Modeling of Modular Multilevel Converters for the France-Spain link (original) (raw)
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Modular Multilevel Converter Models for Electromagnetic Transients
IEEE Transactions on Power Delivery, 2014
Modular multilevel converters (MMCs) may contain numerous insulated-gate bipolar transistors. The modeling of such converters for electromagnetic transient-type (EMT-type) simulations is complex. Detailed models used in MMC-HVDC simulations may require very large computing times. Simplified and averaged models have been proposed in the past to overcome this problem. In this paper, existing averaged and simplified models are improved in order to increase their range of applications. The models are compared and analyzed for different transient events on an MMC-HVDC system.
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This paper deals with the conception and the development of a detailed EMT Model for MMC based on experimental results obtained from a mock-up. The main purpose is to illustrate how to exploit the performances of EMT simulation tools to develop a detailed model that represents accurately the behaviour of a physical MMC. According to step-by-step identification of the MMC element parameters, the idea is to perform a systematic method, which allows expanding an accurate EMT model considering the behaviour of the prototype and its environment. The first part depicts the MMC topology and the modelling approach of the Half-bridge Sub-Module (SM) using a detailed IGBT-based model. The second part of the simulation model conception concerns both control levels such as high-level and low-level controllers. The last part of the EMT model conception involves the modelling of measurement process, ADC (Analogue Digital Converter), sensors dynamics, the communication delays and especially the qu...
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Modular multilevel converters (MMCs) are widely used in the design of modern high-voltage direct current (HVdc) transmission system. High-fidelity dynamic models of MMCsbased HVdc system require small simulation time step and can be accurately modeled in electromagnetic transient (EMT) simulation programs. The EMT program exhibits slow simulation speed and limitation on the size of the model and brings certain challenges to test the high-fidelity HVdc model in system-level simulations. This paper presents the design and implementation of a hybrid simulation framework, which enables the co-simulation of the EMT model of Atlanta-Orlando HVdc line and the transient stability (TS) model of the entire Eastern Interconnection system. This paper also introduces the implementation of two high-fidelity HVdc line models simulated at different time steps and discusses a dedicated method for sizing the buffer areas on both sides of the HVdc line. The simulation results of the two HVdc models with different sizes of buffer areas are presented and compared.
Thanks to scalability, performance and efficiency, the Modular Multilevel Converter (MMC), since its invention, becomes an attractive topology in industrial applications such as high voltage direct current (HVDC) transmission system. However, modelling challenges related to the high number of switching elements in the MMC are highlighted when such systems are integrated into large simulated networks for stability or protection algorithms testing. In this work, a novel dynamic models for MMC is proposed. The proposed models are intended to simplify modeling challenges related to the high number of switching elements in the MMC. The models can be easily used to simulate the converter for stability analysis or protection algorithms for HVDC grids.
2011
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.
Detailed and Averaged Models for a 401-Level MMC–HVDC System
IEEE Transactions on Power Delivery, 2012
Voltage-source-converter (VSC) technologies present a bright opportunity in a variety of fields within the power system industry. New modular multilevel converters (MMCs) are expected to supersede two-and three-level VSC-based technologies for HVDC applications due to their recognized advantages in terms of scalability, performance, and efficiency. The computational burden introduced by detailed modeling of MMC-HVDC systems in electromagnetic-transients (EMT)-type programs complicates the study of transients especially when these systems are integrated into a large network. This paper presents a novel average-value model (AVM) for efficient and accurate representation of a detailed MMC-HVDC system. It also develops a detailed 401-level MMC-HVDC model for validating the AVM and studies the performance of both models when integrated into a large 400-kV transmission system in Europe. The results show that the AVM is significantly more efficient while maintaining its accuracy for the dynamic response of the overall system.
A Novel Modular Multilevel Converter Modelling Technique Based on Semi-Analytical Models
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Thanks to scalability, performance and efficiency, the Modular Multilevel Converter (MMC), since its invention, becomes an attractive topology in industrial applications such as high voltage direct current (HVDC) transmission system. However, modelling challenges related to the high number of switching elements in the MMC are highlighted when such systems are integrated into large simulated networks for stability or protection algorithms testing. In this work, a novel dynamic models for MMC is proposed. The proposed models are intended to simplify modeling challenges related to the high number of switching elements in the MMC. The models can be easily used to simulate the converter for stability analysis or protection algorithms for HVDC grids.
Unified Modeling and Simulation Approach for Modular Multilevel Voltage Source Converters
This paper presents a unified approach for efficient modeling and simulation in a multi-tool environment. The motivations are clearly defined and the approach is explained. While this method is applicable to a wide range of tools and applications, it is illustrated with Matlab/Simulink, for control system development, and two EMT simulation tools, EMTP-RV and Hypersim. The sample application is a point-to-point HVDC link based on modular multilevel voltage source converters: the EMT modeling of this technology is briefly presented as well as a complete control and protection system. The unifying agent in this example is the Simulink controller but the unified approach could be applied with other parts of the system and/or developed in other software. Results comparison is shown to be excellent and fully coherent, enabling this software to be used with full confidence in its respective niche applications.
Generalized switching function model of modular multilevel converter
2015 IEEE International Conference on Industrial Technology (ICIT), 2015
this paper presents a generalized switching function model of the modular multilevel converter (MMC) that can be used instead of MMC electromagnetic transient simulation model for full-scale simulations of high-voltage dc (HVDC) and flexible ac transmission systems (FACTS). The proposed method is computationally more efficient and numerically stable than its electromagnetic transient simulation counterpart, and it is applicable for wide range of studies, including ac and dc network faults. The proposed switching function model is packaged in a graphical form to suit various simulation platforms such as Simulink and PSCAD. The validity of the presented model is confirmed using simulation and its scalability has been demonstrated on MMC with 301 cells per arm, considering power reversal during normal operation and dc short circuit fault.