Loading Impacts of PHUV Electric Jeepney

It is interesting that while the US is looking into the impact of PHEVs on the existing electric grid infrastructure, the Philippines is producing it's own electric vehicles.

http://electric-vehicles-philippines.blogspot.com is a website detailing most of these products. From E-Jeepneys, electric motorcycles and electric tricycles or electric taxicles, they have it all.

Figure 1. PHUV Electric Jeepney (from http://electric-vehicles-philippines.blogspot.com/2010/04/phuv-electric-jeepney.html)

Though IEEE literature have investigated the impact of PHEVS on distribution transformer loading [1-3], Philippine electric vehicles are very different from the studied PHEVs. No literature have studied the local and global effects of these electric vehicles on the Philippine electric power systems.

In this post, loading impact of charging a PHUV Electric Jeepney on a given distribution transformer. Normally, a distribution transformer serves about five to seven households. A typical load curve is provided in Figure 1, taken from reference 4. The load curve is given in MW and was scaled down to kW. The figure also includes capacities of a 25 kVA and a 37.5 kVA distribution transformers. In the figure, neither of the transformer is overloaded.

Figure 2. Typical residential load curve.

From [5], the PHUV Electric Jeepney charging process is provided:

"PHUV batteries amp hour capacity rating is 220 amp hrs. Since they have a 72 volt system, they have 12 pcs of 6 volt deep cycle batteries. That's 16000 watt hours or 16 kilowatt hours at P8 per kwhour (Meralco rate with all the side charges) is equal to P128 or $2.8 per 8 hour full charge. So if it runs for 65 kms then that's 1.97 per km or 5 US cents per km."

To check the calculation, P = V x I ( P = 72 x 220 = 15,840 watts) . Converting it to kW, P = 15.84 kW which is fully charged for 8 hours. Note that 15.84 kW is above half of a 25 kVA transformer capacity and about 42% loading a 37.5 kVA transformer.

Assuming that the PHUV is utilized for public transport from 8am to 5pm, to integrate the PHUV into the load curve above, three scenarios are studied: (1) charge the PHUV from 6 pm to 2 am, (2) charge the PHUV from 1 am to 8 am, and (3) charge the PHUV from 11 pm to 7 am.

Figure 3 shows the load curve with an additional one (1) PHUV charging considering the three charging scenarios cited above. From the figure, a 25 kVA transformer will overload for charging scenario (1) and will be heavily loaded for the other scenarios.

Figure 3. Residential load curve with 1 PHUV charging.

Figure 4 shows the load curve with an additional two (2) PHUV charging considering the three charging scenarios cited above. From the figure, a 25 kVA transformer will be heavily overloaded for all charging scenarios and even the 37.5 kVA distribution transformer will overload for all charging scenarios.

Figure 4. Residential load curve with 2 PHUV charging.

Electric vehicles are good for the environment and will provide a boost in the Philippine economy since they are locally made. However, it is imperative to look into the loading impact of electric vehicles since they will provide distribution transformer overloading if not investigated.

Further analysis will include additional charging scenarios of electric motorcycles and electric tricycles in the mix. Also, a global outlook analysis is needed if the Philippine power grid as a whole can handle the forecasted usage of electric vehicles in the country.

References:

1. Shao, Shengnan; Zhang, Tianshu; Pipattanasomporn, Manisa; Rahman, Saifur; , "Impact of TOU rates on distribution load shapes in a smart grid with PHEV penetration," Transmission and Distribution Conference and Exposition, 2010 IEEE PES, 19-22 April 2010
2.  S. Shao, M. Pipattanasomporn and S. Rahman, "Demand Response as a Load Shaping Tool in an Intelligent Grid with Electric Vehicles”, IEEE Transactions on Smart Grid, vol. 2, No. 4, December 2011, pp. 624-631. 
3.  S. Shao, M. Pipattanasomporn, and S. Rahman,"Challenges of PHEV Penetration to the Residential Distribution Network,"  IEEE/PES 2009 General Meeting, Power & Energy Society General Meeting, 2009. PES '09. IEEE, Calgary, AB, Canada,  July, 27th, 2009.
4. Occidental Mindoro Electric Cooperative, Inc. Information Memorandum. Available: http://www.omeco.com.ph/files/pdf/OMECO%20INFORMATION%20MEMORANDUM.pdf
5. PHUV Electric Jeepney - http://electric-vehicles-philippines.blogspot.com/2010/04/phuv-electric-jeepney.html