10kV配电网中性点灵活接地方式及接地故障检测系统的研究

【作者】 蔡雅萍；

【导师】 陈维江； 蔡国雄；

【作者基本信息】 中国电力科学研究院 ， 高电压与绝缘技术， 2002， 硕士

【摘要】 通过分析10kV配电网的故障特点和中性点不接地、经消弧线圈接地和经电阻接地三种方式的优缺点，提出了一种灵活接地方式的设想：该方式下中性点设备由自动调谐的消弧线圈和灵活投切的接地电阻器并联而成，充分发挥消弧线圈补偿电容电流、提高单相接地故障自恢复概率的作用，以及电阻器抑制弧光接地过电压和谐振过电压等的作用，并通过投入电阻器产生足够的电流使在单相永久接地故障下实现可靠的变电所选线和馈线上的故障点定位，从而大大提高配电网的运行可靠性和安全性。 对于电容电流较小，按照电力行业标准DL／T620-1997规定不必装设消弧线圈的10kV配电网，亦可采用上述灵活接地方式，此时消弧线圈可简化为两极自动调节，使电网始终处于过补偿状态；对于电容电流大于100A的电网，消弧线圈由固定容量和自动调谐两部分组成。 利用ATP电磁暂态计算程序对灵活接地方式下的单相接地故障进行了数值计算分析，提出了以零序有功分量的大小和方向作为判据的故障选线方法，该方法原理简单，对过渡电阻小于3000Ω的单相接地故障，可实现准确选线；提出了零序电流有功增量和零序电流幅值增量作为判据的故障点定位方法。此外，还建立了380V模拟实验电路，对单相接地特征进行了大量试验，证实了部分理论分析结果。 给出了灵活接地方式下中性点设备的技术参数、测量控制装置的测量方法和控制规律，已在华北电力集团公司廊坊供电公司薛营变电所研制的中性点灵活接地方式成套设备中通过试验检测，技术性能满足规定要求。更多还原

【Abstract】 On the basis of fault characteristic analysis for distribution networks and by comparing both the advantages and disadvantages among the three different neutral ground modes, such as ungrounded, Petersen coil grounded as well as resistor grounded, a neutral flexible ground method is proposed in this paper. For such method, the neutral equipment consists of a auto-tuned Petersen coil and a paralleled automatically switched resistor. The Petersen coil is mainly used to compensate the capacitive current and then to increase the self-restoration probability after single phase fault, while the resistor is used to restrain the over voltage due to arc grounding and resonance. Further more, the paralleled ground resistor can be adjusted to produce enough active component in the fault current that can help to identify the faulty feeder from other feeders in a substation, and even the fault location on the feeder. Consequently, the reliability and availability of distribution network can be improved considerably.The above neutral flexible ground method can also be applied in cases of such lOkV distribution networks with lower capacitive current where Petersen coil is not needed according to DL/T620-1997, a standard for the electric power industry. In such cases, a two tapped Petersen coil is enough for automatic adjustment to ensure over-compensation to the network. For the networks with capacitive current greater than 100A, the Petersen coils should consist of a fixed part and an auto-tuned part.Through numerical calculations and analysis of the single phase to ground fault of a flexible ground system by the ATP, an Alternative Transient Program to the Electro-Magnetic Transient Program (EMTP), a new simple detection method for the faulty feeder is put forward based on both the value and direction of the active component of zero-sequence current. The method ensures correct selection of faulty feeder in a network for a faulty resistance lower than 3000Q. This paper also proposed a new fault locating method based on either the active component increment or the amplitude increment of zero-sequence current. In addition, a 380V experiment model was built up with which some propositions are proved by experiment.Neutral equipment parameters, the measures as well as the control rules for the flexible ground networks are also presented in the paper. The parameters and control rules has been tested by experiment in a real lOkV network in Xueying substation managed by Langfang Power Supply Bureau. And the test results proved that the performance is satisfied.更多还原