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With the access of small hydro-power stations (SHS), the distribution system presents a multiple power supply pattern, which has a negative impact on the original local feeder automation (LFA) which is suitable for single side power supply system. In view of this effect, the phase to phase short-circuit fault (PPF) and single-phase grounding fault (SPGF) are treated differently, and an improved LFA method (IMLFA) considering SHS’s access based on low-frequency load shedding (LFLS) and high-frequency generator tripping (HFGT) is proposed. In case of SPGF, the section switch (SSW) and the outgoing circuit breaker of the substation shall be opened in sequence, and the isolated network (IN) generated in the process can be operated stably by cooperating with LFLS or HFGT while the fault is preliminary isolated. The SSW and the breaker are added with the function of no-voltage detection and synchronization detection. In case of instantaneous fault, the power supply in the fault area can be restored after a series of operations, and the IN can be connected to the grid. If it is a permanent fault, the section switches (SSWs) around the fault area will be locked to close in order to isolate the fault effectively, and the IN, not separated by the fault area from the grid, can be connected to the grid. Analysis and simulation show that the method is correct and feasible.

The access to distributed power sources such as small hydropower (SHP) makes the distribution system present a multi-power supply pattern, which has an adverse impact on the voltage-time type feeder automation (VTFA) suitable for a one-side power supply system. In view of this influence, this paper proposes a new type of feeder terminal unit (FTU) for VTFA, which has a new energy access processing mode. In this mode, in case of phase-to-phase short-circuit fault (PTPF) or single-phase grounding fault(SPGF) in the system, after the feeder’s outlet circuit breaker (OCB) of the substation trips, the FTU shall be able to make the corresponding switch to cut off SHP as soon as possible before the OCB’s re-closing, so as to prevent affecting the realization of VTFA. To verify that VTFA equipped with the new type of FTU can still work normally under SHP access, a feeder automation (FA) test platform is built based on RTDS, and the test results show that the expected goal is achieved.

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