The Influence Of Wind Farms On Power System Reliability And Their Capacity Credit Assessment Method

The double pressure of energy shortage and environmental pollution forcesrapidly development of wind power industry, high power wind power generators andlarge scale wind farm has become a trend, the scale of wind power inergration into thepower grid also expands unceasingly. But because the intermittency, volatility andother natural attributes of wind, the integration of wind power generation into thepower grid will bring something different from any conventional units in influence onthe grid. Therefor, researches on these apects are of great significance to thelarge-scale wind energy development.Weibull distribution parameter values reflect wind energy status. The authorfirstly analyzes the influence of wind speed distribution parameters on the reliabilityand explains root causes of different influences of scale parameters and shapeparameters on reliability indexes of different nature. In addition, impacts of the windpower penetration rate and the forced outage rate of wind power generator on thereliability are analyzed. In this paper, centering on the specific example ofIEEE-RBTS, the author evaluates the reliability of the power system including thewind farm by means of the Sequential Monte Carlo simulation and VC++program.The results reveal that the probabilistic reliability index is only sensitive to the scaleparameter while the frequency is sensitive to both the scale and shape parameters.When the wind power penetration rate gradually increases, the reliability contributionof wind power tends to approach a certain kind of saturation. Moreover, it isconcluded that the forced outage rate of wind power generator exerts little influenceon the reliability, which can be ignored in general calculations to simplify thecalculation process.The measurement of the capacity credit of the wind farm is the basic problem tobe solved in the valuation of the wind farm. There are various methods available fordefining and calculating this relatively new concept. In this paper, commonly-usedmethods are clarified in detail and the single point secant method is introduced tocalculate the capacity credit of the wind farm. Based on sequential Monte Carlosimulation, the installed capacity of the wind farm is taken as the initial value and theunilateral iteration calculation is adopted, enabling the capacity credit to graduallyapproach the true value. Compared with dichotomy and simplified Newton method, the unilateral secant method boasts certain advantages in both the selection of initialvalues and the convergence.