Device for measuring the negative sequence voltage in a three phase system outlet
(57) Abstract:The invention can be used in Metrology indicators of the quality of electric power in three-phase networks of industrial frequency. The inventive device for measuring the negative sequence voltage in a three phase system grid contains braked motor 1 with multiple measuring coil 2, the switch 3, the synchronizer-limiter 4, the integrator 5, the selective filter 6, an amplifier 7, a detector 8, the indicator 9 voltage corrector 10 technological errors. 1 Il. The invention relates to Metrology performance power quality (SCE) in a three-phase industrial frequency of 50 Hz. The device measures voltage reverse power General purpose.It is known device  , performed on three transformers with nine secondary windings, six rectifiers, three potentiometers. In transformers device formed six-phase voltage on the secondary (primary and secondary) windings, the coils are bound by strict interdependence. These stresses act on the six gates, the output of which occurs displaced the STS - acceptable accuracy (5-10% ). The disadvantage is the difficulty of manufacturing technology identical transformers. Closest to the invention is a device  , containing a synchronous electromachine, in a rotating rotor which (if any unbalance in the grid) there is a counter-rotating magnetic field EMF (twice the power frequency, 100 Hz) and amplitude proportional to the voltage of the reversed sequence. Dignity devices - high precision measurement. The disadvantage is the presence of rotating parts and, consequently, reducing the metric parameters in time.The purpose of the invention is the measurement and operational control reverse sequence with high accuracy (1-2% ).Goal is achieved by slow motor with multiple measuring windings of the rotor blocks amplitude-pulse coding and processing of the useful signal transistors and chips.The device includes (see drawing), inhibited the motor-sensor 1 with the measuring windings 2, switch 3, the synchronizer-limiter 4, the integrator 5, the selective filter 6, an amplifier 7, a detector 8, the indicator 9, the corrector 10 tehnologicheskimi measurement, due to mechanical rotation, electronic switch performs a serial poll EMF windings, concealer (passive RC circuits) is used to align technological variations of the magnitude and phase of the respondents EMF windings, synchronizer stop forms of network voltage control signals switch and blocks of electronic circuits from overvoltages in the measured power. The stated differences from the prototype informs the device the new property.The operation of the device in the dynamics. Voltage three-phase network is fed to the stator windings of the motor 1 and the synchronizer stop 4. When the asymmetry in the power grid, the intensity distribution of the magnetic field in the rotor windings in a plane perpendicular to the axis of the motor, resembles an ellipse. In sections of the rotor induced EMF is proportional to the magnetic flux, rotating with the frequency of the mains. Synchronizer-limiter 4 generates the synchronous frequency of 50 Hz signals control the operation of the switch 3. Corrector 10 compensates for the variation of EMF windings. Switch 3 generates a sequence of pulses for successive survey windings in accordance with the locations of each of the n) contains the envelope frequency of 100 Hz, proportional to the negative sequence voltage. This voltage is derived by the integrator 5, a filter 6, is amplified to the required level by the amplifier 7, passes the detector 8 and gets on indicator 9, which captures the desired voltage reverse order. The estimated error of the meter 1-2% .These studies confirm the advantages of the proposed technical solution in comparison with the prototype. (56) USSR Author's certificate N 1272402, CL N 02 F 3/26, 1984.Zielonko I. C. Indicators of power quality and control in industrial plants. M : Atomizdat, 1986, S. 47. DEVICE FOR MEASURING the negative SEQUENCE VOLTAGE IN a three PHASE ELECTRICAL SYSTEM containing an electric motor, a filter and a voltage indicator, characterized in that, to improve measurement accuracy, put the switch corrector technological errors, synchronizer stop, integrator, amplifier, detector, and the rotor locked motor equipped with a multi-section measuring winding, the conclusions of which is connected through serially connected corrector technological errors, a switch, an integrator, a filter, such operation is controlled network, to which is also connected to the input of the synchronizer-limiter, the output of which is connected with the control input of the switch.
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.