Applied Mechanics and Materials Vols. 321-324

Abstract: This paper presented a new improved Prony algorithm based on neural network to train weights.The algorithm solved some problems that difficulty and low precision during matrix inversion in Prony method. According to real-time transform characteristics of low frequency oscillation in power system, the algorithm used limited data windows in on-line parameter estimation and pattern recognition, and improved pattern recognition precision. The simulation results proved that this proposal algorithm has some features of directly ,effective, high reliability, less calculation amount and minor error when it be used to analysis oscillation characteristics and mode identification. So it is suitable for identification of low frequency oscillation mode in power system.

Abstract: The crosslinking agent (DCP) was added to LDPE.The blend was crosslinked at different process temperature.The breakdown voltage and indurance time of samples prepared under different process were observed. Experiment results showed that the breakdown voltage and indurance time were determined by the crosslinking temperature.They were reduced with the increase of temperature. when the the experiment temperature exceeded 90 degrees.The decline was intensified.

Abstract: The hardware design and software design of network transformation to relay electric control system of the original mine hoist are introduced. Double PLC and computer control technology is adapted in the transformation project, in order to improve intelligent level of hoist control system. The monitoring system was design to monitor the hoist running state on line and realize remote monitoring through network. The systems successful transformation had done a leap from old relay-contact control to automatic control. Test running shows that, running safely and reliably and stabile performance of the system satisfies design requirements of hoist transportation.

Abstract: The objective of this work is to research on a SVC auto-compensation method to improve the power factor of the power supply system. Firstly, the principles of the reactive power compensation of FC+TCR are analyzed qualitatively. According to the deficiencies of this compensator, a novel SVC auto-compensating method based on the variable reactor is presented. The reactor controlled by anti-parallel thyristors is namely as the variable reactor in this method. The secondary-side equivalent inductance of the variable reactor is varied by adjusting the SCR firing angles. And then, the equivalent inductance of the variable reactor of the compensator branch is adjusted indirectly for compensating the corresponding reactive power after the working conditions of the load are changed. Therefore, the auto-compensating of this var compensator is realized. The auto-compensating principles of this compensator have been analyzed, and a research on the compensating parameters of this compensator is given emphatically in this paper. Finally, the essential operation steps of this SVC compensation method are given. The research of this paper has laid a theoretical foundation for this compensator in industrial applications.

Abstract: Ozone is widely used in industry or even home nowadays, the power supply with frequency and duty cycle easy-adjust feature is very important to ozone production. An intelligent power supply based on MCU system is introduced in this paper, Intelligent Power Module (IPM) is used to compose a full bridge inverter circuit, and PWM technology is used to drive the IGBTs integrated in the IPM. The frequency and duty of the output AC can be adjusted manually or by auto tracking, and can be displayed synchronously on the LCD. The result shows that the power supply can adjust and display the output frequency and duty cycle by keyboard manually or by auto tracking based on detected current, and ozonizer have a higher efficiency with adjustable output frequency and duty cycle.

Abstract: In case of the arc suppression coil for neutral point grounding of small current grounding system, when single-phase grounding fault occurs, due to the arc suppression coil for fault line of the compensation effect of the zero sequence current, the fault features is not obvious, it can't implement the fault line selection and fault point location. This paper puts forward a method of change fault lines zero sequence current shortly, namely a resistance inductance (RL) series branch parallel in arc suppression coil, the series branch acts on the system shortly and changes arc suppression coil compensation degree temporarily in single-phase grounding fault. The change of zero sequence residual current only appears the loop from the neutral point to the fault point via the fault line, using FTU (feeder terminal units) on lines monitor the change of zero sequence current on each nodes for fault regional location. And prove this theory the feasibility of the by using MATLAB software of system modeling simulation method.

Abstract: A high amplitude, fast rising time, and high isolating strength trigger signal is needed for triggering spark gap switch. A high voltage power supply scheme was verified by means of simulation in this paper. Proper parameters of power supply circuit were selected according to the simulation result. Finally, a pulsed power supply was developed. The experimental results show that a negative pulse with 25 kV isolating strength and 15 kV amplitude can be generated by the power supply, and this generated negative pulse can meet the demand of triggering spark gap switch.

Abstract: In order to accurately evaluate sensitive equipment failure rate caused by voltage sag, the concept of credibility measure is introduced to measure the uncertainty of equipment failure event. This evaluation measure can avoid the deficiencies containing in classical probability measure which needs a large number of testing samples. The uncertainty of failure event is presented by a fuzzy measure where the membership function of equipment voltage tolerance curve corresponding to the characteristic quantities in the uncertain area was determined by fuzzy statistical and a polynomial fit method. Then the credibility distribution function was determined. The proposed evaluation model of sensitive equipment failure rate caused by voltage sag is developed. Using the practical testing samples, the personal computer (PC) was evaluated by the proposed method. Comparing the proposed method with current methods, the results have shown that the proposed method is proper, correct and credible. This method may be more practicable in practical condition.

Abstract: In high power converter design, low-inductance busbar connecting DC capacitors and power devices is main concern to improve the quality of the whole power electronics system. This paper analyzes the impact of layer-number on the stray inductance of busbar taking a subway traction converter as example. The method of partial element equivalent circuit and the Q3D software were used to extract the stray inductance. The simulation and experimental results show that the stray inductance of three-layer busbar is lower than two-layer busbar with other same conditions.

Abstract: An electrostatic film vibration voltage transducer（EFVVT，Electrostatic Film Vibration Voltage Transducer）is presented in this paper. The theoretical model is derived particularly. A high voltage is measured based on sensing of the film vibration displacement. The application of high precision measurement method of the film micro-displacement is also introduced into the EFVVT. The simulation measurement system is built up by the transfer function in the Simulink environment and the result shows that the measurement accuracy of the EFVVT is good enough which can reach a 0.2 class in the 110kV voltage level in a 20%~150% rated voltage range.