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Research Publications (Engineering and Built Environment)

Permanent URI for this collectionhttp://ir-dev.dut.ac.za/handle/10321/215

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    On demand and supply management in domestic microgrids
    (Turkish Online Journal of Qualitative Inquiry (TOJQI), 2021-12-01) Chidzonga, Richard; Nleya, Bakhe; NLEYA
    Standalone or residential microgrids (MG) are becoming increasingly common. Their success is premised on optimal operational strategies like demand side management (DSM). It is not uncommon in optimization problems to deal with competing objectives in the context of multi-objective optimization. In a domestic MG, optimization objectives may encompass minimization of OPEX, maximization of consumers’ utility, and minimization of CO2 emissions etc. This article employs a technique which transforms a bi-objective energy optimization problem into a single objective problem, then solving the problem using the heuristic technique of binary particle swarm optimization (B PSO). The random phenomena associated with the statistical load profiles and multiple renewable energy sources (RESs) are modelled using established statistical approaches. Results obtained using simulation show that the pro-posed model can minimize the OPEX of isolated MG whilst simultaneously meeting the utility expectations of the consumer.
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    Optimization of university campus microgrid for cost reduction: a case study
    (Trans Tech Publications, Ltd., 2022) Akindeji, Kayode Timothy; Tiako, Remy; Davidson, Innocent
    This paper presents an optimization model to minimize the fuel cost and CO2 emision on university campuses using an hybrid power system (HPS). The HPS is made up of solar photovoltaic (PV), diesel generator (DG), wind turbine (WT) and battery energy storage system (BESS). Two university campuses are used as case study to investigate the efficiency of the proposed HPS. The objective function is formulated such that each campus load is met by the renewable energy source (RES) when available and the DG only swicthes on when the output of the RES is not eneough to meet the load. The resulting non linear optimization problem is solved using a function in MATLAB called “quadprog”. The results of the simulation are analyzed and compared with the base case in which the DG is used exclusively to meet the entire load. The results show the effectiveness of the optimized HPS in saving fuel when compared to the base case and reflect the effects of seasonal variations in fuel costs.
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    Modeling of double stage photovoltaic inverter system with fast delayed signal cancellation for fault ride-through control application in microgrids
    (MDPI AG, 2022-02) Buraimoh, Elutunji; Davidson, Innocent E.
    This research presents a secondary control for a grid-supporting microgrid with photovoltaics sources to guarantee grid code compliance and ancillary services. The secondary control accomplishes the fault ride-through, which implements a delayed signal cancellation (DSC) algorithm for negative sequence detection. Without mode switching, the proposed control strategy meets grid code requirements and ensures voltage regulation at the secondary level, which is active and more salient throughout the transient period of host grid disturbances. This control also ensures a constant supply of the microgrid’s sensitive local load while adhering to grid code requirements. Similarly, active power injection into the main grid is limited by progressively altering the MPPT operating point dependent on the depth of voltage sag to optimize reactive power injection to sustain grid voltage sag. The recommended secondary control is triggered by utilizing the DSC process’s detection algorithm to identify the occurrence of a fault in a tiny fraction of a half-cycle in a grid fault. Consequently, while satisfying microgrid load needs, the devised technique guaranteed that increases in DC-link voltage and AC grid current were controlled. MATLAB Simscape ElectricalTM and OPAL-RT Lab are used to do time-domain simulations of the model using the recommended secondary control systems.
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    Decentralized fast delayed signal cancelation secondary control for low voltage ride-through application in grid supporting grid feeding microgrid
    (Frontiers Media SA, 2021-04-15) Buraimoh, Elutunji; Davidson, Innocent E.; Martinez-Rodrigo, Fernando
    In this study, a distributed secondary control is proposed alongside the conventional primary control to form a hierarchical control scheme for the Low Voltage Ride-Through (LVRT) control and applications in the inverter-based microgrid. The secondary control utilizes a fast Delayed Signal Cancelation (DSC) algorithm for the secondary control loop to control the reactive and active power reference by controlling the sequences generated. The microgrid consists of four Distributed Energy Resources (DER) sources interfaced to the grid through interfacing inverters coordinated by droop for effective power-sharing according to capacities. The droop also allows for grid supporting application for microgrid’s participation in frequency and voltage regulation in the main grid. The proposed decentralized fast DSC performance is evaluated with centralized secondary and traditional primary control using OPAL-RT Lab computation and MATLAB/SIMULINK graphical user interface for offline simulations and real-time digital simulator verification. This study presents and discusses the results.
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    Modeling and assessment of the fault ride-through capabilities of grid supporting inverter-based microgrids
    (IEEE, 2020-03) Buraimoh, Elutunji; Davidson, Innocent E.
    Grid-connected micro-grids are subject to grid disturbances. This has undesirable effects on system operation. Riding through fault conditions is a crucial technical challenge. Evolving grid codes require micro-grids to possess fault ridethrough capabilities and support the grid voltage recovery to imitate the behavior of the traditional electrical power systems. The paper proposes two models of a grid supporting inverterbased microgrid; the first controlled as a current source with a parallel impedance suitable for grid feeding applications; the second regulated as a voltage source with a virtual impedance suitable for grid forming applications. The main objective of these two systems is to achieve controlled power delivery to the grid using grid voltage and frequency regulation. This paper discusses power interaction under steady states and transient conditions. Grid voltage parameters, such as amplitude, phase angle, and frequency, are estimated using a synchronization system, as these are necessary for precise active and reactive power control. Results obtained provide an understanding of grid fault impact on grid supporting systems and fault ridethrough compliance and evaluates the impacts of the virtual impedances on fault ride through and power interaction.