Designing a Protection Scheme in Micro-Grid Systems with DG Using Central Protection Unite and Multiple Setting Group Protection Relays

Distributed generators now is widely used in electrical power networks, in some cases it works seasonally, and some types works at special weather conditions like photo voltaic systems and wind energy, and due to this continuous changes in generation condition, the fault current level in network will be affected, this changes in fault current level will affect in the coordination between protection relays and to keep the coordination at right way, an adaptive protection system is required that can adaptive its setting according to generation changes, the fault current level in each case is evaluated using ETAP software, and the required relay setting in each case is also evaluated using Grey Wolf Optimizer (GWO) algorithm, and to select suitable setting which required in each condition, to select the active setting group of protection relay according to generation capacity, central protection unite can be used, and to improve protection stability and minimizing relays tripping time, a proposed method for selecting suitable backup relay is used, which leads to decrease relays tripping time and increase system stability, output settings for relays in all cases achieved our constrains.

Directional Overcurrent Relays Coordination Restoration by Reducing Minimum Fault Current Limiter Impedance

FCL （fault current limiter） is used to solve relays miscoordination problem arises from DG （distributed generation） installation. In most published researches, different optimization methods are developed to obtain optimal relay settings to achieve coordination in case of not installing DG, then depending on the achieved optimal obtained relay settings, FCL impedance is deduced to ensure relays coordination restoration in case of installing DG. Based on original optimal relay settings, obtained FCL impedance is not the minimum one required to achieve relay coordination. The contribution of this paper is the generation of multi sets of original relay settings that increase the possibility of finding FCL impedance of minimum value which is lower than the calculated value based on original optimal relay settings. The proposed method achieves better economic target by reducing FCL impedance. The proposed approach is implemented and tested on IEEE-39 bus test system.

Coordination of dual setting overcurrent relays in microgrid with optimally determined relay characteristics for dual operating modes

Fault current magnitude in a microgrid depends upon its mode of operation,namely,grid-connected mode or islanded mode.Depending on the type of fault in a given mode,separate protection schemes are generally employed.With the change in microgrid operating mode,the protection scheme needs to be modified which is uneconomical and time inefficient.In this paper,a novel optimal protection coordination scheme is proposed,one which enables a common optimal relay setting which is valid in both operating modes of the microgrid.In this con-text,a common optimal protection scheme is introduced for dual setting directional overcurrent relays(DOCRs)using a combination of various standard relay characteristics.Along with the two variables,i.e.,time multiplier setting(TMS)and plug setting(PS)for conventional directional overcurrent relay,dual setting DOCRs are augmented with a third variable of relay characteristics identifier(RCI),which is responsible for selecting optimal relay characteristics from the standard relay characteristics according to the IEC-60255 standard.The relay coordination problem is formulated as a mixed-integer nonlinear programming(MINLP)problem,and the settings of relays are optimally determined using the genetic algorithm(GA)and the grey wolf optimization(GWO)algorithm.To validate the superiority of the pro-posed protection scheme,the distribution parts of the IEEE-14 and IEEE-30 bus benchmark systems are considered.

Optimal Coordination of Directional Overcurrent Relays in Meshed Active Distribution Network Using Imperialistic Competition Algorithm

The optimal setting of directional overcurrent relays(DOCRs)ensures the fault detection and clearing in the minimum possible operation time.Directional protective relaying is carried out to coordinate relay settings in a meshed network in the presence of distributed generation.The main goal of DOCR coordination is to find the optimal time dial setting(TDS)and pickup multiplier setting(PMS)to reach the minimum total operation time of all primary relays in the presence of coordination constraints.Due to the complexity of mixed integer non-linear programming(MINLP)problem,imperialistic competition algorithm(ICA)as a powerful evolutionary algorithm is used to solve the coordination problem of DOCRs.The proposed DOCR coordination formulation is implemented in three different test cases.The results are compared with the standard branch-and-bound algorithm and other meta-heuristic optimization algorithms,which demonstrates the effectiveness of the proposed algorithm.

A New Proposal of Inverse-Time Characteristics for Overcurrent Relay Based on Microcomputer

The conventional time function of electromechanical relays is hard to coordinate with other relays. In order to promote the application of inverse-time overcurrent relays, a new time function for microprocessor-type relay is proposed. The setting of the trip time for this relay is performed by determining the shortest trip time and the longest trip time, respectively. The results of analysis show that with the new time function, the inverse-time overcurrent relay is easy to coordinate with other relays and has a comparatively shorter trip time, and that the fault happens in the protective zone.

基于三端柔性直流的光热储能站与新能源场站功率协同控制策略

新能源基地大多经传统交流方式接入高压交流或直流外送通道,为解决大规模新能源经交流接入方式下并网容量小、损耗大,以及功率波动对电网稳定性影响等问题,构建了一个基于柔性直流输电并网的风电和光伏、光热储能及电网三端柔性直流系统。基于直流电压-有功功率特性,提出一种适用于该系统的站间协调控制策略,根据柔性直流输电系统的直流电压波动情况,调整光热储能机组的出力,以平抑风、光功率波动,降低其对电网的影响。针对光热储能侧换流站,采用直流电压裕度下垂混合控制策略,通过控制器参数配置,抑制控制模式切换过程中的暂态过电压,提高系统响应速度。最后,在PSCAD/EMTDC中搭建三端柔性直流系统仿真模型,验证所提控制策略的有效性。

Summary of Useful Concepts About the Coordination of Directional Overcurrent Protections

This paper summarizes some useful concepts about the coordination of directional overcurrent protections.The following key topics are described:the analysis of systems in a ring configuration and only one source of short-circuit currents;the impossibility of obtaining selectivity for all the possible system configurations with multiple sources;the need for inverse functions in order to obtain selectivity in systems with multiple sources;the coordination with protections for radial loads;the coordination between instantaneous and delayed functions;the considerations to select the pickup values;the influence of contributions from motors to short circuit currents;the transient configurations due to sequential trips at both line ends;the influence of dynamic behavior of overcurrent functions;the influence of stability constraints;other specific considerations for ground functions;some specific considerations for systems with distributed generation.A summary of these points and their effect on the coordination of directional overcurrent protections is not available in the current literature.This novel description should facilitate the inclusion of these key points in research and coordination studies related to these protective functions.

基于GA的环网方向保护配合最小断点集的计算

利用复杂环网方向保护最优整定配合中最小断点集 (MBPS)的启发知识 ,将MBPS的计算归结为解不等式———欠定方程组 ,进而等价为 0— 1整数二次规划问题 ,基于基因遗传优化计算原理 ,首次提出了MBPS问题的基因遗传计算方法 ,降低了问题的计算复杂性。

多环复杂电网方向保护全网最优配合的研究──第2部分 确定全网最优配合顺序

引入相关顺序组的概念，从数学上准确地描述了大规模多环复杂网络方向保护全网最优配合问题，提出了利用系统最小断点集和主／后备保护函数依赖关系形成全网最优配合顺序的新方法。

基于配合依赖关系图计算环网方向保护最优配合顺序的新方法

提出了基于保护主后备配合关系,利用保护配合依赖关系有向图节点邻接矩阵计算环网方向保护最优配合顺序的新方法。根据节点入度最大的原则逐步选择断点,根据节点出度为0的原则确定保护配合顺序,通过对节点邻接矩阵简单的行列化简运算逐步计算大规模复杂环网最小断点集和确定全网保护最优配合顺序。该方法简单直观,大大降低了问题的复杂度和计算量。

基于双向配置方向过流继电器的反时限后备保护优化整定策略

提出一种双向配置方向过流继电器,该继电器配有2套反时限特性保护,根据故障方向设定每套保护的参数。双向配置方向过流继电器采用连接在同一条母线不同线路上的保护对,有效提高了保护系统的速动性和灵敏性。双向配置方向过流继电器的整定计算被转化为一种优化问题,将继电器间的配合问题抽象为约束条件,将主保护和备用保护的动作时间之和抽象为目标函数。IEEE 30节点的仿真结果表明,与传统保护方案相比,双向配置方向过流继电器能明显提升保护系统的速动性。

环网方向保护配合最小断点集的神经计算方法

将复杂环网方向保护整定计算中最小断点集ＭＢＰＳ的计算归结为０－１整数线性规划问题，基于神经优化计算原理，综合应用模拟退火技术和惩罚函数法于ＴＨ线性规划神经网络，提出了一种新的神经优化求解方法，降低了问题的计算复杂性。软件仿真研究表明，算法能以接近概率１获得全局最优解，ＴＨ网络对初始参数的不稳健性得到了改善。

基于配合关系计算复杂环网保护最优配合顺序的新方法

基于保护主后备配合关系,引入并定义了保护配合主依赖度和后备依赖度的概念来描述保 护之间的配合依赖关系,提出了通过动态调整保护主依赖度和后备依赖度逐步计算复杂环网最小 断点集和确定全网最优配合顺序的新方法,根据保护后备依赖度最大的原则选择候选断点和主依 赖度为0的原则确定保护配合顺序,同时给出了详细的算法流程和算例分析。该方法简单直观,计 算量小,只需利用基本的配合关系,完全不需要形成全网所有有向回路,有效解决了多环复杂网络 中方向保护全网最优配合问题。

基于环网方向保护协调配合的最小断点集选取方法

为实现环网方向保护整定配合起始点的合理选择,给出一种基于保护协调配合性能的最小断点集选取方法。该方法基于继电保护整定配合的阶梯原则,定义了评价环网各级阶段式方向保护整体协调配合性能的测度指标,通过测度指标定量评价最小断点集问题各组可行解的优劣性,进而实现最小断点集问题多组可行解的合理选取;同时给出了基于图论中最长基本路径概念的测度指标计算方法。算例仿真表明,所提方法能够避免最小断点集选取不当引起的保护配合级数过多和动作时限过长问题。

反时限方向过电流保护最优协调整定的分析

反时限方向过电流保护常作为电气设备和配电网的保护,一定程度上它具有三段式电流保护的功能,但其整定相对复杂。文中阐述了利用最优化理论,在保证正确性和选择性的前提下对该保护的最优协调整定,并对其中的几个主要问题,如确定主后备保护对问题、优化模型实现等问题进行了讨论、分析和解决。

点物体主方向关系的一致性检验

一致性检验问题是主方向关系推理中非常重要的基础理论问题,提出了一种利用欧几里德空间坐标图实施一致性检验的新方法。首先对研究的问题进行了定义,阐述了方向关系的坐标图表示方法,从而使得对点物体方向关系约束集的一致性检验就转化为检测图中是否存在环的问题,通过一致性判定、环的检测、实施方法这3个环节来具体实现。其算法的时间复杂度是O(n+e),优于传统的O(n2)。

城市轨道交通双电源并列环式供电方案的过电流保护配合

对城市轨道交通双电源并列环式供电方案的过电流保护进行全面分析,包括电流方向设定、电流定值设置及延迟时间配合,并在这三方面对环式供电分区进线的过电流保护配合进行了论述。

高速公路占地边桩的测试方法与实践

本文阐述了高速公路占地边桩测设的基本原理,给出了线路中桩和边桩坐标的计算公式以及方向坐标测设法的计算公式。实践表明文中推荐的综合坐标法,用于线路测设具有明显的优越性。

对隧道控制测量洞口投点必要性的研究

论述了隧道测量控制网的建立方法,分析洞口投点的方法、投点的测量误差、投点对隧道控制网的影响,以及隧道控制网与铁路设计中线的关系。结合已贯通的多个特长隧道测量控制网实践,讨论在建立隧道施工測量控制网过程中,隧道洞口投点的必要性。得出结论:若采用交切放线法进行勘測,有必要布设洞口投点;若采用坐标法进行勘测,不宜进行洞口投点。坐标法勘測,可以先采用一点一方向将测量点投影至线路基础网平面,再将坐标转换至隧道内线路的平均高程面上,计算出隧道施工坐标系的坐标。现阶段,对于布设隧道测量控制网,不宜要求布设洞口投点。