特高压自耦变压器的建模和电磁暂态仿真  

Modeling and Electromagnetic Transient Simulation of UHV Autotransformer

作　　者：曾麟钧[1] 林湘宁[1] 黄景光[1] 郑峰[1] 李智[1] 

机构地区：[1]三峡大学电气信息学院,湖北省宜昌市443002

出　　处：《中国电机工程学报》2010年第1期91-97,共7页Proceedings of the CSEE

基　　金：国家自然科学基金项目(50777024)~~

摘　　要：为了在特高压环境下正确应用变压器差动保护,需要对特高压变压器进行合理建模,并进行相应的电磁暂态仿真。根据三绕组自耦变压器星型等值电路的原理,用电磁暂态仿真软件EMTDC中的统一电磁等效电路(unified magnetic equivalent circuit,UMEC)普通三绕组变压器模型来模拟1000MVA/1050kV三绕组自耦变压器,将特高压变压器参数折算成UMEC模型参数,形成特高压变压器模型。在特高压环境下,分别进行励磁涌流和故障电流仿真,并用于考察应用得最为广泛的2次谐波闭锁的变压器差动保护的动作可靠性。分析表明:当合闸角和剩磁满足一定条件时,特高压变压器三相励磁涌流的2次谐波含量都会在10%以下,即使采用一相制动三相的2次谐波闭锁策略,如果2次谐波门槛值维持在15%～20%,也不能避免差动保护误动;另外,在某些轻微故障的情况下,故障初期故障电流的2次谐波含量成分较高,会使保护动作短暂延迟。To correctly apply transformer differential protection in the environment of ultra high voltage （UHV）, it is necessary to model the UHV power transformer reasonably and carry out the corresponding electro-magnetic transient simulations. According to the equivalent circuit of three winding autotransformer, we set up the three winding autotransformer model by means of unified magnetic equivalent circuit （UMEC） transformer model provided by EMTDC software. The parameters of UHV transformer are converted to those of the UMEC model. By this way, the UHV transformer model is built. Under the UHV environment, the excitation and internal fault current of UHV power transformer are simulated, and the simulated data are utilized to investigate the operation reliability of the well-applied differential protection combined with second order harmonic blocking. Simulation results show that the second order harmonic ratios of inrush currents through three phases of the UHV power transformer are all below 10%. In this case, the mal-operation of the differential protection cannot be avoided if the strategy that one phase current is applied to restrain three phases is adopted and the threshold of second order harmonic restraint ratio is 15%-20%. Besides, in some light fault conditions, the second harmonic ratio of the fault current is relatively high in the beginning of fault inception, leading to the short time delay of operation of protection.

关 键 词：特高压变压器 自耦变压器 EMTDC 励磁涌流 内部故障电流 谐波 

分 类 号：TM74[电气工程—电力系统及自动化] TM41