• The Transactions of the Korean Institute of Electrical Engineers A
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• v.53 no.9
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• pp.481-486
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• 2004

In operation of distribution system, $DG_s$ Distributed Generations) are installed as an alternative of extension and establishment of substations and transmission and distribution lines according to increasing power demand. In operation planning of $DG_s$, determining optimal capacity and allocation gets economical pro(it and improves power reliability. This paper proposes determining a optimal number, size and allocation of $DG_s$ needed to minimize operation cost of distribution system. Capacity of $DG_s$ (or economical operation of distribution system estimated by the load growth and line capacity during operation planning duration, DG allocations are determined to minimize total cost with power buying cost. operation cost of DG, loss cost and outage cost using GA(Genetic Algorithm).

• The Transactions of The Korean Institute of Electrical Engineers
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• v.66 no.9
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• pp.1317-1324
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• 2017

These days, a penetration of distributed generation(DG) has increased in power system. Due to increased penetration of DG, a whole system is forced to install the maximum hosting capacity of DG. Therefore analysis between the maximum hosting capacity of DG at the target bus and the whole system is important. If we know the maximum hosting capacity, it will be able to satisfy the demand of system planner and customer. In this paper, we use a genetic algorithm to calculate the hosting capacity with optimization program using Design Analysis Kit for Optimization and Terascale Applications(DAKOTA). To consider a real system, we establish constraints and use IEEE 34 node test system. In addition, through the correlation coefficient between the target bus and the other buses, when capacity of DG at the target bus increases, we analyze which capacity of DG at the other buses will be decreased.

• Proceedings of the KIEE Conference
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• 2008.07a
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• pp.27-28
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• 2008

For stable and sustainable energy supply, distributed generator (DG) has become an essential and indispensable element from environmental and energy security perspectives. However, installation of DG in distribution systems may cause negative affects on feeders because power outputs of DG could be changed irregularly. One of major negative affects is variation in voltage profile. In general, voltage regulation devices such as under load tap changer (ULTC) at distribution substation and step voltage regulator (SVR) along feeder in distribution system are used to maintain customers' receiving voltage within a predetermined range. These regulators are controlled by line drop compensation (LDC) method which calls for two parameters; the equivalent impedance and the load center voltage. Therefore, consideration of DG outputs in the LDC parameter design procedure may give large impact on the installable DG capacity. This paper proposes a method that estimates maximum Installable DG capacity considering LDC parameters of ULTC and SVR. The proposed algorithm is tested with model network.

• Proceedings of the KIEE Conference
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• 2002.11b
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• pp.277-279
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• 2002

Recently, power requirement has been increasing. But the large generation unit is hardly installed because of economic and environment problem. Therefore, the concern for DG(distributed generation) is growing. Present, allowable interconnection capacity of DG for composite distributed generation is studied. In this paper, it is studied that the new interconnection capacity of DG for composite distribution system interconnected DG. We study new allowable interconnection capacity by power factor and placement. We study SERV(sending end reference voltage) variation and allowable interconnection capacity interconnected new DG.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.58 no.7
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• pp.1263-1269
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• 2009

Stable and sustainable power supply means maintaining a certain level of power quality and service while securing energy resource and resolving environmental issues. Distributed generation (DG) has become an essential and indispensable element from environmental and energy security perspectives. It is known that voltage violation is the most important constraint for load variation and the maximum allowable DG. In distribution system, sending voltage from distribution substation is regulated by ULTC (Under Load Tap Changer) designed to maintain a predetermined voltage level. ULTC is controlled by LDC (Line Drop Compensation) method compensating line voltage drop for a varying load, and the sending voltage of ULTC calls for LDC parameters. The consequence is that the feasible LDC parameters considering variation of load and DG output are necessary. In this paper, we design each LDC parameters determining the sending voltage that can satisfy voltage level, decrease ULTC tap movement numbers, or increase DG introduction. Moreover, the maximum installable DG capacity based on each LDC parameters is estimated.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.19 no.10
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• pp.655-660
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• 2018

Internal combustion generation (ICG) is used to supply power to islands due to geographical characteristics, but there are some problems, such as considerable operating cost, salt pollution, and environmental pollution. For these islands, KEPCO pays a significant amount of operating deficit each year, especially for the fuel and servicing costs, which account for a large portion of this deficit. Integrated ICG (IICG) through an offshore cable between near islands is being considered to decrease servicing costs. Distributed generation (DG) is also being introduced on the islands because of the demand for a low-carbon society. In hybrid internal combustion generation (HICG), DG is introduced into IICG, which can be applied because the DG output is insufficient due to environmental characteristics, and the IICG is used as an auxiliary power source. Therefore, this paper proposes an algorithm to estimate the optimal DG capacity that can be introduced in accordance with the KEPCO operating deficit in the HICG. According to simulations, the optimal DG capacity depends on the fuel cost and load capacity. The validity of the proposed algorithm was confirmed for multiple islands with different peak loads.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.58 no.11
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• pp.2149-2154
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• 2009

Electric power quality in power transmission/distribution systems has considerably been deteriorated with the increase in the capacity of distributed generators (DGs). It is because inverters, connecting DGs to conventional power grids, tend to generate harmonic current and voltage. For harmonic mitigation, a large amount of research has been done on passive and active filters, which have been operating successfully in many countries. This paper, therefore, presents how to adopt the filters to an inverter-based DG, with considering a system consisting of both inverter-based DG and harmonic filters. In particular, this paper describes the simulation results using the PSCAD/EMTDC: firstly, the relationship between total harmonic distortion(THD) of current and output power of DG: secondly, the harmonic mitigation ability of passive and active filters. The system, furthermore, is obliged to satisfy the regulations made by Korean Electric Power Corporation(KEPCO). In the regulations, power factor should be maintained between 0.9 and 1 in a grid-connected mode. Thus, this paper suggests two methods for the system to control its power factor. First, the inverter of DG should control power factor rather than an active filter because it brings dramatic decrease in the capacity of the active filter. Second, DG should absorb reactive power only in the range of low output power in order to prevent useless capacity increase of the inverter. This method is expected to result in the variable power factor of the system according to its output power.

• Journal of Electrical Engineering and Technology
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• v.12 no.1
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• pp.161-172
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• 2017

In the paper, a hybrid technique is proposed for detecting the location and capacity of distributed generation (DG) sources like wind and photovoltaic (PV) in power system. The novelty of the proposed method is the combined performance of both the Biography Based Optimization (BBO) and Particle Swarm Optimization (PSO) techniques. The mentioned techniques are the optimization techniques, which are used for optimizing the optimum location and capacity of the DG sources for radial distribution network. Initially, the Artificial Neural Network (ANN) is applied to obtain the available capacity of DG sources like wind and PV for 24 hours. The BBO algorithm requires radial distribution network voltage, real and power loss for determining the optimum location and capacity of the DG. Here, the BBO input parameters are classified into sub parameters and allowed as the PSO algorithm optimization process. The PSO synthesis the problem and develops the sub solution with the help of sub parameters. The BBO migration and mutation process is applied for the sub solution of PSO for identifying the optimum location and capacity of DG. For the analysis of the proposed method, the test case is considered. The IEEE standard bench mark 33 bus system is utilized for analyzing the effectiveness of the proposed method. Then the proposed technique is implemented in the MATLAB/simulink platform and the effectiveness is analyzed by comparing it with the BBO and PSO techniques. The comparison results demonstrate the superiority of the proposed approach and confirm its potential to solve the problem.

• Proceedings of the KIEE Conference
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• 2002.11b
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• pp.137-140
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• 2002

This paper describes the effect of distributed generations (DG) on the bus protection scheme. When the generating capacity of DG is larger than 3 MVA totally, DG are generally connected to the 22.9 kV bus directly with the dedicated line. Due to the fault current contribution of DG, the overcurrent protective relay that have conventional set value cannot detect the fault occurred in distribution power network with DG. Therefore. the impacts from interconnection of DG on the overcurrent protective relay for bus protection should be accurately assessed and mitigated. Simulation results show that it would be necessary to modify the overcurrent protective relay set value for protecting the bus according to the generating capacity of DG.

• Journal of Soil and Groundwater Environment
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• v.19 no.2
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• pp.25-37
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• 2014

The volcanic type of geothermal water is linked intimately to active or potentially active volcanoes and takes place near the plate boundaries. In contrast to the volcanic type, the geothermal water in Korea has a non-volcanic origin. Korea's geothermal water is classified into the residual magma (RM) type and deep groundwater (DG) type according to the criterion of $35^{\circ}C$. This study reviewed the relationship between the physical and chemical features of the 281 geothermal water sources in South Korea in terms of the specific capacity, water temperature, and chemical compositions of two different basements (igneous rock and metamorphic rock) as well as the geological structures. According to the spatial relationship between the geothermal holes and geological faults, the length of the major fault is considered a key parameter determining the movement to a deeper place and the temperature of geothermal water. A negligible relationship between the specific capacity (Q/s) and temperature was found for both the RM type and DG type with the greater specific capacities of the RM- and DG-igneous types than the RM- and DG-metamorphic types. No relationship was observed between Q/s and the chemical constituents ($K^+$, $Na^+$, $Ca^{2+}$, $Mg^{2+}$, $Zn^{2+}$, $Cl^-$, $SO_4{^{2-}}$, $HCO_3{^-}$, and $SiO_2$) in the DG-igneous and DG-metamorphic types. Furthermore, weak relationship between temperature and chemical constituents was found for both the RM type and DG type.