电力系统暂态稳定性闭环控制（六）—— 控制地点的选择

基于实时性的要求,提出一种实时快速选择高效阻止失稳的切机地点的方法。按照发电机的有符号动能和功角乘积的大小在超前失稳机群中对可切机组进行排序,得到初始有效切机地点集合,通过计算等值机械功率切机前后的变化,剔除超前失稳机群中的被动失稳机组,得到最终的切机地点集合。IEEE 39节点系统和三华联网系统的仿真结果验证了所提方法的有效性。     

基于权重数值积分的电力电子开关仿真插值算法

随着电力电子技术在电力系统中的广泛应用,电力电子开关引起的高频次系统拓扑突变对电磁暂态仿真提出了新挑战,为此,提出了一种电力电子开关仿真插值算法。在全局隐式梯形积分法条件下,该算法在开关动作点通过线性插值计算系统变量,并利用后向欧拉法对系统进行重新初始化,而后根据插值点在当步仿真步长的位置,利用权重法数值积分,灵活改变积分步长,快速积分至仿真整步时间点,对仿真进行再同步。在开关动作过程中,算法仅通过一次插值对仿真进行重新初始化,并在再同步过程中保持节点导纳矩阵不变,且能有效抑制数值振荡。算法在保证精度的前提下,降低了计算负担,提高了计算速度,并考虑了多重开关问题。最后通过算例验证了算法的适应性和有效性。     

A novel simulation of AC magnetic contactor based on electromagnetic transients program

This paper proposes a new simulation approach for the AC magnetic contactor using the electromagnetic transients program (EMTP). The duality transformation technique is applied to convert a magnetic model into an electrical model. The great advantages of the proposed model are its capability of being directly simulated with other electrical components using EMTP and, therefore, its minimum level of complexity. To enhance the precision of the proposed model, the saturation of magnetic core and the fringing flux effects are taken into account. The performance and accuracy of the proposed model are verified by comparing them with those from finite element method (FEM) simulations and experiments. The results confirm that the proposed model has very good performance and the technique can be further applied to other magnetic components. © 2014 Institute of Electrical Engineers of Japan. Published by John Wiley & Sons, Inc.     

交直流混联电网中交流暂态侵入对直流继电保护的影响分析

为减少交流系统故障情况下直流继电保护误动作事故的发生,引入交流暂态侵入(IAST)的概念,为交直流混联系统中直流继电保护的设计与运行提供新的视角。首先分析了IAST及其暂态响应的机理、形式、特征等。在此基础上,分析了IAST给直流继电保护带来的问题和挑战。结果表明,IAST使得换流器区保护与换流变压器区保护之间的权责不清,导致以100 Hz保护为代表的直流保护与交流保护之间的时序配合不当,影响到直流保护的动作定值与性能。在保证直流输电系统一次设备安全的前提下,可通过改进保护逻辑、优化定值等手段,最大限度地提高交直流混联系统的运行效率和可靠性。     

自适应谱峭度滤波方法及其振动信号检测应用

谱峭度滤波方法是一种在强背景噪声下也能有效提取振动信号中瞬态成分的方法。笔者针对谱峭度滤波方法中窗宽的自适应选择问题,提出一种自适应谱峭度滤波方法。该方法将小波相关滤波提取的振动信号特征频率作为Morlet小波滤波窗口中心频率,并按最大谱峭度原则自适应选择滤波小波窗口宽度,以确定最优带宽Morlet小波窗。通过强背景噪声下的瞬态成分的提取验证该方法的有效性,并与窗口融合自适应谱峭度滤波方法进行比较。针对轴承故障振动信号检测,应用该方法提取反映轴承故障的冲击响应成分,说明该方法能够实现轴承故障振动特征信号的提取。     

MATLAB在系统灾变恢复相关问题研究中的应用

讨论了如何将MATLAB应用于电力系统恢复的仿真研究 ,主要利用MATLAB进行了如下两方面的工作 :以黑启动机组为系统恢复起动电源 ,仿真电网黑启动过程中可能出现的操作过电压和同步发电机的自励磁现象。仿真结果表明 ,与传统的仿真手段相比 ,MATLAB是一种强有力的仿真工具 ,使用它能极大地提高工作效率 ,而且其结果也是值得信赖的。     

南水北调中线工程北京西四环段输水安全分析

水锤是保证长距离输水管道安全的重要技术问题,工程中要避免弥合水锤的发生,降低水锤压力。由于受施工条件的限制,水锤防护措施的安装施工有时非常困难,往往需要作适当调整。根据对南水北调中线京石段应急供水工程北京西四环段通气孔设计,将通气孔概化成半气垫式调压室进行输水管道水力过渡过程计算分析。通过多方案比较分析,低水头长距离输水管道通气孔的设置可以在增加其它安全措施的基础上适当增大设置间距。     

Long‐term transient and metastable effects in cadmium telluride photovoltaic modules

Thin‐film cadmium telluride (CdTe) photovoltaic (PV) technology is poised to begin making significant contributions and impact on terrestrial, electric power generation. However, some outstanding issues such as stability and transient behavior, and their impact on reliability and assessment of performance, remain to be thoroughly addressed, which has prompted some unease among PV industry integrators toward deploying this technology. We explore the issues of long‐term stability and transient behavior in the performance of CdTe modules herein, using data acquired from indoor light‐soaking studies. We find that measurement of current‐voltage parameters and their temperature coefficients are entangled with transient effects. Changes in module power depend on recent operating history, such as electrical bias, and can result in either artificially high or low performance. Both the open‐circuit voltage (V_OC) and fill factor (FF) are significantly impacted by metastable behavior that appears to linger for up to tens of hours, and we observe such increased transient effects after modules have undergone several hundred hours of light exposure. We present and analyze data measured under standard reporting conditions and actual operating conditions for six CdTe modules light‐exposed and stressed at 65°C nominal temperatures. Copyright © 2006 John Wiley & Sons, Ltd.     

新疆下坂地电站水力过渡过程计算

介绍利用程序进行水电站水力过渡过程计算。通过对下坂地水电站的调压室涌波计算、调节保证计算以及调节系统的稳定分析，确定调压室的型式和尺寸、推荐调速器主要参数整定值、提出了调节保证计算成果，并得出结论电站即使孤立运行也能满足小波动稳定性要求，为电站及引水系统的设计提供了依据