Finite control set model predictive control for a three-phase shunt active power filter with a kalman filter-based estimation

In this paper, the finite control set model predictive control is combined with the vector operation technique to be applied in the control of a three-phase active power filter. Typically, in the finite control set technique applied to three-phase power converters, eight different vectors are considered in order to obtain the optimum control signal by minimizing a cost function. On the other hand, the vector operation technique is based on dividing the grid voltage period into six different regions. The main advantage of combining both techniques is that for each region the number of possible voltage vectors to be considered can be reduced to a half, thus reducing the computational load employed by the control algorithm. Besides, in each region, only two phase-legs are switching at high frequency while the remaining phase-leg is maintained to a constant dc-voltage value during this interval. Accordingly, a reduction of the switching losses is obtained. Unlike the typical model predictive control methods which make use of the discrete differential equations of the converter, this method considers a Kalman filter in order to improve the behavior of the closed-loop system in noisy environments. Selected experimental results are exposed in order the demonstrate the validity of the control proposalPostprint (published version

Sliding-Mode Observer Based Voltage-Sensorless Model Predictive Power Control of PWM Rectifier under Unbalanced Grid Conditions

© 1982-2012 IEEE. A sliding-mode grid voltage observer (SMGVO) is proposed and experimentally verified in this paper for voltage-sensorless operation under an unbalanced network. The fundamental positive sequence component (FPSC) and fundamental negative sequence component (FNSC) are inherently separated in the observer without employing any additional filters. Due to embedded filtering effect, high frequency chattering and harmonic ripples can be well suppressed. Additionally, dc components can be completely rejected. As a result, dc offset would not cause fundamental frequency oscillations in magnitude and frequency of the estimated FPSC and FNSC. Owing to the predictive ability of SMGVO, one-step delay can be directly compensated using state variables in the observer. By combining estimation and prediction into one stage, the designed SMGVO turns out to be a compact solution for finite-control-set model predictive power control without voltage sensors. Theoretical proof is derived to verify that FPSC and FNSC can be accurately estimated and separated. Experimental results obtained from a two-level PWM rectifier confirm the effectiveness of the whole control system

Grid Voltages Estimation for Three-Phase PWM Rectifiers Control Without AC Voltage Sensors

This paper proposes a new ac voltage sensorless control scheme for the three-phase pulse-width modulation rectifier. A new startup process to ensure a smooth starting of the system is also proposed. The sensorless control scheme uses an adaptive neural (AN) estimator inserted in voltage-oriented control to eliminate the grid voltage sensors. The developed AN estimator combines an AN network in series with an AN filter. The AN estimator structure leads to simple, accurate, and fast grid voltages estimation, and makes it ideal for low-cost digital signal processor implementation. Lyapunov-based stability and parameters tuning of the AN estimator are performed. Simulation and experimental tests are carried out to verify the feasibility and effectiveness of the AN estimator. Obtained results show that the proposed AN estimator presented faster convergence and better accuracy than the second-order generalized integrator-based estimator; the new startup procedure avoided the overcurrent and reduced the settling time; and the AN estimator presented high performances even under distorted and unbalanced grid voltages

Variable structure control for three-phase LCL-filtered inverters using a reduced converter model

This paper presents a new concept in active damping techniques using a reduced model of a LCL-filtered grid connected inverter. The presence of the LCL filter complicates the design of the inverter control scheme, particularly when uncertainties in the system parameters, especially in the grid inductance, are considered. The proposed control algorithm is addressed to overcome such difficulties using a reduced model of the inverter in a state observer. In this proposal, two of the three state variables of the system are obviated from the physical inverter model and only the inverter side current is considered. Therefore, the inverter side current can be estimated emulating the case of an inverter with only one inductor, thus eliminating the resonance problem produced by the LCL filter. Besides, in the case of a distorted grid, the method allows to estimate the voltages at the point of common coupling free of noise and distortion without using any PLL-based synchronization. To complete the control scheme, a theoretical stability analysis is developed considering the effect of the observer, the system discretization and the system parameters deviation. Experimental and comparative evaluation results are presented to validate the effectiveness of the proposed control schemePostprint (published version

Neural Networks based Shunt Hybrid Active Power Filter for Harmonic Elimination

The growing use of nonlinear devices is introducing harmonics in the power system networks that results in distortion of current and voltage signals causing damage to the power distribution system. Therefore, in power systems, the elimination of harmonics is of great concern. This paper presents an efficient techno-economical approach to suppress harmonics and improve the power factor in the power distribution network using neural network algorithms-based Shunt Hybrid Active Power Filter (SHAPF), such as Artificial Neural Network (ANN), Adaptive Neuro-Fuzzy Inference System (ANFIS), and Recurrent Neural Network (RNN). The objective of the proposed algorithms for SHAPF is to reduce Total Harmonic Distortion (THD) within an acceptable range to improve system quality. In our filter design approach, we tested and compared conventional pq0 theory and neural networks to detect the harmonics present in the power system. Moreover, for the regulation of the DC supply to the inverter of the SHAPF, the conventional PI controller and neural networks-based controllers are used and compared. The applicability of the proposed filter is tested for three different nonlinear load cases. The simulation results show that the neural networks-based filter control techniques satisfy all international standards with minimum current THD, neutral wire current elimination, and small DC voltage fluctuations for voltage regulation current. Furthermore, all three neural network architectures are tested and compared based on accuracy and computational complexity, with RNN outperforming the rest

One-Cycle Zero-Integral-Error Current Control for Shunt Active Power Filters

[EN] Current control has, for decades, been one of the more challenging research fields in the development of power converters. Simple and robust nonlinear methods like hysteresis or sigma-delta controllers have been commonly used, while sophisticated linear controllers based on classical control theory have been developed for PWM-based converters. The one-cycle current control technique is a nonlinear technique based on cycle-by-cycle calculation of the ON time of the converter switches for the next switching period. This kind of controller requires accurate measurement of voltages and currents in order achieve a precise current tracking. These techniques have been frequently used in the control of power converters generating low-frequency currents, where the reference varies slowly compared with the switching frequency. Its application is not so common in active power filter current controllers due to the fast variation of the references that demands not only accurate measurements but also high-speed computing. This paper proposes a novel one-cycle digital current controller based on the minimization of the integral error of the current. Its application in a three-leg four-wire shunt active power filter is presented, including a stability analysis considering the switching pattern selection. Furthermore, simulated and experimental results are presented to validate the proposed controller.Orts-Grau, S.; Balaguer-Herrero, P.; Alfonso-Gil, JC.; Martínez-Márquez, CI.; Gimeno Sales, FJ.; Segui-Chilet, S. (2020). One-Cycle Zero-Integral-Error Current Control for Shunt Active Power Filters. Electronics. 9(12):1-16. https://doi.org/10.3390/electronics9122008S116912Orts-Grau, S., Gimeno-Sales, F. J., Abellan-Garcia, A., Segui-Chilet, S., & Alfonso-Gil, J. C. (2010). Improved Shunt Active Power Compensator for IEEE Standard 1459 Compliance. IEEE Transactions on Power Delivery, 25(4), 2692-2701. doi:10.1109/tpwrd.2010.2049033Orts-Grau, S., Gimeno-Sales, F. J., Segui-Chilet, S., Abellan-Garcia, A., Alcaniz-Fillol, M., & Masot-Peris, R. (2009). Selective Compensation in Four-Wire Electric Systems Based on a New Equivalent Conductance Approach. IEEE Transactions on Industrial Electronics, 56(8), 2862-2874. doi:10.1109/tie.2009.2014368Trinh, Q.-N., & Lee, H.-H. (2013). An Advanced Current Control Strategy for Three-Phase Shunt Active Power Filters. IEEE Transactions on Industrial Electronics, 60(12), 5400-5410. doi:10.1109/tie.2012.2229677Bosch, S., Staiger, J., & Steinhart, H. (2018). Predictive Current Control for an Active Power Filter With LCL-Filter. IEEE Transactions on Industrial Electronics, 65(6), 4943-4952. doi:10.1109/tie.2017.2772176Balasubramanian, R., Parkavikathirvelu, K., Sankaran, R., & Amirtharajan, R. (2019). Design, Simulation and Hardware Implementation of Shunt Hybrid Compensator Using Synchronous Rotating Reference Frame (SRRF)-Based Control Technique. Electronics, 8(1), 42. doi:10.3390/electronics8010042Imam, A. A., Sreerama Kumar, R., & Al-Turki, Y. A. (2020). Modeling and Simulation of a PI Controlled Shunt Active Power Filter for Power Quality Enhancement Based on P-Q Theory. Electronics, 9(4), 637. doi:10.3390/electronics9040637Panigrahi, R., Subudhi, B., & Panda, P. C. (2016). A Robust LQG Servo Control Strategy of Shunt-Active Power Filter for Power Quality Enhancement. IEEE Transactions on Power Electronics, 31(4), 2860-2869. doi:10.1109/tpel.2015.2456155Herman, L., Papic, I., & Blazic, B. (2014). A Proportional-Resonant Current Controller for Selective Harmonic Compensation in a Hybrid Active Power Filter. IEEE Transactions on Power Delivery, 29(5), 2055-2065. doi:10.1109/tpwrd.2014.2344770Panigrahi, R., & Subudhi, B. (2017). Performance Enhancement of Shunt Active Power Filter Using a Kalman Filter-Based ${{{\rm H}}_\infty }$ Control Strategy. IEEE Transactions on Power Electronics, 32(4), 2622-2630. doi:10.1109/tpel.2016.2572142Jiang, W., Ding, X., Ni, Y., Wang, J., Wang, L., & Ma, W. (2018). An Improved Deadbeat Control for a Three-Phase Three-Line Active Power Filter With Current-Tracking Error Compensation. IEEE Transactions on Power Electronics, 33(3), 2061-2072. doi:10.1109/tpel.2017.2693325Buso, S., Caldognetto, T., & Brandao, D. (2015). Dead-Beat Current Controller for Voltage Source Converters with Improved Large Signal Response. IEEE Transactions on Industry Applications, 1-1. doi:10.1109/tia.2015.2488644Tarisciotti, L., Formentini, A., Gaeta, A., Degano, M., Zanchetta, P., Rabbeni, R., & Pucci, M. (2017). Model Predictive Control for Shunt Active Filters With Fixed Switching Frequency. IEEE Transactions on Industry Applications, 53(1), 296-304. doi:10.1109/tia.2016.2606364Kumar, M., & Gupta, R. (2017). Sampled-Time-Domain Analysis of a Digitally Implemented Current Controlled Inverter. IEEE Transactions on Industrial Electronics, 64(1), 217-227. doi:10.1109/tie.2016.2609840Ho, C. N.-M., Cheung, V. S. P., & Chung, H. S.-H. (2009). Constant-Frequency Hysteresis Current Control of Grid-Connected VSI Without Bandwidth Control. IEEE Transactions on Power Electronics, 24(11), 2484-2495. doi:10.1109/tpel.2009.2031804Wu, F., Feng, F., Luo, L., Duan, J., & Sun, L. (2015). Sampling period online adjusting-based hysteresis current control without band with constant switching frequency. IEEE Transactions on Industrial Electronics, 62(1), 270-277. doi:10.1109/tie.2014.2326992Holmes, D. G., Davoodnezhad, R., & McGrath, B. P. (2013). An Improved Three-Phase Variable-Band Hysteresis Current Regulator. IEEE Transactions on Power Electronics, 28(1), 441-450. doi:10.1109/tpel.2012.2199133Komurcugil, H., Bayhan, S., & Abu-Rub, H. (2017). Variable- and Fixed-Switching-Frequency-Based HCC Methods for Grid-Connected VSI With Active Damping and Zero Steady-State Error. IEEE Transactions on Industrial Electronics, 64(9), 7009-7018. doi:10.1109/tie.2017.2686331Chang, C.-H., Wu, F.-Y., & Chen, Y.-M. (2012). Modularized Bidirectional Grid-Connected Inverter With Constant-Frequency Asynchronous Sigma–Delta Modulation. IEEE Transactions on Industrial Electronics, 59(11), 4088-4100. doi:10.1109/tie.2011.2176693Mertens, A. (1994). Performance analysis of three-phase inverters controlled by synchronous delta-modulation systems. IEEE Transactions on Industry Applications, 30(4), 1016-1027. doi:10.1109/28.297919Morales, J., de Vicuna, L. G., Guzman, R., Castilla, M., & Miret, J. (2018). Modeling and Sliding Mode Control for Three-Phase Active Power Filters Using the Vector Operation Technique. IEEE Transactions on Industrial Electronics, 65(9), 6828-6838. doi:10.1109/tie.2018.2795528Guzman, R., de Vicuna, L. G., Morales, J., Castilla, M., & Miret, J. (2016). Model-Based Control for a Three-Phase Shunt Active Power Filter. IEEE Transactions on Industrial Electronics, 63(7), 3998-4007. doi:10.1109/tie.2016.2540580Pichan, M., & Rastegar, H. (2017). Sliding-Mode Control of Four-Leg Inverter With Fixed Switching Frequency for Uninterruptible Power Supply Applications. IEEE Transactions on Industrial Electronics, 64(8), 6805-6814. doi:10.1109/tie.2017.2686346E. S., S., E. K., P., Chatterjee, K., & Bandyopadhyay, S. (2014). An Active Harmonic Filter Based on One-Cycle Control. IEEE Transactions on Industrial Electronics, 61(8), 3799-3809. doi:10.1109/tie.2013.2286558Wang, L., Han, X., Ren, C., Yang, Y., & Wang, P. (2018). A Modified One-Cycle-Control-Based Active Power Filter for Harmonic Compensation. IEEE Transactions on Industrial Electronics, 65(1), 738-748. doi:10.1109/tie.2017.2682021Jin, T., & Smedley, K. M. (2006). Operation of One-Cycle Controlled Three-Phase Active Power Filter With Unbalanced Source and Load. IEEE Transactions on Power Electronics, 21(5), 1403-1412. doi:10.1109/tpel.2006.880264Hirve, S., Chatterjee, K., Fernandes, B. G., Imayavaramban, M., & Dwari, S. (2007). PLL-Less Active Power Filter Based on One-Cycle Control for Compensating Unbalanced Loads in Three-Phase Four-Wire System. IEEE Transactions on Power Delivery, 22(4), 2457-2465. doi:10.1109/tpwrd.2007.893450Qiao, C., Smedley, K. M., & Maddaleno, F. (2004). A Single-Phase Active Power Filter With One-Cycle Control Under Unipolar Operation. IEEE Transactions on Circuits and Systems I: Regular Papers, 51(8), 1623-1630. doi:10.1109/tcsi.2004.832801Qiao, C., Jin, T., & MaSmedley, K. (2004). One-Cycle Control of Three-Phase Active Power Filter With Vector Operation. IEEE Transactions on Industrial Electronics, 51(2), 455-463. doi:10.1109/tie.2004.82522

Estudio comparativo entre el control en el marco de referencia αβ y el control predictivo basado en el modelo dinámico del sistema para un filtro activo en paralelo

[CASTELLÀ] El uso de elementos electrónicos en las aplicaciones industriales está en constante crecimiento debido a las ventajas que éstos presentan en términos del control del comportamiento de sistemas. Dicho esto, el incremento de cargas no lineales ha sido inevitable, repercutiendo directamente en el aumento de las distorsiones de corriente y voltaje presentes en la redes de distribución, provocando pérdidas significativas, empeorando el factor de potencia, y, en últimas, reduciendo la calidad de la energía eléctrica. Con el ánimo de solventar este tipo de inconvenientes, se han implementado diversos métodos que compensen el impacto de las cargas no lineales pero se ha encontrado que su comportamiento puede llegar a acarrear problemas adicionales. Un ejemplo de esto son los arreglos de condensadores y los conocidos filtros pasivos. Sin embargo, la implementación de filtros activos, han tenido una gran acogida en losúltimos años debido a que sus características dinámicas permiten la adaptación a las necesidades del sistema a compensar. Es por esto que el desarrollo de controladores que permitan dominar el comportamiento de los filtros activos se ha convertido en una necesidad inherente al crecimiento industrial, y actualmente existen una gran diversidad de métodos que pueden ser implementados para ello. A lo largo de este Trabajo de Fin de Máster (TFM) se desarrollan las simulaciones de dos tipos de control para un sistema que cuenta con un filtro activo en paralelo (SAPF) a una carga no lineal: el Control en el marco de referencia y el Control Predictivo basado en el Modelo del sistema (MPC). Estos son comparados con la intención de definir cuál genera mejores resultados en cuanto a la calidad de energía, prestando especial atención a la tasa de distorsión armónica (THD) obtenida, para el esquema simulado de un banco de pruebas experimentales desarrollado por el grupo de investigación SEPIC de la UPC. Los resultados obtenidos permiten concluir que, aunque los dos tipos de controladores presentados compensan el contenido armónico introducido por la carga no lineal del sistema cumpliendo con la normativa asociada a sistemas que requieren potencia, solamente el MPC lo realiza de una manera precisa, lo cual esta asociado a que al tener una función de coste que integra tanto las variables como las restricciones que deben ser tenidas en cuenta, realiza de forma autónoma los cálculos que optimizan el comportamiento del SAPF para el objetivo planteado.[ANGLÈS] The use of electronic equipment in industrial applications is constantly growing due to the advantages that are inherent to these elements in terms of controlling the behavior of the systems. That said, the increase of non-linear loads has been inevitable, directly increasing the distortion of the current and the voltage from the distribution network, causing significant losses, worsening the power factor, and, ultimately, reducing the quality of the electric power. In order to solve this type of inconvenience, several methods have been implemented to compensate the impact of non-linear loads, but it has been found that their behavior can lead to additional problems. An example of this are the capacitor arrays and the commonly known passive filters. However, the implementation of active filters have been very well received in recent years because of the characteristics of its dynamic that allows the adaptation to the needs of the system to be compensated. That is why the development of controllers that allow to dominate the behavior of active filters has become an inherent necessity for industrial growth, and nowadays there is a great diversity of control methods that can be implemented for it. Throughout this Final Master’s Project (TFM) the simulations of two types of control are developed for a system that has an active filter in parallel (SAPF) to a non-linear load: the Control in the reference frame and the Model Predictive Control (MPC). These are compared with the intention to define which one generates the best results in terms of the energy quality, paying special attention to the harmonic distortion rate (THD), of the simulated scheme of an experimental test bench developed by the SEPIC research group of the UPC. par The results obtained allow us to conclude that, although the two types of controllers presented compensate the harmonic content introduced by the non-linear load of the system complying with the regulations associated with systems that require power, , only the MPC does it in an accurate way, which is associated with the fact that having a cost function that integrates both the variables and the restrictions that must be taken into account, gives the controller the autonomy to independently perform the calculations that optimize the behavior of the SAPF for the proposed objective

Control strategy of grid connected power converter based on virtual flux approach

A la portada consta el nom del programa interuniversitari: Joint Doctoral Programme in Electric Energy Systems [by the] Universidad de Málaga, Universidad de Sevilla, Universidad del País Vasco/Euskal Erriko Unibertsitatea i Universitat Politècnica de CatalunyaDistributed Generation (DG) provides an alternative to the Centralized Generation (CG) by means of generating electricity near to the end user of power with the employment of small-scale technologies to produce electricity, mainly using Renewable Energy Sources (RES). The prospects of renewable energy integration during the next years are still very optimistic. This PhD dissertation is made to provide an alternative control framework for the grid connected power converter by adopting the virtual flux concept in the control layer. This dissertation can be divided into three main topics. The 1st topic presents the voltage sensorless control system for the grid-connected power converter. The control system presented is done without depending on AC-voltage measurement where the grid synchronization is based on the Virtual Flux (VF) estimation. In this regard, the Frequency Locked Loop (FLL) is used in conjunction with the estimation scheme to make the system fully adaptive to the frequency changes. This voltage sensorless application is useful for reducing cost and complexity of the control hardware. It is also can be utilized in case of limited reliability or availability of voltage measurements at the intended point of synchronization to the grid. Considering that most previous studies are based on the VF estimation for the case of power converter connected to the grid through the L-filter or LC-filter, this dissertation is focused on the power converter connected to the grid through the LCL filter. The Proportional Resonant (PR) current controller is adopted in the inner loop control of the power electronics-based converter to test the performance of such system. Another control method based on VF synchronization that permits to control the active and reactive power delivery in a remote point of the grid is also presented in this dissertation. This is due to the fact that the VF is implemented that the voltage in a remote point of the line can be estimated. As it will be shown in simulations and experiments, the proposed control scheme provides a good tracking and dynamic performance under step changes in the reference power. The fast synchronization and the smooth reference tracking achieved in transient conditions have demonstrated the effectiveness of the Dual Second Order Generalized Integrator controlled as Quadrature Signal Generator (DSOGI-QSG) and also the current controller used in the proposed system. In addition to the power control itself, this study could also benefit the frequency and the voltage regulation methods in distributed generation applications as for instance in microgrid. Considering the fact that the grid connected power converter can be controlled as a virtual synchronous generator where the flux is a variable to be used for controlling its operation, this dissertation also presents a Virtual Synchronous Flux Controller (VSFC) as a new control framework of the grid connected power converter. In this regard, a new control strategy in the inner loop control of the power converter will be proposed. The main components of the outer loop control of VSFC are based on the active and reactive power control. The results presented show that the VSFC works well to control the active and reactive power without considering any synchronization system. The inner loop control is able to work as it is required, and the measurement flux is able to track the reference flux without any significant delays. All the work presented in this dissertation are supported by mathematical and simulation analysis. In order to endorse the conclusions achieved, a complete experimental validations have been conducted before wrapping this dissertation with a conclusion and recommendation for future enhancement of the control strategies that have been presented.Postprint (published version