Histogram-Based Method to Avoid Maloperation of Transformer Differential Protection Due to Current-Transformer Saturation Under External Faults

Zheng, Tao; Huang, Ting; Ma, Yulong; Zhang, Zihang; Liu, Lianguang

doi:10.1109/tpwrd.2017.2712806

Cited by 31 publications

(11 citation statements)

References 33 publications

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“…External short circuit stresses the PAR and reduces the transformer life. A non-zero differential current flows due Total = 21×12×5×2 = 2520 to saturation of CTs during external faults and may lead to false trips [27]. Raising the bias threshold of differential relays may ensure stability, but then the sensitivity for inzone internal faults is reduced.…”

Section: External Fault With Ct Saturationmentioning

confidence: 99%

A Data Mining Based Protection and Classification of Transients for Two-Core Symmetric Phase Angle Regulators

Bera

Işık

2021

IEEE Access

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Several conventional and non-conventional transient conditions cause differential relays associated with Phase Angle Regulators to malfunction. For Two-core Symmetric Phase Angle Regulators, this article investigates the suitability of time and time-frequency feature-based estimators to differentiate internal faults from other transient conditions such as overexcitation, external faults with current transformer (CT) saturation, and magnetizing inrush. Subsequently, the faulty core unit (series or exciting) is located, and the transients are identified. Six well-known classifiers are trained on features extracted from one-cycle of post transient 3-phase differential currents filtered by an event detector. Maximum Relevance Minimum Redundancy, Random Forest, and exhaustive search with Decision Trees are used to select the relevant wavelet energy, time-domain, and wavelet coefficient features respectively. The fault detection scheme trained on XGBoost classifier with hyperparameters obtained from Bayesian Optimization gives an accuracy of 99.8%. The reliability of the proposed scheme is verified with varying tap positions, noise levels, and transformer ratings; and under different conditions like CT saturation, fault during magnetizing inrush, series core saturation, low current faults, and integration of wind energy. As a potential application, the methodology can be deployed to supervise microprocessor-based differential relays to improve the security and dependability of the protection system.

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Section: External Fault With Ct Saturationmentioning

confidence: 99%

A Data Mining Based Protection and Classification of Transients for Two-Core Symmetric Phase Angle Regulators

Bera

Işık

2021

IEEE Access

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“…A large magnitude of fault current may cause the secondary induction electromotive force to reach its saturated value and then force CT into saturation [41]. After the occurrence of CT saturation, the excitation reactance is sharply reduced; thus, the excitation branch approximates to the short-circuit condition, which causes the CT secondary current to exponentially decay.…”

Section: ) Internal Fault With Ct Saturationmentioning

confidence: 99%

Transient Current Similarity-Based Protection for Interconnecting Transformers in Wind Farms

2019

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Large-scale wind farms are usually integrated into transmission systems through interconnecting transformers. Applying traditional, steady-state, fundamental frequency-based differential protection (DP) strategies in these interconnecting transformers creates challenges. First, the fault current of wind farms might be dominated by non-fundamental frequency components caused by the activation of their own protection systems during low-voltage ride-through (LVRT). Second, the fault current contains low-order components that may affect the second-harmonic restraint algorithm of the transformer DP, thereby blocking the differential relay for a long time. Therefore, a novel transient current similarity-based protection scheme is proposed to deal with these issues. The current protection scheme uses the fundamental frequency and non-fundamental frequency characteristics and can, therefore, reduce the influence of LVRT to a minimum. The proposed method uses transient current (within 15 ms after fault inception) and ignores the features of steady-state fault current. In the proposed method, an improved Hausdorff distance algorithm is used to calculate the similarity of transient current signals at both ends of the interconnecting transformer. The simulation results demonstrate that using a common sampling frequency, the proposed protection scheme reveals current information, correctly identifies magnetizing currents and internal transformer faults in a short period, and achieves superior performance in cases of abnormal data, missing data, and noise.INDEX TERMS Wind farm, interconnecting transformer, differential protection, magnetizing current, similarity.

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“…Authors in [15] propose a method that is based on current behavior in the differential protection scheme. During external faults resulting to CT saturation the shape of the differential current has two specific sections.…”

Section: Introductionmentioning

confidence: 99%

Detection of the initial region of the current transformer core saturation

Odinaev¹,

Pazderin²,

Murzin³

et al. 2024

RE&PQJ

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In the first part of the paper the detailed analysis of the existing current transformer (CT) saturation detection methods with their classification is presented. A new saturation detection method has been proposed in second part of the paper. Mathematical description of the method is given. In the next section of the paper a CT model with test scheme is presented. To identify the reliability of proposed method against nose and remanent flux density experiments have been produced in the fourth section. Comparative analysis between proposed and existing methods is also given. Finally, in conclusion a detailed description of the method is given regarding its behavior with respect to remanent flux and noise

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Histogram-Based Method to Avoid Maloperation of Transformer Differential Protection Due to Current-Transformer Saturation Under External Faults

Cited by 31 publications

References 33 publications

A Data Mining Based Protection and Classification of Transients for Two-Core Symmetric Phase Angle Regulators

A Data Mining Based Protection and Classification of Transients for Two-Core Symmetric Phase Angle Regulators

Transient Current Similarity-Based Protection for Interconnecting Transformers in Wind Farms

Detection of the initial region of the current transformer core saturation

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