In view of the fast charging and discharging characteristics of the plug-in electric vehicles (PEVs), this paper coordinates PEVs in conventional load frequency control (LFC). To avoid the installation of measurement devices for each PEV, a resilient distributed frequency estimation strategy is presented for PEVs with the frequency measurements taken only at distribution substations. Since the communication links among PEVs are vulnerable to cyber attacks, this strategy integrates a credibility-based intrusion detection unit to distinguish compromised PEVs. Then, a maximal power acquisition algorithm is designed for well-being PEVs, to obtain sufficient power capacity for the frequency regulation. In simulations, we validate the effectiveness of the credibility-based distributed frequency estimation scheme for PEVs under strongly connected interaction topology. Also, we verify the rapidity of LFC with the coordination of well-being PEVs compared with its conventional counterpart.