Reactive power correcting device

IPC classes for russian patent Reactive power correcting device (RU 2256994):

H02J3/18 - Arrangements for adjusting, eliminating, or compensating reactive power in networks (for adjustment of voltage H02J0003120000; use of Petersen coils H02H0009080000)

B60L9/12 - with static converters

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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

The invention relates to electrical engineering and is intended to improve the power factor of consumers, in particular electric rolling stock AC with semiconductor converters.

One of the drawbacks of currently operating locomotives AC stepless voltage regulation is poor power factor, reaching at best 0,84. The power factor is one of the main energy indicators locomotive, determining the consumption of reactive power. The work of a locomotive with a low power factor leads to significant energy losses.

To improve the power factor applied compensating installation in the form of LC-circuits located on the locomotive and connected directly to the secondary winding it of traction transformer. The compensating device increases the power factor by creating a capacitive load and displacement of the primary current of the locomotive in the direction of advance of the supply voltage.

A device for compensation of reactive power rectifier-inverter electric rolling stock [1], which compensates for the reactive power consumed by the load from the power source. Compensation at the expense of the English connections to the secondary winding of the transformer locomotive inductive-capacitive LC compensator with fixed parameters of inductance and capacitance.

The device comprises a traction transformer, load, LC compensator, a key element, the forming device control pulses a key element. LC compensator through the key element is connected in parallel with the load and the secondary winding of the traction transformer, the primary winding of which is connected with the mains supply. Function key item is to enable or disable LC compensator. When this key element is designed in the form of two anti-parallel connected thyristors. Through the key element LC compensator permanently connected to the load. Testing devices for reactive power compensation in electric WL [2] showed that the average value of the power factor of the locomotive increases to 0.92 and provides almost double the reduction in the consumption of reactive energy for traction of trains.

However, the application of LC-compensator with constant current compensation improves the power factor of the locomotive only under certain (nominal) load currents. The load deflection of the locomotive from the nominal causes incomplete compensation of reactive power, which reduces the effectiveness of the device.

It is also known device [3], allowing to partially eliminate this disadvantage.

The device comprises a traction transformer, the load in cachelocatio used rectifier-inverter Converter, the source of reactive power, consisting of two LC-compensators, each of which is formed by the serial connection of the inductance and capacitance, two key elements, each made in the form of two anti-parallel connected thyristors. Reactive power compensation is performed by connecting the specified LC-joints parallel to the secondary winding of the traction transformer.

Testing devices for reactive power compensation on the train AR [4] showed that when the load currents in excess of 0.5 of the nominal value, the power factor exceeds 0,97. However, when load currents less than 0.5 of the nominal value, there is a significant overcompensation and the decrease in the energy parameters of the train.

As a prototype of the invention it is advisable to take the device for compensation of reactive power, containing the traction transformer, load, made in the form of a rectifier of the inverter locomotive connected to the traction motor and connected to their inputs with the conclusions of the secondary winding of the traction transformer, two sources of reactive power - first and second, each of which is formed of series-connected inductance and capacitance, the sensor network mode, which includes the voltage sensor and the current sensor, the controller can control the means and the switch, connected by their outputs with the conclusions of the secondary winding of the traction transformer and entrances: one from the output of the control unit and the other - with the specified reactive power sources, with the primary winding of the traction transformer connected to the mains supply via a current sensor, voltage sensor is in parallel with the mains supply, the outputs of the sensor network mode connected to respective inputs of the control unit [5].

The disadvantage is the occurrence of surge currents when connecting the switch of the source of reactive power to the secondary winding of the transformer in case of no compliance voltage winding of the transformer and the capacitor reactive power sources. Moreover, the emergence of surge currents affects the waveform of the current supply network and reduces the power factor of a locomotive.

The technical result is the total compensation of reactive power in various modes of operation of the locomotive at any (sinusoidal and non-sinusoidal) voltage and current.

Significant features of the proposal are that additionally introduced two key elements, the first and second, each of which contains a thyristor key, consisting of two anti-parallel connected thyristors, the sensor voltage thyristors and for irovel pulse control thyristor key, and voltage sensor connected in parallel to the thyristor, and the output is connected to the first input of the shaper of control pulses connected to its output with the control input of the thyristor key, and two resistors, with thyristor key of the first key element is connected in series with the first source of reactive power thyristor key second - consistently with the second source of reactive power, a second input shapers of the control pulses of the first and second key elements are connected with the output of the control unit, and additional resistors are included: one is the parallel capacitance of the first source of reactive power and the second parallel capacitance of the second source of reactive power.

Introduction in the device array of new elements (two key elements, each of which contains a thyristor key, the sensor voltage and the driver control pulses, and two resistors) and their relationship allows us to eliminate shock currents when switching sources of reactive power and regulate the amount of reactive power without distorting the shape of the curve consumed from the network current shock currents. While the consumption of reactive power from the mains is reduced to a minimum.

This is because the device changes the wiring of the sources of reactive the th power to windings of the traction transformer and thereby the amount of reactive power, for each source is determined by the formula:

where ω is the angular frequency of the mains voltage,

With_1,2the capacitance of the capacitor, respectively, the first, the second source of reactive power,

U_1,2- the RMS voltage on the first capacitor, a second source of reactive power.

The resulting value of the reactive power device is defined as the number of reactive power sources are connected to the windings of the transformer, and the voltage at these windings. Source switching is performed by the contactors of the switch, and their unstressed connection key elements for the signals of the control unit. The signal control unit is formed on the basis of the information on the amount of reactive power is determined by the instantaneous values of current and voltage of the mains, thus, to minimize the amount of reactive power of a locomotive.

The drawing shows a diagram of an apparatus for reactive power compensation.

Device for compensation of reactive power provides traction transformer 1, load 2, in the form of a rectifier of the Converter 3 connected to the traction motor 4, the first 5 and second 6 sources of reactive power, the sensor network mode 7, including ina voltage sensor 8 and the current sensor 9, the control unit 10, a switch 11 and two key elements - the first 12 and second 13. The first source of reactive power 5 consists of a series connected inductance 14 and tank 15, the second source of reactive power 6 consists of a series connected inductance 16 and the vessel 17. The first key element 12 includes a thyristor switch - two anti-parallel connected thyristors 18 and 19, the voltage sensor 20 and the driver control pulses 21. The second key element 13 includes a thyristor switch - two anti-parallel connected thyristors 22 and 23, the voltage sensor 24 and the driver control pulses 25.

Additional resistors 26 and 27 connected in parallel to the tanks 15 and 17 of the first and second sources of reactive power, respectively.

The load 2 is connected to the terminal of the secondary winding of the traction transformer 1, the primary winding of which is connected to the mains supply via the current sensor 9, the voltage detector 8 is in parallel with the mains. The outputs of the sensor network mode 7 is connected to the corresponding inputs of the control unit 10. The switch 11 is connected by its outputs with the conclusions of the secondary winding of the traction transformer 1. One input of switch 11 is connected to the output of the control unit 10. The reactive power sources 5 and 6 are connected in series with the thyristor keys 18, 19 and 2, 23 key elements 12 and 13 respectively and are connected to other inputs of the switch 11. The voltage sensors 20 and 24 connected in parallel to the thyristor 18, 19 and 22, 23 respectively. The outputs of the voltage sensors 20 and 24 are connected with the first inputs of the pulse shapers 21 and 25, the outputs of which are connected to control inputs of the thyristor keys 18,19 and 22, 23 respectively. Second input shapers pulses 21 and 25 are connected to the output of the control unit 10.

The proposed device operates as follows.

When the power to the load 2 from the transformer 1 voltage and current of the primary winding are not sinusoidal, and the current shifted in phase from the voltage-to-side lag, due to the inductive nature of the load. These current and voltage are measured by the sensors 8 and 9 and are fed to the control unit 10, which determines the magnitude of the reactive power and a signal is generated at the switching of the contactors of the switch 11 and the connection corresponding, for example, the first source of reactive power to the selected secondary winding of the transformer 1. Simultaneously, the signal from the block 10 is supplied to the second input of the shaper 21. Direct connection of the source of reactive power will occur when turning on the thyristor key 18,19 by feeding on its control input pulse from the output of the shaper 21. For this the first input of the shaper 21 to receive the signal from the voltage detector 20 on the “zero” voltage on thyristor key 18,19. The presence of such a signal indicates equality of the instantaneous values of voltage on the selected secondary winding of the transformer and the capacitance of the source of reactive power, which eliminates the occurrence of surge currents when connecting the source of reactive power. Since the switching of the source of reactive power can be supplied from a transformer with a higher voltage to the coil with a lower voltage to reduce the voltage on the tank 15 is provided by the resistance 26, through which there is a discharge capacity of 15.

Similarly operates the switching device of the second source of reactive power.

The presence of two sources of reactive power, switch, and two key elements allows you to adjust the amount of reactive power source and compensate reactive power load in different modes of operation with sinusoidal and distorted form of network voltage and current.

Technical and economic efficiency of the proposal is determined by the fact that when using it minimizes the reactive power consumed from the power source, and accordingly increases the power factor. The results of the test devices for reactive power compensation showed that the power factor of the locomotive around diazoketone loads increased to 0.95, that in turn led to the reduction of energy consumption by 5%.

Sources of information

1. A.S. 1468791. Device to control the compensated rectifier-inverter inverter electric rolling stock. The authors of this invention Wasukuma, Washaterias, Yea, Schubiner. - Publ. in BI No. 12, 1989, CL 60 L 9/12.

2. Yea, Washaterias, Schubiner. Improvement in energy AC locomotives. - Railroad transport, 1988, No. 7, p.33.

3. Bijomaru, Sierkowski, Onnatural, etc.. Experienced train ER AC. The results of the traction power of the tests. - Electric and diesel traction. 1991. No. 12. p.12-16.

4. Sierkowski, Bijomaru, Onnatural. Energy indicators converters experienced electric OR AC. /Development of electric trains and high-voltage equipment passenger cars: sbauer./ Edited May. - M.: Transport, 1993. - S.//p.27-36.

5. Patent No. 2212086. Device for compensation of reactive power. The Authors Hummelink, Animosity. - Publ. in BI No. 25. 10.09.2003 g, class H 02 J 3/18, 60 L 9/12.

Device for compensation of reactive power, containing the traction transformer, load, made in the form of a rectifier of the inverter locomotive connected to it is a traction engine and connected to their inputs with the conclusions of the secondary winding of the traction transformer, two sources of reactive power, the first and second, each of which is formed of series-connected inductance and capacitance, the sensor network mode, which includes a voltage sensor and a current sensor, a control unit and a switch, connected to their outputs with the conclusions of the secondary winding of the traction transformer and entrances - one to the output of the control unit and the other - with the specified reactive power sources, with the primary winding of the traction transformer connected to the mains supply via a current sensor, voltage sensor is in parallel with the mains supply, the outputs of the sensor network mode connected to respective inputs of the control unit, wherein it additionally introduced two key elements, the first and second, each of which contains a thyristor key, consisting of two anti-parallel connected thyristors, the sensor voltage thyristors and the pulse shaper control thyristor key, and the sensor voltage thyristors connected in parallel to the thyristor, and the output is connected to the first input of the shaper of control pulses connected to its output with the control input of the thyristor key, and two resistors, with thyristor key of the first key element is connected in series with the first source of reactive power, Tiesto the hydrated key of the second consistently with the second source of reactive power, a second input shapers of the control pulses of the first and second key elements are connected with the output of the control unit, and additional resistors included one parallel capacitance of the first source of reactive power and the second parallel capacitance of the second source of reactive power.