Through a large number of digital simulations by atp , this paper analyzes the impact of the ct ' s saturation of the distance protection in detail . then a new scheme anti ct ' s saturation for distance protection has been put forward . at last , some compensation methords have also been introduced , and a compensation algorithm of ann ( artifical neural network ) based on matlab has been discussed as an emphasis 本文通过atp进行大量的数字仿真实验，详细分析了电流互感器饱和对距离保护的影响，并且提出了一种抗ta饱和的距离保护方案；介绍了电流互感器饱和的补偿方法，其中重点分析了基于matlab的人工神经网络的补偿方法。
The transient solution obtained from the multi - loop mathematical model are in agreement with experiment results approximately under the conditions that saturation is not severe . though the errors of currents in some non - fault branch seem a little large , the fundamental components of the simulation current are accurate 结果表明，多回路数学模型在电机饱和不严重的情况下，暂态仿真结果与实验结果大致吻合，虽然有时非故障分支电流与实验结果的差异比较大，但基波分量还比较准确，基本可以满足保护方案的灵敏度校验等工程需要。
To resolve the situation that the sensitivity of present ground fault protection schemes is low for the large - sized hydro - generators , a kind of protection scheme based on the fault component of third - harmonic voltage and two kinds of protection scheme based on the fault component of zero - sequence voltage at the terminals and neutral are developed , and they can obtain higher sensitivity and reliability and provide 100 % protection for the stator windings . the influence of noise on the stator ground fault protection based on the local modulus maximum of wavelet transform is analyzed 针对目前大型水轮发电机定子绕组单相接地保护灵敏度偏低的问题，通过分析单相接地故障后机端和中性点零序电压的变化特点，提出了一种基于机端和中性点三次谐波电压故障分量和两种基于机端和中性点零序电压故障分量的高灵敏度、高可靠性保护方案，并实现定子绕组的100 %保护。
This paper is based on the pingpong bridge field ground protection , it presents one point to ground protection scheme which include the self - checking method of switches . the two point to ground protection scheme presents self - adapting fault location warp criterion after evaluating the effect on the calculation of fault location made by the change of transient resistance in the process of bridge switch . in order to make up the shortcoming of location warp criterion , this paper presents a comprehensive scheme into which integrate the second harmonic criterion 本文针对乒乓式保护，结合开关自检方法提出了完整的一点接地保护方案：在两点接地保护方案中估算了开关切换过程中过渡电阻变化对接地点位置计算的影响，提出了故障位置偏差式两点接地的自适应判据，为了弥补该判据的缺陷，提出了结合二次谐波辅助判据的综合方案。
In order to analyze the characteristics of stator ground fault and develop its protection schemes , a mathematical model for large - sized hydro - generators is established based on the multi - loop theory of ac machines and considering the capacitance to ground and actual construction of the stator windings 为了详细分析大型水轮发电机定子绕组单相接地故障特点，校验和开发相应的保护方案，本文建立了以交流电机多回路分析方法为基础、考虑定子绕组对地电容、采用实际绕组结构的发电机定子绕组单相接地故障仿真模型。
Because the network operates in a large - scale , with many different layers and extensive contents , the security and management are critical subjects . guided by the information security theories and based on the analysis of security risks and requirement , the overall security framework of the information system of press and publication area ( ppa ) is designed in this thesis , including the design of wan security , lan security , boundary security and implementation means . the choice principle and configuration scheme of security equipments are also given 本安全框架研究和安全体系设计依照新闻出版行业信息化总体规划，遵照我国相关法律法规，参照有关信息安全标准体系，结合行业网络应用系统的实际需求，在风险分析及安全需求分析的基础上，对行业网络系统的安全体系了全面的设计，设计内容包括广域网、局域网的安全系统结构和技术实施路线、网络边界安全保护方案及实施办法、安全产品的选型及配置等。
By combination use of the symmetric cryptosystem and threshold cryptosystem , this paper proposes a practical scheme of secure distributed storage , which aims to guarantee that the process of storing the information is correct even when some of the servers fail , while considering the privacy requirement of the system , and don ' t storing the encryption / decryption key in a single device , either held by the user or by the servers 摘要结合对称加密技术和门限加密技术，提出了一种适用于分布式数据存储需要的有效的系统机密性保护方案，其中对称加密技术用于对所存储的文件进行加密，分布式门限加密技术则对对称加密方案中所用的密钥进行保护，可在不带来密钥存储问题情况下满足恶意环境中分布式数据存储系统的机密性要求。
