Applied Mechanics and Materials Vols. 543-547

Abstract: An ultrasonic guide instrument with temperature compensation circuit has been designed. How to realize and design hardware and software of the circuit has been illustrated. The effect from temperature compensation on the instruments ranging accuracy has been verified, Results show that the instrument can operate steadily under a great temperature difference. This is a practical method.

Abstract: With the wide application of high voltage direct current, it also created some problems, such as transformers dc bias. This article describes the impact on the transformer of the operation of HVDC monopole mode, introducing the model used in the soil and the ground electrode potential distribution, it also calculates the ground voltage in the case of a single or double ring grounding .Besides this paper describes the potential level of the two layers of soil structure calculation method and uses this method to analyze the influence on 220kV station of the 500kV Tian-Guang HVDC monopole operation mode. The conclusion is that the operation mode has seriously affected the station.

Abstract: Large scale wind power penetration has a significant impact on the reliability of the electric generation systems. A wind farm consists of a large number of wind turbine generators (WTGs). A major difficulty in modeling wind farms is that the WTG not have an independent capacity distribution due to the dependence of the individual turbine output on the same energy source, the wind. In this paper, a model of the wind farm output power considering multi-wake effects is established according to the probability distribution of the wind speed and the characteristic of the wind generator output power: based on the simple Jenson wake effect model, the wake effect with wind speed sheer model and the detail wake effect model with the detail shade areas of the upstream wind turbines are discussed respectively. Compared to the individual wake effect model, this model takes the wind farm as a whole and considers the multi-wakes effect on the same unit. As a result the loss of the velocity inside the wind farm is considered more exactly. Furthermore, considering the features of sequentially and self-correlation of wind speed, an auto-regressive and moving average (ARMA) model for wind speed is built up. Also the reliability model of wind farm is built when the output characteristics of wind power generation units, correlation of wind speeds among different wind farms, outage model of wind power generation units, wake effect of wind farm and air temperature are considered. Simulation results validate the effectiveness of the proposed models. These models can be used to research the reliability of power grid containing wind farms, wind farm capacity credit as well as the interconnection among wind farms

Abstract: In order to further grasp the overhead rules of transmission line de-icing, this thesis designed and developed a newly transmission line icing apparatus, which can acquire the needed ice thickness covered upon a certain transmission line in laboratory. Combined with the walk-in temperature and humidity box, the temperature tester, current generator and other equipment, enhance the technology research capacity of overhead lines ice-melting. And the software can simulate the overlying ice temperature and cloud distribution changes with time, verify the line ice-melting rules. The method can be easily extended to other types of wires, and has certain application value.

Abstract: An optical system which collimate the light of LED uniformly is proposed in this paper. This optical system consist of two part of optical surface. First a TIR lens collimate all of the light of the LED parallel to the z axis. Then the first reflector redirect the collimating light to a uniform distribution and the second reflector collimate the uniform light pattern. The simulation result of the designed system shows that the uniformity of the output wave-front is 0.78 and the total efficiency of the system is 89.32%.

Abstract: Low-pass filter is an integral part of lock-in amplifier, low-pass FIR or IIR filter is typically used in lock-in amplifier, which need a large number of multiplications and occupy more hardware resources. To reduce cross-correlation computing requirement of multiplications, this paper, designed orthogonal vector lock-in amplifier based on the down-sampling dual mean filter. Experiments show that, the digital amplifier has good detection performance and noise or clutter suppression. Keywords: lock-in amplifier, mean filter, down-sampling, Gaussian noise suppression, clutter suppression.

Abstract: The problem of power system reactive power optimization is a mathematical problem with multiple variables and constraints, which is complex and non-linear. The control variables include continuous variables and discrete variables; its difficult to get the optimal solution. A solution in power flow calculation is put forward after the mathematical model of wind farm is built in this paper. Based on this, taking the WSCC 9 nodes system as an example, use the particle swarm algorithm to solve the reactive power optimization problem. The result shows that this algorithm has an apparent positive effect on reducing system power loss and improving system voltages.

Abstract: Low temperature economizer is an efficient way to recover the flue gas waste and to improve the efficiency of the boiler. Several basic layout of low temperature economizer are introduced in this paper. Layout is divided into flue gas side arrangement and water side arrangement. In this paper, combined with the parameters of a 600 mw, the economy of the different configuration is calculated and compared.

Abstract: The work mainly by the front level attenuator, the LC tuned amplifier, the push-pull output stage is composed. The first level weakens 40dB fixedly through pi the attenuator realization. Front the double grid field effect manages 3SK223 to make the level to increase the controllable LC tuned amplifier, the LC resonance by double harmonious and the list harmonious cascade way, enhanced the system selectivity. The complete machine gain is bigger than the 80dB, AGC control area to achieve above 60dB.The output stage uses the low pressure high electric current high speed axle to the axle structure integration operational amplifier OPA2354 push-pull transformer coupling output, sharpened the belt load capacity greatly. In order to reduce the amplifier as far as possible the noise and ceases the high frequency auto excitation, this design has adopted the power source filter, the shield, electromagnetic compatibility, the interstate coupling, the impedance matching and so on many kinds of measures. After the test, this plan has completed completely the basic function and the expansion function. Sweeps the frequency source turning on input end after CPLD self-made DDS, May very convenient see the system frequency response on the oscilloscope.

Abstract: For the study of distributed generation and its impact on power system, this paper briefly introduces the basic concept, the advantages of distributed generation, and the concept and basic structure of micro-grid. From the power system planning, system voltage, power quality, island effect, relay protection and other aspects, this paper analysis and discusses the influence of distributed power on power system. To properly resolve the grid-connected distributed generation power influence, it will be helpful for the development of future of distributed power generation. Distributed power generation can be used not only as an important supplement of the traditional centralized power supply mode, but also as a very important role in energy utilization, it will become an important area of research and development in future energy.