基于电动汽车的极端场景多微电网韧性提升策略研究

极端场景下微电网与主网断开形成多个孤岛时,微电网内重要负荷的持续可靠供电面临极大挑战。微电网群内的电动汽车储能参与负荷支撑是提高系统韧性的有效技术手段。针对微电网孤岛供电问题,提出了一种基于电动汽车储能的多微电网两阶段韧性提升策略。首先,建立正常运行时多微电网能量管理模型,通过协调系统内各类发电资源进行能量互济,实现运行成本最小化。然后,针对台风极端事件引起的孤岛微电网持续可靠供电问题,通过多微电网各类发电资源和电动汽车储能进行能量互济,构建了多微电网两阶段韧性提升模型,最大限度地减少切负荷量,使系统运行成本最优。最后,采用Shapley值对涌现收益进行合理分配,并通过与传统多微电网能量管理方法进行对比,验证了所提韧性提升策略的有效性。     

Multi-actor perspective,socio-technical barriers,and microgrid development in China

The microgrid is a new concept in China and may potentially play an important role in enhancing the resilience and sustainability of electricity generation and distribution. However, the development of microgrids faces many challenges. This study examines the barriers to microgrid development using a case study of a pilot zone in Qingdao. Drawing on the theories of multi-level perspective and multi-actor perspective, we presented new empirical evidence on how the pilot microgrid projects were rendered difficult by the resistance from the existing industrial regime and the challenging economic and socio-political environments. The monopoly of state-owned grid operators in electricity transmission and distribution is difficult to break at a local level. The findings deepen our understanding of the challenges encountered by innovators in China’s microgrid development and hold implications for policymakers in making more targeted policy mixes to support energy transition activities.     

Sectionalized microgrids: The key to regulatory assistance for unbundling reliability?

Are telecom precedents involving the development of premium reliability services transferable to electric utilities? Can electric utilities offer customers premium reliability services through microgrids? We believe sectionalization, a new network design, can preserve customer choice and ensure that incremental costs for premium services are not shifted to customers taking standard service – key objectives necessary to gain regulatory approval. We present three case studies to illustrate how sectionalization can be used.     

基于模型预测控制混合储能系统的直流微电网韧性提升策略

受可再生能源出力波动、负荷变化、故障以及非计划性脱网等事件的影响,直流微电网将面临不同时间尺度的动态功率不平衡问题.直流微电网运行韧性体现了系统在高频/小干扰事件与低频/极端事件下的快速响应、减少性能损失并尽快恢复的能力.提出了一种基于有限控制集模型预测控制的混合储能系统的直流微电网运行韧性提升策略.为完善直流微电网韧性评价体系,首先提出了量化直流微电网运行韧性的方法.其次,建立混合储能系统离散预测模型,设计代价函数以及不同控制目标之间的权重系数,最大化功率型与能量型储能系统的优势,实现了基于局部信号的快速充放电与能量自动恢复控制.最后,通过多种干扰事件算例,验证所提出的韧性提升方法的可行性与有效性.     

考虑路径损耗的热电联供型微网三层能量优化策略

为了降低微网对外部系统的依赖与微网自身的运行成本,针对热电联供型微网群,提出了一种三层能量优化策略。该策略不仅构建了以各微网运行成本最小为目标的下层优化运行模型、各主体间交互成本最小为目标的上层优化运行模型,还新构建了以能量传输路径损耗最小为目标的中间层优化运行模型。该中间层模型通过易货交易和买卖交易的方式提高微网间能量互济能力,并基于Floyd-Warshall算法为微网间能量交易搜索最优传输路径。算例结果显示,该三层优化策略具有良好的适用性,相比其他优化策略,能量传输过程损耗更低、微网间能量互济能力更强,各微网运行成本更小。     

兼顾可靠性与经济性的孤岛型光储微电网容量配置方法

可靠性和经济性是孤岛型光储微电网容量配置的2个重要参照,但不能同时最优.为协调二者矛盾,提出了一种兼顾可靠性与经济性的孤岛型光储微电网容量配置方法.该方法针对概率类、频率及持续时间类指标,从容量及功率角度进行了可靠性评估与经济性分析,对比研究了不同负荷点接入光储微电网的配置方案.结果表明:一定储能配置方案下,光伏容量的增加可优化概率类指标,但频率及持续时间类指标变化并非单调;合理的储能配置能进一步优化概率类指标,降低或平抑系统平均停电次数指标对微电网的冲击;在负荷水平较低处安装微电网可实现可靠性与总成本的最优折中.     

微电网并网标准研究

根据现有的国内外相关标准和规范,从电力系统的角度初步研究了微电网并网、并网运行以及解列过程的技术要求。提出了微电网并网的基本要求和并网准则,基于配电网可靠性考虑,对微电网并网时接入点、接入容量和接入方式提出了要求。对微电网接入电网引起的电能质量、有功功率和无功功率控制、电压调节、继电保护、通信、监测和电能计量等问题进行了分析。将微电网的解列分为正常解列和事故解列,着重强调事故解列时孤岛区域的划分原则及解列要求。通过对微电网接入电网所需考虑的关键问题进行分析探讨,为制定微电网的接入标准提供了一定的基础。     

基于博弈论的配电网中多级微电网优化配置分析

随着分布式发电和微电网技术的发展,未来配电网中将分布着多种规模不同的微电网系统,投资主体也将呈现多样化趋势,为配电网规划设计带来巨大挑战。文中探讨了配电网中的多级微电网结构,选取用户、以能源服务公司为代表的投资开发商和电力公司为参与者,分析了不同投资主体的利益关系,综合考虑分布式电源投资费用、购售电费用、补贴、环保收益、供电可靠性收益等因素,建立了基于不同投资主体的经济模型。结合博弈分析方法,提出了一种基于博弈论的配电网中多级微电网优化配置模型。从经济性角度,以光蓄微电网为例,探讨分析了竞争博弈模式下不同投资主体的优化配置方案,为未来配电网中微电网的设计和建设提供了参考。     

Unbundling reliability: Lessons from the telecom industry

Electric utility customers are seeking increased reliability and resilience. Evolving distributed energy and grid modernization technologies can provide customers with new self-supply options, but regulatory issues are holding back their full deployment. We examine microgrid projects to identify causes of regulatory resistance. Then we examine how telecom utilities, faced with similar challenges, responded by offering customers new, regulator-approved premium reliability services. Finally, we offer insights from telecom precedents that may be transferable to electric utilities.     

Missing discourse on microgrids – The importance of transmission and distribution infrastructure

The current discourse on microgrids is mostly limited to enhancing resiliency and misses the importance of existing transmission and distribution (T&D) infrastructure. Using a conceptual framework and ten microgrid case studies, we illustrate that T&D infrastructure affects the anticipated benefits of microgrids. Currently microgrids are often constructed in lieu of T&D improvements. In the long run, microgrids can work with existing T&D infrastructure to improve the reliability, efficiency and environmental sustainability of the electrical grid.     

新型交直流混合微电网拓扑及其可靠性分析

交直流混合微电网综合了交流微电网和直流微电网的优点,是未来智能电网的发展趋势之一,而拓扑结构和可靠性研究是交直流混合微电网发展的基础。参考现有微电网拓扑结构,结合交直流混合微电网的构成和运行方式,提出了3类新型交直流混合微电网拓扑,分别是一对多型(一个交流微电网与多个直流微电网)、多对一型和多对多型,根据3类拓扑自身的特点,指出了各自的适用场景;基于配电网可靠性分析方法,考虑分布式电源接入和微电网孤岛运行,提出了交直流混合微电网的可靠性计算方法;通过算例,对比和分析了提出的3类新型交直流混合微电网拓扑的可靠性。     

Blockchain for decentralized transactive energy management system in networked microgrids

The proliferation of distributed energy resources is reshaping the landscape of power distribution systems, including a network of autonomous microgrids. Networked microgrids transact energy for managing the efficiency, reliability, resilience, security, and sustainability of electric power services. This article offers a vision and analyzes a scheme developed for networked microgrids that utilizes blockchain technologies to optimize the financial and physical operations of power distribution systems. Blockchain provides a powerful and trustworthy path for launching distributed data storage and management, the article explores the possibility of customizing blockchain technologies to meet socioeconomic requirements of transactive energy management at the power distribution level. Then, a set of interoperable blockchains embedded with self-enforcing smart contracts is proposed to manage energy and financial flows among transacting microgrids in a credible manner. The article presents additional smart contract measures for securing optimal energy transactions between networked microgrids and the local distribution grid. It is concluded that blockchain technologies embedded in transactive energy will play a significant role in the evolution of traditional power distribution systems to active distribution networks.     

可交易能源框架下的微网群动态电能交易策略

为促进微网间的能量互济和协调控制以及平抑微网与配网之间的功率波动，文章提出了可交易能源（transactive energy，TE）框架下的微网群动态电能交易策略。首先，设计了基于可交易能源平台的微网群电能交易结构，保证了市场参与者的隐私安全，提高了电能交易的灵活性；其次，构建了微网群动态电能交易模型，以计及储能电池退化成本和可控负荷调度补偿成本的微网成本最低为目标优化电能报价，以微网群电能交易成本最低为目标优化电能交易量，通过多轮竞价以协调微网间的电能交易，促进系统供需平衡，减小微网与配网之间的交互功率；最后通过3个互联的微网分析验证所提策略的有效性和经济性。     

基于合作博弈的微网储能容量优化配置

合理配置储能容量在平抑清洁能源功率波动、辅助稳定电网频率等方面具有重要意义。针对含有风电、光伏发电的微网,兼顾储能设备参与电网一二次应急调频,利用储能空闲资源参与电网调频,同时考虑了微网的电量成本、投资维护成本等因素,以微网每天综合费用最低为优化目标,基于合作博弈建立微网均衡模型,利用粒子群和内点算法求解各微网最优容量配置。算例结果验证了模型与方法的合理性。     

Alternative ratemaking in the US: A prerequisite for grid modernization or an unwarranted shift of risk to customers?

With increasing frequency, investor-owned electric utilities are requesting preferred cost recovery for “grid modernization” in multiple forms, from multi-year rate plans to riders. Utilities’ claims that massive grid investment is necessary, and that exceptional investment requires exceptional cost recovery, are typically accepted by policymakers with little challenge. It is difficult for policymakers to resist the siren call of grid modernization’s perceived outcomes, from improved reliability and resilience to reduced risks to safety and new customer technology adoption (electric vehicles, distributed energy resources, and more). This paper provides a contrarian viewpoint that is virtually absent as policymakers consider alternative ratemaking practices. It introduces the possibility that excess grid investment in the name of modernization is not only possible, and economically harmful, but has already occurred, encouraged by alternative ratemaking. It provides examples of common grid modernization expenditures the authors have identified as cost-ineffective in the course of their work. It also describes traditional grid planning practices with proven ability to address changing requirements over time, calling into question the need for exceptional grid modernization investment plans. Most important, the paper explains the moral hazard inherent in alternative ratemaking, and the fundamental shift in ratemaking risks and responsibilities from utilities to customers that results. The perspectives this paper presents are critical for policymakers to understand before adopting, extending, or expanding alternative ratemaking practices in their respective jurisdictions.     

基于机会约束规划的综合能源微网群协调运行策略研究

随着我国分布式能源系统的迅速发展,在用能侧出现大量的综合能源微网,而相邻综合能源微网以微网群的形式协同运行将是综合能源微网今后发展的重要趋势。基于此,提出了一种适用于综合能源微网群的协调运行方法。该方法旨在协调分属不同利益主体的综合能源微网,在共享有限信息和彼此独立决策的条件下,寻求微网群系统的最优运行方案。考虑到综合微网群系统中通常含有较多可再生能源,为了提高运行方案应对可再生能源出力不确定性的鲁棒性,采用机会约束规划方法,以有效抑制不确定性的影响。最后,通过对含电力-天然气的微网群系统算例进行分析,结果表明,与传统集中方法相比,所提方法能较好提升系统的经济性和安全性,实现二种特性的权衡。     

计及电动汽车充电需求的孤岛微网可靠性计算方法

由于远离大陆,独立海岛上的微网多运行于孤岛模式,不与配电网发生功率交换,微网内部实现电力供需平衡,同时,电动汽车充电需求的接入给孤岛微网的可靠运行带来了影响。提出了一种计及电动汽车充电需求的孤岛微网可靠性计算方法。首先,通过模拟用户的出行行为建立了基于出行链理论的电动汽车充电负荷模型,计及风电和储能特性提出了微网运行策略和负荷分块削减策略。其次,考虑电动汽车充电需求,提出了年均充电中断次数、系统平均充电可用性等新型指标,构建了与传统配电网有差异的微网供电可靠性评估体系。最后,对改进的RBTS Bus6馈线F4系统进行了可靠性评估。算例结果表明,微网运行策略和电动汽车充电需求对孤岛微网的供电可靠性影响显著。     

考虑灵活性的孤岛微电网群分层能量管理策略

彼此临近的孤岛微电网形成孤岛微电网群,可通过能量互济实现不同源荷特性的微电网之间的资源优化分配,进而提升区域电网运行的经济性、可靠性和可再生能源利用率。针对孤岛微电网群的能量管理问题,基于多代理系统,建立了孤岛微电网群分层能量管理架构。建立了灵活性指标评估可再生能源出力不确定性对系统运行的影响,在此基础上,构建了微电网层多目标优化能量管理策略和集群层能量分配策略。采用宽容分层序列法对线性化后的模型进行求解。最后以四个微电网组成的孤岛微电网群为例,验证了所提能量管理策略的有效性。     

适于微电网可控开关无缝切换的无源网络优化设计

含可再生能源的分布式发电系统在配电网和微电网中的渗透率正日益提高,供电可靠性得到提高。但配电网和微电网中大量敏感负荷对电压质量的要求日渐严格,要求外部电网故障时微电网工作状态能"无缝切换"。针对现有微电网与外部电网连接的可控开关方案在无缝切换过程中存在的问题,文中提出了一种适于微电网可控开关无缝切换的无源网络优化设计方案。在外部电网发生电压暂降时刻实现微电网向孤岛模式的无缝切换,确保敏感负荷的可靠运行,同时也有效实现微电网公共连接点电能质量问题的综合治理。通过数学建模和数值计算确定了无源网络的优化设计方法,建立了典型算例的PSCAD/EMTDC电磁暂态仿真验证了该方法的有效性。     

Value-based power system reliability planning

In a competitive energy market, in which power supply reliability can influence customer purchasing decisions, electric utilities throughout the world are rapidly recognizing that they cannot ignore customer preferences. Today's energy market is characterized by intense price competition, and electric utilities are faced with new challenges of large debts, budget constraints, safety, environment and economic issues, lower load growth than in the past, need for more involvement of public at large in the planning and design process, and more competitive nonconventional suppliers of electricity. In addition, in a deregulated competitive energy market, electric utilities are under conflicting pressures of providing even higher standards of service reliability and holding the line on rates. Value-based system facility planning offers a rational response to these conflicting customer demands. This paper presents two case studies to illustrate the basic concepts and applications of value-based power system planning. The paper also presents a methodology for determining the unique composite customer cost of interruptions (i.e. damage functions) for changing area system network configurations. These techniques are presently being used in the decision-making processes at Alberta Power Limited, Edmonton, Alta., Canada