microgrids pdf

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Seminar DISTRIBUTED GENERATION: KEY ISSUES, CHALLENGES, ROLES , Paris, 1 st March 2004

Microgrids A Possible FutureEnergy Configuration?

Nikos Hatziargyriou Goran [email protected] [email protected]

NTUA, Greece UMIST, UK


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Topics Definition

Technical, Economic and Environmental Benefits of MicroGrids Conceptual design of MicroGrids

Integration requirements and device-network interfaces Market and regulatory frameworks for MicroGrids Modelling and simulation of MicroGrids The MicroGrids Project Conclusions


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What are MICROGRIDS?

Interconnection of small,modular generation to low

voltage distributionsystems forms a new typeof power system, theMicroGrid .MicroGrids can beconnected to the mainpower network or be

operated autonomously,similar to power systemsof physical islands.


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Technical, economic andenvironmental benefits

Energy efficiency Minimisation of the overall energy consumption Improved environmental impact Improvement of energy system reliability and

resilience Network benefits Cost efficient electricity infrastructure replacement

strategies Cost benefit assessment


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Energy Efficiency - Combined Heat and Power

Prof. Dr. J. Schmid

Up to now:

Central power stations Decentral heat production

In Future: Decentral combined heatand power

1/3 less consumption of fossil sources of energy100 % Oil / Gas

exchange of electrical energy

100 %powerstation

50 % electrical energy

50 %unusedwaste heat

50 % fossil fuel


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Improvement of ReliabilityDistribution of CMLs


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Potential for DG to improve service quality

G G G

DG

G G G

DG

DG

-Mediumscale DG

Central generation

Small-scale DG

Voltagelevel

Security of supply Security of supply


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Network Benefits Value of Micro Generation

LV Distribution

MV Distribution

HV Distribution

Transmission

Central Generation

MicroGeneration

~ .02-.04 /kWh

~ .05-.07 /kWh

~.1-.15 /kWh

~.03-.05 /kWh


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Cost benefit assessmentCMLs of European countries (in 1999) - Is it worth?


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Cost of Power Outages for SelectedCost of Power Outages for SelectedCommercial CustomersCommercial Customers

Brokerage Operations $6,480,000 per hour Credit Card Operations $2,580,000 per hour

Airline Reservations $90,000 per hour Telephone Ticket Sales $72,000 per hour Cellular Communications $41,000 per hour

Source: Reliability and Distributed Generation, a White Paper by ArthurD. Little


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Conceptual Design of MicroGrids energy management within and outside of the distributed

power system control philosophies (hierarchical or distributed) islanding and interconnected operation philosophy type of networks (ac or dc, fixed or variable frequency)

management of power flow constraints, voltage and frequency device and interface response and intelligence requirements protection options for networks of variable configurations

next-generation communications infrastructure (slow, fast) standardisation of technical and commercial protocols and

hardware


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Internal and External Markets

MGCC

DomesticCustomers

Non DomesticCustomers (shops, etc)

(A) Markets within a microgrid cell(internal interaction)

MGCC MGCC

DistributionManagement System

(B) Markets outside a microgrid cell(external interaction)


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MicroGrids Hierarchical Control

MicroGrid Central Controller (MGCC) promotes technicaland economical operation, provides set points to LC and MC;

Interface with loads and micro sources and DMS;MC and LC Controllers : interfaces to control interruptibleloads and micro sources (active and reactive generationlevels).

MV LVDMSDMSMGCCMGCC

DCAC

PV

MC

LC

MCAC

DC

LC

Storage

LC

~ CHPMC

Micro Turbine

MC

Fuel CellMCAC

DC

LCAC

DC

~

FlywheelMCAC

DC


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Interconnected Operation MicroGrids can operate:

Normal Interconnected Mode : Connection with the main MV grid; Supply, at least partially, the loads or injecting in the

MV grid; In this case, the MGCC:

Interfaces with MC, LC and DMS; Perform studies (forecasting, economic scheduling,

DSM functions,);


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Islanding Operation

MicroGrids can operate: Island Mode :

In case of failure of the MV grid; Possible operation in an isolated mode as in physical

islands; In this case, the MGCC: Changes the output control of generators from a dispatch

power mode to a frequency mode; Primary control MC and LC; Secondary control MGCC (storage devices, load

shedding,); Eventually, triggers a black start function.

Improvedreliability and

resilience


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Integration requirements anddevice-network interfaces

operation as the good and model citizen seamless transition between connection/islanding resilience under changing conditions operation fault level management and protection recovery from disturbances and contribution to

network restoration interfacing ac and dc networks Safety, modularity, robustness, low losses, calibration

and self-tuning


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Modelling and simulation of MicroGrids

modelling of generator technologies (micro generators,

biomass fuelled generation, fuel cells, PV, wind turbines),storage, and interfaces load modelling and demand side management unbalanced deterministic and probabilistic load flow and fault

calculators unbalanced transient stability models stability and electrical protection

simulation of steady state and dynamic operation simulation of interactions between Microgrids


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Market and Regulatoryframeworks for MicroGrids

coordinated but decentralised energy trading and management

market mechanisms to ensure efficient, fair and secure supplyand demand balancing

development of open and closed loop price-based energy andancillary services arrangements for congestion management

secure and open access to the network and efficient allocationof network costs

alternative ownership structures, energy service providers

new roles and responsibilities of supply company, distributioncompany, and consumer/customer


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MICROGRIDS Project

GREAT BRITAIN UMIST URENCO

PORTUGAL EDP INESC

SPAIN LABEIN

NETHERLANDS EMforce

USA EPRI

GREECE GERMANOS ICCS/NTUA PPC /NAMD&RESD

GERMANY SMA ISET

FRANCE EDF Ecole des Mines de Paris/ARMINES

CENERG

Large Scale Integration of Micro-Generation to Low Voltage Grids Contract : ENK5-CT-2002-00610

ARMINES

CENERG

ISET

ICCS / NTUAGERMANOS

EDF

SMA

UMISTURENCO

PPC/NAMD&RESD

LABEIN

14 PARTNERS,7 COUNTRIES

INESC

EDP

EPRI

http://microgrids.power.ece.ntua.gr


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The MicroGrids ProjectR&D Objectives:

Contribute to increase the share of renewables and to reduceGHG emissions; Study the operation of MicroGrids in normal and islanding

conditions;

Optimize the operation of local generation sources; Develop and demonstrate control strategies to ensure efficient,reliable and economic operation;

Simulate and demonstrate a MicroGrid in lab conditions;

Define protection and grounding schemes; Define communication infrastructure and protocols; Identify legal, administrative and regulatory barriers and propose

measures to eliminate them;


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MICROGRIDS - 9 Workpackages

WP A: Development of Steady State and DynamicSimulation Tools

WPB Development of Local Micro Source ControllersWPC Development of Micro Grid Central ControllerWPD Development of Emergency FunctionsWPE Investigation of Safety and Protection

WPF Investigation of Telecommunication Infrastructuresand Communication ProtocolsWPG Investigation of Regulatory, Commercial, Economic

and Environmental Issues

WPH Development of Laboratory MicroGridsWPI Evaluation of the system performance on study case

networks


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Challenges

Specific technical challenges: Relatively large imbalances between load and generation to

be managed (significant load participation required, need fornew technologies, review of the boundaries of microgrids)

Specific network characteristics (strong interaction between

active and reactive power, control and market implications) Small size (challenging management) Use of different generation technologies (prime movers) Presence of power electronic interfaces

Protection Unbalanced operation


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Highlight - Permissible expenditure to

enable islanding

Customer Sector: Residential Commercial

Annual benefit = 1.4 /kW pk 15 /kW pk

Net present value = 15 /kW pk 160 /kW pk

Peak demand = 2 kW 1000 kW

Perm. expenditure = 30 160,000

MicroGrid (2,000kW) 30,000 320,000


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Highlight: MGCC Simulation Tool


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Good Citizen Cost Reduction : 12.29 %

Model Citizen Cost reduction : 18.66%Load & Power exchange with the grid (residential feeder)

-30-20-10

0102030405060708090

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24

Hour

k W

Pow er exchanged w ith the grid Load Pattern

Steady state security increases cost by 27% and 29% respectively.

Residential Feeder with DGs


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Study CaseLV Feederwith DGsources

0.4 kV

uk=4%, r k=1%, Dyn1120/0.4 kV, 50 Hz, 400 kVA

3+N 3

20 kV

Off-load TC19-21 kV in 5 steps

80

10

80

3x70mm2 Al XLPE +54.6mm 2 AAACTwisted Cable

30 m

80 80 80

80

Single residencialconsumer3 , Is=40 A

S max=15 kVAS0=5.7 kVA

4x6 mm 2 Cu

20 m

4x25 mm 2 Cu

3+N3+N+PE

3+N+PE

20 m

30

30 m

4x16 mm 2 Cu

2

Possible neutral bridgeto adjacent LV network

80

80

20 m

Single residencial

consumer3 , Is=40 A

Smax=15 kVAS 0=5.7 kVA

Group of 4 residences4 x 3 , Is=40 AS max=50 kVAS0=23 kVA

3+N+PE

1+N+PE

3+N+PE

3+N+PE

3+N+PE

Appartment building5 x 3 , Is=40 A8 x 1 , Is=40 AS max=72 kVAS0=57 kVA

Appartment building1 x 3 , Is=40 A6 x 1 , Is=40 AS max=47 kVAS0=25 kVA

3x50 mm 2 Al +35mm 2 Cu XLPE

Pole-to-pole distance = 35 m

Overhead line4x120 mm 2 Al XLPE

twisted cable

80

Other lines

4x6 mm 2 Cu

Flywheel storageRating to be determined

~~~

Microturbine3 , 30 kW

Photovoltaics1 , 3 kW

30

Photovoltaics1 , 4x2.5 kW

~Wind Turbine3 , 15 kW

Circuit Breaker instead of fuses

80

30 m

4x16 mm 2 Cu

Fuel Cell3 , 30 kW

10

~

Circuit Breaker Possible sectionalizing CB


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3x250 A

Twisted Cable3x70mm2 Al XLPE +

54.6mm 2 AAAC

80 80 80

80

Pole-to-pole distance = 30 mSingle residencial

consumer3 , Is=40 A

Smax=15 kVAS0=5.7 kVA

3+N

2

Possible neutral bridgeto adjacent LV network

80

80

80

Single residencialconsumer3 , Is=40 A


Group of 4 residences4 x 3 , Is=40 ASmax=55 kVAS0=25 kVA

Appartment building5 x 3 , Is=40 A8 x 1 , Is=40 ASmax=72 kVAS0=57 kVA

Underground line3x150 mm 2 Al +

50 mm 2 Cu XLPE cable

Appartment building1 x 3 , Is=40 A6 x 1 , Is=40 ASmax=47 kVAS0=25 kVA

3x160 A

50

200 m

Workshop3 , Is=160 ASmax=70 kVAS0=70 kVA

3x160 A Overhead line4x50,35,16 mm 2 Al conductors

3+N3+N

80

Pole-to-pole distance = 35 m

Overhead line4x120 mm

2Al XLPEtwisted cable

3 , Is=40 ASmax=20 kVAS0=11 kVA

1 , Is=40 APhase: a


4x1 , Is=40 APhase: abccSmax=25 kVAS0=13.8 kVA

3 , Is=63 ASmax=30 kVAS0=16.5 kVA

80

4x35 mm2 Alconductors

1 , Is=40 APhase: c


2x1 , Is=40 APhase: ab


80 80

80


80

80

4x1 , Is=40 APhase: abbcSmax =25 kVAS0=13.8 kVA

3x1 , Is=40 APhase: abc

Smax=20 kVAS0=11 kVA



80

80

0.4 kV

uk=4%, r k=1%, Dyn1120/0.4 kV, 50 Hz, 400 kVA

3+N3

20 kV

Off-load TC19-21 kV in 5 steps

Industrial load

Residential load

Commercial load

LV network with multiple feeders

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