• The Transactions of The Korean Institute of Electrical Engineers
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• v.62 no.4
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• pp.451-456
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• 2013

Development of the technologies for offshore wind power is proceeding actively and the installation capacity is continuously increasing because of its many advantages in comparison with the land wind power. Accordingly, project for Southwestern 2.5GW offshore wind power plant is in progress in Korea. Design of electric power systems for offshore wind power plant is very important due to its high investment and operational costs. Hence, it needs to be designed in order to minimize costs. This way can be employed in determining the installation location of offshore substation for HVAC wind power plant. According to the offshore substation site, MV inter-array cable and HV export cable lengths vary and they change a total cost regarding submarine cable. This paper represents cost models with variables which are MV inter-array cable and HV export cable lengths to locate the offshore substation for HVAC wind power plant. It is classified into submarine cable installation cost, reactive power compensator installation cost, ohmic losses, and unsupplied energy cost. By minimizing a total cost, an appropriate installation site of the offshore substation is determined.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.29 no.8
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• pp.83-89
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• 2015

This study suggests the methodology to decide the number and adequate capacity of substation transformer in a large-scale offshore wind farm (OWF). The recent trend in transformer capacity of offshore substation is analyzed in many European offshore wind farm sites prior to entering the studies. In order to carry out the economic evaluation for the transformer capacity we present the cost models which consist of investment, operation, and expected energy not supplied (EENS) cost as well as the probabilistic wind power model of wind energy that combines the wind speed with wind turbine output characteristics for a exact calculation of energy loss cost. Economic assessment includes sensitivity analysis of parameters which could impact the 400-MW OWF: average wind speed, availability, discount rate, energy cost, and life-cycle.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.63 no.9
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• pp.1192-1198
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• 2014

With an increase in the penetration of offshore wind farm, the need of an accurate economic evaluation of offshore wind farm has become crucial. This paper presents an economic evaluation method of offshore wind farm in Korea reflecting the cost of offshore wind farm infrastructure (offshore substation, submarine cable and foundation) in its cost model. Each cost of offshore substation, submarine cable, and foundation is represented as a function of installed capacity, distance to shore, and water level, respectively. We have applied the method to the case study of offshore in Jeju Island and analyzed the economics under various conditions. The results show that the distance to shore is of importance in economics of offshore wind farm.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.64 no.7
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• pp.984-991
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• 2015

This paper presents the methodology for optimal design of power grid for offshore wind power plant (OWPP) and optimum location of offshore substation. The proposed optimization process is based on a genetic algorithm, where the objective cost model is composed of investment, power loss, repair, and reliability cost using the net present value during the whole OWPP life cycle. A probability wind power output is modeled to reflect the characteristics of a wind power plant that produces electricity through wind and to calculate the reliability cost called expected energy not supplied. The main objective is to find the minimum cost for grid connection topology by submarine cables which cannot cross each other. Cable crossing was set as a constraint in the optimization algorithm of grid topology of the wind power plant. On the basis of this method, a case study is conducted to validate the model by simulating a 100-MW OWF.

• Journal of the Korean Solar Energy Society
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• v.30 no.5
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• pp.44-55
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• 2010

The proposed offshore wind farm projects, i.e., Mooudo offshore, Yeonggwang-Gochang offshore, Saemangeum offshore, Imjado offshore and Gadeokdo-Dadeapo offshore, were compared and analyzed using the Korea National Wind Mapand Wind Farm Suitability Assessment System developed by the Korea Institute of Energy Research. The suitability of the proposed areas was comprehensively assessed using geographic, economic constraints, wave condition and wind resource factors, but the focus of this paper was on the geographic constraints and wave conditions. Imjado had several geographical constraints, despite having a good wind power density, while Saemangeum had a relatively low wave height, shallow water depth, close substation and slow tidal current. It is anticipating that the present comparison and analysis could be used as reference guidelines when selecting and preparing the design of large-scale offshore wind farm in the near future.

• The Transactions of the Korean Institute of Electrical Engineers P
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• v.63 no.4
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• pp.339-344
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• 2014

An offshore wind power plant (WPP) is very expensive and different from an onshore wind power system in many ways. There has been a continuous increase in the capacity of the offshore WPPs. Therefore it is essential to analyze the feasibility and reliability of the offshore wind power to optimize their redundancy. Besides, it is very important to study a planning for grid interconnection of adjacent offshore WPPs. This paper proposes a economic evaluation method to interconnect with adjacent offshore substations in offshore wind power grid. Also, we suggest the probabilistic reliability method to calculate a probabilistic power output of the wind turbine and a cost of the expected energy not supplied that is used as the reliability index of the power system.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.65 no.5
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• pp.811-818
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• 2016

This paper suggests a structure of power control system in floating wave-offshore wind hybrid power generation system. We have developed an unified SCADA(Supervisory Control and Data Acquisition) system which can be used to monitor and control PCS(Power Conversion System) based on IEC61850. The SCADA system is essential to perform the algorithm like proportional distribution and data acquisition, monitoring, active power, reactive power control in hybrid power generation system. IEC61850 is an international standard for electrical substation automation systems. It was made to compensate the limitations of the legacy industrial protocols such as Modbus. In order to test the proposed SCADA system and algorithm, we have developed the wind-wave simulator based Modbus. We have designed a protocol conversion device based on real-time Linux for the communication between Modbus and IEC61850. In this study, SCADA system consists of four 3MW class wind turbines and twenty-four 100kW class wave force generator.

• Proceedings of the KIEE Conference
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• 2015.07a
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• pp.1094-1095
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• 2015

The costs of installation, loss, and energy not supplied energy for submarine cable of offshore wind power plant (OWPP) are very high because the level of technology is still in the early stage as well as because of the marine environments. Therefore, reducing the total costs of a grid network for OWPPs is very important for financial feasibility. In particular, it is needed to minimize the project cost for optimizing the grid design and offshore substation location of a OWPP. The suggested method can reduce the total system cost and make it lower compared with existing methods.

• The Transactions of the Korean Institute of Electrical Engineers P
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• v.66 no.4
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• pp.151-157
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• 2017

In this paper, it is the result of analysis of the stability by power system analysis about the influence on the power system when the southwest - offshore wind power demonstration complex is constructed to 60MW and it is linked with the onshore power system. Considering the position of the wind turbine actually installed and the length of the cooperating line, we modeled the wind generators, offshore substation and the turbine step-up transformer. Changes of voltage when internal and external faults occurred is analyzed and the reactive power demand according to the amount of electricity generation is derived. And also phase angle stability and frequency is observed through a transient analysis. This paper clarify that there is no problem in the system when only offshore wind power is linked with the grid and try to present the reactive power amount necessary for maintaining the voltage of the point of cooperation appropriately.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.27 no.11
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• pp.89-95
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• 2013

In resent years, Offshore Wind Farm (OWF) is being actively developed. Typically, OWF has a better wind resource than onshore one, but also have a very high investment cost and maintenance cost. Furthermore, due to a difficulty of geographical access, OWF can be affected by the failure for a longer time. As the result, OWF has a higher loss cost. Therefore, a reliability evaluation should be performed more carefully at OWF planning stage. In this paper, a methodology for the reliability evaluation on inner grid is suggested. Inner grid connects wind turbines via submarine cables and transfers power to offshore substation. According to location of the faulted cable under layouts of inner grid, the transfer ability of inner grid is influenced. In order to indicate the transfer ability of inner grid, several indices are introduced such as PNDR, EEND and EENDC. To demonstrate the methodology described in this paper, diversity case studies were performed.