Distributed generation (DG) that uses renewable energy sources has an unstable output and this can negatively affect existing electric power systems. In order to reduce above impact, we need to develop an energy contr...
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Based on the modal series method, this paper derives the second- and first-order solutions of torques for investigating nonlinear torsional dynamics. The derivatives of the two types of solutions are compared to expla...
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Based on the modal series method, this paper derives the second- and first-order solutions of torques for investigating nonlinear torsional dynamics. The derivatives of the two types of solutions are compared to explain the advantage of the second-order solutions. The index is given for evaluating the feasibility of solutions. Subsequently, several nonlinearity indices are defined to quantify the effects of nonlinear modal interactions on torsional dynamics, and the suitable indices are determined for analyzing nonlinear torsional dynamics. The systematic method is developed for the analysis of nonlinear torsional dynamics. Furthermore, the concept of nonlinear modal interactions is extended to deal with both the fundamental and the combination modes; the nonlinearity contribution factors are emphasized. The study is implemented on two modified cases from the IEEE first benchmark model, which validates the presented method for investigating torsional dynamics in the stressed case and gives new engineering insights into nonlinear torsional dynamics.
With the rapid development and interconnection of power systems, the low frequency oscillations(LFO) has become one of the serious factors threatening the power system stability. Thus, how to quickly locate the source...
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Once the power system low frequency oscillation occurs, the operators desire to find out the dominant mode LFO so as to take measures to suspend it. This paper proposes an identification method for dominant mode of LF...
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This paper presents a simple and effective approach based on two dynamic matrixes of node-relay matrix (NRM) and relay-incidence matrix (RIM) to determine minimum break point set (MBPS) for coordination of the directi...
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This paper presents a simple and effective approach based on two dynamic matrixes of node-relay matrix (NRM) and relay-incidence matrix (RIM) to determine minimum break point set (MBPS) for coordination of the directional relays. Firstly, the NRM and RIM are defined and their calculation methods are developed. Then, some optimization operations for network reduction and special structure are presented to update the NRM and RIM and the detailed flowchart is provided. At last, case studies on various topologies demonstrate the effectiveness and simplicity of the proposed method.
Wind power forecasting has great significance to the connection of wind farms to the electric power system. This paper analyzes individual forecast models, such as the time series forecasting, Elman network forecastin...
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ISBN:
(纸本)9781424480807
Wind power forecasting has great significance to the connection of wind farms to the electric power system. This paper analyzes individual forecast models, such as the time series forecasting, Elman network forecasting that based on the chaos theory, grey neural network forecasting, and generalized regression neural network forecasting, etc., then puts forward an entropy weight combination prediction model, and an optimal combination forecasting model for the wind power forecasting that based on vector angle cosine. The forecasting results indicate that due to the different forecast precisions of different methods, the methods with high precisions may bring great variation in some points, and the combination forecast can reduce the forecasting variation in several points, which improve the forecasting precision.
This paper studies the FPGA-based control 4 H-bridge cascaded 9-level structure of voltage quality adjustment device, for the variety of voltage quality issues appears in electric power system, providing a comprehensi...
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This paper studies the FPGA-based control 4 H-bridge cascaded 9-level structure of voltage quality adjustment device, for the variety of voltage quality issues appears in electric power system, providing a comprehensive solution. With the voltage swell, voltage sag, voltage harmonics, voltage fluctuations which occurs in the power system, it can give out the complex compensation, so as to ensure the system voltage quality, 0.1MVA/400V Low-voltage prototype was designed and developed for validating the variety of experiments. Experimental results show that the design of this device is feasibility and effectiveness.
In view of the harmonic problems caused by plenty of nonlinear load, especially large-capacity rectifiers, are becoming more and more serious, a kind of harmonic suppression method based on phase-shifting reactor (PSR...
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In view of the harmonic problems caused by plenty of nonlinear load, especially large-capacity rectifiers, are becoming more and more serious, a kind of harmonic suppression method based on phase-shifting reactor (PSR) is studied in this paper. The problem of determination of the winding turns aiming at a certain phase-shifting angle is solved through theory analysis and calculation. And the topological structure of multi-phase rectifier system composed by cascade phase-shifting reactors is introduced. Also, a method of determining the phase-shifting angles is proposed and the characteristic harmonic of rectifier system is suppressed comprehensively. At last, simulation and experiment of twelve-phase rectifier system composed by phase-shifting reactors are made and the results show that using phase-shifting reactors can realize the same effect as phase-shifting transformers. The harmonic caused by rectifier system can be suppressed very well by phase-shifting reactors.
Substation configuration is a vital part of the power system network topology, and its implementation has taken most of the total time of network topology analysis. The improvement of the network topology efficiency f...
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Substation configuration is a vital part of the power system network topology, and its implementation has taken most of the total time of network topology analysis. The improvement of the network topology efficiency focuses on the faster and more accurate substation configuration based on the distributed modeling formation, which can be finished in parallel way in order to reduce the time consumed. Based on the analysis of the common characteristic of adjacent matrix and node admittance matrix and impedance matrix, a new method of original and tracking topology analysis in the substation has been proposed in this paper, which uses the addition of the virtual switch impedances and the virtual ground branches. The directional treatment to the original adjacent matrix is avoided in this new method. According to the characteristic of node impedance matrix, the work for substation configuration has been realized. Finally, the examples have validated the function of the new method in analyzing the original topology and tracking the variation in switch status. Compared to other methods based on adjacent matrix, this method features the easy-to-program property.
This paper researches the intrinsic relationship between inter-harmonics and typical voltage fluctuations of which the enveloping line is sine wave, it analyses the effects to voltage fluctuations of inter-harmonics o...
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This paper researches the intrinsic relationship between inter-harmonics and typical voltage fluctuations of which the enveloping line is sine wave, it analyses the effects to voltage fluctuations of inter-harmonics of different frequencies, including a single inter-harmonic and a pair of inter-harmonics. In this paper, experiments of voltage fluctuations production and compensation are all carried out. The disturbance producing device makes use of different frequency voltage to modulate inverter output voltage, then the output voltage is superimposed on system voltage, at last voltage fluctuation waveforms of different frequency are produced, the voltage compensation device firstly detect the output voltage of disturbance producing device, and the standard reference 220V is subtracted from it, the result is used to modulate the output voltage of the compensation device, and it get a good compensation effect.
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