风机并网与解裂对电力系统的影响及应对策略

并网型风力发电机组由于受其固有功率特性的影响,启停时会对电力系统产生较大的冲击电流,引起系统电压跌落,影响系统功率平衡。以异步风力发电机组为例,在常规研究的基础上,提出在风力发电机组出口端加延迟控制器,构建风力发电机组并网模型,分析风电机组并网与解列对电力系统的影响,合理安排各台机组的最佳并网时间,避免多台风力发电机组同时并网,减小风电启动对电力系统安全运行的影响。选取中型规模风电场为例,构建内部接线图及并网模型,并仿真验证。该研究成果对风电并网运行具有一定的工程借鉴意义。     

A two-process view of Facebook use and relatedness need-satisfaction: Disconnection drives use, and connection rewards it.

Does using Facebook help people to meet their relatedness needs? Study 1 shows that more frequent Facebook usage paradoxically correlates with more relatedness satisfaction (connection) and more relatedness dissatisfaction (disconnection). Study 2 supports a 2-process explanation of this finding, showing that disconnection motivates greater usage as a coping strategy, whereas connection results from greater usage. Study 3 examines the effects of depriving participants of Facebook use for 48 hr. Further supporting the 2-process view, connection decreased, but disconnection was unaffected during the deprivation period; however, those who became more disconnected during the deprivation period engaged in more Facebook use during a 2nd, unconstrained 48-hr period, whereas changes in connection did not predict later use. In Study 4, participants set a Facebook reduction goal; initial disconnection interfered with and predicted worse performance in this goal. Implications for theories of psychological needs, behavioral motives, and adaptive coping are considered. (PsycINFO Database Record (c) 2011 APA, all rights reserved)     

Disconnection control of wind power generators for the purpose of reducing frequency fluctuation

This paper proposes a new approach for disconnection control of wind power generators to reduce the frequency fluctuation caused by wind power. The approach is based on the correlation between frequency and total output of wind power generators and the turbulence degrees of individual wind power generators. At a control center, frequency and all the outputs of wind power generators are monitored, and the correlation and the turbulence degrees are computed on‐line. If the large variation of frequency is detected, then whether the variation comes from the wind power generators or loads is checked by using the correlation. When the wind power generators cause the frequency variation, the wind power generator with maximum turbulence degree is searched and disconnected from the power systems. This search and disconnection process is repeated until the correlation reaches the level where the frequency variation observed is not caused by the wind power generators. The effectiveness of the proposed approach was confirmed with the simulation studies of a two‐area interconnected power system including many wind power generators. The results show that the correlation and the turbulence degree are useful for the reduction of frequency fluctuation so as not to disconnect too many wind power generators. © 2010 Wiley Periodicals, Inc. Electr Eng Jpn, 171(1): 10–18, 2010; Published online in Wiley InterScience ( www.interscience.wiley.com ). DOI 10.1002/eej.20911     

110kV输电线路单相断线故障分析

介绍了一起110kV输电线路B相断线故障及引起的其他故障,通过与AC两相接地故障的对比,分析了单相断线和AC两相接地故障现象的异同,为专业工作人员介绍了一种便捷的工作思路。     

MAWA:基于移动Agent的一种高效可靠无线Web访问机制

在无线移动环境中进行Web访问承受着更多的技术挑战,移动设备在此环境中进行无线Web访问时需有一种高效且可靠的机制给予支持,以克服由于移动设备自身硬件能力的有限,移动设备自身的物理移动及无线网络的不可靠性而带来的困难.提出一种基于移动Agent的无线Web访问机制MAWA. 该机制利用移动Agent作为移动设备与Web服务器之间交互的中介,有效避免移动设备不必要的Web页面更新提交操作,从而节省了其无线网络连接开销,与其他协议相比有着较高的执行效率;同时该机制还可有效支持移动设备进行无线Web访问时在基站间的切换,及运行期间发生故障后的状态恢复,从而确保了移动设备运行过程的可靠性.最后通过实验分析了MAWA机制的可靠性与高效性.     

微机故障解列装置

发微机故障解列装置的原理、特点和算法。采用８０Ｃ１９６高性能快速单片机为保护ＣＰＵ,频率测量单元运用硬件测频,测量精度高;低用解列单元设有完善可靠的防止误动作的闭锁措施;低压角列单元具有可靠的三相ＴＶ断线闭锁判据。该装置已通过各种测试和动模试验,并投入现场运行。     

基于余弦相似度的新能源场站T接型送出线路纵联保护

新能源场站T接型线路保护受新能源电源短路电流幅值受限、畸变的故障特征以及T接型线路拓扑影响,传统电流相量差动保护不能同时满足区外故障可靠性与区内故障灵敏性,存在误、拒动风险。因此,在分析T接型线路对基于余弦相似度纵联保护主判据影响的基础上,提出了基于余弦相似度特征判据的T接型线路纵联保护。综合考虑了电流互感器饱和、发展性故障与电流互感器二次侧断线的影响,研究了相应辅助判据。仿真结果表明,所提保护原理能够在新能源场站T接型线路中可靠识别区内外故障,并应对电流互感器饱和与发展性故障场景,且在常规采样频率下动作性能良好,适应不同类型新能源场站的故障特征。现场数据验证了所提新原理保护的有效性。     

开关电源对蓄电池寿命影响的探讨

随着数字通信技术的发展，对各通信局站供电的可靠性、电源维护方式、技术维护水平提出了更高的要求。开关电源及蓄电池为各局站的可靠运行提供了动力保障，同时也是日常维护的重点。文中先对高频开关电源特性加以阐述，并着重讨论高频开关电源影响蓄电池寿命的因素以及两者之间的关系，最后指出高频开关电源对延长蓄电池寿命的重要性。     

鄂坪电站^#2机PT断线保护动作致机组事故停机的分析

针对鄂坪电站首台机组投产不久出现“PT断线”故障引起失磁保护误动致机组事故停机高速加闸现象,分析了事故的成因,提出了防范措施,消除了机组安全运行隐患,同时也为后续机组的安装提供了有益的借鉴.     

基于相电流特征的配电网单相断线区段定位新方法

由于雷击等原因,配电网单相断线故障时有发生。为了避免断线故障导致电机损坏等事故,文章基于相电流特征提出了一种断线故障区段定位新方法。首先利用序网络分析了配电网发生断线故障后的相电压、电流特征,然后根据相电压特征构造了启动判据和故障选相判据,根据相电流相关系数构造了区段定位识别判据。所提出的方法具有灵敏度高、通信量小的优点,PSCAD仿真验证了该方法的有效性。