Inverter Control Research Articles

Hybrid control for capacitor-assisted Z-source inverter in grid-connected photovoltaic system

Renewable energy integration into the power grid is essential for sustainable energy systems, but maintaining efficiency and reliability in such systems remains a key challenge. This study introduces a novel hybrid control topology for a Capacitor-Assisted Extended Boost Z-Source Multilevel Inverter in a grid associated solar photovoltaic (PV) structure. The suggested hybrid technique implies a united implementation of a Gannet Optimization Algorithm and Spiking Deep Residual Network and usually referred as GOA-SDRN technique. Initially, the modelling of the inverter is collected to get the best signal by the proposed controller. The proposed inverter configuration consists of a minimal quantity of diodes, switches, and sources. This configuration also offers advantages like less total harmonic distortion (THD) and reduced electromagnetic interference, making it a favourable choice for PV integration. The GOA is employed to determine the most favourable gain limiting factor based on a variation of power from their regular values. This control method ideally satisfies the load demand while reducing changes in the system limiting factor and external disturbances. The proposed control topology is executed in MATLAB and the concept is contrasted to different techniques. The THD values of existing methods such as Particle Swarm Optimization, Genetic Algorithm, and Grasshopper Optimization Algorithm are 1.36 %,0.89 %, and 1.99 % respectively, while the THD value of the proposedmethod is 0.63 %, demonstrating its optimal performance over existing methods. The proposed GOA-SDRN technique provides an effective solution for enhancing inverter efficiency and reducing distortion in grid-associated PV systems.

An optimized controller for novel asymmetrical 51-level inverter in hybrid solar and wind turbine-connected power system

An optimized controller for novel asymmetrical 51-level inverter in hybrid solar and wind turbine-connected power system

Retraction Note: Investigation of different MPPT techniques based on fuzzy logic controller for multilevel DC link inverter to solve the partial shading

Retraction Note: Investigation of different MPPT techniques based on fuzzy logic controller for multilevel DC link inverter to solve the partial shading

Dynamic control of grid-following inverters using DC bus controller and power-sharing participating factors for improved stability

Integrating Grid-Following Inverters (GFLs) into power systems presents significant stability challenges, particularly in systems with reduced strength and high renewable energy penetration. This study delves into the dynamic interactions between parallel synchronous generators (SGs) and GFLs, highlighting the impact of reduced system inertia and transient stability margins. A novel DC bus controller is proposed to enhance the inertia and stability of GFLs during grid disturbances by dynamically adjusting power references based on load demand. Through mathematical modelling, small signal analysis, and MATLAB simulations, the study evaluates the effects of inverter-based resources (IBRs) on power system stability. The proposed GFL configuration demonstrates improved stability control, achieving an 80 % increase in stability under weak grid conditions. This paper provides insights into optimized control strategies, emphasizing the importance of power-sharing participation factors (PSPF) for effective GFL integration in modern power systems with high renewable energy penetration.

Fractional Order Feedforward Odd-Harmonic Repetitive Controller for Grid-Tied Inverters in Microgrids

Fractional Order Feedforward Odd-Harmonic Repetitive Controller for Grid-Tied Inverters in Microgrids

Power Control for Household Energy Storage Inverter With Smooth Mode Transition

Power Control for Household Energy Storage Inverter With Smooth Mode Transition

High-Frequency Modified Bridgeless AC-DC PFC Rectifier for Ceiling-Fan

High current percentage total harmonics distortion (%THD), low supply power factor (SPF), and high input-power are main concern in an existing brushless direct current motor ceiling-fan (BLDCMCF). This paper presents AC-DC coupled-inductor-based bridgeless switched-inductor Cuk-converter (CIB-BLSICC) for BLDCMCF to address these concerns. CIB-BLSICC improves supply power quality (SPQ) and reduces input-power. Switched-inductor branch using coupled-inductor provides high-step-down-gain (HSDG), which offers an appropriate operating duty for BLSICC. Front-end CIB-BLSICC is developed in discontinuous mode (DCM) with changeable output voltage and a low component count, which reduces converter's overall size. DCM design offers auto power-factor correction (PFC) at a supply-mains. Variable output-voltage makes voltage source inverter (VSI) control easy (offers inverter switching at fundamental-frequency) with low switching-losses and helps speed-control. In addition to improving CF's (ceiling-fan's) overall efficiency, bridgeless design of PFC-converter lowers losses caused by conduction. Using reference speed of fan, CIB-BLSICC calculates its operational duty in order to create fixed-frequency PWM-pulses (200 kHz) while supply-voltage remains constant. This simple-control brings CF's price down by removing need for a sophisticated sensing-circuit, a DC-link sensor, and a voltage-controller. Test results confirm concept and design, which demonstrate a %THD of 1.483%, a crest-factor of 1.48, SPF of 0.9991, and a power-input of 27.93 W.

Autonomous Control of Voltage and Frequency in Parallel Inverters of Microgrid

Integration of Distribution Generations (DGs) provides flexibility in power transmission. DGs reduce expenditure, expansion of transmission lines and transmission loss. DGs can work separately from the main grid with local loads and form a microgrid. In grid-connected mode, the voltage and frequency of the microgrid are regulated by the main grid. Voltage and frequency regulation in the islanding microgrid are crucial. This paper presents voltage and frequency control techniques for parallel inverters in microgrid. The proposed model works on close loop control of inverters and it can be used for plug-and-play operation of microgrid. The Microgrid model is developed in MATLAB/Simulink and the performance of the system is analyzed in grid-connected mode and isolation mode.

Fuzzy logic based improved direct torque control of DFIG-based wind turbines

This paper investigates direct torque control with a fuzzy controller (F-DTC) for a two-level voltage source inverter feeding the rotor of a doubly-fed induction generator (DFIG) based on a variable-speed wind energy conversion system (VSWECS). The wind turbine's MPPT technology is used to obtain the torque reference. The proposed fuzzy logic-based direct torque control (F-DTC) is designed to eliminate the flux and electromagnetic torque ripples that are common with existing (DTC) controls, leading to smoother operation and improved efficiency in the wind energy conversion system. The fuzzy logic controller improves switching decision-making by handling uncertainties and non-linearities, resulting in smoother and more efficient control of the torque and flux. To validate the effectiveness of the proposed F-DTC method, simulations are conducted in MATLAB/SIMULINK, and the results are compared with those of the classical DTC approach. The findings demonstrate that the F-DTC strategy significantly reduces torque and flux ripples, enhances the dynamic response, and improves overall system performance.

Research on current sharing control of parallel inverters used on electric motor emulator

AbstractParallel inverters have the advantages of low‐output harmonics and high‐parallel power, making them very suitable as the topology structure for an electric motor emulator. However, parallel inverters can also bring about circulating current issues, especially when using carrier phase shifted sinusoidal PWM (CPS‐SPWM) control mode, which significantly increases circulating current, leading to increased output harmonics and losses in the system. In order to suppress circulating currents, this paper provides a detailed analysis from both high‐frequency and low‐frequency perspectives in CPS‐SPWM control mode. A circulating current suppression method that combines hardware and software systems, adopting a cascaded coupled output network structure along with a corresponding error voltage space vector control method to achieve circulating current suppression, is proposed. By constructing a 6‐branch parallel output experimental platform, the feasibility and effectiveness of the proposed method have been verified, suppressing current circulating currents and improving current quality.

A new model reduction method based PBC control for grid-connected inverter with LCL-filter

Passivity-based control (PBC) exhibits robustness against parameters shift, providing a substantial level of stability. However, for the LCL-filtered grid-connected inverter (GCI), the conventional PBC (called C-PBC) controller has a narrow control bandwidth due to the control time delay, resulting in poor dynamic performance, especially in the weak grid state. This paper proposes a new PBC (called P-PBC) method to increase the closed-loop bandwidth of the system by setting an appropriate feedback proportional coefficient between the grid-side current and the inverter-side current. By extending the closed-loop bandwidth of the system, the proposed P-PBC method offers improved dynamic performance, particularly in challenging grid conditions. In addition, a state observer is also employed to reduce sensors, which saves costs and enhances the system's reliability. A 110 V/50 Hz/3 kW/3-phase experimental setup has been developed using the dSPACE DS1202 platform to validate the effectiveness of the proposed control method.

New Approaches in Finite Control Set Model Predictive Control for Grid-Connected Photovoltaic Inverters: State of the Art

Grid-connected PV inverters require sophisticated control procedures for smooth integration with the modern electrical grid. The ability of FCS-MPC to manage the discrete character of power electronic devices is highly acknowledged, since it enables direct manipulation of switching states without requiring modulation techniques. This review discusses the latest approaches in FCS-MPC methods for PV-based grid-connected inverter systems. It also classifies these methods according to control objectives, such as active and reactive power control, harmonic suppression, and voltage regulation. The application of FCS-MPC particularly emphasizing its benefits, including quick response times, resistance to changes in parameters, and the capacity to manage restrictions and nonlinearities in the system without the requirement for modulators, has been investigated in this review. Recent developments in robust and adaptive MPC strategies, which enhance system performance despite distorted grid settings and parametric uncertainties, are emphasized. This analysis classifies FCS-MPC techniques based on their control goals, optimal parameters and cost function, this paper also identifies drawbacks in these existing control methods and provide recommendation for future research in FCS-MPC for grid-connected PV-inverter systems.

Fixed Switching Frequency Model Predictive Control for Parallel Inverters in Microgrids

A Fixed-Switching-Frequency Model Predictive Control (FSF-MPC) for Master-Slave inverters in microgrids is proposed in this paper. The Master is a three-phase, two-level inverter with an LC filter, while the Slave is a three-phase, two-level inverter with an LCL filter. The inverters are connected in parallel in a microgrid, composed of different loads. The voltage and current inner control loops of the Master-Slave FSF-MPC are presented for both inverters. Then, two modes of operation are proposed: grid-connected and islanded, and the primary control for both cases is developed. Finally, Hardware-in-the-Loop (HIL) results are presented for different operational conditions of the microgrid with load-related disturbances. The HIL results validate the good performance of the proposed Master-Slave FSF-MPC, including fast dynamic response, multi-objective control, and fixed switching frequency.

Control of Grid-Tied Inverter During Unbalanced Transient Fault

With increasing use of renewable and clean form of energy, PV systems have become popular due to its versatility and easy implementation. The overall performance of grid-connected PV systems is directly influenced by the performance of grid-tied inverter. Hence, control of grid-tied PV inverter has become a temptation. This project explores the development of grid-connected PV system and optimization of control strategies for grid-tied inverter to ensure its seamless operation and grid stability during transient faults. The transient faults occurring at the inverter side disrupts the normal operation of inverter and even lead to shut down of inverter during faults.Therefore, a control strategy is suggested and developed to control the overvoltage of DC-link capacitor and deliberately functioning and output of grid-tied inverter is improved. This is simply possible by introducing ELC so that the inverter needs not be shut down.

Modeling of Grid Tied PV Inverter to Improve its Performance During Unbalanced Load and Unbalance Fault

Integrating solar through inverter brings about various challenges in the microgrids and the inverter itself. This paper aims to the study of problems in the operation of inverter during unbalance load and unbalance fault condition along with the possible control measures to mitigate those problems to ensure the safe and reliable operation of the inverter. A grid connected PV inverter is modeled using hysteresis band controller and implementing the MPPT of the PV system with the buck boost converter. During unbalance load and unbalance fault condition, the negative and zero sequence components of current exists. All the zero-sequence component of current is delivered by the grid. The negative sequence component of current also flows through the inverter resulting in high value of current and loss of stability. Also, the voltage across the dc link capacitor increases during fault. The high value of current flowing through the inverter and high voltage across dc link capacitor may damages the inverter and capacitor respectively. An inverter dual current controller is introduced replacing the hysteresis band control such that the negative sequence component of current flowing through the inverter is almost mitigated from 600A to 10A and positive sequence current is also reduced relatively to a tolerable value 150A from 550A. The total current flowing through the inverter is limited to 200A from 950A and voltage across dc link capacitor is limited to 700V from 1050V during LG fault at the inverter side thus ensuring safe operation of the inverter during voltage dip condition. A further study can be done on limiting the positive sequence component of current to a rated value and improving the performance while operating in islanded mode.

Voltage quality improvement method based on adaptive power control of photovoltaic inverter

Abstract With the increasing penetration rate of distributed photovoltaics in the distribution network in China, the energy pressure has been effectively alleviated. However, the voltage over-limit problem of its parallel outlets cannot be ignored. Therefore, this paper put forward a power control method with photovoltaic inverters which is adaptive. First, the principle of photovoltaic voltage overstepping the limit is analyzed, and second, an adaptive control tactic is brought up for the disturbance of the volatile load of photovoltaic output. Finally, combined with the analysis and verification of simulation examples, the results show that the proposed strategy can effectively improve the voltage quality of the grid and prove the effectiveness of the proposed strategy.

A Novel Modulated Model-Free Predictive Control for LC-Filtered Grid-Forming Inverters with Double-Difference Updating

A Novel Modulated Model-Free Predictive Control for LC-Filtered Grid-Forming Inverters with Double-Difference Updating

Stability Control for Grid-Connected Inverters Based on Hybrid-Mode of Grid-Following and Grid-Forming

Stability Control for Grid-Connected Inverters Based on Hybrid-Mode of Grid-Following and Grid-Forming

Feedforward Repetitive Control for Grid-Tied Inverters in Microgrids: Analysis, Design, and Verification

Feedforward Repetitive Control for Grid-Tied Inverters in Microgrids: Analysis, Design, and Verification

Virtual Model Predictive Control for Inverters to Achieve Flexible Output Impedance Shaping in Harmonic Interactions With Weak Grids

Virtual Model Predictive Control for Inverters to Achieve Flexible Output Impedance Shaping in Harmonic Interactions With Weak Grids