No description available.

An ever-expanding global industry focuses attention on energy supply and use. Cost-effective electrical energy production and reduced consumption pave the way for this expansion. Eskom’s demand-side management (DSM) initiative provides the opportunity for reduced electricity consumption with cost-effective implementation for their respective clients. South African gold mines have to extend their operations to up to 4000 m below the surface to maintain profitable operations. Deep-level mining therefore requires large and energy-intensive cooling installations to provide safe working conditions. These installations generally consist of industrial chillers, cooling towers, bulk air coolers and water transport systems. All of these components operate in unison to provide chilled service water and cooled ventilation air underground. In this study the improved energy efficiency and control of a South African gold mine’s cooling plant is investigated. The plant is separated into a primary and secondary cooling load, resulting in a cascading cooling system. Necessary research was conducted to determine the optimal solution to improve the plant’s performance and electrical energy usage. Variable speed drives (VSD) were installed on the chiller evaporator and condenser water pumps to provide variable flow control of the water through the chillers, resulting in reduced motor electricity usage. Potential electricity savings were simulated. Proposed savings were estimated at 600 kW (13.6%) daily, with an expected saving of R 2 275 000 yearly, resulting in a payback period of less than 9 months. Results indicated are based on total savings, as VSD savings and control savings were combined. The VSDs that were installed, were controlled according to an optimum simulation model’s philosophy. A real-time energy management program was used to control the VSDs and monitor the respective systems. The program’s remote capabilities allow for off-site monitoring and control adjustments. A control strategy, which was implemented using the management program, is discussed. Energy efficiency was achieved through the respective installations and control improvements. The results were analysed over an assessment period of three months to determine the viability of the intervention. A newly installed Bulk Air Cooler (BAC) added to the service delivery of the cooling plant post installation of the VSDs. Focusing on service delivery to underground showed a savings of 1.7 MW (33.6%) daily and a payback period of 3.6 months (0.3 years). The overall implementation showed an average energy saving of 2.3 MW (47.1%) daily, with the result that a daily saving of R 23 988.20 was experienced, reducing the payback period to 2.3 months (0.2 years). Through the installation of energy-efficiency technology and a suitable control philosophy, a cost-effective, energy-efficiency improvement was created on the case-study cooling plant. / MIng (Mechanical Engineering), North-West University, Potchefstroom Campus, 2014

An ever-expanding global industry focuses attention on energy supply and use. Cost-effective electrical energy production and reduced consumption pave the way for this expansion. Eskom’s demand-side management (DSM) initiative provides the opportunity for reduced electricity consumption with cost-effective implementation for their respective clients. South African gold mines have to extend their operations to up to 4000 m below the surface to maintain profitable operations. Deep-level mining therefore requires large and energy-intensive cooling installations to provide safe working conditions. These installations generally consist of industrial chillers, cooling towers, bulk air coolers and water transport systems. All of these components operate in unison to provide chilled service water and cooled ventilation air underground. In this study the improved energy efficiency and control of a South African gold mine’s cooling plant is investigated. The plant is separated into a primary and secondary cooling load, resulting in a cascading cooling system. Necessary research was conducted to determine the optimal solution to improve the plant’s performance and electrical energy usage. Variable speed drives (VSD) were installed on the chiller evaporator and condenser water pumps to provide variable flow control of the water through the chillers, resulting in reduced motor electricity usage. Potential electricity savings were simulated. Proposed savings were estimated at 600 kW (13.6%) daily, with an expected saving of R 2 275 000 yearly, resulting in a payback period of less than 9 months. Results indicated are based on total savings, as VSD savings and control savings were combined. The VSDs that were installed, were controlled according to an optimum simulation model’s philosophy. A real-time energy management program was used to control the VSDs and monitor the respective systems. The program’s remote capabilities allow for off-site monitoring and control adjustments. A control strategy, which was implemented using the management program, is discussed. Energy efficiency was achieved through the respective installations and control improvements. The results were analysed over an assessment period of three months to determine the viability of the intervention. A newly installed Bulk Air Cooler (BAC) added to the service delivery of the cooling plant post installation of the VSDs. Focusing on service delivery to underground showed a savings of 1.7 MW (33.6%) daily and a payback period of 3.6 months (0.3 years). The overall implementation showed an average energy saving of 2.3 MW (47.1%) daily, with the result that a daily saving of R 23 988.20 was experienced, reducing the payback period to 2.3 months (0.2 years). Through the installation of energy-efficiency technology and a suitable control philosophy, a cost-effective, energy-efficiency improvement was created on the case-study cooling plant. / MIng (Mechanical Engineering), North-West University, Potchefstroom Campus, 2014

Student Number : 0400486V - MSc (Eng) dissertation - School of Electrical and Information Engineering - Faculty of Engineering and the Built Environment / The Voltage Dip Test Facility at the University of the Witwatersrand utilises a resistive load during testing of variable speed drives. This method produces valuable results regarding the performance of drives under dip conditions. It has been shown that load type does influence the performance of drives and this variation cannot be tested under current conditions as only linear loading is attainable with resistive loads. This thesis proposes a programmable load based on the concept of field-oriented control of an induction motor. The concepts involved with field-oriented control are discussed and shown to be suitable for this application. An implementation strategy utilising custom-designed software and an off-the-shelf VSD is developed and executed. The performance of the programmable load is analysed under both steady-state and dynamic conditions.

No description available.

A presente dissertação aborda a avaliação de três sistemas fotovoltaicos de bombeamento, que compreendem duas configurações com equipamentos dedicados à tecnologia fotovoltaica e um com equipamentos alternativos com potências entre 0,75 CV e 1,0 CV. Os resultados mostram que a configuração alternativa apresenta menor eficiência diária do sistema motobomba. A avaliação econômica revela a competitividade da configuração alternativa frente aos sistemas importados dedicados à tecnologia fotovoltaica. Alia-se a isso a disponibilidade dos equipamentos de condicionamento de potência e a facilidade de reposição. Verificou-se também que a configuração alternativa, conversor de freqüência WEG CFW08 e motobomba SOMAR de 1,0 CV e 8 estágios, trabalha com eficiência diária próxima aos 30% na faixa de operação de 20 a 40 metros de coluna dágua. Portanto, com uma adequada escolha da motobomba para a configuração alternativa, podem-se obter desempenhos semelhantes aos obtidos com sistemas importados dedicados à tecnologia fotovoltaica. Para 30 metros, a configuração alternativa bombeou somente 1% a menos do que o sistema Grundfos. O custo do volume bombeado para 30m de altura manométrica total do sistema alternativo é 22% menor do que o sistema Grundfos e 51% mais econômico do que o sistema Solarjack (Sun Pumps). / The present dissertation shows the evaluation of three Photovoltaic Pumping Systems, which involves two configurations: the equipment dedicated to the photovoltaic technology and the alternative equipment with nominal powers between 0.75 CV and 1.0 CV. The results show that the alternative configuration attained minor daily efficiency of the motopump system. The economic evaluation reveals the competitiveness of the alternative configuration in comparison with imported photovoltaic technology dedicated systems. It also should be considered the availability of equipment for power conditioning and the facility of replacement. It was also verified that the alternative configuration, variable speed drive WEG CFW08 and 1.0 CV SOMAR motor pump with 8 stages, works with daily efficiency near 30% in the 20 to 40 meters operation range. Therefore, with an adequate choice of the motor pump for the alternative configuration, performances similar to the imported photovoltaic technology dedicated systems can be obtained. For 30 meters, the alternative configuration pumped only 1% less than the Grundfos system. The cost of pumped volume for 30 meters of manometer total height of the alternative system is 22% cheaper than the system Grundfos and 51% cheaper than the system Solarjack (Sun Pumps).

O trabalho dedica atenção à otimização do acoplamento de geradores fotovoltaicos a motores de corrente alternada através de conversores de frequência comerciais, para acionar bombas centrífugas para fins de bombeamento de água. Procedimentos para otimização deste novo tipo de configuração são propostos. As ações de otimização são avaliadas através de ensaios experimentais realizados em uma bancada desenvolvida para este propósito. A bancada desenvolvida permite simular poços de até 100 m de profundidade. Resultados da operação de um protótipo instalado em campo são apresentados. Os resultados da pesquisa comprovam que este novo tipo de configuração é confiável e economicamente viável, podendo ser adotada como uma solução universal para sistemas de bombeamento de água que utilizam motobombas com potência igual ou superior a 1/2 CV. / This work is concerned with in the optimization of photovoltaic pumping systems that make use of a variable-speed drive and conventional induction motor with centrifugal pumps. Procedures for optimization of this new kind of configuration are proposed. The optimization actions are evaluated through experimental measurements accomplished in a test facility developed for this purpose. The developed test facility allows the simulation of wells with total head up to 100 m. Operation results of a prototype installed in the field are shown. The research results prove that this new kind of configuration is reliable and economically feasible, and could be adopted as a universal solution for water pumping systems with motors of 1/2 HP (metric) or higher.

A presente dissertação aborda a avaliação de três sistemas fotovoltaicos de bombeamento, que compreendem duas configurações com equipamentos dedicados à tecnologia fotovoltaica e um com equipamentos alternativos com potências entre 0,75 CV e 1,0 CV. Os resultados mostram que a configuração alternativa apresenta menor eficiência diária do sistema motobomba. A avaliação econômica revela a competitividade da configuração alternativa frente aos sistemas importados dedicados à tecnologia fotovoltaica. Alia-se a isso a disponibilidade dos equipamentos de condicionamento de potência e a facilidade de reposição. Verificou-se também que a configuração alternativa, conversor de freqüência WEG CFW08 e motobomba SOMAR de 1,0 CV e 8 estágios, trabalha com eficiência diária próxima aos 30% na faixa de operação de 20 a 40 metros de coluna dágua. Portanto, com uma adequada escolha da motobomba para a configuração alternativa, podem-se obter desempenhos semelhantes aos obtidos com sistemas importados dedicados à tecnologia fotovoltaica. Para 30 metros, a configuração alternativa bombeou somente 1% a menos do que o sistema Grundfos. O custo do volume bombeado para 30m de altura manométrica total do sistema alternativo é 22% menor do que o sistema Grundfos e 51% mais econômico do que o sistema Solarjack (Sun Pumps). / The present dissertation shows the evaluation of three Photovoltaic Pumping Systems, which involves two configurations: the equipment dedicated to the photovoltaic technology and the alternative equipment with nominal powers between 0.75 CV and 1.0 CV. The results show that the alternative configuration attained minor daily efficiency of the motopump system. The economic evaluation reveals the competitiveness of the alternative configuration in comparison with imported photovoltaic technology dedicated systems. It also should be considered the availability of equipment for power conditioning and the facility of replacement. It was also verified that the alternative configuration, variable speed drive WEG CFW08 and 1.0 CV SOMAR motor pump with 8 stages, works with daily efficiency near 30% in the 20 to 40 meters operation range. Therefore, with an adequate choice of the motor pump for the alternative configuration, performances similar to the imported photovoltaic technology dedicated systems can be obtained. For 30 meters, the alternative configuration pumped only 1% less than the Grundfos system. The cost of pumped volume for 30 meters of manometer total height of the alternative system is 22% cheaper than the system Grundfos and 51% cheaper than the system Solarjack (Sun Pumps).

O trabalho dedica atenção à otimização do acoplamento de geradores fotovoltaicos a motores de corrente alternada através de conversores de frequência comerciais, para acionar bombas centrífugas para fins de bombeamento de água. Procedimentos para otimização deste novo tipo de configuração são propostos. As ações de otimização são avaliadas através de ensaios experimentais realizados em uma bancada desenvolvida para este propósito. A bancada desenvolvida permite simular poços de até 100 m de profundidade. Resultados da operação de um protótipo instalado em campo são apresentados. Os resultados da pesquisa comprovam que este novo tipo de configuração é confiável e economicamente viável, podendo ser adotada como uma solução universal para sistemas de bombeamento de água que utilizam motobombas com potência igual ou superior a 1/2 CV. / This work is concerned with in the optimization of photovoltaic pumping systems that make use of a variable-speed drive and conventional induction motor with centrifugal pumps. Procedures for optimization of this new kind of configuration are proposed. The optimization actions are evaluated through experimental measurements accomplished in a test facility developed for this purpose. The developed test facility allows the simulation of wells with total head up to 100 m. Operation results of a prototype installed in the field are shown. The research results prove that this new kind of configuration is reliable and economically feasible, and could be adopted as a universal solution for water pumping systems with motors of 1/2 HP (metric) or higher.

No description available.