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• A leakage protection method for low-voltage power supply systems based on flexible regulation of the neutral point voltage is proposed. • A neutral point voltage flexible regulation method of phase potential feedback is proposed. • Using the proposed method, the fault phase to ground voltage can be suppressed to below 0.05 V, and the fault point residual current can be suppressed to below 1 mA. • The proposed method can actively isolate single-phase leakage faults and eliminate potential leakage problems without affecting the power supply of users. • The method proposed can achieve high resistance ground fault protection without affecting the power supply of users. Low-voltage power supply systems, which are very prone to leakage faults, are deep in the customer terminal, and the operation environment is complex. The traditional leakage protection devices applied in TN-S systems cannot isolate single-phase leakage faults while maintaining power supply. Thus, a leakage protection method based on flexible regulation of the neutral point voltage for a low-voltage power supply system is proposed. By extracting the potential of the fault phase, using a single-phase regulating transformer to reverse the voltage applied between the zero line and the protection ground line, and adjusting the ratio of the single-phase regulating transformer to regulate the fault phase to ground voltage, the fault phase to ground voltage is suppressed to 0 V and the leakage fault residual current is eliminated. In the PSCAD/EMTDC simulation environment and in a 10 kV real-type distribution network laboratory, a TN-S system model was built to simulate various fault conditions. The simulation and experimental test results show that the method can actively isolate single-phase leakage faults and eliminate potential leakage problems without affecting the power supply of users. [ABSTRACT FROM AUTHOR]

Traditional fault traveling wave location schemes, which are based on the fault information of only one line, have lower sensitivity and reliability, especially when one or more traveling wave fault location devices (TWFLD) break down, startup fails or an incorrect arrival time of the initial traveling wave is recorded, this will result in the failure of the fault location. Based on the analysis of the propagation characteristics of the fault traveling wave in power grid, a novel power grid fault traveling wave network location method is proposed in this paper. Firstly, the topology of a power grid is analyzed, and the installation principle of TWFLD is presented. Secondly, when the fault occurs on one transmission line, the fault traveling waves travel from the fault point to the whole power grid, and the values of the arrival time of the initial traveling wave is recorded in the substations where the TWFLD are installed. Then the values of the arrival time are analyzed with the information fusion and the fault point is located by using the power grid fault traveling wave network location method. Compared to the existing fault traveling wave location schemes those are based on the fault information of only one line, all correct time information of the whole power grid has been used to calculate the fault distance in this method. Therefore, this method can achieve reliable fault location even when one or more TWFLD break down, startup fails or an incorrect arrival time of the initial traveling wave is recorded. The simulation results match the theoretical analysis well and show that the proposed location method provides not only high accuracy and reliability, but also good economy. These characteristics are beneficial to further enhancement of the practicability of the traveling wave location. [ABSTRACT FROM AUTHOR]

• A method of primary traveling wave inversion combined with EEMD and L 1 -Ls regularization algorithm is proposed, which realizes the accurate detection of traveling wave shape by inverting the measured secondary traveling wave signal. • The inversion primary traveling wave obtained exhibits a remarkable resemblance to the measured primary traveling wave, and the inversion outcomes closely align with the actual waveform. • This method is not affected by the mode aliasing effect and the accuracy of regularization parameters. The fault information of the inversion primary traveling wave obtained by the method has a small error with the measured primary traveling wave. Aiming at the problem of waveform distortion of the secondary traveling wave obtained from the primary traveling wave signal transmitted by the voltage traveling wave sensor, an accurate detection method of voltage traveling wave based on ensemble empirical mode decomposition (EEMD) and L 1 norm least squares regularization is proposed in this paper. Firstly, the forward transfer function model of the specialized voltage traveling wave sensor is established, and the inversion model is derived to analyze the phase frequency and amplitude frequency characteristics of the secondary traveling wave after transmission. EEMD is used to decompose the secondary traveling wave into the intrinsic modal function (IMF) components of different frequency bands. The L 1 norm least square regularization inversion algorithm was used to invert each IMF component. Finally, the IMF' components after inversion are synthesized to obtain the primary traveling wave. Simulation and experimental results demonstrate that the proposed method is not affected by noise, mode aliasing effect and regularization parameter accuracy, and the obtained waveform has high similarity to the simulated waveform, which enables precise identification of fault traveling wave. [ABSTRACT FROM AUTHOR]

• A novel detection method for detecting the initial time of traveling waves based on RLMD-TEO-IDR. • The RLMD method is used to reduce the influence of the noise signal and to maximally retain the characteristic components of traveling wave signal. • The TEO method is utilized for extracting the abrupt properties of the high-frequency modal signals. • The proposed incremental difference ratio algorithm(IDR) can effectively detect the initial time of traveling wave signal. • A fault location method based on three-terminal fault matrix is proposed, which achieves the fault location through the gradual reduction of the fault area range. To reduce the distortion effects of traveling wavefronts for fault location in distribution networks, a novel fault traveling wave detection method employing Robust Local Mean Decomposition (RLMD), Teager Energy Operator (TEO) and Incremental Difference Ratio (IDR) is proposed. According to the dispersion characteristic of traveling waves with multi-branch lines, the sampled faulty traveling wave signal is filtered using the RLMD method, then the TEO is used to determine the first half-wave time interval of the fault traveling wave. Finally, the IDR is proposed to detect the initial moment of the faulty traveling wave. And according to the fault traveling wave transmission path of multi-branch lines, the complex multi-branch line fault location problem is transformed into a three-terminal fault location problem. The fault traveling wave location method is proposed based on the three-terminal fault matrix, which achieves the fault location through the gradual reduction of the fault area range. Simulation and experiment results indicate that the method proposed in this paper can effectively calculate the arrival time of faulty traveling waves, and is more suitable for fault detection in multi-branch distribution lines compared to existing methods. The new proposed faulty location method can achieve reliable location to reduce location errors. [ABSTRACT FROM AUTHOR]