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  1. (Dept. of Energy Engineering, Korea Institute of Energy Technology (KENTECH), Naju, Republic of Korea.)



Reactive Power Planning, Grid code, Offshore Wind Farm

1. ์„œ ๋ก 

์„ธ๊ณ„์ ์ธ ๊ธฐํ›„ ์œ„๊ธฐ๋กœ ์‹ ์žฌ์ƒ์—๋„ˆ์ง€์›์— ๋Œ€ํ•œ ๊ด€์‹ฌ์ด ์ง‘์ค‘๋˜๊ณ  ์žˆ๋‹ค. ๊ธฐ์กด ์ „๋ ฅ ๊ณ„ํ†ต์— ์‹ ์žฌ์ƒ์—๋„ˆ์ง€ ๋ฐœ์ „์›์˜ ์ ‘์†์ด ์ฆ๊ฐ€ํ•˜๊ณ  ์žˆ๊ณ , ๋Œ€ํ‘œ์ ์ธ ์˜ˆ๋กœ๋Š” ํ’๋ ฅ๋ฐœ์ „์ด ์žˆ๋‹ค. ์œก์ƒ ํ’๋ ฅ๋ฐœ์ „์›์˜ ๊ฒฝ์šฐ ๊ทธ ๊ทœ๋ชจ๊ฐ€ ์ปค์ง์— ๋”ฐ๋ผ ์„ค์น˜ ๊ณต๊ฐ„์˜ ์ œ์•ฝ๊ณผ ์†Œ์Œ ๋ฌธ์ œ ๋“ฑ์œผ๋กœ ์ธํ•œ ์ œ์•ฝ์ด ๋งŽ์ง€๋งŒ, ๋Œ€๊ทœ๋ชจ ํ•ด์ƒํ’๋ ฅ๋‹จ์ง€๋Š” ํƒ„์†Œ ์ค‘๋ฆฝ ๋‹ฌ์„ฑ์„ ์œ„ํ•œ ํ•ด๊ฒฐ์ฑ…์ด์ž, ํ•ด์ƒ์— ์„ค์น˜๋˜์–ด ๊ณต๊ฐ„ ์ œ์•ฝ์ด ์ ๊ณ  ์†Œ์Œ ๋ฌธ์ œ๋„ ํ•ด๊ฒฐํ•  ์ˆ˜ ์žˆ๋‹ค๋Š” ์ ์—์„œ ์ „ ์„ธ๊ณ„์ ์œผ๋กœ ์ฃผ๋ชฉ๋ฐ›๊ณ  ์žˆ๋‹ค[1,2]. ์ด์— ๋ฐœ๋งž์ถ”์–ด ๊ตญ๋‚ด์—์„œ๋„ ์„œํ•ด์™€ ๋‚จํ•ด๋ฅผ ์ค‘์‹ฌ์œผ๋กœ ๋Œ€๊ทœ๋ชจ ํ•ด์ƒํ’๋ ฅ๋‹จ์ง€ ๊ฑด์„ค ๊ณ„ํš์„ ์ˆ˜๋ฆฝํ•˜๊ณ  ์žˆ์œผ๋ฉฐ, ์ด๋ฅผ ํ†ตํ•ด ์‹ ์žฌ์ƒ์—๋„ˆ์ง€ ํ™•๋Œ€ ๋ชฉํ‘œ์™€ ํƒ„์†Œ ์ €๊ฐ ๋ชฉํ‘œ๋ฅผ ์‹คํ˜„ํ•˜๊ณ ์ž ํ•˜๊ณ  ์žˆ๋‹ค.

ํ•ด์ƒํ’๋ ฅ๋‹จ์ง€์—์„œ ์ƒ์‚ฐ๋˜๋Š” ํ’๋ ฅ ์—๋„ˆ์ง€๋Š” ํ™˜๊ฒฝ ์นœํ™”์ ์ธ ์ž์›์œผ๋กœ, ๊ธฐํ›„ ๋ณ€ํ™” ๋Œ€์‘๊ณผ ์ง€์† ๊ฐ€๋Šฅํ•œ ์—๋„ˆ์ง€ ๊ณต๊ธ‰์—์„œ ์ค‘์š”ํ•œ ์—ญํ• ์„ ํ•˜๊ณ  ์žˆ๋‹ค. ๊ทธ๋Ÿฌ๋‚˜ ๊ฐ„ํ—์ ์ด๋ฉฐ ๋ฐ”๋žŒ์˜ ์„ธ๊ธฐ๋‚˜ ๋ฐฉํ–ฅ์„ ์ œ์–ดํ•  ์ˆ˜ ์—†๋Š” ํŠน์„ฑ ๋•Œ๋ฌธ์— ์ „๋ ฅ๋ง ์šด์˜์— ๋ถˆ์•ˆ์ •์„ฑ์„ ์ดˆ๋ž˜ํ•  ์ˆ˜ ์žˆ๋‹ค. ๋˜ํ•œ, ํ•ด์ƒ ํ’๋ ฅ ๋ฐœ์ „์†Œ์˜ ๊ทœ๋ชจ๊ฐ€ ์ปค์ง์— ๋”ฐ๋ผ ์ค‘์ „์•• ์ „๋ ฅ๋ง์— ๊ตญํ•œ๋˜์ง€ ์•Š๊ณ , ๊ณ ์ „์••(HV) ๋ฐ ์ดˆ๊ณ ์••(UHV) ์ „๋ ฅ๋ง์— ํ†ตํ•ฉ๋˜๋Š” ์ถ”์„ธ๊ฐ€ ๋šœ๋ ทํ•ด์ง€๊ณ  ์žˆ๋‹ค. ํ’๋ ฅ ๋ฐœ์ „์˜ ๋น„์œจ์ด ๋†’์•„์ง€๋ฉด์„œ ์ „๋ ฅ๋ง ์šด์˜์—์„œ๋Š” ์ถœ๋ ฅ ๋ณ€๋™๊ณผ ๊ฐ™์€ ๋ถˆํ™•์‹ค์„ฑ์„ ๊ด€๋ฆฌํ•ด์•ผ ํ•˜๋Š” ๊ณผ์ œ๊ฐ€ ๋ฐœ์ƒํ•˜๋ฉฐ, ์ด๋กœ ์ธํ•ด ์ „๋ ฅ๋ง์˜ ์šด์˜ ๋ณด์•ˆ์„ ํ™•๋ณดํ•˜๊ณ  ์•ˆ์ •์ ์ธ ์ „๋ ฅ ๊ณต๊ธ‰์„ ์œ ์ง€ํ•˜๊ธฐ ์œ„ํ•œ ๊ธฐ์ˆ ์  ๋ฌธ์ œ๋“ค์ด ๋ณต์žกํ•ด์ง€๊ณ  ์žˆ๋‹ค. ์ด๋Ÿฌํ•œ ๋ณ€๋™์„ฑ์„ ์™„ํ™”ํ•˜๊ณ  ๊ธ‰๊ฒฉํ•œ ์ถœ๋ ฅ ๋ณ€ํ™”๋ฅผ ์˜ˆ์ธกํ•˜์—ฌ ๋Œ€์‘ํ•  ์ˆ˜ ์žˆ๋Š” ๊ธฐ์ˆ ์  ๋ฐฉ์•ˆ์ด ํ•„์ˆ˜์ ์ด๋‹ค. ๋”ฐ๋ผ์„œ ๋†’์€ ํ’๋ ฅ ๋ฐœ์ „ ๋น„์œจ์„ ์ˆ˜์šฉํ•  ์ˆ˜ ์žˆ๋Š” ์ „๋ ฅ๋ง ์‹œ์Šคํ…œ์˜ ์•ˆ์ •์„ฑ์„ ๊ฐ•ํ™”ํ•˜๊ธฐ ์œ„ํ•œ ์—ฐ๊ตฌ๊ฐ€ ํ™œ๋ฐœํžˆ ์ง„ํ–‰ ์ค‘์ด๋ฉฐ, ์ฃผํŒŒ์ˆ˜ ์กฐ์ •, ์ „์•• ์ œ์–ด, ์ถœ๋ ฅ ์˜ˆ์ธก ๊ธฐ์ˆ  ๋“ฑ์˜ ์ค‘์š”ํ•œ ์—ฐ๊ตฌ๋“ค์ด ์ „ ์„ธ๊ณ„์ ์œผ๋กœ ์ง„ํ–‰๋˜๊ณ  ์žˆ๋‹ค[3]. ๋งˆ์ฐฌ๊ฐ€์ง€๋กœ ๊ตญ๋‚ด์—์„œ๋„ ๋Œ€๊ทœ๋ชจ ํ•ด์ƒํ’๋ ฅ๋‹จ์ง€์˜ ์ ‘์†์„ ์œ„ํ•œ ๊ธฐ์ˆ ์ ์ธ ๊ทœ์ •๊ณผ ๊ธฐ์ค€์ด ๋งˆ๋ จ๋˜์–ด ์žˆ์œผ๋ฉฐ, ์ด๋ฅผ ๊ณ„ํ†ต์— ์ ‘์† ์‹œ ๋”ฐ๋ฅด๋„๋ก ํ•˜๊ณ  ์žˆ๋‹ค. ํ•ด์ƒํ’๋ ฅ๋ฐœ์ „๋‹จ์ง€์˜ ๊ณ„ํ†ต ์—ฐ๊ณ„ ์‹œ, AC ์™ธ๋ถ€๋ง ํ•ด์ €์ผ€์ด๋ธ”์˜ ๋ฌดํšจ์ „๋ ฅ ๋ณด์ƒ ๋ฐฉ์•ˆ[4]๊ณผ ํ•ด์ƒํ’๋ ฅ๋‹จ์ง€ ์—ฐ๊ณ„ ๊ณ„ํ†ต ๋ฌดํšจ์ „๋ ฅ ๋ณด์ƒ๋Ÿ‰ ์‚ฐ์ • ๋ฐฉ์•ˆ์€ ์ œ์‹œ๋˜์–ด ์žˆ๋‹ค[5].

๋ณธ ๋…ผ๋ฌธ์—์„œ๋Š” โ€˜์‹ ์žฌ์ƒ๋ฐœ์ „๊ธฐ ์†ก์ „๊ณ„ํ†ต์—ฐ๊ณ„ ๊ธฐ์ˆ ๊ธฐ์ค€โ€™์— ๋”ฐ๋ผ ๋Œ€๊ทœ๋ชจ ํ•ด์ƒํ’๋ ฅ๋‹จ์ง€๊ฐ€ ์ ‘์†ํ•˜๊ธฐ ์œ„ํ•œ ๋ฌดํšจ์ „๋ ฅ ๋ณด์ƒ๋Ÿ‰ ๊ฒฐ๊ณผ๋ฅผ ์ œ์‹œํ•˜๊ณ , ๋ฌดํšจ์ „๋ ฅ ๋ณด์ƒ๋Ÿ‰ ๊ธฐ์ค€์  ์ฐจ์ด์— ๋”ฐ๋ฅธ ๋ฌดํšจ์ „๋ ฅ ๋ณด์ƒ๋Ÿ‰ ๋น„๊ต ๊ฒฐ๊ณผ๋ฅผ ์ œ์‹œํ•œ๋‹ค. ๋˜ํ•œ, ๋ฌดํšจ์ „๋ ฅ ๋ณด์ƒ๋Ÿ‰ ์‚ฐ์ • ๋ฐฉ์•ˆ์— ๋”ฐ๋ผ ํ•„์š”ํ•œ ๋ณ‘๋ ฌ ๋ฆฌ์•กํ„ฐ์™€ STATCOM ์„ค๋น„์šฉ๋Ÿ‰์„ ๊ฐ๊ฐ ์ œ์‹œํ•œ๋‹ค. ํ•ด์ƒํ’๋ ฅ๋‹จ์ง€ ๊ฒ€ํ†  ์‚ฌ๋ก€ ์—ฐ๊ตฌ๋Š” ์ „๋ ฅ๊ณ„ํ†ต ํ•ด์„ ํ”„๋กœ๊ทธ๋žจ์ธ PSS/E ํ”„๋กœ๊ทธ๋žจ์„ ํ™œ์šฉํ•˜์˜€๋‹ค.

์ œ2์žฅ์—์„œ๋Š” ์šฐ๋ฆฌ๋‚˜๋ผ ์‹ ์žฌ์ƒ๋ฐœ์ „๊ธฐ ์—ฐ๊ณ„ ๊ธฐ์ค€๊ณผ ํ•ด์ƒํ’๋ ฅ๋‹จ์ง€ ์‹œ๋ฎฌ๋ ˆ์ด์…˜์„ ์œ„ํ•œ ์‹œ์Šคํ…œ์˜ ๊ตฌ์„ฑ ๋ฐ ๋ฌดํšจ์ „๋ ฅ ๋ณด์ƒ๋Ÿ‰ ์‚ฐ์ • ๋ฐฉ์•ˆ์„ ์†Œ๊ฐœํ•œ๋‹ค. ์ œ3์žฅ์—์„œ๋Š” PSS/E๋ฅผ ์‚ฌ์šฉํ•˜์—ฌ ์‚ฌ๋ก€๋ณ„ ๋ฌดํšจ์ „๋ ฅ๋Ÿ‰์„ ๊ณ„์‚ฐํ•˜์—ฌ ๋ฌดํšจ์ „๋ ฅ ๋ณด์ƒ ์„ค๋น„์šฉ๋Ÿ‰์„ ์‚ฐ์ •ํ•œ๋‹ค. ์ œ4์žฅ์—์„œ๋Š” ๊ฒฐ๋ก ์„ ์ •๋ฆฌํ•˜์˜€๋‹ค.

2. ๋ณธ ๋ก 

2.1 ํ•ด์ƒํ’๋ ฅ๋‹จ์ง€์˜ ๊ณ„ํ†ต์—ฐ๊ณ„ ๊ทœ์ • ๋‚ด์šฉ

์šฐ๋ฆฌ๋‚˜๋ผ์—์„œ ๋Œ€๊ทœ๋ชจ ํ•ด์ƒํ’๋ ฅ๋‹จ์ง€๊ฐ€ ์ ‘์†ํ•˜๊ธฐ ์œ„ํ•ด์„œ๋Š” ์‹ ์žฌ์ƒ๋ฐœ์ „๊ธฐ์˜ ์†ก์ „๊ณ„ํ†ต์— ์—ฐ๊ณ„ ์‹œ ์—ฐ๊ณ„ ๊ธฐ์ค€์„ ๋”ฐ๋ฅด๋„๋ก ํ•˜๊ณ  ์žˆ๋‹ค[6]. ๊ธฐ์ค€์— ์˜ํ•˜๋ฉด ํ•ด์ƒํ’๋ ฅ๋‹จ์ง€๊ฐ€ ์œก์ง€๊ณ„ํ†ต๊ณผ ์—ฐ๊ณ„๋˜๋Š” ๊ฒฝ์šฐ ์šด์ „์ „์•• ๋ฒ”์œ„ ๋‚ด์—์„œ <๊ทธ๋ฆผ 1>๊ณผ ๊ฐ™์ด ํ•ด์ƒํ’๋ ฅ๋‹จ์ง€ ์œ ํšจ์ „๋ ฅ ์ถœ๋ ฅ์— ๋”ฐ๋ฅธ ๋ฌดํšจ์ „๋ ฅ ๊ณต๊ธ‰๋Šฅ๋ ฅ์„ ๋ณด์œ ํ•˜์—ฌ์•ผ ํ•œ๋‹ค๊ณ  ๋ช…์‹œํ•˜๊ณ  ์žˆ๋‹ค. ๋˜ํ•œ, ์‹ ์žฌ์ƒ๋ฐœ์ „๊ธฐ๊ฐ€ <๊ทธ๋ฆผ 1>์˜ ๋ฌดํšจ์ „๋ ฅ ๊ณต๊ธ‰๋Šฅ๋ ฅ์„ ๊ฐ–์ถ”๊ธฐ ์–ด๋ ค์šด ๊ฒฝ์šฐ ๋ณ„๋„์˜ ์ˆœ๋™๋ฌดํšจ์ „๋ ฅ๋ณด์ƒ์žฅ์น˜๋ฅผ ๊ฐ–์ถ”์–ด์•ผ ํ•œ๋‹ค๊ณ  ๋ช…์‹œํ•˜๊ณ  ์žˆ๋‹ค. ์‹ ์žฌ์ƒ๋ฐœ์ „๊ธฐ ์†ก์ „๊ณ„ํ†ต์—ฐ๊ณ„ ๊ธฐ์ˆ ๊ธฐ์ค€ 2์žฅ 7์žฅ์˜ ์„ธ๋ถ€๋‚ด์šฉ์€ ๋‹ค์Œ๊ณผ ๊ฐ™๋‹ค.

๊ฐ€) ์‹ ์žฌ์ƒ๋ฐœ์ „๊ธฐ๋Š” ์šด์ „์ „์•• ๋ฒ”์œ„ 90~110% ๋‚ด์—์„œ ๊ทธ๋ฆผ 1๊ณผ ๊ฐ™์ด ์œ ํšจ์ „๋ ฅ ์ถœ๋ ฅ์— ๋”ฐ๋ฅธ ๋ฌดํšจ์ „๋ ฅ ๊ณต๊ธ‰๋Šฅ๋ ฅ์„ ๋ณด์œ ํ•˜์—ฌ์•ผ ํ•จ

๋‚˜) ๋ฐœ์ „๊ธฐ ์œ ํšจ์ „๋ ฅ 20%~100% ์ถœ๋ ฅ ์‹œ ์œ ํšจ์ „๋ ฅ ์ •๊ฒฉ์šฉ๋Ÿ‰ ๋Œ€๋น„ 33%์˜ ๋ฌดํšจ์ „๋ ฅ์„ ํก์ˆ˜ ๋˜๋Š” ๊ณต๊ธ‰

๋‹ค) ๋ฐœ์ „๊ธฐ ์œ ํšจ์ „๋ ฅ 20%~0% ์ถœ๋ ฅ ์‹œ ์œ ํšจ์ „๋ ฅ ์ถœ๋ ฅ๊ฐ์†Œ์— ๋”ฐ๋ผ ์„ ํ˜•์ ์œผ๋กœ ๊ณต๊ธ‰๋Šฅ๋ ฅ ๊ฐ์†Œ

๋ผ) ๋ฌดํšจ์ „๋ ฅ์— ๋Œ€ํ•œ ์ •์ƒ์ƒํƒœ ํ—ˆ์šฉ์˜ค์ฐจ๋Š” 5% ์ดํ•˜์—ฌ์•ผ ํ•จ

๋งˆ) ์‹ ์žฌ์ƒ๋ฐœ์ „๊ธฐ๊ฐ€ <๊ทธ๋ฆผ 1>์—์„œ ์ •ํ•œ ๋ฌดํšจ์ „๋ ฅ์„ ๊ณต๊ธ‰ํ•˜๊ธฐ ์–ด๋ ค์šด ๊ฒฝ์šฐ ์ˆœ๋™๋ฌดํšจ์ „๋ ฅ๋ณด์ƒ์žฅ์น˜๋ฅผ ๊ตฌ๋น„ํ•˜์—ฌ ๋ฌดํšจ์ „๋ ฅ์„ ๊ณต๊ธ‰ํ•˜์—ฌ์•ผ ํ•จ

๊ทธ๋ฆผ 1. ์œ ํšจ์ „๋ ฅ ์ถœ๋ ฅ์— ๋”ฐ๋ฅธ ๋ฌดํšจ์ „๋ ฅ ๊ณต๊ธ‰๋Šฅ๋ ฅ ๋ฒ”์œ„[6]

Fig. 1. The range of reactive power capability with respect to active power output

../../Resources/kiee/KIEE.2025.74.2.238/fig1.png

๋˜ํ•œ, ์—ฐ๊ณ„๊ธฐ์ˆ  ๊ธฐ์ค€์—์„œ ์‹ ์žฌ์ƒ๋ฐœ์ „๊ธฐ ์†ก์ „๊ณ„ํ†ต ์—ฐ๊ณ„ ์‹œ ๋ฌดํšจ์ „๋ ฅ ๊ณต๊ธ‰๋Šฅ๋ ฅ ํ‰๊ฐ€ ๊ธฐ์ค€์ ์— ๋Œ€ํ•œ ๋‚ด์šฉ์ด ์ •์˜๋˜์–ด ์žˆ๋‹ค. ๋ฌดํšจ์ „๋ ฅ ๊ณต๊ธ‰๋Šฅ๋ ฅ ํ‰๊ฐ€ ๊ธฐ์ค€์ ์„ ์—ฐ๊ณ„์ ์œผ๋กœ ์ •์˜ํ•˜๊ณ  ์žˆ๋Š”๋ฐ, ์ด๋Š” ๊ณต์šฉ์†ก์ „๋ง ๋˜๋Š” ๊ณต์šฉ๋ฐฐ์ „์„ค๋น„๊ฐ€ ์—ฐ๊ฒฐ๋˜๋Š” ์ง€์ ์„ ๋งํ•œ๋‹ค. ์ฆ‰, AC ์„ ๋กœ๋ฅผ ํ†ตํ•ด ๊ณ„ํ†ต์ ‘์†๋ชจ์„ ์œผ๋กœ ์—ฐ๊ณ„๋˜๋Š” ์ง€์ ์ด๋‹ค. ์ด์™€ ๋ฐ˜๋Œ€๋กœ ์ ‘์†์ ์€ ์ ‘์†์„ค๋น„์™€ ๊ณ„ํ†ต์— ์ ‘์†ํ•˜๋Š” ๊ณ ๊ฐ, ์ฆ‰ ์‚ฌ์—…์ฃผ ๋ฐœ์ „์†Œ ์ธก ์ „๊ธฐ์„ค๋น„๊ฐ€ ์—ฐ๊ฒฐ๋˜๋Š” ์ง€์ ์„ ๋งํ•œ๋‹ค. ๋‹ค์Œ < ๊ทธ๋ฆผ 2>์— ์—ฐ๊ณ„์ ๊ณผ ์ ‘์†์ ์˜ ์ •์˜๋ฅผ ์š”์•ฝํ•˜์—ฌ ๊ทธ๋ฆผ์œผ๋กœ ๋‚˜ํƒ€๋‚ด์—ˆ๋‹ค. ๋ณธ ๋…ผ๋ฌธ์—์„œ๋Š” ์—ฐ๊ณ„์ ๊ณผ ์ ‘์†์ ์—์„œ ๋ฌดํšจ์ „๋ ฅ ๋ณด์ƒ๋Ÿ‰์„ ๊ฐ๊ฐ ์‚ฐ์ •ํ•˜์—ฌ, ๋น„๊ตํ•˜์˜€๋‹ค.

๊ทธ๋ฆผ 2. ์ ‘์†์ ๊ณผ ์—ฐ๊ณ„์ ์˜ ์ •์˜

Fig. 2. Definition of the point of connection and the point of interconnection

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2.2 ํ•ด์ƒํ’๋ ฅ๋‹จ์ง€ ๊ฒ€ํ†  DB ๊ตฌ์„ฑ ๋ฐ ๋ชจ์˜ ๋ฐฉ์•ˆ

๋ฌดํšจ์ „๋ ฅ ๋ณด์ƒ๋Ÿ‰ ์‚ฐ์ •์„ ์œ„ํ•ด [๊ทธ๋ฆผ 3]๊ณผ ๊ฐ™์€ ํ•ด์ƒํ’๋ ฅ๋‹จ์ง€ ํ…Œ์ŠคํŠธ ๊ณ„ํ†ต์„ ์ •์ƒ์ƒํƒœ ํ•ด์„ ํ”„๋กœ๊ทธ๋žจ์ธ PSS/E๋ฅผ ํ™œ์šฉํ•˜์—ฌ ๊ตฌํ˜„ํ•˜์˜€๋‹ค. ์ด 3GW ๊ทœ๋ชจ์˜ ํ•ด์ƒํ’๋ ฅ๋‹จ์ง€๋Š” 300MW ๊ทœ๋ชจ์˜ 6๊ฐœ, 400MW ๊ทœ๋ชจ์˜ 3๊ฐœ ๋‹จ์ง€๋กœ ๋‚ด๋ถ€๋ง์ด ๊ตฌ์„ฑ๋˜์–ด ์žˆ์œผ๋ฉฐ, ๋‚ด๋ถ€๋ง ๋‹จ์ง€๋Š” ์•ฝ 30~40km ๊ธธ์ด์˜ ํ•ด์ €์ผ€์ด๋ธ” 2ํšŒ์„ ์œผ๋กœ ๊ณต๋™์ ‘์†๋ชจ์„ ์— ์—ฐ๊ณ„๋˜์–ด ์žˆ๋‹ค. ๊ณต๋™์ ‘์†๋ชจ์„ ์— ์—ฐ๊ฒฐ๋œ ํ•ด์ƒํ’๋ ฅ๋‹จ์ง€๋Š” ์•ฝ 40km ๊ธธ์ด์˜ ํ•ด์ €์ผ€์ด๋ธ”์ธ ๊ณต๋™์ ‘์†์„ ๋กœ๋ฅผ ํ†ตํ•ด ์œก์ง€๊ณ„ํ†ต๊นŒ์ง€ ์—ฐ๊ณ„๋œ๋‹ค. ์œก์ง€๊ณ„ํ†ต์˜ ์—ฐ๊ณ„์ „์••์€ 345kV์ด๋ฉฐ, ์ •์ƒ์ƒํƒœ๋ฅผ ๊ฐ€์ •ํ•˜์—ฌ ๋ฌดํ•œ ๋ชจ์„ ์œผ๋กœ ๋“ฑ๊ฐ€ํ•˜์˜€๋‹ค. ํ’๋ ฅ๋ฐœ์ „๊ธฐ๋Š” ๋ฌดํšจ์ „๋ ฅ ๊ณต๊ธ‰๋ฒ”์œ„๋ฅผ ๋งŒ์กฑํ•˜๋Š” ๋ฌดํšจ์ „๋ ฅ ๋ณด์ƒ๋Ÿ‰์˜ ์ตœ๋Œ€๊ฐ’์„ ์‚ฐ์ถœํ•˜๊ธฐ ์œ„ํ•ด ๋ฌดํšจ์ „๋ ฅ์„ ์ถœ๋ ฅํ•˜์ง€ ์•Š๋„๋ก ์„ค์ •ํ•˜์˜€๋‹ค.

ํ•ด์ƒํ’๋ ฅ๋‹จ์ง€์˜ ๋ฌดํšจ์ „๋ ฅ ๋ณด์ƒ๋Ÿ‰์„ ์‚ฐ์ •ํ•˜๊ธฐ ์œ„ํ•ด์„œ๋Š” ์ „์ฒด ๋ฌดํšจ์ „๋ ฅ ๊ตํ™˜๋Ÿ‰์„ ํŒŒ์•…ํ•ด์•ผ ํ•œ๋‹ค. ํ˜„์žฌ ๊ตญ๋‚ด์—์„œ๋Š” ์—ฐ๊ณ„ ๋ชจ์„ ์˜ ์šด์ „์ „์•• ๋ฒ”์œ„๋ฅผ 0.9pu์—์„œ 1.1pu๋กœ ์„ค์ •๋˜์–ด ์žˆ๊ณ , ๋ฐœ์ „๋‹จ์ง€์˜ ๋ฌดํšจ์ „๋ ฅ ์ˆ˜๊ธ‰ ์กฐ์ ˆ ๋ฐ ๊ฒฐ์ •์€ ํ•ด๋‹น ์ „์•• ๋ฒ”์œ„๋ฅผ ์œ ์ง€ํ•˜๋Š” ๋ฒ”์œ„ ๋‚ด์—์„œ ๊ฒฐ์ •๋˜์–ด์•ผ ํ•œ๋‹ค. ๋”ฐ๋ผ์„œ ๋ณธ ์—ฐ๊ตฌ์—์„œ๋Š” ๊ณ„ํ†ต ์ ‘์†๋ชจ์„ ์˜ ๊ณ„ํ†ต์ „์•• ์ƒํ™ฉ์„ ์šด์ „์ „์•• ๋ฒ”์œ„์˜ ํ•˜ํ•œ์ ์ธ 0.9pu, ์ƒํ•œ์ ์ธ 1.1pu๋กœ ์„ค์ •ํ•˜์˜€๋‹ค. ๊ทธ๋ฆฌ๊ณ  ์ „๋ ฅ๊ณ„ํ†ต ์‹ ๋ขฐ๋„ ๋ฐ ์ „๊ธฐํ’ˆ์งˆ ์œ ์ง€๊ธฐ์ค€ ์ œ5์กฐ ์ „์••์กฐ์ •๋ชฉํ‘œ์—์„œ ๋ช…์‹œํ•œ 345kV ๊ณ„ํ†ต์˜ ์ „์••๋ชฉํ‘œ์ธ 353kV๋ฅผ pu๋กœ ํ™˜์‚ฐํ•œ ๊ฐ’์ธ 1.023pu๋ฅผ ์—ญ๋ฅ  1์ธ ์ƒํ™ฉ์œผ๋กœ ์„ค์ •ํ•˜์˜€๋‹ค. ์ด์™€ ๊ฐ™์€ 3๊ฐœ์˜ ๊ณ„ํ†ต ์ „์•• ์šด์ „์ ์„ ์ •์˜ํ•˜๊ณ , ํ˜„์‹ค์ ์ธ ์ „๋ ฅ๊ณ„ํ†ต ์šด์˜ ์ƒํ™ฉ์—์„œ์˜ ๋ฌดํšจ์ „๋ ฅ ๋ณด์ƒ๋Ÿ‰์„ ์‚ฐ์ •ํ•˜๊ธฐ ์œ„ํ•ด์„œ ๊ณ„ํ†ต์˜ ์ „์••์ด 0.9pu์ธ ์ƒํ™ฉ์—์„œ๋Š” ๋ฌดํšจ์ „๋ ฅ์„ ๊ณต๊ธ‰ํ•˜๋Š” ๊ฒฝ์šฐ๋งŒ ๊ณ ๋ คํ•˜์˜€๊ณ , ๋ฐ˜๋Œ€๋กœ ๊ณ„ํ†ต ์ „์••์ด 1.1pu์ธ ์ƒํ™ฉ์—์„œ๋Š” ๋ฌดํšจ์ „๋ ฅ์„ ํก์ˆ˜ํ•˜๋Š” ๊ฒฝ์šฐ๋งŒ ๊ณ ๋ คํ•˜์˜€๋‹ค. ๊ณ„ํ†ต ์ „์••์ด 1.023pu์ธ ์ƒํ™ฉ์—์„œ๋Š” ์—ญ๋ฅ ์ด 1์ด๋ฏ€๋กœ ๊ณต๋™์ ‘์†๋ชจ์„ ๊ณผ ๊ณ„ํ†ต์ ‘์†๋ชจ์„ ์‚ฌ์ด์˜ ๋ฌดํšจ์ „๋ ฅ ์กฐ๋ฅ˜๊ฐ€ ๋ฐœ์ƒํ•˜์ง€ ์•Š๋„๋ก ์‹œ๋‚˜๋ฆฌ์˜ค ์ƒํ™ฉ์„ ์ •์˜ํ•˜์˜€๋‹ค. ๋ฌดํšจ์ „๋ ฅ ๊ณต๊ธ‰๋Šฅ๋ ฅ ๋ฒ”์œ„๋ฅผ ๋งŒ์กฑํ•˜๊ธฐ ์œ„ํ•ด ์œ ํšจ์ „๋ ฅ ์ถœ๋ ฅ์˜ ๋น„์œจ์„ 10% ์กฐ์ ˆํ•˜์—ฌ ๊ฐ ์ƒํ™ฉ์—์„œ์˜ ๋ฌดํšจ์ „๋ ฅ ๋ณด์ƒ๋Ÿ‰์„ ๊ณ„์‚ฐํ•  ์ˆ˜ ์žˆ๋„๋ก ํ•˜์˜€๊ณ , 3๊ฐœ์˜ ๊ณ„ํ†ต ์šด์ „ ์ „์••๊ฐ’์—์„œ ์œ ํšจ์ „๋ ฅ ์ถœ๋ ฅ์— ๋”ฐ๋ผ ํ•„์š”ํ•œ ๋ฌดํšจ์ „๋ ฅ๋Ÿ‰์„ ๊ณ„์‚ฐํ•  ์ˆ˜ ์žˆ๋„๋ก ํ•˜์˜€๋‹ค.

๋ณธ ๋…ผ๋ฌธ์—์„œ ์‹ ์žฌ์ƒ๋ฐœ์ „๊ธฐ ์†ก์ „๊ณ„ํ†ต์—ฐ๊ณ„ ๊ธฐ์ˆ ๊ธฐ์ค€์— ์ œ์‹œ๋œ ๋ฌดํšจ์ „๋ ฅ ๊ณต๊ธ‰๋Šฅ๋ ฅ ๊ธฐ์ค€์˜ ํŠน์„ฑ์— ๋”ฐ๋ผ ์œ ํšจ์ „๋ ฅ ์ถœ๋ ฅ์„ 10% ๋‹จ์œ„๋กœ ์กฐ์ ˆํ•ด๊ฐ€๋ฉฐ ๋ชจ์˜๋ฅผ ์ˆ˜ํ–‰ํ•˜์˜€๋‹ค. ๋ฌดํšจ์ „๋ ฅ ๊ณต๊ธ‰๋Šฅ๋ ฅ ๊ธฐ์ค€์€ ๊ทธ๋ฆผ 1๊ณผ ๊ฐ™์ด ์˜ค๊ฐํ˜• ๋ชจ์–‘์œผ๋กœ ๋‘ ๊ตฌ๊ฐ„์œผ๋กœ ๋‚˜๋ˆ„์–ด์„œ ํ•ด์„ํ•  ์ˆ˜ ์žˆ๋‹ค. ์ฒซ ๋ฒˆ์งธ ๊ตฌ๊ฐ„์€ ์œ ํšจ์ „๋ ฅ 0%๋ถ€ํ„ฐ 20%์˜ ๊ตฌ๊ฐ„์œผ๋กœ ์œ ํšจ์ „๋ ฅ์— ๋”ฐ๋ฅธ ๋ฌดํšจ์ „๋ ฅ์€ ์ผ์ •ํ•œ ๊ธฐ์šธ๊ธฐ๋กœ ํ‘œํ˜„๋˜๋Š”๋ฐ, ์ด๋Š” ์—ญ๋ฅ ์ด ์žˆ์Œ์„ ์˜๋ฏธํ•œ๋‹ค. ๋•Œ๋ฌธ์—, ํ•ด๋‹น ๊ตฌ๊ฐ„์—์„œ๋Š” 20% ์ง€์ ์ด ๊ฐ™์€ ์—ญ๋ฅ ์„ ๊ฐ–๋Š” ์ƒํ™ฉ ์ค‘์—์„œ ์กฐ๋ฅ˜๋Ÿ‰์ด ๊ฐ€์žฅ ํฐ ์ง€์ ์ด๋‹ค. ๋ฐ˜๋ฉด, 20%๋ถ€ํ„ฐ 100% ๊ตฌ๊ฐ„์—์„œ๋Š” ์œ ํšจ์ „๋ ฅ ์ถœ๋ ฅ์— ๋”ฐ๋ฅธ ๋ฌดํšจ์ „๋ ฅ ๊ณต๊ธ‰ ๋ฐ ํก์ˆ˜ ํ•„์š”๋Ÿ‰์ด 33%๋กœ ๊ณ ์ •๋˜์–ด ์žˆ๋‹ค. 100% ์ง€์ ์€ ์—ญ๋ฅ  0.95๋กœ ์œ ํšจ์ „๋ ฅ์— ๋”ฐ๋ฅธ ์กฐ๋ฅ˜๋Ÿ‰์ด ํฌ์ง€๋งŒ, 20% ์ง€์ ์ด ์—ญ๋ฅ  ์ธก๋ฉด์—์„œ๋Š” ์—ญ๋ฅ  0.52๋กœ ๊ฐ€์žฅ ์ข‹์ง€ ์•Š์€ ์ง€์ ์ด ๋œ๋‹ค. ๋‹ค์‹œ ๋งํ•ด, ๊ธฐ์ค€์—์„œ ์ œ์‹œํ•˜๋Š” ๋ฌดํšจ์ „๋ ฅ ๊ณต๊ธ‰๋Šฅ๋ ฅ ๋ฒ”์œ„ ์ค‘, ์ ˆ๋Œ€์ ์œผ๋กœ ๊ฐ€์žฅ ์กฐ๋ฅ˜๊ฐ€ ๋งŽ์ด ํ๋ฅด๋Š” ์ง€์ ์ธ 100% ์ง€์ ๊ณผ ์—ญ๋ฅ  ์ธก๋ฉด์—์„œ ๊ฐ€์žฅ ์ข‹์ง€ ์•Š์€ ์กฐ๊ฑด์ธ 20% ์ง€์ ์ด ์ž„๊ณ„์ ์ด ๋œ๋‹ค. ๋”ฐ๋ผ์„œ, 20% ์ง€์ ๊ณผ 100% ์ง€์ ์„ ํฌํ•จํ•  ์ˆ˜ ์žˆ๋„๋ก ์œ ํšจ์ „๋ ฅ์„ 10% ๋‹จ์œ„๋กœ ์กฐ์ ˆํ•ด๊ฐ€๋ฉฐ ๋ชจ์˜๋ฅผ ์ˆ˜ํ–‰ํ•˜์˜€๋‹ค.

๊ทธ๋ฆผ 3. ํ•ด์ƒํ’๋ ฅ๋‹จ์ง€์˜ ํ…Œ์ŠคํŠธ ๊ณ„ํ†ต ๋ชจ๋ธ

Fig. 3. Test system model for offshore wind farm

../../Resources/kiee/KIEE.2025.74.2.238/fig3.png

์‹ ์žฌ์ƒ๋ฐœ์ „๊ธฐ ์†ก์ „๊ณ„ํ†ต ์—ฐ๊ณ„๊ธฐ์ˆ  ๊ธฐ์ค€ ๋‚ด์šฉ์ธ ๋ฌดํšจ์ „๋ ฅ ๊ณต๊ธ‰๋Šฅ๋ ฅ ํ‰๊ฐ€ ๊ธฐ์ค€์ ์— ๋Œ€ํ•˜์—ฌ ์—ฐ๊ณ„์ ๊ณผ ์ ‘์†์ ์— ๋”ฐ๋ผ ๋‘ ๊ฐ€์ง€ ์‚ฌ๋ก€๋กœ ๋‚˜๋ˆ„์–ด ๋ถ„์„ํ•˜์˜€๋‹ค. ๊ฐ ๋‘ ๊ฐœ์˜ ๋ฐฉ์•ˆ์—์„œ ๋ฌดํšจ์ „๋ ฅ ํ•„์š”๋Ÿ‰๊ณผ ๋ฌดํšจ์ „๋ ฅ ์ตœ์  ๋ณด์ƒ ๋ฐฉ์•ˆ์— ๋”ฐ๋ผ ๊ณ„์‚ฐ๋œ ๊ฐ๊ฐ์˜ ๋ณด์ƒ์„ค๋น„ ์šฉ๋Ÿ‰์˜ ๊ฒฐ๊ณผ๋ฅผ ๊ฒ€ํ† ํ•˜์˜€๋‹ค. ์ฒซ ๋ฒˆ์งธ ์‚ฌ๋ก€ ์—ฐ๊ตฌ๋Š” ๊ณต๋™์ ‘์†๋ชจ์„ ์—์„œ ๊ณ„ํ†ต์ ‘์†๋ชจ์„ ์œผ๋กœ ์—ฐ๊ฒฐ๋˜๋Š” ๋ฌดํšจ์ „๋ ฅ๋Ÿ‰์— ๋Œ€ํ•˜์—ฌ ๊ณ„ํ†ต์ ‘์†๋ชจ์„  ์ธก ์—ฐ๊ณ„์  ๊ธฐ์ค€์—์„œ ๋ฌดํšจ์ „๋ ฅ์„ ์ธก์ •ํ•˜์—ฌ ํ•„์š” ๋ฌดํšจ์ „๋ ฅ ๋ณด์ƒ๋Ÿ‰์„ ๊ณ„์‚ฐํ•˜์˜€๊ณ , ๋‘ ๋ฒˆ์งธ ์‚ฌ๋ก€ ์—ฐ๊ตฌ๋Š” ๋งˆ์ฐฌ๊ฐ€์ง€๋กœ ๊ณต๋™์ ‘์†๋ชจ์„ ์—์„œ ๊ณ„ํ†ต์ ‘์†๋ชจ์„ ์œผ๋กœ ์—ฐ๊ฒฐ๋˜๋Š” ๋ฌดํšจ์ „๋ ฅ์— ๋Œ€ํ•˜์—ฌ ๊ณต๋™์ ‘์†๋ชจ์„  ์ธก ์ ‘์†์  ๊ธฐ์ค€์œผ๋กœ ๋ฌดํšจ์ „๋ ฅ๋Ÿ‰์„ ์ธก์ •ํ•˜์—ฌ ํ•„์š” ๋ฌดํšจ์ „๋ ฅ ๋ณด์ƒ๋Ÿ‰์„ ๊ณ„์‚ฐํ•˜์˜€๋‹ค. ๋ฌดํšจ์ „๋ ฅ ๋ณด์ƒ๋Ÿ‰์€ ๊ฐ€์ƒ์˜ ๋ฐœ์ „๊ธฐ๋ฅผ ๊ณต๋™์ ‘์†๋ชจ์„ ์— ์„ค์น˜ํ•œ ์ƒํ™ฉ์„ ๊ฐ€์ •ํ•˜์˜€๊ณ , ์ด๋•Œ ๊ฐ๊ฐ ์—ฐ๊ณ„์ ๊ณผ ์ ‘์†์ ์—์„œ์˜ ๋ฌดํšจ์ „๋ ฅ ๊ณต๊ธ‰๋Šฅ๋ ฅ ๊ธฐ์ค€์„ ๋งŒ์กฑํ•˜๋„๋ก ๊ณ„์‚ฐํ•˜์˜€๋‹ค. ๋ฌดํšจ์ „๋ ฅ ๋ณด์ƒ๋Ÿ‰ ์‚ฐ์ • ๊ฒฐ๊ณผ๋Š” ๊ฐ€์ƒ๋ฐœ์ „๊ธฐ์˜ ์ถœ๋ ฅ๋œ ๋ฌดํšจ์ „๋ ฅ๋Ÿ‰์œผ๋กœ ๊ณ„์‚ฐํ•˜์˜€๋‹ค.

2.3 ๋ฌดํšจ์ „๋ ฅ ๋ณด์ƒ๋Ÿ‰ ์‚ฐ์ • ๋ฐฉ์•ˆ

2.1์—์„œ ๋Œ€๊ทœ๋ชจ ํ•ด์ƒํ’๋ ฅ๋‹จ์ง€๊ฐ€ ๊ณ„ํ†ต์— ์—ฐ๊ณ„ํ•˜๊ธฐ ์œ„ํ•ด์„œ๋Š” <๊ทธ๋ฆผ 1>์˜ ๋ฌดํšจ์ „๋ ฅ ๊ณต๊ธ‰๋Šฅ๋ ฅ์„ ๊ฐ–์ถ”์–ด์•ผ ํ•œ๋‹ค. ํ•ด์ƒํ’๋ ฅ๋‹จ์ง€๋Š” ์ˆ˜์‹ญ km์˜ ํ•ด์ €์ผ€์ด๋ธ”๋กœ ์ธํ•ด ๊ฐ€๊ณต์„ ๋กœ์™€ ๋‹ฌ๋ฆฌ ๋†’์€ ์ถฉ์ „์ „๋ฅ˜๋ฅผ ๊ฐ€์ง€๊ณ  ์žˆ๊ธฐ์—, ์ด๋ฅผ ๋ณด์ƒํ•˜์—ฌ์•ผ ํ•œ๋‹ค. ๋”ฐ๋ผ์„œ ๋ณ‘๋ ฌ๋ฆฌ์•กํ„ฐ(Shunt reactor)์˜ ์„ค์น˜๊ฐ€ ํ•„์š”ํ•˜๋ฉฐ, ๊ธฐ์ค€์— ๋”ฐ๋ผ ์ „๋ ฅ๊ณ„ํ†ต ์ƒํ™ฉ์— ๋ฌดํšจ์ „๋ ฅ ๊ณต๊ธ‰๋Šฅ๋ ฅ์„ ํ™•๋ณดํ•˜๊ธฐ ์œ„ํ•ด ์ˆœ๋™๋ฌดํšจ์ „๋ ฅ ๋ณด์ƒ์žฅ์น˜์ธ STATCOM์„ ํ•จ๊ป˜ ์„ค์น˜ํ•ด์•ผ ํ•œ๋‹ค. STATCOM ์„ค์น˜ ๊ฐ€๊ฒฉ์ด ๋ณ‘๋ ฌ๋ฆฌ์•กํ„ฐ์˜ ์„ค์น˜ ๊ฐ€๊ฒฉ๋ณด๋‹ค ์ผ๋ฐ˜์ ์œผ๋กœ ๋†’๊ธฐ์—, STATCOM์˜ ๊ฐ€๊ฒฉ์„ ์ตœ์†Œํ™”ํ• ์ˆ˜๋ก ์ „์ฒด ๋ฌดํšจ์ „๋ ฅ ๋ณด์ƒ์„ค๋น„ ์„ค์น˜ ๊ฐ€๊ฒฉ์„ ์ค„์ผ ์ˆ˜ ์žˆ๋‹ค. ์‹ (1)๊ณผ (2)๋Š” ํ•ด์ƒํ’๋ ฅ๋‹จ์ง€์—์„œ STATCOM๊ณผ ๋ถ„๋กœ ๋ฆฌ์•กํ„ฐ๋กœ ๋ฌดํšจ์ „๋ ฅ์„ ๋ณด์ƒํ•˜๋Š” ๊ฒฝ์šฐ, STATCOM์˜ ์šฉ๋Ÿ‰์„ ์ตœ์†Œ๋กœ ์‚ฐ์ •ํ•˜๊ธฐ ์œ„ํ•œ ์‹์ด๋‹ค[5].

(1)
VQmaxXS+V2QmaxXR=Qmax
(2)
โˆ’VQminXS+V2QminXR=Qmin

VQmax์™€ VQmin์€ ๊ฐ๊ฐ ๋ฌดํšจ์ „๋ ฅ ์ตœ๋Œ€, ์ตœ์†Œ ๋ณด์ƒ ์ƒํ™ฉ์—์„œ์˜ ๋ณด์ƒ์„ค๋น„๊ฐ€ ์„ค์น˜๋˜๋Š” ๋ชจ์„ ์˜ ์ „์••์„ ์˜๋ฏธํ•˜๋ฉฐ, XS, XR์€ ๊ฐ๊ฐ STATCOM๊ณผ ๋ถ„๋กœ ๋ฆฌ์•กํ„ฐ์˜ ์šฉ๋Ÿ‰, Qmax, Qmin์€ ๊ฐ๊ฐ ๋ฌดํšจ์ „๋ ฅ ์ตœ๋Œ€, ์ตœ์†Œ ๋ณด์ƒ๋Ÿ‰์„ ์˜๋ฏธํ•œ๋‹ค. ์œ„์˜ (1)๊ณผ (2)์˜ ์ˆ˜์‹์„ ๋ณด์ƒ์„ค๋น„ ์šฉ๋Ÿ‰์— ๋Œ€ํ•ด์„œ ์ •๋ฆฌํ•˜์—ฌ ๊ฐ๊ฐ ์‹ (3)๊ณผ (4)๋กœ ๋‚˜ํƒ€๋‚ด์—ˆ๋‹ค.

(3)
XS=V2QminQmaxโˆ’V2QmaxQminVQmaxVQmin(VQmax+VQmin)
(4)
XR=VQminQmax+VQmaxQminVQmaxVQmin(VQmax+VQmin)

2.4 ๊ฒ€ํ†  ๊ฒฐ๊ณผ

์ฒซ ๋ฒˆ์งธ ์‚ฌ๋ก€ ์—ฐ๊ตฌ์˜ ๋ฌดํšจ์ „๋ ฅ ๋ณด์ƒ๋Ÿ‰ ๊ฒฐ๊ณผ ๊ทธ๋ž˜ํ”„๋Š” <๊ทธ๋ฆผ 4>์— ๋‚˜ํƒ€๋‚ด์—ˆ๋‹ค. ๊ณต๋™์ ‘์†๋ชจ์„ ๊ณผ ๊ณ„ํ†ต์ ‘์†๋ชจ์„ ์—์„œ ๊ณ„ํ†ต์ ‘์†๋ชจ์„ ์œผ๋กœ ์ „๋‹ฌ๋˜๋Š” ๋ฌดํšจ์ „๋ ฅ๋Ÿ‰ ์ฆ‰, ์—ฐ๊ณ„์ ์œผ๋กœ ๋“ค์–ด์˜ค๋Š” ๋ฌดํšจ์ „๋ ฅ๋Ÿ‰์„ ๊ธฐ์ค€์œผ๋กœ ๊ณ„์‚ฐํ•œ ๊ฒƒ์ด๋ฉฐ, ๋ฌดํšจ์ „๋ ฅ์„ ๊ณต๊ธ‰ํ•˜๋Š” ๊ทธ๋ž˜ํ”„๋Š” ๋นจ๊ฐ„์ƒ‰, ํก์ˆ˜ํ•˜๋Š” ๊ทธ๋ž˜ํ”„๋ฅผ ํŒŒ๋ž€์ƒ‰ ์„ ์œผ๋กœ ๋‚˜ํƒ€๋‚ด์—ˆ๋‹ค. ๋ฌดํšจ์ „๋ ฅ ๋ณด์ƒ๋Ÿ‰์ด ๊ฐ€์žฅ ๋งŽ์€ ๊ฒฝ์šฐ๋Š” ํ’๋ ฅ๋‹จ์ง€ ์œ ํšจ์ „๋ ฅ ์ถœ๋ ฅ์ด 20%์ผ ๋•Œ ๊ณ„ํ†ต์œผ๋กœ๋ถ€ํ„ฐ ๋ฌดํšจ์ „๋ ฅ์„ ํก์ˆ˜ํ•˜๋Š” ๊ฒฝ์šฐ์˜€๊ณ , ํ•„์š” ๋ฌดํšจ์ „๋ ฅ ๋ณด์ƒ๋Ÿ‰์€ 5,345MVAr๋กœ ๊ณ„์‚ฐ๋˜์—ˆ๋‹ค. ๋ฐ˜๋Œ€๋กœ ๊ฐ€์žฅ ์ ์€ ๊ฒฝ์šฐ๋Š” ์œ ํšจ์ „๋ ฅ ์ถœ๋ ฅ์ด 100%์ผ ๋•Œ ๊ณต๊ธ‰ํ•˜๋Š” ๊ฒฝ์šฐ์˜€๊ณ , ์ด๋•Œ ํ•„์š” ๋ฌดํšจ์ „๋ ฅ ๋ณด์ƒ๋Ÿ‰์€ 3,080MVAr๋กœ ๊ณ„์‚ฐ๋˜์—ˆ๋‹ค.

๋‘ ๋ฒˆ์งธ ์‚ฌ๋ก€ ์—ฐ๊ตฌ์˜ ๋ฌดํšจ์ „๋ ฅ ๋ณด์ƒ๋Ÿ‰ ๊ฒฐ๊ณผ ๊ทธ๋ž˜ํ”„๋Š” <๊ทธ๋ฆผ 5>์— ๋‚˜ํƒ€๋‚ด์—ˆ๋‹ค. <๊ทธ๋ฆผ 5>์—์„œ๋Š” ๋ฌดํšจ์ „๋ ฅ ๋ณด์ƒ๋Ÿ‰ ๊ณต๊ธ‰๋Šฅ๋ ฅ์˜ ๊ธฐ์ค€์„ ์ ‘์†์ ์—์„œ์˜ ๋ฌดํšจ์ „๋ ฅ๋Ÿ‰์œผ๋กœ ๊ณ„์‚ฐํ•˜์˜€์„ ๋•Œ์˜ ๊ฒฐ๊ณผ๋ฅผ ๋‚˜ํƒ€๋‚ธ ๊ทธ๋ž˜ํ”„์ด๋‹ค. ๊ณต๋™์ ‘์†๋ชจ์„ ์—์„œ ์œก์ง€๊ณ„ํ†ต์œผ๋กœ ๋‚˜๊ฐ€๋Š” ๋ฌดํšจ์ „๋ ฅ๋Ÿ‰์„ ๊ธฐ์ค€์œผ๋กœ ๊ณ„์‚ฐํ•œ ๊ฒฐ๊ณผ์ด๋‹ค. ๋ฌดํšจ์ „๋ ฅ ๋ณด์ƒ๋Ÿ‰์ด ๊ฐ€์žฅ ๋งŽ์€ ๊ฒฝ์šฐ๋Š” ์œ ํšจ์ „๋ ฅ ์ถœ๋ ฅ์ด 20%์ผ ๋•Œ ๊ณ„ํ†ต์œผ๋กœ๋ถ€ํ„ฐ ๋ฌดํšจ์ „๋ ฅ์„ ํก์ˆ˜ํ•˜๋Š” ๊ฒฝ์šฐ์˜€๊ณ , ํ•„์š” ๋ฌดํšจ์ „๋ ฅ ๋ณด์ƒ๋Ÿ‰์€ 4,820MVAr๋กœ ๊ณ„์‚ฐ๋˜์—ˆ๋‹ค. ๋ฐ˜๋Œ€๋กœ ๊ฐ€์žฅ ์ ์€ ๊ฒฝ์šฐ๋Š” ์œ ํšจ์ „๋ ฅ ์ถœ๋ ฅ๋Ÿ‰์ด 20%์ผ ๋•Œ ๊ณ„ํ†ต์œผ๋กœ ๋ฌดํšจ์ „๋ ฅ์„ ๊ณต๊ธ‰ํ•˜๋Š” ๊ฒฝ์šฐ์˜€๊ณ , ํ•„์š” ๋ฌดํšจ์ „๋ ฅ ๋ณด์ƒ๋Ÿ‰์€ 2,883MVAr๋กœ ๊ณ„์‚ฐ๋˜์—ˆ๋‹ค.

ํ•ด์ƒํ’๋ ฅ๋‹จ์ง€์˜ ์œ ํšจ์ „๋ ฅ ์ถœ๋ ฅ์— ๋”ฐ๋ฅธ ๋ฌดํšจ์ „๋ ฅ ๊ณต๊ธ‰๋Šฅ๋ ฅ์„ ์—ฐ๊ณ„์ ๊ณผ ์ ‘์†์ ์œผ๋กœ ๋‚˜๋ˆ„์–ด ๋ฌดํšจ์ „๋ ฅ ๋ณด์ƒ๋Ÿ‰์„ ์‚ฐ์ถœํ•˜์˜€๋‹ค. ์—ฐ๊ณ„์ ์—์„œ์˜ ๋ฌดํšจ์ „๋ ฅ ๋ณด์ƒ๋Ÿ‰ ๊ฒฐ๊ณผ ๊ทธ๋ž˜ํ”„๋Š” <๊ทธ๋ฆผ 4>์— ๋‚˜ํƒ€๋‚ด์—ˆ์œผ๋ฉฐ, ์ ‘์†์ ์—์„œ์˜ ๋ฌดํšจ์ „๋ ฅ ๋ณด์ƒ๋Ÿ‰ ๊ฒฐ๊ณผ ๊ทธ๋ž˜ํ”„๋Š” <๊ทธ๋ฆผ 5>์— ๋‚˜ํƒ€๋‚ด์—ˆ๋‹ค. ์ฒซ ๋ฒˆ์ฉจ ์‚ฌ๋ก€ ์—ฐ๊ตฌ์ธ ์—ฐ๊ณ„์ ์—์„œ์˜ ๋ฌดํšจ์ „๋ ฅ ๊ณต๊ธ‰๋Šฅ๋ ฅ ๊ธฐ์ค€์„ ๋งŒ์กฑํ•˜๊ธฐ ์œ„ํ•œ ๊ทธ๋ž˜ํ”„๋Š” <๊ทธ๋ฆผ 6>์œผ๋กœ ๋‚˜ํƒ€๋‚ผ ์ˆ˜ ์žˆ๋‹ค. ์—ฐ๊ณ„์ ์—์„œ์˜ ๋ฌดํšจ์ „๋ ฅ ๊ณต๊ธ‰๋Šฅ๋ ฅ์„ ๋งŒ์กฑํ•˜๊ธฐ ๋•Œ๋ฌธ์—, ๊ณ„ํ†ต์—ฐ๊ณ„ ๊ธฐ์ˆ ๊ธฐ์ค€์˜ ๊ทธ๋ž˜ํ”„๋ฅผ ์ •ํ™•ํžˆ ๋งŒ์กฑํ•˜๋Š” ์˜ค๊ฐํ˜• ๊ทธ๋ž˜ํ”„๋กœ ๊ทธ๋ ค์ง€๊ฒŒ ๋œ๋‹ค. ๋‘ ๋ฒˆ์งธ ์‚ฌ๋ก€ ์—ฐ๊ตฌ์ธ ์ ‘์†์ ์—์„œ ๋ฌดํšจ์ „๋ ฅ ๊ณต๊ธ‰๋Šฅ๋ ฅ์„ ๋งŒ์กฑํ•˜์˜€์„ ๋•Œ, ์—ฐ๊ณ„์ ์œผ๋กœ ์ „๋‹ฌ๋˜๋Š” ๋ฌดํšจ์ „๋ ฅ์„ ๋น„๊ตํ•˜์˜€๋‹ค. ์ด๋ฅผ <๊ทธ๋ฆผ 7>์— ๋‚˜ํƒ€๋‚ด์—ˆ๋‹ค. ์ ‘์†์ ์—์„œ ๋ฌดํšจ์ „๋ ฅ ๊ณต๊ธ‰๋Šฅ๋ ฅ์„ ํ‰๊ฐ€ ๊ธฐ์ค€์œผ๋กœ ์ •ํ•˜์˜€์„ ๋•Œ, ๊ณ„ํ†ต ์ธก์ธ ์—ฐ๊ณ„์ ์— ์ „๋‹ฌ๋˜๋Š” ๋ฌดํšจ์ „๋ ฅ์„ ๋น„๊ตํ•œ ๊ทธ๋ž˜ํ”„๋Š” ์ƒ๋Œ€์ ์œผ๋กœ ์˜ค๋ฅธ์ชฝ์œผ๋กœ ์น˜์šฐ์น˜๋Š” ๊ฒฝํ–ฅ์„ ๋ณด์ด๊ฒŒ ๋œ๋‹ค. ์ ‘์†์ ์—์„œ ํ˜„ ๊ณ„ํ†ต์—ฐ๊ณ„ ๊ธฐ์ˆ ๊ธฐ์ค€์˜ ๋ฌดํšจ์ „๋ ฅ ๊ณต๊ธ‰๋Šฅ๋ ฅ์— ๋งž๋Š” ๋ฌดํšจ์ „๋ ฅ์„ ๋ณด์ƒํ•˜์—ฌ๋„, ์—ฐ๊ณ„์ ์—์„œ๋Š” ๋ฌดํšจ์ „๋ ฅ์ด ๊ธฐ์ค€์„ ๋งŒ์กฑํ•˜์ง€ ๋ชปํ•˜๋Š” ๊ฒฐ๊ณผ๋ฅผ ๋‚˜ํƒ€๋‚ธ ๊ฒƒ์ด๋‹ค. <๊ทธ๋ฆผ 6> <๊ทธ๋ฆผ 7>์˜ ๋ฒ”๋ก€๋Š” <ํ‘œ 1>์— ์ƒ‰์„ ๊ตฌ๋ถ„ํ•˜์—ฌ ๋‚˜ํƒ€๋‚ด์—ˆ๋‹ค. <๊ทธ๋ฆผ 6>๊ณผ <๊ทธ๋ฆผ 7>์˜ ๋ฌดํšจ์ „๋ ฅ ๊ณต๊ธ‰๋Šฅ๋ ฅ ๊ธฐ์ค€์— ์˜ํ•œ ์ ๋“ค์€ ์—ฐํ•œ ์ƒ‰์œผ๋กœ ๊ตฌ๋ถ„ํ•˜์˜€๋‹ค.

๊ทธ๋ฆผ 4. ์—ฐ๊ณ„์ ์—์„œ ๋ฌดํšจ์ „๋ ฅ ๊ณต๊ธ‰๋Šฅ๋ ฅ์„ ๋งŒ์กฑํ•˜๊ธฐ ์œ„ํ•ด ํ•„์š”ํ•œ ์ ‘์†์ ์—์„œ์˜ ๋ฌดํšจ์ „๋ ฅ ๋ณด์ƒ๋Ÿ‰

Fig. 4. The required reactive power compensation at the point of connection to meet the reactive power capability at the point of interconnection

../../Resources/kiee/KIEE.2025.74.2.238/fig4.png

๊ทธ๋ฆผ 5. ์ ‘์†์ ์—์„œ ๋ฌดํšจ์ „๋ ฅ ๊ณต๊ธ‰๋Šฅ๋ ฅ์„ ๋งŒ์กฑํ•˜๊ธฐ ์œ„ํ•ด ํ•„์š”ํ•œ ์ ‘์†์ ์—์„œ์˜ ๋ฌดํšจ์ „๋ ฅ ๋ณด์ƒ๋Ÿ‰

Fig. 5. The required reactive power compensation at the point of connection to meet the reactive power capability at the point of connection

../../Resources/kiee/KIEE.2025.74.2.238/fig5.png

๊ทธ๋ฆผ 6. ๊ณ„ํ†ต์—ฐ๊ณ„ ๊ธฐ์ˆ ๊ธฐ์ค€์˜ ๋ฌดํšจ์ „๋ ฅ ๊ณต๊ธ‰๋Šฅ๋ ฅ์— ๋”ฐ๋ฅธ ์—ฐ๊ณ„์ ์—์„œ์˜ ๋ฌดํšจ์ „๋ ฅ ๊ณต๊ธ‰๋Šฅ๋ ฅ ๊ฒฐ๊ณผ

Fig. 6. Results of reactive power capability at the point of interconnection according to the reactive power capability requirements of grid codes

../../Resources/kiee/KIEE.2025.74.2.238/fig6.png

๊ทธ๋ฆผ 7. ์ ‘์†์ ์—์„œ ๋ฌดํšจ์ „๋ ฅ ๊ณต๊ธ‰๋Šฅ๋ ฅ์„ ๋งŒ์กฑํ•  ๋•Œ, ์—ฐ๊ณ„์ ์—์„œ ๋ฌดํšจ์ „๋ ฅ ๊ณต๊ธ‰๋Šฅ๋ ฅ ๊ฒฐ๊ณผ

Fig. 7. Results of reactive power capability at the point of interconnection to meet the capability at the point of connection

../../Resources/kiee/KIEE.2025.74.2.238/fig7.png

ํ‘œ 1 <๊ทธ๋ฆผ 6>๊ณผ <๊ทธ๋ฆผ 7> ๋ฒ”๋ก€ ๊ตฌ๋ถ„

Table 1 Legend Distinction of Figure 6 and Figure 7

../../Resources/kiee/KIEE.2025.74.2.238/tb1.png

๋˜ํ•œ, <๊ทธ๋ฆผ 4>์™€ <๊ทธ๋ฆผ 5>์˜ ๋ฌดํšจ์ „๋ ฅ ๋ณด์ƒ๋Ÿ‰์„ ํ†ตํ•ด ์‹ (3)๊ณผ (4)๋ฅผ ํ†ตํ•ด ๋ฌดํšจ์ „๋ ฅ ๋ณด์ƒ์„ค๋น„์— ๋”ฐ๋ฅธ ๊ฐ๊ฐ์˜ ๋ณด์ƒ๋Ÿ‰์„ ๊ณ„์‚ฐํ•˜์—ฌ <ํ‘œ 2>์— ๋‚˜ํƒ€๋‚ด์—ˆ๋‹ค. ์—ฐ๊ณ„์ ์—์„œ์˜ ๋ณ‘๋ ฌ ๋ฆฌ์•กํ„ฐ์™€ STATCOM ์šฉ๋Ÿ‰์€ ๊ฐ๊ฐ 4266.611MVAr, 1156.201MVAr, ์ ‘์†์ ์—์„œ์˜ ๋ณ‘๋Ÿด ๋ฆฌ์•กํ„ฐ์™€ STATCOM ์šฉ๋Ÿ‰์€ ๊ฐ๊ฐ 3918.304MVAr, 981.321MVAr๋กœ ๊ณ„์‚ฐ๋˜์—ˆ๋‹ค. <ํ‘œ 3>์—๋Š” ์—ฐ๊ณ„์ ๊ณผ ์ ‘์†์ ์—์„œ์˜ ๋ฌดํšจ์ „๋ ฅ ๋ณด์ƒ๋Ÿ‰์ด ๊ฐ€์žฅ ๋งŽ์€ ๊ฒฝ์šฐ์™€ ๊ฐ€์žฅ ์ ์€ ๊ฒฝ์šฐ์˜ VQmax, VQmin๊ณผ Qmax, Qmin์˜ ๊ฒฐ๊ณผ๋ฅผ ๋‚˜ํƒ€๋‚ด์—ˆ๋‹ค.

ํ‘œ 2 ๋ฌดํšจ์ „๋ ฅ ๋ณด์ƒ์„ค๋น„ ์šฉ๋Ÿ‰ ๊ณ„์‚ฐ ๊ฒฐ๊ณผ

Table 2 Calculation results of reactive power compensation equipment capacity

์—ฐ๊ณ„์ 

์ ‘์†์ 

๋ณ‘๋ ฌ ๋ฆฌ์•กํ„ฐ

4266.611MVAr

3918.304MVAr

STATCOM

1156.201MVAr

981.321MVAr

ํ‘œ 3 ํ•„์š” ๋ฆฌ์•กํ„ฐ ์šฉ๋Ÿ‰์ด ์ตœ๋Œ€ยท์ตœ์†Œ์ธ ๊ฒฝ์šฐ ์ „์•• ๋ฐ ๋ฌดํšจ์ „๋ ฅ ํ•„์š” ๋ณด์ƒ๋Ÿ‰

Table 3 Voltage and required reactive power compensation in cases of maximum and minimum reactor capacity

์—ฐ๊ณ„์ 

์ ‘์†์ 

VQmax[pu]

1.07187

1.088682

VQmin[pu]

0.974163

0.948004

Qmax[MVAr]

6141.2295

5712.4326

Qmin[MVAr]

2922.6575

2591.1287

ํ•œํŽธ, <๊ทธ๋ฆผ 4>์™€ <๊ทธ๋ฆผ 5>์˜ ๊ทธ๋ž˜ํ”„์˜ ์–‘์ƒ์ด ๋‹ค๋ฅธ ๊ฒƒ์„ ํ™•์ธํ•  ์ˆ˜ ์žˆ๋‹ค. <๊ทธ๋ฆผ 4>๋Š” ์—ฐ๊ณ„์ ์—์„œ ๊ณ„ํ†ต์—ฐ๊ณ„ ๊ธฐ์ˆ ๊ธฐ์ค€์„ ์ถฉ์กฑํ•˜๊ธฐ ์œ„ํ•ด ์ ‘์†์ ์— ํ•„์š”ํ•œ ๋ฌดํšจ์ „๋ ฅ ๋ณด์ƒ์„ค๋Ÿ‰์„ ์‚ฐ์ถœํ•œ ๊ฒฐ๊ณผ์ด๋‹ค. ์œ ํšจ์ „๋ ฅ์ด ์ฆ๊ฐ€ํ•จ์— ๋”ฐ๋ผ ํ•„์š” ๋ฌดํšจ์ „๋ ฅ๋Ÿ‰์ด ์ค„์–ด๋“œ๋Š” ์–‘์ƒ์„ ๋ถ„์„ํ•˜๊ธฐ ์œ„ํ•ด, ๊ฐ€์žฅ ๋งŽ์€ ๋ฆฌ์•กํ„ฐ๊ฐ€ ํ•„์š”ํ•œ ๊ฒƒ์œผ๋กœ ์‚ฐ์ถœ๋˜๋Š” 20% ์ง€์ ๊ณผ, ๊ฐ€์žฅ ์ ์€ ๋ฆฌ์•กํ„ฐ๊ฐ€ ํ•„์š”ํ•œ ๊ฒƒ์œผ๋กœ ์‚ฐ์ถœ๋˜๋Š” 100% ์ง€์ ์„ ๋น„๊ตํ•˜์—ฌ ์„ค๋ช…ํ•˜์˜€๋‹ค.

์—ฐ๊ณ„์ ์— ์ „๋‹ฌ๋˜๋Š” ๋ฌดํšจ์ „๋ ฅ์€ ์ ‘์†์ ์—์„œ ์—ฐ๊ณ„์ ์œผ๋กœ ์ „๋‹ฌ๋˜๋Š” ๋ฌดํšจ์ „๋ ฅ๊ณผ ์ ‘์†์ ๊ณผ ์—ฐ๊ณ„์ ์— ์—ฐ๊ณ„๋œ ์„ ๋กœ์˜ ์ถฉ์ „ ์šฉ๋Ÿ‰์˜ ํ•ฉ์œผ๋กœ ๊ณ„์‚ฐ๋œ๋‹ค. ํ•ด๋‹น ์—ฐ๊ณ„์ ์„ ๊ธฐ์ค€์œผ๋กœ ๊ฒฐ๊ณผ๋ฅผ ์‚ฐ์ถœํ•˜์˜€์„ ๋•Œ, ์—ฐ๊ณ„์ ์˜ ์ „์••์€ ์ผ์ •ํ•˜๊ฒŒ ๊ณ ์ •๋˜์–ด ์žˆ์œผ๋ฏ€๋กœ, ์ ‘์†์ ๊ณผ ์—ฐ๊ณ„์ ์— ์—ฐ๊ณ„๋œ ์„ ๋กœ์˜ ์ถฉ์ „ ์šฉ๋Ÿ‰ ํ•ฉ์€ ๋™์ผํ•˜๋‹ค. ํ•œํŽธ, ์—ฐ๊ณ„์ ์— ์ „๋‹ฌ๋˜๋Š” ์ „๋ ฅ ์กฐ๋ฅ˜๋Š” ์ „๋ ฅ ์กฐ๋ฅ˜ ๋ฐฉ์ •์‹์— ๋”ฐ๋ผ ์—ฐ๊ณ„์ ์˜ ์ „์••๊ณผ ์ ‘์†์ ์—์„œ ์—ฐ๊ณ„์  ์‚ฌ์ด์— ์—ฐ๊ณ„๋œ ์„ ๋กœ์— ํ๋ฅด๋Š” ์ „๋ฅ˜ ๊ณต์•ก(Iโˆ—)์˜ ๊ณฑ์— ์˜ํ•ด ๊ฒฐ์ •๋˜๊ฒŒ ๋˜๋ฉฐ, ์ด๋•Œ ๋‘ ๋ชจ์„  ์‚ฌ์ด ์—ฐ๊ณ„๋œ ์„ ๋กœ์˜ ์ž„ํ”ผ๋˜์Šค์— ๋”ฐ๋ผ ์œ ํšจ์ „๋ ฅ ๋ฐ ๋ฌดํšจ์ „๋ ฅ์˜ ์†์‹ค์ด ๋ฐœ์ƒํ•˜๊ฒŒ ๋œ๋‹ค. ์œ ํšจ์ „๋ ฅ ์ถœ๋ ฅ์ด 100%์ผ ๋•Œ๋Š” 20%์ผ ๋•Œ์™€ ๋น„๊ตํ•˜์—ฌ ๋” ๋งŽ์€ ์ „๋ฅ˜๊ฐ€ ํ˜๋Ÿฌ์•ผ ํ•˜๋Š”๋ฐ, ์ด์— ๋”ฐ๋ผ ์„ ๋กœ์˜ ๋ฆฌ์•กํ„ด์Šค(X)์— ์˜ํ•ด ๋ฐœ์ƒํ•˜๋Š” ๋ฌดํšจ์ „๋ ฅ ์†์‹ค๋„ ๋” ํฌ๊ฒŒ ์ฆ๊ฐ€ํ•˜๊ฒŒ ๋œ๋‹ค. ์ฆ‰, ๋™์ผํ•œ ๋ฌดํšจ์ „๋ ฅ์„ ์ ‘์†์ ์— ๋ณด์ƒํ•˜๊ฒŒ ๋˜๋ฉด, ์„ ๋กœ์—์„œ ๋ฐœ์ƒํ•˜๋Š” ๋ฌดํšจ์ „๋ ฅ ์†์‹ค์— ์˜ํ•˜์—ฌ ์ ‘์†์ ์—์„œ ์—ฐ๊ณ„์ ์œผ๋กœ ์ „๋‹ฌ๋˜๋Š” ๋ฌดํšจ์ „๋ ฅ๋Ÿ‰์€ ๋” ๊ฐ์†Œํ•˜๊ฒŒ ๋œ๋‹ค. ๋•Œ๋ฌธ์—, ๋™์ผํ•œ ์ ‘์†์ ์—์„œ ์—ฐ๊ณ„์ ์œผ๋กœ ์ „๋‹ฌ๋˜๋Š” ๋ฌดํšจ์ „๋ ฅ๋Ÿ‰์„ ์œ ์ง€ํ•˜๊ธฐ ์œ„ํ•ด์„œ๋Š” ์กฐ๋ฅ˜๋Ÿ‰์ด ์ ์–ด์งˆ์ˆ˜๋ก ๋” ๋งŽ์€ ๋ฆฌ์•กํ„ฐ๊ฐ€ ํ•„์š”ํ•˜๊ฒŒ ๋œ๋‹ค.

๋ฐ˜๋ฉด, <๊ทธ๋ฆผ 5>๋Š” ์ ‘์†์ ์—์„œ ๊ณ„ํ†ต์—ฐ๊ณ„ ๊ธฐ์ˆ ๊ธฐ์ค€์„ ์ถฉ์กฑํ•˜๊ธฐ ์œ„ํ•ด ์ ‘์†์ ์— ํ•„์š”ํ•œ ๋ฌดํšจ์ „๋ ฅ ๋ณด์ƒ์„ค๋น„๋Ÿ‰์„ ์‚ฐ์ถœํ•œ ๊ฒฐ๊ณผ์ด๋‹ค. ์ ‘์†์ ์— ์ง์ ‘ ์—ฐ๊ณ„ํ•˜์—ฌ ๋ณด์ƒํ•˜๊ธฐ ๋•Œ๋ฌธ์—, ํ•ด๋‹น ๋ฌดํšจ์ „๋ ฅ์€ ์†์‹ค ์—†์ด ๋ชจ๋‘ ์ ‘์†์ ์— ์ „๋‹ฌ๋˜๊ฒŒ ๋œ๋‹ค. ๋•Œ๋ฌธ์—, ํ•„์š”ํ•œ ๋ฌดํšจ์ „๋ ฅ ๋ณด์ƒ๋Ÿ‰์ด ํฌ๊ฒŒ ์ค„์–ด๋“ค์ง€ ์•Š๋Š” ์–‘์ƒ์„ ๋ณด์ธ๋‹ค. ์ด๋ฅผ ๊ฒ€์ฆํ•˜๊ธฐ ์œ„ํ•ด, ๊ฐ ์œ ํšจ์ „๋ ฅ ์ถœ๋ ฅ์ด 20%์ผ ๋•Œ์™€ 100%์ผ ๋•Œ๋ฅผ ๋น„๊ตํ•œ ๊ทธ๋ฆผ์„ <๊ทธ๋ฆผ 8>๊ณผ <๊ทธ๋ฆผ 9>๋ฅผ ํ†ตํ•ด ๋น„๊ตํ•˜์˜€๋‹ค. ์ ‘์†์ ์—์„œ ๋ฌดํšจ์ „๋ ฅ ๊ณต๊ธ‰๋Šฅ๋ ฅ ๋ฒ”์œ„๋ฅผ ๋งŒ์กฑํ•  ๋•Œ, ๋ฌดํšจ์ „๋ ฅ์„ ๊ณ„ํ†ต์œผ๋กœ๋ถ€ํ„ฐ ํก์ˆ˜ํ•˜๋Š” ์กฐ๊ฑด(๊ณ„ํ†ต์ „์•• 1.1pu)์—์„œ ์œ ํšจ์ „๋ ฅ ์ถœ๋ ฅ์ด 20%์ธ ๊ฒฝ์šฐ์™€ ์œ ํšจ์ „๋ ฅ ์ถœ๋ ฅ์ด 100%์ธ ๊ฒฝ์šฐ ์กฐ๋ฅ˜ ํ๋ฆ„์„ ๋น„๊ตํ•˜์˜€๋‹ค. ์œ ํšจ์ „๋ ฅ ์ถœ๋ ฅ์ด 20%์ธ ๊ฒฝ์šฐ๋ฅผ <๊ทธ๋ฆผ 8>, 100%์ธ ๊ฒฝ์šฐ๋ฅผ <๊ทธ๋ฆผ 9>์— ๋‚˜ํƒ€๋‚ด์—ˆ๋‹ค.

๊ทธ๋ฆผ 8. ์ ‘์†์ ์—์„œ ๋ฌดํšจ์ „๋ ฅ ๊ณต๊ธ‰๋Šฅ๋ ฅ์„ ๋งŒ์กฑํ•  ๋•Œ, ๋ฌดํšจ์ „๋ ฅ์„ ๊ณ„ํ†ต์œผ๋กœ๋ถ€ํ„ฐ ํก์ˆ˜ํ•˜๋Š” ์กฐ๊ฑด์—์„œ ์œ ํšจ์ „๋ ฅ ์ถœ๋ ฅ์ด 20%์ธ ๊ฒฝ์šฐ, ์œ ํšจ์ „๋ ฅ ๋ฐ ๋ฌดํšจ์ „๋ ฅ ์กฐ๋ฅ˜

Fig. 8. Active and reactive power flows when absorbing reactive power from the grid at 20% active power output while meeting reactive power capability at the point of connection

../../Resources/kiee/KIEE.2025.74.2.238/fig8.png

๊ทธ๋ฆผ 9. ์ ‘์†์ ์—์„œ ๋ฌดํšจ์ „๋ ฅ ๊ณต๊ธ‰๋Šฅ๋ ฅ์„ ๋งŒ์กฑํ•  ๋•Œ, ๋ฌดํšจ์ „๋ ฅ์„ ๊ณ„ํ†ต์œผ๋กœ๋ถ€ํ„ฐ ํก์ˆ˜ํ•˜๋Š” ์กฐ๊ฑด์—์„œ ์œ ํšจ์ „๋ ฅ ์ถœ๋ ฅ์ด 100%์ธ ๊ฒฝ์šฐ, ์œ ํšจ์ „๋ ฅ ๋ฐ ๋ฌดํšจ์ „๋ ฅ ์กฐ๋ฅ˜

Fig. 9. Active and reactive power flows when absorbing reactive power from the grid at 100% active power output while meeting reactive power capability at the point of connection

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3. ๊ฒฐ ๋ก 

๋ณธ ๋…ผ๋ฌธ์—์„œ๋Š” ๋Œ€๊ทœ๋ชจ ํ•ด์ƒํ’๋ ฅ๋‹จ์ง€๊ฐ€ ๊ธฐ์กด ์œก์ง€๊ณ„ํ†ต์— ์—ฐ๊ณ„ํ•˜๊ธฐ ์œ„ํ•ด ์‹ ์žฌ์ƒ๋ฐœ์ „๊ธฐ ์†ก์ „๊ณ„ํ†ต์—ฐ๊ณ„ ๊ธฐ์ˆ ๊ธฐ์ค€์„ ๋”ฐ๋ผ์•ผ ํ•˜๋Š”๋ฐ, ์ด๋•Œ ๋ฌดํšจ์ „๋ ฅ ๊ณต๊ธ‰๋Šฅ๋ ฅ์— ๋Œ€ํ•˜์—ฌ ๋ฌดํšจ์ „๋ ฅ ๊ณต๊ธ‰๋Šฅ๋ ฅ ํ‰๊ฐ€ ๊ธฐ์ค€์  ์ฐจ์ด์— ๋”ฐ๋ผ ์—ฐ๊ณ„์ ๊ณผ ๊ธฐ์ค€์ ์—์„œ์˜ ๋ฌดํšจ์ „๋ ฅ ๋ณด์ƒ๋Ÿ‰์„ ๋น„๊ตํ•˜์˜€๋‹ค. ํ•ด์ƒํ’๋ ฅ๋‹จ์ง€์˜ ํ•ด์ €์ผ€์ด๋ธ”์˜ ์ถฉ์ „ ์ „๋ฅ˜์œผ๋กœ ์ธํ•ด ์ฒซ ๋ฒˆ์งธ ์‚ฌ๋ก€์™€ ๋‘ ๋ฒˆ์งธ ์‚ฌ๋ก€์˜ ๋ชจ๋“  ์œ ํšจ์ „๋ ฅ ์ถœ๋ ฅ ์ƒํ™ฉ์—์„œ ๋ฌดํšจ์ „๋ ฅ์„ ํก์ˆ˜ํ•˜์—ฌ์•ผ ๊ณ„ํ†ต์—ฐ๊ณ„ ์กฐ๊ฑด์„ ๋งŒ์กฑ์‹œํ‚ฌ ์ˆ˜ ์žˆ์—ˆ๋‹ค. ์ฒซ ๋ฒˆ์งธ ์‚ฌ๋ก€์ธ ์—ฐ๊ณ„์ ์—์„œ ๋ฌดํšจ์ „๋ ฅ ๋ณด์ƒ๋Ÿ‰ ๊ฒฐ๊ณผ์˜ ์œ ํšจ์ „๋ ฅ ์ถœ๋ ฅ์ด 0% ์ƒํ™ฉ์ผ ๋•Œ, ํ•„์š” ๋ฌดํšจ์ „๋ ฅ ๋ณด์ƒ๋Ÿ‰์€ 4,514MVAr ์˜€์ง€๋งŒ, ๋‘ ๋ฒˆ์งธ ์‚ฌ๋ก€์ธ ์ ‘์†์ ์—์„œ ๋ฌดํšจ์ „๋ ฅ ๋ณด์ƒ๋Ÿ‰ ๊ฒฐ๊ณผ์˜ ์œ ํšจ์ „๋ ฅ ์ถœ๋ ฅ์ด 0% ์ƒํ™ฉ์ผ ๋•Œ, ํ•„์š” ๋ฌดํšจ์ „๋ ฅ ๋ณด์ƒ๋Ÿ‰์€ 3,982MVAr๋กœ 532MVAr ์ •๋„๊ฐ€ ๋œ ํ•„์š”ํ•˜๊ฒŒ ๋˜์—ˆ๋‹ค. ์ฒซ ๋ฒˆ์งธ ์‚ฌ๋ก€์ธ ์—ฐ๊ณ„์ ์—์„œ์˜ ๊ฒ€ํ†  ๊ฒฐ๊ณผ์™€ ๋‘ ๋ฒˆ์งธ ์‚ฌ๋ก€์ธ ์ ‘์†์ ์—์„œ์˜ ๊ฒ€ํ†  ๊ฒฐ๊ณผ๋ฅผ ๋น„๊ตํ•˜์˜€์„ ๋•Œ, ๋Œ€๊ทœ๋ชจ ํ•ด์ƒํ’๋ ฅ๋‹จ์ง€๊ฐ€ ๊ณ„ํ†ต ์ ‘์† ๊ทœ์ •์„ ๋งŒ์กฑํ•˜๊ธฐ ์œ„ํ•ด ํ•„์š”ํ•œ ๋ฌดํšจ์ „๋ ฅ ๋ณด์ƒ๋Ÿ‰์ด ๋‘ ๋ฒˆ์งธ ์‚ฌ๋ก€์ธ ์ ‘์†์ ์—์„œ์˜ ํ•„์š”ํ•œ ๋ฌดํšจ์ „๋ ฅ ๋ณด์ƒ๋Ÿ‰์ด ๋” ์ ์€ ๊ฒƒ์„ ํ™•์ธํ•  ์ˆ˜ ์žˆ๋‹ค. ์ด๋Š” ํ•ด์ƒํ’๋ ฅ ์‚ฌ์—…์ž์—๊ฒŒ ๋ฌดํšจ์ „๋ ฅ ๋ณด์ƒ์„ค๋น„ ์„ค์น˜์— ๋Œ€ํ•œ ๊ฒฝ์ œ์ ์ธ ๋ถ€๋ถ„์„ ์™„ํ™”ํ•  ์ˆ˜ ์žˆ์Œ์„ ์˜๋ฏธํ•œ๋‹ค. ๋˜ํ•œ, <๊ทธ๋ฆผ 7>์˜ ์ ‘์†์ ์—์„œ ๋ฌดํšจ์ „๋ ฅ ๊ณต๊ธ‰๋Šฅ๋ ฅ์„ ๋งŒ์กฑํ•  ๋•Œ, ์—ฐ๊ณ„์ ์—์„œ ๋ฌดํšจ์ „๋ ฅ ๊ณต๊ธ‰๋Šฅ๋ ฅ ๊ฒฐ๊ณผ๋ฅผ ๋ณด๊ฒŒ ๋˜๋ฉด, ๊ณต๊ธ‰ํ•˜๋Š” ๊ฒฝ์šฐ์—์„œ๋Š” ๊ธฐ์ค€๋ณด๋‹ค ๋” ๋งŽ์€ ๋ฌดํšจ์ „๋ ฅ์„ ๊ณต๊ธ‰ํ•˜๊ณ  ํก์ˆ˜ํ•˜๋Š” ๊ฒฝ์šฐ์—์„œ๋Š” ๊ธฐ์ค€๋ณด๋‹ค ๋ฌดํšจ์ „๋ ฅ์„ ํก์ˆ˜๋ฅผ ๋ชปํ•˜๋Š” ๊ฒฐ๊ณผ๋ฅผ ๋ณด์ธ๋‹ค. ๋‹ค์‹œ ๋งํ•ด, ์ ‘์†์ ์—์„œ ๋ฌดํšจ์ „๋ ฅ ๊ณต๊ธ‰๋Šฅ๋ ฅ ๊ธฐ์ค€์„ ์ ์šฉํ•˜๋ฉด, ์—ฐ๊ณ„์ ์—์„œ ๊ณต๊ธ‰์ธ ๊ฒฝ์šฐ๋Š” ๋ฌดํšจ์ „๋ ฅ ๊ณต๊ธ‰๋Šฅ๋ ฅ์ด ์ž‰์—ฌ๋˜๊ณ , ํก์ˆ˜์ธ ๊ฒฝ์šฐ๋Š” ๋ถ€์กฑํ•จ์„ ์˜๋ฏธํ•œ๋‹ค. ๋”ฐ๋ผ์„œ, ๋ฌดํšจ์ „๋ ฅ ๊ณต๊ธ‰๋Šฅ๋ ฅ์„ ํ‰๊ฐ€ํ•˜๋Š” ๊ธฐ์ค€์ ์— ๋”ฐ๋ผ ๋ฌดํšจ์ „๋ ฅ ํ•„์š” ๋ณด์ƒ๋Ÿ‰ ์ฐจ์ด์™€ ๋ฌดํšจ์ „๋ ฅ ๊ณต๊ธ‰๋Šฅ๋ ฅ ๋ฒ”์œ„์—์„œ ์ž‰์—ฌ ๋ฐ ๋ถ€์กฑ์ด ๋ฐœ์ƒํ•  ์ˆ˜ ์žˆ๋‹ค.

Acknowledgements

๋ณธ ์—ฐ๊ตฌ(No.20210501010010)๋Š” ์‚ฐ์—…ํ†ต์ƒ์ž์›๋ถ€์˜ ์žฌ์›์œผ๋กœ ํ•œ๊ตญ์—๋„ˆ์ง€๊ธฐ์ˆ ํ‰๊ฐ€์›(KETEP)์˜ ์ง€์›์— ์˜ํ•˜์—ฌ ์ด๋ฃจ์–ด์ง„ ์—ฐ๊ตฌ๋กœ์„œ, ๊ด€๊ณ„๋ถ€์ฒ˜์— ๊ฐ์‚ฌ๋“œ๋ฆฝ๋‹ˆ๋‹ค.

๋ณธ ์—ฐ๊ตฌ(No.20225500000060)๋Š” ์‚ฐ์—…ํ†ต์ƒ์ž์›๋ถ€์˜ ์žฌ์›์œผ๋กœ ํ•œ๊ตญ์—๋„ˆ์ง€๊ธฐ์ˆ ํ‰๊ฐ€์›(KETEP)์˜ ์ง€์›์— ์˜ํ•˜์—ฌ ์ด๋ฃจ์–ด์ง„ ์—ฐ๊ตฌ๋กœ์„œ, ๊ด€๊ณ„๋ถ€์ฒ˜์— ๊ฐ์‚ฌ๋“œ๋ฆฝ๋‹ˆ๋‹ค.

References

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X. Sun, D. Huang, and G. Wu, โ€œThe current state of offshore wind energy technology development,โ€ Energy, vol. 41, no. 1, pp. 298~312, May 2012. DOI:10.1016/j.energy.2012.02.054DOI
2 
J.-A. Perez-Rua, M. Stolpe, K. Das, and N. A. Cutululis, โ€œGlobal Optimization of Offshore Wind Farm Collection Systems,โ€ IEEE Transactions on Power Systems, vol. 35, no. 3, pp. 2256~2267, May 2020. DOI:10.1109/tpwrs.2019.2957312.DOI
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Meiqi Yao, and L. Yao, โ€œIntegration of large scale wind farm into electrical grids,โ€ CICED 2010 Proceedings, pp. 1~5, 2010.URL
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Sukhyun Kang, and Injae Kim, โ€œA study on the transmission voltage selection of an AC export cable system and countermeasures to compensate for its reactive power for the connection of a 400 MW offshore wind farm to a power system,โ€ Journal of Wind Energy, vol. 13, no.1, pp. 21~29, 2022. DOI:10.33519/kwea.2022.13.1.003DOI
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Ji-Min Lee, Jaeyeop Jung, and Gyu-sub Lee, โ€œMethodology for Reactive Power Compensation in Offshore Wind Farm Inconnected Systems,โ€ Proceedings of the KIEE Conference, pp. 278~279, 2023.URL
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KEPCO, Renewable Energy Technical Connection Code for Transmission Level, pp.12, 2024.URL

์ €์ž์†Œ๊ฐœ

์ตœ์ง„ํ˜ธ(Jin-Ho Choi)
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He received the B.S. degrees in the Department of Electrical Engineering from Gachon University, Seongnam, South Korea, in 2023. He is a current M.S. course student in Energy Engineering at the Korea Institute of Energy Technology (KENTECH), Naju, South Korea.

์ •์žฌ์—ฝ(Jaeyeop Jung)
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He received the B.S. and Ph.D. degrees in Electrical Engineering from Korea University, Seoul, South Korea, in 2016 and 2023, respectively. Since 2023, he has been working as a Research Professor in Korea Institute of Energy Technology (KENTECH), Naju, South Korea.

๋ฌธ์Šน์ผ(Seung-Il Moon)
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He received the B.S. in the Department of Electrical Engineering from Seoul National University, Seoul, South Korea, in 1985 and M.S. and Ph.D. degrees in Electrical Engineering from Ohio State University, Columbus, OH, USA, in 1989 and 1993, respectively. He is currently working as a Distinguished Professor in Korea Institute of Energy Technology (KENTECH), Naju, South Korea.

์ด๊ทœ์„ญ(Gyu-Sub Lee)
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He received the B.S. and Ph.D. degrees in Electrical and Computer Engineering from Seoul National University (SNU), Seoul, South Korea, in 2013 and 2020, respectively. From 2020 to 2021, he was a Senior Researcher and R&D Manager with Seoul National University Electric Power Research Institute, Seoul, South Korea. From 2021 to 2024, he was an Assistant Professor with the Korea Institute of Energy Technology (KENTECH), Naju, South Korea. From March 2024, he has been working as an Assistant Professor in Dept. Electrical and Computer Engineering (ECE), Seoul National University (SNU), affiliated with the Seoul National University Electric Power Research Institute in Seoul, South Korea.