A new method for measuring power system frequency

Author

Sezi, Tevfik

Author_Institution

Distribution Autom. Div., Siemens Power Transmission & Distribution, Raleigh, NC, USA

Volume

1

fYear

1999

fDate

11-16 Apr 1999

Firstpage

400

Abstract

The algorithms of numerical protective relays are very sensitive to variations in the power system frequency during operation. Even slight changes of the power frequency can lead to large calculation errors in the values for impedances, the power factor, etc. Implementing an adaptive sampling rate requires knowing the actual system frequency at all times with high accuracy. A new frequency measurement method has been successfully implemented. Since the method is not dependent upon zero-crossings of the measured current, it can calculate the frequency after every sample. In addition, the necessary signal-window is approximately 3 cycles, which means that the calculation is faster than all classical methods. The new method has made possible the development of a full-featured generator protection relay that can operate over a frequency range of 15 Hz-70 Hz. The accuracy of the frequency calculation is better then 10 mHz for a nominal frequency of 60 Hz

Keywords

frequency measurement; machine protection; power system measurement; power system protection; relay protection; 15 to 70 Hz; adaptive sampling rate; generator protection relay; impedance; numerical protective relay algorithms; power factor; power system frequency measurement; power system frequency variations; Current measurement; Frequency measurement; Impedance; Power measurement; Power system measurements; Power system protection; Power system relaying; Protective relaying; Reactive power; Sampling methods;

fLanguage

English

Publisher

ieee

Conference_Titel

Transmission and Distribution Conference, 1999 IEEE

Conference_Location

New Orleans, LA

Print_ISBN

0-7803-5515-6

Type

conf

DOI

10.1109/TDC.1999.755385

Filename

755385