Julio Romero Aguero

A novel approach for evaluating the impact of electric vehicles on the power distribution system

this paper presents a useful and practical approach for assessing the impact of electric vehicles on the electric power distribution system while keeping to a manageable volume of detailed circuit and equipment studies. This paper addresses electric vehicles as an electric load only and does not consider the potential of the vehicle being a generation source. It also only addresses the substation, primary and distribution transformer impacts. It does not consider impacts on the secondary system. The method uses a statistical clustering algorithm to identify a set of representative feeders for the electric utility system, each representing a certain subset of the utility feeder system. This set of representative feeders is analyzed over a series of electric vehicle market penetration scenarios from 0 to 100%, in order to determine the expected impacts on loading, losses, voltage and reliability performance and power quality that each feeder will see. Then, distribution system capacity upgrades that are required to serve uncontrolled EV loads in each area, as well as the benefits that could if EV loads were limited or re-scheduled via demand response are assessed for each. Results from these representative feeder scenario studies are then used to estimate the impacts, control and mitigation needed, and performance expected across the entire utility feeder set. This method has been used to plan for increasing amounts of electric vehicle loads on several utility systems in the USA. Results from one case study are discussed.

Improving the efficiency of power distribution systems through technical and non-technical losses reduction

This paper presents a review of technologies, methodologies and operational approaches aimed at improving the efficiency of power distribution systems, with emphasis in the accurate estimation and reduction of technical and non-technical power and energy losses. From a losses evaluation viewpoint this includes efficiently using data supplied by utility information systems, and utilizing computational feeder models and advanced modeling and simulation software for accurately calculating technical and non-technical losses. From a technical losses reduction perspective this includes the implementation of smart grid approaches such as Volt-VAr Optimization (VVO), distribution state estimation, automatic feeder reconfiguration, meshed distribution feeder operation, and Distributed Energy Resources (DER) among others. From a non-technical losses reduction standpoint this includes the utilization of Advanced Metering Infrastructures (AMI) and metering and fraud deterrence and detection technologies such as prepaid and tamper-proof electricity meters, macro-meters (communal metering), remote connection and disconnection systems, inspection and monitoring programs, data collection and calculation improvement, etc. A summary of international experiences, as well as conclusions and recommendations regarding the effectiveness, advantages and disadvantages of these approaches is presented and discussed.

Integration challenges of photovoltaic distributed generation on power distribution systems

A growing number of North American utilities are experiencing a significant proliferation of photovoltaic distributed generation (PV-DG). PV-DG integration can pose a challenge to distribution utilities due to the variety of impacts on several aspects of distribution systems planning and operations and the fact that hitherto distribution feeders have been designed and operated for supplying unidirectional power flow. The purpose of this paper is to discuss the impacts of utility-scale PV-DG on power distribution systems planning and operations, including those of steady state and dynamic nature. This paper discusses mitigation measures to address these impacts and reviews potential benefits and synergies of PV-DG.

Integration of Plug-in Electric Vehicles and distributed energy resources on power distribution systems

The utility industry is expecting a proliferation of Plug-in Electric Vehicles (PEV). This has prompted increasing interest in evaluating the potential impacts of PEVs on power distribution system planning and operations, as well as in proposing mitigation approaches that allow their seamless integration. In addition, there is a noticeable growth in the number of solar photovoltaic distributed generation (PV-DG) being interconnected to distribution feeders in North America and other regions. The rising penetration of PV-DG may also lead to important impacts on power distribution systems, particularly due to the intermittent nature of its output caused by cloud cover. As an emerging technology, Distributed Energy Storage (DES) aims to improve the reliability, efficiency, and controllability of the power distribution system and to facilitate the integration of distributed generations. This paper discusses the integration of all these technologies from a technical perspective and investigates how DES may be used as a means for mitigating the impacts of PEV charging and PV-DG interconnection. Results of simulations conducted on an actual distribution feeder are presented and discussed.

Integration of Photovoltaic Distributed Generation in the Power Distribution Grid

Numerous North American utilities are integrating growing numbers of investor-owned photovoltaic distributed generation (PV-DG) plants into their distribution systems to comply with state-mandated Renewable Portfolio Standards (RPS). Given the fact that distribution systems have been designed to be operated in a radial fashion, interconnection of PV-DG may lead to significant impacts on planning and operations that need to be studied to identify mitigation measures and ensure seamless integration. The purpose of this paper is to discuss impacts of PV-DG on power distribution systems planning and operations, including those of steady state and dynamic nature, with emphasis on utility-scale PV-DG. This paper also discusses mitigation measures to address these impacts and presents results of analyses conducted on real distribution feeders and other ramifications of their increased use in distribution networks, especially urban ones.

Applying self-healing schemes to modern power distribution systems

Self-healing schemes in the context of power distribution systems have the objective of performing fault location, isolation, and service restoration in an automated fashion, i.e., without (or with limited) distribution system operator and repair crew intervention. Some of the intrinsic benefits of this smart distribution technology are increased reliability due to outage duration reduction, more efficient use of personnel and resources (crews, operators, vehicles, etc), and increased operational flexibility. Reliability is naturally increased since less time is needed for locating and isolating faulted feeder areas, as well as for restoring customers located on healthy feeder sections. Self-healing schemes are an inherent part of the Smart Grid and are expected to play a fundamental role in modern and future distribution systems. It is worth noting that the switchgear technology (protective and switching devices, including adaptive protection), sensors, enterprise systems and communications infrastructures required for the implementation of self-healing schemes represent the basis for the execution of other smart distribution applications such as automated system reconfiguration and optimization. Therefore, a growing number of self-healing projects are being implemented by utilities as part of their power delivery modernization plans. This paper discusses the estimation of reliability benefits of self-healing schemes, with emphasis on Fault Location, Identification and Service Restoration (FLISR) applied to real distribution feeders.

Integration of pevs and PV-DG in power distribution systems using distributed energy storage — Dynamic analyses

Growing numbers of utilities are experiencing proliferation of Plug-in Electric Vehicles (PEV) and Photovoltaic Distributed Generation (PV-DG) in their distribution systems. Charging patterns of PEVs tend to increase the original day-time and evening peak demands of distribution feeders, while PV-DG units are highly intermittent energy sources. Therefore, the integration of large amount of PEVs and PV-DGs represents a significant challenge for distribution planning and operations. As an emerging technology, Distributed Energy Storage (DES) is a promising alternative to improve the reliability and efficiency of distribution systems. DES serves as an energy buffer to manage demand and supply fluctuations. Through proper control algorithms, DES has the potential to facilitate the integration of both, PEVs and PV-DG units. Previous works have studied the mitigation of steady state impacts of PEVs and PV-DG units by using DES systems. However, this topic has not been fully investigated from a dynamic analysis perspective. This paper discusses the utilization of DES to alleviate dynamic impacts of PEVs and PV-DG units on power distribution systems. This alternative is analyzed by using models of PV-DGs, PEV and DES developed in PSCAD. Results of dynamic simulations, including voltage profiles at critical points on a test distribution feeder and operations of Load Tap Changer (LTC) are presented and discussed. Simulation results show the potential of DES for improving dynamic performance of distribution feeders with PEVs and PV-DGs proliferation.

Building Resilient Integrated Grids: One neighborhood at a time.

The microgrid, as defined by the U.S. Department of Energy, is a group of interconnected loads and distributed energy resources (DERs) with clearly defined electrical boundaries that acts as a single controllable entity with respect to the electric utility grid. DERs consist of distributed generation (DG) and distributed energy storage (DES) installed at utility facilities, e.g., distribution substations, DG sites, or consumer premises. A microgrid must have three distinct characteristics: 1) the electrical boundaries must be clearly defined, 2) there must be control systems in place to dispatch DERs in a coordinated fashion and maintain voltage and frequency within acceptable limits, and 3) the aggregated installed capacity of DERs and controllable loads must be adequate to reliably supply the critical demand. The microgrids may be operated in two modes.

Sharing the Ride of Power: Understanding Transactive Energy in the Ecosystem of Energy Economics

Advocates of Transactive Energy (TE) make arguments for the integration of distributed energy resources (DERs) into a market environment from the standpoint of overall energy economics, customer choice, facilitating technology adoption, and encouraging innovation. At a very high level, this is reasonable given the rapid development and adoption of personalized transactions via the web and mobile computing in many domains and the equally rapid proliferation of DERs, at least in some geographic areas.

Increasing penetration of Distributed Generation with meshed operation of distribution systems

Electric distribution systems are traditionally operated in a radial manner. In order to accommodate the increasing penetration levels of Distributed Generation (DG), meshed operation of distribution systems is investigated in this paper. Different limiting factors for increasing penetration levels of DGs are discussed; then, a methodology that determines maximum DG penetration level based on bus voltage and line current constraints is described. Alternative meshed operation of distribution systems, viewed as a more long-term systematic solution to increase maximum allowable DG penetration, can then be evaluated using the described metrics. Results for a 69 bus test case are presented for the radial system as well as for select meshed configurations. The obtained results verify the ability of meshed networks to accommodate proliferation of DGs.