Control design for grid and energy/balancing controllers of modular multilevel converter based VSC HVDC systems

Hahn, Christoph; Burkhardt, Matthias; Luther, Matthias

doi:10.1109/compel.2016.7556679

Cited by 12 publications

(3 citation statements)

References 15 publications

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“…The adaptive carrier PDPWM is able to continue the operation of MMCs and react fastly when certain SM failure. The general energy-based control of MMC system is used in this work due to its excellent expandability [26], [27]. A prototype of MMC has been built to effectively investigate the proposed method and performance of energy-based control during the fault.…”

Section: P C_umentioning

confidence: 99%

Adaptive Carrier-Based PDPWM Control for Modular Multilevel Converter With Fault-Tolerant Capability

et al. 2020

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Modular multilevel converters (MMCs) are considered very promising converters due to their modularity structure and high reliability from fault-tolerant. A fault within a submodule (SM) is one of the main issues in half-bridge MMCs with substantial switching devices. In this paper, an adaptive carrier based phase disposition pulse width modulation (PDPWM) technique for MMCs, which uses only one carrier having flexibility with fault-tolerant capability, is presented. The energy-based control is also used in this study to regulate the balancing of SMs during and after a fault. In order to investigate the performance of the proposed method, a laboratory single-phase MMC prototype has been built by using four SMs to generate nine-level. The single-phase MMC prototype is tested by assuming one of the SMs in the failure condition. The result revealed that the proposed method had been successfully applied to the MMC prototype to control the upper and lower arm during the failure. In addition, the reference command will correct the fault according to the adaptive carrier and the computational burden is lesser since it only uses one single carrier.

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Section: P C_umentioning

confidence: 99%

Adaptive Carrier-Based PDPWM Control for Modular Multilevel Converter With Fault-Tolerant Capability

et al. 2020

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“…This mode is called islanded mode, as it serves to connect weak or islanded AC grids such as OWF. At the lower level-control, the converter controls, such as the circulating current control and the energy balancing control as well as the valve control, such as the capacitor balancing and the modulation take place (Hahn et al, 2016).…”

Section: Control Of the Mmcsmentioning

confidence: 99%

Demonstration of Offshore Wind Integration with an MMC Test Bench featuring Power-Hardware-in-the-Loop Simulation

Loku

Ruffing

Brantl

et al. 2020

Preprint

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Abstract. The integration of offshore wind energy into the existing power system is continuously growing. With the increasing distance of the offshore wind farms (OWF) to the onshore AC transmission systems, HVDC systems are emerging as a preferable solution for the connection of OWF due to their techno-economic advantages in comparison to AC subsea connections. Integrating HVDC systems into the existing AC systems poses various planning and technological challenges. To be able to overcome these challenges a variety of studies has to be conducted, e.g. the HVDC system behaviour under faults. Simulations using electromagnetic transient (EMT) tools represent a generally accepted method to conduct the relevant studies. To increase the trust in the developed concepts subsequent hardware demonstrations would be preferable. However, performing these investigations with full-scale components is often not an option due to unavailability and high costs. As an alternative way, Power-Hardware-in-the-Loop (PHiL) approaches are considered. In this context, a new and worldwide unique laboratory demonstrator - the MMC Test Bench - is set up at RWTH Aachen University as part of the Horizon2020 project PROMOTioN. Here, laboratory-scaled Modular Multilevel Converters (MMCs) are used, which are connected on the DC side by cascaded Pi-line segments. The adjacent AC grids (i.e. offshore wind farms, AC transmission networks) are represented by real-time simulators (RTS) and connected to the MMCs via high bandwidth linear power amplifiers (PA). In this work, the MMC Test Bench is initially described. Afterwards, the PHiL set-up to demonstrate the implemented controls for an OWF connected to shore via an HVDC link is explained. To allow the joint operation of the hardware set-up and the RTS in a stable manner, adequate PHIL interfaces algorithms have to be designed and the scaling between the RTS, the power amplifiers and the hardware is explained. The connection of the OWF represents a special challenge for PHiL demonstrations as the OWF represents a weak AC system with the MMC in grid forming mode. In a next step, the results of the successful demonstration of the interconnection of the OWF via an HVDC link with the MMC Test Bench are presented. The system behaviour in stationary and transient operation is analysed based on the wind farm start-up sequence as well as different cases of wind infeed fluctuations. The results are compared to a simulated full-scale model and deviations are discussed.

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“…For a stable operation, the average AC and DC power have to be equal and voltages of the SM capacitors have to be constant over a period of the fundamental frequency f AC . Therefore, the energy differences between the phases and between the upper and lower arms are minimised using an energy balancing control [8]. The energy balancing output is used as input of the circulating current suppression control (CCSC) [7].…”

Section: Technical Considerationsmentioning

confidence: 99%

Fault current control methods for multi‐terminal DC systems based on fault blocking converters

Ruffing

Brantl

Petino

et al. 2018

J. eng.

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Control design for grid and energy/balancing controllers of modular multilevel converter based VSC HVDC systems

Cited by 12 publications

References 15 publications

Adaptive Carrier-Based PDPWM Control for Modular Multilevel Converter With Fault-Tolerant Capability

Adaptive Carrier-Based PDPWM Control for Modular Multilevel Converter With Fault-Tolerant Capability

Demonstration of Offshore Wind Integration with an MMC Test Bench featuring Power-Hardware-in-the-Loop Simulation

Fault current control methods for multi‐terminal DC systems based on fault blocking converters

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