Reduction of Three-Phase Transformer Inrush Currents Using Controlled Switching

Mitra, Joydeep; Xu, Xufeng; Benidris, Mohammed

doi:10.1109/tia.2019.2955627

Cited by 37 publications

(24 citation statements)

References 50 publications

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“…𝐿 is variable in nature and is estimated from the fluxmagnetizing current slope, resulting in a very low inductance value in saturation region, and consequently very high magnetizing current. Assuming negligible 𝐿 and very high 𝑅 values for simplification, and considering that the secondary side is open-circuit during energization, the core flux 𝜙 can be estimated as in Equation ( 8) from [34], where 𝜙 is the residual core flux following previous de-energization, and 𝛼 is the voltage angle at the energization instant. as in Equation ( 8) from [34], where φ r is the residual core flux following previous deenergization, and α is the voltage angle at the energization instant.…”

Section: Black-start/ac Synchronization Modesmentioning

confidence: 99%

“…Assuming negligible 𝐿 and very high 𝑅 values for simplification, and considering that the secondary side is open-circuit during energization, the core flux 𝜙 can be estimated as in Equation ( 8) from [34], where 𝜙 is the residual core flux following previous de-energization, and 𝛼 is the voltage angle at the energization instant. as in Equation ( 8) from [34], where φ r is the residual core flux following previous deenergization, and α is the voltage angle at the energization instant.…”

Section: Black-start/ac Synchronization Modesmentioning

confidence: 99%

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Innovative Energy Management System for MVDC Networks with Black-Start Capabilities

et al. 2021

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Medium voltage DC (MVDC) networks are attracting more attention amid increased renewables penetration. The reliability of these DC systems is critical, especially following grid contingencies to maintain critical loads supply and provide ancillary services, such as black-start. This paper proposes an innovative energy management system (EMS) to maintain reliable MVDC network operation under prolonged AC grid contingencies. Similar EMS designs in literature tend to focus on limited operating modes and fall short of covering comprehensive elongated blackout considerations. The proposed EMS in this paper aims to preserve the distribution network functionality of the impacted MVDC system through maintaining a constant DC bus voltage, maximizing critical load supply duration, and maintaining the MVDC system black-start readiness. These objectives are achieved through controlling generation units between Maximum Power Point Tracking (MPPT) and Voltage Regulation (VR) modes, and implementing a smart load shedding and restoration algorithm based on network parameters feedback, such as storage State of Change (SoC) and available resources. Practical design considerations for MVDC network participation in AC network black start, and the following grid synchronization steps are presented and tested as part of the EMS. The proposed system is validated through simulations and scaled lab setup experimental scenarios.

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Section: Black-start/ac Synchronization Modesmentioning

confidence: 99%

Section: Black-start/ac Synchronization Modesmentioning

confidence: 99%

Innovative Energy Management System for MVDC Networks with Black-Start Capabilities

et al. 2021

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“…[13] calculated the impulse current and torque generated by PSE, and defined the conditions under which the system can sustain the PSE impulse, and proposed split-phase control can suppress the impulse to a certain extent. At present, there are many different phase control methods have been proposed to suppress the impulse current caused by component access or removal, such as that for the reduction of the impulse current of a three-phase transformer [14][15][16][17][18]. However, there is still no physics or experiment to prove which phase control method is the best to suppress the impulse of PSE.…”

Section: Introductionmentioning

confidence: 99%

An optimal phase control method for the suppression of phase sequence exchange impulse current and voltage

Sun

et al. 2022

IET Power Electronics

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Phase sequence exchange (PSE) is an emerging emergency control method for power systems. However, PSE will generate impulse current and voltage. In this research, to suppress the impulse of PSE, a phase control method for zero-current opening and equal-voltage closing is adopted, and verified via both physics and experiments. First, an equivalent circuit is established, and the differential equations are solved to validate that this phase control method is the optimal method for the suppression of the impulse current and voltage in PSE. Then, the action sequence scheme and calculation method of the phase control method are advanced. Finally, based on the real-time digital simulation system (RTDS), a PSE prototype was used to carry out impact experiments. The results verify that the performance of the optimal method is the best compared to those of other control methods, the requirement for the sampling frequency is low, and there is almost no additional cost. In the two experiments, the first peak of the impulse current was found to be reduced by 47.49% and 33.28% on average, respectively, and the first peak of the impulse voltage was found to be reduced by 14.89% and 44.10% on average, respectively.

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“…Sometimes this current may be 6 to 8 times higher than the rated state current [9], which will result the transformer failing to connect with the power grid. To suppress inrush current, synchronous closing technology and phase selection closing technology are proposed in [10]- [12], on the premise of Br magnitude and direction being obtained [13]. Moreover, demagnetization without knowing the magnitude of Br in the transformer core is not only time consuming and laborious, but also has a poor demagnetization effect [14].…”

Section: Introductionmentioning

confidence: 99%

Residual Flux Density Measurement Method of Single-Phase Transformer Core Based on Time Constant

Huo

Yang

et al. 2020

IEEE Access

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Residual flux density in the single-phase transformer core can dramatically increase inrush current when the transformer is energized. To reduce inrush current, it is necessary to study residual flux density measurement. This paper proposes a new residual flux density measurement method based on time constant. Firstly, the generation principle of residual flux density is analyzed under different magnetization states, and it is found that the positive relative differential permeability is smaller than the negative at different residual flux density. To obtain the relative differential permeability, when an appropriate DC excitation is applied, the measurement circuit is equivalent to a first-order RL circuit. Then, combining magnetic circuit and transient circuit analysis, the relationship between time constant and relative differential permeability is obtained. It is conclusion that the positive time constant is less than the negative. Residual flux density direction is determined by comparing the positive and negative time constant, and the magnitude of residual flux density is calculated by the relationship between residual flux density and the difference of the positive and negative time constant. Finally, the empirical formula between residual flux density and time constant difference of the square core is obtained in finite element method, and then verified on the experimental platform. Compared with other measurement methods, the relative error of proposed empirical formula is within 4.58 %, and it has higher accuracy in this paper. The proposed method in this paper can provide a reference for selecting the demagnetization voltage, which improves the effectiveness of demagnetization. INDEX TERMS Residual flux density, relative differential permeability, time constant difference, empirical formula.

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Reduction of Three-Phase Transformer Inrush Currents Using Controlled Switching

Cited by 37 publications

References 50 publications

Innovative Energy Management System for MVDC Networks with Black-Start Capabilities

Innovative Energy Management System for MVDC Networks with Black-Start Capabilities

An optimal phase control method for the suppression of phase sequence exchange impulse current and voltage

Residual Flux Density Measurement Method of Single-Phase Transformer Core Based on Time Constant

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