Browsing by Author "Gbadega, Peter Anuoluwapo."

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Adaptive model predictive control of renewable energy-based micro-grid.
(2021) Gbadega, Peter Anuoluwapo.; Saha, Akshay Kumar.
Energy sector is facing a shift from a fossil-fuel energy system to a modern energy system focused on renewable energy and electric transport systems. New control algorithms are required to deal with the intermittent, stochastic, and distributed nature of the generation and with the new patterns of consumption. Firstly, this study proposes an adaptive model-based receding horizon control technique to address the issues associated with the energy management system (EMS) in micro-grid operations. The essential objective of the EMS is to balance power generation and demand through energy storage for optimal operation of the renewable energy-based micro-grid. At each sampling point, the proposed control system compares the expected power produced by the renewable generators with the expected load demand and determines the scheduling of the different energy storage devices and generators for the next few hours. The control technique solves the optimization problem in order to minimize or determines the minimum running cost of the overall micro-grid operations, while satisfying the demand and taking into account technical and physical constraints. Micro-grid, as any other systems are subject to disturbances during their normal operation. Hence, the power generated by the renewable energy sources (RESs) and the demanded power are the main disturbances acting on the micro-grid. As renewable sources are used for the generation, their time-varying nature, their difficulty in predicting, and their lack of ability to manipulate make them a problem for the control system to solve. In view of this, the study investigates the impacts of considering the prediction of disturbances on the performance of the energy management system (EMS) based on the adaptive model predictive control (AMPC) algorithm in order to improve the operating costs of the micro-grid with hybrid-energy storage systems. Furthermore, adequate management of loads and electric vehicle (EV) charging can help enhance the micro-grid operation. This study also introduced the concept of demand-side management (DSM), which allows the customers to make decisions regarding their energy consumption and also help to reduce the peak load demand and to reshape the load profile so as to improve the efficiency of the system, environmental impacts, and reduction in the overall operational costs. More so, the intermittent nature of renewable energy and consumer random behavior introduces a stochastic component to the problem of control. Therefore, in order to solve this problem, this study utilizes an AMPC control technique, which provides some robustness to the control of systems with uncertainties. Lastly, the performances of the micro-grids used as a case study are evaluated through simulation modeling, implemented in MATLAB/Simulink environment, and the simulation results show the accuracy and efficiency of the proposed control technique. More so, the results also show how the AMPC can adapt to various generation scenarios, providing an optimal solution to power-sharing among the distributed energy resources (DERs) and taking into consideration both the physical and operational constraints and similarly, the optimization of the imposed operational criteria.
Power losses in HVDC converter stations.
(2018) Gbadega, Peter Anuoluwapo.; Saha, Akshay Kumar.
In transmission systems, particularly when the power is transported over a transmission line of distance 500 km and above, a considerable amount of power is lost during power system operations, which consist of all the components that are used in generation and transmission of power. Therefore, it is imperative to estimate the power losses due to some power equipment on the electrical network during transmission systems. More so, it is of importance to comprehend the pros and cons of both LCC-based and VSC-based transmission systems and subsequently carry out detailed research on power losses of both systems using the calculation methods listed in standards. It is the purpose of this research work to determine and calculate the overall losses of various equipment of high-voltage direct current (HVDC) converter stations under operating and standby modes using standards IEC 61803, IEEE 1158, IEC 62751-1-2 and the component datasheet parameters (Phase Control Thyristor Type DCR3030V42 and Dynex IGBT module DIM1200ASM45-TS000). The loss calculations in this research work are precisely applicable to all parts of the converter station and cover standby, partial-load, and full-load losses using the standardized calculation methods stipulated in the aforementioned standards. Furthermore, Switching losses, as well as conduction losses are included in the calculation using a simplified analytical model, based on the standards IEC 62751-1-2 and power semiconductor (Dynex) datasheet information. Therefore, an analytical method was adopted to estimate the power losses of VSC-based HVDC system of two-level, three-level and modular multilevel VSC configurations. Finally, the various HVDC technologies (circuit simulations) models were implemented in the Matlab-Simulink environment. The Matlab models were used to estimate the power losses of these technologies converter losses for various operating conditions. The simulation technique has been devised to provide an independent crosscheck on the results obtained using idealized mathematical representations (analytical technique). Subsequent to these circuit implementations, some results were obtained and consequently validated with other commercial power loss simulation tools or electronic software, such as Semisel and Melcosim. The use of different contrasting techniques to provide equivalent characteristics losses calculations provide a good method of validating the feasibility of the HVDC technology loss study, giving confidence in the results for the converter losses that have been obtained. This research work is based on an existing method of loss evaluation, but strictly followed the IEEE loss calculation methods stipulated in standards. The major contribution of this research work was the new approach adopted in the power loss evaluation of various HVDC technologies such as the LCC-based and VSC-based topologies of the converter stations using the idealized mathematical representations stipulated in standards IEC 61803, IEEE 1158, IEC 62751-1-2 and the component datasheet parameter, which signifies the novel output of this research work.