In, a queueing network of EVs was modeled to estimate the capacity for regulation up during under-frequency and regulation down during over-frequency. In, an approach for estimating achievable power capacity was proposed in a probabilistic manner, where capacity probability distribution was obtained by classifying EV groups and analyzing historical data. However, the capacity of an EV fleet varies, which increases the difficulty of evaluation. To ensure the success of frequency regulation, the capacity of EVs should be accurately evaluated. Therefore, it is necessary to discuss and compare ACE and ARR for EVs’ participation in regulation. Almost all existing researches have focused on area control error (ACE), while in real power systems, area regulation requirement (ARR) is considered in the automatic generation control (AGC) system. However, in practice, the maximum V2G power cannot represent the real capacity of an EV for regulation, because the capacity of an EV for regulation will vary in real time along with the variation of the charging/discharging power. In, high frequency signal was designed for the control center to dispatch the regulation to EVs, but the maximum V2G power was considered as the capacity for regulation. In, the economics of V2G providing regulation services, spinning services, and peak power were analyzed. In, an aggregator of EVs was considered to make efficient use of EVs’ distributed power to perform optimal dispatch. EVs can also be considered as a kind of regulating resource to take part in supplementary frequency regulation. A primary frequency regulation using EVs was addressed by adaptive droop control in. In, an energy management algorithm was proposed for EVs to reduce the peak load and simultaneously perform frequency regulation. Because of the fast response characteristics, EV fleet participating in frequency regulation has a natural advantage over other ancillary services. In particular, grid frequency regulation has been paid significant attentions.įrequency, as one of the most important indexes of power system operation must be controlled within the allowable limits by regulating power sources such as generators. Since then, V2G has shown great applications such as voltage regulation, spinning reserve, load peak shifting, and frequency regulation. In 1997, Kempton and Letendre firstly proposed the concept of vehicle to grid (V2G). However, the EV batteries, as mobile energy storage devices, can be considered for providing support for the power grid. For instance, large-scale disordered charging can aggravate the peak load level, increase the burden on power lines, and damage the safety of grid operation. The large-scale integration of EVs into power grids poses a great challenge to power system operation and control due to the randomness and uncertainty of plug-in time and charging demands of EVs. Electric vehicles (EVs) play a vital role in dealing with fossil energy crises and reducing carbon emissions, because they benefit local and global climates.