RU75518U1 - REACTIVE POWER COMPENSATION DEVICE - Google Patents

Abstract

A device for reactive power compensation relates to electrical engineering and can be used on electromotive stock of alternating current to increase the power factor. In each half-cycle, the first (7) or second (8) diodes go into a conducting state, while the second (11) or first (10) thyristor also goes into a conducting state, since the control unit (6) supplies a control pulse to the thyristor control electrode . When the voltage passes through "zero", the voltage sensor (5) generates a signal according to which the first timer included in the control unit (6) is reset, and a constant is written to the second timer of the control unit (6). When the current passes through “zero”, the current sensor (4) generates a signal according to which the contents of the first timer of the control unit (6) are fixed, while the number recorded in this timer is proportional to the clock frequency of the control unit (6) and the phase angle of the current phase. The second timer of the control unit (6), in which the constant is written at the beginning of the half-cycle, continues to be subtracted until its contents become equal to the contents of the first timer of the control unit (6). If the values of the first and second timers are equal, the control unit (6) generates a control pulse to turn off the first (10) or second (11) thyristor. The technical result consists in increasing the power factor in the entire range of regulation and reliability of the device for reactive power compensation, 1 il.

Description

The utility model relates to electrical engineering and can be applied on electromotive stock of alternating current to increase power factor.

A device for compensating reactive power, comprising a traction transformer, a converter, a pulsating current traction motor, two reactive power sources, current and voltage sensors, a control unit, a switch (RU 2212086, class H02J 3/18, B60L 9/12, Bull. No. 25, 09/10/2003).

The disadvantage of this device is the occurrence of shock currents when the switch connects the source of reactive power to the secondary winding of the transformer in the event of a voltage mismatch on the transformer winding and on the capacitor of the reactive power source, which reduces the reliability of the device. The appearance of shock currents reduces the power factor.

A device for compensating reactive power, comprising a traction transformer, a converter, a pulsating current traction motor, two reactive power sources, a control unit, a switch, current and voltage sensors (RU 2256994, class H02J 3/18, B60L 9/12, Bull. No. 20, 07/20/2005 - prototype).

The disadvantage of the device adopted for the prototype is a discrete method of reactive power regulation with a large step of discreteness, which reduces the power factor in the entire control range, a large number of elements reduces the reliability of the device.

The objective of the utility model is to increase the reliability of a device for reactive power compensation by reducing the number of elements and eliminating the occurrence of shock currents in reactive elements, and

to increase the power factor in the entire range of regulation through the use of sector regulation in a controlled rectifier.

The technical result is achieved by the fact that in a device for compensating reactive power, containing a traction transformer, the primary winding of which is connected to the supply network, the armature winding and the excitation winding of a pulsating current traction motor, a current sensor and a voltage sensor are connected in series, their outputs are connected to the first and second the inputs of the control unit, respectively, three diodes and two two-operational thyristors are additionally introduced into it, to the free output of the anchor winding of the traction motor a pulser the anode of the first, second and third diodes and the first output of the voltage sensor, the second output of which is connected to the free output of the excitation winding of the traction motor of the pulsating current and the common output of the cathodes of the third diode, the first and second two-stage thyristors, the control electrodes of which are connected to the first and second the outputs of the control unit, respectively, the anode of the first two-stage thyristor and the cathode of the first diode are connected to the first output of the secondary winding of the traction transformer, the second the output of which is connected through a current sensor to the cathode of the second two-stage thyristor and the anode of the second diode.

The drawing shows a circuit diagram of the proposed device for reactive power compensation.

In accordance with the drawing, a device for reactive power compensation, comprising a traction transformer 1, the primary winding of which is connected to the mains, an armature winding 2 and an excitation winding 3 of a pulsating current traction motor, a current sensor 4 and a voltage sensor 5, their outputs are connected to the first and the second inputs of the control unit 6 (for example, ADAM-5510, Prosoft short product catalog 6.0, 2001, p. 47), respectively, to the free output of the anchor winding 2 of the traction motor

the pulsating current connected anodes of the first 7, second 8 and third 9 diodes and the first output of the voltage sensor 5, the second output of which is connected to the free output of the excitation winding 3 of the traction motor of the pulsating current and the common output of the cathodes of the third diode 9, the first 10 and second 11 two-operation thyristors, the control electrodes of which are connected to the first and second outputs of the control unit 6, respectively, the anode of the first two-stage thyristor 10 and the cathode of the first diode 7 are connected to the first output of the secondary winding of the traction t ansformatora 1, the second terminal of which is connected through the supply 4 to the cathode of the second thyristor dvuhoperatsionnogo sensor 11 and the anode of the second diode 8.

A device for reactive power compensation works as follows. In each half period, a polarity voltage is applied to the corresponding arm of the semi-controlled bridge, at which the first 7 or second 8 diodes go into a conductive state, while the second 11 or first 10 thyristor also goes into a conductive state, since the control unit 6 supplies a control pulse to the electrode thyristor control. When the voltage passes through "zero", the voltage sensor 5 generates a signal according to which the first timer included in the control unit 6 is reset, and the number is written in the second timer , where T is the alternating current period, f is the clock frequency of the control unit 6. Since the rectifier load is reactive, the current consumed by the load is shifted in phase with respect to the voltage by an angle α. When the current passes through "zero", the current sensor 4 generates a signal according to which the contents of the first timer of the control unit 6 are fixed while the number recorded in this timer is proportional to the clock frequency of the control unit 6 and the angle of the current phase shift α. The second timer, in which the number N is written at the beginning of the half-cycle, continues to be subtracted until its contents become equal to the contents of the first timer. If the values of the first and

the second timer, the control unit 6 generates a control pulse to turn off the first 10 or second 11 thyristor. Moreover, the turn-off angle β = π-α. The accumulated reactive energy is dissipated through the third diode 9 in the circuit of the third diode 9, the anchor winding 2, the excitation winding 3 of the pulsating current traction motor. Simultaneous adjustment of the angles α and β allows one to obtain a coincidence in phase of the mains voltage and the first harmonic of the current in a wide range of changes in the average value of the rectified voltage. This provides a power factor close to unity.

The proposed device for reactive power compensation implements the task: it increases the reliability of the device for reactive power compensation by reducing the number of elements (by 16) and eliminating the occurrence of shock currents in reactive elements, and increases the power factor in the entire control range due to the use of sector regulation in controlled straightener.

Claims (1)

A device for reactive power compensation, comprising a traction transformer, the primary winding of which is connected to the supply network, an armature winding and an excitation winding of a pulsating current traction motor, a current sensor and a voltage sensor, their outputs connected to the first and second inputs of the control unit, respectively, characterized in that that three diodes and two two-stage thyristors are additionally introduced into it, are connected to the free output of the armature winding of the pulsating current traction motor the nodes of the first, second and third diodes and the first output of the voltage sensor, the second output of which is connected to the free output of the excitation winding of the traction motor of the pulsating current and the general output of the cathodes of the third diode, the first and second two-operation thyristors, the control electrodes of which are connected to the first and second outputs of the control unit accordingly, the anode of the first two-stage thyristor and the cathode of the first diode are connected to the first terminal of the secondary winding of the traction transformer, the second terminal of which is connected through a current sensor with the cathode of the second two-stage thyristor and the anode of the second diode.