• Proceedings of the KIPE Conference
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• 2020.08a
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• pp.7-9
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• 2020

국내 가정용 단상 태양광인버터의 주류는 3kW급으로 그린홈보급사업, 태양광 대여사업 및 여러지원사업, 자가설치 사업 등에 사용되고 있고, 100kW 태양광발전소에 설치되는 경우도 있다. 당사에서 전력변환 효율, 전력밀도 및 신뢰성 향상을 위해 개발하였으며, 추가적으로 요구되는 직류 지락 검출 및 Residual Current 검출 기능 구현을 목표로 개발한 3kW급 계통연계형 태양광 인버터의 특징 및 태양광인버터 개발에 있어 필요한 고려요소를 소개한다.

• Journal of IKEEE
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• v.23 no.4
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• pp.1280-1287
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• 2019

Grid-connected bidirectional PCS(Power Conditioning System) technology is a technology for implementing distributed renewable energy smart grid. And it is always charged by using power collected from solar modules and commercial grid power among vast smart grid systems, and stored when needed.It is a hybrid energy storage device that allows power to be released into the low voltage system. To this end, a PV input power converter with MPPT function, a bidirectional power converter for battery charging and discharging, and a DC Link input are output to a 3 phase 380V AC system, and if nessary, the bidirectional DC/DC converter We designed and developed a PCS with three power converter structures composed of inverters that perform battery charging. Currently, this system is applied to the site of Jeju, which is vulnerable to power outages and fire accidents.

• The Transactions of the Korean Institute of Electrical Engineers P
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• v.63 no.4
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• pp.361-367
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• 2014

This paper is related to a new solar power conditioner for a built-in step-up chopper function. In the first step-up chopper proposed solar PV power conditioner for mutually connected in series with the input voltage of the bypass diodes are respectively connected to the positive terminal should install the mutual boosting chopper diode connected in series with the boost chopper switching element between the two power supply and at the same time the first and the second was connected to a second diode and a resonance inductor and a snubber capacitor in series with each other. And the common connection point between the bypass diode and the step-up chopper and the step-up chopper diode common connection point of the switching elements of the input voltage was set to the boost inductor for storing energy. In addition, between the step-up chopper and the step-up chopper diode and a switching element of a joint connection point of the first auxiliary diode and the second common connection point of the auxiliary diode was provided, the resonance capacitor. Between the step-up chopper and the step-up chopper diode and a switching element of a joint connection point and the common connection point of the resonance inductor snubber capacitor and connecting the third secondary diode, between two power supply lines is characterized by configuring the DC link capacitor bus lines in parallel. Therefore, it is possible to suppress the switching loss through, DC link bus lines, as well as there could seek miniaturization and weight reduction of the power conditioner itself by using a common capacitor of the non-polar non-polar electrolytic capacitor having a capacitor, the service life of the circuit can be extended and it is possible to greatly reduce the loss can be greatly improve the reliability of the product and the operation of the product itself.

• The Transactions of the Korean Institute of Power Electronics
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• v.18 no.4
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• pp.312-321
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• 2013

In this paper, high efficiency control method for flyback inverter with synchronous rectifier(SR) based on photovoltaic AC modules is proposed. In this control method, the operation of SR is classified according to the voltage spike across main switch SP. When the voltage spike across SP is lower than the rating voltage of SP, the operation of active clamp circuit is interrupted for reducing the switching loss of auxiliary switch. In this time, the SR is operated for soft-switching of SP. When the voltage spike across Sp is higher than the rating voltage of SP, the operation of active circuit is activated for reducing the voltage spike. The SR is operated for reducing the conduction loss of secondary output diode. Thus, a switching loss of the main switch can be reduced in low power region, and weighted-efficiency can be improved. A theoretical analysis and the design principle of the proposed method are provided. And validity is confirmed through simulation and experimental results.

• The Transactions of the Korean Institute of Power Electronics
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• v.16 no.4
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• pp.309-316
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• 2011

A PLL system has widely used for synchronizing the grid voltage at the grid-connected inverter for supplying power from the PV generation systems. In this paper, a PLL algorithm without both the loop filter and PI controller is suggested for improving the performance of synchronization at the single-phase and three-phase grid connected inverters. In order that the output voltage of a phase detector in the PLL has only a dc voltage, and it approaches to 0 when the synchronization signal is locked to the grid voltage, the feedback signals are determined by using two-phase voltages. After the PLL system with a proportional controller is modelled with the small signal analysis, the stability and steady-state error are investigated. Through the simulation studies and experimental results, the performances of the proposed PLL algorithm are verified.

• Proceedings of the KIPE Conference
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• 2016.07a
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• pp.473-474
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• 2016

최근 신재생에너지의 보급 정책으로 인해 태양광 또는 풍력과 같은 신재생에너지가 전체 전력 계통에서 차지하는 비율이 증가되고 있는 실정이다. 그러나 신재생에너지는 변동 적이기 때문에 계통의 안정성을 저해하는 원인이 될 수 있다. 이에 따라 각 나라에서는 계통 안정성을 위한 기능들을 요구하고 있으며, 그 요구는 점차 강화되고 있다. 이와 같이 신재생에너지 비율의 증가로 인해 계통 안정성에 대한 문제가 강조되고 있지만, 태양광 분산 발전 시스템의 경우에는 일사량에 의존하여 운전하기 때문에 일사량이 낮거나 야간에는 계통 안정성을 위한 기능을 수행하지 못하는 단점이 있다. 본 논문에서는 일사량이 낮거나 야간에도 계통 안정화를 위해 무효전력 지원이 가능한 확장된 무효전력 운전(EF-RPO: Extended feed-in Reactive Power Operation)방법의 제어 전략을 제안하며, 제안한 방식은 1MVA 계통 연계형 인버터의 제작과 실험을 통해 검증하였다.

• Proceedings of the KIEE Conference
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• 1996.07a
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• pp.525-527
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• 1996

Hysteresis current control is one of the simplest techniques used to control currents for high speed drive systems, because of its simplicity of implementation, fast current control response, and inherent peak current limiting capability. However the conventional fixed-band hysteresis control has a variable switching frequency throughout the fundamental period, and consequently the load current harmonics spreaded on the wide frequency range. In this paper, a simple, novel alterative approach is proposed for a variable-hysteresis band current controller which uses feedback techniques to achieve constant switching frequency with good dynamic response. The method is easily implemented in hardware, the resultant controller is easily tuned to a particular load, and has good immunity to variation in PV parameter and dc supply voltage.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.17 no.6
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• pp.23-30
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• 2003

This paper analyzes the characteristic of utility connection type solar power generation system which it is available to connect the utility. And the operation characteristic of this system is compared and analyzed when it is operated in the real system. The constructional and operational problem were obtained by that result. Overcoming that defect is that finding the proper place to be well operated and to find the best place for getting the sunshine data. This method could increase the efficiency of the generation system. And more, current OS in operating system and monitoring management couldn't solve the problem so that improving OS and constructing data backup system should be implemented, This paper proposes the plan to solve that defect in the real system.

• Journal of Electrical Engineering and Technology
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• v.11 no.1
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• pp.117-124
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• 2016

Solar photovoltaic pumping system is one of most important of renewable energy applications especially in rural areas. Besides, the control strategy for standalone solar pumping system based on induction motor and without DC/DC converter has been widely studied and discussed in the literature. This topology is of great concern due its economic issues, especially when a standard frequency converter (SFCs) with scalar control is used instead of a dedicated PV inverter. This paper proposes an external control module to generate SFCs frequency reference in order to ensure both maximum power point tracking (MPPT). We present method of modeling and control of photovoltaic pumping system based centrifugal pump controlled by new improved incremental conductance in order to optimize the price and operation of pumping system this MPPT algorithm have many advantages like can be eliminate proportional integral controller It is a low cost solution since it requires no additional power equipment. The induction motor driven pump that is powered by a solar array is controlled by the indirect field oriented control (IFOC). The effectiveness of the proposed approach is illustrated by simulations carried out under Matlab Software. The experimental results are compared with simulation results.

• 한국태양에너지학회:학술대회논문집
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• 2012.03a
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• pp.153-159
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• 2012

In photovoltaic system, the characteristic of photovoltaic module such as open circuit voltage and short circuit current will be changed because of cell temperature and solar radiation. Therefore, a boost converter of the PV system connects between the output of photovoltaic system and DC link capacitor of grid connected inverter as controlling duty ratio for maximum power point tracking(MPPT). This paper shows the dynamic characteristic of the boost converter by comparing single-loop control algorithm and two-loop control algorithm using both analog and digital control. The proposed both compensation method has been verified with computer simulation and simulation results obtained demonstrate the validity of the proposed control schemes.