## 6 Simulation Results
### Optimal Scheduling for Voltage Control  
The simulations have been conducted in four-case scenarios as follows:  
* Case 1: Without optimization impact evaluation for massive penetration of RESs. * Case 2: Conventional control method by DisCo; the distribution system consists of BESS, OLTCs (LRT, three SVRs), SVCs at each node, DGs (PV and its interfaced inverters) and loads. * Case 3: Coordinated operation under the DR program; DisCo verifies the maximum amount of control equipment reduction. * Case 4: Although this case concludes the coordinated operation of the DR program, unlike Case 3, distribution loss reduction is the main point of view. Figure 6: Scheduling (SC) method for optimal scheduling. Figure 7: PV output and load demand curve. (**a**) PV output and (**b**) load demand profile for each area. The system configurations of each case are indicated in Table 3, and the equipment location is shown in Figure 2. The third and final cases are proposed scenarios, which adopt the reactive power incentive program. Case 2-4 employ the dual scheduling algorithm. Figure 8a-c illustrates the influence of the massive installation of RESs. The dashed line in each figure denotes the acceptable range of the system constraints. Figure 8a shows the voltage deviation from the proper range, and the reverse power flow is confirmed by the negative value, as shown in Figure 8b. The bandwidth of Figure 8c expresses PFlimitations (PF = 0.85); thus, the power quality has not been satisfied under the high penetration without reactive power control. In order to verify the conventional system and control, Case 2 provides the optimal operation schedule of control devices (BESS, SVCs, SVR, OLTCs), and this result is shown in Figure 9. Figure 9a-c shows node voltages, active and reactive power for Case 2. From these plots, it is seen that voltage deviations and reverse power flow are resolved. Furthermore, the proper PF is confirmed by the reactive power flow within the stipulated range from Figure 9c. Control devices' operation is shown in Figure 9d-h. Figure 9d,e illustrates BESS operation of the active, reactive power output and SOC, then, each SVC and OLTC operation is illustrated in Figure 9g,h, respectively. This result indicated the necessary equipment configuration for maintaining system safety and satisfied power quality with optimal operation. The distribution losses are shown in Figure 9i. High distribution losses in the day-time (11-16 h) and night-time (19-24 h) are caused by heavy power flow amounts. In Case 3, DisCo attempted to reduce the investment of control devices by cooperation control from the customer instead of using SVR and SVC controllers. The results in Figure 10 accomplished the effort to reduce the introduction of control devices by supplying the reactive power incentive method for customers. In a similar order as shown in the figures of Case 2, Figure 10a-i shows comparable variables. As opposed to Figure 9g of Case 2, Figure 10g illustrates the coordinated reactive power from the customers with SVCs' output replaced with the output of the PV inverter. The reactive power supply limitation illustrates a curved dashed line because this cooperation was provided by the unused capacity of the PV inverter, which differs from Figure 9g for Case 2. In Figure 10h, the tap operation of LRT is illustrated. It is shown in Figure 10 that the voltage control by cooperative control can reach the proper value of the distribution system (voltages, active and reactive power flow); as shown from Table 3, cooperative achievement has been confirmed, despite the reduction in capacity of the control equipment on the DisCo side and the storage battery. The hourly distribution losses shown in Figure 10i are described after the description of Case 4. Figure 11, which is the result of Case 4, confirms the control contents based on the same configuration as Case 3, except for Figure 10h, which shows three SVRs' support voltage control.