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An islanding operation refers to the phenomenon in which a part of a power system composed of one or more power sources and loads is separated from the rest of the system for a certain period. An unintentional islanding operation may cause system instability and lead to human accidents, so it should be detected to prevent problems. Conventional various methods for determining islanding operation detect the islanding through the variation of power quality. However, these methods may not operate correctly in a power system which includes a variety of devices that improve power quality in the future. Therefore, in this study, we propose a method of determining islanding operation based on system configuration. Connection status between Renewable Energy Sources (RESs) and main source can be checked using depth first search among the graph search method. If RESs and main sources are connected, it is not an islanding operation and vice-versa. The simulation results show that the proposed islanding detection method complies with the maximum detection time of IEEE Std. 1547. [ABSTRACT FROM AUTHOR]

In South Korea (RE PUBLIC OF KOREA), there has been a recent increase in the deployment of renewable energy sources. Concerns regarding environmental impacts from traditional fossil-fuel generation resulted in a 227% increase in renewable energy in 2015, compared to 2008. The South Korean Ministry of Trade, Industry, and Energy is considering generating 20% of the nation's electricity using renewable resources by 2030, up from 6.2% in 2017, according to the Renewable Energy 3020 Implementation Plan (signifying that in 2030 there should be 20% of energy from renewables) and the Eighth Basic Plan for Long-Term Electricity Supply and Demand, which were announced in December 2017. To aid in achieving this goal, it is expected that the capacity of renewable energy equipment to be supplied by 2030 will be 48.7 GW. [ABSTRACT FROM AUTHOR]

Owing to the development of highly efficient electric power converters, the number of studies on the construction of low-voltage dc (LVDC) systems is gradually increasing. To use LVDC distribution systems, voltage regulation methods to compensate for the voltage drop and to limit the voltage unbalance are essential. In a bipolar LVDC distribution system, a voltage drop and voltage unbalance could occur because of the load current and the variation in the amount of power supplied to the poles. However, not enough research has been conducted on voltage regulation methods for LVDC distribution systems. To reduce the voltage drop and the voltage unbalance, this paper proposes a voltage regulation method based on the neutral to line drop compensation (NLDC) method, which employs a modified LDC to calculate the sending-end reference voltage. In the NLDC method, the neutral current and neutral line impedance are taken into consideration to compensate for the neutral line potential fluctuation and voltage drop on the pole. The next sending-end voltage is determined by checking the voltage unbalance factor, and it is adjusted to maintain it within the allowable voltage unbalance factor. A voltage regulation algorithm and a bipolar LVDC system model are implemented using the Electromagnetic Transients Program. [ABSTRACT FROM PUBLISHER]