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Welcome to the University of Venda Institutional Repository, an open digital archive of the research output of the University of Venda. Univen IR contains theses and dissertations, research papers as well as conference papers. For further information and assistance please contact Mr Keith Malabi at +27 15 9628564 or +27 15 962 8314 during office hours

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Open Access

Probabilistic renewable energy modelling in South Africa

(2024-05-05) Ravele, Thakhani; Sigauke, Caston; Jhamba, Lodwell

The variability of solar power creates problems in planning and managing power system operations. It is critical to forecast accurately in order to maintain the safety and stability of large-scale integration of solar power into the grid. Accurate forecasting is vital because it prevents transmission obstruction and maintains a power equilibrium. This thesis uses robust models to solve this problem by addressing four main issues. The first issue involves the construction of quantile regression models for forecasting extreme peak electricity demand and determining the optimal number of units to commit at minimal costs for each period using the forecasts obtained from the developed models. The bounded variable mixed-integer linear programming (MILP) model solves the unit commitment (UC) problem. This is based on priority constraints where demand is first met from renewable energy sources followed by energy from fossil fuels. Secondly, the thesis discusses the modelling and prediction of extremely high quantiles of solar power. The methods used are a semi-parametric extremal mixture (SPEM), generalised additive extreme value (GAEV) or quantile regression via asymmetric Laplace distribution (QR-ALD), additive quantile regression with covariate t (AQR-1), additive quantile regression with temperature variable (AQR-2) and penalised cubic regression smoothing spline (benchmark) models. The predictions from this study are valuable to power utility decision-makers and system operators in knowing the maximum possible solar power which can be generated. This helps them make high-risk decisions and regulatory frameworks requiring high-security levels. As far as we know, this is the first application to conduct a comparative analysis of the proposed robust models using South African solar irradiance data. The interaction between global horizontal irradiance (GHI) and temperature helps determine the maximum amount of solar power generated. As temperature increases, GHI increases up to the point that it increases at a decreasing rate and then decreases. Therefore, system operators need to know the temperature range in which the maximum possible solar power can be generated. The study used the multivariate adaptive regression splines and extreme value theory to determine the maximum temperature to generate the maximum GHI ceteris paribus. Lastly, the study discusses extremal dependence modelling of GHI with temperature and relative humidity (RH) using the conditional multivariate extreme value (CMEV) and copula modes. Due to the nonlinearity and different structure of the dependence on GHI against temperature and RH, unlike previous literature, we use three Archimedean copula functions: Clayton, Frank and Gumbel, to model the dependence structure. This work was then extended by constructing a mixture copula model which combined the Frank and Gumbel models. One of the contributions of this thesis is the construction of additive quantile regression models for forecasting extreme quantiles of electrical load, which are then used in solving the UC problem with bounded MILP with priority constraints. The other contribution is developing a modelling framework that shows that GHI converges to its upper limit if temperature converges to the upper bound. Another contribution is constructing a mixture of some copulas for modelling the extremal dependence of GHI with temperature and RH. This thesis reveals the following key findings: (i) the additive quantile regression model is the best-fitting model for hours 18:00 and 19:00. In contrast, the linear quantile regression model is the best-fitting model for hours 20:00 and 21:00. The UC problem results show that using all the generating units, such as hydroelectric, wind power, concentrated solar power and solar photovoltaic is less costly. (ii) the AQR-2 was the best-fitting model and gave the most accurate prediction of quantiles at τ = 0.95, 0.97, 0.99 and 0.999, while at 0.9999- quantile, the GAEV model had the most accurate predictions. (iii) the marginal increases of GHI converge to 0.12 W/m2 when temperature converges to 44.26 ◦C and the marginal increases of GHI converge to −0.1 W/m2 when RH converges to 103.26%. Conditioning on GHI, the study found that temperature and RH variables have a negative extremal dependence on large values of GHI. (iv) the dependence structure between GHI and variable temperature and RH is asymmetric. Furthermore, the Frank copula is the best-fitting model for variable temperature and RH, implying the presence of extreme co-movements. The modelling framework discussed in this thesis could be useful to decisioniii makers in power utilities, who must optimally integrate highly intermittent renewable energies on the grid. It could be helpful to system operators that face uncertainty in GHI power production due to extreme temperatures and RH, including maintaining the minimum cost by scheduling and dispatching electricity during peak hours when the grid is constrained due to peak load demand.

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Use of information communication technology as a tool for preserving Tshivenda Proverbs

(2024-09-06) Nevondo, Phathutshedzo Unarine; Madima, T. J.; Makhanikhe, T. J.; Matshidze, P. E.

This study explored the use of Information Communication Technology in preserving the Tshivenḓa proverbs. From time immemorial, proverbs were valuable cultural practices of oral tradition, which were used to empower the young generation on morals, norms, behaviour, education, and other African values. It has been noticed that due to modernisation and lack of preservation, proverbs have been abounded by the majority of Vhavenḓa youths, which seems to be resulting in moral degeneration because youth no longer acquire moral knowledge and skills through proverbs. The overall objectives were to examine different ways of gaining knowledge and understanding about proverbs and Information Communication Technology, to explore the role of information Communication Technology in preserving proverbs within Vhavenḓa communities, and to explore strategies to mitigate challenges associated with the preservation of Tshivenḓa proverbs through the use of Information Communication Technology. The study was grounded in socio-cultural and diffusion of innovation theories. This study intended to adopt a qualitative research design. Therefore, participants were selected using Purposive and snowballing samplings. Furthermore, semi-structured and focus group discussions were used to collect data. Thematic data analysis was used to analyse data. The envisioned findings of the study could be convenient in preserving the Vhavenḓa proverbs.

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Views of women regarding gender-based violence in Thulamela Municipality, Limpopo Province

(2024-09-06) Netshiongolwe, Rabelani; Mushwana, M.; Madzhie, M.

Background: South Africa is identified to be one of the most unsafe countries for women because of its high prevalence of Gender-Based violence. About 10.516 rapes, 1.514 cases of attempted murder and 14.401 assaults against female victims were recorded in 2023 (Mpako &Ndoma, 2023). Gender Links has reported that more than two thirds of women in Limpopo have had an experience on some form of gender-based violence in their lifetime, including partner and non-partner violence. Therefore, the aim of the study was to explore the views of women regarding Gender based violence. The objectives were: to explore the views of women on gender- based violence against women, to explore the social impacts of GBV towards women, to describe the effects of GBV on women as victims of GBV and to explore the potential measures that may reduce GBV against women. Methods: The study was qualitative in nature and utilized exploratory research design to explore the views of women regarding gender-based violence. The study was conducted at the five villages with the Thulamela municipality, Thohoyandou, Lwamondo, Tshisaulu, Itsani, Muledane. A sample of 20 Tshivenda speaking women aged between the ages of 25 to 50 were selected using purposive sampling method. Semi-structured interviews and an interview guide was used during data collection process, and the study employed thematic analysis for the purpose of data analysis. Pre-testing of the interview guide was done using two participants who fell within the inclusion criteria of the study but were later excluded in the actual study. Trustworthiness of the study was assessed using credibility, conformability, dependability and transferability. Furthermore, the study adhered to the following research ethics; institutional ethics, informed consent, confidentiality, avoidance of harm, voluntary participation, publication of results and acknowledgement of others works. Results: The findings of the study found that GBV is indeed prevalent in the Thulamela municipality. The study found psychological, social and physical impacts of GBV on women as victims of gender-based violence. The following impacts were identified: stress and depression, trauma, suicide, alcoholism, anxiety and mood disorder, low self-esteem, feelings of worthlessness and shame. Furthermore the study suggested that changing certain societal norms and expectation like normalising divorce might help reduce GBV against women. Recommendation: based on the findings of the study, it is recommended that communities are to change certain societal expectations and norms and teach females to be more independent financially to reduce the number of females who become victims of GBV. The study further recommends that the department of justice along with the department of correctional services to give longer sentences to perpetrators of GBV.

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Evaluation of Gender Mainstreaming on the appointment process of senior management: A case study of the Office of the Premier in Limpopo Province, South Africa

(2024-09-06) Ngobeni, Ellah Nkensani; Mukwevho, M. H.; Thobejane, T. D.

The challenges of inequality in South Africa’s workplace are compounded by the legacy of the system of apartheid and colonialism. Gender inequality continues to exist even during the new dispensation despite the existence of national, regional and international legislation to address inequality. This study evaluated the extent of the implementation and enforcement of employment equity policies on the appointment of senior management officials at the Office of the Premier. The study adopted a feminist qualitative approach to collect data. The sample of the study comprised males and females in the Office of the Premier. Non-probability purposive sampling to identify and select Deputy Directors, Directors and Chief Directors was used as these categories of employees are in the pipeline and poised to take different senior management positions. Data was collected using interviews, focus group discussions and document analysis. Due to my position as the Chief Director working in the Office of the Premier, I relied on the process of reflexivity to question and analyse any biases I may have had in the process of collecting and analysing the data. Reflexivity is a process of continual internal dialogue and critical self-evaluation of the researcher’s positionality as well as active acknowledgement; and explicit recognition that this position may affect the research process. Collected data was analysed using thematic analysis. Ultimately, findings and recommendations from the study were shared with the Institutional Development Support Branch in the Office of the Premier for implementation by all sector departments in the Limpopo Provincial Administration.

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The Impact of Nandoni Dam construction on selected indigenous plant diversity: A case study in Thulamela Municipality within Vhembe District of Limpopo Province South Africa.

(2024-09-06) Thovhogi, Ntevheleni Justice; Odhiambo, B. D. O.; Ligavha-Mbelengwa, H. H.; Mokoebo, M. J.

The study assessed the impact of Nandoni Dam construction on selected indigenous plant species (IPS) diversity: A case study in Thulamela Municipality within Vhembe District. The construction of Nandoni Dam started in 1998 and was completed in 2005. The research focused on the following three specific objectives: to examine the selected IPS diversity before dam construction, to determine whether some selected IPS diversity were protected after dam construction, and to assess the community’s perceptions on the need to develop long-term management plans for the conservation of selected IPS diversity. The literature reviewed concentrated on the background of the study, problem statement, justification of the study, Environmental Impact Assessment (EIA), and other studies. Under the methodology of data collection and research design, both qualitative and quantitative methodologies were used. Primary data collection includes field surveys, interviews, and observations. Secondary data were collected from documentary reviews, library books, published articles, theses, etc. Permission was requested and granted by the traditional leaders of Tshiulungoma, Budeli, Dididi, and Mulenzhe villages, which were affected by the construction of Nandoni Dam. For systematic data analysis, the researcher used Statistical Package for the Social Sciences (SPSS) Version 25, narrative, and ethnography. Government officials were visited and communicated face-to-face and telephonically. Ethical consideration was granted by UHDEC. Results: Documentation of selected IPS diversity before 1998; photos of submerged and protected selected IPS diversity after dam construction in 2005. Recommendation: Community environment alliance, public community education on EIA reports, and conservation of selected IPS diversity.