1. CHAPTER 1 DISTRIBUTION SYSTEMS AND TARIFFS
BEX – UTILISATION OF ELECTRICAL ENERGY
Prepared by,
DR. KOK BOON CHING

2. Outlines Introduction Electricity Generation Scenario in Malaysia
Electric Supply System
HV Distribution Networks
LV Distribution Networks
Hardware for Distribution Systems
Load Characteristics and Tariffs Rate

3. Introduction Energy is needed in many areas of human endeavor such as:
moving people and goods around - TRANSPORT
producing and processing of food - AGRICULTURE
manufacturing of useful materials and artifacts - INDUSTRY
Powering communication gadgets and equipment, and going about other commercial activities - COMMERCE
maintaining physical comfort and convenience in our homes - HOUSEHOLDS

4. Introduction - TRANSPORT
Transportation is the movement of people and goods from one place to another.
Transportation depends on continuous supply of energy.
Automobiles are powered by gasoline (petrol), aeroplanes by jet fuel (kerosene), and trucks, trains, and ships by diesel oil.
Conveyers, cranes, robots and pipelines use motors and pumps, which are powered by electricity.

5. Introduction - AGRICULTURE
Agro-industries and processing of agricultural products require energy.
Mechanical implements powered by fuel or electricity are immensely more efficient and productive than humans and animals.
In developed countries, a major portion of electricity used in agriculture powers irrigation pumps.
The energy requirements in agriculture are mainly met using solar energy, fossil fuels (oil, coal and natural gas), fuel wood and electricity.

6. Introduction - INDUSTRY
Most of the energy used in industry is used by the machines and processes, which make the products of industry.
Industrial energy-consuming systems include boiler and other fired systems (furnace, kilns, incinerators, dryers), compressed air system, electric motors (for fans, blowers, pumps, conveyers, etc.) and lighting system.
Energy is also used to heat or cool the buildings and to provide hot water and other facilities for workers.

7. Introduction - COMMERCE
Highly sophisticated communication systems both for the supply of goods and services, and the maintenance of organisational cohesion requires a ready supply of suitable energy.
Energy in commerce is basically use for information processing, ACMV, and lighting.
Electrical energy is the most common form of energy used and supplemented by chemical energy from batteries (renewable energy system).

8. Introduction - HOUSEHOLD
Energy is required in households for space heating or cooling, water heating, cooking, lighting, ironing, and power appliances like fridge, washing machines, sound systems, TV, hair dryers, shavers, clocks, blenders, toasters, vacuum cleaners, sewing machines, etc.
The energy may come from direct heating from the sun, electricity, burning of fossil fuels or fuel wood.

9. Generation Mix Profile in Malaysia
Installed Capacity by Fuel Type (2010)

10. Generation Mix Profile in Malaysia
Installed Capacity by Power Producers (2010)
Generation Mix Profile in Malaysia

11. Number of Consumers by Sector
Malaysia (2010)
Number of Consumers by Sector

12. SALES OF ELECTRICITY (Peninsular)

13. Major Power Station in Peninsular Malaysia (2010)

14. Some of Thermal Power Plants in Peninsular Malaysia
CONNAUGHT
BRIDGE (832 MW)
GT x 130 MW Gas
CC x 312 MW Gas
SERDANG (625 MW)
GT 3x135 MW Gas
GT 2x110 MW Gas
PORT DICKSON (360 MW)
CSP 3x120 MW Gas/Oil
PAKA (1,139 MW)
CC 3x290 MW Gas
CC 1x269 MW Gas
MANJUNG (2100 MW)
3 x 700 MW Coal
KEV (2,420 MW)
CSP 2x500 MW Coal/G/O
CSP 2x300 MW Coal/G/O
CSP 2x300 MW Gas/Oil
GT² 2x110 MW Gas
PASIR GUDANG (729MW)
CSP 2x120 MW Oil/Gas
CC x269 MW Gas
GT² 2x110 MW Gas
GELUGOR
CC 1 x 330 MW Gas
Teluk Ewa (68 MW)
GT 2 x 34 MW Dist
PRAI (360 MW)
CSP 3x120 MW Fuel Oil
TANJUNG BIN (2100 MW)
3 x 700 MW Coal N
LEGEND
Hydro
Thermal
SOUTH
CHINA
SEA
Note:
GT - Open Cycle Gas Turbine
CC - Combined Cycle
CSP - Conventional Thermal
C/G/O - Triple Fuel Coal, Oil & Gas
Dist - Distillate
STRAITS OF
MELAKA

15. Some of Hydro Power Plants in Peninsular Malaysia
Sg.Piah
2 x 7.3 MW
2 x 27 MW
Pergau
4 x 150MW
Chenderoh
3 x 10.7 MW
1 x 8.4 MW
Kenering
3 x 40MW
Temengor
4 x 87 MW
Kenyir
4 x 100MW
Bersia
3 x 24MW
Cameron Highland
261.9 MW N
LEGEND
Hydro
Thermal
SOUTH
CHINA
SEA
Note:
GT - Open Cycle Gas Turbine
CC - Combined Cycle
CSP - Conventional Thermal
C/G/O - Triple Fuel Coal, Oil & Gas
Dist - Distillate
STRAITS OF
MELAKA

16. Maximum Demand and Installed Generation Capacity
Peninsular Malaysia (2010)
(Source: Electricity Supply Industry in Malaysia: Performance and Statistical Information, Suruhanjaya Tenaga, 2010)

17. Maximum Demand and Installed Generation Capacity
Sabah (2010)
(Source: Electricity Supply Industry in Malaysia: Performance and Statistical Information, Suruhanjaya Tenaga, 2010)

18. Maximum Demand and Installed Generation Capacity
Sarawak (2010)
(Source: Electricity Supply Industry in Malaysia: Performance and Statistical Information, Suruhanjaya Tenaga, 2010)

19. Electricity Forecast (2007 – 2011)

20. TNB GRID SYSTEM 2010

21. TNB Grid System (2006)

22. MAJOR POWER STATION AND GRID SYSTEM IN SARAWAK (2010)

23. MAJOR POWER STATION AND GRID SYSTEM IN SABAH (2010)

24. Prospective ASEAN Power Grid

25. Electrical Supply Systems
Medium/High Voltage (HV)
Overhead transmission lines (500 kV, 275 kV).
Underground cables (132 kV, 66 kV, 33 kV, 22 kV, 11 kV, 6.6 kV).
For large scale industry customers.
Low Voltage (LV)
Voltage level below 1 kV (240 V and 415 V).
For residential, commercial, and small industry applications.

26. Definition of Voltage Levels
1 kV
50 kV
Low Voltage
Medium Voltage
High Voltage

27. Low Voltage (LV System)
Single-phase, 2-wire, 240 V, up to 12 kVA maximum demand
Three-phase, 4-wire, 415 V, up to 45 kVA maximum demand
Three-phase, 4-wire, C.T. metered, 415 V, up to 1000 kVA maximum demand
Citation: TNB Electricity Supply Application Handbook, 2nd Edition, March 2007

28. Medium and High Voltage (MV & HV)
Three-phase, 3-wire, 11 kV for load of kVA maximum demand and above
Three-phase, 3-wire, 22 kV or 33 kV for load of 5000 kVA maximum demand and above
Three-phase, 3-wire, 66 kV, 132 kV and 275 kV for exceptionally large load of above 25 MVA maximum demand
Citation: TNB Electricity Supply Application Handbook, 2nd Edition, March 2007

29. Steady-state Supply Voltage Performance
Under normal conditions
Voltage Level
% variation
415 V and 240 V
-10% & +5%
6.6 kV, 11 kV, 22 kV, 33 kV
5%
132 kV and 275 kV
-5% & +10%
Under contingency conditions
Voltage Level
% variation
415 V and 240 V
10%
6.6 kV, 11 kV, 22 kV, 33 kV
+10% & -10%
132 kV and 275 kV
Citation: TNB Electricity Supply Application Handbook, 2nd Edition, March 2007

30. Security Levels for Distribution Systems
For voltage levels of 6.6 kV, 11 kV, 22 kV and 33 kV – the average supply restoration is less than 4 hours.
For supplies at 240 V and 415 V – the restoration period may vary beyond 4 hours depending on the type of network fault.
Citation: TNB Electricity Supply Application Handbook, 2nd Edition, March 2007

31. Overview of Electricity Supply Systems
Structure of the Power System

32. High Voltage Electrical Supply
Main Transmission Line Network System
Connecting the electrical supply source from electrical generation stations to the main distribution network system at certain large areas like states, districts and big towns.
The main transmission line networks are liked to each other to form the “National Grid System”.
The method used in the transmission line network is the 3ø, 3 lines (R-Y-B) system through main overhead line tower.

33. High Voltage Electrical Supply
Primary Distribution Network System
It receives electrical supply from main transmission line network system.
It is located at few selected locations in a state.
The electrical power is delivered to the users through 4 distribution levels.

34. American Versus European System

35. High Voltage Electrical Supply
First Level (1) – Transmission Main Intake (TMI) or Pencawang Masuk Utama (PMU).
Interconnection point of 132kV or 275kV to the distribution network.
The standard transmission capacity and voltage transformation provided at the PMU are as follows:-
- 132/33kV, 2 x 90 MVA /22kV, 2 x 60 MVA /11 kV, 2 x 30 MVA

36. High Voltage Electrical Supply
Second Level (2) – Main Distribution Sub-station (MDS) or Pencawang Pembahagian Utama (PPU).
Main Distribution Sub-station is normally applicable to 33kV for interconnecting 33kV networks with 11 kV networks.
It provides capacity injection into 11 kV network through a standardized transformation of 33/11 kV.

37. High Voltage Electrical Supply
Third Level (3) – Main Switching Station (MSS) or Stesyen Suis Utama (SSU).
SSU at 33kV, 22kV and 11 kV are established to serve the following function:
To supply a dedicated bulk consumer ( 33kV, 22kV, 11 kV)
To provide bulk capacity injection or transfer from a PMU/PPU to a load center for further localized distribution.

38. High Voltage Electrical Supply
Fourth Level (4) – Distribution Substation (DS) or Pencawang Elektrik (PE).
Distribution sub-stations are capacity injection points from 11 kV, 22kV and sometimes 33kV systems to the low voltage network (415V, 240V).
Typical capacity ratings are 1000kVA, 750kVA, 500kVA and 300kVA.

39. High Voltage Electrical Supply
Under ground cables are used in the delivery system from level 1 – 4.
Types : 3C x 300 mm sq/ 3C240 mm sq/ 3C185 mm sq, XLPE (cross-linked Polyethylene), Aluminum.
Block diagram:
MTL
TMI
MDS
MSS DS
132kV/33 kV/11kV
33 kV/22 kV
33kV/22 kV/11 kV …
11kV/415 V
(LV) 1 2 3 4
33kV/11kV
22 kV/11kV

40. High Voltage Electrical Supply
Secondary Distribution Network System
Begins whenever the High Voltage electrical supply (11KV) received at DS is converted to Low Voltage electrical supply (415V).
Method used is the 4 lines (R-Y-B-N) through step-down transformer.
The number of DS is depends on the total load demands (VA) requested by the user.
Type of DS : Single Chamber (200 A) and Double Chambers (600 A).

41. High Voltage Electrical Supply
Number of chamber indicating the number of transformers needed. (2 chambers type can be recognised with 2 doors of the size of 2400 mm wide X 3000 mm high)
Type of transformer :
Oil Immersed Type, cheap but low efficiency (for small users).
Cast Resin - Dry, more expensive but higher efficiency (larger customers).
Nominal Volt-Ampere capacity of the transformer: 300 kVA, 500 kVA, 750 kVA, and kVA.

42. High Voltage Electrical Supply
What are inside the DS?
Switch gear
Transformer
Low Voltage Distribution Board
The 415V supply will then connected to the kWh metering system (user side) through LV underground cables.

43. High Voltage Electrical Supply
Layout of an DS (Single Chamber):
LV Board
Switchgear Room
Transformer Room
Outgoing Points

44. Single Chamber DS

45. Double Chamber DS

46. High Voltage Electrical Supply
Types of Electrical Supply Users:
HV – Higher institutions, shopping complexes, large factories (owned the MDS, MSS, DS).
LV – Domestic users, shop lots, public buildings.

47. Low Voltage Electrical Supply
Types:
3ø, 4 wires + E – 415V
1ø, 2 wires + E – 240V
Types of LV electrical installation:
Small Industry Buildings.
Small Commercial Building (shop, office, restaurant).
Small Residential Building (Condo, Terrace, Apartment).
Small Public Building (wet market, bus station,….)
Public Utilities (Street lights, traffic lights,…..)

48. Low Voltage Electrical Supply
Main components in a LV electrical supply distribution system (building):
kWh meter TNB
Main Switch Board (MSB)
Sub Switch Board (SSB)
Distribution Board (DB)

49. Low Voltage Electrical Supply
Example of residential connection: DS M
Loads
TNB
Consumers

50. Low Voltage Electrical Supply
Example of industry connection: DS
MSS
FACTORY
MSB
HT Switch Room
HT Meter Room
User’s Transformer Room
Main Switch Board
SSB

51. Main Switchboard (MSB)

52. Sub Switchboard (SSB)

53. Low Voltage Electrical Supply
Example: Double-storey House

54. Low Voltage Electrical Supply
Example: Terrace house installation

55. Economic Aspects
Utility company must plans for the electricity demand in advance as requested by its consumers.
Common terms used:
Connected load
Maximum demand
Demand factor
Average demand
Load factor
Diversity factor

56. Economic Aspects
Connected Load – sum of the rated maximum values of all loads used by consumer. It may be expressed in watts, kW, A, hp, kVA etc.
Maximum Demand – highest or peak demand for a specified time (might be in hour, day, month, or year).
Demand Factor (DF)

57. Economic Aspects
Average Demand – Sum of the total demand (in kWh) divided by the demand period (hr).
Load Factor (LF) - The ratio of the average load over the peak load. LF is always ≤ 1.

58. Economic Aspects
Diversity Factor (Div F) - The ratio of the sum of the individual maximum demands in a distribution system to the maximum demand of the whole distribution system.
For consumer – Div. F < 1.0
For generation supplier – Div. F > 1.0

59. Example 1 – Economic Aspects
A load rises from zero to 10 kW instantaneously and stays constant for 1 minute, then rises to 20 kW and remains constant for 1 minute, continues at this rate of rise until it reaches a maximum value of 50 kW for 1 minute, then instantly falls to zero for 1 minute, after which it again rises in 10 kW steps at 1 minute intervals to a maximum of 50 kW and returns to zero for 1 minute. If the load continues to vary in these steps:
What is the average demand over the first 15 minutes?
Over the second 15 minutes?
Over the 30 minutes demand interval?

60. Example 1 – Economic Aspects
Solution: 10 20 30 40 50 kW
15 minutes
Time (minute)

61. Example 1 – Economic Aspects
Solution (Cont.): (i) Total demand = (10 kW x kW x kW x kW x kW x 2) = 360 kW Average demand over 15 minutes = 360 kW/15 minutes = 24 kW.

62. Example 1 – Economic Aspects
Solution (Cont.): (ii) Total demand for the second 15 minutes = 390 kW Average demand = 390 kW/15 minutes = 26 kW (iii) Total demand over 30 minutes = 360 kW kW = 750 kW Average demand = 750 kW/30 minutes = 25 kW

63. Example 2 – Economic Aspects
A factory consumes 425,200 kVAh in a year
with the yearly average power factor, If
the half-an-hour demand was 120 kW, find,
The average load demand
Annual load factor
If the factory decided to increase the electricity usage to 450,000 kWh and the load factor to 65%, what will be the maximum demand?

64. Example 2 – Economic Aspects
Solution: (i) Average load demand = (425,200 x 0.86) kWh/ (365 x 24) hr = kW. (ii) Load factor = kW/ 120 kW = 35%. (iii) Maximum demand = 450,000 kWh/ (8,760 x 0.65) = kW.

65. Example 3 – Economic Aspects
A group of Parit Raja consumers has a total annual individual maximum demand of 132 kVA supplied from a single phase distribution transformer. If the average diversity factor between the group of consumers is 2.8, determine the nearest standard size of the distribution transformer that serving the consumers.

66. Example 3 – Economic Aspects
Solution: The size of the transformer is determined according to the maximum demand of the whole group. Group Maximum demand, = Annual individual maximum demand/ DF = 132 kVA/ 2.8 = kVA.  Nearest standard size = 50 kVA.

67. Tariffs
The rate of charging for electrical energy supplied by the utility company to its consumer.
Tariff charge is depends on various factors:
Type of consumer (industrial, commercial, or domestic)
Type of service (lighting, heating, etc)
Total fixed running annual charges of the utility company
Facility for calculating the bill

68. Tariffs Definition of electricity tariff: 3 types of tariffs:
Residential
Commercial
Industrial

69. TNB Tariffs Refer to “ TNB Tariffs Book” (updated 2011).
Power Factor Tariff (Low Power Factor Penalty):
Below 0.85 and up to 0.75 lagging, 1.5% of the bill for that month for each one-hundredth (0.01).
Below 0.75 lagging, A supplementary charge of 3% of the bill for that month for each one-hundredth (0.01).

70. Example 4 – Power Factor Tariff
A medium voltage industrial consumer having
the following data for its monthly electricity bill:
Total electricity consumption in kWh
- 160,000 units
The reactive power consumption in kVArh
- 120,000 units
The monthly load factor - 68%
For each kilowatt of maximum demand per month
= RM 25.30/ kW
For all kWh = 28.8 cents/ kWh

71. Example 4 – Power Factor Tariff
Determine the monthly maximum demand for this consumer. [take 30 days/month]
What is the total monthly bill charge for this consumer?
Recalculate the total monthly bill charge if the reactive power consumption is increased to 150,000 units.

72. Example 4 – Power Factor Tariff
Solution: (i) Monthly max. demand = 160,000 kWh/(0.68)(30 x 24) = kW. (ii) Monthly bill without PF consideration, = kW x RM ,000 kWh x RM = RM 54, PF = cos (tan-1 120,000/160,000) = 0.8 Poor PF charge = 1.5% x ( ) x 100 x RM54, = RM 4, Total monthly bill charge = RM 58,424.14

73. Example 4 – Power Factor Tariff
Solution: (iii) Monthly bill without PF consideration, = kW x RM ,000 kWh x RM = RM 54, PF = cos (tan-1 150,000/160,000) = 0.73 Poor PF charge = [1.5% x ( ) + 3.0% x ( )] x 100 x RM54, = RM 11, Total monthly bill charge = RM 65,761.13