• 한국태양에너지학회:학술대회논문집
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• 2009.11a
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• pp.297-302
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• 2009

As the grid-connected photovoltaic power conditioning systems (PVPCS) are installed in many residential areas, these have raised potential problems of network protection on electrical power system. One of the numerous problems is an Islanding phenomenon. In this paper, active frequency drift (AFD) method, one of the anti-islanding analyzed by current magnitude compensation and calculation of RMS value of the output power.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.25 no.10
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• pp.76-86
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• 2011

This paper proposes novel algorithm for anti-islanding of grid-connected photovoltaic(PV) inverter. The islanding of PV systems can cause a variety of problems such as deterioration in power quality and electric shock. To prevent islanding, many anti-islanding methods are researched. Typical methods of anti-islanding are active frequency drift(AFD) and active frequency drift positive feedback(AFDPF). However, the AFD has problem that widely exists non diction zone(NDZ). The AFDPF is a method that improves the AFD method and is detected islanding by changing the chopping fraction(cf). However, The AFDPF does not detect when cf is very small and does not satisfy the IEEE Std. 929-2000 when cf is very big. Therefore, this paper proposes novel anti-islanding method that is simple to implement using virtual resister. The anti-islanding method proposed in this paper is compared with conventional method. The validity of this paper is proved using this result.

• The Transactions of the Korean Institute of Power Electronics
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• v.16 no.2
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• pp.145-151
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• 2011

In this paper, among the active islanding detection techniques, the modified active frequency drift method was analyzed, which is relatively easy to apply to the single-phase grid-connected PV PCS. The existing designs for turbulences in these applications were empirically conducted, and do not have sufficient reliability and performance. Therefore, three application forms of the modified active frequency drift technique were modeled, based on which the proper magnitude of turbulence, which is the frequency acceleration component, was calculated. Using the results, the magnitude of and injection method for turbulence for ensuring the islanding detection performance and improving the output power quality were proposed, and they were verified via simulations and experiment to prove that the reliable islanding detection technique can be developed merely by measuring the basic output power quality, without the need for expensive islanding simulation equipment.

• The Transactions of the Korean Institute of Power Electronics
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• v.14 no.2
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• pp.160-167
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• 2009

To detect islanding mode when the grid is being tripped is a major safety issue in the Utility Interactive Photo Voltaic (UIPV) system. In this paper, analytical design method is suggested for AFD & RPV method under IEEE 929-2000 recommended islanding test condition. We have discussed that there is a same point. we injected reactive component of the current by AFD & RPV methods, but the current reference generated is other waveform. Possible if amount of reactive components in this methods are same each method, there is happened same rates frequency variation. To verify the validity of the analytical comparison, this paper presents simulation and experimental results from single phase, 3[kW] inverter for the transformerless UIPV system.

• Proceedings of the KIPE Conference
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• 2015.07a
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• pp.524-525
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• 2015

본 논문은 계통연계형 소용량 태양광 인버터에 적용된 AFD(Active Frequency Drift) 기반의 단독 운전 검출 기법을 제안한다. 태양광 시스템에 일반적인 인버터 토폴로지를 사용한 경우, 무효전력 주입을 이용하여 단독운전 검출이 가능하다. 하지만 무효전력의 제어가 불가능한 인버터를 사용한 경우에는 기존의 무효전력을 이용하는 단독운전 검출기법을 사용할 수 없다. 무효전력의 제어가 불가능한 인버터 토폴로지에 새로운 스위칭 기법을 적용하면 무효전력을 주입한 효과를 얻을 수 있고, 이를 통해 기존의 AFD 방식을 응용하여 단독운전 검출이 가능한 새로운 검출기법을 제안하였다. 제안하는 검출기법은 기존의 AFD 방식보다 인버터 출력전류의 THD (Total Harmonic Distortion)를 개선할 수 있는 장점이 있다. 제안하는 기법의 성능을 시뮬레이션을 통해 확인하였다.

• Proceedings of the KIPE Conference
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• 2012.11a
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• pp.9-10
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• 2012

AFD(Active Frequency Drift), SMS(Slip-Mode frequency Shift)를 비롯한 주파수 이동 단독 운전 검출 방법은 단독 운전 발생 후, 계통의 주파수를 정상 운전 범위 밖으로 이동시켜 OUF(Over/Under Frequency) 릴레이를 동작하게 만들어 단독 운전을 검출한다. 이 방법들의 불검출 영역은 알고리즘에 의한 전류 위상각 변화율과 부하 역률 각 변화율 사이의 관계, 그리고 단독 운전 후 정상 상태(steady state) 운전 주파수에 의해 결정된다. 본 논문에서는 불검출 영역에 영향을 미치는 부하 역률 각 변화율을 분석하고 그를 바탕으로, 설계한 Q(Quality)-factor보다 낮은 Q-factor를 갖는 부하 조건에서는 항상 단독 운전을 검출할 수 있는 설계 방법을 제시한다. 제안된 방법의 유효성은 모의실험 및 실험으로 검증되었다.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.17 no.1
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• pp.127-136
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• 2013

The islanding detection and prevention function in the important performance of the grid-connected inverter is the essential details which should be considered for worker's safety to maintain the system. This paper tries to suggest the active frequency shake islanding detection technique in the grid-connected PV generation system using sunlight. The existing active frequency drift method algorithm is described to suggest active frequency shake method algorithm. And, the algorithm which can reduce the non-detection zone, improve THD, and improve the detection speed in comparison with the existing algorithm is suggested. And we applied the proposed algorithm to the 3kW grid-connected photovoltaic inverter generation and verified the feasibility of the technique through the simulation and experiments.

• Proceedings of the KIPE Conference
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• 2010.07a
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• pp.172-173
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• 2010

본 논문은 신 재생에너지원 중 태양광을 이용한 계통연계형 PV PCS의 단독운전 검출 성능을 극대화하고, 출력전력의 품질 외곡을 최소화 할 수 있는 개선된 능동 주파수 변이기법의 최적 외란의 크기를 모델링, 시뮬레이션 및 실험을 통하여 검증하고, 이를 근거로 계통 보호 협조 및 안전을 위한 단독운전 검출 기법의 설계방법을 제시하고자 한다.