本文根据压水堆(Pressurized Water Reactor,PWR)堆芯燃料组件间定向横流与湍流交混等流动换热特性,提出了一种基于Sub栅元尺度的压水堆堆芯子通道计算分析方法,通过细致划分Sub栅元控制体,建立高分辨率三维动量源模型,自主开发了基于...本文根据压水堆(Pressurized Water Reactor,PWR)堆芯燃料组件间定向横流与湍流交混等流动换热特性,提出了一种基于Sub栅元尺度的压水堆堆芯子通道计算分析方法,通过细致划分Sub栅元控制体,建立高分辨率三维动量源模型,自主开发了基于此方法的压水堆堆芯精细栅元子通道分析程序CUNLUN。选取OECD/NEA MATiS-H和EPRI NESTOR国际基准题进行数值模拟验证。在MATiS-H国际基准题中,4个不同位置的轴向速度平均相对误差为9.07%,该程序可以准确评估压水堆堆芯的热工水力特性。在NESTOR国际基准题中,32个对比点内有24个点的计算精度提升69.08%,表明高分辨率三维动量源模型可以有效提高CUNLUN代码的计算精度。本代码能为压水堆堆芯热工水力分析提供有效的设计和研究手段,对反应堆堆芯热工水力分析程序的开发提供借鉴与参考。展开更多
Well-controlled resource allocation is crucial for promoting the performance of multiple input multiple output orthogonal frequency division multiplexing(MIMO-OFDM) systems. Recent studies have focused primarily on tr...Well-controlled resource allocation is crucial for promoting the performance of multiple input multiple output orthogonal frequency division multiplexing(MIMO-OFDM) systems. Recent studies have focused primarily on traditional centralized systems or distributed antenna systems(DASs), and usually assumed that one sub-carrier or sub-channel is exclusively occupied by one user. To promote system performance, we propose a sub-channel shared resource allocation algorithm for multiuser distributed MIMO-OFDM systems. Each sub-channel can be shared by multiple users in the algorithm, which is different from previous algorithms. The algorithm assumes that each user communicates with only two best ports in the system. On each sub-carrier, it allocates a sub-channel in descending order, which means one sub-channel that can minimize signal to leakage plus noise ratio(SLNR) loss is deleted until the number of remaining sub-channels is equal to that of receiving antennas. If there are still sub-channels after all users are processed, these sub-channels will be allocated to users who can maximize the SLNR gain. Simulations show that compared to other algorithms, our proposed algorithm has better capacity performance and enables the system to provide service to more users under the same capacity constraints.展开更多
新能源场站的次/超同步振荡给电力系统的安全稳定运行造成威胁,调相机可以在一定程度上抑制次/超同步振荡。为进一步发挥调相机抑制振荡的能力,提出一种基于储能型双馈调相机的多通道附加阻尼控制策略。首先,设计针对特定频段振荡的附...新能源场站的次/超同步振荡给电力系统的安全稳定运行造成威胁,调相机可以在一定程度上抑制次/超同步振荡。为进一步发挥调相机抑制振荡的能力,提出一种基于储能型双馈调相机的多通道附加阻尼控制策略。首先,设计针对特定频段振荡的附加阻尼控制器,公共耦合点(point of common coupling,PCC)的电流信号经过附加阻尼控制器调制后被输出到机侧控制系统,调节调相机的无功输出实现对系统振荡的有效抑制;其次,根据移相环节的相位补偿偏差将控制器划分为多个通道,每个通道针对特定频段进行振荡抑制;然后,使用Prony算法提取功率振荡信号进行阻尼比计算,评估多通道附加阻尼控制器的振荡抑制效果;最后,在单机系统及新能源场站系统中进行仿真,结果表明多通道附加阻尼控制策略能够显著提高储能型双馈调相机对次/超同步振荡的抑制能力。该策略提高了新能源场站的小干扰稳定性,有利于新能源发电的长期可持续发展。展开更多
文摘本文根据压水堆(Pressurized Water Reactor,PWR)堆芯燃料组件间定向横流与湍流交混等流动换热特性,提出了一种基于Sub栅元尺度的压水堆堆芯子通道计算分析方法,通过细致划分Sub栅元控制体,建立高分辨率三维动量源模型,自主开发了基于此方法的压水堆堆芯精细栅元子通道分析程序CUNLUN。选取OECD/NEA MATiS-H和EPRI NESTOR国际基准题进行数值模拟验证。在MATiS-H国际基准题中,4个不同位置的轴向速度平均相对误差为9.07%,该程序可以准确评估压水堆堆芯的热工水力特性。在NESTOR国际基准题中,32个对比点内有24个点的计算精度提升69.08%,表明高分辨率三维动量源模型可以有效提高CUNLUN代码的计算精度。本代码能为压水堆堆芯热工水力分析提供有效的设计和研究手段,对反应堆堆芯热工水力分析程序的开发提供借鉴与参考。
基金Project supported by the National High-Tech R&D Program(863) of China(Nos.2012AA01A502 and 2012AA01A505)
文摘Well-controlled resource allocation is crucial for promoting the performance of multiple input multiple output orthogonal frequency division multiplexing(MIMO-OFDM) systems. Recent studies have focused primarily on traditional centralized systems or distributed antenna systems(DASs), and usually assumed that one sub-carrier or sub-channel is exclusively occupied by one user. To promote system performance, we propose a sub-channel shared resource allocation algorithm for multiuser distributed MIMO-OFDM systems. Each sub-channel can be shared by multiple users in the algorithm, which is different from previous algorithms. The algorithm assumes that each user communicates with only two best ports in the system. On each sub-carrier, it allocates a sub-channel in descending order, which means one sub-channel that can minimize signal to leakage plus noise ratio(SLNR) loss is deleted until the number of remaining sub-channels is equal to that of receiving antennas. If there are still sub-channels after all users are processed, these sub-channels will be allocated to users who can maximize the SLNR gain. Simulations show that compared to other algorithms, our proposed algorithm has better capacity performance and enables the system to provide service to more users under the same capacity constraints.
文摘新能源场站的次/超同步振荡给电力系统的安全稳定运行造成威胁,调相机可以在一定程度上抑制次/超同步振荡。为进一步发挥调相机抑制振荡的能力,提出一种基于储能型双馈调相机的多通道附加阻尼控制策略。首先,设计针对特定频段振荡的附加阻尼控制器,公共耦合点(point of common coupling,PCC)的电流信号经过附加阻尼控制器调制后被输出到机侧控制系统,调节调相机的无功输出实现对系统振荡的有效抑制;其次,根据移相环节的相位补偿偏差将控制器划分为多个通道,每个通道针对特定频段进行振荡抑制;然后,使用Prony算法提取功率振荡信号进行阻尼比计算,评估多通道附加阻尼控制器的振荡抑制效果;最后,在单机系统及新能源场站系统中进行仿真,结果表明多通道附加阻尼控制策略能够显著提高储能型双馈调相机对次/超同步振荡的抑制能力。该策略提高了新能源场站的小干扰稳定性,有利于新能源发电的长期可持续发展。
