DE407195C - Mercury rectifier system with a device for eliminating currents of higher harmonics from the alternating current network - Google Patents

Description

GERMAN EMPIRE

ISSUED
ON DECEMBER 18, 1924

REICH PATENT OFFICE

PATENT LETTERING

- JVi 407195 - CLASS 21 d GROUP

(S 54826 VIUpZtP)

Societe Anonyme Appareillage et Applications Electriques in Liège.

Mercury rectifier system with a device for eliminating the currents higher harmonics from the AC network.

Patented in the German Empire on November 23, 1920.

In the case of mercury rectifiers which supply an essentially constant direct current, A composite current flows on the alternating current side, partly through the Mains supplied sinusoidal current and on the other hand by the higher harmonic Disturbance waves is formed.

So if a mercury rectifier system is branched off from an alternating current network is, this is except for a sinusoidal

The base current still has a fault current from the rectifiers flowing through it, which causes harmful interference in the network equipment.

The invention relates to an arrangement which makes it possible to avoid this inconvenience. For this purpose it provides a device which acts in such a way that the rectifiers are combined Can absorb current, ίο without the disturbance current flowing in the network, in which rather the sinusoidal stem circles alone.

To achieve this, the interference current going through the mercury rectifiers closes according to the invention via a shunt in which a machine is provided which an idling synchronous or asynchronous motor can be and that at any moment a voltage equal to the voltage of the network, but in the opposite direction, is generated, so that the Basic current cannot flow through this shunt.

So that this short circuit is as effective as possible for the disturbance current it is important that the resistance and self-induction of the shunt for the disturbance currents is as weak as possible.

Therefore, the invention also provides devices through which one practically Self-induction and zero resistance can be obtained for this disturbance current. Devices by which one can remove the resistance are known. In the following Embodiments of the invention described are devices for cancellation indicated by self-induction.

In the drawing are some exemplary embodiments of mercury rectifier systems shown schematically according to the invention, namely shows:

Fig. Ι a scheme of a rectifier system for single-phase electricity,

Fig. 2 shows the same scheme with some additional parts,

Fig. 3 a second scheme of a rectifier system for single-phase electricity,

Fig. 4 is a schematic of a rectifier system for three-phase electricity.

Figs. 1 and 2 relate in particular to rectifier systems with a single-phase Alternating current relatively low voltage.

The anodes A ₁ and A _{2 of} the rectifier 1

and 2 are directly connected to lines L ₁ and L ₂ . The cathodes K ₁ and Ji ₂ are connected to one another by a conductor which is connected at point K to the positive terminal K ^{1 of} the direct current circuit. The wires leading to the anodes are connected to one another in a known manner by an induction coil CBD , the center point B > of which is connected to the negative terminal B ^{1 of} the direct current circuit.

In the scheme shown in Fig. 1, a self-induction coil hg is switched on in one of the wires leading to the anodes.

According to the invention, a shunt rh is provided in parallel to the rectifiers 1 and 2, in which a machine m is located, which can be an idle synchronous or asynchronous motor.

This motor, which rotates at a synchronous or almost synchronous speed, generates a voltage that is always the same and in the opposite direction to the voltage of the mains base current. This current can therefore not go through the shunt rh . ■

However, this is different for the disturbance current. This is formed by higher harmonics, the frequency of which is significantly different from that of the base current, so that the motor for these disturbance currents cannot be regarded as running synchronously.

The motor therefore only sets a very weak impedance for this interference current, so that this current is short-circuited across said shunt.

As a result, the entire fault current of the rectifier can close across rh without affecting the mains current.

In the scheme shown in Fig. 2, the winding of the self-induction hg in Fig. 1 is replaced by a self-induction with a collector ef . This arrangement allows, when the rotor has been given a suitable speed of self-induction, that no impedance is created for the base current, while a considerable impedance is obtained for the disturbance current.

The self-induction rotor with collector ef can be mechanically coupled to the rotor of the machine m in such a way that it rotates at the same speed as the latter. It should be noted that in the scheme of Fig. 1 the impedance opposed by the shunt rh is not completely equal to zero. This circuit actually has some resistance and some self-induction. no

In order to completely short-circuit the fault current, this impedance must be canceled. The resistance can be removed by known means. To the self-induction dem The following procedure can be used to cancel out disturbance extremes.

A self-induction winding lh is connected into the circuit rh and is provided on the same magnetic core as the self-induction winding of the self-induction with collector ef . These two windings are arranged in such a way that the mutual induction

coefficient of the second equal to the first and is opposite to the self-induction coefficient of the shunt, d. H. to the Self-induction coefficient to be canceled.

In order to bring the winding lh on the same core as the winding of the self-induction with collector, one can provide the said winding lh \ on the stator of the self-induction with a collector. I.

Figs. 3 and 4 relate to networks that are operated with high voltage. Here ■ is a transformer T between the line and | the rectifier switched.

In Fig. 3, which relates to a network with single-phase current, the point B connected to the negative terminal B ^{1 of} the direct current circuit is the center point of the secondary winding CD of the transformer T. The cathodes K ₁ and Ji ₂ are with the positive terminal in the same way as in Figs. 1 and 2. The shunt rh, into which the synchronous or asynchronous motor is switched on, starts from two points which lie on two windings P ₁ and ₂ connected to the anodes A ₁ and A _{2 of} the rectifiers 1 and 2. j The windings P ₁ and p ₂ form a double

Primary winding of a transformer P, the secondary winding q of which feeds the self-induction with collector ef , the rotor of which is keyed on the axis of the machine m.

The use of a double primary winding in transformer P is justified by the need to keep point B exactly neutral to anodes A ₁ and A _%.

In Fig. 4, which relates to a three-phase network, three single-phase rectifiers 1, 2 and 3 are used, the cathodes of which are connected to the positive terminal K ^{1 of} the direct current circuit. The negative terminal B ^{1 of} this latter is connected to the neutral point B of the star-connected secondary direction of a transformer, the primary winding of which is connected in delta and connected to the lines L ₁ , L ₂ and L ₃ .

The shunt r, s, h, the three-phase

includes idling motor m , is branched off from points selected on windings P ₁ , p ₂ , p ₃ , which are connected to the anodes A _1, A ₂ and A _{3 of} the rectifiers 1, 2 and 3.

These windings form the primary windings of a transformer P, whose secondary windings q _x , q ₂ , q ₃ feed the three-phase self-induction with collector ef.

It can be seen that in the examples in Figs. 2 to 4, on the one hand, a shunted machine m is present, which opposes the passage of the basic currents and short-circuits the interference currents, and, on the other hand, a self-induction with a collector is connected in series, which is as little as possible counteracts the passage of the basic currents and largely reduces the interference currents.

The combination of these parts completely prevents any disturbances from occurring in the network L ₁ , L ₂ or L ₁ , L ₂ , L _{: i} .

Claims (3)

Patent Claims: 1. Mercury rectifier system with a device for elimination of the currents of higher harmonics of the ac network, characterized in that an idler synchronous or asynchronous ^ ·) is connected in shunt to the rectifier and at any moment one of the voltage of the rectifier supplying alternating current network (L ₁ , L ₂ or L ₁ , L ₂ , L ₃ ) generated oppositely the same voltage, so that it is not traversed by the basic current of the network, but due to its shunt circuit for short-circuiting the . Interference currents of higher harmonics stored above the base current are used. 2. Installation according to claim 1, characterized in that on the axis of the synchronous or asynchronous machine of the shunt, the rotor of a self-induction {ef ) is wedged with a collector, which is in one of the composite current or one through this in the secondary winding of a transformer ( P) induced current flowing through the conductor is switched on, and which forms a self-induction equal to zero for the basic current, but a significant self-induction for the interference current. 3. System according to claim 2, characterized in that to eliminate the self-induction of the shunt circuit against the fault current flowing through it in this circuit a self-induction winding [U) is switched on, which sits on the same core as the winding of the self-induction with the collector. 1 sheet of drawings. Berlin, printed in the reichsdruckerbl