Power Electronic Components Research Articles

ANFIS Supervised PID Controlled SAPF for Harmonic Current Compensation at Nonlinear Loads

ABSTRACT The smart devices comprise extensive embedding of small-size AC power-driven power electronics components. This improves the smart automation in the majority of applications in the industry and home system. But, the nonlinear characteristics of such component introduces several higher-order harmonics and generates possible deviation in performance measures. The long-term persistence of harmonic distortions in the current distribution may result in system failure and depreciation in system efficiency. This paper presents a soft computing technique for reactive power compensation of harmonic current using adaptive neural fuzzy interface system (ANFIS). The smart ANFIS supervises the PID controller for adequate gate signaling to shunt active power filter (SAPF) by hysteresis current control. The neural network is trained by adaptive data set of error and deviation in error with respect to hysteresis current control. The nonlinear load model is subjected to transformer-less SAPF to avoid the presence of insertion losses and improves the system compatibility. The proposed system reduces the harmonic distortion from 92.23 to 0.49% in the nonlinear power converter model with improved 0.99 power factor. Additionally, the proposed system is absolutely feasible and novel for real-time application in smart devices with adequate transient and regression response. The proposed system is realized for individual effects of PID, ANN and ANFIS to justify the candidature of the soft computing technique in real-time applications as per IEEE 519 standard.

Methods for the Separation of Failure Modes in Power-Cycling Tests of High-Power Transistor Modules Using Accurate Voltage Monitoring

The accurate measurement of on-state device voltage during power-cycling tests can deliver important information about the health of the tested power electronics components. In this article, we present the major aspects of how a power-cycling test can be set up to enable high-resolution device voltage monitoring, during both heating and cooling stages, and discuss the effect of some important parameters on the arising failure modes. The thermal transient of the component can also be captured in these setups. We show how the structure functions calculated from the captured thermal transients can be used to reveal the location of degradation in the module structure. Finally, the method for identification of bond-wire cracking and lift-off using only the measured voltage curves, is shown.

Novel iGSE-C Loss Modeling of X7R Ceramic Capacitors

Due to the large relative permittivity of Class II dielectrics, ceramic capacitors (CCs) from these materials promise significant volume and weight reductions in inverter and rectifier sine-wave filters, and are especially attractive in mobile applications that demand ultrahigh power density. While previous literature found large low-frequency losses in these components, no extensible loss model was proposed to accurately characterize these ferroelectric losses. In this article, we take advantage of prior art on ferromagnetic components in power electronics to propose a Steinmetz parameter-based loss modeling approach for X7R CCs, named the Improved Generalized Steinmetz Equation for CCs, or iGSE-C. This model is verified using the Sawyer-Tower circuit to measure losses in a commercially available X7R capacitor across excitation magnitude, dc bias, temperature, excitation frequency, and harmonic injection. Losses are shown to scale according to a power law with charge, with the resulting Steinmetz coefficients valid across dc bias and slightly varying as the temperature is increased. The iGSE-C accurately predicts losses for typical nonsinusoidal phase voltage waveforms with an error under 8%. Finally, the loss modeling technique is demonstrated for the sine-wave output filter of a bridge-leg arrangement with both low- and high-frequency excitations, with total capacitor losses predicted within 12% accuracy.

A Comparative Study of the UPFC System by Simulation with PI-D and (NEWELM and NIMC) Controllers Based on the Adaptive Control for the Compensation of Power

-Flexible Alternating Current Transmission System devices (FACTS) are power electronic components. Their fast response offers potential benefits for power system stability enhancement and allows utilities to operate their transmission systems even closer to their physical limitations, more efficiently, with improved reliability, greater stability and security than traditional mechanical switching technology. The unified Power Flow Controller (UPFC) is the most comprehensive multivariable device among the FACTS controllers. According to high importance of power flow control in transmission lines, new controllers are designed based on the Elman Recurrent Neural Network (NEWELM) and Neural Inverse Model Control (NIMC) with adaptive control. The Main purpose of this paper is to design a controller which enables a power system to track reference signals precisely and to be robust in the presence of uncertainty of system parameters and disturbances. The performances of the proposed controllers (NEWELM and NIMC) are based neural adaptive control and simulated on a two bus test system and compared with a conventional PI controller with decoupling (PI-D). The studies are performed based on well known software package MATLAB/Simulink tool box.

Reducing the risk of cascading failure in active distribution networks using adaptive critic design

In this study, a technique for developing a distribution management system (DMS), which possesses the flexibility to take both preventive and corrective actions against thermal overloading of branches in active distribution networks (ADNs), has been demonstrated. An ADN comprises microgrids that consist of photovoltaic and battery energy storage systems (BESSs). The DMS primarily minimizes the hourly cumulative cost incurred by loads due to energy pricing of utility, by effectively dispatching the BESSs. Besides, the DMS regulates BESS state of charge and bus voltages within their limits. It also controls loading of branches by taking corrective measures during overloading or preventive measures during critical loading conditions. This DMS has been designed using a reinforcement learning based technique, namely, adaptive critic design (ACD). This study elaborates the formulation of ACD algorithm so that an effective performance of the controller can be achieved. As case study, a modified IEEE 5-bus system along with a microgrid and its controllers have been modelled in detail and simulated in real-time by developing a simulation-in-the-loop testbed using OPAL-RT and DSpace. This testbed facilitates simulation of the detailed model along with its power electronic components, such that both transient and steady-state performance of the system can be observed.

Analysis and Design Method of Multiple-Output Switched-Capacitor Voltage Regulators With a Reduced Number of Power Electronic Components

This paper presents a study of compact multiple-output switched-capacitor voltage regulators (MOSCVRs). Two methods to produce multiple outputs with an SCVR and their effects on performance – power efficiency and cross-regulation, are examined with output impedance analysis. Moreover, to help a circuit designer to implement a compact MOSCVR, a design method to determine the number of outputs and their conversion ratios is also proposed in this work. To verify this method, we demonstrate the design of an example compact MOSCVR. The MOSCVR is capable of simultaneously producing four different output voltages from a single input power supply with only two flying capacitors and twelve switches. The study presented in this work provides not only comprehensive insight but also guidance to find the suitable topology of a compact MOSCVR.

Design of Experiments Predictive Models as a Tool for Lifespan Prediction and Comparison for Enameled Wires Used in Low-Voltage Inverter-Fed Motors

Since the development of power electronic components, which allowed the manufacturing of reliable and efficient inverters, variable speed drives using inductive motors have become more and more popular. The pulsewidth modulation (PWM) technique has proven to be a very effective method of rotational speed control. However, the fast-changing voltage pulses, with very steep slopes (in the order of a few kilovolt/microsecond), have brought new hazards for the electrical insulation system of such motors. Very high frequency harmonic components of PWM voltage will result in significant overvoltage due to an impedance mismatch between the cable and the motor. As an effect, the voltage seen by some parts of the insulation system may exceed the partial discharge inception voltage stating the localized partial discharges activity. The aim of this article is to investigate and analyze the aging process of the enameled wire exposed to different factors and to propose a method allowing them to predict their lifespans in given conditions. This study introduces a prediction based on the design of experiments method and the statistical Weibull distribution. Thanks to the model obtained with short multistress aging tests, it is possible to predict the results of significantly longer ones. Moreover, the adopted methodology is proposed that allows us to predict the scatter of the long tests based on the short-time results dispersion. The same approach is used to compare different products between each other and rank them. All model predictions are compared with the experimental data in order to prove the model accuracy.

Electro-Thermal Modelling and Experimental Verification of Power Semiconductor Diode

The aim of the proposed paper is discussing problematics related to the thermal modelling of power electronic components. More in detail, the electro-thermal relationship is investigated for the selected power diode, while analysis shall serve for system optimization considering thermal performance with the use of highly accurate 3D simulation model. The presented approach describes the procedure of the simulation model development, whereby the main part is discussing necessities relevant for material property identification through the indirect procedure, i.e, material properties are not known from the manufacturer. Electro-thermal dependencies are defined within the proposed model, while this model enables parametric changes of the geometrical properties of the device. Added value of this procedure is the possibility of its use in exact determination of the lifetime of a semiconductor component using mathematical models taking into account operational variables (current, voltage, temperature, etc.). The proposed model is verified and validated through thermovision experimental measurements within defined operational conditions.

Large‐signal model of pulsed power load for analysis of dynamic voltage and frequency

The characteristics of pulsed power loads (PPLs), which contain several power electronic components, are different from the conventional RLC loads. If a PPL is directly connected to a sole power supply that has limited generation and small inertia (e.g. diesel generator), the sudden increase of energy demand could cause the huge voltage sags and the significant frequency drop upon the power supply. For this reason, this study proposes a large-signal model of PPL for analysing the dynamic voltage and frequency during PPL deployment. The proposed model can be described by non-linear differential-algebraic equations and established based on the equivalent circuit of PPL and the corresponding switching functions. According to the case study, the proposed model is compared with the conventional state-space averaged model and the time-domain simulation, by analysing the dynamic voltage and frequency. Finally, the test results verify the effectiveness of the proposed model and demonstrate that the proposed large-signal model would help for the study on the stability of the case-study system as well as the interaction between the diesel generators and the PPLs.

A Reconfigurable On-Board Power Converter for Electric Vehicle With Reduced Switch Count

This paper proposes a compact reconfigurable on-board power converter for low voltage electric vehicle. The proposed converter serves the purpose of a battery charger as well as a 3-phase voltage source inverter (VSI) to drive the traction motor. The 3-phase VSI is the backbone of this converter that can be either reconfigured to a propulsion unit or to a battery charger by adding few more power electronics components. During charging mode, the topology is reconfigured to form a front-end boost power factor correction rectifier which is cascaded by a DC-DC converter through a DC link. The same power stage is reconfigured to operate as a 3-phase VSI to drive the traction motor during propulsion mode. Thus, it reduces the switch count by eliminating the requirement of a separate inverter stage. Simultaneously the weight, volume, and cost of the overall system are reduced. Unified control technique is implemented which is capable to achieve near-unity power factor operation of front-end boost rectifier as well as optimal battery charging without sensing the DC link voltage. This control scheme implements a single control loop for both stages by eliminating the need of two separate control loop for each stage of the charger. A 470 W scaled-down prototype is developed and its performance is validated with Constant Current-Constant Voltage charging of a 24 V, 30Ah battery pack in charging mode and with a 400W BLDC motor in propulsion mode.

Karakteristik Disturbansi di Rentang Frekuensi 9-150 kHz Pada Sistem UPS Berbeban Induktif

In every UPS device there are power electronic components including inverters, therefore using an inverter will cause voltage disturbances at high frequency because the switching frequency of the inverter is at high frequency. Data recorded by the oscilloscope along with the Picolog Recorder software and processed by Matlab software to make it more efficient. Research conducted when the UPS uses dual conversion mode and with inductive load variations 0.35 H, 0.7 H, 1.4 H and 2.8 H. The test results show that voltage disturbances occur in three dominant frequency ranges at each level of load variations are 9-19 kHz, 20-30 kHz and 31-41 kHz. In the condition of 10% loading rate with a load of 0.35 H the peak voltage disturbances occur at 81.17 mV in frequency of 9.2 kHz and at the condition of the 75% loading rate with 2.8 H load the peak voltage disturbances that occur at 92.20 mV in frequency of 9.6 kHz. The disturbances voltage increases with the increasing of inductive loads that connected to UPS.

Comparative Evaluation of Lifetime of Three-Level Inverters in Grid-Connected Photovoltaic Systems

The cost of the PV energy reduction is still required to increase the penetration level of PV systems in the energy market. The reliability of PV inverters is one of the important aspects to be enhanced in order to reduce the cost of PV energy, since it is closely related to the maintenance cost and the annual energy production. In this paper, the lifetime of NPC and T-type inverters, which are three-level inverter topologies that are widely used for PV systems, are comparatively evaluated with a 30 kW grid-connected PV system. It is performed by focusing on power devices since the power electronic components of both converters are the same except for the power devices. Therefore, this result can represent the comparison of the reliability performance of the NPC and T-type inverters. The power loss and temperature distributions of power devices are analyzed and their efficiencies are compared at different power levels with different switching frequencies. The lifetimes of the reliability-critical power devices in the NPC and T-type inverters are estimated, respectively with a one-year mission profile of the PV system, and the results are compared.

Methodology for Reliability Analysis of Cyber–Physical MTdc Grids

The MTdc grid can be considered as a cyber–physical system as they are dependent on the cyber infrastructure for optimal coordination of its resources irrespective of the adopted control strategy (master–slave, voltage margin, or droop). Hence, the reliability of the MTdc grids depends not only on the reliability of the power electronic components of the converter but also on the cyber infrastructure. This article proposes a reliability evaluation method based on a continuous-time Markov chain (CTMC) for cyber–physical MTdc grids. The detailed failure models of the cyber–physical components of the MTdc grids are presented. A method is proposed to derive the multidomain reliability of the MTdc grid. Finally, the proposed method is applied for the reliability analysis of a three-terminal dc grid. The impact of specific redundancy measures of the cyber components on the reliability of the MTdc grid control is presented.

A Novel Structural Similarity Based Pilot Protection for Renewable Power Transmission Line

The wide application of power electronic component in power system with renewable energy sources has changed the fault characteristics of conventional power system, resulting in the performance degradation of conventional protection, and even the risk of maloperation and rejection. This brings challenges to the security and stability of the power grid. Therefore, in order to solve these problems, a novel principle of pilot protection based on structural similarity and square error method is proposed. The structural similarity criterion makes use of the difference of fault characteristics between renewable sources and synchronous generators to identify internal faults, while the square error auxiliary criterion is used to solve abnormal calculation of the existing similarity based protection. The detailed model of grid-connected renewable energy power plant is built in Real Time Digital Simulator (RTDS) and the proposed protection algorithm is solidified in the industrial protection device. The effectiveness of the proposed principle is verified by hardware-in-loop dynamic simulation experiments. Compared with conventional differential protection, the proposed protection shows excellent performance in speed and reliability during various faults. In addition, a field short-circuit test is carried out in a real wind farm to verify the effectiveness of the proposed protection scheme. It is proved that this proposed method has the prospect for industrial application.

Fault tolerant architecture of an efficient five‐level multilevel inverter with overload capability characteristics

Multilevel inverters (MLIs) are gaining the widespread attention in various industrial applications. However, the advantages offered by MLIs are only met with the employment of a high number of semiconductor switches and capacitors, which are most vulnerable amongst all the power electronic components. Thus, designing of a reliable MLI topology is a need of the present hour. In this regard, a five-level fault tolerant MLI topology has been proposed here. The proposed MLI topology comprises the main inverter topology and a redundant leg. The main inverter topology comprises bidirectional switches which result in high power losses under both healthy and faulty conditions. Eighteen different cases arising from the inherent redundancy available in the main inverter topology have been analysed to achieve the optimum solution for obtaining high efficiency. A novel redundant leg architecture has been designed, which achieves significantly improved efficiency under all faulty conditions. Under overload conditions, the proposed redundant leg architecture is capable of reducing the current stress on the main inverter switches. An effective qualitative and quantitative comparison of the proposed topology with the recent literature has been presented. The feasibility of the proposed concepts has been verified by the obtained simulation and hardware results.

Electric Vehicle Battery Performance Investigation Based on Real World Current Harmonics

Electric vehicle (EV) powertrains consist of power electronic components as well as electric machines to manage the energy flow between different powertrain subsystems and to deliver the necessary torque and power requirements at the wheels. These power subsystems can generate undesired electrical harmonics on the direct current (DC) bus of the powertrain. This may lead to the on-board battery being subjected to DC current superposed with undesirable high- and low- frequency current oscillations, known as ripples. From real-world measurements, significant current harmonics perturbations within the range of 50 Hz to 4 kHz have been observed on the high voltage DC bus of the EV. In the limited literature, investigations into the impact of these harmonics on the degradation of battery systems have been conducted. In these studies, the battery systems were supplied by superposed current signals i.e., DC superposed by a single frequency alternating current (AC). None of these studies considered applying the entire spectrum of the ripple current measured in the real-world scenario, which is focused on in this research. The preliminary results indicate that there is no difference concerning capacity fade or impedance rise between the cells subjected to just DC current and those subjected additionally to a superposed AC ripple current.

5-Hz Distribution System for Mitigation of Energy Theft by Residential Consumers

Energy theft through meter bypass by residential consumers constitutes significant revenue loss to electric power distribution companies. This unpleasant phenomenon is particularly worrisome in sub-Saharan Africa and some parts of Asia. This paper reports the outcome of a research which attempts to develop a modified distribution and metering system to demotivate energy theft by residential consumers. The project involves modeling and simulating a 5-Hz distribution system in SimPowerSystems. The developed system is then implemented using laboratory-scale power electronics components. The modified distribution system is thereafter interfaced with a modified digital consumer energy meter. The system is subsequently tested by deploying it to power two categories of lighting loads. The test results show that one category of lighting load flickers while the other category is non-operational whenever the proposed system is bypassed, though the power remains available. This is expected to demotivate the practice of energy theft through meter bypass. Thus, it is further expected that the proposed system will mitigate revenue loss by power distribution companies thereby stimulating investments in the sub-sector.

Експериментальне дослідження компактної системи охолодження з тепловими трубами для потужної світлодіодної матриці

LED light sources, and powerful multichip light sources in particular, are currently widely used for lighting household and industrial premises. With an increase in power, the amount of heat increases as well, which leads to an increase in the temperature of semiconductor crystals and, accordingly, to a decrease in the reliability of LEDs and a change in their photometric characteristics. Therefore, when developing the design of LED lighting devices, special attention is paid to thermal management. Since the early 2000s, heat pipes have been widely used to efficiently remove heat from powerful electronic components. They do not require power for moving the working fluid and are most suitable for use in LED luminaires. In this study, the authors carry out a computer simulation of a cooling system based on heat pipes, which is then used to design and test a powerful compact LED lamp with a thermal load of up to 100 W. Heat pipes with a length of 150 mm are used to remove heat from the LED light source to the heat exchanger rings located concentrically around it. The heat exchanger rings are cooled by natural convection of the ambient air. The results of computer modeling of the temperature field of the developed cooling system show that at a power of the LED light source of 140.7 W, the temperature of the LED matrix case is 60.5°C, and the experimentally measured temperature is 61.3°C. The experimentally determined thermal power of the LED matrix is 91.5 W. The p–n junction temperature is 79.6°C. The total thermal resistance of the cooling system is 0.453°C/W. The obtained results indicate the effectiveness of the developed design.

Energy Arbitrage Optimization With Battery Storage: 3D-MILP for Electro-Thermal Performance and Semi-Empirical Aging Models

Dispatch of battery storage systems for stationary grid applications is a topic of increasing interest: due to the volatility of power system's energy supply relying on variable renewable energy sources, one foresees a rising demand and market potential for both short- and long-term fluctuation smoothing via energy storage. While the potential revenue attainable via arbitrage trading may yet surpass the steadily declining cost of lithium-ion battery storage systems, profitability will be constrained directly by the limited lifetime of the battery system and lowered by dissipation losses of both battery and power electronic components. In this study, we present a novel three-dimensional mixed-integer program formulation allowing to model power, state of charge (SOC), and temperature dependence of battery dynamics simultaneously in a three dimensional space leveraging binary counting and union-jack triangulation. The inclusion of a state-of-the-art electro-thermal degradation model with its dependence on most influential physical parameters to the arbitrage revenue optimization allows to extend the battery lifetime by 2.2 years (or 40%) over a base scenario. By doing a profitability estimation over the battery's lifetime and using 2018 historical intraday market trading prices, we have shown that profitability of the system increases by 11.14% via introducing SOC awareness and another significant 12.64% via introducing thermal sensitivity, resulting in a total 25.19% increase over the base case optimization formulation. Lastly, through the open source publication of the optimization routines described herein, an adaption and development of the code to individual needs is facilitated.

Performance Assessment of the RTDS/RSCAD VSC Model

This document presents a performance assessment of the three-phase two-level voltage source converter (VSC) model of the real-time digital simulator RTDS/RSCAD. This evaluation is conducted through two case studies. One case is a simple two-bus power electronic-based system, and the second case is a three-bus system with a frequency-dependent transmission line model and a closed-loop controlled VSC with communication delay. The results obtained reveal that the RTDS/RSCAD VSC model presents some issues on stability, harmonic spectrum, ripple, and power quality in general, as compared with the PSCAD VSC solutions. These results also suggest the need for better power electronic components models.