Orientador: Dionizio Paschoareli Junior / Banca: Falcondes Jose Mendes de Seixas / Banca: Hari Bruno Mohr / Resumo: A tendência dos sistemas de energia elétrica é uma operação cada vez mais próxima de seus limites operacionais. A presença de equipamentos que utilizam a eletrônica de potência, no controle e condicionamento da energia, é cada vez mais freqüente. A utilização de conversores como fonte de tensão, associados a elementos armazenadores de energia como, por exemplo, a bateria de sódio-enxofre, com alta densidade de energia, alta eficiência na carga e descarga e ainda um longo ciclo de vida, é a configuração básica de um Compensador Regenerativo de Potência Ativa. Compensação regenerativa de potência é um conceito que permite o armazenamento de energia em períodos favoráveis sob o ponto de vista dos custos da energia elétrica. Este conceito de compensação baseia-se no armazenamento da energia excedente ao longo do dia, nos períodos de menor tarifação, para utilizá-la nos horários de ponta (sobre-tarifa), aproveitando-se as vantagens contratuais de consumo de energia fora de ponta e promovendo-se uma melhor equalização de consumo, permitindo uma redução no contrato de demanda. Portanto, na compensação regenerativa de potência ativa, os períodos de consumo de energia são deslocados, com o objetivo de se obter redução na tarifa. Este conceito mostra-se interessante em sistemas com tarifação do tipo horo-sazonal, como é o caso brasileiro. Com o objetivo de se verificar tal troca de potência ativa, um modelo trifásico foi implementado e simulado. Os controles da potência ativa trocada entre o compensador e o sistema e da tensão na barra na qual o mesmo está instalado são realizados independentes e por controladores do tipo PID. Os sinais de controle dos interruptores semicondutores que compõe o conversor como fonte de tensão são gerados a partir do DSP TMS320F2808 da Texas Instruments, o que está embarcado no módulo didático eZdsp F2808 da Spectrum Digital / Abstract: Nowadays, electric power systems are expected to work closer to their operating limits. Power electronics based controllers, such as voltage sourced converters, are increasingly present in power systems. Electronic devices are often used to energy controlling and conditioning. The use of voltage sourced converters, associated to high-density storage elements, is the basic configuration of a Regenerative Active Power Compensator. Regenerative Active Power Compensator is a concept which proposes the energy storage as a possibility for revaluation of electrical energy cost with demand contracts. This concept is based on storing energy surplus during off peak periods, when the energy cost is cheaper, and injecting it back to the system during the overpriced peak periods. This procedure allows a better equalization of energy consumption and a reduction in electric power demand contracts. Therefore, using regenerative active power compensation, the consumption is dislocated from peak periods, resulting in a reduction of energy costs for the consumer. This concept is especially attractive for countries that use hour-seasonal fees police, as in the Brazilian case. This work proposes a three-phase model simulation with digital signal processor controller to investigate the active power flow control between the power system and the compensator, using a proportional-integral-derivative control strategy. The control signals are generate using the Texas Instruments DSP TMS320F2808, witch is embedded into the eZdsp F2808 didactic module, from Spectrum Digital / Mestre

Made available in DSpace on 2014-06-11T19:22:32Z (GMT). No. of bitstreams: 0 Previous issue date: 2009-05-28Bitstream added on 2014-06-13T20:09:45Z : No. of bitstreams: 1 nascimento_bm_me_ilha.pdf: 1604913 bytes, checksum: f565cd826c9093459f7a60aa26c658fb (MD5) / Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq) / A tendência dos sistemas de energia elétrica é uma operação cada vez mais próxima de seus limites operacionais. A presença de equipamentos que utilizam a eletrônica de potência, no controle e condicionamento da energia, é cada vez mais freqüente. A utilização de conversores como fonte de tensão, associados a elementos armazenadores de energia como, por exemplo, a bateria de sódio-enxofre, com alta densidade de energia, alta eficiência na carga e descarga e ainda um longo ciclo de vida, é a configuração básica de um Compensador Regenerativo de Potência Ativa. Compensação regenerativa de potência é um conceito que permite o armazenamento de energia em períodos favoráveis sob o ponto de vista dos custos da energia elétrica. Este conceito de compensação baseia-se no armazenamento da energia excedente ao longo do dia, nos períodos de menor tarifação, para utilizá-la nos horários de ponta (sobre-tarifa), aproveitando-se as vantagens contratuais de consumo de energia fora de ponta e promovendo-se uma melhor equalização de consumo, permitindo uma redução no contrato de demanda. Portanto, na compensação regenerativa de potência ativa, os períodos de consumo de energia são deslocados, com o objetivo de se obter redução na tarifa. Este conceito mostra-se interessante em sistemas com tarifação do tipo horo-sazonal, como é o caso brasileiro. Com o objetivo de se verificar tal troca de potência ativa, um modelo trifásico foi implementado e simulado. Os controles da potência ativa trocada entre o compensador e o sistema e da tensão na barra na qual o mesmo está instalado são realizados independentes e por controladores do tipo PID. Os sinais de controle dos interruptores semicondutores que compõe o conversor como fonte de tensão são gerados a partir do DSP TMS320F2808 da Texas Instruments, o que está embarcado no módulo didático eZdsp F2808 da Spectrum Digital / Nowadays, electric power systems are expected to work closer to their operating limits. Power electronics based controllers, such as voltage sourced converters, are increasingly present in power systems. Electronic devices are often used to energy controlling and conditioning. The use of voltage sourced converters, associated to high-density storage elements, is the basic configuration of a Regenerative Active Power Compensator. Regenerative Active Power Compensator is a concept which proposes the energy storage as a possibility for revaluation of electrical energy cost with demand contracts. This concept is based on storing energy surplus during off peak periods, when the energy cost is cheaper, and injecting it back to the system during the overpriced peak periods. This procedure allows a better equalization of energy consumption and a reduction in electric power demand contracts. Therefore, using regenerative active power compensation, the consumption is dislocated from peak periods, resulting in a reduction of energy costs for the consumer. This concept is especially attractive for countries that use hour-seasonal fees police, as in the Brazilian case. This work proposes a three-phase model simulation with digital signal processor controller to investigate the active power flow control between the power system and the compensator, using a proportional-integral-derivative control strategy. The control signals are generate using the Texas Instruments DSP TMS320F2808, witch is embedded into the eZdsp F2808 didactic module, from Spectrum Digital

<p>This project deals with voltage source converters with energy storage capability. The main objective is to study the possible benefits of energy storage to a power system with a VSC as the interface between them.</p><p>First of all, a converter control system is proposed for a two level VSC. In the conventional converter control, the control system usually takes the voltage measured at the point where the converter is connected and calculates the reference voltage for the converter; with a modulation system the converter then produces the required 'average voltage'. In this project, a novel flux modulation scheme, combined with the deadbeat current control strategy, is proposed. The current controller is capable of controlling both positive and negative sequence current components. With flux modulation, the control system measures the bus flux and commands the converter to generate the required flux.</p><p>Based on the proposed control strategies, several application studies have been carried out.</p><p>The first application study investigates the effect of energy storage on the power quality at the point of common coupling when a system is subject to load disturbances. The voltage at PCC in a weak network is very sensitive to load changes. A sudden change in active load will cause both a phase jump and a magnitude fluctuation in the bus voltage, whereas reactive load changes mainly affect the voltage magnitude. With the addition of energy storage to a StatCom, it is possible to compensate for the active power change as well as providing reactive power support. In this thesis, some effective active power compensation schemes are proposed. Simulations and experiments have been performed to verify the compensation schemes. The results show that a StatCom with energy storage can significantly reduce phase jumps and magnitude deviations of the bus voltage.</p><p>pact of the energy storage on the performance of weak systems under fault conditions has been investigated. The investigation was done by studying an example system. The system model was established based on a real system, in which some induction motors driving pumps along a pipeline are fed from a radial transmission line. Studies show that for a weak system with induction motor loads, a StatCom with certain energy storage capacity will effectively improve the system recovery after faults. Although this incurs extra cost for the increasing dc voltage rating and size of the dc side capacitor, the overall rating of the converter can be reduced by utilization of the proposed active power compensation scheme.</p><p>The last case study investigates the possible use of a StatCom with energy storage to improve the power quality at the point of common coupling where a cyclic load is connected. Studies show that by providing both fast reactive and fast active power support to the network, not only the voltage magnitude can be well controlled, but also the voltage phase jump can be reduced significantly.</p>

Static synchronous compensation (StatCom) is an application that utilizes a voltage source converter (VSC) to provide instantaneous reactive power support to the connected power system. Conventionally, StatComs are employed for reactive power support only. However, with the integration of energy storage (ES) into a StatCom, it can provide active power support in addition to the reactive power support. This thesis deals with the integration of ES into StatComs. The investigation involves the following aspects: possible benefits for power systems, main circuit design, and control strategies. As the basis of the investigation, a control scheme is proposed for two-level VSCs. It is a novel flux modulation scheme combined with the well-known deadbeat current control. The current controller is capable of controlling the positive sequence, the negative sequence, and the offset components of the converter current. With flux modulation, all the three above-mentioned components of the bus flux are controllable. This differs from the conventional voltage modulation scheme, in which only the positive and negative sequence components of the bus voltage are controllable. The difference between the proposed flux modulation scheme and the voltage modulation scheme is investigated regarding saturation of transformers in the connected system during fault recovery. The investigation shows that by controlling the offset component of the bus flux, the transformer saturation problem can be mitigated to a certain extent. The possible benefits of the additional active power support of StatComs are investigated through several case studies. Different active power compensation schemes are proposed. First, active power compensation for sudden load changes in weak systems is investigated. The proposed control strategies are verified through computer simulations and through experiments in a real-time simulator. It is shown that with active power compensation, both the phase jumps and magnitude variations in the voltage at the PCC can be reduced significantly. Secondly, the power compensation of cyclic loads is investigated. The results show that the power quality at the connection point can be improved regarding both phase jumps and magnitude variations. In the third case study, the fault-recovery performance of an example system is investigated, showing that improved performance can be achieved by the additional active power support. ES devices such as capacitors, supercapacitors, and batteries exhibit considerable variation in the terminal voltage during a charging/discharging cycle. A direct connection of ES devices to the dc side of a VSC requires a higher voltage rating of the VSC. Thus, the cost of the VSC has to be increased. In this thesis, a dual thyristor converter topology is proposed to interface ES devices with the dc side of the VSC. First, a cost comparison is performed to compare the total cost of the whole system with and without the proposed interface topology. A cost comparison between various types of ES is also presented, providing a guideline for the choice of ES at energy levels where several alternatives exist. Then, the dynamics of systems with the proposed interface topology are investigated. Control strategies are proposed and verified by computer simulations. Two different control methods for the dual-thyristor converter are compared. / QC 20100819

This project deals with voltage source converters with energy storage capability. The main objective is to study the possible benefits of energy storage to a power system with a VSC as the interface between them. First of all, a converter control system is proposed for a two level VSC. In the conventional converter control, the control system usually takes the voltage measured at the point where the converter is connected and calculates the reference voltage for the converter; with a modulation system the converter then produces the required 'average voltage'. In this project, a novel flux modulation scheme, combined with the deadbeat current control strategy, is proposed. The current controller is capable of controlling both positive and negative sequence current components. With flux modulation, the control system measures the bus flux and commands the converter to generate the required flux. Based on the proposed control strategies, several application studies have been carried out. The first application study investigates the effect of energy storage on the power quality at the point of common coupling when a system is subject to load disturbances. The voltage at PCC in a weak network is very sensitive to load changes. A sudden change in active load will cause both a phase jump and a magnitude fluctuation in the bus voltage, whereas reactive load changes mainly affect the voltage magnitude. With the addition of energy storage to a StatCom, it is possible to compensate for the active power change as well as providing reactive power support. In this thesis, some effective active power compensation schemes are proposed. Simulations and experiments have been performed to verify the compensation schemes. The results show that a StatCom with energy storage can significantly reduce phase jumps and magnitude deviations of the bus voltage. pact of the energy storage on the performance of weak systems under fault conditions has been investigated. The investigation was done by studying an example system. The system model was established based on a real system, in which some induction motors driving pumps along a pipeline are fed from a radial transmission line. Studies show that for a weak system with induction motor loads, a StatCom with certain energy storage capacity will effectively improve the system recovery after faults. Although this incurs extra cost for the increasing dc voltage rating and size of the dc side capacitor, the overall rating of the converter can be reduced by utilization of the proposed active power compensation scheme. The last case study investigates the possible use of a StatCom with energy storage to improve the power quality at the point of common coupling where a cyclic load is connected. Studies show that by providing both fast reactive and fast active power support to the network, not only the voltage magnitude can be well controlled, but also the voltage phase jump can be reduced significantly. / QC 20101124

The electric power supply industry has evolved into one of the largest industries. Even though secure and reliable operation of the electric power system is fundamental to economy, social security and quality of modern life, the complicated power grid is now facing severe challenges to meet the high-level secure and reliable operation requirements. New technologies will play a major role in helping today's electric power industry to meet the above challenges. This dissertation has focused on some key technologies among them, including the emerging technologies of energy storage, controlled power electronics and wide area measurement technologies. Those technologies offer an opportunity to develop the appropriate objectives for power system control. The use of power electronics based devices with energy storage system integrated into them, such as FACTS/ESS, can provide valuable added benefits to improve stability, power quality, and reliability of power systems. The study in this dissertation has provided several guidelines for the implementation of FACTS/ESS in bulk power systems. The interest of this study lies in a wide range of FACTS/ESS technology applications in bulk power system to solve some special problems that were not solved well without the application of FACTS/ESS. The special problems we select to solve by using FACTS/ESS technology in this study include power quality problem solution by active power compensation, electrical arc furnace (EAF) induced problems solution, inter-area mode low frequency oscillation suppression, coordination of under frequency load shedding (UFLS) and under frequency governor control (UFGC), wide area voltage control. From this study, the author of this dissertation reveals the unique role that FACTS/ESS technology can play in the bulk power system stability control and power quality enhancement in power system. In this dissertation, almost all the studies are based on the real system problems, which means that the study results are special valuable to certain utilities that have those problems. The study in this dissertation can assist power industry choose the right FACTS/ESS technology for their intended functions, which will improve the survivability, minimize blackouts, and reduce interruption costs through the use of energy storage systems. / Ph. D.