Three-phase alternating current generating system with voltage inverter
SUBSTANCE: invention is related to the field of electric engineering and power electronics and can be used for manufacturing of HV three-phase alternating current generating systems for aircraft. The suggested three-phase alternating current generating system with voltage inverter contains a three-phase synchronous generator, a static electric energy transducer based on a three-phase bridge rectifier which inputs are connected to outputs of the synchronous generator, two filter capacitors in the direct current link connected in-series and switched on in parallel to the output terminals of the rectifier and a three-phase bridge voltage inverter which inputs are connected to the rectifier outputs and outputs are connected to inputs of three low-frequency LC filters; a neutral load wire of the generation system is connected to the average point of filter capacitors in the direct current link; an inductance coil is connected by its one output to the neutral load wire of the generation system and by its other output to the neutral wire of the stator three-phase winding of the synchronous generator.
EFFECT: reducing electric losses in elements and improving efficiency ratio of the system as a whole.
The invention relates to the field of electrical and power electronics and can be used to build systems generate electrical energy (SGAE) three-phase alternating current for aircraft in which to achieve qualitative indicators output energy applied static Converter of electrical energy (SPAA) with voltage inverter (JN). The primary sources with unstable parameters of the input energy in such systems is synchronous generator with variable speed of rotation of the shaft. Ensuring quality indicators generated electric power is vested in the static Converter and the output power low-pass filter.
For the specified application generation systems important indicator is the weight and dimensions of all elements of the system, the design of which must be pursued to its reduction. Weight and dimensions of the system generate largely determined by the magnitude of the coefficient (η) of its individual elements, so the challenge is to increase the value of this ratio.
A known system for generating electric energy of three-phase AC voltage inverter [Kharitonov S.A. Integral parameters and characteristics invert the ditch voltage in the systems of generating alternating current type variable speed - constant frequency for wind turbines. Scientific Bulletin of the NSTU, Novosibirsk, 1999. No. 2 (7). 92-120 S.], containing three-phase synchronous generator with output neutral wire, static Converter of electrical energy on the basis of the three-phase bridge rectifier, two filter capacitors in the DC link connected in series, and a three-phase bridge voltage source inverter with three low-pass LC filters, zero wire load system connected with the zero wire of the generator and the middle point of the filter capacitors in the DC link.
This system has a number of disadvantages. The connection of the neutral wire synchronous generator with system load generation and the middle point of the filter capacitors in the DC link leads to an increase in current of the generator is approximately
In addition, the known system for generating electric energy of three-phase AC voltage inverter [Kharitonov S.A., Korobkov A.R., A.S. Khlebnikov and Some other results of the development of power systems for aircraft. Technical electrodynamics, special issue "Power electronics and energy efficiency". Kyiv. Institute of electrodynamics of national Academy of Sciences, 2010, T.1. P.88-89], which is the prototype of the present invention containing three-phase synchronous generator, a static Converter of electrical energy on the basis of the three-phase bridge rectifier, the input of which is connected to the outputs of the synchronous generator, two filter capacitors in the DC link connected in series and connected in parallel to the output terminals of the rectifier, and a three-phase bridge voltage source inverter, the input of which is connected to the outputs of the rectifier, and o the dy - to the inputs of three low-pass LC filters, zero wire load system generation is connected to the middle point of the filter capacitors in the DC link (figure 1).
The disadvantage of this system is that you must install in parallel with the filter capacitors of the DC link current is relatively low ohmic resistors R, which are necessary to reduce the DC component in the output voltage of the system generation, arising from the difference between the static and dynamic characteristics of the power transistors of the inverter, and also in connection with the inaccuracy playback of law control the power transistors of the inverter [Grabovetskaya, GV, Korobkov D.V., Kharitonov, S.A. Features of the operation of the inverter voltage in the system generating electric energy of the aircraft. No. 1 (18), January-June, pp.69-79]. In this work, in particular, it is shown that for the suppression of the DC component in the output voltage of the system generation using negative feedback with integral regulator, provided that the sum of a permanent component without feedback was equal to 1.6, you need to meet the conditions of R<(8÷10)RH0where RH0- load resistance systems generate DC. Given that the voltage across the resistor R is approximately equal to the
The objective of the invention is to reduce the weight and dimensions of the system generation by increasing the magnitude of the efficiency of its individual elements.
This object is achieved in that in the known system, the generation of electric energy of three-phase AC voltage inverter, containing three-phase synchronous generator, a static Converter of electrical energy on the basis of the three-phase bridge rectifier, the input of which is connected to the outputs of the synchronous generator, two filter capacitors in the DC link connected in series and connected in parallel to the output terminals of the rectifier, and a three-phase bridge inverter voltage, the turns of which are connected to the outputs of the rectifier, and outputs to the inputs of three low-pass LC filters, zero wire load system generation is connected to the middle point of the filter capacitors in the DC link, enter the inductor, which one output is connected to a zero load wire system generation, and the other to a zero output three-phase stator winding of the synchronous generator.
Scheme of the proposed system generating electric energy of three-phase AC voltage inverter is shown in figure 2.
The generation system includes a synchronous generator (1) with excitation from permanent magnets and three-phase winding on the stator () with output neutral wire (NSG), the static Converter of electrical energy (2) and low-pass LC filter (3). In the static Converter (2) includes a rectifier (4), which can be both unmanaged and managed, in the latter case it can be implemented on any managed security keys; two capacitor DC link (5, 6), connected in series with the output midpoint NWiththe voltage inverter (7). Low-pass LC filter (3) can be implemented by any known scheme such filters in figure 2 as an example, a diagram of the l-shaped LC filter of the second order. It should be noted, Thu is the filter capacitors can be included in the triangle.
Conclusions three-phase winding (THAT) generator (1) connected to respective three-phase inputs (TV) static Converter (2), in which they are connected with three-phase input rectifier (4). Parallel to the findings DC rectifier (4) is connected capacitors (5, 6)connected in series, and their average point NWithconnected with the zero wire of the Nnthe load of the system generation (9) and one of the conclusions of the inductor (8), the second output of which is connected to the output neutral conductor NSGsynchronous generator. Inputs DC voltage inverter (7) is connected with the conclusions of the DC rectifier (4), three output AC inverter connected to the same inputs of low-pass LC filter, the findings of which are connected to the load of the system generation (9).
The proposed system operates as follows.
The inductance L0coil inductance (8) is selected:
where ωSG min- minimum cyclic frequency of the synchronous generator voltage, C is the capacitance value of the capacitors (5, 6).
The choice of a value for L0in accordance with equation (1) preserves the "chistipolsky" mode rectifier, because currents with frequency 3ωSG minthe electrical circuit between the points NSGand NWithhas a very high resistance. When this DC this circuit has almost zero resistance, the role of the resistance R in the circuit in figure 1 will perform output impedance DC three-phase zero-circuit rectification (REQ), the maximum value of which according to [I. Kaganov Electron and ion probes. Part III / Ilegenes. - M.: State energy publishing house, Moscow, 1956. - 528 S., Il.] will be equal to:
where ωSG max- maximum cyclic frequency of the synchronous generator voltage, Ld, Lqthe Indus is aktivnosti SG along the longitudinal and transverse axes.
It is obvious that the resistance value will satisfy the inequality
because the value of
Thus, in the proposed scheme system generating no problems with working DC component in the output voltage of the system generation, as is the inequality (3)is excluded, the resistor R, which reduces the electrical losses in the elements of the system generation, increased efficiency and, consequently, decrease the weight and dimensions of the system.
The system of generating electric energy of three-phase AC voltage inverter, containing three-phase synchronous generator, static transformed the Converter of electrical energy on the basis of the three-phase bridge rectifier the inputs of which are connected to the outputs of the synchronous generator, two filter capacitors in the DC link connected in series and connected in parallel to the output terminals of the rectifier, and a three-phase bridge voltage source inverter, the input of which is connected to the outputs of the rectifier, and the outputs to the inputs of three low-pass LC filters, zero wire load system generation is connected to the middle point of the filter capacitors in the DC link, wherein introducing the inductor, which one output is connected to a zero load wire system generation, and the other to a zero output three-phase stator winding of the synchronous generator.
SUBSTANCE: voltage stabiliser for a power supply system, which stabilises load of active power, comprises the first AC-DC and DC-AC converter to convert between AC power and DC power; and a nickel-metal-hydride battery located between and connected to a high-voltage cable at the DC side of the first AC-DC and DC-AC converter and a low-voltage cable at the DC side of the first AC-DC and DC-AC converter.
EFFECT: reduced mass and dimension parameters of a device.
10 cl, 17 dwg
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.
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.
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.