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DEVICES AND METHODS OF ECONOMY AND PRESERVATION OF ELECTRICITY
INVENTION
Patent of the Russian Federation RU2232085

DEVICE FOR AUTOMATIC REGULATION OF REACTIVE POWER

DEVICE FOR AUTOMATIC REGULATION OF REACTIVE POWER

The name of the inventor: Rabinovich MD (RU); Donskoy A.L. (RU); Kondratenko A.N. (RU); Krivnoy A.M. (RU); Litovchenko V.V.
The name of the patent holder: OOO "ZHELDORKONSALTING" (RU)
Address for correspondence: 129626, Moscow, ul. 3-ya Mytischinskaya str., 10, p.8, OOO "ZHELDORKONSALTING"
The effective date of the patent: 2002.08.27

The invention relates to electrical engineering and can be used on an AC-powered AC motor with thyristor converters. The device comprises a traction transformer with a load connected to its secondary winding, the primary winding of which is connected to the supply network, a reactive power source, a network mode sensor, a synchronizing pulse unit, a control unit and a pulse-phase control unit, two integrators and a multiplier. The reactive power source is connected to the secondary winding of the traction transformer and consists of two LC-chains, each of which is formed by inductively connected inductance, capacitance and a key element made in the form of counter-parallelly connected thyristors. The device is equipped with a control unit whose output is connected to the second input of the pulse-phase control unit connected by its outputs to the thyristors of the key elements of the reactive power source and the two integrators. The first integrator with its input is connected to the output of the voltage transformer, and the output to the first input of the multiplier, the second input of which is connected to the output of the current transformer. The second integrator is connected by its inputs, one to the output of the multiplier and the other to the output of the clock pulse block, respectively, and the output is connected to the second input of the control unit. The technical result of the invention is the compensation of reactive power with any form of rod feed voltage.

DESCRIPTION OF THE INVENTION

(EN) The invention relates to electrical engineering and is intended to increase the power factor of consumers, in particular an AC rolling stock with thyristor converters.

One of the disadvantages of AC electric locomotives currently operating with smooth voltage regulation is a low power factor. The power factor is one of the main energy indicators of an electric locomotive, which determines its consumption of reactive power. The operation of an electric locomotive with a low power factor leads to significant energy losses. To increase the power factor, compensating installations are used in the form of LC-circuits located on an electric locomotive and connected directly to the secondary winding of its traction transformer. The compensating device increases the power factor by creating a capacitive load and shifting the primary current of the electric locomotive in the direction of advancing the supply voltage.

A device is known for controlling a compensated rectifier-inverter converter of an electric rolling stock [1], which compensates for the reactive power consumed by the load from the power source. Compensation is achieved by connecting an inductive capacitive LC compensator to the secondary winding of the electric locomotive transformer with fixed inductance and capacitance parameters. With an inductive load, this causes the appearance of a capacitive current component that compensates for the inductive component. In this case, the phase of the consumed current approaches the supply voltage, contributing to an increase in the power factor of the electric locomotive.

The device comprises a traction transformer, a load, an LC compensator, a key element, a key element generation device, a trigger trigger, an AND element, a pulse generator, a network voltage sensor, a protection unit, a command unit.

The LC-compensator through the key element is connected in parallel with the load and secondary winding of the traction voltage transformer, the primary winding of which is connected to the mains. The first input of the AND element is connected to the output of the network voltage sensor whose input is connected to the network. The protection unit is connected to the second input of the AND element, whose output is connected to the input R of the trigger of the trigger. The inputs of the pulse driver are connected to the capacitor of the compensator and the secondary winding of the transformer, and the output is connected to the input C of the trigger trigger, the output of which is connected via the key element control pulse generator to the control input of the key element, the command block is connected to the trigger input D of the trigger.

The function of the key element is to enable and disable the LC-compensator. In this case, the key element is made in the form of two counter-parallelly connected thyristors. The thyristors are switched on by the signal from the trigger output triggered through the control pulse shaping device. The trigger input C of the trigger triggers a signal from the output of the pulse generator, which is generated at the time of equal voltage on the capacitor of the compensator and the secondary winding of the voltage transformer. The signal at the output of the trigger is generated after the command signal is input to its input D. In this case, the appearance of the voltage at the output of the flip-flop coincides with the closest moment of equality of the voltages on the capacitor and the transformer.

Closing of the thyristors of the key element occurs either in case of exceeding the permissible voltage in the network, or when the protection is activated. The trip signals are formed respectively by the network voltage sensor and the protection unit. If there is at least one of these signals at the input of the AND element, a signal appears on its input to the R input of the trigger trigger. This signal leads to the formation of a signal at the output of the flip-flop to close the thyristors of the key element.

Thus, through the key element, the LC-compensator is permanently connected to the load, with the main purpose of the control units being to prevent overcurrents, when connecting the LC-compensator to the secondary winding voltage of the transformer and providing high-speed protection. The converter is protected by removing the control pulses from the thyristors in the event of dangerous currents and voltages.

Tests of the reactive power compensation device on the locomotive VL85 [2] showed that the average value of the power factor of the locomotive rises to 0.92 and provides almost a twofold reduction in the consumption of reactive energy for the traction of trains.

However, the use of an LC compensator with a constant compensation current increases the power factor of an electric locomotive only at certain (nominal) load currents. The deviation of the electric locomotive load from the nominal results in incomplete compensation of the reactive power, which reduces the efficiency of the device application.

The device [3] is also known, which makes it possible to partially eliminate this deficiency.

The device comprises a traction transformer, a load in which the rectifier-inverter converter is used, a reactive power source consisting of two LC compensators, each of which is formed by a series connection of inductance and capacitance, two key elements executed each in the form of two counter-parallel connected Thyristors, and a control device for key elements.

Compensation for reactive power is realized when these LC-compensators are connected in parallel with the secondary winding of the traction transformer.

The tests of the reactive power compensation device on the electric train ER29 [4] showed that with load currents exceeding 0.5 of the nominal value, the power factor exceeds 0.97. However, with load currents less than 0.5 of the rated value, there is a significant overcompensation and a decrease in the power indicators of the electric train.

It is also known a device for automatic control of reactive power [5], which allows changing the current of the compensator by controlling the opening angle of the thyristors. In this case, the angle of opening of thyristors is determined by the phase angle of the shift between the main harmonics of the mains current and voltage. The compensator current is regulated in such a way as to ensure a minimum phase shift between the current consumed and the mains voltage. This makes it possible to increase the power factor of an electric locomotive at various load currents.

The device for automatic control of reactive power contains a load connected through a traction transformer to the mains supply, a reactive power source, a network mode sensor, a synchronizing pulse unit, a control unit and a pulse-phase control unit. The load is a thyristor converter. The reactive power source consists of a series-connected inductance, capacitance and two counter-parallelly connected thyristors. The network mode sensor includes a voltage transformer and a current transformer. The traction transformer is connected to the mains via a current transformer. The voltage transformer is connected in parallel to the supply network, its output is connected to the input of the synchronizing pulse unit, the output of which is connected to the first inputs of the control unit and the pulse-phase control unit. The output of the current transformer is connected to the second input of the control unit. The output of the control unit is connected to the second input of the pulse-phase control unit. The output of the pulse-phase control unit is connected to the thyristors of the reactive power source.

Compensation for reactive power occurs due to the creation of a capacitive component of the load current, which is carried out with the help of a reactive power source. The magnitude of this current is determined by the opening angle of the thyristors entering the reactive power source.

The load power factor is measured by the magnitude of the phase angle of the shift between the current and the voltage of the supply network. Such a measurement method is realized with the help of a reactive power sensor, a control unit and a pulse-phase control unit. At the output of the control unit, a voltage proportional to the load power factor is generated. With the help of this voltage and the synchronization voltage pulses arriving at the inputs of the pulse-phase control unit, the voltage is converted into a phase for controlling the thyristors of the reactive power source.

When the power factor, caused by the appearance of a phase angle of shear between the mains current and the voltage, is reduced, the device automatically changes the thyristor opening phase. A change in the opening angle of the thyristors results in a change in the capacitive component of the reactive power source current flowing in antiphase with the inductive component of the current consumed by the load. This causes a decrease in the phase angle of shear between the supply voltage and the resulting load current, which leads to an increase in the load power factor. This is how the reactive power of the load is compensated in all operating modes of the electric locomotive.

However, with pulse-phase control of the inclusion of the thyristors of the compensator, the current flowing through the reactive power source becomes discontinuous, which leads to distortions in the shape of the supply current. With a distorted (nonsinusoidal) form of the supply current and voltage associated with the operation of electric locomotives with pulse converters, the power factor is determined by the ratio of the active and total powers consumed by the load. Since the active and apparent power also depend on the higher harmonic components associated with distortions in the shape of the voltage and current, the method for measuring the power factor in the shear angle between current and voltage adopted in the device causes an error in determining the power factor for the non-sinusoidal current and voltage form . This leads to incomplete compensation of reactive power. In addition, the intermittent current of the reactive power compensator degrades the power characteristics of the locomotive.

As a prototype of the invention, it is advisable to adopt a device for automatic control of reactive power, containing a load, which is a rectifier-inverter converter connected to the secondary winding of a traction transformer whose primary winding is connected to the supply network, a reactive power source connected to the secondary winding of the traction transformer , A network mode sensor including a voltage transformer and a current transformer, a synchronizing pulse unit, a control unit and a pulse-phase control unit, wherein the primary winding of the traction transformer is connected to the supply network via a current transformer of the network mode sensor and parallel to a voltage transformer whose output Connected to the input of the clock pulse unit, the output connected to the first inputs of the pulse-phase control unit and the control unit, whose output is connected to the second input of the pulse-phase control unit [5].

The disadvantage of the known is connected with incomplete compensation of reactive power, but also with intermittent current of the reactive power compensator, which worsens the spectral composition of the current of the supply network and, as a result, reduces the power parameters of the locomotive.

The technical result is full compensation of reactive power in various operating modes of an electric locomotive at any (sinusoidal and non-sinusoidal) forms of supply voltage and current.

The essential distinctive features of the proposed device are that two integrators and a multiplier are additionally introduced, wherein the first integrator is connected by its input to the output of the voltage transformer, and the output to the first input of the multiplier whose second input is connected to the output of the current transformer, and the second integrator is connected by its One input to the output of the multiplier and the other to the output of the clock block respectively, and the output is connected to the second input of the control unit, and the reactive power source is made up of two parallel connected LC circuits, each of which is formed by inductively coupled inductance, A key element in the form of counter-parallelly connected thyristors, the control inputs of the key elements being connected to the corresponding outputs of the pulse-phase control unit.

The introduction into the device of a set of new elements (two integrators and a multiplier) and their interrelations allow to regulate the value of the capacitive current of the reactive power source. At the same time, the consumption of reactive power from the supply network is reduced to a minimum.

This is due to the fact that the device automatically changes the circuit of switching on the LC-chains of the reactive power source and thereby the value of the capacitive current, ensuring maximum compensation of reactive power. In this case, the circuit of switching on LC-chains varies depending on the value of reactive power, which is determined by the formula [6]

Where u, i are the instantaneous values ​​of the supply current and voltage,

T is the period of the mains voltage.

Since the instantaneous values ​​of the supply current and voltage are used to determine the reactive power, this approach takes into account the higher harmonic components of the input current and voltage. On the basis of the information on the reactive power, the control unit adjusts the output signal so that the thyristor control pulses of the key elements of the reactive power source formed at the output of the pulse-phase control unit lead to the inclusion of such thyristor pairs in which the value of the reactive power is minimized. In this case, three possible circuits for connecting the LC-chains of the reactive power source to the secondary winding of the transformer are realized: first, the first LC-chain is connected; The second is connected to the second LC-chain and the third - two LC-chains are connected.

Adjustment of the capacitive current value of the reactive power source allows to compensate the reactive power, both with sinusoidal and non-sinusoidal current and voltage forms, and with different operating modes of the electric locomotive.

The figure shows the device for automatic control of reactive power.

DEVICE FOR AUTOMATIC REGULATION OF REACTIVE POWER

The device for automatic reactive power control contains a load 1 connected to the secondary of the traction transformer 2, a reactive power source 3 consisting of two LC chains 4 and 5 and key elements 6 and 7, a network mode sensor 8, a clock pulse unit 9, a unit 10, two integrators 11 and 12, a multiplier 13, and a pulse-phase control unit 14.

Each LC-chain is formed by inductively connected inductance and capacitance in series, 15, 16 - the first 4 and 17, 18 - the second 5. The key elements are made in the form of counter-parallelly connected thyristors: 19, 20 - the first 6; 21, 22 - second 7. The network mode sensor 8 includes a voltage transformer 23 and a current transformer 24.

The key elements 6 and 7 are connected in series with the corresponding LC circuit and are connected to the secondary winding of the transformer 2. The primary winding of the traction transformer 2 is connected to the supply network via the current transformer 24 and parallel to the voltage transformer 23. The output of the voltage transformer 24 is connected to the input of the clock pulse unit 9 And to the input of the first integrator 11. The output of the integrator 11 is connected to the first input of the multiplier 13 whose second input is connected to the output of the current transformer 24. The second integrator 12 is connected by one input to the output of said multiplier 13 and another input to the output of the clock pulse unit 9, To the second input of the control unit 10. The first input of the control unit 10 is connected to the output of the clock pulse unit 9 and the output to the second input of the pulse-phase control unit 14 connected by its outputs to the thyristors of the key elements 6 and 7. The first input of the pulse- Phase control 14 is connected to the output of the synchronizing pulse unit 9.

DEVICE WORKS AS FOLLOWING

When feeding load 1 from transformer 2, the voltage and current of its primary winding have a non-sinusoidal shape, and the current is shifted in phase from the voltage to the side of the lag, which is due to the inductive nature of the load, and the phase regulation of the voltage on it. At the output of voltage transformers 23 and current 24, a voltage proportional to the instantaneous value of the supply voltage and the current consumed is formed. With the help of the integrator 11, a signal proportional to the integral of the supply voltage is determined, and in the multiplier 13, the output of the integrator 11 and the instantaneous current from the current transformer 24 is multiplied. Integration of the signal fed to the first input of the integrator 12 allows determining the reactive power in accordance With the given formula.

For this purpose, a pulse is received at the first input of the control unit, obtained by the synchronizing pulse block 9 from the mains supply voltage. In this case, the synchronizing pulses correspond to the period T of the mains voltage. At the moment of receipt of the synchronizing pulses, the signal of the reactive power at the output of the integrator 12 is fixed to the control unit 10 and the integrator 12 is reset by the same pulses. Thus, information about the reactive power at the input of the control unit is constantly updated. Depending on the magnitude of the reactive power, a signal appears at the output of the control unit to activate a pair of thyristors of the corresponding reactive power source key element.

For example, if the magnitude of the reactive power is positive, then the signal at the output of the control unit allows the first key element 6 (thyristors 19 and 20) to be switched on and the pulse-phase control unit provides the pulses for switching on these thyristors. This connection corresponds to the minimum value of the capacitive current and provides compensation of the corresponding reactive power.

If the value of the capacitive current is insufficient to completely compensate the reactive power, as indicated by the positive value of the signal at the output of the integrator 13, the signal at the output of the control unit permits the inclusion of the second key element 7 (thyristors 21 and 22) and the pulse- On the inclusion of these thyristors. With the thyristors 21 and 22 turned on, only the second LC circuit 5 is connected to the transformer 2's winding. When capacitor 18 is selected, the capacitor 16 will be larger than the capacity of the capacitor 16, resulting in a corresponding increase in the capacitive current.

The largest value of the capacitive current and the corresponding reactive power is achieved with simultaneous inclusion of the first 6 and second 7 key elements (thyristors 19, 20 and 21, 22). With this switching on, two LC circuits are connected to the transformer 2 winding.

If the value of the capacitive current is greater than necessary to completely compensate the reactive power when the load changes, as indicated by the negative value of the signal at the output of the integrator 13, the signal at the output of the control unit permits the inclusion of such a pair of thyristors at which the value of the capacitive current decreases. In this case, the switching of the thyristors of the key elements to reduce the value of the capacitive current is carried out in the reverse order.

Thus, using the principle of regulation for reactive power, it is possible to maximally compensate the reactive power of the load in various operating modes of an electric locomotive with both sinusoidal and distorted forms of mains voltage and current.

The technical and economic efficiency of the proposal is determined by the fact that when using it the reactive power consumed from the power supply is minimized, and accordingly the power factor is increased. The results of testing the device for automatic reactive power control showed that the power factor of an electric locomotive throughout the range of load changes increased to 0.95, which in turn led to a 5% reduction in electricity consumption.

INFORMATION SOURCES

1. Ac. 1468791. A device for controlling a compensated rectifier-inverter converter of an electric rolling stock. The inventors of V.A. Kuchumov, V.A. Tatarnikov, N.N. Shirochenko, Z.G. Bibineishvili. - Opubl. In BI No. 12, 1989, cl. At 60 L of 9/12.

2. N.N. Shirochenko, V.A. Tatarnikov, ZG. Bibineishvili. Improving the power of AC electric locomotives. - Railway transport, 1988, №7, p. 33.

3. B.I. Khomyakov, S.I. Merkushev, ON Nazarov, etc. Experienced electric train ER29 AC. Results of traction-energy tests. - Electric and diesel traction. 1991. № 12, p. 12-16.

4. S.I. Merkushev, B.I. Khomyakov, O.N. Nazarov. Power indicators of converters of the experimental electric train ER29 of alternating current. / Perfection of electric equipment for electric trains and high-voltage equipment of passenger cars: сб.научн.тр. / Under the editorship of. G.G. Homilies. - Moscow: Transport, 1993. - 128 pp. / P. 27-36.

5. Ac. 1674306. Device for automatic control of reactive power. The authors of the invention A.S. Kopanev, B.M. Naumov, I.K. Yurchenko. - Opubl. In the BI № 32, 1991, cl. H 02 J 3/18.

6. D.E. Kadomsky. Active and reactive power - the characteristic of the average values ​​of the work and energy of the periodic electromagnetic field in the elements of nonlinear circuits. Electricity. No. 7, 1987. p. 39-43.

CLAIM

Device for automatic control of reactive power, containing a load, which is a rectifier-inverter converter connected to the secondary winding of a traction transformer whose primary winding is connected to the supply network, a reactive power source connected to the secondary winding of the traction transformer, a network mode sensor comprising A voltage transformer and a current transformer, a synchronizing pulse unit, a control unit and a pulse-phase control unit, wherein the primary winding of the traction transformer is connected to the supply network via a current transformer of the network mode sensor and parallel to a voltage transformer whose output is connected to the input of a clock pulse unit , An output connected to the first inputs of the pulse-phase control unit and the control unit, the output of which is connected to the second input of the pulse-phase control unit, characterized in that two integrators and a multiplier are additionally inserted into it, wherein the first integrator is connected by its input to the output of the transformer Voltage, and the output to the first input of the multiplier whose second input is connected to the output of the current transformer, and the second integrator is connected by its inputs, one to the output of the multiplier and the other to the output of the clock block respectively, and the output is connected to the second input of the control unit, And the reactive power source is made in the form of two LC circuits connected in parallel, each of which is formed by inductively connected inductance, capacitance and a key element in the form of counter-parallelly connected thyristors, the control inputs of the key elements being connected to the corresponding outputs of the pulse-phase control unit .

print version
Published on February 15, 2007