A DFT-based phasor estimation method robust to primary and secondary decaying DC components

Afrandideh, Saeed; Haghjoo, Farhad

doi:10.1016/j.epsr.2022.107907

Cited by 10 publications

(9 citation statements)

References 27 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…However, it is observed that the proposed algorithms are quite error-free. This verifies that the proposed FIGURE 16 The estimated fundamental phasors for signal S1 in noisy condition algorithms are more robust than other methods to estimate the fundamental phasor of fault current signals containing DDC components.…”

Section: Evaluation With Simulated Signalssupporting

confidence: 73%

See 1 more Smart Citation

Two modified DFT‐based algorithms for fundamental phasor estimation

Afrandideh

Arabshahi

Fazeli

2022

IET Generation Trans & Dist

Self Cite

View full text Add to dashboard Cite

The discrete Fourier transform (DFT) is a powerful phasor estimation algorithm conventionally used in digital relaying applications. The DFT-based phasor estimation is usually accompanied by oscillatory error due to the presence of the decaying DC (DDC) components in fault current signals. Accordingly, two modified DFT-based phasor estimation algorithms are proposed in this paper. The proposed algorithms accurately estimate the exact fundamental phasor by extracting the DDC components using successive outputs of the conventional DFT algorithm. The performance of the proposed algorithms is validated by the mathematically generated and PSCAD-simulated signals and is compared with previous algorithms. The results demonstrate that the proposed algorithms in this paper are more robust than other ones. Moreover, they are applicable in the DFT algorithm with different data windows. INTRODUCTIONThe fundamental phasor estimation plays an important role in detecting, locating, and discriminating faults in power systems. There are a number of conventional phasor estimation algorithms, that include: discrete Fourier transform (DFT), least-square error (LSE), discrete wavelet transform (DWT), Kalman filters, discrete Hartley transform (DHT), and artificial neural networks (ANNs) [1][2][3][4]. The discrete Fourier transform (DFT) is a powerful phasor estimation algorithm, widely used in digital relaying applications due to its simplicity, accuracy, and speed. The DFT algorithm has a high capability to estimate the fundamental phasor of periodic sinusoidal signals. However, its performance is extremely influenced by non-periodic signals such as decaying DC components (DDCs), which are created in the current and voltage signals during fault conditions. This issue causes an undesired oscillating error in the estimated phasor, especially phase angle. Although this error decays after a certain period of time (depending on the time constant of the DDC component), it extremely reduces the speed and accuracy of decision-making in relays. The DDC component has two parameters, the initial value and time constant, which depend on fault inception angle and the value of pathway X ∕R ratio, respectively. Because the source impedance and line X ∕R ratio are so close to each other, the initial value ofThis is an open access article under the terms of the Creative Commons Attribution License, which permits use, distribution and reproduction in any medium, provided the original work is properly cited.

show abstract

Section: Evaluation With Simulated Signalssupporting

confidence: 73%

“…Combining (15) in (3), y 1,[n] is obtained as shown by (19). Similarly, by combining ( 16) in ( 15), ( 17) in (16), and then (18) in (17), y 2,[n] to y 4,[n] are obtained as shown by (20) to (22).…”

Section: Multiple Ddc Components Estimationmentioning

confidence: 99%

Two modified DFT‐based algorithms for fundamental phasor estimation

Afrandideh

Arabshahi

Fazeli

2022

IET Generation Trans & Dist

Self Cite

View full text Add to dashboard Cite

show abstract

“…An updated version of [1] is presented in [20], where three consecutive samples of an average filter were used to compute DDC parameters. Then, by solving two quadratic equations, DDC parameters were obtained.…”

Section: A Brief Survey On the Ddc Mitigation In Pre-dft Methodsmentioning

confidence: 99%

“…In this section, a critical review of the different pre-DFT methods and some of the main drawbacks are presented. x x x NA [11] x x x 1 cycle [12] x x 1 cycle +1 sample [14] x x 1 cycle [13] x x 1 cycle [15] x x 1 cycle [16] x 1 cycle +2 samples [1] 1 cycle [17] x 1 cycle +3 samples [6] x 1 cycle [18] x x 4 samples [3] 1/2 cycle +3 samples [19] half cycle + 2 samples [20] 1 cycle [21] half cycle + 1 sample…”

Section: Critical Review Of Pre-dft Methodsmentioning

confidence: 99%

See 1 more Smart Citation

Decaying DC Offset Current Mitigation in Phasor Estimation Applications: A Review

et al. 2022

View full text Add to dashboard Cite

Decaying DC (DDC) offset current mitigation is a vital challenge in phasor current estimation since it causes malfunctioning/maloperation of measurements and protection systems. Due to the inductive nature of electric power systems, the current during fault inception cannot change immediately and it contains a transient oscillation. The oscillatory component acts similar to an exponential DC signal and its characteristics depend on the X/R ratio of the system, fault location, and fault impedance. DDC attenuates accurate phasor estimation, which is pivotal in protection systems. Therefore, the DDC must be eliminated from the fault current (FC) signal. This paper presents an overview of DDC mitigation methods by considering different groups—before the discrete Fourier transform (pre-DFT), after the discrete Fourier transform (post-DFT), the least square-based (LS-based), and other methods. Through a comprehensive review of the existing schemes, the effects of noise, harmonics, multiple DDCs (MDDCs), and off-nominal frequency (ONF) on the accuracy of DDC estimation, were recognized. A detailed discussion (along with some simulation results) are presented to address the main advantages/disadvantages of the past studies. Finally, this paper presents a few suggestions for future researchers, for researchers to investigate more implementable solutions in this field.

show abstract