Advanced Materials Research Vols. 516-517

Abstract: In recent years, significant progress has been made with in-deep application of piezoelectric harvesting energy technology. To make the technology development more convenient, a comprehensive review on application of piezoelectric harvesting technology is made in the paper. Piezoelectric harvesting devices as power source from vibration, human motion and so on are expounded. The technology would bring fast increasing in systems of micro wireless sensor, integrated systems and self-power MEMS.

Abstract: With the gradual deepening of electricity market reform, electric power industry has not completely in accordance with the annual consolidated planning to organize the operation and development, but more and more by the macro-economic environment, the coal market fluctuations and other factors. This requires that power enterprise groups in the process of planning and controlling market boundaries to assess the scheme under various boundary conditions of the market. Presented a comprehensive plan of electric power Enterprise assessment method, according to the changing market environment, an amendment to the selected indicators, adjust the index value, so as to better meet corporate management target.

Abstract: Accurate forecast of electric load provides scientific grounds for national departments to plan how to produce electric power or how to use it and it also benefits the maintenance and construction plan of power grid to improve power supply security. Now the demand of electric power in Beijing increases yearly due to sustained economic development, the electric-load-forecast is practical for Beijing to prepare future development of its electric power. This paper selected 1973~2008 data of Beijing to test the causality between economy and electric load. Then it established equation based on cointegration theory to forecast electric load in future years.

Abstract: In recent years, significant progress has been made with in-deep application of piezoelectric harvesting energy technology. To make the technology development more convenient, a comprehensive review on application of piezoelectric harvesting technology is made in the paper. Piezoelectric harvesting devices as power source from vibration, human motion and so on are expounded. The technology would bring fast increasing in systems of micro wireless sensor, integrated systems and self-power MEMS.

Abstract: High voltage distribution network is an important link between transmission and middle voltage distribution network. If a high voltage distribution network fault occurs, the economy and reliability of the whole city distribution system will be seriously affected. To solve this problem, a traditional reconstruction optimization model is improved and a 2-staged reconstruction optimization model is proposed based on an improved particle swarm optimization (PSO) algorithm. The first stage reconstruction only considers the economic goal and the second stage reconstruction needs consider the boundary constrains. The 2-staged method considers the economic benefit and the voltage quality simultaneously. It can achieve the multi goals: meeting actual boundary operation conditions, optimizing the combination of network losses and the number of operation switching. The fault isolation and reconfiguration of an actual distribution network system in Dezhou power grid were simulated. Simulation results validate the rationality and feasibility of the proposed method

Abstract: Causes of induced electromotive force (emf) in other circuit are analyzed when a single loop in control cable is connected to an alternating voltage source in this paper. The size of induced emf and its influence factors are discussed. Based on theoretical analysis and test, the control measures of induced emf in control cable are put forward.

Abstract: The techniques for developing a kind of the precision continuously adjustable high-voltage switching power supply are proposed, based on the constant frequency pulse width modulation strategies with SG3525, and the continuous output voltage adjustment effect is achieved through a gain amplifier controlled by MCU. The circuit is of the significant features such as high precision output voltages, continuously adjustable, a wide adjustment range and a low power consumption. The results of the experiments show that the output voltage is adjustable between 1KV and 25KV, and the maximum output voltage error is 1.6%.

Abstract: Using the finite element analysis, this work analyzed the electric field distribution of 220kV transmission steel tower with double-circuit and composite material transmission tower with the same size, and compared the electric field effect of two materials transmission tower for surroundings. And this work compared the vertical and axial electric field distribution along transmission line of the two materials transmission tower. The results indicate the composite material tower can improve the environment of electric field near the transmission lines.

Abstract: In the smart power grids construction and for the needs of the power distribution reliability，and for the overhaul and maintenance of the power equipment, it is important for all the operation equipment condition being under monitoring. All equipment has its own characteristics. These characteristics give the customizing messages for monitoring the equipment condition. For the overhead lines insulators, its leakage current mainly mirror insulating property and can give out the insulating strength degrading in time. So trying to monitor the insulators leakage current is significant for Electrical safety. In this paper, the polluted insulator leakage current generating mechanism and characteristics in the operating voltage be analyzed, the actual use of the leakage current on-line monitoring methods and equipment be compared. Based on MSP430 single chip, one facility insulator leakage current online monitoring device is developed. This on-line monitoring device make up of leakage current signal acquisition unit, periodically the leakage current signal into the signal processing unit, the microcontroller to process data effectively, and given the alarm in case of problems, and the data stored by the host computer communication module and communication. By preliminary testing on the good and polluted insulator, the test data reflect the polluted insulator leakage current changed condition, and can find out fault insulators nicely.

Abstract: After ten years operation, Tian-Guang HVDC control and protection system will be updated. The Tian-Guang HVDC physical simulation system and RTDS simulation system were set up in this paper. Based on these two simulation systems, the function and dynamic performance of the updated Tian-Guang HVDC C&P system were tested. Totally 30 test groups and more than 300 test items are included in the testing matrix. And the simulation results in the physical simulation system were compared with those in the RTDS simulation system. The C&P software were optimized and improved during the test. The test shows that, the control and protection strategies and parameters used in the upgraded HVDC system perform well and meet the criterion.