Investigation of Power Flows in Wound-Rotor Induction Generators at Wind Power Plants under Various Operating Modes

Abstract

Relevance: worldwide, considerable attention is being paid to the rational use of existing natural energy resources, improving the energy efficiency of power plant generators through the use of renewable energy sources, and developing energy-saving operating modes for electromechanical systems of hydroelectric power plants. Currently, in developed countries, extensive research is being conducted on the application of wound-rotor induction generators (WRIGs) in renewable energy systems, as well as on automatic control of electromechanical systems. According to global statistics, the installed capacity of wind power plants increases annually by 93.6 GW and has reached 950 GW. In this context, the improvement of wind power plant generators, enhancement of their energy performance, and increase in the energy efficiency of electromechanical systems remain pressing tasks.

Aim: conducting an analysis of methods for controlling the rotational speed of a wound-rotor induction generator (WRIG) in renewable energy systems over a wide speed range; developing a functional diagram of an automatic speed control system for the WRIG under varying wind speeds; and, taking into account that the speed control range of a wind power plant based on a doubly-fed induction generator (DFIG) is ± 30 % relative to the synchronous speed, determining the possibilities for improving the energy efficiency of the DFIG at wind power plants as well as enhancing its reliability indicators.

Methods: in the course of the study, mathematical modeling and computational methods were employed to analyze the power characteristics of the rotor and stator. For the DFIG based on the WRIG, power flow directions were examined under two operating modes: sub-synchronous and super-synchronous rotor speeds..