1. ABS Ennin, George Coleman, David Dadson & Anthony Ansah
Substation Overview
Presentation by
ABS Ennin, George Coleman, David Dadson & Anthony Ansah

2. Substation Overview Introduction
Modern day users of electricity demand a constant and unvarying voltage and frequency to operate new sophisticated equipment. Customers also expect electric power 24 hours a day, seven days a week.
Many unpredictable incidents can interrupt the continuous operation of a power system. Overhead lines may be struck by lightning; untrimmed trees can fall or blow into a line; strong winds can cause lines to fall or make contact with each other; ice can accumulate re­sulting in overstressed conductors; cars can hit utility poles during an accident; electrical equipment can fail due to poor maintenance; contractors can dig into an underground cable; operating personnel can make switching errors. Yet, customers still expect electric power, on demand. Substations play a significant role in meeting these requirements.

3. Substation Overview OBJECTIVES
Upon completion of this module the participant should be able to:
Describe the purpose of a substation.
List the types of substations.
State the advantages of various switching configurations.
List the basic components of a substation.
List methods of voltage control in a substation.
Describe the function of metering in a substation.
 Describe the function of relaying in a substation
 Describe the function of equipment in the control room.
 List and describe the function of equipment at the switchyard.

4. Substation Overview
Purpose of a Substation Substations play an important role in a power system. Basically, a substation has three main functions; switching, transform the voltage, and control the voltage. An electrical power system is designed so that service will continue despite any damage or impairment to other components of the sys­tem by natural disaster or other phenomena. When a single element of the system is out of operation for a period of time, be it a few sec­onds or several days, the power system shall be capable of meeting the usual needs of the customer. Substations represent an impor­tant role in providing this reliability.

5. Substation Overview Purpose of a Substation
One important function of substations is switching. Whether it is switching normal load currents or fault currents, switching protects the power system and equipment in the event of trouble. Normally, the switching is done automatically with relaying and circuit breakers or switches. However, non-automatic switching of circuits can be done if it becomes necessary to improve reliability or security of the system.

6. Substation Overview Purpose of a Substation
Secondly, substations function to transform the voltage. For eco­nomic reasons, different voltages are used in various parts of the system, ranging from 11.5kV or lower in distribution systems, up to 330kV in bulk transmission systems. High voltages are desirable when the amount of power is great or the distance of transmission is very long. Lower voltages are advantageous where the amount of power is small or transmission distances are short. When a sub­station uses transformers, it represents a division between sections of the power system with different voltages.

7. Substation Overview Purpose of a Substation
Substations also function to control the system voltage. Various types of equipment are used to accomplish this. Voltage regulators and load-tap changers (LTCs) modify the voltage directly; whereas synchronous condensers, capacitor banks, static voltage compensator (svc) and shunt reactors con­trol system voltage by modifying the reactive power flow.

8. Substation Overview Substation Design Stage Construction Stage
A substation can be describe into two areas as:
Switchyard
Controlroom

9. Substation Overview Switchyard A Switchyard comprises of:
A Line Gantry
Incoming Line
Outgoing Line
Bus Configuration
Transformer Bank
Feeder Structure
Earthing
Voltage Control

10. Substation Overview Switchyard Equipment Lines Incoming Line Gantry
Outgoing Line Gantry
Shield Wire Network
Line Insulators/Arcing Horns
Wave Traps
Line CVTs
Line Lightning Arrestors/Shaded Rings
Skywire or Shieldwire
Line Disconnecting Switches
By-pass Switches
Line Breakers – Dead and Live Tanks
Line Ground Switch

11. Substation Overview
Switchyard Equipment Line Gantry

12. Substation Overview
Switchyard Equipment Line Gantry

13. Substation Overview
Switchyard Equipment - Line Insulator/Wave Trap/Arcing Horns

14. Substation Overview
Switchyard Equipment
Arcing Horns

15. Substation Overview
Switchyard Equipment Free Standing CTs for SF6 Breaker “Live Tank”

16. Substation Overview Switchyard Equipment
Lightning Arrestor with Shaded Ring

17. Substation Overview
Switchyard Equipment - Surge arresters act to discharge any power surge (transient cur­rents) high enough to cause serious damage. During normal opera­ting conditions, surge arresters appear in the system as open cir­cuits. When a disturbance occurs, such as from a lightning strike or switching surge, surge arresters discharge transient voltages that can cause serious equipment damage to ground.
Lightning Arrestor with Shaded Ring

18. Substation Overview
Switchyard Equipment Free Standing CTs for SF6 Breaker “Live Tank”

19. Substation Overview
Switchyard Equipment
Live Tank SF6 Circuit Breaker

20. Substation Overview
Switchyard Equipment Live Tank SF6 Breaker

21. Substation Overview
Switchyard Equipment Dead Tank SF6 Breaker

22. Substation Overview
Switchyard Equipment
Dead Tank

23. Substation Overview
Switchyard Equipment
SF6 Circuit Breaker

24. Substation Overview
Switchyard Equipment
SF6 Circuit Breaker

25. Substation Overview
Switchyard Equipment
Disconnect
Switch

26. Substation Overview Switchyard Equipment
Lightning Arrestor with Shaded Ring

27. Substation Overview
Switchyard Equipment
CVT with WAVETRAP

28. Substation Overview Switchyard Equipment
CVT with Carrier Mounting Device

29. Substation Overview Switchyard Equipment Busbar Conductors Hollow Bus
Busbar Insulator Support
Bus PTs
Bus CVT/CTs
Bus Ground Switch

30. Substation Overview
Substation Bus Configuration Single Bus

31. Substation Overview
Substation Bus Configuration Transfer Bus

32. Substation Overview
Substation Bus Configuration Double Bus

33. Substation Overview
Substation Bus Configuration Reserve Bus

34. Substation Overview
Substation Bus Configuration Ring Bus

35. Substation Overview
Substation Bus Configuration Breaker and Halve (Mesh) Bus

36. Substation Overview
Switchyard Equipment BUS PT

37. Substation Overview Switchyard Equipment Transformer Bank
Transformer Breakers
Breaker CTs
Isolating Switches
Motorized Disconnect Switch (MOD)
Transformers
Free Standing CTs
Lightning Arrestors /Shaded Rings
CVTs
Reactors

38. Substation Overview Switchyard Equipment Feeder Structure
Feeder Breakers
Feeder CTs
Feeder PTs
Station Service Transformer
Fused Switches
Grounding Transformer
Customer Connections
Capacitor Banks
Capacitor Bank Breaker
Capacitor Bank Ground Switches
Capacitor Bank Disconnect Switches

39. Substation Overview
Switchyard Equipment
Current Transformer

40. Substation Overview
Switchyard Equipment
Voltage Transformer

41. Substation Overview Switchyard Substation Earthing
System Earthing Alternatives
There are three basic alternatives, isolated systems with no intentional connection to earth,
impedance earthed systems with connection through a reactor or resistor and directly earthed
systems where transformer neutrals are connected directly to earth.

42. Substation Overview Substation Earthing Earthing of fences
Fences around the substation are might be energised through induced currents from overhead lines passing above. They should always be connected to encircling earth wires. The best is to put the earth wires outside the fence, but risks for theft often makes more practical to put them inside the fence.
The most common practice is to connect the fence at corners and every 50m along straight stretches. Gateposts shall always be connected. Fences inside the substation area must also be connected to the earth grid in the same way. However, for straight stretches, connect at every 10m.
NOTE: if the fence surrounds an air-core reactor group, the fence must be connected to earth at one place only, and that should be by one gatepost (if there is a gate). If the fence is connected at more than one place, the magnetic field surrounding the reactors will drive very

43. Substation Overview

44. Substation Overview Switchyard Voltage Control Capacitor Banks
Transformers
SVC Static Voltage Compensators
Reactors
Synchronous Condenser

45. Substation Overview Controlroom Equipment Annunciator Panel
Relay Panel
Protective Relays
Control Panel
Indicating Lamps
AC 400v Station Service Panel
DC 125V Rectifier
DC 48V Rectifier
125v Battery Banks
48v Battery Bank
DC/DC Converters

46. Substation Overview
Controlroom Equipment Annunciator Panel

47. Substation Overview
Controlroom Equipment Annunciator Panel

48. Substation Overview
Controlroom Equipment Relay Panels

49. Substation Overview
Controlroom Equipment Relay Panel

50. Substation Overview
AC Station Service Panel

51. Substation Overview
Controlroom Equipment
DC 125V Rectifier

52. Substation Overview
Controlroom Equipment
DC 125V Panel

53. Substation Overview
Controlroom Equipment
DC 125V Rectifier

54. Substation Overview
Controlroom Equipment
DC 48V Rectifier

55. Substation Overview Controlroom Equipment 125v DC battery Bank