Wei Li

Real-time simulation of a Modular Multilevel Back-to-back HVDC System using RT-LAB

Publication date : Sep 2014
Paper File : Not available yet

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Author(s)

Weihua Wang, Jin Zhu, Wei Li, Yijun Zou,

Abstract

This paper demonstrates an advanced model based on the RT-LAB simulation platform, which is able to simulate a Modular Multilevel Back-to-back HVDC system for both steady-state operations and various contingencies in real time. This application takes advantages of the FPGA-based sub-microsecond model of the Modular Multilevel Converter (MMC) valves and combines it into the model of a Back-to-back HVDC link and adjacent AC networks using the State-space Nodal (SSN) solver. The real-time simulation is used to study the start-up and charging scheme, as well as the effectiveness of surge arrestors to mitigate the over-voltage of DC faults. Simulation results confirm the feasibility that the proposed model can be used to study the dynamic performance of Back-to-back MMC HVDC system.

Generic High Level VSC-HVDC Grid Controls and Test Systems for Offline and Real Time Simulation

Publication date : Aug 2014
Paper File : Generic High Level VSC-HVDC Grid Controls and test systems for offline and real time simulation.pdf



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Author(s)

Wei Li, Student Member, Naveed Ahmad Khan, Md. Rokibul Hasan, Luigi VANFRETTI,

Abstract

This article describes generic high level control models for VSC-HVDC grid systems. An average value model of the voltage source converter (VSC) is used; it includes the vector current control strategy. As an improvement to traditional conventional high-level control systems, this paper includes dc voltage, negative sequence current and dc voltage droop control loops. To validate the controller’s performances, two tests systems were developed: a point-to-point link and a four-terminal DC grid. Both offline and real-time simulations are carried out for several test scenarios. A methodology for calibrating controller parameters is presented and used to tune the controls of each test system considering the different scenarios presented. All simulation models were developed in SimPowerSystem/Simulink and prepared using the RT-LAB software from OPAL-RT for real-time simulation; real-time simulation performance of the simulation models is also discussed

Modular Multilevel Converter Model Implemented in FPGA for HIL Test of Industrial Controllers

Publication date : Aug 2014
Paper File : Modular Multilevel Converter Model Implemented in FPGA for HIL Test of Industrial Controllers.pdf



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Wei Li, Sisounthone Souvanlasy, Pierre-Yves Robert, Luc-André Gregoire, Jean Bélanger,

Abstract

Since Modular Multilevel Converters (MMC) have a sophisticated control, the real time simulation platform becomes critical for hardware-in-the-loop (HIL) test of the actual controllers in various scenarios before commissioning. This paper presents a multi-rate real time simulator that is able to simulate electromagnetic transients of MMC systems and connect to industrial controllers through fiber optics and copper wires for HIL tests. The MMC is implemented in field-programmable gate array (FPGA) with a sub-μs time step and the rest of the power system is simulated in the central processing unit (CPU) with a time step of 10~50 μs. Input and output (I/O) drivers are implemented in the same FPGA for a fast-rate and low-latency communication. Each FPGA accommodates up to 1530 sub-modules (SM), and multiple FPGA connected to one simulator can simulate MMC with more SM and multi-MMC systems. The performance is demonstrated in a 1500-SM MMC study case.

Modular-Multilevel-Converter Dynamic Analysis and Remedial Strategy for Voltage Transients During Blocking

Publication date : Sep 2013
Paper File : Modular Multilevel Converters Dynamic Analysis 2colones.pdf



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Author(s)

Luc-André Gregoire, Handy Fortin Blanchette, Wei Li, Antonios Antonopoulos, Lennart Ängquist, Kamal Al-Haddad,

Abstract

This paper proposes a thorough analysis of the blocking sequence for modular multilevel converters in order to avoid fast voltage transients; such transients increase the stress on the different components of the converter. An issue was identified for this topology when blocking all the semiconductor devices. Under certain circumstances, unconditional blocking can result in an over-voltage on the dc bus, or across the inductors. The issue is studied using analytical equations and experimental results. A new controlled-blocking scheme is suggested in order to avoid this problem, and supporting real-time simulation results are provided.

Modeling and Control of a Full-Bridge Modular Multilevel STATCOM

Publication date : Feb 2012
Paper File : PES12_MMCSTATCOM.pdf



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Author(s)

Jean Bélanger, Wei Li, Luc-André Gregoire,

Abstract

Due to its unique topology, the Modular Multilevel STATCOM has many advantages but requires a sophisticated controller and puts higher requirements on simulation tools. To simulate the STATCOM in real-time is preferable because it enables hardware-in-the-loop test of the system in various scenarios including extreme fault conditions, which cannot be tested on a real STATCOM. This paper presents a model of full-bridge sub-module which enables fast offline and real-time simulation of the STATCOM. A control scheme with a new SM capacitor voltage balancing method is also proposed in this paper. The model and the controller are investigated for different operating conditions. Implemented in a real-time simulator, the model can be simulated in real time at a time step of 20 µs, 131 times faster than its reference model. As demonstrated by the results, the proposed control scheme is effective and robust.

A Smart Distribution Grid Laboratory

Publication date : Nov 2011
Paper File : IECON2011_Smart_Distribution_Grid_Laboratory.pdf



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Wei Li, Toshifumi Ise, Takeiki Aizono, Jean Bélanger, Isao Iyoda, Christian Dufour, Amine Yamane,

Abstract

This paper details a Smart Grid Laboratory for the study of modern house distribution systems with multiple energy sources and energy regeneration capability. The laboratory is designed to perform real-time simulation of a realistic distribution system connected to multiple houses. In addition, a real house with typical appliances and power sources is connected to the eMEGAsim real-time simulator with a Power- Hardware-In-the-Loop (PHIL) interface. Such PHIL interface enables the simulation of a simulated plant and real devices at a connection point where actual energy is exchanged between the two parts. Because of the coupling delays and the bandwidth of the plant and real devices, the stability of such a PHIL connection is not guaranteed. This paper will have a special emphasis on the stability of such power-HIL simulation.

Control and Performance of a Modular Multilevel Converter System

Publication date : Aug 2011
Paper File : Control and Performance of a modular multilevel converter system.pdf



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Author(s)

Jean Bélanger, Luc-André Gregoire, Wei Li,

Abstract

The Modular Multilevel Converter (MMC) system has many advantages over conventional voltage source converters and therefore can be used in dc power transmission, micro grid, or renewable energy applications. While MMC’s distinctive topology offers many new features, it also necessitates a sophisticated controller to deal with extra control requirements. This paper presents a control scheme with multiple control objectives required by MMC, i.e. active and reactive power control, dc voltage control, sub-module capacitor voltage control and balancing, circulating current eliminating, and zero-sequence current eliminating. The system is modeled in an electromagnetic transients program, RT-LAB, and its dynamic performance is evaluated by time-domain studies using a real-time simulator, eMEGAsim. The results show the multiple control objectives are fulfilled and the system has fast response to control command and system dynamics

Validation of a 60-Level Modular Multilevel Converter Model - Overview of Offline and Real- Time HIL Testing and Results

Publication date : Apr 2011
Paper File : Validation of a 60-Level Modular Multilevel.pdf



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Author(s)

Wei Li, Luc-André Gregoire, Laurence Snider, Jean Bélanger,

Abstract

In this paper, full real-time digital simulation of a static modular multilevel converter (MMC) HVDC link interconnecting two AC networks is discussed. The converter has 60 cells per arm; each cell has two power switches with antiparallel diodes and one capacitor. The simulated model can be used to study the natural rectifying mode, which is very important in the energizing process of the converter, whether a ramping voltage or a charging resistance is used. The model also incorporates a simple controller to show the system behavior in different operating conditions. The converter model and the controller are simulated on two independent real-time simulators and connected though their respective IO and physical signal cables to perform Hardware-in-the-Loop testing. All capacitor voltages are supplied to the controller using digital to analog converters. Firing signals from the controller are sent using digital signals with opto-couplers, as would be the case with a real setup. By doing so, a Hardware-in-the-Loop (HIL) simulation is obtained. The main challenges of this setup are the very high number of IOs, which reaches over 730, considering both controller and converter, and the processing power required to simulate the 360 cells within a small time-step of 50 μs or less, as required for electromagnetic transient analysis. The simulation is achieved with a time-step of 20 μs using 10 INTEL 3.2-Ghz processor cores. Different faults are applied to determine their effects on the controller and the converter. In order to produce results that are as realistic as possible, a saturable transformer is used; the impact is particularly noticeable during faults and unbalanced load. The real-time digital simulator used is based on MATLAB, SIMULINK, SimPowerSystems and eMEGAsim.

Booklet of electric applications and simulation examples

Publication date : Jul 2011
Paper File : Sim_Apps_Booklet.pdf



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Author(s)

Wei Li, Jean-Nicolas Paquin, Jean Bélanger,

Abstract

eMEGAsim and eDRIVEsim product information & simulation application examples

Monte-Carlo Study on a Large-Scale Power System Model in Real-Time using eMEGAsim

Publication date : Oct 2009
Paper File : ECCE2009_Opal-RT_paperID1802_Final.pdf



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Author(s)

Wei Li, Laurence A. Snider, Jean-Nicolas Paquin, Jean Bélanger, Claudio Pirolli,

Abstract

This paper describes a versatile, multi-domain, large power grid real-time digital simulator. Its ability to conduct multiple tests for protection coordination studies is described. A large grid model built using the EMTP-RV software and simulated in real-time using the eMEGAsim platform’s EMTP-RT software tool is described. A discussion and comparisons on the different solvers offered with both simulation environments are made. Comparisons between offline and Real-Time simulations are made using superimposed fault condition waveforms. Finally, multiple random tests are performed on the featured power system model and analyzed using the eMEGAsim simulator’s software package.

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