1. 1 Coping with the Emerging Energy Demand for Charging Plug-in Electric Vehicles background lecture

2. 2 Electric Vehicles (EVs) over the next few years… Why? 64-86% U.S. sales of new light vehicles by 2030

3. 3 electric vehicles benefits (1) Economic saving in fueling 40% saving of primary energy with respect to the ICE but there is another benefit of paramount importance for society..

4. 4 have you heard about Global Warming? increasing temperatures in various regions increasing extremities in weather patterns almost 100% is due to the increase in the atmosphere of …

5. 5 greenhouse gases greenhouse gases are those gases that contribute to the greenhouse effect…

6. 6 the largest contributing source of greenhouse gases is the burning of fossil fuels leading to the emission of carbon dioxide

7. 7 conventional vehicles emissions when a combustion vehicle operates carbon dioxide is produced

8. 8 some data… an average passenger vehicle produces 5.2 metric tons of carbon dioxide per year considering 800 million of cars circulating worldwide, this means 4 billion 160 million (4,160,000,000) Metric Tons per year! it is more than 15 percent of total CO 2 emissions!!

9. 9 Electric Vehicles benefits (2) electric vehicles may contribute to reduce the greenhouse gas emissions: no combustion= no pollutants Indeed if electric energy they require comes from RENEWABLE SOURCES (wind, solar, geothermal, hydropower, wave/tidal etc…) Zero emissions!!!

10. 10 EV anatomy the engine is an electric motor energy is supplied by a battery pack an electronic system controls the motor operation and the state of charge of the battery pack Electrical engine Battery pack Dashboard Electronic control

11. 11 main advantages Clean (low or zero emissions) Higher driving comfort More convenient in terms of cost per mile Reduced engine maintenance Higher Safety in case of car accidents Reduced dependence on Oil

12. 12 main disadvantages Expensive Limited autonomy Battery maintenance “Refueling” time (battery charging) The risk of a new dependence on rare metals the major concerns are just about batteries..

13. 13 the battery is the vehicle “tank” ! the tank capacity is now the ENERGY that can the battery can store for the propulsion. it is expressed in Wh (Watt hour) typical range in commercial EVs: 5-50kWh (for a range autonomy of 100-200 miles)

14. 14 how much fast we “fill” our battery: The “speed” of the battery charging process is related to the charging rate. It is a measure of ELECTRICAL POWER, expressed in Watts! 1 hour 1,5 hours 3 hours a 15kWh battery charged at 15kW, 10 and 5kW…

15. 15 the energy stored in the battery and used for propulsion is supplied by the electric grid..

16. 16 the problem we have to cope with: when a vehicle is connected for battery recharging, it is an electric load for the grid to understand the problem, let’s consider the load trend during a typical day…

17. 17 typical load trends during the day* The energy request is low during the night can you imagine the effect of a diffusion of electric vehicles? It starts to increase as people wake up.. quite stable during the day Increases when people come back home Slowly decreases during the evening… When people will charge their electric vehicles? just when they’ll come back at home!! * based on the daily winter weekday maximum demand on the GB transmission system in 2005/06 from http://www.nationalgrid.com/uk/sys_06/print.asp?chap=2 http://www.nationalgrid.com/uk/sys_06/print.asp?chap=2

18. 18 effect of the EVs contemporary load on the grid overload!! higher energy request during peak hours

19. 19 the charging process starts just when the vehicle is plugged in, provided that the available power on the grid is enough the charging process is performed at a fixed rate (usually the maximum charging rate allowed by the battery) if the power request exceeds the available power at the time of plug- in, the charging request is rejected and the user cannot charge its battery existing grids are not able to manage this overload, because.. this is the so-called “superdumb” approach: no communication between users and service supplier no supply/demand adjustments

20. 20 a practical example at 18.00 Ms. Gray arrives her charging begins, at a rate of 20kW 10kW are still available at the node at 18.15 Mr. White arrives the available power at the node does not suffice his charging is not possible! Available power 30kW Ms. Gray 20kWh Arrival 18:00 Depart 22:00 Max Rate 20kW Arrival 18:15 Depart 22:00 Mr. White 20kWh Max Rate 20kW Available power 30kW

21. 21 at 18.00 Ms. Gray arrives her charging begins, at a rate of 20kW 10kW are still available at the node at 18.30 Mr. Red arrives the available power at the node does not suffice his charging is not possible! a practical example Available power 30kW Ms. Gray 20kWh Arrival 18:00 Depart 22:00 Max Rate 20kW Arrival 18:30 Depart 20:00 Mr. Red 20kWh Max Rate 20kW

22. 22 at 22.00… average satisfaction degree= (100%+0%+0%) / (3 users) = 33.3% Ms. Gray State of charge 100% State of charge 0% Mr. Red State of charge 0% Mr. White

23. 23 a first possible development… we could “schedule” the energy demand of the users

24. 24 if the available power on the grid suffices, the charging process starts just when the vehicle is plugged in if it not possible to satisfy the user request, the user is queued in a queue containing the users still to be charged, sorted in accord with their arrival time as soon as enough power becomes available, the users of the queue are served how time scheduling works… clearly users must communicate to a control entity their expected departure times, as well as the instant at which they are fully charged

25. 25 in the same case now.. at 18.15 Mr. White arrives the available power at the node is not enough his charging is not possible! however he is queued Ms. Gray 20kWh Arrival 18:00 Depart 22:00 Max Rate 20kW Arrival 18:15 Depart 22:00 Mr. White 20kWh Max Rate 20kW Arrival 18:30 Depart 20:00 Mr. Red 20kWh Max Rate 20kW 10kW are still available at the node at 18.00 Ms. Gray arrives her charging begins, at a rate of 20kW at 18.30 Mr. Red arrives the available power at the node is not enough his charging is not possible! however he is queued

26. 26 at 19.00… at 19.00 Ms. Gray is fully charged her charging ends 30 kW are now available at the node so, at 19.00 Mr. White can be served however, at 19.00 the available power at the node does not suffice also for Mr. Red his charging is not possible! he is still queued his charging begins, at a rate of 20kW 10 kW are now available at the node Ms. Gray 20kWh Arrival 18:00 Depart 22:00 Max Rate 20kW Arrival 18:15 Depart 22:00 Mr. White 20kWh Max Rate 20kW Arrival 18:30 Depart 20:00 Mr. Red 20kWh Max Rate 20kW

27. 27 at 20.00… Mr. White is fully charged the charging of Mr. Red could start however, he departs so, Mr. Red is not satisfied his charging ends 30 kW are now available at the node Ms. Gray is fully charged Ms. Gray 20kWh Arrival 18:00 Depart 22:00 Max Rate 20kW Arrival 18:15 Depart 22:00 Mr. White 20kWh Max Rate 20kW Arrival 18:30 Depart 20:00 Mr. Red 20kWh Max Rate 20kW

28. 28 at 22.00 Average satisfaction degree= (100%+100%+0%) / (3 users) = 66.7% It’s better than the “superdumb” approach, but… Ms. Gray State of charge 100% State of charge 0% Mr. Red State of charge 100% Mr. White

29. 29 it is still a “dumb” approach Mr. Red has less time at disposal. His charging is more urgent… using a fixed charging rate of 20 kW with a maximum available power of 30 kW does not allow performing more than one charging process at the same time Ms. Gray 20kWh Arrival 18:00 Depart 22:00 Max Rate 20kW Arrival 18:15 Depart 22:00 Mr. White 20kWh Max Rate 20kW Arrival 18:30 Depart 20:00 Mr. Red 20kWh Max Rate 20kW

30. 30 summarizing the “dumb” approach : the charging process is performed at a fixed charging rate, without any adapting mechanism to the grid load conditions the users are arranged in the queue solely on the basis of their arrival time this scheduling process does not take into account that some users could have less time at disposal to complete the charging process

31. 31 what if… can you imagine what happens if you could sort the charging processes by assigning to Mr. Red a higher priority? can you imagine what happens if you could adjust the charging rate of each user during the charging process to fully exploit the 30 kW available from the grid? Ms. Gray 20kWh Arrival 18:00 Depart 22:00 Max Rate 20kW Arrival 18:15 Depart 22:00 Mr. White 20kWh Max Rate 20kW Arrival 18:30 Depart 20:00 Mr. Red 20kWh Max Rate 20kW

32. 32 a “smart” approach the charging process of each PEV can be scheduled on the basis of a priority criterion rather than just considering the arrival times of the users the charging rate of each PEV can be adapted to the grid load condition during the charging process users must communicate to a control entity their arrival and departure times, as well as their current state of charge

33. 33 how to assign the priority? you can consider how much energy an user requires and how much time is still available for its charging process before the user drive-off do you think there should be something else to be taken into account?

34. 34..and the utility profit? in a realistic scenario, it is presumable that users will have different electricity rates utility would like to give a higher priority to users which are disposed to pay higher electricity rates this can be an important parameter for the utility profit

35. 35 a more complete priority function we can also account for the electricity rate of the user the influence of the power required and the electricity rate on determining the user priority can be adjusted by tuning the weighting coefficients a and b (it is convenient to set always a+b=1)

36. 36 how to decide the charging rate? you can “spread” the required energy over the entire remaining time period before the user drive-off

37. 37 updating priority and charging rate for each user, both the energy required and the time still available change during the charging process. Therefore, priority and charging rate must be updated at regular intervals (time resolution). How do you choose the time resolution?

38. 38 what about the grid structure? system users, operators and automated devices need to exchange information about grid operating conditions, so to dynamically respond to changes in grid condition and user requests smart grid manager the grid becomes “smart” two-way communication devices

39. also the vehicle.. Electronic control on-board control system needs to be developed to support both data exchange with the grid and advanced charging strategies Electrical engine Battery pack Dashboard Smart charging manager/grid interface

40. 40 in your experiments… measure of the effectiveness: users satisfaction degree (it is a measure of the success the system has to satisfy the requests) utility profit (it is a measure of how effective is for the system owner its resource management policies) you’ll also evaluate the impact of each charging strategy on the system complexity … you’ll simulate the charging processes of Electric Vehicles by using different charging strategies

41. 41 how to “measure” the system complexity? you can measure: 1)simulation time 2)number of communication events the larger the simulation time, the more complex (and then costly) the system the larger the number of communication events, the more complex (and then costly) the system

42. 42 the tool the main Graphical User Interface (GUI) will allow you to navigate easily through all the tasks to be performed you will use a very intuitive Graphical User Interface (GUI) implemented in Matlab environment

43. 43 you will create different scenarios… in the different tasks you will analyze different situations by fixing the grid available power, the number of users, the user parameters (battery capacity, max. charging rate, electricity rate, etc.), the energy dispatching strategy…

44. 44 … and you will see the system evolution The tool allows to visualize the satisfaction degree and the communication events for each user of the system, as well as the utility profit and the simulation time

45. 45 summarizing your tasks Task 1: you will be familiarized with the basic concepts about battery charging parameters: available power from the grid, battery charging rate and capacity, state of charge Task 2-5: you will compare the superdumb, the dumb, and your different smart approaches in a small-scale scenario (a local node of the grid with 6 vehicles at most)

46. 46 Part 2 (optional)

47. 47 Task 6: extension to a large scale system real grids consists of hundreds of local nodes experiment the impact of different strategies in a large scale scenario rather than focusing solely on a local node in this case thousands of users will be involved in your experiments..

48. 48 statistical analysis thousands of users will have a random behavior: the simulation tool provides you the possibility to carry out a statistical analysis of a large scale scenario random arrival and departure times random electricity rates

49. 49 statistics distribution to perform large-scale analyses, you will decide statistical user profiles. you can choose uniform or gaussian statistical distributions for the user arrival and departure times, as well as for their electricity rate uniform gaussian the probability that a user arrives in a given time instant x is the same within the time interval [a, b] the probability that a user arrives in a given time instant x is higher around the instant  (mean). However, about 68% of users will arrive in the time interval [   is the “standard deviation”

50. 50 for further details please refer to the project assignment document and the GUI manual

51. 51 useful references [1] http://www.youtube.com/watch?v=xKg7EYThJ0c http://www.youtube.com/watch?v=xKg7EYThJ0c [2] R. Pratt et al., “The Smart Grid: An Estimation of the Energy and CO 2 Benefits”, Pacific Northwest National Laboratory Report, 2010. [3] Emission Facts: Greenhouse Gas Emissions from a Typical Passenger Vehicle http://www.epa.gov/oms/greenhousegases.htm http://www.epa.gov/oms/greenhousegases.htm (http://timeforchange.org/cause-and-effect-for-global-warming) [4] http://energycenter.org/index.php/technical-assistance/climate-change http://energycenter.org/index.php/technical-assistance/climate-change [5] Bureau of Transportation, number of vehicles and vehicle classification http://www.bts.gov/publications/national_transportation_statistics/html/table_01 _11.html. http://www.bts.gov/publications/national_transportation_statistics/html/table_01 _11.html

52. 52 Images credits Slide 2. Left: Image by Joe Ross, http://www.fotopedia.com/items/flickr-2254098564. Right: Image by saebaryo, http://www.fotopedia.com/items/flickr-3455146732http://www.fotopedia.com/items/flickr-2254098564 http://www.fotopedia.com/items/flickr-3455146732 Slide 3. Image by tobym, http://www.fotopedia.com/items/flickr-466229969http://www.fotopedia.com/items/flickr-466229969 Slide 4. Image by Martha de Jong-Lantink, http://www.fotopedia.com/items/flickr-2889561921http://www.fotopedia.com/items/flickr-2889561921 Slide 6. Image by net_efekt, http://www.flickr.com/photos/wheatfields/4688140998/http://www.flickr.com/photos/wheatfields/4688140998/ Slide 7. Image by wwf_france, http://www.flickr.com/photos/wwf-france_footage/2916082821/http://www.flickr.com/photos/wwf-france_footage/2916082821/ Slide 9. Image by United Nations Photo, http://www.flickr.com/photos/un_photo/5410822714/http://www.flickr.com/photos/un_photo/5410822714/ Slide 15. Power plant image by Bruno D Rodrigues, http://www.flickr.com/photos/davipt/164341428/. Transmission substsation image by ykanazawa1999, http://www.flickr.com/photos/27889738@N07/4860145679. High voltage transmission lines image by Henrik Johansson, http://www.fotopedia.com/items/flickr-5515505114. Power substation image by Iris Shreve Garrott, http://www.fotopedia.com/items/flickr-2310447664. Transformer image by Paul Chernikhowsky, http://www.flickr.com/photos/pchernik/4099436471/. Low voltage line image by Paul Joseph, http://www.fotopedia.com/items/flickr-3110129640. Home image by James Thompson, http://www.flickr.com/photos/jwthompson2/139445633/sizes/l/in/photostream/.http://www.flickr.com/photos/davipt/164341428/http://www.flickr.com/photos/27889738@N07/4860145679http://www.fotopedia.com/items/flickr-5515505114http://www.fotopedia.com/items/flickr-2310447664http://www.flickr.com/photos/pchernik/4099436471/ http://www.fotopedia.com/items/flickr-3110129640 http://www.flickr.com/photos/jwthompson2/139445633/sizes/l/in/photostream/ Slide 20. Ms. Gray car image by Gioxx, http://www.fotopedia.com/items/flickr-3095669284. Mr. White car image by harry_nl, http://www.fotopedia.com/items/flickr-3444637211.http://www.fotopedia.com/items/flickr-3095669284http://www.fotopedia.com/items/flickr-3444637211 Slide 21. Mr. Red car image by Nadir Hashmi, http://www.fotopedia.com/items/flickr-2227623451.http://www.fotopedia.com/items/flickr-2227623451 Slide 38. Two-way communication devices image by HEA Engineering Subject Centre, http://www.flickr.com/photos/22760956@N08/. Smart grid manager image by npslibrarian, http://www.flickr.com/photos/npslibrarian/2104253867/. http://www.flickr.com/photos/22760956@N08/ http://www.flickr.com/photos/npslibrarian/2104253867/ Slide 49. Uniform distribution, http://en.wikipedia.org/wiki/File:Uniform_distribution_PDF.png. Gaussian distribution, http://en.wikipedia.org/wiki/File:Normal_Distribution_PDF.svg.http://en.wikipedia.org/wiki/File:Uniform_distribution_PDF.pnghttp://en.wikipedia.org/wiki/File:Normal_Distribution_PDF.svg