## 5 Case Simulation
### Discussion of Reactive Power Output Ratio by PV Inverter  
The influence of the reactive power output ratio restriction by the PV inverter is discussed. The active power output of the PV operates at the rated power before optimization. It can be optimized together with reactive power, under the circumstance of satisfying the capacity constraint. The reactive power output ratio restriction of the PV can be adjusted from 0.01 to 0.31 by an increment of 0.01, composing 31 scenarios. Each scenario is simulated five times. The results are the average value of the five simulations. NSGA-II is used for solving problems. FIDs with different port numbers are also simulated. The simulation results are shown in Figure 6. The reference value used in Figure 6 is the voltage deviation and network loss without PV reactive power optimization. As seen from Figure 6, with the increase in PV reactive power output ratio restriction, the active power loss of the PV increases. Owing to the objective function of minimizing PV abandonment ratio, the active power loss of the PV cannot increase without limit. The active power loss does not exceed 70 kW. The whole PV rated capacity is 2500 kW. The ratio of PV abandonment is lower than 2.8%. Because the promotion ratio of the PV abandonment ratio is relatively small, the compromised optimal solution tends to the minimization of voltage deviation and network loss. The reduction in network loss increases with the increase in reactive power output ratio restriction. However, it is less than 10 kW. It indicates that the optimization performance for network loss is limited due to the injection point of PV. Figure 6: Optimization result comparison by setting allowed ratio of PV reactive power output. Blue line—FID with two ports; red line—FID with three ports; green line—FID with four ports. (**a**) Active power loss of PV. (**b**) Voltage deviation. (**c**) Reduction in network loss. The voltage deviation is reduced when the reactive power output ratio restriction increases. The injection of reactive power improves the power factor of the distribution line. The voltage loss is reduced, and better power quality is obtained. The optimization results are also compared for different FID port numbers. When the FID port number increases, the active power loss of the PV is substantially unchanged. The reduction in network loss slightly increases. The voltage deviation is obviously reduced, representing better power quality. Comparison of Optimization Operation Results Under Different Reactive Power Output Modes of PV Inverter  
The synergetic optimization of FID and PV under five PV reactive power output modes is simulated. The results are listed in Table 3 and shown in Figure 7. Because the ratio of PV abandonment was analyzed above, it is not listed. It can be seen that the network loss of the different modes is nearly the same. The range of network loss is 0.0043, which is very small. The difference focuses on the voltage deviation. The range of voltage deviation is 0.1217. Different from mode 1, mode 2 can provide reactive power of no more than 0.31 pu during the night. The injection of reactive power during the night reduces both voltage deviation and network loss. Different from mode 2, mode 3 canceled the power factor limitation of the PV inverter during the daytime. The adjustment range of reactive power output is 0.31 pu during the daytime. The voltage deviation and network loss are further reduced. Compared with mode 2, mode 4 utilizes the night SVG scheme for PV inverters. The adjustment range of reactive power output increases to 1 pu. The voltage deviation is reduced from 0.7976 to 0.7253. The drop proportion is 9.06%. The voltage quality is obviously improved. However, due to the injection of reactive power, the network loss is slightly increased from 0.0933 to 0.0970. The overall level of power quality is ameliorated.