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A new digital prediction method by integrating circuit computation and linear estimation is proposed to achieve high-precision energy charge and discharge operations of a superconducting magnet. The principle and implementation processes are presented by considering a bridge-type chopper circuit. The simulation results verify the feasibility of the proposed method to achieve high-precision energy...
A new bridge-type chopper topology using MOSFETs is proposed and studied for superconducting magnetic energy storage (SMES) applications for use in low-voltage end-user sides. Both the bridge-type and conventional choppers are theoretically analyzed and experimentally compared. The dynamic energy exchange characteristics of SMES for solving the voltage swell and voltage sag problems are presented...
A space vector pulse width modulation (SVPWM) signal source based on Virtual Instrument (VI) and related DAQ devices is presented in this paper. In addition, using the developed SVPWM signal source, a close-loop control system of permanent magnet linear synchronous motor (PMLSM) has also been built. To increase the drive's performance, the field oriented control (FOC) scheme and point-to-point trajectory...
Currently a controlled SCR-based bridge type solid state fault current limiter (SSFCL) without a DC bias needs up to ten millisecond acting time to limit a fault current. An improved model of high temperature superconducting (HTS) FCL for a single phase system was proposed and analyzed in this paper. The proposed SSFCL system has a rectifying bridge connected with a HTS coil without a bias voltage...
Comprehensive consider grid catastrophic accident is influenced by the uncertainties of weather, environment, and network topology, to establish grid introduced to reflect the economic factors of risk assessment models and a comprehensive index system. Determine the risk indicators of relative weight by Analytic Hierarchy Process, and the fuzzy simulation methods is applied to assess the risk of catastrophic...
This paper introduces the advanced sensor technique and ANN. It describes application of the sensors in transformer fault diagnosis in detail. Further, the transformer fault diagnosis artificial neural network (TFDANN) is developed. The feasibility and effectiveness of TFDANN are explained by some examples for transformer fault diagnosis.
The three-level inverter Space Vector Pulse Width Modulation (SVPWM) method is researched, in accordance with the calculation of the vector variation a triangle rotational relations is proposed, which can make the time calculation and time state allocation modules be simplified and improved. Compared with the traditional SVPWM control method, its control becomes more simple and easy to implement....
A battery charge-discharge control strategy which based on the single Z-source three-level space vector pulse width modulation (SVPWM) inverter and the designed corresponding closed-loop control system is proposed. The inverter can not only eliminate the transformer or DC/DC converter link in traditional system, but also realize charger-discharge control in the case of a large range of battery voltage...
Weakly electric fish employ active electrolocation for orientation and navigation in their environment at night and thus able perceive an electrical image of their surroundings even in complete darkness. This principle of active electrolocation is adopted to design a technical sensor system. In this paper, we conducted the underwater active electrolocation experiments in different water conductivities...
This paper presents a bridge type solid state superconducting fault current limiter (SFCL) based on MOSFETs. It has a rectifying bridge connected with a superconducting coil without a bias voltage source. The SFCL integrated with the electrical network has been simulated by Matlab/Simulink. The theory analysis, simulation model and analysis result have been presented. It proves the theoretical prediction...
Some tiny metallic particles generated due to the manufacturing process as well as the mechanical operation in the compressed gas-insulated transmission line, which may induce breakdown should be cleared from the volume of the apparatus not only at the very beginning of the manufacturing period but also during the operation cycle. In the operation period the metal particles are trapped in the electromagnetic...
Overvoltage is a threat to the security of power transmission lines, it is important to get the actual amplitude and waveform of the lightning overvoltage. This paper proposes a contactless overvoltage transducer for overhead transmission lines overvoltage monitoring. By a certain structure arrangement, the overhead transmission line conductor and the transducer forms a capacitive voltage divider,...
Harmonic currents elimination are significant for improving efficiency and reliability for wind power system with PMSG. Several factors can induce harmonic current, in which the most significant is back EMF distortion. In order to compensate the voltage distortion, we propose a harmonic elimination method in multiple synchronous rotating reference frames in this paper. Different orders of current...
The purpose of our present study is to understand the Superconductor-Insulator Transition. In this paper we report tunnel experiments on Bi2Sr2Ca1−xYxCu2O8+δ (Y-Bi2212) crystals with x = 0, 0.01, 0.05, 0.1, 0.11 and 0.12. The results are discussed about Copper pairs existing. Tunneling spectra were measured for Y-Bi2212 crystal-SiO-Ag planar junctions. For superconducting samples the V-shape gap structure...
Voltage Source Inverters (VSIs) generally use the multi-loop control strategy, while single-loop control strategy has been proposed. In order to maintain low total harmonic distortion content in the output voltage, resonant controllers with parallel structure have also been commonly adopted. Firstly, the parameter design problems for the parallel resonant controllers are discussed. On this basis,...
Nowadays, the impulse characteristics of capacitive voltage transformer have caused extensive concern among scholars. This paper proposes a distributed parameter model of capacitive voltage transformer. Simulation calculation is used to research the impulse response of capacitive voltage transformer with the influence on signal distortion of transformer considered. Results indicate that impulse response...
In designing lightning insulation margin of substation equipment in China, the attenuation and distortion of intruding wave caused by corona in the transmission lines is neglected, thus making too strict insulation requirements on the electrical equipment, what's more, the impulse corona has a great impact on the shielding failure and lightning resisting level of ultra high voltage alternating current...
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