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Raeey Regassa

Bio: Raeey Regassa is an academic researcher from Georgia Institute of Technology. The author has contributed to research in topics: AC power & Voltage regulation. The author has an hindex of 5, co-authored 5 publications receiving 75 citations.

Papers
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Proceedings ArticleDOI
10 Mar 2015
TL;DR: In this paper, the authors used OpenDSS to simulate a distribution network (feeder J1 located in the northeastern United States and enhanced by thirteen photovoltaic (PV) systems and calculate the time-series steady-state power flow of the distribution network when PV systems generate or absorb reactive power.
Abstract: Grid-connected photovoltaic (PV) systems with relatively high capacity effectively reduce peak load, but because of their reverse power flow, they can cause overvoltage along a feeder that can exceed five percent of the rated voltage Modern PV systems with the capability of Volt/Var control can mitigate overvoltage by either injecting or absorbing reactive power Thus, the objectives of this study are to (1) model a distribution network (feeder J1 located in the northeastern United States and enhanced by thirteen PV systems) using OpenDSS; (2) use actual collected load profile data as input data to the simulation model and PV generation output data at 15-minute intervals; and (3) calculate the time-series steady-state power flow of the distribution network when PV systems generate or absorb reactive power Finally, it addresses overvoltage resulting from the deployment of high-capacity grid-connected renewable PV systems and mitigation techniques for such overvoltage issues, particularly Volt/Var management and control

32 citations

Proceedings ArticleDOI
01 Sep 2014
TL;DR: In this article, the authors proposed a genetic algorithm with an objective function that minimizes voltage variations caused by the installation of DG systems, near-optimally allocates the locations and the capacities of DG system either with or without the capability of volt/var control on a distribution network at peak load, and analyzes their impact on the improvement of the voltage profile along the feeder.
Abstract: One of the main concerns of utilities is overvoltage along their feeders when they enhance their networks by various distributed generation (DG) systems. The objective of this study is (1) to near-optimally allocate locations and capacities of DG systems on distribution networks at peak load and (2) to analyze the impact of DG inverters with the capability of volt/var control on the improvement of the voltage profile along the feeder during steady state. This study proposes a genetic algorithm with an objective function that minimizes voltage variations caused by the installation of DG systems, near-optimally allocates the locations and the capacities of DG systems either with or without the capability of volt/var control on a distribution network at peak load, and analyzes their impact on the improvement of the voltage profile along the feeder.

15 citations

Proceedings ArticleDOI
14 Jun 2015
TL;DR: This study models a distribution network enhanced by the DG system, particularly the photovoltaic (PV) system, in the Digital Simulation and Electrical Network Calculation Program (DIgSILENT) and the Open Distribution System Simulator (OpenDSS).
Abstract: As distributed generation (DG) has been deployed in radial distribution networks, it changes their steady-state and transient behavior. To analyze the potential impact of DG on the distribution network, this study models a distribution network enhanced by the DG system, particularly the photovoltaic (PV) system, in the Digital Simulation and Electrical Network Calculation Program (DIgSILENT) and the Open Distribution System Simulator (OpenDSS). As a first case study, this study initially examines load models, voltage regulators, and single- and three-phase transformers provided by DIgSILENT and OpenDSS, adds a single-phase PV system to the IEEE 37-bus test feeder, and compares steady-state power-flow solutions of the IEEE 37-bus test feeder calculated by DIgSILENT to those calculated by OpenDSS. As a second case study, this study also models sufficiently complex feeders, or feeder J1 with the number of 3,434 buses. The test distribution network developed in DIgSILENT will be used in various fields for analyzing the steady-state or transient behavior of DG-enhanced distribution systems.

14 citations

Proceedings ArticleDOI
14 Jun 2015
TL;DR: In this article, the authors investigated the maximum effect of reactive power control such as the Volt/Var control of distributed generation on the voltage regulation of practical distribution networks and designed a genetic algorithm that determines optimal set points for the reactive power controlling of photovoltaic (PV) systems to minimize the voltage variations of buses when PV systems inject active and reactive power during a day in hourly intervals.
Abstract: An amendment to the IEEE standard on interconnecting distributed resources (DRs) with electric power systems (EPSs) permits reactive power control upon mutual approval by EPS and DR operators and their agreed-upon coordination [1]. Therefore, this study investigates the maximum effect of reactive power control such as the Volt/Var control of distributed generation on the voltage regulation of practical distribution networks. For this purpose, this study, using OpenDSS, models a practical distribution system with more than 1,000 nodes and designs a genetic algorithm that determines optimal set points for the reactive power control of photovoltaic (PV) systems to minimize the voltage variations of buses when PV systems inject active and reactive power during a day in hourly intervals. Finally, it calculates the time-series power flow of a distribution network enhanced by such PV systems and finds the maximum effect of the Volt/Var control of PV systems on voltage regulation.

9 citations

Proceedings ArticleDOI
10 Mar 2015
TL;DR: In this article, the authors analyzed the transient behavior of such a distribution system integrated by distributed generation (DG) systems and proposed case studies of DG systems with their total capacity of 10 and 38 percent of the feeder rating.
Abstract: Various distributed generation (DG) systems with capacities in the range of several kilowatts to tens of megawatts can increase voltage along a feeder when they are injecting power into distribution systems. Thus, the main objective of this study is to analyze the transient behavior of such a distribution system integrated by DG systems. This study (1) models the IEEE 37-bus test feeder as a distribution network enhanced by DG systems in Simulink of MATLAB; (2) proposes case studies of DG systems with their total capacity of 10 and 38 percent of the feeder rating; and then (3) simulates the transient behavior of the test feeder when DG systems inject active power at the unity power factor during a few cycles of 60 Hz. Finally, it addresses the issues of an increase in voltage resulting from the installation of DG systems in a transient state.

7 citations


Cited by
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Journal ArticleDOI
18 Nov 2017-Energies
TL;DR: In this paper, the authors present a structured literature review of published distribution test networks with a special emphasis on classifying their main characteristics and identifying the types of studies for which they have been used.
Abstract: Under the increasing penetration of distributed energy resources and new smart network technologies, distribution utilities face new challenges and opportunities to ensure reliable operations, manage service quality, and reduce operational and investment costs. Simultaneously, the research community is developing algorithms for advanced controls and distribution automation that can help to address some of these challenges. However, there is a shortage of realistic test systems that are publically available for development, testing, and evaluation of such new algorithms. Concerns around revealing critical infrastructure details and customer privacy have severely limited the number of actual networks published and that are available for testing. In recent decades, several distribution test feeders and US-featured representative networks have been published, but the scale, complexity, and control data vary widely. This paper presents a first-of-a-kind structured literature review of published distribution test networks with a special emphasis on classifying their main characteristics and identifying the types of studies for which they have been used. This both aids researchers in choosing suitable test networks for their needs and highlights the opportunities and directions for further test system development. In particular, we highlight the need for building large-scale synthetic networks to overcome the identified drawbacks of current distribution test feeders.

70 citations

Journal ArticleDOI
22 Aug 2018-Heliyon
TL;DR: This research demonstrates that reactive power compensation in distribution grids with distributed resources is a problem that must be analyzed from multiple criteria that consider several objective functions to be optimized; thus achieving a global solution that contemplates an optimal location and dimensioning of reactive power compensating elements.

43 citations

Proceedings ArticleDOI
01 Jul 2017
TL;DR: In this paper, the authors simulate several deployment scenarios of these inverters on a real California distribution feeder and show that minimum and maximum voltage, tap operations, and voltage variability are improved due to the inverters.
Abstract: The impacts of high PV penetration on distribution feeders have been well documented within the last decade. To mitigate these impacts, interconnection standards have been amended to allow PV inverters to regulate voltage locally. However, there is a deficiency of literature discussing how these inverters will behave on real feeders under increasing PV penetration. In this paper, we simulate several deployment scenarios of these inverters on a real California distribution feeder. We show that minimum and maximum voltage, tap operations, and voltage variability are improved due to the inverters. Line losses were shown to increase at high PV penetrations as a side effect. Furthermore, we find inverter sizing was shown to be important as PV penetration increased. Finally we show that increasing the number of inverters and removing the deadband from the Volt/VAr control curve improves the effectiveness.

37 citations

Journal ArticleDOI
TL;DR: This work provides a clear delineation of costs to integrate PV in to the distribution system within the larger context of total costs and benefits associated with PV generators, and emphasizes that these costs are situationally dependent, and that a single “cost of integration” cannot be obtained.
Abstract: The broadening of our energy system to include increasing amounts of wind and solar has led to significant debate about the total costs and benefits associated with different types of generators—with potentially far-reaching policy implications. This has included debate about the cost associated with integrating these generators onto the electric grid. For photovoltaics (PV), this encompasses costs incurred on both the bulk power and distribution systems, as well as the value provided to them. These costs and benefits, in particular those associated with integrating PV onto the distribution system, are not well understood. We seek to advance the state of understanding of “grid integration costs” for the distribution system by reviewing prior literature and outlining a transparent, bottom-up approach that can be used to calculate these costs. We provide a clear delineation of costs to integrate PV in to the distribution system within the larger context of total costs and benefits associated with PV generators. We emphasize that these costs are situationally dependent, and that a single “cost of integration” cannot be obtained. We additionally emphasize that benefits must be considered when evaluating the competitiveness of the technology in a given situation.

37 citations

Proceedings ArticleDOI
10 Mar 2015
TL;DR: In this paper, the authors used OpenDSS to simulate a distribution network (feeder J1 located in the northeastern United States and enhanced by thirteen photovoltaic (PV) systems and calculate the time-series steady-state power flow of the distribution network when PV systems generate or absorb reactive power.
Abstract: Grid-connected photovoltaic (PV) systems with relatively high capacity effectively reduce peak load, but because of their reverse power flow, they can cause overvoltage along a feeder that can exceed five percent of the rated voltage Modern PV systems with the capability of Volt/Var control can mitigate overvoltage by either injecting or absorbing reactive power Thus, the objectives of this study are to (1) model a distribution network (feeder J1 located in the northeastern United States and enhanced by thirteen PV systems) using OpenDSS; (2) use actual collected load profile data as input data to the simulation model and PV generation output data at 15-minute intervals; and (3) calculate the time-series steady-state power flow of the distribution network when PV systems generate or absorb reactive power Finally, it addresses overvoltage resulting from the deployment of high-capacity grid-connected renewable PV systems and mitigation techniques for such overvoltage issues, particularly Volt/Var management and control

32 citations