Abstract: Distance relays are prone to symmetrical power swing phenomenon. To mitigate this issue, a dynamic threshold-supported algorithm is proposed. A single logic is not supposed to be secure for all cases. Thus, a supervisory algorithm, as proposed in this study, can aid in the improvement of the immunity of the relay during swing cases and be sensitive to symmetrical faults. In the developed stages, a three-phase power signal was used and processed in two different steps: (i) extraction of the effective intrinsic mode function (IMF) selected from the Kurtosis analysis using the wavelet synchro-squeezing transform, and (ii) estimation of the average Euclidean distance index using the absolute values of the decomposed IMF’s. The adaptive threshold facilitated resistance to swing situations. At the onset of a symmetrical fault, the proposed algorithm efficiently discriminated among events using a dynamic threshold. The IEEE 39-bus test system and Indian Eastern Power Grid networks were modelled using PSCAD software, and cases were generated to test the efficacy of the method. The impact of the proposed method on a large-scale wind farm was also evaluated. A comparative analysis with other existing methods revealed the security and dependability of the proposed method.

Key words: Distance relays, symmetrical power swing, wind farm, wavelet synchro-squeezing transform (WSST), Euclidean distance