Inverter Voltage Research Articles

DC‐link voltage stability enhancement in intermittent microgrids using coordinated reserve energy management strategy

AbstractIn recent years, due to its cost effectiveness and environmental advantages, demand for renewable energy resources has grown and their contributions to grid power has therefore increased while requiring effective frequency and voltage regulation. DC link voltage instability is a potential problem in solar energy microgrids, especially during an intermittency, where the system reliability degrades and DC link capacitor is under higher stress. In this article, a novel reserve energy management scheme based on battery and super capacitor storage is presented to stabilize the DC link voltage and reduce capacitor stress, while enhancing the system reliability. The scheme is tested in four different scenarios: Inverter connected DC‐microgrid with irradiance intermittencies, standalone DC‐microgrid without inverter and irradiance intermittencies, standalone DC‐microgrid without inverter and load intermittencies, and standalone DC‐microgrid with inverter under irradiance intermittencies. Simulation results indicate that the proposed control strategy stabilizes DC link voltage over all scenarios, even subject to large instances of irradiance or load changes. During low solar irradiance, the battery and super‐capacitor promote voltage stability by compensating power deficits from the utility grid in the inverter connected grid case. In stand alone mode, the battery provides power during intermittencies and the supercapacitor provides fast transient voltage compensation. The strategy is notable in reducing stress on DClink capacitors and mitigating inverter voltage fluctuations, ultimately enhancing inverter longevity. The results show that the proposed control scheme can improve voltage stability, mitigate the transient effects and guarantee the reliable operation of solar microgrids in variable conditions.

ANALYTICAL MODEL FOR THE SWITCHING VOLTAGE AND GAIN COEFFICIENT OF A CMOS INVERTER WITH NANOCHANNEL 2D TRANSISTORS

The study presents an analytical model for the switching voltage and gain factor of a CMOS inverter with 2D nanochannel transistors. The derived expressions enable the modeling of these two fundamental parameters of the device, which serves as the basement for logic elements in contemporary nanoelectronics. The feasibility of creating efficient inverters with a high gain factor based on transistors with channels made of 2D monolayers of transition metal dichalcogenides and arrays of carbon nanotubes has been confirmed. It was demonstrated that the gain factor is restricted by the drain induced barrier lowering (DIBL) effect, which is undesirable for FETs (when DIBL trends to zero the gain factor becomes infinitely large).

Straightforward predictive direct power control for grid-connected ANPC inverter with flying capacitor voltage self-balancing

Improving control quality in inverter systems has attracted considerable attention, particularly in multilevel inverters for high-power applications. This study suggests a straightforward predictive direct power control system for a five-level Active Neutral Point Clamped inverter connected to the grid. The proposed method offers the benefit of reducing the heavy computational load by implementing a two-stage optimization process for the objective function. In contrast to the conventional finite control set model predictive control which involves comprehensive searches for all possible switching configurations within the iterative optimization process, the suggested approach focuses only on potential voltage vectors based on the desired inverter voltage’s location at the initial stage. Second, the self-balancing flying capacitor voltages are guaranteed by employing the duplicative switching states. Another advantage of the presented algorithm is an obviation of numerous selecting weighting factors. The effectiveness of the advanced strategy is confirmed through extensive comparative simulation and hardware-in-the-loop studies conducted in both conditions during stable states and transitions. Contrasted to the previous technique, this innovative method demonstrates an improvement in the grid’s power ripple and total harmonic distortion of the current by 14.66% and 19.58%. Furthermore, the computational time required for this method is significantly reduced by 64.58%, and 61.36% correlate to the traditional and other approaches, respectively. These results may facilitate the implementation of an effective control approach for multilevel inverters, employing a cost-effective control platform by a limited sampling interval.

Research on harmonic suppression method of SPWM inverter circuit for photovoltaic power generation system

To effectively reduce and suppress the harmonics generated by single-phase inverter circuits, this paper mainly investigates the harmonic characteristics of single-phase Sinusoidal Pulse Width Modulation (SPWM) inverter in the output voltage and its suppression methods. According to the SPWM principle and Fourier series theory, the mathematical model and simulation of the output voltage of the SPWM inverter are established, and the harmonic characteristics of the SPWM inverter are analyzed. Secondly, the harmonic content and distribution of the output voltage under three different carrier control methods are investigated. Then, two effective methods for suppressing the harmonics of the output voltage of single-phase SPWM inverters are investigated: selecting the appropriate carrier ratio and injecting the proper number of harmonics. Finally, the study shows that a single-phase unipolar frequency doubling SPWM inverter can effectively filter out the high harmonics, making the output voltage waveform smoother and closer to the sinusoidal waveform. This study will have a certain positive impact on the future development of energy-saving power supply, high-quality power supply, and high-performance power supply technology in China, which can realize the efficient and low-pollution use of electric energy.

Proportional resonant controller design with anti-windup for a single-phase solar inverter

This paper introduces a novel control strategy for regulating the output voltage of a single-phase inverter equipped with an LC filter. The proposed method integrates a Proportional Resonant (PR) controller with an anti-windup compensator to address challenges in voltage regulation and system stability. Unlike conventional techniques, this control approach relies on a single measurement from an output voltage sensor, eliminating the need for complex frame transformations and significantly simplifying the control architecture. The innovative use of the PR controller ensures high performance by achieving zero steady-state error for sinusoidal references, making it particularly effective for applications requiring precision and reliability. The anti-windup compensator enhances system robustness by mitigating controller saturation and maintaining stability under varying load conditions. Extensive experimental tests were conducted to validate the proposed method, demonstrating its superior effectiveness and robustness compared to traditional control strategies. Results highlight its ability to achieve fast response times, minimal steady-state error, and consistent performance across a wide range of operating conditions. This control design offers a simplified yet efficient solution for inverter applications, paving the way for improved performance in renewable energy systems, power distribution networks, and industrial automation, where precise voltage regulation is critical.

Design of a Univariate Dual‐Loop Voltage System Based on the Multisampling Method

ABSTRACTThis study presents an innovative control framework designed for voltage source inverters (VSIs) equipped with LC output filters. The objective of this control framework is to reduce delay and suppress aliasing effects by employing multisampling techniques and implementing repetitive filtering methods. The multisampling approach can significantly reduce control delays, thereby enhancing both the bandwidth and stability margins of the system. The implementation of multisampling techniques for inverter voltage can enhance dynamic performance. However, it may introduce high‐frequency ripples in the control loop, resulting in low‐order aliasing harmonics and ultimately leading to output voltage distortion. To address this issue, a multiple notch filter with minimal phase delay is employed suppress aliasing. The optimal parameters of the system are determined by evaluating the filter specifications, filtering effectiveness, output voltage ripple, and overall system performance, while also considering the actual filtering requirements and circuit size. Its effectiveness and performance are carefully verified by experimental results.

Evaluation of an Infinite-Level Inverter Operation Powered by a DC–DC Converter in Open and Closed Loop

This paper evaluates the open- and closed-loop DC–DC converter operation within a DC coupling multilevel inverter architecture to obtain an infinite-level stepped sinusoidal voltage. Adding a cascade controller to the DC–DC converter should reduce the settling time and increase the number of levels in the output voltage waveform; it could decrease the speed error and phase shift concerning the sinusoidal reference signal. The proposed methodology consists of implementing an experimental multilevel inverter with DC coupling through a single-phase bridge inverter energized from a BUCK converter. Trigger signals for the two converters are obtained from a control circuit based in an ATMEGA644P microcontroller to explore its capabilities in power electronics applications. A digital controller is also implemented to evaluate the operation of the BUCK converter in open and closed loop and observe its influence in the stepped sinusoidal output voltage. The evaluation is performed to energize a resistive load with common output voltage in multilevel inverters, i.e., 3, 5, 7, 11, and infinity levels. Results show that during the design stage, fast dynamic elements, like the storage capacitor, can be used to obtain a minimum THD because the settling time is sufficiently fast, the speed error remains small, and there is no need for a controller. A digital controller requires processing time, and although in theory it can reduce the settling time to a minimum, the processor introduces latency in the control signals generation, producing the opposite effect. Controller complexity of the digital controller must be considered because it increases processing time and influences the efficiency of the closed-loop operation.

Design of single-phase shifted full-bridge inverter voltage regulation system based on voltage-controlled closed-loop control and LLC resonant network

Abstract The phase-shifted full-bridge inverter is widely used in the field of power electronics technology, aiming to achieve precise regulation of the output voltage and improve the stability and efficiency of the power system. This paper proposes a single-phase phase-shift full-bridge inverter voltage regulation system and its parameter design method based on the LLC resonant network. Combined with voltage-controlled closed-loop control and APFC technology, the working mode of the system circuit is analyzed, and the system parameters are designed. The system simulation model is built in MATLAB/Simulink. The constant voltage output of the system is realized, the power factor is greater than 96%, and the relative error of the output voltage change is less than 2%.

A bi-level inter-phase coordinated control method for voltage regulation in unbalanced LV distribution networks using PV-battery energy storage systems

Photovoltaic systems coupled with battery energy storage (PV-BES) can help to minimize the effects of variability in PV generation including voltage problems in low voltage distribution grids (LVDNs). Therefore, a joint centralized-decentralized method consisting of two control levels based on sensitivity analysis is proposed in this paper, which employs the BES charging and discharging control in the first level and reactive power capability of inverters in the second control level. When the BES charging and discharging control is insufficient for voltage regulation, the second level of the proposed method is triggered. For full utilization of the BES capacity and to ensure adequate capacity for the following day's voltage regulation needs, an enhancement algorithm is applied to the voltage to active power sensitivity coefficients. All of the voltage sensitivity coefficients are calculated by a central controller using an offline procedure and sent to the PV-BES inverters to determine the amount of active and reactive power in real-time according to the measured local voltage. Taking into account the inter-phase voltage effects, a request for Var compensation signal flow with inter-phase coordination constraints is utilized to properly coordinate the inverters in reactive power control. The proposed method can efficiently regulate voltage by preventing over and under-voltage problems, improving the average total voltage deviation (TVD), reducing the total reactive power absorption and injection by the inverters, and avoiding reduction in PV generation. To evaluate the performance of the proposed control method, it is compared with the commercially available inverter voltage control techniques in an unbalanced residential test feeder. Moreover, a comparison is conducted between the proposed method and an adaptive decentralized control approach presented in the literature. Furthermore, a three-phase Volt-Var strategy, with and without the inter-phase coordination constraints, is simulated that indicates the necessity of the constraints for proper coordination.

A RANDOMIZED CARRIER-BASED DISCONTINUOUS PULSE WIDTH MODULATION STRATEGY FOR NEUTRAL POINT CLAMPED THREE-LEVEL INVERTER

This article introduces a novel approach called randomized carrier-based discontinuous pulse width modulation (RCDPWM) to address the challenge of mitigating both low-order and high-order harmonics concentrated at the switching frequency and its integer multiples in the output voltage and current of a three-level inverter. The proposed strategy reduces switching losses and a wide dispersion of voltage and current harmonics with significantly smaller amplitudes by integrating features from discontinuous and randomized PWM methods. This characteristic proves beneficial for enhancing efficiency and electromagnetic compatibility. The RCDPWM strategy involves three schemes: two simple schemes (one random parameter), randomized pulse position modulation (RPP-DPWM) and randomized carrier frequency modulation (RCF-DPWM), and a dual scheme combining the two previous ones (RPPRCF-DPWM). Power spectral density (PSD) is used to assess the effectiveness of the proposed strategy in quantitatively analyzing the harmonic dispersion degree. The results demonstrate that the proposed RCDPWM strategy significantly expands harmonic clusters around the switching frequency, reducing its intensity. The spectrum analysis revealed that the RPPRCF-DPWM scheme is the most effective in spreading the output voltage and current spectrum compared to simple schemes (RPP-DPWM and RCF-DPWM).

Adaptive control strategy for microgrid inverters based on Narendra model

In recent years, microgrid technology has been widely studied and applied. However, with times developing, the installed capacity of distributed power generation devices has been improved, and work is being carried out in increasingly complex situations, resulting in a decline in the control performance of microgrids. In view of this, to effectively improve inverter’s control performance, research is conducted on the fusion of Narendra model and adaptive control strategies for real-time voltage correction and compensation in complex situations. Compared to traditional inverters, inverters under research methods have faster voltage recovery speed when encountering load switching, and can recover in about one cycle, with good control performance. In the comparison between the improved inverter adaptive control system and the inverter adaptive system, the improved inverter voltage recovery speed is faster, can be restored within one cycle, and the control effect of the inverter is better. The harmonic rate of the port voltage has decreased from 10.43 to 1.92%. The applicability of the research method was verified. It indicats that the research method can improve inverter’s control effect and solve problems such as voltage deviation, three-phase asymmetry, harmonic pollution, etc. that are easily generated by the output terminal voltage. Simultaneously, research has provided theoretical basis and data support for the research of microgrids.

Virtual power plant management with hybrid energy storage system

The transition to renewable energy sources and distributed energy generation (DG) has spurred the global evolution of energy production methods. However, virtual power plants (VPPs) face challenges due to fluctuations in renewable energy sources (RES) production, such as those from photovoltaics and wind turbines. Factors like temperature, solar radiation, wind speed, and high-frequency interference contribute to unstable output power, potentially affecting power supply quality with voltage fluctuations and frequency changes. To address these challenges, it is crucial to smooth alternating current before grid transmission.This paper proposes a solution involving a smart grid with decentralized generators and controllable loads forming a VPP. The approach introduces a Hybrid Energy Storage System (HESS) comprising batteries, supercapacitors, and fuel cells. Equipped with proportional-integral (PI) and model predictive control (MPC) regulators, the HESS aims to regulate inverter voltage for renewable energy. By converting fluctuating electricity into high-quality power, the system enables seamless integration into the VPP, thereby preventing disruptions in generation processes and reducing potential costs associated with damage caused by power fluctuations to grid-connected devices.In the context of the HESS, a photovoltaic system and a wind turbine have been developed, with the proposed system connected to an RLC series load through an IGBT inverter. To evaluate the effectiveness of the HESS within the proposed VPP, two different scenarios were examined by varying the location of these systems in a 14-bus microgrid.

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.

Optimasi Charger Controller Pembangkit Listrik Picohidro Kapasitas 250 Watt

PLTMH is one of the renewable energy power plants that is environmentally friendly. Indonesia has considerable hydropower potential that can be developed into Micro / Mini Hydro Power Plants of 19,385 MW spread throughout Indonesia [2]. PicoHidro Power Plant is part of PLTMH with an output power of < 1 kW [1]. The advantages of this plant are generating electricity without being too influenced by seasons and day and night changes, power generation fluctuations are relatively small, the possibility of electricity generation is high, the impact on the environment is very small and the fast response is suitable for peak load conditions and when there is a disturbance in the network. PLPicohidro uses a DC generator that utilizes a power source for battery charging. The battery is used as an inverter voltage source to turn on the AC load. For that, a Charger Controller is needed which is useful for charging the battery. The DC voltage source coming from the generator is stored using a battery and then goes to the inverter to be converted into AC voltage. In this study, automatic charging of two batteries was used or can be called automatic charging. The way this circuit works is when the battery is full, the charger will automatically stop. The voltage indication during the charger process is 11 Volts and stops when the voltage reaches 14 volts. The use of two batteries in the charger process can work alternately, if battery 1 is full then battery 2 will charge automatically, and vice versa.

IEZ-Source Inverter Topology with Tuned PID Controller of Carrier SPWM Technique in Grid Connected System

Z-source inverters are used in controller applications, which offer higher performance than the buck-boost converter. This work presents the Improved Embedded Z (IEZ)-source inverter used for the impedance network. The Z-source inverter includes the switching topologies, so the double inductor is added to the EZ source inverter circuit. IEZ source inverter manages the Total Harmonic Distortion (THD), and the PID controller controls the inverter voltage. The Social Ski Driver (SSD) Optimization algorithm is used to tune the parameters of the PID controller. The harmonic content of the Z-source inverter is reduced by the carrier based sinusoidal Pulse Width Modulation (SPWM) technique. The Improved Embedded Z-source Inverter (IE-ZSI) is utilized to apply a grid-connected system. The inverters receive the power from the DC voltage and supply the grid-connected load with controllable voltage. The proposed work is implemented in the platform MATLAB/SIMULINK to evaluate the performance of the voltage across the capacitor, the voltage across the inductor, grid current and grid voltage. Inverter DC link voltage performance was compared to conventional Z-source inverters and embedded Z-source inverters. The proposed work achieved 1.52% THD compared with existing techniques.

Disturbance Observer-Based Feedback Linearized Controller for Grid-Forming Four-Leg VSI Supplying Unbalanced and Nonlinear Loads

This paper presents the design of a disturbance observer-based controller that regulates the output voltage of three-phase four-leg voltage source inverters (VSIs) deployed for grid-forming operation in Renewable Energy-based Distributed Generation (REDG) Systems. The primary objective of the controller is to provide a symmetric and sinusoidal voltage at the output of the VSI when supplying highly unbalanced and nonlinear loads. The controller employs the feedback linearization (FL) technique and incorporates a disturbance observer (DO) to address a range of disturbances that include oscillations resulting from unbalanced loads, harmonics generated by nonlinear loads, and non-oscillatory disturbances. Notably, the controller adopts a direct control scheme without the need for nested current control loops and does not use any transformation frames. Simulation studies and experimental investigations were conducted to assess the controller’s performance under various load conditions, including both linear and nonlinear types, as well as load transients. The findings demonstrate the controller’s capability to accurately track references while complying with the IEEE power quality standards for the tested conditions.

Stabilized voltage source inverter for sensitive loads in nuclear installations

The present paper proposes a novel design of a stabilized single-phase voltage-source inverter with pure sinusoidal output voltage for photovoltaic systems employed for feeding sensitive loads in nuclear installations. Such types of loads require a voltage source with quite stabilized magnitude and frequency and pure sinusoidal shape that is free from higher-order harmonics. The inverter is based on an H-bridge four insulated gate bipolar transistors (IGBTs) with gate drivers and optocoupler isolators. A control system based on a fast DSP unit and a microcontroller is designed for cancelation of the higher-order harmonics to produce a pure sinusoidal output with almost zero total harmonic distortion (THD). The sinusoidal purity, frequency and magnitude stabilization are achieved through pulse width modulation (PWM) controlled by a fast-response feedback system that measures the time wave form of the output voltage applied to the load and then calculates the THD, frequency and amplitude. The sinusoidal shaping is performed with aid of a sinusoidal shaping filter (SSF) to fasten the operation of higher-order harmonic cancellation. The frequency measurement is achieved through a frequency counter whereas the amplitude measurement is carried out through a differential amplifier that amplifies the difference between the output voltage of the inverter (while being applied to the load) and reference voltage that determines the desired amplitude. A prototype of the entire system of the proposed voltage-source inverter is fabricated for experimental evaluation of its performance. It is shown through simulation and experimental work that the proposed control system of the inverter output voltage is able to stabilize both the amplitude and frequency of the voltage applied to the load irrespective of the load impedance. Also, it is shown that the THD of the output voltage is -57dB\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$-57 \ ext{ dB}$$\\end{document} (0.00025%\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$0.00025 \\%$$\\end{document}), which is almost zero. Moreover, the switching losses are considerably reduced and can be negligible owing to the use of the appropriate IGBTs. The efficiency of the proposed inverter is obtained by simulation taking into account all types of losses. Also, the dependence of the inverter efficiency on the load current is investigated. The average efficiency of the proposed voltage-source inverter is shown to be higher than 97%\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$97\\%$$\\end{document}.

Harmonic Self-Compensation Control for Bidirectional Grid Tied Inverter Based on Crown Porcupine Optimization Algorithm

A self-compensating control strategy for harmonic parameters based on the crown porcupine optimization algorithm is proposed for the single-phase rectifier and two-phase inverter operation mode of the bidirectional converter. In order to improve the response speed of the inverter voltage, the instantaneous expressions of the phase angle coefficient and amplitude coefficient of the dc-side voltage doubling fluctuation are derived, and the third harmonic is calculated based on the crown porcupine optimization algorithm according to the Proportional Integral (PI) + Quasi-Proportional Resonance (QPR) double closed-loop control method and injected into the input voltage of the inverter side to offset the influence of the bus-doubling fluctuation on the output voltage of the two-phase inverters of B and C so that the total harmonic content of the two-phase output voltages of the two-phase inverters of B and C can be reduced. The total harmonic content of the B and C inverter output voltages is reduced. The effective control of the control method for single-phase rectifier two-phase inverter mode is verified through simulation. Finally, the effectiveness of the control strategy is verified by experimenting with a 15 kW LCL-type bi-directional converter prototype.

Fundamental frequency switching strategies of a seven level hybrid cascaded H-bridge multilevel inverter

This paper presents a novel hybrid cascaded H-bridge multilevel inverter (HCHB MLI) designed to address the growing importance of multilevel inverters in the context of renewable energy sources such as solar, wind, and fuel cells. The proposed topology features eight insulated-gate bipolar transistor (IGBT) switches and utilizes two distinct input direct current (DC) sources: a battery and a capacitor, making it a hybrid system. The control strategy employed in this topology is based on fundamental switching frequency techniques. Simulation results of the proposed topology are conducted using MATLAB/Simulink software, while hardware experimentation with a single-phase H-bridge inverter is also demonstrated in the paper. For pulse generation and IGBT switch control, an Arduino UNO microcontroller is utilized. The output voltage of the single-phase H-bridge inverter is verified through experimentation using a cathode-ray oscilloscope (CRO).

A novel hybrid-fuzzy logic based UVC technique for solar-PV/grid integrated water-pumping system

The continual depletion of fossil fuels and increased green-house emissions are persuading the consumers to install micro-renewable energy sources-based water pumping system. Among numerous energy sources, the solar-PV plays a significant role in water pumping application due to its virtuous, environment friendly, noise-free and abundant nature, so on. Along with solar-PV, the grid integrated system enables the continuous operation of water pumping system during varying temperature and irradiance conditions, and also delivers available solar-PV energy to grid during non-functional of pumping system. The above operations are carried by using bidirectional inverter which is controlled by using unit-vector control (UVC) technique. It consists of proportional-integral controller, which is not suited for regulation of DC-link voltage at desired level because of improper selection of gain values. In this work, an intelligent hybrid-fuzzy logic based UVC technique evidences the intelligent knowledge base for better regulation of DC-link voltage and power-flow of bidirectional inverter. The performance and operation of proposed hybrid-fuzzy logic control UVC technique for solar-PV/Grid integrated water-pumping system is evaluated under various operating cases by using MATLAB/Simulink tool; simulated results are conferred with superlative comparisons.