This paper deals with the three-dimensional dynamics and postbuckling behavior of flexible supported pipes conveying fluid, considering flow velocities lower and higher than the critical value at which the buckling in...This paper deals with the three-dimensional dynamics and postbuckling behavior of flexible supported pipes conveying fluid, considering flow velocities lower and higher than the critical value at which the buckling instability occurs. In the case of low flow velocity, the pipe is stable with a straight equilibrium position and the dynamics of the system can be examined using linear theory. When the flow velocity is beyond the critical value, any motions of the pipe could be around the postbuckling configuration(non-zero equilibrium position) rather than the straight equilibrium position, so nonlinear theory is required. The nonlinear equations of perturbed motions around the postbuckling configuration are derived and solved with the aid of Galerkin discretization. It is found, for a given flow velocity,that the first-mode frequency for in-plane motions is quite different from that for out-of-plane motions. However, the second-or third-mode frequencies for in-plane motions are approximately equal to their counterparts for out-of-plane motions, keeping almost constant values with increasing flow velocity. Moreover, the orientation angle of the postbuckling configuration plane for a buckled pipe can be significantly affected by initial conditions, displaying new features which have not been observed in the same pipe system factitiously supposed to deform in a single plane.展开更多
With the extensive integration of high-penetration renewable energy resources,more fast-response frequency regulation(FR)providers are required to eliminate the impact of uncertainties from loads and distributed gener...With the extensive integration of high-penetration renewable energy resources,more fast-response frequency regulation(FR)providers are required to eliminate the impact of uncertainties from loads and distributed generators(DGs)on system security and stability.As a high-quality FR resource,community integrated energy station(CIES)can effectively respond to frequency deviation caused by renewable energy generation,helping to solve the frequency problem of power system.This paper proposes an optimal planning model of CIES considering FR service.First,the model of FR service is established to unify the time scale of FR service and economic operation.Then,an optimal planning model of CIES considering FR service is proposed,with which the revenue of participating in the FR service is obtained under market mechanism.The flexible electricity pricing model is introduced to flatten the peak tieline power of CIES.Case studies are conducted to analyze the annual cost and the revenue of CIES participating in FR service,which suggest that providing ancillary services can bring potential revenue.展开更多
基金supported by the National Natural Science Foundation of China (Grants 11602090, 11622216, and 11672115)
文摘This paper deals with the three-dimensional dynamics and postbuckling behavior of flexible supported pipes conveying fluid, considering flow velocities lower and higher than the critical value at which the buckling instability occurs. In the case of low flow velocity, the pipe is stable with a straight equilibrium position and the dynamics of the system can be examined using linear theory. When the flow velocity is beyond the critical value, any motions of the pipe could be around the postbuckling configuration(non-zero equilibrium position) rather than the straight equilibrium position, so nonlinear theory is required. The nonlinear equations of perturbed motions around the postbuckling configuration are derived and solved with the aid of Galerkin discretization. It is found, for a given flow velocity,that the first-mode frequency for in-plane motions is quite different from that for out-of-plane motions. However, the second-or third-mode frequencies for in-plane motions are approximately equal to their counterparts for out-of-plane motions, keeping almost constant values with increasing flow velocity. Moreover, the orientation angle of the postbuckling configuration plane for a buckled pipe can be significantly affected by initial conditions, displaying new features which have not been observed in the same pipe system factitiously supposed to deform in a single plane.
基金supported by the National Key R&D Program of China(No.2018YFB0905000)National Natural Science Foundation of China(No.51961135101)。
文摘With the extensive integration of high-penetration renewable energy resources,more fast-response frequency regulation(FR)providers are required to eliminate the impact of uncertainties from loads and distributed generators(DGs)on system security and stability.As a high-quality FR resource,community integrated energy station(CIES)can effectively respond to frequency deviation caused by renewable energy generation,helping to solve the frequency problem of power system.This paper proposes an optimal planning model of CIES considering FR service.First,the model of FR service is established to unify the time scale of FR service and economic operation.Then,an optimal planning model of CIES considering FR service is proposed,with which the revenue of participating in the FR service is obtained under market mechanism.The flexible electricity pricing model is introduced to flatten the peak tieline power of CIES.Case studies are conducted to analyze the annual cost and the revenue of CIES participating in FR service,which suggest that providing ancillary services can bring potential revenue.
