Bayod

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Future development of the

electricity systems withDistributed Generation

Angel Antonio Bayod Rújula

Prof. Titular Department of Electrical Engineering

University of Zaragoza, Spain

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Traditional electricity system

Large Central

Generatión

Transmission

Network

Distribution

Network

Demand

Bulk transport of electricity

Coordination of control

Meshed network

Delivery system,Passive

Radial networks

Passive, uncontrollable

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Some drawbacks

• High level of dependence on imported fossil fuels

– fossil fuels running out – environmental impact of greenhouse gases and other

pollutants

– security of supply under threat

• Transmission losses

• Necessity for continuous upgrading andreplacement of transmission and distribution

facilities

– Load demand is continuously growing

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Distributed generation

• Use of small generating units installed

close to load centres• Other terms:

– Decentralized generation – Embedded generation

– Disperse generation

• Trend: generators sized from kW to MW at

load sites

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• “When planning the development of the

distribution network, energy efficiency/demand-side management measures

and/or distributed generation that might

supplant the need to upgrade or replace

electricity capacity shall be considered by

the distribution system operator” Article 14/7 of the Directive of the European Parliament and

of the Council concerning common rules for the internal

market in electricity

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DG it is not new

• In the early days of electricitygeneration, distributedgeneration was the rule, notthe exception.

• Customers in the closeneighbourhood of the

generation plant.• DC, voltages and distanceslimited

• Balancing demand and supply

was partially done using localstorage, i.e. batteries, whichcould be directly coupled to theDC grid.

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Renewed interest for DG

IEA lists five major factors

• developments in distributed generationtechnologies,

• constraints on the construction of newtransmission lines,

• increased customer demand for highly

reliable electricity,• the electricity market liberalisation and

• concerns about climate change.

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• Kyoto Objectives means to achieve an 8% CO2reduction between 2008 and 2012 compared to1990 level.

• Other current EU targets: – increase of the share of RES from 6% to 12% of gross energy consumption by 2010

– increasing the share of electricity from RES to 21% of

gross electricity consumption by 2010 (from 14% in2003);

• Different studies:

– By 2010, DGs will take nearly 25%-30% of the newfuture electric generation,

– PV industries and companies expect about onemillion rooftops equipped by PV modules

– Very big rise of wind farms capacities, etc

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Applications

• Stand alone, (Rural and remote applications)

• Standby – to supply power for sensitive loads during grid outages

• Peak load shaving – supply loads at peak periods (high electricity cost)

• Combined heat and power (CHP)

• Utility-owned DGs – support the grid, voltage profile,

reduce power losses, improve PQ

• Connected to the grid to sell kWh

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Technologies

Reciprocating Engines

Gas Turbines

Micro turbines

Fuel CellsPhotovoltaic Systems

Wind Energy

BiomassHydro electric resources

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Benefits of DG

• RES: Reduce fossil fuel consumption (emissions)

• Efficiency

– CHP

– Reduction of T & D electrical losses

• Deferral investments in T & D systems (enhance network

capacity)• Network support and ancillary services (?)

• Continuity, Reliability and Security of supply

• Improve competitiveness and Market opportunities• Flexibility and locality (resources, business, employment,

no new T&D lines)

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Technical problems

• Electricity grids are complex, integrated systems:

interaction between generators, grid and load.

• Inversion of energy flow

– Protection

– Operation

• Voltage control

• Initial network investments

• Reliability (?)• Additional stand-by and spinning-

reserve needed

-1.5

-1

-0.5

0

0.5

1

1.5

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Technical problems (II)

• Impact on Power

Quality

• Management of

reactive power

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The Future

Large CentralGeneratión

Transmission

Network

DistributionNetwork

Demand

Coordination of control

Meshed network

Active distribution networks

Coordination of controlMeshed networks

Responsive Demand

DistributedGeneration

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Active Distribution Networks

• Coordination of control

• Connectivity – Increase Interconnection

– Decide best operation IN REAL TIME – More sensors and actuators

– Ancillary services (stability, voltage support)

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Microgrids

• Low voltage networks with DG sources, together with local storage devices and controllable loads

• They connect multiple customers to multipledistributed sources of generation and storage

• Although they operate mostly connected to thedistribution network, they can be automaticallytransferred to islanded mode.

• They can be operated as a single aggregated loador generator. Given attractive remuneration, it cansupport the network, providing ancillary services

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Microgrids

Slide from CEU Microgrids project

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Virtual Utilities

• New model of energy infrastructure which

consists on integrate different kind of distributed generation utilities in an energy

(electricity and heat) generation network

controlled by a central energy

management system (EMS).

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• Centralized control with the EMS and different clusters of distributedgeneration utilities and heat storage tanks.

• Each of these clusters is controlled by a local management station

(LMS).• Every LMS has information about the requirements (heat, cold and

electricity) of the users connected to its cluster and the state of theutilities and water level of the storage tanks in its cluster.

• The EMS receives the information from the LMSs and sets theelectricity input or output of every cluster in the network.

• With the information ordered by the EMS, the LMS set the run or stand-by of the utilities of its cluster.

• The EMS can give priority to renewable energy sources instead of the use of fossil fuels.

• The electricity production in the network is subordinated to the heatnecessity of every user. The thermal energy is consumed on site;the electricity is generated and distributed in the entire network.

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Virtual Utility

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New network technologies

• Advanced Power Electronics

– FACTS – ASD and other high efficiency systems

• Demand-side Management and Demand-response techniques

• Stationary energy storage• Information and Communication

Technology (ICT)

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Conclusions

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• Within the Energy Theme, the Commission proposal for the Seventh Framework Programme (COM(2005) 119

final) confirms power networks and distributedgeneration as a priority for future research activitiesrequiring a European approach.

• The objective of the research area, referred to as ‘SmartEnergy Networks’ is

• “to increase the efficiency, safety and reliability of theEuropean electricity (and gas) system and networks, e.g.by transforming the current electricity grids into aninteractive (customers/operators) service network, and toremove the technical obstacles to the large scale

deployment and effective integration of distributed andrenewable energy sources.”

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• Thank you

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• Smaller amounts of energy produced by

numerous, small, modular energyconversion units

• Often located close to the point of enduse.

• These units can be stand-alone or

integrated into the electricity grid.

Fuente Eurobserv´ER

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Fuente Eurobserv ER

Eurobarometer 2004

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Technologies (I)

Reciprocating Engines

Main choice for emergency or standby power supplies, and generation < 1 MW

Gas Turbines

Small industrial gas turbines of 1- 20 MW are commonly used in CHP.

Particularly useful when higher temperature steam is required

Micro turbinesIndividual units range from 30-200 kW

Extremely high rotational speed ( up to 120 000 rpm)

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Technologies (II)Fuel Cell

Compact, quiet

Use hydrogen and oxygen to make electricity.

No combustion, noxious emissions are low.

Photovoltaic Systems

Capital-intensive,

Generate no heat and are inherently small-scale.

Best suited to household or small commercial applications,

Wind

Rapidly growing in importance. About 4.2 GW of capacity was installed during the year 2000.

Biomass

Hydro electric resources

E i i

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Emissions

Fuel

Cells Gas-Fired

Engine Diesel

Eng. SCR

Micro

Turbine

Small Gas

Turbine Photo-

voltaics

Wind

Turbine

Electric

Efficiency (LHV) 40-70% 25-45% 30-50% 20-30% 25-40% 15-30% 20-46%

Typical

Capacity

(kW) 2 1000 1000 25 4600 5000 1500

NO x

(lb/MWh) 0.03 0.50 4.70 0.44 1.15 0.00 0.00

SO 2

(lb/MWh) 0.006 0.007 0.454 0.008 0.008 0.000 0.000

PM-10(lb/MWh) 0.00 0.03 0.78 0.09 0.08 0.00 0.00

CO 2

(lb/MWh) 1078 1376 1432 1596 1494 0 0

Key:

NO x = Nitrogen oxides PM = Particulate Matter LHV= Lower Heating Value

SO 2 = Sulfur dioxide CO 2 = Carbon dioxide SCR= Selective Catalytic Reduction

ource: Emissions data from Joel Bluestein, Energy and Environmental Analysis, Inc.

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Transformador

Subestación

transformadoraRed MT (20 kV)

Red AT (220 kV)

Generadores BT (690 V)

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V+

Zth pcc

Loads

DG

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Bayod

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