SU1032587A1 - Excitation system of synchronous machine with forced field damping - Google Patents

Abstract

1. EXCITATION SYSTEM FOR SYNCHRONOUS MACHINE WITH FORCED FIRE DETECTION, containing two thyristor converters connected anti-parallel to the field winding, the converter control system, the current interruption unit and the control relay of the field connected to the second converter control system and through the conversion unit an inverter mode with a control system controlled by the first converter, characterized in that, in order to increase reliability, a residual voltage sensor of the synchronous machine stator is inserted, with l its output connected to the second inputs of the converter control system and the current interrupting unit, whose output is connected to the second transducer. 2. The system according to claim 1, characterized in that the current sensor of the second converter is inserted, the output Q of the sensor is connected to the inputs of the control system S by the second converter W and the current interrupting unit.

Description

: The invention relates to electrical equipment and can be used; excitation systems for electric machines, mainly for: power of synchronous motors.

The excitation system of the syn-5 chronical machines is known with field quenching, short circuit of the excitation winding to active or nonlinear resistance, as well as by switching on the electromachine exciter or by transferring 10 ionic or thyristor exciters to the i inverter mode C 1.

 When an excitation winding is clamped for active or nonlinear resistance, 5 ot dependence of these resistances results in a higher or lower rotor current quenching speed, however, the quenching speed of the cj field of the RW Machine in this case is limited due to the presence of damping links on the rotor and the larger the larger damping circuit. Systems with the opposition of an electric machine driver are complex and cumbersome because of the difference in switching equipment to: the same electric machine agents have low technical and economic indicators.

The excitation system of the synxHan machine is known, containing two thyristor converters, connected} the first counter-parallel to the exciter coil, corresponding to the control systems of the converters, the reversing sensor of the current of the excitation winding, the separate control unit of the converter; lock block associated with converter control systems, b; inverter transfer bales and x1 contact relay. 40

Such a system provides a reverse excitation of the synchronous machine from the command relay, with one thyristor converter being converted to inverter mode and dg after the current drops to zero in the field winding according to the reverse signal dg1t, the current transducer locks the first converter through its control system and turns on the second n transformer. Reverse reverse Kci excitation occurs in the same order 2,

A disadvantage of the known excitation system is that, resolving the issue of extinguishing 55 tons of excitation during the reverse process, it does not solve the problem of forced extinguishing of the field of the synchronous machine, necessary for slowing down the start of synchronous motors after a short interruption of the power 60 to reduce the residual voltage on the machine and limiting the transient current in a non-synchronous switch-on. This reduces the reliability of the excitation system .65

The purpose of the invention is to increase the reliability due to the implementation of the synchronous machine floor mode.

The goal is achieved by the fact that in the excitation system of a synchronous machine containing two thyristors | , a transducer connected anti-parallel to the field winding, a transducer control system, a current interrupter unit and a command field suppressor relay connected to the second transducer control system and a residual voltage sensor introduced through the inverter mode conversion unit synchronous motor stator, while its output is connected to the inputs of the control system of the second thyristor converter and the current interrupter, the output of which is connected to the second transducer to the applicant

In addition, a current sensor of the second converter is inserted, the sensor output is connected to the inputs of the control system of the second converter and the current interrupting unit.

Figure 1 shows the block diagram of the excitation system of a synchronous machine with forced field blanking; Fig. 2 shows an example of a circuit for interrupting a current in a second converter; Fig. 3 shows a block diagram of an excitation system with an additional current sensor of a second converter.

The excitation system (fig. And consists of a first thyristor converter 1 with a control system 2 and a converter conversion unit 3 in an inverter mode, a second thyristor converter 4 with a control system 5 and with a current interruption block b thereon, a synchronous residual voltage sensor 7 The machine and the command relay 8 are quenched. The output of the second thyristor converter 4 is connected in parallel with the output of the main thyristor converter 1 is opposite, the output of the sensor 7 of the residual stator voltage is connected to the input of the system 5 are controlled by the second converter 4 and with the input of the current interrupting unit 6 in the second thyristor converter 4, and the output of the quench command relay 8 is connected to the input of the inverter mode 3 of the main converter 1 and to the input of the control system 5 of the second thyristor 4 o Outputs The converters are connected to the excitation winding 9 of the synchronous machine, and the inputs are connected to the source 10 of the excitation system.

The current interrupting unit 6 in accordance with the embodiment thereof consists of a capacitor 11 connected in parallel to the thyristors 4 (Fig. 2) of the anodic (or cathodic) group of the second converter through a sequential target from the additional thyristor 12 and diodes 13 for interfacial isolation and the charging circuit from diode 14 and resistor 15 connected in series between the point of connection of the capacitor 11 to the thyristor 12 and any phase of the source 10 of the excitation system. The excitation system with an additional current sensor of the second converter (Fig. 3) fully corresponds to the previously considered excitation system (Fig. 1) and additionally includes a sensor 16 of the current of the second converter 4, the sensor output is connected to the input of the control system 5 with the second converter 4 and input block b interrupt current. The excitation system works hardly. When a signal is applied to the field quench, the input of the command relay 8 from the relay output enters a signal at the input of the unit 3, which, through the control system 2, converts the first converter 1 to the inverter mode of operation, and the current in the excitation winding 9 goes to zero, The excitation winding stored in the induction is transmitted through converter 1 back to the source 10 of the excitation system. At the same time, the output of the relay 8 receives a signal to the input of the control system 5, which turns on the second thyristor converter 4. The current through the converter 4 will not go until the current in the excitation winding 9 drops to zero, since until that moment the converter 4 is locked in reverse excitation winding voltage. When the current in the excitation winding 9 reaches zero, the reverse current will flow through the converter 4 to the field winding, since the converter 4 is connected in parallel to the converter 1 with the opposite polarity of the voltage. The reverse of the current in the excitation winding does not quickly quench the magnetic flux in the synchronous machine circuits (machine quenching), while the residual stator voltage drops proportionally to the magnetic flux When the field is quenched to a sufficiently small value corresponding to the residual voltage sensor 7 the stator, from the output of the sensor 7, receives a signal to the input of the control system 5, which stops the current in the thyristor control circuits of the converter 4. At the same time, the signal from the sensor 7 of the residual voltage of the stator pos falls on the input of block 6, which interrupts the current in the conductive thyristor of converter 4. When converters 1 and 4 are simultaneously connected in parallel, the short-circuit currents flowing between them are short and small and do not damage the excitation system, since converter 4 operates in the rectifying mode, and the converter 1 in the inverter mode with the limiting thyristor control angle. Such a solution makes it possible not to include in the excitation system a complex switching unit of the transducers with a reversible current sensor in the excitation winding. Converter 4 is made small, designed to work only during the period of damping the floor of the machine, i.e. for a duration of less than 1 s. The field quenching speed of the machine depends on the voltage of the second converter, therefore the control system of the second converter switches it on with the constant lowest thyristor control angle and can be made as a relay, the closure contacts of which are connected between the anode and cadmium electrode of each thyristor of the second converter. The role of the indicated relay can also be performed by a command relay for blanking the machine floor. The current interrupter unit (Fig. 2) operates as follows. The capacitor 11 is charged during operation of the excitation system from the power supply 10 of the excitation system with a positive polarity through the diode 14 and a resistor 15 limiting the charging current, and a negative polarity from the same source through the excitation winding 9. The discharge of capacitor 11 is prevented by diode 14. At the end of the field quenching process, the signal from the residual voltage sensor 7 of the stator stops the current in the thyristor control circuits 4 and turns on the thyristor 12, the capacitor 11 through the thyristor 12 and one of the diodes 13 is discharged to the thyristor group 4, wherein the discharge current is directed against the current in the conducting thyristor, as a result of which the current in it reaches zero and the thyristor is closed. During parallel operation from common tires of several synchronous machines with an excitation system with forced field quenching due to different machines quenching magnetic flux rate, differences in their parameters may be the case when by the time of complete field quenching of one of the machines the residual voltage on the common tires does not fall to settings of the residual voltage sensor 7

the stator. In this case, fig. 3j, when the current of the reverse polarity in the excitation system of this machine rises to the setpoint of the high-speed sensor 16 of the input current of the second converter from the sensor 16 output to the control system 5, a signal on which the current in the thyristor control circuits 4 stops, at the same time, the signal from the sensor 16 is fed to the input of block 6, which interrupts the current in the conductive thyristor of the converter 4. As a result, the increase in the second converter 4 to the setpoint of the high-speed sensor: 16 ADDITIONAL termination criterion blanking floor of the synchronous machine, preventing the possibility of its magnetization reversal obratnzhm flow and, at the same time, protecting the second thyristor overload.

Thus, the excitation system with forced quenching of the synchronous machine floor provides high quenching speed, which increases reliability and allows self-starting of synchronous machines after a short power interruption with a low residual voltage.

on the stator and limited transition current.

Claims (2)

1. SYSTEM OF EXCITATION OF A SYNCHRONOUS MACHINE WITH FORCED FIELD EXTINGUISHING, containing two thyristor converters connected in parallel to the field winding, a control system of the converters, a current interruption unit and> The unit is a sandwich command field blanking relay connected to the control system of the eye converter and through the inverter to the inverter mode with my control of the first converter, characterized in that, in order to increase reliability, • a residual voltage sensor of the stator of the synchronous machine is introduced, while its output is connected to the inputs control systems of the second converter and the current interruption unit, the output of which is connected to the second converter. 2. The system according to claim 1, with the fact that a current sensor of the second converter is introduced, the output of the sensor is connected to the inputs of the control system of the second converter and the current interrupt block. Fig! cl H