RU68195U1 - REACTIVE POWER COMPENSATOR - Google Patents

Abstract

The utility model relates to electrical equipment, namely to electrical equipment of electric rolling stock of single-phase alternating current railways with zone-phase regulation. The reactive power compensator of an AC electric locomotive contains a traction transformer, a load in the form of two rectifier converters and traction motors, two reactive power sources having different reactive power values and each representing inductance and capacitance connected in series, thyristor switches connected in series with the sources; control unit, discharge resistors, shunt capacitance; two current sensors connected in series with thyristor switches; two voltage sensors, each of which is connected in parallel with thyristor switches; two thyristor control pulse shapers. The control unit is connected by its inputs to a reactive power meter. EFFECT: increased efficiency of reactive power compensators on an electric locomotive.

Description

The utility model relates to electrical equipment, namely to electrical equipment of electric rolling stock of single-phase alternating current railways with zone-phase regulation and is intended to increase the power factor of electric locomotives and electric trains.

The use of reactive power compensators on an electrically rolling stock is one of the ways to increase the power factor using an LC circuit connected to the secondary winding of the transformer to create a capacitive load and reduce the phase angle between the primary current and voltage.

A utility model prototype adopted a reactive power compensator for an alternating current electric locomotive (utility model of the Russian Federation No. 56734), containing a traction transformer, the primary winding of which is connected to the traction network, and a load in the form of two rectifier-inverter converters connected to the outputs of which are traction motors, and through two thyristor switches, each consisting of thyristor arms turned on, two reactive power sources are connected, each consisting of connected inductance and capacitance shunted by discharge resistors, two thyristor switch control pulse generators connected by their outputs to the thyristor control inputs, two voltage sensors connected in parallel to the thyristor switches, two current sensors, each of which is connected in series with the thyristor switch, voltage sensors and current are connected by their outputs to the control unit, the outputs of which are connected to the inputs of the control pulse shapers, two mechanical commutators and made in the form of two pairs of bipolar

contactors; in this case, one pair of bipolar contacts is connected to the terminals of one traction winding and the first source of reactive power, and the other pair is connected to the terminals of another traction winding and the second source of reactive power, the outputs of the control unit are connected to the inputs of the bipolar contactors.

The disadvantages of the prototype are:

- regulation of reactive power is carried out using a mechanical switch by changing the voltage at the sources of reactive power from 0.5 to 0.75 voltage of the traction winding;

- low reliability of this switch, associated with frequent switching switching (“sticking” contactors, the need for a time delay during switching to avoid short circuit sections of the traction windings);

- low reliability of the control unit that implements a complex control algorithm for a mechanical switch and a thyristor key for regulating reactive power;

- lack of information on the magnitude of the consumed reactive power in various modes of operation of the electric locomotive, and therefore information on the real power factor.

The objective of the proposed utility model is to eliminate these drawbacks, and, consequently, increase the efficiency of compensating devices on AC electric locomotives.

The solution to this problem is achieved by the fact that in the reactive power compensator of an alternating current electric locomotive containing a traction transformer, the primary winding of which is connected to the traction network, and the load in the form of two rectifier-inverter converters with traction motors connected to the outputs of the transformer, and through two thyristor switches, each consisting of thyristor arms turned on, two reactive power sources are connected, each consisting in series

connected inductance and capacitance shunted by discharge resistors, two thyristor switch control pulse generators connected by their outputs to the thyristor control inputs, two voltage sensors connected in parallel to the thyristor switches, two current sensors, each of which is connected in series with the thyristor switch, voltage sensors and current are connected by their outputs to the control unit, the outputs of which are connected to the inputs of the control pulse shapers, counters are additionally introduced into it reactive energy, connected to the transformer primary input and its output connected to the control unit and each of the two sources is different in magnitude reactive power.

The first source has a reactive power of Q ₁ , the second source has a reactive power of Q _2. different from the first in magnitude, with Q _2. > Q ₁ . At the command of the control unit, depending on the magnitude of the consumed reactive power Q _fact received from the counter, the corresponding thyristor switches are turned on, providing three stages of reactive power regulation:

1) with Q _fact <Q _{1, the} first reactive power source with Q _{1 is} turned _on ;

2) when Q _fact > Q _{1, the} second source of reactive power with Q _{2 is} turned _on , and the first is turned off;

3) when Q _fact > Q ₁ , both reactive power sources with Q ₁ and c Q _{2 are} turned _on ;

Due to the introduction of new features, a positive effect is achieved, which eliminates the need for a mechanical switch and its control circuitry and increases the reliability of the control unit, provides information on the magnitude of the consumed reactive power.

The figure 1 shows a reactive power compensator with reactive power sources turned on at the extreme terminals

traction winding.

The figure 2 presents a reactive power compensator with one source turned on to the extreme leads of the traction winding, another source is connected to the intermediate leads of the traction winding.

The reactive power compensator of an alternating current electric locomotive contains a traction transformer 1, the primary winding of which 2 is connected to the supply network. The secondary windings of the traction transformer 3 are made in the form of two sectioned traction windings. The load is made in the form of two rectifier converters 4, each of which is connected to traction motors 5. Two sources of reactive power 6 and 7, which have different values of reactive power Q ₁ and Q ₂ , with Q _2. > Q ₁ , and which are connected in series the inductance 8, 9 and the capacitance 10, 11 are connected in parallel with the secondary traction windings 3. Moreover, the reactive power compensator contains: thyristor switches 12, connected in series with sources 6 and 7, consisting of two thyristos shoulders; a control unit 17, discharge resistors 13, shunt capacitance 10 and 11; two current sensors 14 connected in series with thyristor switches 12; two voltage sensors 15, each of which is connected in parallel with thyristor switches 12; two thyristor control pulse shapers 16 connected by their outputs to the control inputs of the thyristor switches 12 and the input to the control unit 17. The control unit 17 is connected by its inputs to a reactive power meter 18 connected in front of the network winding 2, the outputs of the current sensors 14 and voltage 15.

The control unit 17 is connected to a microprocessor control system of an electric locomotive 19 and receives information from it about the magnitude of the armature current of the traction motor and the regulation zone.

The utility model allows implementing three stages of regulation by reactive power compensation. In this case, the difference in the reactive

power sources connected to different traction windings can be achieved in two ways. In the first embodiment, shown in figure 1, reactive power sources 6 and 7 can have different capacitance and inductance parameters and can be connected to the full voltage of the traction winding. In the second embodiment, shown in figure 2, with the same parameters of inductances and capacities of sources 6 and 7, the difference in their reactive power is achieved by connecting to different sections of the traction winding: source 6 is connected to 0.75 voltage of the traction winding, and source 7 to the full voltage of traction windings.

The proposed utility model of a reactive power compensator completely eliminates the disadvantages of the prototype and will increase the efficiency of the use of reactive power compensators on an electric locomotive.

Claims (1)

A reactive power compensator for an alternating current electric locomotive containing a traction transformer, the primary winding of which is connected to the traction network, and a load in the form of two rectifier-inverter converters, to the outputs of which the traction motors are connected, and through two thyristor switches, each consisting of counter thyristor arms, two reactive power sources are connected, each consisting of a series-connected inductance and a capacitor shunted discharge resistors, two thyristor switch control pulse generators connected by their outputs to the thyristor control inputs, two voltage sensors connected in parallel with the thyristor switches, two current sensors, each of which is connected in series with the thyristor switch, and the voltage and current sensors are connected by their outputs to the unit control, the outputs of which are connected to the inputs of control pulse shapers, characterized in that a counter of reactive energy is additionally introduced into it, ny inlet of the primary winding of the transformer and its output connected to the control unit and each of the two sources of reactive power has a different value for reactive power.