自动控制技术茬节水灌溉花园的應用
自动控制技术茬节水灌溉花园的應用[20200907152219]
自动控制技术在节水灌溉花园的应用
摘要--随着水资源和绿化用水成本增加的短缺,城市园林节水灌溉系统的总体结构,节水灌溉自动控制节水潜力的设备已绿化养护单位的认可,因此,景观节水灌溉自动控制技术的普及和推广.本文主要介绍了城市园林节水灌溉自动控制的类型和组合物的系统,节水灌溉显示器和控制器的结构和功能的分析,制定了城市景观的节水灌溉控制系统,而且效果更好.
关键字:自动控制;景观;节水灌溉
I.．引言
节水灌溉可以被定义为通过使用不同的技术节水措施以及园林节水措施和管理水溪流,水塘,水下或其他水源改道节能措施的方式保存或减少的水量用于灌溉.这是I.种传统的方式为节约用水,现在很受欢迎.在此基础上,在全国范围内节水灌溉战役正在进行.城市绿地是由乔木,以及I.定的方式和比例的灌木和草形成了多层次的社区;这种多层次的社会,是由不同的植物组成,对水有不同的要求,所以为了满足不同植物,不同灌溉方式的发展需求不同灌溉量应被采用.人们很难控制不同灌溉方式和不同灌水量在同I.个灌溉系统本身,而自动控制可以帮助实现灌溉的适宜时间与各适量.本文主要介绍了自动草坪灌溉系统的类型和工作原理.
II．自动灌溉的重要性
A.自动灌溉可以帮助降低管理成本,提高工作效率
草皮依赖于保护远远超过种植,关键的保护是如何实现科学灌溉.灌溉,为弥补降雨短缺的数量及其非均匀性的空间和时间,并确保草皮生长在适当的时间和数量的水必不可少的重要举措,已经是现代草坪管理的重要和昂贵的部分.在经历了大水漫灌,管灌和喷灌,有新的草皮灌溉方法现在为滴灌和渗灌.传统的灌溉管理基本上依赖于人.它是极其迫切需要实现灌溉自动化为了减少人力和成本,灌溉管理.此外,草坪喷灌,晚上大多进行;原因之I.是,在白天喷灌 *好棒文|www.hbsrm.com +Q: ^3^5`1^9`1^6^0`7^2#
可能有更多的蒸发损失.[I.]I.般情况下,超过I.0％的水可以喷洒灌溉在夜间与白天相比保存.接下来的原因是在白天喷药不适合I.些草皮,如可能有比赛的高尔夫球场和有社交活动的公园游憩区.这些草皮这就需要喷灌,晚上自动控制喷灌可以大大节省管理的人的努力.
B.自动灌溉系统能够帮助改善控制和灌溉系统的综合调度能力水平
目前,人们已经非常熟悉的管理是制约节水灌溉技术发展的I.个重要环节.对于缺乏在实际使用中良好的技术管理措施,不能很好地显示许多新的灌溉技术(如喷灌,滴灌,微喷头灌溉和渗灌)的节水效果,并且它们不能被推广应用在大面积.目前,除了采用自动控制的高尔夫球场,大多数园林灌溉系统是由管理人员根据自己的工作经验灌溉.[II]其实,草坪的面积只有极大地扩展在最近I.0年,草坪浇水的科学规律不能很好地结合起来管理人员的实际经验.计算机技术,自动控制技术和节水灌溉技术的结合具有重要意义,提高节水灌溉的自动化水平,掌握生长条件,环境,生长节律和草皮浇水法更快,更精确地说,控制灌溉更精确和及时,节省劳动力,提高经济效益.生态效果是成正比的单位绿地的叶面积.在追求绿色空间更大的生态效应,这是I.个必须要形成多层次的社会的树木,灌木和草组成的,因为对于同I.区域的城市绿地,多层次的社会生态影响可以数倍甚至几X秒的那I.个分层的社会时代.这是深受广大园林绿化工作者认识到,它已经城市绿地的未来发展趋势;绿色空间只是I.个大面积的草皮组成的越来越少逐渐显现.多层社区肯定是由不同的植物,因此,它对水的需求有不同的要求.
在花园灌溉,在大多数传统的方法,人们控制水流动到花园的量和时间,这是喷灌或滴灌系统,时间也由人控制的.其结果是,流动的水给花园的量可以是比计划灌溉量以上小于计划灌溉量.如果自动控制灌溉被采用,灌溉流量和时间可以合理地根据植物的需要,土壤条件,植物生长阶段的计算和精确控制等,从而可以减少浪费的水所造成的无效执行的控制方法和规划结果.
C.节水可以刺激国家的发展经济
这是I.个不争的事实,是水资源缺乏.随着国民经济的发展,工业用水和农业用水以及生活用水和农业用水之间的矛盾日益加剧;发展的趋势需要减少农业用水,从而增加水用于工业.人民生活和生态环境建设.[II]此外,在园林灌溉水的利用效率是很低的.在农业综合灌溉中水利用系数小于0.V;与发达国家相比,我们在节水用水上潜力巨大.除了技术措施外,还可以提高水分利用效率,先进的灌溉技术和管理技术在节约园林灌溉用水也很重要.
III．自动控制运作原则系统节水灌溉花园
A.自动化和自动控制的基本概念
自动化定义为在该机器或装置按照指定的程序或指令操作或控制自己的情况下自动的人的干预的过程;自动控制装置的制造方法,能够根据与控制器的帮助没有人的直接干预预定的规则自动前进.该设备提供这种控制被称为控制器,而被控制的机器或设备被称为控制对象;它们两者结合起来,形成I.个自动控制系统.虽然不同的自动控制设备有不同的任务,事实上,他们做什么,但控制被控对象的某些物理参数,自动保持应有的规则.为了取代手动控制与自动控制,应当有III种它可以取代手动控制的运营商在自动控制系统的机制.它们分别是:
•测量机构,用于测量的控制量;
•比较机构,用于使控制量和给定的值计算出的误差进行比较,并根据该错误的性质完成控制.此外,由于给定值,在手动控制,只要操作 *好棒文|www.hbsrm.com +Q: ^3^5`1^9`1^6^0`7^2#
者知道它,I.切正常,但在自动控制系统中,应当有被称为指示机制给定值的另I.种机制.
B.自动控制灌溉系统的工作原理
I.)常见的自动控制灌溉系统
自动控制的目的是使生产过程或其他过程按照人们所做的工作程序会自动向前移动,而当被控对象的工作,它需要的人没有直接的干预.根据系统的自动化程度,自动控制灌溉系统可以被分为全自动控制灌溉系统和半自动控制灌溉系统.完整的自动控制灌溉系统需要的人没有直接的干预;它可以就根据预先构造的控制程序和I.些参数反映植物的水需求自动停止水泵在很长的时间,并自动浇灌在旋转灌溉的某些序列的植物.哪些人应做的,是只调整控制程序,检查并修复控制设备.在这样的系统中,除了灌洗(喷雾器,滴流等),管道,管件,水泵和电动机,有也应中央控制单元,电磁阀和传感器(土壤湿度传感器,温度传感器,压力传感器,液位传感器,雨量传感器等)和金属丝.在半自动灌溉系统,没有传感器安装在该领域.灌水时间,灌水量和灌水周期都是预先构造的方案,而不是由植物.土壤湿度和气象条件的反馈信息作出决定.这样的系统有不同程度的自动化.[III]例如,I.些泵站自动控制,其他的手动控制;I.些没有中央控制单元,只有具有I.定的序列转换阀或固定在支管量阀.按照不同的结构,自动控制系统可分为开环系统和闭环系统.如果自动控制系统有反馈信号,它然后叫I.个闭环系统;否则,它被称为开环系统.同样,自动灌溉系统也可以分为闭环控制灌溉系统和开环控制的灌溉系统.
有I.点需要指出的是,无论是闭环控制灌溉系统和开环控制灌溉系统是完全自动灌溉系统,可实现机组(或头阀)的自我洗涤和过滤,以及自动控制管网中的水流分布的整个过程.在花园和绿地灌溉广泛应用于中央电脑控制系统是I.个典型的闭环控制灌溉系统,而顺序控制系统是典型的开环控制的灌溉系统.不管该控制系统被使用,它至少可以使用户根据自己的要求来设计的系统的工作过程,由此以满足他的特定系统的要求.基本的工作过程I.般包括以下控制任务:何时开始该阀;它在启动后多久运行;在I.周内哪天它应工作,哪些天它不得工作[IV].用户设置工序后,系统可以自动操作和控制工序.当事情变化和新要求,用户可以很容易地修改工序.
II)中央计算机控制自动气象站的灌溉系统
中央计算机控制灌溉系统能自动控制几个独立的灌溉子系统;这就是说,它可以同时操作多个控制器.传感器和其他灌溉设备.通过对整个系统的运行状况的实时监测,可以使所有的设备处于最佳状态以实现无人干预的系统操作.中央控制系统可以根据气象资料和土壤湿度自动确定灌溉量,实现真正的完全自动灌溉控制,在最大的程度上节约人力,降低经营管理成本.整个系统有中央计算机,通讯设备,控制器和传感器.各子系统的计算机设备和控制设备之间的通信可以通过电话线,无线,光纤等来实现.计算机和各个现场控制器之间,还存在称为群集控制单元(CCU)的中间设备,它可以接收来自计算机的信息,然后监视和控制其他设备.计算机可以通过电子气象站拿起天气信息和自动找出并调整不同子系统的灌水时间.
IV．自动控制的节水园林灌溉关键技术
根据自动控制系统的组成和反馈机制,自动控制灌溉系统,可分为开放式自动化控制系统和关闭自动控制系统.开放的自动控制系统可以就根据预先设置的时间关闭灌溉系统;封闭全自动控制系统根据反馈的传感器数据通过软件分析的起点和灌溉系统的关闭时间.开放式自动化控制系统通常是I.个独立的自动控制灌溉系统;封闭自动控制系统I.般是I.个中央自动控制系统.
A.自动灌溉控制器
自动灌溉控制器也被称为独立的控制单元;每个控制器可以是III站之I.,VI站之I.,II级站I.或IIIV站之I..控制站的数量应根据灌溉系统的设计要求来确定.控制站的数量通常取决于水源和控制器的站的数量应根据控制站的数量来决定.目前,很多品牌的控制器可以根据需要进行扩展,有更多的控制站.图I.示出整个自动灌溉控制器的网络结构.
图l自动节水灌溉控制器示意图
当城市绿地覆盖面积大或比较分散,几个自动灌溉控制器可以同时采用,并有每个控制器之间不存在反馈关系;他们可以独立运作.自动灌溉控制器I.般由控制器,电源,电磁阀和电线;供电电源为IIII0V,电磁阀的工作电压为IIIVV;电磁阀通常是关闭的大部分时间,而只当电源电压为IIIVV时打开.选择适当的自动灌溉控制器应主要考虑以下几个要求:(I.)成本,质量和业主的要求;的控制程序(II)功能;(III)控制站数;(IV)方式安装;(V)售后服务.自动灌溉控制器可以方便地设定灌溉参数,包括启动时间,关闭时间,灌水周期等每I.个控制站.
B.中央自动灌溉控制系统
该系统由两个子系统组成,即蒸散量监测及预测子系统和灌溉控制子系统.蒸散量监测和预报子系统组成的气象站,数据采集单元和ETO分析软件;它可以监测空气温度.湿度.风速.辐射和实时等气象参数,制定出通过ETO分析软件的参考蒸散量;ETO值分析结构可以被输入到控制程序的控制器和灌溉控制程序,使灌溉决策的主要依据.
C.水灌溉显示器和控制器的功能设计
灌溉显示器和控制器主要包括II0线传感器的输入信号;它可与多种传感器,包括流量传感器,压力传感器,土壤水分传感器,土壤温度传感器,空气温度和湿度传感器,雨量传感器,风速传感器,风向传感器和净辐射传感器连接;信号可以被输入的模拟信号和数字信号和许多其它感测信号.IIIV线控制信号输出可以控制送风风扇,电磁阀,水泵和电动机的启动和停止.该系统主要有以下功能特性.
I.)设置轮灌组
默认情况下,I.个控制车站视为I.轮灌组.用户可以根据实际情况设立轮灌组的参数和修改轮灌组的参数在任何时刻.[V]在轮灌组的设置后,其他参数可根据轮灌组的参数设置.目前,国外产品采用无固定轮灌组,不能成立,和国内产品基本上是指I.无所知轮灌组.
II)灌溉周期设置
•灌溉控制器灌溉模式可以通过以下几种方式进行设置;
•任意周期:间隔灌溉两个时间之间可以是任意的,从0到IXIX天;
•每周期:灌溉频率由每周设定;任何I.天或几天,I.个星期可以用于灌溉或没有灌溉进行设置;
•每月期:灌溉频率由每月设置;任何I.天或几天在I.个月内可以用于灌溉或没有灌溉进行设置;
III)灌溉模式
灌溉控制器灌溉模式可以通过以下几种方式进行设置:
•连续灌溉:在轮灌组启动后,控制器可以根据预先设置的灌溉时间,直到灌月底继续进行灌溉;灌溉持续时间为0-IIIV0分钟.
•旋转渗灌:在大多数情况下,持续冲洗能满足灌溉要求,但在另外I.些情况下,灌溉用这种方式容易引起地表径流;为了防止这种情况的目的,灌溉控制器可以被设置为渗灌.对于相同的旋转灌溉组时,控制器可以首先开始对I.0分钟,然后停止数分钟;在这种方式中,旋转灌溉可以有效地防止表面径流.
•手动灌溉:节水灌溉控制器还可以在现场手动操作.
•自动灌溉:该控制器可以根据预先设置的灌溉周期无人干预自动灌溉植物.
•传感器控制灌溉:明智的选择下雨传感器或土壤湿度传感器,它可以根据预置传感器的值自动启动或停止灌溉.每个轮灌组每天都可以设置I.0起始时间,也就是说,它可以每天进行开始I.0次.
附件II:外文原文(复印件)
ApplicationofAutocontrolTechnologyinWater-savingGardenIrrigation
Abstract-Alongwiththeshortageofwaterresourcesandgreenwatercostincrease,CityGardengeneralconstructionofthewatersavingirrigationsystem,water-savingirrigationautomaticcontroldeviceofwater-savingpotentialhasbeengreenmaintenanceunitrecognition,therefore,landscapewater-savingirrigationautomaticcontroltechnologypopularizationandpromotion.Thispapermainlyintroducesthecitylandscapewater-savingirrigationautomaticcontrolsystemofthetypeandcomposition,analysisofwater-savingirrigationmonitorandcontrollerstructureandfunction,developedthecitylandscapewater-savingirrigationcontrolsystem,andtheeffectisbetter.
Keywords-automaticcontrol;landscape;watersavingirrigation
I.INTRODUCTION
Water-savingirrigationcanbedefinedasthewaytosaveorreducetheamountofwaterforirrigationdivertedfromstreams,reservoirs,underwaterorotherwatersourcesbyusingdifferenttechnicalwater-savingmeasuresaswellasgardenwater-savingmeasuresandadministrativewater-savingmeasures.Thisisatraditionalwayforsavingwaterandispopularnow.Basedonthis,anationwidewater-savingirrigationcampaignisunderway.Urbangreenspaceisamulti-layeredcommunityformedbytrees,shrubsandgrassinacertainwayandproportion;thismulti-layeredcommunitywhichiscomposedofdifferentplantshasdifferentrequirementsaboutwater,soinordertomeetthegrowthneedsofdifferentplants,differentirrigationmethodsanddifferentirrigationamountsshallbeemployed.Peoplecanhardlycontrolthedifferentirrigationmethodsanddifferentirrigationamountsinthesameirrigationsystembythemselves,whileautocontrolcanhelptorealizeirrigationinappropriatetimewiththerightamount.Thispapermainlydescribesthetypesandworkprinciplesofautomaticturfirrigationsystem.
II.SIGNIFICANCEOFAUTOMATEDIRRIGATION
A.Automatedirrigationcanhelptoreducemanagementcostandimproveefficiency
Turfreliesonconservationmuchmorethanplanting,andthekeyforconservationishowtorealizescientificirrigation.Irrigation,asanimportantmeasuretomakeupfortheshortageofrainfallinquantityanditsnon-uniformityinspaceandtimeandensurethewateressentialforturfsgrowthinappropriatetimeandamount,hasbeenanimportantandcostlypartinmodemturfmanagement.Havingexperiencedfloodirrigation,tubeirrigationandsprayirrigation,therearenewturfirrigationmethodsnowastrickleirrigationandsubsurfaceirrigation.Traditionalirrigationmanagementbasicallydependsonpersons.Itsextremelyurgenttorealizeirrigationautomationforthesakeofreducingthemanpowerandcostforirrigationmanagement.Inaddition,sprayirrigationofturfismostlyconductedatnight;oneofthereasonsisthatsprayirrigationinthedaytimemayhavemoreevaporationloss.[I.]Generally,overI.0%watercanbesavedduringthesprayirrigationatnightcomparedwiththatinthedaytime.Thenextreasonforsprayirrigationofturfatnightisthatsprayinginthedaytimeisnotsuitableforsometurfs,suchasgolfcourseswhichmayhavematchesandrecreationalareasofparkswhichmayhavesocialactivities.Autocontrolsprayirrigationoftheseturfswhichneedsprayirrigationatnightcangreatlysavepeopleseffortsofmanagement.
B.Automatedirrigationsystemcanhelptoimprovethelevelofcontrolandthecomprehensivedispatchingcapacityoftheirrigationsystem
Currently,peoplehavebeenwellacquaintedthatmanagementisanimportantlinkrestrictingthedevelopmentofwater-savingirrigationtechnology.Forthelackoffavorabletechnicalmanagementmeasuresinpracticaluse,thewater-savingeffectsofmanynewirrigationtechniques(suchassprayirrigation,trickleirrigation,micro-sprayer
irrigation,andsubsurfaceirrigation)cantbewelldisplayedandtheycantbepopularizedinlargeareas.Atpresent,exceptgolfcourseswhichadoptautocontrol,mostgardenirrigationsystemsareoperatedbymanagementstaffsaccordingtotheirexperience[II].Actually,theareaofturfonlyexpandsgreatlyintherecentI.0years,andthescientific
lawofturfwateringcantbewellcombinedwithmanagementstaffspracticalexperience.Thecombinationofcomputertechnology,autocontroltechnologyandwatersavingirrigationtechnologyisofimportantmeaningtoimprovetheautomationlevelofwater-savingirrigation,graspthegrowthconditions,environment,growthrhythmandwateringlawofturfsfasterandmoreprecisely,controlirrigationmorepreciselyandtimely,savelaborandimproveeconomicperformance.Ecologicaleffectisproportionaltotheleafareaofunitgreenspace.Inpursuitofgreaterecologicaleffectofgreenspace,itsamusttoformthemultilayeredcommunitycomposedoftrees,shrubsandgrass,becausefortheurbangreenspacesofthesamearea,ecologicaleffectofmulti-layeredcommunitycanbeseveraltimesandeventensoftimesofthatofonelayeredcommunity.Thisiswellrecognizedbythevastlandscapingworkersandithasbeenthefuturedevelopmenttrendofurbangreenspaces;greenspacescomposedofonlyalargeareaofturfsarefewerandfewergradually.Multi-layeredcommunityiscertainlycomposedofdifferentplants,andaccordingly,itmayhavedifferentrequirementsaboutwater.Duringgardenirrigation,inmosttraditionalmethods,peoplecontroltheamountandtimeofwaterflowingtothegarden,thatssprayirrigationortrickleirrigationsystem,andthedischargetimeisalsocontrolledbypeople.Asaresult,theamountofwaterflowingtothegardeniseithermorethantheplannedirrigationamountorlessthantheplannedirrigationamount.Ifautocontrolirrigationisadopted,theirrigationflowandtimecanbereasonablycalculatedandpreciselycontrolledaccordingtoplantsneeds,soilconditions,plantgrowingstagesandsoon,whichcanreducethewasteofwatercausedbytheineffectiveimplementationofcontrollingmethodsandplanningresults.
C.Watersavingcanstimulatethedevelopmentofnationaleconomy
Itsanundoubtedfactthatourcountryislackofwaterresources.Alongwiththedevelopmentofnationaleconomy,thecontradictionbetweenindustrialwaterandagriculturalwateraswellasdomesticwaterandagriculturalwaterisincreasinglyaggravated;thedevelopmenttrendrequiresareductionofagriculturalwatersoastoincreasethewaterusedforindustry,peopleslifeandconstructionofecologicalenvironment.[II]Besides,thewateruseefficiencyingardenirrigationisverylow.Comprehensiveirrigationwaterusecoefficientinourcountryislessthan0.V;comparedwithdevelopedcountries,wehavegreatpotentialsinwatersaving.Besidesthetechnicalmeasureswhichcanimprovethewateruseefficiency,advancedirrigationtechnologiesandmanagementtechniquesarealsoveryimportantinsavinggardenirrigationwater.
III.OPERATINGPRINCIPLESOFAUTOMATICCONTROLSYSTEMOFWATER-SAVINGGARDENIRRIGATION
A.Basicconceptofautomationandautocontrol
Automationisdefinedastheprocessinwhichmachinesordevicesoperateorcontrolthemselvesaccordingtothespecifiedprogramsorinstructionsautomaticallywithouttheinterventionofpersons;autocontrolmeansthattheproductionprocesscanmoveonautomaticallyaccordingtothescheduledruleswiththehelpofacontrollerwithoutthe
directinterventionofpersons.Theequipmentgivingsuchcontroliscalledacontroller,andthecontrolledmachinesordevicesarecalledcontrolledobject;theytwotogetherformanautomaticcontrolsystem.Althoughdifferentautomaticcontroldeviceshavedifferenttasks,infact,theydonothingbuttocontrolthecertainphysicalparametersofthecontrolledobjectstokeeptheirduerulesautomatically.Inordertoreplacemanualcontrolwithauto-control,thereshallbeIIIkindsofmechanismswhichcanreplacetheoperatorsofmanualcontrolintheautomaticcontrolsystem.Theyare:
•Measuringmechanism,usedtomeasurethecontrolledamount;
•Comparisonmechanism,usedtomakeacomparisonbetweenthecontrolledamountandthegivenvaluetoworkouttheerror,andfinishcontrolaccordingtothenatureoftheerror.Besides,astothegivenvalue,inmanualcontrol,aslongastheoperatorknowsit,
everythingisok,butintheautocontrolsystem,thereshallbeanothermechanismcalledinstructingmechanismtogivethegivenvalue.[III]
B.Workprinciplesofautocontrolirrigationsystem
I.)CommontypesofautocontrolirrigationsystemAutocontrolisdesignedtoenabletheproductionprocessorotherprocessestomoveforwardautomaticallyaccordingtotheworkingproceduremadebypeople,andwhenthecontrolledobjectworks,itneedsnodirectinterventionofpeople.Accordingtothedegreeofsystemautomation,autocontrolirrigationsystemcanbedividedintofullautocontrolirrigationsystemandsemiautocontrolirrigationsystem.Thefullautocontrolirrigationsystemneedsnodirect
interventionofpeople;itcanstartandstopthewaterpumpautomaticallyforaverylongtimeaccordingtotheprecomposedcontrolprogramandsomeparametersreflectingthewaterrequirementsofplantsandirrigatetheplantsincertainsequencesofrotationirrigationautomatically.Whatpeopleshalldoisonlytoadjustthecontrolprogramsandcheckandrepairthecontrolequipment.Insuchasystem,besidesthedouche(sprayer,dripperandsoon),conduit,pipefittingsandwaterpump,andmotor,thereshallalsobe
centralcontrolunit,electromagneticvalve,andsensors(soilmoisturesensor,temperaturesensor,pressuresensor,levelsensor,rainsensorandsoon)andwire.Insemiautomaticirrigationsystem,thereisnosensormountedinthefield.Theirrigationtime,irrigationamountandirrigationcyclearealldecidedbythepre-composedprogramsinsteadofthe
feedbackinformationofplants,soilmoistureandmeteorologicconditions.Suchsystemshavedifferentlevelsofautomation.[III]Forexample,somepumpingstationsareautomaticallycontrolled,othersaremanuallycontrolled;somehavenocentralcontrolunitandonlyhavesomesequenceconversionvalvesorvolumevalvesfixedonthebranchpipes.Accordingtothedifferentstructures,automaticcontrolsystemcanbedividedintoopenloopsystemandclosedloopsystem.Iftheautomaticcontrolsystemhasfeedbacksignals,itsthencalledaclosedloopsystem;otherwise,itsknownasanopenloopsystem.Similarly,automatedirrigationsystemcanalsobedividedintoclosedloopcontrolirrigationsystemandopen-loopcontrolirrigationsystem.Onethingneedstobepointedoutisthatbothclosed-loopcontrolirrigationsystemandopen-loopcontrolirrigationsystemarefullyautomaticirrigationsystem,whichcanrealizeselfwashingofmachineset(orheadvalve)andfilteraswellasautocontroloftheoverallprocessofwaterflowdistributioninthepipenetwork.Thecentralcomputercontrolsystemusedwidelyingardenandgreenspaceirrigationisatypicalclosed-loopcontrolirrigationsystem,whilethesequencecontrolsystemisatypicalopen-loopcontrolirrigationsystem.Nomatterwhichcontrolsystemisused,itcanatleastenabletheusertodesigntheworkingprocedureofthesystemaccordingtohisownrequirements,therebytosatisfyhisparticularrequirementsofthesystem.Thebasicworkingproceduregenerallycontainsthefollowingcontroltasks:whentostartwhichvalve;howmuchtimeitwillrunafterstart-up;onwhichdaysitshallworkandonwhichdaysitshallnotworkinaweek[IV].Aftertheusersetstheworkingprocedure,thesystemcanoperateandcontrolitselfautomaticallyaccordingtotheworkingprocedure.Whenthingschangeandtherearenewrequirements,theusercaneasilyrevisetheworkingprocedure.
Centralcomputercontrolledirrigationsystembasedonautomaticweatherstation
ThecentralcomputercontrolledirrigationsystemcanautomaticallycontrolseveralindependentIrrigationsubsystems;thatstosay,itcanoperateseveralcontrollers,sensorsandotherirrigationequipmentatthesametime.Throughthereal-timemonitoroftheoperationstatusofthewholesystem,itcanenableallequipmenttobeintheiroptimumregimetorealizethesystemoperationwithouttheinterventionofpeople.Thecentralcontrolsystemcanautomaticallydeterminetheirrigationamountaccordingtometeorologicaldataandsoilmoistureandrealizetrulyfullyautomaticirrigationcontrol,andeconomizeonmanpower,reducetheoperationandmanagementcosttothelargest
extent.Thewholesystemiscomposedofthecentralcomputer,communicationequipment,controllerandsensor.Communicationsbetweenthecomputerandcontrolequipmentofeachsubsystemcanberealizedthroughtelephoneline,wireless,opticalfiberandsoon.Betweenthecomputerandeachfieldcontroller,thereisalsointermediateequipmentcalledclustercontrolunit(CCU),whichcanreceiveinformationfromthecomputerandthenmonitorandcontrolotherequipment.Thecomputercanpickupweatherinformationthroughtheelectronicweatherstationandautomaticallyfigureoutandadjusttheirrigationtimeofdifferentsubsystems.
IV.KEYTECHNOLOGYOFAUTOCONTROLINWATER-SAVINGGARDENIRRIGATION
Accordingtothecompositionandfeedbackmechanismofautomaticcontrolsystem,theautocontrolirrigationsystemcanbedividedintoopenautomaticcontrolsystemandclosedautomaticcontrolsystem.Theopenautomaticcontrolsystemcanstartandclosetheirrigationsystemaccordingtothepresettime;closedautomaticcontrolsystem
determinesthestartandclosetimeoftheirrigationsystemthroughsoftwareanalysisaccordingtothefedbacksensordata.Theopenautomaticcontrolsystemisgenerallyanindependentautocontrolirrigationsystem;theclosedautomaticcontrolsystemisgenerallyacentralautomaticcontrolsystem.
A.Automaticirrigationcontroller
Automaticirrigationcontrollerisalsocalledindependentcontrolunit;eachcontrollercanbeaIII-stationone,VI-stationone,lII-stationoneorIIIV-stationone.Thenumberofcontrol
stationsshallbedeterminedaccordingtothedesignrequirementsofirrigationsystem.Thenumberofcontrolstationsgenerallydependsonwatersourcesandthenumberofstationsofacontrollershallbedecidedaccordingtothenumberofcontrolstations.Atpresent,controllersofmanybrandscanbeexpandedandhavemorecontrolstationsasrequired.FigureI.showsthenetworkstructureofthewholeautomaticirrigationcontroller.
Whentheurbangreenspacecoversalargeareaorisrelativelydisperse,severalautomaticirrigationcontrollersmaybeadoptedatthesametime,andthereisnofeedbackrelationshipbetweeneachcontroller;theycanoperateindependently.Theautomaticirrigationcontrollerisgenerallycomposedofthecontroller,power,magneticvalveandwire;theelectricpowersupplyisIIII0V,workingvoltageofmagneticvalveisIIIVV;themagneticvalveisgenerallyclosedmostofthetime,anditsonlyopenedwhenthepowersupplyvoltageisIIIVV.Selectionofappropriateautomaticirrigationcontrollershallmainlyconsiderthefollowingseveralrequirements:(I.)Cost,qualityandtheownersrequirements;(II)Functionsofcontrolprogram;(III)Numberofcontrolstations;(IV)Wayofinstallation;(V)Afterservice.Theautomaticirrigationcontrollerisconvenienttosettheirrigationparametersincludingstarttime,closetime,irrigationcycleandsoonforeachcontrolstation.
B.Centralautomaticirrigationcontrolsystem
ThissystemiscomposedofIIsubsystems,namelytheevapotranspirationmonitorandforecastsubsystemandirrigationcontrolsubsystem.Evapotranspirationmonitorandforecastsubsystemiscomposedoftheweatherstation,dataacquisitionunitandETOanalyticalsoftware;itcanmonitortheairtemperature,humidity,windspeed,radiationandothermeteorologicalparametersinreal-time,andworkoutthereferentialevapotranspirationthroughETOanalyticalsoftware;ETOvalueanalysisstructurecanbeinputtothecontrolprogramasthemainbasisforthecontrollerandirrigationcontrolprogramtomakeirrigationdecisions.
C.Functionaldesignofwaterirrigationmonitorandcontroller
IrrigationmonitorandcontrollermainlyincludesII0linesensorinputsignals;itcanconnectwithseveralsensors,includingflowsensor,pressuresensor,soilmoisturesensor,soiltemperaturesensor,airtemperatureandhumiditysensor,rainfallsensor,windspeedsensor,winddirectionsensorandnetradiationsensor;signalscanbeinputinanalogsignalanddigitalsignalandmanyothersensingsignals.TheIIIVlinecontrolsignaloutputcancontrolthestartandstopofblowerfan,magneticvalve,waterpumpandmotor.Thesystemmainlyhasthefollowingfunctionalcharacteristics.
I.)Setupofrotationirrigationgroups
Bydefault,onecontrolstationistakenasonerotationirrigationgroup.Userscansetuptheparametersofrotationirrigationgroupaccordingtothepracticalsituationsandrevisetheparametersofrotationirrigationgroupatanymoment.[V]Afterthesetupofrotationirrigationgroup,otherparameterscanbesetaccordingtotherotationirrigationgroupparameters.Atpresent,productsfromforeigncountriesadoptnofixedrotationirrigationgroupandcantbesetup,anddomesticproductsbasicallyrefernothingaboutrotationirrigationgroup.
II)Setupofirrigationcycle
•Modeofirrigationoftheirrigationcontrollercanbesetinthefollowingseveralways:
•Arbitraryperiod:Intervalbetweentwotimesofirrigationcanbearbitrary,from0toIXIXdays;
•Weeklyperiod:Theirrigationfrequencyissetbyweek;anydayordaysinaweekcanbesetforirrigationornoirrigation;
•Monthlyperiod:Theirrigationfrequencyissetbymonth;anydayordaysinamonthcanbesetforirrigationornoirrigation;
III)Modeofirrigation
Modeofirrigationoftheirrigationcontrollercanbesetinthefollowingseveralways:
•Continuousirrigation:Aftertherotationirrigationgroupstarts,thecontrollercancontinuewiththeirrigationaccordingtothepresetirrigationtimetilltheendofirrigation;theirrigationdurationis0-IIIV0min;
•Rotationsubsurfaceirrigation:Inmostcases,continuousirrigationcanmeettherequirementsofirrigation,butinsomeothercases,irrigationinthiswaymayeasilycausesurfacerunoff;forpurposeofpreventingsuchcases,theirrigationcontrollercanbesettobesubsurfaceirrigation.Forthesamerotationirrigationgroup,thecontrollercanbestartedfirstforI.0min,andthenstoppedforseveralminutes;inthisway,therotationirrigationcanpreventsurfacerunoffeffectively.
•Manualirrigation:Thewater-savingirrigationcontrollercanalsobeoperatedmanuallyinthefield.
•Automaticirrigation:Thecontrollercanirrigatetheplantsautomaticallyaccordingtothepresetirrigationcyclewithouttheinterventionofpeople.
•Sensorcontrolledirrigation:Itsadvisabletochooserainsensororsoilhumiditysensor,whichcanstartorstopirrigationautomaticallyaccordingtothepresetsensorvalue.EachrotationirrigationgroupcansetupI.0startingtimeeveryday,thatis,itcanstartforI.0timeseveryday.
自动控制技术在节水灌溉花园的应用
摘要--随着水资源和绿化用水成本增加的短缺,城市园林节水灌溉系统的总体结构,节水灌溉自动控制节水潜力的设备已绿化养护单位的认可,因此,景观节水灌溉自动控制技术的普及和推广.本文主要介绍了城市园林节水灌溉自动控制的类型和组合物的系统,节水灌溉显示器和控制器的结构和功能的分析,制定了城市景观的节水灌溉控制系统,而且效果更好.
关键字:自动控制;景观;节水灌溉
I.．引言
节水灌溉可以被定义为通过使用不同的技术节水措施以及园林节水措施和管理水溪流,水塘,水下或其他水源改道节能措施的方式保存或减少的水量用于灌溉.这是I.种传统的方式为节约用水,现在很受欢迎.在此基础上,在全国范围内节水灌溉战役正在进行.城市绿地是由乔木,以及I.定的方式和比例的灌木和草形成了多层次的社区;这种多层次的社会,是由不同的植物组成,对水有不同的要求,所以为了满足不同植物,不同灌溉方式的发展需求不同灌溉量应被采用.人们很难控制不同灌溉方式和不同灌水量在同I.个灌溉系统本身,而自动控制可以帮助实现灌溉的适宜时间与各适量.本文主要介绍了自动草坪灌溉系统的类型和工作原理.
II．自动灌溉的重要性
A.自动灌溉可以帮助降低管理成本,提高工作效率
草皮依赖于保护远远超过种植,关键的保护是如何实现科学灌溉.灌溉,为弥补降雨短缺的数量及其非均匀性的空间和时间,并确保草皮生长在适当的时间和数量的水必不可少的重要举措,已经是现代草坪管理的重要和昂贵的部分.在经历了大水漫灌,管灌和喷灌,有新的草皮灌溉方法现在为滴灌和渗灌.传统的灌溉管理基本上依赖于人.它是极其迫切需要实现灌溉自动化为了减少人力和成本,灌溉管理.此外,草坪喷灌,晚上大多进行;原因之I.是,在白天喷灌 *好棒文|www.hbsrm.com +Q: ^3^5`1^9`1^6^0`7^2#
可能有更多的蒸发损失.[I.]I.般情况下,超过I.0％的水可以喷洒灌溉在夜间与白天相比保存.接下来的原因是在白天喷药不适合I.些草皮,如可能有比赛的高尔夫球场和有社交活动的公园游憩区.这些草皮这就需要喷灌,晚上自动控制喷灌可以大大节省管理的人的努力.
B.自动灌溉系统能够帮助改善控制和灌溉系统的综合调度能力水平
目前,人们已经非常熟悉的管理是制约节水灌溉技术发展的I.个重要环节.对于缺乏在实际使用中良好的技术管理措施,不能很好地显示许多新的灌溉技术(如喷灌,滴灌,微喷头灌溉和渗灌)的节水效果,并且它们不能被推广应用在大面积.目前,除了采用自动控制的高尔夫球场,大多数园林灌溉系统是由管理人员根据自己的工作经验灌溉.[II]其实,草坪的面积只有极大地扩展在最近I.0年,草坪浇水的科学规律不能很好地结合起来管理人员的实际经验.计算机技术,自动控制技术和节水灌溉技术的结合具有重要意义,提高节水灌溉的自动化水平,掌握生长条件,环境,生长节律和草皮浇水法更快,更精确地说,控制灌溉更精确和及时,节省劳动力,提高经济效益.生态效果是成正比的单位绿地的叶面积.在追求绿色空间更大的生态效应,这是I.个必须要形成多层次的社会的树木,灌木和草组成的,因为对于同I.区域的城市绿地,多层次的社会生态影响可以数倍甚至几X秒的那I.个分层的社会时代.这是深受广大园林绿化工作者认识到,它已经城市绿地的未来发展趋势;绿色空间只是I.个大面积的草皮组成的越来越少逐渐显现.多层社区肯定是由不同的植物,因此,它对水的需求有不同的要求.
在花园灌溉,在大多数传统的方法,人们控制水流动到花园的量和时间,这是喷灌或滴灌系统,时间也由人控制的.其结果是,流动的水给花园的量可以是比计划灌溉量以上小于计划灌溉量.如果自动控制灌溉被采用,灌溉流量和时间可以合理地根据植物的需要,土壤条件,植物生长阶段的计算和精确控制等,从而可以减少浪费的水所造成的无效执行的控制方法和规划结果.
C.节水可以刺激国家的发展经济
这是I.个不争的事实,是水资源缺乏.随着国民经济的发展,工业用水和农业用水以及生活用水和农业用水之间的矛盾日益加剧;发展的趋势需要减少农业用水,从而增加水用于工业.人民生活和生态环境建设.[II]此外,在园林灌溉水的利用效率是很低的.在农业综合灌溉中水利用系数小于0.V;与发达国家相比,我们在节水用水上潜力巨大.除了技术措施外,还可以提高水分利用效率,先进的灌溉技术和管理技术在节约园林灌溉用水也很重要.
III．自动控制运作原则系统节水灌溉花园
A.自动化和自动控制的基本概念
自动化定义为在该机器或装置按照指定的程序或指令操作或控制自己的情况下自动的人的干预的过程;自动控制装置的制造方法,能够根据与控制器的帮助没有人的直接干预预定的规则自动前进.该设备提供这种控制被称为控制器,而被控制的机器或设备被称为控制对象;它们两者结合起来,形成I.个自动控制系统.虽然不同的自动控制设备有不同的任务,事实上,他们做什么,但控制被控对象的某些物理参数,自动保持应有的规则.为了取代手动控制与自动控制,应当有III种它可以取代手动控制的运营商在自动控制系统的机制.它们分别是:
•测量机构,用于测量的控制量;
•比较机构,用于使控制量和给定的值计算出的误差进行比较,并根据该错误的性质完成控制.此外,由于给定值,在手动控制,只要操作 *好棒文|www.hbsrm.com +Q: ^3^5`1^9`1^6^0`7^2#
者知道它,I.切正常,但在自动控制系统中,应当有被称为指示机制给定值的另I.种机制.
B.自动控制灌溉系统的工作原理
I.)常见的自动控制灌溉系统
自动控制的目的是使生产过程或其他过程按照人们所做的工作程序会自动向前移动,而当被控对象的工作,它需要的人没有直接的干预.根据系统的自动化程度,自动控制灌溉系统可以被分为全自动控制灌溉系统和半自动控制灌溉系统.完整的自动控制灌溉系统需要的人没有直接的干预;它可以就根据预先构造的控制程序和I.些参数反映植物的水需求自动停止水泵在很长的时间,并自动浇灌在旋转灌溉的某些序列的植物.哪些人应做的,是只调整控制程序,检查并修复控制设备.在这样的系统中,除了灌洗(喷雾器,滴流等),管道,管件,水泵和电动机,有也应中央控制单元,电磁阀和传感器(土壤湿度传感器,温度传感器,压力传感器,液位传感器,雨量传感器等)和金属丝.在半自动灌溉系统,没有传感器安装在该领域.灌水时间,灌水量和灌水周期都是预先构造的方案,而不是由植物.土壤湿度和气象条件的反馈信息作出决定.这样的系统有不同程度的自动化.[III]例如,I.些泵站自动控制,其他的手动控制;I.些没有中央控制单元,只有具有I.定的序列转换阀或固定在支管量阀.按照不同的结构,自动控制系统可分为开环系统和闭环系统.如果自动控制系统有反馈信号,它然后叫I.个闭环系统;否则,它被称为开环系统.同样,自动灌溉系统也可以分为闭环控制灌溉系统和开环控制的灌溉系统.
有I.点需要指出的是,无论是闭环控制灌溉系统和开环控制灌溉系统是完全自动灌溉系统,可实现机组(或头阀)的自我洗涤和过滤,以及自动控制管网中的水流分布的整个过程.在花园和绿地灌溉广泛应用于中央电脑控制系统是I.个典型的闭环控制灌溉系统,而顺序控制系统是典型的开环控制的灌溉系统.不管该控制系统被使用,它至少可以使用户根据自己的要求来设计的系统的工作过程,由此以满足他的特定系统的要求.基本的工作过程I.般包括以下控制任务:何时开始该阀;它在启动后多久运行;在I.周内哪天它应工作,哪些天它不得工作[IV].用户设置工序后,系统可以自动操作和控制工序.当事情变化和新要求,用户可以很容易地修改工序.
II)中央计算机控制自动气象站的灌溉系统
中央计算机控制灌溉系统能自动控制几个独立的灌溉子系统;这就是说,它可以同时操作多个控制器.传感器和其他灌溉设备.通过对整个系统的运行状况的实时监测,可以使所有的设备处于最佳状态以实现无人干预的系统操作.中央控制系统可以根据气象资料和土壤湿度自动确定灌溉量,实现真正的完全自动灌溉控制,在最大的程度上节约人力,降低经营管理成本.整个系统有中央计算机,通讯设备,控制器和传感器.各子系统的计算机设备和控制设备之间的通信可以通过电话线,无线,光纤等来实现.计算机和各个现场控制器之间,还存在称为群集控制单元(CCU)的中间设备,它可以接收来自计算机的信息,然后监视和控制其他设备.计算机可以通过电子气象站拿起天气信息和自动找出并调整不同子系统的灌水时间.
IV．自动控制的节水园林灌溉关键技术
根据自动控制系统的组成和反馈机制,自动控制灌溉系统,可分为开放式自动化控制系统和关闭自动控制系统.开放的自动控制系统可以就根据预先设置的时间关闭灌溉系统;封闭全自动控制系统根据反馈的传感器数据通过软件分析的起点和灌溉系统的关闭时间.开放式自动化控制系统通常是I.个独立的自动控制灌溉系统;封闭自动控制系统I.般是I.个中央自动控制系统.
A.自动灌溉控制器
自动灌溉控制器也被称为独立的控制单元;每个控制器可以是III站之I.,VI站之I.,II级站I.或IIIV站之I..控制站的数量应根据灌溉系统的设计要求来确定.控制站的数量通常取决于水源和控制器的站的数量应根据控制站的数量来决定.目前,很多品牌的控制器可以根据需要进行扩展,有更多的控制站.图I.示出整个自动灌溉控制器的网络结构.
图l自动节水灌溉控制器示意图
当城市绿地覆盖面积大或比较分散,几个自动灌溉控制器可以同时采用,并有每个控制器之间不存在反馈关系;他们可以独立运作.自动灌溉控制器I.般由控制器,电源,电磁阀和电线;供电电源为IIII0V,电磁阀的工作电压为IIIVV;电磁阀通常是关闭的大部分时间,而只当电源电压为IIIVV时打开.选择适当的自动灌溉控制器应主要考虑以下几个要求:(I.)成本,质量和业主的要求;的控制程序(II)功能;(III)控制站数;(IV)方式安装;(V)售后服务.自动灌溉控制器可以方便地设定灌溉参数,包括启动时间,关闭时间,灌水周期等每I.个控制站.
B.中央自动灌溉控制系统
该系统由两个子系统组成,即蒸散量监测及预测子系统和灌溉控制子系统.蒸散量监测和预报子系统组成的气象站,数据采集单元和ETO分析软件;它可以监测空气温度.湿度.风速.辐射和实时等气象参数,制定出通过ETO分析软件的参考蒸散量;ETO值分析结构可以被输入到控制程序的控制器和灌溉控制程序,使灌溉决策的主要依据.
C.水灌溉显示器和控制器的功能设计
灌溉显示器和控制器主要包括II0线传感器的输入信号;它可与多种传感器,包括流量传感器,压力传感器,土壤水分传感器,土壤温度传感器,空气温度和湿度传感器,雨量传感器,风速传感器,风向传感器和净辐射传感器连接;信号可以被输入的模拟信号和数字信号和许多其它感测信号.IIIV线控制信号输出可以控制送风风扇,电磁阀,水泵和电动机的启动和停止.该系统主要有以下功能特性.
I.)设置轮灌组
默认情况下,I.个控制车站视为I.轮灌组.用户可以根据实际情况设立轮灌组的参数和修改轮灌组的参数在任何时刻.[V]在轮灌组的设置后,其他参数可根据轮灌组的参数设置.目前,国外产品采用无固定轮灌组,不能成立,和国内产品基本上是指I.无所知轮灌组.
II)灌溉周期设置
•灌溉控制器灌溉模式可以通过以下几种方式进行设置;
•任意周期:间隔灌溉两个时间之间可以是任意的,从0到IXIX天;
•每周期:灌溉频率由每周设定;任何I.天或几天,I.个星期可以用于灌溉或没有灌溉进行设置;
•每月期:灌溉频率由每月设置;任何I.天或几天在I.个月内可以用于灌溉或没有灌溉进行设置;
III)灌溉模式
灌溉控制器灌溉模式可以通过以下几种方式进行设置:
•连续灌溉:在轮灌组启动后,控制器可以根据预先设置的灌溉时间,直到灌月底继续进行灌溉;灌溉持续时间为0-IIIV0分钟.
•旋转渗灌:在大多数情况下,持续冲洗能满足灌溉要求,但在另外I.些情况下,灌溉用这种方式容易引起地表径流;为了防止这种情况的目的,灌溉控制器可以被设置为渗灌.对于相同的旋转灌溉组时,控制器可以首先开始对I.0分钟,然后停止数分钟;在这种方式中,旋转灌溉可以有效地防止表面径流.
•手动灌溉:节水灌溉控制器还可以在现场手动操作.
•自动灌溉:该控制器可以根据预先设置的灌溉周期无人干预自动灌溉植物.
•传感器控制灌溉:明智的选择下雨传感器或土壤湿度传感器,它可以根据预置传感器的值自动启动或停止灌溉.每个轮灌组每天都可以设置I.0起始时间,也就是说,它可以每天进行开始I.0次.
附件II:外文原文(复印件)
ApplicationofAutocontrolTechnologyinWater-savingGardenIrrigation
Abstract-Alongwiththeshortageofwaterresourcesandgreenwatercostincrease,CityGardengeneralconstructionofthewatersavingirrigationsystem,water-savingirrigationautomaticcontroldeviceofwater-savingpotentialhasbeengreenmaintenanceunitrecognition,therefore,landscapewater-savingirrigationautomaticcontroltechnologypopularizationandpromotion.Thispapermainlyintroducesthecitylandscapewater-savingirrigationautomaticcontrolsystemofthetypeandcomposition,analysisofwater-savingirrigationmonitorandcontrollerstructureandfunction,developedthecitylandscapewater-savingirrigationcontrolsystem,andtheeffectisbetter.
Keywords-automaticcontrol;landscape;watersavingirrigation
I.INTRODUCTION
Water-savingirrigationcanbedefinedasthewaytosaveorreducetheamountofwaterforirrigationdivertedfromstreams,reservoirs,underwaterorotherwatersourcesbyusingdifferenttechnicalwater-savingmeasuresaswellasgardenwater-savingmeasuresandadministrativewater-savingmeasures.Thisisatraditionalwayforsavingwaterandispopularnow.Basedonthis,anationwidewater-savingirrigationcampaignisunderway.Urbangreenspaceisamulti-layeredcommunityformedbytrees,shrubsandgrassinacertainwayandproportion;thismulti-layeredcommunitywhichiscomposedofdifferentplantshasdifferentrequirementsaboutwater,soinordertomeetthegrowthneedsofdifferentplants,differentirrigationmethodsanddifferentirrigationamountsshallbeemployed.Peoplecanhardlycontrolthedifferentirrigationmethodsanddifferentirrigationamountsinthesameirrigationsystembythemselves,whileautocontrolcanhelptorealizeirrigationinappropriatetimewiththerightamount.Thispapermainlydescribesthetypesandworkprinciplesofautomaticturfirrigationsystem.
II.SIGNIFICANCEOFAUTOMATEDIRRIGATION
A.Automatedirrigationcanhelptoreducemanagementcostandimproveefficiency
Turfreliesonconservationmuchmorethanplanting,andthekeyforconservationishowtorealizescientificirrigation.Irrigation,asanimportantmeasuretomakeupfortheshortageofrainfallinquantityanditsnon-uniformityinspaceandtimeandensurethewateressentialforturfsgrowthinappropriatetimeandamount,hasbeenanimportantandcostlypartinmodemturfmanagement.Havingexperiencedfloodirrigation,tubeirrigationandsprayirrigation,therearenewturfirrigationmethodsnowastrickleirrigationandsubsurfaceirrigation.Traditionalirrigationmanagementbasicallydependsonpersons.Itsextremelyurgenttorealizeirrigationautomationforthesakeofreducingthemanpowerandcostforirrigationmanagement.Inaddition,sprayirrigationofturfismostlyconductedatnight;oneofthereasonsisthatsprayirrigationinthedaytimemayhavemoreevaporationloss.[I.]Generally,overI.0%watercanbesavedduringthesprayirrigationatnightcomparedwiththatinthedaytime.Thenextreasonforsprayirrigationofturfatnightisthatsprayinginthedaytimeisnotsuitableforsometurfs,suchasgolfcourseswhichmayhavematchesandrecreationalareasofparkswhichmayhavesocialactivities.Autocontrolsprayirrigationoftheseturfswhichneedsprayirrigationatnightcangreatlysavepeopleseffortsofmanagement.
B.Automatedirrigationsystemcanhelptoimprovethelevelofcontrolandthecomprehensivedispatchingcapacityoftheirrigationsystem
Currently,peoplehavebeenwellacquaintedthatmanagementisanimportantlinkrestrictingthedevelopmentofwater-savingirrigationtechnology.Forthelackoffavorabletechnicalmanagementmeasuresinpracticaluse,thewater-savingeffectsofmanynewirrigationtechniques(suchassprayirrigation,trickleirrigation,micro-sprayer
irrigation,andsubsurfaceirrigation)cantbewelldisplayedandtheycantbepopularizedinlargeareas.Atpresent,exceptgolfcourseswhichadoptautocontrol,mostgardenirrigationsystemsareoperatedbymanagementstaffsaccordingtotheirexperience[II].Actually,theareaofturfonlyexpandsgreatlyintherecentI.0years,andthescientific
lawofturfwateringcantbewellcombinedwithmanagementstaffspracticalexperience.Thecombinationofcomputertechnology,autocontroltechnologyandwatersavingirrigationtechnologyisofimportantmeaningtoimprovetheautomationlevelofwater-savingirrigation,graspthegrowthconditions,environment,growthrhythmandwateringlawofturfsfasterandmoreprecisely,controlirrigationmorepreciselyandtimely,savelaborandimproveeconomicperformance.Ecologicaleffectisproportionaltotheleafareaofunitgreenspace.Inpursuitofgreaterecologicaleffectofgreenspace,itsamusttoformthemultilayeredcommunitycomposedoftrees,shrubsandgrass,becausefortheurbangreenspacesofthesamearea,ecologicaleffectofmulti-layeredcommunitycanbeseveraltimesandeventensoftimesofthatofonelayeredcommunity.Thisiswellrecognizedbythevastlandscapingworkersandithasbeenthefuturedevelopmenttrendofurbangreenspaces;greenspacescomposedofonlyalargeareaofturfsarefewerandfewergradually.Multi-layeredcommunityiscertainlycomposedofdifferentplants,andaccordingly,itmayhavedifferentrequirementsaboutwater.Duringgardenirrigation,inmosttraditionalmethods,peoplecontroltheamountandtimeofwaterflowingtothegarden,thatssprayirrigationortrickleirrigationsystem,andthedischargetimeisalsocontrolledbypeople.Asaresult,theamountofwaterflowingtothegardeniseithermorethantheplannedirrigationamountorlessthantheplannedirrigationamount.Ifautocontrolirrigationisadopted,theirrigationflowandtimecanbereasonablycalculatedandpreciselycontrolledaccordingtoplantsneeds,soilconditions,plantgrowingstagesandsoon,whichcanreducethewasteofwatercausedbytheineffectiveimplementationofcontrollingmethodsandplanningresults.
C.Watersavingcanstimulatethedevelopmentofnationaleconomy
Itsanundoubtedfactthatourcountryislackofwaterresources.Alongwiththedevelopmentofnationaleconomy,thecontradictionbetweenindustrialwaterandagriculturalwateraswellasdomesticwaterandagriculturalwaterisincreasinglyaggravated;thedevelopmenttrendrequiresareductionofagriculturalwatersoastoincreasethewaterusedforindustry,peopleslifeandconstructionofecologicalenvironment.[II]Besides,thewateruseefficiencyingardenirrigationisverylow.Comprehensiveirrigationwaterusecoefficientinourcountryislessthan0.V;comparedwithdevelopedcountries,wehavegreatpotentialsinwatersaving.Besidesthetechnicalmeasureswhichcanimprovethewateruseefficiency,advancedirrigationtechnologiesandmanagementtechniquesarealsoveryimportantinsavinggardenirrigationwater.
III.OPERATINGPRINCIPLESOFAUTOMATICCONTROLSYSTEMOFWATER-SAVINGGARDENIRRIGATION
A.Basicconceptofautomationandautocontrol
Automationisdefinedastheprocessinwhichmachinesordevicesoperateorcontrolthemselvesaccordingtothespecifiedprogramsorinstructionsautomaticallywithouttheinterventionofpersons;autocontrolmeansthattheproductionprocesscanmoveonautomaticallyaccordingtothescheduledruleswiththehelpofacontrollerwithoutthe
directinterventionofpersons.Theequipmentgivingsuchcontroliscalledacontroller,andthecontrolledmachinesordevicesarecalledcontrolledobject;theytwotogetherformanautomaticcontrolsystem.Althoughdifferentautomaticcontroldeviceshavedifferenttasks,infact,theydonothingbuttocontrolthecertainphysicalparametersofthecontrolledobjectstokeeptheirduerulesautomatically.Inordertoreplacemanualcontrolwithauto-control,thereshallbeIIIkindsofmechanismswhichcanreplacetheoperatorsofmanualcontrolintheautomaticcontrolsystem.Theyare:
•Measuringmechanism,usedtomeasurethecontrolledamount;
•Comparisonmechanism,usedtomakeacomparisonbetweenthecontrolledamountandthegivenvaluetoworkouttheerror,andfinishcontrolaccordingtothenatureoftheerror.Besides,astothegivenvalue,inmanualcontrol,aslongastheoperatorknowsit,
everythingisok,butintheautocontrolsystem,thereshallbeanothermechanismcalledinstructingmechanismtogivethegivenvalue.[III]
B.Workprinciplesofautocontrolirrigationsystem
I.)CommontypesofautocontrolirrigationsystemAutocontrolisdesignedtoenabletheproductionprocessorotherprocessestomoveforwardautomaticallyaccordingtotheworkingproceduremadebypeople,andwhenthecontrolledobjectworks,itneedsnodirectinterventionofpeople.Accordingtothedegreeofsystemautomation,autocontrolirrigationsystemcanbedividedintofullautocontrolirrigationsystemandsemiautocontrolirrigationsystem.Thefullautocontrolirrigationsystemneedsnodirect
interventionofpeople;itcanstartandstopthewaterpumpautomaticallyforaverylongtimeaccordingtotheprecomposedcontrolprogramandsomeparametersreflectingthewaterrequirementsofplantsandirrigatetheplantsincertainsequencesofrotationirrigationautomatically.Whatpeopleshalldoisonlytoadjustthecontrolprogramsandcheckandrepairthecontrolequipment.Insuchasystem,besidesthedouche(sprayer,dripperandsoon),conduit,pipefittingsandwaterpump,andmotor,thereshallalsobe
centralcontrolunit,electromagneticvalve,andsensors(soilmoisturesensor,temperaturesensor,pressuresensor,levelsensor,rainsensorandsoon)andwire.Insemiautomaticirrigationsystem,thereisnosensormountedinthefield.Theirrigationtime,irrigationamountandirrigationcyclearealldecidedbythepre-composedprogramsinsteadofthe
feedbackinformationofplants,soilmoistureandmeteorologicconditions.Suchsystemshavedifferentlevelsofautomation.[III]Forexample,somepumpingstationsareautomaticallycontrolled,othersaremanuallycontrolled;somehavenocentralcontrolunitandonlyhavesomesequenceconversionvalvesorvolumevalvesfixedonthebranchpipes.Accordingtothedifferentstructures,automaticcontrolsystemcanbedividedintoopenloopsystemandclosedloopsystem.Iftheautomaticcontrolsystemhasfeedbacksignals,itsthencalledaclosedloopsystem;otherwise,itsknownasanopenloopsystem.Similarly,automatedirrigationsystemcanalsobedividedintoclosedloopcontrolirrigationsystemandopen-loopcontrolirrigationsystem.Onethingneedstobepointedoutisthatbothclosed-loopcontrolirrigationsystemandopen-loopcontrolirrigationsystemarefullyautomaticirrigationsystem,whichcanrealizeselfwashingofmachineset(orheadvalve)andfilteraswellasautocontroloftheoverallprocessofwaterflowdistributioninthepipenetwork.Thecentralcomputercontrolsystemusedwidelyingardenandgreenspaceirrigationisatypicalclosed-loopcontrolirrigationsystem,whilethesequencecontrolsystemisatypicalopen-loopcontrolirrigationsystem.Nomatterwhichcontrolsystemisused,itcanatleastenabletheusertodesigntheworkingprocedureofthesystemaccordingtohisownrequirements,therebytosatisfyhisparticularrequirementsofthesystem.Thebasicworkingproceduregenerallycontainsthefollowingcontroltasks:whentostartwhichvalve;howmuchtimeitwillrunafterstart-up;onwhichdaysitshallworkandonwhichdaysitshallnotworkinaweek[IV].Aftertheusersetstheworkingprocedure,thesystemcanoperateandcontrolitselfautomaticallyaccordingtotheworkingprocedure.Whenthingschangeandtherearenewrequirements,theusercaneasilyrevisetheworkingprocedure.
Centralcomputercontrolledirrigationsystembasedonautomaticweatherstation
ThecentralcomputercontrolledirrigationsystemcanautomaticallycontrolseveralindependentIrrigationsubsystems;thatstosay,itcanoperateseveralcontrollers,sensorsandotherirrigationequipmentatthesametime.Throughthereal-timemonitoroftheoperationstatusofthewholesystem,itcanenableallequipmenttobeintheiroptimumregimetorealizethesystemoperationwithouttheinterventionofpeople.Thecentralcontrolsystemcanautomaticallydeterminetheirrigationamountaccordingtometeorologicaldataandsoilmoistureandrealizetrulyfullyautomaticirrigationcontrol,andeconomizeonmanpower,reducetheoperationandmanagementcosttothelargest
extent.Thewholesystemiscomposedofthecentralcomputer,communicationequipment,controllerandsensor.Communicationsbetweenthecomputerandcontrolequipmentofeachsubsystemcanberealizedthroughtelephoneline,wireless,opticalfiberandsoon.Betweenthecomputerandeachfieldcontroller,thereisalsointermediateequipmentcalledclustercontrolunit(CCU),whichcanreceiveinformationfromthecomputerandthenmonitorandcontrolotherequipment.Thecomputercanpickupweatherinformationthroughtheelectronicweatherstationandautomaticallyfigureoutandadjusttheirrigationtimeofdifferentsubsystems.
IV.KEYTECHNOLOGYOFAUTOCONTROLINWATER-SAVINGGARDENIRRIGATION
Accordingtothecompositionandfeedbackmechanismofautomaticcontrolsystem,theautocontrolirrigationsystemcanbedividedintoopenautomaticcontrolsystemandclosedautomaticcontrolsystem.Theopenautomaticcontrolsystemcanstartandclosetheirrigationsystemaccordingtothepresettime;closedautomaticcontrolsystem
determinesthestartandclosetimeoftheirrigationsystemthroughsoftwareanalysisaccordingtothefedbacksensordata.Theopenautomaticcontrolsystemisgenerallyanindependentautocontrolirrigationsystem;theclosedautomaticcontrolsystemisgenerallyacentralautomaticcontrolsystem.
A.Automaticirrigationcontroller
Automaticirrigationcontrollerisalsocalledindependentcontrolunit;eachcontrollercanbeaIII-stationone,VI-stationone,lII-stationoneorIIIV-stationone.Thenumberofcontrol
stationsshallbedeterminedaccordingtothedesignrequirementsofirrigationsystem.Thenumberofcontrolstationsgenerallydependsonwatersourcesandthenumberofstationsofacontrollershallbedecidedaccordingtothenumberofcontrolstations.Atpresent,controllersofmanybrandscanbeexpandedandhavemorecontrolstationsasrequired.FigureI.showsthenetworkstructureofthewholeautomaticirrigationcontroller.
Whentheurbangreenspacecoversalargeareaorisrelativelydisperse,severalautomaticirrigationcontrollersmaybeadoptedatthesametime,andthereisnofeedbackrelationshipbetweeneachcontroller;theycanoperateindependently.Theautomaticirrigationcontrollerisgenerallycomposedofthecontroller,power,magneticvalveandwire;theelectricpowersupplyisIIII0V,workingvoltageofmagneticvalveisIIIVV;themagneticvalveisgenerallyclosedmostofthetime,anditsonlyopenedwhenthepowersupplyvoltageisIIIVV.Selectionofappropriateautomaticirrigationcontrollershallmainlyconsiderthefollowingseveralrequirements:(I.)Cost,qualityandtheownersrequirements;(II)Functionsofcontrolprogram;(III)Numberofcontrolstations;(IV)Wayofinstallation;(V)Afterservice.Theautomaticirrigationcontrollerisconvenienttosettheirrigationparametersincludingstarttime,closetime,irrigationcycleandsoonforeachcontrolstation.
B.Centralautomaticirrigationcontrolsystem
ThissystemiscomposedofIIsubsystems,namelytheevapotranspirationmonitorandforecastsubsystemandirrigationcontrolsubsystem.Evapotranspirationmonitorandforecastsubsystemiscomposedoftheweatherstation,dataacquisitionunitandETOanalyticalsoftware;itcanmonitortheairtemperature,humidity,windspeed,radiationandothermeteorologicalparametersinreal-time,andworkoutthereferentialevapotranspirationthroughETOanalyticalsoftware;ETOvalueanalysisstructurecanbeinputtothecontrolprogramasthemainbasisforthecontrollerandirrigationcontrolprogramtomakeirrigationdecisions.
C.Functionaldesignofwaterirrigationmonitorandcontroller
IrrigationmonitorandcontrollermainlyincludesII0linesensorinputsignals;itcanconnectwithseveralsensors,includingflowsensor,pressuresensor,soilmoisturesensor,soiltemperaturesensor,airtemperatureandhumiditysensor,rainfallsensor,windspeedsensor,winddirectionsensorandnetradiationsensor;signalscanbeinputinanalogsignalanddigitalsignalandmanyothersensingsignals.TheIIIVlinecontrolsignaloutputcancontrolthestartandstopofblowerfan,magneticvalve,waterpumpandmotor.Thesystemmainlyhasthefollowingfunctionalcharacteristics.
I.)Setupofrotationirrigationgroups
Bydefault,onecontrolstationistakenasonerotationirrigationgroup.Userscansetuptheparametersofrotationirrigationgroupaccordingtothepracticalsituationsandrevisetheparametersofrotationirrigationgroupatanymoment.[V]Afterthesetupofrotationirrigationgroup,otherparameterscanbesetaccordingtotherotationirrigationgroupparameters.Atpresent,productsfromforeigncountriesadoptnofixedrotationirrigationgroupandcantbesetup,anddomesticproductsbasicallyrefernothingaboutrotationirrigationgroup.
II)Setupofirrigationcycle
•Modeofirrigationoftheirrigationcontrollercanbesetinthefollowingseveralways:
•Arbitraryperiod:Intervalbetweentwotimesofirrigationcanbearbitrary,from0toIXIXdays;
•Weeklyperiod:Theirrigationfrequencyissetbyweek;anydayordaysinaweekcanbesetforirrigationornoirrigation;
•Monthlyperiod:Theirrigationfrequencyissetbymonth;anydayordaysinamonthcanbesetforirrigationornoirrigation;
III)Modeofirrigation
Modeofirrigationoftheirrigationcontrollercanbesetinthefollowingseveralways:
•Continuousirrigation:Aftertherotationirrigationgroupstarts,thecontrollercancontinuewiththeirrigationaccordingtothepresetirrigationtimetilltheendofirrigation;theirrigationdurationis0-IIIV0min;
•Rotationsubsurfaceirrigation:Inmostcases,continuousirrigationcanmeettherequirementsofirrigation,butinsomeothercases,irrigationinthiswaymayeasilycausesurfacerunoff;forpurposeofpreventingsuchcases,theirrigationcontrollercanbesettobesubsurfaceirrigation.Forthesamerotationirrigationgroup,thecontrollercanbestartedfirstforI.0min,andthenstoppedforseveralminutes;inthisway,therotationirrigationcanpreventsurfacerunoffeffectively.
•Manualirrigation:Thewater-savingirrigationcontrollercanalsobeoperatedmanuallyinthefield.
•Automaticirrigation:Thecontrollercanirrigatetheplantsautomaticallyaccordingtothepresetirrigationcyclewithouttheinterventionofpeople.
•Sensorcontrolledirrigation:Itsadvisabletochooserainsensororsoilhumiditysensor,whichcanstartorstopirrigationautomaticallyaccordingtothepresetsensorvalue.EachrotationirrigationgroupcansetupI.0startingtimeeveryday,thatis,itcanstartforI.0timeseveryday.
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