The effect of transformer non-synchronous energization on differential protection and its countermeasure

Zheng, Tao; Shen, Hongming; Huang, Shaofeng; Chen, Peilu; Chen, Shuiyao

doi:10.1002/etep.2083

Cited by 2 publications

(2 citation statements)

References 13 publications

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“…The second harmonic component in the inrush current is used to detect whether the transformer is experiencing inrush or faulty conditions, and the fifth harmonic component is used to identify the fault conditions . A modified harmonic restraint‐based relay is proposed in Zheng et al to avoid the mal‐operation of the relay during the nonsynchronous energization of the transformer. Single slope and dual slope characteristics suggested in a technical manual provide sensitivity towards internal fault as well as security to the external fault.…”

Section: Introductionmentioning

confidence: 99%

Adaptive differential protection for transformers in grid-connected wind farms

George

Ashok

2018

Int Trans Electr Energ Syst

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Summary In response to energy requirements and environmental concerns, renewable energy technologies including wind power are considered to be the potential alternatives. Generally, wind farms are integrated into the grid through a transformer, and its rating depends upon the capacity of wind farms. The fault current of the system to which wind farm is connected changes according to the wind generators in service as well as with the wind speed. The study shows that the existing differential relay for transformer protection mal‐operates during fault interval according to the operating conditions of the wind farm. Under such conditions, the generalized characteristics for the differential relay of the transformer need modification. The protection scheme should be capable of functioning satisfactorily under various dynamic conditions of the wind, which can be achieved through adaptive relaying. In this work, an algorithm for transformer differential protection according to the variation in wind power injection is proposed. A case study of a typical wind farm shows that the proposed algorithm adaptively modifies the settings of the differential relay with varying wind farm currents, according to the wind generators in service, as well as with regard to different wind speed conditions. The modified algorithm is also validated using the experimental setup in the laboratory.

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Section: Introductionmentioning

confidence: 99%

Adaptive differential protection for transformers in grid-connected wind farms

George

Ashok

2018

Int Trans Electr Energ Syst

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“…Energization of power system components is accompanied by a switching transient, and the energization transients of components such as transformers, shunt capacitor banks, and conventional shunt reactors have been well documented. However, owing to their special body structures, MCSR energization transients are more complicated than those of conventional shunt reactors and transformers, and there has not been much research so far on the energization of MCSRs …”

Section: Introductionmentioning

confidence: 99%

Modeling and impacts analysis of energization transient of EHV/UHV magnetically controlled shunt reactor

Zheng

Huang

Zhang

et al. 2017

Int. Trans. Electr. Energ. Syst.

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To address the problems of overvoltage, harmonic distortion, and mal-operation that can occur in protection systems as a result of direct energization in magnetically controlled shunt reactors (MCSRs), this paper proposes a novel approach for MCSR energization-namely, pre-excited energization. Using the structure and operating principles of an MCSR, a detailed derivation of energization transient mathematical model for both direct and pre-excited energization are presented and the model-specific impacts of the 2 different energization modes are investigated. To validate the theoretical analysis, we performed physical model tests and simulations of different energization modes. The results indicate that pre-excited energization is capable of suppressing overvoltage on the DC link bus and alleviating harmonics caused by direct energization. KEYWORDS energization, impacts analysis, magnetically controlled shunt reactor (MCSR), mathematical model, transient characteristics 1 | INTRODUCTIONControllable shunt reactors placed on line terminals or substation bus bars play an important role in extra high-/ultra high-voltage (EHV/UHV) transmission networks of voltage control and reactive power compensation. 1-3 With the advantages of continuously adjustable capacity, 4 low harmonics, 5 and excellent steady-state control characteristics, 6 magnetically controlled shunt reactors (MCSRs) are preferable for reactive power compensation in EHV/UHV power systems. Energization of power system components is accompanied by a switching transient, 7,8 and the energization transients of components such as transformers, 9-11 shunt capacitor banks, 12-14 and conventional shunt reactors 15 have been well documented. However, owing to their special body structures, MCSR energization transients are more complicated than those of conventional shunt reactors and transformers, and there has not been much research so far on the energization of MCSRs. 16 The simplest energization strategy for MCSRs at present is direct energization, in which the DC excitation system is blocked. As with transformer energization, one of the main problems associated with the MCSR direct energization transient is the occurrence of inrush current with a large number Symbols: _ U m , System bus voltage where MCSR is equipped; α, Phase angle of the system bus voltage at the instant of energization; U k , DC excitation source voltage; i 1 , Current of the grid-side winding; i k , Current of the control winding in the single phase MCSR; R 1 , Resistance of the grid-side winding; R k , Resistance of the control winding; R w , Balance resistor; N 1 , Number of turns in the grid-side winding; N 2 , Number of turns in the control winding; N 3 , Number of turns in the compensation winding; A, Area of the iron limb; l, Magnetic path length of the iron limb; i kA , Current of phase A in the control windings; i kB , Current of phase B in the control windings; i kC , Current of phase C in the control windings; i t , Total current of control windings; I dc , DC excitation current;...

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The effect of transformer non-synchronous energization on differential protection and its countermeasure

Cited by 2 publications

References 13 publications

Adaptive differential protection for transformers in grid-connected wind farms

Adaptive differential protection for transformers in grid-connected wind farms

Modeling and impacts analysis of energization transient of EHV/UHV magnetically controlled shunt reactor

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