A broadband RF energy harvesting system over a frequency range of 900MHz-3GHz has been designed and tested. Some detailed issues of RF design have been studied and tested to improve the efficiency of the rectifier. Te...
详细信息
A broadband RF energy harvesting system over a frequency range of 900MHz-3GHz has been designed and tested. Some detailed issues of RF design have been studied and tested to improve the efficiency of the rectifier. Test results show that as low as -20dBm RF power can be harvested by this system. The series and parallel connections of two RF energy harvesting systems have also been studied, compared with the single system.
For PD pattern recognition, six kinds of typical cable fault models are made and tested. Characteristics are calculated from test data. Multiple statistical characteristics of PD distribution map are calculated and pa...
详细信息
It is very difficult to correctly identify single-phase-to-ground fault (SFG) in distribution system with neutral non-effectively grounded (NNG). A novel travelling wave based singlephase-to-ground protection is propo...
详细信息
ISBN:
(纸本)9781849198349
It is very difficult to correctly identify single-phase-to-ground fault (SFG) in distribution system with neutral non-effectively grounded (NNG). A novel travelling wave based singlephase-to-ground protection is proposed in the paper. The polarity of initial transient current and voltage travelling waves are used to identify the fault direction, and power frequency voltages are used to distinguish SFG from phaseto- phase fault to ensure the reliability of the protection. In the paper, wavelet transforms and module maxima theory was adopted to represent the polarity of travelling waves effectively and construct protection algorithm,. The analysis and simulation demonstrate that the protection is valid.
This paper presents a kind of HVIGBT transient mixture model and corresponding parameter extraction method. The HVIGBT model can divide into MOSFET and BJT two parts. The two models are formed respectively according t...
详细信息
This paper presents a kind of HVIGBT transient mixture model and corresponding parameter extraction method. The HVIGBT model can divide into MOSFET and BJT two parts. The two models are formed respectively according to HVIGBT work principle, in addition, the carrier transport equations have been simplified for avoiding Kirk effect in BJT model. The transient model is realized in PSIM software in the paper. Extraction methods, which include estimation by empirical values, calculation by testing waveforms and comparison with same type models, are adopted in extracting model parameters. Through comparing testing and simulation waveforms, the model's simulation accuracy is proved.
Based on the Chinese demonstration project of Zhangbei wind-photovoltaic-energy storage (W-PV-ES) hybrid generation, which is the world's biggest and Chinese first new energy utilization platform, the design of gr...
详细信息
This paper describes several methods for condition-based maintenance, introduced CBM, RCM development process, the main theoretical logic, techniques and practices. Focuses on the health index based on equipment maint...
详细信息
ISBN:
(纸本)9789881532329
This paper describes several methods for condition-based maintenance, introduced CBM, RCM development process, the main theoretical logic, techniques and practices. Focuses on the health index based on equipment maintenance strategies, namely CBRM. Focused on the development of narrative context, theoretical foundation, model healthy index. And for its application in power transformers were introduced.
The random and intermittent nature of wind power (WP) makes the integration of large-scale wind farms into powersystem problematic. The energy storage system (ESS) is an effective means to smooth the WP. This paper p...
详细信息
The random and intermittent nature of wind power (WP) makes the integration of large-scale wind farms into powersystem problematic. The energy storage system (ESS) is an effective means to smooth the WP. This paper presents a novel Kalman filter (KF) based adaptive wind power smoothing method to determine the power output of an ESS. ESS capacity can be significantly reduced by adjusting the parameters of KF adaptively according to the WP fluctuation. Meanwhile, a fuzzy logic controller is introduced to manage the remained energy level (REL) of the ESS. By considering the current WP fluctuation, the REL and the power output of the ESS together in the controller, the REL can be successfully managed to a reasonable range without deteriorating the WP fluctuation. A test case based on data from an actual wind farm validated the effectiveness of the proposed method.
In the conventional phase-shift control of isolated bidirectional DC-DC converters, the phenomenon of power backflow is quite obvious. General improved phase-shift control methods can reduce the power backflow of the ...
详细信息
ISBN:
(纸本)9781479957774
In the conventional phase-shift control of isolated bidirectional DC-DC converters, the phenomenon of power backflow is quite obvious. General improved phase-shift control methods can reduce the power backflow of the input. However, they do not take the power backflow of the output into consideration. In this paper, a novel phase-shift control of isolated bidirectional DC-DC converters for unidirectional power flow is proposed. It can eliminate the power backflows of both the input and the output at the same time. Furthermore, the converters in the proposed phase-shift control can achieve the zero-current switching in the whole power rang. Experimental results from a prototype verify the feasibility and validity of the proposed control method, and show superior performance.
Online partial discharge monitoring for powerequipments is useful to improve the capacity of the power supply. Main technology for PD testing is introduced in this paper. Advantages and disadvantages of pulse current...
详细信息
ISBN:
(纸本)9789881532329
Online partial discharge monitoring for powerequipments is useful to improve the capacity of the power supply. Main technology for PD testing is introduced in this paper. Advantages and disadvantages of pulse current, UHF, ultrasonic and TEV method are present. The status quo of online PD monitoring is analyzed, and the detection effect of online PD monitoring is not good. Opinions to improve the effect are given. They include built-in sensors, increasing sensitivity and sample rate. Analysis of the state quo indicates that the relevant technical standards and specifications must be revised to improve the normalization and standardization.
Based on summarizing the features of selecting critical flowgates in actual power grid, an automatic discovery method of powersystem critical flowgates considering multiple security themes in power grid is proposed. ...
详细信息
Based on summarizing the features of selecting critical flowgates in actual power grid, an automatic discovery method of powersystem critical flowgates considering multiple security themes in power grid is proposed. Based on topological structure of power grid and online power flow, the electric partitioning of power grid is performed and different types of critical flowgates are selected according to different security theme: according to the demand on transient security theme the long-distance transmission channel composed by tie line between electric partitionings is chosen as critical flowgate;according to the demand on thermal stability theme, the transmission channel composed of high voltage transmission lines with high transmission capacity, which interact each other obviously, is chosen as critical flowgate;according to the thermal stability at load side the transmission channel composed of low voltage transmission lines with higher transmission capacity, which interact each other obviously, is chosen as critical flowgate. Taking Guangdong power Grid in China as testing example, test results show that the proposed method considers common security themes in power grid accurately and different kinds of critical flowgates can be attained;the obtained critical flowgates not only conform to a posteriori critical flowgate given by experts in the field of power grid operation, and new critical flowgates can be discovered, besides, the discovery results are reasonable and creditable.
暂无评论