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:
Why do we need them?
•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 U.S. electricity generation 2007Source: DOE
Source: U.S. Energy Information Administration, Annual Electric Power Industry Report
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
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.
Control of the active and reactive powers total-harmonic-distortion control
Energy storage CONTROL of Vdc
Driver controlling the torque generator, using a vector control
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.
The advantages of HDVC transmission over HVAC transmission:
Reduced version of the centralized inverter
single stringof PV modules is connected to the inverter
No losses on string diodes
increases the overall efficiency
PV modules as seriesconnections (a string) series connections then connected in parallel, through string diodes
Inverter and PV module as one electrical device
No mismatch losses between PV modules
Optimal adjustment of MPPT
high voltage-amplification necessary
The Basslink HVDC project in Australia enables the utilization of renewable energy sources from Tasmania