In this paper, an analytical framework to evaluate the along-wind-induced dynamic responses of a transmission tower is presented. Two analytical models and a new method are developed： （1） a higher mode generalized ...In this paper, an analytical framework to evaluate the along-wind-induced dynamic responses of a transmission tower is presented. Two analytical models and a new method are developed： （1） a higher mode generalized force spectrum （GFS） model of the transmission tower is deduced; （2） an analytical model that includes the contributions of the higher modes is further derived as a rational algebraic formula to estimate the structural displacement response; and （3） a new approach, applying load with displacement （ALD） instead of force, to solve the internal force of transmission tower is given. Unlike conventional methods, the ALD method can avoid calculating equivalent static wind loads （ESWLs）. Finally, a transmission tower structure is used as a numerical example to verify the feasibility and accuracy of the ALD method.展开更多
The effect of static transmission error on nonlinear dynamic response of the spiral bevel gear system combining with time-varying stiffness and backlash was investigated.Firstly,two different control equations of the ...The effect of static transmission error on nonlinear dynamic response of the spiral bevel gear system combining with time-varying stiffness and backlash was investigated.Firstly,two different control equations of the spiral bevel gear model were adopted,where the static transmission error was expressed in two patterns as predesigned parabolic function and sine function of transmission errors.The dynamic response,bifurcation map,time domain response,phase curve and Poincare map were obtained by applying the explicit Runge-Kutta integration routine with variable-step.A comparative study was carried out and some profound phenomena were detected.The results show that there are many different kinds of tooth rattling phenomena at low speed.With the increase of speed,the system enters into stable motion without any rattling in the region(0.72,1.64),which indicates that the system with predesigned parabolic function of transmission error has preferable capability at high speed.展开更多
An adjustable bed is a supporting structure designed to provide a seating base or platform, for a 5.0 KW micro steam turbine generator plant prior to its mounting on a block-type concrete foundation. The design of the...An adjustable bed is a supporting structure designed to provide a seating base or platform, for a 5.0 KW micro steam turbine generator plant prior to its mounting on a block-type concrete foundation. The design of the bed frame and flanges was carried out by considering the predetermined weights of the turbine and generator (alternator) [1]. On this basis, steel materials of U-channels and angle irons were used in the fabrication of the generator bed. The bed was designed to be adjustable by accommodating direct coupling of the turbine with the generator, and the belt drive. Fabrication was carried out by welding, machining, and assembly. During assembly, the bed was made to accommodate damping materials in order to reduce the vibration of the plant [2]. The performance of the unit with or without vibration isolator when they are axially connected with flexible flange coupling or transversely connected with sets of belt and pulley, in succession respectively. The results showed that a reduction in the force transmitted to the supporting structure occurred when the vibration produced by the unit is isolated from its base by the use of a vibration isolator, maximum reduction of 99.95% achieved when axially coupled and 99.91% when transversely connected with belt and pulley system [3].展开更多
Relieving network congestions is a critical goal for the safe and flexible operation of modern power systems, especially in the presence of intermittent renewables or distributed generation. This paper deals with the ...Relieving network congestions is a critical goal for the safe and flexible operation of modern power systems, especially in the presence of intermittent renewables or distributed generation. This paper deals with the real-time coordinated operation of distributed static series compensators(DSSCs) to remove network congestions by suitable modifications of the branch reactance. Several objective functions are considered and discussed to minimize the number of the devices involved in the control actions, the total losses or the total reactive power exchanged, leading to a non-convex mixed-integer non-linear programming problem. Then, a heuristic methodology combining the solution of a regular NLP with k-means clustering algorithm is proposed to get rid of the binary variables, in an attempt to reduce the computational cost. The proposed coordinated operation strategy of the DSSCs is tested on several benchmark systems, providing feasible and sufficiently optimal solutions in a reasonable time frame for practical systems.展开更多
基金National Natural Science Foundation of China Under Grant No.50638010Foundation of Ministry of Education for Innovation Group Under Grant No. IRT0518
文摘In this paper, an analytical framework to evaluate the along-wind-induced dynamic responses of a transmission tower is presented. Two analytical models and a new method are developed： （1） a higher mode generalized force spectrum （GFS） model of the transmission tower is deduced; （2） an analytical model that includes the contributions of the higher modes is further derived as a rational algebraic formula to estimate the structural displacement response; and （3） a new approach, applying load with displacement （ALD） instead of force, to solve the internal force of transmission tower is given. Unlike conventional methods, the ALD method can avoid calculating equivalent static wind loads （ESWLs）. Finally, a transmission tower structure is used as a numerical example to verify the feasibility and accuracy of the ALD method.
基金Project(2011CB706800) supported by the National Basic Research Program of ChinaProject(51275530) supported by the National Natural Science Foundation of China
文摘The effect of static transmission error on nonlinear dynamic response of the spiral bevel gear system combining with time-varying stiffness and backlash was investigated.Firstly,two different control equations of the spiral bevel gear model were adopted,where the static transmission error was expressed in two patterns as predesigned parabolic function and sine function of transmission errors.The dynamic response,bifurcation map,time domain response,phase curve and Poincare map were obtained by applying the explicit Runge-Kutta integration routine with variable-step.A comparative study was carried out and some profound phenomena were detected.The results show that there are many different kinds of tooth rattling phenomena at low speed.With the increase of speed,the system enters into stable motion without any rattling in the region(0.72,1.64),which indicates that the system with predesigned parabolic function of transmission error has preferable capability at high speed.
文摘An adjustable bed is a supporting structure designed to provide a seating base or platform, for a 5.0 KW micro steam turbine generator plant prior to its mounting on a block-type concrete foundation. The design of the bed frame and flanges was carried out by considering the predetermined weights of the turbine and generator (alternator) [1]. On this basis, steel materials of U-channels and angle irons were used in the fabrication of the generator bed. The bed was designed to be adjustable by accommodating direct coupling of the turbine with the generator, and the belt drive. Fabrication was carried out by welding, machining, and assembly. During assembly, the bed was made to accommodate damping materials in order to reduce the vibration of the plant [2]. The performance of the unit with or without vibration isolator when they are axially connected with flexible flange coupling or transversely connected with sets of belt and pulley, in succession respectively. The results showed that a reduction in the force transmitted to the supporting structure occurred when the vibration produced by the unit is isolated from its base by the use of a vibration isolator, maximum reduction of 99.95% achieved when axially coupled and 99.91% when transversely connected with belt and pulley system [3].
基金supported by the Spanish Ministry of Economy and Competitiveness (No. ENE2017-84813-R)the CERVERA research program of the Spanish Industrial and Technological Development Centre (CDTI) under the research project HySGrid+(CER-20191019)Junta de Andalucía (No. P18-TP-3655)。
文摘Relieving network congestions is a critical goal for the safe and flexible operation of modern power systems, especially in the presence of intermittent renewables or distributed generation. This paper deals with the real-time coordinated operation of distributed static series compensators(DSSCs) to remove network congestions by suitable modifications of the branch reactance. Several objective functions are considered and discussed to minimize the number of the devices involved in the control actions, the total losses or the total reactive power exchanged, leading to a non-convex mixed-integer non-linear programming problem. Then, a heuristic methodology combining the solution of a regular NLP with k-means clustering algorithm is proposed to get rid of the binary variables, in an attempt to reduce the computational cost. The proposed coordinated operation strategy of the DSSCs is tested on several benchmark systems, providing feasible and sufficiently optimal solutions in a reasonable time frame for practical systems.
