A novel method, which utilizes harmonic for excitation, is presented to adjust the air-gap magnetic field for permanent magnet synchronous machine. The structure and basic principles of the hybrid excitation PM synchr...
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A novel method, which utilizes harmonic for excitation, is presented to adjust the air-gap magnetic field for permanent magnet synchronous machine. The structure and basic principles of the hybrid excitation PM synchronous generator(HEPMSG) are introduced. The no-load and on-load electromagnetic field are calculated based on finite element method, and the waveform and effective value of the winding voltage and characteristics of the machine are gained for different loads. Calculation results demonstrate the new hybrid excitation scheme is feasible. This new method combines the advantages of PM machines and electrical excitation machines. The machine removes the brushes and slip rings, which makes permanent magnet machine keep simple and highly reliable.
MW level photovoltaic generation has enough power to support the partial loads in the island operations. But the challenge is how to balance the power supply and load while the power grid is blackout, and the power su...
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MW level photovoltaic generation has enough power to support the partial loads in the island operations. But the challenge is how to balance the power supply and load while the power grid is blackout, and the power supply changes to PV power. In response to this question, the anti-islanding strategy is replaced by balancing the PV output and the load shedding in paper to achieve the available maximum power balance in distribution substation. It is achieved by collecting all feeders currents (power supply and feeder outputs), which is realized in the digital substation based on IEC61850. The system scheme and the dynamic emergency control strategy to inverters in PV controller are introduced in paper. The work of the paper is valued to the research on the novel dynamic control scheme in distribution system with DGs.
The corona performance and the electromagnetic environment of the transmission system has become a crucial issue that has been taken into consideration in the line design, and among which audible noise (AN) is one of ...
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ISBN:
(纸本)9781424456215
The corona performance and the electromagnetic environment of the transmission system has become a crucial issue that has been taken into consideration in the line design, and among which audible noise (AN) is one of the most important factors. The wind in the high altitude area is mostly strong, and could greatly influence the AN. This paper, based on the high altitude HDVC test line, studied the characteristics of AN generated by the transmission line, and analyzed the influence of wind velocity and wind direction on the AN lateral profile.
Shielding failure of lightning is the key problem for safe operation of UHV transmission lines. Taking the feature of 1000KV AC double circuit transmission lines into account, the leader progression method with proper...
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ISBN:
(纸本)9781424456215
Shielding failure of lightning is the key problem for safe operation of UHV transmission lines. Taking the feature of 1000KV AC double circuit transmission lines into account, the leader progression method with proper criterion was employed. The lightning shielding failure rate of top phase, middle phase and bottom phase of two different transmission line tower types were compute, in three different geography conditions. The research work is helpful for improving the lightning performance of UHV transmission lines.
The Ultra High Voltage DC power transmission technique is developed quickly in China but used barely in the world. Corona phenomenon in high altitude region is more serious, and corresponding electromagnetic environme...
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ISBN:
(纸本)9781424456215
The Ultra High Voltage DC power transmission technique is developed quickly in China but used barely in the world. Corona phenomenon in high altitude region is more serious, and corresponding electromagnetic environment is more severe as well. A UHVDC test lines are completed for tests in Kunming, China, with an altitude of 2100 m. An automotive electromagnetic environment testing system was installed under the line. Measurement of electromagnetic environment was carried out. Radio interference, audible noise, resultant electric field and ion current density at ground level were measured at different voltage from ±800kV to ±1000kV, and atmosphere conditions including sunny, rainy and cloudy weather. The measured result show some difference with those acquired at sea level and is significant for further studies of corona mechanism under high altitude condition. Measured results were compared with the calculated results.
Corona phenomenon of Ultra High Voltage DC in high altitude region is more serious, and corresponding electromagnetic environment is more severe as well. Radio Interference is the most important consideration during t...
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ISBN:
(纸本)9781424456215
Corona phenomenon of Ultra High Voltage DC in high altitude region is more serious, and corresponding electromagnetic environment is more severe as well. Radio Interference is the most important consideration during the design and operation. Characteristics of RI and its influence factors were studied based on an UHVDC test line with an altitude of 2100 m in the National Engineering laboratory for UHV Technology, located in Kunming, China. The measuring system of RI long term tests was introduced. Lateral and longitudinal distribution and spectrum of RI near the transmission line were analysed at various voltages, weather conditions.
The paper analyses the existed protection of microgrid. And in order to meet the requirements of microgrid protection, a novel protection is presented in this paper. The protection based on local information without t...
The paper analyses the existed protection of microgrid. And in order to meet the requirements of microgrid protection, a novel protection is presented in this paper. The protection based on local information without the need of communication, uses current traveling waves to identify faulted feeder, and the bus bar voltages to determine a event caused by fault or switch operation. In the protection scheme, current traveling waves are measured by current transducers in N line and phase lines, and wavelet multi-resolution analysis is used to decompose traveling wave signals. The initial traveling waves are compared in magnitude and polarity with each other to determine the faulted feeder. The protection is independent of microgrid operation connected with the main power grid or in island.
Cascaded H-Bridge rectifier (CHBR) is a more attractive solution in traction application for its transformerless structure. Because of the currents of different cells are exactly the same one, it is a challenge job to...
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Cascaded H-Bridge rectifier (CHBR) is a more attractive solution in traction application for its transformerless structure. Because of the currents of different cells are exactly the same one, it is a challenge job to regulate the voltages of cells with only one current controller. In this paper, a PI-based control scheme is presented to deal with the voltages balance issue in CHBR. To satisfy the demand of rectifier such as unity power factor and regulated output DC voltages, the proposed control scheme consists of two parts. One is for shaping the grid current waveform and regulating the sum of DC-link voltages of all the cells; the other one is for balancing DC-link voltages. The latter is more concerned in this paper and is discussed in detail especially. simulations and experiments are carried on. The results verified the feasibility and effectiveness of the proposed scheme.
The hybrid excitation permanent magnet machine (HEPMM) combines two kinds of excitation: permanent magnet (PM) and electrical excitation, so it possesses the advantages of PM machines and overcomes the incapability of...
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ISBN:
(纸本)9788986510119
The hybrid excitation permanent magnet machine (HEPMM) combines two kinds of excitation: permanent magnet (PM) and electrical excitation, so it possesses the advantages of PM machines and overcomes the incapability of regulating the excitation field. By now many HEPMM schemes have been presented. In this paper the operation principle, structure, advantages and disadvantages of these HEPMMs have been reviewed and compared in detail. These HEPMMs are classified into three types by new classification method - placement of PM and iron poles. At last novel harmonic excitation HEPMM is proposed and discussed.
The hybrid excitation permanent magnet machine (HEPMM) combines two kinds of excitation: permanent magnet (PM) and electrical excitation, so it possesses the advantages of PM machines and overcomes the incapability of...
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The hybrid excitation permanent magnet machine (HEPMM) combines two kinds of excitation: permanent magnet (PM) and electrical excitation, so it possesses the advantages of PM machines and overcomes the incapability of regulating the excitation field. By now many HEPMM schemes have been presented. In this paper the operation principle, structure, advantages and disadvantages of these HEPMMs have been reviewed and compared in detail. These HEPMMs are classified into three types by new classification method - placement of PM and iron poles. At last novel harmonic excitation HEPMM is proposed and discussed.
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