Experiments and Numerical Simulation of Small-scale Slapper Driven by Electrical Explosion

Based on the low inductance technology and parallel-plate transmission principle,an experimental apparatus of small-scale slapper initiating primary high explosives driven by electrical explosion is designed and established.The problem of instantaneously and continuously measuring the velocity of the small-scale slapper is successfully solved by using the technique of laser interference.Compared with the results published on the literatures at home and abroad,data of the experimental and the numerical simulation shown in this paper are more proper to reflect the physical process of electrical explosion driving slapper.One-dimensional numerical simulation of electrical explosion driving slapper is done using the hydrodynamic code.The experimental results are consistent with the computed ones by introducing a power correction factor.In the end,the introduced power correction factor is discussed.

Power system transient stability simulation based on module bi-directional iteration

A new simultaneous solution method using module bi-directional iteration is proposed for power system transient stability simulation. In this method, power network is partitioned into a tree hierarchy; computation modules are established for decomposed power networks and various power system components respectively. Through representing every computation module by a computation node, a computation tree is constructed by connecting the nodes together according to their electrical relations in power systems. A tree-traversing procedure called forward reduction and backward evaluation is performed to calculate correction factors of the variables in Newton iterations. This high-efficiency simulation method is feasible to be applied in parallel computation for large interconnected systems. Simulation tests are conducted on the New England 10-generator test power system and the North China-Northeast interconnected system, and the results are compared with those of the commercial software BPA to validate the effectiveness and correctness of this method.

Power system transient stability simulation under uncertainty based on Taylor model arithmetic

The Taylor model arithmetic is introduced to deal with uncertainty.The uncertainty of model parameters is described by Taylor models and each variable in functions is replaced with the Taylor model(TM).Thus,time domain simulation under uncertainty is transformed to the integration of TM-based differential equations.In this paper,the Taylor series method is employed to compute differential equations;moreover,power system time domain simulation under uncertainty based on Taylor model method is presented.This method allows a rigorous estimation of the influence of either form of uncertainty and only needs one simulation.It is computationally fast compared with the Monte Carlo method,which is another technique for uncertainty analysis.The proposed method has been tested on the 39-bus New England system.The test results illustrate the effectiveness and practical value of the approach by comparing with the results of Monte Carlo simulation and traditional time domain simulation.

Power World Simulator软件的电力系统暂态稳定性仿真

将可视化软件Power World Simulator应用于电力系统暂态稳定性仿真,介绍了仿真的步骤和发电机模型库,建立IEEE-3机9节点系统,先求得系统的潮流分布,然后选择发电机、励磁系统和稳定器的类型,设置三相短路故障,完成暂态稳定性仿真。通过分析和对比发电机6阶、5阶实用模型和经典2阶数学模型时的仿真结果,验证了暂态稳定性仿真结果的有效性。

Smart Grid Wide-Area Transmission System Visualization

The installation of vast quantities of additional new sensing and communication equipment, in conjunction with building the computing infrastructure to store and manage data gathered by this equipment, has been the fi rst step in the creation of what is generically referred to as the "smart grid" for the electric transmission system. With this enormous capital investment in equipment having been made, attention is now focused on developing methods to analyze and visualize this large data set. The most direct use of this large set of new data will be in data visualization. This paper presents a survey of some visualization techniques that have been deployed by the electric power industry for visualizing data over the past several years. These techniques include pie charts, animation, contouring, time-varying graphs, geographic-based displays, image blending, and data aggregation techniques. The paper then emphasizes a newer concept of using word-sized graphics called sparklines as an extremely eff ective method of showing large amounts of timevarying data.

Forming condition of transient saturated zone and its distribution in residual slope under rainfall conditions

Rainfall, as one of the most significant factors triggering the residual soil slope failure, leads to not only the reduction of soil shear strength, but also the increase of soil weight and the decrease of matric suction as well. All these modifications in soil properties have important influence on the slope stability. The water infiltration and redistribution inside the slope are the preconditions of the slope stability under rainfall conditions. Based on the numerical simulation via finite element method, the water infiltration process under rainfall conditions was studied in the present work. The emphases are the formation, distribution and dissipation of transient saturated zone. As for the calculation parameters, the SWCC and the saturated permeability have been determined by pressure plate test and variable head test respectively. The entire process(formation, development, dissipation) of the transient saturated zone was studied in detail. The variations of volumetric water content, matric suction and hydraulic gradient inside the slope, and the eventually raise of groundwater table were characterized and discussed, too. The results show that the major cause of the formation of transient saturated zone is ascribed to the fact that the exudation velocity of rainwater on the wetting front is less than the infiltration velocity of rainfall; as a result, the water content of the soil increases. On the other hand, the formation and extension of transient saturated zone have a close relationship with rainfall intensity and duration. The results can help the geotechnical engineers for the deeper understanding of the failure of residual slope under rainfall condition. It is also suggested that the proper drainage system in the slope may be the cost-effective slope failure mitigation method.

Determination of Effective Load Shedding Schemes in Electric Power Plants

The ability of power system to survive the transition from preloading state to the gradual increase in load and thereafter reach an acceptable operational condition is an indication of transient stability of the system. The study analyzed load shedding scheme through the use of empirical measurement tools and load-flow simulation techniques. It was geared towards determining effective load shedding strategies to reduce unnecessary overload in order to achieve dynamic stability of the electric power network in the Export Free Trade Zone, Calabar, Nigeria. From the tests and the measurements taken, it was observed that the real and reactive powers from the generator and the mechanical power from the turbine engine were stable when the load shedding controller was switched on, as compared to when it was off. The engine speed, the bus-bar frequency and the output voltage of the generator stabilized within a shorter time (about 8 seconds) when the controller was switched on than when it was on the off condition. Also, there were noticeable fluctuations in the speed of the remaining two generators. It became stable at about 12 seconds after the loss. The variations were 0.3 per cent of the nominal speed value. The excitation voltage fluctuated from 1.2 (pu) to 4.5 (pu) when the bus voltage dipped as a result of additional load. It then came down and stabilized at 1.8 (pu) after few swings. This confirmed that the stability of power system is much enhanced when load shedding controllers are effectively configured on the network.

风电不确定性输入下电力系统仿真的区间仿射算法

大规模的风电机组并网改变了以同步发电机为主的传统电力系统的暂态特性,此外风电出力的随机性会影响电力系统的暂态稳定性。为此,文中提出了基于仿射算术的电力系统不确定性时域仿真算法,以考虑风电出力的波动性。在双馈风电机组机电暂态模型的基础上,扩展电力系统机电暂态模型,建立考虑双馈风电机组输入功率波动下的电力系统机电暂态仿射模型,通过隐式梯形积分法将仿射模型转化为的仿射雅克比矩阵方程迭代求解。仿真结果表明,文中所提出的仿射方法在不假设输入不确定量概率分布的情况下,能够较蒙特卡洛仿真更快地获得电力系统暂态响应的区间边界。

电力管廊通风规律及结构布局优化研究

为改善电力管廊的通风效果,依托北京新机场高速公路综合管廊工程,采用数值分析与现场试验的方法,对电力舱通风规律进行系统研究。在得到初步规律的基础上,通过改变通风方式、通风口位置和电缆布局,对比研究机械进风自然排风和自然进风机械排风、通风口设在管廊顶部和两侧、10 k V和110 k V电缆交换位置3类6种工况下的通风效果。结果表明:1)现有正常通风条件下,从进风口到排风口,进风口处气流组织混乱;同时,由于在进风口处气流2次改变运动方向导致能量损失很大,致使可用于驱动管廊内空气的能量减小,通风效果下降,造成能源浪费。2)将通风口(风机)布置在电力舱两侧时,因初始风速与通风方向一致,避免了能量损失,有效提高了通风效果。研究显示,管廊中间断面的平均风速提高了0.31 m/s,变幅达39.6%;温度降低了1.6℃,变幅达6.1%;压力损失降低了13.7 Pa,变幅达30.4%,极大地改善了电力舱通风效果。3)在通风口(风机)位于顶部的条件下,对电缆布局优化后,10 k V电缆表面温度降低3.21℃,110 k V电缆表面温度升高1.68℃,纵断面平均温度下降0.365℃,电缆布局调整有利于降低舱内温度,减少压力损失。

利用网络等值进行图降维的图注意力暂态功角稳定评估模型

省级以上实际大电网节点众多,用于电网暂态稳定评估的深度学习模型输入特征空间面临维数灾,训练成本高且泛化能力难以保证,成为该类方法难以应用于实际大系统的一个瓶颈。针对这一问题,提出了一种面向稳控校核、利用网络等值进行图降维的图注意力深度学习暂态功角稳定评估模型。首先,建立全网发电机图,基于转子惯量等决定暂态功角稳定的关键参数构建其节点相似度,并利用节点相似度改进发电机图的边权重;作为一种领域知识嵌入方式,借鉴电网动态等值思路,对待研究稳控系统所涉及区域以外的网络部分,基于发电机图和分层聚类算法进行分区,将所形成分区对应成等效节点形成降维发电机图,并建立原图到降维图节点、边权重参数的映射,实现对原输入空间的降维。最后,以降维图作为输入建立图注意力深度学习模型,实现对复杂网络的暂态功角稳定评估。在南方电网某实际稳控系统算例上进行对比分析,验证了模型的有效性及准确性。

基于时空特征融合的电力系统暂态稳定评估

为提高暂态评估模型对电气动态特征的提取能力,以及面临系统拓扑结构发生变化时的泛化能力,本文提出一种具有时空双通道并行结构的在线评估模型。首先,该模型基于门控循环单元(GRU)捕捉暂态时序数据的动态信息,基于图注意力网络(GAT)构建电力系统拓扑结构与暂态稳定状态的非线性拟合关系,并通过注意力机制融合两通道的时空特征,从而得到更可靠的评估结果。其次,将该模型与迁移学习技术相结合,当原系统拓扑结构发生变化后,更新模型的网络参数,实现模型的在线更新。最后,采用IEEE 39节点系统和IEEE 300节点系统进行仿真与验证,模型评估准确率分别达到98.62%和98.51%,表明所提方法能够实现高效的暂态稳定评估,且有较强的鲁棒性。

复杂地形瞬变电磁三维正演模拟与地形效应分析

目前,地面瞬变电磁法凭借其优势已被广泛用于煤矿水文地质勘查中,然而,在野外实际勘探中,复杂地形环境常导致发射源几何形状的改变与信号接收偏差,降低了勘探精度。为此,采用理论分析、数值模拟和实际地形数据分析相结合的方式,系统研究了复杂地形条件下电性源与磁性源瞬变电磁场的响应特征。首先,基于二阶后退欧拉离散的矢量有限元正演模拟技术,详细探讨了山峰和山谷地形位于接收点和发射源位置时,对两种源系统的影响规律。结果表明:电性源系统会出现响应变号现象,源导线位置高于周围地形时响应增强,反之则被削弱;而磁性源无变号现象,但响应变化规律与电性源类似。其次,利用实测地形数据,采用四面体网格建立与实际地形高度吻合的三维正演模型。模拟结果显示:早期响应曲线能够清晰反映地形细节,曲线形态与地形特征一致;而晚期响应则逐渐趋于平缓,体现了深部背景的影响。研究成果可为复杂地形条件下瞬变电磁法的勘探装置布设、数据采集、处理和解释提供理论指导,对提高煤矿水文地质勘探精度具有重要意义。

基于PEF-PinSVM的含可再生能源并网电力系统电压暂态稳定裕度评估

为精准掌握含可再生能源并网电力系统电压暂态稳定性,提出一种改进弹球损失支持向量机的评估方法。首先,结合系统特征与投影能量函数指标相关理论建立电力系统暂态稳定裕度的原始特征集,随后借助最大相关最小冗余特征选择法,筛选出衡量并网电力系统电压暂态稳定裕度的特征子集,以表征可再生能源并网对电力系统电压暂态稳定裕度的影响;其次,采用分位数方法将系统划分为稳定类与不稳定类,并将电压暂态稳定裕度分类问题转换为在PEF-PinSVM中寻找最优分位数距离问题,减小可再生能源并网波动性与不确定性对系统电压暂态稳定裕度评估的影响;最后,以IEEE-39节点系统进行算例仿真,发现含可再生能源并网电力系统电压暂态稳定裕度评估准确率会伴随可再生能源渗透率的增加而提升。

构网型、跟网型非同步机电源并网系统暂态同步稳定性分析

研究构网型、跟网型非同步机电源并网系统的暂态同步稳定性,并在实际电网场景下进行仿真验证。首先,根据构网型、跟网型非同步机电源的控制策略,分析影响其暂态同步稳定性的关键因素。随后,在PSCAD/EMTDC中搭建实际电网场景500 kV等值交流系统的时域仿真模型。基于此模型,研究非同步机电源接入实际电网系统的暂态失稳故障表现特征,并验证暂态同步稳定性影响因素的正确性。

Analysis and Optimization of Transient Mode Switching Behavior for Power Split Hybrid Electric Vehicle with Clutch Collaboration

The power split hybrid electric vehicle(HEV)adopts a power coupling configuration featuring dual planetary gearsets and multiple clutches,enabling diverse operational modes through clutch engagement and disengagement.The multi-clutch configuration usually involves the collaboration of two clutches during the transient mode switching process,thereby substantially elevating control complexity.This study focuses on power split HEVs that integrate multi-clutch mechanisms and investigates how different clutch collaboration manners impact the characteristics of transient mode switching.The powertrain model for the power-split HEV is established utilizing matrix-based methodologies.Through the formulation of clutch torque curves and clutch collaboration models,this research systematically explores the effects of clutch engagement timing and the duration of clutch slipping state on transient mode switching behaviors.Building upon this analysis,an optimization problem for control parameters pertaining to the two collaborative clutches is formulated.The simulated annealing algorithm is employed to optimize these control parameters.Simulation results demonstrate that the clutch collaboration manners have a great influence on the transient mode switching performance.Compared with the pre-calibrated benchmark and the optimal solution derived by the genetic algorithm,the maximal longitudinal jerk and clutch slipping work during the transient mode switching process is reduced obviously with the optimal control parameters derived by the simulated annealing algorithm.The study provides valuable insights for the dynamic coordinated control of the power-split HEVs featuring complex clutch collaboration mechanisms.

基于格点气象数据电力系统暂态稳定分析

为确保电力系统在不同气象条件下能够保持稳定运行,提出了一种基于格点气象数据的电力系统暂态稳定分析方法。首先,基于数值模式预报数据获取线路输电走廊的格点数据。其次,基于输电线路热平衡方程及潮流方程,并利用输电走廊气象数据计算线路参数。最后,利用等面积定则计算电力系统暂态稳定裕度,并定义多项指标对算法进行评估。仿真结果表明,气象因素对系统暂态稳定有显著影响,不同天气状况和常规条件计算出来的暂态稳定裕度偏差在10%以内,电网实际运行过程中可依据不同天气状况及时调整电网运行控制策略来保证系统稳定性。

基于复合探测的空区群精细化建模与稳定性分析

根据矿山采空区赋存特征,采用三维激光扫描和瞬变电磁法分别对明、盲采空区进行探测,获得了空区群的精细化三维模型,在此基础上建立三维数值计算模型开展采空区稳定性数值模拟,分析了6#剖面内采空区开挖后最大主应力、最小主应力、塑性区、应力强度比分布情况以及各监测点位移随计算时步变化规律。结果表明:6#剖面内岩体最大主应力为-0.25~-3.9 MPa,最小主应力为0.29~-0.50 MPa,采空区与巷道间矿柱内应力强度比≥1.64,巷道整体稳定性较好,采空区稳定性相对较差。研究方法与成果为同类条件下隐蔽采空区探测和治理提供了有益借鉴。

永富直流回送云南电网方式安全稳定分析

永富直流“十三五”期间主要以送电广西电网为主,随着滇东南地区负荷的快速增长,永富直流需回送云南电网,满足新增负荷的用电需求,减轻云南电网500 kV南北交流断面和滇东南500 kV交流断面的输送潮流。本文对现状电网永富直流回送云南电网以及500 kV柳井输变电工程投产后永富直流回送云南电网的系统稳定性进行了仿真分析。仿真结果显示,现状电网不能完全满足永富直流回送云南电网的运行要求,500 kV柳井输变电工程投产后永富直流具备回送云南电网的条件。

单相自适应重合闸相位判据的研究

自适应自动重合闸技术具有诸多传统重合闸技术所不具有的优势。提出了一种新型区分输电线路单相瞬时性故障与永久性故障的方法。当瞬时性故障发生时 ,短路点电弧熄灭后 ,在恢复电压阶段 ,断开相电压的大小及其相位都与永久性故障情况有本质不同。在详细分析断开相电压工频分量组成部分的基础上 ,利用它们的相位特性 ,提出了单相自适应重合闸的相位判据 ,并针对输电线路的实际参数、运行方式以及故障条件对判据的影响做了详尽分析 ,结果表明 ,相位判据可以准确判定故障性质。该判据方法简单、可靠 ,而且仅利用单端电气量 ,易于实现。

考虑暂态安全性的低频低压减载量的全局优化

指出了低频和低压减载装置的整定不仅要满足静态和中长期动态对频率和电压的安全性要求 ,而且要满足暂态过程中的频率和电压安全约束。通过详细模型的时域仿真 ,在各种运行方式及故障集下寻找使系统暂态安全且总体控制代价最小的减载策略。给出了其减载量优化问题的数学描述 ,以减载代价最小为目标函数 ,把低频和低压减载控制作为多级控制序列。根据暂态频率和电压安全裕度指标计算减载的性价比 ,把性价比最大的决策作为下一级的初始条件 。