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Ground fault in the rotor winding of generators can cause serious damage to the generators and consequently, to the power plant. This paper proposes a practical online technique to determine the ground fault location in the rotor winding of a synchronous generator. The proposed technique is based on the analysis of the measured voltage and input/output currents of the rotor winding. The main distinguishing feature of the proposed technique is that, contrary to the existing technique, it is applicable to various types of excitation system. The accuracy and applicability of the proposed technique is demonstrated through both computer simulations and experimental tests. The experimental tests have been carried out using a new device which works based on the proposed technique. The results show that the proposed technique can determine ground fault locations with a higher accuracy compared with the existing techniques. Copyright © 2016 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

• Double-circuit grounded cross-country fault location in GUPFC-compensated DCTLs. • The proposed algorithm is independent of the GUPFC's operating point and parameters. • No GUPFC output current/voltage is measured in the proposed algorithm. • The algorithm is based on phasor theory; easily applicable in industrial relays. • The performance of the proposed method is very accurate and desirable. This paper presents an accurate fault location algorithm for double-circuit grounded cross-country (DCGCC) faults in double-circuit transmission lines (DCTLs) compensated by a generalized unified power flow controller (GUPFC). The algorithm incorporates synchronous current and voltage phasors at both end buses of the line. The proposed algorithm determines the accurate location of simultaneous faults occurring in both line circuits in three basic steps. In the first step, the faulty sections are identified using a zero-sequence current analysis. In the second step, the accurate location of a fault in the circuit on which only a series converter is installed is calculated. Next, by employing the calculated zero-sequence current of this fault point, the zero-sequence current component of the other line circuit, which is equipped with series and shunt converters, is obtained. Finally, the accurate fault location in this circuit is calculated. The calculation process and the derived equations for all DCGCC fault types are described in detail. The GUPFC considered in this study along with the test network is modeled in MATLAB/Simulink environment. The simulation results confirm the accurate performance of the proposed algorithm for various fault types occurring in different operating conditions. [ABSTRACT FROM AUTHOR]

• Fault location (FL) algorithm for three-terminal series capacitor compensated lines. • Phasor-based FL equations derived for different fault types in any line section. • Fault location using asynchronously measured phasors at all three terminals. • Independent of the parameters of series capacitor compensator and its protections. • Not requiring a high sampling rate or training process for implementation. In this study, a new algorithm for fault location in series capacitor compensated three-terminal transmission lines using the distributed line model is proposed. The proposed algorithm uses the sampled data of currents and voltages of all the three terminals, which are transferred asynchronously using telecommunication lines. All data transmission delays are calculated in terms of line parameters as well as the measured values of currents and voltages of the three terminals. Based on the data received from the three terminals, current and voltage equations of different points of the network are constituted for different types of faults. By solving these equations according to their boundary conditions, accurate locations of faults are estimated. One of the salient features of the suggested algorithm is that the schemed equations are independent of the model of the series capacitor compensator during fault occurrence and its protective circuitry. Also, based on the sensitivity analyses performed in this paper, the presented algorithm works perfectly against the errors caused by measurements and parameters. The test system and the suggested algorithm were realized in MATLAB environment. The obtained simulation results for different fault types occurring in various places in the line verify the accurate performance of the algorithm. [ABSTRACT FROM AUTHOR]

• Presenting a single end-based fault location method for hybrid parallel HVAC/HVDC overhead transmission lines (HPOTL). • Accurate modeling of HPOTL considering electromagnetic coupling between AC and DC lines. • Low sampling frequency and high accuracy in fault location estimation. • Determining the faulty half of transmission line using a robust method. • The proposed method is robust and independent of fault resistance, noise and fault angle. In this paper, a single ended traveling wave based fault location method is presented for Hybrid Parallel HVAC/HVDC Overhead Transmission Lines (HPOTLs) on the same tower using Discrete Wavelet Transform (DWT). In HPOTLs, the AC and DC transmission lines are adjacent to each other from the sending to the receiving end of the lines and there is electromagnetic coupling between them. Fault detection and classification algorithms in HPOTLs are presented in another paper. Therefore, in order to summarizing, in this paper, it is assumed that the fault is detected in the HVAC or/and HVDC lines and faulty line is identified. HPOTL faults include AC faults, DC faults and AC/DC intersystem faults. AC and DC voltage signals on sending end of the transmission line with a sampling frequency of 100 kHz are used for fault location in this paper. In order to minimize the noise effect, the squared wavelet transform coefficients (WTC2) is used for proposed fault location method. Finally, Bewley-Lattice diagrams are checked for the traveling wave pattern and locate the fault. At the end of paper, it has been shown that the proposed method has high accuracy, noise immunity, robustness against fault inception angles, and high impedance faults. [ABSTRACT FROM AUTHOR]