Comparative Study on 220V AC Feed System and 300V DC Feed System for Internet Data Centers

김효성 전력전자학회 2012 JOURNAL OF POWER ELECTRONICS Vol.12 No.1

Internet Data Centers (IDCs), which are essential facilities in the modern IT industry, typically have scores of MW of concentrated electric loads. The provision of an Uninterruptible Power Supply (UPS) is necessary for the power feed system of IDCs owing to the need for stable power. Thus, conventional IDC AC power feed systems have three cascaded power conversion stages, (AC-DC), (DC-AC), and (AC-DC), resulting in a very low conversion efficiency. In comparison, DC power feed systems require only a single power conversion stage (AC-DC) to supply AC main power to DC server loads, resulting in comparatively high conversion efficiency and reliability [4-11]. This paper compares the efficiencies of a 220V AC power feed system with those of a 300V DC power feed system under equal load conditions, as established by the Mok-Dong IDC of Korea Telecom Co. Ltd. (KT). Experimental results show that the total operation efficiency of the 300V DC power feed system is approximately 15% higher than that of the 220V AC power feed system.

Comparative Study on 220V AC Feed System and 300V DC Feed System for Internet Data Centers

Hyosung Kim 전력전자학회 2012 JOURNAL OF POWER ELECTRONICS Vol.12 No.1

Internet Data Centers (IDCs), which are essential facilities in the modern IT industry, typically have scores of MW of concentrated electric loads. The provision of an Uninterruptible Power Supply (UPS) is necessary for the power feed system of IDCs owing to the need for stable power. Thus, conventional IDC AC power feed systems have three cascaded power conversion stages, (AC-DC), (DC-AC), and (AC-DC), resulting in a very low conversion efficiency. In comparison, DC power feed systems require only a single power conversion stage (AC-DC) to supply AC main power to DC server loads, resulting in comparatively high conversion efficiency and reliability [4-11]. This paper compares the efficiencies of a 220V AC power feed system with those of a 300V DC power feed system under equal load conditions, as established by the Mok-Dong IDC of Korea Telecom Co. Ltd. (KT). Experimental results show that the total operation efficiency of the 300V DC power feed system is approximately 15% higher than that of the 220V AC power feed system.

Comparative Study on 220V AC Feed System and 300V DC Feed System for Internet Data Centers

Kim, Hyo-Sung The Korean Institute of Power Electronics 2012 JOURNAL OF POWER ELECTRONICS Vol.12 No.1

Internet Data Centers (IDCs), which are essential facilities in the modern IT industry, typically have scores of MW of concentrated electric loads. The provision of an Uninterruptible Power Supply (UPS) is necessary for the power feed system of IDCs owing to the need for stable power. Thus, conventional IDC AC power feed systems have three cascaded power conversion stages, (AC-DC), (DC-AC), and (AC-DC), resulting in a very low conversion efficiency. In comparison, DC power feed systems require only a single power conversion stage (AC-DC) to supply AC main power to DC server loads, resulting in comparatively high conversion efficiency and reliability [4-11]. This paper compares the efficiencies of a 220V AC power feed system with those of a 300V DC power feed system under equal load conditions, as established by the Mok-Dong IDC of Korea Telecom Co. Ltd. (KT). Experimental results show that the total operation efficiency of the 300V DC power feed system is approximately 15% higher than that of the 220V AC power feed system.

300V DC Feed System for Internet Data Center

Du-Hwan Kim,Taesik Yu,Hyosung Kim,Hyungsoo Mok,Kyung-Seok Park 전력전자학회 2011 ICPE(ISPE)논문집 Vol.2011 No.5

Internet Data Centers (IDC), as essential facilities for modern IT industry, typically have scores of ㎿ of concentrated electric loads. Uninterruptible Power Supplies (UPS) are necessary for the power feed system of IDCs because of stable power requirement. Thus, conventional AC power feed systems of IDCs have three cascaded power conversion stages such as (AC-DC), (DCAC), and (AC-DC), which results in very low conversion efficiency. On the contrary, DC power feed systems need just a single power conversion stage (AC-DC) supplying AC mains power to DC server loads, which gives comparatively high conversion efficiency and reliability [5]. This paper compares the efficiencies between 220V AC power feed system and 300V DC power feed system on equal load conditions which were established in Mok-Dong IDC of Korea Telecom Co. Ltd. (KT). Experimental results show that the total operation efficiency of the 300V DC power feed system is around 15% higher than that of the 220V AC power feed system.

Reliability Modeling of Direct Current Power Feeding Systems for Green Data Center

Jung Yul Choi 대한전기학회 2013 Journal of Electrical Engineering & Technology Vol.8 No.4

Data center is an information hub and resource for information-centric society. Since data center houses hundreds to ten thousands servers, networking and communication equipment, and supporting systems energy saving is one of the hottest issues for green data center. Among several solutions for green data center this paper introduces higher voltage direct current (DC) power feeding system. Contrary to legacy alternating current (AC) power feeding system equipped with Uninterruptible Power Supply (UPS), higher voltage DC power feeding system is reported to be a more energy efficient and reliable solution for green data center thanks to less AC/DC and DC/AC conversions. Main focus of this paper is on reliability issue for reliable and continuous operation of higher voltage DC power feeding system. We present different types of configuration of the power feeding systems according to the level of reliability. We analyze the reliability of the power feeding systems based on M/M/1/N+1/N+1 queueing model. Operation of the power feeding system in case of failure is also presented.

Design and Assessment of DC Traction Power Supply System for Light Rail Transit

백병산,문종필,최준호,김재철,Baek, Byung-San,Moon, Jong-Fil,Choi, Joon-Ho,Kim, Jae-Chul The Korean Institute of IIIuminating and Electrica 2006 조명·전기설비학회논문지 Vol.20 No.4

전기철도 급전시스템의 설계와 평가에 관련하여 어려운 점은 고려해야 할 요소들이 많고, 시스템적 접근이 요구되나 단편적인 논문과 엔지니어링 측면의 접근이 대부분이다. 본 논문에서는 전기철도 시스템 중 국내외에서 최근 활발히 추진되고 있는 경량전철을 위한 직류 급전시스템의 설계 및 그의 적정성을 평가하는 기법을 체계화하였다. 먼저, 급전 시스템의 구성요소인 급전 변전소와 부하인 차량과 그리고 전력선을 포함한 전체 시스템의 특성파악하고 분석하였다. 실제 계통과 동일하게 모델링하기 위하여 축약 및 등가화를 하였으며, 등가화한 시스템을 해석하기 위한 방안으로 노드방정식과 반복접근법을 적용하였으며, 이를 체계화하여 모의절차, 평가 및 설계방법을 제시하였다. 제시한 알고리즘 및 설계절차에 따라 프로그램을 개발하였으며 사례연구를 통하여 그 유효성을 입증하였다. For the design of DC traction power supply system at new Light Rail Transit(LRT) construction, it is very important to determine system configuration, location and power capacity of substation. However, a LRT system consists of a number of subsystems such as train movement, power supply and traction drives, which inevitably contains many complexities and diversities. The objective of this paper is to clarify and systematize the design procedure and its assessment for the electrification system of a LRT line. This paper discusses in detail our approach to system design and its assessment. The whole DC-feeding network configuration, characteristics of a train, and design method of substation arrangements is thoroughly investigated for the design. As a result of the investigations, the design procedure is clarified and systematized and a computer program for the design and evaluation of the system is developed using the most suitable iterative method with nodal equation. To verify the proposed design and its assessment procedure, case studies for the DC traction power supply system of a planed Korean LRT line are performed.

고무차륜시스템에서의 지락보호를 위한 급전선로 절연과 부극전위와의 영향 분석

정호성(Hosung Jung),신승권(Seongkuen Shin),김형철(Hyungchul Kim),박영(Young Park),조상훈(Sanghoon Cho) 대한전기학회 2013 전기학회논문지 Vol.62 No.4

We have analyzed influence of potential rise in negative bus, which caused by decrease of power feeding line insulation, upon protecting method of DC ground protection device which detecting potential rise between negative bus and ground in order to detect ground fault in the rubber wheel system. For this purpose, we proposed negative potential equation between negative bus and ground and calculated negative potential according to system condition changes by estimating power feeding line insulation changes in steel wheel system and rubber wheel system, and equalizing DC power feeding system when ground fault occurred. Also, in order to estimate negative potential of real system, we modeled the rubber wheel system, and simulated normal status, grounding fault occurrence and power feeding line insulation changes. In normal status, negative potential did not rise significantly regardless of vehicle operation. When ground fault occurred, negative potential rose up over 300V regardless of fault resistance. However, we also observed that negative potential rose when power feeding line insulation dropped down under 1MΩ. In conclusion, our result shows that in case of rubber wheel system unlike steel wheel system, relay will be prevented maloperation and insulation status observation can be ensured when ground over voltage relay will be set 200V ~ 300V.

Novel DC Grid Connection Topology and Control Strategy for DFIG-based Wind Power Generation System

Yi, Xilu,Nian, Heng Journal of International Conference on Electrical 2013 Journal of international Conference on Electrical Vol.2 No.4

The paper presents a novel DC grid connection topology and control strategy for doubly-fed induction generator (DFIG) based wind power generation system. In order to achieve the wind power conversion, the stator side converter and the rotor side converter is used to implement the DFIG control based on the indirect air-gap flux orientation, and a DC/DC converter is used for the DFIG system to DC grid connection. The maximum power point tracking and DC voltage droop control can also be implemented for the proposed DFIG system. Finally, a 4-terminal DFIG-based multi-terminal DC grid system is developed by Matlab to validate the availability of the proposed system and control strategy.

A Feasibility Design of PEMFC Parallel Operation for a Fuel Cell Generation System

Kang, Hyun-Soo,Choe, Gyu-Yeong,Lee, Byoung-Kuk,Hur, Jin The Korean Institute of Electrical Engineers 2008 Journal of Electrical Engineering & Technology Vol.3 No.3

In this paper, the parallel operation for a FC generation system is introduced and designed in order to increase the capacity for the distributed generation of a proton exchange membrane fuel cell (PEMFC) system. The equipment is the type that is used by parallel operated PEMFC generation systems which have two PEMFC systems, two dc/dc boost converters with shared dc link, and a grid-connected dc/ac inverter for embedded generation. The system requirement for the purpose of parallel operated generation using PEMFC system is also described. Aspects related to the mechanical (MBOP) and electrical (EBOP) component, size, and system complexity of the distributed generation system, it is explained in order to design an optimal distributed generation system using PEMFC. The optimal controller design for the parallel operation of the converter is suggested and informative simulations and experimental results are provided.

Reliability Modeling of Direct Current Power Feeding Systems for Green Data Center

최정열 대한전기학회 2013 Journal of Electrical Engineering & Technology Vol.8 No.4

Data center is an information hub and resource for information-centric society. Since data center houses hundreds to ten thousands servers, networking and communication equipment, and supporting systems energy saving is one of the hottest issues for green data center. Among several solutions for green data center this paper introduces higher voltage direct current (DC) power feeding system. Contrary to legacy alternating current (AC) power feeding system equipped with Uninterruptible Power Supply (UPS), higher voltage DC power feeding system is reported to be a more energy efficient and reliable solution for green data center thanks to less AC/DC and DC/AC conversions. Main focus of this paper is on reliability issue for reliable and continuous operation of higher voltage DC power feeding system. We present different types of configuration of the power feeding systems according to the level of reliability. We analyze the reliability of the power feeding systems based on M/M/1/N+1/N+1 queueing model. Operation of the power feeding system in case of failure is also presented.