1. Electrical Power System SMJE 2103
Electrical Power Delivery System

5. Power Flow / Load Flow
A numerical analysis for future planning of operational power system in order to optimize generated power.
The objective is to produce following inform:
i- voltage magnitude and phase angle at each bus
ii- real and reactive power flowing in each element
iii- reactive power loading on each generator

6. Problem Statement
For a given power network, with known complex power loads and some set of specification or restrictions on power generation and voltages, solve for any unknown bus voltage and unspecified generation and finally for the complex power flow in the network components.

7. Network Structure

8. Load Flow Solution
There are four quantities of interest with each bus:
Real Power
Reactive power
Voltage magnitude
Voltage angle
At every bus of the system, two of these four quantities will be specified and the remaining two will be unknowns.
Each of the system buses may be classified in accordance with which of the two quantities are specified.

10. Power Delivery “Overhead Lines - Components”

11. Power Delivery “Towers - types”

12. Power Delivery “Towers - size”
Height of tower is determine by-
h1=Minimum permissible ground clearance
h2=Maximum sag
h3=Vertical spacing between conductors
h4=Vertical clearance between earthwire and top conductor

13. Power Delivery “Conductor - types”
ACSR Conductor(Aluminium Conductor Steel Reinforced)
AAC(All Aluminium Conductor)
AAAC(All Alloy Aluminium Conductor)

14. Power Delivery “Line – equivalent circuit”
L’ = Inductance
R’ = Resistance
C’ = Capacitance
G’ = Leakage Resistance

15. Power Delivery “Conductor - resistance”
Short line (up to 80 km)
Medium-length lines (up to 240 km)
Long line (above 240 km)

16. Power Delivery “Transmission Line – Single Line”

17. Power Delivery “Transmission Line”

20. Power Delivery “Power Cable”

21. Power Delivery “Power Cable”

22. Power Delivery “Power Cable - losses”

23. Power Delivery “Power Cable - losses”
Dielectric used for cable insulation must have following properties:
High insulation resistance
High dielectric strength
Good mechanical strength
Immune to attack by acids and alkali in the range 0-100o C
Should not be too costly
Should no be hygroscopic (tending to absorb water), or if hygroscopic should be enclosed in a water tight covering

24. Power Delivery “Cable - resistance”

25. Power Delivery “Cable - inductance”

26. Power Delivery “3- Core Cable - inductance”

27. Power Delivery “3- Core Cable – inductance (M & C)”

28. Power Delivery “3- Core Cable – inductance” (Measured)

29. Power Delivery “3- Core Cable - inductance” (Measured)

30. Example
A 3 core, 3 phase metal sheathed cable on testing for the capacitance gave the following result;
Capacitance between all conductors bunched and sheath, Cm1 = 0.6 F
Capacitance between two conductors bunched with sheath and third conductor, Cm2 = 0.36 F
With the sheath insulated, find;
Capacitance between any two conductor
Capacitance to neutral
Charging current if the cable is connected to 11 kV, 3 phase, 50 Hz system

31. Power Delivery “3- Core Cable – Gas-pressure”

32. Power Delivery “3- Core Cable – Gas-pressure”

33. Power Delivery “3- Core Cable – Gas-pressure”

34. Power Delivery “Insulator”

35. Power Delivery “Insulator - Types”
There are several types of insulators but the most commonly used are :
Pin Insulator
Suspension Insulator
Strain Insulator and
Shackle insulator.

36. Power Delivery “Pin Insulator”
- Nonconducting material such as porcelain, glass, plastic, polymer, or wood.
- Upto 33 kV

37. Power Delivery “Pin Insulator”

38. Power Delivery “Suspension Insulator”
- For high voltages (>33 kV)
- Each unit or disc is designed for low voltage, say 11 kV
- The number of discs in series would obviously depend upon the working voltage

39. Power Delivery “Suspension Insulator”

40. Power Delivery “Strain Insulator”
- Dead end of the line or corner or sharp curve.
- For low voltage lines (< 11 kV).
- Two or more strings are used in parallel.

41. Power Delivery “Strain Insulator”

42. Power Delivery “Shackle Insulator”
- Used for low voltage distribution lines.
- Horizontal or vertical position.

43. Power Delivery “Shackle Insulator”

44. Power Delivery “Insulator”

45. Power Delivery “Circuit Breaker”

46. Power Delivery “Circuit Breaker”

47. Power Delivery “Circuit Breaker”

48. Power Delivery “Circuit Breaker”

49. Power Delivery “Circuit Breaker”

50. Power Delivery “Switchgear (GIS)”

51. Power Delivery “Switchgear (GIS)”

52. Power Delivery “Switchgear (GIS)”

53. Power Delivery “Switchgear (GIS)”

54. Transmission-Lines Design
There are some factors should be considered in designing transmission lines for new power-system planning to meet future system requirement of load growth and new generation:
Electrical factors
Mechanical factors
Environmental factors
Economics factors
Discuss the factors in detail.