Integrating Offshore Wind Power Via Fractional Frequency Transmission System

Abstract

A novel solution to integrating offshore wind power via the Fractional Frequency Transmission System (FFTS) is introduced in this paper. The basic idea of FFTS is to improve the technical and economic performance of AC transmission systems by lowering the grid frequency. FFTS is especially suitable for transmitting offshore wind power because the low frequency dramatically reduces the charging current in the cable. In addition, as a novel AC transmission system, FFTS performs much better than HVDC in constructing a multi-terminal (MT) grid. The basic structures and characteristics of a typical PMSG-based FFTS offshore wind power system and a MT-FFTS offshore grid are described first. Then two offshore wind power cases are used to compare the technical and economical pros and cons of the FFTS solution with the conventional solutions: HVAC and HVDC. The feasibility studies show that the performance of FFTS offshore wind power system is superior to that of HVAC and HVDC in both point-to-point (PP) and multi-terminal cases. The uniform annual value of PP-FFTS and MT-FFTS are 5.01% and 5.07% cheaper than PP-HVDC and MT-HVDC. Therefore, FFTS is a promising solution to offshore wind power integration and building offshore grids.Index Terms-Feasibility study; fractional frequency transmission system; offshore grid; offshore wind power integration

A global asymptotical stable control scheme for a Hexverter in fractional frequency transmission systems

“…At present, the widely-used wind power integration strategy is the flexible HVDC system, of which the two terminals are connected by the high-voltage high-power converter such as the modular multilevel converter (MMC) through a DC transmission line [3][4][5]. However, the HVDC system needs an offshore converter station which will lead to high costs for construction and CrossCheck date: 26 March 2019 maintenance, and it is difficult to deal with the fault cases [6]. In order to overcome the shortcomings of the HVDC system, the FFTS is proposed, in which the offshore wind farm and offshore transmission system works at a relatively low frequency [7][8][9].…”

Penetrating power characteristics of half-wavelength AC transmission in point-to-grid system

“…This can largely reduce the electrical distance between both ends of the line [2,3]. Because of this, HWACT is suitable for long-distance and high-capacity transmission [4][5][6][7][8]. For the traditional line, the resistance is far less than the reactance.…”

A novel SoC feedback control of ESS for frequency regulation of fractional frequency transmission system with offshore wind power

“…It is a very promising transmission method for wind power generation. By using low transmission frequency(50/3Hz), this novel method is able to increase the transmission capacity and reduce the fluctuation at the connection point of wind farm [4]. Relevant experiments have been published in [5] as the system is called Fractional Frequency Wind Power System (FFWPS).…”