Applied Mechanics and Materials Vols. 336-338

Abstract: The construction and development of power system have made our country form interconnected power grid. When oscillates occurs without timely disconnected control, accident may spread which will cause stability damage and uncontrollable chain reaction. So, how to guarantee the system to make effective out-of-step separation in the critical moment is the significant task in current power system. This paper analyzes the characteristics of electrical quantity after out-of-step, proposes a criterion based on reactive power integral, and does simulation in CEPRI-36-node system. The experimental results show that this control can start from the comprehensive situation, adopt multiport electrical parameter, locate and capture oscillation center accurately, monitor system state timely, adapt to system network structure and operation mode change automatically, recognize condition of out-of-step rapidly.

Abstract: Aiming at how to solve the question of quantitatively distinguish negative damping low frequency oscillation and forced power oscillation, the difference in frequency and damping ratio between the two kinds of oscillations have been discovered through mechanism analysis, and a new quantitative distinction criterion for the property of the low frequency is proposed. The oscillation data is windowing identified by ARMA model based on weighted recursive least squares algorithm dynamically, and low frequency type can be distinguished according to the changes of oscillation frequency and damping ratio during the oscillation. The simulative results have shown that the method is feasible and effective.

Abstract: In navigation war, satellite signals need to be power-enhanced to improve anti-jamming performance, especially in some important areas. A navigation constellation structure is proposed for optimal regional power-enhancing performance. In the structure, GEO and IGSO are adopted to be the basic power-enhanced satellite, all the GEO and IGSO satellite antenna beams are turned to point to the power-enhanced target areas center while power-enhancing. MEO satellites are adopted as complementation to improve satellite coverage performance in power-enhanced area. The design principle is to let the satellite number minimum under the condition of satisfying coverage performance in power-enhancing area. Simulation results show that, for a regional area with the radius less than 1500km, 3GEO and 3IGSO constellation structure can provide a power-enhancing service with average GDOP less than 5.3. When adding 12 MEO satellites, the GDOP can reduce to 2.

Abstract: Smart substation is the tendency of the evolutionary substation in the future and is one key parts of smart grid. The Technical guide for smart substation is published by State Gird Corporation of China for the construction of smart substation. This paper recounts the differences from substation and smart substation, describes the system architecture of smart substation, characteristic of smart equipment and monitors the status of smart equipment. Base on the automation and communication technology, it research on the applications of smart equipment and information technology in smart substation of China. Finally, it prospects the application of smart substation.

Abstract: Under the situation of distribution network construction, evaluating the reliability and comprehensive level of distribution network planning accurately is an important issue in decision-making progress. Based on the analysis of reliability related factors and the inner mechanism of the evaluation process, a reliability-based evaluation methodology of distribution network planning is proposed. Firstly, starting from the study of the reliability and conventional evaluation, a reliability-based index system and its evaluation process are presented. Then, combining the advantage of analytic hierarchy process (AHP) and date envelopment analysis (DEA) as well as Cross-Evaluation, a CE-DEA model with AHP constraint cone is developed for the comprehensive evaluating of distribution network planning scheme. Finally, the simulation results of a factual case are presented and discussed. The proposed methodology and comprehensive evaluation model are illustrated to be effective, providing useful guidance for the distribution network planning.

Abstract: For the problem of 6-DOF serial manipulator position inverse solution, the paper proposed a new method for 6-DOF serial manipulator position inverse solution by introducing the quaternion algorithm. The relative pose transformation expression in quaternion coordinate system is proposed based on the transformation relationship between dual quaternion and double quaternion, based on which the closed equation of 6-DOF serial manipulator position inverse solution times in the form of double quaternion is established. For the obtained four position constraint equations, the Dixon resultant is constructed and a equation of 16 yuan is derived which is neither with increases root nor with the leak root. And this point is proved by the Mathematica practical calculations. The process of the method is simple. And it can not only avoid extraneous roots, but also overcome some singular position caused by the correlation equation in the process of trajectory planning, and further, the real-time performance of control process is improved.

Abstract: This paper elaborates the effect of wind speed on the output power of the wind farms at different locations. It also describes the correction of the power curve and shows the comparison chart of the standard power curve and the power curve after correction. In China's inland areas, wind farms altitude are generally higher, the air density is much different from the standard air density. The effect of air density on wind power output must be considered during the wind farm design.

Abstract: The composite parallel four-bar manipulator multi-objective function simulation by B-splines shows the new method for multi-objective planning trajectory of manipulator is effective. The algorithm minimizes the objective function for optimization. By setting restriction on acceleration, the method has been tested in simulation yielding good results which get the smooth trajectory through the via-points by fourth-order B-splines.

Abstract: Using MCU as the control core, combined with a variety of sensors, based on the PID control algorithm, a robot is developed with a flexible mechanism and low price which can carry small cargoes. The paper introduces the principle, the working process of the system and analyses the application prospect of the robot in the field of logistics.

Abstract: A novel adjustable magnetic field adhesion mechanism for use in wall-climbing robot is designed. The magnetic field in air gap can be switchable by rotating the center axis of adhesion mechanism so that the magnetic adhesion force is variable and it is conveniently for robot adhesion and detachment from the wall. The influence of structure parameters on adhesion performance and the optimal dimensions of mechanism are obtained by parameter variation method for best performing design. The novel optimal mechanism has been dimensioned and its magnetic force is measured. The results are compared to the simulation and it is shown that it is one of the best performing of magnet designs published for wall climbing robot adhesion mechanism.