A flexible flat torque converter was proposed to fulfill the requirement of miniaturization and power density maximization for automobiles.Constructed by two arcs joined by lines,the torus was designed directly from d...A flexible flat torque converter was proposed to fulfill the requirement of miniaturization and power density maximization for automobiles.Constructed by two arcs joined by lines,the torus was designed directly from design path.The influence of flatness on the performance of the torque converter was evaluated.The software CFX and standard k-ε model were adopted to simulate the internal flow fields of the torque converter under different flatness ratios.The results indicated that the performance of the torque converter got worse as the flatness declined,but the capacity of pump increased.The efficiency and the torque ratio dropped slightly as the flatness ratio decreased.So the torque converter could be squashed appropriately to get high power density without too much efficiency sacrifice.But when the flatness ratio was below 0.2,there was a significant drop in the efficiency.展开更多
The application of a novel Particle Swarm Optimization (PSO) method called Fitness Distance Ratio PSO (FDR PSO) algorithm is described in this paper to determine the optimal power dispatch of the Independent Power Pro...The application of a novel Particle Swarm Optimization (PSO) method called Fitness Distance Ratio PSO (FDR PSO) algorithm is described in this paper to determine the optimal power dispatch of the Independent Power Producers (IPP) with linear ramp model and transient stability constraints of the power producers. Generally the power producers must respond quickly to the changes in load and wheeling transactions. Moreover, it becomes necessary for the power producers to reschedule their power generation beyond their power limits to meet vulnerable situations like credible contingency and increase in load conditions. During this process, the ramping cost is incurred if they violate their permissible elastic limits. In this paper, optimal production costs of the power producers are computed with stepwise and piecewise linear ramp rate limits. Transient stability limits of the power producers are also considered as addi-tional rotor angle inequality constraints while solving the Optimal Power Flow (OPF) problem. The proposed algo-rithm is demonstrated on practical 10 bus and 26 bus systems and the results are compared with other optimization methods.展开更多
根据交直流互联电网出现的直流落点谐波从高电压级向低电压级的传导过程和低电压级非线性负荷谐波向高电压级的扩散过程的不同,提出了一种基于等效注入电流的城市电网谐波传导特性分析方法,将两种情况下的谐波电流在谐波国标框架下统一...根据交直流互联电网出现的直流落点谐波从高电压级向低电压级的传导过程和低电压级非线性负荷谐波向高电压级的扩散过程的不同,提出了一种基于等效注入电流的城市电网谐波传导特性分析方法,将两种情况下的谐波电流在谐波国标框架下统一,得出一致行为评价。注意到城市电网电缆大量使用带来的高次谐波放大,提出潮流谐波比作为输送单位基波潮流的谐波含量评价指标,用以评价由电网参数变化以及电缆使用带来的谐波变化。应用所提方法计算了在某直流落点从500 k V变电站到10 k V母线谐波传导过程,并与实测数据相比较,揭示了谐波从高电压级向低电压级的传导规律和分析了城市电网电缆使用引起的谐波放大,验证了方法的有效性。展开更多
基金Supported by the National Natural Science Foundation of China (50905016)
文摘A flexible flat torque converter was proposed to fulfill the requirement of miniaturization and power density maximization for automobiles.Constructed by two arcs joined by lines,the torus was designed directly from design path.The influence of flatness on the performance of the torque converter was evaluated.The software CFX and standard k-ε model were adopted to simulate the internal flow fields of the torque converter under different flatness ratios.The results indicated that the performance of the torque converter got worse as the flatness declined,but the capacity of pump increased.The efficiency and the torque ratio dropped slightly as the flatness ratio decreased.So the torque converter could be squashed appropriately to get high power density without too much efficiency sacrifice.But when the flatness ratio was below 0.2,there was a significant drop in the efficiency.
文摘The application of a novel Particle Swarm Optimization (PSO) method called Fitness Distance Ratio PSO (FDR PSO) algorithm is described in this paper to determine the optimal power dispatch of the Independent Power Producers (IPP) with linear ramp model and transient stability constraints of the power producers. Generally the power producers must respond quickly to the changes in load and wheeling transactions. Moreover, it becomes necessary for the power producers to reschedule their power generation beyond their power limits to meet vulnerable situations like credible contingency and increase in load conditions. During this process, the ramping cost is incurred if they violate their permissible elastic limits. In this paper, optimal production costs of the power producers are computed with stepwise and piecewise linear ramp rate limits. Transient stability limits of the power producers are also considered as addi-tional rotor angle inequality constraints while solving the Optimal Power Flow (OPF) problem. The proposed algo-rithm is demonstrated on practical 10 bus and 26 bus systems and the results are compared with other optimization methods.
文摘根据交直流互联电网出现的直流落点谐波从高电压级向低电压级的传导过程和低电压级非线性负荷谐波向高电压级的扩散过程的不同,提出了一种基于等效注入电流的城市电网谐波传导特性分析方法,将两种情况下的谐波电流在谐波国标框架下统一,得出一致行为评价。注意到城市电网电缆大量使用带来的高次谐波放大,提出潮流谐波比作为输送单位基波潮流的谐波含量评价指标,用以评价由电网参数变化以及电缆使用带来的谐波变化。应用所提方法计算了在某直流落点从500 k V变电站到10 k V母线谐波传导过程,并与实测数据相比较,揭示了谐波从高电压级向低电压级的传导规律和分析了城市电网电缆使用引起的谐波放大,验证了方法的有效性。
