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Renewable energy sources have power quality and stability issues despite having vast benefits when integrated with the utility grid. High currents and voltages are introduced during the disconnection or injection from or into the power system. Due to excessive inverter switching frequencies, distorted voltage waveforms and high distortions in the output current may be observed. Hence, advancing intelligent and robust optimization techniques along with advanced controllers is the need of the hour. Therefore, this article presents an improved arithmetic optimization algorithm and an offset hysteresis band current controller. Conventional hysteresis band current controllers (CHCCs) offer substantial advantages such as fast dynamic response, over-current, and robustness in response to impedance variations, but they suffer from variable switching frequency. The offset hysteresis band current controller utilizes the zero-crossing time of the current error for calculating the lower/upper hysteresis bands after the measurement of half of the error current period. The duty cycle and hysteresis bands are considered as design variables and are optimally designed by minimizing the current error and the switching frequency. It is observed that the proposed controller yields a minimum average switching frequency of 2.33 kHz and minimum average switching losses of 9.07 W in comparison to other suggested controllers. Results are validated using MATLAB/Simulink environment followed by real-time simulator OPAL-RT 4510.

A second-order-generalized-integrator (SOGI)-based frequency-locked-loop (FLL) equivalent proportional-resonant (PR) current controller is introduced in this paper to minimize torque ripple in switched reluctance motor (SRM) drive system. The typical cascaded closed-loop speed control of SRM comprises a speed controller giving desired torque, a static look-up table mapping the desired torque to desired/reference phase currents of SRM, and a current controller to track the reference phase currents. It is often seen that conventional current controllers like hysteresis controllers, proportional-integral (PI) controllers, and even intelligent controllers such as fuzzy logic controllers and model predictive direct torque controllers (MPDTC) are not very effective in minimizing the torque pulsations for a wide range of operating scenarios. The proposed SOGI-FLL-PR-based current control strategy is aimed at improving torque control under a wide range of operations of SRM. The performance of the proposed current controller has been compared to that of traditional current controllers like the hysteresis controller, the proportional-integral controller, the fuzzy logic current controller (FLCC), and MPDTC; and has shown to be superior in both simulation and experimental studies. Our study details a systematic approach to the dynamic modeling of SRMs, control strategy formulation, dynamic analysis, and experimental verification.

Parabolic carrier Pulse Width Modulation (PWM) method is considered as one of the direct current control methods for the Voltage Source Converters (VSCs). This method has an excellent dynamic response. Besides, it offers a constant switching frequency by employing a pair of parabolic PWM carriers. However, it suffers from some drawbacks and limitations. The major drawback of this method is its sensitivity to the inductance variations. In other words, in grid-connected applications, the exact value of grid inductance should be known to achieve a proper performance. Moreover, it is essential that during each switching cycle, the voltage at the point of common coupling remains constant. In grid connected applications such as active power filter, these drawbacks may lead to operation at variable or non-expected frequencies. Therefore, this paper provides suggestions to deal with the situation. In this paper, by applying the conventional method, the aforementioned problems are examined in a grid-connected active power filter. It is shown analytically that by using the proposed method, the problem of sensitivity to inductance is overcome and the necessity for a constant voltage at the point of common coupling in a switching period will be solved as well. The simulation and experimental results are presented.

The permanent magnet synchronous motor (PMSM) is a highly efficient energy saving machine. Due to its simple structural characteristics, good heat radiation capability, and high efficiency, PMSMs are gradually replacing AC induction motors in many industrial applications. The PMSM has a nonlinear system and lies on parameters that differ over time with complex high-class dynamics. To achieve the excessive performance operation of a PMSM, it essentially needs a speed controller for providing accurate speed tracking, slight overshoot, and robust disturbance repulsion. Therefore, this article provides an overview of different robust control techniques for PMSMs and reviews the implementation of a speed controller. In view of the uncertainty factors, such as parameter perturbation and load disturbance, the H∞ robust control strategy is mainly reviewed based on the traditional control techniques, i.e., robust H∞ sliding mode controller (SMC), and H∞ robust current controller based on Hamilton–Jacobi Inequality (HJI) theory. Based on comparative analysis, this review simplifies the development trend of different control technologies used for a PMSM speed regulation system.

This paper presents the improvement of operating characteristics of three level full bridge ac–dc converter by proposing four different closed loop control techniques for telecom applications. Comparisons between different controllers have been considered to evaluate the power quality parameters with fast dynamic response under various operating conditions. Simulations have been done with Matlab/Simulink with four different voltage and current controllers, namely; PID with hysteresis current controller, Fuzzy Logic with hysteresis current controller (FL-HCC), Hysteresis Modulation based Sliding Mode Controller (HM-SMC) and Genetic Algorithm based Average Current Control (GA-ACC). Comparative analysis has been carried out with power factor, total harmonic distortion (THD) for various loading conditions upto 300 W. Based on the comparative analysis, GA-ACC technique provides better power quality parameters with improved dynamic response than the other three controllers. GA-ACC technique improved the power factor to 0.9911 and source current THD of 5.11% for converter. Also, voltage ripple and efficiency of the converter were calculated and tabulated under a wide range of load variations. Simulated results of the converter with GA-ACC have been validated with the experimental results.

This paper presents a comprehensive study on a novel voltage injection based offline parameter identification method for surface mounted permanent magnet synchronous motors (SPMSMs). It gives solutions to obtain stator resistance, d- and q-axes inductances, and permanent magnet (PM) flux linkage that are totally independent of current and speed controllers, and it is able to track variations in q-axis inductance caused by magnetic saturation. With the proposed voltage amplitude selection strategies, a closed-loop-like current and speed control is achieved throughout the identification process. It provides a marked difference compared with the existing methods that are based on open-loop voltage injection and renders a more simplified and industry-friendly solution compared with methods that rely on controllers. Inverter nonlinearity effect compensation is not required because its voltage error is removed by enabling the motor to function at a designed routine. The proposed method is validated through two SPMSMs with different power rates. It shows that the required parameters can be accurately identified and the proportional-integral current controller auto-tuning is achieved only with very limited motor data such as rated current and number of pole pairs.

This research introduces an adaptive hysteresis current controller (HCC) integrated with a multilevel inverter (MLI) and a battery storage system (BSS), which improves real power injection accuracy and enhances performance during load fluctuations. Maintaining voltage stability is essential for delivering high-quality power, especially as networks become increasingly complex, particularly in distributed systems with nonlinear loads, necessitating innovative control strategies. The proposed controller demonstrates superior performance compared to traditional methods, overcoming the limitations of conventional inverters. Simulation results indicate that the total harmonic distortion (THD) of the system achieves 2.43%, representing a 52% improvement over standard HCC, and enhances system efficiency by 6.8%. Additionally, the adaptive HCC reduces current injection errors by up to 85%, indicating significant efficacy, with phase angle deviations of less than 1° from the grid voltage. This reduction in reactive power demands contributes to maintaining grid stability under controlled and stressed conditions. These results comply with IEEE Std 519-2014 and IEC 61000-3-2 standards, ensuring reliability. This novel adaptive technique ensures stable grid connection and improved power quality, particularly in residential and commercial areas with prevalent nonlinear loads. The findings confirm the method’s reliability and effectiveness for modern grids, even during dynamic and unstable conditions.

This paper presents a novel method for current control for a modular multilevel converter (MMC). The proposed current control methodology is based on a modified sliding mode control (SMC) with proportional and integral (PI) sliding surface which allows fast transient responses and improves the robustness of the MMC control performance. As the proposed method is derived via Lyapunov direct method, the closed-loop stability is ensured and results in globally asymptotically stable. Furthermore, the reaching time is also guaranteed by the proposed method, leading to fast transient responses. The proposed method is validated by comparing with some existing methods, which are proportional integral controller and conventional SMC, via offline and hardware-in-loop (HIL) simulations where a 10 MW, medium-voltage MMC system is tested. According to these results, the proposed method is able to provide fast transient responses, zero overshoot, and robustness to the weak grid and short-circuit conditions.

This paper addresses the challenges encountered by grid-connected photovoltaic (PV) systems, including the stochastic behavior of the system, harmonic distortion, and variations in grid impedance. To this end, an in-depth technical and pedagogical analysis of three linear multivariable current control strategies is performed: proportional-integral (PI), proportional-resonant (PR), and deadbeat (DB). The study contributes to theoretical formulations, detailed system modeling, and controller tuning procedures, promoting a comprehensive understanding of their structures and performance. The strategies are investigated and compared in both the rotating (dq) and stationary (αβ) reference frames, offering a broad perspective on system behavior under various operating conditions. Additionally, an in-depth analysis of the PR controller is presented, highlighting its potential to regulate both positive- and negative-sequence components. This enables the development of more effective and robust tuning methodologies for steady-state and dynamic scenarios. The evaluation is conducted under three main conditions: steady-state operation, transient response to input power variations, and robustness analysis in the presence of grid parameter changes. The study examines the impact of each controller on the total harmonic distortion (THD) of the injected current, as well as on system stability margins and dynamic performance. Practical aspects that are often overlooked are also addressed, such as the modeling of the inverter and photovoltaic generator, the implementation of space vector pulse-width modulation (SVPWM), and the influence of the output LC filter capacitor. The control structures under analysis are validated through numerical simulations performed in MatLab® software (R2021b) using dedicated computational routines, enabling the identification of strategies that enhance performance and ensure compliance of grid-connected photovoltaic systems.

This study proposes an advanced control scheme for the interlinking inverters of the hybrid AC/DC microgrids, which facilitates a seamless transition between grid-connected and stand-alone/islanding modes for the microgrid. Due to a nonlinear relationship between the terminal voltages of the voltage-source inverter (VSI) interfacing through inductor–capacitor (LC) filters with the grid voltages and currents, a feedback linearization technique (FLT) is employed to control the interlinking VSI under both grid-connected and islanding operations. The FLT-based current controllers are applied in the grid-connected mode, in which they adjust the power exchange between the DC and AC subgrids and mitigate the distortion of the grid currents produced by nonlinear loads. Under the stand-alone operation, the AC bus voltages are directly regulated by the FLT-voltage controllers of the interlinking VSI. In order to reduce the inrush currents and voltage overshot at the instant of mode switching, the FLT-based controllers are performed all the time regardless of the operating modes, where the voltage references for the VSI are not changed abruptly. The control performance of the VSI is highly satisfactory with low-transient overshoot values of the voltages and currents and low total harmonic distortion (THD) values of the grid currents and AC bus voltages are about 3.5% and 2.7%, respectively, under the nonlinear load condition. The validity of the new control strategy is verified by the simulation work, which investigates the operation of a hybrid AC/DC microgrid.