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전기추진선박의 통합전력계통 시뮬레이션 모델에 관한 연구
구현근(Hyun-Keun Ku),곽기곤(Ki-Kon Kwak),김장목(Jang-Mok Kim) 전력전자학회 2015 전력전자학회 논문지 Vol.20 No.1
The simulation model of All-Electric-Ship consists of electrical and mechanical systems. Running the total simulation requires considerable time and causes a lack of computer memory, because the two systems have different dynamic characteristics. Therefore, integrated simulation is practically impossible. This paper proposes the simplified model of electrical system to reduce simulation time significantly, compared to the detailed model. The validity of the proposed simplified model is verified by comparing detailed and simplified simulation results. Thus, the simplified models are applied to the integrated system. As a result, total system simulation can be implemented.
과풍속 영역에서의 약계자 제어를 이용한 풍력발전용 3상 PWM 컨버터의 출력제어
구현근(Hyun-Keun Ku),김재흥(Jae-Heung Kim),이형욱(Hyung-Uk Lee),김장목(Jang-Mok Kim) 전력전자학회 2014 전력전자학회 논문지 Vol.19 No.2
This paper proposes the battery charging algorithm for small-scale wind power generator using three phase PWM converter. it is impossible to control output power of the converter in over wind speed region since back EMF of PMSG is higer than battery voltage. Therefore, battery charging algorithm is proposed to expand battery charging over wind speed region. The suggested method is using the q-axis current for battery charging in the rated wind speed region. In the over wind speed region after it lower back EMF of PMSG using d-axis current it can control output power of the converter. The validity of the proposed algorithm are verified by experiments.
배터리 충전을 위한 소형풍력 발전 시스템의 한계 풍속에 관한 연구
구현근(Hyun-Keun Ku),이형욱(Hyung-Uk Lee),김장목(Jang-Mok Kim) 대한전기학회 2014 전기학회논문지 Vol.63 No.4
Three phase PWM(Pulse Width Modulation) converter of the small-scale wind power system is able to charge battery under the rated wind speed regions. However, it is impossible to control output power of converter at the over win speed region because back-EMF(Electro Motive Force) of PMSG(Permanent Magnet Synchronous Generator) is higher than the battery terminal voltage of PMSG is reduced. However, the cut-off wind speed exists although battery charging algorithm is implemented by flux weakening control method. Therefore, this paper performs analysis of other factors which affects limitation wind speed. The validity of the analysis are verified through simulation.
박인권,이종후,이장,구현근,권용한,In Kwon, Park,Yi, Zhong Hu,Yi, Zhang,Hyun Keun, Ku,Yong Han, Kwon Korea Electric Power Corporation 2022 KEPCO Journal on electric power and energy Vol.8 No.2
Often a network becomes complex, and multiple entities would get in charge of managing part of the whole network. An example is a utility grid. While the entire grid would go under a single utility company's responsibility, the network is often split into multiple subsections. Subsequently, each subsection would be given as the responsibility area to the corresponding sub-organization in the utility company. The issue of how to make subsystems of adequate size and minimum number of interconnections between subsystems becomes more critical, especially in real-time simulations. Because the computation capability limit of a single computation unit, regardless of whether it is a high-speed conventional CPU core or an FPGA computational engine, it comes with a maximum limit that can be completed within a given amount of execution time. The issue becomes worsened in real time simulation, in which the computation needs to be in precise synchronization with the real-world clock. When the subject of the computation allows for a longer execution time, i.e., a larger time step size, a larger portion of the network can be put on a computation unit. This translates into a larger margin of the difference between the worst and the best. In other words, even though the worst (or the largest) computational burden is orders of magnitude larger than the best (or the smallest) computational burden, all the necessary computation can still be completed within the given amount of time. However, the requirement of real-time makes the margin much smaller. In other words, the difference between the worst and the best should be as small as possible in order to ensure the even distribution of the computational load. Besides, data exchange/communication is essential in parallel computation, affecting the overall performance. However, the exchange of data takes time. Therefore, the corresponding consideration needs to be with the computational load distribution among multiple calculation units. If it turns out in a satisfactory way, such distribution will raise the possibility of completing the necessary computation in a given amount of time, which might come down in the level of microsecond order. This paper presents an effective way to split a given electrical network, according to multiple criteria, for the purpose of distributing the entire computational load into a set of even (or close to even) sized computational loads. Based on the proposed system splitting method, heavy computation burdens of large-scale electrical networks can be distributed to multiple calculation units, such as an RTDS real time simulator, achieving either more efficient usage of the calculation units, a reduction of the necessary size of the simulation time step, or both.