## 3 Analysis of Dispatchability on EGCS
### Evaluation Index of Dispatchability on EGCS  
The dispatchability indexes of the traditional power system usually include parameters such as adjustable power range, output, or load regulation rate. For EGCS, the concept of dispatchability can be analogized, and the supply and demand of dispatchability of power side, network side, and load side can be quantitatively analyzed. (1) Dispatchability analysis of conventional power  
The conventional power included in the EGCS studied in this paper include thermal power units and gas units, which are the main dispatching supply resources in the system. The upward/downward dispatchability is respectively \(F_{G+}\) and \(F_{G-}\), as shown in Equations (7) and (8):  
\[F_{G+}=P_{Gmax}-P_{G}, \tag{7}\]  
Figure 6: The multi-dimensional attribute of EGCS. \[F_{\text{G--}}=P_{\text{G}}-P_{\text{Gmin}}, \tag{8}\]  
where \(P_{G}\) is the real-time output of the unit. \(P_{\text{Gmax}}\) and \(P_{\text{Gmin}}\) are, respectively, the maximum and minimum output of the unit. The sum of Equations (7) and (8) can obtain the total amount of dispatching resources \(F_{G}\) that can be provided by conventional units, as shown in Equation (9):  
\[F_{\text{G}}=P_{\text{Gmax}}-P_{\text{Gmin}}. \tag{9}\]  
(2) ispatchability analysis of distributed energy  
Distributed energy such as wind and photovoltaic cannot be as stable and controllable as conventional power. Therefore, in the process of power balance, the output of the distributed energy is equivalent to the conventional power according to the given confidence capacity, while the remaining part is the un confidence capacity caused by the prediction error, which consumes the dispatchable resources. Therefore, the dispatching resources that are provided and consumed are as shown Equations (10) and (11):  
\[F_{\text{res,}t}=P_{\text{cl,}t} \tag{10}\]  
\[D_{\text{res,}t}=P_{\text{res,}t}-P_{\text{cl,}t} \tag{11}\]  
where \(F_{\text{res,}t}\) is the dispatchability that renewable energy can provide in \(t\)th period. \(P_{\text{cl,}t}\) is the confidence capacity. in \(t\)th period. \(D_{\text{res,}t}\) is the dispatchability of renewable energy consumption in \(t\)th period. \(P_{\text{res,}t}\) is the output power of renewable energy in \(t\)th period. (3) Dispatchability analysis of controllable load  
The controllable load can be regarded as a \"conventional power\" on the load side because of the load's ability to be artificially adjusted. The dispatchability provided can be calculated according to Equation (9). (4) Dispatchability analysis of uncontrollable load  
The uncontrollable load is a resource that consumes dispatchability. Usually, the system will reserve a part of the backup capacity according to the historical maximum load when setting up the start-up mode, and the backup coefficient will be expressed as \(\mu\). The load's demand for dispatching resources is shown in Equation (12):  
\[D_{\text{load}}=\mu P_{\text{load,max}}+(P_{\text{load,max}}-P_{\text{load, min}}) \tag{12}\]  
where \(D_{\text{load}}\) is the dispatchability of uncontrollable load consumption. \(P_{\text{load,max}}\) and \(P_{\text{load,min}}\) are, respectively, peak and valley values of day-ahead load forecasting. (5) Dispatchability analysis of network side energy conversion  
There are different types of energy conversion on the network side of EGCS. Take P2G as an example. When the natural gas capacity in the network is insufficient and the electricity is surplus, the energy can be converted to natural gas through the energy conversion device. At this time, power can be regarded as the source side energy. The power's dispatchability analysis is similar to the conventional power dispatchability analysis, there is a problem of energy conversion efficiency because the network side energy conversion is a conversion between different energy sources. Therefore, the dispatchability calculation of network side energy conversion in the link of P2G is shown in Equation (13).