## 4 Simulation Results
### Financial Impacts for Power Producers and the Retailer  
Following the calculation of the market prices under each pricing scheme, the power purchase costs, generation costs, revenues, and profits must be quantified to assess the financial impact on power producers and the retailer. These quantitative indicators can be calculated using the results of the market-clearing models and the pricing mechanisms described in the previous subsection. In this study, the single retailer was assumed to purchase electricity at the market price corresponding to its specific area. Accordingly, the retailer's power purchase cost is defined in Equation (9) as the product of the demand and market price at the respective zone or node, depending on the pricing scheme. The generation costs of the power producers, including fuel and start-up costs, are expressed as Equation (10). Energy revenue is defined in Equation (11) as the product of the market price and generation output determined by the market-clearing model. Furthermore, the MWPs, which compensate for deficits in generation costs, are determined by Equation (12) as the difference between energy revenues and generation costs per hour. Finally, the profit of power producers is expressed in Equation (13) as the sum of the energy revenues and MWPs minus the generation costs. Figure 8: Comparison of Nodal (ELMP) and Uniform (SMP) prices for individual generators. If the generators receive MWPs, their profit during those specific operating hours is zero. The following equations define the calculations:  
\[PowerPurchaseCost_{i,t}=\pi_{i,t}\times D_{i,t} \tag{9}\]  
\[GenerationCost_{g,t}=\left(C_{g}^{QD}p_{g,t}^{2}+C_{g}^{LN}p_{g,t}+C_{g}^{NL}x_{g,t }\right)+C_{g}^{SU}y_{g,t} \tag{10}\]  
\[EnergyRevenues_{g,t}=\pi_{g,t}\times p_{g,t} \tag{11}\]  
\[MWP_{g,t}=-min\left(0,EnergyRevenues_{g,t}-GenerationCost_{g,t}\right) \tag{12}\]  
\[Profit_{g,t}=EnergyRevenues_{g,t}+MWP_{g,t}-GenerationCost_{g,t} \tag{13}\]  
where \(\pi_{i,t}\) is the market price in area \(i\) at time \(t\), and \(\pi_{g,t}\) denotes the market price received by generator \(g\) at time \(t\). Based on these definitions, the comparative financial effects between uniform and zonal pricing and between uniform and nodal pricing are presented in Tables 9 and 10, respectively. For a more detailed examination of the financial effects across pricing schemes at the zonal level, please refer to Appendix B. The results for power purchase costs, energy revenues, and profits followed a trend similar to that of the market prices discussed in the previous section. This trend can be summarized as: Uniform (SMP) > Nodal (ELMP) \(\approx\) 2-Zonal (SMP) > Nodal (LMP) \(\approx\) 5-Zonal (FBMC, ZMP) \(\approx\) 5-Zonal (ATC, ZMP) \(\approx\) 2-Zonal (ZMP). However, the MWP exhibited a trend opposite to that of the market prices. This is because it compensated for deficits in generation costs when energy revenues were insufficient, which resulted in higher MWPs under pricing schemes that yield lower market prices. An analysis of generation costs revealed that while uniform and zonal pricing exhibited minimal differences, nodal pricing resulted in higher generation costs owing to the additional constraints in more granular representation of the network topology at the node level. However, these results did not consider redispatch costs. If such costs \begin{table}
\begin{tabular}{c c c c c} \hline \hline  & **Pricing Scheme** & **Uniform** & \multirow{2}{*}{**Nodal Pricing**} \\  & **(KRW Billion)** & **(SMP)** & **Nodal (LMP)** & **Nodal (ELMP)** \\ \hline \multirow{4}{*}{Power Producers} & \multirow{2}{*}{Power Purchase Cost} & 93,810 & 81,739 & 88,795 \\ \cline{3-5}  & & Generation Cost & 39,317 & 40,863 & 40,863 \\ \cline{1-1} \cline{2-5}  & Energy Revenues & 93,905 & 79,374 & 85,923 \\ \cline{1-1} \cline{2-5}  & Make-Whole Payments & 1592 & 2940 & 2064 \\ \cline{1-1} \cline{2-5}  & Profit & 56,179 & 41,451 & 47,123 \\ \hline \hline \end{tabular}
\end{table} 
Table 10: Comparative financial impacts of uniform and nodal pricing.