ANSI 87T-Based Differential Protection of 3ϕ Solid-State Transformers

Saleh, S. A.; Ozkop, E.

doi:10.1109/ias44978.2020.9334837

Cited by 2 publications

(1 citation statement)

References 22 publications

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“…As power systems have adapted to irregular operation, power transformers have shown limited ability to support the new functionalities introduced by operational disturbances [22][23][24][25]. Such functionalities include power flow control, the integration of distributed generation and storage, voltage and frequency regulation, power quality improvement, and DC load integration [24][25][26][27][28][29][30][31][32][33][34][35].…”

Section: Introductionmentioning

confidence: 99%

Experimental Study of the Dynamic Short-Circuit Withstand Capability of an 8400 kVA Power Transformer Specially Designed for Photovoltaic Applications

Sălceanu,

Dobrea,

Ocoleanu

et al. 2023

Machines

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This article, besides offering data of great value for any designer of high-power short-circuits of special three-winding design, illustrates the correlation with the corresponding FRA measurements, validating this type of measurement. The frequency response measurements can provide data about the transformer’s status after it is put into service, its vulnerability in incipient states, and, particularly for this type of transformer, its insulation, which is the subject of high dielectric stress due to its invertor working regime. This article presents the behavior of a three-phase 8400 kVA medium-voltage step-up transformer (corrugated hermetic tank) specially designed for photovoltaic applications during short-circuit tests. This transformer, fed by two inverters, has two secondaries with elliptical windings (non-circular aluminum foil for LV windings and an aluminum conductor for HV windings). Various experiments were performed, including measurements of winding resistance, measurements of voltage ratio, measurements of short-circuit impedance and load loss on three tappings, measurements of no-load loss and current, a frequency response analysis, and short-circuiting. These experiments were performed to study the behavior of the transformer, which, in real life, is powered by photovoltaic inverters on the LV side that feed into the MV grid on the HV side, making it the interface between the photovoltaic inverter and the MV grid. An auxiliary supply transformer may be connected to the LV side. Given these elements, concerning both the importance and the particularities of the problem studied, we can say that this article represents a niche study on the guarantee of good functioning and safety in operation given the passing of the test to withstand the dynamic effects of short-circuiting.

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Section: Introductionmentioning

confidence: 99%

Experimental Study of the Dynamic Short-Circuit Withstand Capability of an 8400 kVA Power Transformer Specially Designed for Photovoltaic Applications

Sălceanu,

Dobrea,

Ocoleanu

et al. 2023

Machines

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An Approach to Performing Stability Analysis for Power Transformer Differential Protection: A Case Study

Sheryar¹,

Ali²,

Umer

et al. 2022

Energies

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Differential protection normally detects short circuits and ground faults in the windings of a power transformer and its terminals. Inter-turn faults refer to flashovers among the electrodes that arise only in a similar type of physical winding. Inter-turn faults can be examined when the adequate sum of turns is served as short-circuited. In electrical protection, it is difficult to detect inter-turn faults. An inter-turn fault of small magnitude is based on the limited number of turns that resultantly provide a large quantity of current. Due to this reason, protection that comes from the differential scenario possesses a higher degree of sensitivity without causing unwanted operations during external faults. In this paper, a protection-based stability method is proposed whereby external voltages are applied at the low-voltage (LV) side of the transformer while keeping the high-voltage (HV) side short-circuited. This was conducted using a three-phase power transformer (rating: 100 MVA, 380 kV/13.8 kV) at SWCC Shoaiba Power Plant, Saudi Arabia. In this work, differential protection (87T) and high-impedance differential protection for HV-restricted earth faults (REFs) were verified by creating In-Zone and Out-Zone fault conditions to ensure current transformer (CT) circuits and tripping logic. All of the IEDs, protection, and control schemes involved were designed by ABB. This method verifies protection stability for power transformers by implementing differential protection (87T) and high-impedance restricted earth fault (64HV) schemes through creating In-Zone and Out-Zone fault conditions.

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ANSI 87T-Based Differential Protection of 3ϕ Solid-State Transformers

Cited by 2 publications

References 22 publications

Experimental Study of the Dynamic Short-Circuit Withstand Capability of an 8400 kVA Power Transformer Specially Designed for Photovoltaic Applications

Experimental Study of the Dynamic Short-Circuit Withstand Capability of an 8400 kVA Power Transformer Specially Designed for Photovoltaic Applications

An Approach to Performing Stability Analysis for Power Transformer Differential Protection: A Case Study

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