$25. 002009 ieee 52 ieee

figure 6.

 Charging load of electric vehicles.

---

march/april 2009 

IEEE

 

power & energy magazine  

59

enable DR to reach its promised poten-

tial. Some ISOs and RTOs are taking 

the  approach  of  treating  DR  simply 

as negative generation and imposing 

the existing tariffs and technology re-

quirements on DR resources. 

Can Plug-in Vehicles 

Help in Load Shaping?

Plug-in vehicles and other distributed re-

sources will offer capabilities that can be 

used for shaping the distribution system 

load. As illustrated in Figure 7, car batter-

ies, when treated in an aggregated fash-

ion, represent a considerable level of dis-

tributed storage capability. Furthermore 

PHEV and PEV batteries are designed 

for fast discharge to provide for rapid car 

acceleration and other driving conditions 

that need a burst of power. Thus, parked 

PHEVs and PEVs with Vehicle-to-Grid 

(V2G) capability in a given area can alleviate localized distribu-

tion system overload problems. Moreover, if a group of parked 

cars with V2G capability are aggregated, they can provide 

ramping and regulation in support of the power grid. Ancillary 

services markets, on the other hand, are well-suited for batteries 

since spin and nonspin reserve markets require quick response 

times with low total energy demand. A recent demonstration 

project has successfully shown V2G capabilities supplying an-

cillary services, including real-time frequency regulation, in 

the PJM Interconnection  market. The 

project successfully connected a plug-

in vehicle with 19-kW V2G  

capability 

to PJM’s Automatic Generation Control 

(AGC) signal and demonstrated the bat-

tery’s ability to closely follow the regula-

tion control signal for regulation-up and 

regulation-down requests. Frequency 

regulation,  when  compared  with  other 

market products,  

provides the highest 

market value at about $30 to $45/MW 

per hour; spinning reserve provides 

the second-highest value at $10/MW 

per hour. The primary revenue in both 

of these ancillary service markets is for 

capacity rather than energy.

It should be pointed out, however, 

that the design of many of the early 

PHEVs and PEVs allows only for a 

one-way fl ow of charge, and exces-

sive cycling of a plug-in car battery 

may drastically shorten the life of the battery.