지중 XLPE 전력케이블 및 직선접속부의 고주파 전송특성 연구

Abstract

This thesis analyzes the high-frequency propagation characteristics of underground cross-linked polyethylene power cables using analytic modeling, simulation and measurement. We demonstrated that the existing analytic modeling can be applied to obtain the propagation characteristics of XLPE power cables below 1 GHz. We designed an adaptor for connection with a network analyzer and extracted the propagation constant by measuring the S-parameters in the range of 10 MHz - 1 GHz. We analyzed the electric field distribution using simulation, laying the foundation for development of a partial discharge sensor. Further, we analyzed the high-frequency propagation characteristics and the electric field of a straight joint that connected the XLPE power cables. We measured the permittivities of all the materials the joint is composed of and simulated the electric field distribution of the straight joint using these permittivities. We extracted only the propagation characteristics of the straight joint by excluding the characteristics of the XLPE cable using the ABCD matrix. Thus, we discovered that PD signals above 50 MHz cannot pass through the straight joint because the reflection between the cable and the joint is very high. We proposed, using a new design method, a 2-port multiple-input multiple-output antenna (MIMO) structure having no extra structure for isolation. Our new method enabled the antenna to operate in the frequency range of 2.40 - 2.48 GHz as a Bluetooth antenna. The existing MIMO antennas have structures such as a filter and a slot for isolation. However, we increased the isolation between the two planar inverted F antennas (PIFAs) by making their electric field polarizations opposite each other. Therefore, the proposed MIMO antenna occupies less space than the existing MIMO antennas.