接地网缺陷诊断的磁耦合谐振检测方法研究

The eddy current detection method, based on the principle of electromagnetic induction, is an important diagnosis method for grounding grid. It has the advantages of on-line and non-excavation, and even without grounding’s topology information. However, it encounters difficulties in the following situations as a relatively, steel barrier layers and strong anti-interference brought by the power equipments. The magnetic resonance coupling technology adopted in wireless power transfer possesses the characteristics of tightly coupling, long effective distance, and strong interference ability for the middle or surrounding objects. Therefore, the tight coupling can be utilized for solving the far distance problems. The frequency selection can be adopted for pass through the barrier layer and weakening the interference from ground equipment. Hence, we propose a magnetic resonance coupling detection method for grounding grid. The research includes magnetic resonance mechanism, detection principle of magnetic resonance coupling, the relationship between the grounding state and the resonance parameters, the ability of passing through barrier layer and the anti-interference of equipments, followed by the experiments and demonstration applications. The research will extend the electromagnetic induction application the in the near field, the magnetic resonance coupling application is introduced in the area of detection, and meanwhile a new grounding detection method will be provided.

基于电磁感应原理的涡流检测是接地网诊断的重要方法，它能够实现非开挖在线检测，甚至不需要接地网拓扑信息，但也面临着作用距离较小、难以穿越钢筋障碍层和受到地面设备严重干扰的问题。而无线电能传输中的磁耦合谐振技术具有紧耦合、作用距离远、对处于中间或者周围物体的抗干扰能力强等特性。故可利用其紧耦合性来解决作用距离问题，利用谐振系统对频率的选择性解决穿越障碍层和抗地面设备干扰问题，就此提出了应用磁耦合谐振的接地网检测方法。课题主要研究磁谐振机理、磁耦合谐振检测原理、接地网状态与磁耦合谐振参数的关系、磁耦合谐振检测系统穿越障碍层和抗地面设备干扰的性能，并开展实验验证和示范应用。课题研究拓展了电磁感应原理在近场盲区的应用，将磁耦合谐振技术的应用从能量领域引入信息检测，更也为接地网检测提供一种新方法。

接地网主要实现电力系统工作接地、保护接地和防雷接地功能，其随着使用年限的增加，因焊接或腐蚀等造成接地导体变细甚至断裂，引起接地电阻增加，导致地电位上升并影响设备正常工作、带来安全威胁、降低系统防雷性能甚至引起控制设备误动或拒动等事故，对电力系统的稳定运行造成安全隐患。因而查找接地网导体断点，诊断导体腐蚀状态受到广泛关注。接地网因其处于特殊环境之中，无法直接检测其存在断点与否。所以，针对同时满足强耦合和穿越障碍层的需求，根据接地网孔完好和断裂时对应不同的电路模型，提出一种基于目标体谐振的磁耦合检测方法。该方法在金属环境中有较强的稳定性。此外，分析了各参数对该检测方法性能的影响，并针对主要影响因素进行发射端优化。在接地网断点检测的仿真中，发现该方法能够实现口字形、日字形、田字形网孔的断点检测。该断点检测方法相对传统方法具有一定的跨越障碍层的能力，有望应用于接地缺陷诊断工程中。因此，开展该接地网断点检测方法的研究具有重要的理论意义和应用价值。