Composite Fiber-optic Ground Wire Research Articles

Online ice-coating monitoring research on overhead transmission lines with Brillouin optical time domain reflectometry

Online monitoring the ice-coating status along the overhead transmission lines under extreme weather is important for the safe operation and pre-warning of power-communication system. For the loose-tube composite fiber-optic ground wire, the external strain applied on the cable caused by the coated ice are directly measured and the ice-coating status are estimated based on the spontaneous Brillouin scattering in the single-mode fiber within the composite cable. When the applied strain is less than 60% of the rated breaking force, the optical fiber is not influenced by the external force. When the applied strain is larger than 60% of the rated breaking force, the Brillouin frequency increases linearly with the external strain. With the same force 85 KN, the 10 mm and 20 mm thickness of coated ice caused 11.3 MHz and 33.19 MHz frequency increase of the Brillouin scattering, corresponding to 226 με and 663.8 με strain change on the fiber. Experimental results show that BOTDR sensing system is feasible for the ice-coating monitoring of loose-tube composite fiber-optic ground wire, and could provide technical support for the further scientific analysis.

Calculation of melting/breaking of GW and OPGW strands struck by DC arc discharge simulating high energy lightning

Some metal strands of ground wire (GW) and composite fiber-optic ground wire (OPGW) are sometimes melted and broken by high energy lightning strikes. Direct current (DC) arc tests simulating high energy lightning strikes have thus been performed to obtain the melting and breaking characteristics of these strands. In this work, calculations regarding these characteristics are performed considering the transferred heat and its area from the arc to the strands. The melting/breaking characteristics of the strands are calculated for arc currents of 0.1–100kA, considering the current prescribed in the IEC standard and the measured actual lightning current. The calculation results of the strand-breaking duration depending on the arc current show good agreement with the experimental values obtained in DC arc tests. Furthermore, the calculation results show that the IEC standard testing conditions are far more severe than those in the cases of a higher current and longer gap.

Development of a Method of Calculating the Melting Characteristics of OPGW Strands Due to DC Arc Simulating Lightning Strike

Some strands of composite fiber-optic ground wire (OPGW) are sometimes melted and broken by high-energy lightning strikes. DC arc tests simulating lightning strikes have been performed to obtain the melting and breaking characteristics of OPGW strands. The tests have to be performed under many conditions concerning the arc (e.g., current, duration, polarity, gap length) and the OPGW (e.g., size, type, and number of strands) to clarify the melting and breaking characteristics of the strands. In this paper, the calculations regarding the melting characteristics of strands are performed considering the transferred heat and its area from the arc to the strands under the aforementioned conditions. The melting characteristics of strands are calculated with an arc current of 1-100 kA considering the measured current of actual lightning. The calculation results of the strand melting duration depending on arc current show good agreement with the experimental values obtained in dc arc tests.

Enhancement on Al–Mg–Si alloys against failure due to lightning arc occurred in energy transmission lines

This article has been prepared to share some experience and technical investigation related to lightning and short circuit strength of the OPGW type conductor used in transmission lines. It is well known that overhead ground wires are vulnerable to strand breakage due to lightning strikes. Recently applications of composite fiber optic ground wire have become more important to protect them from such damage. In this paper, we present test results before and after application of modification to the main conductive part of the conductor, which is composed of AA-6101 alloy, galvanized steel and SS-steel tube with fibers. Modification of AA-6101 aluminum alloy was performed by adding 3% AlB2 into molten metal. After having completed manufacturing of the improved feedstock at CCL, we performed the drawing and stranding of wires.

Innovation on Energy Power Technology (24)Development of Composite Fiber-Optic Ground Wire

In correspondence with the development of the high information-oriented society, macroscale of the information voltage by the optical fiber is planned. In such situation, it is OPGW forming the basis of the current communication. I introduce process about this development.

Melting and Breaking Characteristics of OPGW Strands by Lightning

Some strands were melted and broken in a 140 mm/sup 2/ OPGW (composite fiber-optic ground wire) in a 187 kV transmission line. It was assumed that this was caused by a lightning strike. DC arc tests simulating lightning strikes were carried out, and the melting and breaking characteristics of OPGW strands were obtained. The electric charge of the lightning strike that damaged the OPGW was estimated from the number of strands broken by the DC arc. In this paper, the DC arc test results, and the test conditions required to simulate a powerful lightning strike are described.

Development of lightning-resistant overhead ground wire

Overhead ground wires (GW) are vulnerable to strand breakage due to lightning strikes. With the wider application of composite fiber optic ground wire (OPGW), it becomes more important to protect GW from such damage. In this paper, the authors present the results of various investigations made in developing lightning-resistant GW/OPGW. Investigations included field experiments using rocket-triggered lightning, studies on materials and designs to improve lightning characteristics and various evaluation tests, such as DC arc tests, of several prototypes. As a result, the authors have developed lightning-resistant GW/OPGW applicable for conventional transmission lines.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>