毕业论文 风力涡轮发电机雷击风险评估方法和解决方案

毕业论文 风力涡轮发电机雷击风险评估方法和解决 方案 气瓶 现场处置方案 .pdf气瓶 现场处置方案 .doc见习基地管理方案.doc关于群访事件的化解方案建筑工地扬尘治理专项方案下载 毕业论文 风力涡轮发电机雷击风险评估方法和解决方 案 风力涡轮发电机雷击风险评估方法和解决方案 摘要:本文论述了风力涡轮发电机的直击雷风险评估方法,通过此方法得出风力涡轮发电机的直击雷保护等级。依据防护等级,提出直击雷保护的解决方案,该方案利用传统空气间隙型避雷器的工作原理和共地不共线的原则,为涡轮发电机的直击雷保护提出了一种的新思路。 关键词:风险评估;改进方法;保护措施; 1、前言 风能做为当前最具开发潜能、最清洁的可再生资源,已经被人们广泛接受和利用。我国风力资源丰富,风力涡轮发电机的分布较广,在我国电力事业和经济快速发展中,发挥着越来越重要的作用。 但是,由于风力涡轮发电机是工作在露天的自然环境中,不可避免地受到自然灾害的影响,尤其是雷电的影响。随着涡轮发电机技术的成熟,发电机组装机容量不断增加,为了获得更多的风能,涡轮发电机的轮毂和叶片半径随着塔架的增高而增高,同时也增大了风力涡轮发电机叶片、机舱等重要部件遭受雷击的概率,严重地影响了风力涡轮发电机的正常工作,大大增加了维护费用,并对工作人员的人身安全造成安全隐患。 为了最大限度的减少涡轮发电机遭受直接雷击时损坏的概率,同时确保工作人员的人身安全,必须对风力涡轮发电机采取相应的直击雷防护措施。风力涡 轮发电机的直击雷电防护是一项系统性、复杂性的工程,必须在认真调查地理、地质、土壤、气象、环境等条件和雷电活动规律以及了解风力涡轮发电机的组成、系统特点、重要性和损坏后产生的后果等基础上,经过雷击风险评估后,合理地做出雷电防护要采取的措施,做到安全可靠、技术先进、经济合理。 2、风力涡轮发电机直击雷风险评估和决绝方案 本评估方法借鉴国内外关于直击雷风险评估的先进经验,并结合我国的实际情况,为风力涡轮发电机的雷击风险评估提出一种方法和程序,为防雷工程的实施提供一个科学的依据,最大限度地发挥防雷保护措施的效能,并提出一种直击雷的解决方案。 本评估将以一个轮毂高度为80米,叶片长度为40米的风力涡轮发电机为例。假设坐落在一个土壤电阻率为500Ω?m的平原地区,与风力涡轮发电机组分开的操作间距离为500米。操作间尺寸:长5米,高3米,宽4米。该地区的雷暴日为56a/d。如图1: 2.1涡轮发电机直击雷风险评估 任何防雷保护系统在设计之前,都应该考虑雷电对风力涡轮发电机破坏的风险问题。对雷击风力涡轮发电机造成损害的风险评估将有助于防雷保护设计者是否建立防雷保护系统和选择合适的保护措施。选择足够的保护等级是为了将直击雷造成损坏的风险降低到可接受的范围之内。任何建筑物的雷击风险是一个与风力涡轮发电机的高度、所处的地理环境和当地的雷电活动频率有关的一个函数。 对于风力涡轮发电机的年预计雷击次数,我们可以按照图2的 流程 快递问题件怎么处理流程河南自建厂房流程下载关于规范招聘需求审批流程制作流程表下载邮件下载流程设计 图对防雷保护系统进行评估[1]。 风力涡轮发电机的年预计雷击次数应按下列公式确定[2]: Nd=Ng×Ad×Cd×10-6 (1) 式中 Nd:风力涡轮发电机的年预计雷击次数(次/a); Ng:风力涡轮发电机所在地区雷击大地年平均密度(次/km2?a); Ad:与风力涡轮发电机截收相同雷击次数的等效面积(km2); Cd:环境因子,对于风力涡轮发电机,位于平地时取1.0,位于山丘时取2.0; Nd计算中的各个参数,其中Ng为客观存在的一个重要因子,因此对风力涡轮的年雷击次数进行评估时,收集当地的雷击大地密度数据是必要的,这些数据可以由当地气象部门的雷电监测系统提供的。由于风力涡轮发电机的地理位置至关重要,在选址时,除对该地区的风能进行评估外,也要对该地区的雷电密度进行实时监测,必要时,应在选址范围内安装雷击大地密度监测系统,以获得更为准确的数据,为雷电风险评估提供科学的依据。下图3为雷电监测系统监测到的全国地闪监测密度分布图[3]。 当雷击大地密度无法确定时,可用下列公式进行估算: Ng=0.04×Td1.25 (2) 式中 Ng:每平方公里的雷击大地密度(次/km2?a); Td:年雷暴日,通常由当地气象台站提供的实时资料为准。 等效截收面Ae积定义为与风力涡轮发电机具有相同的年直接雷击次数的大地表面积。对于孤立风力涡轮发电机,等效截收面积是以一条斜率为1:3的直线,与叶片的顶部相接触,并绕塔筒旋转,直线与地面相交得出的边界线所包围的 大地面积。如图4是关于平地上孤立建筑物的等效截收面积计算方法: Ae=LW+6HL+W+9πH2 建议所有的风力涡轮发电机都简化成一个桅杆,其高度等于塔筒的高度加上叶片的半径。 图5是关于平地上风力涡轮发电机等效截收面积的计算方法。很清楚,它是以风力涡轮发电机高度三倍为半径的一个圆[4]。 下列方程用于计算平地上风力涡轮发电机的年雷击次数Nd,将公式(2)带入公式(1)得: Nd=0.04×Td1.25×9πH2×Cd×10-6 (3) =0.04×561.25×9×3.14×1202×1×10-6 =2.5次/a 式中 H:风力涡轮发电机的有效高度; 注:IEC61024-1-1给出了风力涡轮发电机在复杂地势下或接近其他建筑情况下等效面积的估算方法。 一旦我们对风力涡轮发电机的年雷击次数作出评估以后,我们将选择一个合适的防雷保护系统。失败的防雷保护系统会造成严重的事件,如果防雷保护系统的失败对人的生命安全构成威胁,那么可接受的雷击事故的数量应该由国家或地方法规和相关的监管机构来确定。如果雷击造成的损失仅仅是经济问题的话,那么,可接受的雷击事故的数量则由风力涡轮发电机的所有者来确定。 可接受的雷击事故的数量Nc与建筑物的用途、位置、结构和其内部人员数量、特定的时间有关系。 IEC61024-1-1声明可接受的雷击事故的数量(Nc)必须大于或等于建筑物的年预计雷击次数(Nd)与1减去防雷保护系统保护效率E的乘积。对于风力涡轮发电机即 Nc?Nd(1-E) (4) 式中 E:防雷保护系统的效能; Nd:建筑物年平均预计雷击次数; Nc:年预计可接受的事故数量; 防雷保护系统的保护效率是由两个独立的效率相乘得到的,一个是保护系统的拦截效率(拦截雷电的能力),一个是传导效率(将雷电流泄放的能力)。这个概念由IEC6124-1提出。因此,防雷保护系统的最低保护效率可由下面的公式确定: E?1-Nc/Nd5 对于可接受的雷击损坏风险(Nc)是一个不确定的值,每个国家或风力涡轮发电机的所有者可以根据不同的要求自行拟定。 IEC62305-2则规定可承受的风险表现在雷电引起人的死亡或社会、文化价值的损失。并列举了代表性值[5]:如人员死亡:10-5,为大众服务的公共设计的损失:10-3,文化遗产的损失:10-3。 而希腊 标准 excel标准偏差excel标准偏差函数exl标准差函数国标检验抽样标准表免费下载红头文件格式标准下载 化组织给出的NC值是5×10-5(对风力涡轮发电机)[6]。美国给出的值是10-5,对于没有人员伤亡的情况下,NC值是10-3[4]。我国GB50057-94(2000版) 则规定可接受的最大雷击次数Nc按下式确定[7]: Nc=10-5/PrWr 对于风力涡轮发电机PrWr取8?10-4,经计算,Nc=1.2?10-2。该值也可以由风力涡轮发电机的所有者提供。 通过上述的计算,我们已经能够得出可接受的雷击次数NC与年预计雷击次数Nd,然后对其比较,当NdNC时,应该按照下列表格确定防护等级,并根据相应的防护等级采取相应的防护措施。 IEC61024-1将防雷保护系统划分为四个等级,从等级?到等级?,下面的表格是防雷保护效率E与防护等级划分的关系,当已知NC和Nd时我们就可以利用公式(5)求出相应的保护效率。 保护等级 拦截效率(E1) 传导效率E2 效率E ? 0.99 0.99 0.98 ? 0.97 0.98 0.95 ? 0.91 0.97 0.90 ? 0.84 0.97 0.80 从上面表格可以看出,当E>0.98时,保护等级为?,带附加的防护措施。 0.95 设计规范 民用建筑抗震设计规范配电网设计规范10kv变电所设计规范220kv变电站通用竖流式沉淀池设计 》[S] 中国 计划 项目进度计划表范例计划下载计划下载计划下载课程教学计划下载 出版社 [8] 风力发电机组规范2008[s] 中国船级社 Wind turbine lightning risk assessment methods and solutions LUO Jia-jun Tianjin Lightning protection Technology Center, TianJin 300074 ZHANG Xiao-shi FengShun Bureau of Meteorology, Guangdong 514300 Abstract: This paper discusses the wind turbine lightning risk assessment methods, through the method we get the lightning protection system levels for the wind turbine. Based on the level of protection level, put forward the protection solution of direct lightning flash which used the theory of traditional air gap arrester and the principle of common earthing system but non-collinear, and bring forward new train of thought for the protection of wind turbine Keywords: Risk assessment;Improving methods;Protection measures; 附 作者简介 附 作者简介 罗佳俊(1984?)男,山西长治人,技术员,毕业于广东海洋大学,主要从事防雷 工程设计等工作。 张小石(1980-)男,新疆吉木萨尔县人,助理工程师,毕业于成都信息工程学 院(原成都气象学院),主要从事建筑物防雷装置检测验收、雷电灾害调查等工作。 罗佳俊:天津市河西区气象台路98号 天津市防雷技术中心邮编300074电话 邮箱:tjfanglei@yahoo 张小石:广东省丰顺县汤坑镇气象路41号丰顺县气象局 邮编:514300 电话: 邮箱:fsfls@yahoo Editor's note: Judson Jones is a meteorologist, journalist and photographer. He has freelanced with CNN for four years, covering severe weather from tornadoes to typhoons. Follow him on Twitter: @jnjonesjr CNN -- I will always wonder what it was like to huddle around a shortwave radio and through the crackling static from space hear the faint beeps of the world's first satellite -- Sputnik. I also missed watching Neil Armstrong step foot on the moon and the first space shuttle take off for the stars. Those events were way before my time. As a kid, I was fascinated with what goes on in the sky, and when NASA pulled the plug on the shuttle program I was heartbroken. Yet the privatized space race has renewed my childhood dreams to reach for the stars. As a meteorologist, I've still seen many important weather and space events, but right now, if you were sitting next to me, you'd hear my foot tapping rapidly under my desk. I'm anxious for the next one: a space capsule hanging from a crane in the New Mexico desert. It's like the set for a George Lucas movie floating to the edge of space. You and I will have the chance to watch a man take a leap into an unimaginable free fall from the edge of space -- live. The lack of air up there Watch man jump from 96,000 feet Tuesday, I sat at work glued to the live stream of the Red Bull Stratos Mission. I watched the balloons positioned at different altitudes in the sky to test the winds, knowing that if they would just line up in a vertical straight line "we" would be go for launch. I feel this mission was created for me because I am also a journalist and a photographer, but above all I live for taking a leap of faith -- the feeling of pushing the envelope into uncharted territory. The guy who is going to do this, Felix Baumgartner, must have that same feeling, at a level I will never reach. However, it did not stop me from feeling his pain when a gust of swirling wind kicked up and twisted the partially filled balloon that would take him to the upper end of our atmosphere. As soon as the 40-acre balloon, with skin no thicker than a dry cleaning bag, scraped the ground I knew it was over. How claustrophobia almost grounded supersonic skydiver With each twist, you could see the wrinkles of disappointment on the face of the current record holder and "capcom" capsule communications, Col. Joe Kittinger. He hung his head low in mission control as he told Baumgartner the disappointing news: Mission aborted. The supersonic descent could happen as early as Sunday. The weather plays an important role in this mission. Starting at the ground, conditions have to be very calm -- winds less than 2 mph, with no precipitation or humidity and limited cloud cover. The balloon, with capsule attached, will move through the lower level of the atmosphere the troposphere where our day-to-day weather lives. It will climb higher than the tip of Mount Everest 5.5 miles/8.85 kilometers, drifting even higher than the cruising altitude of commercial airliners 5.6 miles/9.17 kilometers and into the stratosphere. As he crosses the boundary layer called the tropopause, he can expect a lot of turbulence. The balloon will slowly drift to the edge of space at 120,000 feet 22.7 miles/36.53 kilometers. Here, "Fearless Felix" will unclip. He will roll back the door. Then, I would assume, he will slowly step out onto something resembling an Olympic diving platform. Below, the Earth becomes the concrete bottom of a swimming pool that he wants to land on, but not too hard. Still, he'll be traveling fast, so despite the distance, it will not be like diving into the deep end of a pool. It will be like he is diving into the shallow end. Skydiver preps for the big jump When he jumps, he is expected to reach the speed of sound -- 690 mph 1,110 kph -- in less than 40 seconds. Like hitting the top of the water, he will begin to slow as he approaches the more dense air closer to Earth. But this will not be enough to stop him completely. If he goes too fast or spins out of control, he has a stabilization parachute that can be deployed to slow him down. His team hopes it's not needed. Instead, he plans to deploy his 270-square-foot 25-square-meter main chute at an altitude of around 5,000 feet 1,524 meters. In order to deploy this chute successfully, he will have to slow to 172 mph 277 kph. He will have a reserve parachute that will open automatically if he loses consciousness at mach speeds. Even if everything goes as planned, it won't. Baumgartner still will free fall at a speed that would cause you and me to pass out, and no parachute is guaranteed to work higher than 25,000 feet 7,620 meters. It might not be the moon, but Kittinger free fell from 102,800 feet in 1960 -- at the dawn of an infamous space race that captured the hearts of many. Baumgartner will attempt to break that record, a feat that boggles the mind. This is one of those monumental moments I will always remember, because there is no way I'd miss this.