Distributed simulation for power system analysis including shipboard systems

Power systems are distributed in nature. Often they can be divided into sections or groups and treated separately. Terrestrial power systems are divided into separate utilities and are controlled by different regional transmission organization (RTO). Each RTO has detailed data for the area under its control, but only limited data and boundary measurements of the external network. Additionally, shipboard power systems may be divided into sections where local information is kept but not distributed to other parts of the system. Thus, performing a comprehensive power system analysis in such a case is challenging. Also, simulating a large-scale power system with detailed modeling of the components causes a heavy computational burden.     

船舶区域配电系统全智能体重构及其优化研究

为确保船舶电力系统故障发生时主电力推进动力系统不失去供电,对电力推进船舶区域配电系统的拓扑结构重构方法进行了深入研究。依托智能体理论,设计了一种环境智能感知、信念产生、目标控制、粒子群最优决策的全智能体重构方法,实施船舶区域配电系统故障的拓扑重构。重构策略以保证全船的不间断供电、负荷损失最小、继电保护效率最高等为目标。对某电力推进船舶区域配电系统电网发生三相短路工况的仿真实验表明,所设计的全智能体方法相比粒子群算法、遗传算法的电力系统重构更能保证船舶电力系统的安全运行,且具有电力系统故障时重构功率损耗更小、开关效率更高的优点;进一步提高了船舶电力系统的安全可靠性。     

考虑可靠性约束的舰船电力系统故障重构策略

网架重构是舰船电力系统发生故障时恢复供电的有效措施。考虑到舰船电力系统的特殊工况,故障重构时有必要考虑重要负荷的供电可靠性和电能质量,为此提出了一种考虑可靠性约束的舰船电力系统故障重构策略。利用图论建立了供电可靠性与电网拓扑之间的关联模型,并通过深度搜索算法遍历重要负荷节点的所有供电路径。基于二阶锥规划建立了故障重构凸优化模型,并进一步通过多面体逼近算法将模型转化为混合整数线性规划问题以加速求解。通过系统仿真并对比分析,结果表明所提出的算法能快速获取全局最优解,所得到的故障重构策略能保证重要负荷的电能质量与供电可靠性。     

改进粒子群算法在船舶电力系统网络重构中的应用

船舶电力系统网络重构本质上是带约束的多目标组合优化问题.针对船舶电网重构问题的特点,建立了船舶电力网络的无向图模型;在此基础上,进一步建立了以负荷恢复量、开关操作次数和发电机效率均衡性为优化目标的船舶电力系统多目标重构模型:提出了一种结合"背包策略"和模拟退火算子的改进粒子群算法进行求解.其中"背包策略"可以明显提高粒...     

Self-healing reconfiguration for restoration of naval shipboard power systems

Naval shipboard power systems form a critical component of the U.S. defense infrastructure. When there is a fault in a shipboard power system either due to battle damage or material casualty, it is important to quickly isolate the fault and restore supply to as many loads as possible. This paper presents an automated self-healing strategy for reconfiguration for service restoration in naval shipboard power systems. The proposed method is illustrated on a system developed based on a typical surface combatant ship.     

Optimized restoration of combined ac/dc shipboard power systems including distributed generation and islanding techniques

Reconfiguration involves changing the status (OFF/ON) of switches, and reconfiguration for restoration involves changing the switch status to maximize the supply to loads that are left unsupplied after fault removal. Shipboard Power Systems (SPS) need automated reconfiguration for restoration schemes to restore vital loads quickly and efficiently in order to improve fight-through and survivability capabilities. The restoration in this paper is achieved using optimization with multiple objectives—maximizing the restored load and giving priority to vital loads. A restoration scheme for SPS with an integrated power system (IPS) and distributed generation (DG) involving islanding has been developed. This formulation includes a hybrid power system that has both ac and dc parts. The restoration formulation in this paper also considers the unbalanced nature of SPS operation with mutual coupling.     

A multiagent approach to power system normal operation

Recently, the electric utility industry worldwide has been facing pressure to be deregulated or restructured in order to increase its efficiency, to reduce operational cost, or to give consumers more alternatives. For this aspect, a great deal more research is needed to achieve a better, intelligent knowledge process. The present centralized system for power system control, operation, and planning must be remodeled to cope with these situations. With the promotion for the deregulation of the electric power system, the definition of the objective function for the optimization problem such as outage work operation for electric power systems is becoming critical. Currently, agents are an intense focus in many subfields of computer science and artificial intelligence. Agents are being used in an increasingly wide variety of applications. In this paper, we developed a power system normal operation application by multiagent architecture. Our multiagent system consists of several facilitator agents, equipment agents, and switch‐box agents. Facilitator agent acts as a manager for negotiation process between agents. Equipment agent corresponds to the element of the electric power system, such as bus, transformer, and transmission line, while switch‐box agent is the pseudo object which consists of neighboring current breakers and disconnecting switches. The proposed system realizes the appropriate switching operations by interacting with corresponding agents. The proposed approach is applied to a simple network, and the results show that the proposed multiagent system is an efficient decentralized approach for solving power system normal operations. © 2004 Wiley Periodicals, Inc. Electr Eng Jpn, 146(4): 26–33, 2004; Published online in Wiley InterScience ( www.interscience.wiley.com ). DOI 10.1002/eej.10227     

A case-based construction method for a fault-restoration support system in secondary power systems

The authors have already clarified that case-based reasoning (CBR) is very useful for the fault-restoration support system in electrical power networks. This paper describes the case-based construction method, adaptation and modification method of a case which is a fundamental process of CBR, and the results of evaluation. The following points were clarified through the simulations of fault restoration under various conditions with electrical power networks of practical scale: (1) a case-based construction method and the guide to the selection of cases which should be included in the case were made clear. Restoration plans which include many cases are registered in the base. Cases which would require long computation time are also registered in the case base. In the application which requires high-speed processing, such as fault restoration, there exists an optimum value in the total numbers of cases in the case base; (2) the function of load switching which is essential to perform adaptation and modification of a case flexibly was studied and embedded in the system herein. Inference power was augmented by the implemented of this function, and optimum for suboptimum solutions were obtained. Processing time with CBR is considerably shorter than other methods, and this feature is remarkable with complicated cases.     

免疫克隆选择算法在船舶电力系统故障恢复中的应用研究

实现船舶电力系统的快速供电恢复是一个复杂的多目标非线性组合优化问题。为了解决船舶电力系统发生故障时供电恢复问题,采用了免疫克隆算法,并对算法的变异算子进行了改进,改进后的变异算子把高频变异和柯西变异有效的结合在一起,兼顾全局搜索和局部搜索,吸取了遗传算法并行搜索优点,提高了搜索效率和收敛性。船舶电力系统典型故障恢复算例表明,该算法具有很高的搜索效率和寻优性能,能有效地提高供电恢复的速度及精度,较好地实现船舶电力系统的故障恢复。     

船舶环形配电网无通道保护方法研究

环形配电网结构具有较高船舶生命力和供电可靠性,在大型船舶电力系统中逐渐得到应用。然而在环网中,传统的保护方法很难在短时间内切除电站附近的故障。针对船舶环形电网的特点,提出了两种无通道保护方法。两种方法都利用了短路故障和线路一侧保护跳闸引起另一侧支路的电流变化,方法一和方法二分别通过加速保护的动作时限特性和电流比值判据来判断故障区间,最终实现相继速动。通过Matlab/Simulink仿真验证了两种方法的可靠性和速动性。     

Integration of a bi-directional DC-DC converter model into a real-time system simulation of a shipboard medium voltage DC system

A bi-directional dc/dc converter model is investigated for a notional Medium Voltage DC (MVDC) shipboard power system to improve energy flexibility and deal with peak energy demand in shipboard power system. Surplus energy in the MVDC system during light load condition can be captured by energy storages distributed in local load zones through the bi-directional dc/dc converters and then can be used during heavy load condition or black starting of the MVDC system. In this paper, the derivation process of the small-signal average models of the isolated-type bi-directional dc/dc converter is presented for controller design. This paper also presents the controller optimization process using intelligent optimal searching algorithm, Particle Swarm Optimization, for optimizing dynamic and steady-state control performance of a bi-directional dc/dc converter. The control performance of the proposed controller is evaluated using frequency-domain analysis and time-domain simulation of the large-scale notional MVDC shipboard power system using the Real-Time Digital Simulator.     

应用模糊聚类的电力系统网络重构分析

以提高电力系统电压稳定裕度为目的,基于模糊聚类方法对网络重构进行分析。若系统网络发生故障(如某联络线发生短路、过载等)或因不确定性问题引起其他网络故障,应迅速切除。为不影响负荷供电,需要其他线路替代故障点,但此时可能有多种候选方案。应用模糊聚类方法将众多候选支路予以分类,在最大限度提高电压稳定裕度的基础上选取最为合适的候选支路,以完成网络重构。应用IEEE-30节点系统验证所提模糊聚类分析方法的正确性和有效性。     

基于电流饱和深度的船舶电网接地故障定位装置的研究

针对船舶交流电网接地故障的特点,比较了现有接地故障选线方法的利弊,提出基于饱和深度的零序电流幅值比较法,并研制出实际装置,实船应用验证了装置原理和方法的合理性和有效性。     

A decentralized control system for stabilizing multimachine power systems

A decentralized control system is studied for stabilizing multimachine power systems. A longitudinal power system with three areas, each having one machine, is considered in this study. A decentralized control design method is proposed, which is based on the optimal regulator theory. First a centralized control system is designed without any consideration on whether state variables are all available or not. Second a pseudo-decentralized control system is designed by omitting control gains corresponding to state variables which give hardly any effects on the power system stability. It is found that only one variable of phase angle of each machine is absolutely necessary for the pseudo-decentralized control system. This leads to an idea based on power system engineering, that is to say, new variables of tieline power flow are introduced in the decentralized control system design to substitute for the phase angle of each machine. Thus a decentralized control system for power system stability can be designed using the new variables of tieline power flow. It is demonstrated from simulation studies that the decentralized control system improves even longitudinal power system stability as well as the centralized control system.     

采用云理论自适应遗传算法的舰船电力系统故障智能恢复策略

提出了基于云理论自适应遗传算法并面向负荷投切的舰船电力系统故障智能恢复策略,该方法在考虑负荷和开关优先级及线路负荷分配均衡的基础上,借助于正态云固有的稳定倾向性和随机性,由云发生器自适应调整交叉率和变异率,增强了算法鲁棒性,改善了算法收敛速度。算例分析验证了基于云理论自适应遗传算法多目标故障恢复策略的可行性和有效性,且优于标准遗传算法和传统自适应遗传算法,具有一定的实用价值。     

Oppositional krill herd algorithm for optimal location of capacitor with reconfiguration in radial distribution system

The delivery of power from sources to the consumer points is always accompanied of power losses. Basically, active losses in distribution systems can be reduced by optimal reconfigurations of the network. Optimal capacitor allocation problem in reconfigured distribution network is a challenge of researchers for several decades. This paper presents a computationally efficient methodology namely, krill herd (KH) algorithm to find optimal location of capacitor and optimal reconfiguration in order to minimize real power loss of radial distribution systems. Moreover, the opposition based learning (OBL) concept is integrated with KH algorithm for improving the convergence speed and simulation results. In order to show the usefulness and supremacy, the conventional KH and proposed oppositional KH (OKH) algorithms are tested on 33-bus and 69-bus radial distribution networks. The simulation results of the proposed methods are compared with fuzzy multi-objective approach and non dominated sorting genetic algorithm (NSGA). The solution results show that OKH technique could generate better quality solutions and better convergence characteristics than those obtained by conventional KH algorithm and other existing optimization techniques available in the literature. Results also show the robustness of the proposed methodology to solve reconfigured distribution network (RDN) problems.     

Distribution system reconfiguration for loss minimization using modified bacterial foraging optimization algorithm

In this paper the network reconfiguration problem is formulated as non-linear objective optimization problem. The proposed solution to this problem is framed as a non-linear combinatorial optimization problem and status of switches is non-differentiable which is solved using modified bacterial foraging algorithm, the algorithm is modified for better convergence. The modified bacterial foraging algorithm is described in a general context and then applied specifically to the network reconfiguration problem. This program was tested on 16 bus, 33 bus & 69 bus test systems. The test results proved that the efficiency of modified bacterial foraging algorithm is better than other existing methodology.     

发电企业风险知识管理系统研究

发电企业实际安全生产所存在的危险不是单一的,是多项危险相关联.基于现代质安健环管理理论,提出采用风险知识管理系统来进行风险管理.通过该系统对典型风险源及其预控措施进行全面知识管理和知识应用,提供科学有效的风险信息,指导安全生产,解决了因发电企业作业的复杂性而导致风险源和预控工作分析难的问题.     

An interpretative structural modeling based network reconfiguration strategy for power systems

The network reconfiguration is an important stage of restoring a power system after a complete blackout or a local outage. Reasonable planning of the network reconfiguration procedure is essential for rapidly restoring the power system concerned. An approach for evaluating the importance of a line is first proposed based on the line contraction concept. Then, the interpretative structural modeling (ISM) is employed to analyze the relationship among the factors having impacts on the network reconfiguration. The security and speediness of restoring generating units are considered with priority, and a method is next proposed to select the generating unit to be restored by maximizing the restoration benefit with both the generation capacity of the restored generating unit and the importance of the line in the restoration path considered. Both the start-up sequence of generating units and the related restoration paths are optimized together in the proposed method, and in this way the shortcomings of separately solving these two issues in the existing methods are avoided. Finally, the New England 10-unit 39-bus power system and the Guangdong power system in South China are employed to demonstrate the basic features of the proposed method.     

Issues for power system operation for future renewable energy penetration: Robust power system security

A large amount of PV penetration may introduce uncertainties in future power system planning and operations. This paper proposes the concept of “Robust Security (RS)” and the “RS region” in order to investigate power system security in the presence of a large amount of uncertainties. The RS region is defined as the region of power system operation where the system is secure under uncertainties. It is shown that the region tends to shrink and disappear for a high degree of PV penetration. Emerging problems concerned with security in future power systems are investigated. © 2012 Wiley Periodicals, Inc. Electr Eng Jpn, 182(1): 30–38, 2013; Published online in Wiley Online Library (wileyonlinelibrary.com). DOI 10.1002/eej.22289