• 한국산업융합학회 논문집
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• 제23권3호
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• pp.491-498
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• 2020

Recently, In the production line of batteries, charge and discharge tests are essential to verify battery characteristics. In this case, the battery charging uses a unidirectional AC/DC converter capable of output voltage and current control, and the discharge uses a resistive load. Since this method consumes energy during discharge, it must be replaced with a bi-directional AC/DC converter system capable of charging and discharging. Although it is difficult to replace the connected inverter part of the bi-directional AC/DC converter system due to the high cost, the spread of the solar-connected inverter rapidly increases as the current solar supply business is activated, and thereby the solar-connected type Inverter prices are plunging. If it can be used as a power converter for battery discharge without program modification of the solar-powered inverter, it will have competition. In this paper, propose a new battery discharge system using a combination of a photovoltaic DC/DC simulator and photovoltaic PCS using a battery to be used as a power converter for battery discharge without program modification of a low-cost photovoltaic inverter. In addition, propose an optimal solar characteristic curve for the stable operation of PCS. The validity of the proposed system was verified using a 500[W] class solar DC/DC simulator and a solar PCS prototype.

• Journal of Electrical Engineering and Technology
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• 제13권3호
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• pp.1123-1130
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• 2018

Voltage stabilization is an essential component of power quality in low voltage DC (LVDC) microgrid. The microgrid demands the interconnection of a number of small distributed power resources, including variable renewable generators. Therefore, the voltage can be maintained in a stable manner through the control of these distributed generators. In this study, we did research on the new advanced operating method for a photovoltaic (PV) simulator in order to achieve interconnection to a bipolar LVDC microgrid. The validity of this voltage stabilization method, using the distributed generators, is experimentally verified. The test LVDC microgrid is configured by connecting the developed PV simulator and DC load, DC line, and AC/DC rectifier for connecting the main AC grid. The new advanced control method is applied to the developed PV simulator for the bipolar LVDC grid in order to stabilize the gird voltage. Using simulation results, the stabilization of the grid voltage by PV simulator using the proposed control method is confirmed the through the simulation results in various operation scenarios.

• 전기학회논문지
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• 제65권11호
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• pp.1800-1805
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• 2016

The micro-grid designed as bipolar ${\pm}750V$ low-voltage DC power distribution system demonstrated by KEPRI, demands interconnection of a number of small decentralized power source including variable renewable generator. Therefore, variable researches for the influence of interconnection with the bipolar typed DC grid and these variable power sources are required for superior quality of power distribution. Renewable power generation simulators for the bipolar ${\pm}750V$ low-voltage DC power distribution system are necessary for such researches. In this paper, we carry out a research on the photovoltaic simulator that be actually able to interconnect with a bipolar ${\pm}750V$ low-voltage micro-grid. Simulator for this research is not only able to simulate photovoltaic generation according to weather informations and PV modules characteristics, but also contribute to stabilization of bipolar ${\pm}750V$ low-voltage of the system. Therefore, the simulator was designed to develop a system that can situationally respond to variable control algorithms such as the MPPT control, droop control, EMS power control, etc.

• Journal of Power Electronics
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• 제13권2호
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• pp.313-321
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• 2013

This paper describes the operation analysis results of a communication-based DC micro-grid using a hardware simulator developed in the lab. The developed hardware simulator is composed of distributed generation devices such as wind power, photovoltaic power and fuel cells, and energy storage devices such as super-capacitors and batteries. Whole system monitoring and control was implemented using a personal computer. The power management scheme was implemented in a main controller based on a TMS320F28335 chip. The main controller is connected with the local controller in each of the distributed generator and energy storage devices through the communication link based on a CAN or an IEC61850. The operation analysis results using the developed hardware simulator confirm the ability of the DC micro-grid to supply the electric power to end users.

• 한국산학기술학회논문지
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• 제18권9호
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• pp.444-453
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• 2017

기존 RTDS를 이용한 PV PHIL(Power-Hardware-In-Loop) Simulator는 확장성과 유연성의 문제로 인하여 일반 DC Amplifier를 이용한 많은 연구가 진행되었으나, PV Inverter와 연계할 경우에 과도 상태의 출력이 발생하여 안정성과 PV Inverter의 성능 개선이 불가능하였다. 따라서, 이러한 문제점을 해결하기 위하여 본 논문에서는 PV PHILS의 출력 성능 향상과 안정적인 운영이 이루어질 수 있는 제어 알고리즘을 제안한다. 즉, 이 제어 알고리즘은 DC Amplifier의 전기적 출력 특성을 극복하기 위해 정전압(CV), 정전류(CC) 상태에 따라 전압, 전류의 목표 값을 제어하고 각 장치별 특성 고려한 Multi-rate 기반의 특성을 갖는다. 먼저, PV Array의 수학적인 모델링과 DC Amplifier 그리고 DC 전력측정용 Isolated 장치와 통합하여 실시간 처리 기반의 장치로 구성하였고, 제안한 알고리즘이 적용된 PV PHILS와 실제 계통에 연계된 PV Inverter를 이용한 성능시험을 통해서, 그 결과가 기존 방법에 대비해 우수성 및 유용성을 입증하였다.

• 한국신재생에너지학회:학술대회논문집
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• 한국신재생에너지학회 2009년도 춘계학술대회 논문집
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• pp.103-106
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• 2009

In this paper, the implemented photovoltaic array simulator is the power supply based on a common photovoltaic characteristic. This simulator is consisted of a common DC power supply and PC for controlling output. User can select the number of PV modules and solar radiation energy and then can get output whatever user wants. This simulator is a very helpful system to PV generating test and unexpensive than the existing PV simulators.

• 반도체디스플레이기술학회지
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• 제17권1호
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• pp.40-44
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• 2018

In this paper, the efficiency of the solar system is lowered due to the partial shading such as the environmental factors of the solar panel. In order to solve this problem, a DC OPTIMIZER is proposed for a maximum power generation system of a photovoltaic panel. The proposed DC OPTIMIZER is composed of a buck structure that performs the maximum power point tracking (MPPT) control of each module of the solar panel, thus maximizing the efficiency. In order to verify the proposed DC Optimizer, the efficiency was measured by varying the irradiance using a solar simulator instead of the solar panel. As a result, it showed high efficiency characteristics as the maximum energy conversion efficiency was 99.3% at $800w/m^2$, $900w/m^2$, and the average efficiency was 99.06% excluding $100w/m^2$. The maximum efficiency of MPPT was 99.97% at $200w/m^2$, efficiency showed excellent performance.

• Journal of Power Electronics
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• 제3권1호
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• pp.62-67
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• 2003

Recently, photovoltaic system has been studied widely as a renewable energy system, because it does not produce environmental pollution and it has infinity energy source from the sun. A study on photovoltaic system has a lot of problems like as reappearance and repetition of some situation in the laboratory experiment for development of MPPT algorithm and islanding detection algorithm. because output characteristics of solar cell are varied by irradiation and surface temperature of solar cell. Therefore, the assistant equipment which emulates the solar cell characteristics which can be controlled arbitrarily by researcher is require to the researchers for reliable experimental data. In this paper, the virtual implement of solar cell (VISC) system is proposed to solve these problems and to achieve reliable experimental result on photovoltaic system. VISC system emulates the solar cell output characteristics, and this system can substitute solar cell in laboratory experiment system. To realize the VISC, mathematical model of solar cell is studied for driving converter and the DC/DC converters are compared in viewpoint of tracking error using computer simulation. Output dynamic characteristic of PV array is varied by irradiation and PWM converter performance is studied using PSIM simulator.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2008년도 심포지엄 논문집 정보 및 제어부문
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• pp.234-235
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• 2008

본 논문은 계통연계형 태양광발전 시스템의 Power Conditioning System의 성능 테스트를 위한 태양광 시뮬레이터의 제어기 최적 설계에 관한 내용이다. 태양광 시뮬레이터 기술의 핵심은 정확한 에너지원의 모델링과 빠르고 안정적인 전력증폭기 제어기술에 있다. 종래의 제어기인 비례 적분제어기를 사용하는 과정에서 비례 적분 제어기 특유의 응답지연 특성으로 시뮬레이터의 동적 특성을 완벽하게 구현할 수 없기에, 응답속도가 빠르고 안정적인 제어기법인 $H_{\infty}$제어 이론을 적용하였다. 태양광 시뮬레이터의 제어기 성능평가를 위해서 태양광 시뮬레이터의 출력을 결정 하는 DC Power Amplifier의 성능실험을 하였다. DC Power Amplifier를 정전압에서 부하의 투입/제거시 비례-적분 제어기와 $H_{\infty}$제어기의 응답속도와 변동전압의 크기를 비교하여 제어기의 성능을 비교하였다.

• 전력전자학회:학술대회논문집
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• 전력전자학회 2018년도 전력전자학술대회
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• pp.126-128
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• 2018

Solar array simulator (SAS) is a special DC power supply that regulates the output voltage or current to emulate characteristics of photovoltaic (PV) panels. Especially, the control of SAS is a challenging task due to the nonlinearity in the output curve, which is dependent on irradiance as well as temperature and is determined by panel materials. Conventionally, both current-mode control and voltage-mode control should be alternated by partitioning the operating curve into multiple sections, which is not only for the measurement noise problem with the feedback sensing but also for the control stability issue near the maximum power point. However, the occurrence of transition among different controllers may deteriorate the overall performance. To eliminate the mode transitions, a novel single controller scheme has been introduced in this paper, where the reference operating projection technique enables simple, smooth and numerically stable control. Theoretical consideration on the loop stability issue is discussed and the performance is verified experimentally for the emulation of a PV panel data in view of stability and response speed.