Flexible AC transmission systems(FACTS)devices can effectively optimize the distribution of power flow.Power flow entropy can be applied as a measure of load distribution.In this paper,a method is proposed to optimize...Flexible AC transmission systems(FACTS)devices can effectively optimize the distribution of power flow.Power flow entropy can be applied as a measure of load distribution.In this paper,a method is proposed to optimize the distribution of power flow with the coordination of multi-type FACTS devices and establishes the corresponding mathematical models.The modified group searcher optimization(GSO)algorithm is proposed,in which the angle search is combined with chaotic search model to avoid jumping into local optimization.Compared with the different optimal allocation of multi-FACTS devices,the optimal allocation of multi-FACTS devices is achieved under the economic constraints.The locations obtained by this method can achieve the purpose of balancing power flow and enhancing the system performances.The simulations are demonstrated in an IEEE 118-bus power system with two classical types of FACTS,namely static var compensator(SVC)and thyristor controlled series Compensator(TCSC).The simulation results show that the proposed method is feasible and effective.展开更多
The popularity of insulated gate bipolar transistors(IGBTs)for use in high-voltage direct current(HVDC)transmission and flexible AC transmission systems(FACTS)is increasing.Unfortunately,for these applications wire-bo...The popularity of insulated gate bipolar transistors(IGBTs)for use in high-voltage direct current(HVDC)transmission and flexible AC transmission systems(FACTS)is increasing.Unfortunately,for these applications wire-bond IGBT technology has a number of shortcomings,such as insufficient current ratings for the most powerful schemes,and inability to fail to short-circuit.Press-pack IGBT technology,conversely,offers increased current ratings,and an inherent short-circuit failure mode,making it a more attractive choice for HVDC and FACTS.However,the design and manufacture of these devices requires a comprehensive understanding of the unique technical challenges,which differ markedly from those for wirebond modules or traditional pressure contact devices.Specific challenges include providing a high degree of mechanical protection for the IGBT chip against normal operating stresses.Furthermore,it is essential to achieve uniform contact pressure across each chip surface to ensure optimum performance.To achieve this,manufacturers have designed products that use rigid copper electrodes manufactured to tighter tolerances than for other pressure contact devices,such as thyristors,and products that use compliant electrodes,incorporating spring assemblies.Dynex is in the advanced stages of development of press-pack IGBT technology with demonstrated robust solutions for the technical challenges outlined in this paper.Design success has been achieved through the use of state-of-the-art simulations in conjunction with a long history of manufacturing expertise for bipolar and IGBT products.Finally,multiple press-pack IGBT variants are currently undergoing evaluation tests prior to product release.展开更多
To study the vibration transmission character istics of a flexible carbody and its suspended equipment, a vertical mathematical model of highspeed electric multiple unit was established with equipment excitation consi...To study the vibration transmission character istics of a flexible carbody and its suspended equipment, a vertical mathematical model of highspeed electric multiple unit was established with equipment excitation considered. And the dynamic unbalance and impact turbulence excita tion from equipment were taken into account in a single stage and twostage vibration isolation system, respectively. Results show that the excitation transferred to carbody increases with suspension stiffness but decreases with the equipment mass increasing; the vibration transmission can be reduced by increasing the equipment mass or reduce the suspension stiffness. To avoid vibration resonance, the dynamic unbalance frequency of equipment should be out of the possible range of the carbody flexible modes, and a small stiffness should be applied to reduce the impact tur bulence. A small stiffness, however, would result in a large movement of the equipment which is limited by the static deflection requirement, while a great stiffness will transfer high frequency vibration. Therefore, a preferred stiffness should make the suspension frequency of equipment a bit greater than the first bending mode of carbody. Additionally, a 3D rigidflexible coupled dynamics model was built to verify the mathematical analysis, and they show good agreements. Results show that a twostage isolation could reduce the excitation transmission and make the vibration of carbody and equipment acceptable.展开更多
The main objective of this paper is three-fold.First, to provide an overview of the current status of the power electronics technology, one of the key actors in the upcoming smart grid paradigm enabling maximum power ...The main objective of this paper is three-fold.First, to provide an overview of the current status of the power electronics technology, one of the key actors in the upcoming smart grid paradigm enabling maximum power throughputs and near-instantaneous control of voltages and currents in all links of the power system chain. Second, to provide a bridge between the power systems and the power electronic communities, in terms of their differing appreciation of how these devices perform when connected to the power grid. Third, to discuss on the role that the power electronics technology will play in supporting the aims and objectives of future decarbonized power systems. This paper merges the equipment, control techniques and methods used in flexible alternating current transmission systems(FACTS) and high voltage direct transmission(HVDC) equipment to enable a single, coherent approach to address a specific power system problem, using ‘best of breed’ solutions bearing in mind technical, economic and environmental issues.展开更多
基金This work was funded by National Science and Technology Support Program of China(2010BAE00816).
文摘Flexible AC transmission systems(FACTS)devices can effectively optimize the distribution of power flow.Power flow entropy can be applied as a measure of load distribution.In this paper,a method is proposed to optimize the distribution of power flow with the coordination of multi-type FACTS devices and establishes the corresponding mathematical models.The modified group searcher optimization(GSO)algorithm is proposed,in which the angle search is combined with chaotic search model to avoid jumping into local optimization.Compared with the different optimal allocation of multi-FACTS devices,the optimal allocation of multi-FACTS devices is achieved under the economic constraints.The locations obtained by this method can achieve the purpose of balancing power flow and enhancing the system performances.The simulations are demonstrated in an IEEE 118-bus power system with two classical types of FACTS,namely static var compensator(SVC)and thyristor controlled series Compensator(TCSC).The simulation results show that the proposed method is feasible and effective.
文摘The popularity of insulated gate bipolar transistors(IGBTs)for use in high-voltage direct current(HVDC)transmission and flexible AC transmission systems(FACTS)is increasing.Unfortunately,for these applications wire-bond IGBT technology has a number of shortcomings,such as insufficient current ratings for the most powerful schemes,and inability to fail to short-circuit.Press-pack IGBT technology,conversely,offers increased current ratings,and an inherent short-circuit failure mode,making it a more attractive choice for HVDC and FACTS.However,the design and manufacture of these devices requires a comprehensive understanding of the unique technical challenges,which differ markedly from those for wirebond modules or traditional pressure contact devices.Specific challenges include providing a high degree of mechanical protection for the IGBT chip against normal operating stresses.Furthermore,it is essential to achieve uniform contact pressure across each chip surface to ensure optimum performance.To achieve this,manufacturers have designed products that use rigid copper electrodes manufactured to tighter tolerances than for other pressure contact devices,such as thyristors,and products that use compliant electrodes,incorporating spring assemblies.Dynex is in the advanced stages of development of press-pack IGBT technology with demonstrated robust solutions for the technical challenges outlined in this paper.Design success has been achieved through the use of state-of-the-art simulations in conjunction with a long history of manufacturing expertise for bipolar and IGBT products.Finally,multiple press-pack IGBT variants are currently undergoing evaluation tests prior to product release.
基金supported by the National Science and Technology Support Program of China (No. 2011 BAG10B01)the National Key Basic Research Program of China (No. 2011CB711100)+1 种基金the National Science and Technology Support Program of China (No. U1334206)the New Century Excellent Talents of Ministry of Education funded project (No. NCET-10-0664)
文摘To study the vibration transmission character istics of a flexible carbody and its suspended equipment, a vertical mathematical model of highspeed electric multiple unit was established with equipment excitation considered. And the dynamic unbalance and impact turbulence excita tion from equipment were taken into account in a single stage and twostage vibration isolation system, respectively. Results show that the excitation transferred to carbody increases with suspension stiffness but decreases with the equipment mass increasing; the vibration transmission can be reduced by increasing the equipment mass or reduce the suspension stiffness. To avoid vibration resonance, the dynamic unbalance frequency of equipment should be out of the possible range of the carbody flexible modes, and a small stiffness should be applied to reduce the impact tur bulence. A small stiffness, however, would result in a large movement of the equipment which is limited by the static deflection requirement, while a great stiffness will transfer high frequency vibration. Therefore, a preferred stiffness should make the suspension frequency of equipment a bit greater than the first bending mode of carbody. Additionally, a 3D rigidflexible coupled dynamics model was built to verify the mathematical analysis, and they show good agreements. Results show that a twostage isolation could reduce the excitation transmission and make the vibration of carbody and equipment acceptable.
基金supported by Spanish Ministry of Economy and Competitiveness and Junta de Andalucía through the projects ENE2014-54115-R and TEP-7411
文摘The main objective of this paper is three-fold.First, to provide an overview of the current status of the power electronics technology, one of the key actors in the upcoming smart grid paradigm enabling maximum power throughputs and near-instantaneous control of voltages and currents in all links of the power system chain. Second, to provide a bridge between the power systems and the power electronic communities, in terms of their differing appreciation of how these devices perform when connected to the power grid. Third, to discuss on the role that the power electronics technology will play in supporting the aims and objectives of future decarbonized power systems. This paper merges the equipment, control techniques and methods used in flexible alternating current transmission systems(FACTS) and high voltage direct transmission(HVDC) equipment to enable a single, coherent approach to address a specific power system problem, using ‘best of breed’ solutions bearing in mind technical, economic and environmental issues.
