Conference Agenda

A novel, simple and fast method to identify the faulted phases using the maximum rate of change of incremental current (ROCOIC) is proposed. Six indices are calculated considering a pairwise comparison of ROCOIC. The decision-making process is based on selecting which two indices are the largest among all. The algorithm requires only three thresholds to detect fault inception and to identify the ground and three-phase faults. Simulation studies show that the method is robust and not affected by fault inception angle, fault location, and fault resistance. The proposed method only requires locally measured current signals. Since the method relies on the fundamental component of instantaneous incremental current, the proposed method can be implemented in systems with low sampling rates and avoids the need to use transducers with high bandwidth.

Faulty feeder selection is a challenging task for distribution system operator due to the low earth fault current magnitudes in compensated networks. However, extensive cable usages, especially in metropolitan cities causes unintentional resonance in the network earthed through inductance or grounding transformer. The unintentionally resonated networks are not designed like intentionally compensated networks where faulty feeder should be isolated in a predetermined time. There are transient zero sequence current based methods, particularly synthesized for compensated networks to identify faulty feeders. However, zero sequence-based faulty feeder selection methods have drawbacks in the presence of underground cables. Further, transient zero sequence current is prone to many parameters such as capacitive imbalance and fault resistance. In this study, a transient negative sequence current based faulty feeder selection method is proposed. The effectiveness of the proposed method is demonstrated in a simulated 151-node distribution network. EMTP simulations are carried out by considering different fault inception times, fault resistance and capacitive imbalance of the system. Results show that negative sequence current offers selective faulty feeder selection and no false trip is observed in unintentionally resonating distribution network.

The condition where the load angle of a generatorchanges rapidly with respect to another generator or portion ofa system is called Generator Out-of-Step (OOS). The traditionalway of detecting an OOS condition is to analyze the trajectoryof the impedance seen from the generator terminals. Therefore,setting calculations for these impedance-based methods becomemore challenging and time consuming. Detailed time domainsimulations, which required both generator and system data, arenecessary to set up these relays. This paper proposes a novelmethod to detect an OOS condition of a generator using itsrelative rotor speed. The inputs for the proposed algorithm arethe terminal voltage, current and machine parameters whichare readily available for typical synchronous generators. Theproposed algorithm monitors the change of relative rotor speedfollowing a fault and declares the OOS condition if the relativespeed tends to increase during a swing cycle. This technique iscomputationally simple, easy to implement, and fast comparedto impedance-based methods. The application of the proposedmethod is investigated using time domain simulations. Also, thesensitivity and security of the proposed method are analyzedunder various power system conditions.

This paper investigates the effects of communicationchannel latency (CCHL) on time-domain line protectionfunctions. The Alternative Transients Program (ATP) was usedto simulate the monitored power system and to model boththe analyzed relays and communication channels via MODELSlanguage. By doing so, the need for extra long optical fibers forlaboratory tests is overcome. To provide a reliable investigationon the CCHL effects, a time-domain relay model is firstlyimplemented and validated by comparing its response against anactual device. Then, the communication channel is set to properlyrepresent practical CCHL values under different fault scenariosfor transmission lines with different lengths. The obtained resultsshow that including the CCHL effects on time-domain protectiontesting procedures is of utmost importance because, depending onthe data propagation time through the communication channel,it may have a relevant influence in what we call here “race ofprotection functions”.

In this paper, the performances of one-ended and two-ended traveling wave (TW)-based fault location techniques in series compensated transmission lines (SCTLs) are thoroughly investigated, highlighting the impact of the series capacitors (SCs) and their associated overvoltage protection on such routines. To do so, a diversity of fault simulations were carried out on a realistic Alternative Transients Program (ATP) power system model of a 500 kV/60 Hz double-circuit SCTL located in the north region of Brazil. From the carried out studies, it is demonstrated that the two-ended algorithm is not impacted when the SCs are installed at the line ends, but the single-ended routines based on correlation functions are more affected by the SCs banks, even though some promising results may be obtained depending on their adjustments.

The algorithms for the correction of transients in coupling capacitor voltage transformers (CCVTs) are generally designed from processing samples in the time domain. Therefore, they need to be embedded in the measurement, protection, and control devices, because in these instruments only the phasors are available for the development of dedicated applications. In this paper, as an extension of a method originally developed by these authors for the time domain correction of CCVT secondary voltage samples, a mathematical formulation is developed that demonstrates the applicability of the existing method for phasor compensation, regardless of the phasor estimation algorithm used. Three phasor estimation algorithms and two CCVTs with different topologies and voltage levels are used to evaluate the method's performance. ATP (Alternative Transients Program) was used to generate the oscillographic records, while the phasor estimation algorithms and their corrections were implemented in MatLab. From the results, it can be inferred that the evaluated method can be used to correct voltage phasor disturbances, providing more suitable signals for protection algorithms.