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This talk will discuss methods to implement different topologies of DC Microgrids.
Synchrophasor measurement technology is based on calculation of phasors obtained from Phasor Measurement Units. This technology is used in several countries to get better observability of electric systems. CEPEL’s Synchronous Phase Measurement Laboratory (LabPMU), in Cidade Universitária, Rio de Janeiro, RJ, is a laboratory infrastructure conceived to provide performance tests of PMUs and research on applications based on this technology. One relevant project carried out at LabPMU is to use Fractional Cycle Digital Fourier Transform Algorithm for Phasor Measurement Units (FC-DFT). This project aims to achieve faster PMUs, regarding the increasing presence of power electronics interfaced resources in power system generation and transmission. The presentation will show power electronic electrical simulations using HYPERSIM, in order to show the benefits of the algorithm. Two different simulation circuits were used: an HVDC multi-infeed circuit, as that arrangement is extensively used in the world, especially in Brazil; and a simulation of a distribution circuit provided with a PV array connected to the distribution electrical system through a converter (switching function model). Some occurrences of the power electronics equipment are simulated, and the results are the input of the FC-PMU. The FC-DFT results are then analyzed, showing that the equipment may deliver beneficial information for the control system operator and for early forensic analysis.
CENER has developed an EMS to manage either microgrids or renewable generation plants hybridized with energy storage systems. Its first prototype has been validated at its facilities in the ATENEA microgrid, which have been previously simulated through RT-LAB using a OP4510 target.
The EMS consists of a SCADA where the user can configure almost any plant based on renewable generation systems, loads, electric vehicle, connection to utility grid, gen-set and different types of energy storage systems. Also, the EMS lets the user select between several strategies and plant control depending on the configuration chosen before and their interests.
Since the study focuses on the ATENEA microgrid, which is composed of lithium, flow and lead-acid energy storage systems, a gen-set, programmable loads, one electric car, solar generation and grid connection, this system has been modelled and then simulated in an OPAL-RT target.
Through a previous process of validation of every model as well as the communication system with the EMS, the built system allows to design, adjust, and validate the strategies and control systems before testing them in ATENEA.
The development process of the microgrid controller (MGC) is that we first develop the controlling function in C that matches with the SIL preliminary algorithm developed by OPAL-RT/HYPERSIM. Secondly, a real HIL lightweight IED controller based on an iec61850 library is developed. Thirdly, we then test both the developed algorithm and the lightweight IED controller via various simulation scenarios. We perform testing scenarios of a developed MGS in a microgrid cyber-physical simulation subject to cyber-attacks in our lab. These testing are designed through performing two MGC testing scenarios. First, a delay attack is implemented, when the microgrid is islanded–the MGC monitors whole MG circuit breakers (CBs) specifically in this scenario—and the PCC CB should disconnect Load 4. Secondly, we test a packet manipulation on a measured data attack. External MGC HIL monitors the power generation as well as load consumption, in case (no balance) a trip command is issued to disconnect Load 3 via GOOSE. We then provide this development procedure for HIL MGC, which can communicate with the real-time simulator’s HYPERSIM simulation model over IEC 61850 GOOSE, as well as run the designed intelligent controlling algorithm and send the dispatching signal back to the real-time simulator model.
Low-inertia power systems can experience high rates of change of frequency and large frequency deviations during power imbalances. Inertia emulation using high power density storage systems such as a Flywheel Energy Storage System (FESS), can help limit the rate of change of frequency following sudden changes in generation or demand. In this presentation, a new adaptive inertia emulation controller for a high-speed FESS is proposed. To validate the behavior of the FESS with the proposed control design, the controller is implemented on a real 60 kW high-speed FESS, using the concept of rapid control prototyping. The performance of the FESS, equipped with the adaptive inertia emulation controller, is evaluated by means of Power Hardware-in-the-Loop (PHIL) simulations using the real-time simulation model of a low voltage microgrid. To reduce the overall loop delay, the established PHIL setup uses fiber optic connections to the power amplifier and several I/O expansion units. The State-space Nodal (SSN) solver is also applied to reduce the simulation time step of the microgrid model. The results of PHIL simulation show that the FESS with the newly-proposed adaptive inertia emulation controller outperforms the previously-suggested adaptive control designs, in terms of reducing the maximum rate of change of frequency and limiting the maximum frequency deviation, while not demanding significantly more energy from the FESS.
Modular Multilevel Cascaded Converters (MMCC) have attracted considerable attention from the power electronic and drive research community since their introduction at the beginning of 2000. Originally, MMCCs were proposed for High-Voltage Direct Current (HVDC) transmission systems. Still, recently, they have been introduced into other fields, e.g., static compensators, wind energy conversion systems, and motor drives.
Among MMCCs, the Modular Multilevel Converter (M2C) is a well-established topology used extensively for HVDC transmission. However, the M2C has some difficulties in achieving good performance in applications where the electrical machine operates at a very low speed.
Therefore, other MMCC topologies, such as the Hexverter, the Modular Multilevel Matrix Converter, the Series-Shunt MMCC have been studied in the last few years. However, novel converters require complex implementations and control strategies that have hindered the number of works where experimental results of these topologies are reported.
In this context, this presentation introduces a joint project lead by the University of Santiago of Chile, in collaboration with OPAL-RT and Conecta Engineering, where a reconfigurable MMCC composed of 120 power modules is implemented using OPAL-RT MMCC modules. Thus, the testbed can perform rapid control prototyping testing and Power Hardware in The Loop analyses of novel topologies such as M3C, Hexverter and other novel topologies.
Smart grid applications, especially those focusing on the coordination of distributed flexibilities, include many devices governed by increasingly complex software architectures, all linked together by communication technology. In theory, some of these applications would have the potential to revolutionize the way the grid is being operated. However, in practice they are met with skepticism due to the uncertainties and vulnerabilities that these systems might introduce. Therefore, exhaustive testing and validation steps need to be undertaken before deployment to guarantee reliability. Approaching this task manually is extremely time-consuming and error prone. In this presentation we show an approach to automatically generate cyber-physical test beds which allow the evaluation of such applications. The proposed method uses PSAL (Power System Automation Language) to describe the cyber-physical system under test, i.e., the electrical network, the sensors, the actuators, as well as the various controllers/software components and their interconnections. Several model generators parse the PSAL code, and they automatically build a real-time simulation of the physical system; they establish various interfaces for the controllers to interact with the sensors and actuators; they package the controllers and deploy them to their designated locations; and they configure the data collection framework to enable the recording and analysis of experiment data.
The success of EVs depends on the charging infrastructure. Due to different charging standards, it is difficult for EV manufacturers to rely on any one standard. Therefore, there is a need to design a charging system which can fit in many charging protocols. This presentation will give an insight into the different charging standards and their probable solutions.
This paper presents the design and development of a wind turbine emulator (WTE), based on a separately excited DC motor, using an OPAL-RT digital simulator. The power-motor speed characteristics for different armature voltages in the motor are like the power-turbine speed characteristics for varying wind speeds in the turbine. WTE is a power electronic step-down chopper that is interfaced with a mathematical model of wind turbine present in the RT simulator. The wind turbine model generates a reference armature current that is compared with the actual armature current of the motor. The PI controller is used here to minimize the current error and provides a desired switching pulse to the MOSFET. The laboratory setup consists of a WTE that is coupled to a three-phase permanent magnet synchronous generator (PMSG) as a standalone system. The turbine model and PMSG model are presented in this paper. The effectiveness of this RT-LAB-based WTE is verified by simulation and experimental results under various wind speed and load change conditions.
Precision is the most important aspect for designing, controlling, or validating any power system—and due to this, real-time simulation is growing. Especially in design, it allows accurate modeling of a system, which is the baseline of design. Therefore, in this work, a switching function-based model of a three-phase voltage source inverter is transformed into a real-time model using OPAL-RT’s real time simulator (OP4510) with hardware-in-the-loop technology for its implementation in an actual power system. For the validation of its behavior in real time, it has been compared to the detailed inverter model having the same input variables and control dynamics. The results reveal that the proposed inverter model keeps the total harmonic distortion within limits as per the latest grid code and, at the same time, it maintains the required accuracy for the system. Further, this work shows the importance of real-time simulation by comparing its mode of simulation with other offline modes of simulations such as normal, accelerator and rapid accelerator.
This work proposes an interfacing technique that uses the built-in three-phase transmission line models available in simulation platforms to perform Root Mean Square (RMS)-Electromagnetic Transient (EMT) real-time, multi-domain and multi-rate co-simulation. The main objective of this paper is to show the application of this kind of simulation in hardware-in-the-loop (HIL) testing of protective relays. Two well-known platforms are considered in this work: OPAL-RT with its ePHASORSIM tool is used for RMS simulation, and RTDS is used for EMT simulation. However, the proposed technique is sufficiently general to be applied to other real-time simulation platforms that have similar built-in transmission line models. To convert waveforms to phasors, a non-buffered rapid curve fitting method was implemented to attend to real-time constraints. During the testing phase of this research, tests for the HIL were completed using an actual transmission line protection relay. The presented results of tests highlight the benefits of the proposed interfacing technique.
With the increasing level of penetration of renewable production and the need for long-distance energy transport, Multi-Terminal DC grids (MTDC) have become a crucial field of research for the future development of wide-scale DC grids.
These MTDC grids pose several technical challenges: protecting the DC grid against electrical faults; transforming DC voltage; and controlling the flow of energy in a meshed system. The possible technical solutions and new technologies addressing these issues need to be assessed through real-time and HIL simulations to demonstrate the system’s performance.
With that perspective, an MTDC HIL test bench is being developed at the Supergrid Institute to test and validate any proposed control and protection solution.
On this HIL setup, several Raspberry PIs are used to simulate in real time the different IEDs of the system: protection relays, station supervisors, DC Grid Control. These IEDs communicate with each other and with the electrical model using the IEC61850 communication protocol.
The electrical benchmark is a 4 Terminal DC Grid, modelled with HYPERSIM and running in real time with an OP5700 simulator.
The HYPERSIM model uses a Graphical User Interface (GUI), coded in Python and using the Python API provided by HYPERSIM. This interface allows a user to interact with the electrical system: launch a start-up sequence to connect the DC Grid, simulate a fault to test the implemented protection strategy.
The distribution system has undergone tremendous upgrades that have leaned toward a more carbon-free, reliable, and resilient infrastructure. This has been made possible by incorporating more sophisticated controllers in conventional generation, smart inverters based distributed generation, automatic load regulators, seamless interfacing of mini, micro and nano grids etc. To the contrary, the system is exposed to different events resulting from intermittent generation, as well as the unpredictable and uncertain behavior of loads in distribution networks. Real-time digital simulators from OPAL-RT let the power professionals study these events through digital twin models and by tweaking system parameters to create diverse and disruptive steady, dynamic, and transient event signatures–and also provides real datasets through the direct interface of sensors, PMUs, remote terminal units, smart measurement/meters, for testing and validating the AI-centric data analytics. Online testing of data analytical tools is made easy through real-time simulators by OPAL-RT as it has dedicated input and output digital/analog channels for export/import signals from/to power system models and supports standard communication protocols such as DNP3, C31.118-2011, etc. This presentation revolves around the wide usage of OPAL-RT’s real-time digital simulations in prospective testing environments of data analytics through real and simulated distribution phasor measurement units. Actual case studies are emphasized in the presentation.
Wide Area Monitoring and Smart Automation (WAMSA) is today’s innovative research area under smart grid execution to overcome real-time protection difficulties. Modern communications and information processing technologies offer outstanding real-time benefits. The development of big data applications and satellite uplinks are rapidly changing. Several new measurement devices are being incorporated into an advanced smart grid metering infrastructure. In this process, PMUs can sense, converting signals from voltage and current into digital form under real-time wide-area monitoring systems. In modern power systems’ real-time applications point of view, big data analytics are playing a vital role with increasingly popular technological concept that contains smart electricity facilities, for instance, smart power control, energy utilization, and management. Initially, it emphasized smart grids, modern data analytics, massive-scale information control, and reliable monitoring methods with the extreme size of data required. This paper summarizes the PMU setup and installation overview in the Unified Real-time Dynamic State Measurement project (URTDSM) with the synchrophasor based wide-area monitoring system in India. The novelty of this presentation is to focus on big data potential functions and practices like fault detection, transient stability, load forecasting, and power quality monitoring into real-time wide-area monitoring.
Part 1: The global power system’s transition to nearly 100% renewable-based generation presents new challenges not only in terms of control strategies but also in terms of tools required to perform HIL simulations. In this context, conventional generators such as synchronous machines may be gradually replaced by power electronic converters or similar generation units. HIL simulation setups of large grid models with multiple switching inverters are a challenge due to the high-level of accuracy required. The coupling of the power electronic domain with the network-level domain is currently the major issue to overcome. Two approaches are followed: the first one involves the coupling of the FPGA and the CPU model, while the second one uses the ARTEMiS library.
Part 2: Non-real-time or offline simulation methodologies using numerical solving techniques for network or component models have their limitations with respect to the necessity of high complexity. Therefore, they may prove insufficient with respect to resulting simulation accuracy or computation time. Real-time simulation based HIL simulation testing can overcome these issues, because physical hardware equipment, including the entire control system, is interlinked with the simulated network model via HIL interfaces. This enables natural coupling which guarantees the conservation of instantaneous power via the conservation of the through and across quantities at interfaces as exists in the real-world system.
Georg Lauss received the Dipl.-Ing. degree from the Johannes Kepler University JKU Linz, Austria, in 2006 and jointly from the Eidgenössischen Technischen Hochschule ETHZ, Zürich, Switzerland, and the Université Pierre-et-Marie-Curie, Paris, France. He is a researcher with the AIT Austrian Institute of Technology, Vienna, Austria. His main interests include electromagnetic systems, power electronics, system and control theory, mathematical methods for optimized control systems, hardware-in-the-loop simulation systems, and real-time simulation for electromagnetic power systems. Georg Lauss is the Chairman of the IEEE WG P2004 Recommended Practice for Hardware-inthe-Loop (HIL) Simulation Based Testing of Electric Power Apparatus and Controls and the IEEE PES Task Force on Real-Time Simulation of Power and Energy Systems.
The advancement of technology has allowed the exponential development of electric engineering applications, and several of these fields are: digital simulation in real-time in conjunction with synchro-phasor measurements in electrical power systems; the generation of data applying the Monte Carlo method; and the analysis of data by application of data mining techniques. Research on load-shedding schemes, together with the application of the above-mentioned fields, allows the prediction of certain events that have caused the disconnections of large amounts of load, and even the operating output (blackout) of large power systems, around the world.
The present project proposes a methodology for the implementation of a load shedding scheme as a function of voltage and frequency that allows, through an indicator, and by means of an indicator calculated in real time through a previously-trained regressor, to determine the amount of load to be disconnected after the occurrence of a contingency for loss of generation.
To do this, a comprehensive real-time digital simulation platform is implemented, which uses OPAL-RT’s ePHASORsim, together with the functionalities of CENACE’s WAMS system, WAProtector, to execute a Software in the loop (SIL) to perform adaptive load shedding in real time, triggered when the indicator condition calculated by the regressor previously-trained with simulation results obtained from PowerFactory is met.
Our UPS HIL Testbench presentation will focus on how we used OPAL-RT’s solution in the UPS HIL system design to speed up the product launch, as well as key parameters Gs Understanding and TSB bridge usage in the UPS HIL system.
Japan intends on attaining carbon neutrality before 2050, and offshore wind farms are one of the primary energy sources that will help to realize this ambition. Since the sea depth around Japan is more that 50m, facilities of transmission systems for offshore wind farms must be installed on floating platforms. Middle frequency (500Hz) convertors are a promising equipment that reduce the weight and volume of transformers used for substations on the floating platform. MMC is a solution that can operate at 500Hz with less switching loss. It however requires much system analysis to develop and tune the control system. Real-time simulators are a useful tool for small academic laboratories to study on MMC. It saves risks of hardware trouble caused by mis-operation of the control system. An example of studies–such as the fundamental operations of scaled models (200V, 1A) of MMC convertors, real time simulation for tuning of control systems, as well as harmonics studies in our laboratory–will be introduced in the presentation
Real-time Simulation for Sector-Coupling: Opportunity and Challenges