Microgrid Architecture- A Reliability Constrained Approach

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2024年电力技术行业微电网规划

微电网的规划原则和标准
规划原则：确保电力供应的安全、可靠和经济性
规划标准：符合国家相关法律法规和标准要求，同时考虑环境保护和可持续发展
规划目标：提高可再生能源的利用率，降低碳排放，实现能源的优化配置
规划内容：包括微电网的总体布局、设备选型、容量配置、运行控制等方面的规划
微电网的规划布局和设计
全球微电网发展现状
微电网技术不断成熟，应用领域不断扩大
各国政府加大对微电网的投入和支持力度
微电网与可再生能源结合更加紧密，助力绿色能源转型
智能化的微电网管理系统成为发展趋势，提高能源利用效率和供电可靠性
中国微电网发展现状
微电网技术应用范围不断扩大
政策支持力度持续加大
微电网建设投资规模逐年增长
微电网的建设和运营模式
建设模式：独立或与大电网配合建设运营模式：市场化运作或政府主导管理模式：集中或分布式管理盈利模式：通过电力销售或补贴实现盈利
微电网的发展前景
微电网将成为智能电网的重要组成部分，提高能源利用效率和供电可靠性。
随着可再生能源的发展，微电网有望成为分布式能源的重要载体，实现能源的本地化生产和消费。
政策支持和市场驱动将促进微电网技术的推广和应用，带动相关产业的发展。
未来微电网将面临技术、经济、环境等多方面的挑战，需要不断创新和完善。
微电网发展面临的挑战
技术难题：如何提高微电网的稳定性和可靠性
投资成本：如何降低建设和运营成本，实现经济效益
政策法规：如何适应和推动相关政策法规的制定和实施
布局原则：根据区域特点、能源需求和电网结构进行合理布局
设计要素：包括电源、储能、控制和监控等系统的设计

微服务架构在网级电能量数据平台中的应用研究

浙江工业大学学报JOURNAL OF ZHEJIANG UNIVERSITY OF TECHNOLOGY Vol.49No.3 Jun.2021第49卷第3期2021年6月微服务架构在网级电能量数据平台中的应用研究肖勇1，周密1，钱斌】，周积峰2,刘海峰2(1.南方电网科学研究院，广东广州5106632.烟台东方威思顿电气有限公司，山东烟台264001)摘要：使用微服务架构对网级电能量数据平台进行改造升级，提高平台的业务扩展能力。

智能电网建设的推进使得电网用户数和电力计量数据规模大幅增长，现有的单体式架构已经不足以支撑电能量数据平台的多业务扩展。

采用微服务架构技术对平台进行升级改造，架构内各个服务根据并发量和负载率独立制定部署方案，从而实现高可用和负载均衡，同时降低平台各功能的耦合性。

所提架构已在南方电网网级电能量数据平台中得到应用，长时间的稳定运行证明该架构可以提高平台运行稳定性及业务扩展能力。

关键词：高级量测体系；智能电网；微服务；计量自动化系统；电力计量中图分类号:TP302.1文献标志码:A文章编号：1006-4303(2021)03-0258-08Research on application of micro-service architecturein grid-level electrical energy data platformXIAO Yong,ZHOU Mi1,QIAN Bin1,ZHOU Jifeng2,LIU Haifeng2(1.SouthernPowerGridResearchInstitute Guangzhou510663China 2.YanTaiDongFang WisdomElectricsCo.Ltd.Yantai264001China)Abstract:This paper uses micro-service architecture to reform the grid-level electrical energy data plaIformIo improveIhe capabiliIy of daIa processing and business applicaIion exIension.The advanee of smart grid construction has greatly increased the scale of grid user number and electricity metering data size.The existing single-mode architecture is no longer su f icient to support the multi-business extension of electrical energy data platform.The micro-service architecturetechnologyis used to upgrade and transform the platform.Each servicein the architecture is deployed independently based its concurrent volume and load rate"thereby to achievehighavailabilityandloadbalance"meanwhiletoreducethecouplingofvariousfunctions ofthe platform.The architecture proposedin this paper has been appliedin the grid-level electricalenergy data platform of China Southern Power Grid.Thelong-term stablesystem runningprovesthatthisarchitecturecanimprovethestabilityofplatformandbusinessexpansion capabilities.Keywords:advanced metering infrastructure；smart grid；micro-serviee；metering automation system；electricity metering随着智能电表和低压集抄的覆盖面积越来越及数据密度随之增加(现有的电力计量系统已经不广，电网用户的规模和电力计量自动化系统数据项足以支撑未来的业务需求，需要对计量系统进行升收稿日期：2020-06-29基金项目：国家自然科学基金资助项目(1672451)南方电网公司科技项目(ZBKJXM20180157)作者简介：肖勇(1979—)，男，湖南岳阳人，教授级高级工程师，博士，研究方向为电能计量技术、智能电网，E-mail：xiaoyong@。

基于双层优化的微电网系统规划设计方法

第43卷第8期电力系统保护与控制V ol.43 No.8 2015年4月16日Power System Protection and Control Apr. 16, 2015 基于双层优化的微电网系统规划设计方法刘振国1,2，胡亚平1,2，陈炯聪1,2，余南华1,2(1.广东电网有限责任公司电力科学研究院，广东广州 510080；2.广东省智能电网新技术企业重点实验室，广东广州 510080)摘要：规划设计是微电网系统核心技术体系之一。

从分布式电源的综合优化(组合优化、容量优化)和分布式电源间的调度优化两个方面对其展开研究。

根据分布式电源特性，提出了适用于并网型微电网系统和独立型微电网系统的双层优化规划设计模型。

上层优化采用基于NSGA-II的多目标遗传算法计算系统最优配置；下层优化采用混合整数线性规划算法(MILP)计算系统最优运行方案。

运用所建立模型，分别针对并网型和独立型微电网系统作了案例计算, 验证了所提方法的正确性。

关键词：微电网；双层优化；规划设计；NSGA-II；MILPA planning and design method for microgrid based on two-stage optimizationLIU Zhenguo1, 2, HU Yaping1, 2, CHEN Jiongcong1, 2, YU Nanhua1, 2(1. Electric Power Research Institute of Guangdong Power Grid Co., Ltd., Guangzhou 510080, China;2. Guangdong Provincial Key Laboratory of Smart Grid Technology, Guangzhou 510080, China)Abstract: Planning and design for microgrid is one of the key technology. Comprehensive optimization (including combination optimization and capacity optimization) and dispatch optimization for distributed generations (DG) are studied. Based on the characteristics of DGs, a two-stage optimal planning and design model for microgrid is presented, which can apply to both stand-alone microgrid and grid-connected microgrid. For the first stage, multi-objective genetic algorithm based on non-dominated sorting genetic algorithm II (NSGA-II) is used to calculate the optimal system configuration, while the mixed integer linear programming (MILP) is used to deal with the dispatch optimization in the second stage. Using the presented model, a case study is made for stand-alone microgrid and grid-connected microgrid respectively, and the validity of the method is verified.This work is supported by National High-technology R & D Program of china (863 Program) (No. 2012AA050212).Key words: microgrid; two-stage optimization; planning and design; NSGA-II; MILP中图分类号：TM715 文献标识码：A 文章编号：1674-3415(2015)08-0124-100 引言微电网系统可将多种类型的分布式发电单元组合在一起，有效发挥单一能源系统的优点，实现多种能源互补，提高整个微电网系统的效率、能源利用率和供电可靠性。

直流微电网改进虚拟直流电机控制策略

第54卷第12期2020年12月电力电子技术Power ElectronicsVol.54,No.12December2020直流微电网改进虚拟直流电机控制策略支娜，丁有国，赵佳宝(西安理工大学，自动化学院，陕西西安710048)摘要：针对已有虚拟直流电机(VDCM)控制增大直流母线电压稳态误差的问题，提出一种改进VDCM控制策略。

通过分析传统VDCM模型中阻尼系数对母线电压稳态误差及储能变换器控制系统阻尼特性的影响规律，提出一种去掉阻尼系数环节的改进VDCM控制策略。

该控制策略既能提高直流变换器的阻尼特性，又能消除阻尼系数对直流母线电压稳态误差的影响，提升直流母线电压的稳定性。

仿真和实验结果表明了改进VDCM 控制策略的正确性和优越性。

关键词：直流微电网；虚拟直流电机；阻尼系数中图分类号:TN819.1文献标识码:A文章编号:1000-100X(2020)12-0093-03DC Microgrid Improved Virtual Direct Current Motor Control StrategyZHI Na,DING You-guo,ZHAO Jia-bao(Xi1an University of Technology,Xi'an710048,China)Abstract:Aiming at the problem that the existing virtual direct current machine(VDCM)control increases the direct current bus voltage steady-state error,an improved VDCM control strategy is proposed.By analyzing the influence of the damping coefficient on the busbar voltage steady-state error and the damping characteristics of the energy storage converter control system in the traditional VDCM model,an improved VDCM control strategy is proposed to remove the damping coefficient.This control strategy can not only improve the damping characteristics of the direct current converter,but also eliminate the influence of the damping coefficient on the direct current bus voltage steady-state er・ror,and improve the stability of the direct current bus voltage.Simulation and experimental results show the correctness and superiority of the improved VDCM control strategy.Keywords:direct current microgrid；virtual direct current machine；damping coefficientFoundation Project:Supported by General Program of National Natural Science Foundation of China(No.51877175)；Natural Science Foundation of Shaanxi Province(No.201刀M5100)1引言VDCM控制策略⑴能够提高直流微电网控制系统的惯性，抑制由直流微电网内功率波动引起的母线电压波动，从而得到广泛的应用PT。

考虑构网型和跟网型变流器的孤岛微电网小信号稳定性分析

考虑构网型和跟网型变流器的孤岛微电网小信号稳定性分析张心怡;杨波
【期刊名称】《综合智慧能源》
【年(卷),期】2024(46)2
【摘要】由电力电子设备主导的孤岛微电网面临系统惯量小、无频率支持而导致的稳定性问题,恒功率负荷的渗透也加剧了系统的失稳风险。

研究了由构网型变流器和跟网型变流器为主导的,计及恒功率负荷的孤岛微电网稳定性。

首先,建立了孤岛微电网系统的全阶小信号模型,通过特征值分析法研究了构网型变流器控制中下垂系数对稳定性的影响并得到了下垂系数的数值上界;其次,通过参与因子法揭示了系统参数和控制参数对小信号稳定性的影响;最后,在Matlab Simulink中建立了该孤岛微电网的开关模型,仿真验证了小信号分析结果的准确性。

【总页数】7页(P12-18)
【作者】张心怡;杨波
【作者单位】德国柏林工业大学电气工程与计算机科学学院;东北大学信息科学与工程学院
【正文语种】中文
【中图分类】TM712
【相关文献】
1.离网型微电网主电源储能逆变器的小信号建模及稳定性分析
2.考虑构网型与跟网型逆变器交互的孤岛微电网小信号稳定性分析
3.构网型与跟网型变流器主导孤岛
微网阻抗稳定性分析及提升策略4.构网型变流器并网系统在强弱电网下的分岔分析5.光储系统电网侧故障下VSC变流器的跟网-构网型控制方法
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enphase 微逆拓扑

enphase 微逆拓扑Enphase 微逆拓扑是一种先进的太阳能逆变器拓扑结构，它采用了微电网技术，能够将太阳能电池板产生的直流电转换为交流电，并将其注入到电网中。

这种拓扑结构具有许多优点，使其成为目前市场上最受欢迎的逆变器之一。

首先，Enphase 微逆拓扑具有高效率。

传统的太阳能逆变器通常采用串联式结构，这意味着整个系统的效率受到最低效率组件的限制。

然而，Enphase 微逆拓扑采用并联式结构，每个太阳能电池板都有一个独立的微逆器进行转换。

这种设计使得系统可以更好地利用每个组件的最大功率点，并提高整个系统的效率。

其次，Enphase 微逆拓扑具有模块化设计。

每个微逆器都是独立工作的单元，可以根据实际需求进行灵活配置和安装。

这种模块化设计不仅简化了系统的维护和管理，还提高了系统的可靠性和可扩展性。

此外，Enphase 微逆拓扑还具有智能监控和管理功能。

每个微逆器都配备了智能电子设备，可以实时监测太阳能电池板的工作状态和电网的负载情况。

通过与云端平台的连接，用户可以随时随地监控和管理整个太阳能发电系统，提高系统的运行效率和可靠性。

最后，Enphase 微逆拓扑还具有高度安全性。

每个微逆器都配备了多重保护机制，包括过压、过流、过温等保护功能，可以有效防止系统故障和事故发生。

此外，Enphase 微逆拓扑还采用了双向通信技术，可以实现与电网的双向交互，并确保系统与电网的稳定连接。

总之，Enphase 微逆拓扑是一种先进的太阳能逆变器拓扑结构，具有高效率、模块化设计、智能监控和管理功能以及高度安全性等优点。

它不仅可以提高太阳能发电系统的效率和可靠性，还可以为用户提供更好的使用体验。

因此，在未来的太阳能市场中，Enphase 微逆拓扑有着广阔的应用前景。

CERTS Microgrid Laboratory Test Bed

Abstract--. CERTS Microgrid concept captures the emerging potential of distributed generation using a system approach. CERTS views generation and associated loads as a subsystem or a “microgrid”. The sources can operate in parallel to the grid or can operate in island, providing UPS services. The system can disconnect from the utility during large events (i.e. faults, voltage collapses), but may also intentionally disconnect when the quality of power from the grid falls below certain standards. CERTS Microgrid concepts were demonstrated at a full-scale test bed built near Columbus, Ohio and operated by American Electric Power. The testing fully confirmed earlier research that had been conducted initially through analytical simulations, then through laboratory emulations, and finally through factory acceptance testing of individual microgrid components. The islanding and resynchronization method met all Institute of Electrical and Electronics Engineers Standard 1547 and power quality requirements. The electrical protection system was able to distinguish between normal and faulted operation. The controls were found to be robust under all conditions, including difficult motor starts and high impedance faults.Keywords:CHP, UPS, distributed generation, intentional islanding, inverters, microgrid, CERTS, power vs. frequency droop, voltage droop.I. I NTRODUCTIONERTS Microgrid concepts where first formulated in 1998 as a cluster of micro-generators and storage with the ability to separate and isolate itself from the utility seamlessly with little or no disruption to the loads [1]. Key concepts include controllers based on local terminal quantities only, fast load tracking and the use of frequency droop methods to insure load sharing between microsources. This work was later formalized in a white paper and a US patent [2,3].The authors are grateful for the support and technical direction provided by the Public Interest Energy Research (PIER), Energy Commission staff Bernard Treanton, and former staff Jose Palomo and Mark Rawson.R. H. Lasseter is with the University of Wisconsin, Madison, WI 68902 USA (e-mail: lasseter@).J. H. Eto is with Lawrence Berkeley National Laboratory, Berkeley, CA 94720 USA (e-mail JHEto@).Ben Schenkman and John Stevens are with Sandia National Laboratories, Albuquerque, NM 87185 USA. (e-mail blschen@)Harry Volkommer and Dave Klapp are with American Electric Power, Dolan Technology Center, Columbus, OH 43215 USA (e-mail htvollkommer@; daklapp@)Ed Linton and Hector Hurtado are with Northern Power Systems, Waitsfield, VT 05673, USA (e-mail elinton@; HHurtado@)Jean Roy is with Tecogen, Inc., Waltham, MA 02451 USA (e-mail Jean.Roy@) The objective of the CERTS Microgrid Laboratory Test Bed project was to demonstrate the ease of integrating small energy sources into a microgrid. The project accomplished this objective by developing and demonstrating three advanced techniques, collectively referred to as the CERTS Microgrid concept, that significantly reduce the level of custom field engineering needed to operate microgrids consisting of small generating sources. The techniques comprising the CERTS Microgrid concept are: 1) a method for effecting automatic and seamless transitions between grid-connected and islanded modes of operation; 2) an approach to electrical protection within the microgrid that does not depend on high fault currents; and 3) a method for microgrid control that achieves voltage and frequency stability under both grid and islanded conditions without requiring high-speed communications.II. M ICROGRID C ONCEPTCERTS Microgrid control is designed to facilitate an intelligent network of autonomous units. The concept has three critical components, the static switch, the microsources and loads [4]. The static switch has the ability to autonomously island the microgrid from disturbances such as faults, IEEE 1547 events or power quality events. After islanding, the reconnection of the microgrid is achieved autonomously after the tripping event is no longer present. Each microsource can seamlessly balance the power on the islanded microgrid using a power vs. frequency droop controller. If there is inadequate generation the frequency will droop below the normal operating range signaling the non-critical loads to shed. The coordination between sources and loads is through frequency The voltage controller at each source provides local stability. Without local voltage control, systems with high penetrations of DG could experience voltage and/or reactive power oscillations. Voltage control must also insure that there are no large circulating reactive currents between sources. This requires a voltage vs. reactive power droop controller so that, as the reactive power generated by the source becomes more capacitive, the local voltage set point is reduced. Conversely, as reactive power becomes more inductive, the voltage set point is increased. The CERTS Microgrid has no “master” controller or source. Each source is connected in a peer-to-peer fashion with a localized control scheme implemented for each component. This arrangement increases the reliability of the system in comparison to having a master-slave or centralized control scheme. In the case of master-slave controller architecture theCERTS Microgrid Laboratory Test Bed R. H. Lasseter, Fellow, IEEE, J. H. Eto, Member, IEEE, B. Schenkman, J. Stevens, Member, IEEE, H. Volkmmer, Member, IEEE, D. Klapp, E. Linton, H. Hurtado, and J. RoyCWork was supported, in part, by the U.S. Department of Energy under ContractNo. DE-AC02-05CH11231.failure of the master controller could compromise the operation of the whole system. The CERTS Testbed uses a central communication system to dispatch DG set points as needed to improve overall system operation. However this communication network is not used for the dynamic operation of the microgrid. This plug and play approach allows us to expand the microgrid to meet the requirements of the site without extensive re-engineering. This implies that the microgrid can continue operating with loss of any component or generator. With one additional source, (N+1), we can insure complete functionality with the loss of any source. Plug-and-play implies that a unit can be placed at any point on the electrical system without re-engineering the controls thereby reducing the chance for engineering errors. The plug-and-play model facilitates placing generators near the heat loads thereby allowing more effective use of waste heat without complex heat distribution systems such as steam and chilled water pipes.III. CERTS/AEP M ICROGRID T EST-B EDThe test bed is shown in Figure 1. There are three feeders (A, B and C) with loads and three microsources. Two microsources are on Feeder-A, (A-1 and A-2) with the third, B-1, on Feeder-B. Feeder-A uses a four-wire cable with a common ground point. The cable between A-1 and A-2 is 100yds, providing impedance to verify the plug and play feature and local stability. The second feeder (B) with a single load and source is a three-wire system with an isolation transformer.Feeders-A and B can be islanded from the utility using a static switch. The static switch hardware consists of back-to-back thyristors with local implementation of the CERTS Microgrid islanding and re-synchronization procedures. The four load banks, Load-3 through Load-6 can be remotely controlled from 0-90 kW and 0-45 kVar. Each load bank also has remote fault loads which range from bolted faults to high impedance faults (60 kW and 83 kW). Other loads include an induction motor 0-20 HP.The other equipment includes: protection relays, shunt trip breakers and a complete digital acquisition system. The digital acquisition system includes twelve 7650 ION meters providing detailed voltage and current waveforms for each phase conductor, including the neutral.MicrosourceAt the AEP site the prime mover is a 7.4 liter, naturally aspirated V-8, specially modified for natural gas [5]. The block and exhaust manifolds are liquid cooled. Typical coolant temperatures supplied to the host facility are in the range of 185/235 F when exhaust heat recovery is used for CHP applications. Heat is recovered from an external oil cooler as well. The fuel supply, natural gas at low pressure (18 inches of water column), is combined with air in a venturi mixer upstream of the throttle and intake manifold. To maintain the precise air/fuel ratio control required for the catalyst emissions system, a closed loop feedback control system is utilized incorporating twin oxygen sensors in the exhaust system.The generator is liquid-cooled permanent magnet type designed specifically to match the speed and power curve of the engine. Voltage and power are proportional to RPM. The cooling fluid can be combined with the main heat recovery system in some cases where temperatures are relatively low. Each microsource can seamlessly balance the loads when the microgrid islands using a power vs. frequency droop controller. Stability is insured using a voltage vs. reactive power droop controller to regulate AC voltage. The basic source consist of a prime mover and a power conditioning system which together provide the necessary power and voltage control required for operation of the CERTS microgridThe power conditioning system is shown in Figure 2. ThereFigure 1. CERTS/AEP Microgrid Test SiteFigure 2. Power condition systemare three fundamental stages: an AC/DC diode rectifier bridge with voltage boost, DC storage and a DC/AC inverter. Diode rectifier and boost has two tasks: the first is to convert the AC waveform into a DC voltage and the second is to increase the DC voltage to a higher level so that the inverter has extra room to be able to synthesize a voltage larger than nominal. When the inverter injects reactive power to regulate voltage at the feeder, the magnitude of the voltage at the inverter can exceed 1 PU. To make sure that the inverter does not operate in the over modulation region, a larger DC bus voltage is used.The DC storage can provide short bursts of power, drawingfrom an internal supply of stored energy. This insures that the inverter can provide the power required by the microgrid independent of the rate of the prime mover. Subsequent to a burst and settling to steady state, a charger ensures that the energy is slowly replenished into the batteries. The inverter is a power electronic block composed of a matrix of solid state devices with high switching frequency that can convert a DC voltage into an stiff AC voltage. For these tests storage was not used since the prime mover could provideine needed energy to the inverters.Autonomous ControllerIntegration of large numbers of microsources into a Microgrid is not possible with basic unity power factor controls. Voltage regulation is necessary for local reliability and stability. Without local voltage control, systems with high penetrations of microsources could experience voltage and/or reactive power oscillations.Voltage control must also insure that there are no large circulating reactive currents between sources. With small errors in voltage set points, the circulating current can exceed the ratings of the microsources.This situation requires a voltage vs. reactive power droop controller so that, as the reactive power, Q, generated by the microsource become more capacitive, the local voltage set point is reduced. Conversely, as Q becomes more inductive, the voltage set point is increased, [6].Each microsource uses a power vs. frequency droop controller to insure power balance in an islanded state. There are two possible power droop controllers. One is unit power control, which controls the power being injected by the microsource. The other is zone flow power controller which regulates the power in a feeder, for example the flow into Feeder-A in Figure 1. When regulating unit power, each source has a constant negative slope droop on the P vs. frequency plane as shown in Figure 3. In zone control each source has a positive slope on P vs. frequency plane. The fixed slope is the same magnitude used in unit power control, but with a reversed sign. When regulating unit power the relative location of loads and source is irrelevant but when regulating zone flow these factors becomes important. Power flow into the feeder is positive while power from the feeder is negative [6]. When the microgrid is connected to the grid, loads receive power both from the grid and from local microsources, depending on the customer’s situation. If the grid power is lost because of IEEE 1547 events, voltage droops, faults, blackouts, etc., the Microgrid can autonomously transfer to island operation.Figure 3 shows power vs. frequency droop for unit power control. The slope is chosen by allowing the frequency to drop by a given amount as the power spans from zero to Pmax, for the AEP test site this was 5 Hz. Figure 3 also shows the power set-points Po1 and Po2 for two units. This is the amount of power injected by each source when connected to the grid, at system frequency.If the system transfers to island when importing from the grid, the generation needs to increase power to balance power in the island. The new operating point will be at a frequency that is lower than the nominal value. In this case both sources have increased their power output, with unit 2 reaching its maximum power point. If the system transfers to island when exporting power to the grid, then the new frequency will be higher, corresponding to a lower power output from the sources with unit 1 at its zero power point.The characteristics shown in Figure 3 are steady state characteristics. The slope is fixed over the normal operating power range. The limits are enforced by the controller. These curves represent the locus of the steady state operation, but during dynamics the trajectory will deviate from these characteristics.The dynamics of this droop characteristic is shown in Figure 4. The figure shows the response of two sources during an islanding event. The data is from Test 8.3 taken on 21 February 2008 at 11:45 AM at the microgrid laboratory test bed, [7]. Figure 4a traces are measured at unit A-1, see figure 1. Before islanding at time = 0.0 seconds both sources are connected to AEP. The real power output of A-1 is 5kW and reactive power (capacitive) is close to 9 kVAr. The three phase currents are from the Y side of the source are shown in the middle plot and the lower plot is voltage at the point of connection to feeder-A.Figure 3. Steady state power vs. frequency droopFigure 4b traces are measured at unit A-2. Before islanding the real power output of A-2 is 55kW and reactive power (capacitive) is close to 5 kVAR.When connected to the grid the microgrid is importing 32 kW of power from the utility. After islanding the units need to compensate for lost power. A-2 overshoots its steady state maximum for less than 200 milliseconds peaking at 70 kW but then the controls backs off the generation while unit A-1 increases its output to meet its share of the loads. The new steady state operating point for A-1 is 29 kW and A-2 is 60 kW. Note that the reactive output is greatly reduced. Voltage magnitudes are unchanged for both sources demonstrating the stiffness of the inverter voltages. The current traces are from the inverters.IV. F IELD T ESTSTen different classes of test were performed [7]. The first five are focused on commissioning of the test site. Tests sequence 6.0 relates to the static switch, 7.0 the protection system, 8.0 reduced system tests, 9.0 power flow control and 10.0 difficult loads [8]. In this paper focuses on the last three tests: reduced system tests, power flow control and difficult loads. These tests illustrate the performance of the sources and their autonomous controllers. This set of tests started early in 2008 resulting in hundreds of successful tests taken over a twelve-month period. Plots are labeled with test number and time the data was taken. Reduced System TestsReduced system tests were designed to ensure that the microsources’ autonomous controllers were working as designed. This includes unit control, zone control and mixed controls, in conjunction with limit controls and synchronized closing of the static switch. These tests were based on replicating tests that had previously been conducted during the factory acceptance testing of the inverters. The performance goal was to observe the microsources’ response to different conditions. Thirteen separate tests were conducted and all performed as designed.Test 8.1 verifies islanded microsource transitions during step load and changes in voltage set points ranging from +5% to -5%. Test 8.2 is designed to test zero power limits during islanding. Before islanding A-1 was operating at 5 kW and A-2 at 55 kW exporting 20 kW. After islanding A-1 was driven its zero power limit and A-2 autonomously reduced its output to 40 kW. Test 8.3 is designed to check the maximum power limit on A-2 during an islanding event. The results of this test are shown in Figures 4. Test 8.4 illustrates the dynamic of the microgrid to loss of load in one phase. The test is also discussed in detail in this paper with dynamic traces shown in Figure 5. Test 8.5 verifies the load tracking ability for a mixed mode control system while connected to the grid. Microsource A-1 is in zone mode controlling the power flow feeder-A, Figure 1. A-2 was in unit control and remains constant during load changes. The event is a load increase the load in Feeder-A from 70 kW to 120 kW. For this event A-1 increased its output by 50kW insuring that the feeder flow remained constant. Zone control provides an autonomousFigure 4a. Dynamic response of unit A-1 Figure 4b. Dynamic response of unit A-2method for isolating the utility from interment loads orrenewable source dynamics. Test 8.6 verifies the load tracking behavior of a mixed mode control system when the zone controlled microsource reaches its limits. During a load step change A1 is driven to its maximum, which causes an automatic reset of the zone power set point. Test 8.7 is a mixed mode testing while grid connected. It is designed to test a zone power level much larger that the controlling source maximum power level. The intent was to insure the PU system in the controller was correctly normalized. Test 8.8 is the first mixed mode test of islanding. The zone is Feeder-A. In this test the zone flow goes to zero while A-1 increase is 4 kW and A-2 is 46 kW. Operation is as expected. Test 8.9 tests mixed mode islanding at maximum power limits. A-1 is in Zone operation mode and A-2 in Unit operation mode. Islanding forces both A-1 and A-2 to their maximum. The test successfully demonstrated this operation with a new steady state frequency of 59.5 Hz. If the load had been larger the frequency would continue to drop providing a signal for a load trip. Test 8.10 is an islanding test with Feeder A and B in zone control. In this test A-1 and B-1 are operating and the microgrid is importing 50 kW from the utility. After island B-1 output is increased exporting 10 kW to Feeder-A to help meet the load on this feeder. Test 8.11 is another islanding test with Feeder A and B in zone control. In this case Feeder-A is exporting 25 kW of which 10 kW flows to Feeder-C outside the static switch. Tests 8.12 and 8.13 are designed to test the black-start capacity [7]. This paper looks at three of these test in more detail; 8.3, 8.4 and 8.10. Test 8.3 was discussed in the last section.Figure 5 is data from test 8.4. This test illustrates the dynamic of the microgrid to loss of load in phase-a. The initial system is operating in island mode with source A-1 at 43 kW and A-2 at 13 kW. Generator B-1 is off. The only load is load-3 drawing approximately 56 kW. The top plot shows the load currents in the three phases and neutral conductors. Prior to the event the phase currents are balanced with no neutral current. At time=0 phase-a load is disconnected resulting in zero current in phase-a and non-zero current in the neutral. The power response of A-1 and A-2 are shown in the second plot indicating the load is reduced by one third. A-1 is operating near 4 kW and A-2 is 34 kW. These power changes are a result of the autonomous power vs. frequency controller on each source. The line-to-line voltages at each source show no transients. The currents at A-1 and A-2 are shown in the lower two plots. Phase-a current for A-2 is reduced while A-1 current has a phase shift indicating a power flow into the transformer at the source.Figure 6 is data from test 8.10. This test is focused on islanding while operating in a zone control mode. The zone control configuration, regulates the power flowing into feeders A and B, See Figure 1. Load changes in Feeder-A are supplied by source A-1 showing a constant feeder load. Likewise load changes in Feeder-B are supplied by source B-1. In this mode of operation, the microgrid becomes a true dispatchable load as seen from the utility, allowing for demand-side management arrangements. The initial system isTimeFigure 5. Response to unbalanced loadFigure 6. Islanding dynamics while in zone modeoperating grid connected with flow in Feeder-A set at 36 kW and Feeder-B at 14 kW. The load on Feeder-A is 36 kW implying that source A-1 is providing near zero power. Feeder-B load is 47 kW with source B-1 providing 37 kW. Generator A-2 is off. The top plot shows the real power in the static switch, Feeder-A and Feeder-B. At time equal zero the static switch opens indicated by the power through the static switch going to zero. The power flowing into Feeder-A is 15 kW which is provided by Feeder-B with a negative power flow of 15 kW. After islanding A-1 had a measured output of 21 kW and B-1 was operating at 62 kW.The second plot shows the voltage and current related to source A-1. Recall that before opening of the static switch A-1 was not providing any real power. This plot indicates that A-1 is providing close to 60 amp of reactive current to support the voltage. The third plot shows the current and voltages for B-1. Note that the voltage at A-1 and B-1 shows no transients during loss of power from the grid.Power Flow ControlThe fourth set of tests (Section 9 of the test plan) demonstrates the flexibility of the microgrid both grid connected and islanded for different loads, power flows and impact on the utility. The tests included addition of an inductor to weaken grid. Three sets of tests were conducted [9].Tests 9.1 to 9.3 verified and documented power flow and microgrid frequency changes when transitioning from utility connected to an islanded mode of operation. In each test, 9.1 to 9.3, a series of tests was performed that vary in the amount of load that is applied to the microgrid in a weak grid scenario along with the power settings of each microsource. The difference between tests is the control mode for each microsource. In Test 9.1, all the microsources were set for unit control mode. In test, 9.2, all the microsources are in zone control mode. Test 9.3 mixed the unit and zone control modes of the microsources during each test. All three tests, 9.1 to 9.3, went as expected demonstrating the variety of control and power flow options available through the CERTS concept.Figure 7 is data from test 9.1.7. This test is focused on islanding with three sources operating in unit control mode, see Figure 1. All loads (3, 4 and 5) are 37kW in real power and 20 kVAR reactive power. The grid provides 22 kW with A-1, A-2 and B-1 providing the remaining 89 kW. The top plot in Figure 7 shows the power imported from the grid and the power provided by each source. The islanding event is indicated at time equal zero by the loss of grid power due to the opening of the static switch. The three other plots are each the current provided by phase-a of the three sources. The voltage at each source is similar to those shown in Figure 6. The power sharing among the three sources in response to loss of power from the grid is inherent in the CERTS concept. Difficult LoadsThe final set of testing covered in this paper explores the operation limits of the microgrid. Two primary sets of tests were conducted under weak grid conditions; the first involved induction motor starting loads under balanced and unbalanced load conditions; the second involved only unbalanced loads [10].Figure 8 is data from test 10.2.17. This test illustrates the response of an islanded microgrid to starting of an induction motor. The initial system is operating in island mode with a single source A-1 at 20 kW. Generators A-1 and B-1 are off. The only load is load-3 drawing approximately 20 kW with aFigure 7. Response of three sources to an islanding eventFigure 8. Response to starting of an induction machine0.9power factor. The top two plots shows the voltages and currents at source A-1. The bottom plot contains the real and reactive powers provided by A-1 to the loads. It is clearly seen that this event draws significant reactive power from A-1 for 0.7 seconds. The voltage distortion is also significant. It is also clear that as soon as the motor was operating the islanded microgrid recovered to normal operation. This motor was started with maximum load. If this load had soft start features the impact on the microgrid would have been greatly reduced.Another difficult load event was provided by a reverse power test, Test 6.1.2 based on IEEE 1547 (loss of utility source). In this test one source was operating with a 3 phase 500kW load on the utility side of the static switch. The event was to open the feeder from the utility which would place the full 500kW on a single source A-1. The static switch was to open in one cycle but it did not due to an error in the tripping controls of the static switch. This resulted in the 500 kW load across A-1 for 12 cycles. The traces for this event are shown in Figure 9. The solid curve is the current provided by A-1 while the dashed curve is the voltage at A-1’s transformer. It is clear that the 500 kW load was imposed at time equal zero. The current shoots up to 600 amps, which is close to four times the rated current. Simultaneously the voltage is reduced approximately 50%. After 12 cycles the static switch opens and the large load is removed with the voltage returning to normal operation. This is achieved through an inter current loop which smoothly reduces the output voltage holding the output current to four per unit. This event demonstrates the robustness and stability of the microgrid design.V. C ONCLUSIONSThe objective of the CERTS Microgrid Laboratory Test Bed project was to demonstrate the ease of integrating distributed energy sources into a microgrid. This includes autonomous sources with peer-to-peer and plug-and-play functionality. The tests demonstrated stable behavior at critical operations points, the flexibility of control modes and the ability to island and re-connect to the grid in an autonomous manner. All tests performed as expected and demonstrated a high level of robustness. Continued work includes advancing CERTS Microgrid concepts to a full range of Distributed Energy Resources including renewables. At the University-of-Wisconsin’s Microgrid Laboratory successful demonstrationof a microgrid with synchronous generation and storage has been completed, [11, 12]. Other issues include advanced protection design, reduction of cost, meshed microgrids and frequency based load shedding.VI. A CKNOWLEDGMENTThis work was funded by the Energy System Integration Division of the Public Interest Energy Research Program of the California Energy Commission under Contract No. 500-02-004, Commission Work Authorization No: MR-041VII. R EFERENCES[1] Lasseter, R. H.,“Control of Distributed Resources,” Bulk Power Systemand Controls IV Conference, August 24-28, 1998, Santorini, Greece. [2] Lasseter, R. H., A. Akhil, C. Marnay, J Stephens, J Dagle, RGuttromson, A. Meliopoulous, R Yinger, and J. Eto, “The CERTS Microgrid Concept,” White paper for Transmission ReliabilityProgram, Office of Power Technologies, U.S. Department of Energy, April 2002. Available: /certs-der-pubs.html [3] Lasseter, R.H., P. Piagi, “Control of small distributed energyresources,” US Patent 7 116 010, Oct. 3, 2006.[4] Lasseter, R.H., P. Piagi, “Microgrid: A Conceptual Solution,”PESC’04 Aachen, Germany 20-25 June 2004[5] Panora, R., J. Gerhrt, P. Piagi, “Design and Testing of an Inverter-Based CHP Module for Special Application in a Microgrid,” IEEE PES General Meeting, 24-28 June 2007, Tampa, FL[6] Piagi, P., R.H. Lasseter, “Autonomous Control of Microgrids,” IEEEPES Meeting, Montreal, June 2006.Available:/CERTS_P_DER.html[7] Eto, Joseph, Robert Lasseter, Ben Schenkman, John Stevens, HarryVolkommer, Dave Klapp, Ed Linton, Hector Hurtado, Jean Roy, Nancy Jo Lewis, “CERTS Microgrid Laboratory Test Bed Report:Appendix K,” /CERTS_P_DER.html[8] Klapp, D., H. Vollkommer, “Application of an Intelligent Static Switchto the Point of Common Coupling to Satisfy IEEE 1547 Compliance,” IEEE PES General Meeting, 24-28 June 2007, Tampa, FL.[9] Eto, Joseph, Robert Lasseter, Ben Schenkman, John Stevens, HarryVolkommer, Dave Klapp, Ed Linton, Hector Hurtado, Jean Roy, Nancy Jo Lewis, “CERTS Microgrid Laboratory Test Bed Report: Appendix L”[10] Eto, Joseph, Robert Lasseter, Ben Schenkman, John Stevens, HarryVolkommer, Dave Klapp, Ed Linton, Hector Hurtado, Jean Roy, Nancy Jo Lewis, “CERTS Microgrid Laboratory Test Bed Report:Appendix M.”[11] Krishnamurthy, S, T. Jahns and R.H. Lasseter ,”The Operation ofDiesel Genset in a CERTS Microgrid,” PES 2008, Chicago.[12] Lasseter, R.H, M. Erickson, “Microgrid Dynamics with Storage,”/CERTS_P_DER.htmlVIII. B IOGRAPHIESRobert H. Lasseter (F’1992) received the Ph.D. in Physics from the University of Pennsylvania, Philadelphia in 1971. He was a Consulting Engineer at General Electric Co. until he joined the University of Wisconsin-Madison in 1980. His research interests focus on the application of power electronics to utility systems. This work includes microgrids, FACTS controllers, use of power electronics in distribution systems and harmonic interactions in power electronic circuits. Professor Lasseter is a Life Fellow of IEEE, past chair of IEEE Working Group on Distributed Resources and IEEE distinguished lecturer in distributed resources.Joseph H Eto (M’1987) is a staff scientist in the Environmental Energy Technologies Division of the Lawrence Berkeley National Laboratory. He has authored over 150 publications on electricity policy, electricity reliability, transmission planning, cost-allocation, demand response, distributed energyTime SecondsFigure 9. Response to 500 kW step load。

微电网中分布式能源的协调调度与优化方法研究

微电网中分布式能源的协调调度与优化方法研究微电网是一种基于分散式能源（distributed energy resources，DERs）的小规模电力系统，其具有可再生能源高渗透、低碳排放等优势。

然而，微电网中存在着DERs间的协调调度与优化问题。

本文将从微电网的背景出发，介绍微电网中分布式能源的协调调度与优化方法的研究。

一、微电网背景微电网是指由多种不同能源资源组成的小规模电力系统，能够以可靠、经济的方式为用户提供电能。

相比传统电网，微电网更加灵活、可持续、可靠。

它可以以可再生能源为主导，降低对传统能源的依赖，并且可接入到传统电网中实现互补运行。

二、分布式能源的挑战与优化微电网中的分布式能源包括太阳能光伏发电、风力发电、储能系统等。

这些分布式能源的可再生特性要求协调调度与优化，以最大限度地利用可再生能源、提高电网供电质量和稳定性。

1. 供需平衡优化分布式能源的产生是不确定的，而电力用户的需求是变化的。

因此，如何在微电网中实现供需平衡成为一个关键问题。

传统的供电方式往往是通过中心调度来实现，而在微电网中，则需要通过协调DERs的输出来满足用户的需求。

因此，供需平衡的优化方法主要包括基于经济的调度策略和基于能源流动的调度策略。

2. 能源管理与调度策略优化能源管理与调度策略是微电网中的一个基础问题。

在微电网中，各种DERs的输出和负载的需求是分散的，因此如何实现有效地能源管理和调度策略成为一个难题。

目前，常见的优化方法包括基于模型预测控制、遗传算法、人工智能等。

3. 微电网的网优化问题微电网的网优化问题主要包括输电网的规划与优化、变电站的选择与配置、微电网系统的安全性与稳定性等。

需要考虑的因素很多，包括电力互联、负荷调度、电力传输等。

对于这些问题，需要综合考虑微电网的经济性、可靠性和稳定性，以提高微电网的运行效率和供电质量。

三、优化方法研究进展目前，微电网中分布式能源的协调调度与优化方法正在得到广泛的研究与应用。

微电网组网优化设计

随着对微电网技术的研究、试点项目的开展，微电网的组网技术受到越来越多的关注。根据分布式电源发电特征和用电（尤其是低压用电）特征，文献［4 － 6］分别提出直流微电网结构、交流微电网结构、交直流混合微电网等组网方式，本文通过对这些组网方式优缺点的分析，
非重要负荷图7采用固态开关的微电网结构固态开关具有快速关断支路的特性由于微电网在并网运行时常常与配电网有较大的功率交换尤其是分布式电源较小的微电网系统其功率来源主要依靠于配电网当微电网从并网无缝切换到离网时将存在一个较大的功率差额因此固态开关的安装位置应该保证离网后在很短的时间内重要负荷和分布式电源侧的功率能够快速平衡
微电网能够并网运行，也能离网运行，在外部电网发生短路、电压跌落、频率异常等故障时，为了保证微电网内部重要负荷不受影响应快速断开微电网入口断路器，使微电网无缝切换到离网运行。目前常 NORTH CHINA ELECTRIC POWER
在直流微电网中，系统中的分布式电源、储能、直流负荷均通过电力电子装置直接连在直流母线上，直流微电网通过逆变器连接到外部交流
No． 1 2012
华北电力技术 NORTH CHINA ELECTRIC POWER
33
电网，而交流负荷则需要通过交流转直流后接在直流母线上。这种组网方式可以实现向不同电压等级的交流、直流负荷提供电能［3］。直流微电网的结构如图 1 所示［4］。
图 7 采用固态开关的微电网结构
固态开关具有快速关断支路的特性，由于微电网在并网运行时常常与配电网有较大的功率交换，尤其是分布式电源较小的微电网系统其功率来源主要依靠于配电网，当微电网从并网无缝切换到离网时，将存在一个较大的功率差额，因此固态开关的安装位置应该保证离网后在很短的时间内重要负荷和分布式电源侧的功率能够快速平衡。在微电网离网后储能或具有自调节能力的微燃气轮机等承担整个离网系统频率和电压的稳定，因此其容量的配置需要充分考虑重要负荷的大小、出力、受天气因素影响的分布式电源的最大可能出力和最小可能出力大小等因数。

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MicrogridArchitecture:AReliabilityConstrainedApproach

ShashiB.Patra,StudentMemberKlipschSchoolofElectricalandComputerEngineeringNewMexicoStateUniversityLasCruces,NM88003Email:patra@nmsu.eduJoydeepMitra,SeniorMemberKlipschSchoolofElectricalandComputerEngineeringNewMexicoStateUniversityLasCruces,NM88003Email:jmitra@nmsu.eduSatishJ.Ranade,SeniorMemberKlipschSchoolofElectricalandComputerEngineeringNewMexicoStateUniversityLasCruces,NM88003Email:sranade@nmsu.edu

Abstract—Today’spowerdeliveryinfrastructureisoperatingunderextremestress.Thelastfewdecadeshaveseenminimalin-vestmentininfrastructure,andlittlehasbeendonetopreparetheageingequipmentforincreasingloadgrowthsandthedemandsofopenaccess.Consequently,thedeploymentofDistributedEnergyResources(DER)isbecominganincreasinglyattractivealternativetotheexpensiveandtimeconsumingprocessesofupgradingandaugmentingthetransmissionanddistributionsystems.DERsaresmall,modularsources(generationorstorage)ofenergywhichareoftenmoreefﬁcientandcontrollablethantraditionalpowerplants.Thesedeviceswillbeinstalledatornearcentersofutilization.Eventually,astheirpenetrationincreasesconsiderably,theywillbeinterconnectedinagrid-likefashionforstabilityandenhancedreliability.Thesegridsarecalled‘microgrids.’Thispaperpresentsarationalmethodofbuildingmicrogridsoptimizedforcostandsubjecttoreliabilityconstraints.Themethodisbasedondynamicprogrammingandconsistsofdeterminingtheoptimalinterconnectionbetweenmicrosourcesandloadpoints,giventheirlocationsandtherightsofwayforpossibleinterconnections.Anewapproach,called‘unitlinkaddition,’isalsointroduced.Themethodisdemonstratedusinga22-bussystem.

I.INTRODUCTION

Thesigniﬁcanceofsystemplanningandexpansionhasincreasedmanifoldduringthepastfewyearsbecauseoftheradicalchangesgoingoninthepowerindustry[1].Thesystemisbeingrestructured.Deregulationisallowingopenaccessontransmissionlinesandwheelingoflargeamountsofpowerfromgeographicaldistantareas.Thetransmissionsystemwhichwasoriginallydesignedforstabilityisnowexperiencingseverestress.Further,theaginginfrastructureisnolongercapableofaccommodatingloadgrowth.Recentblackoutshavepointedtothefactthatthesystemisindeedexperiencingunprecedentedamountsofstress.Onepossiblesolutionistobuildnewtransmissionfacilities.However,thisisaveryexpensiveandtimeconsumingprocess.Theotheralternativeistouseon-sitegeneration.Thisisintheformofdistributedgeneration,thatcanbeusedatornearpointsofutilization.Thismethodismoreattractivebecauseﬁrstly,italleviatestheneedforbuildingthecostlytransmissiongrid.Secondly,becauseoftheirverynature,distributedgener-atorscanbeinstalledondemand,insteadofwaitingforalong

timetobuildtraditionalplants.Inthisregard,therehavebeenmanyeffortsfromboththegovernmentandindustrialagenciesfordevelopinganddeployingtheseresources.Inparticular,theUSDepartmentofEnergy(USDoE)haslaidoutastrategicplan[2][3]foreffectiveplacementandutilizationofDERsintheformofmicrogrids.Asmentionedpreviously,DERsarelikelytobesitedatloadpoints,i.e.,inthedistributionnetwork.Thisintegrationwillsigniﬁcantlychangethestructureofthesenetworks.Tra-ditionallydistributionnetworkshavebeenradial,andthefocusofplanningmethodologieshasbeenprimarilyonpreservingtheradialityofthedistributionsystem[4][5].However,asthepenetrationofDERsincreases,itmaybeprudenttointerconnectthesegeneratingdevicestoformagrid.Thiswouldbeanimplementationofamicrogrid.Signiﬁcantresearchhasbeenconductedintheareasoftransmissionexpansionplanning[6]anddevelopingmicro-grids[7]–[12].Mostnotableisthe“CERTSMicrogridCon-cept”whichfocusesonaself-sustainedheatandpowersupplytoacompactclusterofloads.ManyoftheapproacheshavefocusedontheoptimalplacementofDERsinthedistributionnetwork[11][12].Theseapproacheshaveassumedandhaveattemptedtopreservethefundamentallyradialstructureofthedistributiongrid.Incontrast,weaddresstheissueofdistributionnetworkexpansionwithareliabilitycriterionusingdeploymentofdistributedresources.OurapproachisdirectedtowardthedevelopmentofmicrogridsthatarenetworkedinstructureandconformtotheUSDepartmentofEnergy’svisionofmicrogridsthatcanoperateinbothgrid-connectedandislandedmodes.Thispaperpresentsarationalmethodofbuildingcostoptimalmicrogridssubjecttoreliabilityconstraints.Thisworkisaninitialsteptowardsfulﬁllinganimmediateneedforsystemplanningtoolsthattakeintoaccountthechangesgoingonintheindustry.Itwillenabledesignofreliablearchitecturesforfuturesystemplanning.

II.SYSTEMMODELING

1)Generators:Thesearemodeledastwo-statedevices.EachgeneratoriisdescribedbyitsmaximumgeneratingcapacityGmaxianditsforcedoutagerateFORi.