* Power distribution becomes an important issue when power demand exceeds power supply. * As electric vehicles get more popular, for a period of time, there could be a shortage of power generating facilities. In order to allow the use of electric vehicles grow at a normal rate, it is necessary to look for some techniques to charge all vehicles as fairly as possible. * Our objective is to find out and compare different types of fairness schemes so as to meet the customers’ needs to a great extent.

WeekTasks 1, 2, (Jan 30 – Feb 10) Background reading and literature review 3,4, (Feb 13 – Feb 24) Simulate a baseline charging system 5, 6 (Feb 27 – Mar 9) 8, (Mar 19 – Mar 23) Implement different types of fairness; Each of us is responsible for one specific fairness scheme. 9,10, (Mar 26 – Apr 6) Compare the results and make some conclusions. 11,12,13, (Apr 9 – Apr 27) Write a technical paper.

1. Set up simulation environment: * information of electric vehicles * charging habits * power on smart grid 2. Realize the basic fairness scheme – Round Robin 3. Obtain some results using two metrics: * the fraction of electric vehicles without sufficient charge on departure * the average departure delay

1. Set up information of electric vehicles * Battery limit: 100 miles – 28kwh * Charge mode: 120V 15A – 1.8kw or nearly 6.5miles at maximum power

1. Set up charging habits * Total number of person leaving home to go to work every half hour during a day  time shift (8am corresponds to 6pm) * The arrival of electric vehicles is poison process: arrival rate  interarrival time satisfies exponential distribution. * Plug-in time for an electric vehicle is Gaussian distribution truncated to 2 deltas. (mean=14 delta=4, unit: hour) * The departure process is obtained accordingly.

1. Set up charging habits – contd. * Desired distance satisfies exponential distribution truncated to [20, 90] miles  desired energy * Current battery level is uniformly distributed between 0% to 30% of full battery energy. * Energy needed is calculated based on demand  the amount of charging periods (5 minute switch on/off intervals) for each electric vehicle

1. Set up power * Summer daily load profile sampled hourly.

2. Realize the basic fairness scheme – Round Robin * Round Robin based system works in the way that – If 20 cars waited to be charged, and the power company can merely charge 15, then in the first 5 minute it will charge cars 1 to 15, in the second cars 16 to 20 and 1 to 10, in the third cars 11 to 20 and 1 to 5, and so on so forth. * Eventually each car receives the same charge. * In real implementation, run round robin every 5 minute to achieve real-time coordination. * Two cases: sufficient power/ insufficient power for all cars in the waiting list

2. Round Robin algorithm * Create a waiting list based upon arriving times of the cars that need to be charged. * Check which of the two cases applied. * Charge a fixed number of cars in the front of the waiting list. * Update the cars’ information. * Update the waiting list: adding new arrivals, removing the cars that finish charging and reordering the waiting list.