• The Transactions of The Korean Institute of Electrical Engineers
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• v.67 no.6
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• pp.715-723
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• 2018

The energy storage system consists of batteries, power conditioning system and energy management system. If ESS is installed and operated in the field, SAT(Site Acceptance Test) of ESS is being essentially required for the safety and performance of ESS. Furthermore, in order to more accurately and reliably validate the performance of the ESS in advanced countries, it has been required to perform not only performance testing by H/W equipments but also performance verification by S/W tool. Therefore, this paper proposes the modeling of portable test equipment in order to evaluate the performance and reliability of ESS by using the PSCAD/EMTDC S/W. And also, the prototype of 30[kW] scaled portable test equipments is implemented based on the S/W modeling. From the results of various simulations and testings such as power quality, LVRT and anti-islanding tests, it is confirmed that 30[kW] scaled portable test equipment is useful for SAT of ESS, because the simulation results of PSCAD/EMTDC are identical to them of 30[kW] test equipment at the same test conditions.

• Journal of Power Electronics
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• v.17 no.1
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• pp.222-231
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• 2017

In this paper, a new architecture for a cost-effective power conditioning systems (PCS) using a single-sourced asymmetric cascaded H-bridge multilevel inverter (MLI) for photovoltaic (PV) applications is proposed. The asymmetric MLI topology has a reduced number of parts compared to the symmetrical type for the same number of voltage level. However, the modulation index threshold related to the drop in the number of levels of the inverter output is higher than that of the symmetrical MLI. This problem results in a modulation index limitation which is relatively higher than that of the symmetrical MLI. Hence, an extra voltage pre-regulator becomes a necessary component in the PCS under a wide operating bias variation. In addition to pre-stage voltage regulation for the constant MLI dc-links, another auxiliary pre-regulator should provide isolation and voltage balance among the multiple H-bridge cells in the asymmetrical MLI as well as the symmetrical ones. The proposed PCS uses a single-ended DC-DC converter topology with a coupled inductor and charge-pump circuit to satisfy all of the aforementioned requirements. Since the proposed integrated-type voltage pre-regulator circuit uses only a single MOSFET switch and a single magnetic component, the size and cost of the PCS is an optimal trade-off. In addition, the voltage balance between the separate H-bridge cells is automatically maintained by the number of turns in the coupled inductor transformer regardless of the duty cycle, which eliminates the need for an extra voltage regulator for the auxiliary H-bridge in MLIs. The voltage balance is also maintained under the discontinuous conduction mode (DCM). Thus, the PCS is also operational during light load conditions. The proposed architecture can apply the module-integrated converter (MIC) concept to perform distributed MPPT. The proposed architecture is analyzed and verified for a 7-level asymmetric MLI, using simulation results and a hardware implementation.

• Journal of the Korean Society of Safety
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• v.33 no.4
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• pp.1-7
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• 2018

This paper is analyzed for the thermal characteristics(1 year) of the 6 components(DC breaker, DC filter(including capacitor and discharge resistance), IGBT(Insulated gate bipolar mode transistor), AC filter, AC breaker, etc.) of a photovoltaic power generation-based PCS(Power conditioning system) below 20 kW. Among the modules, the discharge resistance included in the DC filter indicated the highest heat at $125^{\circ}C$, and such heat resulting from the discharge resistance had an influence on the IGBT installed on the rear side the board. Therefore, risk priority through risk priority number(RPN) of FMEA(Failure modes and effects analysis) sheet is conducted for classification into top 10 %. According to thermal characteristics and FMEA, it is necessary to pay attention to not only the in-house defects found in the IGBT, but also the conductive heat caused by the discharge resistance. Since it is possible that animal, dust and others can be accumulated within the PCS, it is possible that the heat resulting from the discharge resistance may cause fire. Accordingly, there are two options that can be used: installing a heat sink while designing the discharge resistance, and designing the discharge resistance in a structure capable of avoiding heat conduction through setting a separation distance between discharge resistance and IGBT. This data can be used as the data for conducting a comparative analysis of abnormal signals in the process of developing a safety device for solar electricity-based photovoltaic power generation systems, as the data for examining the fire accidents caused by each module, and as the field data for setting component management priorities.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.19 no.2
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• pp.175-180
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• 2019

In order to overcome the drawbacks of low rated power of the string inverter, the necessity of micro -inverters and future development directions will be examined by comparing the power conditioner system with existing PCS using micro inverter. Currently, string inverters have been used in household solar power generation systems, and research and penetration of micro-inverters(PV-MIC) have been expanding, which can overcome the shortcomings of string inverters starting from Europe. However, in the PV inverter industry, precise technical standards, test measurement equipment and related test methods for micro-inverters(PV-MIC) are obstacles to product development. Therefore, in this paper, considering the characteristics of micro-inverter (PV-MIC), it aims to make it competitive so that it does not lag behind advanced technology change through test measurement equipment and related technical standard.

• Proceedings of the KIPE Conference
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• 2010.07a
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• pp.399-400
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• 2010

본 논문에서는 고전력 밀도 및 저가형으로 구현이 가능한 새로운 구조의 계통 연계형 태양광 인버터 시스템을 제안한다. 제안된 시스템은 태양전지의 최대 전력점 추종기능과 배터리의 충 방전 기능을 통합하여 기존 3단 구성을 2단으로 줄임으로써 시스템 제작단가가 낮아지고 고전력 밀도 구성이 가능하다. 제안 시스템의 우수성과 신뢰성 검증을 위하여 1.5kW급 PV PCS 시작품을 제작하고 이를 이용한 실험결과를 바탕으로 제안 시스템의 타당성을 검증한다.

• 한국신재생에너지학회:학술대회논문집
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• 2007.06a
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• pp.176-179
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• 2007

본 연구에서는 고분자연료전지(PEMFC)을 이용하여 보조전원용으로 사용할 수 있는 계통연계 연료전지 시스템을 개발하였다. 또한 본 연구에서는 DSP(Digital Signal Processor)칩을 이용한 계통 연계용 전력변환기(PCS, Power Conditioning System)와 제어시스템 개발도 병행하여 수행되었다. 개발된 1kW급 계통연계형 시스템은 다양한 조건에서의 스택 성능 실험 및 BOP 연계 시험을 통해 최적의 운전점을 도출할 수 있었으며, PID(Proportional, Integral, Differential) 운전제어 방법올 적용하여 시스템의 안정적인 운전 특성을 확보하였다. 향후 본 시스템을 계통연계용은 물론 독립전원용으로 사용하기 위해 전력변환장치를 설계중이며, 2007년 하반기에 시스템에 적용될 예정이다.

• Proceedings of the KIEE Conference
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• 2007.07a
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• pp.197-198
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• 2007

본 논문에서는 연료전지 시스템에서 발생되는 저주파 리플의 전달과정을 분석하고, PCS 회로 및 인버터 제어방식에 따른 저주파 리플 영향을 비교 분석한다. 부스트 컨버터와 풀브리지 컨버터의 입력전류 고조파 분포와 인버터 PWM 스위칭 방식에 따른 입력전류에서의 영향을 고조파 분포 및 저주파 리플 측면에서 분석한다. 풀브리지 컨버터에서 전달되는 저주파 리플 크기가 상대적으로 작은 것을 확인하고, PWM 스위칭 방식은 저주파 리플에 영향을 주지 않는다는 것을 시뮬레이션을 통하여 확인한다.

• Proceedings of the KIEE Conference
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• 2007.10c
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• pp.189-191
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• 2007

본 연구에서는 고분자전해질연료전지(PEFC)를 이용하여 보조전 원용으로 사용할 수 있는 계통연계 연료전지 시스템을 개발하였다. 또한 본 연구에서 DSP(Digital Signal Processor)를 이용한 계통연계형 전력변환장치(PCS, Power Conditioning System)와 시스템 제어기의 개발도 병행하여 수행되었다. 개발된 1kW급 보조전원용 연료전지 시스템은 다양한 조건에서의 스택 성능 실험 및 BOP 연계 시험을 통해 최적의 운전점을 도출할 수 있었으며, PID(Proportional, Integral, Differential) 운전제어 방식을 통하여 시스템의 안정적인 운전 특성을 확보하였다. 향후 본 시스템은 계통연계용은 물론 독립전원용으로도 사용이 가능할 수 있도록 전력변환장치를 설계하여 적용할 예정이다.

• The Transactions of the Korean Institute of Power Electronics
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• v.16 no.6
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• pp.587-593
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• 2011

A new high power density and low cost Photovoltaic Power Conditioning System (PV PCS) with energy storage system is proposed. Its high power density and cost effectiveness can be achieved through the unification of the maximum power point tracker and battery charger/discharger. Despite of the reduced power stage, the proposed system can achieve the same performances of maximum power point tracking and battery charging/discharging as the conventional system. Moreover, the high voltage stress across the link-capacitor can be relieved through the series-connected link-capacitor with the battery. Therefore, a large number of series/parallel-connected link-capacitors can be reduced by 4-times. Especially, when the utility power failure happens, both photovoltaic and battery energies can be supplied to the load with only one power stage. Therefore, it features a simpler structure, less mass, lower cost, and fewer devices. Finally, to confirm the operation, validity, and features of the proposed system, theoretical analysis and experimental results from a single phase AC 220Vrms/1.5kW prototype are presented.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.24 no.9
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• pp.62-70
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• 2010

Fuel cell system which can solve the environmental problem is receiving attention. To use utility power necessary power conversion system from low voltage that is generated by fuel cell system. because fuel cell has special characteristic of low voltage high current. To improve PCS's efficiency the paralleling method is used. Available the method could reduce the switching loss. But the existing research could not be found optimal result and accompanying several effects. In this study analysis several effects causing the parallel method. The effects have been demonstrated through simulations and experiments.