| With the widespread using of gas insulated substations(GIS),In its promotion of intelligent process,more and more secondary intelligent devices with control,communication and protection functions are applied to the high-voltage switching field and installed on the primary side.In the event of electromagnetic interference,there may be malfunction or damage to the equipment,which will seriously threaten the safe and stable operation of the substation.Switching operation in GIS will produce a class of very fast electromagnetic transient(VFT)phenomenon,that is the source of the electromagnetic interference.When VFT propagates inside the enclosure,it will catadioptric and propagate to the enclosure,and radiate to outer space through GIS enclosure.Because the electromagnetic interference source VFT have the characteristics of high amplitude,fast rising speed,wide frequency band and so on.It can produce very serious electromagnetic interference,which has become the bottleneck of the development of substation intellectualization.Therefore,the research of electromagnetic compatibility of GIS enclosure is of great significance to reveal the mechanism of electromagnetic interference in switching operation and ensure the safe operation of substation.The electromagnetic compatibility of GIS enclosure mainly refers to the shielding performance and radiation performance of the enclosure.Though it is well-known that shielding properties of the GIS enclosure,but how does the VFT propagate within the GIS enclosure and how many internal VFT electromagnetic waves can be shielded by the GIS enclosure lacked systematic theoretical research;At the same time,there is a lack of intensive study on the radiation level and distribution characteristics of the transient electromagnetic field generated by transient current,which caused by the TEV propagate to the enclosure.The lack of research on the electromagnetic compatibility of the GIS enclosure makes it difficult to reveal the mechanism of VFT electromagnetic interference,and the characteristics of the electromagnetic distribution of space radiation are unknown,so it is hard to put forward effective measures to prevent electromagnetic interference.To this end,the thesis focuses on the propagation of VFT in the GIS,the quantitative calculation of the shielding effectiveness of the enclosure and the calculation of the transient electromagnetic radiation electromagnetic field.The main research contents are as follows:1)This thesis describes the electromagnetic interference sources and GIS EMC characteristics in domestic and abroad,the propagation characteristics and research methods of transient electromagnetic wave in GIS enclosure are discussed,based on the theory of transmission line,a simulation calculation model of electromagnetic wave propagation was established.The propagation process of high frequency electromagnetic wave and the intensity of radiation electromagnetic field inside the enclosure were discussed.2)Secondly,the thesis quantitatively analyzes the electromagnetic shielding effectiveness of GIS enclosure,and describes the principle of electromagnetic shielding.Considering the reflection loss,absorption loss and internal multiple reflection loss of the metal shell on the calculation model of the electromagnetic shielding simulation.The electromagnetic shielding of the enclosure of GIS of the shielding effectiveness of quantitative analysis and discuss the factors that affect the shielding effectiveness.The electromagnetic shielding effectiveness of the GIS enclosure was quantitatively analyzed and the factors affecting the shielding effectiveness were studied.3)The thesis carries out the simulation calculation and measurement of GIS enclosure radiation electromagnetic field after the completion of the above work.Based on the research group’s work on the measurement of TEV waveform,the mathematical expression of the transient current of the enclosure used as the radiation electromagnetic interference source is preliminarily equivalent.The electric dipole radiation model of the equivalent GIS enclosure is established based on the antenna theory,and the field measurement of the radiated electromagnetic field is carried out based on the 330 kVGIS platform.Finally,a brief summary is made in this thesis,the defect of the model established and measurement here are discussed,and the prospect of the next investigation is made as well.The results of the thesis show that: The GIS metal enclosure has a very strong shielding effectiveness on the internal high frequency electromagnetic field,and it can shield the electromagnetic field generated by the electromagnetic interference source propagating along the GIS busbar;The amplitude,the frequency and the distribution characteristics of the space radiation transient electric field and the magnetic field in the GIS substation under the transient impact condition of the switching operation are obtained by simulation and measurement.The research contents provide theoretical basis for explaining the electromagnetic interference mechanism of switching operation and putting forward the corresponding measures to prevent electromagnetic interference. |
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