Frequency stability analysis in low frequency AC systems for renewables power transmission

Abstract

The foreseen high penetration levels of wind energy will have serious implications on frequency stability, hence developed control methods of wind turbine and alternative technologies including energy storage should enable the provision of frequency support by wind power. Active research is ongoing to investigate the possibility of collecting and transmitting offshore wind power through low frequency alternating current systems (LFAC). This paper develops a novel method to enhance frequency support capability of generators connected to a LFAC system. The leveraged frequency regulation ability of the generators at LFAC system is emphasized. The voltage is proportional to the frequency of the LFAC system, so that the transformers can be protected when frequency drops. Then the generators at LFAC system acquire sufficient time for frequency regulation. In this paper, a hydro generator at LFAC system is regarded as an energy storage plant, which is connected to the LFAC system rather than normal frequency grid.

A network control system for hydro plants to counteract the non-synchronous generation integration

“…It is focused on the pitch control and the frequency support from the turbine. A similar approach is given in [23], where a control method is developed to enhance the frequency capability including energy storage.…”