Advanced Materials Research Vols. 354-355

Abstract: In practice, the getting product data types have ordinary real number, interval-valued in real number field, fuzzy set in real number field. In order to dispose these data simultaneously, a new generalized closeness degree is proposed in this paper. And then make it applied to reliability prediction. The new generalized closeness degree is getting through the weighted fusion with two of commonly used closeness degree. lattice close-degree Based on membership degree, and measure close-degree Based on area ratio. According calculating the characteristic factors’ close-degree between the awaiting predicting product and the case products, for every attribute value distributing a weight, prediction result is obtained by integrating the data.

Abstract: The topic research, standard device for power frequency lines parameters tester, can be used for calibrating the power frequency lines parameters tester. The equip functions involve: positive/zero sequence impedance, positive/zero sequence capacitance, etc. The topic introduces the working principle and composition of the standard device, focusing on the technology of virtual complex impedance and accurately amplitude control. The paper end gives the relevant specification and experimental data. The research of the standard device can be used to resolve the traceability of power frequency lines parameters tester.

Abstract: A new method of fuzzy multiple reference models adaptive control(FMRMAC) for dealing with significant and unpredictable system parameter variations is presented. In this method, different suitable reference model is chosen by fuzzy rules when changes occurred to the model parameters. A successful application to the speed servo system of dynamic model of induction motor (IM) shows this method works well with high dynamic performance under the condition of command speed change and load torque disturbance.

Abstract: When single-line-to-ground fault happen in neutral non-effectively earthed system, there is a big difference between the fault feeder and un-fault feeder in transient signal energy centralized frequency band and signal amplitude of fault phase. The transient signal energy in fault feeder’s fault phase is bigger, and it centralizes in lower frequency band. But the transient signal in un-fault feeders’ has the contrary features. And this feature is affected little by the fault initial angle. So the paper proposed a method that using the gravity frequency and transient signal energy to form a two-dimension line selection method that using the signal overall distribution characteristics. It can be applied in neutral unearthed and resonant system simultaneously. And the method is effectively to different fault initial angle and fault resistance. The method is proved correctly, effectively and adaptively by actual simulation in different fault cases.

Abstract: According to the characteristics of fire process, this paper does some research in fire detection, combining the gray system theory and fuzzy reasoning, and makes the simulation experiment. The simulation results show that this method has satisfied identification effects, which can effectively reduce the rate of false positives and shorten the alarm time of judging that whether there is fire and what’s the type of it.

Abstract: Combined with the existing research results, the heat transfer property of Pulsating Heat Pipe (PHP) was analyzed on the basis of experimental data processing in multi-operating conditions. PHP could self-repair when heat transfer was deteriorated, and the operating temperature continued to rise with the increased heating power during the operation. This study would contribute to the safe and effective operating; moreover, it could lay foundations for the fundamental investigation of PHP.

Abstract: The mathematical model for thermokinetic characteristics of an irreversible reciprocating Brayton cycle has been analyzed. The analytical formulas of the specific work and the actual cycle thermal efficiency are derived, taking the variable specific heats of working fluid and the irreversibility in the compressor and the turbine into account. The model mentioned above has carried on the numerical calculus under typical circulation performance parameters. The results show that the variable specific heat and the internal efficiency of both the compressor and the turbine have an obvious influence on the cycle performance, and the internal efficiency of both the compressor and the turbine have more remarkable influence on the cycle performance. The results obtained in this paper may provide a theoretical guide for the assessment and improvement of the performance of actual gas turbine engines.

Abstract: Power Electronic Transformer (PET) has potential application value in distribution network. This paper presents a novel PET with only one stage single-phase to single-phase AC/AC converter at the primary side of the transformer, the high voltage end, which generates high-frequency alternating voltage. The secondary side of the transformer, the low voltage end, is also one stage AC/AC converter, by which low power frequency voltage can be created. The final stage is a resistive converter obtaining low DC output voltage and unitary input power factor. Consequently, the unitary power factor can be reflected to the mains side and the PET owns a four-quadrant operation capability. The theory of four-quadrant PET is analyzed and the simulation analysis using MATLAB/SIMULINK is also provided. The result shows that this kind of PET holds some prominent advantages such as simple structure, easy to control, safe commutation, unitary input power factor, bidirectional power flow and easy to cascade. So it has application value.

Abstract: For the existence of a large input current harmonic content and the problem of low power factor, we propose an idea using APFC technical to design high power factor switching power supply to deal with it, meanwhile, the design process of APFC circuit parameters of the various components is given. Finally, the design proved to be correct and feasible by the simulation with Saber.

Abstract: This paper presents a novel and practical method for monitoring harmonic impedances of power systems seen at load serving substations. The method uses the natural load fluctuations measured at the substation for impedance estimation. It avoids the needs for intrusive disturbances and can be used for online tracking of impedance parameters. The method has been verified through several real field measurements.