Multi-agent system for energy resource scheduling of integrated microgrids in a distributed system

This paper proposes a multi-agent system for energy resource scheduling of an islanded power system with distributed resources, which consists of integrated microgrids and lumped loads. Distributed intelligent multi-agent technology is applied to make the power system more reliable, efficient and capable of exploiting and integrating alternative sources of energy. The algorithm behind the proposed energy resource scheduling has three stages. The first stage is to schedule each microgrid individually to satisfy its internal demand. The next stage involves finding the best possible bids for exporting power to the network and compete in a whole sale energy market. The final stage is to reschedule each microgrid individually to satisfy the total demand, which is the addition of internal demand and the demand from the results of the whole sale energy market simulation. The simulation results of a power system with distributed resources comprising three microgrids and five lumped loads show that the proposed multi-agent system allows efficient management of micro-sources with minimum operational cost. The case studies demonstrate that the system is successfully monitored, controlled and operated by means of the developed multi-agent system.     

Energy requirement for distributed energy resources with battery energy storage for voltage support in three-phase distribution lines

Integration of distributed energy resources (DER) into distribution systems is a new concept for improving system capacity and stability, feeder voltage, and supply quality and reliability. This paper has addressed voltage support in distribution systems by energy injection from a battery storage distributed energy system. An operation strategy for an inverter interface battery energy storage DER has been developed for maximum improvement in feeder voltage with minimum energy injection from the DER. A control strategy has been proposed for inverter based battery storage DER to regulate network voltage effectively, through operating the DER to generate real (P) and reactive (Q) power with Q priority. The implementation of the inverter interface DER with battery energy storage will save fuel cost of DER but be of much higher capital cost than using a rotary generator. The proposed technique has been evaluated by simulation on a three-phase distribution system with time varying loads. Test results indicate that DER operating with Q priority offers the best solution for maximum voltage improvement. The results also confirm that DER injecting P and Q at the ratio of maximum voltage sensitivity of line presents better solution for power loss reduction than the solution offered by the DER operating with Q priority.     

From microgrids to aggregators of distributed energy resources. The microgrid controller and distributed energy management systems

Microgrids are a collection of distributed energy resources (DER) within a specific boundary, with a control system for their management and operations at the point of interconnection with the distribution utility. As microgrid concepts evolve, they are being applied to aggregations of DER outside boundaries with appropriate controls for operation with transmission and distribution utilities and participation in markets. This article marks this evolution and points towards the common functionalities of microgrid controllers and distributed energy management systems for integration of DER into transmission and distribution operations and markets.     

Economic framework for compensating distributed energy resources: Theory and practice

We offer an economic framework for analyzing the compensation that DERs should receive for energy exported to the grid. This economic framework requires that the prices paid to DER owners be based upon the forward-looking, economic costs that their utility avoids when it buys the energy from the customer. We explain why this results in efficient ‘build or buy’ and ‘purchase and install’ decisions of the utility and DER customer, respectively.     

The role of energy efficiency in a distributed energy future

Many state regulatory commissions are engaged in proceedings to modernize the electric grid. These proceedings include a heavy focus on updating system planning processes to reflect growth in distributed generation and other technological advances. This essay examines current distribution system and distributed resource planning. We analyze how states are incorporating energy efficiency into these plans, focusing on states that are actively using efficiency as a resource.     

Integration of distributed energy resources into low voltage grid: A market-based multiperiod optimization model

This paper develops a multiperiod optimization model for an interconnected micro grid with hierarchical control that participates in wholesale energy market to maximize its benefit (i.e. revenues-costs). In addition to the operational constraints of distributed energy resources (DER) including both inter-temporal and non-inter-temporal types, the adequacy and steady-state security constraints of micro grid and its power losses are incorporated in the optimization model. In the presented model, DER are integrated into low voltage grid considering both technical and economical aspects. This integration as a micro grid can participate in wholesale energy market as an entity with dual role including producer and consumer based on the direction of exchanged power. The developed model is evaluated by testing on a micro grid considering different cases and the results are analyzed.     

多目标配电网综合节能潜力评估

由于某些配电网改造措施既能使网损下降亦能使线路电压质量得到改善,因此创新地提出了结合节能及电压质量改善的综合节能潜力评估方法。根据实际情况对某地区线路进行分类,抽取典型线路进行六项改造措施的综合节能潜力计算。根据各措施的综合节能潜力排名值,得到适合各线路的改造方案。以南方某市配电线路为例,进行综合节能潜力评估,提出适宜的改造方案。     

Retail pricing responses to the challenge of distributed energy resources

The recent growth in distributed energy resources has raised issues of how to ensure that utilities recover allowed fixed costs for customer and distribution system services. This paper presents the issues related to DER in the context of both traditional cost-of-service and rate design methods, and economically efficient retail pricing. The objective is to clarify certain misconceptions and recommend retail pricing solutions.     

考虑源网荷灵活性资源的配电网储能鲁棒规划

配电网中风光等分布式发电渗透率增加造成净负荷剧烈波动,导致配电网灵活性需求急剧增加.为此,提出一种考虑源网荷灵活性资源的配电网储能优化配置方法.首先,基于灵活性理论分析配电网中灵活性资源的特性,建立衡量配电网整体灵活性的灵活性供需平衡指标和衡量网络灵活性的支路灵活性应对能力指标;然后,从多时间尺度采用K-means方法...     

Extraneous instabilities arising in power systems with non-synchronous distributed energy resources

This short communication describes an extraneous instability that can be observed when solving time domain simulations for power systems with inclusion of non-synchronous distributed energy resources such as those based on voltage source converters and asynchronous generators. The instability object of the paper is caused by the interaction of (i) synchronous machines modeled using a synchronous reference speed and (ii) non-synchronous generators whose controllers depend on a d − q transformation. The paper also provides two simple solutions able to remove such extraneous instabilities. The New England 39-bus benchmark system is used for testing the proposed solutions.     

A dynamic model for distributed energy resource expansion planning considering multi-resource support schemes

In this paper, a system dynamics based model is developed to investigate the impacts of multi-resource regulatory policies on distributed energy resource (DER) expansion planning. DERs usually include a variety of renewable and fossil based generation technologies such as wind and gas engine resources, combined heat and power (CHP), demand response (DR) and energy storage. The intermittent nature and uncertainty in power generation of some of these resources and other uncertainties that exist in the market environment would cause investors to encounter risk in their investment decisions. Implementation of any supporting policy affects any investor’s behavior and investment level of other investors. Regulators should properly identify long-term impacts of their support policies in the energy resource expansion in order to choose a proper support scheme. These support schemes should ensure the long-term market stability. It is important for a DER investor to properly identify his/her long-term investment behavior to select an appropriate strategy. In this paper, the system dynamics method is used to investigate these issues. The impacts of various multi-resource regulatory policies on market dynamics are modeled and compared with the single-resource support schemes ones. In this study, support schemes are considered for supporting DR, wind resources, CHPs and photovoltaic resources.     

国外需求响应技术在主动配电网中的应用

主动配电网是提高可再生能源渗透率、智能电网用电的有效手段,而需求侧响应机制能够显著提高配电网的灵活性。着重介绍国外最新需求侧管理技术在主动配电网管理中的应用以及未来发展,包括需求侧管理技术对配电网规划、网络一体化的影响以及欧洲的需求侧管理项目实践。     

含能源互联微网的主动配电网分层分布式协调控制

目前,天然气网络、热力网络和电力网络在主动配电网中的耦合联系加深,共同为用户提供冷、热、电、气等多种不同形式的能源,但相关的协调控制技术仍不成熟。以电网为核心,和热网、天然气网进行互动优化,首先提出了含电力网络、天然气网络和热力网络的综合建模方法,对各能源子系统多能流的约束条件及运行目标进行了综合优化,实现了多能源协调互补和深度融合。然后,设计了多微网和主动配网之间在稳定运行时的分层分布式协调控制策略,将系统分为主动配电网层、能源互联微网层和元件层的三级控制结构,在元件层提出采用改进后的二级功率优化控制来进行分布式设备之间的协调控制。最后,利用PSCAD/EMTDC仿真软件,搭建主动配网的仿真平台,含3个能源互联微电网来证明智能调控方法的合理性。     

Planning of distributed renewable energy systems under uncertainty based on statistical machine learning

The development of distributed renewable energy, such as photovoltaic power and wind power generation, makes the energy system cleaner, and is of great significance in reducing carbon emissions. However, weather can affect distributed renewable energy power generation, and the uncertainty of output brings challenges to uncertainty planning for distributed renewable energy. Energy systems with high penetration of distributed renewable energy involve the high-dimensional, nonlinear dynamics of large-scale complex systems, and the optimal solution of the uncertainty model is a difficult problem. From the perspective of statistical machine learning, the theory of planning of distributed renewable energy systems under uncertainty is reviewed and some key technologies are put forward for applying advanced artificial intelligence to distributed renewable power uncertainty planning.     

考虑电动汽车接入的主动配电网优化调度

主动配电网(ADN)中可再生能源与电动汽车的大量接入给当前配电网的规划、建设、调度和运行带来了诸多挑战。文中研究和设计综合考虑源、网、荷侧不确定因素的ADN优化调度方法,对实际配电网运行具有重要指导意义。首先建立ADN综合评估体系,分别从主动控制性、主动管理性和主动经济性三方面衡量ADN的优化调度水平。而后,依据综合评估体系,提出考虑电动汽车智能调度系统的多阶段优化方法,该方法不仅可平抑间断性电源和电动汽车接入电网引起的波动,还可实现当前配电网结构和资源的优化调度。因此,所提方法可被广泛运用于电力系统日前调度,实现ADN的高效运行和管理。     

可视化的配电网线损计算与管理系统

介绍了一个适用于配电管理系统 (DMS)高级应用软件的可视化操作平台 ,并在此平台上开发了全图形化人机界面的配电网线损计算与管理系统 ,提高了配电网大量数据录入的准确性和效率 ,并提供了方便、快捷、直观的查询和统计功能。实现了图形、数据、计算、分析与管理的高度一体化。这里还提出了一种适用于配网潮流计算的改进型前推回代法 ,这种方法具有收敛快、准确、实用等特点。     

Integrated distribution network expansion planning incorporating distributed generation considering uncertainties,reliability, and operational conditions

In this paper, an integrated methodology is proposed for distribution network expansion planning which considers most of the planning alternatives. The planning aims to determine the optimal reinforcement of existing medium voltage lines and high voltage/medium voltage substations, or installation of new ones to meet the load growth in the planning horizon subject to the technical and operational constraints. Also, to take the advantages of new technologies, the renewable and non-renewable distributed generations have been included in the problem as another alternative. The uncertainties related to renewable DGs, load demand, and energy price have been considered in the calculation of cost components. The load duration curve has been utilized for loads such that the results be more precise. The possibility of islanding and load transferring through the reserve feeders have been regarded in the problem to improve the reliability of the network. Also, the required condition for successful and safe operation of island considering all of uncertainty states have been checked out to accurately calculate the reliability. The genetic algorithm is employed to solve this integrated problem. Finally, the proposed method is applied to the 54-bus system and also a real large-scale distribution network, and the results are discussed. The results verify the effectiveness of the presented method.     

主动配电系统中分布式电源和储能系统的优化配置

针对多类型分布式电源和储能系统在主动配电系统中的接入位置及容量问题,建立了综合主动配电系统的经济成本、电压质量以及CO_2排放量三个方面的多目标优化配置模型。对传统的NSGA-Ⅱ算法进行了改进,在初始种群中引入反向学习机制,并以一定比例选择种群中的支配个体,以增加种群的多样性和提高算法的搜索能力,然后基于权重系数调节方法帕累托最优解集中确定最优解。最后,利用IEEE-33配电系统算例验证了所提出模型和算法的正确性和可行性。     

主动配电网储能动态配置规划方法

主动配电网中的负荷和分布式发电出力具有明显的周期变化特性,已有的配电网储能规划方法,其规划结果均是接入点和容量固定不变的储能配置,储能的灵活性和价值尚存在较大的发挥空间。提出了一种主动配电网储能动态配置规划方法,即伴随负荷需求和分布式发电出力场景变化,在配电网中动态配置储能装置。以储能在不同场景下的接入点、容量、运行方式为决策变量,以储能带来的综合经济效益最大为目标,构建了主动配电网储能动态配置的混合整数二阶锥规划模型。以IEEE 33节点系统为例,验证了所提方法的可行性和有效性。该方法是对储能装置灵活性运行方式的有益拓展,使其能够服务于主动配电网多变的运行场景,从而使储能价值得到充分发挥。