When High-Impedance Grounded Faults (HIGFs) occur in Low-Resistance Grounded Systems (LRGSs), it is difficult to locate the fault reliably, because of its small fault current. Symmetrical components and a current branching coefficient are used to analyze the characteristics of three-phase current power frequency variations. The analysis shows that the current power frequency variation in the faulty phase of upstream fault points is much larger than that of healthy phases, while the current power frequency variations in the hree-phase of downstream fault points and healthy lines are approximately the same. From this, a highly sensitive HIGFs location method based on the phase current power frequency variation ratio is proposed. A large number of simulations developed on platform PSCAD/EMTDC indicate that the proposed method can locate the fault quickly and reliably, even when the fault impedance value reaches 2 000 Ω. It only uses the current signal, and this is easy to implement. This work is supported by the Natural Science Foundation of Guangdong Province (No. 2021A1515010631).