Enhancement of power system data debugging using GSA-based data-mining technique

In this paper, a gap-statistic-algorithm (GSA)-based data-mining technique is applied to enhance the data debugging in power system operations. In the proposed approach, the GSA technique is embedded into a neural network frame in anticipation of improving the detection capability of bad data. Thanks to the clustering capability exhibited by GSA in which the number of clusters can be optimally determined, the proposed approach becomes highly effective to localize the group of abnormal data. This proposed approach has been tested through the data collected from different scenarios made on an IEEE 30-bus system and 118-bus systems. Test results reveal the feasibility of the method for the data diagnosis applications.     

Time delay approach for PSS and SSSC based coordinated controller design using hybrid PSO–GSA algorithm

In this work we present a novel approach in order to improve the power system stability, by designing a coordinated structure composed of a power system stabilizer and static synchronous series compensator (SSSC)-based damping controller. In the design approach various time delays and signal transmission delays owing to sensors are included. This is a coordinated design problem which is treated as an optimization problem. A new hybrid particle swarm optimization and gravitational search algorithm (hPSO–GSA) algorithm is used in order to find the controller parameters. The performance of single-machine infinite-bus power system as well as the multi-machine power systems are evaluated by applying the proposed hPSO–GSA based controllers (PSS and damping controller). Various results are shown here with different loading condition and system configuration over a wide range which will prove the robustness and effectiveness of the above design approach. From the results it can be observed that, the proposed hPSO–GSA based controller provides superior damping to the power system oscillation on a wide range of disturbances. Again from the simulation based results it can be concluded that, for a multi-machine power system, the modal oscillation which is very dangerous can be easily damped out with the above proposed approach.     

Fully reference-independent LMP decomposition using reference-independent loss factors

The decomposition of locational marginal price (LMP) under the popular DCOPF framework generally depends on the choice of the reference bus. A previous work has achieved reference independence for the overall LMP and LMP congestion component, but not all individual LMP components. This paper proposes a method to obtain a truly reference-independent LMP decomposition such that all three components of LMP at each bus will be invariant w.r.t. the choice of the system reference bus. This is achieved with loss factors based on a new AC-based distribution factor model, which depends on the network topology and the present operating condition only, but not the system reference bus. This model gives reference-independent loss prices, which can serve for a better loss hedging financial transmission rights, since the choice of reference bus will not change the loss prices. Further, this paper uses the fictitious nodal demand (FND) model to obtain loss distribution factors (LDFs). FND gives more reasonable power flows since losses should be distributed in each individual line, rather than at load buses when the load-weighted LDFs are applied. Also, the proposed reference-independent distribution factors and loss factors may have great potentials in other areas of power system analysis.     

An improved distribution network reconfiguration method based on minimum spanning tree algorithm and heuristic rules

This paper presents an improved distribution network reconfiguration method with the goal to minimize active power loss. The proposed method combines the minimum spanning tree (MST) algorithm and improved heuristic rules. It consists of three procedures. The first procedure calculates the branch (edge) weights with bus (vertex) voltages, and then carries out preliminary optimization with MST algorithm to get a local optimal solution. The second procedure gets alternative optimal solution based on the improved heuristic rules. Then during the third procedure, the optimal solution can generally be obtained through correcting the results. The algorithm does not rely on the initial network topology. The local optimal solution, solved by MST algorithm, provides a favorable initial condition for the subsequent optimization procedures. Further with the improved heuristic rules, the amount of the candidate switches can be significantly reduced. Two typical test systems, 33-bus system and 69-bus system, and a real 210-bus MV utility distribution system verified the feasibility and effectiveness of the proposed method. The method has higher efficiency and can be used to the large distribution systems.     

基于交替方向乘子法的主动配电网分布式多目标优化调度

主动配电网优化调度是实现主动配电网中各类分布式能源协调、高效利用的有效手段。随着分布式能源渗透率的逐渐提高,传统的集中式优化调度面临计算复杂、通信量大、目标单一等问题,基于此,提出了一种基于交替方向乘子法(alternating direction method of multipliers,ADMM)的主动配电网分布式多目标优化调度方法。建立了计及分布式电源、柔性负荷、储能装置等的多区域、多目标优化调度模型,采用ADMM进行相邻分区间的交替迭代并行计算,降低了计算复杂度,并且各分区可根据利益主体的不同实际情况与重点需求,科学、独立地确定不同的优化目标,与目前普遍采用的统一设定各分区相同优化目标的调度方法相比,大大提高了灵活性;同时,相邻分区间只需交互少量信息,使通信量大幅减小。最后通过对算例的分析验证了所提方法的可行性与高效性。     

A novel algorithm for ATC calculations and applications in deregulated electricity markets

In this new deregulated environment, transmission networks should be regulated to ensure a competitive, open, and reliable market, which relies on the implementation of many transmission assessment functions. Among them, a key concept is the ability to quantify accurately and rapidly the capabilities of the transmission system. Accurate ATC values on major interfaces of the system can provide an important index to evaluate system security and reliability.

The main contribution of this paper is to propose a novel algorithm for contingency ATC computation and a sensitivity analysis for system uncertainties. It incorporates linear distribution factors and AC load flow sensitivity-based method in order to calculate ATC values efficiently and speedily considering line outages.     

An efficient hybrid method for solving the optimal sitting and sizing problem of DG and shunt capacitor banks simultaneously based on imperialist competitive algorithm and genetic algorithm

Nowadays due to development of distribution systems and increase in electricity demand, the use of distributed generation (DG) sources and capacitors banks in parallel are increased. Determining the installation location and capacity are two significant factors affecting network loss reduction and improving network performance. This paper, proposes an efficient hybrid method based on Imperialist Competitive Algorithm (ICA) and genetic algorithm (GA) which can greatly envisaged with problems for optimal placement and sizing of DG sources and capacitor banks simultaneously. The objective function is power loss reduction, improving system voltage profile, increasing voltage stability index, load balancing and transmission and distribution relief capacity for both utilities and the customers.The proposed method is implemented on IEEE 33 bus and 69 bus radial distribution systems and the results are compared with GA/Particle swarm optimization (PSO) method. Test results show that the proposed method is more effective and has higher capability in finding optimum solutions.     

适用于双边交易的一种基于灵敏度的网损分摊方法

在电力市场下网损分摊问题的处理方法中,灵敏度方法由于具有经济导向作用,受到了普遍关注.但其分摊结果中常常出现一些交易承担负值网损份额的情况,这是不公平的.因为如果没有其他交易,任一交易都必定承担正值网损,所有交易既然在使用电力网络的过程中都生成了网损,应该让它们一起承担系统网损,即平均分摊到正值的网损份额.在此基础上,作者提出了一种适用于双边交易的使用线路网损灵敏度分摊网损的损耗分摊方法.先计算得出各交易在每条线路上的线路网损灵敏度;然后以其绝对值为依据,在各交易间分摊所有线路上的网损;最后加总,得到各交易应承担的总网损份额.以IEEE2机14节点系统的11个双边交易为例,通过对算例系统的计算、分析及比较,验证了所提算法在依据灵敏度合理分摊网损的同时,能够解决灵敏度类方法中网损份额结果存在负值的问题.     

基于相空间重构与GSA-LVQ的有载调压变压器分接开关机械故障诊断

针对有载调压变压器分接开关机械故障诊断准确率不高以及潜在机械故障不能及时被发现的问题,提出了一种基于互补集合经验模态分解(CEEMD)、相空间重构结合万有引力搜索法(GSA)改进学习矢量量化神经网络(LVQ)的有载分接开关机械故障诊断新方法。采用CEEMD对振动信号进行时频域分解,然后通过C-C算法确定延迟时间和嵌入维数,对反映不同频率特征的固有模态函数(IMF)进行相空间重构,并提取反映混沌特征的两个特征量李雅普诺夫指数和关联维数构成特征向量。利用GSA优化LVQ,解决网络对初始连接权值敏感的问题,增强网络对有载分接开关机械故障分类识别性能。通过对有载分接开关机械状态的实验分析,证明了相空间重构结合GSA-LVQ算法的可行性和有效性。     

基于GSA的电力系统不良数据辨识算法

随着数字化技术在电力系统中的广泛应用及对电力系统运行可靠性要求的不断提高,不良数据的辨识显得越来越重要。目前广泛应用的状态估计法,存在残差污染等缺点。论文研究了建立在神经网络和聚类分析基础上的GSA不良数据辨识算法,该算法运用神经网络完成对测量数据的预处理,然后由GSA算法对聚类分析后的结果进行判断,完成不良数据的辨识。论文借助M atlab及C语言对GSA算法进行了仿真,通过一个具体的网络不良数据辨识将此算法与状态估计算法进行了比较,验证了该算法的有效性及实用性,有效地避免了不良数据的漏检、误检。     

MMC-UPFC在南京西环网的应用及其谐波特性分析

基于模块化多电平换流器(MMC)的统一潮流控制器(UPFC)是当前最新型的柔性交流输电技术,与柔性直流输电中MMC交流电压在额定值附近不同,理论上UPFC串联侧MMC输出电压可在零到额定值之间任意可调,在调制比较小时,换流器输出电压中将含有较大的谐波成分。结合南京西环网UPFC实际工程,为研究基于MMC的UPFC对电网谐波的影响,从UPFC工作原理出发分析MMC谐波理论计算方法及分布特性,给出了UPFC接入系统后电网谐波的计算公式,用于评估系统各种运行方式下UPFC在不同子模块数量及电压调制比下的谐波特性及其对电网电压谐波的影响,为工程设计和系统运行维护提供依据。最后,理论计算和仿真结果验证了所提出的谐波分析计算方法的有效性。     

基于灰色关联分析法及GSA-LSSVM的汽轮机排汽焓预测模型

排汽焓是汽轮发电机组热经济性诊断必不可少的一个参数。通过汽轮机功率方程与灰色关联分析(grey correlation analysis,GCA)理论确定了模型的输入变量,利用万有引力搜索算法(gravitational search algorithm,GSA)优化了最小二乘支持向量机(least squares support vector machine,LSSVM)的惩罚因子μ以及核径向范围σ2个参数。通过比较分析,选用RBF_kernel为LSSVM的核函数。以GCA-GSA-LSSVM为基础,建立了预测汽轮机排汽焓的数学模型,并将其与BP神经网络、RBF神经网络进行对比,同时分析了该数学模型的鲁棒性。结果表明基于GCA-GSA-LSSVM的汽轮机排汽焓预测模型具有精度高、泛化能力强、鲁棒性强等优点,该方法为精确预测机组节能潜力提供了一种有力的工具。     

配电网安全性指标的研究

该文从配电网供电安全性出发，在K（N-1 1）安全性准则的基础上，通过比较配电网和输电网的差异，指出配电网静态安全分析需要不同于输电网的安全性指标和分析方法。以此为前提提出了事故后果严重程度指标，并在此基础上进一步提出系统网架结构强弱指标和系统整体安全性指标，作为配电网静态安全分析的基础。文中还对指标的应用进行了探讨，并利用算例对安全性存在差异的系统的各项安全性指标进行了计算、分析和比较。算例表明文中提出的配电网安全性指标是可行的。它能够定量地刻画事故后果的严重程度，准确地反映系统安全性的高低，为配电网静态安全分析奠定了基础。     

柔性配电网的最大供电能力模型

提出了柔性配电网(FDN)的最大供电能力(TSC)模型与计算方法。首先,提出了FDN的概念,FDN利用电力电子开关构成的柔性开闭站(FSS)将多回馈线联络组网,采用能灵活控制潮流的柔性闭环运行方式。其次,提出了FDN的TSC模型与求解方法,模型计及了FSS对负荷的柔性转带策略。最后,搭建典型组网形态下不同情况的FDN验证所述方法。与传统配电网TSC对比发现:FDN的TSC总量既有提升的情况也有不变的情况,文中分析了原因。从TSC角度看,FDN的优势在于:1TSC在FDN实际运行中更易实现,达到TSC时FDN允许馈线上负荷任意分布,而传统配电网只有在负荷满足特定分布时才能达到TSC;2达到同等TSC时,FDN的组网结构更简单。所述方法已应用于国内外首个多端柔性闭环中压配电网示范工程的方案论证。     

Optimal power flow for distribution networks using gravitational search algorithm

This paper presents a gravitational search algorithm (GSA)-based approach to solve the optimal power flow (OPF) problem in a distribution network with distributed generation (DG) units. The OPF problem is formulated as a nonlinear optimization problem with equality and inequality constraints, where optimal control settings in case of fuel cost minimization of DG units, power loss minimization in the distribution network, and finally simultaneous minimization of the fuel cost and power loss are obtained. The proposed approach is tested on an 11-node test system and on a modified IEEE 34-node test system. Simulation results obtained from the proposed GSA approach are compared with that obtained using a genetic algorithm approach. The results show the effectiveness and robustness of the proposed GSA approach.     

GPRS通信技术在配电网自动化中的应用研究

根据配电自动化对通信系统的要求,在分析现行配电网自动化各种通信技术的基础上,提出采用通用分组无线业务(GPRS)通信技术解决配电自动化信息传输问题的设想,通过对GPRS可用性、可靠性、安全性及经济性等方面的论述,结合GPRS应用系统的方案设计及组网测试结果,认为将GPRS通信技术应用于配电网自动化传输是可行的。     

EXTERNAL SYSTEM MODELING FOR POWER TRANSMISSION SYSTEM HARMONIC ANALYSIS USING THE BILINEAR THEOREM

Abstract

A method is proposed which easily and accurately determines the relative importance of external system equivalents on the harmonic impedance of a transmission network. Oversimplifications of external systems cause errors in transfer impedance for harmonic analysis. The bilinear theorem provides an economical and accurate method of determining the appropriate locations for network simplification. This method needs three system constants to be computed and then changes in transfer impedance due to variations in equivalent impedance of external system can be checked without extensive network solutions. Using this technique, we can also fix the errors bounds and reduce the high error range of the equivalent impedance. This method permits the modeling of larger transmission systems with a known accuracy for harmonic analysis, filter designs and switching studies     

考虑“风-光-荷-储”联合运行的配电网双层规划方法

分布式电源与储能系统在配电网中的应用是当前研究的热点。提出了一种风机、光伏电源、储能系统在配电网中的双层规划模型。上层模型以投资、运维费用为优化目标,同时考虑区域的购电费用及网损费用,完成风机和光伏电源的容量配置;下层模型提出了一种储能系统削峰填谷的运行策略,基于该策略完成储能系统的选址定容工作。针对以上模型,提出以下求解方法:基于遗传算法求解上层模型,并通过K均值聚类方法对比研究输入数据序列长度对规划结果的影响,通过帕累托分析研究了投资运维费用与购电费用及网损费用的关系;使用YALMIP工具箱完成储能系统运行策略的求解,进而完成储能系统的选址定容工作。最后,通过IEEE-33节点标准配电系统仿真验证了所提模型在风机和光伏电源以及储能系统规划方面的有效性,结果显示所提储能运行策略具有良好的削峰填谷效果。     

LOSS REDUCTION IN DISTRIBUTION NETWORKS USING NEW NETWORK RECONFIGURATION ALGORITHM

ABSTRACT

Network reconfiguration is an operation task, and consists in the determination of the switching operations such to reach the minimum loss conditions of the distribution networks. In this paper, a general formulation of the network reconfiguration for loss minimization is given for the optimization of distribution loss reduction and a solution approach is presented. The solution employs a search over different radial configurations, created by considering branch exchange type switches. The solution algorithm for loss minimization has been developed based on the two stage solution methodology. The first stage of this solution algorithm finds a loop which gives the maximum loss reduction in the network. For this purpose a simple-to-use formula, called loop loss reduction formula, has been developed. To find a branch exchange, which results in the maximum loss reduction in the loop, the second stage applies a proposed technique called distance-center technique. Therefore, the solution algorithm of the proposed method can identify the most effective branch exchange operations for loss reduction, with a minimum computational efforts. The solution algorithm of the proposed method has been tested, with very promising results, on a 69-bus radial distribution system. Test results prove that, via proposed network reconfiguration for loss minimization, real power loss is reduced significantly, and that the voltage profile of the network is considerably improved. As compared to the established methods the proposed method eliminates the need to run numerous load flows.     

分布式电源接入配电网的经济效益及电压稳定性

借助于回归分析方法将配电网和主网联系起来,基于实时电价理论构建了DG接入配电网的经济效益及配电网电压稳定性分析模型。以IEEE30系统节点8下属配电网接入4个DG为例,定量分析了6个典型日内DG接入前后主配网经济效益及配电网电压稳定性。结果表明：DG合理接入后,终端电力用户的支付电价下降,能够有效消除可能出现的输电阻塞;主配网网损率明显下降,提高了电力输送效率;主配网购电成本显著下降,提高了市场运行效率;高峰时段DG因相对低成本而全额发电,能获得较高的利润;配电网电压稳定性明显增强。随着分布式发电技术的成熟,其成本将会不断下降,DG会因具有成本优势和地理位置优势而成为传统电网的有效补充。