# Research on Interval Optimal Scheduling Strategy of Virtual Power Plants with Electric Vehicles
## 5 Example Analysis
### Results of the Algorithm
#### 5.2.3 Typical Scenario Scheduling Scheme  
(1) The most economical scheduling scheme  
The median value of each objective function in the most economical dispatching scheme is shown in Table 5, and the power of each object, system, and grid interaction power is shown in Figure 15. From Figure 15b, it can be seen that the virtual power plant sells electricity to the grid from 7:30 to 8:30 and needs to purchase electricity from the grid at all other times; the charging power of the EV is high in the low power consumption valley and low in the peak power consumption period. Figure 14: Grid load smoothing target. Figure 12: Economic targets. Figure 13: Environmentally friendly targets. The gas turbine operates at higher power during the hours of 19:00 to 6:00 and higher electricity prices; the power-to-gas converts electrical energy to natural gas energy and stores it in the gas storage equipment from 7:00 to 15:00, and converts natural gas energy to electrical energy for load demand during peak electricity consumption periods; the storage equipment needs to be recharged because the electricity consumption is less than the electricity generation when wind power or PV is sufficient, and when the electricity consumption is greater than in the peak electricity consumption period, the electricity storage equipment needs to be discharged; the gas storage equipment transmits natural gas to the natural gas network during the peak natural gas demand period, thus ensuring the maximum economic income of the virtual power plant, i.e., the maximum difference between the income and cost of the virtual power plant selling electricity to the grid. The median value of each objective function in the most environmentally friendly scheduling scheme is shown in Table 6 when the median value of the interval of the environmental friendliness objective is the smallest, and the power of each object and the power of the system interacting with the grid is shown in Figure 16, which shows that the charging power of electric vehicles is higher at night than other time periods. From Figure 13, it can be seen that the system sells electricity to the grid during the period from 7:00 to 8:00, and during all other periods, needs to purchase electricity from the grid. Figure 15: Economically optimal solution. (**a**) Scheduling results of each power supply; (**b**) Interactive power dispatch results with the grid. \begin{table}
\begin{tabular}{c c c} \hline \hline
**Economical Target (Yuan)** & **Environmental Target (kg)** & **Peak-Shaving Target (kW)** \\
**Median of the Interval** & **Median of the Interval** & **Median of the Interval** \\ \hline
6503.16 & 9821.03 & 2402.56 \\ \hline \hline \end{tabular}
\end{table} 
Table 5: Median objective function of economic optimal solution. In this scheme, the gas turbine output is more gentle from 14:00 to 24:00; the power-to-gas equipment output is intermittent, converting natural gas into electricity at the peak of electricity consumption, and converting electricity into natural gas through the storage equipment at the peak of gas consumption, and the power-to-gas equipment effectively converts carbon dioxide into methane, thus reducing greenhouse gas emissions; at the low point of electricity consumption, the storage equipment stores excess electricity generation, and at the peak of electricity consumption, discharges it. Since power purchased from the larger grid is assumed to be coal-fired generation, this scenario reduces the power purchased from the grid to reduce CO2 emissions. (3) Optimal scheduling scheme for grid smoothing objectives  
The median value of each objective function of the optimal scheme for the grid load smoothing objective is shown in Table 7, and the power of each object, system, and grid interaction power is shown in Figure 17, which shows that the electric vehicles are called more at night than the economic and environmental objectives.