作者：何毅帆1, 徐恒昌2, 汤亮亮3, 宋恒力4, 徐霞3
作者单位：1. 国网浙江电力科学研究院，浙江 杭州 310003;
2. 杭州意能电力技术有限公司，浙江 杭州 310003;
3. 国网电力科学研究院武汉南瑞有限责任公司，湖北 武汉 430074;
4. 中国地质大学（武汉）自动化学院，湖北 武汉 430074
关键词：无损检测;接地网;锁相放大器;虚拟仪器;LabVIEW
摘要：
在接地网无损探测的工程实际中，复杂强干扰会给数据采集带来困难。锁相放大技术能有效从强背景干扰下稳定地提取出微弱的可用信号，在分析变电站测量环境噪声成分的基础上，基于锁相放大器原理，运用虚拟仪器技术设计一种虚拟数字锁相放大器。该锁相放大器利用数据采集卡内部的可编程滤波器进行抗混叠处理，同时对两路传感器输出信号进行采集，利用虚拟信号发生器产生精确的两路0°和90°参考信号，再用数字低通滤波器得到信号的实部和虚部，最后利用成像算法得到接地网的结构图。通过实验室内测试，该锁相放大器具有较高的频率稳定性、幅值和相位测量精度及较强的抗干扰能力。将该锁相放大器用于接地网无损探测系统，在实际变电站得到工程应用。结果表明：该无损探测系统能够应对变电站复杂的电磁环境，可在现场正常工作，并准确探测到接地网结构。
Non-destructive detection system of grounding grids based on virtual lock-in amplifiers
HE Yifan1, XU Hengchang2, TANG Liangliang3, SONG Hengli4, XU Xia3
1. Research Institute of State Grid Zhejiang Electric Power Limited Company, Hangzhou 310003, China;
2. Hangzhou Yi Neng Electric Technology Limited Company, Hangzhou 310003, China;
3. Wuhan NARI Limited Liability Company, State Grid Electric Power Research Institute, Wuhan 430074, China;
4. School of Automation, China University of Geosciences(Wuhan), Wuhan 430074, China
Abstract: In the engineering practice of non-destructive of grounding grids, the harsh and strong interference makes data acquisition difficult. Lock-in amplifier is an effective technology to extract the needed signal from a complex electromagnetic environment. Base on the principle of lock-in amplifier, a virtual digital lock-in amplifier is proposed applying virtual instrument technology after analysis the noise character of substations. After the anti-alias filter which is programed in the DAQ, the inducted signals from two sensors are synchronously sampled. Virtual phase intensive detectors and digital filters constitute the lock-in amplifier to suppress noise. Two pulse references with phase of 0° and 90° are generated in the virtual instrument. The real and imaginary part of the inducted signal are obtained by digital low pass filter. The topology diagram of the grounding grids is visualized by imaging algorithm. The test in laboratory shows the stability and precision of the virtual lock-in amplifier on frequency, amplitude and phase. The anti-interference performance is verified by a simulated noise. The virtual lock-in amplifier is applied in the non-destructive system of grounding grids. In result of the engineering practice shows the normal operation condition of the non-destructive system in the complex electromagnetic environment of substation. The topological graph is correct and consistent with reality.
Keywords: non-destructive detection;grounding grids;lock-in amplifier;virtual instrument;LabVIEW
2020, 46(3):84-90 收稿日期: 2019-09-15;收到修改稿日期: 2019-11-03
基金项目: 武汉市科技局资助项目（2017010201010142）
作者简介: 何毅帆(1991-),男,浙江杭州市人,工程师,硕士,研究方向为电网设备腐蚀及电气化学
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