• 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 Electrical Engineering and Technology
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• v.2 no.1
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• pp.19-28
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• 2007

The paper discussed various techniques for islanding detection and described in detail the working principles of ROCOF and vector shift relays. A simulator was used to investigate why the stability of both types of relays maybe affected by network and load switching, short-circuit faults and in the case of a ROCOF relay the loss of bulk generation or the tripping of a transmission feeder. Finally, to enhance the reliability of Loss of Mains protection, a new islanding detection technique based on a GPS synchronized phasor measurement system was proposed.

• Proceedings of the KIEE Conference
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• summer
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• pp.217-219
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• 2004

The installation of small sized dispersed generation(DG) units operating in parallel with the utility supply presents several technical problems for the protection and control of the system. One of the critical concerns is the occurrence of islanding. Hence, this paper propose the Digital Universal Relay(DUR) including anti-islanding function as DG interconnection interface. The existent islanding detection algorithms are examined. And the most effective and reliable method of those is modified for DUR application. The modified algorithm is evaluated through the modeling of the test system by PSCAD/EMTDC.

• The Transactions of the Korean Institute of Power Electronics
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• v.9 no.6
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• pp.568-576
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• 2004

This paper presents a new anti-islanding method for distributed power generation system (DPGS) using renewable energy. Based on the concept of real and reactive power mismatch, three different islanding conditions are analyzed. It is shown via analysis that islanding voltage is a function of real power alone, where as its frequency is a function of both real and reactive power. Using this analysis, a new anti-islanding method is developed. The proposed protection algorithm continuously perturbs ($\pm$5%) the reactive power supplied by DPGS while simultaneously monitoring the utility voltage and frequency. If a measurable frequency deviation took place by islanding, the real power of DPGS is further reduced to 80%. This detection method is shown to be fast acting under resonant loads. Possible islanding conditions are simulated and verified with analysis. Experimental results on a 0.5kW utility-interactive fuel cell system are suggested.

• Proceedings of the KIEE Conference
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• 2011.07a
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• pp.145-146
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• 2011

A micro-grid (MG) is usually interconnected to the main grid through the dedicated line. Immediately after the removal of the grid supply, the MG should be disconnected and remain disconnected until the main grid is re-energized. It should detect islanding condition as soon as it happens to adjust the setting of the protection relays in the MG. This paper proposes an islanding detection algorithm for the MG based on the active and reactive power delivered to the dedicated line in the time domain. The performance of the proposed algorithm is verified under islanding conditions and fault conditions using the PSCAD/EMTDC simulator. The results indicate that the proposed algorithm can discriminate the islanding conditions from the various fault conditions.

• Proceedings of the KIEE Conference
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• 2008.07a
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• pp.1085-1086
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• 2008

Shunt active filter can compensate harmonic current of utility results from non-linear loads such as rectifiers, cycloconverters and arc furnaces. It has the same structure as photovoltaic(PV) generation system. So, It was proposed the system that generates PV power and also has active filter function. It is called PV-AF(Photovoltaic and Active Filter) power generation system. Islanding can be occurred in an inverter based dispersed generation system, when the system disconnected from utility and loads are entirely supplied by PV system only. Islanding may result in interference to grid protection devices, equipment damage, and even personnel safety hazards. Therefore, islanding has to be detected and protected. The conventional anti-islanding methods have NDZ(None-Detection Zone) or power quality degradation. But PV-AF power generation system has the function of not only shunt active filter but also anti-islanding method without NDZ. In this paper, a novel anti-islanding method for PV-AF system is proposed and analysed in detail.

• Proceedings of the KIEE Conference
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• summer
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• pp.1477-1479
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• 2004

Increasing numbers of photovoltaic arrays are being connected to the power utility through the power conditioning systems (PCS). This has raised potential problems of network protection. If, due to the action of the PCS, the local network voltage and frequency remain within regulatory limits when the utility is disconnected, then islanding is said to occur. In this paper, the representative methods to prevent the islanding are described and a PSIM-based model and analysis of the reactive power variation (RPV) method are presented. A novel phase detector using the all-pass filter and digital phase locked loop (DPLL) is proposed especially for the single-phase PCS. Finally, this paper provides the simulation and experimental results with a single-phase 3kW prototype PCS. Islanding test method of IEEE Std. 929-2000 was performed for verification.

• Proceedings of the KIEE Conference
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• 2001.05a
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• pp.42-45
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• 2001

The islanding protection for distributed resources (DR) becomes an important and emerging issue in power system protection since the distributed generator installations are rapidly increasing and most of the installed systems are interconnected with distribution network. In order to avoid the negative impacts on distributed network resulting from islanding operations of DR, it is necessary to detect the loss of mains (LOM) effectively. This paper presents a new LOM detection method using the rate of change in total harmonic distortion (THD) of current. The proposed method effectively detects LOM of the DR unit operating in parallel with the distribution network. We also verified the efficiency of the proposed method using the radial distribution network of IEEE 34 bus model.

• Journal of the Korean Solar Energy Society
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• v.39 no.1
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• pp.59-66
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• 2019

BIPV or BAPV installation applied to building is increasing through public utility mandates enterprise. Solar PV energy generates only during the day, but if it is operated in convergence with ESS, which stores electrical energy, it can restrain the fossil energy used in buildings throughout the day. A solution is to converge with PV system and ESS. However, PV systems and ESS connected to the power grid in parallel can cause problems of electrical stability. A study was conducted on the case of failure to detect islanding operation under the parallel operation of PV generation and ESS that are connected in parallel to power grid. Experiments conducted various non-islanding detections under the operating conditions. In the experiment results, when one PCS - PV inverter or ESS inverter - was operating under the islanding condition, it stopped working within 0.5 seconds of the Korean grid standard. However, when both of PV inverter and ESS inverter were operating at the same time under the islanding situation, the anti-islanding algorithm did not operate normally and both inverters continuously supplied power to the connected RLC loads. islanding detection Algorithm developed by each inverter manufacturer has caused this phenomenon. Therefore, this paper presented a new test standard for islanding detection.

• International Journal of Internet, Broadcasting and Communication
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• v.7 no.2
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• pp.90-95
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• 2015

This paper describes IEC 61727 standard of Photovoltaic (PV) systems -Characteristics of the utility interface. IEC 61727 standard tests include utility compatibility and personnel safety and equipment protection of PV inverter performance functions. Especially utility compatibility part includes test items of 1) voltage, current and frequency, 2) normal voltage operating range, 3) flicker, 4) DC injection, 5) normal frequency operating range, 6) harmonics and 7) waveform distortion, 8) power factor of PV inverter. Also personnel safety and equipment protection part includes test items 1)loss of utility voltage, 2)over/under voltage and frequency, 3)Islanding protection, 4)response to utility recovery, 5)earthing, 6)short circuit protection, 7)Isolation and switching of PV inverter. In this paper, each item of IEC 61727 standard test is studied and analyzed and finally full tested by PV inverter performance function.