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The performance of the negative sequence pilot protection (NSPP) is less deteriorated by the phase-ground shunt capacitance since the negative sequence current loops in phase-phase lines. Hence NSPP is a good candidate for the main protection in UHV lines with the special characteristic of larger charging current. But as we all known, NSPP is not suit to the open-phase operations in transmission line,...
The fast development in both microprocessor and transducer technologies has enabled fault detection techniques to be considered which were impractical in the past and encouraged interest in the utilization of fault generated transients for protection. This paper presents an integrated approach for high-speed protection of transmission lines. The technique uses a fault transient detector unit at the...
This paper presents a simulation model of DC traction system which is based on bilateral power supply mode. The model of two substation rectifiers in one track section has been proposed which is according to practical situation. The modeling was conducted with respect to the variations of the starting-up process and short circuit conditions. By comparing and investigating the simulation results of...
In order to study phase-frequency characteristic of zero sequence current after single-phase earth fault in neutral indirectly grounded power system, this paper starts with the line model of distribution network, and analyzes phase-frequency character of zero sequence impedance for distributed parameter line model. By simulation analyzing, for a single feeder, the factors such as transmission line...
Cascading overload trip due to lack of transmission section protection is an important reason of large-scale blackout. This paper illustrates the meaning of transmission section and points out that the objective of transmission security protection is to maintain its integrality and transmission capacity, and to avoid cascading overload trip. In addition, the implement condition and key technology...
The principles of the equivalent circuit principle and the magnetic property theory are not affected by the inrush current and over-excitation, which enable protection to act rapidly and reliably and implement ideas different from differential protection. However, the leakage inductance and resistance of each winding are required as priori parameters. At present, there is no accurate measurement method...
On the basis of effective extraction and utilization of transient fault information, this paper presents a whole scheme of ultra- high-speed transient based protection for EHV/UHV transmission lines, which consists of the main protection, the auxiliary protection and related protection elements. All protection elements are introduced, including starting element, directional element, boundary element,...
Autoreclosure schemes have been widely used in power system and an effective way to improve greatly the dependability and stability of power systems. However, most of these schemes adopt a presetting time to reclose breaker after a tripping operation. There are many problems due to the conventional reclosure schemes. In this paper, a self-adaptive auto-reclosure criterion using dual-window transient...
The fault detection and analysis for power transformer are the key measures to improve the security of power systems and the reliability of power supply. Due to the complicity of the power transformer structure and the variations in operating conditions, the occurrence of a fault inside power transformer is uncertain and random. Until now, the fault statistics of power transformer is very limited...
This paper presents a novel integrated protection scheme for distribution networks using the transient polarity directional comparison technique. The technique is based on the detection and processing of fault generated transient current signals, in which specially designed protection relays are installed at each substation of a distribution network. The transient detection unit of the relay detects...
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