Search

The performance and range of electric vehicles are largely determined by the characteristics of the energy storage system (EES) used. The EES should be sufficiently sized to be able to provide the necessary power and energy requirements of the vehicle. Batteries are typically energy dense, although batteries that are both energy and power dense exist, they are much more expensive. The life and usable capacity of batteries are negatively impacted by power impulses. Battery packs in electric vehicles (EV) are typically oversized to be able to provide enough power during these impulses experienced when the vehicle accelerates. An additional EES with a high power density, such as an ultracapacitor, can be used as a buffer to provide power during power surges to reduce the power impulses experienced by the battery. Isolating the battery from the power impulses would allow the EV to utilize more energy dense batteries, increasing the range of the EV as well as increasing the lifetime of the utilized batteries. A hybrid energy storage system (HESS) allows one to utilize the complimentary characteristics of both the battery and ultracapacitor in one system. The method proposed uses a fuzzy logic controller, multiple dc/dc converters, batteries and ultracapacitors in a HESS to minimize the power impulses experienced by the battery, thereby increasing the usable capacity of the battery, whilst being able to deliver high amounts of power for short durations

The research presented in this paper documents the implementation of an active hybrid energy storage system that combined a battery pack and an ultracapacitor bank. The implemented hybrid energy storage system was used to reduce the peak-power that the battery needs to provide to the load. An active topology utilising two direct current/direct current (DC/DC) converters and a switch was used to implement the hybrid energy storage system. Fuzzy logic was used as a closeloop control structure to control the DC/DC converters in the topology, whilst a rule-based control strategy was used to control the operating states of the hybrid energy storage system. Experimental implementation of the system showed that the system was able to actively control the energy flow throughout the hybrid energy storage system in order to limit the power drawn from the battery to a user-defined limit. The performance of the fuzzy logic controllers was also experimentally found to be sufficient when used in conjunction with the rule-based control strategy. The system allows one to utilize batteries that are optimized for energy density seeing that the system was able to actively limit the power drawn from the battery, whilst providing the required power to the load by utilising the ultracapacitor bank

The research presented in this paper proposes a new design of a vaccine cooling and storage unit that can keep vaccines in the cold chain (2°C to 8°C). This design was done to facilitate effective completion of the African vaccination week. The cooling and storage unit was designed to be compact, portable, well isolated and to make use of a PV solar energy system as a source of electricity. The cooling unit makes use of a Liquid to Air thermoelectric cooling module connected to some tubing and a liquid pump to cool the inside of the cooling unit. The design process also included designing a control system that controls the temperature inside the cooling holder and a monitoring system to monitor the battery voltage and capacity. The system also has a user interface that displays the temperatures inside and outside of the cooling holder, as well as the battery voltage and capacity. The cooling system successfully developed was able to keep vaccines in the cold chain for up to three days, the system could control the temperature of the vaccines with an accuracy of 1°C and was small and portable, but still had enough room to house up to 250 vaccines

This paper proposes a novel topology of hybridizing battery, supercapacitor and hybrid capacitor for optimum utilization of energy in electric vehicles. Hybridization of energy storage has been the theme of much research in the field of power electronics as it is an effective economic solution towards improving the utilization of energy. This paper deals with the combination of both supercapacitor and hybrid capacitor with the battery thus addressing the problem of the lack of autonomy between two recharge points in supercapacitors. The prospects of using a multiple-input DC-DC converter is also analyzed. An experimental electric vehicle profile was used to verify the proposed topology and the results are presented. The application of the novel hybridization of the three energy storage devices can be extended to other applications having a load profile with high crest factors

The aim of this paper is to present a new energy monitoring and verification control interface for the Eskom demand market participation (DMP) program that can be implemented on a commercial scale on all the split unit air conditioner systems of consumers actively participating in the program. After the detailed design was completed, the sub-system circuits were created and tested, and evaluation commenced. The sub-systems were integrated after each test and evaluation phase to see whether the system functionality performed as it should have. The final integration was implemented and the final system (consisting of a master – and slave controller unit) were placed inside their enclosures. From there on, the programming logic was modified to and the program was evaluated to see if the completely integrated system was still functional. The slave controller unit was attached to the split unit air conditioner together with the appropriate sensors to monitor and verify the operation of the air conditioner. The developed system was able to successfully monitor the current state of the split unit air conditioner, control it to a specific mode (usually fan mode) according to the required demand at that stage, verify that it has indeed been switched to that specific mode and provide an estimate of the power consumption in the current mode

There has been increasing interests in the use of double layer capacitors (DLCs)—most commonly referred to as supercapacitors (SCs), ultra-capacitors (UCs), or hybrid capacitors (HCs)—in the field of power electronics. This increased interest in the hybridization of energy storages for automotive applications over the past few years is because of their advantage of high power density over traditional battery technologies. To facilitate accurate design and simulation of these systems, there is a need to make use of accurate and well validated models. Several models have been postulated in literature, however, these models have various limitations and strengths, ranging from the ease of use down to the complexity of characterization and parameter identification. The aim of this paper is to review and compare these models, specifically focusing on the models that predict the electrical characteristics of DLCs. The uniqueness of this review is that it focusses on the electrical circuit models of DLCs, highlighting the strengths and weaknesses of the different available models and the various areas for improvement

This paper provides a review on active magnetic bearing (AMB) system limitations, risks of failure and control technologies. Details regarding the operation of an AMB system and background on bearings and sensors are provided. The following benefits for AMBs was identified and are discussed: 1) high reliability, 2) clean environment, 3) high speed applications, 4) position and vibration control, 5) equipment design, development and testing, 6) machine diagnostics, 7) elimination of oil supply, 8) low power consumption and long life, 9) low weight and 10) capability to operate under extreme conditions. The paper further discussed the limitations of AMBs under the following headings: 1) larger bearings, 2) higher complexity and cost, 3) requires electrical power and 4) windage losses. System faults can be broadly classified as either internal or external to the magnetic bearing control system. This classification then relates to the way in which the faults can be dealt with following occurrence. The measures for reducing risks of failure include the following: 1) quality control and standards, 2) systematic check of the design, 3) software development system, and 4) redundancy. Possible future AMB control technologies are likely to be driven by 1) higher operating speeds, 2) lower power loss, 3) greater use of the available clearance, 4) generalised actuation, sensing and control and 5) control of the unbalance response, which are all discussed in this paper. The paper ends with a conclusion on the review of AMB system limitations, risks of failure and control technologies

This paper provides a review on condition monitoring analysis methods for electrical machines. An overview of condition monitoring is provided where online as well as offline monitoring is discussed. A section on vibration monitoring is included, since vibration monitoring is one of the most important online monitoring techniques. As part of vibration monitoring, background vibration, the effect of machine speed and load and variation of a signal at constant operating conditions are discussed. The paper further discussed time and process domain averaging, temperature effects, spurious low frequency ‘ski-slope’ effect and evaluation standards related to vibration monitoring. Various analysis methods exist for the condition monitoring of machines. These analysis methods are divided and discussed in this paper as deterministic and non-deterministic (or statistical analysis approach) methods. The paper ends with sections on condition monitoring measurements and noise filtering during condition monitoring

This paper provides a review on fault detection techniques on active magnetic bearing systems and electrical machines. The following non-linear processing fault detection techniques are discussed in this paper: 1) Time domain analysis, 2) Frequency domain analysis, 3) Time-frequency analysis, and 4) Feature analysis. Time domain analysis is discussed and broken up into data collection, time domain features and Weibull distribution. Frequency domain analysis is discussed and broken up into Cepstrum analysis, enveloped spectrum analysis, equi-sampled discrete Fourier transform, high frequency resonance technique, shock pulse analysis and spike energy analysis. Time-frequency analysis is discussed and broken up into short-time Fourier and bilinear transform, which includes Wigner-Ville distribution. Feature analysis is discussed and broken up into artificial neural networks, feature selection and extraction, feature set reduction, fuzzy logic and pattern recognition. This paper focuses only on nonlinear fault detection techniques and ends with a conclusion on the discussed fault detection techniques for active magnetic bearing systems and electrical machines

Due to the impact of consecutive periods of drought recently being experienced in Africa; food storage and shelf life are decreasing rapidly. Food drying increases the shelf and storage life. Electrical dryers are expensive and electricity availability is a challenge in most African countries. To provide high quality and fast drying, a new intelligent automated active solar dryer is proposed in this paper. The dryer mainly operated on a battery system charged by photovoltaic panels. To produce heat in the oven, a heating element was used which was powered by a battery system. Sensors monitored the temperature, humidity and air velocity inside the dryer house and the data was send to a controller which performed automations on the switching of the convection fans and the heating element. The heating element switching was automated to optimise power consumption. Since the main energy source is solar radiation, a backup energy source was needed for worst case situations regarding weather. A port for electrical energy was installed for operations during cloudy and rainy days. From the results obtained, it was observed that the proposed system with temperature control, humidity control, forced hot air convection and forced humidity extraction offered an improved solution in comparison to the already available methods. These improvements observed are in terms of reduced energy usage, faster drying rate and preserved quality in the dried fruits

Eskom, South Africa’s electricity utility organisation, dedicates an enormous amount of resources in the form of time and money to visually inspect the conditions of these transmission lines on an annual basis. These transmission lines are inspected normally by means of a foot patrol or by flying a helicopter in close proximity to the line. During the foot patrol inspection, a team of people walk from pylon to pylon and inspect the transmission line. Binoculars and IR or corona detection cameras are typically used to aid their inspection. The transmission lines are often located in geographical areas where it is difficult to access these lines by foot; it then becomes necessary to use a helicopter to inspect the line. Various hazards exist in operating a helicopter in such close proximity to these transmission lines and the process of hiring or employing trained specialists to operate the helicopter and the accompanying equipment is costly. Inspecting transmission lines by means of foot patrols or by helicopter is not only costly, but dangerous as well. This paper proposes a new method of transmission line inspection using a solar powered UAV with the inspection equipment mounted on it. The addition of the solar cells to the UAV was beneficial to the overall flight performance of the aircraft, only contributing 6% to the aircrafts total weight, while supplying 20% to 35% of the aircrafts energy needs. This resulted in an approximate increase in the flight range of the aircraft by about 20%

Wind turbines are one of the fastest growing forms of renewable energy. The amount of power a wind turbine extracts from the incoming wind is dependent on the rotational speed and for every wind speed there is an optimal rotational speed that will extract the most amount of power from the incoming wind. Large wind turbines incorporate active control techniques whereas micro wind turbines incorporate passive control techniques with the disadvantage of lower efficiency in controlling the rotational speed and therefore a lower amount of power can be extracted. This paper proposes the development of a new control method that alters the rotational speed of a micro wind turbine in order to improve the power extraction from the incoming wind. This was done by using a DC-DC boost converter controlled by an intelligent fuzzy logic controller on the output of the generator. The controller is also unique, since it only requires the rotational speed and power output of the wind turbine generator, therefore eliminating the difficulties in obtaining the exact wind speed due to the wake effect of the wind turbine tower, whereas the majority of controllers currently in use require the wind speed. The required change in the duty cycle of the DC-DC boost converter is determined by the controller which in turn controls the electromechanical torque of the generator. The design was simulated in Matlab®/Simulink® and practically implemented using Control Desk® and a dSPACE® DS1104 controller board on a 1 kW micro wind turbine generator. Both the simulation and experimental results indicate an improvement in the amount of power extracted by the micro wind turbine generator incorporating the controller, especially during high wind speeds

Currently within South Africa and other developing countries, net-metering policies are not yet widely implemented which hinders the adoption of residential PV systems. Without proper net-metering policies in place, the benefits of residential PV systems are limited to self-consumption as all energy fed into the utility grid is lost without remuneration. This leads to an inefficient and non-profitable PV system. To improve the efficiency and feasibility of the PV system in countries with no feed-in policy, it is of utmost importance that an energy management system (EMS) that optimises self-consumption, of the generated energy, be employed. A new intelligent PV EMS is proposed in this paper which takes historical data of energy consumption and forecasted weather information thereby optimising the energy consumption off the utility grid. Experimental results obtained from a real-world system showed that the local energy consumption percentage increased by 15- 20% when compared to a PV system with no EMS

The research presented in this paper proposes a hybrid energy storage system that combines both electrolytic double-layer capacitors (EDLCs) also known as supercapacitors (SCs) and lithium-ion capacitors (LiCs) also known as hybrid capacitors (HCs) with a battery through a multiple input converter. The proposal was verified in simulation and validated by implementing a laboratory prototype. A new hybridisation topology, which reduces the amount of resource requirement when compared to the conventional hybridisation topology, is introduced. An electric vehicle (EV) current profile from previous research was used to test the performance of the proposed topology. From the results obtained, the hybridisation topology proposed in this research had the lowest cost per unit power at 14.81 $/kW, the lowest cost per unit power to energy, and available power to energy ratio, both at 1:1.3, thus making it a more attractive hybridisation topology than the two conventional alternatives. The multiple input converter built had efficiency values in excess of 80%. The key take away from this paper is that using the proposed hybridisation topology, the battery is less often required to supply energy to the electric vehicle, and so, its cycle life is preserved. Furthermore, since the battery is not used for the repeated acceleration and deceleration in the entire driving cycle, the battery’s cycle life is further preserved. Furthermore, since the battery is not the only storage device in the energy storage system, it can be further downsized to best fit the required base load; therefore, leading to a more optimized energy storage system by reducing the weight and volume of space occupied by the energy storage system, while also achieving better efficiencies

Particulate emission is a major problem in industrial processes, caused mainly by power plants that make use of coal as a primary source of energy. Stringent emissions limits, set by government organisations requires industries to conform to these limits to ensure that air quality is sustained and within minimum pollutant limits. Electrostatic precipitators (ESP) are, implemented as the main form of dust burden collection. In recent years, power stations of the national electricity supplier (Eskom) have struggled to maintain particulate emissions below legislation limits, resulting in power stations having to de-load and reduce power generation production. A pilot project was initiated to investigate what the effects of new high frequency power supplies will be on the ESP collection efficiency. This paper presents the results obtained from the implemented pilot project, whereby 16 new high frequency power supplies (HFPS) were installed in a 28 field ESP plant

This paper compares four different configurations of PM transverse-flux machines. The permanent magnet transverse flux machines with: internal rotor; outer rotor with magnetic shunts; double coil; and outer rotor without magnetic shunts with optimal average air-gap diameter - are designed, analyzed and tested in the laboratory. The study implies that each design has its own advantages and disadvantages in terms of power density, cogging torque, and cost. Special attention is given to the manufacturing process of the machines, materials, and components, which determine the total cost of the machine. Power densities, cogging torque, and cost of the machines are compared and discussed. Conclusions on practical use of the proposed configurations are provided in the paper

This paper presents the electromagnetic analysis of two permanent magnet transverse-flux outer rotor machines with and without magnetic shunts. The research started with designing and analyzing a permanent magnet transverse-flux machine with an inner rotor, previously patented by J. Giearas in 2010. However, the results obtained from the prototype test differed significantly from the estimated results. Applying three-dimensional (3-D) finite element method (FEM), the main problem of the machine was detected. The problem was in high flux leakage that weakened magnetic flux density in the stator poles. Such observation led to designing two machines with outer rotor, with and without magnetic shunts. The role of the magnetic shunts is to minimize flux leakage in the stator in order to improve the performance of the machine. Electromechanical parameters of both outer rotor machines, with and without magnetic shunts, are compared in the paper. Three-D FEM results are supported by laboratory analysis of the machines' prototypes. Experimental measurements proved that the machine with magnetic shunts demonstrated better performance as compared with the machine without magnetic shunts. Presence of the magnetic shunts in the machine resulted in reducing of flux leakage and cogging torque

This paper presents work completed in order to investigate the importance of magnetic shunts in transverse flux machines. Two types of transverse flux machines with different configurations were designed and tested in the laboratory. The first type of machine is a transverse flux generator with inner rotor. This machine was designed according to one of the patents. The second type of the machine is a transfer flux generator with double coil. Both types of the generators were designed in such a way so that it was possible to implement magnetic shunts inside the machines. Finite-element method analysis and experimental results showed that transverse flux machines without magnetic shunts had a number of disadvantages compared to those with magnetic shunts. These disadvantages are: higher flux leakage in the stator cores, partial cancelation of flux linkage in the coils, higher cogging torque, and increased torque ripple. This paper showed that magnetic shunts played a significant role in the performance of transverse flux machines. As study showed, magnetic shunts complicate a manufacturing process and increase the weight of the machine. However, power to weight ratio of the machines with magnetic shunts is higher than that of the machines without magnetic shunts

Due to an ever increasing demand for electricity Eskom is struggling to cope, which inevitably leads to load shedding. Although this is a minor inconvenience for residential users, the effects can be detrimental for businesses. This increases the need for alternative provision of an uninterrupted power supply. Wind energy is a viable solution for this problem as wind turbines proved to be one of the cleanest and fastest growing forms of renewable energy. Although micro wind turbines are the most common type of wind turbines used for homes, businesses, farms or other rural areas, the fundamental drawback is that the majority of these wind turbines are designed to produce maximum efficiency for only a single wind speed. The consequence of a deviation from this designed wind speed is that the overall efficiency of the wind turbine decreases. This problem can be overcome by designing an intelligent controller that allows variable speed operation of the wind turbine and therefore increases the overall efficiency of power extraction from the incoming wind. The method proposed uses a fuzzy logic controller connected to the generator that continuously adapts the rotational speed of the generator to ensure the optimal rotational speed is obtained and therefore extracts the maximum amount of energy from the wind

This paper presents a comparison analysis of two electric motors with helical movement of the rotor. These machines are also referred to as machines with two degrees of mechanical freedom. The machines are designed in such a way that the rotor performs rotary-linear movement. The first machine is a permanent magnet synchronous motor. The motor is a combination of two permanent magnet synchronous motors: conventional rotary and linear motors, which are connected by the mutual housing and shaft. The second motor is an induction motor with mutual rotor, and two stator armatures: linear and rotary. The electromechanical characteristics of both machines were determined and compared. The conclusions about the machines' performance were made

In South Africa the agricultural sector is a significant energy user, with irrigation pumping being the single biggest electricity-demanding farming activity. The agricultural and commercial sectors contribute 6.5% to annual South African electricity sales. Since 2004, Eskom demand side management (DSM) programmes actively engaged farmers to reduce peak period power usage. Farmers with higher power usage were also assisted to move from Landrate tariff structure to Ruraflex in order to incentivise away from peak-period power use. As part of the DSM programme, a number of large evening peak-load-shifting irrigation projects were implemented. Independent measurement and verification (M&V) assessments were made to establish attained savings over the contracted project life. The M&V of DSM projects normally have problems that complicate project assessments, but even taking this into account, the M&V team experienced exceptional difficulties and cumbersome M&V methodology challenges with certain irrigation projects. Normal baseline development methods were ineffective and novel M&V methods needed to be devised and developed. This paper explains the normal M&V methodology used for typical DSM projects and how it is applied. It gives guidance on baseline metering equipment, sampling and metering point selection. Further it demonstrates project specific issues and service level adjustment (SLA) anomalies that render normal M&V methodologies ineffective. It shows novel and alternative baseline development and SLA methods that were incorporated on DSM projects to accurately quantify project impacts

This paper presents a study on a hybrid electric vehicle for mines and other industrial sectors. The power supply system of the vehicle is designed by combining two sources of power: a battery and super-capacitor banks. The benefit of batteries is in sustained energy delivery to enhance energy delivery time, whereas the super-capacitors offer the benefit of short bursts of energy to overcome high power demanding situations. The run-time and maximum performance capabilities of the vehicle were tested in rough terrain conditions typically found in the mining industry. Test results led to conclusions and recommendations which can be valuable for the future research in this area

In this paper, the authors present a twin-armature rotary–linear permanent magnet (PM) motor. The stator consists of two armatures which generate two rotating magnetic fields and the rotor consists of two rigidly coupled parts. Each part consists of PMs on its surface which are skewed in opposite directions. By changing the direction of magnetic field rotation in each armature, the resultant force produced by the motor can be varied between rotary, linear, or rotary–linear. The torque and axial forces acting on the rotor are calculated by using 3-D finite element method analysis. The influence of the PM skew angle on the torque and linear force exerted on the rotor is investigated and presented. The effect of cogging torque and torque ripple reduction for the twin-armature rotary–linear PM motor is also discussed

One of the disadvantages of permanent magnet (PM) transverse flux machines is high magnetic flux leakage in the stator and rotor cores. To improve the magnetic circuit of this class of machines, a generator with double coil was designed and built to research the problem. The machine topology is different from the topologies previously introduced in the literature. The main difference was in the stator and rotor configurations. The stator of the generator is divided by two parts: 1) outer and 2) inner. Two coils were placed in the inner and outer stators. The rotor with PMs was placed between the two stators. To diminish magnetic flux leakage in the stator and to decrease machine’s weight, magnetic poles were placed in aluminum housings. This resulted in high-density eddy currents induced in the housings, and a significant raise of the temperature. The housing of the machine was modified. The prototype test showed that the modified version of the stator contributed to a significant decrease in temperature. Electromechanical parameters and cogging torque of the proposed generator is also studied and presented in this paper

Nowadays, switched reluctance machines (SRM) are gaining interest in the scientific community due to the advantages they offer. The SRM offers an overall efficiency similar to an induction motor of the same rating, since the friction and windage losses are comparable. Many researches have been done on SRMs, their related systems and challenges. This paper reviews the SRM structures, their advantages and disadvantages. Various SRM topologies are studied and their merits and limits are given. Additionally, the most common control strategies for SRM drives are categorized, which is followed by a summary of the researches on challenges in torque and vibration reduction

This paper presents an efficiency analysis of an induction motor with direct torque and flux control at a hot rolling mill in South Africa. Two scenarios were evaluated: 1) where the induction motor was controlled at a constant speed with a variable thickness slab; and 2) where the speed of the induction motor was controlled according to the thickness of the slab. Both scenarios used the speed as reference to control the torque and flux of the induction motor. A comparison on the energy consumption of the induction motor for both scenarios was done by means of a detailed simulation model. The simulation model for this specific case study is explained in detail. The results obtained showed an increase in the efficiency of the induction motor from the original system (scenario 1) to the improved system (scenario 2). Part of this paper provides an overview on hot rolling mills

The purpose of this paper is to verify the power consumption of different topologies of cooling system for the storage of vaccine in a portable solar powered vaccine carrier box for the domestic use in South Africa. The efficiency of the cooling holder is evaluated under normal operating conditions to determine if its cooling capacity is adequate. It is important to know the exact power requirements for the design in order to determine the correct size of the photovoltaic panels and batteries. The cost of the power supply increase with the increase in power consumption due to the increase in the power ratings of the photo voltaic panels and batteries to provide enough power to the Thermoelectric Cooling Modules (TECMs). The objective is to keep the power consumption to a minimum so that the cost of the power supply is kept as low as possible, but still providing enough cooling power for the refrigeration compartment. Various simulations done in SolidWorks® and the temperature profile of different cooling holder topologies were evaluated and discussed and the best topology for the scenario is proposed

The national electricity supplier in South Africa is experiencing difficulty in providing the required electricity, due to compliance with environmental regulations and the continuous price increase of commercial fuels. Making use of renewable energy solutions and energy efficient systems in everyday applications would address this problem. This project focusses on cooling systems, and illustrates an energy efficient cooling system by making use of a pre-cooler for a bulk storage tank. The cooling tank uses thermoelectric cooling modules (TECMs) to cool the milk before it is added to the actual bulk tank, and is controlled by a programmable logic controller (PLC). A small scale model of an actual tank was used to perform tests, which indicated the abilities of the cooling system. Further Solidworks® simulations were done by implementing the measured results, where after it was decided to make use of a pre-cooler, instead of adding the system to a traditional cooling system. A solar power system to power the TECMs was also designed by making use of PVSyst® simulations

This paper provides the development of an axial suspended active magnetic bearing (AMB) experimental bench for load and disturbance tests. This test bench must be capable of levitating a 2 kg steel disc at a stable working distance of 3 mm and a maximum attraction distance of 6 mm. The suspension is accomplished by two electromagnets producing upward and downward attraction forces to support the steel disc. An inductive sensor measures the position of the steel disc and relays this to a PC based controller board (dSPACE® controller). The control system uses this information to regulate the electromagnetic force on the steel disc. The intent is to construct this system using relatively low‑cost, low‑precision components, and still be able to stably levitate the 2 kg steel disc with high precision. The dSPACE® software (ControlDesk®) was used for data acquisition. In this paper, an overview of the system design is presented, followed by the axial AMB model design, inductive sensor design, actuating unit design and controller development and implementation. The paper concludes with results obtained from the dSPACE® controller and evaluation of the axial suspended AMB experimental bench with load and disturbance tests

Transformers are key elements in the industrial processes into which they are integrated. Reliability is crucial to ensure uninterrupted power supply to motors, furnaces and smelters used in a wide variety of applications including primary aluminium and steel plants, mines, pump storage power plants, rail networks etc. For example, referring to ‘references’ in this article – in [1] authors discuss an importance of efficient transformers feeding electric railways

With the national power grid under tremendous pressure, there are enormous pressure exerted on residential electricity consumers to cut-back on electricity consumption to ensure a reliable supply. This has led to residential electricity users wanting to generate their own electricity through solar and wind systems, more formally known as distribution energy resources (DERs). The possibility of DERs currently exists within the centralized power grid, but is currently not well supported by Eskom and local municipalities. There are currently very little widely implemented policies regarding net-metering and feed-in tariff structures amongst Eskom and municipalities. Thus, excess generated energy fed into the grid is used elsewhere without any benefit going to the owner of the DER. By implementing an active energy management system (EMS) alongside the grid integrated system, electricity generated by the DER can be consumed locally by the residential loads. The EMS achieves an electricity consumption reduction of 23. 4 % compared to a system with no EMS. Further results show that the EMS compensated system shows a cost saving of R19.17 per day which translates to a reduction of 51. 4 % compared to a system with no EMS

To reduce strain on Eskom and decrease the cost for producing dairy products, an energy-efficient bulk storage tank using solar power was designed. The system uses thermoelectric cooling modules as a supporting cooling mechanism to the traditional bulk tank cooling methods, and is intelligently controlled by a programmable logic controller

Condition monitoring of electrical cables can prevent cables from failing prematurely. Partial discharge (PD) is the main source for degradation of the insulation material of medium-voltage cables. The well-known capacitor model of Germant and Philippoff was used to create Simulink models for the purpose of simulating PD. A basic model was designed to detect and measure PD activity within the insulation material of medium-voltage electrical cables

Due to the increase of electricity prices in South Africa and the World, there exists the need for energy efficient water heating systems. The authors of this paper conducted a literature study on existing water heating systems. The study shows that there is a possibility of designing more efficient water heating system at lower cost. An in-line water heating system for industrial applications was designed and tested. Before the system was designed a Finite Element Method analysis of the system was carried out to predict the systems’ pressure and temperature. During a physical model test the energy consumption was measured and compared to a conventional storage water heating system. The designed in-line water heating system is shown to be more energy efficient than the conventional storage water heating system. It also had a variety of advantages such as: size, adaptability to a variety of locations, and robustness

In this paper, the development of a portable solar power vaccine carrier box for local usage in Africa and South Africa is described. The purpose is to provide guidance to the design of a thermoelectric cooling holder. An overall design of a cooling holder was done in SolidWorks® and a thermal analysis of the complete systems was done in Flow Simulation. The thermal analysis was done to simulate the cooling capacity of the Thermoelectric Cooling Module (TECM) heat exchanger. Design of the solar power supply including photovoltaic panels, charge controller, and batteries were also done.

The growing demand for energy in the world causes a lot of pressure to the environment and the resources used to supply the energy. To ensure a continuous, more reliable and environmentally friendly energy supply system alternative technologies were developed including photovoltaic panels, wind turbines and hydrogen fuel cells. The hydrogen fuel cell in combination with batteries is used in electric vehicles to minimize greenhouse gas emissions and the strain on crude oil. There is however no effective control applied on the different energy sources within the electric vehicle system. This project focused on developing a controller that would determine the energy source supplying the power demanded by the load. The energy sources include a hydrogen fuel cell, batteries and supercapacitors. The load for the system was simulated on an electronic load using a scaled profile of the power needed by an electronic motor that could be installed in a vehicle. The results showed that by using a controller in the system the motor can operate for a longer time than without the controller. Using a controller would thus increase both the lifetime and energy supplying time of the energy sources within the system

With the world encountering huge pollution problems, use of renewable energy is being encouraged in place of fossils fuels for electricity generation. On such renewable energies is solar power. Solar powered systems are able to generate electricity using photovoltaic (PV) panels, or thermal collectors directly from sunlight. Pool pump electricity consumption has also risen in South Africa. This paper presents the results of the design, and construction of a PV solar system to effect water pumping in rural areas; pool pumping in urban areas. Before the design was completed the load requirement of pump/motor was gathered. PV system software carried out simulations of the design before implementation. A PV solar system prototype was constructed, tested; results verified

Metal, chemical, cement, concrete automobile, mining and other industries struggle to increase the efficiency of the energy they use. Three-phase power transformers play significant role in terms of energy saving, so one method of improving efficiency is to ensure that power transformers operate within their rated loads. However, many industries experience problems with inefficient power transformers

In this paper, the authors present the impact of thermoelectric cooling modules (TECMs) on the efficiency of a single-phase asynchronous machine. TECMs are used to lower the stator winding temperature and core temperature of the single-phase asynchronous machine. A similar effect might be possible by operating the asynchronous machine in a controlled lower temperature environment or by using other means of improved controlled cooling. An overview on the materials and method used during the experimental setup of the single-phase asynchronous machine with the TECMs is provided. Experimental results on the efficiency analysis, temperature analysis and equivalent circuit parameter analysis are provided. It is shown that the efficiency of the single-phase asynchronous machine can be increased by 4.44% when cooled by TECMs

Power factor correction (PFC) is common in commercial and industrial applications. A need to extend its application increased with the dwindling natural resources used for power generation and also exceeding energy demand, hence more efficient motor systems and power usage are required at the forefront of utility's demand side management system. The aim is to design and build an active PFC using a boost DC/DC converter and implement it on a single phase induction motor for residential and small industrial applications. However it can be developed to a three phase system for bigger industrial applications. The basic architecture includes a power supply, a rectifier, DC/DC boost converter (for the system with PFC), an inverter, control circuitry, and a single split phase induction motor. The energy usage of the motor without PFC is recorded and compared with energy of a motor with PFC. The cost analysis of the two energy usage is compared and the objective is to realise some savings. This paper discusses system design, influence of the PFC on the system's power consumption and power factor, comparing the results between two systems, and cost evaluation

Condition monitoring of electrical cables can prevent cables from failing prematurely. Partial discharge (PD) is the main source for degradation of the insulation material of medium-voltage cables. The well-known capacitor model of Germant and Philippoff was used to create Simulink models for the purpose of simulating PD. A basic model was designed to detect and measure PD activity within the insulation material of mediumvoltage electrical cables

T he rapid growth of the cement and concrete industry has created the need for concrete products such as concrete pipes, culverts, manholes, slabs, piles, etc. Since the role of electric machines in the concrete industry is vital, this article focuses on presenting the design of an energy efficient concrete mixer drive. The novelty of the proposed synchronous permanent magnet (PM) motor is in its ability to develop helical movement of the rotor. This allows the mixer blades to mix concrete compound effectively with minimal energy consumption. The machine was analysed in 3D FEM and Matlab/ Simulink software. Efficiency and rated power were also determined. The energy consumption of the proposed synchronous motor drive is compared to that of a conventional induction motor. Conclusions about the effectiveness of using the proposed machine in concrete mixers were made. The advantages of the proposed motor over conventional induction drives used in industrial mixers are also discussed

Globally around 40% of the electricity supplied to the industrial and mining sectors is consumed by electric motorised systems and for South Africa around 60% of the electricity supplied to these sectors is consumed by asynchronous machines. The efficiency of these asynchronous machines can be improved by reducing their operating temperatures

To reduce strain on Eskom and decrease the cost for producing dairy products, an energy-efficient bulk storage tank using solar power was designed. The system uses thermoelectric cooling modules as a supporting cooling mechanism to the traditional bulk tank cooling methods, and is intelligently controlled by a programmable logic controller

Eskom owns thousands of kilometres of transmission lines that need to be inspected in order to plan maintenance. Current methods of inspection are costly and ineffective and could pose safety risks. Systems already developed for inspection purposes do not meet the specifications as determined by Eskom for transmission line inspection. A solution is proposed by the design and construction of a monitoring system consisting of a single board computer (SBC), USB video and infrared cameras, and a GPS unit. The system is attached to a quadcopter that flies along the transmission line to collect data. Software is developed that stream the video and GPS data to a monitoring station and provide logging capability

A need exists for a transmission line monitoring system for use by Eskom to inspect transmission lines. A solution which uses a single board computer, visual and infrared cameras and a GPS module is described. Real-time data streaming from the cameras, GPS and fault logging capability was achieved

South African state-owned utility company, Eskom, is under severe pressure to ensure the stability and reliability of the national electricity grid. With a shortfall in capacity of the national electricity grid, the possibility of distribution level generation in the form of micro-grids takes rise, Onlangse persvrystellings en media-aankondigings deur die Suid-Afrikaanse staatsbeheerde nutsmaatskappy, Eskom, dui daarop dat die nasionale kragnetwerk onder geweldige druk is. Daar word enorme druk deur residensiële- en industriële elektrisiteitverbruikers uitgeoefen om die betroubaarheid van 'n stabiele kragnetwerk te verseker. Die moontlikheid van 'n mikrokragnetwerk bestaan wel binne die huidige gesentraliseerde kragnetwerk, maar word tans nie baie goed ondersteun deur Eskom en streekmunisipaliteite nie. Mikrokragnetwerke verwys na kragopwekking deur onafhanklike kragprodusente op distribusie- en transmissievlak. Mikrokragnetwerke kan as 'n selfstandige, kragnetwerkgeïntegreerde of hibriede kragnetwerk opgestel word. Sodoende, met toepassing van hierdie topologieë, kan die mikrokragnetwerk aanvullend tot die gesentraliseerde kragnetwerk wees. In eerstewêreldlande soos België en Switserland word mikrokragnetwerke baie goed ondersteun deurdat die nutsmaatskappye oortollige gegenereerde elektrisiteit by die mikrokragnetwerk terugkoop. Dit is egter nie die geval in Suid-Arika nie en oortollige gegenereerde elektrisiteit gaan verlore. 'n Residensiële energiebestuurstelsel kan die genoemde probleem oorkom deur aktiewe monitering en bestuur van die mikrokragnetwerk se inkomende en uitgaande energie

A new dynamic model is developed in this paper to connect PEM Fuel Cell (PEMFC) to a Z-source inverter (ZSI). This model is used to analyse the behaviour of a fuel cell by providing a polarization curve. A controller is designed based on an interpolation to spot parameters of PEM Fuel Cell such as temperature (or anode and cathode pressure). A current feedback is gained to regulate the output voltage through determination of physical parameters. The ZSI is used in the proposed model to generate AC power. In this research, to compensate the voltage drop of fuel cell the capacitor voltage of the Z-network is controlled using the state space averaging method to stabilize the AC output voltage of the ZSI. Simulation and experimental results verify the validity of the proposed controlling model

The national energy supplier (Eskom in South Africa) supplies electricity through thousands-of-kilometers of overhead power lines. The current methods of inspection of these overhead power lines are infrequent and expensive. In this paper, the authors present the development of a prototype monitoring system for power line inspection in South Africa. The developed prototype monitoring system collects data (information) from the overhead power lines, is remotely accessible and fits into a power line robot. The prototype monitoring system makes use of a PandaBoard® (SBC) with GPS receiver and 5 MP camera to collect data. Hardware fatigue is the biggest problem faced on the overhead power lines and is captured by means of the 5 MP camera and is displayed on a website hosted by the PandaBoard® via Wi-Fi. The monitoring system has low power consumption, is light weight, compact and easily collects data. The data obtained from the prototype monitoring system was satisfactory and provides an improved solution for monitoring power lines for Eskom in South Africa

A three-phase shunt active filter is used for current and/or voltage unbalance compensation. Two control schemes with two different theory, instantaneous power theory and Generalized Fryze are considered to compensate the unbalance of current, voltage, or both that are due to the unbalanced load. The compensation results of the different control schemes in unbalance case are simulated and results are shown here. Different compensation objectives can be achieved, i.e., balanced and unity power factor source current, balanced and regulated voltage, or both, by choosing appropriate control schemes by using Instantaneous Power theory. In the case of Generalized Fryze it is seen that the current compensated by means of the generalized Fryze currents method makes the compensated line current proportional to the corresponding phase voltage, that is, they have the same waveform and behave like a “pure resistive” load