计及DSTATCOM和并网逆变器协同的高比例分布式光伏配电网鲁棒控制策略

针对新型电力系统安全稳定运行过程中由于高比例分布式光伏接入配电网产生的电能质量问题,提出一种计及配电静止同步补偿器(distribution static compensator,DSTATCOM)和并网逆变器协同的高比例分布式光伏配电网鲁棒自适应控制策略。首先,建立DSTATCOM和并网逆变器的无功电压控制统一模型,以及计及系统出力及负荷随机性的配电网电压控制不确定系统模型;其次,采用灵敏度分析方法,考虑节点受其他分布式光伏注入功率的影响情况,并结合鲁棒H∞性能约束,设计DSTATCOM和并网逆变器的鲁棒电压控制策略;然后,计及分布式光伏的有功功率削减,构建鲁棒自适应控制策略;最后,搭建含DSTATCOM和高比例分布式光伏的IEEE 33节点系统模型进行仿真分析。结果表明,所提策略能够实现DSTATCOM和并网逆变器对配电网电压的协同控制,并具有较强的自适应能力。

Wind Power System Risk Assessment Based on Fuzzy Clustering and Copula Function Modeling

According to the characteristics of the correlation of multiple wind farm output, this paper put forwards a modeling method based on fuzzy c-means clustering and the copula function, and correlation wind farms are inserted into IEEE-RTS79 reliability system for risk assessment. By the probabilistic load flow calculated by Monte Carlo simulation method, the probability of the accident is derived, and bus voltage and branch power flow overload risk index are defined in this paper. The results show that this method can realize the modeling of the correlation of wind power output, and the risk index can identify the weakness of the system, which can provide reference for the operation and maintenance personnel.

基于ISFO-KELM的SF_(6)电气设备故障组分CO_(2)浓度反演模型

SF_(6)电气设备内部的分解组分可以通过可调谐吸收光谱技术进行检测,其中CO_(2)浓度反映了设备内部的绝缘缺陷情况。因此,通过准确测量CO_(2)浓度可以及时发现设备潜在的绝缘故障。为克服传统最小二乘法浓度反演模型稳定性较差的问题,文中基于改进的旗鱼优化算法(Improved Sailed Fish Optimizer,ISFO)与核极限学习机(Kernel Based Extreme Learning Machine,KELM)建立了ISFO-KELM气体浓度反演模型。利用多策略初始化方法、Levy随机步长、柯西变异和自适应t分布变异等技术提升了旗鱼优化算法寻优能力和跳出局部最优解能力。实验结果表明,该模型具有高精度和鲁棒性,并且在稳定性和泛化能力方面优于最小二乘法、极限学习机、反向传播(Back Propagation,BP)神经网络等传统方法,对评估SF_(6)电气设备运行状态具有重要意义。

基于COMSOL分析步进电动机故障的电流和磁场变化规律研究

步进电动机是电力系统稳定运行的关键设备之一,当步进电动机在运行过程中出现故障,将直接导致电力系统的停运,给电力企业带来经济损失,需要对步进电动机内部故障原因进行研究。通过COMSOL有限元分析及建模的方式,对步进电动机的失步故障和开路故障所引起的电场和磁场的变化展开了研究,分析了在5种不同频率下失步故障和开路故障所引起的电场和磁场的变化规律,以提高对步进电动机故障诊断的效率。

The Reliability Evaluation Method Study of Power System Communication Networks in Case of Ice Storm

This paper is divided into two cases to study the communication transmission equipment reliability in the state of the ice storm, according to the huge losses of power system communication caused by the ice storm. For the nodes or links which are not affected by the ice storm, we use the calculation with “the mean time between failures (MTBF)” and “the mean time to repair” (MTTR) to put forward the calculation methods;for the OPGW cable which influenced greater in ice storm, we use the fiber excess length and the elongation of fiber optic cable. It obtains all the paths of the network through improved adjacency matrix method, and then it uses binary decision diagram to obtain the overall reliability of the network. By testing the network nodes and links using “N-1” inspection, the key nodes and key links can be obtained. Finally, considering the importance degree of network transmission business, the reliability evaluation method of power system communication network based on the risk theory in the case of the ice storm has been put forward, and the example to verify that the method can provide the basis for the reliability assessment of the power system communication in the case of the ice storm has been given.

HFO-1234ze(E)/CO_(2)混合气体工频击穿及分解特性实验研究

近年来,由于HFO-1234ze(E)具备良好的环保特性和优良的绝缘性能,被认为有较大潜力应用于中低压设备中。目前针对该气体的试验探究相对比较少。文中首先计算了不同气压下HFO-1234ze(E)/CO_(2)混合气体的液化温度,然后利用气体绝缘性能测试平台,分别探究了气压、混合比对HFO-1234ze(E)/CO_(2)混合气体绝缘特性的影响,并讨论实际工程应用中的最优混合比和气压值,再采用气相色谱质谱联用仪(GC-MS)对分解产物进行定性分析,同时对分解产物进行了仿真计算。研究结果表明在不同均匀场的条件下,HFO-1234ze(E)/CO_(2)混合气体的绝缘性能均随着混合比的提升而提高,击穿电压呈近似线性增长;在混合比保持不变的条件下,提高气压能够显著改善HFO-1234ze(E)/CO_(2)混合气体绝缘性能;同时在0.3 MPa条件下,20%~25%体积分数的HFO-1234ze(E)不仅具有良好的绝缘水平,而且受到电场不均匀度的影响相对较小,适用于实际工程应用。HFO-1234ze(E)/CO_(2)混合气体具有良好的自恢复绝缘特性,分解的产物主要为氢氟化碳(HFC)和碳氢化合物(HC),仿真结果表明分解产物较为稳定。综合实验和仿真计算结果表明HFO-1234ze(E)/CO_(2)混合气体有潜力替代SF6气体应用中低压绝缘设备中。

C3F7CN/CO2混合气体在准均匀电场中的绝缘性能

近年来C3F7CN作为一种环保绝缘介质受到SF6替代气体领域研究者的广泛关注,目前针对其混合气体的工频击穿特性鲜有系统性研究。利用球电极模拟准均匀电场测试了C3F7CN/CO2混合气体的工频击穿特性及自恢复特性,系统分析了混合比和气压等因素对工频击穿电压的影响情况及C3F7CN与CO2气体间的协同效应,并与相同条件下的SF6进行对比。研究发现,C3F7CN体积分数为2%～8%的混合气体的工频击穿电压随气压增加呈线性增长趋势,随混合比的增加呈饱和增长趋势。混合比为2%的C3F7CN/CO2混合气体工频击穿电压能达到相同条件下纯SF6的50%,混合比为8%的C3F7CN/CO2混合气体工频击穿电压能达到相同条件下纯SF6的75%。C3F7CN与CO2气体存在一定的协同效应。另外,C3F7CN混合气体的复原特性优良。相关研究成果证实了C3F7CN/CO2混合气体具有替代SF6的潜力。

基于STATCOM的直流融冰控制系统与策略

直流融冰技术是解决输电线路覆冰的主要方法之一,中性点相连的2台星接链式STATCOM可实现直流融冰,同时兼具动态无功补偿功能。首先介绍了直流融冰装置的运行原理,然后研究了三相电压型整流器(voltage source rectifier,VSR)控制系统的设计,提出了均压控制与饱和调制控制方法,解决了传统控制方法下融冰电流较小的问题。最后搭建了基于NI和RT-LAB的实时仿真平台进行仿真,结果表明输出的融冰电流显著提高,验证了方案的正确性。

基于COMSOL和MATLAB的输电铁塔力学仿真界面设计

输电线路覆冰严重时,可能导致线路断线、线间闪络、铁塔倒塌等事故,严重影响电网的稳定运行。为了更深入地了解输电铁塔关键构件的力学特性,提高其运行质量并降低运维成本,本文利用COMSOL和MATLAB设计了一个具有交互功能的输电铁塔力学仿真界面。用户可以根据需要输入不同的仿真参数,并通过点击不同电压等级下的输电铁塔类型节点进行关键构件的力学仿真和参数计算。该仿真界面实现了输电铁塔的几何建模、网格剖分、仿真结果云图展示以及关键构件的最大节点位移、最大轴向应力等力学参数的动态输出。同时,根据输出参数对输电铁塔的力学失效状态进行评估。界面操作简单直观,用户可以快速获取仿真结果,有助于加深对输电铁塔关键构件力学仿真的理解。这对于开展输电铁塔关键构件的运行维护工作,提高输电铁塔的运行质量具有重要意义。

基于动态C藤pair-Copula的电力系统动态经济调度场景协同优化算法

新能源的大规模并网为电力系统的稳定经济运行引入了复杂的不确定性。已有的电力系统经济调度模型研究中,对于多维新能源之间出力相关特性的考虑较少,建模精细度有待提高。为准确描述高维新能源间的出力相关特性,基于动态C藤pair-Copula理论建立了高维相依新能源出力的动态Copula模型。同时,着眼于解决高维新能源接入系统后,求解动态经济调度模型效率不高的问题,首先利用多学科协同优化算法针对误差场景分解实际模型,从而得到各子学科场景的动态经济调度模型;其次,对包含系统级和误差场景级的双层优化模型进行循环交互的降维求解,提升引入高维相依新能源的协同优化调度计算效率。最后,通过IEEE118节点系统的仿真建模算例,验证了文中所提模型及算法的有效性和实用性。

Research on Optimization for Units Start During Power System Restoration

Considering units starting and network constraints and the concept of optimization period,a optimization model which is a typical multi-constraint knapsack problem is established to solve the selection optimization problem of units starting in power system restoration period in this paper, and the objective of the model is to maximize the total power generation capability. A relative effectiveness assessment based on a improving data envelopment analysis is adopted to select the initial units to be started, genetic algorithms are employed to solve the knapsack problem to determine the most reasonable units be started at the current time. Finally, IEEE-39 bus system simulation result proves that the proposed model is feasible and effective.

Emergency Control Strategy Based on Multi-agent Theory under Blackout

The multi-agent theory is introduced and applied in the way to strike the control amount of emergency control according to stability margin, based on which an emergency control strategy of the power system is presented. The multi-agent control structure which is put forward in this article has three layers: system agent, areal agent and local agents. System agent sends controlling execution signal to the load-local agent according to the position and the amount of load shedding upload from areal agent;The areal agent judges whether the power system is stable by monitoring and analyzing the maximum relative power angle. In the condition of instability, determines the position of load-shedding, and the optimal amount of load-shedding according to the stability margin based on the corrected transient energy function, upload control amount to system agent;local-generator agent is mainly used for real-time monitoring the power angle of generator sets and uploading it to the areal agency, local-loads agent control load by receiving the control signal from system agent. Simulations on IEEE39 system show that the proposed control strategy improves the system stability.

Classification of Transmission Line Ground Short Circuit Fault Based on Convolutional Neural Network

Ground short circuit faults in current transmission lines are common in the power systems.In order to prevent the power system from aggravating the accident caused by short-circuit faults of transmission lines,a novel convolutional neural network(CNN)model is constructed to identify the short-circuit fault of the transmission line in the power system.The CNN model is mainly consisted of five convolutional layers,three max-pooling layers,one concatenate layer,one dropout layer,one fully connected layer,and a Softmax classifier.This method uses a fixed time window to intercept system short-circuit fault data,extracts the deep features of these data from the training samples,and then corresponds the extracted features to labels one-to-one.Finally,in PSCAD/EMTDC,the new England 10 machine 39 nodes are taken as an example to realize the simulation.The experimental results show that the CNN model can quickly and accurately identify the short-circuit fault types,and the optimal model accuracy rate reaches 99.95%.The results of this manuscript-have positive effect on enhancing the disaster prevention capability and the operation stability of transmission lines.

Parameters Identification for Extended Debye Model of XLPE Cables Based on Sparsity-Promoting Dynamic Mode Decomposition Method

To identify the parameters of the extended Debye model of XLPE cables,and therefore evaluate the insulation performance of the samples,the sparsity-promoting dynamicmode decomposition(SPDMD)methodwas introduced,aswell the basics and processes of its applicationwere explained.The amplitude vector based on polarization current was first calculated.Based on the non-zero elements of the vector,the number of branches and parameters including the coefficients and time constants of each branch of the extended Debye model were derived.Further research on parameter identification of XLPE cables at different aging stages based on the SPDMD method was carried out to verify the practicability of the method.Compared with the traditional differential method,the simulation and experiment indicated that the SPDMD method can effectively avoid problems such as the relaxation peak being unobvious,and possessing more accuracy during the parameter identification.And due to the polarization current being less affected by the measurement noise than the depolarization current,the SPDMD identification results based on the polarization current spectral line proved to be better at reflecting the response characteristics of the dielectric.In addition,the time domain polarization current test results can be converted into the frequency domain,and then used to obtain the dielectric loss factor spectrum of the insulation.The integral of the dielectric loss factor on a frequency domain can effectively evaluate the insulation condition of the XLPE cable.

Identification of Critical Lines in Power System Based on Optimal Load Shedding

Based on risk theory, considering the probability of an accident and the severity of the sequence, combining N-1 and N-2 security check, this paper puts forward a new risk index, which uses the amount of optimal load shedding as the severity of an accident consequence to identify the critical lines in power system. Taking IEEE24-RTS as an example, the simulation results verify the correctness and effectiveness of the proposed index.

三相导线-相间间隔体系直流融冰热特性有限元及脱冰动力响应分析

为研究输电线路导线直流融冰非对称运行特性,以LGJ-400/50输电导线为研究对象,建立不同运行条件下的输电导线实体模型,采用COMSOL软件探究不同覆冰厚度对导线温度分布的影响,并对不同环境温度和不同风速对导线中心点温度变化进行分析,得到脱冰时刻导线温度作为初始条件施加,应用ANSYS LS-DYNA PrepPost非线性结构动力学模型,建立实际运行过程三相导线-相间间隔体系有限元模型,分析导线体系直流融冰非对称脱冰动力响应。结果表明,在采用不同融冰方案工况下,不同脱冰相数下导线体系最大脱冰跳跃高度不同,三相导线-相间间隔导线体系在融冰过程中相比单导线脱冰情况具有非对称性,依据间隔棒布置条件对导线体系脱冰动力响应影响规律,能够优化导线相间距进而保证直流融冰过程安全运行。

基于IEDScout的数字化保护装置建模研究

IEC 61850标准为解决智能电子设备间的互操作性问题提供了一种新方法。近年来其应用领域也不断得到扩展,但由于配电网络线路复杂、设备数量巨大,IEC 61850标准在配电自动化领域的应用仍需进一步探索。以智能配电网为研究环境,以具体的数字化配电保护装置为研究对象,首先阐述了IEC 61850基本体系和信息模型。然后按照IEC 61850面向对象的建模技术,对数字化保护装置进行了功能定义和分解,并利用标准中的信息模型对其逻辑节点及逻辑设备进行了建模。最后利用SCL编辑工具建立保护装置IED模型文件,IEDScout测试工具与保护装置进行通信,Wireshark网络分析软件捕获报文,验证模型的正确性。

基于改进卷积神经网络的非侵入负荷辨识方法研究

非侵入式负荷监测作为客户侧泛在电力物联网重要技术之一,不仅有助于电力公司加强负荷管理,还可以引导用户合理安排负荷的使用,为实现以家庭电力用户为主体的需求侧响应和满足居民用户对精准精益用电服务需求提供了重要的技术支持。对非侵入式负荷监测中低频采样信号分辨率低,负荷特征易重叠,以及卷积神经网络不能有效辨识具有相似波形特征负荷的问题,提出了融合暂态电流波形和时域特征的改进方法,将暂态电流值均方根融合到电流波形图像以提升相似波形特征负荷的辨识正确率。通过实测数据和负荷识别参考数据集(REDD)测试,验证了所提方法的可行性和有效性。

适应于逆变型风电接入系统的改进故障序分量选相方法

针对传统故障序分量选相元件在逆变型风电接入系统中可靠性较低的问题,提出了一种改进的故障序分量选相方法。首先,分析在最新风电场低电压穿越策略下,风电侧的故障序阻抗特性及传统故障序分量选相元件的适应性。然后,利用负正序、负零序阻抗相位差等效正负序、零负序电流分支系数相位差,以补偿传统序分量选相判据的相角误差。最后,采用补偿后的故障序电流相位差作为选相判据,实现了故障相的判别。同时通过调整零负序选相分区,使其具有较好的耐过渡电阻能力。仿真实验表明,在不同故障类型、故障位置和过渡电阻下改进选相方法均能可靠地选出故障相。