In this paper, a novel variable-speed constant-frequency brushless doubly-fed induction generator (BDFIG) system using back-to-back multilevel converter for high power wind turbine is described. Based on analysis of p...
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In this paper, a novel variable-speed constant-frequency brushless doubly-fed induction generator (BDFIG) system using back-to-back multilevel converter for high power wind turbine is described. Based on analysis of power stator flux oriented vector control theory of BDFIG, an improved maximum power point tracking control strategy is explored. The paper specialty discusses the feasibility and advantage of a novel technique which should soft and fast synchronizing of BDFIG to the grid by using power stator voltage control method and disconnecting from the grid. Simulation results prove the feasibility and validity of the proposed model, theoretical analysis and excellent performance of the proposed control scheme.
In this paper, the newly invented brushless dual-mechanical-port electrical machine(BLDMPEM) based on the principle of magnetic field modulation with multi-operational modes and control strategies are presented which ...
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In this paper, the newly invented brushless dual-mechanical-port electrical machine(BLDMPEM) based on the principle of magnetic field modulation with multi-operational modes and control strategies are presented which is suitable for hybrid electrical vehicle application. The prototype structure and principle of operation are described, the mathematic model and equivalent circuit are established, the torque and power reference direction is analyzed,the vector control strategy and power management algorithm of this electrical variable transmission system is discussed. Simulation results prove the feasibility and validity of the proposed prototype, theoretical analysis and excellent performance of the proposed control scheme.
To improve the understanding of the turbulence intermittency, a detailed investigation of the intermittency of the density fluctuations has been performed in the boundary of J-TEXT. The intermittency of the density fl...
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To improve the understanding of the turbulence intermittency, a detailed investigation of the intermittency of the density fluctuations has been performed in the boundary of J-TEXT. The intermittency of the density fluctuations and its influence on the radial transport are reported. The probability distribution functions of the density fluctuations are not scale-invariant, being inconsistent with the self-organized criticality hypothesis. The underlying dynamics of the intermittency are detected using the quiet-time statistical method. The probability distribution function of the quiet times shows double-power-law regions, indicating the existence of correlations between the successive burst events.
Compared with the conventional short-pitched winding switched reluctance machine, the fully-pitched winding machine produces the effective electromagnetic torque by utilizing the changing mutual inductances among the ...
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ISBN:
(纸本)9781467323277
Compared with the conventional short-pitched winding switched reluctance machine, the fully-pitched winding machine produces the effective electromagnetic torque by utilizing the changing mutual inductances among the phase windings. Previous works show that the fully-pitched winding machine can offer better circuit utilization, higher ratio of torque and current and higher efficiency. This paper compares the static and dynamic performances of these two winding configuration machines at the condition of same outline size, phase voltage and revolving speed. The results show that the advantages of fully-pitched winding machine only appear in the low speed range. According to low speed applications, such as servo drives and torque machine, the torque ripple reduction is necessary. This paper introduces the instantaneous torque closed-loop control to suppress the torque ripple of two machines. By experimental comparison, it is seen that the fully-pitched winding machine is superior to short-pitched winding machine only regarding to low speed applications.
To solve the problem of controlling the stator flux linkage amplitude, a direct torque control (DTC) scheme is proposed for a novel transverse-flux permanent magnet motor (TFPMM) with two-phase conduction mode of brus...
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ISBN:
(纸本)9781467323277
To solve the problem of controlling the stator flux linkage amplitude, a direct torque control (DTC) scheme is proposed for a novel transverse-flux permanent magnet motor (TFPMM) with two-phase conduction mode of brushless DC drive. In this approach, flux linkage hysteresis comparator is removed and the desired voltage space vector is determined by only stator flux position and the output from torque hysteresis comparator, obtaining adaptive stator flux linkage. Further, reasonable phase compensation for the difference of optimal phase advance angle and the angle between stator and rotor flux is adopted to obtain maximum torque per ampere in the constant torque region. The validity and effectiveness of the proposed DTC scheme are verified through simulation results.
The large-scale wind power may influence the stability of the power system when its penetration level exceeds some limit and some disturbance as the short circuit happen. To study and preview this phenomenon before co...
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ISBN:
(纸本)9781457705458
The large-scale wind power may influence the stability of the power system when its penetration level exceeds some limit and some disturbance as the short circuit happen. To study and preview this phenomenon before connect the wind farm into the grid, the use of simulation method has been a good tool. This paper evaluated the stability analysis of the power system in Santiago Island, Cape Verde, considering a 9.25 MW wind farm installed and connected into the 40 MW grid. The simulation results by MATLAB/Simulink? show the stable performance of power system under short circuit fault. The effect of STATCOM is also evaluated.
This paper establishes the model of wind speed correlation (WSC) by inverse Nataf transformation. The impacts of WSC on distribution network operation and maximum installed capacity of wind power are investigated by M...
ISBN:
(纸本)9781622763153
This paper establishes the model of wind speed correlation (WSC) by inverse Nataf transformation. The impacts of WSC on distribution network operation and maximum installed capacity of wind power are investigated by Monte Carlo simulation and chance constrained programming method. A new definition of wind power penetration is proposed. Finally, conclusions are duly drawn.
High Voltage Direct Current (HVDC) technology has been widely recognized advanced in power transmission. Classical HVDC has shown its advanced features in long distance bulk power delivery, submarine cable crossings, ...
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ISBN:
(纸本)9781457715983
High Voltage Direct Current (HVDC) technology has been widely recognized advanced in power transmission. Classical HVDC has shown its advanced features in long distance bulk power delivery, submarine cable crossings, and asynchronous interconnections. Therefore, the new generation of technology, embedded HVDC, is further broadening the range of applications of HVDC transmission. The embedded HVDC is beneficial to all traditional occupations. Meanwhile, perspective novel applications, which are involved in offshore transmissions, infeed large urban areas, DC segment grid, and weak AC system connections, come into service. The installation of the embedded HVDC systems on the existing AC power grid may largely improve the transient stability and power flow oscillation damping factor of power transmission system.
Integrating large amount of low-inertia and intermittent renewable generation into the power system has increased the occurrence probability of power system imbalance brought about by large disturbances in short time ...
ISBN:
(纸本)9781622763153
Integrating large amount of low-inertia and intermittent renewable generation into the power system has increased the occurrence probability of power system imbalance brought about by large disturbances in short time scale and reduced the control capability of the power system under those disturbances. The continually increased electric vehicles (EVs) connected to the power grid may be capable of responding to those disturbances and contributed to the power balance by utilizing the fast-response, continuously regulating and power decoupling control capability of the power electronic charging interfaces. In this paper, different control schemes have been proposed to respond to the disturbances originated from distribution systems and the transmission systems respectively by regarding the electric vehicles as power support resources and considering the characteristics of the distribution network. A typical 11-kV 38-node system has been presented and tested to validate the effectiveness of utilizing the electric vehicles as power balance control resources and the related control schemes.
The double closed loops control strategy composed of inner current loop and outer voltage loop in the d-q synchronous frame is a relatively common control strategy of the three-phase voltage-sourced PWM rectifier. The...
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