垂直軸風(fēng)力發(fā)電機(jī)設(shè)計(jì),垂直,風(fēng)力發(fā)電機(jī),設(shè)計(jì) 關(guān)于垂直軸風(fēng)力發(fā)電機(jī)系統(tǒng)結(jié)構(gòu)的研究——文獻(xiàn)綜述 湖州師范學(xué)院 機(jī)械設(shè)計(jì)制造及其自動(dòng)化 09283622 莫昃 摘要:隨著不可再生能源的消耗，人們逐漸被能源危機(jī)的陰影所困擾。于是人們想到以風(fēng)力發(fā)電作為補(bǔ)充能，垂直軸風(fēng)力發(fā)電機(jī)和水平軸風(fēng)力發(fā)電機(jī)面世了。相比水平軸風(fēng)力發(fā)電機(jī)，垂直軸風(fēng)力發(fā)電機(jī)有著啟動(dòng)風(fēng)力小，風(fēng)能利用率高，故障率小，低噪音等諸多優(yōu)點(diǎn)。本文就垂直軸風(fēng)力發(fā)電機(jī)的基礎(chǔ)上進(jìn)行優(yōu)缺點(diǎn)分析，總結(jié)國內(nèi)外風(fēng)力發(fā)電機(jī)的發(fā)展概況。 關(guān)鍵詞：風(fēng)力發(fā)電機(jī)，結(jié)構(gòu)組成，工作原理，優(yōu)化設(shè)計(jì)，結(jié)構(gòu)設(shè)計(jì) 1、引言 在如今化石能源不斷消耗日益減少的時(shí)刻，發(fā)展可再生能源的利用變得尤為重要。而風(fēng)力是一種具有大規(guī)模發(fā)展?jié)摿Φ脑偕鍧嵞茉碵1]。作為一種替代礦物燃料，可再生，是豐富，分布廣泛，清潔，不產(chǎn)生溫室氣體的排放。能從風(fēng)能中提取的經(jīng)濟(jì)力量總額是大大超過目前人類利用來自所有來源，并且在操作過程中，和每單位煤和天然氣能源生產(chǎn)的裝置成本相近 [2]。 風(fēng)力發(fā)電機(jī)種類很多，但總體的歸納起來分為2種：水平軸風(fēng)力發(fā)電機(jī)和垂直軸風(fēng)力發(fā)電機(jī)。水平軸風(fēng)輪的旋轉(zhuǎn)和風(fēng)向平行，具有對(duì)風(fēng)裝置，能隨風(fēng)改變而轉(zhuǎn)動(dòng)。垂直軸的風(fēng)輪一般垂直地面，結(jié)構(gòu)設(shè)計(jì)簡(jiǎn)單，而且無需對(duì)風(fēng)，減少了風(fēng)輪對(duì)風(fēng)是的陀螺力[3]。目前，水平軸風(fēng)力發(fā)電機(jī)的技術(shù)水平要高于垂直軸，風(fēng)力機(jī)大部分都是水平軸，但水平軸風(fēng)力機(jī)由于結(jié)構(gòu)原因，具有一些不可避免的缺陷，而且技術(shù)專利大多為國外公司所有，對(duì)國內(nèi)風(fēng)力發(fā)電機(jī)的發(fā)展極為不利，垂直軸風(fēng)力機(jī)其設(shè)計(jì)方法先進(jìn)，風(fēng)能利用率高，啟動(dòng)速度低，基本不產(chǎn)生噪音等有點(diǎn)，被人們認(rèn)識(shí)和重視，具有廣泛的市場(chǎng)應(yīng)用前景。 2、風(fēng)力發(fā)電機(jī)的研究現(xiàn)狀與發(fā)展趨勢(shì) 2.1風(fēng)力發(fā)電機(jī)的基本知識(shí) 風(fēng)力發(fā)電機(jī)裝置主要由葉片、調(diào)速機(jī)構(gòu)、低速軸、齒輪箱、剎車、高速軸、發(fā)電機(jī)、調(diào)向結(jié)構(gòu)、臺(tái)架、塔架構(gòu)成[4]。風(fēng)力發(fā)電是將風(fēng)能轉(zhuǎn)換成機(jī)械能的動(dòng)力熱能，風(fēng)以一定速度和攻角作用在槳葉上，使槳葉產(chǎn)生旋轉(zhuǎn)力矩，轉(zhuǎn)動(dòng)軸，并通過低速軸，增速箱，高速軸等部件，將風(fēng)能轉(zhuǎn)變成機(jī)械能，最后驅(qū)動(dòng)高速發(fā)電機(jī)發(fā)電。簡(jiǎn)單的說就是空氣流動(dòng)的動(dòng)能作用在葉輪上，將動(dòng)能轉(zhuǎn)換成機(jī)械能，從而推動(dòng)葉輪旋轉(zhuǎn)[5]。風(fēng)力發(fā)電依靠風(fēng)能，是可再生清潔能源，相比熱力發(fā)電要好得多，無污染，零排放，只需要大約3m/s的微風(fēng)，就能開始發(fā)電。 2.2 研究現(xiàn)狀 風(fēng)力發(fā)電的技術(shù)始于19世紀(jì)美國的Charles F.Bursh(1849-1929)，他在俄亥俄州克利夫蘭市安裝了被現(xiàn)代人認(rèn)為的第一臺(tái)自動(dòng)運(yùn)行且用于發(fā)電的風(fēng)力機(jī)[6]。 1891年，丹麥的Poul la Cour（1846-1908）制造了用來發(fā)電的風(fēng)力機(jī)，并建立了風(fēng)力發(fā)電機(jī)實(shí)驗(yàn)的風(fēng)洞，發(fā)現(xiàn)葉片數(shù)少，轉(zhuǎn)動(dòng)越快的風(fēng)力機(jī)在發(fā)電是比轉(zhuǎn)速低的分離機(jī)效率高得多[6]。 1920年至1930年，丹麥約有120個(gè)地方公用事業(yè)擁有風(fēng)力發(fā)電，單機(jī)容量一般為20~35KW，總裝機(jī)容量約為3MW[6]。 直至20世紀(jì)20年代才出現(xiàn)了垂直軸風(fēng)力發(fā)電機(jī)，芬蘭的工程師Savonius發(fā)明了典型的阻力式垂直軸風(fēng)力發(fā)電機(jī)，命名為薩窩紐斯型風(fēng)力機(jī)，是一種S型風(fēng)輪[6]。 1927年，由法國工程師達(dá)理厄（G.J.M.Darrieus）發(fā)明了達(dá)理厄型風(fēng)力發(fā)電機(jī)組，是典型的利用翼型的升力做功的升力垂直軸風(fēng)力發(fā)電機(jī)。達(dá)理厄風(fēng)力發(fā)電機(jī)種類很多，如H型、Δ型、◇型，φ型，其中以H型和φ型最為典型。厄爾里風(fēng)力機(jī)組轉(zhuǎn)速高，旋轉(zhuǎn)慣性大，結(jié)構(gòu)簡(jiǎn)單成本低，但是啟動(dòng)性能差，需要啟動(dòng)機(jī)構(gòu)和離合器，提高了系統(tǒng)結(jié)構(gòu)的復(fù)雜性和成本[6]。 1941年10月，工程師Palmer C.putnamh和馬薩諸塞州一些注明科學(xué)家研制了第一臺(tái)大型的并網(wǎng)風(fēng)力發(fā)電機(jī)，并在佛蒙特州的小山頂安裝，風(fēng)輪直徑53.3m。額定輸出1250KW，塔高35.6米，它可能是世界上第一臺(tái)大型風(fēng)力發(fā)電機(jī)[6]。 1950年，丹麥的Vester Egesborg開發(fā)了世界上第一臺(tái)交流風(fēng)力發(fā)電機(jī)，并在1956年至1957年為SWAS電力公司在丹麥南部Gedser海岸建成了新型200KW的Gedser風(fēng)力發(fā)電機(jī)，這是當(dāng)時(shí)世界上最大功率的交流風(fēng)力發(fā)電機(jī)，并在不需維護(hù)的情況下運(yùn)行了11年之久[6]。 20世紀(jì)80年代，歐洲風(fēng)力發(fā)電機(jī)組設(shè)計(jì)概念出現(xiàn)了多元化格局。至90年代，單機(jī)容量不斷增加，300KW、500KW、600KW、750KW風(fēng)力發(fā)電機(jī)成為主流機(jī)型[6]。 2.3 發(fā)展趨勢(shì) 風(fēng)能資源儲(chǔ)備量大，全球風(fēng)能資源總量達(dá)2.47×109兆瓦，其中可利用的風(fēng)能為2×107兆瓦，裝機(jī)容量可達(dá)10TW，每年可發(fā)出電力13PWh。比地球上可開發(fā)利用的水能總量還大10倍[7]。中國風(fēng)能儲(chǔ)量很大，面積廣開發(fā)利用潛力巨大，在陸地加上近海的風(fēng)力資源有16億千瓦以上[7]。目前全球風(fēng)力發(fā)電已逐步從探索走向成熟，風(fēng)力發(fā)電事業(yè)也逐步擴(kuò)大范圍和領(lǐng)域。2006年7月22日，中國垂直軸風(fēng)力試驗(yàn)基地在內(nèi)蒙古化德縣正式啟動(dòng)，是我國自主研發(fā)，擁有自主知識(shí)產(chǎn)權(quán)的新星風(fēng)力發(fā)電機(jī)組，目前，50KW小樣機(jī)組已建成投入 運(yùn)行開始發(fā)電[8]。2007年9月，西山瑞法水力發(fā)電設(shè)備公司和哈爾濱發(fā)電設(shè)備研究中心聯(lián)合開發(fā)設(shè)計(jì)的1.5MW垂直軸永磁風(fēng)力發(fā)電機(jī)研制成功，并在張家口風(fēng)電場(chǎng)安裝運(yùn)行[8]。麟風(fēng)瘋癲設(shè)備公司主導(dǎo)產(chǎn)品為H型垂直軸風(fēng)力發(fā)電機(jī)，他改變了“攻角”技術(shù)，達(dá)到了最大風(fēng)能利用率[9]。 3、結(jié)束語 相比水平軸風(fēng)力發(fā)電機(jī)，垂直軸風(fēng)力發(fā)電機(jī)可以用先進(jìn)的計(jì)算流體力學(xué)方法，能精確的分析流體過程。而且垂直軸風(fēng)力機(jī)的葉片基本都是幾何構(gòu)型，易于加工，葉片旋轉(zhuǎn)空間小，可全方位接受來風(fēng)，無需轉(zhuǎn)向裝置，充分利用風(fēng)能，發(fā)電效率高達(dá)70%以上，并且能抵抗12-14級(jí)臺(tái)風(fēng)，低噪音，故障率低，風(fēng)機(jī)接近地面，更加利于維護(hù)保養(yǎng)，發(fā)電曲線飽滿。無論是風(fēng)電場(chǎng)還是中小型獨(dú)立用戶，垂直軸風(fēng)力發(fā)電機(jī)必定被大量應(yīng)用。 綜上所述，垂直軸風(fēng)力發(fā)電機(jī)的總體設(shè)計(jì)，電路系統(tǒng)及傳動(dòng)系統(tǒng)設(shè)計(jì)，其他部位設(shè)計(jì)將成為本畢業(yè)實(shí)際主要研究方法，通過各種文獻(xiàn)和書籍參考比較，從中選擇出幾個(gè)合理的風(fēng)力機(jī)設(shè)計(jì)方案，再計(jì)算比出啟動(dòng)性能穩(wěn)定，發(fā)電效率高，噪音小，成本低廉的設(shè)計(jì)方案， 本次畢業(yè)設(shè)計(jì)的重點(diǎn)是通過比較葉片實(shí)度、形狀和材料設(shè)計(jì)葉片，根據(jù)電路系統(tǒng)挑選發(fā)電機(jī)類型，設(shè)計(jì)合理的傳動(dòng)結(jié)構(gòu)和傳動(dòng)軸、軸承，設(shè)計(jì)塔架、蓄電池、箱體外形等，最后通過比較數(shù)據(jù)，優(yōu)化，設(shè)計(jì)出最合理的設(shè)計(jì)方案。 參考文獻(xiàn)： [1]寇 微等. 一種組合型垂直軸風(fēng)力發(fā)電機(jī)的結(jié)構(gòu)設(shè)計(jì)[J].電力科學(xué)與工程，2011，27（5）：25-28 [2]HE SIYUAN. Capacity credit of wind power generation problems and solutions[C] [3]http://baike.baidu.com/view/1070501.htm [4]鄭 云. 小型H型垂直軸風(fēng)力發(fā)電機(jī)氣動(dòng)性分析[D].西安：西安交通大學(xué)，2008：3-10 [5]王 輝. 一種垂直軸風(fēng)力發(fā)電機(jī)結(jié)構(gòu)設(shè)計(jì)[J].科技信息，2010，21：99 [6]趙丹平等. 風(fēng)力機(jī)設(shè)計(jì)理論及方法[M].北京：北京大學(xué)出版社，2012：1-29 [7]田海蛟.等 垂直軸風(fēng)力發(fā)電機(jī)發(fā)展概述[J].應(yīng)用能源技術(shù)，2006（11）：22-27 [8]孫云峰等.垂直軸風(fēng)力發(fā)電機(jī)的發(fā)展概況及趨勢(shì)[J].農(nóng)村牧區(qū)機(jī)械化，2008（2），75：42-44 [9]嚴(yán) 強(qiáng)等. 垂直軸風(fēng)力發(fā)電機(jī)的發(fā)展趨勢(shì)和應(yīng)用[J].上海電力，2007，2：166-167 畢業(yè)設(shè)計(jì)（論文）——外文翻譯（原文） Capacity credit of wind power generation problems and solutions People have used wind energy for thousands of years. The earliest known use of wind power is by the Egyptians some 5000 years ago, who used it to sail their boats from shore to shore on the Nile. Around 2000BC the first windmill was built in Babylon. Till now, people have used wind power generation to generate for so many years and the research on this field is keep moving all the time. People have found the huge potential on helping we to solve the energy crisis, so I want to just discuss one easy aspect on the wind power generation about its problems and the solutions. First, I will point out some basic concepts about wind power as the foundation of the further discussion. Wind power is the conversion of wind energy into a useful form of energy, such as using wind turbines to make electricity, windmills for mechanical power, windpumps for water pumping or drainage, or sails to propel ships. The total amount of economically extractable power available from the wind is considerably more than present human power use from all sources. Wind power, as an alternative to fossil fuels, is plentiful, renewable, widely distributed, clean, and produces no greenhouse gas emissions during operation, and the cost per unit of energy produced is similar to the cost for new coal and natural gas installations. A large wind farm may consist of several hundred individual wind turbines which are connected to the electric power transmission network. Offshore wind power can harness the better wind speeds that are available offshore compared to on land, so offshore wind power’s contribution in terms of electricity supplied is higher. Small onshore wind facilities are used to provide electricity to isolated locations and utility companies increasingly buy back surplus electricity produced by small domestic wind turbines. The construction of wind farms is not universally welcomed, but any effects on the environment from wind power are generally much less problematic than those of any other power source. A wind farm is a group of wind turbines in the same location used for production of electric power. A large wind farm may consist of several hundred individual wind turbines, and cover an extended area of hundreds of square miles, but the land between the turbines may be used for agricultural or other purposes. A wind farm may also be located offshore. In a wind farm, individual turbines are interconnected with a medium voltage (often 34.5 kV), power collection system and communications network. At a substation, this medium-voltage electric current is increased in voltage with a transformer for connection to the high voltage electric power transmission system. The surplus power produced by domestic micro-generators can, in some jurisdictions, be fed into the network and sold to the utility company, producing a retail credit for the micro-generators' owners to offset their energy costs. Electricity generated from wind power can be highly variable at several different timescales: from hour to hour, daily, and seasonally. Annual variation also exists, but is not as significant. Related to variability is the short-term (hourly or daily) predictability of wind plant output. Like other electricity sources, wind energy must be "scheduled". Wind power forecasting methods are used, but predictability of wind plant output remains low for short-term operation. Because instantaneous electrical generation and consumption must remain in balance to maintain grid stability, this variability can present substantial challenges to incorporating large amounts of wind power into a grid system. Intermittency and the non-dispatchable nature of wind energy production can raise costs for regulation, incremental operating reserve, and (at high penetration levels) could require an increase in the already existing energy demand management, load shedding, or storage solutions or system interconnection with HVDC cables. At low levels of wind penetration, fluctuations in load and allowance for failure of large generating units require reserve capacity that can also regulate for variability of wind generation. Wind power can be replaced by other power stations during low wind periods. Transmission networks must already cope with outages of generation plant and daily changes in electrical demand. Systems with large wind capacity components may need more spinning reserve. After knowing about some basic aspects, we have a relatively clear concept in many ways, such as wind farms, electricity generation,, variability and intermittency. So next, I will discuss the topic of this thesis, Capacity Credit. The capacity credit of wind power in a grid has received quite some attention in the past. In the early days of wind power, the capacity credit, or rather the perceived lack thereof, was a grave concern for the large-scale development of wind power on a nation-wide basis. Therefore, a number of studies were made since the 1970ies, arriving at the conclusion that wind power has a capacity credit and the capacity credit is around the mean wind power output for small penetrations of wind power in the grid, and drops to a value near the minimum wind power generation for larger penetrations. The value of wind energy has traditionally been assessed by a comparison of wind power output characteristics to those of conventional power plants. This reflects the cost-based planning paradigm of the regulated electricity market. The standard of measure of the comparison is the availability of both plant types. Forced outage rates of conventional plants and wind availability captured by the probability distributions of wind speed are aggregated to a cumulative availability function using reliability models. An acceptable loss of load probability determines the maximum load. On this basis capacity credit is calculated as an “equivalent capacity” of wind generators to conventional generators with respect to reliability. As available wind energy varies over time, capacity credit changes as well. Therefore the capacity credit in time of peak demand is generally used for further interpretation. Consequently, a high correlation between wind energy production and electricity demand would result in a high capacity credit assigned to wind generators. An intermittent energy source is any source of energy that is not continuously available due to some factor outside direct control. The intermittent source may be quite predictable, for example, tidal power, but cannot be dispatched to meet the demand of a power system. An example of intermittent sources is the wind. The concept that Capacity Credit of wind power is relativity newly so till now there is not a clear and agreed by all definition. Many researchers concentrate on whether or not wind has any "capacity credit" without defining what they mean by this and its relevance. Wind does have a capacity credit, using a widely accepted and meaningful definition, equal to about 20% of its rated output (but this figure varies depending on actual circumstances). This means that reserve capacity on a system equal in MW to 20% of added wind could be retired when such wind is added without affecting system security or robustness. UK academic commentator Graham Sinden, of Oxford University, argues that this issue of capacity credit is a "red herring" in that the value of wind generation is largely due to the value of displaced fuel-not any perceived capacity credit – it being well understood by the wind energy proponents that conventional capacity will be retained to "fill in" during periods of low or no wind. The main value of wind, (in the UK, 5 times the capacity credit value) is its fuel and CO2 savings. Wind does not require any extra back-up, as is often wrongly claimed, since it uses the existing power stations, which are already built, as back-up, and which are started up during low wind periods, just as they are started up now, during the non availability of other conventional plant. More spinning reserve, of existing plant, is required, but this again is already built and has a low cost comparatively. The capacity factor of a power plant is the ratio of the electrical energy produced in a given period of time to the electrical energy that could have been produced at continuous maximum power operation during the same period. For a conventional fossil-fuel power station, the capacity factor is determined by planned maintenance downtime, unplanned equipment failure, and by shutdowns when the station’s electricity is not needed. For wind and solar energy, power output is also determined by the availability of wind and sunlight. The maximum power output, or ‘installed capacity’, is a rather theoretical value that is rarely reached. It would be clearer to quote the mean power for solar and wind energy, but because peak power is more commonly quoted, it’s important to know the capacity factor as well, to make sense of the peak numbers. So after comprehending the capacity factor of wind?power generation, we know that’s the ratio between a wind farm’s average power output and its maximum or “nameplate” capacity. That ratio is usually between about 20% and 30%. That is, when averaged over a year, a wind farm produces about 20%–30% as much energy as it would if it operated continuously at its maximum power output. But with research growing, there is another more advanced key operating parameter for wind power generation, its “capacity credit”. Whereas the capacity factor is a measure of the average output of a wind farm, the capacity credit is a measure of the worst case minimum output that can be relied on as a part of the total system capacity. The capacity credit is the “firm” capacity of a wind farm that can be counted on as a reliable contribution to the sum of all grid capacity. The capacity credit of wind, is estimated by determining the capacity of conventional plants displaced by wind power, whilst maintaining the same degree of system security, in other words an unchanged probability of failure to meet the reliability criteria for the system. Alternatively, it is estimated by determining the additional load that the system can carry when wind power is added, maintaining the same reliability level. For low wind energy penetrations levels, the relative capacity credit of wind power (that is ‘firm’ capacity as a fraction of total installed wind power capacity) will be equal or close to the average production (load factor) during the period under consideration, which is usually the time of highest demand. For Northern European countries, this is winter time and the load factor is typically 25–30 percent onshore and up to 50 per cent offshore. The load factor determining the capacity credit in general is higher than the average yearly load factor. With increasing penetration levels of wind energy in the system, its relative capacity credit reduces. However, this does not mean that less conventional capacity can be replaced, but rather that a new wind plant added to a system with high wind power penetration levels will substitute less than the first wind plants in the system. Put another way, the capacity credit of a wind farm is the amount by which other generating capacity (such as coal, for example) can be removed from the grid without compromising reliability of supply. Wind is unusual, however, in the unpredictability of its output. It doesn’t have the fixed periodic variations of tidal or solar. This unpredictability of wind power makes the question of its capacity credit a rather complicated one. What, then, is the capacity credit of wind power? What is that minimum power capacity that a wind farm can reliably provide? Since a wind farm’s output can drop all the way to zero, it seems at first sight that the capacity credit of wind power must be zero. In fact that’s not the case. It would be true if the wind farm operated in isolation, but a wind farm is usually connected to a much larger supply grid. Supply and demand across the grid vary all the time, and energy planners have developed detailed statistical calculations to handle this problem. They plan grid capacity so as to meet a given “l(fā)oss of load probability”, or LOLP. The LOLP is the probability that generation will be insufficient to meet demand. Energy supply planners must ensure that there is sufficient capacity to keep the loss of load probability below some specified level, but they don’t want to spend money needlessly on surplus capacity beyond that. One issue of managing risk is that wind farms can be treated statistically in exactly the same way as conventional power plant. For any type of power plant it is possible to calculate the probability of it not being able to supply the expected load. As wind is variable, the probability that it will not be available at any particular time is higher. Wind power can be factored into the grid reliability statistics in exactly the same way as every other power source. Wind has a lower probability of being available, but that number is simply fed into the calculations. There is nothing qualitatively different about wind. Energy engineers have taken a careful look at the statistics of wind supply, and their conclusion is that wind has a significant capacity credit after all. How can this be? After all, the wind speed can drop all the way to zero. To answer that, we have to look at the supply statistics across the entire electricity grid. For example, when wind power is geographically dispersed, it becomes less likely that the wind will stop blowing at all wind farm sites simultaneously. That’s not to say it’s impossible, but it is less likely. Also, when wind strength and electricity demand correlate (for example, in regions where the wind is stronger during the winter) there is again a higher likelihood that wind will contribute to that demand. After then, what are the actual numbers for the capacity credit of wind power? The capacity credit of wind depends on the fraction of total grid capacity that is met by wind power. In the jargon, it depends on the “penetration” of wind power on the grid. “Wind energy penetration” is generally defined as the ratio of the total amount of wind energy produced in a year to the total electrical energy produced in a year for a given region, while “wind capacity penetration” is defined as the ratio of installed wind power capacity to peak load for a given region. When the amount of wind capacity is a negligible fraction of the total grid capacity, the capacity credit of the wind farm can be treated as being equal to the average power of the wind farm. That is, the capacity credit is the same as the capacity factor multiplied by the installed capacity. That’s because at very low levels of wind penetration, the grid can deal with fluctuations in wind output as part of its routine capability. As wind capacity increases to about 10% of total grid capacity, the capacity credit falls to about 20% of the installed capacity (peak power) of the wind farm. That is, the capacity credit is now lower than the average power of the wind farm. If still more wind farms are built, so that wind capacity increases to well above 10% of grid capacity, then wind starts to form a very substantial part of total electricity supply. There is now less leeway elsewhere in the system, and the capacity credit falls further still, to about 10% of installed capacity. That is, each 1?GW of installed wind capacity must be treated as only 100?MW of “firm” capacity. Put another way, each 1?GW of installed wind capacity allows 100?MW of conventional (gas or coal) capacity to be removed from the grid, although that wind capacity supplies about 300?MW of power on average (because it still has a 30% capacity factor). Since we have already known that the capacity credit of wind power generation can be quantificational, we will discuss how to calculate capacity credit of wind power generation. Power systems must have enough generation to meet demand at each moment of the day. In addition, they must also have enough reserve to deal with unexpected contingencies. The increase in the penetration of wind generation in recent years has led to a number of challenges in the calculations required to facilitate wind generation while maintaining the existing level of security of supply. A key calculation in this process is the capacity credit or value of wind generation. Capacity credit/value of wind generation can be broadly de?ned as the amount of ?rm conventional generation capacity that can be replaced with wind generation capacity, while maintaining the existing levels of security of supply. Power system reliability consists of system security and adequacy. A power system is adequate if there is a sufficient installed power supply to meet customer needs. A system is secure if it can withstand a loss (or potentially multiple losses) of key power supply components such as generators or transmission links. This paper focuses on the impact that wind generation has on generation adequacy. The analyses for generation adequacy are made several months or years ahead and associated with static conditions of the system. This can be studied by a chronological generation load model that can include transmission and distribution or by probabilistic methods. The estimation of the required production needs includes the system demand and the availability data of production units. Capacity credit is the contribution that a given generator makes to overall system adequacy. Even the availability of conventional generation is not assured at all times because there is always a nonzero risk of mechanical or electrical failure. Because reliability is expensive it is common to adopt a reliability target for the system. The capacity value of any generator is the amount of additional load that can be served at the target reliability level with the addition of the generator in question. Although there are several methods used to calculate wind capacity value, most methods are based on power system reliability analysis methods. The criteria that are used for the adequacy evaluation include the loss of load expectation (LOLE), the loss of load probability (LOLP) and the loss of energy expectation (LOEE), for instance. LOLP is the probability that the load will exceed the available generation at a given time. This criterion gives an idea of the possibility of system malfunction but it lacks information on the importance and duration of the outage. LOLE is the number of hours, usually per year, during which the load will not be met over a de?ned time period. One key capacity value metric is effective load carrying capability (ELCC). This metric is calculated by calculating a suitable reliability measure such as loss of load probability or loss of load expectation for the year. During the course of system operation through the year, generating units can be in one of several states. Units are scheduled for maintenance at regular intervals, and this is typically scheduled during noncritical system periods. However, it is always possible that any generator could fail unexpectedly at any time of the year. The unexpected nature of these forced outages is the primary concern and focus of reliability analysis. Contingency reserves (sometimes called disturbance re-serves) are provided to ensure against system collapse in the event of a forced outage. System adequacy assessments must take planned outages and forced outages into account, although the different types of outages are treated very differently in the reliability model. Additional considerations include hydro system operation, both run of river and reservoir hydro power (and pumped storage, if available). Other system services may also be quanti?ed in the reliability model. While hourly load and wind gen