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With the continue increases in power system voltage level, more and more complex wiring has resulted in the more frequently occurrence of the subharmonic resonance. To address this issue, this paper deduces the mathematical expression of the subharmonic resonance and uses mathematical analysis method to solve the nonlinear differential equations based on the system equivalent diagram. The relevant...
Appropriate modeling of dynamic loads is of primary importance in voltage stability studies, especially increasing use of induction machines in both consumption and generation. This paper is mainly related to short-term voltage instability depending on time domain simulation. The actuality of voltage instability research is summarized, and the mechanisms of short- term voltage stability are explained...
Self-adaptive system islanding refers to the separation of an interconnected power system into electrically isolated islands automatically based on the identification of unstable mode. A fast searching algorithm for self-adaptive power system islanding, which is called multilevel reduced graph partitioning (MLRGP) algorithm, is presented in this paper. The aim of this algorithm is that the generation...
Converter needs to absorb large amount of reactive power from AC power system when it transmits active power. The control mode of converters and the setting of each control mode will affect the quantity of reactive power directly. Thus, the control modes of converters are one of the important objectives for establishing the converter operation modes. The most familiar control mode of DC system is...
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...
This paper presents an integrated PMU and protection scheme for power systems. The scheme integrates local and wide area control and protection systems by implementing the WAMS function and substation protections into one system to identify the overload caused by flow transfer from isolation of main trunk line. This integrated system mainly consists of three major components: local interface unit...
This paper presents the design of new real time digital simulator (RTDS) based novel relay test systems. The background of the developments in protection relays and their associated technologies, such as optical transducers and IEC 61850, are introduced. The new developments in RTDS systems are described. It is shown that the recent developments in transducers and communication technology will have...
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 studies the modeling and simulation of Scott Transformer to investigate the transient behaviors of traction system. The paper presents an equivalent model of Scott Transformer, which can be used to simulate normal operation, internal fault and excitation inrush of the transformer. The model combines both the Scott Transformer and the Auto transformer, which are widely used in AT power supply...
A comprehensive investigation on the effects of HVDC parameters to system power losses is carried out in this paper. The parameters include converter location, length of DC line and power flow control. Based on the research on the power transmission mode via AC and DC parallel lines, the elements of the power losses of DC subsystem and AC subsystem are analyzed. The major factors affecting the power...
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...
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...
Centralized control using the wide-area information has been suggested to enhance the dynamic performance of large interconnected power systems. According to the inverse system method and LQR optimal control theory, this paper presents a nonlinear hierarchical global controller based on the wide-area information including the on-line measured center of rotor angle and total unbalanced power. Moreover,...
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...
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