Power electronics for renewable energy smart grids
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Power Electronics for Renewable Energy, Smart Grids. - Chunyan An -Pooja Shah. What are Smart grids? Why do we need them?. International Programs: Drivers for Smart Grid Development. Notes:

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Power Electronics for Renewable Energy, Smart Grids

-Chunyan An

-Pooja Shah

What are Smart grids?

Why do we need them?

International Programs: Drivers for Smart Grid Development


•Government Policies/Mandates - The individual country government or region in which the country is a part (e.g., EU) has policies in place or has issued mandates specific to smart grid development.

•Environmental Goals – The country has a strong focus on environment and climate goals and the advancement of smart grid initiatives is seen as a key factor in meeting those goals.

•Electric Vehicle Integration – The integration of electric vehicles is seen as a major component of smart grid development in the country.

•Renewable Integration – The country is focused on rapidly increasing the integration of intermittent renewable energy sources which is driving the need for an advanced grid infrastructure.

•Reliability Concerns – The reliability of electric power supply to end use customers is a concern and smart grid development is seen as a main way to mitigate this.

•Financial Incentives - The country is supplying a large amount of government subsidies targeted specifically to smart grid development. The country is ranked as one of the top ten in government investment on smart grid.

•Energy Efficiency Goals – The country has a focus on the improvement of efficiency in the electric power sector and smart grid initiatives are seen as a way to accomplish this.

•Increasing Demand – The country is seeing a rapid increase in energy demand due to increasing population or expanding industry. Smart grid development is seen as a primary means to manage the growing energy demand related to this growth.

•Economic Competitiveness – The country views smart grid development as a key way to spur industry growth and improve global economic competitiveness.

•Geographic Grid Constraints – Sources of energy supply and centers of energy consumption are separated by long geographic distances or challenging terrain putting strain on the energy delivery system. More effectively managing the energy delivery through smart grid upgrades is seen as a key method of alleviating this issue.

•Energy Security Goals – Improving energy security and reducing imports is a key smart grid driver in these countries.

•Energy Theft Reduction – Energy theft is widespread and the development of a smart grid, especially smart meters, is viewed as a way to manage these non-technical losses.

Sources of Electricity Generation

Sources of U.S. electricity generation 2007Source: DOE

Smart Grid Challenges

Smart meter Deployment

Source: U.S. Energy Information Administration, Annual Electric Power Industry Report

  • Smart meters, or advanced metering infrastructure (AMI), can take real-time or near-real-time measurements, provide outage notification and power quality monitoring, and support in-home energy applications.

  • These meters use two-way communication to connect utilities and their customers. They support demand response and distributed generation, can improve reliability, and also provide information that consumers can use to save money by managing their use of electricity.

  • Utility companies have incentives to install advanced meters for residential customers because automated meter reading and remote connect-disconnect options can help lower costs.

  • When combined with automated data analysis, AMI data can provide the utility with detailed outage information in the event of a storm or other system disturbance. This information helps the utility restore service to customers more quickly and reduces the overall length of electric system outages. In a recent example, a tree limb fell onto a power line, knocking out power to 1,100 customers. Smart meter data allowed the utility to reroute power to all but 200 customers in less than one minute.

Power Electronics for Smart Grids

  • Power electronics for smart grids can mainly be divided into four categories:

    • Generators

    • Transmission/Distribution Systems

    • Energy Storage Systems/Distributed Generation

    • Smart End User Appliances

  • These power electronic systems along with communication systems form the heart of a smart grid energy network.

A decisively greater variety of PE arrangements occurs in distribution systems

In these systems PE converters/controllers are applied in general to matching parameters and coupling of distributed sources with power lines or local end-users, and controlling consumption of EE with these resources

Power Electronics for Smart Grids Wind turbines

  • Pros:

    • Variable-speed technology – 5% increased efficiency

    • Easy control of active and reactive power flows

    • Rotor acts as a flywheel (storing energy)

    • No flicker problems

  • Cons:

    • Higher cost (power electronics cost 7%)

Power Electronics for Smart Grids Variable-speed turbine with DFIG

  • Converter feeds the rotor winding

  • Statorwinding connected directly to the grid

  • Smallconverter

  • Lowprice

Power Electronics for Smart Grids Semi-variable speed turbine

  • Simplified Technique

  • Rotor resistance of the squirrel cage generator - varied instantly using fast power electronics

A number of turbines, ranging from 600kW to 2.75 MW, have now been equipped with this system, which allows transient rotor speed increases of up to 10% of the nominal value. In that case, the variable-speed conditions are achieved dissipating the energy within a resistor placed in the rotor.

Using this technique, the efficiency of the system decreases when the slip increases, and the speed control is limited to a narrow margin.

Power Electronics for Smart Grids Variable-Speed Concept Utilizing Full-Power Converter

Energy Transfer

Control of the active and reactive powers total-harmonic-distortion control

  • Decoupled from the grid

Energy storage CONTROL of Vdc

Driver controlling the torque generator, using a vector control


Power Electronics for Smart Grids Semiconductor-Device Technology

  • Power semiconductor devices with better electrical characteristics and lower prices

  • InsulatedGate BipolarTransistor (IGBT) is main component for power electronics

IGBTs have higher switching frequency , so

they introduce less distortion in the grid.

IGBTs are built like modular devices.

The silicon is isolated to the cooling plate and can be connected to ground for low electromagnetic emission even with higher switching frequency. The base plate of

this module is made of a special material that has exactly the same thermal behavior as silicon, so nearly no thermal stress occurs.

Power Electronics for Smart Grids Transmission / Distribution Systems -HVDC

The advantages of HDVC transmission over HVAC transmission:

  • More economic > 100 km and power 200-900 MW

  • Sending and receiving end frequencies are independent.

  • Transmission distance using dc is not affected by cable charging current.

  • Offshore installation is isolated from mainland disturbances

  • Power flow is fully defined and controllable.

  • Cable power losses are low.

  • Power-transmission capability per cable is higher.

Power Electronics for Smart Grids Photovoltaic Technology

  • PV systems as an alternativeenergy resource

  • Pros:

    • High reliability

    • Reasonable cost

    • User-friendly design

Power Electronics for Smart Grids Photovoltaic Inverters

Reduced version of the centralized inverter

single stringof PV modules is connected to the inverter

No losses on string diodes

separate MPPTs

increases the overall efficiency

PV modules as seriesconnections (a string) series connections then connected in parallel, through string diodes

Disadvantages !

Inverter and PV module as one electrical device

No mismatch losses between PV modules

Optimal adjustment of MPPT

high voltage-amplification necessary

Power Electronics for Smart GridsEnergy Storage Systems

  • Improvement of Quality

  • Support the Grid during Interruption

  • Flywheels – spinning mass energy

  • commercial application with active filters

Power Electronics for Smart GridsHydrogen-storagesystems

  • Storable

  • Portable

  • Highly versatile

  • Efficient

  • Clean energy carrier

  • Fuel cells to produce electricity

Renewable Energy Sources: A Challenge to the Grids

  • Sustainability of power supply stands for a number of measures for efficiency enhancement – with regard to power generation.

  • This refers to the increase in efficiency ratio during energy conversion at a power plant, the reduction in transmission losses in the grid and, last but not least, efficiency enhancement at the load.

  • The decisive role in terms of sustainability is played by the renewable energy sources, particularly those capable of producing entirely CO2-free power, such as hydro, solar and wind energy.

  • The balance between generation and consumption does not match on a lot of occasions.

  • The unbalance requires large amounts of reserve capacity from the rest of the grid which must be at hand. In the case of thermal power plants, this kind of reserve capacity is comparatively expensive (peak power).

Renewable Energy Sources: The Smart Grid wins!

The Basslink HVDC project in Australia enables the utilization of renewable energy sources from Tasmania

Future work

  • Vehicle to Grid and Vehicle to Home technology

  • Charging of Electric Vehicles using small packets, to spread the load overnight

  • Grid security: Why it may be safer to switch our control centers to the cloud

  • The future power grids will have to withstand increasingly more stresses caused by large-scale energy trading and a growing share of fluctuating regenerative energy sources

  • Smart grids need smart inverters.

  • A recent research suggests the discovery of a possible superconductor, which can point us in the direction of efficient power transmission.

  • Another recent research points towards the usage of Graphene for large storage of energy. This technique is in fact, being tested for a local university grid in Manchester.

  • Long life flow batteries


  • Power Electronics in Smart Electrical Energy Networks, Strzelecki.Benysek

  • http://www.eia.gov/energy_in_brief/article/power_grid.cfm

  • http://www.eia.gov/tools/faqs/faq.cfm?id=108&t=3

  • http://www.eia.gov/energy_in_brief/article/renewable_electricity.cfm

  • http://www.eia.gov/survey/meetings/elec-prelim0612/pdf/ee_demandresponse_smartgrid_conchanges.pdf

  • http://www.eia.gov/conference/2010/session8/grant.pdf

  • http://www.eia.gov/analysis/studies/electricity/pdf/intl_sg.pdf

  • http://www.eia.gov/conference/2010/session8/valocchi.pdf

  • http://www.eia.gov/todayinenergy/index.cfm?tg=%20smart%20grid

  • http://www.smartgridnews.com/artman/publish/Technologies_DG_Renewables/What-to-do-when-you-have-TOO-MUCH-solar-power-think-inverters-6558.html#.U41AoXJdWSo

  • http://www.outbackpower.com/applications/residential/grid-interactive

  • http://www.uetechnologies.com/

  • http://www.smartgridnews.com/artman/publish/Projects_R_D/DOE-New-battery-design-could-help-renewables-power-the-grid-5719.html#.U41PKHJdWSo

  • http://www.eetimes.com/document.asp?elq=a7d14c99801d433ba6ba63d4d25a6621&doc_id=1322501&page_number=2

  • http://www.eetimes.com/document.asp?doc_id=1322549&page_number=2

  • http://en.wikipedia.org/wiki/High-voltage_direct_current

  • http://am.renesas.com/ecology/index.jsp

  • http://www.culturechange.org/cms/content/view/714/63/

  • http://www.theatlantic.com/national/archive/2010/11/whats-really-wrong-with-the-smart-grid/66832/

  • http://www.45magazineonline.com/index.php?page=section_pages&sid=143

  • http://www.generatinginsights.com/whitepaper/building-the-business-case-for-smart-grid.html

Thank you!


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