变压器差动保护常见误动研究与防范措施

发布时间：2018-07-31 17:43

【摘要】：随着我国特高压输电系统的大力发展和智能变电站广泛推广建设,中国电力特高压电网技术的研究与应用已经迈入国际领先水平。电力系统的运转离不开坚强的电网骨架和精良的一次设备,变压器作为电力系统中电压等级变换的重要设备,其安全运行关系到整个电力系统能否连续稳定的工作。差动保护作为电力变压器的主保护,其动作的可靠性决定了电力系统的稳定运行。但是在实际工程中,由于安全措施执行不到位,工程验收、技改中试验不仔细,带负荷向量测试工作操作失误,电流互感器保护绕组与测量绕组使用错误,差动电流回路存在多个接地点,空载合闸时变压器产生励磁涌流,智能化变电站运行经验不足,在操作中SV软压板投退不合理等因素引起差动保护误动作情况仍有发生,因此论文研究具有重要实用价值和一定理论研究意义。首先,论文对不同接线方式下变压器差动保护范围进行详细的研究,得出其保护范围在各侧电流互感器所包含的区间,从而判断故障时变压器差动保护动作正确性;其次,对变压器差动保护的原理、励磁涌流判据波形对称原理、二次谐波制动原理和间断角原理以及差流平衡补偿方法进行详细分析,对两种比率制动差动保护动作特性以及动作实现逻辑进行深入探讨;着重选取工程应用中典型的国电南自PST1200系列保护装置,对其校验时所做安全措施和校验方法进行详细说明,为工程人员在现场设备维护中提供参考建议。最后,论文针对工程中发生的二次回路多点接地引起干扰电流、主变差动保护各侧流变变比极性接线不一致、智能变电站主变保护单侧SV接收软压板未投入、电流互感器选错准确等级、空载合闸变压器产生励磁涌流等原因造成差动保护误动作典型案例,详细分析其误动原因,并结合常见保护误动案例,提出以带负荷向量测试为代表的一些在工程中有效防止变压器差动保护误动作的防范措施。
[Abstract]:With the development of UHV transmission system in China and the widespread construction of intelligent substation, the research and application of UHV power grid technology in China has entered the international leading level. The operation of power system can not be separated from strong network skeleton and excellent primary equipment. As an important equipment of voltage grade transformation in power system, its safe operation is related to whether the whole power system can work continuously and stably. As the main protection of power transformer, the reliability of differential protection determines the stable operation of power system. But in the actual engineering, due to the lack of safety measures, the acceptance of the project, the inattention of the test in the technical reform, the error in the operation of the test with load vector, the wrong use of the protective winding and the measuring winding of the current transformer, There are many locations in differential current circuit, excitation inrush current is produced by transformer when no load is closed, operation experience of intelligent substation is not enough, and the maloperation of differential protection is still occurred due to some factors, such as unreasonable operation of SV soft voltage plate in operation, etc. Therefore, the thesis research has important practical value and certain theoretical significance. Firstly, the paper studies the range of transformer differential protection in different connection modes in detail, and gets the range of transformer differential protection in each side of current transformer, so as to judge the correctness of transformer differential protection operation when the fault occurs. The principle of transformer differential protection, the principle of waveform symmetry of excitation inrush current criterion, the principle of second harmonic braking, the principle of discontinuous angle and the compensation method of differential current balance are analyzed in detail. In this paper, the action characteristics and actualization logic of two kinds of ratio braking differential protection are discussed in depth, and the typical PST1200 series protective devices in engineering application are selected, and the safety measures and calibration methods are explained in detail. Provide reference advice for engineers in site equipment maintenance. Finally, aiming at the interference current caused by multi-point grounding in secondary circuit, the rheological ratio polarity of main transformer differential protection is not consistent, and the single side SV receiving soft voltage plate of main transformer protection in intelligent substation is not put into operation. The typical cases of differential protection maloperation caused by the accurate grade of current transformer selection and excitation inrush of no-load closing transformer are analyzed in detail, and combined with common protection misoperation cases, the typical cases of differential protection maloperation are analyzed in detail. This paper puts forward some preventive measures which are represented by load vector test to prevent transformer differential protection from maloperation effectively in engineering.
【学位授予单位】：华北电力大学(北京)
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TM774

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