SU1037377A2 - Apparatus for symmetrization of three-phase networks - Google Patents

Abstract

DEVICE FOR SYMMETRICATION OF THREE-PHASE NETWORKS on aut.sov. 974499, characterized in that, in order to improve the accuracy of balancing four-wire 1 rephase networks, a second group of tpex phase-sensitive rectifiers and is additionally introduced into it. Ratios of two voltages, as well as of three operational units with linear amplifiers at the input, the first inputs of the additional phase-sensitive rectifiers connected to the phase voltages of the network, and the second inputs connected in series with a certain phase of the load, additional meters of the ratio of two voltages the first inputs are connected to the measuring device of the current value of the voltage, and the second inputs are connected to the corresponding output of additional phase-sensitive rectifiers, each of ration blocks connected to inputs of two inputs of a corresponding difference and three other blocks inputs - outputs to three additional gauges ratio of two voltages, and outputs a second linear amplifiers are connected to three groups; additional inputs of the executive circuit that are made six-element to compensate for currents of both reverse and zero sequences.

Description

co 4 The invention relates to electrical equipment and can be used to automatically balance the currents of a four-wire network when an unbalanced three-phase load is connected to it with time-varying parameters. I According to the main auth. No. 974499. A device for balancing three-phase networks is known, which contains three phase-sensitive rectifiers, an effective value sensor, voltage, three meters of the ratio of two voltages, three difference blocks and three linear amplifiers connected to an executive device compensating negative sequence currents, where the first inputs of the two voltage ratio meters are interconnected and connected to the current voltage sensor, and the second inputs are connected to the outputs of the corresponding phases of the corresponding rectifiers, the first input of one of which and the input of the sensor of the effective voltage value are interconnected: and connected to one of the network voltages, the inputs of the difference blocks are connected in pairs to the outputs of the corresponding meters of the ratio of two voltages The inputs of the two other phase-sensitive rectifiers are connected to the other two phase voltages with the inputs of the linear amplifiers, and the second inputs of each phase-sensitive rectifier are connected in series with divided phase HEAT Cl3 ki. . However, the known device provides compensation only for negative sequence currents. At the same time, in four-wire three-phase networks, as a rule, there are zero-sequence currents. In this case, the device has methodical errors introduced by the currents of the zero sequence /, which leads to a decrease in the accuracy of symmetrization. . The purpose of the invention is to improve the accuracy of balancing four-wire three-phase networks. About D To achieve this goal, the eiTBO device additionally introduced a second group of three phase-sensitive rectifiers and two voltage ratio meters, as well as three operating blocks with linear output amplifiers, the first inputs of the Additional phase-sensitive rectifiers connected to the phase voltages network, and the second inputs are connected in series with a certain phase of the load, additional meters of the ratio of two voltages are connected to the first inputs to the meter of the effective voltage value, and These inputs are connected to the corresponding outputs of additional phase-sensitive rectifiers, each of the operational units is connected to two inputs to the inputs of the corresponding {(mutual difference blocks and three other inputs to the outputs of all Three meters of the ratio of two voltages of the second group, and the outputs of the linear amplifiers of the second group are connected to - three additional inputs of the executive body, which is made six-element to compensate for the TQKOB of both reverse and zero sequence. The drawing shows a block diagram of the proposed device. The device contains a three-phase power supply 1, a three-phase alternating load 2. The device also includes phase-sensitive rectifiers 3, a sensor 4 of the effective voltage, two meters of the ratio of two voltages, blocks b of differences, operational blocks 7, linear amplifiers 8 and executive body 9. Executive body 9 is made of six elements, three of which are included in the triangle, and three - in a star. Thus, at certain values of the parameters of these elements, the currents of both the reverse and zero sequences are compensated. Reactive conductivities are each. go of the six elements are regulated independently of others, and they are made in such a way that they can be both inductive and capacitive in nature. Each of the phase-sensitive rectifiers 3 is connected to one of the phases of the three-phase circuit, both in voltage and current. A voltage sensor 4 is connected to one of the phase voltages. The first inputs of meters 5, the ratios of the two voltages are interconnected and connected to the output of the sensor 4, and the second input of each of the meters 5 is connected to the output of one of the phase-sensitive rectifiers 3. The outputs of the meters 5 of the ratios of the double voltages and operational units 7, the outputs of which through linear amplifiers 8 are connected to the actuator 9. for the general case of a four-wire three-phase network, the phase currents of which contain the components of the direct, reverse pocledovate.pnoc zero minute, hold sleduk que ratios; “Id4A1 4o 1,) 1igG () o4 (, where. 1d, IB, 1s are the complex currents of phase currents; -., K, iV are the complexes of forward, reverse, and zero consecutive .4 (.. completeness, phase multiplier. The elements of the executive body 9 (balancing device) are chosen purely reactive, with the conductivities .- .A ".A.Av-.with. The elements Od, Yg, Chc are connected to phase voltages, the elements Odg, YBC IcA And linear. The selected symmetric part of the parameters - three congestion, we get, UIS - ULS - LSA; L (Afti 6C VS “) symkutrichnye parts of the parameters of the executive body 9, .. A, yChd, LCH..LCH; d asymmetric or reg parts of the parameters of the executive opracia, and; jAy; | ((LHde ,. For currents. Direct, inverse, and zero sequences of the executive organ 9, with a symmetrical system of voltages, the following expressions are valid), -Uy; -Wow;) , Jtor J where vf-phase voltage. &Amp; fi (AChd + a-lhcts Lx, ...); 1. AH. 4 C lt () (.o1cUc; St); Conditions for compensating for currents of zero and inverse sequences have view . , By)) 1.,) - i. in the compensation equation. (10) LU, LU / L – Vg values are included depending on six parameters: AY, Ue US Udb - Since these six parameters are connected by two CONDITIONS (3), then the number. There are four unavailable parameters. On the other hand, the two complex equations (10) are equivalent to four real equations, from which all six parameters can be determined taking into account two additional conditions (3). The solution of the system of equations (10) with regard to conditions (3) is simplified if it is carried out in a symmetric form. By performing the operation of complex conjugation in equations (10) and using conditions (3), we obtain a symmetric set of equations (.: CH); Cho --- i () - 0; ; -4 иУвс «СА л в) - |, WVi 4 1 иУе, с Ав) - | (r y) (.) The solution of the system of equations (11) --DW Dul v.)) w «i. Ay. Ir cirHo i IV E ". (A i (, l, -d1 (5) i Abi 4ir t 4oj) Substituting relations (1) into these curves, we obtain the parameters of the executive rynna 9 through triple currents | d, l, c and phase shifts fA, FV, fc of these currents with respect to the corresponding phase voltages m. Final year 4 4 ° C09%. T 71 V JL. 4 jccoejpc. g 6SiVifa k infc, V T V .Т VW -, tcCOS4c, -t lASln4 AJ, UCOStf. V3NтГ5 V.. U - kiir. JL iAiin with & V% V

i a so h in

2 1 SBM J.. , -Uz V, g-P V

1 1SSOTUD J2.

d sliTf V S-UZ V JACOg. 1 ta.

iib

6A

rtG N I5 V. (13) Expressions 4137 form the basis of the operation of the device. . .

For every two phase-sensitive rectifier 3, phase voltages and a current from one of the phase mains are supplied. At the outputs of phase-sensitive rectifiers 3, constant voltages are formed, proportional to, respectively, the values of Sin f0,

 c: ChC ° A & ° c os Pci

These voltages are fed to the first inputs of the meters 5 ratios of the two voltages, the second inputs of which are supplied with a constant voltage from the transmitter 4 of the current voltage value. The output voltages of the meters 5 are proportional to the ratios. . ) ;, 1e. V v n

. GbS05Uv V

The voltages from the outputs of the generators 5 are supplied to the inputs of the difference blocks and the operational blocks 7 in accordance with expressions (13) as follows. The voltage difference blocks δ are supplied in pairs with the same transmission coefficient for determining the values of | b, σ, σ and dfd. Operating units 7 have five inputs, three of which from three meters, 5 are supplied

proportional

.

))

 J

and

and V V

the other inputs are two components with the same meters 5 as for blocks of 6 differences. The characters and transmission coefficients of the operational blocks 7 for each of the components are determined by the first three equalizing systems (13).

At the outputs of the difference blocks b and the operational blocks 7, voltages are formed, which are proportional to the asymmetrical part of the parameters of the actuator 9 according to expressions (13). The sign of these voltages determines the character of the increment — inductive or capacitive. The voltages from the outputs of the difference blocks and the operational blocks 7 are amplified by linear amplifiers 8 and fed to the executive unit 9, in which a corresponding restructuring of the parameters of the reactive elements is made in accordance with expressions (13), valid for any three-phase network and four-wire, with time-varying load.

Thus, the proposed device, as compared to the well-known one, does indeed provide a higher accuracy in balancing four-wire three-phase networks, since the OIO makes it possible to compensate for the currents of not only reverse, but also zero sequence. This greatly expands the field of application of such a device in industrial and autonomous power supply systems. This is the technical and economic effect of the invention.

Claims (1)

DEVICE FOR SYMMETRATION OF THREE-PHASE NETWORKS according to ed. No. 974499, characterized in that, in order to improve the accuracy of balancing of four-wire Three-phase networks, the second group of Three phase-sensitive rectifiers and is additionally introduced into it. measuring the ratio of two voltages, as well as from three operating units with linear amplifiers at the input, the first inputs of additional phaosensitive rectifiers connected to the phase voltage of the network, and the second inputs connected in series with a certain phase of the load, additional measuring instruments of the ratio of two voltages with the first inputs connected to measuring the actual voltage value, and the second inputs are connected to the corresponding outputs of additional phase-sensitive rectifiers, each of the operational x blocks are connected by two inputs to the inputs of the corresponding difference blocks and three other inputs - to the outputs of three additional meters of the ratio of the two voltages, and the outputs of the linear amplifiers of the second group are connected to three § additional inputs of the executive body / which is made of six elements to compensate for currents both reverse and zero sequences