Valuation of distributed energy resources in active distribution networks

In concert with the transformation of conventional passive power distribution system, distributed energy resources (DERs) have progressively become participants in the provision of electricity services in active distribution networks (ADNs). In this paper, we propose a systematic valuation process to quantify the value of DERs in the ADN context. The paper first provides comprehensive insights into the impacts of DERs on ADN and the society as a whole. Given the technological, locational, and temporal diversity of DERs, a two-part scheme is developed to value and compensate DER portfolios proposed by customers and independent third parties. In particular, DERs are valued for their benefits and costs in both short and long terms. An integrated resource planning model is formulated to quantify the value of a given DER portfolio to be installed, where bi-level optimization techniques are applied to coordinate decisions on ADN planning and operations. In order to determine the short-term operation benefits of the DER portfolio on a continuous basis, a retail market operation model is developed based on peer-to-peer energy transactions among prosumers, when the impacts of DERs on ADN operations are monetized by distribution locational marginal prices. It is finally concluded in the paper that the proposed valuation scheme will not only contribute to the proactive investment of DERs in ADN but also help enhance the role of DERs in offering affordable, reliable, resilient and sustainable electricity services to customers.     

改善微电网频率稳定性的分布式逆变电源控制策略

基于电力电子换流器并网的分布式能源对微电网系统的惯性几乎没有贡献,这将成为分布式能源大规模接入微电网之后面临的新问题。虚拟同步发电机控制策略作为一种能够使含储能装置的分布式逆变电源具有虚拟惯性的方法,对改善微电网系统频率的稳定性具有重要作用。在理论推导及分析虚拟同步发电机控制与微电网关系的基础上,提出了一种改善微电网频率稳定性的分布式逆变电源虚拟同步发电机整体控制策略,将同步发电机的转子运动方程、一次调频特性及无功调节延迟特性引入到逆变电源的上层控制中,底层控制则根据同步发电机的并网矢量关系得到。最后,搭建了简单微电网系统的Matlab/Simulink仿真模型及物理实验平台,通过仿真和实验充分验证了所提虚拟同步发电机控制方法对微电网频率稳定性的支持作用。     

Integrating distributed generation into electric power systems: A review of drivers,challenges and opportunities

It is now more than a decade since distributed generation (DG) began to excite major interest amongst electric power system planners and operators, energy policy makers and regulators as well as developers. This paper presents an overview of the key issues concerning the integration of distributed generation into electric power systems that are of most interest today. The main drivers behind the focus on DG integration, especially of the renewable type, in many countries around the world are discussed. A synopsis of the main challenges that must be overcome in the process is presented. Particular emphasis is placed on the need to move away from the fit and forget approach of connecting DG to electric power systems to a policy of integrating DG into power system planning and operation through active management of distribution networks and application of other novel concepts. The paper also analyses the repercussions in transmission system operation and expansion that result from the connection of large amounts of DG of different energy conversion systems focusing on issues related with impacts in steady state operation, contingency analysis, protection coordination as well as dynamic behaviour analysis. A discussion on the possibility of provision of ancillary services by DG is also included. Some results from studies performed in the interconnected Portuguese transmission system are presented and discussed. Some of the opportunities that could be exploited in support of the integration and hence greater penetration of DG into electric power systems are also explored.     

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.     

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.     

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.     

Electricity rates for the zero marginal cost grid

The electricity industry is rapidly changing: costs are increasingly dominated by capital and technology is turning loads into resources. This is similar to the early days of the Internet. Building on rate-structures used in the communications industry, utilities of the future should offer customers a portfolio of service contract options that provide a signal to the utility regarding the type and amount of infrastructure that should be deployed.     

需求侧管理理论体系初探

需求侧管理（DSM）是节能减排、改善环境、应对全球气候变化行之有效的手段．也是国家可持续发展的重要战略选择。综合资源规划（IRP）是需求侧管理的理论基础,需求侧管理是综合资源规划的重要组成部分,两者构成IRP／DSM理论体系。在20世纪后20年,其之所以取得了巨大成效,IRP/DSM理论体系发挥了很大作用。若希望需求侧管理在21世纪继续发挥更大作用。需要深入研究综合资源战略规划（IRSP）。文章探讨了在电力市场化改革的条件下将综合资源规划的理念拓展为国家层面的综合资源战略规划,使其成为需求侧管理的理论基础。IRSP和DSM构成新的理论体系,并在这一理论体系中分析了在现行价格及机制的市场环境下,到2020年我国需求侧管理的潜力。     

基于图论的主动配电网双阶段电压控制

对分布式电源实施主动管理可以减小其出力间歇性和随机性给配电网造成的负面影响,但这也对配电网的电压控制提出了更高的要求。首先介绍了主动配电网电压控制的特点,采用图论对主动配电网的网络结构进行描述。提出了主动配电网双阶段电压控制方法,该方法是通过优化系统中各分布式电源的无功出力共同协作将电压控制在规定范围内。最后,在8节点和30节点配电系统验证了所提方法的有效性和实用性。     

Rural electrification and expansion planning of off-grid microgrids

This paper presents the past and current practices for rural electrification and the current trend in using off-grid microgrids to provide energy to the customers with no access to the central electricity network. The challenges correspond to the capacity expansion of off-grid microgrids including the financial and business models for establishing these technologies, the economic and reliability considerations, the environmental issues, the expansion and feasibility studies, and the uncertainties in the operation horizon were presented.     

All-source bidding: Extending integrated competition to utility resource procurement

When facing a resource need, utilities should use all-source bidding to help identify the highest value resources to procure. By soliciting proposals from suppliers across all resource options, the utility applies to procurement the same important principles that guide integrated resource planning. All-source bidding is not new, but many utilities have not used it. This article explains how all-source bidding works, describes the benefits, and offers practical recommendations for utilities and utility regulators.     

对我国电力行业应用综合资源规划方法的探讨

剖析传统规划方法存在的问题,对我国电力行业应用综合资源规划方法的必要性进行论述,并对电力行业应用这一规划方法提出了建设性意见。     

Resolving the conflict between new and old: A comparison of New York,California and other state DER proceedings

Distributed energy resources present opportunities to serve grid and customer need through two-way power flow. New values, methods, and planning are required to efficiently interconnect and utilize DERs. This paper analyzes New York’s and California’s DER proceedings to provide a comparison of the similarities and differences between these and other states that will result in different levels of deployments and valuations of DERs.