An Examination of AC/HVDC Power Circuits for Interconnecting Bulk Wind Generation with the Electric Grid

Abstract

Abstract:The application of high voltage dc (HVDC) transmission for integrating large scale and/or off-shore wind generation systems with the electric grid is attractive in comparison to extra high voltage (EHV) ac transmission due to a variety of reasons. While the technology of classical current sourced converters (CSC) using thyristors is well established for realization of large HVDC systems, the technology of voltage sourced converters (VSC) is emerging to be an alternative approach, particularly suitable for multi-terminal interconnections. More recently, a more modular scheme that may be termed 'bridge of bridge' converters (BoBC) has been introduced to realize HVDC systems. While all these three approaches are functionally capable of realizing HVDC systems, the converter power circuit design trade-offs between these alternatives are not readily apparent. This paper presents an examination of these topologies from the point of view of power semiconductor requirements, reactive component requirements, operating losses, fault tolerance, multi-terminal operation, modularity, complexity, etc. Detailed analytical models will be used along with a benchmark application to develop a comparative evaluation of the alternatives that maybe used by wind energy/bulk transmission developers for performing engineering trade-off studies. Keywords

Modular multilevel converter as a low inductance machine drive

“…This paper will focus on the most common configuration, a three phase DC-AC BoBC whose simplified schematic and equivalent circuit are illustrated in Fig. 1, which can provide excellent waveform quality, modularity, scalability, and fault tolerance [5]. While these performance attributes have been discussed elsewhere, issues related to low inductance loads is the subject of this paper.…”

“…Of the converters poised for high-power-high-voltage power conversion endeavors, the modular multilevel converter (MMC) has been conjectured as the future of MVAC & HVDC technology [4][5][6]. The converter consists of multiple arms of series connected capacitive storage embedded bridges (CSEBs) to form a larger symmetric bridge thus leading to the more apt name "bridge of bridge" (BoBC) as there are many types of modular multilevel converters.…”

Operation and Power Flow Control of Multi-Terminal DC Networks for Grid Integration of Offshore Wind Farms Using Genetic Algorithms

“…The most important technical aspects are the choice of HVDC converter topology [11][12][13][14], the necessity of dc/dc converters [15,16], the need for protection schemes [17][18][19], dynamic stability issues [20][21][22], and power-flow control strategies [23][24][25][26].…”

Improved Adaptive Droop Control Design for Optimal Power Sharing in VSC-MTDC Integrating Wind Farms

“…Multi-terminal DC (MTDC) grids are foreseen as an alternative solution to point-to-point connections owing to their increased redundancy and higher flexibility [4]. Intensive researches have recently been conducted to resolve various technical issues in the VSC-MTDC system, such as locating and isolating of DC faults [5], operation and control of MTDC grid integrating wind farms and so on [6,7]. In order to improve the capacity and stable operation of MTDC, X. Chen et al [8] have studied the control methods of hybrid MTDC grid integrating wind farms, and proposed corresponding control strategies.…”