Modular Multilevel Converters: Control and Applications

This paper presents an overview of the DC link development and evolution dedicated to HVDC structure for connecting offshore wind power plants to onshore power systems. The growing demand for the green energy has forced investors in power industry to look for resources further out at sea. Hence, the development of power electronics and industrial engineering has enabled offshore wind farms to be situated further from the shore and in deeper waters. However, their development will require, among other technologies, DC-DC conversion systems. The advantages of HVDC over HVAC technology in relation to transmission distance are given. The different HVDC configurations and topologies of HVDC converters are elucidated. In this context, the HVDC grids are a promising alternative for the expansion of the existing AC grid.

Section: Hvdc Offshore Technologies Comparisonmentioning

confidence: 99%

“…An example of a modern multilevel structure is a Modular Multilevel Converter (MMC) (Figure 6b). This topology was developed in the early 2000s and received increased attention since then [32,41]. MMC converters are the preferred technology in today's VSC-HVDC.…”

Section: Voltage Source Convertersmentioning

confidence: 99%

Evolution of the HVDC Link Connecting Offshore Wind Farms to Onshore Power Systems

Ryndzionek

Sienkiewicz

2020

“…Their multilevel output waveform reduces the total harmonic content of the generated ac voltage and, thus, the harmonics the of ac currents are quite limited also using a very small filter. Depending on the number of levels and the grid impedance, a filter-less solution can be acceptable [7][8][9][10].…”

Section: Introductionmentioning

confidence: 99%

Integration of Stationary Batteries for Fast Charge EV Charging Stations

Simone

Piegari

2019

One of the biggest issues preventing the spread of electric vehicles is the difficulty in supporting distributed fast charging stations by actual distribution grids. Indeed, a significant amount of power is required for fast charging, especially if multiple vehicles must be supplied simultaneously. A possible solution to mitigate this problem is the installation of auxiliary batteries in the charging station to support the grid during high peak power demands. Nevertheless, the integration of high-voltage batteries with significant power is not a trivial task. This paper proposes the configuration and control of a converter to integrate batteries in a fast charging station. The proposed configuration makes it possible to decouple the grid power from the vehicle power using several auxiliary battery modules. At the same time, the converter makes it possible to draw different amounts of power from the battery modules, allowing the use of second life batteries performing in different ways. This paper discusses the design, control, and operation of the converter. Moreover, the effectiveness of the proposed control is shown by means of numerical results.

“…The use of the stationary reference frame is possible with the proposed algorithm, in order to decrease the computational difficulty and avoid the application of the synchronous reference frame. Thus, the non-linear transformation (abc → dq) used with PI-R regulators is changed by the linear abc → αβ transformation using the PR controllers [39,40]. Moreover, as explained in Section 3, PR regulators can control the two sequences generated during grid voltage faults.…”

Section: Introductionmentioning

confidence: 99%

Improved Control of Grid-connected DFIG-based Wind Turbine using Proportional-Resonant Regulators during Unbalanced Grid

Karkri

Rey-Boué

Moussaoui³

et al. 2019

The quality of power and current control are the greatest challenges of grid-connected wind farms during abnormal conditions. The negative-and positive-sequence components of the grid currents may be injected into a wind generation system during grid faults, which can affect the power stability and damage the wind system. The proposed work assures a low-voltage ride through capability of doubly-fed induction generator-based wind turbines under the grid voltage sag. A new technique to protect the wind system and to recompense the reactive power during failures of the utility grid according to the Spanish grid code is proposed. The control design is implemented to the power converters, and the grid current regulation is developed by using proportional-resonant regulators in a stationary two-phase (αβ) reference frame. The control performance is significantly validated by applying the real-time simulation for the rotor-side converter and the hardware in the loop simulation technique for the experiment of the generator's grid-side converter control.