Balancer for three-phase networks with neutral wire
SUBSTANCE: balancer is purposed to improve quality of current and voltage balancing in three-phase networks with neutral wire due to self-adjustment of power in case of current change in the neutral wire. The device contains additionally two power stages and automatic control circuit operating as current function of the neutral wire.
EFFECT: improving quality of adjustment due to detuning parameters of the suggested device from current unbalance in the network of 0,38 kV present at the moment.
The invention relates to electrical engineering and can be used for self-balancing currents and voltages in three-phase networks with zero wire when connected to the unbalanced load.
It is known device  electromagnetic type, the windings of which are connected according to the scheme counter zigzag.
The disadvantage of this device is the use of complex schemes to control the device.
The closest technical solution, selected as a prototype, is filtersysteme device for three-phase networks with zero wire containing a three-phase electromagnetic device having a three phase output and one neutral, each phase output is intended for connection to the phase wires of the network, and the neutral - zero-wire .
The disadvantage of this device is the constancy of its parameters, which does not allow to regulate the power of the device when changing the unbalance currents in an electrical network.
The objective of the invention is to improve the quality of balancing the currents and voltages in three-phase networks with zero wire through self-regulation capacity of the device when changing the current in the ground wire.
The invention consists in the following. Winding each of the electromagnetic apparatus is of the ATA is connected according to the scheme counter zigzag and have three phase and one neutral conclusions. Each phase output is intended for connection to the phase wire network, and a neutral output to a zero wire. Each electromagnetic device forms one stage of power. Each stage power turns on when the circuit power contacts of the respective magnetic starter, the coil of which is driven by a scheme of automatic control, working in the function current bullet wire and includes a current transformer. established in bullet wire electrical network and two current relay and one time relays on each output step. The result is improved quality of balancing the currents and voltages in three-phase networks with zero wire.
Figures 1 and 2 show symmetrise device for three-phase networks with zero wire.
Figure 1 shows the diagram of the device, figure 2 - scheme of automatic control of the balancing device.
In the proposed device has three levels of power.
Symmetrise device for three-phase networks with zero wire consists of three three-phase electromagnetic machines, windings are connected according to the scheme counter zigzag with three phase output and one neutral, each phase output is intended for connection to the phase wires of the network, and the neutral to the ground wire. Each three-phase electromagnetic apparatus forms one stage of power balancing device. At the first stage power connected first three-phase electromagnetic apparatus. With increasing unbalance of currents and voltages in the power of the device increases. This is achieved by connecting an additional one or two three-phase electromagnetic devices to the electrical network. The proposed device is completely disconnected from the network while achieving current in the ground wire is the minimum value corresponding allowable unbalance currents and voltages specified by GOST 13109-97.
For automatic control of the balancing device are encouraged to use the scheme, which regulates the function of the current bullet wire (figure 2). The circuit includes a current transformer TL, six current relay KA1-CA, three time relay KT1-CT and three magnetic contactor KM1-KM3. Elements SA1, CA, KT1 KM1 and are designed to control the first output step of balancing device; CA, CA, CT KM2 and to control the second stage of the power balancing device; CA, CA, CT and KM3 for the management of the third stage of the power balancing device.
The principle of operation of the device let us consider the following example of setting values of the current relay KA1 - 1A, CA - 2A, CA, CA - 4A, CA - 5A, CA - 6A.
With increasing current in the ground wire in the secondary circuit of the current transformer TA to 1F closes normally open contact relay KA1, with a further increase of the current up to 2A - work (closes) normally open contact relay CA will receive power relay coil time KT1, with time delay closes normally open contact relay KT1 is powered on and the coil of the magnetic contactor KM1. After that, a magnetic starter closes his power contacts KM1 (figure 1) and includes a first output step of balancing devices. Disconnect from the network the first step of capacity balancing will occur after the device of the current reduction to the value of 1A. Thus closing contact KA1 comes in its original position (opened) and the coil of the time relay KT1 loses power. contact KT1 opens with a time delay, the coil of the magnetic contactor KM1 loses power and power contacts of the contactor KM1 open (figure 1). When this occurs, disable the first stage symmetrised device from the network. By reducing the current to 2A shutdown will not occur, since the normally open contact relay KA blocks auxiliary contact of the magnetic contactor KM1.
Work (connecting and disconnecting to the network) the second and third stages of power balancing device is similar: connecting the second STU is Yeni power occurs when the current relay KA, equal to 4A, and off - by reducing the current to 3A, i.e. by reducing the current below setpoint current relay KA.
The third step of balancing device is connected with increasing current up to 6A, and the network disconnection occurs when the current is reduced to below the value of 5A.
The time delay when connecting or disconnecting the speed of the power balancing device is performed using the three time relay KT1, KT and KT to prevent actuation of the speed of the device at short-term load fluctuations.
A current transformer THAT is installed in the neutral wire of the electrical network 0,38 kV and is designed to connect current relay TA1-TA.
Thus, the capacity of the self-adjusting device as a function of current neutral conductor and the parameters of the proposed device rebuilt from the level of unbalance of the currents in the network 0,38 kV, taking place in a given time.
SOURCES of INFORMATION
1. As the USSR №1206881, 23.09.83.
2. As the USSR №1206881, 23.09.83 prototype.
Symmetrise device for three-phase networks with zero wire containing three-phase electromagnetic apparatus, characterized in that the winding of each of the electromagnetic devices are connected according to the scheme counter zigzag and have three phase and one neutral conclusions, each phase output is intended for connection to the phase wire network,and a neutral output - zero wire, each electromagnetic device forms one output step, each stage power turns on when the circuit power contacts of the respective magnetic starter, the coil of which is driven by a scheme of automatic control, working in the function current zero wire and includes a current transformer installed in the neutral wire of the electrical network and two current relay and one time relays on each output step.
FIELD: electrical engineering.
SUBSTANCE: power supply device (100) for immediate electric heating of a pipeline system contains basically a three-phase transformer (2), a symmetrisation unit (14), a compensation unit (22). The three-phase transformer (2) is adapted for supporting a single-phase load connected between the first phase (6) and the second phase (8) of the transformer (2). The transformer (2) contains at least one first tap switch (10) on the high-voltage side (12) of the transformer (2). The symmetrisation unit (14) contains the first capacitor means (16) connected between the first phase (6) and the third phase (18) of the transformer and an inductor means (20) connected between the second phase (8) and the third phase (18) of the said transformer (2). The compensation unit (22) contains the second capacitor means (24) connected between the first phase (6) and the second phase (8) of the transformer (2). The first tap switch (10), the first capacitor means (16), the second capacitor means (24) and/or the inductor means (20) are adapted for variation under load.
EFFECT: changing the value of capacity and inductivity of the corresponding capacitive and inductive means under load and optimisation under load on a real time basis.
7 cl, 4 dwg
SUBSTANCE: three-phase filter balancing device comprises input and output terminals, to which a transformer is connected, having two groups of primary windings connected as serially and oppositely into a "zigzag". A neutral of the first group of primary windings is connected to a zero wire of a supply network and non-linear phase loads. A neutral of the second group of primary windings is an artificial neutral for linear phase loads.
EFFECT: reduced losses of power and its higher quality by separation of zero sequence currents passage paths for these loads.
SUBSTANCE: level of a specified higher harmonics in a power flux picked by a non-linear load is reduced by extraction of its energy in the form of an equivalent energy of sequence of unipolar periodically repeating width-modulated current pulses, by means of a fully controlled pulse-width-modulation rectifier of a transistor type, which is used to control a modulating signal proportional to the current of the specified higher harmonics. The extracted energy of the higher harmonics is disposed of, by means of its usage for supply to a DC load and accumulation in the form of a DC energy.
EFFECT: reduction of higher harmonic components levels in a supplying power system and increased efficiency of power usage.
FIELD: electric engineering.
SUBSTANCE: application: in electric engineering. The three-leg transformer in three-phase balancing device is comprised of three coils with the first, nearest to leg, and the utmost leg being connected in series and in accord between each other and the total number of windings in coils is equal to the number of windings in the second coil to be opposite connected in zigzag pattern. Free terminals of the first coils are connected to input and output clips, while free terminals of the second coils are integrated in one common zero point to connect phase loads. Semi-conducting a.c. switch is energised between zero terminal of power system and three-phase transformer.
EFFECT: improved reliability and reduced resistance of zero-sequence current.
2 cl, 1 dwg
FIELD: electrical engineering.
SUBSTANCE: according to the method, both reactive power and the active power component of the balanced phase group are used to supply DC load. Upon that, initially, the reactive power component is extracted from n-phases of the power grid, and then the active power component is extracted from at least one of the grid's phases, the active power component consists of a balanced phase group, via balancing currents. Furthermore, the power from reactive and active currents is extracted by means of a fully controlled solid state PWM rectifier, with phases being individually controlled via corresponding modulating signal. This power is extracted in the form of equivalent power of unidirectional repeating width-modulated current pulse sequence.
EFFECT: increase of power usage efficiency by reducing its non-productive losses.
SUBSTANCE: power required for supply of DC load is extracted with the help of a fully controllable n-phase WPM-rectifier of transistor type by means of balancing currents, at least from one phase, making a group of balanced phases, - so that the current that remained in each phase of the specified group picked by a non-balanced load, has a module value equal to either the one that has been previously determined or equal to the value of the current module in the reference phase, which has been previously selected from n-supplying phases of unbalanced system of power supply according to the condition of the maximum value of the current module.
EFFECT: increased efficiency of power usage by reduction of non-efficient losses in power flow caused by unbalance of phase currents.
SUBSTANCE: substance of method consists in distribution of highest load of lagging or leading phases of contact network at non-loaded phase of traction-feeding transformer. At that the highest capacity of one of phases of contact network is identified, voltage picked up from non-loaded phase of traction-feeding transformer is rectified and converted with the help of inverter driven by according phase of contact network, and step-up transformer into sinusoid voltage with frequency equal to frequency of the main harmonic of network, and specified voltage is supplied to according phase of contact network. Loading of non-loaded phase of traction-feeding transformer is carried out via rectifier and inverter, only at one phase of contact network, which makes it possible to transfer electric capacity to that phase of contact network, in which unit of contact network capacities comparison has identified the highest capacity.
EFFECT: increased efficiency of using capacity of traction-feeding transformer, reduced volumes of distortion capacity generation in the form of active power by reverse sequence and active power by high harmonics.
SUBSTANCE: device comprising serially connected reactor switches and shunting reactors, neutral of which includes parallel compensating reactor and breaker, capacitor batteries are additionally connected serially with shunting reactors in each phase from the side of neutral leads, shunted with switches.
EFFECT: reliability improvement.
SUBSTANCE: improved efficiency of method implementation is achieved due to multi-phase system balancing against specified phase, or phase with load current close to mean current, or less loaded phase defined as reference phase. By the method, balancing is implemented by generation of pre-formed currents by means of additional power source in each of remaining (n-1) phases, so that in each balanced (n-1) phase of the main n-phase network, the geometrical sum of currents generated in balanced phase and with load current is equal modulo to current in reference phase, and angle formed by the current of reference phase and total current of balanced phase following the reference phase at forward sequence of phases, as well as between total currents of neighbouring (n-1) balanced phases is equal to electrical degrees.
EFFECT: improved efficiency of multi-phase system balancing due to increased response and simplified implementation, extended application sphere, improved economy.
SUBSTANCE: method consists in generation by means of additional power source to each of the rest (n-1) phases of currents, which are pre-formed so that in each adjustable (n-1) phase of the main n-phase network the geometrical sum of currents - generated to adjustable phase and with current of its load can be equal as to current modulus to the current equal to current in reference phase, and the angle formed with the current of the latter and with total current of adjustable phase following the reference one at forward sequence of phases, as well as between total currents of neighbouring (n-1) adjustable phases can be equal to electrical degrees. At that, power takeoff to the above additional power source is performed from combination of at least two minimum loaded phases which are pre-determined by the condition of decreasing asymmetry in adjustable n-phase system.
EFFECT: increasing quick operation, economy, simplifying the implementation and enlarging application range.
FIELD: electrical and power engineering.
SUBSTANCE: proposed method intended for measuring current and voltage unbalance level and organizing on-line impact on them in three-phase power systems characterized in low quality of their power characteristics includes measurement of unbalance level with respect to reverse and zero sequence of both line and phase voltages and currents at frequency of each harmonic component. Frequency at which unbalance in analyzed characteristics occurs is found. Results obtained are used to generate control signal by correcting devices.
EFFECT: facilitated procedure.
1 cl, 5 dwg
FIELD: power engineering.
SUBSTANCE: method allows to fully utilize power of traction transformer due to loading its free phase by rectifiers and inverters, one of which is lead by leading phase of contact network, and second one of late phase, which allows to transfer electric energy to contact network, to exclude idling mode, to provide for lower asymmetry on reverse series in power grid 220 (110) kV, and also decreases level of higher harmonics.
EFFECT: higher efficiency, lowered values of quality coefficients of electric energy - asymmetry coefficient of reverse series and values of higher harmonics.
FIELD: electrical engineering.
SUBSTANCE: proposed method intended to enhance power quality characteristics for users subject to negative influence of higher harmonic components includes generation of circuit current higher harmonic components which are in phase opposition to higher harmonics of supply mains using electrical energy of independent power supply.
EFFECT: enhanced electrical energy quality characteristics for power consumers.
1 cl, 3 dwg
FIELD: electrical engineering.
SUBSTANCE: proposed method used to enhance quality characteristics of electrical energy supplied to users susceptible to impact of negative factors of electrical-energy higher harmonic components includes generation of higher harmonic components of current in network which are acting in phase opposition relative to higher harmonics of supply mains.
EFFECT: enhanced quality characteristics of electrical energy supplied to users.
1 cl, 3 dwg
FIELD: electric engineering, possible use in power circuits of various equipment.
SUBSTANCE: three-phased balancing device contains input and output clamps of powering networks. To output clamps, three-phased transformer is connected, primary windings of which are oppositely coupled in a zigzag. In accordance to the invention, between input and output clamps of powering network, first three-phased automatic switch is coupled, having an independent release. Serially with primary windings of three-phased transformer, second three-phased automatic switch is coupled. As zero contact for connection of phase loads, zero contact of primary windings of three-phased transformer, coupled oppositely in a zigzag, is used. Control block is connected serially to independent release, coupled between output clamp of one of the phases and zero contact of powering network, and ensures supply of voltage to independent release and activation of first automatic switch on disabling of second automatic switch.
EFFECT: increased reliability when powered from three-conductor or four-conductor powering network.
FIELD: electric engineering, possible use for powering various equipment.
SUBSTANCE: the balancing three-phased to one-phased transformer of alternating voltage contains input and output contacts, to which a transformer is connected which has primary windings in all three phases and two secondary windings in phases A and C. Primary windings are connected in a "zigzag". Windings of phases A and B, B and C, and also C and A are connected respectively. Secondary windings in phases A and C are coupled oppositely and are connected to output contacts.
EFFECT: reduction of stabilized power and asymmetry of primary currents and voltages.
FIELD: power production.
SUBSTANCE: when non-sinusoidal shape of supply voltage is decreased, electric power is distributed between electronic devices distorting the shape of supply voltage and electronic devices improving the shape of supply voltage during the semi-wave of supply voltage. Device is connected in parallel with consumers introducing distortions of voltage shape. Main voltage is supplied to the device input. Device includes serial connection of phase-shifting chain, control pulse shaper, dc power supply and power switcher, which connects consumers improving the shape of supply voltage to the mains at a certain period of time.
EFFECT: improvement of supply voltage shape and simplification of device design.
2 cl, 4 dwg
SUBSTANCE: invention concerns current power transmission equipment, particularly high-voltage power transmission. Device includes reactive shunts connected by reactive switches to line, with additional special reactive shunts connected to the line in star network pattern with unearthed neutral conductor.
EFFECT: enhanced shunt compensation of power transmission line in low load mode, stability and reliability in elimination of single-phase short circuits at single-phase reclosing.
FIELD: electrical engineering.
SUBSTANCE: invention relates to electrical engineering and may be used for hardware designing to improve quality and reduce voltage and electric power losses, when such power is transmitted in three-phase four-wire electric networks due to reduction of anharmonicity and asymmetry. Protection device generates 150 Hz frequency current from phase currents. This current is immediately introduced to harmonics 3 current of neutral working wire in opposite phase.
EFFECT: compensating highest current harmonics flowing along neutral conductor.
2 cl, 2 dwg
FIELD: electrical engineering.
SUBSTANCE: invention relates to electrical engineering, and can be used for phase-to-phase distribution of current in magnetically unstable three-phase signals, for example for neutralisation of zero-sequence harmful effects on current feed circuit in three-phase AC-to-DC and DC-to-AC voltage transformers. Proposed device comprises the transformer with its two phase windings connected, each by one output terminal, to zero input terminal, while their other output terminal is connected to appropriate phase input terminal. The transformer comprises two magnetic cores with phase windings connected in series and furnished with central tap. The said windings have their central and extreme free terminals connected to zero and common phase input terminals, respectively. Note here that central output terminal divides the number of turns in each phase windings into unequal parts, smaller ones being connected to opposing phase input terminals.
EFFECT: possibility to use two single-phase transformers with various-shape magnetic cores instead of three-phase transformer.