Scada sistemi yardımıyla su getirme hatlarının optimum işletimi

Abstract

Büyük bir şehrin su dağıtımı tek elden, merkezden idare edildiği takdirde daha kontrollü ve istenilen bir şekilde yapılabilir. Bu çalışmada su dağıtım sistemlerinde Denetlemeli Kontrol ve Veri Edinme (SCADA : Supervisory Control And Data Acquisition) sisteminin uygulaması incelenmiştir. SCADA'nın avantajları, felsefesi, alt sistem ve enstrümanları tanıtılmış, arıza ve erken uyarım halleri ve sistem elemanlarının ömrü üzerinde SCADA'nın fonksiyonları anlatılmıştır. Kurulan bir matematik model yardımı vana sistemlerinin simulasyonu yapılmış, tartışılmıştır. ile depo-boru- çeşitli durum- SCADA uygulamalarının sistemdeki depo hacimlerine etkisi analitik ve grafik yollarla incelenirken, otoma tik kontrol vanalarının bu hacimler üzerinde nasıl etkili olabileceği kurulan matematik model yardımıyla da belirlenmiştir. SCADA'nın su getirme hatları üzerindeki bazı ele manları nasıl etkilediği incelendikten sonra pompa is tasyonlarının işletilmesindeki alternatifler tartışılmış ve birkaç yöntem son bölümde Büyükçekmece Hamsu Pompa İstasyonuna uygulanmıştır. Son bölümde SCADA'nın İstanbul Büyük şehir Belediyesi İstanbul Su ve Kanalizasyon idaresi İSKİ'nin B. çekmece - Bahçelievler su getirme hattının mevcut problemleri incelendikten sonra, SCADA'nın buraya uygulanması ile optimum işletimi ve bu uygulamaların yararı gösterilmiştir.

Today's administrations who are responsible for the daily distribution of millions of metercubes of potable water and serve millions of users choose to monitor and remotely control their water resources, main distribution lines, lake, dam and reservoirs levels in continuous and uninterruptible ways. This can only be achieved by supplying the vital data to one control center for enabling the operators to generate the necessary commands to operate the system in requested state. Evaluation of the total flow amount in pipeline can be regarded as an example: If the amount exceeds the limits then a decision of reducing the opening of a valve on the same line might be generated and can be driven by the necessary operational actions in control center. Within the context of a water supply SCADA system besides the monitoring and the control of the distribution lines any fault, breakage or power failure can be detected and any necessary actions taken immediately. In addition the water demands from the different parts of city may be examined in more detail and the whole water distribution network can be rum with the highest efficiency. Some of the parameters for a water supply SCADA system, to be monitored and controlled are: - Meteorological measurements (rainfall, air temperature, evaporation) - Flow (rate and total) - Pressure - Water level (in dams, reservoirs and surge tanks) Pump status (stopped, running, fault, alarm, pump running time, power factor, kilowatt hours) - Water quality (turbidity, PH, residual chlorine) Valve status (on/off and selector switch position, valve opening position in percentage) - Security alarm of each gemote station. After the processing of the collected data, the water can be distributed in accordance to the demands from the consumer. Besides all, future investments for the expansion of network may easily be planned, to serve the increasing population and geographical area. VII DC Ol f- Ui S O û. 2 O. LU CO ÜZ «0 LU «J Ui 5 Ui DC W CO ILI cc o. DC LU H Ui u2 > **. _ıS >- D O cc£ UJ (D lj rT ıı ı nr Ü^JT J lifc.» İMİMİ N- UJ > O 3o CO o o VIII LU 00 O h- ^ Öİ l& o o ıx The main advantages of the controlling from one center can be described as following: - Achieving homogeneous operation of the distribution - Supplying continuous and necessary amount of water - Controlling of the flow in order to avoid instability and water hammer effects. - Enabling the controlling of the complex and distributed systems where the efficient operation requirements exceeds the capability of the operators. Simplifying the water generation and the distribution operations. Reducing of employment expert operators which in some extent enables to reduce the operational costs. Maintains an advanced data processing and statistical data bank where the logs and reports of the operation are processed and kept for the future references. A SCADA system is high technology computer-based system which has a wide variety of applications in industry for the monitoring of the remotely located plants and equipments, including the collection of essential data from the remote locations. SCADA systems are widely used in the following industries : - Power generation/distribution - Gas authorities - Oil refineries - Water authorities - Process industries - Transportation A completely integrated computer-based SCADA system would typically include the following major complementary components to effect a smooth and trouble-free SCADA system to satisfy particular system objectives depending upon the applications. - A Computer sub-system - A Communications sub-system - Remotely Operated Devices - A Telemetry sub-system - Field Instruments X Telemetry and telecommunication system generally consists of remote telemetry units (where the function ally were explained above) and a telecommunication media. The media can vary depending on the nature of the system. Wide area systems can utilize the power lines a radio dependent telecommunication but a local area system also use optical or telephone wires. In computer sub-system which is located in the control centers conversion of signals from telecommunica tion media to digital inputs are performed. Processing of all inputs are done in real time; the monitoring and control facilities are enabled over this computer sub system. All operations and incoming events are kept in logs for security and administrative purpose, reports are generated upon request for specified the intervals. Audible alarms and warnings are produced as soon as a sudden excess or fail in the measurement of a field instrument is observed to inform the operators about the situation of the distribution lines. Besides the items above the SCADA software shows all instrumentation in detailed graphics over color video display units which eases the burden of the operators. Supplied simulation programs help to shape the operational principles well in advance for the future usages in networks. Such a system can be evaluated upon examining the stable operation of the main distribution network, achieved efficiency, response time and operational expenses, as well as with the continuity of the operation, security and secrecy of the data. Due to the complexity of the main distribution lines and networks of the water supply systems, the behavior of the whole system can not be easily predicted especially because of many parameters and variables which are involved in the problem. It is advisable to create a model and work on it before realizing any operation on the water system, for avoiding any unwanted effect. With that advantage of simulation, a set of scenarios can be prepared beforehand to be used when the critical situations arises on the SCADA system which also forms the operational philosophy. With the use of a mathematical hydraulic model, simulation is done for the tank-pipe-valve systems. Tank volumes, which are to be used to compensate the instabil ities in daily consumptions, can be minimized especially with the remotely controlled valves in SCADA system. In this study the different values of volumes were examined (which were defined as ratio of the maximum input flow to the maximum daily consumption flow). Relying upon daily consumption figures, the input flow to tanks can be adjusted by use of valves so the XI required tank volumes might be minimized. The above mentioned flow control might bring a question of the flow control in non-natural, (non gravity feed ) pump feed lines. So the following methods were also mentioned briefly: - Throttling - Connection or disconnection of pumps - In parallel - in series - By pass regulation - Speed regulation - Impeller regulation - Prerotation control In the last section of the study; Büyükçekmece- Bahçelievler main distribution line (which were designed for a daily capacity of 400.000 m3 of water) of the Istanbul Metropolitan City, Istanbul Water and Sewerage Administration. The current problems of this line were examined and the new approaches which to be come along with the application of the SCADA system were also emphasized. XII c o O) < O W o Ü CD 03 O CO 111 in W H Ûİ OS 2 2 O O W H O o «jjs o ¦&¦ 2 O H < to ^ o a: ~ O H 3 < H O W ~ 2 2 < r Q O < U o 2 O < U 2 o o £~ Dİ CO < O) < < <$- 4» o (X E- 2 a o gjl^ w o < tu K W 2 W 2 X O < I 2 < I I I XIII BÖLÜM 1. GÎRİŞ Sürekli büyüyüp gelişen ve zamanla daha geniş alanlara yayılan büyük şehirlerin su problemlerini çözmek için, şehrin değişik yerlerine dağılmış su kaynakları, yüzlerce kilometrelik ana su getirme (isale) hatları ile şehire ulaştırılmaya çalışılmaktadır. Pompaları işleten teknik adamlar bazen tek bir pompanın işletimini üstlenmekte, bazen de yüzlerce pom panın işletiminden sorumlu olmaktadır. Acil durumlarda önemli kararlar vermeleri istenip bir yandan da en ekonomik işletim politikasını seçip uygulamaları beklenirse, özellikle yüksek güçlü pompa istasyonlarında ve karmaşık su getirme sistemlerinde iyi bir verim elde edilemeyeceği ortadadır. Bu durumda merkezden kontrol gerekmektedir. Merkezden kontrol terimi, bir sistem hakkında gerekli bilgileri tek bir merkeze ulaştırıp, sistemin istenen şekilde davranabilmesi için gerekli komutları üretmek ve bunları yürütmek şeklinde özetlenebilir, örneğin bir su getirme borusunda ölçülen debinin merkezde değerlendirilip istenenden fazla bulunduğu takdirde boru üzerindeki vananın kısılması kararı ve komutunu üretmek ve bunu yürüterek vanayı kısmak gibi. Artık günümüzde, günlük su dağıtımının milyon met reküp mertebeleri ile ölçüldüğü bir çok şehirde su dağıtımını düzenli yapabilmek için bilgi işlem, kontrol ve kumanda teknolojileri sahip Merkezi Su Yönetim Sistemleri - SCADA '1ar kurulmaktadır.