*5.3. Effect of Ground Resistor*

A different ground resistor has an effect on the magnitude of transient signals, which will affect the accuracy of the protection actions. Here, the performance of the proposed method in dealing with PPF, PGF, LF, and AG-AC is discussed. Figure 17 shows the influence of the ground resistor on the action accuracy. As demonstrated by Figure 17, when the ground resistor is smaller than 50 Ω, the proposed method is immune to the change in ground resistor. However, with the increase in ground resistor, the fluctuation of high-frequency components of the transient currents becomes less obvious, which mean less disorder in high-frequency bands, and decreases. For internal faults, the values of W4 and W3 will decrease, and misoperations of protection will be found. However, for external faults, such as AG-AC, the criterion W5 = 0 is not affected. The judgment of external faults is still effective.

**Figure 17.** The influence of ground resistor on the action accuracy.
