Wind power forecasting has great significance to the connection of wind farms to the electric powersystem. 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 powersystem. 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 powersystem, 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 powersystem, providing a comprehensive solution. With the voltage swell, voltage sag, voltage harmonics, voltage fluctuations which occurs in the powersystem, 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.
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.
Substation configuration is a vital part of the powersystem 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 powersystem 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.
The removal of overload lines can cause power flow transferring, which may give rise to some transmission lines overload. By analysis of available methods of determining transmission sections with shortcomings, this p...
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The removal of overload lines can cause power flow transferring, which may give rise to some transmission lines overload. By analysis of available methods of determining transmission sections with shortcomings, this paper proposes a new way to determine transmissions section based on real-time power flows, and then deduce a new criterion of transmission section securityprotection based on the redundancy of normal line's power flows. A new transmission section securityprotectioncontrol scheme based on wide area measurement system (WAMS) is also proposed. When there is line overload, we should make a decision according to the protection criterion, if the transmission lines are safe after the overload removal, allow the backup protection to cut off the overload line; if not, block the protection. Therefore, it can avoid cascading overload tripping. At last, the validity of proposed algorithm is verified by the simulation results of CEPRI 36-bus system.
The topology characteristics of the nodal matrix in powersystem analysis and the adjacent matrix in graph respectively has been proved to be absolutely identical. According to this feature and modification principles...
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The topology characteristics of the nodal matrix in powersystem analysis and the adjacent matrix in graph respectively has been proved to be absolutely identical. According to this feature and modification principles of the nodal impedance matrix, a new tracking algorithm for the state change of the circuit breaker has been built based on the general multiplication and general addition operations. The new algorithm is able to reduce the computation burden than the traditional way. Finally, the text example has validated the efficiency of the novel tracking algorithm in substation configuration.
When taking emergency control measures to eliminate the overload circuits, it is necessary to ensure the normal lines of powersystem won't overload. Therefore, it's necessary to analyze the security of the no...
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When taking emergency control measures to eliminate the overload circuits, it is necessary to ensure the normal lines of powersystem won't overload. Therefore, it's necessary to analyze the security of the normal lines when take measures to eliminate overload. Based on the analysis of traditional methods of eliminating overload lines, this paper proposes an new overload control scheme based on wide area information, which can in parallel analyzing the impact of the normal line's redundancy on the regulated quantity of matching units, then the analysis results are sent to the control center, which finally determines the regulated quantity. It can ensure the normal lines won't overload when eliminating overload, and also can improve the computing speed of the whole control process. Therefore, it's very conducive to ensure the powersystem operating in a safe and stable state. Finally, simulation experiments verify the program is fast and reasonable.
Wavelet energy entropy has a small calculation amount, and it has a unique sensibility to slightly change of the dynamicsystem parameters. This paper presents a novel transient-based protection for powersystem EHV t...
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Wavelet energy entropy has a small calculation amount, and it has a unique sensibility to slightly change of the dynamicsystem parameters. This paper presents a novel transient-based protection for powersystem EHV transmission line, which employ the value of wavelet energy entropy to reflect the different energy distribution between internal and external fault. The basic principle of the protection is according to the attenuation effect of busbar capacitance and line trap to the high-frequency components. Simulation results show that the proposed protection criterion has high sensitivity and reliability, and capable of providing correct responses under conditions of different fault types, positions, path resistances, and inception angles.
Based on the synthetic control of microgrid, a flexible power electronics interface is developed in this paper. Considering distributed generation types and storage devices, different control strategies are adopted in...
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Based on the synthetic control of microgrid, a flexible power electronics interface is developed in this paper. Considering distributed generation types and storage devices, different control strategies are adopted in controller design for different distributed generation units. The interface comprises a couple of back-to-back VSC converters, and exports variable active power and reactive power in order to maintain the power balance inside the microgrid. Apparently, the interface separates the microgird from the AC grid, prevent harmonic component transmitting from one side to the other side and control the active power precisely flowing between microgrid and main grid. Besides, it's also in charge of reactive power compensation and keeping the microgrid voltage stable. Simulation results can approve its superiority and validity comparing with direct connection.
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