Enhancing power quality in electrical distribution systems using a smart charging architecture

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).

Europe’s electric power network is entering a period of extreme flux as we move to an era where it is dominated by non-linear, asynchronous generation such as wind power plants. The rapid rise of new technologies in this space has led to increasingly complex interactions within the power network that are difficult to cover through traditional test regimes. Existing facilities are not fully equipped to address these new system orientated challenges and while investing in new sites and facilities is one way forward, this is likely to be prohibitively expensive and runs the risk of only being applicable to niche applications. This work presents the first stage in an alternative approach which seeks to address these challenges through the pooling of existing resources. In this concept, geographically distributed test facilities are combined virtually to create new capabilities and perform complex system level validations. This can be done through a Geographically Distributed – Power Hardware in the Loop (GD-PHIL) setup. To achieve this, each site requires a PHIL setup allowing the Device Under Test (DUT) to interact in real time with a simulation. This work will present the outcome of the first step towards the development of such a network, developing and demonstrating the stable communications interfaces necessary to link geographically distributed real time simulators from two different manufacturers.

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.

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

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 Power Hardware-in-the-Loop (PHIL) simulation can be used to determine the dynamic behaviour of renewable energy sources feeding into a grid before deployment. This article shows the necessary prerequisites for achieving stability of the simulation. It enlarges the range of SISO interfaces and introduces the MIMO PHIL simulation and the associated interfaces. A use case is shown with two photovoltaic inverters feeding into a low voltage distribution grid. In a lot of applications stability of the simulation can be judged beforehand by use of analytic concepts and a pure software simulation. This opens the way for a broad range of application for Power Hardware-in-the-Loop simulation studying the interaction component-grid-component.

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.

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.

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.

The proliferation of PV generation systems connected to electrical distribution systems (EDSs) brings many operational challenges, and within them, over-voltage issues are regarded as the most critical. Among all the strategies available to handle these over-voltage issues, those implemented locally at the PV inverters seem to be the more promising, considering their distributed and easy-to-implement features. In this paper, the feasibility and performance assessment of a commercial PV inverter for mitigating over-voltage events in an EDS is presented. To do this, an active and reactive droop-based voltage control strategy is implemented in a commercial inverter. Realtime power hardware-in-the-loop (PHIL) laboratory tests were performed to assess the PV inverter's efficiency when absorbing reactive power, as well as its interaction with the distribution grid. According to the obtained results, the PV inverter's efficiency was not noticeably affected by the changes in reactive power. Additionally, the PV inverter responded accordingly, following the voltage control strategy implemented, providing successfully the expected voltage support services.

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

Real-time simulation and its use in Hardware in the Loop and Power Hardware in the Loop testing may not be realized with one single hardware platform. Instead, multiple systems are needed to realistically address the analysis and testing needs of the smart grid. This is particularly the case when the target system is the future electrical distribution grid, with its multi-physic, hybrid nature, its pervasive power electronics and communication. The approach adopted at the authors' laboratory is presented to exemplify the interface and integration challenges when such platform is extended to realize relevant scenarios.

The main objective towards electrical-distribution system is to experience the consumer’s demands for energy later acquiring the huge electrical-energy from the transmission/substation. Various network compositions remain feasible to suit the needed supply reliability. Protection, control and supervising apparatus are implemented to empower the adequate process of distribution network. This effort mainly analyzes on 3phase, 3bus distribution system by introducing an UPQC with various load configurations. The outcomes are correlated as regards real-power, reactive power, voltage, current-THD. The Significance of the present work is to upgrade the quality of power for a 3-ph, 3-bus distribution network by introducing an UPQC with various load configurations.

In this paper the operation and control of battery-less hybrid systems for off-grid power supply is investigated. The load demand of the system is covered by a diesel-driven generator (DDG) and photovoltaic (PV) arrays. First, an overview of the features and operation of such systems is provided. Primary control of the system is investigated where the PV inverter curtails its active power in order to respect the minimum load ratio of the DDG and contribute to frequency control. Secondary control of the system is applied using the Hardware in the Loop (HIL) technique, where parts of the real-time simulation are replaced with actual physical components. Hardware controllable loads are activated by a hardware controller in order to respect the minimum load ratio of the DDG. An alternative method is applied where instead of controllable loads a hardware PV inverter curtails its active power production. The HIL simulation results show that both methods are effective to reduce the frequency deviation of the system and maintain the power output of the DDG above the predefined minimum requirement. The tests were performed with a combination of Controller HIL and Power HIL simulation leading to more realistic testing than Controller HIL simulation or pure digital simulation.