1. Problem Statement On power lines with different power sources on both sides, to avoid equipment damage caused by asynchronous parallel operation, the three-phase reclosing on both sides of the line typically employs a synchronization check method and a line no-voltage check method, respectively. Once a transient fault occurs on the line, the protection devices on both sides of the line activate and trip the switches. After the reclosing operation using the line no-voltage check method, if the power sources on both sides of the line have not lost synchronization and can meet the conditions for synchronous parallel operation, then the reclosing operation using the synchronization check method will close the switch on that side, restoring power supply to the line. Clearly, a necessary condition for successful line reclosing is that the power sources on both sides can maintain synchronous operation after the line fault is disconnected. However, for most small power plants operating in grid connection, since they typically adopt a single-line, single-channel grid connection method, the possibility of an isolated small power plant maintaining synchronization with the system after the tie line trips is extremely low. Therefore, after a line fault, the reclosing success rate is close to zero. In this case, the reclosing is essentially useless. If the tie line has a large switching capacity before a line fault occurs, then after the tie line is disconnected and the system is disconnected, the isolated system where the small power plant is located will experience a large power surplus (when the small power plant sends power out through the tie line) or deficit (when the small power plant receives power through the tie line), which will greatly affect the power supply quality of the isolated system, and in severe cases, may lead to power outages or even damage to electrical equipment. Therefore, to improve the reliability of power supply, it is necessary to study other reclosing methods. In some cases, using busbar-detection-free reclosing instead of synchronization-detection-free reclosing is a good option. 2 Application of Busbar-Detection-Free Reclosing As shown in Figure 1, the small power plant G is connected to system S via tie line l1, the busbar of substation B, and line l2. Simultaneously, substation B supplies power to load P. Since the tripping of tie line L1 does not affect the system's power supply to substation B, the reclosing methods on both sides remain as traditionally configured. The reclosing on the substation side uses a line-no-voltage detection method, while the reclosing on the power plant side uses a synchronization detection method (given the low expected success rate of reclosing on this side, it can also be discontinued). Line L2 provides a grid connection channel for power plant G and also supplies power to substation B along with it. When L2 trips, small power plant G is disconnected from system S. If small power plant G supplies power to load P of substation B alone, as mentioned earlier, when there is a large power difference between the output of power plant G and load P, the power quality of the islanded system will not meet the requirements of load P. The result may be that the small power plant's underfrequency and undervoltage disconnection protection trips, causing the disconnection point switch to open, resulting in a complete power loss for load P; or the underfrequency load shedding device installed in substation B will activate, disconnecting part of the load. In either case, the power supply reliability of load P will be significantly reduced, which should be avoided as much as possible. Therefore, the reclosing of line L2 should not use the same method as that of tie line L1. If the reclosing of line L2 on the substation side (load side) is set to detect busbar de-voltage, the reclosing of its system side (power supply side) should still be set to detect line de-voltage. When a transient fault occurs on line L2 and the switches on both sides of the line trip due to protection, the reclosing of line L2 on the system side will close its own switch after detecting line de-voltage (indicating that the switch on the opposite side has tripped) and after a set time limit; at the same time, the reclosing of line L2 on the substation side will also close its own switch after detecting substation busbar de-voltage (indicating that the small power plant tripping protection has acted and the tripping point switch has tripped) and after a set time limit. In this way, power can continue to be supplied to the load P of substation B, significantly improving its power supply reliability. To prevent the failure of the small power plant tripping protection from affecting the success rate of the reclosing of line L2 on the substation side using the busbar de-voltage detection method, a circuit can be added to the protection on the substation side of line L2 to trip the switch on the substation side of line L1. In this way, if a fault occurs at L2, the substation-side protection will not only trip its own switch but also the L1 substation-side switch, thus ensuring that the L2 substation-side busbar-based reclosing under no-voltage detection can successfully reclose. 3. Implementation of the Busbar-Based No-Voltage Detection Reclosing Device The commonly referred to no-voltage detection reclosing refers to reclosing under no-voltage detection of the line. A voltage on the line side (introduced to the reclosing device by the line PT) less than a set value is a necessary condition for its activation. The busbar-based no-voltage detection reclosing discussed in this paper uses the voltage of the busbar at the reclosing device installation location as the detection object—a busbar voltage less than a set value is a necessary condition for the reclosing to activate. As shown in Figure 2, using busbar-based no-voltage detection reclosing does not require modification of the conventional reclosing device itself; only the terminals originally connected to the line voltage within the device need to be reconnected to the busbar voltage. During the reclosing device setting, conventional no-voltage detection reclosing can still be performed, and since the line PT can be eliminated, implementation is very convenient. Furthermore, when using the busbar-no-voltage reclosing method, since reclosing is only possible after all other power supply incoming switches on the busbar have tripped, similar to the reclosing method using synchronization detection, the post-acceleration stage of this side's protection can be disabled. 4. Conclusion Installing busbar-no-voltage reclosing on switches near the load side of certain lines in small power grid connection channels can effectively improve the reliability of power supply to the load. This reclosing method has been adopted on four 110 kV interconnected lines in the Nantong power grid, and its operation is satisfactory.