LQR CONTROL APPROACH APPLIED TO UNINTERRUPTIBLE POWER SUPPLY (UPS)

This paper presents a control strategy applied to high power uninterruptible power supplies with a low switching frequency. In the controller design, the gains are determined by minimizing a cost function, which reduces the tracking error and smoothes the control signal. A recursive least square estimator identifies the parameters model at different load conditions. Then the linear quadratic controller gains are adapted periodically. The output voltage is the only state variable measured.The other state variables are obtained by estimation process. Simulation results show that the proposed control strategy offers good performances for either linear and non-linear loads with low total harmonic distortions (THD) even at low frequencies making it very useful for high power applications. 

Self tunning filter for three levels four legs shunt active power filter with fuzzy logic controller

The low harmonic distortion and reduced switching losses are the advantages of using the multilevel inverter. For this purpose, the three-level inverter is used in this paper as a three-phase four-leg shunt active power filter (SAPF). The SAPF is used to eliminate the harmonic current to compensate the reactive power current, and to balance the load currents under an unbalanced non-linear load. A fuzzy logic controller and self-tuning filters (STF) are used to control the active power filter (APF) and generate the reference current. To demonstrate the validity of the proposed control strategy, we compared it with a conventional p − q theory, under distortion voltage conditions and unbalanced non-linear load. The Matlab-Simulink toolbox is used to implement the algorithm of Fuzzy logic control. The performance of the SAPF controller is found very effective and adequate as compared with the p − q theory

LQR CONTROL APPROACH APPLIED TO UNINTERRUPTIBLE POWER SUPPLY (UPS)

This paper presents a control strategy applied to high power uninterruptible power supplies with a low switching frequency. In the controller design, the gains are determined by minimizing a cost function, which reduces the tracking error and smoothes the control signal. A recursive least square estimator identifies the parameters model at different load conditions. Then the linear quadratic controller gains are adapted periodically. The output voltage is the only state variable measured.The other state variables are obtained by estimation process. Simulation results show that the proposed control strategy offers good performances for either linear and non-linear loads with low total harmonic distortions (THD) even at low frequencies making it very useful for high power applications

Real-Time Implementation of High Performance Control Scheme for Grid-Tied PV System for Power Quality Enhancement Based on MPPC-SVM Optimized by PSO Algorithm

This paper proposes a high performance control scheme for a double function grid-tied double-stage PV system. It is based on model predictive power control with space vector modulation. This strategy uses a discrete model of the system based on the time domain to generate the average voltage vector at each sampling period, with the aim of canceling the errors between the estimated active and reactive power values and their references. Also, it imposes a sinusoidal waveform of the current at the grid side, which allows active power filtering without a harmonic currents identification phase. The latter attempts to reduce the size and cost of the system as well as providing better performance. In addition, it can be implemented in a low-cost control platform due to its simplicity. A double-stage PV system is selected due to its flexibility in control, unlike single-stage strategies. Sliding mode control-based particle swarm optimization (PSO) is used to track the maximum power of the PV system. It offers high accuracy and good robustness. Concerning DC bus voltage of the inverter, the anti-windup PI controller is tuned offline using the particle swarm optimization algorithm to deliver optimal performance in DC bus voltage regulation. The overall system has been designed and validated in an experimental prototype; the obtained results in different phases demonstrate the higher performance and the better efficiency of the proposed system in terms of power quality enhancement and PV power injection

Optimized Modulation Scheme for Four-Leg Quasi Z-Source Inverter: Reducing Power Loss and Improving Output Quality

This study introduces a new three-dimensional space vector modulation technique for a four-leg quasi Z-source inverter (4L-qZSI) integrating a qZSN and a two-level four-leg inverter. The proposed method encompasses three variants, namely 3DZSVM2, 3DZSVM4, and 3DZSVM8, designed to enhance steady-state operations and harmonic distortions for 4L-qZSI. One of the main contributions of this research is the establishment of a new modulation technique for the 4L-qZSI. The proposed method amalgamates the benefits of SVMs in both abc and $\alpha \beta \gamma$ coordinates. The design processes of the 3DZSVM algorithm are carried out in the newly proposed $\rho \sigma \tau$ coordinates, while the space vector diagram (SVD) of the 4L-qZSI is utilized in the $\alpha \beta \gamma$ location. The proposed algorithm is applied in a single sector, optimizing time interval calculations and pulse creation without requiring trigonometric functions. Extensive simulation studies were conducted to validate the performance of the introduced modulation scheme for the 4L-qZSI. The simulation results show excellent steady-state performance and benefit over the conventional space vector modulation with zero sequences (CZPWM), including a power loss reduction of 50% and a 50% decrease in the THD of the output voltage. In addition, applying this technique results in enhanced output current quality, reduced power loss by 40%, and decreased inductive current ripple by 50% under unbalanced load conditions. Furthermore, the proposed 3DZSVM control strategy for 4L-qZSI is experimentally verified using the TMS320F28379D kit based on the Hardware-in-the-Loop (HIL) simulator. This demonstrates the practicality and effective performance of the suggested control strategy under unbalanced load conditions

Управление током Z-инвертора с четвертой стойкой для автономной фотоэлектрической системы на основе прогнозирующего управления

Возобновляемые источники для производства электроэнергии вызывают больший интерес у ученых и исследователей по сравнению с традиционными источниками, работающими на основе использования углеводородного топлива. Одним из типов возобновляемых источников энергии, отвечающих реализации концепции «зеленая энергетика», являются фотоэлектрические системы, способные эффективно использоваться в качестве автономной системы электроснабжения для потребителей, географически расположенных в отдаленных, труднодоступных районах. Производительность автономной системы электроснабжения во многом определяется системой преобразования и ее алгоритмами управления. В статье рассмотрена новая и альтернативная система управления автономных фотоэлектрических станций, основанная на стратегии прогнозирующего управления напряжением и током нагрузки Z-инвертора с четвертой стойкой. Цель: разработка алгоритма, основанного на стратегии прогнозирующего управления, для регулирования токов нагрузки автономной фотоэлектрической системы электроснабжения. Методы: математическое и компьютерное моделирование с использованием программной среды MatLab/Simulink. Результаты. Благодаря использованию Z-инвертора система преобразования энергии для фотоэлектрических систем генерации сокращается до одноступенчатой структуры. Результаты показывают, что предложенный алгоритм управления может эффективно регулировать ток нагрузки при сбалансированных и несбалансированных нагрузках с высокой эффективностью управления. Предлагаемый алгоритм управления имеет отличные характеристики в установившихся и переходных режимах.The relevance. Renewable energy resources for electrical power generation have gained higher interest over the traditional underground fuels due to geo-reasons, such as the low generation cost and clean energy resources. Moreover, renewable energy resources, especially photovoltaic generation system, can efficiently be used as an autonomous power supply for consumers geographically located in remote, inaccessible areas. The performance of autonomous power supply depends mainly on the conversion system and its control technique. Therefore, this paper uses a new and alternative control system based on the finite control set model predictive control strategy to control the load current of the Z-source four-leg inverter employed for the autonomous photovoltaic generation system. The main aim of the research is the development of a control algorithm based on finite control set model predictive control strategy to regulate the load currents of Z-source four-leg inverter for a geographical stand-alone photovoltaic generation system. Methods: mathematical and computer modeling using the MatLab/Simulink software environment. Results. Due to using Z-source four-leg inverter, the power conversion system for the photovoltaic generation systems is reduced to be single-stage, instead of two-stage power conversion. The results show that the proposed control algorithm can effectively regulate load current under balanced/unbalanced issues with high controllability. The proposed control algorithm has excellent steady-state and transient performances

Управление током Z-инвертора с четвертой стойкой для автономной фотоэлектрической системы на основе прогнозирующего управления

Возобновляемые источники для производства электроэнергии вызывают больший интерес у ученых и исследователей по сравнению с традиционными источниками, работающими на основе использования углеводородного топлива. Одним из типов возобновляемых источников энергии, отвечающих реализации концепции «зеленая энергетика», являются фотоэлектрические системы, способные эффективно использоваться в качестве автономной системы электроснабжения для потребителей, географически расположенных в отдаленных, труднодоступных районах. Производительность автономной системы электроснабжения во многом определяется системой преобразования и ее алгоритмами управления. В статье рассмотрена новая и альтернативная система управления автономных фотоэлектрических станций, основанная на стратегии прогнозирующего управления напряжением и током нагрузки Z-инвертора с четвертой стойкой. Цель: разработка алгоритма, основанного на стратегии прогнозирующего управления, для регулирования токов нагрузки автономной фотоэлектрической системы электроснабжения. Методы: математическое и компьютерное моделирование с использованием программной среды MatLab/Simulink. Результаты. Благодаря использованию Z-инвертора система преобразования энергии для фотоэлектрических систем генерации сокращается до одноступенчатой структуры. Результаты показывают, что предложенный алгоритм управления может эффективно регулировать ток нагрузки при сбалансированных и несбалансированных нагрузках с высокой эффективностью управления. Предлагаемый алгоритм управления имеет отличные характеристики в установившихся и переходных режимах.The relevance. Renewable energy resources for electrical power generation have gained higher interest over the traditional underground fuels due to geo-reasons, such as the low generation cost and clean energy resources. Moreover, renewable energy resources, especially photovoltaic generation system, can efficiently be used as an autonomous power supply for consumers geographically located in remote, inaccessible areas. The performance of autonomous power supply depends mainly on the conversion system and its control technique. Therefore, this paper uses a new and alternative control system based on the finite control set model predictive control strategy to control the load current of the Z-source four-leg inverter employed for the autonomous photovoltaic generation system. The main aim of the research is the development of a control algorithm based on finite control set model predictive control strategy to regulate the load currents of Z-source four-leg inverter for a geographical stand-alone photovoltaic generation system. Methods: mathematical and computer modeling using the MatLab/Simulink software environment. Results. Due to using Z-source four-leg inverter, the power conversion system for the photovoltaic generation systems is reduced to be single-stage, instead of two-stage power conversion. The results show that the proposed control algorithm can effectively regulate load current under balanced/unbalanced issues with high controllability. The proposed control algorithm has excellent steady-state and transient performances