Arnold Johan Rix

Arnold Johan Rix
Stellenbosch University | SUN · Department of Electrical & Electronic Engineering

PhD

About

86
Publications
75,864
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369
Citations
Introduction
Dr. Arnold Rix is a senior lecturer at the department of Electronic & Electrical Engineering and holds the Scatec Solar Chair in Photovoltaics Systems position at Stellenbosch University. He recently came from the utility scale solar industry, with experience in grid connection and grid code compliance as well as project management and project development of utility scale solar PV plants. Before he got involved with solar PV he was working as electrical engineer and project developer for a local wind turbine manufacture. He has a keen interest in solar and wind energy and is establishing a research group in Solar PV systems at Stellenbosch University while presenting undergraduate and postgraduate subjects in renewable energy systems and advanced PV systems respectively.

Publications

Publications (86)
Article
Full-text available
Electrification is expected to decarbonise transportation and forms part of the agenda to delay climate change. EV sales have ballooned and production of combustion engines will stop soon. In sub-Saharan Africa the transition is slow. Minibus taxis carry more than 70% of commuters and little is known about the electrification requirements. This unc...
Article
Minibus taxi public transport is a seemingly chaotic phenomenon in the developing cities of the Global South with unique mobility and operational characteristics. Eventually this wide-spread fleet of minibus taxis will have to transition to electric vehicles. This paper examines the impact of this inevitable evolution on a city-wide scale in Kampal...
Article
With the increase in variable inverter-based renewable energy sources, power systems become increasingly subjected to stochastic sources. Considering the decline in rotational inertia, the consequence of the continuous spatially distributed perturbations is stochastic frequency dynamics. In this paper, the stochastic dynamics of the power system dy...
Thesis
Full-text available
Due to global environmental concerns, power systems are transitioning from conventional to renewable energy sources (RES). The integration of large-scale inverter-based RES introduces numerous challenges to power system stability, specifically frequency transient stability. The power system becomes more complex and will continue evolving in this di...
Preprint
Minibus taxis are ubiquitous in the developing cities of the Global South. This versatile, and somewhat chaotic public transport system is now faced with the need to move to renewable energy. But the looming roll-out of electric vehicles poses a threat to the already fragile electrical grids of African cities. This chapter evaluates the energy requ...
Conference Paper
Full-text available
The transition to renewable power generation creates new challenges in power system operation. A decline in system inertia with increasing stochastic and distributed power generation will result in fluctuating network frequency. This research paper focuses on the spatial-temporal correlation of meteorological conditions like wind speed and solar ir...
Article
Full-text available
Minibus taxi public transport is a seemingly chaotic phenomenon in the developing cities of the Global South with unique mobility and operational characteristics. Eventually this ubiquitous fleet of minibus taxis is expected to transition to electric vehicles, which will result in an additional energy burden on Africa's already fragile electrical g...
Conference Paper
Full-text available
With the increase in stochastic renewable energy generation, the reliable operation of the power system faces new challenges. This paper implements a stochastic approach to evaluate the impact of correlating generation fluctuations, inverter-based renewable energy penetration and inertia on power system frequency stability using a stochastic differ...
Preprint
Minibus taxi public transport is a seemingly chaotic phenomenon in the developing cities of the Global South with unique mobility and operational characteristics. Eventually this wide-spread fleet of minibus taxis will have to transition to electric vehicles. This paper examines the impact of this inevitable evolution on a city-wide scale in Kampal...
Article
The transitioning from synchronous machine generation to large-scale integration of inverter-based renewable generation introduces new challenges in power system frequency stability. This paper proposes a new approach for evaluating power system frequency stability based on network clusters. First, the most common metrics for power system frequency...
Article
Full-text available
The power system network topology influences the system frequency response to power imbalance disturbances. Here, the objective is to find the network metric(s) contributing to frequency transient stability. The graph Laplacians of six 4-node network topologies are analysed using Spectral Graph Theory. For homogeneous network connections, we show t...
Article
A novel daily and 15-min period solar resource classification algorithm, based only on the Fourier transform of global horizontal irradiance (GHI) and calculable parameters, is presented. These methods can identify GHI series that are not attenuated by clouds, whether the clouds may or may not be visible. Additional sky condition classes are also a...
Preprint
Full-text available
Minibus taxi public transport is a seemingly chaotic phenomenon in the developing cities of the Global South with unique mobility and operational characteristics. Eventually this ubiquitous fleet of minibus taxis will have to transition to electric vehicles. This paper examines the impact of this inevitable evolution. We present a generic simulatio...
Preprint
Full-text available
With the increase in variable inverter-based renewable energy sources, power systems become increasingly subjected to stochastic sources. Considering the decline in rotational inertia, the consequence of the continuous spatially distributed perturbations is stochastic frequency dynamics. In this paper, the stochastic dynamics of the power system dy...
Preprint
Full-text available
The transitioning from synchronous machine generation to large-scale integration of inverter-based renewable generation introduces new challenges in power system frequency stability. This paper proposes a new approach for evaluating power system frequency stability based on network clusters. First, the most common metrics for power system frequency...
Article
Photovoltaic (PV) system power supply is characteristically intermittent. Therefore, PV forecasting is crucial for decision makers responsible for electrical grid stability. With forecast models traditionally trained as macro-level solutions, where a single model emulates the entire PV system, there is uncertainty regarding the ability of these mac...
Article
Low-inertia power systems with a large share of variable renewable energy have less ability to maintain system frequency stability. These networks are at the mercy of the variable meteorological conditions like wind speed fluctuations. This paper investigates the temporal and spatial behaviour of wind speed, how the wind variability impacts the sys...
Article
Full-text available
Field generated data for single-axis-tracker (SAT) photovoltaic (PV) modules, subjected to the semi-arid Northern Cape region of South Africa, is presented. Experimental dust mitigation methods and the effects of dust soiling on PV module performance are explored. In particular, the use of a hydrophobic anti-soiling coating and a unique SAT self-cl...
Article
Full-text available
The objective of this study is to optimise the use of virtual inertia given a virtual inertia budget and a network topology. Following a brief investigation into inertia distribution, it was observed that distributed inertia is more effective than centralised inertia for a large and sparse power system network. A subsection of the South African tra...
Preprint
Full-text available
The power system network topology influence the system frequency response to power imbalance disturbances. Here, the objective is to find the network metric(s) contributing to frequency transient stability. The graph Laplacians of six 4-node network topologies are analysed using Spectral Graph Theory. For homogeneous network connections, we show th...
Preprint
Full-text available
Low inertia power systems with a large share of variable renewable energy have less ability to maintain system frequency stability. Thus, these types of networks are at the mercy of the variable meteorological conditions like wind. This paper investigates the temporal and spatial fluctuations of wind speed, how the wind variability impacts the syst...
Conference Paper
Full-text available
In this paper the filtering effect of a wind turbine is modelled to provide insight into the transient dynamics of a wind turbine generator (WTG), considering the fluctuating/turbulent nature of wind speed and the impact it has on fluctuating power feed-in to a power system. The results show that the turbine inertia of a WTG acts as a first-order l...
Conference Paper
Full-text available
This paper presents the modelling of the total insolation on a collecting surface using a varying water surface albedo model to approximate the reflected radiation. The effect of the water surface on the reflected radiation for a solar collector inclined at a fixed tilt optimum slope is investigated. The annual insolation is approximated to demonst...
Article
Full-text available
The recent reductions in PV costs and the convenient concurrence of insolation and schools' energy usage have resulted in increased interest in augmenting supply with solar PV to save on energy costs and unburden the grid in developing countries.However, optimal sizing of PV solutions requires a detailed analysis and hourly simulation to match dema...
Conference Paper
Full-text available
Varying albedo, due to water surface, is currently not incorporated in PV yield simulation software. In the absence of measured data of reflected radiation from water, a default albedo value of 0.2 is generally used in the modelling of Floating Photovoltaic (FPV) systems. This paper presents modelling of water surface's varying albedo with the chan...
Preprint
Full-text available
The recent reductions in PV costs and the convenient concurrence of insolation and schools' energy usage have resulted in increased interest in augmenting supply with solar PV to save on energy costs and unburden the grid in developing countries.However, optimal sizing of PV solutions requires a detailed analysis and hourly simulation to match dema...
Conference Paper
Full-text available
This paper addresses the impact of high penetration of renewable energy sources (RES), in particular wind and solar power generation on the western transmission network of the South African (Eskom) power system. The study focuses on the power system's stability, specifically the frequency dynamics. With a decline in power system inertia, inertial r...
Conference Paper
This paper investigates network integration of distributed rooftop PV systems on three distribution networks (one residential, one commercial and one industrial) in Cape Town, South Africa. A methodology is developed that can be used to model the technical influence (focusing solely on voltage rise and equipment overload) of randomly distributed so...
Preprint
Full-text available
South Africa's escalating electricity rates are increasingly diverting educational resources to utility bills. Recent advances in solar PV affordability, the advent of the smartgrid and the capacitive nature of water heaters could be combined to enable new methods for electricity cost and efficiency management without affecting user comfort.Control...
Thesis
Full-text available
The monitoring of PV plants is a crucial aspect in ensuring smooth operation and optimum e ciency. Early detection of faults or ine ciencies can greatly reduce downtime and increase overall plant e ciency. Faults include temporary and permanent soiling, shadowing, anomalous ageing and critical electrical or mechanical faults. Many solar installatio...
Thesis
Full-text available
The solar photovoltaic (PV) industry has seen an exponential growth over the last decade, prompted mainly by government incentives and -regulations. Although the global PV industry is dominated by large, utility-scale PV plants, there has been an increase in the uptake of distributed generation (DG) in the form of residential-, commercial- and indu...
Thesis
Full-text available
There is an ever increasing global adoption of solar photovoltaic (PV) technologies as sources of renewable energy due to an increasing worldwide energy demand, the depletion of fossil fuel reserves, the shift towards environmentally friendly sources of energy, and an increasing supply, coupled with a decreasing cost, of solar PV technologies. Ligh...
Thesis
Full-text available
Inverter-based renewable energy generation are integrated into power systems at an increasing rate. Governments continuously set higher goals for renewable energy generation considering only the impact on the environment, development time, financial and economical side, while ignoring the impact of high penetration of inverter-based renewable energ...
Article
Full-text available
South Africa's escalating electricity rates are increasingly diverting educational resources to utility bills. Recent advances in solar PV affordability, the advent of the smartgrid and the capacitive nature of water heaters could be combined to enable new methods for electricity cost and efficiency management without affecting user comfort. Contro...
Conference Paper
Full-text available
Bi-facial PV modelling software is scarce and existing software mainly implements the view factor model which may neglect a number of effects that greatly influence the rear side irradiance of bi-facial modules. This paper shows the results of bi-facial PV simulation software that is being developed by implementing the ray tracing technique to mode...
Article
Full-text available
This paper looks at how the power system of the future will look when the majority of generation comes from inverter-based generation and conventional synchronous generation declines. Today synchronous generators provide inertia to the power system, which slows down the frequency dynamics, allowing for easier frequency control. The purpose of this...
Article
Full-text available
This paper considers the future power system consisting of high share inverter-based generation like solar photo-voltaic (PV) plants. The concern is on the impact this new form of generation will have on power system stability, specifically on the frequency dynamics. The increase in inverter-based generation, means a decline in the synchronous gene...
Conference Paper
Full-text available
Accurate forecasting of PV plants is paramount in ensuring that the electricity grid operates efficiently. This is due to the fact that PV resources have power fluctuations in multiple horizons and the grid has limited storage. An important aspect in creating the forecasting model of a solar PV plant is gathering detailed module-level measurement d...
Conference Paper
Full-text available
This paper identifies the rooftop photovoltaic (PV) potential of three areas in Cape Town, South Africa using a combination ArcGIS 10.5, Google Earth, PVplanner and PVsyst analytic tools. The specific areas investigated are Llandudno (residential), Montague Gardens (industrial) and Century City (commercial). The results of the PV electricity genera...
Conference Paper
Full-text available
The purpose of this paper is to identify cases in which the Schottky barrier diodes, used as bypass diodes in photovoltaic modules, are susceptible to damage as a result of induced currents and voltages caused by nearby lightning strikes. In this paper, a modular voltage impulse generator is used to induce failures within Schottky barrier diodes. T...
Conference Paper
Full-text available
In this paper, two optimisation frameworks are presented as approaches that can improve the process of PV system design optimisation to make it more efficient, integrated and holistic. Of particular interest was how applicable these frameworks would be in a South African context so an existing plant in the Northern Cape province of South Africa was...
Thesis
Full-text available
Improved efficiency of power conversion is high priority when it comes to renewable energy applications. Model predictive control (MPC) can be used to optimise the switching pattern applied in the converter to reduce switching losses. During this research the suitability of a direct MPC strategy with long horisons is evaluated for current control o...
Conference Paper
Full-text available
The monitoring of photovoltaic (PV) modules is an important aspect of efficient PV plant operation. Although various remote telemetry approaches exist, the sheer size of a typical solar PV plant presents challenges for wireless communications. Module-level monitoring devices provide more detail of a solar PV plant's performance than the conventiona...
Conference Paper
Full-text available
This paper provides a contextual summary of the process behind the design of a modular voltage impulse generator. This apparatus forms part of a larger study which aims to identify common causes of photovoltaic (PV) module failures during nearby lightning strikes, with the aim of proposing possible mitigation measures. The paper will firstly scruti...
Thesis
Full-text available
Solar photovoltaics are one of the leading renewable energy generators that are being installed in South Africa. The understanding of how this technology works and how it responds to radiation, is important. This thesis evaluates the different parameters that influence the performance of a solar cell. The parameter extraction method is of interest...
Thesis
Full-text available
Aside from the many existing problems on the electric network; new problems have been introduced with the increased adoption of renewable energy sources. In this thesis, how battery storage systems can be applied in order to address some of the problems is investigated. These problems include: addressing the intermittent nature of photovoltaic powe...
Conference Paper
Full-text available
The performance of variable electricity generation sources such as solar PV and wind is an important consideration in their integration into a power system. The expected performance may affect a number of decisions related to network planning, tariff determinations, energy planning as well as future policy decisions. This study analyses the capacit...
Conference Paper
Full-text available
Data monitoring in utility scale PV systems is an essential part of maximising the energy output of solar PV systems, it serves for the comparison of the initial energy yield assessment with the current plant performance and also captures historic production data. Uncertainty in the solar resource can make the difference between loss and profit and...
Conference Paper
Full-text available
In this paper, three commercially available photovoltaic (PV) system simulation software programs are described and evaluated. The three, namely PVSyt, SAM and PVLib, are assessed according to several criteria to identify their merits and demerits in different PV system modelling stages and scenarios. The work was inspired by the fact that there is...
Thesis
Full-text available
Factors such as the increasing energy demand, the depletion of fossil fuels and the push for more sustainable, less polluting energy sources have resulted in increased interest and inve