CN201918719U - A three-phase transformer excitation inrush current suppression circuit - Google Patents

Abstract

The utility model discloses an exciting-surge-inhibiting circuit for three-phase transformers, which belongs to the technical field of electric engineering technology. The exciting surge-inhibiting circuit comprises a three-phase rectifier bridge and a direct-current inducer, the three-phase rectifier bridge comprises six diodes, the direct-current inducer is connected with the direct-current side of the rectifier bridge, the whole exciting surge-inhibiting circuit is connected with the joint among three primary windings of a three-phase transformer, and the three primary windings are connected in the form of a star. The circuit adopts the method of the hardware circuit, the designed exciting surge-inhibiting circuit can effectively inhibit the exciting surge of medium-capacity and large-capacity three-phase transformers, moreover, the structure is simple, the cost is low, and the stability of a system can be enhanced.

Description

A three-phase transformer excitation inrush current suppression circuit

technical field

The utility model relates to a three-phase transformer inrush suppression circuit, which can effectively suppress the excitation inrush current of medium and large-capacity three-phase transformers, and belongs to the technical field of electrical engineering technology.

Background technique

Transformer core material, magnetic circuit structure, the size and direction of the original residual magnetism, no-load closing initial phase angle and power supply voltage amplitude, system equivalent internal impedance and many other factors, all affect the magnitude of the inrush current of the transformer. In practical applications, the above factors cannot be eliminated, so the excitation inrush current generally exists in the power system, and the frequency of the excitation inrush current is relatively high. The adverse effects of the inrush current mainly include: 1) The inrush current with a large peak value and a large number of high-order harmonics causes a large vibration of the iron core, endangers the mechanical strength of the related parts of the iron core, and causes a lot of noise; 2) Excitation When the inrush current is large, it is easy to trip the relay protection, and the sudden disconnection of such a large inrush current will cause the internal overvoltage of the transformer; 3) The inrush current generated by the air-dropped transformer flows through the upper-level or parallel operation transformers, which easily causes their relay protection to fail. move.

Contents of the invention

In view of the above-mentioned technical problems in the prior art, the purpose of this utility model is to provide a three-phase transformer suppression circuit by using a hardware circuit method, which can suppress the excitation inrush current of the transformer.

In order to realize the above-mentioned purpose of the invention, the technical scheme of the utility model is:

A three-phase transformer excitation inrush suppression circuit, including a three-phase rectifier bridge composed of six diodes and a DC inductor, the DC inductor is connected to the DC side of the rectifier bridge; the suppression circuit is connected to three star-connected three-phase transformers At the connection point of the primary winding.

The suppression circuit of the utility model can effectively suppress the excitation inrush current of the three-phase transformer with medium and large capacity, has simple structure, low cost and can improve the stability of the system.

Description of drawings

Fig. 1 is a circuit diagram of the excitation inrush suppression circuit of the three-phase transformer of the present invention.

Detailed ways

Below in conjunction with accompanying drawing and embodiment, the utility model is described in further detail.

As shown in Figure 1, where Wa, Wb, and Wc are the three primary windings of the three-phase transformer, since there is no special requirement for the secondary winding of the transformer, the secondary circuit is omitted. Six diodes D1, D2, D3, D4, D5, and D6 are used to form a three-phase rectifier bridge, and a DC inductance L1 is arranged on the DC side of the rectifier bridge, thereby forming a three-phase transformer excitation inrush suppression circuit of the present invention, and The suppression circuit is connected to the star connection points of the three primary windings Wa, Wb and Wc of the three-phase transformer.

Before the transformer is switched on, the current in the DC inductor L1 is zero. After the transformer is switched on, the current in the inductor L1 must increase from zero, and the inductor current cannot change suddenly, so that the excitation inrush current of the transformer is suppressed by the inductor L1. Since the inductor L1 is located on the DC side of the rectifier bridge, the current in the inductor L1 continues to increase under the action of the DC voltage, and enters a stable working state after reaching the maximum load current. Neglecting the on-state voltage drop of diodes D1-D6 and the loss of inductor L1, there is no voltage drop at both ends of the excitation inrush current suppression circuit composed of diodes D1-D6 and inductor L1, and there is no adverse effect on the system.

Claims (1)

1. A three-phase transformer excitation inrush suppression circuit, including a three-phase rectifier bridge composed of six diodes (D1-D6) and a DC inductance (L1), is characterized in that: the DC inductance (L1) is connected to the DC of the rectifier bridge side; the suppression circuit is connected to the connection point of the three primary windings of the three-phase transformer star-connected.

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