Interface Converter Research Articles

Influence of Output Terminations on Common-Mode Conducted Emissions Evaluation of Interface Converters

Influence of Output Terminations on Common-Mode Conducted Emissions Evaluation of Interface Converters

Reinforcement Learning-Based Integrated Control to Improve the Efficiency of DC Microgrids

The hierarchical control of the DC microgrid regulates the terminal voltages of the interfacing converter to achieve proportional load sharing and good voltage regulation at the DC bus. In doing so, the difference of the voltage at different nodes increases which results in higher circulating current and leads to higher losses. In this paper, a Reinforcement Learning Based Integrated Control (RLIC) is proposed which will minimize the circulating current and power losses in the transmission. The proposed RLIC consists of a primary and secondary controller. The primary controller is a robust sliding mode controller which receives the voltage references from secondary controller and regulates the terminal voltage and source current accordingly. The secondary control consists of a proportional integral control (PI), and a Deep Neural Network (DNN) surrogate model with implementation of Q-Learning as reinforcement method. A novel DNN based surrogate model uses the droop value from the PI controller and estimates the power loss and the local and global loading difference for a particular node, for a set of operating condition. This surrogate model is used by the Q-Learning based reinforcement technique which adjusts the droop constants and provide the voltage reference to primary controller to maintain load sharing and reduce the power losses, there-by leading to an improved overall efficiency. The proposed control structure is verified to improve efficiency while maintaining the load sharing and bus voltage regulation.

Stability Boundary of Power System with Converter Interfaced Generation: Evolution and Transition Point

Stability Boundary of Power System with Converter Interfaced Generation: Evolution and Transition Point

Refined vector control structure and indirect MPPT for grid connected DFIG-based wind energy conversion system, and appraisal on matrix converter interface

Refined vector control structure and indirect MPPT for grid connected DFIG-based wind energy conversion system, and appraisal on matrix converter interface

Design and Development of Bidirectional Converter based on V2G and G2V Operation

The rapid progression of electric vehicles (EVs) in the transportation sector poses a potential challenge of increased peak energy demand on existing grid structures. Consequently, the significance of V2G power conversion technology becomes paramount in managing sudden surges in energy requirements. To address this issue, the authors propose a “Bidirectional Converter Based on V2G and G2V Operation” which focuses on facilitating energy transfer between vehicles and the grid through bidirectional converters, catering to both V2G and G2V operations. In this work, the authors analyzed a bidirectional buck-boost converter interface with an H bridge AC/DC converter together with the related control method in a reduced topology. The efficiency of the developed system is evaluated with the help of a developed simulation model in MATLAB/SIMULINK. The developed model was tested under various conditions and was able to perform effectively.

Sector Wise Modified Droop Control to Improve Voltage Regulation and Current Sharing in Parallel Boost Converter Interfaced DC Microgrid

Sector Wise Modified Droop Control to Improve Voltage Regulation and Current Sharing in Parallel Boost Converter Interfaced DC Microgrid

Enhanced Multiphase Interleaved Boost Converter Interface for Grid-Connected PV Power System

Enhanced Multiphase Interleaved Boost Converter Interface for Grid-Connected PV Power System

Investigation of a Low-Speed Commutation Voltage Shock Problem in Three-Level ANPC Inverter with Hybrid Modulation Mode

With the development of the photovoltaic industry; there will be an increasing demand for efficient, high-power density, and low-cost grid interface converters. Compared with two-level inverters, multilevel inverters have the following advantages: (1) lower device voltage ratings; (2) better output filtering spectrum; (3) lower electromagnetic interference (EMI) noise; and (4) higher switching speed capability. However, the complex switching circuit of the multilevel inverter will bring more parasitic inductance, resulting in severe switching overvoltage (ringing). Especially in order to reduce the cost of the inverter, using the long-loop modulation mode, the commutation loop will introduce more parasitic inductance, which will make the overvoltage more serious. Consider that commonly used overvoltage absorption schemes are effective only for overvoltage or suppression of oscillations. Therefore, a new overvoltage absorption circuit is proposed in this paper, which can not only alleviate the overvoltage and ringing phenomena but also suppress the effect of voltage jumps during low-frequency switching on high-frequency input voltage. This overvoltage absorption circuit is characterized by low overvoltage, fast ringing damping, and minimum capacitance. Experiments and simulations are conducted to verify the effectiveness of this overvoltage absorption circuit using a three-level ANPC inverter as a prototype. The results show that the proposed overvoltage absorption circuit can significantly reduce the overvoltage level, shorten the oscillation time, and reduce the voltage difference between the upper and lower DC bus capacitors.

Diagnostic system of the facility for studying superconducting quadrupoles

For the HED@FAIR project, NRC “Kurchatov Institute” — IHEP creates four quadrupole magnets with a unique combination of a large internal diameter of the superconducting winding and a high magnetic field gradient in the magnet aperture. To evaluate these superconducting magnets in different operation modes (cooling, maintaining operating parameters, heating, and transitioning magnet to the normal state), a cryogenic facility equipped with a diagnostic system was created. The main measured parameters of the unit were temperature, pressure, and vacuum in the equipment and pipelines, levels of liquid helium and liquid nitrogen, level of the gas holder, and helium flow rate. The control devices were represented by valves with electric and valves. For processing incoming signals from sensors and generation of control actions, the equipment of the domestic company OVEN was used, particularly analog input modules MV110, discrete output modules MU110, and interface converters alternating current four and direct current power supplies. The critical part of the diagnostics system, namely, the control of cryogenic valves, was provided through analog output modules NI 9219 and input modules NI 9212 (feedback) of the CompactRIO chassis. The program part of the installation for the study of superconducting quadruples is a mnemonic diagram with interactive graphic elements, physically located on the computer (operator console), and available in the read mode via the remote desktop protocol to users outside the installation. The mnemonic scheme allows the manual control of the plant’s valves and the automatic regulation of some indicators, depending on the settings assigned by the operator. The dynamics of the processes can be monitored with graphs on the right side of the interface. These graphs are displayed on a separate display at the operator’s console, whereas they are displayed on a unified screen for remote users.

Power converter interface for urban DC traction substations - solutions and functionality

Power converter interface for urban DC traction substations - solutions and functionality

A comprehensive analysis of control strategies for enhancing regulation in standalone photovoltaic systems

This article extensively analyses PI, Type-2, and Type-3 controllers in interfacing converters, specifically focusing on boost and interleaved-boost converters. The primary objective is to enhance regulation within a standalone microgrid system integrated with photovoltaic (PV) sources. The analysis encompasses various aspects of regulation, including line and load regulation, reference tracking, and parametric sensitivity analysis. The initial phase of the study involves examining interfacing converters, specifically the boost and interleaved-boost converters, using small-signal modelling in the continuous conduction mode (CCM). Subsequently, we propose and implement PI, Type-2, and Type-3 controllers for the closed-loop operation of these converters to achieve improved dynamic efficiency and reliability. The implemented control strategy integrates maximum power point tracking (MPPT) with these controllers (PI, Type-2, Type-3) and compares boost and interleaved-boost converters comprehensively. This comparison is supported by theoretical, numerical, and graphical analyses of various transient parameters such as rise time, settling time, and maximum overshoot. The results of our study demonstrate that the interleaved-boost converter (IBC) coupled with a Type-3 controller exhibits the most favourable transient performance across all aspects of regulation, including line and load regulation, reference tracking, and parametric sensitivity analysis. To validate the proposed methodology, we conducted experimental work with an input voltage of 10 V, using the parameters of the Exide 225-watt polycrystalline solar panel as a reference.

Digital-Power-Communication Concept for Energy Coordination in PV-Battery-Charging DC Microgrid

A new digital-power-communication (DPC) concept is proposed to better realize information interaction and energy coordination in the PV-battery-charging DC microgrid, which uses the DPC auxiliary power supply as carrier. The DPC auxiliary power supply can be used to replace other communication modules as a common carrier for auxiliary power supply and information interaction of microgrid interface converter. Then, the implementation conditions of DPC are indicated that this communication concept requires active power consumption and an adjustable resonant network. Meanwhile, an appropriate circuit topology of the DPC auxiliary power supply is evolved. Furthermore, an integrated control method of optimal-admittance information regulation & power supply is further proposed for the DPC auxiliary power supply, and the implementation mechanism of this method is analyzed in detail by establishing the admittance model. More importantly, based on this method, the contradiction between power supply quality and signal intensity can be solved in the transmit mode, and the received signal intensity of the communicating node can be significantly enhanced in the receive mode. Finally, the PVbattery-charging DC microgrid platform is developed, and the experiment result verify the feasibility of the DPC concept and the effectiveness of the proposed control method.

Method to Quantify Modal Interactions Between Converter Interfaced Generators and Synchronous Generators

The aim of this paper is to quantify the interactions between the oscillation modes of power systems within the realm of small-signal stability. This paper focuses on the interactions between Converter Interfaced Generator (CIG) oscillation modes and electromechanical oscillation modes of Synchronous Generators (SGs). It is difficult to determine the modal interactions using the existing analysis such as mode sensitivity, mode loci and participation factors. This paper proposes an extension to eigenvalue sensitivity analysis in order to determine the interaction between modes and impact of the interaction on system stability. Interaction coefficients are proposed to quantify the interaction between the modes. A modified IEEE 39-bus system with CIGs is considered to carry out the proposed analysis. The analysis is carried out to investigate the impact of PLL parameters on the interaction among the oscillation modes. The analysis is also carried out considering renewable energy penetration levels of 50-70%. It is observed that the interaction between CIG and electromechanical modes of SG results in increased participation of SGs' states in CIG modes. This increased participation of SG states in CIG modes results in reduced damping of oscillations in SG states.

Система обучения программированию и выбор микроконтроллеров для управления электроприводами

Ability of university graduates to design electric drives (ED) implies that they have knowledge and skills to develop software for microcontrollers (MC) used in modern electric drive control systems (ED CS). Studies on this topic touch upon the issues of particular training courses or teaching methods, and laboratory benches mean only debug boards. Often, education process is designed on a piecemeal basis. A systematic approach is required to teach students programming of microcontrollers of ED CS. In the context of restrictions of manufacturers from the USA, Japan and Europe, the selection of microcontroller for training and developing the ED CS is also topical. When developing the interrelated training courses, the authors have used 20 years of experience of design of ED CS. Product design software packages and metalworking technologies have been used as tools to develop a specialized laboratory bench. The method of comparative analysis is used when selecting microcontrollers. A multi-level (3-stage) model of interrelated training courses to teach students programming MC of ED CS is described. The evolution of the contents of training courses is shown. The author-developed bench is presented. It includes the debug board, measuring (multimeter, oscilloscope) and debugging (interface converters) equipment placed on a special unit. A review is given, an analysis of studies on these issues is carried out, and recommendations to select MC of ED CS in the current situation are given. Implemented at the department, a systematic approach to teach students programming MC of ED CS gives them the qualifications necessary to independently perform tasks during the design of modern ED CS. The developed laboratory bench provides convenient and safety work with all debugging and measuring equipment used in the educational process. An overview and recommendations on the selection of MC of domestic and Chinese manufacturers will be useful for the developers of the electrical drive control systems.

An Automated Method for Generating Prefabs of AR Map Point Symbols Based on Object Detection Model

Augmented reality (AR) technology enables paper maps to dynamically express three-dimensional geographic information, realizing the fusion of virtual and real information. However, in the current mainstream AR development software, the virtual information usually consists of prefabricated components (prefabs), and the content creation for AR maps heavily relies on manual prefabrication. It leads to repetitive and error-prone prefabrication work, which restricts the design of the dynamic, interactive functions of AR maps. To solve this problem, this paper explored the possibility of automatically generating AR map prefabs using object detection models to establish a data conversion interface from paper maps to AR maps. First, we compared and analyzed various object detection models and selected YOLOv8x to recognize map point symbols. Then, we proposed a method to automatically generate AR map prefabs based on the predicted bounding boxes of the object detection model, which could generate prefabs with corresponding categories and positional information. Finally, we developed an AR map prototype system based on Android mobile devices. We designed an interaction method for information queries in the system to verify the effectiveness of the method proposed in this paper. The validation results indicate that our method can be practically applied to the AR map prefabrication process and can quickly generate AR map prefabs with high information accuracy. It alleviated the repetitive workload established through the manual prefabrication method and had specific feasibility and practicality. Moreover, it could provide solid data support for developing dynamic interactive functions of AR maps.

Connecting multiple vehicular PEM fuel cells to electrical power grid as alternative energy sources: A Case Study

Advances in fuel cell (FC) technology make them an alternative energy source in several applications such as static, portable, and transportation. Recently, the energy needs of hydrogen electric vehicles, which have developed as an alternative to battery electric vehicles (BEVs) and have significant potential in the future, are met by vehicular hydrogen FCs. In this regard, fuel cell electric vehicles (FCEVs), which have started to take their place in the transportation sector, can also be used as an additional energy source with their energy unit for electrical power grid-connected systems. In grid-vehicle integration, vehicular FCs can meet a significant part of the electricity consumption when parked and help stabilize the grid. In this study, multiple vehicular PEM fuel cells (PEMFCs), the most widely used in FCEVs, support the residential grid by injecting electrical power into the connecting system. For this, a multi-input dc-dc boost converter interface is designed and utilized to manage electrical energy from vehicular PEMFCs to the electrical power grid instead of a conventional single-input dc-dc boost converter. In the dc-dc converter control, Incremental-Conductance (InC) maximum power point tracking (MPPT) method is utilized to extract maximum power from PEMFCs. Subsequently, the extracted electrical energy is supplied to the grid through a full-bridge inverter controlled by hysteresis pulse width modulation. The designed grid-support system supplied by vehicular PEMFCs in the ratings of 75 kW, 100 kW, and 125 kW are connected to local dynamic loads and analyzed for a 24-h operation. The minimum load consumption value is 84.6 kWh at midnight while load consumes at most 396.2 kWh during the daytime. Various connection situations of vehicular PEMFCs are considered to examine the energy flow analysis between vehicles and the grid/consumer side. A detailed economic analysis has been carried out by using hourly energy values in terms of load profile and generated energy to show the profit amount on the user side. While the cost of the energy consumed by the loads is calculated as €1004.8 without connection to the grid of FCEVs, the amount of profit obtained on the load side is measured as €943.9 with the connection.

Large-Signal Stability Analysis of DC Distribution Systems With Cascading Converter Structure

DC-DC converters are major components of the DC distribution systems. The converters interface with external power inputs, internal DC buses and loadings of subsystems. The interfacing DC-DC converters should be stable locally and globally under mutual interactions through a DC bus within the system. Current research efforts have focused on the analysis of the stability of the DC distribution system subject to small-signal disturbance. However, in practice, the system routinely operates under large-signal disturbances, such as when an additional subsystem is turned on after being connected to the DC bus. In this scenario, the small-signal model may fail to fully describe the dynamics of the system. In this paper, we identify and analyze the bifurcation process when the system undergoes abrupt load changes. According to the nonlinear operation of the interconnected system, a large-signal stability criterion is derived. This criterion is simple, and can be easily extended to multiple connected converter systems. The criterion is also consistent with the result from bifurcation analysis. Finally, the validity of the proposed criterion is verified by the full-circuit simulations and the experimental works.

A Universal Parametric Modeling Framework for Electric Machine Design

At present, the majority of electric machine design software employs its own unique machine data structure. However, when users need to transfer their designs between software, they are often faced with significant obstacles or cannot obtain a parametric model suitable for optimization. In order to solve this issue, a universal parametric modeling framework is proposed for electric machine design. The geometric structure is strictly constrained to ensure that the model will not interfere with each part because of the randomness of input parameters. A data structure consisting of points, lines, and surfaces is constructed, and a conversion interface for parametric modeling with different software is established. Consequently, this universal framework can automatically generate parametric models appropriate for different finite element analysis (FEA) software according to the input parameters. The framework is especially convenient for users who need to design or optimize an electric machine, particularly when FEA software is required for verification. Numerical verification is performed using different software based on interior permanent magnet (IPM) synchronous machines to demonstrate the effectiveness of the framework.

A virtual inertial control strategy for bidirectional interface converters in hybrid microgrid

Insufficient inertia is one of the urgent problems to be solved in the stability of AC-DC hybrid microgrid. In order to improve AC bus frequency and DC bus voltage inertia in hybrid microgrid, a virtual inertia control strategy for bidirectional interface converter (BIC) based on virtual synchronous generator (VSG) is proposed. The virtual inertia equations on both sides of the AC and DC are used to slow down the variation of the DC voltage and the AC frequency. When the load fluctuates, the dynamic response of the DC voltage, the AC frequency and the power transmission between the AC and DC subnets is improved, thus improving the stability of the system. This control strategy enables BICs to share active power equally under stable conditions, prevents circulating power, and achieves accurate power sharing among parallel BICs. The small signal model of BIC under virtual inertia control is established, the dynamic characteristics of the system under different control parameters are analyzed, and the influence of the control parameters on the system is discussed. The simulation model is established in PSCAD/EMTDC software to verify the correctness of the proposed control strategy.

Modeling and adaptive control strategy of hybrid microgrid based on virtual synchronous generator

AbstractAiming at large system operation fluctuations caused by the technical control of virtual synchronous generators, this article studies the introduction of interface converter control power, builds a virtual synchronous generator (VSG)‐based hybrid microgrid model and adaptive control strategy. Finally it optimizes it with fuzzy logic to obtain an fuzzy logic controller (FLC) based adaptive VSG control strategy. The experimental results show that under the FLC‐based adaptive VSG control strategy, in the reverse current mode, the system regression time is 0.37 s, and the DC bus voltage is 6.5 V; In the rectification mode, the system regression time is 0.49 s, and the DC bus voltage is 2.1 V. The results obtained are faster than the traditional VSG control strategy, and the DC bus voltage is 42.48%–68.66% lower. In summary, the suggested control approach is effective and reliable under the two operation modes, which can make the system operate safely and stably.