## 6 Conclusions and Future Work  
This paper proposed an innovative coordinated operation framework for natural gas and electricity networks to effectively solve the optimization problem of the operation of integrated gas and electricity systems. The modeling approach developed is applied to demonstrate the benefits of an integrated approach to the operation of interdependent gas and electricity systems. In addition, the novel coordinated operation framework changes the traditional decision sequence. GNO as an advance decision-maker provides NGFUs gas consumption constraints to ENO. With this framework, it is possible to avoid frequent information interaction and without a third coordinator. This framework will not affect the local optimal scheduling for both the electricity network and the natural gas network. The modeling indicates that, in pipeline congestion situations, this framework for CO reduces the impact on the electricity network as compared to that of DO. At the same time, it improves DR program acceptance of electricity networks and prevents massive load shedding. The proposed framework can produce more cost-effective solutions as compared to other methods, such as ADMM. It was demonstrated that CO with demand response can reduce the electricity network total cost by 1.19% when pipeline congestion occurs, as compared to \(-\)0.48% using traditional decentralized operation with demand response.  
Future work will investigate the application of a coordinated operation framework to a very large-scale, multi-area system with gas and electricity networks managed by different operators. Sensitivity analysis of credit rank will also be studied in detail. The credit rank will be further developed to form in the hope of a guideline or recommended practices. Gas storage in the view of technical, economic, social, and environmental aspects will be looked at.  
Conceptualization, C.S.L., X.L. and L.L.L.; methodology, C.S.L., M.Y., L.L.L. and Y.X.; software, Y.X.; formal analysis, C.S.L., M.Y. and Y.X.; investigation, C.S.L., M.Y. and Y.X.; resources, C.S.L., X.L. and L.L.L.; data curation, C.S.L. and Y.X.; writing--original draft preparation, C.S.L., L.L.L. and Y.X.; writing--review and editing, C.S.L., X.L., and L.L.L.; supervision, L.L.L.;  
\begin{table}
\begin{tabular}{c c c c c} \hline \hline  & \multicolumn{2}{c}{**Decentralized Operation**} & \multicolumn{2}{c}{**Coordinated Operation**} \\ \hline  & **Without DR** & **With DR** & **Without DR** & **With DR** \\ \hline Without & & & & \\ pipelines & 1708547.2 \$ & 1687651.1 \$ & 1708547.2 \$ & 1687645.0 \$ \\ congestion & & & & \\ \hline Pipelines & 1762052.3 \$ & 1770473.1 \$ & 1721257.2 \$ & 1700798.7 \$ \\ congestion & & & & \\ \hline \hline \end{tabular}
\end{table}
Table 6: The total cost of the electricity network.  
project administration, X.L.; funding acquisition, X.L. and L.L.L. All authors have read and agreed to the published version of the manuscript.  
The work is sponsored by the Department of Finance and Education of Guangdong Province 2016 [202]: Key Discipline Construction Program, China; and the Education Department of Guangdong Province: New and Integrated Energy System Theory and Technology Research Group [Project Number 2016 KCXTD022].  
Not applicable.  
The authors declare no conflict of interest.