This paper describes a new scheme to locate a fault on a multi-terminal transmission line. It describes a simple new algorithm to identify the faulted section first. Then, to exactly locate the fault on this section, a method is described that uses the synchronized voltage measurements at all terminals. The main advantage of this method is that the current-transformer errors in the current measurements can be avoided. Since these errors can be as high as 10%, the fault location is extremely accurate with this method. The scheme can work for transposed as well as untransposed lines and is free of prefault conditions. The paper, after describing the scheme, describes very promising results from an Electromagnetic Transients Program simulation of a multi-terminal transmission line.

Fault location scheme for a multi-terminal transmission line using synchronized Voltage measurements

This paper delineates a novel analytical and computational approach to fault location for power transmission grids. The proposed methodology involves an online and an offline stage. The online stage is based solely on the utilization of the time-of-arrival (ToA) measurements of traveling waves propagating from the fault-occurrence point to synchronized wide-area monitoring devices installed at strategically selected substations. The captured waveforms are processed together at the time of fault in order to identify the location of the fault under study. The overall performance of the developed technique is demonstrated using Alternative Transients Program (ATP) simulations of fault transients and postprocessing the faulted waveform data via discrete wavelet transform. The applicability of the algorithm is independent of the fault type and can readily be extended to transmission grids of any size.

Traveling-Wave-Based Fault-Location Technique for Transmission Grids Via Wide-Area Synchronized Voltage Measurements

This paper presents a critical review on different application of Phasor Measurement Units (PMUs) in electric power system
networks incorporated with FACTS controllers for advanced power system monitoring, protection, and control. Also this paper
presents the current status of the research and developments in the field of the applications of PMUs in electric power system
networks incorporated with FACTS controllers. Authors strongly believe that this survey article will be very much useful to the
researchers for finding out the relevant references in the field of the applications of PMUs in electric power system networks
incorporated with FACTS controllers.

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Applications of phasor measurement units (PMUs) in electric power system networks incorporated with FACTS controllers

CIGRE WG C4.605 : “Modelling and aggregation of loads in flexible power networks”

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.

Parallel transmission lines fault location algorithm based on differential component net

Two new methods are proposed for fault point location in parallel double-circuit multi-terminal transmission lines by using voltages and currents information from CCVTs and CTs at all terminal. These algorithms take advantage of the fact that the sum of currents flowing into a fault section equals the sum of the currents at all terminals. Algorithm 1 employs an impedance calculation and algorithm 2 employs the current diversion ratio method. Computer simulations are carried out and applications of the proposed methods are discussed. Both algorithms can be applied to all types of fault such as phase-to-ground and phase-to-phase faults. As one equation can be used for all types of fault, classification of fault types and selection of faulted phase are not required. Phase components of the line impedance are used directly, so compensation of unbalanced line impedance is not required.

Digital fault location for parallel double-circuit multi-terminal transmission lines

This paper proposes a time domain model of a fault locator with special reference to fault are nonlinearities by applying the MODELS language of the EMTP. It has been found that an impedance relay type locator is significantly influenced by the fault arc nonlinearities, while the current diversion ratio method is not influenced. This validates the advantage of the current diversion approach over the impedance approach.

Influence of fault arc characteristics on the accuracy of digital fault locators

Wind turbine generators in a windfarm are connected by underground cables. Lightning sometimes strikes a nacelle or a blade. Lightning overvoltages due to a direct lightning strike to the system cause damages in the underground cable. Many parameters should be investigated to establish a rational lightning protection design for wind power generation system. Numerical simulation is a useful method to discuss the influence of the parameters on the lightning overvoltages. This paper uses an Electro-Magnetic Transients Program for the lightning surge analysis. This paper discusses the influence of grounding method of metallic sheath of the cable and grounding resistance on the lightning overvoltages for the direct lightning strike to the generation system.

A Study on Overvoltages in Windfarm Caused by Direct Lightning Stroke

This paper has proposed a time domain model of a fault locator with spacial reference to fault arc nonlinearities by applying the MODELS language of the EMTP. It has been found that an impedance relay type locator is significantly influenced by the fault arc nonlinearities, while the current diversion ratio method is not influenced. This validates the advantage of the current diversion approach over the impedance approach.

An influence of the voltage sag magnitude and duration on nonutility generator's mechanical shaft torque is investigated by simulations using the Electromagnetic Transients Program (ATP-EMTP). Various types of fault are simulated, changing the fault point, the number of faulted phases and the voltage phase angle at the moment of fault occurring. From the simulation results, it becomes clear that the high-speed static switchgear is effective for the stable operation of the in-house generation systems and the critical loads, which are subjected to the voltage sag.

H. Otoguro

Papers

Digital fault location for parallel double-circuit multi-terminal transmission lines

Influence of fault arc characteristics on the accuracy of digital fault locators

A Study on Overvoltages in Windfarm Caused by Direct Lightning Stroke

Influence of fault arc characteristics on the accuracy of digital fault locators

An influence of voltage sag duration on nonutility generator's shaft torque