# Flexible Dispatch for Integrated Power and Gas Systems Considering Power-to-Gas and Demand Response
## 5 Simulation Results
### System Description and Data Source  
The topology of the test system is shown in Figure 2 The entire system includes six generating units with a total installed capacity of 540 MW. The main parameters are shown in Table 11. The bus 15 and the bus 22 are, respectively, connected to a wind farm with a rated output of 150 MW, and the penalty for wind power curtailment is set at 500 $/(MWh). The gas-fired units G5 and G6 are connected to node 6 and node 10 of the natural gas system respectively. The two P2G facilities are also installed at the bus 22 and bus 15. The maximum/minimum conversion power is 30 MW and 5 MW, and the operating cost is set to 80 $/(MWh). In the gas system, there are two gas wells W1 and W2, two storage facilities S1 and S2, three compressors, six pipelines, and five gas loads. The detailed parameters of the gas sources and storage facilities can be obtained from Tables 12 and 13. The P2G operation cost, and penalty cost of not-served gas loads are set as 80 $/(MWh) and 200 $/kcf, respectively. Forecast values of electrical load, gas load and wind generation are shown in Figure 3 with peak values of 504.73 MW, 12,816.52 kcf, and 175.84 MW, respectively. system, the P2G facilities also provide a new way for the consumption of wind power during the trough of the electrical load, which greatly improves the downward scheduling flexibility and operating economy of the power system. In order to discuss the impact of P2G facilities on flexible and economical dispatching of the power system, the part on demand response is deleted here, and the following two schemes are set for comparison and analysis:  
Case1: Does not include P2G facilities. Case2: P2G facilities participate in power scheduling and adjustable capacity configuration. The scheduling results of the power system under the two cases are shown in Table 1, and the corresponding unit output curve is shown in Figure 4. And Figure 5 shows the downward adjustable capacity of the power  
It can be seen from Figure 4 that during the trough period of the electric load (1:00-6:00), due to the large wind power output, only the coal-fired units G1 and G3 are in working state in the Case1, and the output is close to the minimum output. The Case1 is similar to the Case2, but considering that the P2G facilities participate in power dispatching and adjustable capacity allocation, they increase the load of the power system during the trough period, and also provide a part of the adjustable capacity for the unit. As a result, in the process of formulating the power generation plan of the units, the coal-fired units G1 and G2 with lower power generation costs are preferentially used to provide power services. Comparing the scheduling results of the two cases in Table 1, it can be found that the generating cost and adjustable capacity allocation cost of the units in Case2 are, respectively, reduced by 6065 and 4508 compared with Case1, which ultimately reduces the total cost of the power system by 4.15%. Observing Figure 5a, it can be seen that Case1 does not include P2G facilities. During the low load period (1:00-6:00), the system's downward adjustable capacity is mainly provided by units G1 and G3. Since the adjustable capacity provided by units G1 and G3 cannot meet the fluctuations and randomness of wind power and load. As a result, the downward adjustable capacity of 7.48 MWh and 7.08 MWh was provided to the power system through wind power curtailment at 3:00 and 6:00, respectively. In Figure 5b, Case2 provided 6.96 MW and 6.16 MW of downward adjustable capacity to the power system through the P2G facility during these two periods, so that the wind power curtailment of the power system was reduced to 0. From the above results, it is not difficult to see that P2G facilities have advantages that cannot be ignored in improving dispatching economy and renewable energy consumption, while providing the system with flexible adjustable capacity.