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This paper presents a novel time-domain fault location algorithm for parallel transmission lines using two terminal currents. Parallel transmission lines with faults can be decoupled into the common component net and differential component net. Since the differential component net is only composed of the parallel lines and its terminal voltages equal zero, the proposed algorithm is based on the fact that the difference between voltage distributions, calculated from two terminal currents, is the smallest at fault point. To be practical, unsynchronized data and the transient transferring ability of the current transformer are taken into consideration. The algorithm needs a very short data window, and any segment of current data can be used to locate faults. The proposed algorithm is verified successfully using the simulation data generated by the frequency-dependent line model of the Alternative Transients Program and the field recording data provided by traveling-wave fault locators. Locating results show the satisfactory accuracy of the algorithm for various fault types, fault distances, and fault resistances. Index Terms--Differential component net, fault location, parallel transmission lines, protective relaying, two terminal currents.

• An improved active injection method is proposed to inject a detection signal to strengthen the fault characteristics with a lesser negative impact on the system during the injection process. • A ZPI algorithm is proposed to calculate the feeder length, and the faulty feeder is selected based on the polarity of the calculated length. • The waveform, frequency, amplitude, and duration of the detection signal are analyzed based on the requirements of the faulty feeder selection method and system constraints. • Simulations verify the feasibility of the proposed method under conditions of up to 5000 Ω transient resistance and 20 dB noise. Identifying single-line-to-ground faults in non-effectively grounded DC distribution networks is challenging because the fault current is fleeting in the transient stage and negligible in the fault steady stage. First, an active signal injection method is proposed to inject signals into the DC network after the fault occurs. And the fault characteristics of the zero-mode fault circuit including the injected signal are analyzed. Second, a zero-mode parameter identification algorithm is proposed to calculate the length of each feeder based on the injected signal in the fault steady stage. It is found that the calculated length of the healthy feeder corresponds to its actual length, but the calculated result of the faulty feeder is the opposite of the total length of all healthy feeders. Finally, a faulty feeder selection method based on the polarity of the calculated length is proposed. The simulation results shown that the method can select faulty feeders under conditions of up to 5000 Ω transient resistance and 20 dB noise. [ABSTRACT FROM AUTHOR]

Feeder automation is important to improve the reliability of power supply for distribution network. Existing voltage‐time feeder automation scheme exists the problems of long fault processing time and the upstream switches of the fault point need to tolerate fault current twice and the upstream sections need to experience two short time power outage. In this paper, a quick fault location and isolation method for distribution network based on adaptive reclosing is proposed. Three key technologies of the strategy are introduced, including a phase segregated switch of the distribution network based on the permanent magnet operating structure, the phase selector based on transient current characteristics, and the temporary fault and permanent fault identification method based on the power frequency voltage characteristics. The proposed strategy can avoid the second impact on upstream switches and power‐off of the upstream section in case of the permanent fault and can effectively shorten the fault processing time. [ABSTRACT FROM AUTHOR]

The multi‐terminal hybrid line commutated converter (LCC)/modular multilevel converter (MMC)‐based high voltage dc (HVDC) has been applied to solve the simultaneous commutation failure problem in East China. Here, the propagation of the travelling wave is characterised by transfer functions and the characteristic of the fault current travelling wave in the multi‐terminal hybrid LCC/MMC HVDC system is analysed. Then a directional pilot protection for the multi‐terminal hybrid LCC/MMC HVDC system is proposed. The proposed method is implemented to the designed HCM5000 dc control and protection device and verified in the Kun–Liu–Long three‐terminal hybrid LCC/MMC HVDC real‐time digital simulator (RTDS) test system. The test results show that the proposed method meets the engineering requirement of multi‐terminal hybrid LCC/MMC HVDC system for line protection. [ABSTRACT FROM AUTHOR]

This study presents a single‐ended fault location method that does not need the information of the remote‐end system. As the foundation of the proposed method, the fault location equations under different fault types are derived based on the fault loops. The fault distance, fault impedance, and equivalent resistance and inductance of the remote‐end system are considered as the unknowns of the fault location equation. Then the equation can be solved using the Gauss‐Newton method, by which the four unknowns can be obtained. Therefore, the proposed method is not sensitive to the fault impedance and the system parameters. A two‐terminal 500 kV ac transmission line test system is built in PSCAD to verify the proposed method. Numerous simulation data of faults of different fault distances, fault impedances, and fault types verify the accuracy and robustness of the proposed method. The proposed method is a time‐domain method that can locate the fault using 5 ms data after the faults. [ABSTRACT FROM AUTHOR]