تعیین حداقل قیمت آب شرب و بهینه‌سازی زمان جایگزینی لوله‌‌های شبکه توزیع آب شهری

نوع مقاله : مقاله پژوهشی

نویسندگان

1 دانشجوی دکترا، گروه علوم مهندسی آب، دانشکده کشاورزی،دانشگاه بوعلی سینا، همدان، ایران

2 دانشیار، گروه علوم مهندسی آب، دانشکده کشاورزی، دانشگاه بوعلی سینا، همدان، ایران

3 استاد، گروه علوم مهندسی آب، دانشکده کشاورزی، دانشگاه بوعلی سینا، همدان، ایران

چکیده

شکست لوله‌ها در شبکه‌های توزیع آب شهری به‌دلیل افزایش سن لوله‌ها، علاوه بر هدررفت قابل‌توجهی از آب شبکه، باعث زیان مالی شرکت آب و فاضلاب نیز می‌شود. بنابراین برای کاهش تعداد شکست لوله‌ها و جلوگیری از نشت، باید لوله‌های فرسوده را تعویض کرد. از سوی دیگر عملیات جایگزینی هزینه زیادی دارد. بنابراین تعیین زمان مناسب جایگزینی و نوسازی شبکه، برای کاهش تعداد شکست لوله‌های شبکه از یک سو و کاهش هزینه‌های تعویض از سوی دیگر، ضروری است. در این پژوهش با استفاده از روش پویای سیستم، شبکه آب‌رسانی شهر همدان شبیه‌سازی و سپس با استفاده از روش‌های حل تحلیلی معادله ارزش فعلی خالص و روش ترکیبی پویایی سیستم-ارزش فعلی، بهترین زمان جایگزینی لوله‌های شبکه، بهینه‌سازی شد. همچنین با استفاده از روش الگوریتم بهینه‌سازی پاول و به‌منظور بهبود توازن مالی شرکت آب و فاضلاب شهر همدان، میزان بهینه قیمت آب شرب تعیین شد. شبیه‌سازی به روش پویا در محیط برنامه‌نویسی VENSIM انجام شد و برای ارزیابی دقت روش‌های مذکور، از اطلاعات و داده‌های 5 ساله (1393 تا 1397) شرکت آب و فاضلاب شهر همدان استفاده شد. به‌منظور تجزیه‌و‌تحلیل آماری از شاخص‌های آماری ریشه میانگین مربعات خطا، خطای استاندارد و ضریب تبیین استفاده شد. بر اساس نتایج، برای متغیر منفعت به هزینه، شاخص RMSE برابر 006/0، SE برابر 010/0 و R2 برابر 991/0 محاسبه شد. خطای استاندارد متغیر منفعت به هزینه نشان داد که میزان اختلاف بین مقدار مشاهده‌ای و شبیه‌سازی شده این متغیر، کمتر از حدود یک درصد است که نشان از دقت بسیار بالای مدل دارد. طبق نتایج روش‌های ارائه شده در این پژوهش، زمان بهینه جایگزینی لوله‌ها در شبکه آب شرب شهر همدان، سال 1420 است. در نهایت، نتایج این پژوهش نشان داد که با تعیین قیمت بهینه آب شرب، می‌توان بیلان مالی شرکت را افزایش داد و علاوه بر جلوگیری از ضرر‌دهی شرکت آب و فاضلاب، با افزایش ضریب نوسازی لوله‌ها، سطح رفاه اجتماعی را نیز بالا برد. بنابراین می‌توان از روش پویایی سیستم و الگوریتم پاول برای بهینه‌سازی حداقل قیمت آب شرب، کاهش زیان وارده به شرکت‌های آب و فاضلاب و کاهش تعداد شکست لوله‌های آب‌رسانی، استفاده کرد.

کلیدواژه‌ها


عنوان مقاله [English]

Determining the Minimum Price of Drinking Water and Optimal Scheduling of Water Pipe Replacement in Urban Distribution Network

نویسندگان [English]

  • Maryam Vafaee 1
  • Hamed Nozari 2
  • Safar Marofi 3
1 PhD Student, Dept. of Water Engineering Science, Faculty of Agricultural, University of Bu Ali-Sina , Hamedan, Iran
2 Assoc. Prof., Dept. of Water Engineering Science, Faculty of Agricultural, University of Bu Ali-Sina, Hamedan, Iran
3 Prof., Dept. of Water Engineering Science, Faculty of Agricultural, University of Bu Ali-Sina, Hamedan, Iran
چکیده [English]

In urban water distribution networks, as the age of the pipes increased, the rates of pipe breakage and water losses increased which causes financial losses to the water and sewerage company. Therefore, to reduce the number of breaks and leaks in pipes, worn pipes should be replaced. Replacing old pipes is an expensive and costly procedure. Thus, it may be more economical to replace the pipe at the appropriate time. In this research, the urban water supply network of Hamedan was simulated by using system dynamics approach. Then the optimal time for pipe replacement was estimated by using analytical solution of the net present value equation and the combined method of system dynamics-net present value. Also, in order to improve the financial balance of Hamadan Water and Sewerage Company, the optimal price of drinking water was determined by using the Powell optimization algorithm method. Dynamic simulation was performed in VENSIM. To test the model, the simulated data were compared with the observed data collected from the water and sewerage organization of Hamedan over the period 2014 to 2018. To statistical analysis and calculating statistical, the root mean square error, standard error and correlation coefficient (R2) were used. Base on the results, for the Benefit-Cost variable, the RMSE index was calculated to be 0.006, the SE to be 0.010 and the R2 to be 0.991. Comparison of the standard error showed that the difference between the observed and simulated values of the standard error of the Benefit-Cost variable is less than about one percent. The result indicate that the presented model has the very high accuracy. Base on the results of the study, the optimal time for pipe replacement is 2041. Finally, the results of this study show that the financial balance of the company can be increased by determining the optimal price of drinking water. However, the level of social welfare can be improved by increasing the renewal coefficient of pipes. Conclusion: Therefore, the system dynamics method and Powell algorithm can be used to determine the optimal scheduling of water pipe replacement, to reduce losses to water and sewage companies and to reduce the number of failure of water supply pipes.

کلیدواژه‌ها [English]

  • Replacement Time
  • Net Present Value
  • optimization
  • Drinking Water Distribution Network
  • System dynamics approach
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