Author(s)

E. K. Arakelyan, A. V. Andryushin, K. A. Andryushin

Abstract

The problem of power backup for steam turbines when passing through the long load failures, is particularly relevant at present. It is caused by stricter requirements of dispatching services of power supply systems to reliability, manoeuvrability and cost-effectiveness. Alternative ways of the units transition to night time backup with the complete removal of the active load are the stop-start mode and generator driving mode (SSM and GDM). The generator driving mode is understood as its work without supply of operational steam to the head part of the turbine without disconnection of the generator from the network. Generator works as the engine, consuming from a network the active power required to cover mechanical and ventilation power losses in the turbine and electric and ventilation losses in the generator. The purpose of the present article is to summarize the results of these studies so as to identify the optimum schemes of GDM implementation process in terms of manoeuvrability, reliability and cost-efficiency. The technique of GDM application will be analyzed for the first time for steam turbines of combined cycle gas turbine units. As a result, it has been shown that GDM application for steam turbines has a number of operational advantages in comparison with SSM: significant increase of manoeuvrability and reliability of the equipment during operation in the semi-peak mode; durability of turbine elements increases thanks to the minimum amplitude of thermal tension; cyclic temperature tensions decrease, which removes the limits of numbers of transition into backup mode for turbine unit.

Keywords

generator driving mode, reliability, maneuverability, cost-effectiveness, combined cycle, gas turbine units