【作者】 古斌；

【导师】 谭建成；

【作者基本信息】 广西大学 ， 电力系统及其自动化， 2014， 博士

【摘要】 随着大容量及超大容量变压器的广泛使用,变压器主保护性能的重要性也更加凸现出来。因此,研究性能更优良的变压器保护新原理和新算法具有重要的理论价值和实际意义。论文着重基于提升电力变压器电流纵联差动保护的整体性能水平及研究与变压器差动保护无关的主保护新原理展开工作,论文研究的主要内容和成果有：(1)基于瞬时无功功率理论,提出了基于差有功及差无功直流分量绝对值比值的变压器涌流辨识新方法。该方法基于变压器不同状态时有功和无功的内在关系,摆脱了传统的基于差流波形特征的涌流识别方法的种种限制,揭示了变压器励磁涌流和故障状态的本质不同。(2)变压器处于励磁涌流状态时,其铁芯随励磁电压的变化周期性地在饱和状态及非饱和状态之间摆动,相应地其瞬时励磁电感值也周期性地变化(铁芯饱和时较小,退出饱和时很大),此时其励磁电感或电抗值含有较丰富的基频分量值；基于励磁电感或电抗的涌流辨识方法把握了涌流与内部故障的本质差异,但其缺陷是需要测量变压器绕组的电流值,因而对现场TA(电流互感器)配置有特殊要求,要求能测各侧各相绕组电流。本文提出了基于零序过滤的变压器励磁电感计算方法及涌流识别方法,适合于TA按典型方案配置的Y/△接线变压器,使得励磁电感涌流辨识方法的应用范围得以扩展。(3)提出了三种高速功率方向保护算法或原理并应用于变压器保护。方法一是基于瞬时值对称分量变换的变压器快速方向保护算法。方法二是基波正序突变量高速方向保护新算法。方法三是滤除高频暂态量的突变量高速方向保护原理。方法一采用了特殊设计的滤波器及快速滤序算法,并根据新型方向判据来快速判别故障方向。相比于方法一,方法二、三无需特殊设计的滤波器,只需采用十分成熟的低通滤波器来滤除高频暂态分量,方法二再采用差分滤波来抑制电流非周期分量,然后采用基于帕克变换的新方法来快速计算基波正序故障分量相量,以实现快速的故障方向判别。不同于方法二的快速相量算法,方法三是时域的高速算法,且无需对短路电流非周期分量进行额外处理,并采用了新型相序变换方法以使保护原理能适应不同的故障类型。这三种新型快速方向保护算法或原理,对于一般内部故障可在故障后极短时间内出口跳闸,可极大提高切除各种情况下变压器内部故障的速度。当选用P级电流互感器时,保护可在互感器进入饱和前可靠出口跳闸。(4)提出了电力变压器故障分量无功功率方向保护原理。该方案基于故障分量保护原理,只需采集变压器端口电压、电流数据,无需任何先验参数,摆脱了传统变压器差动保护中励磁涌流识别的束缚,体现了变压器主保护原理新的研究思路,可应用于不同接线组别的变压器保护,可有效区分外部近区故障切除电压恢复产生涌流、带载合闸等各种变压器状态。(5)提出一种有效区分空投涌流与空投于故障的变压器保护新原理。该原理利用帕克变换或瞬时有功、无功电流分量法,可计算变压器在各种暂态过程中的基波正序有功、视在电流比值或基波正序功率因数,并根据这些计算结果的大小来判断变压器是否发生内部故障。该原理与前述的功率方向保护算法相结合,可构成较为完善的变压器保护方案。更多还原

【Abstract】 With the wide use of the large capacity transformer, the importance of transformer primary protection performance is more apparent. So it is a thing with very vital significance to study the new transformer protection principle and algorithm with more excellent performance. The dissertation focuses on improving power transformer current longitudinal differential protection performance and researching the new transformer primary protection principle having nothing to do with the differential protection, the main content and the research results of the dissertation are as follows:(1) Based on the instantaneous reactive power theory, the dissertation proposes a new algorithm for discrimination between inrush current and internal fault current based on the ratio of real and reactive power of differential power. From the angle of energy conservation and the relationship between real and reactive power,the essential difference between transformer inrush current and fault status is revealed.(2) A computational method of excitation inductance of power transformer to identify inrush current has good effect. However the excitation inductance of power transformer with Y-Delta connection cannot be calculated directly using existed method because the winding currents on the Delta side cannot be measured based on existed TA configuration.An algorithm based on filtering zero sequence component to calculate the excitation inductance of power transformer with Y-Delta connection is proposed in the paper.The algorithm can calculate the excitation inductance representing the combined effects of both positive and negative components by using the delta side line currents directly.The results of the excitation inductance calculated using the algorithm proposed have distinct character in inrush current and fault condition,so the algorithm can identify inrush current effectively.(3) The dissertation proposes three high speed power directional protection algorithms and uses them in transformer protection.The proposed algorithm1is based on transformation of the instantaneous value symmetry component. The proposed algorithm2is based on the fundamental frequency positive sequence superimposed components. The proposed algorithm3is based on fault components with high-frequency transient quantities filtered out. The algorithm1uses the specially designed filters and fast filtering squence algorithms, and determines the fault direction by a novel fault direction criterion. Compared to algorithm1, the algorithm2and3need not the specially designed filters, and only use the conventional low-pass filter to filter the high-frequency transient quantities. The algorithm2presents a high speed algorithm for the extraction of fundamental frequency positive sequence voltages and currents superimposed components based on Park transformation. Be different to the high speed phasor algorithm of algorithm2,the algorithm3is a time domain high speed algorithm, and the current DC decaying component need not to be processed with additional method. In addition, a novel phase-sequence transformation matrix is constructed to identify faults for three-phase systems in the algorithm3, and sequence1quantity transformed by using this matrix is suitable for all fault types.The proposed high speed directional protection algorithms or principle can determinate the fault direction in short data window. With using the P level TA, the protection can reliably send out the clearing order before the TA saturation.(4) A transformer protection principle based on fault component reactive power directional element is proposed. The protection principle is based on fault component protection principle. Only collecting voltage and current data of the transformer port and without any transformer internal parameter, the principle is simple and highly reliable, independent of inrush current, suitable for the differently connected transformers,and can distinguish any operation state including inrush current produced by energizing with load and external fault clearing,and has good project application prospect.(5) The dissertation proposes a novel transformer protection principle using fundamental frequency positive sequence power factor to effectively distinguish between switching the transformer with an internal fault and inrush current. By using the Park transformation,the fundamental frequency positive sequence power factors of transformer in various transient process are obtained.According to the fundamental frequency positive sequence power factor of transformer, magnetizing inrush and internal fault can be distinguished. The principle has clear physics significance, easy engineering realization,and need not any transformer internal parameters,and is free from the impact of transformer wind connection mode,has sufficient sensitivity for energizing into light turn-to-turn fault.更多还原