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This paper presents a new method of fault loop resistance measurement in low voltage systems with residual current devices. The method enables measuring fault loop resistance without nuisance tripping of residual current devices, by application an unconventional waveform of measurement current. It is important for proper verification of the effectiveness of protection against electric shock.
This paper presents use of no-load current harmonic analysis to detect presence of inter-turn fault at incipient stage. At steady state, third and fifth harmonic components are predominant in transformer no-load current. Inception of fault results in decrease in THD and increase in increase in primary current. Based on reduction of total harmonic distortion (THD) of each phase and simultaneous increase...
Double-circuit HVDC transmission lines on the same tower have becoming an inexorable trend for they can not only increase unit corridor area transmission ability but also reduce construction costs. After thoroughly study the phase-mode transformation method for double-circuit HVDC lines and considering that in practice they are not transposed, a novel algorithm for locating faults using mixed modulus...
This paper describes an analysis on power system breakdown sequences caused by circuit breaker and protective relay failures, and applies this to plan a probabilistic test and maintenance schedule for these periodically tested components. The paper shows that a probabilistic and component importance based test and maintenance scheduling can minimize the system breakdown frequency caused by the component...
This paper examines the use of the symmetrical components theory for the representation of unbalanced conditions, when using the concept of analog emulation for highspeed power system analysis. This concept has been proven and validated through the realization of a mixed-signal hardware platform dedicated to power system studies. Computations related to the grid are handled by analog electronics,...
The Low Voltage Ride Through (LVRT) capability of Wind Turbines (WTs) determines the connectivity of WT to the grid based on both voltage sag magnitude and duration locally measured at Point of Common Coupling (PCC), in order to protect the WT against overloading out of its tolerable apparent power. If the WT is still inside its safe and secure operating condition and there is still some standby capacity...
For a HVDC system, a reliable power system protection should be quick and precise in identifying fault. It is also equally important to ensure some events that could be mistaken for fault to not trigger false alarm, for example load change. Wavelet transform is one of the well-known tools that is able to achieve this purpose. In this paper, the fault analysis using a novel Amplitude Tracking Square...
This paper introduces a robust fault location method that utilizes wide area phasor measurements and sparse estimation technique. The proposed method transforms the fault location problem into estimating sparse bus injections in the network, based upon the equivalence in the change of bus voltages between a fault current drawn at an arbitrary point along a line and virtual superimposed current injections...
This paper proposes a method for fault location in medium voltage grids with underground cables, using Bayesian inference. The prior distribution of fault position is obtained from the component failure database. With the measured fault loop impedance, the posterior distribution is calculated based on Bayes' theorem. Several random factors are considered during the calculation, including measurement...
This paper studies the grid code compliance of an offshore multi-terminal HVDC grid used for grid connection of far and large offshore wind power plants during AC system failures. The paper stresses out control modules and parameter sensitivities which influence the combined dynamic response of the MTDC grid and the connected wind power plants. Common low voltage ride through strategies are evaluated...
The current development of distribution networks into active and smarter systems has been facilitated by the integration of novel technologies such as Microgrids (MGs) and Distributed Energy Resources. These new concepts are expected to bring about significant economic benefits at the distribution level in the form of network reinforcement deferral and increased reliability levels, among others. In...
High penetration of distributed energy resources (DERs) creates various protection challenges, such as protection blinding, false tripping, unsynchronized reclosing, etc. Additionally, adaptation of active network management approaches namely demand response and network reconfiguration also threats existing protection practice. In this study, a combination of a local adaptive and communication assisted...
Voltage sags being inherent disturbances to power systems, equipment should be characterized by tolerance curves and grid operators are compelled to report voltage sags. Furthermore, voltage sag responsibility curves are currently being discussed by regulators. This paper condenses relevant information on these subjects, and presents three case-studies. The description and reporting of voltage sags...
One of the main challenges with HVDC multi-terminal (MTDC) configurations, which are based on voltage source converters (VSC), is the protection system. The dc grids have small series inductances which made them unable to limit the rise time of the DC current when a dc fault occurs. For this reason, the dc fault clearing must be performed very fast in order to limit the effect of the rapid increase...
This paper investigates the contribution of a three-phase inverter used for the grid connection of a wave energy generation to the short-circuit currents when a grid fault occurs. By considering a real MV distribution network, the voltage ride-through capability of the power converter is verified both in case of a three-phase and a two-phase fault. The steady-state and transient evolutions of the...
Recently proposed meshed HVDC networks include both converters and DC circuit breakers, and the fault currents experienced and therefore the capacity requirement of circuit breakers are dependent on the topology of converters used on the network. This paper analyses the difference in fault currents seen in various network configurations utilising fault-feeding and fault-blocking converters. Results...
DC power system is gaining popularity. Research is being conducted worldwide on implementation of LVDC (low voltage direct current) and MVDC (medium voltage direct current) in applications such as ship power systems. One major hurdle to this path is the immaturity of the protection systems. This paper deals with the modeling of LV/MVDC power system with different marine loads and faults. Since LV/MVDC...
The reactance method with fault resistance separation has been developed in order to determine as precisely as possible the impedance of a fault loop in a transmission or distribution power system line. This method has commonly been used for impedance calculation in case of a single phase-to-earth fault in diverse power system protection applications. New developments in this area have shown that...
Equipping one support structure with DC and AC systems in parallel can increase the transport capacity of existing transmission corridors. The constant electric field of the DC system induces a constant DC component into the AC systems in near vicinity. All magnetic equipment including an iron core is in danger to saturate. Especially current transformers (CTs) for protection issues can be influenced...
Applications of superconductivity in power systems, especially in transmission systems, is a subject of study since 1970s. Superconductors' advantage of providing an almost lossless transmission system, due to the non-existence of joule losses, has been highlighted during the last decades. However, the absence of resistance and its ability to damp oscillatory phenomena, which in case of a superconducting...
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