Development and Practical Use of a Fault Section Detection System for Underground Cables applying Optical Fiber Current Sensors with Wavelength Division Multiplexing Transmission Technology

Appearance of optical fiber current sensor

Photo.1 Appearance of optical fiber current sensor

Outline of wavelength division multiplexing (WDM) transmission technology

Fig.1 Outline of wavelength division multiplexing (WDM) transmission technology

Configuration of the cable fault detection system using optical fiber current sensors with the WDM transmission technology

Fig.2 Configuration of the cable fault detection system using optical fiber current sensors with the WDM transmission technology

A fault section detection system for underground power cable using optical fiber current sensors (hereinafter we call as OCT) (Photo.1) was developed by cooperated research among Kansai Electric Power Co., Inc. (KEPCO), Tokyo Electric Power Co., Inc. (TEPCO) and TAKAOKA ELECTRIC MFG, CO., LTD., and since 2004 the system has been practically applied instead of the analogue type system based on the pilot-wire relaying method. However, the developed system has drawbacks in facility investment cost and facility reliability, because the system was combined with winding type CTs when it is applied to single-core type power cable lines. And then decline of the facility reliability may be a cause of decline of the power supply reliability. Furthermore, in recent years, a short-circuit-fault in the underground cable line occurred within the jurisdiction of KEPCO, and facility damage was expanded by the fault because operating duty of the conventional fault section detection system installed at the line was detection of the line-to-ground fault only. Therefore, there was growing necessity of the short-circuit-fault detecting function to fault section detection systems.
To realize omission of the winding type CT and addition of the short-circuit-fault detecting function, it is necessary to measure each of the three-phases of line current with an OCT separately and to transmit each of the OCT signal to the detection terminal. This time those functions have been realized with a newly developed system by a cooperated research among the same companies mentioned above, KEPCO, TEPCO and Takaoka. In the novel system, only two optical fiber transmission lines are used, just like the conventional system, with application of wavelength division multiplexing (hereinafter we call as WDM) transmission technology (Fig.1). In this way, a new fault detection system for the underground cable lines was developed successfully (Fig.2). The short-circuit-fault detecting function was realized without using winding type CTs.

Before development of the novel system, in order to apply a fault section detection system to a single-core type power cable, it was necessary to combine the system with winding type CTs or to transmit signal through six optical fiber transmission lines. This time omission of the winding type CT and signal transmission through two optical fibers were realized by using WDM transmission technique. In this way, the novel system enabled utility companies to reduce the investment cost in replacement of power facility.
Moreover, facility reliability is improved by realizing omission of winding type CT and addition of the short-circuit-fault detecting function, this enables utility companies to improve electric power supply quality. In addition, the secondary disaster in the underground cable fault, induced by Oil-Filled cable fire caused by the automatic reclosing etc., can be prevented because automatic reclosing signal is blocked in case of the short-circuit-fault. Therefore application of the new system is effective to prevent common disaster.

As is stated above, the novel system is a groundbreaking system realizing reduction of investment cost, improvement of electric power supply quality and prevention of common disaster. It is considered that the technique to transmit information of the three-phase current of OCT signals directly through two optical fibers by using the WDM is the first development in the world.

The institute of electrical engineers of Japan praised the achievement and presented the Achievement Award in 2010 to Toshinari Hirata (Kansai Electric Power Co., Inc.), Reishi Kondo (Tokyo Electric Power Co., Inc.) and Eiji Itakura (TAKAOKA ELECTRIC MFG, CO., LTD.).


Publications

[1] K.Kurosawa, R.Kondo, M.Kayaki, T.Hirata, T.Yamada, E.Itakura and D.Tsukiyama, “Development of Optical Fiber Current Sensors using Wavelength Division Multiplexing Transmission”,National Convention Record, IEE Japan, No.6-220 , 2007
[2]M.Kayaki, T.Hirata, K.Kurosawa, R.Kondo, T.Yamada, E.Itakura, “Application of Optical Fiber Current Sensors using Wavelength Division Multiplexing Transmission for Fault Detection System”, On system of protection Relays, IEE Japan, No.PPR-07-30 , 2007
[3]T.Hirata, “Development of New-Fault Detection System using Wavelength Division Multiplexing Transmission of Optical Fiber Current Sensor”, Denki Genba Gijutsu, vol.147, No.552, pp38-42, 2008
[4]M. Kayaki, T. Hirata, T. Yamada, E. Itakura, and Y.Naraki, “Development of Fault Detector for Underground cable Using WDM type Optical Fiber Current Sensors”, National Convention Record, IEE Japan, No.6-295 , 2008
[5]M. Kayaki, T. Hirata, K. Kurosawa, R. Kondo, T. Yamada, and E. Itakura, “Development of Fault Detection System using Wavelength Division Multiplexing Transmission of Optical Fiber Current Sensor”, IEEJ Transactions on Power and Energy, Vol.130, N0.1,pp49-54, 2010
[6]M.Kayaki, T.Hirata, K.Kurosawa, R.Kondo, T.Yamada, and E.Itakura, “Development of the Fault Detection System using Optical Fiber Current Sensors with the Wavelength Division Multiplexing Transmission”, CMD2010, B8-4, pp445-448, 2010




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Electricity & Electric Power
(Power System)

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