Real-time Emulation Research Articles

A Fast and Accurate Double-Precision Floating Point Format Paralleled Transient Emulator of AC/DC Grids on Heterogeneous CPU-FPGAs

The rapid development of power electronic devices and the complexity of large-scale power systems call for high fidelity real-time electromagnetic transient (EMT) emulators, which can achieve high precision, high accuracy, and real-time realization simultaneously. Compared with traditional emulators, the emulator that adopted high precision and accuracy brings huge amount of extra hardware resource consumption. Therefore, hardly any traditional field-programmable gate array (FPGA) based real-time emulators can achieve the real-time simulation of large-scale systems with restricted hardware resources. To resolve these issues, this article proposed a novel heterogeneous CPU-FPGA hybrid multirate EMT real-time emulator which supports double-precision floating-point format. Several efforts are made to enhance the simulation scale and accuracy of the emulator: 1) a multiple floating-point sets reduction module is proposed on hardware design to achieve small and real-time simulation step such as 2 <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex-math notation="LaTeX">$\mu$</tex-math></inline-formula> s; and 2) time division multiplexing strategy is conducted throughout the calculation to improve the supported simulation scale by 31%. Simulation results have validated that the one Xilinx VC709 FPGA board can achieve a small time-step of 2- <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex-math notation="LaTeX">$\mu$</tex-math></inline-formula> s real-time realization and the supported scale can be expanded to more than 600 node buses.

Complex Sil Testing of Type-1 Controller for Sssc in Real-Time Emulators

Complex Sil Testing of Type-1 Controller for Sssc in Real-Time Emulators

A Framework for Sensitivity Analysis of Real-Time Power Hardware-in-the-Loop (PHIL) Systems

Power hardware-in-the-loop (PHIL) simulation leverages the advanced real-time emulation based technique to carry out in-depth investigations on novel real-world power components. Power amplifiers, sensors, and signal conversion units based power interfaces (PI) incorporate physical hardware systems and real-time simulation platforms into PHIL setups. However, the employment of any interfacing technique inevitably introduces disturbances such as sensor noise, switching harmonics, or quantization noise to PHIL systems. To facilitate quantitatively analyzing and assessing the impact of external disturbances on PHIL simulation systems, a framework for sensitivity analysis of PHIL setups has been developed in this paper. Detailed modelling principles related to the sensitivity analysis of PHIL systems and the inherent relationship between sensitivity transfer functions and stability criteria are elaborated along with theoretical and experimental validation. Based on this concept, accuracy assessment methods are employed in this framework to quantify generic sensitivity criteria. Moreover, physical passive load and converter-based PHIL setups are applied and experimental results are presented to characterize and demonstrate the applicability of the proposed framework.

Enhanced dynamic performance of steam turbine driving synchronous generator emulator via adaptive fuzzy control

This paper deals with experimental verification of the applicability of an efficient adaptive fuzzy controller (AFC) aimed for enhancing the dynamic performance of a steam turbine driving synchronous generator under different operating conditions. Two controllers are developed to control the system, namely the recursive least square optimal controller (RLSOC) and the AFC. Both controllers are designed based on the linearized and the nonlinear models of the system respectively using LabVIEW™ software and hardware in the loop (HIL). The results show that the system stability is enhanced when applying the proposed AFC. The motivation of this research is to guide the industrial manufacturers and users of steam turbines of different rating and inertia for applying different tests at severe faulty and unstable conditions. Real time emulators recently became cost-effective solutions for testing dynamic system performance using new optimized control techniques due to the relatively high cost and weight of steam turbine.

Dynamic Modeling of a Proton-Exchange Membrane Fuel Cell Using a Gaussian Approach.

This paper proposes a Gaussian approach for the proton-exchange membrane fuel cell (PEMFC) model that estimates its voltage behavior from the operating current value. A multi-parametric Gaussian model and an unconstrained optimization formulation based on a conventional non-linear least squares optimizer is mainly considered. The model is tested using experimental data from the Ballard Nexa 1.2 kW fuel cell (FC). This methodology offers a promising approach for static and current-voltage, characteristic of the three regions of operation. A statistical study is developed to evaluate the effectiveness and superiority of the proposed FC Gaussian model compared with the Diffusive Global model and the Evolution Strategy. In addition, an approximation to the exponential function for a Gaussian model simplification can be used in systems that require real-time emulators or complex long-time simulations.

Hardware-in-the-loop real-time validation of fuel cell electric vehicle power system based on multi-stack fuel cell construction

This paper proposed a Fuel Cell Electric Vehicle (FCEV) power system model which was validated by Hardware-in-the-Loop (HIL) real-time emulation. Multi-stack Fuel Cell (MFC) system was used to increase the system redundancy. Nickel-metal Hydride (NiMH) battery pack (BAT) was selected as the secondary energy source. Dual-input single-output Boost converters were connected with MFC system to satisfy the voltage requirement of DC bus. Bi-directional Buck-Boost converter was connected with BAT and then both discharging and charging modes were controlled. Close loop control strategies were developed for converters to assure their stabilities. Rule-based Energy Management Strategy (REMS) was proposed to distribute the required power among Proton Membrane Exchange Fuel Cells (PEMFCs) and BAT. The proposed model was evaluated by HIL real-time emulation, using the Supplemental Federal Test Procedure US06 (SFTP-US06) driving cycle. MicroLabBox, in which real-time processor and Field Programmable Gate Array (FPGA) were embedded, was selected as the HIL real-time validation platform. The MFC system, BAT model, REMS and low-level controllers were executed by real-time processor while the converter general models were built in FPGA. According to the results, the proposed model and method effectively driven MFC system operating in high efficiency region and successfully kept BAT State of Charge (SOC) in the desired range.

Robust Control of a Class of Nonlinear Discrete-Time Systems: Design and Experimental Results on a Real-Time Emulator

The aim of this study is to develop a new observer-based stabilization strategy for a class of Lipschitz uncertain systems. This new strategy improves the performances of existing methods and ensures better convergence conditions. Sliding window approach involves previous estimated states and measurements in the observer and the control law structures which increase the number of decision variables in the constraint to be solved and offers less restrictive Linear Matrix Inequality (LMI) conditions. The established sufficient stability conditions are in the form of Bilinear Matrix Inequality (BMI) which is solved in two steps. First, by using a slack variable technique and an appropriate reformulation of the Young’s inequality. Second, by introducing a useful approach to transform the obtained constraint to a more suitable one easily tractable by standard software algorithms. A comparison with the standard case is provided to show the superiority of the proposed H∞ observer-based controller which offers greater degree of freedom. The accuracy and the potential of the proposed process are shown through real time implementation of the one-link flexible joint robot to ARDUINO UNO R3 device and numerical comparison with some existing results.

Genetic Algorithm Based PI Control with 12-Band Hysteresis Current Control of an Asymmetrical 13-Level Inverter

In this paper, a twelve-band hysteresis control is applied to a recent thirteen-level asymmetrical inverter topology by employing a robust proportional-integral (PI) controller whose parameters are decided online by genetic algorithm (GA). The asymmetrical inverter topology can generate thirteen levels of output voltage incorporating only ten switches and exhibits boosting capability. A 12-band hysteresis current control strategy is applied to ensure the satisfactory operation of the inverter. It is designed to provide a sinusoidal line current at the unity power factor. The tuning of the PI controller is achieved by a nature inspired GA. Comparative analysis of the results obtained after application of the GA and the conventional Ziegler–Nichols method is also performed. The efficacy of the proposed control on WE topology is substantiated in the MATLAB Simulink environment and was further validated through experimental/real-time implementation using DSC TMS320F28379D and Typhoon HIL real-time emulator (Typhoon-HIL-402).

Particle swarm optimization based sliding mode controllers for electric vehicle onboard charger

High-performance onboard chargers are needed to proliferate the popularity of electric vehicles considering the charging convenience and flexibility. In this study, a sliding mode controller (SMC) for power converters is presented to enhance the performance of the onboard battery charger. The SMC parameters are selected using the particle swarm optimization (PSO) algorithm. A two-stage charging topology is adopted with independent controllers. The grid side AC–DC converter mitigates the harmonic content in the grid current and smoothens the voltage and current in the dc bus. The bidirectional DC–DC converter at the battery side regulates the charging characteristics of the Li-ion battery with a constant current–constant voltage (CC–CV) profile. The steady-state and dynamic behavior of the charging system is presented. Hardware in the loop real-time emulator is utilized to confirm the validity of this study. Experiments show that optimization-based SMC contributes to the overall dynamic performance of the onboard battery charger.

Real-time Coordinated Scheduling for Cloud Radio Access Networks in a Software-only Environment using the OpenAirInterface Platform

The objective of this paper is to extend into the OpenAirInterface platform the Coordinated Scheduling (CS) technique to allocate resource blocks among User Equipment (UE) in a wisely way and to control the energy efficiency, the throughput, and the inter-cell interference for Cloud Radio Access Networks (C-RANs). It is achieved by modifying the OpenAirInterface scheduler code, increasing the Remote Radio Unit (RRU) scalability, and employing some component carriers of the Radio Cloud Center (RCC), each one them with one or more UEs. The hardware utilized is composed of general-purpose processors and fast Ethernet transport ports, and the software is recent frequency-domain methodologies in a software-only environment where the use of radio units are not required. However, the USRP B200 mini-i radio unit and the UE (Samsung Galaxy S8) were considered only for validation purposes. The emulations using frequency-domain methodologies, compatible with fourth and fifth-generation cellular systems, allowed real-time emulations and reduced 10-fold the multipath channel’s signal processing complexity compared to time-domain methodologies. The results show we can emulate a real-time static coordinated scheduling proof-of-concept for one C-RAN composed of one RCC, three RRUs, and three UEs. In the end, it is evaluated the reproducibility and the scalability of synthetic networks composed of one RRU and at least one UE, without using software-defined radio units, reducing prototyping uncertainties of the physical hardware and the total price of the experiment.

Real time emulator for parallel connected dual-PMSM sensorless control

&lt;p&gt;This paper presents a real-time emulator of a dual permanent magnet synchronous motor (PMSM) drive implemented on a field-programmable gate array (FPGA) board for supervision and observation purposes. In order to increase the reliability of the drive, a sensorless speed control method is proposed. This method allows replacing the physical sensor while guaranteeing a satisfactory operation even in faulty conditions. The novelty of the proposed approach consists of an FPGA implementation of an emulator to control the actual system. Hence, this emulator operates in real-time with actual system control in healthy or faulty mode. It gives an observation of the speed rotation in case of fault for the sake of continuity of service. The observation of the rotor position and the speed are achieved using the dSPACE DS52030D digital platform with a digital signal processor (DSP) associated with a Xilinx FPGA.&lt;/p&gt;

Hierarchical control and emulation of a wave energy hyperbaric converter

Wave energy emulators provide an option to extend studies of wave energy converters (WECs) in an electric power laboratory facility and to evaluate the performance of controllers in an experimental set-up. In addition, the integration of control strategies in different steps of the energy conversion process is an important step to improve the WEC overall behaviour that has not yet been widely discussed. This paper proposes a real-time emulator and a hierarchical control scheme for a hyperbaric WEC consisting of floating bodies, hydropneumatic storage system (HSS), hydraulic turbine, and doubly fed induction generator (DFIG). The proposed emulator is based on a typical electric power laboratory facility, where a numerical model reproduces the dynamics of the wet subsystem and a hardware is the WEC electrical subsystem. Thereby, a squirrel-cage induction motor (SCIM) is coupled shaft-to-shaft with the DFIG. The SCIM reproduces the characteristics of torque and speed that would be observed in the real system, and then, the DFIG is subjected to a primary drive with same dynamic characteristics of the real plant. The hierarchical control integrates the generator and HSS controllers considering the optimal operating pressure for local sea state conditions. Experimental results illustrate the performance of the emulator and controllers.

Real-time hardware emulation of wind turbine model with asynchronous generator under hardware-in-the-loop platform

Abstract Renewable energy sources are becoming as one of the major generation strategies around the world. The wind energy systems have been technologically advanced and integrated to the power system in a rapid routine. This paper looks into the modelling as well as operational exploration of a three blade wind turbine connected to asynchronous generator. State-of-the-art wind turbine topologies and a comparative summary of real-time simulation technologies for electrical systems are described. A 2.4 MW wind turbine with three blades is modelled for the analysis of power characteristics. The shift from sub-synchronous to super-synchronous mode is analysed for type-A wind energy conversion system (WECS) with 2 MW asynchronous generator by using MATLAB/Simulink model. The step-by-step standard operating procedure for modelling and real-time simulation of 2 MW type-A WECS having asynchronous generator under hardware-in-the-loop platform is elucidated. The steady state and transient behaviours of the WECS are validated by the real-time emulation under a hardware-in-the-loop platform.

Real-Time Emulation of a Grid-Connected Wind Energy Conversion System Based Double Fed Induction Generator Configuration under Random Operating Modes

This paper presents the design, modeling, simulation and the experimental implementation of a 1.5 kW relatively low-cost wind energy conversion system (WECS) based on the double fed induction generator (DFIG) configuration. In the preliminary experiments, we test the DFIG power control under fixe speed by applying the vector control principle, then we insert the physical emulator presented in the controlled DC motor in order to simulate the static-dynamic behaviors of a real wind turbine with the use of the Tip Speed Ratio TSR based MPPT algorithm to extract the maximum available power on the emulator. The proposed structure is simulated using MATLAB Simulink environment, the obtained results are validated experimentally on our laboratory setup. We also develop an application with MATLAB AppDesigner that calculates the operating point of our system at steady state and visualize the power transfer, current, voltage and electromagnetic torque values of the DFIG and the DC motor before starting the stimulation or the experimental manipulation. The MPPT, the DC motor control and the DFIG power control algorithms are implanted in C, embedded on a dSPACE DS1104 control board. The obtained results confirm the reliability of the proposed WECS to manage all the probable operating modes, also the effectiveness of the physical simulator in the role of wind turbine emulation.

A Real-Time Real-Power Emulator for a Medium-Voltage High-Speed Electrical Drive: Discussion on Mechanical Vibrations

This article, based on modeling and scaling as well as simulation and experiment, provides a comprehensive discussion on a real-time real-power emulator for a medium-voltage, high-power, high-speed motor drive. A three-phase modular multilevel double-star chopper-cell (DSCC) inverter under test is connected in front-to-front (FTF) with the emulator. The DSCC inverter is the same in circuit configuration as the DSCC rectifier. This emulator is characterized by integrating mechanical dynamics of both motor and load into it. The power-electronic circuit of the emulator consists of a three-phase DSCC rectifier, three ac inductors, and a single two-winding common-mode inductor at the dc side. This article starts with modeling and scaling of a three-phase 6.6-kV 10.9-MW four-pole 9000-r/min induction motor drive. Then, the authors design, build, and test a three-phase 200-V 10-kW downscaled test bench. Experimental waveforms from the 10-kW test bench, as well as simulated waveforms from the 10.9-MW full-scale and 10-kW downscaled systems, lead to the following conclusion: The emulator can reproduce both electrical and mechanical dynamics of the three-phase 200-V, 10-kW, four-pole, 9000-r/min induction motor coupled with a centrifugal compressor.

Channel Models for Performance Evaluation of Wireless Systems in Railway Environments

In the automotive and rail domains, vehicles are entering the era of full automation thanks to wireless sensors and communication systems, shifting control functions from a human driver to computers. High data rate, robustness, high reliability and ultra-low latency wireless communications are required in the context of autonomous train and safety critical applications. Today, the Future Railway Mobile Communication System (FRMCS) is under development at European level within the International Union of Railways (UIC). This system will answer all the current and future needs of rail. It will be IP based, multi-bearer and resilient to technology evolution. In the context of the development of different FRMCS prototypes by industry, it is crucial to be able to test them in representative Railway radio environments thanks to laboratory tools. Characterization of radio channels in railway environments, by measurements or simulations, is a very active field. In this article, based on broad literature survey, we show that not all the published models are suitable for performance evaluation. Then, we propose a selection of typical Tapped-Delay-Line channel models to be implemented in an original hardware and software testing platform capable to reproduce the effect of representative Railway environments in laboratory, with real time emulation at RF (Radio Frequency) level. Preliminary results in Hilly 3 taps and Cutting 5 taps channel models are presented as a proof of concept of a “zero on site testing” approach, allowing for time and cost savings in the validation of railway communication systems.

Scalable Real-Time Emulation of 5G Networks With Simu5G

Real-time emulation of 5G networks is highly beneficial for several purposes, such as prototyping or performance evaluation of distributed applications meant to run on 5G networks, research demonstration, evaluation of other technologies (e.g., Multi-access Edge Computing) meant to interoperate with 5G access. In this work, we describe how to use Simu5G, a new end-to-end simulator of 5G networks based on OMNeT++, as a real-time emulator. We describe in detail the modeling choices that allow emulation to scale up without compromising accuracy. We present a thorough evaluation of the Simu5G’s emulation capabilities, showing that networks with hundreds of simulated users and tens of cells can be emulated on a single desktop machine.

Corrections to “Real-Time Vehicular Wireless System-Level Simulation”

In the above article [1] , we discovered an error in the specific version of the AIT real-time channel emulator [2] used for this article. The imaginary part of the channel impulse response was divided by 4, while the real part of the channel impulse response was correct. This was due to a mistake in the conversion from fixed point format 16.16 bits to 14.18 bits in the imaginary part of the discrete prolate spheroidal sequence coefficients. Hence, for Section V in [1] , the following errata list appliesThe complete article including all corrections can be found on arXiv https://arxiv.org/abs/2012.12331 :

Evaluation of Model-Based Biomimetic Control of Prosthetic Finger Force for Grasp.

Restoring neuromuscular reflex properties in the control of a prosthetic hand may potentially approach human-level grasp functions in the prosthetic hand. Previous studies have confirmed the feasibility of real-time emulation of a monosynaptic spinal reflex loop for prosthetic control. This study continues to explore how well the biomimetic controller could enable the amputee to perform force-control tasks that required both strength and error-tolerance. The biomimetic controller was programmed on a neuromorphic chip for real-time emulation of reflex. The model-calculated force of finger flexor was used to drive a torque motor, which pulled a tendon that flexed prosthetic fingers. Force control ability was evaluated in a "press-without-break" task, which required participants to press a force transducer toward a target level, but never exceeding a breakage threshold. The same task was tested either with the index finger or the full hand; the performance of the biomimetic controller was compared to a proportional linear feedback (PLF) controller, and the contralateral normal hand. Data from finger pressing task in 5 amputees showed that the biomimetic controller and the PLF controller achieved 95.8% and 66.9% the performance of contralateral finger in success rate; 50.0% and 25.1% in stability of force control; 59.9% and 42.8% in information throughput; and 51.5% and 38.4% in completion time. The biomimetic controller outperformed the PLF controller in all performance indices. Similar trends were observed with full-hand grasp task. The biomimetic controller exhibited capacity and behavior closer to contralateral normal hand. Results suggest that incorporating neuromuscular reflex properties in the biomimetic controller may provide human-like capacity of force regulation, which may enhance motor performance of amputees operating a tendon-driven prosthetic hand.

Hybrid Microgrid: Energy Management under Different Loading Condition using Typhoon HIL’s Real-time Digital Simulator

This paper presents real time simulation of hybrid microgrid consist AC microgrid along with DC microgrid and utility grid, where developed Hill Climbing algorithm for even power transfer between AC microgrid plus DC microgrid ensuring stable and reliable system operation under different loading conditions. Also generalized function generated to deal with the power flow from utility grid to AC microgrid and DC microgrid. Typhoon HIL control centre used for the accomplishment of hybrid micro grid. The proposed system is developed in the Schematic Editor. Hybrid microgrids are simulated using the real-time emulator HIL402 for real-time simulation within the SCADA environment.