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Faculty of Engineering and Built Environment

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Start date: 2021Subject: search.filters.subject.Photovoltaic cells

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Now showing 1 - 3 of 3
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    Design and application of passive filters for improved power quality in standalone PV system
    (2024-05) Dlamini, Sandile; Adebiyi, Abayomi Aduragba; Kabeya, Musasa
    Harmonic components have developed in power systems due to the non-linear properties of the circuit components utilized in power electronics-based products and their rapid application. Power systems rely on fundamental quantities like sinusoidally varying voltage and current, which oscillate at a frequency of 50 Hz. The standard restrictions of IEEE-519-1992 were utilized as a benchmark in this study. To generate the best output, the total harmonic distortion (THD) should be decreased below the limit, even for certain individual harmonic numbers, and reflect the power factor output. Using the results of the simulation and projections for each mitigation strategy, the THDI can be reduced below the IEEE-519 standard whilst also providing cost and electrical advantages. Analysed and modelled is the PV system, which comprises solar panels, a DC-DC converter, a DC-AC inverter, and a non-linear load. Passive filters are an effective solution for improving power quality in standalone photovoltaic (PV) systems. This dissertation provides an overview of the design and application of passive filters for this purpose. Firstly, an introduction to PV systems and the power quality issues associated with them was preferred. Next, different types of passive filters, namely LC filters, LCL filters and LLCL filters, are discussed along with their advantages and disadvantages, and the design considerations for these filters, including the selection of filter components and the calculation of filter parameters. The application of passive filters in standalone PV systems was then discussed, including their implementation in DC-DC converters and Z-Source inverters and, the design of PWM controllers such as the constant boost control method and simple boost control method. The analysis of the outcome of the engineered systems was conducted according to the IEEE standard and SANS 10142 Standard to protect the connected equipment within the off-grid network. The outcomes pertain to the single-phase stand-alone/off-grid photovoltaic system and the single-phase Z-Source inverter. The Z-Source inverter is equipped with two distinct methods for PWM control, namely the constant boost control method and the simple boost control method. All three designs incorporate three passive filters, namely the LC filter, the LCL filter and the LLCL filter. The results were obtained from the network consisting of three distinct designs. LLCL demonstrates superior performance as a passive filter, substantiating its position as the optimal choice. The optimal outcomes of a single-phase off-photovoltaic (PV) network can be achieved using LC, LCL and LLCL filters, with corresponding percentages of 2.99%, 2.45% and 1.71% respectively. Unfiltered was 89.05%, which is not good for the equipment connected to the network. The Z-Source showcases the capability of voltage amplification to an infinite level, rendering it highly effective in minimizing total harmonic distortion. This research investigation further demonstrated the efficacy of the Z-Source Inverter with Constant Control Boost Method and Simple Boost Control Method, achieving unfiltered total harmonic distortion levels of 38.85% and 44.96% respectively. The Z-Source inverter, when combined with the Constant Boost Control method and Simple Boost Control method, exhibits various filter configurations such as LC, LCL, and LLCL filters. In the context of the constant boost control and simple boost control methods, it is imperative to assess the total harmonic distortion percentage of voltage and current for LC, LCL, and LLCL configurations. The constant boost control voltage (LC, LCL, LLCL) and current total harmonic distortion (LC, LCL, LLCL) are measured at 4.177%, 2.655%, 1.951%, and 2.958%, 2.09%,1.465% correspondingly. The voltage-based boost control methods, namely LC, LCL and LLCL, exhibit total harmonic distortion levels of 2.345%, 1.920% and 0.211%, respectively. Similarly, the current-based boost control methods, LC, LCL and LLCL, demonstrate total harmonic distortion levels of 2.346%, 1.921%, 0.211%, and 2.346%, 1.921%, 0.211%, respectively. Finally, the dissertation wrapped up by exploring the potential of passive filters for enhancing power quality in standalone PV systems. The thesis offers a comprehensive investigation of the design and implementation of passive filters in standalone PV systems, providing valuable insights for engineers and researchers in the field. It enhances understanding and utilization of these imperative devices.
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    Development of an Intelligent Standalone Solar Photovoltaic 48V DC microgrid system
    (2024-05) Makhanya, Thandeka; Pillay, N; Sewsunker, R
    With load shedding negatively affecting South Africans there are many concerns regarding stable power delivery to residential households. Amid all the power delivery concerns some rural communities are still not connected to the existing power infrastructure. Implementation of newer efficient clean energy sources is in demand. A standalone Photovoltaic (PV) Solar distributed renewable energy Direct Current (DC) microgrid can be the best possible approach to tackle the power grid shortcomings and to electrify communities that are not yet covered by the power grid or communities that want to transition to clean energy. The research focuses on the design of an optimal 48 VDC Multiple-PV Standalone microgrid in remote areas not covered by the main grid. The proposed microgrid can be typically used for lighting, charging phones, and other low-power applications. The microgrid will consist of 4 microgrid subgrids, each consisting of a dedicated Solar PV array, battery storage systems, loads, and other components that connect to the DC Bus and need to be monitored and controlled for efficient operation. Furthermore, the subgrids were designed based on the meteorological data of the selected location and the load demand for each subgrid. The microgrid design enables the subgrids to share power through a bidirectional DC-DC converter based on certain conditions. A power-sharing management system was implemented to manage power-sharing ensuring that the sharing subgrid does not drive its users to load shedding. Moreover, the microgrid design was simulated on Matlab/Simulink to observe the operation of the designed system and to determine if the proposed design would be able to achieve the desired goal. The results obtained from simulations indicate that the proposed microgrid design can provide an optimal service to its users by allowing the subgrid with surplus energy to share its power with the subgrid when needed.
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    Optimization of distribution static compensator for mitigation of power quality issues in grid-tied photovoltaic systems
    (2021-12-01) Adebiyi, Abayomi Aduragba; Lazarus, Ian J.; Saha, Akshay K.; Ojo, Evans E.
    The global energy demand is rising above the all-time average, and fossil fuel reserves, which power a large chunk of the existing power generation plants, are being depleted. Hence, Renewable Energy Technologies (RET) have become the alternative to meet demand and provide sustainable power. Solar photovoltaic (PV) energy, an essential aspect of RET, which generates emission-free power, is one of the world's emerging resources. Rooftop PV technology installation is advanced in residential and commercial applications due to government subsidies, lower investment costs, and feed-in tariffs. The rapid penetration of PV systems into conventional distribution grids has created some power quality and power stability issues. Power quality (PQ) distortion is the most critical problem in distribution grids. The literature studied revealed that the several nonlinear loads and PV systems power electronic-based inverters that penetrate the grid and contribute to poor power quality issues, i.e., voltage rise, voltage dip, voltage unbalance, flicker, and harmonics. Also, the PV system maximum power point (MPP) controller's performance was investigated since the current-voltage (I-V) characteristic of PV panels is nonlinear and dependent on variables such as solar radiation and temperature. A comparative analysis conducted showed that the incremental conductance tracks the maximum power point better than the perturb and observe method for better power generation. MATLAB/Simulink system model simulations were run for several case studies to analyze the maximum power point tracking (MPPT) algorithm's performance under varied solar irradiation. The results obtained suggested a course to the implementation of the proposed incremental conductance MPPT algorithm. Selected power quality problems in a grid-tied PV system were analyzed via simulations and enhanced with the application of conventional proportional-integral (PI) controlled DSTATCOM. Also, field measurement-based experiments were conducted to determine system performance in a typical grid-tied PV system. The real-life 110 kW grid-tied PV system installed at the Durban University of Technology (DUT), Steve Biko campus, was used for the fieldwork. Taken into consideration was the impact of solar radiation dynamic variation on the field study. According to the results obtained, the 110 kW PV system's voltage quality data were within the limits of the local and internationally defined standards. The concept of DSTATCOM was implemented with an Enhanced Jaya (E-Jaya) optimization algorithm to mitigate specific power quality issues, such as voltage rise, voltage dip, voltage unbalance, and current harmonics. The precision with which the DSTATCOM reference compensation current is selected is vital to the device's performance. The synchronous reference frame theory of phase lock loop (PLL) for a three-phase system is described in this thesis. The objective was to keep the source current THD below 5% to comply with the recommended limits of the IEEE519 Standard harmonic limits. The implemented novel E-Jaya control optimization algorithm-based D-STATCOM provided continuous and adequate voltage regulation and harmonic compensation to mitigate power quality issues in the grid-tied PV distribution system. Simulation comparative analysis results of the developed control method with Artificial Bee Colony (ABC) and Jaya optimization algorithm indicated that the developed novel E-Jaya optimization algorithm enhanced the grid-tied PV system's performance by providing superior voltage regulation and source current THD compensation significantly declined to 1.01% from 31.93%.