A New Energy Management Control of Modular Multilevel Converters for Coping with Voltage Stress on Sub-Modules

2019-07-26T09:40:20+02:00April 24th, 2019|Publications, Supergrid Architecture & Systems|

This paper investigates the impact of the operating condition on the SM voltage ripples. In particular, it is revealed that under the classical control scheme where the Modular Multilevel Converter internal energy varies naturally with the DC grid voltage, the traditional sizing approach based on the analytical expression of instantaneous SM voltage may fail to respect the SM voltage constraint. To tackle this problem, this paper presents a solution by incorporating the advantages of the explicit energy management and the developed analytical expressions of the SM voltage ripple, which achieves a better utilization of the converter asset.

Overview of DC–DC Converters Dedicated to HVdc Grids

2019-07-26T09:40:23+02:00February 19th, 2019|Power Electronics & Converters, Publications, Supergrid Architecture & Systems|

This paper presents an overview of the dc–dc power converters dedicated to HVdc proposing a classification based on their structure. Two large families are established: those which provide galvanic isolation, and those which do not. Several subfamilies are also proposed. An overview of the main HVdc applications that can be targeted with each family is also presented, highlighting the main converter requirements for each application case.

FMEA of a non-selective fault-clearing strategy for HVDC grids

2019-07-26T09:40:29+02:00February 7th, 2019|Publications, Supergrid Architecture & Systems|

The Failure Mode Effect Analysis (FMEA) is a technique used to investigate failures in a process or component and to identify the resultant effects of these failures on system operations. In this paper it is explained how the FMEA can be used to define and assess the impact of the failure modes (FM) of a protection strategy for High Voltage Direct Current (HVDC) grids.

Virtual Capacitor Control for Stability Improvement of HVDC System Comprising DC Reactors

2019-07-26T09:40:29+02:00February 7th, 2019|Publications, Supergrid Architecture & Systems|

This paper first analyzes the underlying instability issue attributed to the DC reactor by using a simplified converter station model, which reveals that the DC-link capacitor can compensate for the detrimental effect of the DC reactor and increase the stability margin. This capacitor, however, is usually avoided and distributed over the capacitors in sub-modules in the state-of-the-art Modular Multilevel Converters (MMCs).

An Implementation Method for the Supervisory Control of High-Voltage Direct Current Transmission Systems

2019-07-26T09:40:30+02:00January 16th, 2019|Publications, Supergrid Architecture & Systems|

This paper presents an application of the SCT to HVDC grids and proposes an implementation method for the resulting supervisors. The proposed method is capable of integrating decentralized and discrete-event controllers that interact with the continuous-time physical system. The language chosen for the implementation is C code, as it can be easily incorporated in power system simulation software, such as EMTP-RV. The method is validated by the simulation of the start-up of a point-to-point link in the EMTP-RV software.

25 kV-50 Hz railway power supply system emulation for Power-Hardware-in-the-Loop testings

2019-07-26T09:40:30+02:00January 8th, 2019|Power Electronics & Converters, Publications|

This paper presents a methodology to consider the impedance of a grid in power hardware in the loop (PHIL) experiments to validate power converter control in presence of harmonics or resonances in the network impedance. As the phenomena to emulate are in a large frequency range, the skin effect in conductors has to be taken into account. A procedure is developed to model the network.

Modelling of a 25 kV-50 Hz railway infrastructure for harmonic analysis

2019-07-26T09:40:30+02:00December 20th, 2018|Power Electronics & Converters, Publications|

This paper presents a methodology for the modelling of a 25 kV-50 Hz railway infrastructure, for frequencies from 0 to 5 kHz. It aims to quantify the amplifications of current and voltage harmonics generated by on-board converters into the infrastructure. A circuit is developed to model the skin effect in the overhead line for time-domain simulations. A new approach, based on state space representation and transfer functions, is also proposed to analyse the interactions between trains.

Study of Turn-to-Turn Electrical Breakdown for Superconducting Fault Current Limiter Applications

2019-07-26T09:40:42+02:00November 2nd, 2018|High Voltage Substation Equipment, Publications|

The rational insulation design of a resistive superconducting fault current limiter (r-SCFCL) requires data gathered from experimental setups representative of the final apparatus. Therefore, an experimental study was performed to characterize the electrical breakdown (BD) of liquid nitrogen (LN2) in the peculiar conditions of a quenching superconducting device.