• The Transactions of The Korean Institute of Electrical Engineers
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• v.56 no.10
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• pp.1715-1720
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• 2007

The CSC-based HVDC system links the Jeju system to the mainland system. Because CSC-based HVDC is installed in Jeju, the reactive power is needed to transfer active power through the HVDC. In order to supply reactive power, switched capacitors and synchronous condensers are installed in Jeju system. The deterioration of established synchronous condensers, however, causes a reactive power supply capability decline and high maintenance cost. It brings about the instability of Jeju system and the incremental of maintenance and repair costs. In the future the installation of wind generators and additional HVDC system would aggravate the stability of Jeju system. Therefore, it needs to consider a countermeasure against above problems. In this paper, Analysis of several contingencies of Jeju system was peformed, and some contingencies caused voltage-reactive power problem was known. CPF method was introduced in order to make countermeasures to replace the synchronous condensers and to solve the voltage-reactive power problem. The location and capacity of reactive power sources were also decided. It could guarantee medium and long term stability of Jeju system.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.59 no.9
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• pp.1540-1548
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• 2010

KEPCO proposes enhanced voltage management system that is a coordinate voltage control system between the hierarchical voltage control system and the slow voltage control system. It has been installing in Jeju island. VMS consists of a master controller, CVC (Continuous Voltage Controller) and DVC (Discrete Voltage Controller). CVC consists of main controller, FDMU (Field Data Measurement Unit) and several RPDs (Reactive Power Dispatcher). CVC has a control scheme with AVRs of generator to maintain the voltage of a pilot bus in a power system, DVC has a control scheme with static reactive power sources, like a shunt capacitor, a shunt reactor, ULTC and so on, to maintain the reactive power reserve of a power system and a master controller is executed to recover reactive power margin of a power system through coordinated control between CVC and DVC.

• The Transactions of the Korean Institute of Power Electronics
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• v.27 no.2
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• pp.92-99
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• 2022

Due to space and geographical constraints, the power source may be located outside the island area, resulting in the considerable length of transmission line. In these cases, when an active power is transmitted, unexpected reactive power is generated at a point of common coupling (PCC). Unlike the power transmitted from the power generation source, the reactive power adversely affects the system. This study proposes a new algorithm that controls reactive power at PCC. Causes of reactive power errors are separated into parallel and series components, which allows the algorithm to compensate the reactive current of the inverter output and control reactive power at the PCC through calculations from the impedance, voltage, and current. The proposed algorithm has economic advantages by controlling the reactive power with the inverter of the power source itself, and can flexibly control power against voltage and output variations. Through the simulation, the algorithm was verified by implementing a power source of 3 [kVA] capacity connected to the low voltage system and of 5 [MVA] capacity connected to the extra-high voltage system. Furthermore, a power source of 3 [kVA] capacity inverter is configured and connected to a mock grid, then confirmed through experiments.

• Proceedings of the KIEE Conference
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• 1996.07b
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• pp.1298-1300
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• 1996

The application field of photovoltaic system which has no-pollution and no-fuel distinctives is being spreaded inspite of its high installation cost. At present, there are three PV systems within the country, which were already installed and have been operated to supply the electric power in remote island. In this paper, the electrification plan of our government on the unelectrified or subelectrified islands is introduced, and the operation results of three PV systems are investigated to discuss the diffusion possibility of PV system as a power supply option.

• Proceedings of the KIEE Conference
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• 2007.07a
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• pp.606-607
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• 2007

This paper is about optimal flywheel capacity estimation for Ullueng-do power system. The power system of Ullueng-do has some differences with other island power system in Korea. It includes wind generator, hydro-generators as well as diesel generators. There are some problems on 600kW wind generator. Because of frequent drop of wind generator, the Ulleung-do power system have been threatened on frequency. The power frequency is 60Hz, and it should be between 59.9 and 60.1Hz. However, since the electrical inertia is small and the weight of wind generation is relatively high, generator drop of wind generation might make the power frequency out of boundary. In this paper, the flywheel energy storage system is assumed to be installed on Ulleung-do power system. Then, the maximum wind generation capacity and the optimal superconducting flywheel energy storage system capacity is estimated by the transient stability simulations.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.61 no.9
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• pp.1221-1225
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• 2012

This paper describes CSC(Current Sourced Converters)-based HVDC operational strategy for voltage stability enhancement in the power system. In case of CSC-based HVDC system, rectifier and inverter consume reactive power up to about 60% of converter rating. Therefore, CSC-based HVDC is basically not useful system for voltage stability even if AC filters and shunt capacitors are attached. But, If the particular power system condition is fulfilled, CSC-based HVDC also can be the rapid reactive power source for voltage stability enhancement using a cooperative control with converter and AC filters/Shunt Capacitors. In this paper, the cooperative control algorithm is presented and simulated to ${\pm}80kV$ 60MW HVDC system in Jeju island.

• Proceedings of the KIPE Conference
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• 2003.07a
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• pp.375-378
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• 2003

This paper presents a study on the power factor improvement of the Wind turbine Generation System(WTGS) at Haeng-won wind farm in Jeju Island. Vestas WTGS named V47 as a model system is selected in this paper, and has 660 kW Power ratings. In this system, power factor correction is controlled by the conventional method with power condenor bank. So, model system at Haeng-won wind farm has very low power factor in the area of low wind speed, which is from 4 m/s to 6 m/s. This is caused by the power factor correction using power condenser bank To improve the power factor in the area of low wind speed, we used the static var compensator(SVC) using current controlled PWM power converter by IGBT switching device. finally, to verify the profosed method, the results of computer simulation using Psim program are presented to support the discussion.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.67 no.4
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• pp.512-521
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• 2018

Islands that is far away from onshore have used internal-combustion engine driving alternators to secure electric power. However, with Paris convention on climate change, there is a growing interest in eco-friendly energy independent island that replaces microgrid(MG) consisting of photovoltaic, wind power, and energy storage system with alternators for internal combustion engines. And also, national emission trading has been implemented, and the price of certified emission reduction(CER) has a influence on system marginal price(SMP). Because, the low cost generation source decides SMP when CER price is low, while the more expensive generation source decides SMP when CER price is high. Therefore, the increasing of CER price has a strong influence on the annualized return of MG independent power producer. Moreover, the fixed RPS price is implemented from 2017, which the increasing of CER price under the fixed RPS price or the variable RPS price affects annualized return differently. In this paper, the annualized return according to CER price is analyzed for large, middle, and small scaled islands, the effect of CER price on the annualized return was confirmed.

• Journal of Power System Engineering
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• v.20 no.4
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• pp.44-51
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• 2016

An investigation on reliability of reanalysis wind data was conducted using the met mast wind data at four coastal regions, Jeju Island. Shinchang, Handong, Udo and Gangjeong sites were chosen for the met mast sites, and ERA-Interim and MERRA reanalysis data at two points on the sea around Jeju Island were analyzed for creating Wind Statistics of WindPRO software. Reliability of reanalysis wind data was assessed by comparing the statistics from the met mast wind data with those from Wind Statistics of WindPRO software. The relative error was calculated for annual average wind speed, wind power density and annual energy production. In addition, Weibull wind speed distribution and monthly energy production were analyzed in detail. As a result, ERA-Interim reanalysis data was more suitable for wind resource assessment than MERRA reanalysis data.

• Journal of the Korean Solar Energy Society
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• v.27 no.2
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• pp.37-44
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• 2007

As photovoltaic(PV) power generation system becomes more common, it will be necessary to investigate islanding detection method for PV systems. Islanding of PV systems can cause a variety of problems and must be prevented. However, if the real and reactive power of the load and PV system are closely matched, islanding detection by Passive methods becomes difficult. Also, most active methods lose effectiveness when there are several PV systems feeding the same island. The active frequency drift positive feedback method(AFDPF) enables islanding detection by forcing the frequency of the voltage in the island to drift up or down. In this paper the research for the minimum value of chopping fraction gain applied digital phase-locked-loop (DPLL) to AFDPF considering output power quality and islanding prevention performance are performed by simulation and experiment according to IEEE Std 929-2000 islanding test.