CN103617875A - Method for restraining neutral point electric potential drifting of low-voltage winding - Google Patents

Abstract

The invention provides a method for restraining neutral point electric potential drifting of a low-voltage winding. A high-voltage winding, the low-voltage winding and a balance winding are adopted in the method. The method for restraining neutral point electric potential drifting of the low-voltage winding comprises one of the following steps that (1) if a neutral point of the low-voltage winding is provided with a leading-out terminal, a neutral point of a Y-connected winding of the low-voltage winding is grounded; (2) if the neutral point of the low-voltage winding is not provided with the leading-out terminal, a grounding point of the balance winding is untied, connected to a lightning arrester in series and then grounded. The method for restraining neutral point electric potential drifting of the low-voltage winding and the structure are simple, the method is practical, easy to modify, capable of saving energy and efficient, low-voltage neutral point electric potential drifting generated after a balance winding transformer is operated is eliminated, and therefore damage, caused by imbalanced three-phase voltage generated by neutral point electric potential, to power devices such as a power transmission line, the transformer, a mutual inductor and the lightning arrester is avoided.

Description

A kind of method that suppresses low pressure winding neutral point potential drifting

Technical field

The present invention relates to power transformer technical field, be specifically related to a kind of method for the inhibition low pressure winding neutral point potential drifting with balance winding transformer.

Background technology

Existing in 220 kilovolts of autotransformers of system interconnection transformer, its connection is generally YNa0yn0+d, transformer connection also conventional YNyn0+d for some 500 kilovolts of Converter Station, these transformer device structure features are that Working winding is star (Y) connection, in order to allow transformer can obtain the sinusoidal magnetic flux corresponding with applying voltage waveform, generally at the inner balance winding that increases delta connection of transformer, be used for providing the distribution channel of triple harmonic current, make transformer in free excited state.This winding is not generally with live load, by single sleeve pipe or by two sleeve pipes, draws.

When transformer moves, because low pressure winding is 35kV and following electric pressure, neutral point is conventionally earth-free or through grounding through arc, and in balance winding triangle, only has one point earth, typical case connects signal as shown in Figure 3, now because the capacitive coupling effect between winding makes low-pressure side neutral point current potential, drift about, thereby cause low-pressure side three phase-to-ground voltages that in various degree asymmetric occurs.As shown in Figure 4.The imbalance of three-phase voltage being caused by neutral point current potential will form serious threat to power equipments such as power transmission line, transformer, instrument transformer, lightning arresters, must eliminate in time.

Summary of the invention

Technical problem to be solved by this invention is: after putting into operation for prior art band balance winding transformer, the phenomenon of drift in various degree occurs low pressure neutral point current potential, and a kind of method that suppresses low pressure winding neutral point potential drifting is proposed, the threat that the imbalance of three-phase voltage that elimination is caused by neutral point current potential forms power equipments such as power transmission line, transformer, instrument transformer, lightning arresters, guarantees power equipment safety reliability service.

The technical solution used in the present invention is:

A method that suppresses low pressure winding neutral point potential drifting, comprises high pressure winding, low pressure winding and balance winding, the specific practice that suppresses low pressure winding neutral point potential drifting be following both one of:

1) if when low pressure winding neutral point has exit, the Y of low pressure winding is connect to winding neutral ground;

2) if when low pressure winding neutral point does not have exit, balance winding earth point is untied to ground connection again after serial connection lightning arrester.

The inventive method and simple in structure, practical, energy-conservation, efficient, rectification easily, eliminate the low pressure neutral point potential drifting after putting into operation with balance winding transformer, avoided the infringement to power equipments such as power transmission line, transformer, instrument transformer, lightning arresters of the imbalance of three-phase voltage that caused by neutral point current potential.Application of the present invention has successfully solved the problem of station, 500 kilovolts, Yue Loong station, Sichuan with transformer low voltage neutral point potential drifting, has avoided station, Yue Loong station to hang cover and rectification lead-in wire with the scene of transformer, saves the hundreds thousand of units of rectification expense.

Accompanying drawing explanation

Fig. 1 is the embodiment of the present invention 1 principle schematic;

Fig. 2 is the embodiment of the present invention 2 principle schematic;

Fig. 3 is background technology principle schematic;

Fig. 4 is background technology coordinate analysis figure.

In Fig. 1, Fig. 2, Fig. 3,1-high pressure winding, 2-low pressure winding, 3-balance winding, 4-neutral ground, 5-lightning arrester; In Fig. 4, the winding neutral point that OS-is virtual, low pressure winding neutral point after the actual drift of O-.

Embodiment

? embodiment 1 shown in Figure 1, the present embodiment is that low pressure neutral point does not have exit, thereby adopts balance winding earth point is untied after serial connection lightning arrester to ground connection again, can suppress low pressure winding neutral point potential drifting.

Embodiment 2 shown in Figure 2, the present embodiment is that low pressure neutral point has exit, thereby as long as the Y that is Working winding by low pressure winding connects winding neutral ground, just can suppress low pressure winding neutral point potential drifting.

Claims (1)

1. a method that suppresses low pressure winding neutral point potential drifting, comprises high pressure winding, low pressure winding and balance winding, it is characterized in that, the specific practice that suppresses low pressure winding neutral point potential drifting be following both one of:

1) if when low pressure winding neutral point has exit, the Y of low pressure winding is connect to winding neutral ground;

2) if when low pressure winding neutral point does not have exit, balance winding earth point is untied to ground connection again after serial connection lightning arrester.

Images