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In this thesis, existing instability criterion and its stability indicator τ for autonomous single machine infinite-bus system (SMIB) are firstly given, which reflect convex-concave characteristics of the trajectory inΔω-δ phase-plane. On this basis, it is discussed that there are some problems when the instability criterion of autonomous SMIB system is used in non-autonomous SMIB system. Proceeding...
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...
Arc grounding over-voltage is one of the worst over-voltages in the neutral isolated system. It is an important factor to be considered when selecting neutral ground mode. At present, system simulation is the main method for the study of the arc grounding over-voltage. Arc extinguish and re-ignition is simulated by controlling the switch on or off. However, the switch opening or closing need to be...
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...
In this paper, a method is proposed for fast and accurate online detection of transient instability based on real-time measurement. The cluster of critical machines is determined and refreshed at each time. Determination of the irrevocable loss of synchronism is made based on the geometric characteristic of critical machines trajectory. Unlike the previous extended equal-area criterion method, it...
This paper presents a novel integrated protection scheme for distribution lines based on Transient Polarity Comparison technique. In the proposed scheme, the specially designed interface units are installed at each substation and connected to the CTs on every line associated to the busbar. The unit converts the measured signals to optical format and sends to the central protection relay through a...
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...
In this paper, a method, which is essential in initiating emergency control measures, is proposed for fast and accurate online detection of transient instability based on real-time measurement. Under a certain disturbance, the candidate critical cluster of power system is predicted and refreshed at each sampling step. The method identifies the loss of synchronism at each time step by observing the...
This paper presents a new technique for the protection of power transmission systems by using the global positioning system (GPS) and fault generated transients, the integrated positional protection technique. The technique is based on the detection and processing of fault generated high frequency transient signals, in which a centralized protection relay provides the protection of multiple transmission...
The paper reviews the concept and development of the transient based protection and integrated protection for power systems. A number of new protection schemes with features of transient based and integrated protections are outlined. A new transient based integrated protection scheme for the protection of distribution system plant as well as distribution network as a whole using the transient polarity...
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...
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...
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 proposes a new current mode derived by a new modal transformation technique, the alpha mode. The mode is used to detect and distinguish between internal and external faults for power line protection, based on a new transient directional comparison technique using current alone. The technique uses the symmetrical component to replace Clark or Karrenbauer transformation to decouple the three...
This paper reports on the development of integrated protection for power system. The concept of integrated protection is introduced, in which a centralized protection system (or relay) provides the protection of multiple power plant or a substation. Examples are given of the protection schemes with the features of integrated protection which are currently under development. A novel integrated protection...
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