This study presents a non‐communication based algorithm for detection of secondary arc extinction for adaptive single phase auto‐reclosing of transmission lines. The algorithm is based on the behaviour pattern of the faulted phase voltage magnitude (VM) measured at the near end of the line. A prediction function is used to calculate the present VM few milliseconds in advance of its actual measurement. The difference between the actual and calculated values of the faulted phase VM is used as a criterion for detection of secondary arc extinction. A new method is proposed to analyse the arc extinction criterion which does not need a predefined threshold level. The algorithm uses low sampling frequency and is simple and fast. The algorithm can be applied on all transmission line configurations (transposed or untransposed) with different levels of reactive power compensation. The algorithm has been validated using the electromagnetic transient program software tool for simulation studies under many operational and fault cases. The presented test results for 465 cases verify the algorithm performance, which is not affected by the pre‐fault line loading, the circuit breaker opening angle, arc type and fault location.

This paper presents a reliable and fast index to detect the instant of arc extinction for adaptive single-pole automatic reclosing (ASPAR). The proposed method is a simple technique for ASPAR on shunt compensated transmission lines using the Hilbert–Huang Transform (HHT). The HHT method is a combination of the empirical mode decomposition (EMD) and the Hilbert transform (HT). The first intrinsic mode function (IMF1) decomposed by EMD, which contains high frequencies of the faulty phase voltage, was used to calculate the proposed index. HT calculates the first IMF spectrum in the time-frequency domain. The presented index is the sum of all frequency contents below 55 Hz, which remains very low until the fault clearance. The proposed method uses a global threshold level and therefore no adjustment is needed for different transmission systems. This method is effective for various system configurations including different fault locations, line loading, and various shunt reactor configurations, designs, compensation rates, and placement. The performance of the method was verified using 324 test cases simulated in electromagnetic transient program (EMTP) related to a 345 kV transmission line. For all the test cases, the algorithm successfully operated with an average reclosing time delay of 32 ms.

The occurrence of low-frequency electromechanical oscillations is a major problem in the effective operation of power systems. The scrutiny of these oscillations provides substantial information about power system stability and security. In this paper, a new method is introduced based on a combination of synchrosqueezed wavelet transform and the stochastic subspace identification (SSI) algorithm to investigate the low-frequency electromechanical oscillations of large-scale power systems. Then, the estimated modes of the power system are used for the design of the power system stabilizer and the flexible alternating current transmission system (FACTS) device. In this optimization problem, the control parameters are set using a hybrid approach composed of the Prony and residual methods and the modified fruit fly optimization algorithm. The proposed mode estimation method and the controller design are simulated in MATLAB using two test case systems, namely IEEE 2-ar-ea 4-generator and New England-New York 68-bus 16-genera-tor systems. The simulation results demonstrate the high performance of the proposed method in estimation of local and interarea modes, and indicate the improvements in oscillation damping and power system stability.

Geomagnetically induced currents (GICs) in the power system cause half-cycle saturation of the transformers, malfunction of the protective relays, reactive power loss, and voltage instability. A DC Flux Blocker (DFB) that can be installed in series with the power system transformers tertiary windings to neutralize magnetomotive force (mmf) due to GIC is described. The device consists of two circuit breakers and a low power and high current voltage source, which provides the mmf of the GIC DC flux blocking function. The effectiveness of the proposed protective electrical device investigated and validated using the MATLAB software tool. The proposed method can effectively remove the flux due to GIC in both transformers and autotransformers that have tertiary windings. Since the proposed method does not alter the power system topology, it therefore has no effect on protection schemes.

Traditional fault location methods face challenges in grids with high penetration of inverter-based resources (IBRs) due to the non-sinusoidal and distorted nature of the fault currents. This paper presents a fault location method for such grids. It is designed for medium voltage cables, employing sheath current measurements and combining time-domain and phasor-domain analysis. The proposed method addresses the limitations of existing techniques by utilizing low-frequency local measurements. Simulation results on a 10kV test system demonstrate the method’s accuracy, achieving fault location errors below 1.81%. Sensitivity analysis further confirms the method’s robustness against measurement uncertainties. The proposed algorithm’s implementation on an embedded device using IEC 61850-9-2 protocol showcases its practical feasibility for real-time fault location.

Geomagnetically induced currents (GICs) in long high‐voltage transmission lines cause half‐cycle saturation of transformers, malfunction of protective relays, reactive power loss, and voltage instability. This study describes the design for a GIC effects mitigation device (GEMD) that can be installed at a power system autotransformer common node connection to block the flow of GIC DC flux at the cores of the autotransformers. The devices consist of variable resistors, which are controlled by a wide‐area method based on particle swarm optimisation algorithm. The effectiveness of the proposed protective electrical devices is investigated and validated through simulation studies under many operational cases. The test results obtained from 648 cases verify the high performance of GEMD. The proposed method can mitigate the reactive power loss due to GIC in the power system with average improvements by 7.9 and 7.09% over resistive and capacitive blocking devices, respectively.