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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,...
This paper presents a new protection scheme for high-speed protection of transmission lines, the Integrated Positional Protection scheme. The concept of integrated protection is firstly introduced, in which a centralized protection relay provides the protection for multiple transmission lines. The proposed scheme is based on a specially integrated relay unit, which is installed at each substation...
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 novel relay for power transmission line systems, which is based on a combination of positional and boundary protection principle. The relay installed at a substation is responsible for the protection of the transmission lines associated with the substation. The relay is able to offer fast trip for any fault on its protected line sections without the need for communication link...
It is difficult for existing HVDC line protections to distinguish internal fault from external fault rapidly and accurately, and the protective setting work encounters problems and difficulties. As a result, these protections have a low correct action rate. According to the feature of HVDC transmission system, this paper studies the characteristics of the natural boundary composed of the smoothing...
Based on the transient energy function (TEF) theory with classical models considered, the optimal re-closing time (ORT) can be calculated accurately. This paper mainly focuses attention on the validity and practicability analyzing of ORT obtained from this method. Firstly, the characteristics and influencing factors of the ORT are put forward and analyzed, and also the setting strategy of re-closing...
The impedance algorithm in distance protection for high voltage (HV) and extra high voltage (EHV) lines, although neglecting the influence of shunt capacitance, is able to produce satisfactory performance. However, the accuracy of the algorithm is significantly reduced when applying to ultra high voltage (UHV) lines due to the larger P.U. line shunt capacitance and longer transmission radius. Therefore,...
This paper presents a new integrated protection scheme for transmission lines. The concept of the integrated protection is firstly introduced, in which a centralized protection system provides the protection of multiple power plant or a substation. A total integrated protection scheme based on current differential protection techniques is further described. In the proposed scheme, the specially designed...
The re-closing time of a transmission line has a distinct influence on power system transient stability. There is an optimal re-closing time (ORT) for all transmission line faults, no matter the instantaneous fault or permanent one. Based on the transient energy function (TEF) theory with classical models considered, the ORT can be calculated accurately. This paper mainly focuses attention on the...
This paper presents a new integrated current differential protection scheme for transmission lines. The concept of the integrated protection is firstly introduced. An integrated protection scheme based on the current differential techniques is further described, in which a specially designed protection relay with protection algorithms of multiple settings is responsible for the protection of all the...
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,...
The study of various stability-control methods for a transmission system indicates that the reclosing time of a transmission line has a distinct influence on system stability. And there is an optimal reclosing time (ORT) for all transmission line faults. Utilizing the transient energy function (TEF) with classical models considered, the ORT setting computation method is proposed. This paper shows...
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...
A criterion using residual voltage and fuzzy decision to improve the successful rate of reclosing is proposed. Residual voltage of the faulted phase still remains after a single phase to ground fault occurs followed by the faulted phase breaking because distributed parameters of the high-voltage transmission line and coupling capacitance between one phase and another phase transmission lines exist...
This paper presents the extended study on current differential protection schemes based on symmetrical components. The principles of the protection schemes are analyzed firstly. Their performances are evaluated on a typical 500 kV power transmission line system model using EMTP. Extensive simulation studies are presented under various system and fault conditions, such as variations in system load...
This paper presents an integrated boundary protection scheme for power transmission line systems. The scheme combines the latest developments in two areas of power system protection, the transient based protection and the integrated protection. In the proposed scheme, an integrated relay based on boundary protection principle installed at a substation is responsible for the protection of all transmission...
This paper describes a new current differential relay. A current differential plane is presented firstly to depict different system statuses. Two traditional current differential protection schemes are discussed by plotting their operating and restraint region in the current-differential plane. A relay characteristic with more appropriate operating and restraint region is plotted in the plane by analyzing...
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