Comparison the Performances of Three Earthing Systems for Micro-Grid Protection during the Grid Connected Mode

This paper presents, tests and compares three earthing systems (TT, TN and IT) for Micro-Grid (MG) protection against various fault types during the connected mode. The main contribution of this work is including the models of all the micro sources which interfaced to the MG by power electronic inverters. Inverters in turns are provided with current limiters and this also included in the inverter models to exactly simulate the real situation in the MG during fault times. Results proved that the most suitable earthing system for MG protection during the connecting mode is the TN earthing system. That system leads to a suitable amount of fault current sufficient to activate over current protection relays. With using TN system, Touch voltages at the faulted bus and all other consumer’s buses are less than the safety limited value if current limiter is included with the transformer of the main grid which connects MG. For the two others earthing systems (TT and IT), fault current is small and nearly equal to the over load current which make over current protection relay can not differentiate between fault current and overload current. All models of micro sources, earthing systems, inverters, main grid and control schemes are built using Matlab?/Simulink? environment.

Modes for Agricultural Land Protection in China

The main problem of agricultural land protection in China is the single farmland protection mode insuring arable land area only by issuing indicators,which brings great pressure to farmland's production and service function. Through establishing the corresponding relationship between food structure and some land use types,this paper points out that there is asymmetry between farmland area and per capita food consumption structure in China in recent years. Based on the above study,the paper proposes four types for agricultural land production, namely subsistence,fairly well-off,ecological and discrete type. Finally,it concludes that establishing rational type for agricultural land protection and implementing diverse farmland protection modes is the trend of farmland protection in China in the future.

Landscape Protection Mode of Traditional Villages in Ningbo

The protection of traditional village landscape is of great significance for inheriting traditional culture and keeping nostalgia.Taking the traditional villages in Ningbo as the research object,the mode of landscape protection of traditional villages based on the perspective of regional landscape was discussed.This study not only paid attention to the protection of material landscape,but also emphasized the protection of cultural belief and custom landscape,and transformed the intangible cultural belief and custom heritage into material landscape and it not only paid attention to the landscape protection with clear space mechanism of the clan courtyard,but also innovated the landscape space protection with relatively fuzzy space mechanism of the clan courtyard,and adopted different protection methods according to the clarity degree of the courtyard mechanism.In view of the village market space landscape,not only the single dependent architectural landscape protection was considered,but also the linear space landscape protection was emphasized.The idea and method of protection put forward show the historical existence of the value of ancient villages and better reflect the contemporary significance of "remembering nostalgia".

K-Modes聚类数据收集和发布过程中的混洗差分隐私保护方法

针对目前聚类数据收集与发布安全性不足的问题,为保护聚类数据中的用户隐私并提高数据质量,基于混洗差分隐私模型,提出一种去可信第三方的K-Modes聚类数据收集和发布的隐私保护方法。首先,使用K-Modes聚类数据收集算法对用户数据进行采样并加噪,再通过填补取值域随机排列发布算法打乱采样数据的初始顺序,使恶意攻击者不能根据用户与数据之间的关系识别出目标用户。然后,尽可能减小噪声的干扰,利用循环迭代的方式计算出新的质心完成聚类。最后,从理论层面上分析了以上3种方法的隐私性、可行性和复杂度,并利用3个真实数据集和近年来具有权威性的同类算法KM、DPLM、LDPKM等进行准确率、熵值的对比,验证所提方法的有效性。实验结果表明,所提方法的隐私保护和发布数据质量均优于当前同类算法。

基于k-modes聚类算法的混洗差分隐私方法

首次提出一种基于k-modes聚类算法的混洗差分隐私保护方案(简称SDPk-modes).SDPk-modes根据每个数据之间的距离划分为不同的组,得到足够的细粒度优化效用,采用基于梯度随机扰动技术使计算最优概率耗时更短;在k-modes聚类过程中,通过将数据中频繁出现的特征向量作为聚类中心点,基于属性熵的距离度量方法,加快算法收敛至聚类中心的速度,解决原始算法聚类速度慢、易陷入局部最优等问题,显著提高聚类的效果.实验验证表明,本文提出的方案优于当前同类方案.

The geological heritages in Xinjiang, China： Its features and protection

The geological heritage protection and its development at home and abroad reflect the progress in the aspect from the single protection to the coordination between protection and exploitation. The geopark established by UNESCO has closely combined the protection of geological heritages with the promotion of sustainable development of local economy, which has become the best way to protect geological heritages. The geological heritages in Xinjiang, China, are characterized by their large quantity, rich variety and high grade. The complicated geologic-geomorphic environment in Xinjiang contributes to the creation of various geological heritage types and their spatial distribution, and at the same time makes them under control. The main types of the geological heritages in Xinjiang are the geologic-geomorphic landscapes and the water landscapes. The spatial distribution can be divided into five geological heritage districts： Altay, Junggar, Tianshan, Tarim and Kunlun-Altun, among which Tianshan and Kunlun-Altun are most important. Based on the first systematic investigation of the geological heritages in Xinjiang, it is confirmed that the insufficient coordination between protection and exploitation is the primary cause for the backward situation in the geological heritage protection. To solve the problem, this paper proposes 6 major protection steps--from determining the protection types, the protection forms, the protection modes, the protection grades, the protection sequences to determining the＇ protection zones, brings forward the idea of optimal-selection which integrates geoparks with geological heritage protection areas and other protection areas as protection and exploitation reserve list for 209 well as 5 corresponding modes, and makes a important geological heritages in Xinjiang.

基于K-modes聚类算法的安徽历史文化名村分类及保护发展策略

以安徽省44个省级以上历史文化名村为研究对象,分析其空间分布特征与保护管理现状,并探讨影响其类型划分的具体因素。同时,借鉴学者关于历史文化名村和传统村落分类的研究,以地理条件、产业经济、社会生活、历史文化为主要维度,构建形成安徽历史文化名村类型划分的指标体系。基于此,运用K-modes聚类算法,将安徽历史文化名村划分为生态宜居型、文旅资源型、特色民俗型、综合发展型四种类型,并总结各类历史文化名村的典型特征,进而提出相应的保护与发展策略。

Design and testing of a centralized protection scheme for micro-grids

Micro-grids comprise low voltage distribution systems with distributed energy resources(DERs) and controllable loads which can operate connected to the medium voltage grid or islanded in a controlled coordinated way. This concept aims to move from "connect and forget" philosophy towards a full integration of DERs. Micro-grids can provide numerous economic and environmental benefits for end-customers, utilities and society. However, their implementation poses great technical challenges, such as a new philosophy in design of protection systems. In this work, a micro-grid protection scheme is presented based on positive-sequence component using phasor measurement units(PMUs) and a central protection unit(CPU). The salient feature of the proposed scheme in comparison with the previous works is that it has the ability to protect both radial and looped micro-grids against different types of faults with the capability of single-phase tripping. Furthermore, since the CPU is capable of updating its pickup values(upstream and downstream equivalent positive-sequence impedances of each line) after the first change in the micro-grid configuration(such as transferring from grid-connected to islanded mode and or disconnection of a line, bus, or DER either in grid-connected mode or in islanded mode), it can protect micro-grid against subsequent faults. Finally, in order to verify the effectiveness of the suggested scheme and the CPU, several simulations have been undertaken by using DIg SILENT Power Factory and MATLAB software packages.

Current Situation and Protection Means of Traditional Chinese Garden

Traditional garden is a vital element of traditional cultural heritage in China, and it is a common concern of the public to protect, inherit and develop traditional cultural heritage. This paper, on the basis of investigating current protection of royal gardens, private gardens in southern regions of the Yangtze River, and gardens in different regions, summarized 4 fundamental modes of traditional garden protection, namely protective development mode, developmental protection mode, controlled protection mode, no-protection mode. Advantages and disadvantages of different modes were reviewed, protective development was proposed as a traditional garden protection mode adaptive to actual conditions of China.

A Protection Method of VSC-HVDC Cables Based on Generalized S-Transform

Generalized S-transform is a time-frequency analysis method which has higher resolution than S-transform. It can precisely extract the time-amplitude characteristics of different frequency components in the signal. In this paper, a novel protection method for VSC-HVDC (Voltage source converter based high voltage DC) based on Generalized S-transform is proposed. Firstly, extracting frequency component of fault current by Generalized S-transform and using mutation point of high frequency to determine the fault time. Secondly, using the zero-frequency component of fault current to eliminate disturbances. Finally, the polarity of sudden change currents in the two terminals is employed to discriminate the internal and external faults. Simulations in PSCAD/EMTDC and MATLAB show that the proposed method can distinguish faults accurately and effectively.

A Comparison Study of Input ESD Protection Schemes Utilizing NMOS, Thyristor, and Diode Devices

For three fundamental input-protection schemes suitable for high-frequency CMOS ICs, which utilize protection devices such as NMOS transistors, thyristors, and diodes, we attempt an in-depth comparison on HBM ESD robustness in terms of lattice heating inside protection devices and peak voltages developed across gate oxides in input buffers, based on DC, mixed-mode transient, and AC analyses utilizing a 2-dimensional device simulator. For this purpose, we construct an equivalent circuit model of input HBM test environments for CMOS chips equipped with input ESD protection circuits, which allows mixed-mode transient simulations for various HBM test modes. By executing mixed-mode simulations including up to six active protection devices in a circuit, we attempt a detailed analysis on the problems, which can occur in real tests. In the procedure, we suggest to a recipe to ease the bipolar trigger in the protection devices and figure out that oxide failure in internal circuits is determined by the peak voltage developed in the later stage of discharge, which corresponds to the junction breakdown voltage of the NMOS structure residing in the protection devices. We explain strength and weakness of each protection scheme as an input ESD protection circuit for high-frequency ICs, and suggest valuable guidelines relating design of the protection devices and circuits.

A Thyristor-Only Input ESD Protection Scheme for CMOS RF ICs

We propose an input protection scheme composed of thyristor devices only without using a clamp NMOS device in order to minimize the area consumed by a pad structure in CMOS RF ICs. For this purpose, we suggest low-voltage triggering thyristor protection device structures assuming usage of standard CMOS processes, and attempt an in-depth comparison study with a conventional thyristor protection scheme incorporating a clamp NMOS device. The comparison study mainly focuses on robustness against the HBM ESD in terms of peak voltages applied to gate oxides in an input buffer and lattice heating inside protection devices based on DC and mixed-mode transient analyses utilizing a 2-dimensional device simulator. We constructed an equivalent circuit for the input HBM test environment of the CMOS chip equipped with the input ESD protection devices. And by executing mixed-mode simulations including up to four protection devices and analyzing the results for five different test modes, we attempt a detailed analysis on the problems which can occur in real HBM tests. We figure out strength of the proposed thyristor-only protection scheme, and suggest guidelines relating the design of the protection devices and circuits.

On a Parasitic Bipolar Transistor Action in a Diode ESD Protection Device

In this work, we show that an excessive lattice heating problem can occur in the diode electrostatic discharge (ESD) protection device connected to a VDD bus in the popular diode input protection scheme, which is favorably used in CMOS RF ICs. To figure out the reason for the excessive lattice heating, we construct an equivalent circuit for input human-body model (HBM) test environment of a CMOS chip equipped with the diode protection circuit, and execute mixed-mode transient simulations utilizing a 2-D device simulator. We analyze the simulation results in detail to show out that a parasitic pnp bipolar transistor action relating nearby p+-substrate contacts is responsible for the excessive lattice heating in the diode protection device, which has never been focused before anywhere.

基于电流模分量特性的多端柔性直流配电网线路纵联保护

多端柔性直流配电网因在供电可靠性方面极具优势而受到广泛的关注,然而对于直流线路保护中故障的快速、可靠识别成为其急速发展所需解决的关键问题之一。因此,设计了一种利用电流模分量特性的直流线路纵联保护方法。该方法利用故障时正极电流线模分量方向来判别区内外故障,以不同故障条件下故障点正极电流零模分量平均值的差异来构造保护判据,从而判别故障类型,形成保护策略。最后,在PSCAD/EMTDC4.5上搭建了多端柔性直流配电网模型,对保护判据及关键影响要素进行了仿真分析。结果表明,该保护方法能够有选择性地快速、可靠识别区内外故障及故障类型,且具有较好的耐过渡电阻与抗噪声能力。

适用于双馈风电场送出线的纵联方向保护研究

考虑风电场接入电网时,传统方向元件在短路故障发生时易受到风电场内部电力电子器件动态特性的干扰影响,导致频率特性偏移,系统参数不稳定和弱馈性等问题,使继电保护装置不能及时或正确判断故障发生区域。针对上述问题,首先对含有风电场的故障附加网络进行分析,寻找故障发生后纵联保护安装处各测量点电气量之间的关联性,确定其故障逻辑关系。其次通过对常用的相模变换解耦方式进行分析,选择一个合理的方法代入相关性表达式,根据相关系数值完成故障区域判定。最后利用PSCAD/EMTDC搭建双馈风电场并网模型,设置各种不同的故障类型和场景,并利用Matlab进行保护算法验证,检验故障区域判断结果,验证所提保护方法的正确性与合理性,并且仿真结果表明该方法具有较高的可靠性。

“光储直柔”建筑配电系统应用研究

以某项目为例分析“光储直柔”在建筑物中的应用,并对“光储直柔”系统的应用场景、建筑直流配电系统的关注点及“光储直柔”系统关键设备进行阐述。

中国环保技术推广实践模式研究

本文以政府部门、第三方机构和环保企业三类环保技术推广实践主体为调研对象,采用资料调研、现场调研、网络调查、问卷调查及系统分析、归纳等方法,梳理了当前我国环保技术推广实践模式及其存在的问题,并提出环保技术的推广建议。

PDCA循环管理在危重患者保护性约束中的应用效果

目的 探讨PDCA循环管理在危重患者保护性约束中的应用效果。方法 选取本院2022年11月27日至2023年6月23日收治的252例急诊重症监护室患者,随机分为对照组和研究组,每组126例,对照组予以常规保护性约束护理,研究组在常规的保护性约束护理基础上采用PDCA循环管理模式下的保护性约束护理。将两组患者的约束松紧适宜率、约束肢体位置正确率、约束部位皮肤正常率、约束肢体末梢血运良好率进行对比。结果 研究组的约束松紧适宜率、约束肢体位置正确率、约束部位皮肤正常率、约束肢体末梢血运良好率均高于对照组,差异均有统计学意义(P<0.05)。结论 在危重患者保护性约束护理中,PDCA循环管理模式能够有效提高约束松紧适宜率、约束肢体位置正确率、约束部位皮肤正常率、约束肢体末梢血运良好率。

矿用隔爆高压配电装置保护及控制电源设计

针对目前井下矿用隔爆高压配电装置保护及控制电源与供电系统同源存在的问题进行分析,提出了矿用独立电源供电的方式。对矿用隔爆高压配电装置保护及控制供电方式进行了分析与设计;对矿用隔爆高压配电装置用独立电源进行了设计;对矿用隔爆高压配电装置保护控制供电方式进行了研究,进一步对其进行了保护控制供电设计和电源切换装置设计。实现了保护及控制供电一用一备独立供电,保障供电系统的安全运行。目前该供电方式已经在潞安化工集团、晋能控股集团的大型矿井实现了井下应用。

权益区分理论下数据法益保护模式

大数据时代各种数据权益保护学说值得进一步反思与检讨。数据权益保护问题在我国既有规则体系内完全能够得到妥善解决。因数据的非排他性与权利的排他效力间的根本冲突,数据权益难以被纳入绝对权或相对权中进行保护,而各类新型数据权利混淆了权利在民法体系中的定位,忽视了体系功能,甚至阻遏数据的共享与流通。从体系逻辑、制度调适成本与数据治理全球发展方向来看,数据权益应当被纳入法益保护模式中。数据法益保护应以事实控制状态为基础,将数据权益直接归属于事实控制人,保护范围以各个主体享有的事实利益范围为限。数据产权分置政策应经法律解释还原为数据法益归属确认的基础前提与数据主体行为规范的设计方向。