Compensation of voltage sag and flicker during thermal power plant turbo-expander operation by dynamic voltage restorer

The application of the turbo-expander in the auxiliary service system of Neka power plant in Iran causes considerable voltage sag, which is very dangerous to the auxiliary service system. To reduce the voltage sag, the dynamic voltage restorer (DVR) is proposed. The auxiliary service system and main substation of the power plant with compensators are simulated by Power System Computer Aided Design (PSCAD/EMTDC) software. The application of the static synchronous compensator in different scenarios is discussed, and the results are compared with the results of the application of the DVR, which has a new topology and minimum injection power control strategy. It is shown that the results of the DVR application are better in all tested scenarios. Also, the economic assessment shows that the payback period is reduced to half in case of using DVR instead of static synchronous compensator. Copyright (c) 2015 John Wiley & Sons, Ltd.