Device for eliminating the distortion of the voltage curve in distribution networks, ac
The invention relates to electrical engineering, in particular to power active filters, and can be used in power supply systems electrical and power circuits with distorted voltage and current loads to ensure collaboration powerful sharply varying loads sensitive to the distortion of the voltage receiving terminals, as well as to improve transfer efficiency and energy consumption. The technical result is to improve the waveform of the supply voltage. For this purpose, the device for eliminating the distortion of the voltage curve in distribution networks, the AC contains a source of alternating voltage, a controlled current source, a voltage sensor connected to the current-carrying busbars of the distribution network of an alternating current, and a current sensor. 2 Il. The invention relates to electrical engineering, in particular to power active filters, and can be used in power supply systems electrical and power circuits with distorted voltage and current loads to ensure collaboration powerful sharply varying loads sensitive to voltage distortion, the receiver is correct the distortion of the voltage curve in distribution networks, AC (see, for example, L. Gyugyi, E. Strycula Active AC Power Filter. // IEEE Trans. on Industry Applications, p.p. 529-535,1976).Closest to the present invention is a device for eliminating the distortion of the voltage curve containing passive LC-filter and active filter connected in series (see N. Fujita, H. Akagi. A Practical Approach to Harmonic Compensation in Power Systems - Series Connection of Passive and Active Filters. IEEE Trans. on Industry Applications, vol. IA-27, 6, pp. 1020-1025, 1991).The presence of the capacitors in the power circuit of such devices makes the General lack of such technical solutions to the problem of attaching a condenser batteries directly to AC current and potential issues associated with the resonance of such batteries with AC power, resulting in lower static and dynamic stability of the network. In addition, this leads to a significant increase in the voltage drop resonant harmonics on the internal impedance of the source and, as a consequence, a significant distortion of the voltage curve on the buses feeding the load.The essence of the invention lies in the fact that in the device for eliminating the distortion of the voltage curve in distribution networks, AC, containing the source of alternating voltage, a controlled current source, the sensor is Amy a current source and a source of alternating voltage connected in parallel. Connected in parallel to the controlled current source and a source of alternating voltage connected to the current-carrying busbars of the distribution network of an alternating current through the current sensor.In Fig. 1 presents a diagram of the device for eliminating the distortion of the voltage curve in distribution networks, AC, Fig.2 is a waveform of operation of the device.Device for eliminating the distortion of the voltage curve in distribution networks, AC (Fig.1) contains a source of alternating voltage 1; a controlled current source 2 connected in parallel to a source of alternating voltage; a voltage detector 3 connected to the current-carrying bus distribution network of AC VT; the current sensor 4, through which is connected in parallel to the controlled current source and a source of alternating voltage connected to the current-carrying bus distribution network of AC. To live tyre distribution network of AC VTconnected and the load 5.The device operates as follows.Generated power is 1 in the distribution network of AC presents nonideal source VSwith an internal impedance Z
Analysis (3) shows that if |K-ZL|0, the current IShalso approximately equal to zero.In other words, the current harmonics stops flowing through the branch source and completely flows through the branch impedance K, that is, the impedance K bypasses the source for harmonics of the nonlinear load. The branch source flows only active component of the load current Ia. Because harmonic currents from nonlinear loads in this case no longer flow through the source, and does not create a voltage drop of harmonics on the internal impedance of the source, and therefore does not distort the shape of the curve of the voltage VTon the supply tyres. Indeed from (4) it follows that under the above conditions VTVS.Parallel branch with the required impedance is implemented using a controlled current source 2.Data about the voltage at the busbars of the distribution network of AC VTand current tyre distribution network from the voltage detector 3 and the current sensor 4 is coming to a controlled current source. A controlled current source fulfills the desired impedance. Thus the giving of the voltage on the internal impedance of the generator, that, in turn, provides a sinusoidal curve of the supply voltage on the tyre distribution network of AC VT.In Fig. 2 shows waveforms of the mains voltage (top) and current generator (bottom). Scale: voltage 200 V/div., current 50 a/div., time of 0.01 s/div.From the waveforms shows that before the controlled current source began its work, the voltage on the supply bus bars and the current generator contained a large number of harmonics.However, when the controlled current source starts its operation, the voltage on the supply bus bars and the current generator be strictly sinusoidal.The use of the invention allows to improve the shape of the curve of the supply voltage, that is, to reduce harmonics in the supply voltage to zero than to ensure collaboration powerful sharply varying loads sensitive to voltage distortion power receiving terminals.
Device for eliminating the distortion of the voltage curve in distribution networks, AC, containing the source of alternating voltage, a controlled current source, a voltage sensor connected to tocover current and a source of alternating voltage connected in parallel and through the current sensor is connected to the current-carrying bus distribution network of AC.
FIELD: electrical engineering.
SUBSTANCE: two engineering solutions are proposed which are characterized in common engineering goal and common approach to solution. Power supply has transformer incorporating primary windings 1, magnetic core 2, and secondary windings 3; connected in series with the latter is diode bridge 4 closed through poles to reactor coils 5 and 6. Novelty is that central lead of reactor coils 5 and 6 is connected to neutral of load 7. The latter is connected to supply mains through switch 8. Diode bridge with similar double-coil reactor is inserted in series with neutral of all three phases of three-phase load. Novelty in this alternative is that reactor center tap is connected to neutral of supply mains. Damping (smoothing down current peaks) is effected both when three-phase and single-phase loads are connected.
EFFECT: enlarged functional capabilities, ability of damping inrush load currents.
2 cl, 2 dwg
FIELD: computer-aided checkup of electrical energy characteristics.
SUBSTANCE: proposed method involves evaluation of coefficients of current and voltage sinusoid distortions, checkup of these characteristics for compliance with their rated values, and generation of control signal by devices correcting sinusoid of voltage and current levels. This method is characterized in that subharmonic and higher fractional components of current and voltage are included in evaluation of coefficient of current and voltage sinusoid distortions due to determination of actual period of voltage and current variations with time.
EFFECT: enhanced precision of checking voltage and current for their sinusoid distortions.
1 cl, 4 dwg
FIELD: railway transport.
SUBSTANCE: invention relates to longitudinal supply wire systems of non-traction consumers arranged near ac electrified railways. Proposed high-voltage wire system contains three-phase traction transformer connected with contact system and rail-earth and longitudinal power supply line connected with power consumer through electrical meter and consisting of two wires-phases under electromagnetic influence of contact system. Said line is additionally provided with third wire-phase grounded at substation and three-contact switch designed for simultaneously switching off three wires-phases at system supply cutoff mode. All three wires-phase are arranged on supports of contact system or on separately standing supports from field at equal distance from contact system. Electrical meter is made in form of three-element energy meter one element of which is connected to grounded wire-phase in direction of consumer. Use of proposed system reduces asymmetry of voltages at consumers and provides possibility of use of three-element energy meters and precludes emergency situations owing to no resonance conditions with no power losses for resonance.
EFFECT: increased economy of system.
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: reducing voltage ripples across power consumers incorporating rectifiers and inverters.
SUBSTANCE: proposed device has regulation channel, pulse source, series-connected voltage sensor, AC voltage component computing device, comparison gate, delta-modulator, and four-quadrant converter. Regulation channel has series-connected converter transformer, thyristor bridge, amplifier, and pulse distributor. Converter transformer input is connected to supply mains and pulse source output, to pulse distributor input. Voltage sensor input is connected in parallel with converter transformer primary winding and its output, to input of AC voltage component computing device and to second input of comparison gate; four-quadrant converter output is coupled with converter transformer secondary winding.
EFFECT: enhanced power output and mean time between failures.
1 cl, 3 dwg
SUBSTANCE: invention is attributed to electric engineering. For this purpose the device contains compensating block, control system, voltage sensing device and current transformer at that the compensating block includes device for alternating voltage component calculating, comparing element, delta modulator and self-commutated voltage inverter. Power unit consists of converter transformer, thyristor bridge and engine. Primary winding of voltage sensing device is connected between network and "ground", secondary winding of voltage sensing device is linked with input of alternating voltage component calculating device and the second input of compensating block comparing element. Primary winding of current transformer is connected between the network and primary winding of converter transformer, secondary winding of current transformer is linked with output of self-commutated voltage inverter of compensating block. Output of control system is connected with the second input of thyristor bridge.
EFFECT: providing maximisation of device operation stability, increase of electric locomotive power and increase of its travelling speed.
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
FIELD: physics; radio.
SUBSTANCE: present invention pertains to transformation technology and can be used in power-line filters of radio interference. The technical outcome of the invention is the profound suppression of non-symmetrical electromagnetic interference with simultaneous meeting of electrical safety requirements on limiting capacitive leakage currents. Proposal is given of a method of reducing capacitive leakage currents on power-line radio interference filters, comprising one or more nodes, each of which is connected through a capacitor to the power-line filter lines and the case. The potential of one of the nodes is varied such that, the potential difference at low frequency between the given node and the case approaches zero. Potential of similar nodes of other sections of the filter are simultaneously controlled through chokes, decoupling at high frequency. As a result of reducing the potential difference at low frequency between the node and the case down to zero, all leakage currents on the case are practically eliminated. In particular, to implement the method, a signal is generated, proportional to the voltage between one of the indicated nodes and the case. That signal is applied to the input of a duo-directional amplifier, at the positive supply input of which a more positive voltage is applied through rectification, acting on the lines of the power-line filter at points of connection to capacitors of the given node. At the negative supply input of the duo-directional amplifier, a more negative voltage is applied through rectification from the same points of the lines of the power-line filter. Capacitors are re-charged by the output current of duo-directional amplifier and as a result, voltage between the given node and the case of the filter at low frequency is practically reduced to zero and consequently, all leakage currents on the case are eliminated.
EFFECT: reduced capacitive leakage currents of power-line filters of radio-interference.
2 cl, 3 dwg
SUBSTANCE: invention refers to the sphere of electrical engineering and is of relevance for design and development of technical equipment ensuring improved quality of electric power transmission through three phase four-wire electrical networks and reduction of power losses related thereto due to anharmonicity and asymmetry minimisation. The desired effect is due to the electromagnetic compensator identifying among the phase currents the one whose frequency value is equal to 150 Hz current which current is immediately injected in phase opposition to the third harmonic of the neutral lead current.
EFFECT: compensation for the largest spectral harmonic as circulating within the currents neutral lead.
3 cl, 2 dwg