A Multiagent‐Based Microgrid Operation Method

In this paper, we propose an autonomous microgrid operation using a multiagent approach. The proposed multiagent system consists of seven types of agent: a single microgrid controller agent (MGC), several load agents (LAGs), several gas‐turbine (gas‐engine) agents (GAGs), several photovoltaic generation agents (PVAGs), several wind‐turbine generation agents (WTAGs), several battery agents (BAGs), and a single grid agent (GridAG). In a microgrid, LAGs act as consumers or buyers, GAGs, PVAGs, and WTAGs act as producers or sellers, and BAGs act as prosumers or sellers/buyers. In order to verify the performance of the proposed system, it is applied to a simple model system with different electrical power prices. From the simulation results, it can be seen that the proposed multiagent system can perform microgrid operations efficiently.     

A multiagent‐based microgrid operation method considering charging and discharging strategies of electric vehicles

In this paper, we propose a multiagent‐based microgrid (MG) operation method considering charging and discharging electric vehicles (EVs). The proposed system consists of five types of agents: single microgrid controller agent, several load agents, several gas turbines/engine agents, several photovoltaic generation agents, and several electric vehicle agents. In the proposed method, the load balancing can be realized by suppressing sudden fluctuations in supply and demand balance due to the synchronization of charging and discharging of EVs. From the simulation results, it can be seen that the proposed multiagent system could realize the load equalization in MG.     

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     

Comparison of Centralized and Decentralized Systems in Power System Restoration

This paper proposes a multiagent approach to decentralized power system restoration for distribution system networks and presents a comparison of centralized and decentralized systems for power system restoration. Numerous studies have been conducted on power system restoration problems. From the viewpoint of system structures, this research can be divided into two categories: centralized systems and decentralized systems. In this study, we solve a power system restoration problem for a power distribution network by two different methods: mathematical programming (MIP) and the proposed multiagent‐based method (MAS). The proposed multiagent system consists of several distributing substation agents (DSAGs) and load agents (LAGs). An LAG corresponds to the customer load, and a DSAG supplies electricity to the LAG. From the simulation results, it can be seen that the proposed system can reach the right solution by making use of only local information and that the solution quality is better than that of the centralized system (MIP). This means that the proposed multiagent restoration system is a promising approach to larger scale distribution networks.     

A multi‐agent approach to unit commitment

This paper proposes a multiagent system to power system unit commitment problems. Multiagent is a new paradigm for developing software applications. Coordinating the behavior of autonomous agents is a key issue in agent‐oriented programming techniques today. Recently, agents are being used in an increasingly wide variety of applications, ranging from comparatively small systems such as E‐mail filters to large, open, complex systems such as air traffic control. Though some agent frameworks have been proposed in the power system field, the number of studies is limited. In this paper, we developed a power system unit commitment application by multiagent architecture. Our multiagent system has the following characteristics: (1) The system consists of a single facilitator agent, two mobile agents, and one or more generator agents which are elements of power system network. (2) The facilitator agent is developed to act as a manager for the process by using the singleton design pattern. The mobile agents migrate to generator‐agents to increase or decrease their power generations. The generator agents have their operational data. (3) Message object is developed to communicate between the agents using KQML‐like object. The proposed approach is applied to a simple model system, and the results show that the multiagent system is an efficient decentralized approach for solving power system unit commitment problems. © 2002 Wiley Periodicals, Inc. Electr Eng Jpn, 141(2): 41–47, 2002; Published online in Wiley InterScience ( www.interscience.wiley.com ). DOI 10.1002/eej.10057     

A Voltage Control Method for a Distributed Line Feeder by means of Multiagent Approach

This paper proposes a method for the coordinated control of power factor by means of a multiagent approach. The proposed multiagent system consists of two types of agent: single feeder agent (F_AG) and bus agent (B_AG). In the proposed system, an F_AG plays as an important role, which decides the power factors of all distributed generators by executing the load flow calculations repeatedly. The voltage control strategies are implemented as the class definition of Java into the system. In order to verify the performance of the proposed method, it has been applied to a typical distribution model system. The simulation results show that the system is able to control very violent fluctuation of the demands and the photovoltaic (PV) generations.     

Compensation of power fluctuations of wind power generation by means of biomass gas turbine generator and flywheel energy storage equipment

Power generation using natural energy contains electric power fluctuations. Therefore, in order to put such power generation systems to practical use, compensation for system power fluctuations is needed. In this paper, we propose a power compensation method using a biomass gas turbine generator and flywheel energy storage equipment. The gas turbine generator is used for compensation of low‐frequency power fluctuations in order to decrease the required flywheel capacity. The usefulness of the proposed system is confirmed by experiments using a test plant. © 2009 Wiley Periodicals, Inc. Electr Eng Jpn, 170(3): 1–8, 2010; Published online in Wiley InterScience ( www.interscience.wiley.com ). DOI 10.1002/eej.20896     

计及风光不确定性的虚拟电厂多目标随机调度优化模型

为缓解风电和光伏发电不确定性对虚拟电厂稳定运行的影响,引入鲁棒随机优化理论,建立了计及不确定性和需求响应的虚拟电厂随机调度优化模型。首先,风力发电、光伏发电、燃气轮机发电,以及储能系统和需求响应集成为虚拟电厂,然后最大化虚拟电厂运营收益、最小化系统运行成本和弃能成本被作为目标函数,建立虚拟电厂调度优化模型。再应用鲁棒随机优化理论来转换光伏发电以及风力发电不确定性变量的约束条件,建立了虚拟电厂随机调度模型。最后,选择中国国电云南分布式电源示范工程为实例分析对象。分析结果显示：所提模型能够降低系统运行成本,双重鲁棒系数的引入能够为不同风险态度决策者提供灵活的虚拟电厂调度决策工具,协助应对风电和光伏发电的随机特性。储能系统能够借助自身充放电特性,替代燃气轮机发电机组为风电和光伏发电提供备用服务,促进风电和光伏发电并网。将需求响应纳入虚拟电厂能够实现发电侧与用电侧联动优化目标,平缓化用电负荷曲线,系统整体运营效益达到最佳。     

风光氢联合式独立发电系统的建模及仿真

提出了一种独立使用的风光氢联合式独立发电系统，该系统由风力发电、太阳能发电、氢能系统(包括电解水制氢、燃料电池系统、超级电容等)及其他系统单元组成。各单元通过2条直流总线联接，并采用功率流控制。由于风力发电与太阳能发电所输出的功率随风速和日照的变化而变化，因此采用燃料电池系统与超级电容堆与风光发电系统配合使用，以保证系统在任何条件下都具有可靠的供电性能。当风能与太阳能充足时，风机与光伏阵列可满足负荷的需要，同时还可向电解池供电；如果不能满足负荷的需要则由燃料电池提供额外的电能，同时由超级电容在短时期内向负荷提供燃料电池最大功率以外的那部分电能。最后在Matlab环境下建立了系统仿真模型，并以西藏边远村落为例对该系统的动态响应进行了仿真分析，仿真结果表明本文提出的供电系统可以用于以西藏为典型代表的风速和光能变化较大的边远地区。     

熔融碳酸盐燃料电池发电厂的应用展望

分析了开发熔融碳酸盐燃料电池 ( MCFC)发电厂的必要性、可能性及资源条件。首次从电极、单电池、电堆、系统 4个层次阐述了 MCFC燃料电池的发电原理 ,并分析了 4个层次中发生的主要热、电过程 ;给出了有代表性的天然气 MCFC发电厂、煤气化 MCFC—燃气轮机—汽轮机联合发电厂的原理、构成和主要过程 ;介绍了 MCFC发电系统商业化的最佳容量、燃料选择、全球主要市场的前景、特点以及商业化存在的障碍。简要阐明了我国大力研究和开发 MCFC发电系统的现实意义。     

考虑不确定性的综合能源博弈规划

随着电力系统与天然气系统的耦合性不断增强,以电网为核心的综合能源系统应运而生。然而在不确定条件下,当前规划方法仍无法保证各厂商的利益最优,因此本文提出了基于非合作博弈论的电-气系统的协同规划方法。首先,以各能量单元和电、气网公司作为独立的利益团体,以其年净收益最大为优化目标,建立电-气综合系统中风电机组,燃气机组、电转气机组、输电线路和天然气管道的综合非线性规划模型。针对风电、负荷的不确定性,以及经典两阶段鲁棒优化的保守性问题,提出了一种改进的两阶段鲁棒优化方法——期望场景最优,任意场景可行。最后,以修改的IEEE39节点电力系统与比利时20节点天然气系统构造电-气网络,验证了模型及算法的有效性。     

计及电动汽车充放电静态频率特性的负荷频率控制

目前对电动汽车参与电力系统调频的研究,主要集中在电动汽车作为分布式电源参与系统调频,而对电动汽车作为可控负荷参与系统调频的研究较少。但是,电动汽车作为分布式电源和可控负荷对其参与系统调频具有同等重要的作用。基于此,文中计及了电动汽车的充放电静态频率特性模型,在电力系统负荷扰动发生时,实现了对电动汽车充放电的协调控制,使其在分布式电源和可控负荷两个角色间合理转换。在此基础上,建立了计及电动汽车充放电的单区域系统负荷频率控制模型,并将该模型扩展为两区域互联系统。在MATLAB/Simulink中建模并进行仿真分析。算例结果表明,电动汽车作为分布式电源和可控负荷参与系统调频,不仅可以使系统频率调整速度更快,有效减小系统频率偏差,而且能减小传统调频机组的备用容量。     

功率型DC/DC变换器在太阳能发电系统上的应用

将一组几百瓦的光伏电池与电流不连续功率型DC/DC变换器组合成单模块,并将其多块的直流输出端并联后就可得到高功率.再经过一台几千瓦的PWM变频器变为交流电输出,或向电网系统输电或向负载供电,由此构成了光伏功率变换器模块形式的太阳能发电系统.电路经过仿真测试,清楚了它的传输特性,其应用的最大特点是,无论太阳能的发电电压如...     

Market-based multiagent system for reconfiguration of shipboard power systems

On ships, the electric shipboard power system (SPS) supplies electrical power to critical functions such as navigation, communication, emergency systems, and in the case of warships, weapon systems. During ship operation, some parts of the SPS may become unavailable due to damage, fault, or maintenance. For the survivability and reliability of ships, it is desired to make the SPS highly reconfigurable. This paper presents a market-based multiagent system (MAS) for the reconfiguration of radial SPS. Radial SPSs are found on majority of ships. In the proposed MAS, each agent only communicates with its neighbor agents to make the system work in a fully decentralized manner. The MAS is implemented using Java Agent Development Framework (JADE), which is fully implemented in Java and compliant with Foundation of Intelligent Physical Agents (FIPA). An SPS with two generators and four loads is used for testing the proposed MAS. The results show the proposed MAS can successfully reconfigure a radial SPS.     

计及电动汽车的微电网经济调度方法

针对电动汽车接入后微电网的节能减排发电调度问题,提出了结合电动汽车有序充放电控制的微电网多目标经济调度方案。分析电动汽车的行驶特性,建立基于峰谷分时电价的有序充放电负荷模型。以微网发电成本和环境效益的综合最优为目标函数,采用改进遗传算法,根据实时负荷供电需求,动态确定各可控分布式电源出力大小。在Matlab平台上以一个包含风、光、柴油发电机、微型燃气轮机、燃料电池以及电动汽车的小型微电网系统为例进行仿真。仿真结果表明:所提调度方法通过合理引导电动汽车的有序充放电,减少了负荷高峰时段微电网各发电单元的供电负担,以尽量低的发电成本实现良好的环境效益,验证了该优化调度方案的可行性和有效性。     

Modeling and control of distributed generation systems including PEM fuel cell and gas turbine

This paper concentrates on the modeling and control of distributed generation systems including fuel cell and gas turbine. The fuel cell is connected to the power system through a dc/ac converter, which is equipped with both voltage- and power-control loops. The gas turbine is also assumed to be equipped with both voltage-control and generation (or frequency)-control loops. Moreover the gas turbine is modeled using the d–q frame of reference. The interfacing of the gas turbine with the power system is achieved by transforming its equations from the d–q frame of reference to power system frame of reference. A multivariable supplementary fuzzy logic controller is proposed for improving the dynamics of the combined fuel cell and gas turbine system. This fuzzy logic controller is designed using the Matlab Fuzzy Logic Toolbox A distribution test system including a load, a fuel cell and a gas turbine, connected to a power grid is simulated using Matlab/Simulink software package. The dynamics of the combined distributed generation plant are analyzed for the cases of with and without controller. The accuracy of the presented model and the effectiveness of the proposed multivariable supplementary fuzzy controller are deduced from the simulation results.     

Load frequency control of a realistic power system with multi-source power generation

In this paper, load frequency control (LFC) of a realistic power system with multi-source power generation is presented. The single area power system includes dynamics of thermal with reheat turbine, hydro and gas power plants. Appropriate generation rate constraints (GRCs) are considered for the thermal and hydro plants. In practice, access to all the state variables of a system is not possible and also their measurement is costly and difficult. Usually only a reduced number of state variables or linear combinations thereof, are available. To resolve this difficulty, optimal output feedback controller which uses only the output state variables is proposed. The performances of the proposed controller are compared with the full state feedback controller. The action of this proposed controller provides satisfactory balance between frequency overshoot and transient oscillations with zero steady state error in the multi-source power system environment. The effect of regulation parameter (R) on the frequency deviation response is examined. The sensitivity analysis reveals that the proposed controller is quite robust and optimum controller gains once set for nominal condition need not to be changed for ±25% variations in the system parameters and operating load condition from their nominal values. To show the effectiveness of the proposed controller on the actual power system, the LFC of hydro power plants operational in KHOZESTAN (a province in southwest of Iran) has also been presented.     

气电联合系统的双向优化调度

针对气电联合系统双向互联的发展需求,该文提出了含电转气和燃气轮机热电解耦的双向优化调度模型。在电至气与气至电两个方向,分别建立净效益最大电转气容量配置模型与考虑弃风成本、燃气轮机热电解耦的发电总成本最小模型,运用带权极小模函数和遗传算法对电转气设备净效益与系统发电总成本间的矛盾问题进行求解。研究结果表明电转气设备能够提高风电消纳能力并产生较高的净效益,热电解耦提高了燃气轮机发电的灵活性且减小了发电成本。     

垂直轴风力发电系统制动及保护电路设计

为直驱风力发电系统设计了电子制动和保护电路.该发电系统包括垂商轴风轮、永磁同步发电机、整流器、升压变换器、降压变换器及负载.传统的由三相短路系统组成的电子制动装置极易损坏风机转子的桨叶,为此设计了由负温度系数(NTC)电阻组成的电子制动装置,既便宜又安全可靠.实验表明,所设计装置能够有效地保护小型风力发电系统的过压过流状态,并且拓宽了风力发电系统的发电风速范围.     

含分布式电源的配电网供电恢复的多代理方法

针对含分布式电源的配电系统,特别在考虑了由分布式电源和负荷组成微网运行的情况下,建立了以恢复负荷最多、开关操作数最少为目标的供电恢复模型。在提出配网调度中心、微网、分布式电源三者的分层协调控制策略的基础上,应用多代理理论,建立了一个由全系统控制协调代理（CAG）、微网控制代理（MGAG）、分布式电源代理（DGAG）以及母线代理（BAG）组成的多代理系统,在保证配电网辐射状运行、满足配电网电压与电流及馈线容量等约束条件的情况下进行供电恢复。通过分析一个含2个变电站、14条母线和4个分布式电源的配电系统的单重及多重故障供电恢复问题验证了该方法的有效性。