International Journal of Power Electronics (44 papers in press)
Analysis and Modeling of the Role of Temperature in the Static Forward Characteristics of an IGBT
by Boussouar Layachi, Morel Herve, Bruno Allard, Buttay Cyril
Abstract: To effectively simulate the electrical characteristics of an IGBT, it is necessary to have a good model for applications operating in a wide range of temperatures. A new model of the on-state forward characteristics of an IGBT was developed and validated in MAST language in static mode using the SABER simulator. A particular attention was given to temperature dependence, based on the physical analysis of semiconductor device regions and the use of local and physic-based relations. The model was compared to experimental results and to the standard Hefner model. The validation of the model shows a good agreement between measurements and simulation. A clear improvement in the accuracy of the onstate characteristic temperature dependence with the was obtained.
Keywords: IGBT; MOSFET; Modeling; Power semiconductor devises; Power transistors and Simulation.
Control strategy for single phase cascaded nine level inverter with sinusoidal pulse width modulation using LPC 1769 ARM Cortex-M3 microcontroller
by Biju Kunjuraman Nair, Rijil Ramchand
Abstract: The output voltage waveform of a conventional two level inverter is poor due to the presence of harmonics and hence produces power loss which reduces the efficiency of the system. The multilevel inverter is used to improve the voltage waveform by reducing the harmonics, as it synthesizes the output voltage waveform from several levels of input voltage. Thus as the number of voltage levels of multilevel inverter is increased, the harmonics are reduced and hence losses are minimized significantly. The paper describes the implementation of a single phase cascaded nine level inverter with multi carrier based sinusoidal pulse width modulation technique using a low power advanced microcontroller. The simulation of single phase cascaded nine level inverter is done with multicarrier sine PWM technique using MATLAB SIMULINK. Hardware implementation is done for the multicarrier sine PWM single phase nine level inverter using LPC 1769 ARM Cortex-M3 microcontroller. The results of both simulation and hardware implementation are analysed.
Keywords: multilevel inverter; sinusoidal PWM; level shifted sine PWM; cascaded H-bridge inverter; harmonics.
Grid connected wind Energy Conversion System Based on Finite-Set Model Predictive Control
by Ahmed Rashwan, Tomonobu Senjyu, Mahmoud A.Sayed, Youssef Mobarak1, Gaber Shabib
Abstract: Predictive control (PC) theory has been successfully used in a numerous industrial application. In this paper, controlling the torque of a squirrel cage induction generator (SCIG) based on maximum power point tracing (MPPT) in a grid connected wind turbine is presented. Improve the quality of the wind energy conversion system by reducing torque ripples in the SCIG is verified. A decoupled and rapid tracking performance of the reactive power injected to the grid is observed. Online optimization and the included system nonlinearities and restrictions of the proposed algorithm lead to high degree of reliability using only one PI controller. The proposed technique leads to high robustness of the system against the nature of the wind energy fluctuations. DC link voltage was kept constant during the dynamics of the systems. The overall simulation models have been implemented using MATLAB/SIMULINK software.
Keywords: Predictive control; squirrel cage induction generator; torque-power control; wind energy.
A Comarative Analysis of Artificial Neural Network and Synchronous detection Controller to improve power quality in Single Phase System
by PRATAP PUHAN, Pravat Ray, Gayadhar Panda
Abstract: This paper explores the effectiveness of neural network control technique to extract the source current references from the distorted waveform of load current. Artificial Neural Network control technique working under balanced Single phase voltage source conditions is implemented on the shunt active power filter along with unipolar pulse width modulation (U-PWM) , Proportional integral (PI) controller is used for generation of gate signal and regulation of direct current (DC) voltage of the voltage source inverter. The U-PWM technique is based on simultaneously comparing a triangular high frequency carrier signal with a slow-varying regulation signal. A comparative analysis is made between the results obtained in this technique and Synchronous detection technique, It is found that developed neural network controller is very much effective to enhance the power quality in a single phase system by minimizing the Toatal Harmonic Distortion to a level below IEEE-519. To validate the effectiveness of neural network controller , Experimental results are provided using d-space1104 which gives very encouraging results.
Keywords: Active power filter; Synchronous detection technique; Neural network Technique; U-PWM; d-SPACE1104.
Protecting Micro-Grids by A SVM Based Pattern Recognised Islanding Detection Approach and Optimal Placement of PID-FC Controller Using Hybrid ABC-APSO Algorithm
by Gundala Srinivasa Rao, Gattu Keseva Rao
Abstract: The penetration of Distributed Generations (DG) ensures the increase of demand for consistent, reasonable and spotless electricity facing with some design and operational challenges such as islanding and fault current. Several active and passive methods have been suggested in the past to detect islanding with the placement of fault current limiter (FCL) to reduce fault current. As they suffer from the large non-detection zone and a high cost due to the impedance of FCL. In order to overcome such issues we propose a novel Proportional-Integral-Derivative Fault Current Controller (PID-FCC) which is placed optimally by using a Hybrid Artificial Bee Colony with Accelerated Particle Swarm Optimization algorithm (ABC-APSO) to limit the fault current and a SVM based pattern recognising approach for islanding detection in micro-grids. The PID selects the optimal size of the FCC by means of its tuned parameters. The Experimental results shows that our proposed method optimally place the PID-FCC with reduced size and detects islanding with high accuracy.
Keywords: Islanding; Support Vector Machine (SVM); Fault current controller (FCC); Hybrid Artificial Bee Colony with Accelerated Particle Swarm Optimization (ABC-APSO) Algorithm.
Analysis, Design and Simulation of Three-Phase Active Power Filter with Series Capacitor Topology for Current Harmonic Compensation
by Nirav Pandya, Dr P. N. Tekwani, Vinod Patel
Abstract: This paper presents an active power filter with series capacitor topology for the application of harmonic current compensation in case of any three-phase nonlinear load. The proposed system consists of an LC passive filter connected in series with three-phase active power filter. The LC passive filter is tuned to 13th order harmonic frequency. The major portion of harmonic current generated by the nonlinear load is absorbs by the passive filter and active filter is used to improve the filtering performance of the system by providing compensation for the host of other higher order harmonics. The requirement of dc-link voltage of the active filter is very less in the presented scheme as compared to that of the standard voltage source type active power filter without any other passive filtering component. This resulted in significant reduction of cost and the power rating of the active power filter. Systematic analysis and design of various components of the proposed active filter are presented in this paper. The simulation analysis is carried out by using instantaneous active and reactive power (P-Q) theory. The simulation results verify the circuit configuration and filtering performance of the proposed active power filter with series capacitor topology. The proposed system can be an attractive solution for effective harmonic filtering.
Keywords: Active Power Filter; Active and Reactive Power; Analysis and Design; Passive Filter; Series Capacitor Topology; Total Harmonic Distortion.
Analysis, Design and Experimentation with a Four-Element Resonant Immittance Converter Topology as a Constant-Current Power Supply
by Saylee Koli, Mangesh Borage, Sunil Tiwari
Abstract: Resonant immitance converters (RICs) belong to a newly identified family of the resonant converters exhibiting unique characteristics with the help of which a voltage source can be converted to a current source and vice versa. Therefore, RICs are suitable for applications that demand a constant-current (CC) power supply. A fourth-order T-type RIC topology, T5, is analyzed in this paper. Detailed steady-state analysis using fundamental frequency ac analysis is presented providing a detailed insight into the converter characteristics. Analytical results have been used to derive closed-form expressions for calculating the component values and ratings following a converter optimization. The correctness of analysis is validated by developing and testing a 500 W, 109 kHz laboratory prototype converter.
Keywords: Resonant power conversion; dc-dc converters; resonant immittance converters; constant-current.
Design and Implementation of an Improved Tri-state Boost Converter with Optimal Type-III Controller
by Niraj Rana, ARNAB GHOSH, Subrata Banerjee
Abstract: Over the years, DC-DC switched mode power converters (SMPC) are playing important role for technological advancement. Good dynamic performance is the one of the important criterion for designing the closed-loop converters. But some DC-DC switching converters (such as Buck-Boost, Boost, Flyback etc.) have non-minimum phase problem due to a right-half plane (RHP) zero in their small-signal control-to-output transfer function. So, the converters experience poor dynamic performance due to presence of non-minimum phase problem. Tri-state Boost converter with PID controller can solve the non-minimum phase problem easily, but the dynamic response will not be satisfactory. In this work, an improved Tri-state Boost converter with gravitational search algorithm (GSA) based optimized Type-III controller is designed & fabricated in the laboratory. The comparison between closed-loop performances of conventional Boost converter and Tri-state Boost converter with classical (k-factor method) and optimal Type-III controllers have been presented in this work. The experimental results prove the efficacy of optimized controller for the proposed converters. The proposed control scheme based on optimized Type-III controller for Tri-state Boost converter is not found in any literature and is newly introduced in this paper.
Keywords: Switched-Mode Power Converter; Tri-state Boost Converter; Non-Minimum Phase System; Gravitational Search Algorithm (GSA); Optimal Type-III Controller.
Loss Minimization of Trapezoidal BLDCM Drive by UPFC based Optimal Switched Inverter
by Subhendu Bikash Santra
Abstract: This paper presents harmonics behaviour of phase current waveform of trapezoidal BLDC Motor Drive in 120
Keywords: Brushless DC (BLDC) motor;UPFC (Unified Power Flow Controller);Position sensor less control;loss minimization;Selective Harmonics Elimination (SHE).
Active Power Filter using a Novel Adaptive Fuzzy Hysteresis Current Controller
by Karuppanan PitchaiVijaya
Abstract: This paper presents a shunt Active Power Filter (APF) for mitigating harmonics and reactive-power compensation in the distribution system. The compensation process is based on Modified-Synchronous Reference Frame (Modified-SRF) control strategy that is different from conventional-SRF method. A simple and efficient unit vector calculation is used in the proposed Modified-SRF in lieu of phase locked loop for vector orientation that cancels the presence of harmonics and notches in the distribution system. The shunt active power filter is implemented with Voltage Source Inverter (VSI) and its switching pulses are generated through a novel Adaptive-Fuzzy-Hysteresis Current Controller (HCC). The adaptive-fuzzy-HCC calculates the hysteresis bandwidth effectively with the help of Fuzzy Logic Controller (FLC). This method reduces the switching power losses and improves the VSI performances for active filter substantially compared to fixed-HCC and adaptive-HCC. The shunt active filter system is validated through extensive simulation under both steady-state and transient conditions with different non-linear loads. Comparative assessments of conventional-SRF and modified-SRF reference current generator methods are carried out.
Keywords: Modified-Synchronous Reference Frame; Active Power Filters; Adaptive-Fuzzy-Hysteresis Current Controller; Harmonics.
Line Frequency Sine Modulation - A Novel Modulation Scheme for Multilevel Inverters and Its Application Towards Enhanced Illumination of Incandescent Bulb
by Rakesh Kumar, Deepa Thangavelusamy
Abstract: Several modulation schemes are proposed and implemented in
multilevel inverters (MLIs) to reduce the total harmonic distortion (THD) content
at its output. These schemes may be broadly classified in terms of switching
frequencies into fundamental switching frequency (FSF) modulation schemes and
high switching frequency (HSF) modulation schemes. This paper proposes a new
approach towards employing an FSF modulation scheme to reduce the THD at the
output of an MLI. It involves designing two matrices coined as inverter switching
characteristics (ISC) matrix and inverter operating modes (IOM) matrix. The
switching frequency depends on the line frequency of the MLI output. The
presented modulation scheme is implemented in an asymmetrical topology MLI.
An experimental setup is also carried for a maximum power rating of 200W.
The experimental results show the proposed modulation scheme has improved
the parameters of the inverters in terms of the output voltage, output current, THD content of voltage and current waveforms, output power and power factor. Thus
the presented modulation control scheme is found to improve the performance of
Keywords: Multilevel Inverter; Topologies; Modulation Techniques; Total Harmonic Distortion.
A Simplified and Generalised SVPWM Method Including Over Modulation Zone for Seven Level Diode Clamped Inverter - FPGA Implementation
by Bogimi Sirisha
Abstract: This paper presents simplified and generalized SVPWM technique for a neutral point clamped multilevel inverter of any level. This modulation technique provides a simplistic strategy for transition between various modulation indexes with linear transfer characteristic which provides a general solution for over modulation zone. The proposed technique is based on 60ᵒ co-ordinate system with all the computational work is carried out on-line, generating the desired switching states and their sequences through simplified expressions without any additional storage requirement. This modulation technique combines the concept of reference vector modification and on duration modification during over modulation zones. The performance of the proposed technique is tested through FPGA spartan3A processor experimentally for seven level diode clamped inverter. The simulation and experimental results are validated at various modulation indexes and are in well agreement with each other.
Keywords: FPGA; SVPWM; Neutral Point Clamped Inverter; modulation index .
Design and Implementation of a Speed Adaptive Flux Observer For The Induction Motor Using Sylvester Criterion
by Mihai Comanescu
Abstract: The paper presents the design and implementation of a flux and speed observer for the induction motor drive. The method employs an observer with linear feedback that yields the motor fluxes and also estimates the speed using an adaptive law. The convergence conditions are formulated based on Lyapunovs nonlinear stability theory. The gains of the observer are designed using Sylvester criterion. The method proposed is reasonably simple and yields a series of inequalities that provide insight into the design choices and stability margins of the observer. The paper shows that the observer is not globally stable however, with proper design of the adaptation gains, it can be made locally stable. The observer with the corresponding adaptive speed estimate does not perform during low speed regeneration - the speed estimate diverges; to solve this issue, the paper shows a modified adaptation law that yields a stable speed estimate.
Keywords: induction motor control; flux estimation; speed estimation; rotor position estimation; Lyapunov stability theory; adaptive control; sensorless control.
Selective Harmonics Elimination for Three-Phase Seven-Level CHB Inverter Using Backtracking Search Algorithm (BSA)
by Sourabh Kundu, Arka Deb Burman, Santu Kumar Giri, Sarbani Mukherjee, Subrata Banerjee
Abstract: This paper introduces backtracking search algorithm (BSA) to solve the nonlinear transcendental equations to obtain triggering angles of a three phase seven-level cascaded H-bridge (CHB) inverter and also eliminates 5th and 7th order harmonics while satisfying the requested fundamental component. A comparative study has been made in terms of execution time, the statistical probability of achieving global minima, and a rank of convergence rate to establish the supremacy of the BSA optimization technique over other recognized methods such as genetic algorithm, bee algorithm, and particle swarm optimization techniques. Simulation and experimental results confirm the effectiveness and accuracy for obtaining precise switching instants that fruitfully satisfy the required output voltage quality.
Keywords: backtracking search algorithm (BSA); bee algorithm (BA); cascaded H-bridge (CHB); genetic algorithm (GA); particle swarm algorithm (PSO); selective harmonic elimination pulse width modulation (SHE-PWM).
Analysis of 4HSiC Schottky Barrier Diode with a Comb-Shaped Field Plate
by Dongwoo Bae, Chungbu Jeong, Taewan Kim, Kwangsoo Kim
Abstract: In this study, we have proposed a comb-shaped field plate for use in a 4HSiC Schottky barrier diode; this field plate was expected to improve the electric field distribution in the device and provide a higher breakdown voltage than conventional field plate structures. The main principle of the proposed structure is to distribute the inner electric field in the blocking mode through a stepped oxide structure formed by several trenches. The proposed structure was optimized using a simulation, and we fabricated and measured a number of devices to evaluate the performance of the proposed structure. The proposed devices breakdown voltage was 39% better than that of a SiC Schottky barrier diode containing conventional field plates.
Keywords: 4H-SiC; wide band gap; power device; trench oxide; edge termination; field plate; electric field crowding; electric field distribution; breakdown voltage; impact ionization.
A New Reduced Switch Count Three Phase Multilevel Inverter
by GEETHA Ramanujam, Ramaswamy M
Abstract: The paper develops a new multilevel inverter (MLI) topology with a view to reduce the number of power switches in the passage of current to reach each level of the output voltage. The philosophy involves the use of bidirectional switches to avert the flow of circulating current between the two sections of the power circuit. The formulation brings in the use of a new pulse width modulation strategy to eliminate the higher frequency components of the output voltage. It incorporates the phase disposition type of modulating scheme to shape both the voltage and current to a nearly sinusoidal waveform. The total harmonic distortion indexed by smaller values for the output voltage over the traditional firing scheme serves to be the highlight for the MLI in acclaiming its place in the inverter world. The experimental results obtained using a prototype validate the simulated performance and establish the viability of the proposed MLI to serve the diverse needs of the utility world.
Keywords: Multilevel inverter; Total harmonic distortion; Phase disposition; Pulse width modulation.
Optimum Pulse-width modulation strategy for a symmetric cascaded Multilevel Inverter
by Ashraf Yahya, Syed M. Usman Ali
Abstract: This paper investigates for the most suitable PWM strategy for a symmetric cascaded Multilevel inverter. The objective is to determine a PWM switching strategy which optimizes inverter performance by ensuring higher DC link utilization and minimum Total Harmonic Distortion (THD) at low switching frequency to minimize switching power losses also. Simulations carried out in Matlab-Simulink environment has given an insight of inverter performance when carrier based PWM techniques are applied. In this parametric evaluation both odd and even multiples of 50 Hz modulating signal were applied for obtaining switching frequency for various Multicarrier based PWM strategies.
Keywords: Multilevel; inverter; carrier based PWM; modulation index; phase disposition; Inverted sine.
A Modular DC-DC Converter with Zero Voltage Switching Capability
by Farzad Sedaghati, Reza Haghmaram
Abstract: A bidirectional DC-DC converter with high power density is proposed in this paper. The presented converter provides power transfer in both directions only with adjusting phase shift angle. Zero voltage switching (ZVS) in both turn on and turn off moments of all switches is the major capability of the converter that makes it suitable for high power applications. ZVS of the converter is provided without any auxiliary devices. High frequency transformers are employed in the converter configuration to match the converter two sides voltage. Moreover, the transformer leakage inductance along with external auxiliary inductance acts as energy storage in power transfer from one side of the converter to the other side. Steady state operation of the converter is analyzed. ZVS criteria of the proposed converter are studied and finally, experimental measurement results of laboratory scale prototype are presented.
Keywords: DC-DC converter; modular converter; ZVS operation; high-frequency isolation.
A Comparative Closed-Loop Performances of a DC-DC Switched-Mode Boost Converter with Classical and PSO based optimized Type-II/III Controllers
by NIRAJ RANA, ARNAB GHOSH, SUBRATA BANERJEE
Abstract: The DC-DC switched-mode Boost converter is well-known for its extensive applications ranging from few watts to several megawatts in different engineering fields. In this paper, a closed-loop Boost converter has been designed and implemented by using classical and particle swarm optimization (PSO) based optimized Type-II/Type-III controllers. The closed-loop control for Boost converter is difficult due to presence of a right-half-plane zero, and it is problematic for the conventional PID controller to exhibit good closed-loop performance with line, load changes and parametric uncertainty. The comparative studies between the closed-loop performances of the proposed Boost converter with classical and optimized Type-II/Type-III controllers have been produced. Simulations & experimental results are provided to demonstrate the effectiveness of proposed optimized controllers for the Boost converter. It is found that the PSO optimized Type-III controller exhibits better stability & closed-loop performance than the others reported controllers in this paper.
Keywords: DC-DC Switched-Mode Power Converter; Boost Converter; Non-Minimum Phase System; Classical Type II/III Controller; Particle Swarm Optimization; Optimized Type-II/III; Simulation and Experimental Results.
Fuzzy-PI Controller Applied to PMSM Speed Controller - Design and Experimental Evaluation
by Hicham Fadil, Mohamed Larbi Elhafyani
Abstract: Several advantageous are offered by synchronous motors with permanent magnet (PMSM) which are required in numerous fields for high performance adjustable speed operation. However, PMSMs speed control is related to directly to controllers and it needs to be adjusted using an appropriate regulator. In this paper, a proportional integral (PI) regulator applied for PMSM speed adjusting is considered and enhanced using a Fuzzy logic process by making that PI regulator gains self-adapting and ensures a good performances of the controller in transient states. A PMSM motor controlled using an eZdsp F28335 board is exploited to validate MATLAB/SIMULINK software results, and to show Fuzzy-PI improvement and performance under many constraints.
Keywords: Fuzzy-PI regulator; Permanent magnet synchronous motor; PI controller; speed control.
Power Sharing Control Strategy of Parallel Inverters in AC Microgrid Using Improved Reverse Droop Control
by Chethan Raj D, Dattatraya N. Gaonkar, Josep M. Guerrero
Abstract: Microgrid structure is developed on the basis of distributed generation units. Microgrid distributed generation units and energy storage devices are connected through inverters interface to the point of common coupling. Micro-grid system with multiple inverters, the use of conventional direct and reverse droop control method will cause uneven distribution of power, which is due to the difference between the output impedance and the line impedance of the inverter. In this paper, the traditional reverse droop control method is introduced and the power distribution of inverter output impedance is analyzed, and the defects of traditional reverse droop control are pointed out. Adding virtual resistor in the control loop of reverse droop control improves the power sharing and stability of operation, but also leads to the voltage drop in microgrid. To compensate the output voltage deviation, secondary control is proposed. Simulation results show the correctness and effectiveness of the proposed control strategy.
Keywords: Droop control; reverse droop control; distributed generation; inverters; microgrid; output impedance; secondary control; virtual resistors.
Cascaded H-Bridge Inverter with Reduced Device Count Control Considering Harmonic Distortion Minimization
by Faouzi Armi, Lazhar Manai, Mongi Besbes
Abstract: In this paper, a serial/parallel cascaded H-bridge (CHB) multilevel inverter is presented. The topology has the advantage of reduced number of switching devices, DC-sources and gate driver circuits. Consequently cost and complexity are greatly minimized, providing the same number of output voltage levels even more compared to conventional structures and other topologies given in some recent literatures in which authors have proposed new topologies with reduced circuit devices count (RDC).
The main contribution of this work is the ability to choose a set of harmonic order to be eliminated; in other similar works PWM technique is only capable to minimize total harmonic distortion (THD) without eliminating selected harmonic which require a complex output filter.
The feasibility and effectiveness of the proposed topology is evaluated with intensive simulation study and experimentally tested on a prototype using a field-programmable gate array (FPGA) to implement N-R algorithm for inverter selective harmonic elimination (SHE) control.
Keywords: Serial/Parallel CHB multilevel inverter; Reduced Device Count; Newton Raphson algorithm; Switching angles; SHE; THD; FPGA.
Evaluation of level-shifted carrier PWM technique for neutral-point stabilisation of five-level DCMLI
by K. Narasimha Raju, O. Chandra Sekhar, M. Ramamoorty
Abstract: The persistent issue with diode-clamped multilevel inverter is unbalance in DC-link capacitor voltages. These variations become predominant at load power factor near to unity. Evolved techniques exist to balance capacitor voltages for three-level inverter. But for the inverters above three level, the problem still persists. In this paper, a novel level-shifted carrier pulse width modulation technique is proposed. As per this technique, carriers are level shifted based on the difference in capacitor voltage and phase currents. This leads to variation in duty cycle of the switches and thereby adjusting the charging and discharging of capacitors to balance capacitor voltages. The proposed technique is mathematically modelled and verified for five-level inverter using MATLAB SIMULINK.
Keywords: carrier-based PWM; DC-link capacitors; duty cycle; five-level inverter; load pf; neutral-point voltage balancing.
A three-phase current reconstruction technique using a single current sensor based on active vector pulse insertion
by Qian Xun, Xiaorui Guo, Boyang Xun, Peiliang Wang, Zhiduan Cai
Abstract: A single dc-link current sensor to reconstruct all three inverter phase currents has been proposed for the purpose of cost reduction and sensor fault tolerance in the motor drive. A novel phase current reconstruction scheme, with the immeasurable areas reduced, has been reported in the paper to tackle the problems caused by the presence of regions in the voltage vector plane where the phase currents are not directly measured. An active vector pulse insertion method achieves this objective by applying additional active voltage vectors in the brief intervals, and guaranteeing the invariant duty cycle in three-phase leg configuration during each fundamental frequency cycle. The effectiveness of the proposed reconstruction algorithm has been verified via a permanent magnet synchronous motor drive with 500 W rated power. Simulation and experimental results are provided to confirm the attractive performance characteristics of the resulting current reconstruction and regulation using the active vector pulse insertion method.
Keywords: active vector pulse insertion; current reconstruction; immeasurable area; invariant duty cycle; single current sensor.
FPGA implementation and analysis of model predictive current control for three-phase voltage source inverter
by K. Rameshkumar, V. Indragandhi, A. Sakthivel, K. Palanisamy
Abstract: A detailed investigation of the model predictive current control (MPCC) for a three-phase voltage source inverter (VSI) with an output RL filter is examined in this manuscript. The investigation on VSI and its operating conditions such as dynamic, steady state, transient state condition with balanced and unbalanced loads are explained. The parameter variations such as sampling time, filter inductance and DC-link voltage variations are also explained in terms of load current Total Harmonic Distortion (THD) and inverter switching frequency. During each sampling period, the discrete mathematical model of the system is used to predict the load current for all the inverter switching state. These predictions are estimated using cost function, and so, the switching state which gives minimum cost function is selected and applied to the inverter. The effectiveness of the control technique is verified in MATLAB software and also in real-time hardware setup using Xilinx XCS500E Spartan 3E FPGA board. The detailed simulation and hardware results are included to investigate the implementation.
Keywords: cost function; model predictive current control; sampling time (TS); THD; VSI.
Design and implementation of a MRAS sliding mode observer for the inverse of the rotor time constant of the induction motor
by Mihai Comanescu
Abstract: The paper presents an estimator for the inverse of the rotor time constant of the induction motor. Estimation is done using a sliding mode observer under the assumption that the stationary frame fluxes are known. With measured voltages, currents, and with known fluxes and speed, the paper develops an MRAS-type sliding mode observer. This works well under ideal conditions; however, if the speed is inaccurate or if the magnetising inductance saturates, the accuracy suffers. The paper develops a model for the saturated induction motor and attempts to also estimate the saturation level. In the second part, an observer with only a single set of feedback terms is developed. This is transformed into a sensorless observer by feeding it with a speed estimate (assumed inaccurate). The error in the estimated rotor time constant can be reduced by operating the motor drive with a low ratio of id to iq.
Keywords: induction motor control; model reference adaptive control; rotor time constant estimation; sliding mode observer; voltage model observer.
A comparative analysis of DFPI correctors and different techniques to regulate a shunt active power filter
by Nabil Elhaj, Hind Djeghloud, M. Brahim Sedra, Tarik Jarou
Abstract: Power quality is a subject of intense study over recent years, given that it affects the economic impact and costs of utilities, supply and manufacturing. Modern powered electronic equipment is usually nonlinear in nature and causes propagation of harmonic current. This disruptive current can be countered by various solutions, but active power filtering is the most captivating solution. In this paper, a Shunt Active Power Filter (SAPF) system is considered with a new corrector design for both the DC and AC sides. The new design is based on an association between double fuzzy logic and single PI correctors resulting in two 'DFPI' correctors devoted to regulating the DC voltage and the AC current of the SAPF. The DFPI corrector is more advantageous than the classic PI or fuzzy controllers implemented alone for regulation purposes of the SAPF control variables (DC voltage and the AC current). This is demonstrated, in this paper, through the addressed theoretical analysis of the proposed DFPI corrector and the studies shown in the simulation section comparing the proposed DFPI, single fuzzy, double fuzzy and PI controllers. Performances in terms of the filtering quality of the AC feeder side and the SAPF DC-bus voltage regulation quality (THDis%/THDVs%) are noted. The obtained numerical results prove the effectiveness of the DFPI corrector which also described a faster response time, a reduced overshoot and a lessened static error.
Keywords: DFPI-based control; intersective PWM modulator; power quality improvement; PSF algorithm; SAPF.
Optimising the performance of three-phase neutral-point clamped rectifier under disturbed AC mains
by Deepak Sharma, Abdul Hamid Bhat, Aijaz Ahmad
Abstract: In this paper, a novel simplified control technique is proposed to control three-phase neutral-point clamped bidirectional rectifier using optimised switching sequences for disturbed AC mains. In space-vector modulation (SVM) technique using optimised switching sequences, duty ratio and sampling periods in each region are very important. In other words, reference vector trajectory shape and the time spent by the reference vector in each region are very important to obtain exact switching under any supply conditions. With the use of optimised switching sequences, even under ideal supply conditions, it is depicted that source-side and load-side parameters deviate from acceptable limits, and a DC-bus capacitor voltage unbalance occurs. Under the influence of disturbed AC supply, source-side and load-side parameters deviate more beyond acceptable limits which cause a very large unbalance in DC bus capacitor voltages. This non-ideal performance of the converter is responsible for the deterioration of quality of source currents and a large stress on power semiconductor devices. A new algorithm is proposed in this paper to make the converter performance ideal even under ideal and non-ideal supply conditions. According to supply conditions, the proposed technique varies the speed of the reference vector and, also at the same time, forms a required trajectory while passing through the most effective regions of SVM hexagon. The proposed technique maintains parameters within acceptable limits for source side and load side in terms of unity power factor, low input current total harmonic distortion (THD), minimum switching losses and reduced-rippled, well-regulated DC-bus voltage and also at the same time DC-bus capacitor voltage balance. The simulation results are presented to demonstrate the effectiveness of the proposed control technique.
Keywords: DC-bus capacitor voltage unbalancing; disturbed AC mains; harmonics compensation; multilevel converters; neutral-point clamped converter; NPC converter; power quality; space-vector pulse width modulation; SVPWM.
Gbest-guided artificial bee colony algorithm based simultaneous placement of distributed generation and shunt capacitor in distribution networks
by Mukul Dixit, Prasanta Kundu, Hitesh R. Jariwala
Abstract: This paper presents a combined placement of distributed generation (DG) and shunt capacitor in distribution network for the purpose of power loss reduction. The locations of DG and shunt capacitor are evaluated by using power loss index approach and index vector method, respectively. The population based Gbest-guided artificial bee colony meta-heuristic optimisation technique has been implemented to evaluate the optimum size of DG and shunt capacitor simultaneously. This methodology is being demonstrated on 33-bus and 85-bus distribution network. In addition to that, the two load scenarios are considered in this study. The technical analysis has been carried out for different combinations of DG and shunt capacitor. Comparison between various cases for power loss, minimum system voltage, voltage stability index and total voltage deviation are also mentioned in this paper. The numerical results obtained through proposed approach have been compared to the published research papers for showing its effectiveness.
Keywords: distributed generation; GABC algorithm; index vector method; load model; optimization; power loss; power loss index; shunt capacitor; voltage deviation; voltage profile; voltage stability index.
An improved nearest-level modulation for modular multi-level converters
by Keli Li, Yong Liao, Ren Liu, Jimiao Zhang
Abstract: Voltage balancing and switching frequency reduction are common problems of modular multi-level converters. In this research article, an improved nearest-level modulation strategy, which applies fuzzy control and minimal switching frequency pulse pattern, is proposed to coordinate voltage balancing and switching frequency reduction. The performances of voltage balancing and switching frequency reduction can be regulated by changing the parameters of the fuzzy control and the weighting coefficients of the two parts. The simulations are implemented through a high-voltage direct current system which connects a wind farm. The simulation results validate the practicability of the proposed strategy.
Keywords: fuzzy control; high-voltage direct current; modular multi-level converters; nearest-level modulation; switching frequency reduction; voltage balancing.
Design of backstepping controller for PV-wind hybrid system with grid-interfacing and shunt active filtering functionality
by V.N. Jayasankar, U. Vinatha
Abstract: This paper presents the design of a double loop controller for the grid interconnection of PV-wind hybrid system with shunt active filtering and neutral current compensation capabilities. Using Lypunov stability theory-based procedure, a backstepping controller is designed for the outer loop DC link voltage control. The adaptive nature of back stepping controller results in better dynamic performance compared to conventional controllers. Inner loop consists of instantaneous power theory-based controller for harmonic current compensation. Instantaneous power theory is modified by employing positive sinusoidal sequence regulator and self-tuning filter to improve the system performance in unbalanced and distorted grid voltage conditions. A dynamic model of the system is considered for the design. Numerical simulations are done in MATLAB/Simulink platform for different system conditions to verify the effectiveness of controller in grid interfacing of renewable sources, and the shunt active filtering.
Keywords: backstepping control; DC link voltage control; grid connected renewable system; shunt active filter; wind-solar hybrid system.
An efficient islanding detection method in distributed generation using hybrid SVM-based decision tree
by Gundala Srinivasa Rao, Gattu Keseva Rao
Abstract: Islanding is one of the most important concerns of interconnecting the grid-connected distributed resources to the distribution system. At the point when a bit of the distribution system turns out to be electrically detached from the rest of the power system, yet keeps on being empowered by distributed generator (DG) islanding happens. Islanding is an undesirable circumstance, since it is conceivably a hazardous condition for the upkeep work force and might harm the DG and loads on account of unsynchronised reconnection of the lattice because of stage distinction between the grid and DG. So effective and accurate islanding detection is essential to protect the distributed system while landing occurs in a distributed network. In this paper, a hybrid support vector machine with decision-tree classifier is proposed to provide an accurate detection and classification of islanding based on extracted features within less detection time. The proposed method is actualised in MATLAB, and the test results demonstrate the significance and viability of our proposed system than the current islanding discovery strategies.
Keywords: DG; distributed generator; forward feature selection algorithm; islanding; support vector machine with decision tree.
An improved control strategy without current sensors for DSTATCOM
by Sanath Saralaya, K. Manjunatha Sharma
Abstract: An improved control strategy based on power balancing algorithm without using current sensors is presented in this paper. The mathematical model of this improved method is discussed. Point of common coupling (PCC) voltage and DC link voltage are taken as voltage commands for reference signal generation. Sinusoidal pulse width modulation is used to generate the pulses for distribution static compensator (DSTATCOM). Proportional integral (PI) controller is used to control the PCC voltage and DC link voltage of the voltage source converter of DSTATCOM. This improved method is tested for different load conditions using PSCAD/EMTDC package. The improved control strategy is validated by simulation results for linear and non-linear load conditions.
Keywords: distribution static compensator; PI controller; power quality; total harmonic distortion; voltage source converter.
Special Issue on: Advanced Power Electronic Systems for HVDC and DC Grids
Neural Network Based Three-Phase NPC Rectifier for DC Bus Capacitor Voltage Balancing Under Perturbed Mains Supply Conditions
by Deepak Sharma, Abdul Hamid Bhat, Aijaz Ahmad
Abstract: This paper presents an artificial neural network based modified space vector pulse width modulation control approach for better performance of three-phase Neutral-Point Clamped rectifier using optimised switching sequences.Use of optimised switching sequences even under ideal supply conditions, it is depicted that source side and load side parameters deviate from acceptable limits and a DC-bus capacitor voltage unbalance occurs. Under the influence of disturbed supply, source side and load side parameters deviate more beyond acceptable limits which causes a very large unbalance in DC bus capacitor voltages. This non-ideal performance of the converter is responsible for the deterioration of quality of source currents and a large stress on power semiconductor devices.The proposed control scheme employs a three-layer feed-forward neural networks at different stages for capacitor voltage balancing of a three-phase three-level neutral-point clamped converter with improved power quality. According to the supply conditions, the neural network varies the speed of the reference vector and forms a required trajectory while passing through the most effective regions of SVPWM hexagon. Proposed controller scheme is modeled in MATLAB/Simulink software. Simulation results show that the proposed implementation of neural-networks controller in three-Phase NPC converter displays better performance under ideal and disturbed mains conditions
Keywords: Power Quality; Improved Power Quality Converters (IPQCs); Multilevel Converters; Harmonics Compensation; Unbalanced AC Mains; Disturbed AC mains.
Analysis and Modelling of wireless battery charger
by IHSSEN JABRI, ADEL BOUALLEGUE, FETHI GHODHBANE
Abstract: Wireless battery charger system is considered as a multi parameter and multi constrained nonlinear system. The main objective of this work is to analyse the several blocks of the contactless charger and to refer to metaheuristic methods in performance optimization regarding to the impact of parameter selection during designing in order to find the best global solution. An improved PSO algorithm with a selection strategy based on the use of Euclidean distance method between two individuals chosen randomly to form the population is proposed. The convergence characteristic of the adopted algorithm has been introduced. Simulation results show that the improved method may instead the limit of the local optimum solution and get the global optimum solution faster. A robust optimizer algorithm called GODLIKE is involved to solve optimization problems and to take into account the interactions between design parameters on charger system performance. A perturbation-and-observation-based tracking method is developed through an efficient sensing system to act on the misalignment issue and the car position.
Keywords: Wireless battery charger; Coreless transformer; PSO; GODLIKE; perturb & observ.
Special Issue on: Advanced Power Electronics for Distributed Generation and Microgrids
The Optimal Configuration of the multistage model with embedded chance constraints of Mini-type Hydroelectric-Photovoltaic Power Distribution Networks on the Basis of the Improved Genetic Algorithm
by MengYu Wang, Ziwei Zhu, Hongquan Hu
Abstract: The grid-connection of mini-type hydroelectric, photovoltaic and other renewable energy sources has brought remarkable volatility and randomness to the system of power distribution network. But during the planning of that system, the comprehensive model of hydroelectric-photovoltaic planning model is rarely considered. This article brings forward multistage planning model with embedded chance constraints to address the issue of comprehensive planning of mini-type hydroelectric photovoltaic power distribution networks. Firstly, the multistage within different periods of time model which considers the sequence of the hydroelectric generator, the photovoltaic power generator and the capacitors was established. The objective functions of the three stages were respectively set as minimizing annual cost, minimizing transmission losses and abandoned water, and minimizing the times of the switching of transformer taps as well as of the switching of capacitors. Secondly, the objective function, the chance constraint of state variable and control variable and the constraint of the active and reactive power output of the hydroelectric generator, the photovoltaic power generator and the capacitors was comprehensively considered. After that, crossover model was introduced, in order to rectify the prematurity of genetic algorithm. Lastly, the form of IEEE 33-bus system can effectively enhance the utility of resources, reduce transmission losses and gross cost. The comprehensive model was also capable of keeping the voltage of the network stable and lower the times of adjustment of the transformers and the capacitors, improve the durable years of the facility.
Keywords: multistage model Mini-type Hydroelectric-Photovoltaic Improved Genetic Algorithm Optimal Configuration.
TSFLC Based DC Link Voltage Regulation of Grid Connected DC Micro Grid
by SHIKHA GUPTA, Rachna Garg, Alka Singh
Abstract: Abstract: Integration of micro grid with utility power network has major concerns such as active power control and maintaining desired power quality (PQ) standards. Among several power quality issues, voltage dip and harmonics are critical concerns impacting the overall performance and stability of system. In this paper, a grid connected DC micro grid (DCMG) is designed and controlled to ensure requisite power allocation between the micro-grid and utility grid system vis-
Keywords: Voltage Source Converter (VSC); DC Micro Grid (DCMG); Distributed Generation Source (DGs); Fuel Cell (FC); Photovoltaic cell (PV); Wind Energy System (WES).
Implementation and Performance Analysis of Cascaded Multilevel Inverter using Modified SVPWM Techniques
by Lokeshwar Reddy Chintala, Satish Kumar Peddapelli
Abstract: The Space Vector Pulse Width Modulation (SVPWM), which is considered as an efficient PWM technology can also be used for multilevel inverters. This method is originally designed for two-level inverters. This paper introduces a modified SVPWM technique. The cascaded H-bridge multilevel inverter (CMLI) of 7-level, 9-level and 11-level are simulated for three different carrier PWM techniques. Here, Carrier based Sinusoidal Pulse Width Modulation (SPWM), Third Harmonic Injected Pulse Width Modulation (THIPWM), and Modified Carrier-Based Space Vector Pulse Width Modulation (SVPWM) are used as modulation strategies. These modulation strategies include Phase Disposition technique (PD), Phase Opposition Disposition technique (POD), Alternate Phase Opposition Disposition technique (APOD), and Phase Shifted Carrier (PSC). These strategies have been implemented by using simulation and validated by experiment. The detailed examination of the simulation results has been presented and validated with experimental results of 11-level CMLI.
Keywords: PDSVPWM; PODSVPWM; APODSVPWM; CMLI; THIPWM.
Special Issue on: Power Electronics, Industrial Electronics and Their Applications
LMI based Stability analysis of Non-linearly perturbed DC Motor Speed Control System with Constant and Time-varying Delays
by Venkatachalam V, Prabhakaran D, Thirumarimurugan M, Ramakrishnan K
Abstract: In this research work describes the time-delays effect on speed control of DC motor system with nonlinear load disturbance in the states. With this task, the paper presents a linearized model of speed control system based on delay-dependent state equation. Since the non-linearly load disturbance in the DC motor system (with time-delay) ultimately affects the evolution of the system states, the non-linear load disturbance is modeled (mathematical) as a non-bounded non-linear function of current state vector and delayed state vector, subsequently included into the system stability analyses. In the analysis, two cases are employed: constant time-delay and time-varying delay with exogenous load disturbance. In the proposed results, for broad range of PI controller gains, the maximum value of upper bound delay of DC motor speed control system are determined and new stability criterion was identified.
Keywords: DC motor speed control; Delay-dependent stability; Linear Matrix Inequalities (LMIs); Lyapunov-Krasovskii functional technique; Network Control Systems (NCSs); Nonlinear-load perturbations; Time-delays.
A comparative study of Universal Fuzzy Logic and PI speed controllers for Four Switch BLDC Motor Drive
by SENTHIL KUMAR NATARAJAN
Abstract: This paper presents a comparison of PI controller and fuzzy controller for speed control of a low cost brushless DC (BLDC) motor drive used in variable speed drive applications. The cost reduction in BLDC drive system is achieved by the reduction of power semiconductor switches. A PI controller and universal fuzzy controller are designed for the speed control and tested by simulation for various conditions. The simulation is performed by using MATLAB Simulink toolbox and the results show the effective response of the fuzzy controller. The rise time and steady state error of fuzzy controller is improved on an average of about 26% and 55% respectively compared to the conventional PI controller.
Keywords: Four switch drive; BLDC motor; switching sequence; PI controller; Fuzzy controller.
RELEVANCE OF ADAPTIVE PROTECTION SCHEME USING PHASOR MEASUREMENT UNIT IN INDIAN POWER GRID
by DEEPA S KUMAR, SAVIER J S
Abstract: The growing demand for electricity is driving power system nearer to operating limits. The penetration of renewable energy sources, generation diversity and various other technological advancements have added to the variable operating conditions and increasing complexity of present power system. As the configuration of power system is constantly changing due to changing loads, network switching operations or faults, the system may not necessarily be always at its maximum or minimum. The relays settings based on pre-determined static system conditions that are in general maximum or minimum, may not suffice, leading to inaccurate relay operation for a dynamic power system. Malfunction of conventional protection system has been one of the main causes of catastrophes and unwanted cascading trips in power grid . Selection of suitable relay characteristics that will be an appropriate compromise for all loading conditions and contingencies is a matter of concern. The relevance of adaptive relay settings inWide Area Monitoring, Protection, and Control (WAMPAC) using Phasor Measurement Units (PMU) is brought out in this paper using case studies of occurences in Indian grid. The significance of new Wide Area Adaptive Protection System (WAAPS) using synchrophasor measurement in Indian grid is analsyed and an architecture is suggested. The contribution of WAAP in improving the reliability and safety of power transmission through networks with a high level of operational uncertainties, is put forth. Thus, the need for neutralizing the proliferation of disturbances in the grid by acquiring system-wide and chosen restricted information as well as modification of the setting of relays to constitute a class of adaptive or predictive protective devices using Phasor Measurement Units is studied.
Keywords: Phasor Measurement Units (PMUs); Synchronized Measurement
Technology (SMT); Adaptive relay; Protection.
Special Issue on: DC Microgrids and LVDC Distribution Networks
Solar-DC Microgrids for multi-storied Building Complexes in Emerging Nations
by Prabhjot Kaur
Abstract: The emerging nations, like India, are a growing economy and are likely to construct over the next 15 years as many homes and buildings as they exist today. Further the availability of power in these countries is limited and since power is expensive they would want to deploy large-scale decentralized solar PV, especially as the cost of solar PV falls and installation costs of these PV during construction is minimal. For these new homes and building complexes, the DC power-line could provide considerable advantage. It would still need a lot of work to be done before the promised gains would be fully realized, the work such as standardization of voltages, guidelines for wiring practices and making DC-powered appliances available. The potential gains of such deployments, referred to as solar-DC deployments, are enormous.rnIndia therefore took the lead, first focusing on off-grid homes. A 48 V DC micro-grid was driven in homes, by a 125 W solar PV and connecting to a battery which gave effective storage of 0.5 kWh. This could power an LED tube light, two LED bulbs, two BLDC fans and a cell-phone charger in the homes. Such a set-up is now powering 4000 homes located in the deserts of Rajasthan in India and about 1000 homes in other states of India. The advantages in terms of energy-savings and costs to customers are enormous.rnSimilar advantages will apply to offices and multi-storied building complexes. This paper is a study of such pilot implementations as well as development of an eco-system that made these building-owners adopt DC powerlines. The paper starts with a discussion of the architecture used for DC power in such buildings and use of combined 230 V AC and 48 V DC, as well as combined 380 V DC and 48 V DC. It describes the eco-system for DC appliances and then describe test-implementations in three types of buildings as well as some early-results from such deployments.
Keywords: solar-DC; Inverterless; energy efficiency; economical system;.
Overview Paper on: Low Voltage Direct Current (LVDC) Distribution System Standards
by Kyle Smith, Dong Wang, Abdullah Emhemmed, Stuart Galloway, Graeme Burt
Abstract: Low Voltage Direct Current (LVDC) systems have recently been recognised as one of the key enabling technologies that can facilitate the connection of more distributed renewables with improved efficiency and enhanced controllability. This is in addition to the potential provision of increased power flow capacity which is required to meet the anticipated growth in electric transport and heat demand. However, there is still a shortage of mature experience and practical technical solutions that can support the uptake of such systems and increase commercial interest. One of the barriers is the lack of standards necessary to increase industry confidence and for the development of cost effective technical solutions that will accelerate the commercialization of LVDC technologies. Most of the existing international standards focus on alternating current (ac) systems with limited areas covering direct current (dc). Recently, new standard activities at national and international levels have begun to cover specific LVDC applications. However, it is still not clear whether these activities, in addition to existing standards, are sufficient and comprehensive to provide the necessary tools for best practice system design. This paper therefore reviews and evaluates the available LVDC standards within the context of the establish ac system to determine the state of the art of dc standardization and the areas where future work is required.
Keywords: Low Voltage Direct Current (LVDC); Distribution; Applications; Standards.
OVERVIEW ON FAULTS AND PROTECTIONS IN LVDC MICROGRIDS CONNECTED TO THE AC UTILITY
by Marco Carminati, Enrico Ragaini, Enrico Tironi
Abstract: Growth of distributed generation, increasing presence of power electronic devices and energy storage systems are arousing an increasing interest towards LVDC microgrids. Fault protection of such systems it thus becoming more and more important. This paper provides an overview of different possible cases of fault behavior of LVDC microgrids connected to the AC utility grid: commonalities and differences between normal operation and fault condition are highlited. After discussion of some existing critical issues, some possible solutions able to guarantee an effective and selective protection of DC microgrids and avoid the damage of the power electronic converters are proposed.
Keywords: microgrids; short circuits; ground faults; power electronics; converters; protections; solid state circuit breakers.