SU1376887A1 - Device for compensating reactive liquid - Google Patents

Description

(46) 07.09.91. Bil N 33

(21) 3604331/07

(22) 06/15/83

(71) Research Institute here for the transmission of electricity by high-voltage current

(72) A.A. Albertinsky, V.A. Ivanchenko, N.A.Kanashchenko, A.V.Posev

and M.A. Stepanova

(53) 621.316.728 (088.8)

(56) Valve converters with

improved power factor.

Compensatory ways to improve

power factor of valve converters, M .: Informelectro.

1980

USSR author's certificate, U 448536, cl. H 02 J 3/18, 1971. (54) (57) 1. A REACTIVE POWER COMPENSATION DEVICE, containing a three-phase transformer, the primary circuit of which is connected to the AC network and the secondary winding. with the number of turns Wj is connected to the thyristors, as well as a capacitor battery, which is different in that, in order to reduce the cost, the transformer contains a tertiary winding with

, the number of turns W and the intermediate tap, and all the thyristors are filled in the form of symmetrical thyristors, a triac, and the primary winding is connected according to the triangular circuit, and the secondary and tertiary windings are connected according to the star circuit, between their neutral points the coH is connected to the battery, the phase switches The tertiary windings are connected via triacs to the neutral point of the secondary winding, and each phase output of the secondary winding is connected via two simistors ;; - to the intermediate leads of the other phases of the tertiary winding, and the number of turns auxiliary winding from neutral to intermediate branch w 0,395 Wj, and v;, 0,742W ..

2. A device according to claim 1, characterized in that, in order to expand the control range, the capacitor battery is made in the form of parallel-connected sections, all of which, except for one section, have the smallest capacity, contain contactors in series.

3. The device according to paragraphs. t u2, about tl and - due to the fact that, in order to increase the life of a capacitor battery, in the mode of consumption by the device of reactive power, it is triggered by a contactor.

WITH

oo

ABOUT)

00

1 1376887

The invention relates to electrical engineering and three-phase electrical substations can be used to provide and consume reactive power and to quickly adjust its value to jlnpoBaHHn.

The aim of the invention is to reduce the cost of yr.TpoilCTBa.

ila FIG. Figure 1 shows a schematic diagram of the device; in Figure 2, the times and currents and voltage curves; on fig.Z and 4 - vector diagrams of DPT,

The device includes a three-phase

and the number of turns of the secondary winding 4

W,

(sin

40 °), 742W,

five

JO

With this correlation of the coils at the input of the device, an intermittent current arises, which in its form is such an alternating current, which consumes a three-phase rectifier from the three-phase network.

The operation of the device can be viewed by the time curves of the currents and

switch 1, through which the three-phase. - P and Fig.2 according to

f. I .ch .. O /. PPP ..W ..-, I

current transformer with

connects to the three-phase AC buses, the primary winding 3, connected by a triangle, the secondary winding 4c

neutral output 5 and phase nvu-jQ dump 6A, 6B, 6Cj tertiary winding 7. with neutral output 8, in between M11 taps 9A, 9B, FF and phase-. terminals 10A, 10B, JUS, symmetr1 (1 time, thyristors (triacs) 11-19, capacitor 25 and 21 and contactors 22 and 23 J forming a capacitor battery. As can be seen from the diagram (fig.O The phase terminals 10A, 10B, JC of the tertiary winding 7 are connected to the neutral of the secondary winding 4 through the triacs 11,17,14 rt, and the phase output b of the secondary winding 4 is connected to each of the two terminals 12 and 13, 15 and 16, 18 and 19 two intermediate leads ffl of the tertiary ™ winding 7 belonging to two phases, for example, the phase output 6A of phase A of the secondary winding 4 is connected via two triacs 19 and 12 respectively 9B and intermediate taps 90 phases B and C of the tertiary winding 7. The output Apparatus neutral vtodami between 5 and 8 4 secondary and tertiary windings 7 included kovden-. Sator mozhet.byt 20 and the capacitor 21 is connected.

The voltage and, accordingly, the number of turns Wg of the tertiary winding 7 of the transformer 2 are selected D dependent -. From the specified power of the device and the selected current, according to which fy and first of all, the type of triacs 11-19 required for the device is determined. By the selected number of turns W, the number of turns from the tertiary neutral 7 is found to the intermediate 55

40

45

was m 24-30. In the first approximation, it is assumed that the switching of the current from one triac to another occurs instantly and the value of the current passing through the triac in the conduction gap in one direction remains constant. As shown by experimental studies on the physical model of the device, the current commutation actually happens almost instantly, and the current pulses through the ventilator are slightly different (from the angles of the angles, i.e. they have a small bulge at their tops. Thus, the assumptions During the construction of Fig. 25, only small changes in the actual electromagnetic processes occurring in the device are brought in. Axis 24 (Fig. 2) shows the current of the simulator 11. It flows 20 ° (1/18 of the alternating voltage period at the input devices ) in one positive direction and half of the period also 20 in the opposite (negative) direction. The order of triacs 11-19 in the positive and negative directions and, consequently, the order of their conductivity is determined by the vector diagrams of the EMF windings of the transformer 2j constructed on FIGS. 3 and 4. In the diagram of FIG. 3, the EMF vectors between the neutral output 5 of the secondary winding 4 and the neutral output 8 of the tertiary winding 7 are built according to the diagram (FIG. 1) with the conductivity of odd triacs 11,13,15, 17 and 19 in the positive direction and even synchronizers 12,14,16 and 18 in the negative direction (in Fig. 1 near the triacs 11-19 with arrows of Ict. (Ana positive directions of their conductivity). In the diagram of Fig. 4 also according to the diagram (Fig. 1) EMF vectors are constructed between the neutral terminal 8 of the tertiary obw; –20 °), 395W,

and the number of turns of the secondary winding 4

W,

(sin

40 °), 742W,

With this correlation of the coils at the input of the device, an intermittent current arises, which in its form is such an alternating current, the power consumption - from a three-phase network with a phase rectifier.

The operation of the device can be viewed by the time curves of the currents and

with - P and figure 2 for

 .ch, .. About /. PPP ..W ..-, I

Q 5 rt -

0 5

0

five

was m 24-30. In the first approximation, it is considered that the switching of current from one triac to another occurs instantly and the value of the current passing through the triac in the conduction gap in one direction remains constant. As shown by experimental studies on the physical model of the device, the current switching actually happens almost instantly, and the current pulses through the gates are slightly different (OT from the corner of the corner, i.e. they have a slight bulge at their tops. Thus, the assumptions adopted in the construction of Fig. 25, only small changes in the actual electromagnetic processes occurring in the device are brought in. Axis 24 (Fig. 2) shows the current of the stator 11. It proceeds 20 ° (1/18 of the alternating voltage period at the input of the devices ) in one positive direction and in half a period also 20. in the opposite (negative) direction. The order of triacs 11-19 in the positive and negative directions and, consequently, the order of their conductivity is determined by the vector diagrams of the EMF windings of the transformer 2j 3 and 4. In the diagram of FIG. 3, the EMF vectors between the neutral terminal 5 of the secondary winding 4 and the neutral terminal 8 of the tertiary winding 7 with the conductivity of odd triacs 11, 13, 15, 17 and 19 in the positive direction and even triacs 12,14,16 and 18 in the negative direction (in Fig.1, near the triacs 11-19 arrows ukt. (any pos. - specific directions of their conductivity). The diagram of figure 4 also according to the scheme (figure 1) built the EMF vectors between the neutral terminal 8 of the tertiary level

3.. 1376887

skeins 7 and neutral output 5 of the secondary winding A with the conductivity of even triacs 12,14,16 and 18 in the positive direction and odd triacs 11,13,15,17 and 19 in the negative direction. From vector diagrams, we obtain the following order of unlocking and conduction of triacs 11–19, In the positive direction, triacs of 11–19 are conducted, and then similarly, of triacs 11–19. The current is conducted in a negative direction. This order of conduction of triacs 11-19 is indicated in figure 2 between the curves, built now on axes x 25 and 26,

According to the scheme of FIG. 1, it is easy to trace that in the conduction intervals of the emulator 11 the current passes in the phase A of the tertiary winding 7 of the transformer 2 and through the capacitor 20 (or capacitors 20 and 2.1). In this case, in the interval

(FIG. 2) this current passes in the phase A of the tertiary winding 7, triac 11 and

the capacitor 20 is in the positive direction, and in the interval tgt is in the negative direction. In the moment

fS

20

25

s n n for m x n

gd

and de no mo region of ta ta da on the pattern of mo su on ne 29 i;

t is unlocked and the current is flowing in the forward direction. Triac 12 As a result, the current through the simisto 11 stops and a period of tjt arises, during which the current flows in phase A of the secondary winding A in the positive direction, between terminal 9C and neutral 8 of the tertiary winding 7 and through the capacitor 20 - in the negative direction. Such current commutation occurs every 20. As a result, alternating current IC passes through the capacitor 20 at the output of the device, the curve of which is built on axis 25. As can be seen, this current changes with a ninefold frequency compared to. the frequency of the input voltage of the device. With a frequency of 50 Hz at the input, a frequency of 450 Hz appears at the output of the device. When current i passes on capacitor 20, a voltage appears and, the triangular form of which is shown on axis 25, when forming voltage on triacs 11-19, the voltage the capacitor 20 is added to the voltages of the secondary and tertiary 7 windings of the transformer 2. As a result, the voltages on the triacs 11-19 take on such a form that the triacs 11-19. produce current switching when the device is operating

to

S

0

five

0

five

0

five

0

When the adjustment angle is close to -90, as shown in the physical model of the device, for a reliable switching of current in the mode of reactive power generation, it is necessary that the maximum voltage of the capacitor 20

Uer- 0,5UjH.,

where Uj is the amplitude of the phase voltage of the tertiary winding 7 of transformer 2. On axle xs 26-28, the reduced currents of phase A of the secondary winding 4 and phase A of the tertiary winding 7 are constructed. The reduction is made to the number of turns of the primary winding 3. In the construction, it was assumed that the number of turns of the primary winding 3 is equal to the number of turns of the tertiary winding 7. For which windings in one or another period of time the current flows is easy to find according to the scheme of FIG. 1, since already for each period it is known which of the triacs 11-19 and in which direction the current passes . So for example, in the interval when triac 13 has conductivity in the positive direction, current flows in the tertiary winding 7 from neutral 8 to outlet 9A in the positive direction and in phase C of the secondary flow 4 in the negative direction, the sum of reduced currents constructed. on axis x 26-28, gives the current i} D in phase A of the primary winding 3 (axis 29). On axis 29, in addition, the dotted line shows current i;, P in phase C of primary winding 3, connected by a triangle. Alternating current at the device input in a line conductor of phase A (, д - i (-) is built on axis 30, As you can see, it is its form is the same as the input alternating current of the phase rectifier 18 (with instantaneous commutation of currents and absolutely smoothed rectified current).

When operating the device in the mode of outputting reactive power, the first harmonic of the input current I. is shifted relative to the phase voltage U d of the AC network by the angle i in the direction of advance, Angle v,; is equal to the angle of adjustment c / (triac unlocking angle 11-19) and has a value close to -90 °. In consumption mode

reactive power if, and o (close to +90,.

U: Trustao can work with one 20 nmi codensor with one constant - PS with the included sink detector group (without adjusting the size of the gripped capacity). However, this either results in a narrow area of control of reactive power output, or the conditions of the simmers 11–19 and the co1vdsenatoigigorov deteriorate. capacitor 20 is proportional to., but its current. If the capacitance of the capacitor 20 is chosen so that its pairing is sufficient for over-current switching of the current in the mode 6jifi3KOM

nominal then the device will be able jq

operate at nominal reactive power and at overload: but will not be able to work when current decreases and, therefore, we have a narrow area of control over 25 reactive power. If capacitor capacitance 20 is chosen so that its voltage is sufficient for. given the lower limit of the output of the jet engine; then the device will be able to operate in the entire control range. However, with an increase in the current (reactive power) bydef, the voltage of the capacitor 20 to the voltage across the I-HEM simulators increases. This is equivalent to the deterioration of their working conditions and it will be necessary to select these elements of the device for higher voltages. To avoid these drawbacks, it is recommended that capacitors connected to the output of the device be divided into parallel groups. One of the groups with the smallest capacity must be permanently attached, and in their

thirty

reactive power. The diagram of FIG. 1 shows the simplest case when capacitors are separated and Two groups.

 group 20 is connected directly to the output, and the second group 21 is turned on and off by contactor 22.

The proposed device can operate in the mode of reactive power consumption, having the output capacitors 20 and 21 at the output. However, if for the mode of issuing reactive power, the presence of 20 d 21 carts at the output of the device is necessary, then for the mode of reactive power consumption power is optional. To increase the pecypr.; I coefficients, it is advisable. When operating the device in the mode of consumption of reactive power, when the control angle is close to +90, turn on the contactor 23 (FIG. 1) and thus shunt the capacitors. At the same time, the value of Qi toKa is provided by the voltages of the secondary And it tertiary 7 windings of the transformer 2 ..

The advantage of a npeMJraraaMoro device is the high effect of using capacitors, ti is a good, near-sinusoidal form of input AC current. The increase in ef (1) of projectivity7 and the use of condators is determined by the fact that they operate at nine times the frequency of the external frequency with a three-phase input voltage. In the proposed device, capacitors are used more efficiently on the watch circuits of other groups, contactors are introduced, which

ry connect or disconnect as

increase or decrease issued

- Goth, 450 Hz and the cost of them is much lower. Not only non symmetric thyristors (thyristors), but also thyristors can be used as gates. In this case, instead of one simistor, it is necessary to use two thyristors connected in opposite directions.

 ,

Q

5 5

0

reactive power. The diagram of figure 1 shows the simplest case when the capacitors are separated and Two groups.

 group 20 is connected directly to the output, and the second group 21 is turned on and off by contactor 22.

The proposed device can operate in the mode of reactive power consumption, having the output capacitors 20 and 21 at the exit. power is optional. To increase the pecypr.; I coefficients, it is advisable. When operating the device in the mode of consumption of reactive power, when the control angle is close to +90, turn on the contactor 23 (FIG. 1) and thus shunt the capacitors. At the same time, the value of Qi toKa is provided by the voltages of the secondary And it tertiary 7 windings of the transformer 2 ..

The advantage of a npeMJraraaMoro device is the high effect of using capacitors, ti is a good, near-sinusoidal form of input AC current. The increase in ef (1) of projectivity7 and the use of condators is determined by the fact that they operate at nine times the frequency of the external frequency with a three-phase input voltage. In the proposed device, capacitors are used more efficiently per hour, 450 Hz, and their costs are much lower. Not only non symmetric thyristors (thyristors), but also thyristors can be used as gates. In this case, instead of one simistor, it is necessary to use two thyristors connected in opposite directions.

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Claims (3)

1. REACTIVE POWER COMPENSATION DEVICE, comprising a three-phase transformer, the primary winding of which is connected to an alternating current main, and the secondary winding. with the number of turns W, connected to the thyristors, as well as a capacitor bank, characterized in that, in order to reduce the cost, the transformer contains a tertiary winding with a number of turns and an intermediate tap, and all thyristors are made in the form of symmetric thyristors-simistor, and the primary the winding is connected in a triangle pattern, and the secondary and tertiary windings are connected in a star pattern, a capacitor bank is connected between their neutral points, the phase outputs of the tertiary winding are connected again through triacs to the neutral point winding, and each phase terminal of the secondary winding is connected via two intermediate taps to the triac other phase tertiary winding, wherein the number of turns of the tertiary winding-up of the neutral intermediate tap 1 ^ = 0,3951 ^, a W, = 0,742 « '. ³ 2. The device according to claim 1, characterized in that, in order to expand the control range, the capacitor bank is made in the form of parallel-connected sections, and all sections, except one, the smallest capacity of which contain contactors in series. 3. The device according to paragraphs. 1 and 2, characterized in that, in order to increase the resource of the capacitor bank, it is in the mode of consumption of reactive power by the device. It is connected by a contactor. SU.,., 1376887 A1