• Journal of Electrical Engineering and Technology
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• 제11권2호
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• pp.320-328
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• 2016

The introduction of renewable energy sources into the AC grid can change and weaken the strength of the grid, which will in turn affect the stability and robustness of the doubly-fed induction generator (DFIG) wind farm. When integrated with weak grids, the DFIG wind turbine with vector power control often suffers from poor performance and robustness, while the DFIG wind turbine with synchronized control provides better stability. This paper investigates the critical short circuit ratios of DFIG wind turbine with vector power control and synchronized control, to analyze the stability boundary of the DFIG wind turbine. Frequency domain methods based on sensitivity and complementary sensitivity of transfer matrix are used to investigate the stability boundary conditions. The critical capacity of DFIG wind farm with conventional vector power control at a certain point of common coupling (PCC) is obtained and is further increased by employing synchronized control properly. The stability boundary is validated by electromagnetic transient simulation of an offshore wind farm connected to a real regional grid.

• 신재생에너지
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• 제17권3호
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• pp.16-23
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• 2021

Recently, the Korean government announced a plan to activate renewable energies, with focus on clean energy sources such as solar and wind power as the core and the goal of achieving carbon neutrality by 2050. Unlike other photovoltaic (PV) systems, offshore PV installations are advantageous for large-scale expansion because of the ease of securing sites; they also enable lowering the power generation costs based on construction of large-scale power facilities of megawatt class or higher owing to low noise and landscape damage. However, any power generation should proceed with consideration of the special environmental conditions of the ocean. Above all, when installing large-scale facilities, it is important to reduce fluctuations of the structure and secure stability to actively respond to waves. This study is concerned with the development of a floating body technology that actively responds to waves so as to enable commercialization of offshore solar power. A unit platform for research and development on offshore PV generation was installed in the Saemangeum sea, and the structural fluctuations and stability were analyzed to ensure conformity with the major performance indicators.

• 전산구조공학
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• 제26권2호
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• pp.7-12
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• 2013

• 전기학회논문지
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• 제67권10호
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• pp.1265-1270
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• 2018

One of the ways to improve the stability of power facilities used in power systems is to use power surge arresters and to protect against transient overvoltages and surges in normal operation. Also it is important to reduce the impact of lightning strikes because lightning can create overvoltage in the grid of the wind turbine and affect power quality. So This paper analyzes the effects of overvoltage and adjacent turbines due to single strike and multi strike to ground impedance changes when the surge arrester is deteriorated in a wind power farm.

• 대한토목학회논문집
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• 제34권5호
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• pp.1489-1504
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• 2014

본 논문은 국내 서남해안 해상풍력발전 하부기초설계 시 신뢰성 기반의 한계상태설계법 적용을 위한 말뚝기초의 부분안전계수를 제안하고자 한다. 우선, 해상풍력관련 국제 설계기준서인 IEC, GL, DNV, API, ISO, EUROCODE 등에서 제시한 다양한 부분안전계수 및 저항계수를 비교 분석하였다. 그리고 부안-영광 및 새만금 해역의 서남해안 해상풍력단지의 지반조사 결과를 가지고 불확실성 분석을 수행하였다. 불확실성 분석 결과를 토대로 신뢰성해석을 수행하여 지반정수에 대한 부분안전계수를 산정하였으며, 서남해안 지역의 해상풍력 말뚝기초의 부분안전계수는 1.3으로 평가되었다. 본 논문에서 제안된 부분안전계수는 서남해안에서의 지반조사 결과를 근거로 산정된 것이므로 기타 광역단위 해역에 활용하기 위해서는 추가적인 조사 및 지반정수에 대한 불확실성 분석을 통해 보정이 필요하다고 판단된다.

• 한국해안·해양공학회논문집
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• 제23권2호
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• pp.163-170
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• 2011

해상풍력단지 설계과정의 일환으로 실험계획법의 일종인 반응표면분석법을 이용하여 풍력터빈의 최적 배치조건을 연구하였다. 총 36기 터빈을 해상에 설치한다는 가정 하에 터빈들의 행렬조합, 행간 및 열간거리를 반응표면 분석시의 설계변수로 사용하였으며, 터빈 후류손실에 의해 저하되는 발전효율과 내부 전력선 공사비를 목적함수로 고려하였다. 이러한 설계변수와 목적함수간의 관계를 이용한 반응 최적화 분석을 통해 목표 설계조건을 도출하였으며, 해상풍력단지의 경제성을 확보하기 위한 풍력터빈의 배치조건은 "설계범위에서 행수 및 행간거리를 최소화하고, 최적 열간거리를 산정하여 적용해야 한다"는 결과를 얻을 수 있었다.

• Journal of Electrical Engineering and Technology
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• 제13권3호
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• pp.1089-1098
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• 2018

This study aims at developing and applying a hybrid model to the wind power prediction (WPP). The hybrid model for a very-short-term WPP (VSTWPP) is achieved through analytical data, multiple linear regressions and least square methods (MLR&LS). The data used in our hybrid model are based on the historical records of wind power from an offshore region. In this model, the WPP is achieved in four steps: 1) transforming historical data into ratios; 2) predicting the wind power using the ratios; 3) predicting rectification ratios by the total wind power; 4) predicting the wind power using the proposed rectification method. The proposed method includes one-step and multi-step predictions. The WPP is tested by applying different models, such as the autoregressive moving average (ARMA), support vector machine (SVM), and artificial neural network (ANN). The results of all these models confirmed the validity of the proposed hybrid model in terms of error as well as its effectiveness. Furthermore, forecasting errors are compared to depict a highly variable WPP, and the correlations between the actual and predicted wind powers are shown. Simulations are carried out to definitely prove the feasibility and excellent performance of the proposed method for the VSTWPP versus that of the SVM, ANN and ARMA models.

• 한국신재생에너지학회:학술대회논문집
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• 한국신재생에너지학회 2008년도 추계학술대회 논문집
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• pp.332-333
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• 2008

This paper presents an estimation method of national wind resource potential using a national and GIS(Geographical Information System). The wind resource potential is classified into theoretical, geographical and technical potentials and each category narrows down the previous definition by excluding impossible area to be developed as a wind farm using GIS datasets for onshore and offshore. As a basic unit of wind energy potential at a certain area, API(Average Power Intercepted) is calculated from WPD(Wind Power Density) given by a national wind map which is established by numerical wind simulation, so that a logical and relatively accurate potential estimation is possible comparing with other methods based on a field measurement interpolation which is inevitable to avoid critical assumptions.

• 정보통신설비학회논문지
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• 제10권1호
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• pp.40-45
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• 2011

As increasing the importance of renewable energy recently, the scale of a wind power plant is increasing to the number of GW scale and specially, it is trend to move from onshore to offshore to use the higher quantity and quality of wind. Consequently to meet the trend, it is largely considered the importance of communication protocol to control and monitor remotely. But, because the communication protocol between the control center and a wind turbine has been independently developed by each wind turbine vendor, it is absence of the compatibility and extensibility when the heterogeneous wind turbines are installed in the wind farm. The IEC 61400-25 is the specifying standard for these problems in Europe. In this paper, we will show the state of these problems and present a new structure of communication based on the IEC 61400-25 to get the compatibility and extensibility between a control center and wind turbines.

• 동력기계공학회지
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• 제20권4호
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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.