Electrical Machine & Power SystemAn Overview of Power System

Chapter outline

Introduction Power system components - Generation, transmission, distribution Power system loads - Types of load, load demand, demand curve Power system in Malaysia - Energy generation company - IPP, co-generator - National Grid System

Introduction

Main ComponentsSupport Components

At power generating station (generating voltage) 11 20kV and frequency of 50 HzTransform to higher voltage (transmission voltage) 132kV, 275kV and 500kVTransform to lower voltage (distribution voltage) 33kV or 11kV

Power System Components

GenerationTransmissionDistributionLoadsGrid System (500kV, 275kV, 132kV, 66kV)Step-up transformer ( voltage,current)TNBSESCOSESB3 phase - 415 V, single phase - 240 VReduce the voltage 33kV,11kVPower System Components

Power System Components

POWER STATION- Generator output at 11kV/20kV is stepped up by transformer to 132kV 275kV and 500kV for transmission.HEAVY INDUSTRY - Some have direct connections to the transmission at 132kVTRANSMISSION - Transmission is mainly at 132kV, 275kV and 500kVSMALL INDUSTRY - Most small factories receive their electricity at 11kVHOUSE - Overhead distribution to individual houses is at 240V.AROUND TOWN & RESIDENTIAL AREA - Underground distribution to individual premises is at 415V and 240 VPower System Components

High voltages of 500kV, 275kV, 132kV are used for transmitting electricity over the grid system

Power System Components(Generation)

Generation Plant MixPower System Components (Generation)

Combustion Turbine Power PlantPower System Components (Generation)

Coal-fired Power Plant-near a river/lake bcoz large quantities of cooling water are needed to condense the steam as it exhaust from the turbinesPower System Components (Generation)

Hydroelectric Power Plant Sultan Mahmud Power Station, KenyirPower System Components (Generation)

Bakun Dam: Under constructionPower System Components (Generation)

TNB Power StationsPower System Components (Generation)

A transformer in a large sub-station reduces the voltage to 33kV, 22kV,11kVPower System Components (Transmission)

Lines/transformers operating at voltages above 100 kV are usually called the transmission system.Consists of Transmission Line and Sub-stations Transmission network of 500kV, 275kV and 132kV known as National Grid.

Power System Components (Transmission)

Transmission LineOverhead LinesCableUnderground CablesSubmarine CablesSub-stations

Power System Components (Transmission)

Transmission ParametersPower System Components (Transmission)

Waist-Type TowerDouble Circuit TowerGuyed-V-TowerPower System Components (Transmission)Transmission tower

Transmission towerPower System Components (Transmission)

Power System Components (Transmission)

Overhead Line ConductorsPower System Components (Transmission)Overhead Line Conductors

Sub-stationSize of substationDepends on transformer sizeTypical sizes132kV; 2 x 30MVA, 3 x 45MVA, 2 x 90MVA275kV; 2 x 180MVA, 3 x 180MVA, 2 x 240MVATypes of Sub-stationConventional outdoorRequire bigger spaceGIS (gas insulated switchgear)Less spaceOutdoor or indoorPower System Components (Transmission)

Outdoor Sub-stationPower System Components (Transmission)

GISPower System Components (Transmission)

Sub-station ComponentsTransformerCircuit Breaker / Switch GearIsolator SwitchesBusbarProtection Relay & Control Equipment

Power System Components (Transmission)

Power TransformerPower System Components (Transmission)

Circuit BreakerSpark gap. In event of a lightning strike on the line, the current can jump the gap between that ball and the protrusion on the tank, and make a path to earth. This prevents overloading the breaker. Power System Components (Transmission)

Circuit BreakerPower System Components (Transmission)

InsulatorsPower System Components (Transmission)

Supplies to rural communities are often reduced from 11kV to domestic voltages (415/240V) by pole mounted transformers.

Power System Components (Distribution)

Lines/transformers operating at voltages below 100 kV are usually called the distribution system.Part of the electric utility system between the bulk power source and the customer service entrances (loads).33kV, 22kV, 11kV, 6.6kV, 415V and 240V

Power System Components (Distribution)

Distribution Sub-stationDistribution Intakes (33kV, 22kV)Distribution Substations (22kV, 11kV, 6.6kV)Indoor substationOutdoor substationPole mounted substationCompact substationUnderground substationTransformer capacity100kVA, 300kVA, 500kVA, 750kVA and 1000kVAPower System Components (Distribution)

Distribution IntakePower System Components (Distribution)

Indoor Sub-stationPower System Components (Distribution)

Underground Sub-stationPower System Components (Distribution)

Compact Sub-stationPower System Components (Distribution)

Outdoor Sub-stationPower System Components (Distribution)

Pole-Mounted Sub-stationPower System Components (Distribution)

Types of Load:ResidentialCommercialIndustrialPublic TransportationPublic Lightingetc.Power System Loads

Residential LoadConsist of lighting, radio, TV, refrigerator, kitchen appliances, washing machine and etc.Usually, increases in the evening around 6 p.m. and return to a nominal value around 12 p.m.

Power System LoadsCommercial LoadConsists of lighting, air-condition and small appliances. Shops, business premises, schools, universities etc.The load is fairly constant from 9am until 9pm with the exception of any mid-day break.

Industrial LoadMainly consists of motor load, air conditioner, lighting, welding and furnaces etc.It can be divided into small, medium and large category. The nature of industrial load curve depends on the number of shifts worked in the industry. Power System Loads

Electricity Consumers

Power System LoadsElectricity energy cannot be stored.Generate electricity based on demand.Total power drawn by consumer fluctuates depends on the time of day and seasons.Demand CurvePlot each demand of electricity by consumer daily/annually

Demand CurvePower System Loads

Load Duration Curve3 types of loadBase loadHas to be fed 100% of the time.Intermediate loadsHave to be fed

Load Duration Curve100% : 8760hrs Plot the duration of each demand on annual based.Power System Loads

Y-Axis

X-Axis

Load Duration CurveBase-power stationsDeliver full power at all timesNuclear, coal-fired stationsIntermediate-power stationsRespond relatively quickly to changes in demandUsually by adding/removing generating unitHydropower stationsPeak-power stationsDeliver power for brief intervals during the dayPut into service very quicklyEquipped with prime movers that can be started up in a few minutes Diesel, pumped-storage turbines, gas turbines etc.Power System Loads

Main Power Producer in MalaysiaPower System in Malaysia

Generation capacity of major power producerPower System in Malaysia

Independent Power Producer (IPP)Privately owned power producer.After privatization (1990) 18 IPP (long term power purchase agreement)Generates and sell power to TNB.Upload onto the National Grid. Power System in Malaysia

ExampleYTL Generation Sdn. Bhd.Paka, Pasir GudangMalakoff BerhadLumut Power Station, SegariPrai Power Station, ButterworthTanjung Bin Power Station, JohorGenting Sanyen Power Sdn. Bhd.Kuala Langat Power StationIndependent Power Producer (IPP)Power System in Malaysia

Co-GeneratorMinor electricity supplyThere are several small distributors buy electricity from the utilities or generate their own power, mostly by co-generation.Then, distribute to customers within specific areas such as industrial complexes.Power System in Malaysia

Example 1 : Petronas Gas Sdn BhdGenerate electricity Co-generatorDistribute power within two Integrated Petrochemical Complexes (IPC) Central Utilities Facilities (CUF) in Gebeng & KertehExample 2 : KKIP Power Sdn BhdPurchase power from SESBDistribute power within Kota Kinabalu Industrial Park Co-GeneratorPower System in Malaysia

National Grid Systemprimary electricity transmission network linking the electricity generation, transmission, distribution and consumption in Malaysiaoperated and owned by TNBmore than 420 substation in Peninsular Malaysia are linked together by the extensive network of transmission lines operating at 132kV, 275kV and 500kVPower generated by TNB and IPP is carried by the National Grid towards customers connected to the various distribution networkselectrically interconnected to the transmission network of the Electricity Generating Authority of Thailand (EGAT) and also to Singapore PowerPower System in Malaysia

National Grid SystemPower System in Malaysia

National Grid System (main)Power System in Malaysia

Power System in Malaysia

Power System in Malaysia

National Grid InterconnectionTNB EGAT - HVAC 132kV/115kV overhead lines interconnection between Bukit Ketri (TNB) and Sadao (EGAT) 80MWHVDC 300kV interconnection overhead lines between Gurun (TNB) and Ban Khlong Ngae (EGAT) 300MWTNB SINGAPORE POWER - HVAC 275kV/230kV submarine cables interconnection between Pasir Gudang (TNB) and Senoko (Singapore Power) 200MWPower System in Malaysia

Objectives of TNB-EGAT HVDC ProjectPeak lopping; TNB imports during TNBs peak load (morning) and export during lower demand (evening)Sharing of spinning reserves; both TNB and EGAT reduce their respective spinning reserveEconomic power exchange; TNB may export if its price is lower than EGAT and vice versaHelp each other during system emergencies/crisis

Advantages of national grid systemProvide multiple paths between various generation sources and loadsProvide for power transfers from one geographic area to another to achieve overall system operating economicsInterconnect the bulk power facilities of individual power station/utilities so that they can better withstand major disturbancesPower System in Malaysia

Other advantages:StabilityLoad sharingContinuity of serviceMaintenance, breakdownEconomyCheap & efficient

Power System in Malaysia

National Load Dispatch Centre (NLDC)Located in Bangsar, KLObjectives:Grid system requires a grid controller/operator system.In order to ensure the supply of energy is safe and reliable.

Power System in Malaysia

NLDC FunctionMaintains system stabilityFrequency controlVoltage within limitsAchieve minimum operating costOptimize transmission lossesMerit order generation maintain spinning reserve requirementsco-ordinate generation and transmission maintenance outagesRestoration of supply after system faultPower System in Malaysia

Future ASEAN Power Supply Interconnection

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