Conference Paper

Design of an intelligent controller for a renewable energy efficient bulk storage tank

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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.

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... It was thus decided to make use of TECMs as the cooling mechanism and testing it as the cooling device combined with the cooling liquid and a pump for a prototype of the actual transformer. TECMs have also been used as part of an air-conditioning system in a previous project in [5], a TECM holder for vaccines in [6] and for a bulk tank on a dairy farm in [7]. The research for the support of renewable energy was done on solar energy. ...
... The TECMs were suggested by the client as cooling devices and have been used in previous final year projects [5][6][7] -in 2012 as part of a "TECM holder" for vaccines, in 2013 as part of a "Mini TECM Solar Air Conditioning System" and, in 2014 as an "Energy efficient bulk tank." Thus the investigation was not done in depth as the component has already been supported by other articles. ...
Conference Paper
The national electricity supplier in South Africa (Eskom) struggles more and more each year in supplying sufficient amount of power. This is partially due to residential consumers that use appliances that require more power. This results in transformers that overheat which decrease the efficiency of the transformer. A possible solution to this problem is to cool the transformer in a controlled manner. This paper therefore provides the design of a controlled cooling system for a three-phase power transformer that is energy efficient and also makes use of renewable energy. The cooling of the transformer make use of a thermoelectric cooling module (TECM) which is controlled by an programmable logic controller (PLC) which receives its data from a PT 100 thin sensors which is placed between the windings and core of the transformer. A prototype model of the actual transformer was used to perform the tests to indicate the cooling results. Solidworks® where used for the transformer simulation which were then implemented based on the results. Solar energy was used as renewable energy which was simulated by PVSyst®.
... Also see other projects [1]- [3]. ...
Technical Report
This project aims to implement an energy monitoring and verification interface for Eskom on a commercial scale through the control of split control air conditioner systems. Sufficient research was conducted regarding the subject which in turn led to a proposed solution for the given problem. A literature study was conducted based on a conceptual design model and all the sections involved was inspected and discussed. The project budget, timeline and other factors regarding this problem were planned in accordance to this proposed solution. The literature study compared different components with each other and the properties of these various components were listed. A trade-off study was completed by using the information gathered from the literature study to make intelligent component selections based on the engineering process. To do the trade-off study on the selected components, a certain criterion had to be considered to rate the components. The criteria chosen to rate these components were mainly centralized around four points namely: cost, efficiency (or reliability), complexity and availability. The components with the highest rating were selected and a more detailed approach was taken. Programming flowcharts were created to show how the logic of the code would be when implemented. Enclosures, which housed the component, were designed to keep the user safe and which added an aesthetical aspect to the project. After the detailed design was completed, the sub-system circuits were created and testing 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 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.
Technical Report
Wind turbines are one of the fastest growing forms of renewable energy. This is mainly due to wind turbines being one of the cleanest and cheapest form 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 in order to control the rotational speed and ensure the maximum amount of power is extracted from the wind. This usually involves altering the pitch of the blades or the direction of the wind turbine with regards to the incoming wind. Using these active control techniques to control the rotational speed of micro wind turbine creates mechanical and economical difficulties. This results in micro wind turbines incorporating passive control techniques with the disadvantage of lower efficiency in controlling the rotational speed, and therefore the amount of power extracted, when compared to active control techniques. For this project a controller was developed that altered the rotational speed of a micro wind turbine in order to increase the amount of power extracted from the incoming wind. This was done by using a DC-DC boost converter controlled by a fuzzy logic controller on the output of the generator. The controller only requires the rotational speed and power output of the wind turbine generator whereas the majority of controllers require the wind speed and therefore eliminates the difficulties in obtaining exact wind speed due to the wake effect of the wind turbine tower. 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. After the controller was developed, 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.
Technical Report
The industry has changed over the years and makes use of PLCs to control bulk electronic devices. It's found that combining these controllers with motor drives such as VFDs, better the efficiency of motors in a substantial way. South Africa needs more generation capacity like any other country, of which the national electricity supplier, Eskom, can provide it with. Eskom uses drive systems for process control because of the energy efficient benefit, and it is quickly becoming the most used method of control in the industry. Efficiency of motors is at its best around 75% at full-load point, and this is a major problem having a costly effect on the production of large companies. Drive systems are considered to be the most energy efficient way of controlling motors. Combining these drives with PLC control can result in great energy efficiency, which can in turn only benefit the country as well as other countries. Eskom in association with other suppliers has spent much time and resources on this. To address this problem, a PLC-based control system was designed for a three-phase induction motor. The system is designed using a PLC for intelligent control on a three-phase induction motor and DC generator. The motor is tested on four different control speeds (rpms), of which each of these rpm reference values are tested on three different load condition provided by the generator. The system was designed by making use of simulations, assembling the product, and comparing the theoretical results with the practical results in the end. The intelligent control system for the three-phase induction motor in combination with the assembled product turned out to be very effective. The theoretical and practical results were compared and the system in whole showed positive efficiency results. Eskom with their resources may implement such a system and will definitely see energy efficient results in the long term. A conclusion and recommendations are discussed, along with suggested future work on the project.
Technical Report
The purpose of this project was to make use of cost effective and improved technology that increases the efficiency of lectures. This project was mainly software-based and was implemented for mostly educational purposes, and being in a technological era, it will grant the lecturer the ability to present classes through an interactive whiteboard using existing classroom infrastructure, simplifying the way information will be digitally conveyed. Both students and lecturers will benefit from this project, for the smartboard will improve the way the class is presented, attaining more attention from students and enabling the lecturer to present digital lectures in an interactive way and save each lecture digitally to use for future study purposes. After several meetings and discussions, as well as an intensive literature study on the various ways and methods available to complete the project, the decision was made that the Nintendo ® Wii remote whiteboard will be used. The Nintendo ® Wii remote whiteboard is an interactive whiteboard display that makes use of the current infrastructure installed at the university (computers and projectors) as well as a Nintendo ® Wii remote, an Infra-Red pen and a PC suite to control the Bluetooth connectivity for the Nintendo ® Wii remote and for the functional use of the whiteboard. The whiteboard joins the different functionalities of the underlying components to create an effective whiteboard. The Nintendo Wii remote is equipped with a high speed, high resolution Infra-Red camera which is used to detect the Infra-Red dots created by the Infra-Red pen and sends this data to the PC via Bluetooth connectivity. The PC suite interprets the incoming data from the Nintendo ® Wii remote and calculates the position the dot appears on the display, which is simulated by a mouse left-click by the suite. The projector will project the image as well as the alterations made by the lecturer, thus students can see real time changes made to any image or presentation, and for this reason the whiteboard can function as a chalkboards as well.
Technical Report
The national electricity supplier has been reducing their generating capacity in order to comply with environmental regulations and is experiencing further supply difficulty due to the continuous price increase of commercial fuels. Cooling systems are one of the largest everyday energy consumers, and its contents are the first to be negatively affected by the unavailability of power.
Technical Report
Something that every person who has ever owned a swimming pool will tell you are that the time, money and effort put into it is not worth the few hours spent in it. Luckily in the last few years pool automation systems made their way to the markets minimizing the hassle to maintain swimming pool levels, chlorine, temperature, lights etc. Unfortunately these types of systems are very expensive and could well cost up the tens of thousands of Rands. In today's society swimming pool automation systems no longer seems to be a luxury but a necessity. This project focussed on the development and implementation of a low cost swimming pool automation system, with quality and reliability kept in mind. The system must take care of the day to day maintenance tasks of maintaining a healthy swimming pool, also the developed system must be user friendly.
Conference Paper
Full-text available
South Africa is currently in the grips of a severe power supply capacity constraint; January 2007 has already seen blackouts throughout the country, the worst is still expected in the months to come. As a measure of immediate remedy Eskom is turning to Demand Side Bidding (DSB); a methodology whereby the demand side has an opportunity to sell back flexible load to the supply side. Through this paper an assessment of DSB is carried out, with the aim of evaluating and gauging the current and potential future standing of DSB as a technology product within the South African context. The assessment is carried out using the technology balance sheet, the technology road map and the scenarios approach. The results of the assessment show that DSB is not a sustainable solution to the current power supply capacity constraint Eskom is facing.
Technical Report
Infectious diseases are the main course of deaths or disabilities among infants and young children in rural parts of Africa. The most effective and cheapest method to prevent infectious diseases is vaccine. These vaccines are administered into the body of patients during routine immunization programs. The most important part of these immunization programs is the cold chain system. This system implies the storing and transporting of vaccine from the manufacturer to the patient in a certain temperature in order for it to stay in a potent state. All vaccines lose their potency if exposed to heat or when it is frozen. Obviously is it pointless to immunize with vaccine which has lost its potency. The storing standards of vaccine set out by the World Health Organization (WHO) state that vaccine should be stored within 2˚C to 8˚C. The delivery of vaccine brings about the most practical problems. In order to deliver vaccine to patients in a potent state, the most important tool is functioning freezers and refrigerators. These cooling containers must also be rugged and find a mean to power itself as it will be used in rural parts of Africa where no electricity is available. In this paper, the development of a portable solar powered vaccine carrier box is described. Thermoelectric cooling systems pumps heat in the most direct way, through the use of electricity, with plenty of extra benefits. In order to successfully design a vaccine cooling holder, that utilizes thermoelectric technology as a heat pump, it was necessary to determine if the cooling power of this type of technology would be satisfactory for the application. The formulas supplied by the manufacturer as well as thermoelectric theory formulas were used to do a detailed TECM (Thermoelectric Cooling Module) size estimation. TECMs with different voltage, current and heat pumping capabilities are available and that is why it is important to determine the correct heat pumping capability needed for a given application. The hot side of the cooling holder is cooled by using a heat sink and fan assembly, due to the size and complexity when compared to water cooling. A heat exchanger with a very high efficiency should be used to cool the hot surface of a TECM. A complete design of the cooling holder was constructed in SolidWorks and a thermal analysis of the complete systems was done in Flow Simulation. The thermal analysis was constructed to simulate the cooling capacity of the TECM heat exchanger under variable ambient temperatures and input powers. These results from the simulations were then examined to determine if the design is appropriate. These results were also used to verify that the manufacturer's claims for the cooling capacity are valid. These simulations ensure that the results are optimum and that a proper prototype of the design can be implemented. The simulations reveal that the use of a under sized TECM will result in poor cooling characteristics and the use of an over-sized TECM will result in large energy consumption and an inefficient system. The simulation results were used to construct a prototype cooling holder with the exact dimensions as the designed cooling holder. The prototype cooling holder is practical with a large enough cooling space to store a large amount of vaccine. It is fitted with a temperature control circuit that ensure that the temperature of the cooling space stays between 2˚C to 8˚C. A complete design for the solar power supply; including photovoltaic panels, charge controller and batteries; was done. Due to the large energy consumption of the TECMs the designed solar power supply is too big to make the system portable. The prototype cooling holder was tested, and its cooling capabilities were compared to the simulation results. The simulations results and the actual results do not differ substantially.
Technical Report
As climate change takes place in the world, more and more people are using air conditioners for the purpose of cooling as well as heating. The conventional air conditioner is fast becoming a noticeable energy user that negatively affects the supplier's ability to supply energy in peak times as the country's energy need rises. The Clean Development Mechanism (CDM) stipulates that a country committed under the Kyoto Protocol, has to implement emissions-reduction programs in developing countries to help reduce the CO 2 Emissions around the world. By designing a mini solar thermoelectric cooling module (TECM) air conditioner, the system will decrease the amount of energy used from the supplier and the system may also contribute to the Cap and Trade movement that is on the horizon. Replacing one or two conventional air conditioners with a solar TECM air conditioner system, will not be greatly beneficial for a company, but by replacing every conventional air conditioner in a business or country will significantly help with energy shortages as well as reduce a business' or country's carbon footprint. By making use of renewable energy sources it was seen that this project can greatly benefit the environment as well as help the national electricity supplier to reduce the daily peak time energy demand of South Africa. By taking the air conditioners of the near future off the national electricity grid will help reduce the CO 2 emissions of a business or country and will ultimately contribute to the Cap and Trade Movement. It was seen that the initial cost of the mini TECM solar air conditioning system will be relatively higher than the installation of a conventional air conditioner, but as this project qualifies as a renewable energy project that helps relieve the immense pressure Eskom is facing to supply South Africa with the desired peak time energy, Eskom has subsidiaries in place to help such projects get started. From the SolidWorks ® Flow Simulation it was seen that the 4 TECMs configuration will be optimal for the use within the air conditioning system.
Conference Paper
Recent concerns about environmental issues led to global energy policies oriented to new energy sources less polluting and cheaper. Energy produced by photovoltaic technology is clean and renewable. The actual problem is that currently the price of photovoltaic systems is relatively high. Research in this field is now focused on improving the efficiency of electricity production using photovoltaic technology. For this each component of a photovoltaic system must enroll on this course. Solar battery chargers are an important component of photovoltaic systems that could bring significant efficiency improvements through technology. The paper proposes a study on the types of solar battery chargers from the simplest to the most cutting edge technology, chargers searching for the MPP (maximum power point). An MPPT (Maximum Power Point Tracking) charger plays an important role in photovoltaic systems because it maximizes the power output of the photovoltaic panel array for different levels of irradiation and panel temperature leading to more energy harvested.
Conference Paper
In this paper, operator based nonlinear control system of an aluminum plate with a Peltier device is designed by using operator theory. A model of an aluminum plate with a Peltier device is derived. The parameters on Peltier device of model is evaluated by experiment. After that, operator based nonlinear temperature control system by using robust right coprime factorization is designed for the model. The effectiveness of the designed system is confirmed by simulation.
South Africa alone produces move than half of the electricity generated in the entire African continent. In spite of this about, half of South Africans are without electricity in their homes. South Africa's energy production and distribution patterns bear a striking resemblance to its overall economy-a heterogeneous intermingling of First and Third World characteristics. South Africa as a whole is responsible for about 2% of the world's greenhouse gas emissions although it has only 1% of the world's population. The normalisation and democratisation of the country will require enormous efforts to provide electricity, running water and education for the majority of the South Africans previously disadvantaged in the apartheid era. South Africa is trying to comply with the global demand for sustainable development by improving the technologies of its power plants, implementing renewable energy sources, improving efficiency of utilisation of electricity in industry and homes, adopting more efficient standards for electrical appliances, changing of the way of life etc. Although there are some constraints, the country is capable of overcoming these in the years ahead given the political will and proper international assistance
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