Development of a Geographically Distributed Real-Time Test Facility

Power Hardware in the Loop (PHIL) systems are used to test a power system with the help of combined software and hardware. Generally, to construct a PHIL system, a switched-mode power amplifier that has a stable performance is used, because of their large, linear signal control-to-output characteristics. However, the fundamental limitations of a switch-mode power amplifier (PA) are the dynamic performance and output bandwidth. In this paper, a compound controller has been used for the rectifier part of a PA, which can ensure the stability of a PA under transient or fault operating conditions. Moreover, a compound controller, which involves a feed-forward controller, a proportional controller and a repetitive controller, is proposed in the inverter part of a PA, and it can be used for PHIL applications. Experimental results are obtained under various operating conditions, such as transient responses under load step change, and output voltage bandwidth testing for a PHIL system, it is concluded that a proposed switched-mode power amplifier is useful for the PHIL system.

Testing battery pack configurations for their performance under different dynamic load profiles for grid and electric vehicle applications is expensive. Lowering the cost to understand the response of packs and their control strategies is critical. Power hardware in the loop (PHIL) simulation is widely used in power engineering for system and component testing. A simulator computes the model output in real-time, and then controls a power source to generate a dynamic power output with the expected current and voltage response of the emulated battery pack. This emulated battery pack power output can be coupled to a physical load to perform testing.1 Small time steps are useful to observe the transient response of the emulated battery when there is a sudden change in the load. PHIL simulations can also be useful to study the transient response of controllers and inverters present in the battery management system by connecting these devices to the simulator. PHIL simulations can be used to test the model’s accuracy2, to conduct repeatability experiments and to test battery performance under extreme conditions without compromising on safety.3 It provides an efficient approach to designing and testing new configurations of batteries from data of a single cell without building their real prototypes. The computational speed required to solve the battery models chosen for PHIL simulations must be fast in order to achieve real-time implementation. Therefore, models chosen for these simulations tend to have less complexity. However, to provide a better understanding of a battery’s response under a specific load profile, it is necessary to use a model that that accurately represents the behavior of a real battery. Real-time simulations for physics-based battery models have been explored in the past.4 , 5 , 6 It is also essential to comprehend how different battery architectures and how aging affects the overall performance. In literature, equivalent circuit models that describe charge transfer and diffusion dynamics have been used as the main way to capture battery dynamics.7 , 8 We first show results generated using SIMULINK equivalent circuit models that are compiled to run fast on our Opal-RT real-time simulator. The Opal-RT simulator drives an AMETEK 40 kW power supply with feedback to the model, enabling an emulated battery pack response capable of 10ms dynamic control. We evaluate pack configurations with physical parameters that correspond to either LCO or NMC 18650 cells. Overall, this represents a 400V, 10kW pack. A programmable load is used to modulate the emulated battery pack and monitor its dynamic response. We further explore implementing single particle models with our PHIL simulations to help understand the internal dynamics of the cell captured by these models. Physics-based models have rarely been used for PHIL. Our results show that the PHIL emulation of the battery pack meets the expectations for the battery dynamics. However, we observe high frequency noise in the output signal of the emulated battery pack. Because this level of noise is not a trait present in real battery packs, we are exploring signal processing methods to filter and remove it, while retaining the essential dynamics of the emulated battery pack. References A. Viehweider, G. Lauss, and L. Felix, Simul. Model. Pract. Theory, 19, 1699–1708 (2011).Y. He, W. Liu, and B. J. Koch, J. Power Sources, 195, 2969–2974 (2010).H. Dai, X. Zhang, X. Wei, Z. Sun, J. Wang, and F. Hu, Electr. Power Energy Syst., 52, 174–184 (2013).P. W. C. Northrop, V. Ramadesigan, S. De, and V. R. Subramanian, J. Electrochem. Soc., 158, A1461 (2011).V. R. Subramanian, V. Boovaragavan, V. Ramadesigan, and M. Arabandi, J. Electrochem. Soc., 156, A260 (2009).P. W. C. Northrop, V. Suthar, Bharatkumar Ramadesigan, S. Santhanagopalan, R. D. Braatz, and V. R. Subramanian, J. Electrochem. Soc., 161, E3149 (2014).J. V. Barreras, C. Fleischer, A. E. Christensen, M. Swierczynski, E. Schaltz, S. J. Andreasen, and D. U. Sauer, IEEE Trans. Ind. Appl., 52, 5086–5099 (2016).H. Song, T. Kim, J. Jeong, B. Kim, D. Shin, B. Lee, and H. Heo, IET Power Electron., 6, 417–424 (2013).

The inverter impedance estimation is an integral part of the practical application of the impedance-based stability assessment. Now the question arises about the validity of the estimated impedances, due to disturbances in the measurement and the estimation error of the system identification algorithm. In this paper, a practical approach to determine the validity of the estimated impedance by determining the stability limits of a power hardware in the loop (PHIL) setup is proposed. For this purpose, the dynamic behaviour of all components in the PHIL-setup is determined. To confirm the functionality of the proposed method, it is used to validate the estimated impedance of a Cinergia EL15-AC&DC dynamic load in the laboratory.

The aim of this paper is to propose a protection strategy for the voltage generator based inverter against the large load currents. This strategy proposes an algorithm for generators output current limiting. It depends on decreasing the amplitude of the voltage reference in case of over current on generator output current. We aim to give the source a behavior similar to that of a voltage source in series with a virtual resistance. This resistance is activated only above a certain current threshold. Simulation results for the application of this strategy on resistive and resistive-inductive load will be demonstrated, in this paper. The effectiveness of the proposed current limiting method was tested on high load current resulting from the asynchronous motor startup. The last part will discuss the implementation of this current limiting strategy on real time simulation environment RT-LAB. An experimentation using Power Hardware in the Loop and realtime simulation was realized to verify the theoretical analysis.

The electrification of the mobility sector comes with multiple challenges such as the lack of information on when, where, how long and how fast charging processes of electric vehicles will take place. In order to keep up with increasing power demand of charging processes, besides better predictions also the active control of charging processes will be necessary to minimize infrastructure costs. This work deals with a real-time mechanism for supporting the Power Quality (PQ) in electric distribution grids in terms of congestion and voltage management. In the paper, we propose a distributed smart charging approach that considers real-time conditions of the distribution grid provided by an event-driven architecture that collects data from different points in the grid. Our approach adopts the traffic light model, which allows smooth changing of the charging power to avoid drastic changes of the grid state. In order to be ready for real-world application, the algorithm is validated by a series of experiments on two setups: Pure software (co-)simulation and Power Hardware In the Loop (PHIL) where physical charging stations and electric cars are controlled in a laboratory setup.

A comprehensive state-space model of two-stage grid-connected PV systems in transient network analysis

This paper deals with an experimental performance assessment of the participation of wind farms to grid primary frequency control by considering an isolated power system. The French Guadeloupe island is chosen as a case study. The experimental work consists of applying a Power Hardware In the Loop (PHIL) process : a wind farm is emulated by real electrical equipments and connected to the Guadeloupe power grid which is simulated in a RT-Lab realtime simulation environment. Obtained results illustrate the contribution of wind turbines to enhance frequency behavior after a power disturbance.

This paper presents a novel low-cost and highperformance Power Hardware in the Loop (PHIL) test system for electric motor emulation and automotive traction inverter testing. The proposed PHIL test setup utilizes a simple back-toback configuration with a shared DC link, eliminating the need for a full-power voltage source or additional DC/DC converter. Furthermore, no multiphase multilevel converter or increased switching frequency is required. Thus, it greatly reduces the overall system cost and space consumption. The primary innovation lies in a new control methodology that ensures stability, accuracy, and high dynamic response. It guarantees high performance despite the low-cost setup. With a real-time motor model running at 5 MHz on an FPGA, the PHIL test bench can emulate an arbitrary PMSM with nonlinear characteristics including saturation and cross saturation. Full-power tests for both stationary and transient operation states have been conducted. Experimental results prove the feasibility as well as the outstanding performance of the proposed PHIL test system.

Testing power electronic converters of PMSM servo systems under realistic operating conditions usually comprise a costly and complicated process. Paper presents a power hardware in-the-loop (PHIL) emulation system to overcome the difficulties. The proposed PHIL emulation system consists of a real-time simulator to calculate the PMSM behaviors and a bidirectional AC/DC/AC converter to emulate the characteristics of machine interfaces and control power flow between the device under test (DUT) and the emulation system. Different loads and operating conditions can be readily simulated by changing the parameters of models in real-time simulator. Paper describes the concept of this system and presents the experimental results obtained using the prototype.

Hardware in the loop (HIL) simulation, especially power HIL (PHIL) simulation, is a promising tool for motor drive design and prototyping. It inherits both the flexibility of simulation and the authenticity of hardware itself, which therefore allow an actual motor drive design to be thoroughly scrutinized under almost any conceivable condition. In this paper, a unique 5 MW PHIL simulation facility which is in its last stage of commissioning in the Center for Advanced Power Systems (CAPS) is introduced. An illustrative PHIL simulation example based on a similar but downscaled 50 kW test bed is performed. Interesting results very well demonstrates how a PHIL simulation on a motor drive system can expose the hidden problems that are difficult to be identified by other testing methods.

Power-hardware-in-the-loop (PHIL) simulation enables the testing of an electrical load virtually exchanging power with a real-time simulator. PHIL extends the applicability of the traditional hardware-in-the-loop (HIL) simulation, which involves only signal exchange. The main challenge of this power exchange is the requirement for a highly dynamic power electronics interface. In this paper, PHIL simulation is used to test a nonlinear load to analyze its impact on existing electrical systems, A multiagent platform is also used to monitor the behavior of the system under study: the monitoring system is used to validate on-line the PHIL, verifying that the interface does not significantly affect the system behavior. Significant industrial applications of the procedure are also discussed

Power-hardware-in-the-loop (PHIL) platforms are gaining increasing attention as a valid solution for testing of converters operating in power electronics systems. Complex systems of significant power are difficult to validate experimentally in the laboratory. When, in such contexts, the device under test (DUT) is represented by a power converter designed to supply a variable speed drive (VSD), the electrical machine can be emulated through the PHIL platform. However, emulation of electrical machines imposes several requirements to the design of the PHIL test platform. Indeed, the emulable range of the machine operating points is constrained by the choice of the dc-bus voltage and of the coupling network. Furthermore, coupling network sizing strongly affects the stability of the emulation. In this article, the analytical relation between the coupling network, the emulator dc-bus voltage, and the machine operating range is described. A design procedure is then derived for both the dc-bus voltage and the coupling network. Afterward, the stability analysis is carried out to determine the stability characteristic of the PHIL emulation as a function of the coupling network choice and of the main parameters of the DUT control loop. The FPGA implementation of the PHIL is then described. Simulation and experimental results show the capability of the proposed implementation, with respect to both transient and steady-state machine emulation.

Power-hardware-in-the-loop (PHIL) simulation is a scenario where a simulation environment virtually exchanges power with real hardware, in contrast to the usual case in hardware-in-the-loop (HIL) simulation, which involves only signal exchange. In this paper, a novel interface for PHIL simulation is proposed and implemented. This new interface addresses some of the stability issues typically present in this kind of application. A complete PHIL experiment is then performed with the new interface, and the experimental results are presented.

The world's energy paradigm continues to undergo a rapid shift towards an increased use of renewable energy sources. To support this shift, an advanced electric power system architecture is being implemented by many electric utilities, interconnected with new distributed energy resources. As these new installations occur, it is essential to verify that their grid interconnection systems (ICS) conform to the relevant grid interconnection standards and that they perform satisfactorily under a variety of variable resource input and grid output conditions. This paper describes a Grid Interconnection System Evaluator (GISE) that leverages hardware-in-the-loop (HIL) simulation techniques to rapidly evaluate the grid interconnection standard conformance of an ICS according to the procedures in IEEE Std 1547.1TM. The architecture and test sequencing of this evaluation tool, along with a set of representative ICS test results from three different photovoltaic (PV) inverters, are presented. The GISE adds to the National Renewable Energy Laboratory's (NREL) evaluation platform that now allows for rapid development of ICS control algorithms using controller HIL (CHIL) techniques, the ability to test the dc input characteristics of PV-based ICSs through the use of a PV simulator capable of simulating real-world dynamics using power HIL (PHIL), and evaluation of the grid interconnection conformance of an ICS.

The bidirectional dc-dc converter, being the interface between Energy Storage Element (ESE) and DC bus, is an essential component of the power management system for vehicle applications including electric vehicle (EV), hybrid electric vehicle (HEV), and fuel cell vehicle (FCV). In this paper, a novel multiphase bidirectional dc-dc converter interfacing with battery to supply and absorb the electric energy in the FCV system was studied with the help of real time digital simulator (RTDS). The mathematical models of fuel cell, battery and dc-dc converter were derived. A power management strategy was developed and first simulated in RTDS. A Power Hardware-In-the-Loop (PHIL) simulation using RTDS is then presented. The main challenge of this PHIL is the requirement for a highly dynamic bidirectional Simulation-Stimulation (Sim-Stim) interface. This paper describes three different interface algorithms. The closed-loop stability of the resulting PHIL system is analyzed in terms of time delay and sampling rate. A prototype bidirectional Sim-Stim interface is designed to implement the PHIL simulation.