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Cigre Science & Engineering • N°1 February 2015

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problems have been occurred. A new double circuit 765 kV transmission line is currently under construction to satisfy growing power demands. The transmission line is planned to transmit power from the East Coast, where new 10 GW nuclear plants are being built, to the capital area. Total length of the transmission line reaches 181 c-km, passing through densely populated areas such as cities and industrial complexes.

During construction of the transmission line, KEPCO has encountered many civil complaints, which results in the significant delay of the project completion. Those are summarized into three points, i.e. permission for building a structure under transmission lines, demand for larger compensation for decrease of land price near transmission lines, and concerns about health effects of electric and magnetic fields (EMFs). In Korea, the concept of electric transmission right of way (ROW) is slightly different from the other countries. The utility purchases only land for tower construction and pays 30% of the land price in compensation for land use below transmission conductors. Nevertheless, the construction of any structure under the transmission lines is not legally permitted. In addition, due to the limitation of usable land in Korea, KEPCO has consistently been under pressure to expand the use of the land beneath transmission lines. Hence, a need for new guidelines or regulations was brought up for permitting structures below transmission lines. Multiple use of the land will increase worth of land and is, therefore, expected to resolve those civil complaints considerably.

Abstract

During construction of the 3rd 765 kV transmission line in Korea, a strong civil complaint has continued more than 5 years since 2008 and significantly disturbed the progress of the project. It recently progressed to the national concern due to the experience of the wide area blackout on Sep. 15 in 2011 in Korea. The accident occurred due to electricity shortage arising from the combined conditions of unexpected high temperature during autumn season and maintenance actions of several nuclear power plants. The delay of the project obstructs electricity supply to the capital area from the new nuclear power plant and consequently may cause another blackout. Hence, KEPCO has been preparing comprehensive countermeasures such as making new compensation legislation with Korean Government and conducting research works to assess safety and environmental impacts of the transmission line for residents who live near the transmission line routes. In this paper, the situation of civil complaints is introduced with analysing the progress of the project. And also the countermeasures are explained and discussed in detail.

1. Introduction

Korea Electric Power Corporation (KEPCO) has been operating the world’s first double circuit 765 kV transmission line since 2003 [1-4, 8]. While entire length of the 765 kV transmission lines, including single circuit lines, increases up to 835 c-km until now, no operational

Issues in Construction Project of the 3rd 765kV Transmission Line in Korea

D.i.Lee*,s.b.kiM,y.s.LiM,k.y.sHiN,y.H.kiM,(koreaelectricPowerCorporation-republicofkorea)b.y.Lee,s.H.MyuNG,(koreaelectrotechnologyresearchinstitute-republicofkorea)

*[email protected]

Index Terms765 kV, Double Circuit, Transmission Line, Civil Complaint, Electric and Magnetic Field


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1996 to 76,520 MW in 2013, which corresponds to the growth rate of 14% per year. To supply enough power to a metropolitan area such as Seoul, Busan, and Daejeon, new transmission lines were needed. However, increased civil complaints against the construction of transmission lines made it more difficult to get the right-of-way. Consequently, the voltage of transmission line was increased to 345 kV or 765 kV. A graphical description was shown in Fig. 1.

The 765 kV transmission lines, which were designed by our own technical ability, were constructed 2 times. At the first time, two transmission lines were constructed, that are Dangjin thermal plant - Sinanseong Transmission Line and Singapyeong - Sintaebaek Transmission Line. The former was completed in 1999 with a distance of about 150 km and the latter was completed in 2000 with a distance of about 200 km. Lately, the 60 km transmission

This work presents KEPCO’s efforts to resolve the civil complaints. To establish those guidelines, a new research project is planned and started on Jan. 2014. Furthermore, current compensation system for land use and future direction of change are introduced. Finally, the on-going research project dealing with EMF mitigation techniques is introduced. Those activities are expected to be imperative for rapid completion of the transmission line construction project.

2. Outline of the 765kV project

The overhead transmission lines in Korea were composed of low voltage lines such as 22 and 66 kV from 1960s to 1980s, followed by the 154 kV transmission system was mainly used until 2000. The maximum electric power demand rapidly increased from 32,280 MW in

Route Length [km] ConductorNo. Of

bundlesCompletion

yearNote

Dangjin T/P ~ Sinseosan 38.506 ACSR/AW 480SQ 6B 1999

Sinseosan ~ Sinanseong 111.0887 ACSR 480SQ 6B 1999

Singapyeong ~ Sintaebaek 154.8 ACSR 480SQ 6B 2000345kV applied to Sintaebaek ~ Uljin

T/L (about 46.571km)

Sinanseong ~ Singapyeong 59.397 ACSR 480SQ 6B 2010

Singori ~ North-Gyeongnam 87.6 ACSR 480SQ 6B 2014

Dangjin ~ Sinjungbu Not decided ACSR 480SQ 6B 2017

Kangwon ~ Northgyeonggi 130 ACSR 480SQ 4B 2019

Kangwon ~ Sinuljin 130 ACSR 480SQ 6B 2019

Table 1. Summary of 765 kV T/L construction

Fig.1. Rated voltage of overhead transmission line in Korea


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Regulation’ until 2012. The guideline has recently been revised in 2013 to permit construction under 765 kV transmission line in order to cope with the public complaint on the issues of trespass on private properties. However, the safety and electrical effect problem under 765 kV transmission line are not clearly verified because those problems have not been dealt under commercial line in Korea. With this respect, a research project is being carried out for verifying the mutual safety issues between a building and transmission line such as fire from building, earth surface potential raise, electrostatic induction and electromagnetic induction problem. In addition to them, data base (DB) of electrical environmental effect such as audible noise (AI), radio interference (RI), TV interference (TVI), electromagnetic field (EMF), electromagnetic interference (EMI) are included as items for environmental assessment under 765 kV transmission line.

line between Sinanseong and Singapyeong was installed in 2010. The 3rd 765 kV project to connect Singori nuclear plant and north of Gyeongnam Province (Gyeongnam Changnyung) started in 2008. However, it was delayed about 5 years due to strong civil complaints and the completion year was changed to 2014. Besides these transmission lines, 2 new transmission lines are planning and under construciton as shown in Table 1 and Fig. 2.

3. Preparation of Guidelines for Permission of Buildings beneath Transmission Lines

In Korea, all of the activities concerning construction under 765 kV transmission line were prohibited by the national guideline named ‘Korea Electro-technical

Fig.2. Location of 765 kV transmission lines in Korea


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(a) Simulation of the effect from the fire under transmission line

(b) Simulation of the effect by the earth resistance

(c) Simulation of earth surface

Fig.3. Simulation for verifying the safety factors of the building under transmission line


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And also, in order to collect short period electric environmental interferences and atmospheric background, data acquisition system and sensors were installed in a vehicle. It is possible to detect and analyze wind velocity/direction, temperature, humidity, radio interference, television interference, audible noise, ion current density, induced voltage and magnetic/electric field intensity. Measured data is constructed to database and analyzed at site.

The results of the project will be used as technical data for the revision of ‘Korea Electro-technical Regulation’ and safety guideline of KEPCO. DB of electrical environmental effects under commercial 765 kV transmission line will be used for complaint response by the public who are interesting in their private properties and their health.

For the safety test of fire from building under transmission line, computer simulation is carried out for understanding behavior of fire under transmission line and real scale experiments are conducted for verification of simulation results. Similar processes are carried out for verifying earth surface potential raise, electrostatic induction and electromagnetic induction problem respectively at real scale test site.

In order to accomplish data base (DB) of long term electrical environmental effects under commercial 765 kV transmission line, a test site is built up under commercial double circuit 765 kV transmission line. Several kinds of sensors for detecting AI, RI, TVI, EMF and EMI are installed along the vertical line of transmission line. The data pick up by the sensors are collected by data acquisition system (DAS) and used for building the DB.

Fig.4. Test site for accomplishing long term electrical environmental effects

(b) Measurement Program (c) Analysis Program

Fig.5. Mobile DAS system

(a) Diagram of mobile DAS system for detecting environmental interferences


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5. Development of Magnetic field Mitigation technique

Power frequency magnetic field has been a major concern in construction of overhead transmission lines in Korea since classification of magnetic field into Group 2B by IARC monographs in 2002. Although reference level of power frequency magnetic field has been newly set to 200 µT [9] by ICNIRP in 2010, Korean government has no intention of adjusting 83.3 µT [10] specified by law in 2006 to this new reference level considering strength of public concern. Regardless of the current regulation value, KEPCO has been trying to reduce magnetic field in the vicinity of overhead power transmission lines according to WHO’s guidance declared in Fact sheet No. 322. KEPCO has developed two types of mitigation techniques, that is, shielding using passive currents in a wire loop and magnetic shielding with soft magnetic materials. The former is suitable for covering a wide range such as transmission lines, whereas the latter is suitable for a narrow range or an electric apparatus.

4. Preparation of New compensation system

Until 2013, compensation system of Korea was very rigid that the private lands which inside only 3 meters from the directly under of the most outer conductor are compensated. However, the compensation system is revised as illustrated in the Fig. 6. According to the revised compensation system, the man who has private land inside 30 meters from the most outer conductor are compensated for the downed land value due to transmission line. And private house inside 180 meters should be purchased by utility company who will build a transmission line. For the land inside 1,000 meters from outer conductor, neighboring area of the transmission line will be taken areal economical support.

The additional budget for the compensation in according to revised guide line was calculated as shown in Table 2. This budget will be supplied by raise of electricity charge so the charge will be escalated up to 0.34%.

Compensation area(765 kV, 345 kV)

Budget(US M$)

Construction cost(US M$)

Compensation Type

Property Compensation 30 m, 10 m $352.4 (10 year) $35.2

Purchasing Compensation 180 m, 60 m $221.9 (10 year) $22.2

Support Area 1000 m, 700 m $743.3 ( 7 year) $100

Total $1,317.6 $157.4

Table 2. Expected budget for new compensation guideline

Fig.6. Compensation area from the transmission line


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experimental setup. The simple houses were built close to the 1/2 downscaled transmission lines at the KEPCO’s Power Test center in Gochang province. Electric current of the test line was selected to produce magnetic field of 1 and 5 μT that are mean and 5th percentile value of the nationwide distribution of magnetic field, respectively. Two magnetic materials with the same thickness of 0.35 mm, oriented electrical steel and permalloy, were considered as a shielding material. According to the preliminary experiments, permalloy showed a better shielding performance than electrical steel at the range of the tested magnetic field.

As shown in Fig. 8, sheets of permalloy were attached at ceiling, whereas strips of permalloy were vertically placed at window to ensure an outside view. Negligible shielding effect was observed when installing the sheets at walls. Table 4 shows measured magnetic field with the number of permalloy layers. Double layer of sheets with a thickness of 0.35 mm showed a magnetic field reduction factor of about 55% near window. To obtain the same field reduction factor as the case of the passive loop, i.e. 67%, triple layers of permalloy sheets are expected to be installed.

To consider cost-effective methods in magnetic field reduction, costs of the two reduction options are compared. Entire cost for constructing the passive loop to cover the transmission line length of 100 m was about 400,000 US$, i.e. 4,000 US$/m. Material cost amounts to about 20,000 US$ for triple layers of permalloy covering the house width of 6.5 m, i.e. 3,000 US$/m. In these cases, the costs of the two options are comparable. However, considering most of the passive loop cost was

In order to verify effectiveness of the passive loop technique, a horizontal type of passive loop was designed and installed at a commercially operating 154 kV overhead transmission line [5]. Figure 7 shows the 154 kV overhead transmission line installed with passive loop and the calculated magnetic field reduction factor. The transmission line was constructed to supply electric power to an industrial complex which has been being created. Compared with the standard type of KEPCO’s tower configuration, height of the transmission line is exceptionally high and the tower span is only about 100 m. Two-wire type of passive loop was designed using the computer program developed by the authors. The design goal was to achieve a magnetic field reduction factor up to 70% at a point 1 m above the ground. Computer simulation results indicated that maximum magnetic field reduction factor was less than 50% without capacitor compensation. When compensation capacitor was inserted, however, it was found that maximum magnetic field reduction factor increased to about 80%. According to this computer simulation results, capacitance bank with a maximum capacitance of 34 mF was prepared. The capacitance can be regulated by 0.1 mF. Commercial polyethylene cable with a cross section area of 200 mm2 was employed as a conducting wire. Number of turns of the passive loop was 3 and optimal capacitance for reactance compensation determined with the design software was about 5.2 mF. Table 3 shows magnetic field reduction factor measured with EMDEX II. Field reduction factor was found to be 67%.

The effectiveness of magnetic shielding technique [6, 7] was confirmed with an experiment in a model house near a downscaled transmission line. Figure 8 shows the

Fig.7. A passive loop installed to a commercial 154 kV overhead transmission line and calculated magnetic field reduction factor.

Magnetic Field without Passive Loop [μT] Magnetic Field with Passive Loop [μT] Field Reduction Factor [%]

0.03 0.01 67

Table 3. Field reduction factor of the passive loop (1 m above ground)


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8. ReferencesPeriodicals:[1] D. I. Lee, et. al., “Audible noise performance of

6-rail conductors on a 765 kV double circuit test line”, IEEE Trans. Power Delivery, vol. 12, No. 3, July 1997.

[2] J. B. Kim, et. al., “Electromagnetic interference from a three phase double circuit 765 kV test line”, IEEE Trans. Power Delivery, vol. 13, April. 1998.

[3] J. B. Kim, et. al., “Switching overvoltage analysis and air clearance design on the KEPCO 765 kV double circuit transmission system”, IEEE Trans. Power Delivery, vol. 15, No. 1, pp. 381-386, Jan. 2000.

[4] J. B. Kim, et. al., “Route selection and design of 765 kV transmission line considering environmental constraints and public hearing”, CIGRE pp. 22-208-1~6, 1998.

[5] B. Y. Lee et. al., “Power frequency magnetic field reduction method for residers in the vicinity of overhead transmission lines using passive loop,” J. Electrical Engineering & Technology, vol. 6, no. 6, pp. 829-835, Nov. 2011.

[6] S. B. Kim et. al., “Magnetic shielding performance of thin metal sheets near power cables,” IEEE Trans. Magnetics, vol. 46, no. 2, pp.182-185, Feb. 2010.

[7] S. Y. Lee et. al., “Effective Combination of Soft Magnetic Materials for Magnetic Shielding,” IEEE Trans. Magnetics, vol. 48, no. 11, pp.4550-4553, Nov. 2012.

paid for construction of the additional tower, the passive loop technique will be more advantageous for a longer covering range.

6. Discussions & Conclusion

Construction of a transmission line has become more difficut in Korea due to raised demands for environment protection with improvement in standards of living. Visual impact is the most obvious intrusion like the other country. KEPCO has been successfully operating the world’s first double circuit 765 kV transmission line without any disturbance since 2003, even though the 1st and 2nd KEPCO’s 765 kV construction projects had much difficulties in getting the right of way near route of residential area. However, the 3rd project encounters very complicated civil complaints combined with more increased compensation, NIMBY phenomena, environmental interests, etc. Joining of Korean environmental group with the residents made it more complicated. The voices of dissent are growing louder and louder after the Fukushima nuclear accident in Japan. Therefore, KEPCO have been trying to make an enhanced compensation law with Korean Government and to verify safety and environment design factors through field tests. The field tests include assessment of environmental impacts such as corona effects and long term electrostatic and electromagnetic effects under a commercial 765 kV transmission line and a full scale 765 kV test line for more than 2 years. The field test research also contains a joint-research with other country that experiences similar situation such as China. These countermeasures would be one of the most upgraded one in the view point of safety - and environment - friendly design.

Fig.8. Left: simple houses and downscaled transmission lines to conduct a magnetic shielding experiment. Right: installed shielding materials inside the house.

Table 4. Measured magnetic field with number of permalloy layers

Without Permalloy Layers [μT] Single Layer [μT] Double Layers [μT]

5.0 3.3 2.2


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the study on corona & field effects in power System since 2005. Dr. Lim is a member of the KIEE(Korea Institute of Electrical Engineers) and IEEE.

Kooyong Shin was born in Kang-won, Korea on July 8, 1967. He received BS degree in Electrical Engineering from Dong-A University in 1991, and MS degree in electrical engineering from Kyung-Nam University in 1993. He joined Korea Electric Power Corporation in 1988 and has engaged in the study on corona & field effects in power System since 1993. Mr.Shin is a member of the KIEE(Korea Institute of Electrical Engineers).

Younghong Kim was born in Gyeonggi-do, Korea on August 14, 1979. He received BS degree and MS degree in Electrical Engineering from Hanyang University in 2006, and 2008 respectively. He worked in LS cable company from 2008 to 2010. And he joined KEPCO Research Institute in 2010 and has engaged in the study on electrical environment and transmission technology of HVDC T/L since 2010. Mr. Kim is a member of the KIEE(Korea Institute of Electrical Engineering).

Byeongyoon Lee received B.S, M.S and Ph.D degree in electrical engineering from Seoul national university in 1990, 1992, 1997 respectively. Since 1996, he has been with KERI, as a senior research engineer. His research interests are electromagnetic field analysis, protection technologies from transient electromagnetic phenomena and ion flow field analysis.

Sungho Myung received B.S, M.S and Ph.D degree in electrical engineering from Seoul national university in 1981, 1983, 1996 respectively. Since 1985, he has been with KERI. He is an executive manager of smart grid research division. His research interests include assessment of the electric and magnetic field (EMF) effects of electric power facilities and EMF mitigation design of transmission line.

Dissertations:[8] D. I. Lee, Environmental effects caused by corona

noise of 765 kV AC transmission line, ph. D thesis, Hanyang Univ., 1996.

Standards:[9] ICNIRP Guidelines, Guidelines for limiting

exposure to time-varying electric and magnetic fields (1Hz to 100kHz), 2010.

[10] ICNIRP Guidelines, Guidelines for limiting exposure to time-varying electric, magnetic, and electromagnetic fields (up to 300GHz), 1998.

9. Biographies

Dongil Lee was born Korea on March 15, 1958 and received Ph.D degree of Electrical Engineering from Hanyang University in 1996. He joined Korea Electric Power Corporation in 1978 and has engaged in the study on insulation coordination, corona & field effects in power system since 1984. He is a vice president of KIEE(Korean Institute of Electrical Engineers) since 2013 and a member of CIGRE in SC B2 working group from 2004 to 2010 and SC C3 since 2012.

Sangbeom Kim was born on May 21, 1963, in Korea. He received BS, MS, and PhD degrees in Inorganic Materials Science & Engineering from Seoul National University in 1986, 1988, and 1994, respectively. He joined Korea Electric Power Corporation in 1996. His research field covers assessment of HTLS (high temperature low sag) conductors and development of magnetic shielding technology using ferromagnetic materials.

Yunseog Lim was born in Kyung-ki, Korea on January 3, 1973. He received Ph.D degree in Electrical Engineering from Han-Yang University in 2005. He joined Korea Electric Power Corporation in 2005 and has engaged in

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