Hard-switching technique under the high voltage and high current is one of main trends of high power inverters. Under this switching mode, the stray parameters of the commutating loops, especially the stray inductance...
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Auxiliary frequency control of a wind turbine generator(WTG) has been widely used to enhance the frequencysecurity of powersystems with high penetration of renewableenergy. Previous studies recommend two types of con...
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Auxiliary frequency control of a wind turbine generator(WTG) has been widely used to enhance the frequencysecurity of powersystems with high penetration of renewableenergy. Previous studies recommend two types of control schemes,including frequency droop control and emulated inertia control,which simulate the response characteristics of the synchronousgenerator (SG). This paper plans to further explore the optimalauxiliary frequency control of the wind turbine based on previousresearch. First, it is determined that the virtual inertia control haslittle effect on the maximum rate of change of frequency (MaxROCOF)if the time delay of the control link of WTG is taken intoconsideration. Secondly, if a WTG operates in maximum powerpoint tracking (MPPT) mode and uses the rotor deceleration forfrequency modulation, its optimal auxiliary frequency control willcontain only droop control. Furthermore, if the droop control isproperly delayed, better system frequency response (SFR) willbe obtained. The reason is that coordination between the WTGand SG is important for SFR when the frequency modulationcapability of the WTG is limited. The frequency modulationcapability of the WTG is required to be released more ***, when designing optimal auxiliary frequency controlfor the WTG, a better control scheme is worth further study.
This paper proposes a hierarchical control scheme for parallel grid-connected PV inverters with a common dc bus. Droop control and group coordination are implemented to achieve equal power sharing between inverters as...
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ISBN:
(纸本)9781849197588
This paper proposes a hierarchical control scheme for parallel grid-connected PV inverters with a common dc bus. Droop control and group coordination are implemented to achieve equal power sharing between inverters as well as zero steady-state error for dc voltage regulation. The implementation is specifically designed for distributed control to promote modularization and system reliability. Experimental results have verified that the proposed scheme is effective.
Three-phase induction motors as well as power converters are intrinsically efficient machines and devices. However, due to the common misapplication of them with loads like pumps and fans, these electric machine syste...
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ISBN:
(纸本)9787506292214
Three-phase induction motors as well as power converters are intrinsically efficient machines and devices. However, due to the common misapplication of them with loads like pumps and fans, these electric machine systems are considered a great potential of energy conservation in industries. As to assessing methods of energy conservation, neither the study of induction machine efficiency nor the analysis of pumps and fans performance is new. However, the systematic and qualitative analysis and assessment of the energy efficiency of induction machines, loads and control devices acting as a whole system are still complicated yet indispensable for electric machine system energy conservation program in China. In this paper, a systematic and qualitative assessment method for energy application efficiency of electric machine system is raised. Based on this method, an assessing computer program is designed to provide referencing information for making investment decisions regarding energy efficiency measures at manufacturing plants. An expert system is also designed to choose equipments that match each other.
Condition classification has been widely used for assessing equipment status for machine condition monitoring and diagnostics. An engine was fitted with one temperature and two pressure sensors to study the machine co...
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Aircraft engine is an important component of the airplane, which lifespan and reliability have directly influence to flight safety. Vibration analysis is an effective fault diagnosis method for airplane's mechanic...
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The transient voltage unbalance is the major problem that limits the application of series-connected IGBTs in high voltage and high power converters. The asynchronous gate delay which causes that series-connected IGBT...
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In order to improve the energy efficiency and compact structure, the dual-rotor structure including lowpressure rotor and high-pressure rotor has been widely used in aero-engine. Misalignment is one of the most common...
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In order to improve the energy efficiency and compact structure, the dual-rotor structure including lowpressure rotor and high-pressure rotor has been widely used in aero-engine. Misalignment is one of the most common faults in dual-rotor system, which will causes malfunctions. It is a significant task for rotor dynamics personnel to monitor and defect faults in dual-rotor system. In the paper, the dual-rotor vibration signals are applied to solve the fault identification problem by utilizing time frequency techniques. Numerical simulations are carried out through finite element analysis of dual-rotor system with misalignment fault. Two signal processing tools namely Short Time Fourier Transform (STFT) and Continuous Wavelet Transform are used to detect the misalignment fault and compared to evaluate their diagnosis performance. The effect of addition of Signal to Noise (SNR) on three frequency techniques is presented. Experiments are carried out to obtain the vibration data of dual-rotor test rig and the results from the work show that the technique can be used for the monitoring of misalignment, which will have applications in the condition monitoring and maintenance of various types of rotating machinery.
A large number of text and reports about the powerequipment are generated in powersystem, which consist of implicit information of operation condition and insulation status. With the development of convolutional neu...
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The smart grid is attracting more and more attention in electrical engineering for its promising ***,huge challenges also exist in the implementations of the smart grid,such as high penetration of renewable energy res...
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The smart grid is attracting more and more attention in electrical engineering for its promising ***,huge challenges also exist in the implementations of the smart grid,such as high penetration of renewable energy resources,low carbon electricity and cyber-physical security,*** this paper,the latest progress of some research focuses and advance technologies in the development of smart grid is reviewed.
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