Arnold Johan Rix

Stellenbosch University | SUN · Department of Electrical & Electronic Engineering

A novel spectral-corrected Performance Ratio calculation method that aligns the short-term Performance Ratio calculation to the annual calculated Performance Ratio is presented in this work. The spectral-corrected Performance Ratio allows short-term measurements to reasonably estimate the annual Performance Ratio, which decreases the need for long-...

This research develops and validates new decomposition models for hourly direct Normal Irradiance (DNI) estimations for Southern African data. Localised models were developed using data collected from the Southern African Universities Radiometric Network (SAURAN). Clustered areas within Southern Africa were identified, and the developed cluster dec...

The research develops and validates new decomposition models for DNI estimations from Southern African data. The results demonstrated improved DNI estimation accuracy compared to the baseline models across all testing and validation datasets. These outcomes suggest that utilising a localised model can significantly enhance DNI estimations for South...

p>Large photovoltaic (PV) modules comprise multiple series-connected internal strings, which are in turn composed of series-connected PV cells. When excited with time-varying signals, the loops formed by these internal strings couple to each other. Until now, this coupling has not been considered in any radio frequency interference studies of PV sy...

p>A novel circuit-computational electromagnetic (CEM) hybrid simulation methodology, which results in vast improvements in the accuracy of high-frequency photovoltaic (PV) modelling between 1 Hz and 50 MHz, is proposed. At low frequencies, the impedance of a PV module is dominated by the behaviour of the PV cells, while at high frequencies it is do...

p>This study presents a simulated analysis of the response of a photovoltaic (PV) module to a single indirect lightning stroke. It does so by separately passing positive and negative 20 kA, 8/20 µs lightning current waveforms through a wire in space, located 1 m from the centre of a vertically-orientated PV module, and monitoring the voltages and c...

p>Lightning-produced electromagnetic fields can couple into photovoltaic (PV) installations and cause damage. This study examines the far-field radiation patterns of a small and a large PV module between 9 kHz and 30 MHz – by both measurement and simulation. Due to reciprocity, these are also the susceptibility patterns. Firstly, the radiation patt...

p>This study presents a simulated analysis of the response of a photovoltaic (PV) module to a single indirect lightning stroke. It does so by separately passing positive and negative 20 kA, 8/20 µs lightning current waveforms through a wire in space, located 1 m from the centre of a vertically-orientated PV module, and monitoring the voltages and c...

Due to the stochastic behaviour of wind power generation, accurately predicting wind speed and power generation is fundamental to the reliable and large-scale adoption of wind power integration onto the electrical grid. In this research paper, a compact review is presented on wind power forecasting, which focuses on the classification of methods an...

This paper focuses on modelling the influence that the reflected light spectrum has on the rear side of a bifacial PV module. The front and rear-facing spectrums as well as current-voltage (I-V) curves for the front and rear side are measured for a bifacial PV module on two different surfaces (white gravel and grass). The five parameters of a singl...

Estimation of solar photovoltaic (PV) module operating temperature is an important component of accurate PV system simulation and design. Faiman's module temperature model provides a simple method of estimating PV module operating temperature using empirical heat dissipation factors (HDFs) and is widely used in PV simulation. This paper presents HD...

Hydrogen production through water electrolysis, coupled with renewable energy sources presents a promising solution to significantly reduce carbon emissions. A substantial body of research has been conducted in the integration and modelling of these two domains, resulting in numerous models and simulation approaches being presented in the literatur...

p>Lightning-produced electromagnetic fields can couple into photovoltaic (PV) installations and cause damage. This study examines the far-field radiation patterns of a small and a large PV module between 9 kHz and 30 MHz -- by both measurement and simulation. Due to reciprocity, these are also the susceptibility patterns. Firstly, the radiation pat...

p>Lightning-produced electromagnetic fields can couple into photovoltaic (PV) installations and cause damage. This study examines the far-field radiation patterns of a small and a large PV module between 9 kHz and 30 MHz -- by both measurement and simulation. Due to reciprocity, these are also the susceptibility patterns. Firstly, the radiation pat...

p>Large photovoltaic (PV) modules comprise multiple series-connected internal strings, which are in turn composed of series-connected PV cells. When excited with time-varying signals, the loops formed by these internal strings couple to each other. Until now, this coupling has not been considered in any radio frequency interference studies of PV sy...

p>Large photovoltaic (PV) modules comprise multiple series-connected internal strings, which are in turn composed of series-connected PV cells. When excited with time-varying signals, the loops formed by these internal strings couple to each other. Until now, this coupling has not been considered in any radio frequency interference studies of PV sy...

p>A novel circuit-computational electromagnetic (CEM) hybrid simulation methodology, which results in vast improvements in the accuracy of high-frequency photovoltaic (PV) modelling between 1 Hz and 50 MHz, is proposed. At low frequencies, the impedance of a PV module is dominated by the behaviour of the PV cells, while at high frequencies it is do...

p>A novel circuit-computational electromagnetic (CEM) hybrid simulation methodology, which results in vast improvements in the accuracy of high-frequency photovoltaic (PV) modelling between 1 Hz and 50 MHz, is proposed. At low frequencies, the impedance of a PV module is dominated by the behaviour of the PV cells, while at high frequencies it is do...

A review of quality control for large irradiance datasets is applied as a case study for the Southern African Universities Radiometric Network (SAURAN) database. The quality control procedure is automated and applied to 24 stations from the database with a total of 848,189 hourly datapoints. From this, the individual station’s data quality is also...

Planning for the eventual electrification of transport in sub-Saharan Africa requires accurate simulation of its unique transport systems. The few studies that attempt to model electric minibus taxis—vehicles extensively used in sub-Saharan Africa’s public transport systems—vary greatly in their results. This paper analyses, compares and corrects t...

As fuel prices climb and the global automotive sector migrates to more sustainable vehicle technologies, the future of South Africa's minibus taxis is in flux. The authors' previous research has found that battery electric technology struggles to meet all the mobility requirements of minibus taxis. They investigate the technical feasibility of powe...

p>Planning for eventual electrification of transport in sub-Saharan Africa requires accurate simulation of its unique transport systems. The few studies that attempt to model electric minibus taxis – vehicles extensively used in sub-Saharan Africa’s public transport systems – vary greatly in their results. In this paper, we analyse, compare and cor...

p>Planning for eventual electrification of transport in sub-Saharan Africa requires accurate simulation of its unique transport systems. The few studies that attempt to model electric minibus taxis – vehicles extensively used in sub-Saharan Africa’s public transport systems – vary greatly in their results. In this paper, we analyse, compare and cor...

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. However, the looming roll-out of electric vehicles poses a threat to the already fragile electrical grids of African cities. This chapter evaluates the energy...

An emerging area of interest within photovoltaic (PV) centred research is the simulation of the propagation of electromagnetic interference (EMI) and surges within PV installations. An overarching constraint in all simulation-based research is the accuracy of the models employed. In general, for PV-focussed simulations, nonlinear models are utilise...

Decarbonisation of Africa’s informal paratransit through electrification requires adequate data captured correctly. Field workers getting on-board as passengers with tracked phones are extensively used to measure flow rates and volumes of passengers and vehicles on sections of roads in transport planning applications. Although this method is accept...

The modelling of surges within PV (photovoltaic) installations has been the subject of much research in recent years. However, accurate simulations cannot be performed unless each and every component within a PV installation is modelled in sufficient detail. The bypass diodes within a PV module are frequently omitted from such simulations. When inc...

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...

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...

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...

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...

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...

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...

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...

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...

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...

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...

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...

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...

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...

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...

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...

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...

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...

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...

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...

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...

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...

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...

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...

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...

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...

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...

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...

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...

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...

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...

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...

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...

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...