Applied Mechanics and Materials Vol. 492

Abstract: This paper has propose a new metering control system. From the control system, analysis the valve characteristics of heat metering control system. In the design of new heating metering control system, it is critical for electric valve closes when the appropriate degree of opening. Determine the adjustable range of indoor temperature,indoor the most at operating frequency, temperature and other indicators of the dynamic response time. In this paper, the mathematical model of the room heating calculation based on device characteristics through an example for solving typical temperature and time as a function of flow rate. The instantaneous heat dissipation radiator heat in the room, the electric valve to maintain the closed state. when the room temperature is not lower than the lower limit. By analysis the flow,when the coefficient is 0.59, the total cumulative time calories minimum number of the electric valve operations tends to 0, the system is the most efficient.

Abstract: Through theoretical calculations and derivation, the paper obtained the relationship between resistance coefficient and pressure difference, as well as flow rate. For the series pipeline, the flow in the series pipeline is the same, as a result, all the resistance in the series pipeline is the total resistance. For the parallel pipeline, the pressure difference is same, and the all the flow in parallel pipeline is the total flow. According to the real example, the paper identified the inlet pressure difference of the indoor system, the most unfavorable ring and the ratio frictional resistance. Based on the room heat load calculation, the paper determined the most unfavorable loop diameter of each pipe section. By calculating the resistance coefficients of the electric valve at opening, the resistance coefficients of the electric valve at closing were obtained. In the experiment system, the resistance coefficient average value when the electric valve is off was 101831.65, which is basically in line with the calculable value 10719.6, indicating that the existing parameters are much more reasonable.

Abstract: The paper describes the main factors of influencing increase cropper electrolysis current density.The main circuit and the control circuit of cycle reverse rectification power for copper electrolysis are designed. The simulation and practical results show the cycle reverse electrolysis power based active disturbance rejection controller has high reliability and precision of steady current and anti-disturbance,the density of electrolysis current can be increased and anode passivation can be decreased ，the effect is better especially for high impurities of anode sheets. the energy-saving and lower costs and high quality and increase of output are achieved. this technology is practicable.

Abstract: To solve the disadvantage of limited numbers of CAN messages which are received and transferred by TTC200 controller, this paper has studied and verified the CAN buffer Multiplexing technique in the system of Battery-Ultracapacitor used by hybrid bus. Test results show that the data collected by buffer Multiplexing can meet the requirements for data real-time acquisition and accuracy. The problem of misread and miss with different ID does not exist.

Abstract: The objective of this paper is to present the application of microcontroller dsPIC30F6012A to measure the harmonics current and electrical power by using the Fourier series method to calculate the electrical parameters. This design is to develop the low cost harmonics instrument and to focus on working with the single phase AC system. The prototype was then developed to measure the harmonics current and power factor, and the result was compared with the standard instrument. The result is that most electrical parameters have the measurement errors of less than 4.0%. However, this idea could be developed so that it applies in the related work with the power quality measurement.

Abstract: The incomplete probabilistic information can lead to imprecision. The traditional power system risk assessment can only deal with random information, but it cannot deal with the imprecise information. Interval Probability (IP) can reflect both randomness and imprecision. The risk assessment of power system based on IP is an effective method to deal with imprecision and can provide more useful information to the decision-makers. In the paper, the completeness degree of probabilistic information was depicted by IP. The nonlinear optimization models for imprecise risk assessment of generating system and composite generation-transmission system were established. And the genetic algorithm was used to obtain the upper and lower bound of reliability indices. Case study on revised IEEE-RTS79 and IEEE-RBTS system showed the rationality and equity of presented method.

Abstract: This article is devoted to the principles of power equipment technical state assessment at 35-220 kV substations. The article deals with the network hybrid model construction using methods of fuzzy logic and artificial neural network. Finally, in order to construct the knowledge base, a methodology of the power equipment technical state assessment, based on the membership functions, is introduced.

Abstract: In order to improve the power generation benefit of the Tianhu Hydropower Station, a optimal operation model of the water supply system of the power station is built to maximize the gross electric energy generated. The model takes into consideration that Tianhu Hydropower Station has multiple water supply modes and is characterized by its super-high water head, and that any small change on flow control may bring great impact on the output of the power station. Based on existing hydrological data and the optimal scheduling model, the optimized results are calculated and made to optimization curves. These optimization curves are used to guide the operation of the hydropower station. Years of actual practices demonstrated that operating Tianhu Hydropower Station under the guidance of the optimal reservoir group operation model presented in this paper has brought in significant economic benefits, with an annual increase in power generation income of more than eight million yuan.

Abstract: Wind power prediction is very important to maintain the power balance and economic operation of power system. The BP and RBF neural network were respectively used to predict one wind turbines’ output power, in 4 hours, on a wind farm in Shandong Province. The results show that the BP model, with 6-13-1 net structure and considering the meteorological factors, exhibits the best prediction accuracy (MAPE is 3.59%, NRMSE is 1.58%). The most important factor in the meteorological information for power prediction is temperature, followed by air pressure, relative humidity finally. BP model is slightly better than RBF model, but the latter is much better in the learning speed and stability. Dynamic-BP neural network, combined with the dynamical weight adjustment method, is better than BP neural network in solving the weight problem. These methods are feasible to the wind power prediction.

Abstract: The statistical wind data obtained from measurements for the 12 month period of January to December 2008 at Benina, Benghazi, Libya. The site coordinates are: latitude 32,05N and longitude 20,13E. The elevation of the site is 136 m above mean sea level (AMSL). The wind speed has been measured at height of 10 m above the ground level using 3 cup anemometers. Moreover wind speed has been estimated at height of 40 m. The statistical wind data set was analyzed using weibull distributions in order to investigate the weibull shape and scale parameters at 10 m and 40 m height. Finally, the yearly power density has been estimated at both heights. The results showed that strong and sufficient winds for power generation are available at most of months in Benina region.