Device for suppressing operating overvoltage of transformer or reactor

Abstract

The utility model relates to a device for suppressing operating overvoltage of a transformer or an electric reactor, which belongs to the technical field of power transmission and distribution and comprises a switch circuit breaker, the electric reactor or the transformer, a capacitor, a discharge ball gap and a lightning arrester, the tail end of the capacitor is connected with the discharge ball gap in series, and the head end of the capacitor is connected with the head end of the electric reactor or the transformer. The tail end of the discharge ball gap is grounded, the head end of the lightning arrester is connected with the wire outlet end of the electric reactor or the transformer, and the tail end of the lightning arrester is grounded. According to the utility model, through the overvoltage suppression technology, an important supplement is provided for insufficient overvoltage protection of the lightning arrester, and the damage of overvoltage to a reactor and a transformer can be greatly reduced theoretically and practically, so that the use safety of equipment is ensured.

Description

Technical Field

[0001] The utility model relates to the technical field of power transmission and distribution, in particular to a device for suppressing operating overvoltage of a transformer or a reactor, which is a complete set of devices for suppressing damage to the insulation of the transformer or the reactor caused by operating overvoltage. Background Art

[0002] Currently, in the power industry, the protection of reactors and transformers is mainly at the secondary level, implementing relay protection against short circuits to ensure the safe operation of the power grid.

[0003] However, for primary products such as reactors and transformers, in terms of overvoltage protection, apart from using lightning arresters to limit overvoltage, other technologies and products for suppressing system overvoltage are rare. Since lightning arrester protection has certain defects, reactors and transformers in operation are often damaged, and even major accidents are common, seriously affecting the safety and operation of the power grid. Utility Model Content

[0004] In view of the deficiencies in the prior art, the utility model provides a device for suppressing operating overvoltage of a transformer or a reactor, which can greatly reduce the damage of the reactor and the transformer caused by overvoltage.

[0005] The utility model is achieved through the following technical solutions:

[0006] The utility model provides a device for suppressing operational overvoltage of a transformer or a reactor, comprising a switch circuit breaker, a reactor or a transformer, a capacitor, a discharge ball gap and a lightning arrester, wherein the end of the capacitor is connected in series with the discharge ball gap, the head end of the capacitor is connected to the head end of the reactor or the transformer, the end of the discharge ball gap is grounded, the head end of the lightning arrester is connected to the outgoing line end of the reactor or the transformer, the end of the lightning arrester is grounded, and the switch circuit breaker is connected to the head end of the reactor or the transformer.

[0007] Preferably, the discharge ball gap is spherical or rod-shaped, and the gap is configured to break down and conduct under overvoltage and recover after overvoltage.

[0008] Furthermore, the capacitance is preferably 0.05-0.5 microfarads.

[0009] For reactors and transformers, the main overvoltage protection is zinc oxide arrester, whose residual voltage limits the amplitude of the overvoltage but cannot limit its frequency. The shorter the overvoltage wave head, the higher the residual voltage of the zinc oxide arrester. The cut-off overvoltage and the reignition overvoltage are similar to steep waves with extremely short wave heads. Reactors and transformers are inductive loads, and the inter-turn potential gradient is proportional to the steepness of the current, i.e. di / dt. The frequency of the operating cut-off overvoltage and the reignition overvoltage can reach up to several hundred kHz, so the longitudinal insulation of the reactor and transformer is often damaged. Reactors and transformers are inductive energy storage components. After the circuit breaker is disconnected, the stored energy is 1 / 2Li 2 The stray capacitance C of the reactor and transformer is very small, so the energy stored in the reactor and transformer on the transformer side at both ends of the circuit breaker port is 1 / 2Li. 2 , and stray capacitance stores energy 1 / 2CU 2 High-frequency oscillations of electromagnetic energy and electric field energy are generated between them. Due to the small capacitance and large inductance, a large voltage is generated on the capacitor during the energy conversion process. On the other side of the circuit breaker port, that is, the power supply side, there are still inductors and capacitors, so there are also energy conversion-induced overvoltage oscillations. When the peaks of the oscillations at both ends of the circuit breaker port are opposite at a certain moment, repeated breakdown will occur at the circuit breaker port, causing secondary interception overvoltage and oscillation. During electromagnetic oscillation, its frequency changes, which will cause changes in the inductance of other coil products and ferromagnetic protection devices in the system. The frequency and inductance are constantly changing dynamically. The capacitance of stray capacitance and other capacitive devices remains unchanged. The changes in frequency and inductance will inevitably cause a series resonant overvoltage at a certain moment. This will not only damage the reactor and transformer, but may even cause major system quality accidents and damage other components in the entire system.

[0010] The principle of this utility model is to address the shortcomings of the above-mentioned lightning arrester protection. A certain microfarad capacitor is connected in parallel to the ground at the head end of the reactor or transformer, and a discharge spherical gap is connected in series. Under normal operating conditions of the transformer and reactor, the spherical discharge gap is disconnected and no current flows in the capacitor. Under overvoltage, the discharge spherical gap breaks down and the capacitor is connected, which not only reduces the steepness of the overvoltage but also limits the frequency of the overvoltage. This device not only prevents the loss caused by capacitor overload under normal conditions, but also safely and effectively suppresses the oscillation frequency of inductive energy during the conversion process.

[0011] The beneficial effect of the utility model is that the utility model is an important supplement to the insufficient overvoltage protection of the lightning arrester through overvoltage suppression technology. From the theoretical and practical point of view, it can greatly reduce the damage of overvoltage to the reactor and transformer, thereby ensuring the safe use of the equipment. BRIEF DESCRIPTION OF THE DRAWINGS

[0012] Figure 1This is a schematic structural diagram of a device for suppressing transformer or reactor operating overvoltage according to the present invention. DETAILED DESCRIPTION

[0013] The preferred embodiments of the present invention are described in detail below in conjunction with the accompanying drawings so that the advantages and features of the present invention can be more easily understood by those skilled in the art, thereby making a clearer and more precise definition of the protection scope of the present invention.

[0014] Combine Figure 1 The device shown is a device for suppressing operational overvoltage of a transformer or reactor, comprising a switch circuit breaker 1, a reactor or transformer 2, a capacitor 3, a discharge ball gap 4 and a lightning arrester 5. The end of the capacitor 3 is connected in series with the discharge ball gap 4, the head end of the capacitor 3 is connected to the head end of the reactor or transformer 2, the end of the discharge ball gap 4 is grounded, the head end of the lightning arrester 5 is connected to the outgoing terminal of the reactor or transformer 2, the end of the lightning arrester 5 is grounded, and the switch circuit breaker 1 is connected to the head end of the reactor or transformer 2.

[0015] The utility model installs a lightning arrester 5 between the head end of the reactor or transformer 2 and the ground, and then connects a capacitor 3 and a discharge ball gap 4 in series and then in parallel between the head end of the reactor or transformer 2 and the grounding point; the discharge ball gap 4 is spherical or rod-shaped, and the gap is set to: break down and conduct under overvoltage and recover after overvoltage; the capacitor 3 adopts 0.05-0.5 microfarads; the lightning arrester 5 protects the main insulation of the reactor or transformer 2, and the combination of the capacitor 3 and the discharge ball gap 4 protects the longitudinal insulation of the reactor or transformer.

[0016] The above-described embodiments merely represent several implementation methods of the present invention. While the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the patent. It should be noted that a person skilled in the art would be able to make numerous variations and improvements without departing from the concept of the present invention, and all such variations and improvements fall within the scope of protection of the present invention.

Claims

1. A device for suppressing transformer or reactor operating overvoltage, characterized by: It includes a switch circuit breaker, a reactor or a transformer, a capacitor, a discharge ball gap and a lightning arrester. The end of the capacitor is connected in series with the discharge ball gap, the head end of the capacitor is connected to the head end of the reactor or the transformer, the end of the discharge ball gap is grounded, the head end of the lightning arrester is connected to the output terminal of the reactor or the transformer, the end of the lightning arrester is grounded, and the switch circuit breaker is connected to the head end of the reactor or the transformer.

2. The device for suppressing transformer or reactor operating overvoltage according to claim 1, characterized in that: The discharge ball gap is spherical or rod-shaped.

3. The device for suppressing transformer or reactor operating overvoltage according to claim 2, characterized in that: The capacitor is 0.05-0.5 microfarads.

4. The device for suppressing transformer or reactor operating overvoltage according to claim 3, characterized in that: The lightning arrester is a zinc oxide lightning arrester.

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