6.1.1. Simulation Model

According to di fferent generator types, the carbon emission rate δ*sw* of each unit in the IEEE 118-bus system is summarized in Table 2. Besides, this paper adopts the same benchmark model of IEEE 118-bus system in all case studies, related detail parameters can be referenced in [36].

Moreover, the system load of the IEEE 118-bus system is mainly divided into five scenarios, as shown in Table 3. Particularly, the scenarios from 1 to 5 represent the system with di fferent load demands, where the load demand gradually increases from scenarios 1 to 5 for all the presented nodes in Table 3. As mentioned above, Tables 2 and 3 are obtained under the same benchmark model of IEEE 118-bus system [36].

In fact, reactive power compensation can be designed for the nodes with generators or load demand to provide adequate reactive power, while the OLTC ratio can be selected for the line with two di fferent voltage nodes. According to this rule, the reactive power compensation of nodes 45, 79, and 105, and the OLTC ratio of lines 8–5, 26–25, 30–17, 63–59, and 64–61 are respectively selected as controllable variables, which are defined in sequence as (*<sup>x</sup>*1, *x*2, *x*3, *x*4, *x*5, *x*6, *x*7, *x*8), with


Hence, the optimization variables of the IEEE 118-bus system can be found in Table 4, where the variables can be divided into two types, i.e., the reactive power compensation and OLTC ratio; the "no. of bus" represents the location of each variable in the power network; the "action space" denotes the set of the alternative control actions for each variable; and the "variable number" is the number of all the optimization variables.


**Table 2.** Carbon emission rate of the IEEE 118-bus system.

**Table 3.** Load statistical conditions employed in five scenarios.


**Table 4.** Optimization variables of the IEEE 118-bus system.

