a study for hvdc transmission technology to connect power system of north-east asia

8/18/2019 A Study for HVDC Transmission Technology to Connect Power System of North-east Asia

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A Study for HVDC Transmission Technology to

Connect Power System of North-east Asia

Koo-yong Shin*, Young-hong Kim, Hee-won Noh, Dong-il Lee

■ Authors / Affiliations

- Corresponding Author: Koo-yong Shin

- Co-authors: Young-hong Kim, Hee-won Noh, Dong-il Lee

■ Contact details

- Koo-yong Shin(Chief of Engineering Specialist)

Address: Munji-Ro 105, Yuseong-Gu, Daejeon, Korea

Affiliations: Power System Lab. Of KEPCO Research Institute

Tel: +82-42-865-5853 / FAX: +82-42-865-5809

Cell Phone: +82-10-5679-2001

E-mail: [email protected]

- Young-hong Kim (Researcher)



Tel: +82-42-865-5857 / FAX: +82-42-865-5809

Cell Phone: +82-10-8949-3814


- Hee-won Noh (Researcher)


Affiliations: Power System Lab. Of KEPCO Research InstituteTel: +82-42-865-5856 / FAX: +82-42-865-5809

Cell Phone: +82-10-5360-3748


- Dong-il Lee (Vice president)



Tel: +82-42-865-5857 / FAX: +82-42-865-5809

Cell Phone: +82-11-9509-5883



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■ Executive SummaryRecently, demand of electric power has exceeded supply because of change of various conditions

related to electric power industry such as rise of generation cost, increase of demand caused by the

industrial development and abnormal temperature event. In Korea, daytime peak loads of summer,

winter has been occurring from some years ago.

Many countries has solved the lack of electric power by construction of nuclear power plant.However, there are plans to reduce or discard nuclear power plants scheduled or in operation since

Fukushima nuclear accident was happened. And lack of electric energy will be deepened continuously

without proper solution. To solve these, development of renewable energy such as wind, solar,

geothermal powers, a raise and diversifying of the electric power fee to control the demand and

electric power dealing between countries by power system connection were suggested.

In this paper, an application power system connection between countries to Korea was studied

because it is possible to solve peak load problem generated on the specific time or season and offer

efficiency use or sale of surplus electric power. The route from South Korea to Russia via North

Korea was estimated and selected considering distinct that Korea is divided countries. HVDC

transmission technology, 500kV voltage and 2 bi-pole were suggested to transfer electric power about

5% of electric power demand limited by energy security. 22m distance between poles and 18m height

of overhead line were applied to the test line in KEPCO PT Center and tested on the site. The test ofelectric environment was conducted during about 1 year. The result has showed that measurement

values satisfied the standard suggested by preceded research [1]. Through interrelation between

interferences and weather conditions, HVDC transmission line will be optimized to geographical and

climate conditions by analysis measured data.

■ Keyword: HVDC, North-East Asia, Electric Environment


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■ Main Text1. Introduction

The development of industrial civilization has come an exhaustion of natural resources and increase

of energy demand. And many transmission towers, substations and plants for electric power

generation and transmission have been constructed during the past century. Almost kinds of plant are

thermal plant using coal, oil and gas, hydroelectric power plant generated by height different of waterand nuclear power plant energized by atomic fission. In 2011, Fukushima nuclear accident was

happened by earth quake and wakened the world to dangerousness of nuclear power plant. Germany,

Swiss and Italy will phase out the nuclear and grow renewable energy such as wind and solar. Europe

has plans connecting power systems between members and constructing solar power and sunlight

generation plants to in the desert of Africa.

In Asia, several countries try to increase efficiency of power system and power plant. Japan make

an effort to import inexpensively energy such as gas and electric power by connection to Russia

through by gas pipe line and transmission line. The president of Softbank suggested the “Supergrid”

connecting power system between North and South Korea, China, Japan and Russia to exchange

electric power and economically manage the energy. China has plan to export and exchange electric

power by construction of large scale wind farm in the Gobi desert and Mongolia. In case of Korea,

there were discussions related to import natural gas from Russia through by North Korea. These policies and plans show that more efficient energy management is needed by power system

connection between countries.

In this paper, routes through North Korea area of transmission line considering power system

connection to Russia which has the lowest price of electric power and transmission type were

investigated and the development results of 500kv HVDC transmission technology.

2. Review of Transmission Capacity and Voltage

HVDC (High Voltage Direct Current) transmission technology is suitable to the power system

connection because the Power frequency is different of South/North Korea and Russia and

transmission distance is long. The technology has low transmission loss and is able to connect

between other frequency power systems.

Transmission power capacity was set 4~5GW below 5% of power demand for energy security. DC500kV equal voltage level to AC 765kV highest in Korea power system was applied to the line to

minimize the loss. When a conductor allowable current about 1kA is apply, power capacity of 6

bundles consisted by 480SQ or 520SQ overhead conductor is 5~6GW. Considering a half of

maximum capacity is transmitted in normal operation, 2 bi-pole was selected.

3. Selection of Transmission Line Route

The optimal route of transmission line is decided by various investigations such as restrictions, life

environment, natural environment and so on. However, there are many limits such as political,

economical and security characteristics because almost of the route of Korea-Russia passes North

Korea. And the investigations about natural environment, climate condition, economic feasibility and

so on were given more weight. Three routes for Korea-Russia transmission line was suggested as

shown in figure 1. The 1st route is from Kaesong to Hamheung via Wonsan near the East Sea. 2nd routeis similar to 1st route except via Pyongyang. 3rd Route is from Hoengseong to Wonsan via East Sea.

Table 1. Suggested Routes of Korea-Russia Transmission line

Area 1st Route 2nd Route 3rd Route

Russia Vladivostok ∼ Artem ∼ Khasan

NorthKorea

Hamgyeongbuk-do Najin ∼ Chongjin ∼ Hoemul ∼ Myoungchun ∼ Kilchu ∼ Kimchaek

Hamgyeongnam-do Tanchon ∼ Pukchong ∼ Hongwon ∼ Hamheung ∼ Kowon

Kangwon-do Wonsan∼Sepo∼ Ichon Yangdok ∼HuchangWonsan∼Tongchon∼Ko

song

Hwanghaebuk-do Ichon∼Hanpori∼Pyongsan

Pyongyang∼Sariwon -


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Kaesong-si Bakcheon∼Kaesong Pyongsan∼Kaesong -

South

Korea

Sindeokeun Kaesong∼Munsan Kaesong∼Munsan -

Sinpocheon Pocheon -

KangwonSwitching station

- -Kosong∼Yangyang~Inje

∼Hoengseong

T/L Length 1,009㎞ 1,070㎞ 1,030㎞

Also, the routes were considered to be parallel with Trans-Korea Railway that crosses the South

and North Korea and connects to Central Asia and Europe. The optimal route was selected by satellite

map and topographic map (1:50,000) to avoid high mountainous area and be close to an area

developed railroad, port and road. Overhead transmission line was considered to be less than 1,000m

and parallel to 220kV transmission line in operation near the coastline of the East Sea.

The overview of three routes is shown in table 1. There are many mountains and mountain chains

higher than 2,000m with Baekdu mountain as the center. The annual wind velocity is 2~3m/s. The

annual rainfall in Jangjeon area is the heaviest and snowfall is expected to be more than South Korea

because of northern regional characteristic. The route connected to Russia via Wonsan and Hamheung

was designed to be close the East Sea with separation distance more than 5km. Geographical andnatural environmental characteristics is summarized as shown in table 2.

Table 2. The main route overview of transmission line

Route

Overview of the route

Geographicalenvironment

Around ObstacleDistance

from coast

RussiaArtemKhasan

Urban areaAltitude 200~300m

Airport/Crossing Tumen riverContamination(Clean area)

5km~10km

North

Korea

Hamgyeongbuk-

do

NajinIndustrial area

Altitude 500~600mTransmission line in operation

Contamination(Clean area)5km~10km

ChongjinIndustrial area

Altitude 200~400m

Transmission line in operation /Crossing Nampuk river

Contamination(Clean area)

Within10km

KimchaekUrban area

Altitude 150~400mShoreline

Contamination(A area)Within 5km

Hamgye

ongnam-do

TanchonUrban and

Industrial area

Shoreline/Crossing Namhae river

Contamination(A area)Within 5km

HamheungUrban area

Altitude 150~400mTransmission line in operation Above 5km

KowonUrban area

Altitude 250~350mCrossing Dukji river and Salyeoul river Above 5km

Kangwon-do

Tongchon

Altitude above

1,000m

Railroad via northern East Sea

Via Mt. Geumgang Above 5km

Kosong ViaMt. BaekduCrossing the ceasefire line

Via military zoneWithin 5km

SepoAltitude above

1,000mCrossing the ceasefire line

Via military zoneCentralinland

Figure 1 shows longitudinal sections of suggested routes. Altitudes of 1 st route are less than 1,000m.

In 2nd route, Aobiryeong area is located above 1,000m. 3rd route passes mountain chain higher than

1,000m started from Mt. Baekdu. Almost areas from Russia to Hamheung are lower than 700m and a

route passing the coast to inland is rugged. Considering insulation coordination of transmission tower,

1st route located below 1,000m is suitable.


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(a) 1st route

(b) 2nd route

(c) 3rd route

Figure 1. Longitudinal sections of suggested routes


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Figure 2. Selected Route


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4. Insulation Coordination

For the design of 500kV HVDC transmission tower, insulation coordination was conducted with

follow two rules.

a.

Flashover is not generated by internal abnormal voltage of power system such as switching

voltage.

b.

Reliability has to be kept from external abnormal voltage such as lightning.

Withstand voltage characteristics and number of calculated insulators in contamination area are

shown in table 3 and 4.

Table 3. Withstand voltage characteristics of contamination area

Line typeDegree of pollution Clean Area

Contamination area

A B C D

ESDD [mg/cm2] Less than 0.03 0.063 0.125 0.25 0.5

Power line DC insulator (300kN) Anti-fog type 20.3 16.1 13.0 10.4 8.4

Neutral line AC insulator (300kN) Normal type 15.0 12.6 11.0 9.6 8.4

Table 4. Calculated Number of Insulator

Line typeDegree of pollution Clean Area

Contamination area

A B C D

ESDD [mg/cm2] Less than 0.03 0.063 0.125 0.25 0.5

Power line DC insulator (300kN) Anti-fog type 30 37 46 57 71

Neutral line AC insulator (300kN) Normal type 5 6 7 8 9

The route of North Korea is contamination area ‘A’ and 37 insulators and 7 are each applied to

power and neutral line. Gaps between arcing horns are 6,070mm for power line and 1,010mm for

neutral line when efficiency of arching horn is 75%. According to these results the air clearances of

swing angles are shown in table 5. Length of arm is 9.318m from tower body. In case of 1 bi-poletransmission line, considering tower width and length of arm, the distance from center of T/L to end

of an arm is about 11m and distance between two poles is 22m.

Table 5. Air clearance with swing angle

Line Type Insulator typeSwing angle

[degree]Case of clearance

Insulation distance

[mm]

Power

line

Suspension

15 Standard insulation distance 6,070

20 Minimum insulation distance 2,890

60 Abnormal insulation distance 1,300

Supporting/jumper


15 Minimum insulation distance 2,890

40 Abnormal insulation distance 1,300

Neutral

line

Suspension


20 Minimum insulation distance 260

60 Abnormal insulation distance 220

Supporting/

Jumper


15 Minimum insulation distance 260

40 Abnormal insulation distance 220


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Figure 3. Clearance of HVDC tower (Suspension type)

5. Electric Environmental Characteristics

The ground clearance determining height of tower is calculated by electric environmental standard.

Especially, it is close to civil complaints and has to be induced by field evaluation with various

conditions. In this study, ground clearance of test line was set 18m by preceded research results suchas interferences of various height of line [1]. Distance between poles was decided 22m by length of

arm. And 480SQ ACSR conductor was installed to the test line because smaller conductor has higher

electric field intensity of conductor surface.

5.1 Test Line

In this study, the world’s first commercial steel-tower-type test line that is adjustable to variable

pole locations was constructed the DC transmission demonstration test site in the Gochang Power

Testing Center in Korea, where the major performance levels of DC overhead transmission lines can

be investigated, considering the effective aspect of the operation of the test line. That is, the test

transmission line was composed to be used not only in electrical environment assessments but also in

the development of transmission line construction technologies and transmission line hardware by

attaching the line variable device on the test line of a commercial line type.The target operating voltage of the test line was set at ±500 kVdc with a bipolar horizontal 1-circuit,

and the length of the test line was designed to be the maximum in the test site. A total test line length

of 600 m was constructed with three spans: a 150m-long span for the bus line and the model span

between towers 1 and 2, a 300m-long span for the variable main test between towers 2 and 3, and a

150m-long span for the model span between towers 3 and 4, because it is preferable to have three

spans rather than a single span that is installed only at the dead-end steel tower when considering the

development of transmission line hardware. The test line of the commercial changeable tower has the

merits of more excellent functions in the aspects of the possible development of regular line design

technologies and the lower steel tower construction costs than the gantry type, although it has the

demerits of the exchange costs of the test conductors and the time consumption thereof.

Fig. 4 shows the aerial view of the Gochang ±500kVdc DC test line with two changeable towers. A

hoist with special arms, as shown in Fig. 5, was installed on top of the steel tower to make the polespacing variable between 7 to 14 m and to have the line height range from 13 to 22 m, as a method of


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changing the locations of the conductor to carry out the test in variable conditions.

Figure 4. Aerial view of the Gochang DC test line

(a) Tower No. 2 (b) Hoist

Figure 5. Tower 2 and hoist of the test line

5.2 Measuring Equipment and DAS

The corona and ion flow environmental interference measurement system and DAS were designed

considering the required functions of the synthetic investigation and analysis of the environmental

effects of the DC transmission line. A number of measurement sensors were installed around the mid-

span between towers 2 and 3 of the test line, and the data were stored according to the interferences at

the DAS server every 10 seconds. The measurement hardware that collected the data was composed

based on the distributed control system. The disturbance countermeasures were considered as the

signals detected by each measurement sensor were transmitted to the control room that was more than

about 100 m away. Therefore, the UTP cables were mainly used for easier handling in long-distance

data signal transmission.

The ion flow was measured within an about 1.5-fold distance of the line height and up to twofold in

severe winds to the lateral direction of the test line [9]. Therefore, the sensors were allocated as shown

in Fig. 6, considering that the sensors were 30 m from the test line with the line height of 18 m

showed very low measurement values or detected ambient noises. The distance between the sensors

was set at around 8 m to avoid interruptions between the ion flow interference measurement sensors.Table 6 shows the status of the interference items and measurement sensors that were applied at the

Gochang DC transmission test site. Fig. 6 shows the test site and the various sensors installed.

Table 6. Status of the measurement sensors at the Gochang DC transmission test site

Location Measurement Items Number of Ch. Note

Positive

Radio Noise 4

Audible Noise 4

Charged Voltage(Disk) 4 10GΩ×3, 100GΩ×1

Ion Current Density 4

Electric Field 4

CenterIon Current Density 1

Electric Field 1

Negative

Charged Voltage(Disk) 7 10GΩ×5, 100GΩ×2

Charged

Voltage(Cylinder)3 10GΩ1, 100GΩ×2

Ion Current Density 6

Electric Field 4

Meteorological Factors 12

Temperature, Wind direction, Wind

velocity, Humidity, Rain and Atmospheric

PressureSum 56


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Figure 6. Measurement sensors of the DC test yard

5.3 Experiment Results

The electrical environment interferences of the 480mm2(C)x6B conductor bundle were assessed by

measuring the interference quantity caused by the corona and ion flow for about a year, through the

operation of the ±500kV on the bipolar 1-circuit with the line height of 18 m and the pole spacing of

22 m.

5.3.1 Electric Field Intensity on the Ground

The electric field intensity on the ground was measured by installing nine units of the DC electric

field meter (BOLTEK, EFM100) vertical to the test line on the ground to detect the lateral profiles

according to the distance from the test line. Fig. 7 shows the statistical results of the data that were

measured for a year directly under the positive and negative poles of the DC transmission test line.

Fig. 8 shows the lateral profiles of the electric field intensity according to the distance. The maximum

value of the electric field intensity on the ground was shown in the surrounding area directly under

each conductor of the pole and was reduced to about 0.3~0.5 kV/m for every 1m increase in the

distance from the test line of each pole.

Figure 7. Cumulative distributions of the electric

field intensity on the ground under the

test line

Figure 8. Lateral profiles of the electric field

intensity on the ground

The electric field intensity on the ground around the DC overhead transmission line varied

according to the weather conditions such as the wind velocity and humidity, among which the wind

velocity had the greatest effect [10]-[13]. The wind direction and velocity were assessed by analyzing

the data from the case in which the wind blew towards the vertical direction to the test line, as shown

in Fig. 9. The wind direction of 25 º from left to right vertical to the test line was chosen for the

analysis of the data for the determination of the electric field intensity on the ground in the wind

vertical to the test line. Fig. 10 shows the results of the analysis of the case with the wind direction

from the positive pole to the negative pole. In the case of the wind velocity at less than 1 m/s that had

almost no wind, the electric field intensity on the ground appeared to have had similar absolute values

simply opposite the symbols around the ground surfaces of the positive line and the negative line; but

in the case with the wind velocity 5 m/s and higher, the intensity on the ground of the positive lineappeared smaller than that in the case with no wind, and the maximum value of the negative line was

detected not directly under the line but as moving in the wind movement direction. Fig. 11 shows the

0

25

50

75

100

-40 -30 -20 -10 0 10 20 30

Electric Field [kV/m] .

P r o b a b i l i t y ,

Positive Pole

Negative Pole


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result of the case in which the wind blew from the negative pole to the positive pole.

The results of the statistical process of the productions according to the temperature, humidity and

rainfall intensity, using the electric field meter directly under the positive pole to assess the generation

characteristics of the electric field intensity according to the changes of weather condition, showed

that the electric field intensity on the ground tended to slightly decrease as the temperature increased.

The electric field intensity tended to significantly increase when the humidity increased; therefore, the

humidity changes were confirmed as important meteorological factors of the electric field intensity on

the ground.

Figure 9. Wind direction at the Gochang DC test line

Figure 10. Electric field intensity on the groundaccording to the wind speed in the

case with the wind blowing from the

positive pole

Figure 11. Electric field intensity on the groundaccording to the wind speed in the

case with the wind blowing from the

negative pole

5.3.2 Charged Voltage

To investigate the characteristics of the charged voltage generated in the surrounding charged body

by the ion from the corona discharge of the DC overhead transmission line, the charged bodies with

10GΩ and 100GΩ resistance values were manufactured to measure the charged voltages. Fig. 12

presents the lateral profile of the charged voltage from the DC test line. The absolute values of the

charged voltages according to the polarity in both the left and right sides of the transmission line

appeared almost identical and were recognized to have been produced directly under each pole.

Figure 12. Lateral profiles of the charged voltage by 10 G around the test line

The charged voltage was measured in the long term to assess the generation characteristics of the

Tower #2 Tower #3

Wind Direction 110o

~ 160o

Wind Direction 290o

~ 340o

(+)

(-)


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charged voltages from the DC line according to the weather conditions. The statistical results showed

that the voltage hardly differed with the changes in the temperature and the rainfall intensity, but

slightly decreased with the humidity increase.

5.3.3 Ion Current Density on the Ground

The ion current density on the ground was measured with 11 units of plate-type electrodes that had

guard electrodes on the ground surface and that were installed vertical to the test line to detect the

lateral profile according to the distance from the line. Fig. 13 shows the results of the statistical

process for the ion current density on the ground.

Figure 13. Lateral profile of the ion current

density, L50% on the groundFigure 14. Lateral profile of the ion current

density according to the wind speed

in the case with the wind blowing

from the positive pole

Fig. 15 shows the results of the measurement of the ion current density with a wind velocity of 3 m/s

and above and with almost no wind, to assess the wind influence. The analysis results showed the

amount of the interference for the upstream wind tended to decrease, and that for the downstream

wind tended to increase.

The results of the statistical process for the generation amounts according to the temperature and

the humidity showed generation characteristics that were similar to those of the charged voltagedirectly under the positive pole in the assessment of the generation characteristics of the ion current

density on the ground according to the weather conditions at the DC test line.

5.3.4 Radio Noise

The IEEE standard loop antenna (Rohde& Schwarz, HFH2-Z2) for the measurement of the radio

interference was installed 2 m above the ground. A non-radio frequency was selected within the range

of 0.5±0.1 MHz [14]-[15]. The lateral profile of the test line was apprehended by installing four units

of antennas vertical to the test line. The ambient noise of the test yard was measured to have been

about 38~42 dB (µV/m). The radio interferences generated from the test line were assessed at the

standard position 15 m to the vertical direction directly under the positive pole. Fig. 15 shows the

results of the statistical process for the radio noise measured at the assessment position. The corona

discharges, which were produced according to various surrounding conditions in fair weather, showed

an about 15dB difference between the maximum and minimum values, as presented in Fig. 15; and

the difference in the foul weather appeared to have been the same as that in the fair weather because

the foul weather was more stable than the fair weather.

The radio noise produced in foul weather was the same as that in fair weather in the DC

transmission line, unlike in the AC transmission line; but the L50% value of the radio noise appeared

to have been about 3 dB larger than that in fair weather, as shown in Fig. 15. This was considered to

have been the value within the measurement errors of the measurement device and because the

measurement period did not have many rainfall conditions; but it was confirmed to correspond with

the theory that the radio noise caused by the corona discharge in foul weather will be the same as that

in fair weather according to the DC corona discharge characteristics.


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Figure 15. Characteristics of the radio noise

generation according to the weather

condition

Figure 16. Characteristics of the radio noise

generation according to the wind

speed in the case with the wind

blowing from the negative pole

The assessment of the radio noise generation characteristics at the assessment positions according

to the weather conditions showed a tendency to slightly increase within 10~30°C as the temperatureincreased, and to decrease when the humidity increased. Therefore, the DC transmission line produced

more radio noise in fair weather with lower humidity. Moreover, much less radio noise appeared to

have been produced with heavier rain and increased rainfall intensity.

When the wind direction and velocity changed, the result of the statistical process for the radio

noise for the assessment of the radio noise characteristics produced from the DC test line when the

wind direction was from the positive pole to the negative pole was about 2 dB higher than that in the

opposite wind direction. This is considered to have been due to the increase in the radio noise as the

wind velocity increased, as shown in Fig. 16, because the corona discharge characteristics could be

more actively generated from the line conductor according to the wind direction and velocity

conditions.

5.3.5 Audible NoiseThe lateral profile of the test line was apprehended by installing four units of microphones (Bruel &

Kjaer, Type 4184) vertical to the test line. The audible noise generated from the test line was assessed

at the standard position 15 m to the vertical direction directly under the positive pole. Table 7 shows

the results of the statistical process for the audible noise.

Table 7. Audible noise from the ±500kV DC test transmission line

Sensor AN1 AN2 AN3 AN4

Distance from center line, m 14 26 46 110

L50 , dBA 40.2 40.6 40.3 41.4

L5, dBA 45.9 46.7 46.0 48.6


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■ Conclusions and Relevant ImplicationsIn this study, optimal route connect South Korea to Russia via North Korea was suggested by the

estimation of various conditions. It is important because the route will be a part of North-East Asia

transmission line such as Japan-Korea-China-Russia route. The results of estimation of power

capacity and insulation coordination showed that suitable voltage, circuit number and distance

between poles are each 500kV, 2-Bipole and 22m. The height of overhead line was 18m suggested by preceded research [1].

The results of the electrical environment full-scale test that was conducted by composing the

Gochang DC test transmission line with the pole spacing of 22 m apart showed that the 18m line

height above the ground, the bipolar 1-circuit, the 480mm2(C)x6B conductor bundle, and the

establishment of the test voltage at ±500 kV were the key characteristics of each environmental

interference. They are presented as follows and summarized in Table 8.

1. Among the weather conditions that affected the electrical environment interferences produced

from the DC overhead transmission line, the wind influence appeared to have been the most dominant.

2. In the case of the electric field intensity, charged voltage, ion current density and radio noise, the

production amount according to the wind condition showed a significant increase and decrease in

characteristics. The amount of the interference for the upstream wind tended to decrease and that for

the downstream wind, to increase.3. The interrelations of the environmental interferences affected by the temperature changes

appeared insignificant. The electric field intensity decreased when the temperature increased, but the

radio noise emission amount increased. The temperature changes were considered to have generally

not seriously affected the environmental interference production amount because the production

amounts of the other environmental interferences remained almost unchanged.

4. The electric field intensity increased only when the humidity increased, whereas the production

amounts of the other interference items decreased. Therefore, a higher humidity could be considered

somewhat advantageous in the electrical environment aspect of the HVDC overhead transmission line.

The rainfall intensity produced weaker environmental interferences as the rainfall increased due to its

strong inversely proportional characteristics.

5. The basic data that could be used in the prediction of the electrical environment interference

level and the decision on the transmission line height above the ground of future commercialtransmission lines were obtained by understanding the changes in the various environmental

interference amounts according to the changes in the line height above the ground.

Table 9 shows the results of comprehensive assessments of the ±500kV DC test transmission line.

The guidelines are the DC transmission line design criteria in KEPCO (Korea Electric Power Co.).

Table 8. Summary of the results of the electrical environmental full-scale test at the ±500kV DC

Gochang test transmission line

Interferences

Conditions

Electric Field

Intensity

(kVdc/m)

Charged Voltage

(kVdc, 100 GΩ)

Ion current

density (nA/m2)

Radio noise dB

(µV/m), L50%

Productionquantity

Fair －25 ~ ＋23 -50 ~ ＋110 40.0 －20 ~ ＋15Foul - - 43.01 -

Wind influence Yes Yes Yes Yes

Wind velocity influence Yes Yes Yes Yes

Temperature influenceYes (inversely

proportional) No No Yes (proportional)

Moisture influence Yes (proportional)Yes (inversely

proportional)

Yes (inversely

proportional)

Yes (inversely

proportional)

Rainfall intensity

influence No

Yes (inversely

proportional)-

Yes (inversely

proportional)

Table 9. Summary of the assessment of the long-term environmental full-scale test at the ±500kV DCtest transmission line


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Interference Measurement Guideline Assessment

Electric field (kVdc/m) 18.42 Below 25 Satisfactory

Radio interference dB(µV/m) SNR 31 Above SNR 24 Satisfactory

Audible noise [dB (A)] 40.6 Below 50 Satisfactory

Ion current density (nA/m2) 95.7 Below 100 Satisfactory

■ References

[1] D.I. Lee, K.Y. Shin, J.S. Lim, K.H. Yang, M.N. Ju, B.H. Son, Y.E. Park, "Development of Design

and Core Technologies for HVDC Overhead Transmission Line”, Final Report, Mar. 2010.

[2] P. S. Maruvada, R. D. Dallaire, P. Hēroux, N. Rivest, "Corona Studies for Bipolar HVDC

Transmission at Voltages Between ±600kV and ±1200kV; PART2: Special Bipolar Line, Bipolar

Cage and Bus Studies" IEEE Trans. on pas, Vol. Pas-100, No. 3 March 1981

[3] Yukio Nakano, Mitsuo Fukushima, "Statistical Audible Noise Performance of Shiobara HVDC

Test Line" IEEE Transactions on Power Delivery, Vol. 5, No. 1, January 1989

[4] P. S. Maruvada, R. D. Dallaire, "Environmental Effects of the Nelson River HVDC Transmission

Line - RI, AN, Electric Field, Induced Voltage, and Ion Current Distribution Tests" IEEE Trans.on pas, Vol. Pas-101, No. 4 April 1982

[5] Tomotaka Suda, Yoshitaka Sunaga, "An Experimental Study of Large Ion Density under the

Shiobara HVDC Test Line" IEEE Transactions on Power Delivery, Vol. 5, No. 3, July 1990

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HVDC Test Line" IEEE Transactions on Power Delivery, Vol. 3, No. 4, October 1988

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[15] Wan Baoquan, Liu Dichen, Wu Xiong, Lu Yao, "The study on the radio interference from

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Technology

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Transmission Lines", Final Report of CIGRE, August-5-2010

a study for hvdc transmission technology to connect power system of north-east asia

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