Modeling and analysis of a DC electrical system and controllers for implementation of a grid-interactive building

As the penetration of photovoltaic (PV) systems on building rooftops increases, the accumulated effect of the rooftop PV power outputs on electric network operation is no longer negligible. Energy storage resources (ESRs) have been used to smooth PV power outputs, particularly when building load becomes low. In commercial buildings, the batteries of plug-in electric vehicles (PEVs) can be regarded as distributed ESRs. This paper proposes a DC electrical system in a commercial building that enables PEVs to compensate for rooftop PV power fluctuation and participate in tracking signals for grid frequency regulation (GFR). The proposed building system and associated controllers are modeled considering steady-state and dynamic operations of the PV system and PEV batteries. Simulation case studies are conducted to demonstrate the performance of the proposed building system under various conditions, determined by such factors as the maximum voltage, minimum state-of-charge, and desired charging end-time of PEVs batteries. ? 2017 by the authors; licensee MDPI, Basel, Switzerland.112Ysciescopu

Analysis and Experimental Implementation of Grid Frequency Regulation using Behind-the-Meter Batteries Compensating for Fast Load Demand Variations

This paper proposes a new grid frequency regulation (GFR) scheme using behind-the-meter battery energy storage systems (BESSs). The fast dynamic responses of the electrical BESSs enable buildings to compensate for the high-frequency components of load demand variations, through direct load control (DLC). An electrical system in a building, along with its building-level and device-level controllers, is considered to address the difficulties in the application of DLC, especially in communicating with several small-scale BESSs. A small-signal analysis is carried out using the aggregated responses of the generators and the DLC-enabled buildings to investigate the proposed GFR scheme, particularly with respect to the feedback controllers for the buildings. Simulation studies are performed using a test grid for various penetrations of the DLC-enabled buildings, and the test grid is implemented using a laboratory-scale microgrid. The proposed GFR is effective in reducing the frequency deviations and required reserve capacity of the generators, which is achieved by making small variations in the state-of-charge of the behind-the-meter battery.1172Ysciescopu

A Comprehensive Method For Coordinating Distributed Energy Resources In A Power Distribution System

Utilities, faced with increasingly limited resources, strive to maintain high levels of reliability in energy delivery by adopting improved methodologies in planning, operation, construction and maintenance. On the other hand, driven by steady research and development and increase in sales volume, the cost of deploying PV systems has been in constant decline since their first introduction to the market. The increased level of penetration of distributed energy resources in power distribution infrastructure presents various benefits such as loss reduction, resilience against cascading failures and access to more diversified resources. However, serious challenges and risks must be addressed to ensure continuity and reliability of service. By integrating necessary communication and control infrastructure into the distribution system, to develop a practically coordinated system of distributed resources, controllable load/generation centers will be developed which provide substantial flexibility for the operation of the distribution system. On the other hand, such a complex distributed system is prone to instability and black outs due to lack of a major infinite supply and other unpredicted variations in load and generation, which must be addressed. To devise a comprehensive method for coordination between Distributed Energy Resources in order to achieve a collective goal, is the key point to provide a fully functional and reliable power distribution system incorporating distributed energy resources. A road map to develop such comprehensive coordination system is explained and supporting scenarios and their associated simulation results are then elaborated. The proposed road map describes necessary steps to build a comprehensive solution for coordination between multiple agents in a microgrid or distribution feeder.\u2

Plug-in electric vehicle deployment and integration with the electric grid

Key battery, semiconductor, and software technologies have sufficiently progressed over the past few decades to enable viable plug-in electric vehicle (PEV) alternatives to conventional vehicles. Alternatives to petroleum-based fuels for transportation are sought to address concerns over energy security, foreign oil derived U.S. trade deficits, oil related geopolitical entanglements, and emissions. The various types of PEVs have substantially different characteristics. The types and key attributes of PEVs, charging standards, and charging locations are described. The likely scenario for PEV-Grid interactions over the next decade is synthesized from the analysis of the technologies available to and circumstances of vehicle manufacturers, utilities, and supplier firms. PEV adoption considerations are evolving. Many lessons have been learned from the first generation of PEVs that were introduced starting in late 2010. Technology, market, and policy drivers of emerging trends in the diffusion of PEVs are explored more in-depth. PEVs as electric loads are unique in that they are large, flexible, and intelligent. These attributes can not only provide utilities a new source of revenue, but also improve grid stability and economics. Actions, technologies, and policies that utilities can deploy to increase adoption are discussed. Actions are explored to make the overall PEV ownership experience superior to a conventional vehicle. This dissertation also describes research of the capability for PEVs in Vehicle to Home (V2H) scenarios, where the vehicle acts as a residential battery storage system and/or a backup generator in a residential microgrid configuration during a grid outage. Residential energy data collected from a smart grid testbed is used with a custom PEV model to assess the performance (in terms of duration and power output) of a BEV or PHEV used for backup power. Our earlier results quantify the extent to which photovoltaic (PV) generation and the characteristics of a PEV (battery size, gasoline availability) affect the backup duration during an electric grid outage. Strategies to further increase backup duration and non-continuous self-sustaining off-grid alternatives were found in our early V2H research. Varied amounts of load curtailment and PHEV engine-generator control improvements are modeled in subsequent research.Electrical and Computer Engineerin

Open-Source, Open-Architecture SoftwarePlatform for Plug-InElectric Vehicle SmartCharging in California

This interdisciplinary eXtensible Building Operating System–Vehicles project focuses on controlling plug-in electric vehicle charging at residential and small commercial settings using a novel and flexible open-source, open-architecture charge communication and control platform. The platform provides smart charging functionalities and benefits to the utility, homes, and businesses.This project investigates four important areas of vehicle-grid integration research, integrating technical as well as social and behavioral dimensions: smart charging user needs assessment, advanced load control platform development and testing, smart charging impacts, benefits to the power grid, and smart charging ratepayer benefits

Optimisation-based Approaches for Evaluating the Aggregation of EVs and PVs in Unbalanced Low-Voltage Networks

214 p.In the near future, it is expected that the distribution system operators face different technical challenges derived from the massification of electric mobility and renewable energy sources in the low voltage networks. The purpose of this thesis is to define different smart coordination strategies among different agents involved in the low voltage networks such as the distribution system operator, the aggregators and the end-users when significant penetration levels of these resources are adopted. New models for representing the uncertainty of the photovoltaic output power and the connection of the electric vehicles are introduced. A new energy boundary model for representing the flexibility of electric vehicles is also proposed. In combination with the above models, four optimisation models were proposed as coordination strategies into three different approaches: individual, population, and hybrid. The first model was defined at the aggregator level, whereas the other models were proposed at the distribution system operator level. Complementary experimental cases about the proposed optimisation model in the individual-based approach and the quadratic formulation in the hybrid approach for the PV power curtailment were carried out to test its response in real-time. Simulations results demonstrated that the proposed coordination strategies could effectively manage critical insertion levels of electric vehicles and photovoltaic units in unbalanced low voltage networks

State-of-the-Art Assessment of Smart Charging and Vehicle 2 Grid services

Electro-mobility – especially when coupled smartly with a decarbonised grid and also renewable distributed local energy generation, has an imperative role to play in reducing CO2 emissions and mitigating the effects of climate change. In parallel, the regulatory framework continues to set new and challenging targets for greenhouse gas emissions and urban air pollution. • EVs can help to achieve environmental targets because they are beneficial in terms of reduced GHG emissions although the magnitude of emission reduction really depends on the carbon intensity of the national energy mix, zero air pollution, reduced noise, higher energy efficiency and capable of integration with the electric grid, as discussed in Chapter 1. • Scenarios to limit global warming have been developed based on the Paris Agreement on Climate Change, and these set the EV deployment targets or ambitions mentioned in Chapter 2. • Currently there is a considerable surge in electric cars purchasing with countries such as China, the USA, Norway, The Netherlands, France, the UK and Sweden leading the way with an EV market share over 1%. • To enable the achievement of these targets, charging infrastructures need to be deployed in parallel: there are four modes according to IEC 61851, as presented in Chapter 2.1.4. • The targets for SEEV4City project are as follow: o Increase energy autonomy in SEEV4-City sites by 25%, as compared to the baseline case. o Reduce greenhouse gas emissions by 150 Tonnes annually and change to zero emission kilometres in the SEEV4-City Operational Pilots. o Avoid grid related investments (100 million Euros in 10 years) by introducing large scale adoption of smart charging and storage services and make existing electrical grids compatible with an increase in electro mobility and local renewable energy production. • The afore-mentioned objectives are achieved by applying Smart Charging (SC) and Vehicle to Grid (V2G) technologies within Operational Pilots at different levels: o Household. o Street. o Neighbourhood. o City. • SEEV4City aims to develop the concept of 'Vehicle4Energy Services' into a number of sustainable business models to integrate electric vehicles and renewable energy within a Sustainable Urban Mobility and Energy Plan (SUMEP), as introduced in Chapter 1. With this aim in mind, this project fills the gaps left by previous or currently running projects, as reviewed in Chapter 6. • The business models will be developed according to the boundaries of the six Operational Pilots, which involve a disparate number of stakeholders which will be considered within them. • Within every scale, the relevant project objectives need to be satisfied and a study is made on the Public, Social and Private Economics of Smart Charging and V2G. • In order to accomplish this work, a variety of aspects need to be investigated: o Chapter 3 provides details about revenue streams and costs for business models and Economics of Smart Charging and V2G. o Chapter 4 focuses on the definition of Energy Autonomy, the variables and the economy behind it; o Chapter 5 talks about the impacts of EV charging on the grid, how to mitigate them and offers solutions to defer grid investments; o Chapter 7 introduces a number of relevant business models and considers the Economics of Smart Charging and V2G; o Chapter 8 discusses policy frameworks, and gives insight into CO2 emissions and air pollution; o Chapter 9 defines the Data Collection approach that will be interfaced with the models; o Chapter 10 discusses the Energy model and the simulation platforms that may be used for project implementation

Design and development of energy management system for smart homes and buildings

The smart grid, as the next generation of power grid, has redefined the positions of the homes and buildings in the contexts of a whole energy system. With the increasing installation of Distributed Energy Resources (DERs) and retention of Electric Vehicles (EVs) and Plug-in Hybrid Electric Vehicles (PHEVs), the energy system of homes and buildings in power distribution network is becoming more and more complex. In order to find the efficient and effective way for managing the appliances and DERs in smart homes and buildings through the Energy Management System (EMS), the pathway of the thesis is to investigate the optimisation and control approaches of EMS from controlling the loads within home, to fully optimising the operation of both loads and DERs in smart home, and at last coordinating the EMSs in the buildings through the aggregator

Small-Scale Smart Grid Construction and Analysis

The smart grid (SG) is a commonly used catch-phrase in the energy industry yet there is no universally accepted definition. The objectives and most useful concepts have been investigated extensively in economic, environmental and engineering research by applying statistical knowledge and established theories to develop simulations without constructing physical models. In this study, a small-scale version (SSSG) is constructed to physically represent these ideas so they can be evaluated. Results of construction show data acquisition three times more expensive than the grid itself although mainly due to the incapability to downsize 70% of data acquisition costs to small-scale. Experimentation on the fully assembled grid exposes the limitations of low cost modified sine wave power, significant enough to recommend pure sine wave investment in future SSSG iterations. Findings can be projected to full-size SG at a ratio of 1:10, based on the appliance representing average US household peak daily load. However this exposes disproportionalities in the SSSG compared with previous SG investigations and recommended changes for future iterations are established to remedy this issue. Also discussed are other ideas investigated in the literature and their suitability for SSSG incorporation. It is highly recommended to develop a user-friendly bidirectional charger to more accurately represent vehicle-to-grid (V2G) infrastructure. Smart homes, BEV swap stations and pumped hydroelectric storage can also be researched on future iterations of the SSSG

PV Charging and Storage for Electric Vehicles

Electric vehicles are only ‘green’ as long as the source of electricity is ‘green’ as well. At the same time, renewable power production suffers from diurnal and seasonal variations, creating the need for energy storage technology. Moreover, overloading and voltage problems are expected in the distributed network due to the high penetration of distributed generation and increased power demand from the charging of electric vehicles. The energy and mobility transition hence calls for novel technological innovations in the field of sustainable electric mobility powered from renewable energy. This Special Issue focuses on recent advances in technology for PV charging and storage for electric vehicles