A New Measurement Technique for Tracking Voltage Phasors, Local System Frequency, and Rate of Change of Frequency

TLDR

Substation computer systems provide on‑site processing power that enables new applications, such as the microcomputer‑based Symmetrical Component Distance Relay, which facilitates real‑time monitoring of positive‑sequence voltage phasors at the local bus. The paper presents the theoretical basis for computing frequency and rate‑of‑change of frequency from voltage phase angles and outlines future field tests on the AEP system. The method uses regression analysis of the positive‑sequence voltage phase angle to determine bus frequency and its rate of change. Experimental results in the AEP power‑system simulation laboratory confirm the validity of the theoretical computations.

Abstract

With the advent of Substation Computer Systems dedicated to protection, control and data logging functions in a Substation, it becomes possible to develop new applications which can utilize the processing power available within the substation. The microcomputer based Symmetrical Component Distance Relay (SCDR) described in the references cited at the end of this paper possesses certain characteristics which facilitate real-time monitoring of positive sequence voltage phasor at the local power system bus. With a regression analysis the frequency and rate-of-change of frequency at the bus can also be determined from the positive sequence voltage phase angle. This paper describes the theoretical basis of these computations and describes results of experiments performed in the AEP power system simulation laboratory. Plans for future field tests on the AEP system are also outlined.