RU179611U1 - SYMMETRING DEVICE FOR A THREE PHASE NETWORK WITH A NEUTRAL WIRE - Google Patents

Abstract

The utility model relates to the field of electrical engineering and can be used to improve the quality and reduce losses of electric energy in three-phase networks with a zero wire, containing asymmetric and nonlinear loads, and allows you to steadily discrete adjust the parameters of capacitive elements together with the inductance. The purpose of the utility model is to improve the quality and reduction of electric energy losses in electric networks caused by the asymmetry of currents and voltages. A balancing device for a three-phase network and with a neutral wire containing parallel connected power steps in each phase, including capacitive elements connected to a star, a reactor connected between the neutral wire and the zero point of the capacitors, an automatic control system, characterized in that the reactor has working conclusions according to the number of stages power, and each working terminal of the reactor is connected to the neutral wire of the supply network through series-connected closing contact of the corresponding stage and opening contact the next step.

Description

The utility model relates to the field of electrical engineering and can be used to improve the quality and reduce losses of electric energy in three-phase networks with a neutral wire containing asymmetric and nonlinear loads, and allows you to stably discrete adjust the parameters of capacitive elements together with the regulation of inductance.

A device for compensating reactive power in multiphase distribution networks with a zero wire (a.s. No. 458919 H02J 3/18) [1], containing capacitors connected in a star, between the common point of the capacitors and the neutral wire, an inductive element is included.

The disadvantage of this device is:

1. The inability to adjust its parameters when changing network settings.

A device for balancing currents and voltages in a three-phase network with a zero wire and a self-regulating inductance (PM RF No. 26699 H02J 3/26) [2], containing capacitive elements connected to a star, and an inductance made self-regulating, and containing a cylindrical coil, steel the core of electrical steel, a coil spring, the base of the device.

The disadvantages of this device are:

1. The inability to adjust the parameters of capacitive elements when changing the magnitude of the asymmetry in a three-phase network.

2. The impossibility of stable regulation of inductance due to core oscillations when the current in the coil changes.

Known filtering device for a three-phase network with zero wire to reduce losses and improve the quality of electricity (PM RF No. 110876 H02J 3/26) [3].

The disadvantage of this device is:

1. One of the elements of the device is a magnetic amplifier, which is a nonlinear element, the operation of which introduces a significant distortion into the shape of the current curve.

Closest to the proposed device is a well-known balancing device for a three-phase four-wire network with adjustable parameters (PM RF No. 61063 H02J 3/26) [4].

The disadvantages of this device are:

1. Significant energy consumption and the fragility of the magnetic starter coil and its contacts, and as a result, a decrease in the reliability of the device itself.

The purpose of the utility model is to improve the quality and reduce losses of electric energy in electric networks, due to the asymmetry of currents and voltages.

This goal is achieved due to the fact that the balancing device for a three-phase network with a neutral wire contains in each phase parallel connected power steps, including capacitive elements connected to a star, a reactor connected between the neutral wire and the zero point of the capacitors, an automatic control system, characterized in that the reactor has working conclusions according to the number of power steps, and each working conclusion of the reactor is connected to the neutral wire of the supply network through atelno included isolated contact the respective stage and a subsequent stage circuit-opening contact. In fig. 1 shows a diagram of a utility model.

A balancing device for a three-phase network with a neutral wire consists of capacitive elements (1-3) connected to a star, reactors (4-6), make contacts (7-10, 12, 14), disconnect contacts (11, 13) and a control unit device (15). At the first power stage, three tanks (1) and reactors (4-6) are connected. With an increase in the asymmetry of currents and voltages, the second power stage is connected, and the power of the device increases. This is achieved by connecting additional tanks (2) and reactors (4, 5). The reactor 6 is turned off and the overall inductance of the reactor is reduced. The proposed device is completely disconnected from the network upon reaching the level of phase voltages regulated by GOST [5].

To automatically control the device, it is proposed to use a control unit that controls the device in the function of phase voltage unbalance. The control circuit operates as follows.

The control circuit (Fig. 2) consists of differential discriminators, OR gates, and RS triggers. Differential discriminators DD1, DD2 and DD3, built on the 2ILI-NOT circuit, produce a logical unit at the output when the input voltage from voltage transformers (22-24) is between two thresholds and is logical zero in all other cases. If the phase voltage levels are 220 V (± 5%), then at the outputs DD1 – DD3 we get logical zeros. In this case, a logical zero comes to the inputs of the OR logic elements (16-18). From the outputs of the logic elements, zero is supplied to the RS-triggers (19-21). The device does not turn on.

If the deviation values of one or two (three) phase voltages are more than -5% of the values regulated by GOST [5], then the logic unit is sent to the RS-trigger (19) and contacts 7 and 10 are closed, while contact 11 is closed . The device turns on at minimum power.

With an increase in the phase-voltage asymmetry level to the values determined by DD2, the second stage of the device is switched on. To enable the second stage, the logic unit is supplied to the RS-trigger (20), and contacts 8 and 12 are closed and contact 11 is opened. When the phase voltage asymmetry level increases to the values determined by DD3, the third stage of the device is turned on. To enable the third stage, a logical unit is supplied to the RS-trigger (21), while the contacts 9 and 14 are closed and the contact 13 is opened.

The device stage is switched off as follows: if a logic zero is generated at the outputs DD1-DD3, then through an inverting element zero is converted to unity and fed to the R-input of the RS trigger, so a logical zero is formed at its output and the device stage is disabled.

The advantage of this device is that the device is controlled from the level of asymmetry of currents and voltages in the 0.38 kV network, which takes place at a given time.

The economic effect of the introduction of the proposed utility model is expressed in improving the quality and reducing losses of electric energy due to the asymmetry of currents and voltages.

Information sources

1. A.S. No. 458919 (USSR). Device for reactive power compensation in multiphase distribution networks with zero wire / A.K. Shidlovsky, V.G. Kuznetsov, N.N. Kaplichny, etc. Publ. in B.I., 1975, No. 4.

2. PM of the Russian Federation No. 26699. Device for balancing currents and voltages in a three-phase network with a zero wire and self-regulating inductance / G.V. Lukina, I.V. Naumov, A.A. Lukin, S.V. Sukiasov S.V. Scribe. Publ. 12/10/2002 Bull. Number 34.

3. ПМ №РФ №110876. Filter-balancing device for a three-phase network with a zero wire / F.D. Kosoukhov, A.O. Gorbunov, V.A. Romanov, M.Yu. Teremetsky. Publ. 11/27/2011 Bull. No. 33.

4. PM of the Russian Federation No. 61063 H02J 3/26. Balancing device for a three-phase four-wire network with adjustable parameters / D.A. Ivanov, I.V. Naumov, D.A. Shpak, A.A. Matveenko, S.V. Podyachikh, S.V. Sukiasov. Publ. 02/10/2007 Bull. Number 4.

5. GOST 32144-2013. Electric Energy. Electromagnetic compatibility of technical equipment. Quality standards for electric energy in general-purpose power supply systems [Text]: - Introduction. 2014-07-01 - M .: Standartinform, 2014 - 19 p.

Claims (1)

A balancing device for a three-phase network with a neutral wire, containing parallel connected power steps in each phase, including capacitive elements connected to a star, a reactor connected between the neutral wire and the zero point of the capacitors, an automatic control system, characterized in that the reactor has working conclusions on the number of power steps, and each working output of the reactor is connected to the neutral wire of the supply network through the serially connected closing contact corresponding stage and opening contact of the subsequent stage.

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