Smart Converter Research Articles

Digital Active EMI Filter for Smart Electronic Power Converters

Electronic power converters are widespread and crucial components in modern energy scenarios. Beyond mere electrical energy conversion, their electronic structure allows several functionalities to be naturally embedded in them, including energy management, diagnosis, communication, etc. The operation of the converter itself, or the system interfaced by the same, commonly produces undesired electromagnetic interferences (EMIs) that should comply with prescribed limits. This paper presents a digital active EMI filter designed to mitigate such disturbances. The proposed hardware implementation can acquire and analyze the common-mode (CM) noise affecting the circuit and inject a compensation signal to attenuate the measured interference. A novel adaptive algorithm is introduced to compute the necessary signals for effective noise cancellation. The implementation is integrated within a single printed circuit board interfaced with a field-programmable gate array (FPGA) running the control algorithm. The digital filter’s efficacy in EMI reduction is demonstrated using a synchronous buck converter with gallium nitride (GaN) power devices, achieving significant noise reduction. Additionally, potential functionalities are envisioned to fully exploit the capabilities of the proposal beyond EMI filtering, like fault detection, predictive maintenance, smart converter optimization, and communication.

Smart Grid Operation with Hybrid Renewable Resources and Electric Vehicle

The utilization of renewable energy resources will significantly increase to achieve clean and sustainable electricity generation. The management of the continuous growth share of variable renewable resources, integration of electric vehicles (EVs) and regulation of grid frequency require effective communication facilities of recent smart grids. In this respect, smart converters can provide efficient power conditioning devices to extract maximum power from renewable resources. In addition, the batteries of EVs could be used as distributed storage and discharge power back into the grid to compensate power deficit and flactuation. Modeling and controlling of the hybrid resources within smart grid were carried out in this paper. The smart converter is switched to track the maximum power point MPPT of the solar panels. In addition, the pitch angle control and DFIG regulation are used to extracte the maximum power under different wind speed and tidal stream velocities. The deployment of EVs can compensate power fluctuations and regulate the frequency deviations in the grid based on the proposed PID controller. In this paper, the integral minimization of time-weighted absolute error (ITAE) is used for on-line tuning of the PID controller parameters. Using Matlab/Simulink package, the smart grid is modeled and simulated using the weather data of Kuwait and then the grid performance is assessed under system disturbances and load excursions.

A mixed-integer approximation of robust optimization problems with mixed-integer adjustments

In the present article we propose a mixed-integer approximation of adjustable-robust optimization problems, that have both, continuous and discrete variables on the lowest level. As these trilevel problems are notoriously hard to solve, we restrict ourselves to weakly-connected instances. Our approach allows us to approximate, and in some cases exactly represent, the trilevel problem as a single-level mixed-integer problem. This allows us to leverage the computational efficiency of state-of-the-art mixed-integer programming solvers. We demonstrate the value of this approach by applying it to the optimization of power systems, particularly to the control of smart converters.

Power Quality Enhancement of Remote Gas Field Generations with Smart Power Converters

Direct power generation near gas fields offers numerous benefits, including optimized economic efficiency and reduced environmental impact. Moreover, building on-site greenhouses emerges as a promising approach to further minimize carbon emissions and residual heat, greatly promoting resource utilization. However, such power plants generally have access to a weak grid due to their remote locations, and they also contain nonlinear local loads, such as the grow lights in the greenhouses. Consequently, the generation system is susceptible to power quality issues, manifested in overvoltage and harmonics. To address these issues, a smart back-to-back converter is employed to interconnect the gas turbine generator and the utility grid. This smart converter not only enhances power quality but also offers potential ancillary services that contribute to the dynamics of the gas generation system, such as damping low-frequency oscillation among parallel-connected generators. In this paper, three control configurations for the back-to-back converter are developed, enabling the coordinated regulation of exported active power, AC voltage, and DC-link voltage in either a grid-following or grid-forming manner. Furthermore, comparative studies are conducted to provide guidelines for selecting an appropriate control strategy that ensures stable operation under various short circuit ratios. A practical gas cogeneration system is chosen to evaluate the performance of the back-to-back converter, and real-time simulations based on RT-LAB are carried out to validate the effectiveness of the methodology.

Optimal power flow‐based reactive power control in smart distribution network using real‐time cyber‐physical co‐simulation framework

AbstractFuture distribution networks (DN) are subject to rapid load changes and high penetration of variable distributed energy resources (DER). Due to this, the DN operators face several operational challenges, especially voltage violations. Optimal power flow (OPF)‐based reactive power control (RPC) from the smart converter (SC) is one of the viable solutions to address such violations. However, sufficient communication and monitoring infrastructures are not available for OPF‐based RPC. With the development of the latest information communication technology in SC, cyber‐physical co‐simulation (CPCS) has been extensively used for real‐time monitoring and control. Moreover, deploying OPF‐based RPC using CPCS considering the controller design of SC for a realistic DN is still a big challenge. Hence, this paper aims to mitigate voltage violations by using OPF‐based RPC in a real‐time CPCS framework with multiple SCs in a realistic DN. The OPF‐based RPC is achieved by performing the CPCS framework developed in this study. The CIGRE medium‐voltage DN is considered as a test system. Real‐time optimization and signal processing are achieved by Python‐based programs using a model‐based toolchain of a real‐time DN solver and simulator. Real‐time simulation studies showed that the proposed method is capable of handling uncertain voltage violations in real time.

Real-time Volt-Var control of grid forming converters in DER-enriched distribution network

The growing installation of distributed energy resources (DERs) in a distribution network (DN) poses substantial issues related to voltage regulation. Due to constrained switching operation and slower response time, traditional voltage regulation devices cannot handle current voltage-related challenges. One alternative to solve these problems is to use smart converters to control the reactive power to regulate the voltage. Volt-Var control (VVC) is one of the simplest approaches for controlling the reactive power from smart converters. Among several converters, grid forming converters (GFCs) are more suitable in DER-enriched distribution networks. Since DER-enriched distribution networks have a higher fluctuation in voltage profile, real-time control is advantageous. Therefore, this work presents an advanced real-time reactive power control for handling voltage violations in a DN using GFC. The uniqueness of this method is that it controls the voltage magnitude of affected nodes by dispatching reactive power from smart converters in real-time. By running cyber-physical co-simulation (CPCS) between the Typhoon HIL 604 and OpenDSS, the Volt-Var control can be done in real time. The grid-forming converter is modelled in Typhoon HIL 604, which acts as a physical layer of the proposed cyber-physical system for real-time VVC. A CIGRE medium voltage distribution network is designed in OpenDSS and serves as one of the parts of the cyber layer. The CPCS between Typhoon HIL and OpenDSS and the control algorithm are both done by a programme written in Python. The execution of the control algorithm is performed in real time using the Supervisory Control and Data Acquisition (SCADA) developed in this study. The real-time simulation shows that the proposed real-time VVC is capable of handling voltage violations in real time in DER-enriched distribution networks.

Технологічні особливості капсулювання гранульованих добрив плівкою на основі модифікованого ПЕТФ

Проаналізовано взаємодію твердої дисперсної фази, рідкого плівкоутворювача та повітря під час капсулювання гранульованих мінеральних добрив. Показано, що на поверхні частинки відбувається передача тепла від повітря до розчину плівкоутворювача і видалення розчинника у середовище газової фази. Оцінено вплив гідродинаміки, тепло- та масообміну на процес капсулювання амонійної селітри та нітроамофоски в апараті псевдозрідженого стану плівками, які складаються з модифікованого поліетилентерефталату, гідролізного лігніну та цеоліту. Встановлено, що визначальним технологічним параметром процесу капсулювання є швидкість повітря, за якої шар твердого матеріалу буде перебувати у стані стійкого псевдозрідження. Теоретичним методом розраховано швидкість повітря в апараті для капсулювання аміачної селітри 5,6 м/с та нітроамофоски 6,1 м/с. Проведено аналітично-експериментальні дослідження тепломасообміну під час капсулювання гранульованих добрив у апараті псевдозрідженого стану циліндричного типу періодичної дії за встановлених гідродинамічних режимів. Отримано експериментальні залежності температури повітря від висоти шару досліджуваних мінеральних добрив за витрати плівкоутворювача 1∙10-4 кг/с, 3∙10-4 кг/с і 5∙10-4 кг/с з використанням 7-канального інтелектуального перетворювача, який дав змогу одночасно фіксувати температуру в семи точках з виводом інформації на ПК. Графічним методом за кутом нахилу температурних кривих встановлено значення коефіцієнтів тепловіддачі α під час капсулювання аміачної селітри 135,7 Вт/(м2К) і нітроамофоски 118,3 Вт/(м2К). Для плівкоутворювального розчину, який складався із етилацетату 87 % (мас), модифікованого ПЕТФ 10 % (мас), гідролізного лігніну 3 % (мас) визначено коефіцієнти масовіддачі β під час капсулювання аміачної селітри 0,251 м/с і нітроамофоски 0,198 м/с. На підставі отриманих коефіцієнтів масовіддачі встановлено максимальну витрату плівкоутворювача Pmax (104кг/с∙кг добрив): аміачна селітра – 20,512, нітроамофоски – 22,857. За отриманими технологічними параметрами здійснено капсулювання досліджуваних добрив. За характером кінетичних кривих вивільнення компонентів із капсульованих частинок аміачної селітри і нітроамофоски встановлено, що за визначеними технологічними параметрами отримано мінеральні добрива із прогнозованими властивостями.

Design and Control of High-Density High-Voltage Smart Converter for Food Ohmic Heating

The design of an innovative converter for ohmic heating of fluid foods is presented. Application-specific requirements are addressed with new solutions and verified on a commercial-size 60-kW prototype. A multioutput high-voltage (0.8 to 4 kV) transformer with automatic tap change enriches a basic H-bridge topology, enabling processing of a wide set of foods and allowing grounding one of the outputs. High power density is achieved by power switches Pareto optimization in the reliability-efficiency objectives and by pushing the switching frequency up to 30 kHz, solving the electrode corrosion problem, too. Reproducible and reliable operation is assured by three different control strategies: load variability is dealt with high-dynamics power control, repeatable output is guaranteed by input voltage compensation, and optimal working point is ensured by control of the transformer primary current dc component. This last control also allows removing the output capacitors, improving density metrics with respect to the state-of-the-art. Analytical models for all control strategies are given to support dynamic performance tuning while guaranteeing stability.

Multirate Harmonic Compensation Control for Low Switching Frequency Converters: Scheme, Modeling, and Analysis

Using the grid-interfacing voltage-source converters (VSCs) to perform harmonic control as a smart ancillary function is increasingly studied in recent years. Different from the traditional dedicated harmonic compensation converters, the main function of the high-power smart converters is still delivering real power at a low switching frequency (e.g., 2 kHz). It is challenging to compensate harmonics with low switching frequency VSCs due to the low sampling rate and large system delay. This article proposes a multirate control scheme and derives the accurate multirate model to improve harmonic control. The multirate control scheme consists of high-rate harmonic control and synchronous sampled fundamental control. With the proposed control scheme, the advantages of the conventional synchronous sampling method and the benefits of the high sampling rate are achieved simultaneously. To accurately model the low switching VSC with two different sampling rates, the lifting method is introduced to achieve the discrete-time system model for this linear periodic time-varying system. The frequency response and stability analysis are carried out based on the lifted model. The modeling method, as well as the enhanced harmonic control performance of the multirate control structure, is validated in the experiments.

Open-Source Hardware Platforms for Smart Converters with Cloud Connectivity

This paper presents the design and hardware implementation of open-source hardware dedicated to smart converter systems development. Smart converters are simple or interleaved converters. They are equipped with controllers that are able to online impedance match for the maximum power transfer. These conversion systems are particularly feasible for photovoltaic and all renewable energies systems working in continuous changing operating conditions. Smart converters represent promising solutions in recent energetic scenarios, in fact their application is deepening and widening. In this context, the availability of a hardware platform could represent a useful tool. The platform was conceived and released as an open hardware instrument for academy and industry to benefit from the improvements brought by the researchers’ community. The usage of a novel, open-source platform would allow many developers to design smart converters, focusing on algorithms instead of electronics, which could result in a better overall development ecosystem and rapid growth in the number of smart converter applications. The platform itself is proposed as a benchmark in the development and testing of different maximum power point tracking algorithms. The designed system is capable of accurate code implementations, allowing the testing of different current and voltage-controlled algorithms for different renewable energies systems. The circuit features a bi-directional radio frequency communication channel that enables real-time reading of measurements and parameters, and remote modification of both algorithm types and settings. The proposed system was developed and successfully tested in laboratory with a solar module simulator and with real photovoltaic generators. Experimental results indicate state-of-art performances as a converter, while enhanced smart features pave the way to system-level management, real-time diagnostics, and on-the-flight parameters change. Furthermore, the deployment feasibility allows different combinations and arrangements of several energy sources, converters (both single and multi-converters), and modulation strategies. To our knowledge, this project remains the only open-source hardware smart converter platform used for educational, research, and industrial purposes so far.

Design and Implementation of a Cuk Converter Controlled by a Direct Duty Cycle INC-MPPT in PV Battery System

The performance of a solar energy system can be better by inserting a smart power converter with an appropriate MPPT control between the PV source and the load. The smart converter or the well-known as power conditioning unit (PCU) is employed to maximize the power extracted from the solar panel by real-time impedance matching, and to regulate the PV voltage level. The proposed PCU is equipped with a cuk DC-DC converter controlled by a smart energy recovery technique based on direct duty cycle INC algorithm. The review and validity of the proposed PCU model, which interfaces an MSX 60 module with a 12V lead-acid battery, was performed using the Matlab tools. The designed system works effectively and provides the best performance in transient and stable states, regardless of variations in environmental conditions.

Analysis of Power Quality Variations in Electrical Distribution System with Renewable Energy Sources

The increasing u se of Power Electronics along with Distributed Generation Systems (DGs) has been playing a predominant role in the efficient operation of Electric Power Systems. Thus, studies regarding identification and classification of Power Quality (PQ) events have been a subject of recent interest for researchers from the view point of initiating suitable control actions in DGs for achieving improved performance. This requires carrying out a detailed analysis of the various characteristics of real time electrical signals through a set of signal processing techniques . PQ distortions due to environmental factors, such as change in wind speed and solar irradiations are considered in this work. Signal features are extracted for various voltage sag/swell signals using S-Transform, while signal-classification is done by Least Square Support Vector Machine (LS-SVM) technique. A 17-bus test system is modeled using the open source software, Open Distribution System Simulator (OpenDSS). Smart converter control is realized with inputs received from signal classifier, so as to initiate proper grid-support functions. Controlled actions realized are Volt-VAr and Volt-Watt functions. The performance of the control functions is tested for varying levels of solar and wind penetrations. The efficacy of the results is imminent based on control actions being in line with the set reference.

Supervised control of buck-boost converters for aeronautical applications

Recent MEA (More Electric Aircraft) concepts require new approaches to design and management of the electric system onboard. Bidirectional Buck-Boost Converter Units (BBCU’s) used like bridges between power buses with different voltage require intelligent supervisory control for autonomous selection of operating modes. In this paper at low-level, sliding manifold-based strategies are employed to track desired current references, or to recover from overload within a prescribed time. At a higher level, three working modes are defined, (Buck-, Boost- and Intermediate-Mode), and scheduled by a high-level supervisory strategy. Stability proofs of the overall strategy require estimates of the Region of Attraction (ROA) for each controller, that are discussed in the paper. A typical aeronautic scenario is presented, with standard operating conditions followed by two types of overloads (the second more severe than the first) and finally a return to standard condition. Detailed numerical simulations show the effectiveness of the proposed novel control strategy in terms of stability and performance of the smart converter.

Modular Concept of Auxiliary Converters for Diesel Electric Locomotives

Nowadays almost every modern diesel electric locomotive includes auxiliary converters. Auxiliary converters and drives are an integral part of the main traction drives. Auxiliary converters provides cooling of main drives, traction motors, diesel engine, charging the vehicle's batteries and feeding of control circuits in entire locomotive. Auxiliary converters for diesel electric locomotives consists of inverters, chargers, alternator exciters and DC/DC converters of different voltage levels. Due the fact of the equal working principles of individual converters groups, certain amount of power classes has been designed and developed. Also for these groups of converters has been developed universal parameterized control software. The main advantage of parameterization and power classes for individual converters groups is simple design. This feature simply allows to build up complete auxiliary converter for a specific customer application. It is also possible to design and integrate smart converters, which automatically set correct required parameters in locomotive immediately after connecting.

Space Vector Modulation Based Direct Matrix Converter for Stand-Alone system

In this paper Permanent Magnet Synchronous Generator (PMSG) is used for wind power generation in standalone system due to their feature of high efficiency and low maintenance cost, which was fed with smart direct matrix converter for direct AC-AC conversion, It provides sinusoidal output waveforms with minimal higher order harmonics and no sub harmonics and also it eliminate the usage of dc-link and other passive elements. Space vector modulation (SVM) controlled technique is used for matrix converter switching which can eliminate the switching loses by selected switching states.Proposed work are often seen as a future concept for variable speed drives technology.The proposed model for RL load was analysed and verified by varying the resistor and inductance value and analysed using MATLAB simulation. DOI: http://dx.doi.org/10.11591/ijpeds.v4i1.5104

Reliability of power MOSFET-based smart switches under normal and extreme conditions for 24 V battery system applications

This study aims to assess the reliability of smart converters for applications using 24V batteries. It compares degradation effects and lifetime durations for similar dissipated energies when these smart power switches are subjected to normal and extreme protection test conditions. Three experimental ageing tests have been performed: (i) ageing tests under normal protection mode, (ii) ageing tests under repetitive inductive avalanche switching and (iii) ageing tests under repetitive short-circuit. Evolution of several electrical parameters such as on-state resistance; threshold voltage and saturation current have been monitored. Tested devices under normal condition and under repetitive inductive avalanche have failed after about the same number of cycles with the same dissipated energy. However, several results show a significant decrease of the lifetime under repetitive short-circuit tests for a similar dissipated energy.

Scheme for on-Line Monitoring System of Converter Transformer

To achieve a smart converter station, an on-line monitoring system for converter transformer is needed. Furthermore, it is the requirement for transition of maintenance strategy from ‘time-based maintenance’ to ‘condition-based maintenance’. This paper proposes a configuring of converter transformer on-line monitoring system based on the principle and application of on-line monitoring system for transformer, and the characteristics and operating environment of converter transformer. Architecture of converter transformer on-line monitoring system is also proposed on the basis of the 3-layer & 2-net structure applied in new smart substations and reconstruction. The designed scheme is suitable for transformation or new of smart converter transformer on-line monitoring system, which with good reference significance and application value.

Efficiency-Based Current Distribution Scheme for Scalable Digital Power Converters

The trend in next-generation switched-mode power supplies will lead to modular, scalable solutions, which deliver power efficiently over a wide range of operation. This paper details a new approach to introduce more advanced control features to improve system efficiency into these scalable solutions. While these methods have been incorporated into multiphase converters in the past, they all require the distribution of information among the individual converters. An advantage of the proposed method is that it does not require such communication signals between the individual power supplies and is, therefore, fully scalable and cost effective. A system comprising individual, smart converters is proposed, where each converter regulates its respective output power to a level with high efficiency. Converters not required for the delivered output power are shut down. The proposed approach is analyzed theoretically. Implementation details for a field-programmable gate array experimental prototype system are given. The system performance for a four-converter prototype system is analyzed and discussed. The efficiency obtained is compared with the efficiency of a multiphase system with phase-shedding operation and the efficiency of a system with independent power converters without phase-shedding support.

Smart Front-Ends, from Vision to Design

An integral multi-disciplinary chain optimization based on a high-level cascaded Shannon-based channel modeling is proposed. It is argued that the analog part of the front-end (FE) will become a bottleneck in the overall chain. This requires a FE-centric design approach, aiming for maximizing the effective data capacity, and for an optimal exploitation of this capacity for given power dissipation. At high level, this asks for a new view on the so-called client-server relations in the chain. To substantiate this vision, some examples of research projects in our group are addressed. These include FE-driven transmission schemes, duty-cycled operation with wake-up radio, programmable FEs, smart antenna-FE combinations, smart and flexible converters, and smart pre and post correction. Copyright © 2009 The Institute of Electronics, Information and Communication Engineers.