标题 | 生态机组不同布置形式过渡过程研究 |
范文 | 赵修龙等 摘要:在一些已建的大中型水电站中,为了保护水电站下游生态环境,需要在原引水管道中通过岔管分出一条引水管道以保证下游所需生态流量。可通过在引水管道中安装生态机组,来利用生态流量发电。生态机组的布置可分为两种形式:室后分叉、室前分叉。前一种布置形式中,由于两台机组的引水管道共用调压室,使得生态机组与原系统大机组之间相互的水力干扰较大,原机组负荷变化对生态机组的影响大于生态机组对原机组的影响;后一种布置形式中,两台机组拥有独立调压室,各自独立运行,相互之间水力干扰很小。 关键词:生态机组;生态流量;布置形式;过渡过程;水力干扰;岔管;调压室 中图分类号:TV732.4 文献标志码:A 文章编号: 16721683(2014)05001103 Study on transient process of different arrangement forms of ecological unit ZHAO Xiulong,ZHANG Jian,HE Lu (College of water Conservancy and Hydropower Engineering,Hohai University,Nanjing 210098,China) Abstract:In some constructed large and medium hydropower stations,in order to protect the ecological environment of downstream,a new water pipeline is usually developed through the fork tube to ensure the downstream ecological flow.An ecological unit can be installed in the new water pipeline to generate electricity.There are two arrangement forms for the ecological unit:fork tube located behind the surge tank and in front of the surge tank.For the first arrangement form,the two units share the same surge tank,resulting in large hydraulic disturbance between the ecological unit and original unit.The load change of the original unit can have greater impact on the ecological unit than that of the ecological one on the original one.For the latter arrangement form,each unit has its own surge tank,resulting in insignificant hydraulic disturbance between the two units.The two units can operate independently. Key words:ecological unit;ecological flow;arrangement form;transient process;hydraulic disturbance;fork tube;surge tank 生态流量是为保障河流环境生态功能,维持水资源可持续开发利用,避免发生生态环境恶化所必须保证的下游河道最小流量[2],是保证河流所需要的自净扩散能力,不因流量及水流形态发生巨大变化而造成水体污染,维持下游河道内水生生物的生存和水生态系统的固有平衡,保证下游沿岸居民生活取水、农业生产取水等基本需求[3]。许多水利枢纽工程项目在建设初期尚未要求进行生态流量论证[4],设计施工时也未考虑建设生态流量泄放口设施,来满足下游河段生态和景观基本要求[5]。但是,许多电站在经过技术论证后在原引水系统中增加了一条引水道以保证下游所需生态流量[6]。同时,为了充分利用生态流量,还在新增的引水道末端扩建一个小出力生态机组,在大机组停机时段实施生态机组放水发电[7]。生态机组的布置形式可分为两种,即室后分叉和室前分叉。已有研究表明,不同的布置形式对生态机组以及原系统大机组过渡过程的影响不同[8],相同布置形式下,生态机组与原系统大机组之间相互的水力干扰程度也不一样[9],因而,研究生态机组不同布置形式对系统过渡过程的影响具有实际意义。 1 数学模型 描述任意管道中的水流运动状态的基本方程为 连续方程: 由表2、图4可以看出:在室后分叉布置形式下生态机组蜗壳末端最大压力值和转速最大上升率均大于室前布置形式下的相应的值,并且两种布置形式下生态机组蜗壳末端压力和转速上升率变化过程线差别较大。由此可知,不同布置形式下,原机组对生态机组蜗壳末端压力和转速上升率的影响较大,并且室前分叉布置下水力过渡过程优于室后布置。 通过上述两种不同布置形式下生态机组以及原机组蜗壳末端压力和转速上升率的比较可知:不论是生态机组还是原机组,方案二中机组蜗壳末端压力和转速上升率均小于方案一。这是因为方案二中两台机组处于各自的引水管道中,机组增减负荷产生的水锤压力均被各自所在引水管道中的调压室吸收,相互之间影响很小;而方案二中两台机共用一个调压室,一台机增减负荷产生的水锤压力以及流量变化会通过调压室传递给另外一台机,因而相互之间影响较大。 在方案一中两台机组之间的影响差别较大,生态机组对原机组蜗壳末端压力和转速上升率的影响几乎可以忽略,而原机组对生态机组的影响较大,甚至会使得生态机组的蜗壳末端压力和转速上升率增至接近甚至超过调保计算控制值。这是因为生态机组与原机组的额定出力相差较大。当两台机同时甩负荷时,生态机组产生的水锤压力以及流量变化与原机组相比可以忽略,因而其对原机组的蜗壳末端压力和转速上升率影响很小,相反原机组产生的水锤压力以及流量变化对于生态机组而言接近甚至超过生态机组本身的相应值,因而其对生态机组蜗壳末端压力和转速上升率影响很大。 3 结语 本文结合工程实例,探讨了生态机组不同布置形式对两台机组蜗壳末端压力和转速上升率的影响,以及两台机组相互之间的影响,结果表明:室前分叉布置形式下两台机组蜗壳末端压力和转速上升率均小于室后分叉布置形式,即室前分叉布置形式过渡过程优于室后分叉布置形式。在室后分叉布置形式下,两台机组之间的相互影响差别较大,生态机组对原机组蜗壳末端压力和转速上升率的影响几乎可以忽略,而原机组对生态机组的影响较大,甚至会使得生态机组的蜗壳末端压力和转速上升率上升至接近甚至超过调保计算控制标准。上述结论对实际电站中新增的生态机组在布置形式选择以及与原机组之间的相互影响的判定上具有借鉴意义。 参考文献(References): [1] 禹金彪,黄玉然,高水生.大龙潭水电站扩建小机组释放生态流量[J].环境科学与技术,2012,35(6I):330332.(YU Jinbiao,HUANG Yuran,GAO Shuisheng.Dalongtan hydraulic power station to release ecological flow by expanding small units[J].Environmental Science & Technology,2012,35(6I):330332.(in Chinese)) [2] 周世良.浅谈“生态流量”[J].福建环境,2000(2):23.(ZHOU Shiliang.A brief talk of ecologic flow[J].Fujian Environment,2000(2):23.(in Chinese)) [3] 朱蒙恩.水电站生态流量及再利用[J].硅谷,2012(19):29.(ZHU Menen.Ecological flow and reuse in hydropower[J].Silicon Valley.2012(19):29.(in Chinese)) [4] 汪秀丽.河流生态流量浅论[J].水利电力科技,2007(1):2029.(WANG Xiuli.A brief talk on the river ecosystem flow[J].Water Resources and Electric Power.2007(1):2029.(in Chinese)) [5] 杜强,谭红武,张士杰,等.生态流量保障与小机组泄放方式的现状及问题[J].中国水能及电气化,2012(12):16.(DU Qiang,TAN Hongwu,ZHANG Shijie,et al.Status and problems of ecological flow protection and small unit bleeder mode[J].China Water Power & Electrifi cation.2012(12):16.(in Chinese)) [6] 施彬,牛文彬,田迅.生态流量水电站水轮发电机组选型中应注意的几个问题[J].水力发电,2012(1):8183.(SHI Bin,NIU Wenbin,TIAN Xun.Issues on turbinegenerator selection for ecological power stations[J].Water Power.2012(1):8183.(in Chinese)) [7] 魏浪,陈国柱.善泥坡水电站生态流量的确定及其保障措施[J].贵州水力发电,2007(1):1114.(WEI Lang CHEN Guozhu.Flow determine and safeguards of shannipo station[J].Guizhou Water Power.2007(1):1114.(in Chinese)) [8] 李玺,郑源,张丽敏,等.水电站小机组过渡过程对大机组的影响[J].人民黄河,2011(3):125126.(LI Xi,ZHENG Yuan,ZHANG Liming,et al.Impact of the transition process of small units on large units in hydropower station[J].Yellow River.2011(3):125126.(in Chinese)) [9] 丁景焕,杨建东.水电站水力干扰稳定性研究[J].小水电,2007(1):1214.(DING Jinhuan,YANG Jiandong.Study on hydraulic interference stability in hydropower station[J].Small Hydro Power.2007(1):1214.(in Chinese)) [10] 彭小东,葛静,李刚.浅析某水电站生态机组选型设计[J].四川水利,2011(1):2527.(PENG Xiaodong,GE Jing,LI Gang.A brief study on the ecological unit selection and design of a hydropower[J].Sichuan Water Conservancy.2011(1):2527.(in Chinese)) [11] 孙显春,龚兰强,魏浪,等.马马崖一级水电站生态流量保证措施设计与研究[J].贵州水力发电,2012(2):3841.(SUN Xianchun,GONG Lanqiang,WEI Lang,et al.Ecological flow assurance measures design and research on mama cliff hydropower station[J].Guizhou Water Power.2012(2):3841.(in Chinese)) [12] Wylie E B,Streetr V L,Suo Lisheng.Fluid transient in systems[M].Englewood Cliffs,Prentice Hall,1993. 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