CINELDI Annual Report 2020

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Electrical and Computer Engineering Annual Report 2017

Early Career Awards Faculty Directory Faculty Highlights Special Report: Mobility at Michigan Tech Faculty Publications Staff Profile & Directory Graduate Student Research Accelerated Master\u27s Degree Graduate Student Awards & Degrees Undergraduate Highlights Senior Design Enterprise Undergraduate Student Awards & Advisory Grants & Contracts Departmental Statistics A Pioneer\u27s Storyhttps://digitalcommons.mtu.edu/ece-annualreports/1001/thumbnail.jp

Frequency and Voltage Control of a Grid of Microgrids

The rapid proliferation of Distributed Energy Resources (DERs) in recent years has resulted in significant technical challenges for power system operators and planners, mainly due to the particular characteristics of some of these systems that are interfaced with converters that alter the dynamic behavior of typically power systems. To accommodate the increasing penetration of DERs in power systems, microgrids have been formed to facilitate their integration. The operation of these microgrids could be further enhanced by interconnecting them to satisfy the overall system demand, and improve their stability if suitable control schemes are implemented. The control of microgrids has been extensively studied; however, coordinated operation, dynamics, and control of a grid that includes interconnected microgrids have not been sufficiently addressed in the literature, and thus this is the focus of this thesis. In the first stage of the thesis, a new microgrid interface based on Virtual Synchronous Generators (VSGs) is proposed to control the power exchange of interconnected ac and dc microgrids, and provide frequency support, voltage regulation, and virtual inertia for individual microgrids and the host grid as required, to improve both frequency and voltage dynamics for the overall system. Thus, a hierarchical distributed control technique is proposed, where the primary control of interfacing VSGs provides adaptive inertia for the ac systems, while a secondary distributed control of the system regulates the frequency and the voltages of the host grid and the interconnected microgrids, based on a consensus technique with limited information about the overall system. The proposed controller shares the total system load among the grid and microgrids, while minimizing the overall frequency and voltage deviations in all interconnected systems. The proposed interface and the controller are implemented, tested, and validated in detailed simulations for a grid-of-microgrids system. In the second stage of the thesis, an adaptive active power droop controller and voltage setpoint control in isolated microgrids for optimal frequency response and stability after disturbances is first proposed and presented, and then applied to the coordinated control of interconnected microgrids. The control scheme involves an optimal and model predictive control approach, which continuously adjusts the active power droop gains and the voltage setpoints of Distributed Energy Resources (DERs) to maintain the frequency of the system within acceptable limits, and enhance the primary frequency response of the system, while taking into account the active power sensitivity of the microgrid loads to the system's operating voltage. The proposed approach is also implemented, tested, validated, and compared via detailed simulations in a microgrid benchmark system and the developed grid-of-microgrids test system. The results demonstrate that the proposed VSG controlled interfaces limit severe frequency deviations during disturbances, and allow proper power sharing among the microgrids without causing significant power transients for the ac/dc systems, compared to existing techniques. Furthermore, the proposed secondary distributed and centralized frequency and voltage controllers maintain the power balance of the interconnected systems and regulate the microgrids' frequencies and dc voltages to nominal values, compared to conventional frequency controllers; however, the distributed control approach shows better overall frequency and dc-voltage dynamics and regulation than the centralized control approach

Contributions to Decision Support Systems, Energy Economics, and Shared Micromobility Research

This thesis includes research articles on Decision Support Systems, Energy Informatics, and Economics, Shared Micromobility, and Digital Study Assistance. For many years, established Information Systems (IS) scholars have called for solutionoriented research to address the most pressing problems of climate change. In this context, this thesis summarizes three consecutive research articles that present the multi-year development of a Decision Support System (DSS) for the energy transformation of the building sector. The DSS Nano Energy System Simulator (NESSI) was developed using Design Science Research guidelines and was further field tested and evaluated with stakeholders. In the discipline of Energy Informatics, a research article is presented that provides a morphological box for the classification of real microgrids. Next, a research article is presented that used regression analysis to investigate the influences of factors on residential photovoltaic system prices and revealed spatial price heterogeneity in Germany. Three research articles are outlined in the Shared Micromobility field. The first article uses a multi-year dataset of location data to examine the spatial and temporal use of e-scooters in Berlin. The second article builds on this and quantifies the influences of various factors such as weather, Covid-19 lockdowns, and other socio-economic parameters on the use of three micromobility concepts. The third article uses a web content mining process to collect a large dataset of police reports on e-scooter accidents. It analyzes risk factors as well as accident implications for riders. A research article on the requirements analysis and development of a digital study assistant concludes this thesis. Here, quantitative surveys and qualitative expert interviews are used to collect requirements from higher education institution stakeholders for a digital study assistant. In addition, developing a study assistance prototype is demonstrated and tested in the field

Voltage-based droop control of converter-interfaced distributed generation units in microgrids

Sinds de laatste jaren is er in het elektrisch energienet een enorme toevloed aan kleine decentrale generatoren, vaak op basis van hernieuwbare energiebronnen. De distributienetten werden echter niet gebouwd om injectie van energie toe te laten. Hierdoor komen steeds meer problemen in de distributienetten voor, zoals bijvoorbeeld overspanningen tijdens zonnige periodes. Dit bemoeilijkt de verdere integratie van hernieuwbare energiebronnen. In deze context werd het microgrid concept voorgesteld om een gecoordineerde koppeling van decentrale generatoren in het net mogelijk te maken. Microgrids zijn kleine subnetten die lokaal hun elementen, zoals de generatoren en de lasten regelen om bepaalde doeleinden te bereiken. Ze kunnen bijvoorbeeld de spanningsregeling in hun net verzorgen of als een geheel meespelen in de energiemarkten. Een karakteristiek van microgrids is dat ze onafhankelijk van het net kunnen werken, in het zogenaamde eilandbedrijf. In eilandbedrijf moeten het verbruik en de opwekking op ieder tijdstip op elkaar afgesteld zijn. Aangezien microgrids erg verschillende eigenschappen hebben van het gewone elektrisch net, zijn hier specifieke regelstrategieen voor vereist. In deze doctoraatsverhandeling wordt een dergelijke regelstrategie uitgewerkt, de zogenaamde spanningsgebaseerde droop (proportionele) regeling. Het spanningsniveau wordt als de niet-conventionele parameter gebruikt om het microgrid te regelen