14 research outputs found

    Design and implementation of CCNY DC microgrid testbed

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    This paper presents the design, control, energy management, and implementation of the City College of New York (CCNY) direct current (DC) microgrid laboratory testbed. This facility was custom designed and implemented by researchers at CCNY with minimal off-the-shelf components to enable significant flexibility and reconfiguration capability. The microgrid consists of renewable energy resources, energy storage system and controllable loads, and can operate in either a grid-connected or an islanded mode. The design steps, requirements, and results of the developed testbed were discussed. Moreover, several operational scenarios were tested. The experimental results verify the applicability and flexibility of the developed microgrid testbed

    A Hybrid State/Event Driven Communication-based Control for DC Microgrids

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    The U.S. electric power industry is undergoing unprecedented changes triggered by the growing electricity demand, and the national efforts to reduce greenhouse gas emissions. Moreover, there is a call for increased power grid resiliency, survivability and self-healing capabilities. As a result of these challenges, the smart grid concept emerged. One of the main pillars of the smart grid is microgrids. In this thesis, the technical merits of clustering multiple microgrids during blackouts on the overall stability and supply availability have been investigated. We propose to use the existing underground distribution grid infrastructure, if applicable, during blackouts to form microgrid clusters. The required control hierarchy to manage microgrid clusters, and communicate with the Distribution Network Operator (DNO) has been discussed. A case study based on IEEE standard distribution feeders, and two microgrid models, has been presented. Results show that clustering microgrids help improve their performance and that the microgrid total rotating mass inertia has a direct impact on the overall stability of a microgrid cluster. The design and control of individual microgrids have been given genuine attention in this thesis since they represent the main resiliency building block in the proposed clustering approach. Therefore, a considerable portion of this thesis is dedicated to present studies and results of designing, simulating, building and testing a direct current (DC) microgrid. The impact of various operational scenarios on DC microgrid performance has been thoroughly discussed. Specifically, this thesis presents the design and implementation of the City College of New York (CCNY) DC microgrid laboratory testbed. The experimental results verify the applicability and flexibility of the developed microgrid testbed. An autonomous communication-based centralized control for DC microgrids has been developed and implemented. The proposed controller enables a smooth transition between various operating modes. Finite state machine (FSM) has been used to mathematically describe the various operating modes (states), and the events that may lead to mode changes (transitions). Therefore, the developed centralized controller aims at optimizing the performance of MG during all possible operational scenarios, while maintaining its reliability and stability. Results of selected drastic cases have been presented, which verified the validity and applicability of the proposed controller. Since the proposed microgrid controller is communication-based, this thesis investigates the effect of wireless communication technologies latency on the performance of DC microgrids during islanding. Mathematical models have been developed to describe the microgrid behavior during communication latency. Results verify the accuracy of the developed models and show that the impact may be severe depending on the design, and the operational conditions of the microgrid just before the latency occurs. We propose to use the existing underground distribution grid infrastructure, if applicable, during blackouts to form microgrid clusters. The required control hierarchy to manage microgrid clusters, and communicate with the Distribution Network Operator (DNO) has been discussed. A case study based on IEEE standard distribution feeders, and two microgrid models, has been presented. Results show that clustering microgrids help improve their performance and that the microgrid total rotating mass inertia has a direct impact on the overall stability of a microgrid cluster. The design and control of individual microgrids have been given genuine attention in this thesis since they represent the main resiliency building block in the proposed clustering approach. Therefore, a considerable portion of this thesis is dedicated to present studies and results of designing, simulating, building and testing a direct current (DC) microgrid. The impact of various operational scenarios on DC microgrid performance has been thoroughly discussed. Specifically, this thesis presents the design and implementation of the City College of New York (CCNY) DC microgrid laboratory testbed. The experimental results verify the applicability and flexibility of the developed microgrid testbed. An autonomous communication-based centralized control for DC microgrids has been developed and implemented. The proposed controller enables a smooth transition between various operating modes. Finite state machine (FSM) has been used to mathematically describe the various operating modes (states), and the events that may lead to mode changes (transitions). Therefore, the developed centralized controller aims at optimizing the performance of MG during all possible operational scenarios, while maintaining its reliability and stability. Results of selected drastic cases have been presented, which verified the validity and applicability of the proposed controller. Since the proposed microgrid controller is communication-based, this thesis investigates the effect of wireless communication technologies latency on the performance of DC microgrids during islanding. Mathematical models have been developed to describe the microgrid behavior during communication latency. Results verify the accuracy of the developed models and show that the impact may be severe depending on the design, and the operational conditions of the microgrid just before the latency occurs

    ICT-Enabled Control and Energy Management of Community Microgrids for Resilient Smart Grid Operation

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    Our research has focused on developing novel controllers and algorithms to enhance the resilience of the power grid and increase its readiness level against major disturbances. The U.S. power grid currently encounters two main challenges: (1) the massive and extended blackouts caused by natural disasters, such as hurricane Sandy. These blackouts have raised a national call to explore innovative approaches for enhanced grid resiliency. Scrutinizing how previous blackouts initiated and propagated throughout the power grid, the major reasons are lack of situational awareness, lack of real-time monitoring and control, underdeveloped controllers at both the transmission and distribution levels, and lack of preparation for major emergencies; and (2) the projected high penetration of renewable energy resources (RES) into the electric grid, which is mainly driven by federal and state regulatory actions to reduce GHG emissions from new and existing power plants, and to encourage Non Wire Solutions (NWS). RESs are intermittent by nature imposing a challenge to forecast load and maintain generation/demand balance. The conceived vision of the smart grid is a cyber-physical system that amalgamates high processing power and increased dependence on communication networks to enable real-time monitoring and control. This will allow for, among other objectives, the realization of increased resilience and self-healing capabilities. This vision entails a hierarchical control architecture in which a myriad of microgrids, each locally controlled at the prosumer level, coordinates within the distribution level with their correspondent distribution system operator (i.e. area controllers). The various area controllers are managed by a Wide Area Monitoring, Protection and Control operator. The smart grid has been devised to address the grid main challenges; however, some technical barriers are yet to be overcome. These barriers include the need to develop new control techniques and algorithms that enable flexible transitions between operational modes of a single controller, and effective coordination between hierarchical control layers. In addition, there is a need to understand the reliability impacts of increased dependence on communication networks. In an attempt to tackle the aforementioned barriers, in my work, novel controllers to manage the prosumer and distribution networks were developed and analyzed. Specifically, the following has been accomplished at the prosumer level, we: 1) designed and implemented a DC MG testbed with minimal off-the-shelf components to enable testing new control techniques with significant flexibility and reconfiguration capability; 2) developed a communication-based hybrid state/event driven control scheme that aims at reducing the communication load and complexity, processor computations, and consequently system cost while maintaining resilient autonomous operation during all possible scenarios including major emergencies; and 3) analyzed the effect of communication latency on the performance of centralized ICT-based DC microgrids, and developed mathematical models to describe the behavior of microgrids during latency. In addition, we proposed a practical solution to mitigate severe impacts of latency. At the distribution level, we: 1) developed a model for an IEEE distribution test network with multiple MGs integrated[AM1] [PL2] ; 2) developed a control scheme to manage community MGs to mitigate RES intermittency and enhance the grid resiliency, deferring the need for infrastructure upgrade; and 3) investigated the optimal placement and operation of community MGs in distribution networks using complex network analysis, to increase distribution networks resilience. At the transmission level (T.L), New York State T.L was modeled. A case study was conducted on Long Island City to study the impact of high penetration of renewable energy resources on the grid resilience in the transmission level. These research accomplishments should pave the way and help facilitate a smooth transition towards the future smart grid.

    Bidirectional Battery Interface in Standalone Solar PV System for Electrification in Rural Areas

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    In a standalone photovoltaic (PV) system, a bidirectional DC converter (BDC) is needed to prevent the battery from damage caused by DC bus voltage variation. In this paper, BDC was applied in a standalone solar PV system to interface the battery with a DC bus in a standalone PV system. Therefore, its bidirectional power capability was focused on improving save battery operation while maintaining high power quality delivery. A non-isolated, buck and boost topology for the BDC configuration was used to interface the battery with the DC bus. PID controller-based control strategy was chosen for easy implementation, high reliability, and high dynamic performance. A simulation was conducted using MATLAB Simulink program. The simulation results show that the implementation of the BDC controller can maintain the DC bus voltage to 100 V, have high efficiency at 99.18% in boost mode and 99.48% in buck mode. To prevent the battery from overcharging condition, the BDC stops the charging process and then works as a voltage regulator to maintain the DC bus voltage at reference value

    Communication Based Control for DC Microgrids

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    Centralized communication-based control is one of the main methods that can be implemented to achieve autonomous advanced energy management capabilities in DC microgrids. However, its major limitation is the fact that communication bandwidth and computation resources are limited in practical applications. This can be often improved by avoiding redundant communications and complex computations. In this paper, an autonomous communication-based hybrid state/event driven control scheme is proposed. This control scheme is hierarchical and heuristic, such that on the primary control level, it encompasses state-driven local controllers, and on the secondary control level, an event-driven MG centralized controller (MGCC) is used. This heuristic hybrid control system aims at reducing the communication load and complexity, processor computations, and consequently system cost while maintaining reliable autonomous operation during all possible scenarios. A mathematical model for the proposed control scheme using Finite State Machines (FSM) has been developed and used to cover all the possible modes/sub-modes of operation, and assure seamless transitions among them during various events. Results of some case studies involving severe operational scenarios were presented and discussed. Results verify the validity and effectiveness of the proposed communication-based control scheme

    Experimental Testbed for Load Control on an AC/DC Microgrid

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    Microgrids are becoming increasingly popular in the world of power systems to mitigate the effects of high impact events that can lead to blackouts. They are also integral to including distributed renewable energy generation in the grid. A major challenge in effective implementation of DC microgrids, in particular, is the lack of adequate testing platforms. This thesis primarily aims to build a testbed of an AC/DC microgrid in a laboratory environment using programmable sources and loads. A central measurement and control platform is developed to monitor and actuate all the loads from a single unit. While this enhances data measurement, it also enables simultaneous operation of the loads. The use of such state-of-the-art technology gives a better understanding of integration of microgrids into existing power systems. Having a microgrid testbed allows for the study of the control of hybrid AC/DC microgrids under various operating conditions. This thesis uses this capability to test a load shedding problem on a 3 bus and 4 bus AC/DC microgrid. An algorithmic solution to the problem is proposed and implemented in hardware. The results are compared to more traditional control strategies. The microgrid testbed developed in this thesis can prove integral to future research work on AC/DC microgrid controllers. The central control platform can also be used for future research into the effect of communication networks on the performance of the microgrid and power system as a whole.M.S., Electrical Engineering -- Drexel University, 201

    Applications of Complex Network Analysis in Electric Power Systems

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    This paper provides a review of the research conducted on complex network analysis (CNA) in electric power systems. Moreover, a new approach is presented to find optimal locations for microgrids (MGs) in electric distribution systems (EDS) utilizing complex network analysis. The optimal placement in this paper points to the location that will result in enhanced grid resilience, reduced power losses and line loading, better voltage stability, and a supply to critical loads during a blackout. The criteria used to point out the optimal placement of the MGs were predicated on the centrality analysis selected from the complex network theory, the center of mass (COM) concept from physics, and the recently developed controlled delivery grid (CDG) model. An IEEE 30 bus network was utilized as a case study. Results using MATLAB (MathWorks, Inc., Nattick, MA, USA) and PowerWorld (PowerWorld Corporation, Champaign, IL, USA) demonstrate the usefulness of the proposed approach for MGs placement

    Optimal Control of CHP Plant Integrated with Load Management on HVAC System in Microgrid

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    © 2019 IEEE. Combined heat and power (CHP) is a typical community owned distributed generation solution in microgrid development. In this work, the ratio between the electricity output and the thermal output is controlled, along with the demand side load management, so as to minimize the overall microgrid operational cost. A model is established for the energy cost of a smart building system, which includes factors such as the real time electricity pricing, the capacity and constraints within CHP operation, the operating condition of heating, ventilation, and air - conditioning (HVAC), and the indoors air temperature of the smart building. Efficient CHP operation and HVAC load management under demand response (DR) are determined through optimization. A case study is carried out to examine the effectiveness of the proposed strategy

    New energy delivery models for communities: how utilities can transform their delivery models to meet the needs of their stakeholders, short and long term

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    Society has done little to modernize energy delivery or take advantage of proven, commonly available technology. In the past, change was driven by regulated entities with an exclusive franchise. Today, however, disruptors come from outside of the power sector – a phenomenon that is changing the grid. The grid of the future will provide an open platform, similar to a state-owned interstate that allows access to all. Generation, storage, and load elements will be self-registering building blocks, similar to the concept of all ‘Lego’ sets being compatible. Elements will be connected by providers or even consumers, they will self-register, and interact with each other optimizing grid performance with respect to economics, efficiency, adequacy, and reliability. The ubiquitous grid will encompass not only electric, gas, and water, but other services that either we’ve already come to rely upon or haven’t even considered yet. Is this farewell to the grid as we know it? The exclusive franchise model that has been around for more than a century might not be as long lived as expected

    A Case Study on Grid Impacts of Electric Vehicles on New York City Power Grid

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    The U.S. electric power industry is anticipating a huge increase in electricity demand in the future due to reformation of the transportation industry. In this work, we focus on electric cars and their impact on the transportation industry as well as the electric grid. The increase in number of electric cars over the years and their growing number indicates that in the future, transportation means are going to largely depend upon electricity to achieve cost and environmental benefits. In other words, in future, the transportation will be impacting the electric grid and vice versa. The surge in electric vehicles on streets particularly in New York City requires the charging infrastructure to support the electricity demand, and mandates proper planning for the electric power grids to keep them upgraded and resilient enough to support the growth in electric vehicles load. In this thesis, the historical minimum and peak load demand data of areas served by Consolidated Edison, an energy company, in New York City have been collected, processed and analyzed to analyze the performance of the future electric grid. The available data of electric vehicles and parking spaces in different regions of New York City were analyzed to study the impact of electric vehicles on future power infrastructure in the City. Also, the charging and parking behavior of vehicles in New York City was analyzed to determine how the time of charging will impact the electricity demand at the different hours of the day at different locations in New York City, and to find ways to minimize the demand in areas where the electric grid network is congested. It was also concluded that in the future, after phasing out of a portion of the gasoline fleets, electric vehicles will be able help to reduce the greenhouse gasses and conserve the environment and help the City and State of New York’s initiatives to achieve their goals of sustainability. Last but not least, more than eighty percent of the New York City electric infrastructure is underground, which means when the demand in peak hours of summer requires upgrading and increasing the feeder capacity, it will require massive capital investment. So, electric vehicles can be used as Energy Storage Resources and can be utilized if needed to shave the peak demand. The data has been analyzed to find out the kind of infrastructure required and the potential locations in different areas of New York City to use the electric vehicles as distributed energy storage resources
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