Chapter 1 Distribution Systems and Tariffs

UTILISATION OF UTILISATION OF ELECTRICAL ENERGYELECTRICAL ENERGY

CHAPTER 1CHAPTER 1DISTRIBUTION SYSTEMS AND TARIFFSDISTRIBUTION SYSTEMS AND TARIFFS

Name: Dr Goh Hui HwangName: Dr Goh Hui Hwang

BEE 4213BEE 4213

Outline

Introduction Electricity Generation Scenario in Malaysia HV Distribution Networks LV Distribution Networks Hardware for Distribution Systems Load Characteristics and Tariffs Rate

Learning Outcome

Explain the basic understanding of the electrical distribution systems

Overview of the Electricity Supply Industry in Malaysia

Explain the operational and design concepts of High Voltage (HV) and Low Voltage (LV) Distribution Networks.

Describe the basic of tariff rate in Malaysia

Introduction

We need energy in many areas of human endeavor such as: moving people and goods around - transporttransport producing and processing of food - agricultureagriculture manufacturing of useful materials and artifacts -

industryindustry Powering communication gadgets and equipment, and

going about other commercial activities - commercecommerce maintaining physical comfort and convenience in our

homes - householdshouseholds

Introduction - Transport

Transportation is the movement of people people and goodsand goods from one place to another.

Transportation depends on continuous supply of energyenergy.

Automobiles are powered by gasolinegasoline (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 electricityelectricity.

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.

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.

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.

Information processing, storage and retrieval also use a lot of energy in commerce.

Electrical energy is the most common form of energy used and supplemented by chemical energy from batteries.

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.

Electricity Scenario in Malaysia

LEGENDHydro

Thermal

LEGENDHydro

Thermal

Note:GT - Open Cycle Gas TurbineCC - Combined CycleCSP - Conventional ThermalC/G/O - Triple Fuel Coal, Oil & GasDist - Distillate

SOUTH CHINA SEASTRAITS OF

MELAKA

NTeluk Ewa (68 MW)GT 2 x 34 MW Dist

PRAI (360 MW)CSP 3x120 MW Fuel Oil

GELUGOR CC 1 x 330 MW GasSERDANG (625 MW)GT 3x135 MW GasGT 2x110 MW Gas

CONNAUGHT BRIDGE (832 MW)

GT 4x 130 MW GasCC 1x 312 MW Gas

PORT DICKSON (360 MW)CSP 3x120 MW Gas/Oil

PASIR GUDANG (729MW)CSP 2x120 MW Oil/Gas

CC 1x269 MW GasGT² 2x110 MW Gas

PAKA (1,139 MW) CC 3x290 MW GasCC 1x269 MW Gas

KEV (2,420 MW)CSP 2x500 MW Coal/G/OCSP 2x300 MW Coal/G/OCSP 2x300 MW Gas/Oil

GT² 2x110 MW Gas

MANJUNG (2100 MW)3 x 700 MW Coal

THERMAL POWER PLANTS

Electricity Scenario in Malaysia

HYDRO POWER PLANTS

Note:GT - Open Cycle Gas TurbineCC - Combined CycleCSP - Conventional ThermalC/G/O - Triple Fuel Coal, Oil & GasDist - Distillate

SOUTH CHINA SEA

STRAITS OF MELAKA

N

LEGENDHydro

Thermal

LEGENDHydro

Thermal

Bersia3 x 24MWKenering3 x 40MW

Chenderoh3 x 10.7 MW1 x 8.4 MW

Cameron Highland261.9 MW

Sg.Piah2 x 7.3 MW2 x 27 MW

Pergau4 x 150MW

Kenyir4 x 100MWTemengor4 x 87 MW

Electricity Consumptions - 1

Electricity Consumptions - 2

Electricity Consumptions - 3

Electrical Energy Utilisation

GRID SYSTEM IN P. MALAYSIA

GRID SYSTEM IN SARAWAK

GRID SYSTEM IN SABAH

Electrical Supply Systems

High Voltage (HV) Overhead transmission lines (500 kV, 275 kV,

132 kV). Underground cables (66 kV, 33 kV, 22 kV, 11

kV, 6.6 kV). For large scale industry customers.

Low Voltage (LV) Voltage level below 1 kV. For residential, commercial, and small industry

applications.

Overview of Electricity Supply Systems

High Voltage Electrical Supply

A. 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.

High Voltage Electrical Supply

B. 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 several distribution levels as follows:

American Versus European

High Voltage Electrical Supply

First Level (1) – Main Entry Sub-station (MES) or Pencawang Masuk Utama (PMU).

It is a building with high voltage switches and received electrical supply from main transmission line network system.

Second Level (2) – Main Divider Sub-station (MDS) or Pencawang Pembahagi Utama (PPU).

It also furnished with high voltage switches. It operates to receive the electrical supply from

MES.

High Voltage Electrical Supply

Third Level (3) – Main Switch Station (MSS) or Stesyen Suis Utama (SSU).

It operates with high voltage switches in order to receive electrical supply from MDS.

Fourth Level (4) – Electrical Sub-station (ES) or Pencawang Elektrik (PE).

It receives electrical supply from MSS. 2 types : Single Chamber and Double Chambers.

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 MES MSSMDS

ES

ES

33 kV 33kV / 22kV 22kV/11kV

415V(LV)

415V(LV)

High Voltage Electrical Supply

C. Secondary Distribution Network System Begins whenever the High Voltage electrical

supply (11KV) received at ES 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 ES is depends on the total load demands (VA) requested by the user.

Type of ES : Single Chamber (200 A) and Double Chambers (600 A).

High Voltage Electrical Supply

Number of chamber indicating the number of transformers needed.

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 (VA) capacity of the

transformer : 250 kVA, 500 kVA, 1000 kVA.

High Voltage Electrical Supply

What are inside the ES?

(i) Switch gear

(ii) Transformer

(iii) Low Voltage Distribution Board The 415V supply will then connected to the

kWh metering system (user side) through LV underground cables.

High Voltage Electrical Supply

Layout of an ES (Single Chamber):

LV BoardLV Board

Switchgear Room

Transformer Room

Outgoing Points

High Voltage Electrical Supply

D. Types of Electrical Supply Users: HV – Higher institutions, shopping

complexes, large factories (owned the MDS, MSS, ES).

LV – Domestic users, shop lots, public buildings.

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,…..)

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)

Low Voltage Electrical Supply

Example of residential connection:

ES M Users

TNB User

Low Voltage Electrical Supply

Example of industry connection:

ESMSS

FACTORY

MSB

HT Switch Room

HT Meter Room

HT Switch Room

User’s Transformer Room

Main Switch Board

SSB

Main Switchboard (MSB)

Sub Switchboard (SSB)

Low Voltage Electrical Supply

Example: Double-storey House Lighting Power

DB2

Lighting Power

DB1

M

1st Floor

Ground Floor

Incoming TNB

kWH meter TNB

Low Voltage Electrical Supply

Example: Terrace house installation

Terrace House

TH 1 TH 2 TH 3 TH 4

Service Cable

kWHMeter

Road

MM M M

Tap- off Unit

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

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)

load Connected

demand Actual DF

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 ≤ 1.

(hr) period Demand demand Maximum

(kWh) load Average LF

or

demand Maximum

kW)(in demand Average LF

Economic Aspects

Diversity Factor (DF) - The ratio of the sum of the individual peak demands in a distribution system to the peak demand of the whole distribution system. DF ≥ 1.

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?

Example 1 – Economic Aspects

Solution:

10

20

30

40

50

kW

15 minutes

Time (minute)

Example 1 – Economic Aspects

Solution (Cont.):

Total demand

= (10 kW x 3 + 20 kW x 3 + 30 kW x 3 + 40 kW

x 2 + 50 kW x 2)

= 360 kW

Average demand = 360 kW/15 minutes

= 24 kW.

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 + 390 kW = 750 kW

Average demand = 750 kW/30 minutes = 25 kW

Example 2 – Economic Aspects

A factory consumes 425,200 kVAh in a year

with the yearly average power factor, 0.86. If

the half-an-hour demand was 120 kW, find,

(i) The average load demand

(ii)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?

Example 2 – Economic Aspects

Solution:

(i) Average load demand

= (425,200 x 0.86) kWh/ (365 x 24) hr

= 41.74 kW.

(ii) Load factor = 41.74 kW/ 120 kW = 35%.

(iii) Maximum demand

= 450,000 kWh/ (8,760 x 0.65) = 79.03 kW.

Example 3 – Economic Aspects

A group of Parit Raja consumers has an 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.

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

= 47.14 kVA.

Nearest standard size = 50 kVA.

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

Tariffs

Definition of electricity tariff:

3 types of tariffs:i. Residential

ii. Commercial

iii. Industrial

[kWh]consumer the tosuppliedenergy Total

[RM] running) (fixed charges actual Total Tariff

[kWh]consumer the tosuppliedenergy Total

[RM] running) (fixed charges actual Total Tariff

TNB Tariffs

Refer to “ TNB Tariffs Book” (updated 2006). Power Factor Tariff:

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).

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 19.50/ kW For all kWh = 22.2 cents/kWh

Example 4 – Power Factor Tariff

i. Determine the monthly maximum demand for this consumer. [take 30 days/month]

ii. What is the total monthly bill charge for this consumer?

Example 4 – Power Factor Tariff

Solution:

(i) Monthly max. demand

= 160,000 kWh/(30 x 24) = 222.22 kW.

(ii) Monthly bill without PF consideration,

= 222.22 kW x RM 19.50 + 160,000 kWh x

RM 0.222 = RM 39,853.29

PF = cos (tan-1 120,000/160,000) = 0.8

Poor PF charge = 1.5% x (0.85 - 0.8) x 100

x RM39,853.29 = RM 2,989.00

Total monthly bill charge = RM 42,842.29