Improving short-term voltage stability problems by variable-speed air-conditioners

In recent years, air-conditioners have been increasing greatly and consuming larger portion of energy. At the same time, with the development of frequency converter technique, variable-speed air-conditioners have occupied more and more market share, not only because of the better energy efficiency, but also the improved comforts. Meanwhile, frequency converters can alleviate negative influences of induction motors on power system during voltage disturbance, which will do much help to the grid. Therefore, with logical control on frequency converters, performance will be better encountered in grid failure. The purpose of this article is to evaluate the above-mentioned effects of frequency converter by simulation, and to postpone the stalling of induction motor by resorting to logical control on converters.