【作者】 崔杨；

【导师】 莫耀赐；

【作者基本信息】 广西大学 ， 电力系统及其自动化， 2005， 硕士

【摘要】 电力变压器是电力系统中极其重要的设备,差动保护是变压器主保护。空载合闸或外部短路故障切除电压突然恢复时产生的励磁涌流,其大小几可比拟内部故障电流。能否正确区分励磁涌流与内部故障一直是变压器保护的焦点,目前的各种励磁涌流鉴别方法大部分是基于基尔霍夫定律,都存在原理上的缺陷;一些差动保护的新理论、新技术还需要在实践中进一步完善。 随着电力系统规模的增大,有载调压变压器的应用更加广泛,由此也产生了相关的很多问题,其中,由调压抽头的改变引起的TA二次侧电流不匹配的问题,严重影响差动保护的准确性和可靠性。 自适应保护能够在线自动识别和诊断故障类型,并自动调整保护动作定值及特性。作为自适应保护的硬件基础,微机系统的迅猛发展使得自适应原理的应用前景更加广泛。 本文在深入了解变压器差动保护的基础上,将自适应原理与目前常用的励磁涌流判据相结合,提出新的电压开关量原理与二次谐波制动相结合的复合判据。另外对有载调压变压器变比改变时,TA二次侧电流与抽头位置的关系作出研究,提出自动识别变比的电流校正原理,通过在线调整的方式对TA二次侧电流作自适应校正。 本文利用电力系统仿真软件PSCAD/EMTDC对所提出的自适应方案进行仿真验证,并得出结论。更多还原

【Abstract】 Power transformer is one of the most important equipment in power system, its main protection is differential protection. The magnetizing inrush current caused by switch-in or recovery from external fault with voltage sudden rise, its magnitude is as same as which internal fault happens. The ability of identifying inrush current exactly is the focus of transformer protection at all times. At present, most of inrush identified methods based on Kirchhoff current law have the theoretic defect; some new theories and discrimination method, still wait for further consummation.With the development of power system, on-load tap changer transformers apply widely, therefore some coherent questions come up. Mismatch of TA secondary sides currents among these causes by taps changing, severely affect the accuracy and security of differential protection.Self-adaptive protection is able to identify and diagnose fault type automatically, then adjust fixed value and characteristic of protection. As the hardware base of adaptive protection, fast development of microcomputer system renders an extensive prospect for adaptive theory application.In this thesis, a new criterion based on voltage switching value compound with secondary harmonic restraint is put forward. A kind of TA currents correction method based on the analysis between TA secondary sides current and taps position is introduced, which can adjust TA secondary side currents online automatically.The simulation software PSCAD/EMTDC is used for evaluating the schemesuggested upside.更多还原