SU1644291A1 - Arc control device to compensate single phase-grounded capacitance current - Google Patents

Abstract

The invention relates to electrical engineering and power engineering, in particular, to designs of arc-suppressing reactors, designed to automatically compensate for the capacitive current of a single-phase earth fault in electric networks 6-35 kV. The purpose of the invention is to simplify the design of its manufacturing technology and reduce the volume of electrical steel. The arc-suppressing device for automatic compensation of the capacitive current of a single-phase earth fault contains a magnetic core, a primary working 1, a secondary 2 windings and a winding 3 bias. New in the proposed device is the use of the simplest two-core magnetic core without non-magnetic gaps with the placement of the working and secondary windings on different rods, and the bias winding consisting of two halves connected between each other in counter-parallel is located on the upper and lower frames. The bias windings are powered by a direct current source. The secondary winding is secondary short-circuited. In the proposed device, the inductive compensation current is generated mainly due to the reaction of the primary working winding to the short-circuited secondary winding current. Due to the demagnetizing effect of the secondary winding, the magnetic core in operation has reduced induction. This circumstance makes it possible to reduce the cross section of the magnetic circuit by a factor of 1.5–2, which means that the consumption of electrical steel for its manufacture. The mass of the arc suppressor is reduced. The operating winding current is sinusoidal, and in phase it lags behind the neutral bias voltage by close to 90 ° C. regardless of the bias current. By varying the bias current, the current compensation current of the winding is adjusted. The use of automatic devices for this purpose will, depending on the state of the network at the moment of phase-to-ground closure, maintain a resonant compensation mode in the network. 2 Il. (L o and y

Description

The invention relates to electrical engineering and power engineering, in particular, to devices for automatic compensation of capacitive current of a single-phase earth fault.

The purpose of the invention is to simplify the design and technology of its manufacture and reduce the volume of electrical steel.

Fig. 1 is a diagram of a device for compensating for capacitive single-phase earth-fault current in networks with insulated neutral; Figure 2 is a device replacement circuit.

The design is a two-core magnetic core without gaps. On

The first core houses the working winding 1, and on the second core there is a short whip secondary winding 2. Two halves of the control winding 3 are located on the top and bottom of the magnetic core. They are connected in a counter-parallel pattern.

The device works as follows.

When the phase is shorted to earth, a bias voltage U0 appears, under the action of which a current flows to the working winding 1. In the winding 2 a current is generated. Due to the counter-parallel inclusion of control windings, the resulting variable rou in them is zero. Such inclusion of the control windings does not affect the resulting short-circuit inductance of the primary and secondary windings in the absence of current in the control winding. Due to the presence of a short-circuited secondary winding in the primary winding, a certain amount of current arises, the value of which is determined by the parameters of the secondary winding and the section of the steel of the magnetic circuit. The operating current of the winding is determined by the sum of the bias current and the secondary current brought to the primary winding to lo + h. This current is closed through the fault site to compensate for the capacitive current of the single-phase earth fault. The inductance of the short circuit L «o -. and 1 + a2. due to the placement of the secondary winding on another rod, has the desired value. When a driver is applied to the control winding of the magnetisation current, the state of the core and its conductivity change. This is equivalent to the appearance of a shunt circuit (Fig. 2). As a result, the total resistance of the device decreases, and the current in the working winding increases. The control range of the total inductance, and hence the current k, can reach

two or more values. The limit of the multiplicity of regulation is the saturation of the magnetic core and the appearance in the current of the working winding of higher harmonics.

In connection with the demagnetizing effect of the secondary winding, the operating point on the current-voltage characteristic of the arc-suppressing reactor is located on its initial straight line section, which predetermines the sinusoidal curve of the inductive

reactor current. As the magnetization current increases, the operating point approaches the saturation region. In this case, harmonic components may appear in the compensation current, which can be avoided by increasing the cross section of the magnetic circuit taking into account the requirements of the multiplicity of regulation.

Claims (1)

Invention Formula Arc-suppressing device for compensation of capacitive single-phase ground fault current, containing magnetic core, primary winding, intended for connection between network neutral and ground, secondary and regulating windings, characterized in that, in order to simplify the design and technology of its manufacture, to reduce the volume of electrical steel , the magnetic circuit is made two-core, the primary winding is placed on one rod, the secondary winding is short-circuited and placed on the other rod, the regulating winding is made of two windings connected in an opposite-parallel circuit and placed on the magnetic core. 2