息】 华中科技大学 ， 电气工程， 2017， 硕士

【摘要】 随着电力系统的大容量、大规模发展,短路电流超标现象日趋严峻,催生了基于电力电子器件、超导原理的新型故障限流器的发展。这类故障限流器的投入,不仅因为其阻抗时变特性,使得故障暂态过程更加复杂,给速动性要求高的高压、超高压速断保护带来不可忽视的影响;而且,限流阻抗的投入及其动态过程也给传统继电保护带来新的挑战。对于可控串联补偿型超导限流器,本文重点研究了串补模式到限流模式跨区间跃变的动态过程,以及强制旁路模式下的分段数学模型,成功推导出TCSC-FCL的阻抗-时间数学表达式。在此基础上,分析了跨区间跃变的动态过程对距离保护动作范围、动作时间的影响,得出距离保护范围先超越后缩短、保护动作延迟的结论。为提高TCSC-FCL启动速率和限流速率,本文提出了基于工频突变电流的启动判据;简要介绍基于基波稳态阻抗补偿方案的可靠性和速动性不足的问题后,首次提出了基于动态偏移阻抗圆的距离保护新方法;结合TCSC-FCL多区间工作模式,设计了自动识别工作区间的动态偏阻抗圆保护算法,并在PSCAD上仿真验证了该方法的可行性和有效性。对于超导限流器,建立了电阻型超导限流器的数学模型,在研究工频突变量距离保护的动作原理后,指出超导限流器的投入改变了故障前后的电路模型,使得基于故障前记忆数据的突变量不满足叠加条件。在探讨了自适应电流速断保护与工频突变量阻抗继电器在原理、性能上的相似性后,对比分析两种保护方案的速动性、选择性、带过渡电阻能力;提出适应限流设备的自适应电流速断保护补偿方案。最后在PSCAD中进行仿真验证,研究表明,自适应电流速断保护具备不啻于突变量距离保护的速动性和选择性,更高的带过渡电阻能力,更均匀的速动性。验证了新方法的可行性和有效性。更多还原

【Abstract】 With the increasing scale of the power grid,the coupling degree of the network is deepening,the short circuit current increases quickly.Short-Circuit current exceeding standard has become one of the important technical bottlenecks restricting the construction of power grid.Therefore,new type fault current limiter based on power electronic devices and superconducting principles has been developed rapidly.While,with the installation of FCL,a series of problems arise.The time-varying characteristics of impedance make the fault transient process more complicated,and bring nonnegligible influence to quick break protection,especially for the high voltage and ultra high voltage system with high speed requirement.Moreover,the input and the dynamic process of the current limiting impedance also bring new challenges to the traditional relay protection.For thyristor controlled series compensation fault current limiter(TCSC-FCL),the piecewise mathematical model and dynamic process of the cross interval jump between inductive reactance interval and capacitive reactance interval have been researched and analyzed.Then,a mathematical expression of dynamic impedance characteristics of TCSCFCL is proposed.On this basis,a starting criterion based on power frequency variable is proposed and an original distance protection setting strategy based on dynamic offset impedance circle,in order to eliminate the influence of TCSC-FCL dynamic impedance characteristics is put forward,after analyzing the influence of dynamic impedance on distance protection.Finally,a typical grid model including TCSC-FCL is established,and the correctness of dynamic impedance time function and the distance protection setting strategy is verified.For superconducting fault current limiter(SFCL),the mathematical model of resistance type superconducting fault current limiter is established firstly.Then,it indicates that the input of the superconducting current limiter changes the circuit model before and after the fault,so that the power frequency variation impedance relay based on the pre fault memory data does not satisfy the superposition condition.An adaptive current quick break protection considering the impedance characteristics of superconducting current limiter is proposed,after the similarity and difference in principle and performance of the adaptive current quick break protection and power frequency variation impedance relay are discussed.Finally,the feasibility and effectiveness of the new method is verified by simulation in EMTDC/PSCAD.更多还原