A Synchrophasor Estimator Characterized by Attenuated Self-Interference and Robustness Against DC Offsets: the DCSOGI Interpolated DFT

TL;DR

This paper introduces a robust synchrophasor estimation method combining an enhanced SOGI, IpDFT, and windowing techniques to effectively reject DC offsets and harmonic interferences, ensuring compliance with industry standards.

Contribution

It proposes a novel SE algorithm with an improved SOGI formulation and dual window approaches, enhancing robustness against DC offsets and harmonic disturbances in synchrophasor measurements.

Findings

Effective rejection of DC offsets demonstrated in simulations.

Compliance with IEC/IEEE standards achieved under various noise and interference conditions.

Enhanced detection and correction of harmonic tones ensure measurement accuracy.

Abstract

The second-order generalized integrator (SOGI), which can be used to attenuate the self-interference of the fundamental tone, is unable to reject DC offsets on the input signal. Consequently, the performance of any SOGI based synchrophasor estimation (SE) technique might be compromised in the presence of such DC components. The current work presents a SE algorithm which adopts and enhanced SOGI formulation, robust against DC, combined with a three-point IpDFT and a Hanning window. Two alternative formulations relying respectively on the use of two and three nominal fundamental period observation windows are proposed and assessed for simultaneous compliance with both phasor measurement unit (PMU) P and M performance classes. This is done by means of a simulated environment where all the operating conditions defined by the IEC/IEEE Std. 60255-118-1-2018 are evaluated simultaneously combined with a $10\%$ static DC and under two different noise levels. Furthermore, both formulations adopt a dedicated mechanism for the detection and correction of low amplitude $2^{nd}$ harmonic tones to ensure their compliance with the standard can be maintained in the presence of such disturbances even under off-nominal frequency conditions. Finally the resilience of both methods against multiple simultaneous harmonic interferences is also analyzed.