Pulse Width Modulated Voltage Source Research Articles

Enhancement of Voltage Regulation and Transient Stability of Six Phase STATCOM using Decoupled Current Control Strategy

STATCOM is used in a six-phase transmission system to improve voltage regulation and transient stability. Six-phase pulse width modulated voltage source converters are used in the design of STATCOM, and a decoupled current control approach is used to operate it. The voltage references used by the voltage source converters' pulse generator are produced using a decoupled control method. This control technique allows for the decoupling of the coupling effect or the dependence of the d and q currents on one another, which improves system performance under unusual and abnormal conditions. By using the pulse generator of voltage source converters, the inner current control loop and the outer voltage control loop are intended to produce the necessary reference voltages. Simulation results are presented using MATLAB/SIMULINK to check efficacy of proposed six phase STATCOM.

Power quality improvement by using photovoltaic based shunt active harmonic filter with Z-source inverter converter

Introduction. The major source of energy for a long time has been fossil fuels, however this has its drawbacks because of their scarcity, exhaustibility, and impossibility of reusing them. Presently, a shunt active harmonic filter-equipped two-stage solar photovoltaic system is showing off its performance shunt active harmonic filter. The global power system has been impacted by current harmonics during the most modern industrial revolution. Novelty. The proposed work is innovative, by adopting the hysteresis modulation mode with Z-source inverter to enhance the performance of the system. Furthermore, the shunt active harmonic filter also get assists in this system for better improvement in the quality of power. Purpose. By incorporating an impedance source inverter and a photovoltaic shunt active harmonic filter methods, harmonic issues are mitigated. Methods. Load compensation is one of the services that the shunt active harmonic filter offers, in addition to harmonic compensation, power factor correction, and many other functions. The current pulse width modulation voltage source inverter method is more expensive, requires two converters owing to its two-stage conversion, has significant switching losses, and has a low rate of the reaction. The new model, in which the voltage source inverter is substituted out for a Z-source inverter converter, has been developed in order to address the problems of the existing system. Results. Rather than using a hybrid of DC-DC and DC-AC converters, the suggested system uses a shunt active harmonic filter that is powered by a photovoltaic source using a Z-source inverter. Utilizing Z-source inverter helps to address the present issues with conventional configurations. Practical value. By using software MATLAB/Simulink, this photovoltaic shunt active harmonic filter technique is analyzed. Shunt active harmonic filter, which produces compensatory current from the reference current obtained as from main supply, is powered by the photovoltaic array.

Broad Comparison of Multilevel Inverter Topologies Operating in Hostile Environments: DC Transmission Applicability and Feasibility

Especially in the mining industry, pulsewidth modulation voltage source converters driving induction motors located far away are often present. In this case, due to the long cable used for the converter-to-motor connection, several unwanted high-frequency phenomena are generated. In this context, a new configuration for motor drive systems was proposed, in which the rectifier is kept in its original position and the inverter bridge is installed close to the motor terminals, being the long cable used as a dc transmission line. Since this environment is always more hostile and can compromise the inverter lifetime, new concerns regarding the system reliability arise, despite the various technical-economic advantages of this new configuration. In this way, this article presents a comprehensive comparison of commercially widely accepted multilevel inverter topologies, searching for the best technical features for the aforementioned dc transmission applicability/feasibility. Simulations were performed assessing several essential quantities/indexes, with a major focus on reliability. Then, a discussion was made seeking those sets that could minimize the implementation costs and improve the system reliability, concerning the insulated gate bipolar transistor (IGBTs) and the metalized film and aluminum electrolytic capacitors of the dc link.

Mitigation of voltage sag in a distribution system during start-up of water-pumping motors using superconducting magnetic energy storage: A case study

Voltage sag represents one of the most significant features of power quality in operation of distribution systems. The voltage sag throughout the distribution system caused by simultaneous start-up of water-pumping motors represents a problem, which negatively affects the power quality of the distribution system. The present research work investigates mitigation of voltage sag in a real Egyptian distribution system during simultaneous start-up of many connected water-pumping motors by using superconducting magnetic energy storage (SMES) unit. This calls for a transient analysis of the real distribution system using MATLAB package in order to follow up the temporal variation of the system voltage-profile during motors' start-up. A fuzzy-logic (FL) control strategy of SMES unit is adopted to compose of cascaded control a six-pulse pulse-width modulation (PWM) voltage source converter (VSC) and two-quadrant DC-DC chopper. The proposed fuzzy logic controller (FLC) of SMES unit employs the bus voltage variation and the variation of SMES current as input signals to control the power transfer between the distribution system and SMES. The effectiveness of the proposed FL-controlled SMES unit is validated in a case study of a real distribution feeder named Karot distribution feeder loaded by 16 water-pumps driven by induction motors as well as residential loads. The feeder is part of a distribution system serving the Unified Egyptian Electrical Network. The obtained results indicate that the SMES unit successfully mitigated the voltage sag in Karot distribution feeder due to simultaneous start-up of connected water-pumping motors where the voltage never drops below 0.9 pu.

Pulse width modulation voltage source deadtime effect on partial discharge and lifetime of inverter‐fed motor insulation

This paper analyses the impact of square wave pulse voltage deadtime on the partial discharge (PD) and the lifetime of turn-to-turn insulation. A bipolar repetitive pulse voltage with a deadtime of 0–10 μs is produced using double half-bridge solid-state switches having push–pull technology controlled by a field-programmable gate array. The mechanism of the discharge process at rising and falling edges of the pulse voltage before and after deadtime is analysed in detail. The discharge amplitude and PD probability at the rising/falling edges of the voltage waveform increase as the deadtime increases from 0 to 10 μs due to the remanent charges. The number of PD and their intensity is higher at the first rising/falling edges of pulse voltage as compared to the second rising/falling edges for all deadtimes 0–10 μs. As the deadtime increases beyond 2 μs, the number of PDs increases and concentrates at a specific phase angle of rising/falling edges. These localise discharges degrade the insulation material and reduce its lifetime. This study helps to identify the inverter-fed motor insulation faults due to deadtime. It can provide guidelines to motor insulation designers to determine the limit value of deadtime to compensate PD and ensure the safer operation of such motors.

Modeling & implementation of DRLA based partially shaded solar system integration with 3-ϕ conventional grid using constant current controller

Renewable Energy Resources (RERs) are widely used on the concern of global environment protection. Solar energy systems play an important role in the generation of electrical energy, remarkably minimize the utilization of nonrenewable fuel sources. Solar energy can be extracted and transformed into electrical energy via solar photovoltaic process. Several traditional, soft computing, heuristic, and meta-heuristic maximum power point tracking (MPPT) techniques have been developed to extract Maximum Energy Point (MEP) from the solar photovoltaic modules under different atmospheric conditions. In this manuscript, the combination of reinforcement learning algorithm (RLA) and deep learning algorithm (DLA) called deep Reinforcement Learning Algorithm based MPPT (DRLAMPPT) is proposed under partial shading conditions (PSC) of the solar system. DRLAMPPT can deal with continuous state spaces, in contrast to RL it can be operated only with discrete action state spaces. In this proposed DRLAMPPT, deep deterministic policy gradient (DDPG) solves the problem of continuous state spaces are involved to reach the GMEP in photovoltaic systems especially under PSC. In DRLAMPPT, the representative's strategy is parameterized by an artificial neural network (ANN), which uses sensory information as input and directly sends out control signals. This work develops a 2 kW solar photovoltaic power plant comprises of a photovoltaic array, DC/DC step-up converter, 3-Φ Pulse Width Modulated Voltage Source Inverter (PWM-VSI) integrated with conventional power grid using Constant Current Controller (CCC Effectiveness of the proposed DRLAMPPT with CCC can be validated through an experimental setup and with MATLAB. Simulation and tested at different input conditions of solar irradiance. Experimental results prove that, in comparison to existing MPPTs, suggested DRLAMPPT not only attains the best efficiency and also adopts the change in environmental conditions of the photovoltaic system at a much faster rate and able to reach the GMEP within 0.8 s under PSC. Experimental and simulation results also prove that suggested CCC with LC filter makes the inverter output voltage and the grid voltage are in phase at the lower value of THD i.e. 1.1% and 0.98% respectively.

A Novel High Power Hybrid Rectifier With Low Cost and High Grid Current Quality for Improved Efficiency of Electrolytic Hydrogen Production

This letter proposes a novel three-phase hybrid rectifier topology and control method for high power electrolytic hydrogen production application. It is composed of a primary rectifier, i.e., a six-pulse silicon controlled rectifier (SCR) and an auxiliary converter, including a pulsewidth modulation (PWM) voltage source converter and a phase-shift-full-bridge converter. SCR undertakes most of the power consumed by electrolysis cell, and the auxiliary converter can compensate dc current ripples and absorb ac current harmonics of primary rectifier simultaneously. Compared with high power PWM rectifier, the proposed hybrid rectifier can keep the main benefits of PWM rectifier, such as the low dc current ripple to realize improved efficiency of electrolytic hydrogen production and high grid current quality at ac side while significantly reducing the cost. The effectiveness of the proposed hybrid rectifier is verified by the simulation as well as experimental results.

Fast Calculation of Electromagnetic Forces in IPMSMs Under PWM VSI Supply Based on Small-Signal Time-Harmonic Finite Element Method

This paper introduces a novel method for fast calculating the electromagnetic forces in interior permanent magnet synchronous machines (IPMSMs) under pulse width modulation (PWM) voltage source inverter (VSI) supply based on the small-signal time-harmonic finite element analysis (THFEA), which has been successfully utilized for fast calculating the PWM-induced losses in silicon steel sheets and permanent magnets. Based on the small-signal THFEA, the functional relationships between high-frequency harmonic voltages (HFHVs) and corresponding airgap flux densities are established, which are used for calculating the flux density spectra caused by each HFHV in the PWM voltage spectra. Then, the superposition principle is applied for calculating the flux density spectra caused by fundamental currents and all HFHVs, which are converted to the electromagnetic force spectra at last. The relative errors between the force density spectra calculated with the proposed method and those obtained from traditional time-stepping finite element analysis (TSFEA) using PWM voltages as input are within 3.1%, while the proposed method is 24 times faster than the traditional TSFEA.

Harmonics Mitigation of a Solar PV-Fuel Cell Based Microgrid System using a Shunt Active Power Filter

The increased penetration of distributed energy resources is inspiring the entire design of conventional electrical power systems. A Microgrid (MG) includes distributed generation, loads, energy storage, and a control system capable of operating in grid-connected mode and/or island mode. The power quality (PQ) issue is one of the main technical challenges in an MG power system. To improve PQ, it is necessary to analyze the harmonic distortion of the system. Moreover, harmonic distortion in MG networks has significantly reduced PQ, affecting the stability of the system. The shunt active power filter (SAPF) has been extensively used to diminish the current harmonics and verified as being the best solution. Hence, in this paper, the impact of PQ issues in an adopted standalone MG system (comprising solar and fuel cell based renewable energy sources) is investigated in the presence of SAPF. The SAPF is realized using a conventional synchronous reference frame (SRF) technique for current generation with a pulse-width modulation voltage source inverter technique to generate pulses for the inverter along with a PI controller to regulate the DC-link capacitor voltage. The proposed model is developed in MATLAB/SIMULINK and the results validate the superiority of the proposed technique over others in terms of harmonic elimination.

Performance Analysis of High-Speed Electric Machines Supplied by PWM Inverters Based on the Harmonic Modeling Method

This paper presents a method for the performance analysis of high-speed electric machines supplied with pulse-width modulated voltage source inverters by utilizing a fast analytical model. By applying a strict mathematical procedure, effective expressions for the calculation of rotor eddy current losses and electromagnetic torque are derived. Results obtained by the approach suggested in this study are verified by the finite element model, and it is shown that the proposed method is superior in comparison to the finite element method in terms of computation time. The proposed method enables fast parameter variation analysis, which is demonstrated by changing the inverter switching frequency and electric conductivity of the rotor and analyzing the effects of these changes on rotor eddy current losses. The presented work separately models effects of the permanent magnet and pulse-width modulated stator currents, making it suitable for the analysis of both high-speed permanent magnet machines and high-speed induction machines.

Optimal Management Energy System and Control Strategies for Isolated Hybrid Solar-Wind-Battery-Diesel Power System

This paper proposes optimal control strategies of a standalone Hybrid Power System (HPS) to supply sustainable and optimal energy to an isolated site with improved quality of electrical energy. A topology of Isolated Hybrid Power System (IHPS) is proposed, consists of: a Photovoltaic System (PVS), a Wind Energy Conversion System (WECS), electronic power devices controlled to maximize energy production from renewable sources and to maintain the constant DC-link voltage, a Battery Energy Storage System (BESS), Diesel Generator (DG), and a Pulse Width Modulation (PWM) Voltage Source Inverter (VSI) located at the load-side end. In addition, a novel control strategy has been proposed, in this work, to maximize the power from the PVS. This presented strategy, based on the combination between Perturb and Observe (P&O) algorithm and the Fuzzy PI Controller (FPIC), presents a good performance, especially in the dynamic state compared to the classical algorithm P&O. A supervisory control algorithm has been elaborated to manage the energy flows between the devices of the hybrid system to make the decision of the optimal operating mode in order to ensure a continuous supply of the load with minimum usage of batteries and DG. The simulation results developed in the Matlab/Simulink environment are applied to show the efficiency and performance of the proposed control strategies in terms of power optimization and energy management. Doi: 10.28991/esj-2021-01262 Full Text: PDF

Characterization of three phase solid state VAR compensation scheme in three phase pulse width modulation voltage source inverter

The principle of a three phase solid state VAR compensation (SSVC) system that uses a three-phase pulse width-modulated (PWM) Voltage-Source Inverter (VSI) is presented and analyzed. The proposed SSVC system can compensate for leading and lagging displacement power factor and the PWM is used as a means of reducing the size of reactive components. The significant aspect of the presented VAR compensator is the adjustment of the angle difference between the static fundamental circuit output voltage and the utility supply voltage in order to optimize the alternating current (a.c.) power factor to a non-linear load. The SSVC system is analyzed under self-controlled DC bus voltage operating conditions. Other areas of investigation include the design of SSVC reactive components. The dynamic analysis is carried out in a d-q reference frame to verify the performance of the VAR compensator in terms of speed of response and stability. Analysis and stability plots generated confirm a high performance static VAR compensator. Finely, the findings of present research work were found within good agreement with some other workers.

Performance Improvement of a Distributed Generation System Using Unified Power Quality Conditioner

This paper deals with performance improvement of a distributed generation (DG) system using unified power quality conditioner (UPQC). Despite of the several benefits of DG like excellent energy supply, reducing expansion of power distribution system, environmental friendly and so on, there are several challenges existing due to the integration of DG with the grid or operating it in standalone mode. Power quality (PQ) issue is one of the main technical challenges in DG power system. Moreover, harmonic and voltage sag compensation in a DG networks has significantly reduced PQ, which affects the stability of the system. Hence, in this paper, impact of PQ issues in an adopted standalone DG system (comprising of solar, wind and fuel cell based renewable energy sources) is investigated in the presence of UPQC. The realization of UPQC is carried out using conventional synchronous reference frame (SRF) and modified SRF (MSRF) techniques for reference current generation with pulse width modulation voltage source inverter technique for generation of pulses for the inverter along with a PI controller for regulation of DC-link capacitor voltage. The voltage sag compensation with current and voltage harmonics are estimated at different source (ideal and non-ideal) conditions with different control scheme like SRF and MSRF technique. The simulation model of conventional SRF and MSRF technique based UPQC is developed under MATLAB/SIMULINKR environment. The result obtained validates the superiority of proposed technique over others in terms of harmonics elimination and sag compensation.

Evaluation of the High Performance Indirect Field Oriented Controlled Dual Induction Motor Drive Fed by a Single Inverter using Type-2 Fuzzy Logic Control

In this paper, a high-performance indirect field-oriented controlled dual Induction Motor (IM) drive fed by a single inverter using type-2 fuzzy logic control will be presented. At first, the mathematical model of the IM is implemented in the d-q reference frame. Then, the speed control of the Dual Induction Motor (DIM) operating in parallel configuration with Indirect Field Oriented Control (IFOC) using PI and type-2 Fuzzy Logic Controller (T2-FLC) will be presented. For the control of this system, a DC supply and a Space Vector Pulse Width Modulation (SVPWM) voltage source inverter are introduced with constant switching frequency. Also, the performance of T2-FLC, which is based on the IFOC, is tested and compared to those achieved using the PI controller. The simulation results demonstrate that the T2-FLC is more robust, efficient, and has superior dynamic performance for traction system applications.

Modeling and analysis of a single-phase fractional-order voltage source pulse width modulation rectifier

A fractional-order voltage source pulse width modulation (PWM) rectifier (FOVSR) is that a voltage source PWM rectifier (VSR) with fractional-order inductors (FOIs) and fractional-order capacitors (FOCs). This paper deals with the modeling and analysis of a single-phase FOVSR, aiming to extend the single-phase VSRs from integer-order domain to fractional-order domain, and to reveal the influence mechanism of the FOI and the FOC on the operating characteristics of a single-phase FOVSR. Firstly, the model of a single-phase FOVSR is established based on the Caputo fractional calculus. On this foundation, the alternating current (AC) side steady-state operating characteristics are presented in detail by applying phasor analysis. Then the instantaneous power and secondary ripple expressions are derived. Additionally, the changing laws of the PWM operating waveforms of the AC side and the direct current (DC) side are analyzed. In order to control the operation of a single-phase FOVSR, a fractional-order proportional-integral-differential (FOPID) based dual closed-loop transient current controller is proposed. Finally, theoretical analysis is favorably verified by digital simulations. Compared with a single-phase integer-order VSR, a single-phase FOVSR presents more flexible and diversified operating characteristics, and it can operate in a wider range with good dynamic and static performance.

Electromagnetic Characteristic Analysis of High-Speed Motors With Rare-Earth and Ferrite Permanent Magnets Considering Current Harmonics

In general, permanent magnet (PM) motors are driven by a pulsewidth modulation (PWM) voltage source inverter for vector control. The generated PWM signals cause high-frequency voltage components at the carrier frequency. Such components can increase the electromagnetic losses, thereby necessitating the consideration of the phase current corresponding to the carrier harmonics. This study aims to examine the feasibility of high-speed PM motors in which rare-earth magnets are replaced with ferrite magnets, by considering the current harmonics. The electromagnetic characteristics of a high-speed motor with rare-earth and ferrite PMs were analyzed considering the current harmonics. Based on the existing rare-earth magnet model, a ferrite magnet model with the same performance was developed to perform a comparative analysis. The findings were validated via comparison with the experimental results of the manufactured models.

Carrier Electromagnetic Vibration of DC Voltage Fluctuation in Permanent-Magnet Synchronous Motor With Distributed Winding

In this article, we evaluate the noise and vibration in a permanent-magnet synchronous motor (PMSM) with distributed winding driven by voltage source pulsewidth modulation (PWM) inverters. Although the PMSM is a widely used device in a variety of fields, it tends to generate electromagnetic noise and vibration due to the PWM inverters. We describe the frequency of the electromagnetic vibration to estimate the worst point of the carrier electromagnetic vibration of dc voltage fluctuation. The PWM voltage harmonics and the modulation degree of dc voltage fluctuation were investigated through a theoretical analysis of the PWM voltage harmonics. It was found that a modulation degree near 0.56 was the maximum point of the doubled component of the carrier frequency $2f_{c}$ . Compared with the dc voltage fluctuation at this point, the dominant component of the PWM voltage harmonics was near frequency $f_{c}$ at a lower voltage and near frequency $2f_{c}$ at a higher voltage. These tendencies of the carrier electromagnetic vibration of dc voltage fluctuation are also verified in an experiment.

Cascaded controller for a standalone microgrid‐connected inverter based on triple‐action controller and particle swarm optimisation

In this study, power quality (PQ) improvement has been addressed, in the form of total harmonic distortion (THD) minimisation, as well as, voltage regulation using two cascaded schemes. The first scheme is the optimised triple action controller (TAC)-based pulse width modulated voltage source inverter. TAC consists of a proportional resonant controller, selective harmonic compensator, and a new added current-assisted feed forward controller. The second scheme is the optimised cascaded dual-level control of a standalone microgrid. Cascaded level control consists of droop, secondary, and synchronisation control loops. The two approaches have been optimised for best parameter selection out of the possible solution space using a particle swarm optimisation algorithm to satisfy the study objectives. The optimisation objectives/constraints were to minimise THD and minimise overshoot/undershoot, rise time, and steady-state error for voltage compensation under two disturbance scenarios, sudden load change, and voltage flicker injection as a power frequency disturbance. These research results have been compared to other existing simulation and experimental work. The results proved to be better in output voltage, frequency, response time, and THD. Furthermore, the proposed schemes ensure power factor improvement, high efficiency, overall system PQ, and reliability at various load conditions.

Design, Analysis, and Impacts of Sinusoidal LC Filter on Pulsewidth Modulated Inverter Fed-Induction Motor Drive

Squirrel-cage induction motor (SQIM) fed by a pulsewidth modulated voltage source inverter (VSI) is subjected to voltage and current surges. It may cause additional losses in the motor, insulation failure, high bearing current, and electromagnetic interference. To mitigate these problems, sinusoidal LC filter is placed at the ac-side of the VSI. This paper proposes a new methodology to design the filter. In this method, the filter inductance is chosen based on the maximum ripple in the inverter ac-side current and the voltage drop across the filter inductor, and the filter capacitor is chosen based on the steady-state reactive power demand of the SQIM. The effects of the designed filter on the switch current, losses in the drive, temperature of the dc-link capacitor, dv/dt at the motor terminal, stator flux, and air-gap torque of the SQIM are discussed. The performance of the drive with the filters, designed by the proposed method and the standard method, are experimentally tested on a two-level silicon carbide VSI-fed SQIM and comparative analysis is carried out. The impact of the designed filter on the drive is also shown when the neutral point of the filter capacitors is connected with the mid-point of the dc link. The stability of the closed-loop controlled SQIM drive with the proposed filter, and simulation results are presented to verify its performance.

Parameters Uncertainty Immunization of Global Synchronous Pulsewidth Modulated VSIs With Round P&O Algorithm

This letter proposes a closed-loop scheme for global synchronous pulsewidth modulated voltage source inverters with round perturbation and observation (R-P&O) algorithm to immunize the parameters uncertainty, e.g., line impedance and filter impedance variation. In specific, the rms value of measured total current harmonics at point of common coupling will be periodically sent to each inverter as feedback signal using the low-cost narrowband communication system. Then, the inverters will assume the R-P&O scheme to correct the phase shift angles among pulsewidth modulation carriers for intentionally minimizing the total current harmonics. Doing so, the closed-loop scheme can achieve the expected performance even under the severe parameters’ variation. The experimental results verified the performance of the proposed method.