• Title, Summary, Keyword: Stand-alone

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Seamless Transfer Operation Between Grid-connected and Stand-Alone Mode in the Three-phase Inverter (3상 인버터의 계통연계 및 독립운전모드 전환 연구)

  • Lee, Wujong;Jo, Hyunsik;Lee, Hak Ju;Cha, Hanju
    • The Transactions of The Korean Institute of Electrical Engineers
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    • v.62 no.2
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    • pp.201-207
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    • 2013
  • This paper propose seamless transfer operation between grid-connected and stand-alone mode in the three-phase inverter for microgrid. The inverter operates grid-connected mode and stand-alone mode. Grid-connected mode is the inverter connected to grid and stand-alone mode is to deliver energy to the load from inverter at grid fault. When conversion from gird-connected to stand-alone mode, the inverter changes current control to voltage control. When grid restored, the inverter system is conversion from stand-alone to grid-connected mode. In this case, load phase and grid phase are different. Therefore, synchronization is essential. Thus Seamless transfer operation stand-alone to grid-connected mode. In this paper, propose sealmless transfer operation between grid-connceted and stand-alome mode, and this method is verified through simulation and experiment.

Analysis of Voltage Control of Stand-Alone Microgrid for High Quality Power Supply (고품질 전력공급을 위한 독립형 마이크로그리드의 전압제어 해석)

  • Jo, Jongmin;Lee, Hakju;Shin, Chang-hoon;Cha, Hanju
    • KEPCO Journal on Electric Power and Energy
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    • v.2 no.2
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    • pp.253-257
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    • 2016
  • This paper analyzes voltage control method in order to supply high-quality power for stand-alone microgrid. Stand-alone microgrid is composed of battery bank, stand-alone PCS and controllable loads. The main role of stand-alone PCS is to supply high-quality power to loads as main source by using stable voltage method regardless of load conditions. In particularly, output voltage of stand-alone PCS gets severely unbalanced voltage under unbalanced loads. Fundamental positive and negative sequences are transformed by two coordinates transformation which are rotated in each opposite direction, respectively. Each fundamental d-q voltage is regulated by each fundamental PI control. In addition, low-order harmonics are compensated through resonant controllers. Performance of stand-alone microgrid is tested for feasibility, and it is verified that output voltage of THD is improved to 1% from 2.2% under 50 kW balanced load, and is improved to 1.1% from 2.6% under 50 kW unbalanced load.

Study on the operating range of stand-alone sensor in consideration of the impacts of combustion products on residents (연소생성물이 거주자에 미치는 영향을 고려한 단독경보형감지기의 작동범위에 대한 연구)

  • Lee, Jong-Hwa;Kim, Si-Kuk;Jee, Seung-Wook;Kim, Pil-Young;Lee, Chun-Ha
    • Journal of the Korea Safety Management & Science
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    • v.14 no.1
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    • pp.23-31
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    • 2012
  • Recent research on stand-alone focused on the improvement and development of functions for solving problems such as the limited operating time of stand-alone installed at dwelling and their low reliability caused by false alarms, but it is more urgent to study on the operating range of stand-alone sensor in consideration of the impacts of combustion products on residents because the primary goal of fire safety is minimizing casualties. This study purposed to propose the optimized operating range of stand-alone sensor in consideration of the impacts of combustion products on residents. For this purpose, we made a mathematical approach to the change of temperature over the lapse of time in compartment fires similar to house fires, and established the standards of the body's response against heat and smoke based on literature review. In addition, we surveyed domestic and foreign technological standards for stand-alone sensor, and converted them to standards for residents of the body's response against heat and smoke using mathematical model equations and analyzed them comparatively.

Voltage Control of Stand-Alone Inverter for Power Quality Improvement Under Unbalanced and Non-linear Load (불평형 및 비선형부하 시 전력품질 향상을 위한 독립형 인버터의 전압제어 기법)

  • Lee, Wujong;Jo, Jongmin;Cha, Hanju
    • The Transactions of The Korean Institute of Electrical Engineers
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    • v.65 no.4
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    • pp.567-575
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    • 2016
  • This paper proposed the voltage control of stand-alone inverter for power quality improvement under unbalanced and non-linear load. The 3-phase DC-AC inverter controls CVCF(Constant Voltage Constant Frequency) and selective harmonic eliminate method in stand-alone mode by PR controller, and the stand-lone inverter supplies stable sinusoidal voltage to balanced, unbalanced and non-linear loads. The total harmonic distortion(THD) of line-to-line load voltage($V_{LL}$) is 1.2% in the balanced load. THD of $V_{LL}$ is reduced from 5.2% to 1.4% and 6.7% to 3.5%, respectively unbalanced and non-linear load. The stand-alone inverter can be supplies sinusoidal balanced voltage to unbalanced load because the voltage unbalanced factor(VUF) of $V_{LL}$ is reduced from 5.2% to 1.4% in the unbalanced load. Feasibility of control method for a stand-alone inverter will be verified through 30kW stand-alone inverter system.

Real-time Operation Analysis for Stand-alone Microgrid using RTDS (RTDS를 이용한 독립형 마이크로그리드의 실시간 동작 분석)

  • Lee, Yoon-Seok;Han, Byung-Moon;Won, Dong-Jun;Lee, Hak Ju
    • The Transactions of The Korean Institute of Electrical Engineers
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    • v.63 no.10
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    • pp.1393-1401
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    • 2014
  • In this paper the operational characteristics of stand-alone microgrid was analyzed using RTDS simulation models. The accuracy of developed simulation models were verified by comparing with the analysis results using the PSCAD/EMTDC simulation models. The proper scenarios and operation algorithms were developed and analyzed in accordance with various situations that can occur in the actual system, so as to establish operation scheme for the stand-alone microgrid system. The developed simulation models can be effectively utilized to design a newly installed stand-alone microgrid and to develop various operation scenarios for stand-alone microgrid. And these models can be applied for analyzing the transient phenomena due to system fault so that system protection can be properly designed.

Coordinated Droop Control for Stand-alone DC Micro-grid

  • Kim, Hyun-Jun;Lee, Yoon-Seok;Kim, Jae-Hyuk;Han, Byung-Moon
    • Journal of Electrical Engineering and Technology
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    • v.9 no.3
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    • pp.1072-1079
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    • 2014
  • This paper introduces a coordinated droop control for the stand-alone DC micro-grid, which is composed of photo-voltaic generator, wind power generator, engine generator, and battery storage with SOC (state of charge) management system. The operation of stand-alone DC micro-grid with the coordinated droop control was analyzed with computer simulation. Based on simulation results, a hardware simulator was built and tested to analyze the performance of proposed system. The developed simulation model and hardware simulator can be utilized to design the actual stand-alone DC micro-grid and to analyze its performance. The coordinated droop control can improve the reliability and efficiency of the stand-alone DC micro-grid.

NeW Output Voltage Control Scheme Based on SoC Variation of BESS Applicable for Stand-alone DC Microgrid (독립형 DC 마이크로그리드에 적용 가능한 BESS의 SoC를 기반으로 한 새로운 출력전압 제어기법)

  • Yu, Seung-Yeong;Kim, Hyun-Jun;Han, Byung-Moon
    • The Transactions of The Korean Institute of Electrical Engineers
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    • v.65 no.7
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    • pp.1176-1185
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    • 2016
  • This paper proposes a new output voltage control scheme based on the SoC variation of the battery energy storage system (BESS) applicable for the stand-alone DC microgrid. The proposed control scheme provides relatively lower variation of the DC grid voltage than the conventional droop method. The performance of proposed control scheme was verified through computer simulations for a typical stand-alone DC microgrid which consists of BESS, photo-voltaic (PV) panel, engine generator (EG), and DC load. A scaled hardware prototype for the stand-alone DC microgrid with DSP controller was set up in the lab, and the proposed control algorithm was installed in the DSP controller. The test results were compared with the simulation results for performance verification and actual system implementation.

Dynamic Economic Dispatch and Control of a Stand-alone Microgrid in DongAo Island

  • Ma, Yiwei;Yang, Ping;Guo, Hongxia;Wang, Yuewu
    • Journal of Electrical Engineering and Technology
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    • v.10 no.4
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    • pp.1432-1440
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    • 2015
  • A dynamic economic dispatch and control method is proposed to minimize the overall generating cost for a stand-alone microgrid in DongAo Island, which is integrated with wind turbine generator, solar PV, diesel generator, battery storage, the seawater desalination system and the conventional loads. A new dispatching strategy is presented based on the ranking of component generation costs and two different control modes, in which diesel generator and battery storage alternate to act as the master power source to follow system power fluctuation. The optimal models and GA-based optimization process are given to minimize the overall system generating cost subject to the corresponding constraints and the proposed dispatch strategy. The effectiveness of the proposed method is verified in the stand-alone microgrid in DongAo Island, and the results provide a feasible theoretical and technical basis for optimal energy management and operation control of stand-alone microgrid.

Optimized Design and Coordinated Control for Stand-alone DC Micro-grid (독립형 DC 마이크로그리드의 최적화 설계와 협조적 제어)

  • Han, Tae-Hee;Lee, Ji-Heon;Kim, Hyun-Jun;Han, Byung-Moon
    • The Transactions of the Korean Institute of Power Electronics
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    • v.18 no.1
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    • pp.63-71
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    • 2013
  • This paper describes the coordinated droop control method for stand-alone type DC micro-grid to improve reliability and utilization of distributed generations and energy storage. The stand-alone type DC micro-grid consists of several distributed generations such as a wind power generation, solar power and micro-turbine, and energy storage. The proposed method which is based on autonomous control method shows high reliability and stability through coordinated droop control of distributed generations and energy storage and also capability of battery management. The operation of stand-alone type DC micro-grid was analyzed using detail simulation model with PSCAD/EMTDC software. Based on simulation results, a hardware simulator was built and tested with commercially available components and performance of system was verified.