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Steady State Analysis Of A Microgrid Connected To A Power System

Presentation by Program FoS School

Ramesh PaudelEPSMEnergySERD

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Presentation Outline

Conventional Power SystemFuture Electric Power SystemDistributed Generation?Microgrid and Its ArchitectureObjectives of the Study Flowchart of the MethodologyTest Systems and Modes of OperationResultsConclusion

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Conventional Power System

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Pollution

End user0.91 kW

T & D Loss = 0.9 kW

Fuel 100%

33% delivered electricity

Power Plant

67% Total Waste

Line Losses 9%

Generation1 kW

Conventional Power System

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Effects of Emission

Pollutant

Local Effect Global Effect

NOx, SOx

Particulate Matter

CO2, CH4

Acid Rain

Smug

Green House Effect

More underground fault conditions in

older cables

More overhead damage due to harsh

storms

Demand increases for heating & pumping in

winter & air conditioning in

summer

Climate Change

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Future Electric Power System

Small Hydro Solar

Power

PlantBiomass

Off Shore Wind Farm

Hydro Power

Station

Low Emission

Plant Local Control Center

Microgrid

Underground Cable

Solar

Wave Energy

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Distributed Generation?

Advantages

Concern about climate change.

Improve power quality and system reliability.

Reduce transmission and distribution line losses.

Constraints on construction of new transmission lines.

Relatively low capital cost compared to centralized generation due to

avoided T&D capacity upgrades.

Disadvantages

With faults in system, DG has to be disconnected from grid. Loads

will be cut off from power.

Distributed or dispersed generation may be defined as a generating

resource, other than central generating station, that is placed close to

load being served, usually at customer site.

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Microgrid

“Microgrid” is an independent entity which combines loads and

distributed generators and can be controlled locally instead of

central dispatch of grid.

Microgrid follows grid rules and separates itself from distribution

system during disturbances without harming integrity of

distribution network.

Customers will be able to enjoy an uninterrupted power supply

with enhanced reliability and better power quality thereby

meeting their demand for power as well as heat.

From utility prospective MG helps in congestion management,

manage local power requirement and voltage support and delay

requirement of new power plants.

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Microgrid Architecture

HL

HL

Sensitive Loads

Adjustable Loads

Shade-able Loads

Grid Supply

HL

Point of common coupling Static switch

Reciprocating engine

Circuit breaker Heat load Fuel cell

Electronic interface PV panel Micro turbine

Electric wires Protection data

Communication data

A

B

C

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Objectives of the Study Siting of MG within a distribution

system.

To find optimal size DGs in MG.

Interaction between MG and

distribution system during Normal supply condition

Island operation.

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Flow Chart of MethodologyStart

End

Read input data

Run distribution load flow in base case.

Find suitable location of MG based on loss sensitivity factor.

Find optimal size of DGs and their location in MG using loss optimization technique.

Analyze performance of MG and distribution system under various operating conditions.

Print results

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Test Systems and Modes of Operation

1 2

3

4

5

6

7

8

9

10

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20

21

22

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24 26 28

25 27 29 30 31 32 331 2 3

4 7

5

6

11

9

10

15

13

14

19

17

41

21

24

25

28

29

37

33

22 26 31

38 42 46 49 51 53 55

8 12 16 20

18

23 27 32 36 40 45

35

30 34 39 48 50 5244 54 56 58 60 64

43

62

47

57 59 61 65 66 6763 68 69

IEEE 33 Bus System

IEEE 69 Bus System

1 2

3

4

5

6

7

8

9

10

11

12

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14

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16

17

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19

20

21

22

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24 26 28

25 27 29 30 31 32 33

IEEE 33 Bus System with Microgrid

IEEE 33 Bus System with Microgrid Isolated from

Distribution Network

2.378 MW 0.8725 MW

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ResultsSl no Particular Real power loss

(kW)Reactive power loss

(kVAR)

1 Conventional system 211.2 143.21

2 MG connected to power system

113.51 96.81

3 Percentage reduction in loss

46.25 32.4

Generation saving 107.35

kW

CO2 emission reduction

1109 ton/yr

Line 1-2 Line 2-4 Line 4-60

50

100

150

200

250Conventional systemDistribution system with MG

Branch

Cu

rren

t (A

)

Loss reduction

93.69 kW

Network with MG

Annual Energy saving 940

MWhr

Loss Reduction

Feeder Loading Capacity

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Results

1 2 3 4 5 6 7 8 9 101112131415161718192021222324252627282930313233

0.84

0.86

0.88

0.9

0.92

0.94

0.96

0.98

1 Voltage Profile

Conventional system

Distribution system with MG

MG- Isolated mode of operation

Bus No

Volt

ag

e

Pro

file

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Conclusion A methodology has been developed to identify a possible location of

MG in a distribution system. Placement of DGs is done for optimal

system loss.

System loss can be reduced nearly by 46% with the introduction of MG

into distribution system. Less electricity to be generated and hence

less emission.

Voltage profile of the system is greatly enhanced. Better performance

of electrical devices.

Feeder loading capacity is increased. Postpone construction of new

lines.

Isolated mode of operation of MG ensures an uninterrupted power

supply to loads. Consumers can enjoy good quality of power supply

without any interruption.

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7

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Substations

Solar Cells

EDLC

D.G, Battery, Control

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Thank you for your attention!

SAVE ENERGY.WE HAVE ONLY ONE EARTH TO LIVE IN.