Applied Mechanics and Materials Vols. 556-562

Abstract: Aiming at the problems that the traditional active power filter (APF) which is with limited bandwidth and is difficult to realize zero steady-state error control, we use a strategy based on multiple synchronous rotating coordinate for each harmonic separation to achieve the detection of selective harmonic and proportion-integral (PI) control. Then it’s able to implement zero steady-state error compensation. After establishing the mathematical model of harmonic rotating coordinate for the APF, we proposed a simple strategy of current coupling and decoupling. The simulation results and the prototypes’ practical operations proved that the control strategy can compensate for the selective harmonic effectively and respond to the changes of the conditions in time. Meanwhile it has good characteristics in dynamic response.

Abstract: As the primary link and the accepting link of power supply and sale, the quality of business expansion is directly related to the economic benefits and social profile of the power company. By many measures, such as reducing the link of process and delayering business expansion process, realizing multi link synchronous operation and integrally operating all qualified links, the process of high voltage business expansion project is optimized. The practice proves that these measures effectively reduce the average time of power access, and improve the level of power supply service. Keywords: power supply company; business expanding; process optimization; average power access time

Abstract: At present, methods of the navigation and the attitude measurements of projectile utilizing the magnetic fields are facing the interference from the BMF (background magnetic field). The principle and mathematical model of the BMF for the spinning projectile are been researched to realize the high accuracy measurement of the geomagnetic field on projectile. The composition and jamming mechanism of the projectile's BMF are derived with the Faraday electromagnetic induction theory. High precision compensation model of the geomagnetic measurement is established by synthesizing the magnetic sensor error model. Based on the idea of the error transfer, the attitude measuring errors caused by the BMF are analyzed and the error calculation formulas are given. On this basis, numerical simulation is conducted combining with projectile's flight rules. The results show that the influence of attitude angle measuring precisions caused by the background interference magnetic field are much bigger than the errors caused by the sensor noise and the established compensation model has obvious effect. Besides, the effective BMF compensation of geomagnetic measurements on the projectile must be conducted if the attitude angle measurement error is in requirements within ±1 °.

Abstract: It is great significance for development of MTDC (Multi-terminal HVDC) to build DC transmission and distribution grids. However, the relatively low impedance in DC grids makes the fault penetration much faster and deeper .Consequently, fast and reliable DC circuit breaker is needed to isolate faults. Breaking time and other parameters are important for a breaker to achieve its goals. This paper presents a DC circuit breaker with a current-limiting inductance and gets the rising and falling characteristics of fault current. Based on the characteristics, a design method of breaking time sequence will be given, as well as the calculation of current-limiting inductance and the selection principles of arresters. A 10kV DC distribution grid is modeled and simulated by PSCAD/EMTDC to verify that the method can meet the requirements of breaking fault current quickly and reliably.

Abstract: For the deficiencies of traditional wind forecasting method, a wind forecasting method based on improved support vector machine which support any parameters input. The method can compatible with many different types and magnitude data and construct a loop iteration mechanism, based on the wind farm's own situation which constantly prompts to enter the wind speed, season, temperature, humidity, light until it reaches the desired accuracy. For wind power consumptive capacity, the method proposed can obtain the maximum, minimum wind parameters and the range of variation, diverse support vector machine regression model can be produced by learning, which can predict the future of wind energy within a period of time. The method can improve the quality of wind power and grid scheduling, for maintaining grid stability has a very important role.

Abstract: The objective of this work is to study the increase of the convective heat transfer coefficient in the presence of ultrasound waves and, in particular, to find a relationship between the ultrasonic power and the effective pressure of water. The tests have focused on the heat exchange by natural convection, in single-phase conditions, at atmospheric pressure, between a cylinder, heated by means of the Joule effect, and distilled water, with and without the action of ultrasonic waves. The variables involved in the heat exchange have been varied within the range allowed by the experimental apparatus and the convective heat transfer coefficient has been maximized. The specific thermal flow has been chosen in a range compatible with applications in the field of electronics. For the first time the pressure of water at various ultrasonic power levels has been measured, in the vicinity of the cylindrical surface, thanks to the collaboration with the Naval Experimentation and Support Center (CSSN) of the Italian Navy in La Spezia, Italy.

Abstract: Clock is used to enregistering the time and the real-time data collection in the life and the system of the automatic control. The main working principle of DS1302 and programming sought are introduced on the software design. Finally, the system software interactive simulation was completed on the platform of Proteus.

Abstract: In view of the traditional zero-angle memory device with low precision and to reduce errors caused by manual readout, this paper using electro-magnetic technology, designed a new zero-angle memory device based on proximity switch. Experimental results show that the device not only improves the repeatability and reduces the error, but also realize automatic demarcation.

Abstract: According to the principle of a novel integration method with stabilizing voltage and frequency, UPS, intelligent charging for mobile power supply proposed by authors, the mobile UPS system has been developed in this paper. The system is designed by the inverter NB70124 with integration functions and the additional peripheral configuration, such as the touch screen, the circuit breaker, and so on. The following works have been done in the study: the configuration of the mobile UPS system, communication between the touch screen and the inverter, GUI of the mobile UPS system. The system can be realized functions, such as the generating electricity, outputting stabilizing voltage and frequency, UPS, and intelligent charging. By the system, the high precision voltage amplitude and frequency is supply to outdoor load, and the UPS state is maintained.

Abstract: Embedded system is a kind of special computer system that has certain function. Combining it with Multi Media and network technology could increase intelligence and agility of the devices. The use of embedded technology is becoming wider and wider with rapid development of information technology and rapid increase of consumers’ need. This thesis analyzes and studies the application of embedded system through actual project firstly. And then designs an embedded system based on ARM9 processor. Using audio CODEC UDA1341, this design have good effect .