Generator Neutral Grounding Some Aspects of Application for Distribution Transformer with Secondary Resistor and Resonant Types

Brown, P. G.; Johnson, I. B.; Stevenson, Jàmes R.

doi:10.1109/tpas.1978.354539

Cited by 25 publications

(4 citation statements)

References 4 publications

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“…At present, some research is being carried out on the dynamic characteristics of singlephase grounding fault of a hydro generator stator winding at home and abroad. P. G. Brown and others first put forward the transient simulation analyzer (TNA) model [9], and our peers put forward some improved models [10], but the above research methods are based on the lumped capacitance parameter model, and the physical parameters are more simplified, which will bring unavoidable errors. In order to solve this problem, Li Ruliang and others proposed a quasi-distributed capacitance parameter model based on Pspice simulation, which divides the stator winding into multiple circuit units [11,12], and the distributed capacitance of the stator winding to the ground is equivalent to the quasi distributed form.…”

Section: Introductionmentioning

confidence: 99%

Study on Dynamic Characteristics of Single-Phase Grounding Fault of 1000 MW Hydro Generator under Different Grounding Modes

2022

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The continuous operation of 1000 MW large hydro generators in China is of great value to the implementation of “double carbon strategy” and power grid safety. However, with the continuous increase of single unit capacity of the hydro generator, the problems of unit fault grounding current and neutral point voltage drift become more and more prominent, and the traditional analysis methods cannot accurately obtain the fault dynamic data. Therefore, starting from the neutral point grounding mode of the large hydro generator, taking a 1000 MW hydro generator as the research object, this paper establishes the single-phase grounding fault model under the condition of three-phase parameter asymmetry of stator winding and analyzes the dynamic characteristics of fault current, transient overvoltage, and neutral point voltage drift under different grounding modes by using transient analysis method; the influence of frequency offset on neutral voltage drift and the dynamic characteristics of single-phase grounding fault of the large hydro generator under different grounding modes are also obtained. Finally, according to the analysis results, the selection and optimization method of neutral grounding parameters are proposed, which provides a reference for the selection of neutral grounding mode and the research of protection strategy of the large hydro generator.

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Section: Introductionmentioning

confidence: 99%

Study on Dynamic Characteristics of Single-Phase Grounding Fault of 1000 MW Hydro Generator under Different Grounding Modes

2022

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“…These considerations are common to grounding all types of apparatus. The available classes of grounding may be ranked as follows in order of increasing temporary overvoltages assuming a fault resistance that yields the highest coefficient of grounding but neglects theeffects of restrikes within a solid dielectric [15]: [5].) It is, therefore, important when selecting a grounding class to consider the transient and temporary overvoltages that will result and the stresses on apparatus insulation and the protective margins possible with surge protective devices.…”

Section: Limiting Overvoltages On Generator Insulationmentioning

confidence: 99%

IEEE Guide for the Application of Neutral Grounding in Electrical Utility Systems, Part II-Grounding of Synchronous Generator Systems

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“…The statistical data of the transient overvoltage for medium-voltage grounding systems are scarce. However, in 1978, Brown, et al [3], based on their research on a 750-MVA 21-kV generator neutral distribution-transformer grounded system, concluded the following. "A high frequency over-voltage transient from fault initiation on a sound phase is in the order of 2.5 p.u.…”

Section: Introductionmentioning

confidence: 99%

“…Consequently, could be in a range of 0.4-1.5 s. Powell [5] estimated is in a range of 0.8-1.1 s. Therefore, the damage caused by the stator ground fault is proportional to energy released at the fault point Damage energy (3) where is the initial ground current, and is the generator single-line-ground short-circuit time constant. Fig.…”

Section: Introductionmentioning

confidence: 99%

MV generator low-resistance grounding and stator ground fault damage

Wu¹,

Tang²,

Finney³

Conference Record of the 2004 IEEE Industry Applications Conference, 2004. 39th IAS Annual Meeting.

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Most of the in-plant medium-voltage generators are grounded through resistors ranging from 200 to 400 A. In some unusual situations, the resistors may even be as high as 1200 A. Low-resistance grounding is a preferred choice for a medium-voltage power distribution system. However, extensive generator stator ground fault damages had been reported due to the prolonging generator neutral ground current, which would continue to flow even after the main and field breaker opened. This ground fault current could continue to flow for as long as 5 s depending on the generator open-circuit time constant . As a result, the higher the generator neutral current, would lead to the higher stator ground fault damages. An IEEE Working Group has recently completed its study and made recommendations for medium-voltage generator grounding in a multiple source industrial environment. Based on the considerations of transient overvoltage, ground fault damages, and ground fault protection, the working group suggests a few variations of grounding systems, which basically are low-resistance grounding systems during normal operating conditions, and the generator would be switched to a high-resistance grounded system from a normal low-resistance grounded system when a ground fault occurs in the generator stator. The purposes of this paper are: 1) to examine the generator transient over-voltage and currents under the low-resistance ground fault conditions, and also to evaluate their corresponding stator ground fault damages, and 2) to establish an acceptable maximum system ground fault level. For comparison purposes, three versions of low-resistance grounding systems have been considered and they are: a low-resistance grounding system with a neutral breaker at the generator (hereinafter called a "neutral breaker system"); a low-resistance grounding system with the generator neutral low resistor being switched to a high-resistor after a stator ground fault (hereinafter called a "hybrid system"); and a low-resistance grounding system similar to the current practice (hereinafter called a "traditional system"). The simulation study is conducted with the aid of the Electro Magnetic Transient Program. An experimental analog generator model is also used to verify the simulation results.Index Terms-Neutral breaker grounding system and hybrid grounding system, stator ground fault damage, transient overvoltage.

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Generator Neutral Grounding Some Aspects of Application for Distribution Transformer with Secondary Resistor and Resonant Types

Cited by 25 publications

References 4 publications

Study on Dynamic Characteristics of Single-Phase Grounding Fault of 1000 MW Hydro Generator under Different Grounding Modes

Study on Dynamic Characteristics of Single-Phase Grounding Fault of 1000 MW Hydro Generator under Different Grounding Modes

IEEE Guide for the Application of Neutral Grounding in Electrical Utility Systems, Part II-Grounding of Synchronous Generator Systems

MV generator low-resistance grounding and stator ground fault damage

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