Papers by Author: Jian He

Abstract: Under the influence of the view that reactive power compensation on-spot, the study on control of reactive power and voltage in wind farms focused on a single wind farm optimal reactive voltage control. China's wind power resources are relatively concentrated and a region often have several or even a dozen wind farms. Wind farm thought as a unit to adjust often leads to irrational reactive power flow. Wind farm groups and collection substations must be thought together as a whole to manage. This paper makes use of collection substations to support area voltage, coordinates reactive power output of the wind farm groups based on the voltage sensitivity and improves the overall grid voltage level of the wind farm groups areas. Simulation results proved that the program can improve the regional power grid voltage level.

Abstract: Stiffened plate is widely used in vessel structure because of its high bearing capacity and low weight so the research of failure probability for stiffened plate under explosion load has important engineering meaning. Stiffened plate under near-field explosion is taken as research subject, dynamite density and yield stress of plate are selected as random variables, the original values of one hundred groups of random variables are gotten through the random number generation program, and the moments of random variables are obtained. Based on failure criterion of displacement ductility, the performance function of structure is established, probability density function of performance function is fitted using maximum entropy method then the failure probability of stiffened plate structure is obtained. So as to solve the problem of calculate failure probability when the sample size is small and the probability density function is unknown.

Abstract: Stiffened plate is a common structure form in plate and shell structure. There are important theoretical significance and project application value on studying dynamic response of stiffened plate subjected to air explosive loading. The motion equation of orthotropic plate which subjected to explosive loading is established adopting Lagrange’s equation of motion, and the stiffened plate where the stiffener is arranged uniformly is treated as textural orthotropic plate. Then the motion equation of the orthotropic plate is converted into motion equation of the stiffened plate. Therefore the maximum deformation of stiffened plate can be determined.

Abstract: Based on the characteristics of loading condition of ship structure in service and the degeneration of the strength under fatigue and corrosion, the random time-variant model of ship hull section modulus was set up using the theory of random process. Then the time-variant reliability was analyzed with the method of up-crossing analysis and parallel system reliability. This method could not only present successive decrease of reliability of the ship structure under fatigue and corrosion, but also avoid the complicated numerical integration. It could be seen that this method was easy to achieve. Furthermore, the time-variant reliability was compared with the annual instantaneous reliability through an example, which indicated that this method was more precise, and could provide some references to the decision-making of the reliability, maintenance and safeguard.