Study On Self-powered Lightning Current Measurement Method

Transmission line failures take a great proportion of the power grid accidents.Especially, the HV transmission line failures are mainly lightning failures. Traditionalresearch on transmission line lightning protection mainly relies on experimentalsimulation and simulation analysis, but the current impedance model of transmissionline tower and the impulse grounding resistance model of the tower are not perfect,there is a big difference between the calculation results of the analysis and the actualsituation, the lightning parameters is insufficient as a basis for the formulation oftransmission line lightning protection measures, so accurate measurement of lightningtransmission line parameters is needed to obtain the original information of thelightning parameters. Obtaining the lightning parameters is also helpful to find out thedistribution of the lightning, when combined with transmission line lightning shieldfailures and Back flashover failure, it’s helpful to improve the formulation oftransmission line lightning protection measures.Several kinds of lightning current parameters measurement method have beenproposed by both domestic and foreign scholars in recent years. However, there are stillsome defects in the power supply of the lightning online measurement system, whichhas yet restricted the development of lightning monitoring. In order to solve thisproblem, a new way to power lightning current acquisition system namely self-powermethod has been studied in this paper, which is based on the characteristics of lightningcurrent as transiency and large amplitude and is realized by using energy in lightningcurrent itself. In addition, the power unit has been designed including power coil oflightning current and energy conditioning circuit. Again, based on the research ofself-powered method, the whole monitoring system has been proposed, which canmeasure the magnitude of the lightning current, polarity and time of occurrence and thesignal conditioning as well as acquisition units have been designed coordinated with theabove method, among which the former design work includes the design of amplitudesensor of lightning current and signal conditioning while the latter includes bothsoftware and hardware design.With the basis of theoretical design, simulation of power unit and signalconditioning unit has been implemented by the help of the software Safer. Theagreement between simulation results and theoretical analysis has proved the feasibility of this research subject. Moreover, the parameters of signal conditioning unit and powerunit as well as components selection have been optimized by such simulation.The structure of the self-powered lightning current monitoring device is designedas demonstration in this article, including the design of the shield case, the choice ofshielding material. Based on this device shell, a detailed performance test and analysiswas carried out with impulse current generator simulating lightning current in thelaboratory, including the signal control unit and power supply unit, and onlineexperimental analysis of the self-powered lightning current monitoring device.Ultimately, the experimental results show that the self-powered lightning currentmonitoring device is able to work safely in the lightning storm, without external power,the device supply itself through obtaining energy from lightning. And the magnitude ofthe lightning current, polarity and time of occurrence can be accurately measured.