Three-phase reactive-power corrector
 Single-phase instant-power passive component corrector / 2249896Proposed 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. |
 Method and circuit arrangement for using polarized devices in operation on ac current / 2249285Polarized 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. |
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Method and circuit arrangement for using polarized devices in operation on ac current / 2249285 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. |
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Single-phase instant-power passive component corrector / 2249896 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. |
 Three-phase reactive-power corrector / 2251192Proposed 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. |
 Transistorized tree-phase reactive-current supply / 2254658Proposed 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. |
 Reactive power correcting device / 2256994Reactive 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. |
 Device for automatic tuning of adjustable-gap arc-control reactor correction / 2266600Proposed 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. |
 Voltage converter built around combined circuit arrangement / 2269196Proposed 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. |
 Station for testing electric engines / 2271547Station 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. |
 Method for reactive power correction device / 2280934Proposed 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. |
 Method for controlling compensator of reactive power and device for realization of said method / 2282295Reactive 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. |
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
The device relates to electrical engineering and is intended for compensation of reactive power three-phase consumers, particularly industrial enterprises.
The power factor is one of the main energy indicators receivers of electric energy, which determines the unproductive consumption of reactive power. Currently, the power factor of the energy-intensive enterprises is only about 0.6-0.7. Low power factor leads to significant energy losses. The high power factor is achieved by reactive power compensation, the value of which depends on the approximation of the phase of the input current to the line voltage, as well as improving the shape of the consumed current. When a sinusoidal shape of the mains voltage the most widely direction of reactive power compensation by affecting the shape of the network current. In three-phase networks at the waveform distortion of the network voltage reactive power compensation can be made by balancing the network voltage magnitude and phase, as well as improve its shape.
It should be noted that when the asymmetry of the mains voltage, for example, in asynchronous motor only higher harmonics voltage direct sequence create a useful point,harmonics same reverse order - braking torque, and zero-sequence - pulsating electromagnetic field. The resulting torque on the motor shaft is defined as the sum of the moments of individual harmonics, so the chances are developing higher harmonics degrade the parameters of the engine.
It is also known that the degree of distortion of the network voltage is determined by the content of higher harmonic components. Harmonics affect the energy performance of the devices. The improvement of the sinusoidal mains voltage by compensating only the third harmonic voltage increases cosϕ engine 2-3%efficiency - 1.5%. The degree of distortion of the voltage regulated by GOST 13109, should not exceed 5%.
Known three-phase reactive power compensator in the form of a three-phase buck devices [1], intended for compensation of reactive power by controlling the voltage at the terminals of the consumer.
The device comprises a three-phase main and booster transformers, autotransformer, and the AC voltage regulator and the load.
The first output of the primary winding of the booster transformer is connected to three-phase AC power, and its second output from the main transformer connected to the load and the first input of the autotransformer. The second conclusion and is cotransformation through the regulator AC voltage is connected to the secondary winding of the booster transformer.
On the secondary winding of the booster transformer is energized from the output of the autotransformer, adjustable using knob AC voltage. The change in the voltage on the secondary side allows you to regulate the voltage across the primary winding of the booster transformer. The vector of incremental voltage booster transformer, adding to the voltage of the main transformer, changes the vector of the load voltage magnitude and phase. Thus, three-phase reactive power compensator improves the power factor by balancing phase and changes the voltage level of the consumer.
However, changing the phase voltage at the load causes incomplete compensation of reactive power. This is because in this device the change in phase of the output voltage at a certain angle creates a phase shift of the input current at the same angle. This increases the phase angle shift between the input current and the mains voltage, which reduces cosϕ device and leads to incomplete compensation of reactive power.
In addition, the value of the output voltage is changed discretely and has 12 positions of the vector of incremental voltage. Such a device does not provide accurate control of the voltage at the terminals of consumer is the appropriate fields not fully compensate for reactive power.
Closest to the claimed invention, a maximum number of similar features and the achieved result is a three-phase reactive power compensator [2], which compensates for the reactive power due to the balancing and modifying the amplitude of the output voltage.
Three-phase reactive power compensator includes a three-phase transformer, three-phase inverter control systems, rectifier, three-phase current transformer, three-phase measuring voltage transformer, three-phase reactive current sensor, three sensor voltages, three comparison element and the load.
Secondary winding three-phase transformer are connected in series with the primary windings of single-phase transformers of current and included between the network and the load. The primary winding three-phase transformer connected to the outputs of the single-phase inverters. The first input single-phase reactive current sensors are connected to secondary windings of single-phase transformers current, a second input from the other two phases of the secondary winding of three-phase measuring voltage transformer, the primary winding of which is connected to the network. The outputs of single-phase reactive current sensors connected to first inputs of the control system. First the e inputs of the elements of comparison across the voltage sensors connected to the phases of the load, the second inputs to the source of the setpoint voltage. The outputs of the elements of comparison associated with the second inputs of the control system. The third inputs of the control system connected to the network. Each output of the control system connected to respective first inputs of single-phase inverters. The inputs of the rectifier is connected to the connection point of the primary windings of single-phase measuring current transformers and three-phase secondary windings of the transformer, and outputs to the second inputs of the single-phase inverters.
The signals of the phase currents and voltages from the output of the phase measuring current transformers and three-phase measuring voltage transformer serves to corresponding inputs of a single-phase reactive current sensors. The values of these signals at the output of single-phase sensors reactive current generated voltage proportional to the reactive current. These signals are sent to respective first inputs of the control systems of the inverter. Each sensor voltage forming voltage signal load, which with the help of the elements of the comparison is compared with a preset voltage, for example par. The difference of these signals from the output of the elements of the comparison is fed to each second input of the control systems inverters. Single-phase inverters form the voltage supplied to the secondary ammodytidae transformer. These stresses are determined by the magnitude of the reactive current and voltage deviation load from the specified level. With the help of straightener is the supply of constant voltage single-phase inverters.
The output voltage of the compensator, for example phase A U2ais formed from the voltage U1aand single-phase voltage inverter δ Ufa·eja.
Voltage single-phase inverter is regulated in amplitude by changing the duty cycle δ its output pulses and phase by changing its angle control α . Using primary and secondary phase windings of a three-phase transformer output voltage single-phase inverter is reduced in proportion to the ratio Ktand added to the supply voltage. As a result, the voltage of phase a of the load is:
From the expression (1) shows that the amplitude and phase of the voltage vector U2acan be adjusted by changing δ and α . Changing the duty cycle of pulses δ depending on the magnitude of the reactive current, and angle adjustment α - deviation of the load voltage. When the consumption of the reactive power compensator output single-phase sensor reactive current is supplied to the first control input of the system in the management of single-phase inverter. Depending on the magnitude of the reactive current is increase (decrease) duty cycle δ single-phase voltage inverter. Thus is the increase (decrease) the angle between the mains voltage U1aand the load voltage U2A. When this voltage sensor monitors the load voltage phase A U2aand sends a feedback signal to the comparison element. This signal is compared with a signal proportional to the specified mains voltage. The difference of these signals is supplied to the second control input of the control system single-phase inverter. Depending on the magnitude of this signal changes the angle control valves α single-phase inverter. As a result of this control vector voltage single-phase inverter has a magnitude and phase that the vector network voltage U2ais the radius of a given circle. The process of reactive power compensation by changing the voltage in the other two phases is similar. Such voltage regulation ensures the balancing of the magnitude and phase of the three-phase output voltage.
However, the known device does not fully compensate for reactive power. This is because in this device, the reactive power compensation is carried out by exposing only the part of the factors, determining a reactive power compensation, namely the balancing and modifying the amplitude of the output voltage.
The basis of the invention is consisting in the creation of three-phase reactive power compensator, which provides for full compensation of reactive power at the expense of all factors affecting the compensation of reactive power: improving the shape of the mains voltage while improving the shape of current consumption, as well as the preservation of symmetry and the voltage at the load.
To solve the problem in three-phase reactive power compensator containing a three-phase transformer, three-phase inverter control systems, rectifier, three-phase current transformer, three-phase measuring voltage transformer, three-phase reactive current sensor, three sensor voltages, three comparison element and the load, and the secondary winding three-phase transformer are connected in series with the primary windings of single-phase transformers of current and included between the network and the load, the primary winding three-phase transformer connected to the outputs of single-phase inverters, single-phase secondary winding of current transformer connected to current inputs single-phase sensor is in reactive current, the voltage inputs are connected to the other two phases of the secondary winding of three-phase measuring voltage transformer, the primary winding of which is connected to the network, the outputs of single-phase reactive current sensors connected to the first inputs of the control system, the input elements of comparison across the voltage sensors connected to the phases of the load, and the second inputs to the source of the setpoint voltage, the outputs of the elements of comparison associated with the second inputs of the control system, the third inputs of the control system connected to the network, and the output from the first input single-phase inverters, the input of the rectifier is connected to the connection point of the primary windings of single-phase measuring current transformers and the secondary winding three-phase transformer outputs to the second inputs of the single-phase inverters, introduced additional unit of an Autonomous inverter-unit calculation of active and reactive power, the power calculation of the variable component of active and reactive power calculation module of the set values of the currents, the control unit of the Autonomous inverter voltage and current transformer for an Autonomous inverter voltage, the first inputs of the computing unit of active and reactive power is connected to the secondary windings of single-phase transformers current is, and the second inputs to the secondary windings of three-phase measuring voltage transformer and to the first inputs of the computing unit of the set values of the currents, the outputs of the rectifier are connected with the first inputs of the unit offline voltage source inverters whose outputs are connected to the load through the primary winding of current transformer Autonomous voltage inverter, the secondary windings are connected to first inputs of the control unit of the Autonomous inverter voltage, and outputs a control unit offline voltage source inverters connected to the second input unit of the Autonomous inverter-the outputs of the computing unit of active and reactive power through the power calculation of the variable component of active and reactive power is connected to the second inputs of the computing unit set values currents, the outputs of which are connected with the second inputs of the control unit of the Autonomous voltage source inverters.
Introduction in the well-known three-phase reactive power compensator, which compensates the reactive power due to the balancing and modifying the amplitude of the output voltage, a range of new elements, which is the compensator of reactive power due to the approximation of the phase current to voltage, and obtaining a sinusoidal current [3], allows to fully compensate p is the active power, i.e. to implement not only the balancing and modifying the amplitude of the output voltage with the simultaneous approximation of the phase current to voltage and receiving a sinusoidal current, but also to form sinusoidal mains voltage.
This is due to the following. The approach phase power supply to the network is due to the capacitive component of the current compensator. This component of current is equal but opposite to the inductive load current direction, compensates the reactive component of current consumption. This leads to an increase cos ϕ and reduction of the reactive power of the fundamental frequency. The second component of the current compensator reduces to zero all higher harmonic components of current consumption, defining its shape. This is achieved by the selection signal of a current consumption of all its higher harmonic components and their full compensation due to the current compensator. Getting through this sinusoidal input current causes a reduction of reactive power distortion.
Reactive power compensation of the distortion leads to a decrease attributed to harmonic currents flowing through the reactance network, resulting in a reduction of the ripple voltage and the improvement of its sinusoidal shape. Str is Ksenia forms mains voltage leads to a full compensation of reactive power.
Thus, the addition of known devices for reactive power compensation other known device has resulted in not only the technical results inherent in each of them, but the emergence of non-obvious result, namely obtaining sinusoidal mains voltage while maintaining its symmetry and the possibility of changes in the amplitude of the output voltage, allowing fully compensate reactive power.
The drawing shows a diagram of three-phase reactive power compensator.
Three-phase reactive power compensator includes a three-phase transformer 1, three single-phase inverter 2, 3, 4 with 5, 6, 7, a rectifier 8, three-phase current transformer 9, 10, 11, three-phase measuring voltage transformer 12, the three-phase reactive current sensor 13, 14, 15, three sensor voltages 16, 17, 18, the load 19, the three comparison element 20, 21, 22, block Autonomous inverter 23, the computing unit active and reactive power 24, the computing unit of the variable component of active and reactive power 25, the computing unit of the set values of the currents 26, the control unit offline voltage source inverters 27 and measuring current transformers offline voltage source inverters 28, 29, 30.
Secondary winding three-phase transformer is 1 are connected in series with the primary windings of single-phase measuring current transformers 9, 10, 11 and connected between the network and the load 19. The primary winding three-phase transformer 1 is connected to the outputs of single-phase inverters 2, 3, 4. The secondary winding of the single phase measuring current transformers 9, 10, 11 are connected to first inputs of the computing unit of active and reactive power 24th and current inputs single-phase reactive current sensors 13, 14, 15. The output voltage of single-phase reactive current sensors 13, 14, 15 is connected to the second inputs of the computing unit of active and reactive power 24 to the first inputs of the computing unit of the set values of the currents 26 to the two respective phases of the secondary winding of three-phase measuring voltage transformer 12. The primary winding of the measuring voltage transformer 12 is connected to the mains. The outputs of single-phase reactive current sensors 13, 14, 15 are connected with the first inputs of the respective control systems 5, 6, 7. The first inputs of the elements of comparison, 20, 21, 22 through the voltage sensors 16, 17, 18 are connected to the phases of the load 19, the second inputs to the source of the setpoint voltage (not shown). The outputs of the elements of comparison, 20, 21, 22 are connected with the second inputs of the respective control systems 5, 6, 7. The third inputs of the control systems 5, 6, 7 are connected to the network. Each output control systems 5, 6, 7 is connected to the first inputs of the respective single-phase inverters 2, 3, 4. The inputs in the of prameela 8 is connected to the connection point of the primary windings of single-phase measuring current transformers 9, 10, 11 and the secondary winding three-phase transformer 1, and it outputs to the second inputs of the single-phase inverters 2, 3, 4 and to the first inputs of the Autonomous unit of the inverter 23. The outputs of the Autonomous unit of the inverter 23 is connected to the load 19 through the primary winding of current transformer Autonomous voltage inverter 28, 29, 30. The secondary winding of current transformer Autonomous voltage inverter 28, 29, 30 are connected with the first inputs of the control unit of the Autonomous inverter voltage 27. The output control unit Autonomous inverter 27 is connected to the second inputs of the Autonomous unit of the inverter 23. The outputs of the computing unit of active and reactive power 24 through the block of calculation of the variable component of active and reactive power 25 is connected to the second inputs of the computing unit of the set values of the currents 26, the outputs of which are connected with the second inputs of the control unit of the Autonomous voltage source inverters 27.
The Autonomous unit of the inverter 23 is made on the basis of fully managed IGBT transistors in the power calculation of active and reactive power 24 used a voltage multiplier products series C PS5, performing the functions of multiplication and division voltages. In the control unit of the Autonomous voltage source inverters 27 implemented algorithm δ -is odulele. Other units have a known model structure.
When the device is compensation blocks 1-22 and their correlation function of reactive power compensation due to the balancing and modifying the amplitude of the output voltage. Blocks 23-30 and their correlation function of reactive power compensation due to the approximation of the phase current to voltage and current approaches the sinusoidal form.
Three-phase reactive power compensator is as follows.
The signals of the phase currents and voltages from the output of the phase measuring current transformers 9, 10, 11 and three-phase measuring voltage transformer 12 serves to corresponding inputs of a single-phase reactive current sensors 13, 14, 15. The values of these signals at the output of the reactive current sensors 13, 14, 15 are formed of a voltage proportional to the reactive current. These signals are received at the first inputs of the respective control systems 5, 6, 7. Each voltage sensor 16, 17, 18 generates a voltage signal of the load 19, which by means of the elements of comparison, 20, 21, 22 is compared with a preset voltage, for example par. The difference between the two signals output from the elements of comparison, 20, 21, 22 is fed to each second input of the control systems 5, 6, 7. Single-phase inverters 2, 3, 4 form a voltage supplied to the secondary exchange rate is TCA three-phase transformer 1. These stresses are determined by the magnitude of the reactive current and voltage deviation load from the specified level. With the help of the rectifier 8 is powered by the DC voltage of single-phase inverters 2, 3, 4.
The output voltage of the compensator, for example phase A U2ais formed from the voltage U1avoltage δ Ufa·ejasingle-phase inverter 2. Voltage of the inverter 2 is adjusted in amplitude by changing the duty cycle δ its output pulses and phase by changing its angle control α . Using primary and secondary phase windings of a three-phase transformer 1 output voltage single-phase inverter 2 is added to the supply voltage. The amplitude and phase of the voltage vector U2acan be adjusted by changing δ and α . Changing the duty cycle of pulses δ depending on the magnitude of the reactive current, and angle adjustment α - deviation of the load voltage.
When the consumption of the reactive power compensator output single-phase sensor reactive current is supplied to the first control input of the control system single-phase inverter. Depending on the magnitude of the reactive current is increase (decrease) duty cycle δ single-phase voltage inverter. Thus is Uwe is ikenie (decrease) angle between the voltage U 1aand the load voltage U2a. When this voltage sensor 16 monitors the load voltage phase A U2aand sends a feedback signal to the comparison element 20. This signal is compared with a signal proportional to the specified mains voltage. The difference of these signals is supplied to the second control input of the control system 5. Depending on the magnitude of this signal changes the angle control valves α single-phase inverter 2. As a result of this control vector voltage single-phase inverter 2 has a magnitude and phase that the vector network voltage U2ais the radius of a given circle. The process of reactive power compensation by changing the voltage in the other two phases is similar. Such voltage regulation ensures the balancing of the magnitude and phase of the three-phase output voltage.
The signal load current output single-phase measuring current transformers 9, 10, 11 are received at the first input of the computing unit of active and reactive power 24. The signal voltage three-phase network output three-phase measuring voltage transformer 12 receives the second input of the computing unit of active and reactive power 24. The values of these signals are calculated values of active and reactive power. In the loc calculation of the variable component of active and reactive power 25 is the selection of the values of the higher harmonic active and reactive power. At the output of the computing unit of the variable component of active and reactive power 25, a signal is generated that is proportional to the higher harmonic components of active and reactive power. The values of these signals, as well as the values of phase voltages in the computing unit of the set values of the currents 26 are formed signals of the set values of the currents of the compensator. These currents are determined by the variable component of the active and reactive power three-phase load 19, and the values of phase voltages of three-phase network. The signals of the current and preset values of phase currents are compared in the control unit of the Autonomous voltage source inverters 27, where depending on the ratio of these signals is the management unit of the Autonomous inverter voltage 23. The management of this unit lies in the formation of the phase currents, which, flowing out of phase with the inductive component of the load current current offset variables in the active and reactive power. Due to this is an approximation of the phase current to the supply voltage, and obtaining sinusoidal input current. So is the compensation of reactive power by improving current shape.
Compensation in the form of a current consumption of higher harmonic components leads to the decrease of the voltage drop across with is rotellini network, caused by the flow through it of higher harmonics current. Reduce high-frequency ripple voltage drop causes a reduction of higher harmonics voltage in the form of the mains voltage. So, by improving sinusoidally current is to improve the shape of the mains voltage.
Thus, there is full compensation of reactive power by improving the shape of the mains voltage while improving the shape of current consumption, as well as preserve the symmetry and magnitude of the voltage at the load.
Three-phase reactive power compensator is installed in the locomotive depot Belogorsk Transbaikalian VC. road. The application of this compensator has allowed to increase the power factor of the enterprise, comprised of 0.6-0.7, 0.15-0,17. Increasing this efficiency resulted in a reduction in operating costs by 4-5%.
Sources of information
1. Brooms, VA and other voltage control in electrical systems. - M.: Energoatomizdat, 1985.
2. A.S. No. 2027278. Three-phase reactive power compensator. The authors of this invention Klimash B.C., Symonenko I.G. Publ. in BI No. 2 1995 MCI H 02 J 3/18.
3. Naked, A.Nabae and S.Aton. Control Strategy of Active Power Filters Using Multiple Voltage-Source PWM Converters. IEEE Transactions on Industry Applications, Vol. IA-22, No. 3, May/June 1986.
Three-phase reactive power compensator containing t is expasy transformer, three-phase inverter control systems, rectifier, three-phase current transformer, three-phase measuring voltage transformer, three-phase reactive current sensors, three sensor voltages, three comparison element and the load, and the secondary winding three-phase transformer are connected in series with the primary windings of single-phase transformers of current and included between the network and the load, the primary winding three-phase transformer connected to the outputs of single-phase inverters, single-phase secondary winding of current transformer connected to current inputs single-phase reactive current sensors, voltage inputs are connected to two respective phases of the secondary winding of three-phase measuring voltage transformer, the primary winding which is connected to the network, the outputs of single-phase reactive current sensors connected to the first inputs of the respective control systems, the input elements of comparison across the voltage sensors connected to the phases of the load, and the second inputs to the source of the setpoint voltage, the outputs of the elements of comparison associated with the second inputs of the respective control systems, third inputs of control systems connected to the network, and the outputs from the first inputs to meet the existing single-phase inverters, the inputs of the rectifier is connected to the connection point of the primary windings of single-phase measuring current transformers and three-phase secondary windings of the transformer and outputs to the second inputs of the single-phase inverters, characterized in that it introduced additional unit of an Autonomous inverter-unit calculation of active and reactive power, the power calculation of the variable component of active and reactive power calculation module of the set values of the currents, the control unit of the Autonomous inverter voltage and current transformer for an Autonomous inverter voltage, the first inputs of the computing unit of active and reactive power is connected to the secondary windings of single-phase transformers current, a second input to the secondary windings three-phase measuring voltage transformer and to the first inputs of the computing unit of the set values of the currents, the outputs of the rectifier are connected with the first inputs of the unit offline voltage source inverters whose outputs are connected to the load through the primary winding of current transformer Autonomous voltage inverter, the secondary windings are connected to first inputs of the control unit of the Autonomous inverter voltage, and outputs a control unit offline voltage source inverters connected to storieskagome block Autonomous inverter - the outputs of the computing unit active and reactive power through the power calculation of the variable component of active and reactive power is connected to the second inputs of the computing unit of the set values of the currents, the outputs of which are connected with the second inputs of the control unit of the Autonomous voltage source inverters.