The reactive power compensator
(57) Abstract:Area of use: for the three-phase voltage substations (industrial, traction and forming part of the power systems for compensation and reactive power control. The inventive compensator contains a three-phase bridge with lockable gates included in the reactor, two Converter block and capacitors for surge suppression. Each Converter unit contains two groups of three lockable valves and the reactor between them in the branch DC. One group of valves has an angle regulation2=1+ and the other3=1- where1- the angle of the control valve three-phase bridge, the angle value and the ratio between the constant currents of the three-phase bridge Converter blocks are selected so as to reduce the content of higher harmonics in the input current compensator. 3 Il, 1 table. The invention relates to power engineering and can be used on three-phase voltage substations (industrial, traction and forming part of the power systems for compensation and reactive power control.Famous new reactive power compensator before the district thyristor compensator  is they give reactive power due to the forced commutation of the current in the negative angles regulation. As a result, for issuance to the power grid reactive power is not required structures capacitor Bank corresponding capacity.In a known compensators to improve the quality of the input current (to reduce the content of higher harmonics) are used converters high pasnosti 12,18 and 24-phase .Their lack of need to use one winding or several two-winding transformers, the impossibility of a direct connection of the Converter to the tires of three-phase voltage.Closest to the invention is the compensator with one two-winding transformer, three-phase bridge with lockable gates and capacitors to limit surges that occur when forced, almost instantaneous switching current lockable gates .The disadvantage of this compensator in the quality of its input current, which contains higher harmonics of order n = 6k 1, where k = 1,2,3..., has a high THD (about 30%).TSE is of the compensator directly to the tires without the use of a transformer.The essence of the invention lies in the fact that the proposed compensator to its entrance in addition to the three-phase bridge connected two Converter unit with multi-directional lockable gates. Each block contains two groups of valves and the reactor between them in the branch DC. One group of three valves has an angle regulation2=1+ and another group3=1- where1- the angle of the control valve three-phase bridge.The angle value and the ratio between the constant current Id1three-phase bridge and a constant current Idthe first and second unit are selected so as to reduce the content of higher harmonics in the input current compensator. Good results are obtained when = 24aboutand Id1= Idor = 30aboutand Id1= Id.Adding these two Converter blocks improves the quality of the input current compensator due to the formation of the three input phase currents of the bridge and both blocks and produce a three-stage current, similar in its shape to a sine wave. Note that adding two Converter blocks leads to a corresponding increase in power compensator and therefore obiecana diagram of the proposed compensator; in Fig.2 and 3 are graphs showing the form of the compensator currents.Three-phase input of the compensator 1 (Fig.1) is connected capacitors 2, three-phase bridge 3 with lockable gates 4 and reactor 5, the first converting unit 6 with lockable valves 7 and 8 and the reactor 9, and the second Converter unit 10, which differs from block 6 only reverse the direction of the gates.Capacitors 2 provide limitation of overvoltage arising from virtually instantaneous switching current lockable gates. Power capacitor 2 does not exceed 15% of the nominal power of the compensator. Capacitors 2 can be connected in a "star" (Fig.1) or on a "triangle".When the compensator with the consumption of reactive power valves 4 three-phase bridge 3 are angle regulation1= 90about- where the angle depends on the power losses in the compensator, its value lies in the range 1about. When the compensator with the issuance of reactive power angle1= -90about+ .Groups of three lockable valves 7 Converter blocks 6 and 10 have the angle regulation2=1and groups of three lockable valves 8 of these blocks - angle mode is constant current Idthe first and second Converter block are selected so as to reduce the content of higher harmonics in the total current of the bridge and both blocks and, as a consequence, in the input current compensator.Good results in reducing the higher harmonics in the input current are obtained in two variants: = 24about, Id1= Id; = 30about, Id1= Id.Graphics currents compensator for the first variant built on Fig.2 assuming constant currents of the bridge 3 and blocks 6 and 10 fully smoothed reactors 5 and 9. Relative to the time axis 11 shows the phase current i1at the entrance of the bridge 3, relative to the time axis 12 and 13, respectively phase currents i2and i3valves 7 and 8 two Converter blocks 6 and 10. Built timelines phase current i1, i2and i3belong to the same phase. In accordance with the angle regulation2current i2ahead of the current i1angle = 24about.Similarly, in accordance with the angle regulation3current i3lags the current i1on the same angle = 24about. Relative to the time axis 14, we plot the phase current i, which is a sum of phase currents of the bridge and three-phase bridge.Input current compensator consists of two components: current converters i and a relatively low current of the capacitor 2, therefore, the quality of the input current can be judged by the quality of the current transformers i.Current converters i contains the first harmonic of i(1)and higher harmonics i(n). The first harmonic of i(1)it is shown in Fig.2, its effective value
I(1)= (1+2cos24)Id= 2,20 Id.When the compensator angle regulation of three-phase bridge -90aboutthe first harmonic of i(1)current converters ahead of the corresponding phase voltage U on the 90aboutas shown in Fig.2. The compensator thus shows the electrical network to which it is attached, reactive power. When190aboutthe first harmonic of i1current transducers behind at the same angle from the voltage compensator consumes reactive power value (issued and consumed) is subject to a small change of angle control valves, which leads to a change of the currents Id1and Id.The relative importance of each of the higher harmonics of order n in the current transducers i of the version under consideration to/P> The results of the calculation of I(n)*for the first eight harmonics contained in the currents i1, i2and i3shown in the table. For comparison it also lists the known values of I(n)*for the current i1three-phase bridge.These tables describe the reduction in the content of higher harmonics in the input current of the proposed compensator. When Id1= Idand = 24aboutin the input current of the proposed compensator is missing 5-th and 25-th harmonic, the other harmonics are reduced. To improve the quality of the input current is especially important exception of the 5th harmonic and a significant decrease in the magnitude of the 7th and 11th harmonics. The THD of the current i of about 10%, about 3 times less than for the current i1.Schedule DC converters i, for the second variant of its formation, when Id1= Idand = 30aboutbuilt on Fig.3. Was a well-known classical form of the input current 12-phase Converter. This current i contains the first harmonic and higher harmonics of order n = 12k 1, where k = 1,2,3, . .. There are no harmonics, for which n = 5, 7,17, 19... the Relative values of the remaining harmonics (n =11,13,23,25...) are the same as in Thus, both options give good results in the decrease in the input current compensator higher harmonics and, as a consequence, to improve its quality.Can be applied to other variants of the formation of the three-current transformers i. So, for example, to exclude it 7th harmonics should Id1= Idset angle = 17,1about. In this embodiment, the relative values of the 5th and 11th harmonics, respectively, of 7.9% and 3.1%, the THD of the current is about 13%.The choice of one or another variant of formation of the three-step current (ratio between the Id1and Idand the value of the angle ) depends on the specific parameters of the electric network, which connects the compensator (primarily from the frequency characteristics of its reactance) and from the requirements to the quality of the input current compensator. The REACTIVE POWER COMPENSATOR containing a three-phase bridge with lockable valves, reactor, included between the poles of the bridge, and capacitors connected to the three phase input of the compensator on a "star" or "triangle", wherein the input of the compensator additionally attached two preobrazuemyh valves and the reactor between them in the branch DC the first and second groups of gates are angles regulation
2=1+ and3=1- ,
1- the angle of the control valve three-phase bridge,
and the angle is selected within 17,1o30oprovided that the ratio
where I is the constant current three-phase bridge;
Id- DC Converter units.
FIELD: electrical engineering; energy storage, motor starting gear, ac networks.
SUBSTANCE: polarized capacitors or electrochemical batteries are used in standard ac circuits as polarized electrical charge storage devices with new circuit pattern. In one of alternatives opposing-series configuration of first and second polarized devices is used in ac network to improve its operating conditions. At least one dc power supply is provided to keep polarized devices shifted in forward direction when ac signal arrives at them. This ac signal is applied to devices connected in series opposition to excite ac load. These devices are sufficiently shifted by at least one dc voltage supply so that they remain displaced in forward direction upon connection to ac signal.
EFFECT: enhanced effectiveness and economic efficiency of polarized charge storage devices in all their applications.
64 cl, 32 dwg
FIELD: electrical engineering; correction of instant-power passive components associated with characteristics features of load.
SUBSTANCE: proposed corrector uses circuit arrangement of single-phase voltage inverter in the form of transistor bridge incorporating inverted diodes with storage capacitor connected across two diagonally opposite dc terminals and two diagonally opposite ac terminals connected through choke to supply mains in parallel with load; choke has sectionalized coil, that is it is made of two sections with output lead in-between; corrector is provided with newly introduced switch built around two thyristors and used to connect one section of choke coil during discharge of storage capacitor and both sections during its charge.
EFFECT: enlarged adjustment range of instant-power passive components; enhanced reliability of corrector.
1 cl, 2 dwg
FIELD: reactive power correction in three-phase loads.
SUBSTANCE: proposed reactive-power corrector has three-phase transformer, three single-phase inverters with control systems, rectifier, three single-phase current transformers, potential transformer, three single-phase reactive-current sensors, three voltage sensors, three comparison gates, and load; in addition it is provided with newly introduced unit of off-line voltage inverters, active and reactive power computing unit, active and reactive power ac component computing unit, desired current computing unit, off-line voltage inverter control unit, and current transformers of off-line voltage inverters.
EFFECT: enhanced mean power factor of enterprises, reduced maintenance charges.
1 cl, 1 dwg
FIELD: electrical engineering.
SUBSTANCE: proposed device tat can be used to raise efficiency of electrical energy consumption due to relieving power supply mains of reactive currents has three-phase diode bridge connected to supply mains through three reactors; connected at dc output of this diode bridge through isolating diodes are three storage capacitors. Device also has bridge inverter built around six transistors connected through their outputs to ac input of diode bridge and three additional transistors connecting dc input of inverter to storage capacitors. Transistor control system functions to convert signals arriving from outputs of voltage sensors across load, load and supply mains current sensors, and to generate thyristor control signals so that source automatically generates correction currents equal to reactive currents consumed by load, and only resistive component of load currents is consumed from supply mains.
EFFECT: reduced mass and size of device, ability of generating sine-wave corrective currents.
1 cl, 2 dwg
FIELD: electrical engineering; power factor correction for ac electric locomotive.
SUBSTANCE: reactive power correcting device has traction transformer, electric-locomotive rectifying converter with traction motor connected thereto, two reactive-power sources, supply-mains mode sensor, and switching unit; newly introduced are also two switching members, each incorporating thyristor switch, voltage sensor built around thyristors, and thyristor-switch control pulse shaper, as well as two resistors; thyristor switches are connected in series with first and second reactive power sources and resistors are connected in parallel with capacitors of respective reactive-power sources.
EFFECT: enhanced power factor due to improved waveform of output current and more complete correction of input-current reactive component under various operating conditions.
1 cl, 1 dwg
FIELD: power engineering; automatic tuning of capacitive current correction in network incorporating plunger-type arc-control reactor.
SUBSTANCE: proposed device for automatic tuning of adjustable-gap arc-control reactor correction has motor control unit connected to correction maladjustment recording unit and to control input of mentioned arc-control reactor provided with motor for air gap adjustment. Motor control unit has first contactor control unit connected through first auxiliary contact to correction maladjustment recording unit, second contactor control coil connected through second auxiliary contact to correction maladjustment recording unit, and third contactor control coil. First and second power contacts are connected to control input of adjustable-gap arc-control reactor; third and fourth auxiliary contacts are connected to short-pulse shaper. Final relay is connected to short-pulse shaper and its contact is inserted in third control coil of contactor. Fifth and sixth auxiliary contacts are connected in series with first contactor control coil and with second contactor control coil, respectively. Motor control unit also has rectifier bridge connected through limiting resistor and third power contact to control input of mentioned reactor incorporating air gap adjusting motor.
EFFECT: enhanced precision of reactor tuning in resonance with network capacitance.
1 cl, 2 dwg
FIELD: regulation and reactive power correction in power systems; inverters for high-voltage frequency-controlled electric drives.
SUBSTANCE: proposed converter is built around combined circuit arrangement incorporating three-phase bridge circuit of voltage inverter (with series-interconnected semiconductor devices of IGCT, IGBT, and other types) with one or more series-interconnected single-phase bridge voltage converters (whose semiconductor devices are not interconnected in series)connected to each of its phase outputs. All change-over operations are made in three-phase bridge circuit whose arms form valves with series-interconnected semiconductor devices and which forms output voltage base of converter at low frequency (such as that equal to supply mains frequency). Bridge arms incorporating series-interconnected semiconductor devices having different on/off delay times are changed over by means of switching circuits specially inserted in circuit.
EFFECT: enhanced reliability reduced power loss in building converter combined circuit, reduced dynamic loss in semiconductor devices.
3 cl, 9 dwg
FIELD: electric engineering, possible use for engineering of traction electric engines of electrically driven train.
SUBSTANCE: station for testing electric engines has transformer, controllable rectifier, inverter, engine, generator, first and second smoothing reactors, connecting shaft, voltage indicator, first and second current indicators, device for calculating input active current, first and second comparison element. Proportional-integral adjuster, pulse-duration modulator, autonomous voltage transformer and source of reactive power in form of a capacitor. Utilization of station for testing electric engines allows to increase value of power coefficient up to 0,994, and during testing of, for example, electric engine NB418 K6 of electrically driven train current consumed from network is decreased to 5-7 A.
EFFECT: increased energy coefficients due to increase of value of power coefficient by improving form of network current and approach of its phase to network voltage during substantial decrease of energy consumption.
FIELD: power engineering; reactive power correction.
SUBSTANCE: proposed method for controlling reactive power correction device incorporating thyristor-reactor group, higher-harmonic capacitor-bank filters, and reactive-power static condenser built around fully controllable diodes includes measurement of voltage U across ac buses, its comparison with Umax and Umin settings, generation of control signals, and generation of harmonics in static condenser current in phase opposition to current harmonics of thyristor-reactor group detected during analysis.
EFFECT: twice as low power of thyristor-reactor group, enhanced efficiency of input reactive power control and higher harmonic filtration.
1 cl, 1 dwg
FIELD: electric engineering, on railroad train of one-phased alternating current with zone-phased adjustment, acting as means for increasing power coefficient.
SUBSTANCE: reactive power compensator is connected in turns to one of several sections of secondary winding of traction transformer, powering appropriate shoulders of rectification-inversion transformer. Depending on value of reactive power of circuit, sections of reactive power source are connected to power source. Device for realization of proposed method for controlling reactive power compensator, additionally contains keys, which through reactive power compensator are connected to sections of secondary winding of traction transformer, keys control block, operation mode set-point device, indicators of voltage and current, calculating-measuring block.
EFFECT: compensation of reactive power, consumed by electric locomotive, and decreased electric energy consumption.