1. بسم الله الرحمن الرحيم رب اشرح لى صدرى ويسر لى أمر واحلل عقدة من لسانى يفقهوا قولى صدق الله العظيم 18/16/2015Prof. Dr. Magdi El-Saadawi

2. Electrical Power Systems (1) Part II 8/16/2015Prof. Dr. Magdi El-Saadawi2 2 nd Grade EE Students

3. Fundamentals of Electrical loads Chapter 7 8/16/2015Prof. Dr. Magdi El-Saadawi3 pp. 251-264

4. 8/16/20154 Fig 1. Electrical Power System Prof. Dr. Magdi El-Saadawi

5. 8/16/20155 Introduction pp. 251  The function of a power station is to deliver power to a large number of consumers.  The load on a power station is never constant. It varies from time to time.  Electrical power cannot be stored and, therefore, the power station must produce power as and when demanded to meet the requirements of the consumers.  The power station should run at their rated capacity for maximum efficiency and on the other hand the demands of the consumers have wide variations. This makes the design of a power station highly complex. Prof. Dr. Magdi El-Saadawi

6. 8/16/20156 7.1 Variable Load on Power Station pp. 251  In this chapter, we shall focus our attention on the problems of variable load on power stations. The load varies due to uncertain demands of the consumers.  Effects of variable load.  Need of additional equipment.  Increase in production cost. Prof. Dr. Magdi El-Saadawi

7. 7.2 Load Curves pp. 253 A curve showing the variation of load on the power station with w.r.t time. These load variations during the whole day (i.e. 24 hours) are recorded half-hourly or hourly and are plotted against time on the graph. The curve thus obtained is known as daily load curve as it shows the variations of load w.r.t time during the day There is also monthly and yearly Load Curves 8/16/2015Prof. Dr. Magdi El-Saadawi7

8. 8/16/2015Prof. Dr. Magdi El-Saadawi8 Typical Daily Load curve

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11. Yearly Load Curve 8/16/2015Prof. Dr. Magdi El-Saadawi11

12. Information attained from Load curves –Variation of load during different hours of day –The area under the load curve gives the number of units generated in the day (kWh). –Max. and Min. value s of daily load –Average annual load on the station Average load = Area (in kWh) under daily load curve 24 hours 8/16/2015Prof. Dr. Magdi El-Saadawi12

13. Load factor = Average Load / Max. load The load curve helps in selecting the size number of generating units. The load curve helps in preparing the operation schedule of the station. 8/16/2015Prof. Dr. Magdi El-Saadawi13 Information attained from Load curves

14. Connected load: It is the sum of continuous ratings of all the equipment connected to supply system. Maximum demand : It is the greatest demand of load on the power station during a given period. Maximum demand is generally less than the connected load because all the consumers do not switch on their connected load to the system at a time. 8/16/2015Prof. Dr. Magdi El-Saadawi14 7.3 Important Terms and Factors pp 256

15. Demand factor: It is the ratio of maximum demand on the power station to its connected load < 1 Average load (Average demand): The average of loads occurring on the power station in a given period (day or month or year). Load factor: The ratio of average load to the maximum demand during a given period 8/16/2015Prof. Dr. Magdi El-Saadawi15 7.3 Important Terms and Factors pp 256

16. Load Factor Daily L.F.= Average load / Max. demand Monthly L.F. = kWh supplied in a month Maximum demand * 24 * 30 Annual L.F. = kWh supplied in a year Maximum demand * 8760 8/16/2015Prof. Dr. Magdi El-Saadawi16

17. Diversity of Load يعنى أن الأحمال المختلفة لا تعمل فى فترة زمنية واحدة أو أن شركات الكهرباء تتبع سياسات تدفع إلى ذلك Diversity Factor The ratio of the sum of individual maximum demands to the maximum demand on power station 8/16/2015Prof. Dr. Magdi El-Saadawi17

18. Practical Example on Diversity Factor 8/16/2015Prof. Dr. Magdi El-Saadawi18 Solution 1: Transformer Size (Assuming Diversity Factor of 1.0) 2,000 + 1,500 + 1,000 = 4,500 kVA Solution 2: Transformer Size (Assume Diversity Factor of 1.2) Choose 3,750 kVA (4,500 kVA divided by 1.2 = 3,750 kVA)

19. Capacity Factor The ratio of actual energy produced to the maximum possible energy that could have been produced during a given period. Average demand on the Station Maximum Energy that could be produced النسبة بين الطاقة التى أنتجتها المحطة إلى مايمكن أن تنتجه المحطة Average demand Plant Capacity The capacity factor is an indication of the reserve capacity of the plant. 8/16/2015Prof. Dr. Magdi El-Saadawi19

20. ? What is the difference between load factor and capacity factor Can they have the same value? 8/16/2015Prof. Dr. Magdi El-Saadawi20

21. Plant use Factor It is the ratio of kWh generated to the product of plant capacity and the number of hours for which the plant was in operation Station output in kWh kW 1 *h 1 + kW 2 *h 2 + kW 3 *h 3 + ……. It Indicates how best the plant capacity has been utilized الفرق بينه وبين المعامل السابق : أن هذا المعامل يتحدث عن الاستخدام الحقيقى للمحطة والسابق يتحدث عن امكانيات تشغيل المحطة 8/16/2015Prof. Dr. Magdi El-Saadawi21

22. ? What is the difference between Plant use Factor and Capacity factor Can they have the same value? 8/16/2015Prof. Dr. Magdi El-Saadawi22

23. Plant use Factor Load factor = Average load Max. demand Average load = Max. demand x L. F. Units generated/annum = = Average load (in kW) x Hours in a year = Max. demand (in kW) x L.F. x 8760 8/16/2015Prof. Dr. Magdi El-Saadawi23 7.4 Units Generated per Annum pp.261

24. Load Duration Curve pp. 261 8/16/2015Prof. Dr. Magdi El-Saadawi24

25. Load Duration Curve pp. 261 8/16/2015Prof. Dr. Magdi El-Saadawi25

26. Load Duration Curve 8/16/2015Prof. Dr. Magdi El-Saadawi26

27. Load Curve and Load Duration Curve 8/16/2015Prof. Dr. Magdi El-Saadawi27

28. The load duration curve gives the data in a more presentable form. Area under daily load duration curve (in kWh) will give the units generated on that day. (same as load curve) The duration curve can be extended to include any period of time  Daily load duration curve  Monthly load duration curve  Annual load duration curve 8/16/2015Prof. Dr. Magdi El-Saadawi28 Points about load duration curve pp 262

29. Thank You Very Much And Any Question?

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31. Capacity Factor is a value used to express the average percentage of full capacity used over a given period of time. Average demand on the Station Maximum Installed Capacity of the Station 8/16/2015Prof. Dr. Magdi El-Saadawi31

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34. 34 شكل توضيحى لحمل حكومى المحور الرأسى يمثل الحمل بالكيلو وات المحور الأفقى يمثل الزمن بالساعات 8/16/2015Prof. Dr. Magdi El-Saadawi

35. Difference between load curves of summer and winter 8/16/2015Prof. Dr. Magdi El-Saadawi35

36. Load Duration Curve pp. 60 8/16/2015Prof. Dr. Magdi El-Saadawi36

37. Demand Factor: the ratio between average load to the maximum connected load Power Station Maximum Demand: is the greatest average load on the station during a given period (15 min, 30 min or 1 hour as decided) 8/16/2015Prof. Dr. Magdi El-Saadawi37

38. Average Demand: the ratio of kWh delivered by the station in a particular period divided by the hours in that period Load Factor Monthly L.F. = kWh supplied in a month Maximum demand * 24 * 30 Annual L.F. = kWh supplied in a year Maximum demand * 8760 8/16/2015Prof. Dr. Magdi El-Saadawi38

39. ? Which is better and why High or Low load factor value High or Low diversity factor value 8/16/2015Prof. Dr. Magdi El-Saadawi39

40. Plant Factor Indicates how best the plant capacity has been utilized Station output in kWh kW 1 *h 1 + kW 2 *h 2 + kW 3 *h 3 + ……. Capacity Factor is a value used to express the average percentage of full capacity used over a given period of time. Average demand on the Station Maximum Installed Capacity of the Station 8/16/2015Prof. Dr. Magdi El-Saadawi40

41. Connected Load Factor Average kWh Connected load * 8760 8/16/2015Prof. Dr. Magdi El-Saadawi41

42. Load Duration Curve pp. 60 8/16/2015Prof. Dr. Magdi El-Saadawi42

43. Integrated Load Duration Curve pp. 60 8/16/2015Prof. Dr. Magdi El-Saadawi43

44. 8/16/2015Prof. Dr. Magdi El-Saadawi44 Integrated Load Duration Curve pp. 60

45. Mass Curve: pp. 62 represent the total kWh used by the load up to that hour of the day Selection of units pp.61 8/16/2015Prof. Dr. Magdi El-Saadawi45