## 5 Simulation Cases  
### Simulation Model and Parameters  
The simulation cases in this paper are based on a two-area interconnected system, which contains DFIGs, EV cluster, conventional units, and random loads, as shown in Figure 8. All the simulation results are based on the data of Area 1. In the system model, \(M\) and \(D\) are the inertia constant and damping coefficient of the generator, respectively; \(1/(s+T_{delay})\) represents the delay effect of system control and communication, and \(T_{delay}\) is called the system time delay constant. The load frequency control (LFC) blocks in two areas adopt the combination mode of tie-line bias control (TBC), i.e., TBC-TBC mode [23], and the system FR task signal is obtained by proportional-integral (PI) control. The conventional unit block adopts the model of traditional thermal power unit [24].  
The parameters of the system model are listed in Table 4[25]. The parameters of DFIG are listed in Table 5[26], and the model of DFIGs in two areas are the same. The parameters of EV are listed in Table 6. The driving behaviors and SOC changes of individual EVs are simulated by the Monte Carlo method. By reference to Beijing transport annual report [27], it is assumed that the time of arrival at workplace and time of departure from workplace obey the normal distribution, and the driving distance obeys the lognormal distribution. The system rated frequency \(f_{0}\) is 50 Hz. In the simulation results, the base value for the calculation of per-unit value is set to be 5 MW.  
In the system model, the load fluctuation and WS are simulated through white noise by reference to Ref. [14]. The profiles of load fluctuation and WS in two areas are shown in Figure 9a,b, respectively. In the figure, \"p.u.\" is the abbreviation for per unit, which means the variable is represented in the form of per-unit value.  
Figure 7: Flow chart of the coordination of DFIG (double-fed induction generator) and EV (electric vehicle) in FR (frequency regulation). EVA: EV aggregator.  
\begin{table}
\begin{tabular}{c c c} \hline \hline
**Parameter Name** & **Area 1** & **Area 2** \\ \hline Generator inertia constant \(M\) (s) & 6.23 & 5.77 \\ Load damping coefficient \(D\) (p.u.) & 0.87 & 1.23 \\ Governor speed regulation factor (p.u.) & 0.12 & 0.08 \\ Governor time constant (s) & 0.23 & 0.27 \\ Turbine time constant (s) & 0.56 & 0.45 \\ Frequency deviation factor (p.u.) & 4.89 & 5.12 \\ ACE calculation time constant (s) & 2 & 2 \\ Network-induced delay (s) & 1 & \\ Tie-line synchronization factor \(T\) (p.u.) & 2 & \\ System time delay constant \(T_{delay}\) (s) & 1 & \\ \hline \hline \end{tabular} ACE: area control error.  
\end{table}
Table 4: Parameters of the two-area interconnected system model.  
Figure 8: Two-area interconnected system model. LFC: load frequency control; EVA: electric vehicle aggregator; DFIG: double-fed induction generator.  
\begin{table}
\begin{tabular}{c c} \hline \hline
**Parameter Name** & **Parameter Value** \\ \hline Power factor & 1 \\ Polar number & 3 \\ Rated power & 5 MW \\ Rated speed & 1000 rpm \\ Gearbox transmission ratio \(n\) & 100 \\ Blade radius \(R\) & 60 m \\ Inertia constant & 1.12 s \\ The optimal tip-speed ratio & 6.325 \\ Pitch angle change rate limit & \(\pm 8^{\circ}\)/s \\ Cut-in speed & 4 m/s \\ Rated wind speed & 11.8 m/s \\ Cut-out speed & 25 m/s \\ \hline \hline \end{tabular}
\end{table}
Table 5: Parameters of DFIG (double-fed induction generator).