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Oluwaseun M. Akeyo

Bio: Oluwaseun M. Akeyo is an academic researcher from University of Kentucky. The author has contributed to research in topics: Photovoltaic system & Energy storage. The author has an hindex of 5, co-authored 16 publications receiving 103 citations.

Papers
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Journal ArticleDOI
TL;DR: This paper analyzes the configuration, design, and operation of multi-MW grid connected solar photovoltaic (PV) systems with practical test cases provided by a 10-MW field development to improve the capacity factor.
Abstract: This paper analyzes the configuration, design, and operation of multi-MW grid connected solar photovoltaic (PV) systems with practical test cases provided by a 10-MW field development. In order to improve the capacity factor, the PV system operates at its maximum power point during periods of lower irradiance, and the power output is limited to a rated value at high irradiance. The proposed configuration also incorporates a utility scale battery energy storage system (BESS) connected to the grid through an independent inverter and benefits of the experience gained with a 1-MW 2-MWh BESS large demonstrator. The BESS power smoothing and frequency regulation capabilities are illustrated though combined theoretical and experimental studies. The behavior of the grid connected PV and BESS combined system is studied using a modified IEEE 14 bus test system implemented in PSCAD/EMTDC. This paper also includes a sizing exercise for energy storage in order to provide dispatchable PV power.

67 citations

Journal ArticleDOI
TL;DR: A battery system connected to the dc link of an inverter to recuperate excess PV energy that will otherwise be curtailed due to inverter rating limitations is stored in the battery and supplied to the grid during periods of reduced irradiance.
Abstract: Typically, solar inverters curtail or “clip” the available power from the photovoltaic (PV) system when it exceeds the maximum ac capacity. This article discusses a battery system connected to the dc link of an inverter to recuperate this PV energy. Contrary to conventional approaches, which employ two dc–dc converters, one each for the battery and solar PV system, the proposed configuration utilizes a single dc–dc converter capable of simultaneously operating as a charge controller and a maximum power point tracking (MPPT) device. In addition to improving the overall system capacity factor, increasing the conversion efficiencies, and ensuring MPPT stability, the proposed configuration offers a simple solution for adding energy storage to existing PV installations. With this configuration, the excess power that will otherwise be curtailed due to inverter rating limitations is stored in the battery and supplied to the grid during periods of reduced irradiance. Moreover, a systematic methodology for sizing a dc-bus connected battery to minimize total PV energy curtailed was developed using an annual PV generation profile at the Louisville Gas and Electric and Kentucky Utilities E. W. Brown solar facility at Kentucky. The detailed behavior of the proposed system and its power electronics controls and operations were validated with case studies developed in PSCAD/EMTDC software for variable power generation and PV output power smoothing.

47 citations

Proceedings ArticleDOI
01 Nov 2016
TL;DR: In this article, a multi-megawatt grid connected photovoltaic (PV) system with parallel arrays and power electronic units, each with their own DC-DC and DC-AC converters, is studied.
Abstract: The multi-megawatt grid connected photovoltaic (PV) system studied in the paper includes parallel arrays and power electronic units, each with their own DC-DC and DC-AC converters. In one configuration, the DC-AC converters of adjacent parallel sections are connected in cascade, in order to effectively operate as a multilevel inverter, thereby reducing the filtering requirements. Grid voltage oriented control is employed for inverters and a battery is incorporated for energy storage and performance improvement. Modeling is performed with the PSCAD/EMTDC software, such that both the power electronics components, controls and subsystem aspects, and the electric grid power system issues, can be studied during steady-state and transient operation. The system simulation is demonstrated on a modified IEEE 14-bus test case.

21 citations

Proceedings ArticleDOI
01 Nov 2017
TL;DR: This paper proposes a method of expanding the capacity of an existing irrigation farm with additional pumps powered by solar PV that includes PV arrays and battery energy storage connected to a common dc bus, which energizes an array of variable speed inverter driven pumps.
Abstract: Solar photovoltaic (PV) renewable energy systems are undergoing major technological developments and large-scale field deployment and electric grid integration. This paper proposes a method of expanding the capacity of an existing irrigation farm with additional pumps powered by solar PV. The system includes PV arrays and battery energy storage connected to a common dc bus, which energizes an array of variable speed inverter driven pumps. Capacity modulation is achieved by energizing an optimal number of pumps required in order to meet a particular load demand with minimum supply energy. A grid connection to the dc bus of the power electronic system is established via a bidirectional converter, such that active and reactive power demands can be both serviced. The controls and the steady-state and transient performance of the system are implemented and simulated with the PSCADTM/EMTDCTM software.

12 citations

Journal ArticleDOI
31 Dec 2020-Energies
TL;DR: In this article, the authors proposed a framework for analyzing the impact of increasing solar penetration on generation and transmission networks while considering the responses of conventional generators to changes in solar PV output power.
Abstract: Significant changes in conventional generator operation and transmission system planning will be required to accommodate increasing solar photovoltaic (PV) penetration. There is a limit to the maximum amount of solar that can be connected in a service area without the need for significant upgrades to the existing generation and transmission infrastructure. This study proposes a framework for analyzing the impact of increasing solar penetration on generation and transmission networks while considering the responses of conventional generators to changes in solar PV output power. Contrary to traditional approaches in which it is assumed that generation can always match demand, this framework employs a detailed minute-to-minute (M-M) dispatch model capable of capturing the impact of renewable intermittency and estimating the over- and under-generation dispatch scenarios due to solar volatility and surplus generation. The impact of high solar PV penetration was evaluated on a modified benchmark model, which includes generators with defined characteristics including unit ramp rates, heat rates, operation cost curves, and minimum and maximum generation limits. The PV hosting capacity, defined as the maximum solar PV penetration the system can support without substantial generation imbalances, transmission bus voltage, or thermal violation was estimated for the example transmission circuit considered. The results of the study indicate that increasing solar penetration may lead to a substantial increase in generation imbalances and the maximum solar PV system that can be connected to a transmission circuit varies based on the point of interconnection, load, and the connected generator specifications and responses.

9 citations


Cited by
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Journal Article
TL;DR: In this article, an exploratory three-stage seven-level cascaded H-bridge inverter has been manufactured using nine H-bridges, each of which is associated with a 185-W solar panel.
Abstract: Due to the possibility of providing energy with much less dependence on the fossil fuels, renew-competent energy sources, in specified sun photovoltaic (PV) conversion have received elevated acceptance and progress in latest times. Big benefits of PV panels comprise easy and trustworthy power production and suitability for disbursed iteration. In addition the costs for photovoltaic modules is drastically lowering. To comprehend this issue, a control plan with modulation compensation scheme is likewise proposed. An exploratory three-stage seven-level cascaded H-bridge inverter has been manufactured using nine H-bridge modules (three modules for each stage). Each H-bridge module is associated with a 185-W solar panel. Simulation results are introduced to confirm the practicality of the proposed approach.

135 citations

Journal ArticleDOI
TL;DR: This paper analyzes the configuration, design, and operation of multi-MW grid connected solar photovoltaic (PV) systems with practical test cases provided by a 10-MW field development to improve the capacity factor.
Abstract: This paper analyzes the configuration, design, and operation of multi-MW grid connected solar photovoltaic (PV) systems with practical test cases provided by a 10-MW field development. In order to improve the capacity factor, the PV system operates at its maximum power point during periods of lower irradiance, and the power output is limited to a rated value at high irradiance. The proposed configuration also incorporates a utility scale battery energy storage system (BESS) connected to the grid through an independent inverter and benefits of the experience gained with a 1-MW 2-MWh BESS large demonstrator. The BESS power smoothing and frequency regulation capabilities are illustrated though combined theoretical and experimental studies. The behavior of the grid connected PV and BESS combined system is studied using a modified IEEE 14 bus test system implemented in PSCAD/EMTDC. This paper also includes a sizing exercise for energy storage in order to provide dispatchable PV power.

67 citations

Journal ArticleDOI
TL;DR: The key challenges addressed are implementation of automated transition in a PV-B-UPQC system with minimal disturbance to the local loads and the issue of the integrating power quality improvement along with the generation of clean energy.
Abstract: In this article, a methodology for implementation of an automated transition of a solar PV array and battery integrated unified power quality conditioner (PV-B-UPQC) between standalone and grid connected modes of operation is presented and analyzed. This system consists of a shunt and series active filters connected back to back with a common dc-link. The system addresses the issue of the integrating power quality improvement along with the generation of clean energy. Moreover, due to the automated transition, the critical loads have continuous power supply irrespective of grid availability. The key challenges addressed are implementation of automated transition in a PV-B-UPQC system with minimal disturbance to the local loads. The system operation is validated through experimentation under a number of dynamic conditions such as automated transition, supply voltage variations, unavailability of the grid, variation in solar power generation, load variation, etc., which are typically encountered in a modern distribution network.

61 citations

Journal ArticleDOI
TL;DR: In this article, an artificial neural network (ANN) is used to learn the relationship between the minimum impedance of the battery and capacity fading, which can be used to predict the capacity capability of a battery, and an ANN-based capacity estimator is developed to predict available capacity of battery cells.
Abstract: A state-of-charge (SOC) balancing method which accounts for state-of-health (SOH) status of battery cells is presented in this article. The data collected from aging experiments conducted in the laboratory indicates that there is correlation between the minimum impedance of the battery and capacity fading which can be used to predict capacity capability of the battery. However, this relationship is complex and nonlinear. In this article, artificial neural network (ANN) is utilized to learn this relationship and an ANN-based capacity estimator is developed to predict available capacity of battery cells. An online impedance measurement method with improved measurement resolution is presented to obtain a more accurate minimum impedance for the ANN-based capacity estimator. The estimated capacity from the ANN capacity estimator is fed to an SOC balancing controller to calculate SOC values for the battery cells. A battery cell with worse health has lower available capacity than a battery cell with better health, and, therefore, its SOC value is adjusted to a smaller value when SOH or capacity estimation functionality is activated. Because of this mechanism and the control principle of the presented SOC balancing controller, the system draws energy at a slower rate from the battery cell(s) with lower SOH and draws energy at a faster rate from the battery cell(s) with higher SOH such that all battery cells reach their end of discharge at the same time. This results in extending operation time of the system, makes best use of energy from every battery cell, and avoids over-discharging battery cells with lower SOH. The presented method is evaluated using results obtained from a laboratory experimental setup.

56 citations

Journal ArticleDOI
TL;DR: To improve the performance and profitability of ESS for electric grid applications, future research should have a focus on developing decision-making tools for determining the storage technology, installed capacity, and operating strategy.
Abstract: Energy storage systems (ESS) are increasingly deployed in both transmission and distribution grids for various benefits, especially for improving renewable energy penetration. Along with the industrial acceptance of ESS, research on storage technologies and their grid applications is also undergoing rapid progress. We present an overview of ESS including different storage technologies, various grid applications, cost-benefit analysis, and market policies. First, we classify storage technologies with grid application potential into several groups according to the form of energy stored. This classification is presented to summarize technological and economic characteristics of storage technologies and also present the recent development of these technologies. Next, we categorize the grid applications of ESS into several groups based on the physical location, service type, and working principle. We also review the state-of-the-art optimization and control methodologies for each application group. Furthermore, we present the cost-benefit analysis for three types of investors and a comprehensive comparison among market policies for the participation of ESS in different wholesale markets. Finally, we highlight several future research directions that are derived from this review. To improve the performance and profitability of ESS for electric grid applications, future research should have a focus on developing decision-making tools for determining the storage technology, installed capacity, and operating strategy. This research focus should be supported by the further developments of component-level performance and aging models, system-level market frameworks, and cost-benefit analysis.

51 citations