SU1394322A1 - Device for excitation of a synchronous machine - Google Patents

Abstract

The invention relates to electrical engineering. The aim of the invention is to improve reliability and speed in emergency control mode. For this purpose, a capacitor 20 connected between the charging unit 8 and the damping resistor 19, the differentiator 21, the Wmmitt triggers 22, 23, the logic control unit 24, the de-excitation unit 29 with the opening contact 31, included in the device for driving the synchronous machine.

Description

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between the disconnecting blocking contact 12 of the node 13 of the power output and the control input of the bridge rectifier 1, and the closing contact 32, bypassing the closing contact 18 of the node 13, The closing contact 30 of the node 13 is included in the starting circuit 10 of the shunt thyristor 7. Synchronous retention is provided in the device machine 3 in synchronism by forcing a current in a compensated low-inertia excitation circuit when operating in engine mode and intensively stimulating (magnetising the magnetic field) synchronous masking due to oscillatory descending excitation current in the generator mode, which contributes to a successful self-starting when the normal voltage level in the supply network is restored. 1 il.

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The invention relates to electrical engineering and can be used in emergency control of the excitation of synchronous machines, mainly synchronous motors, with deep voltage drops and short power interruptions, when part of the synchronous machines continue to operate in engine mode and the rest in generator mode.

The purpose of the invention is to increase the speed and reliability of controlling the excitation of a synchronous machine in emergency mode.

The drawing is a schematic diagram of a device for driving a synchronous machine.

The device contains a bridge rectifier 1 with thyristors in the cathode group and diodes in the anode, DC terminals podklotochenny parallel to the excitation winding 2 of the synchronous machine 3, a group of separation diodes 4, anodes connected to the AC terminals of the bridge rectifier 1, and the combined cathodes connected sequentially through the switching thyristor 5 and the forcing capacitor 6 to the cathode DC output of the rectifier 1, the shunting thyristor 7 and the charging unit 8 connected in parallel to the boost capacitor 6.upravl guide 9 and the starter circuit 10 connected to the control electrodes of respectively 5 and shunt switching thyristor 7, the control unit 11, a bridge rectifier 1, the output connected to the normally closed switch 12 controlled by a node 13 forcing excitation

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nor, and the input, the control unit 11 of the bridge rectifier. 1 is connected to the output of the sensor 14 active power, the inputs of which are connected to the sensors

voltage 15 and current 16, the threshold unit 17, the input connected to the output of the voltage sensor 15, the free output of the control circuit 9 through the first closing key 18 relay 13 force

The exciter is connected to the anode of the switching thyristor 5. The device also contains a damping resistor 19 and a separating capacitor 20, the first terminal of the resistor being connected to the anode direct current terminal, and the second terminal through the capacitor 20 to the common point of the boosting capacitor 6 and the cathode commuting 5 thyristors.

A differentiator 21, Schmitt triggers 22 and 23, a logic control block 24 composed of an element: AND-NO 25, an HE element 26, elements AND 27 and 28, and an excitation node 29 are introduced into the device. The differentiator 21 is connected to the output of the active power sensor 14 and to the input of the first Schmitt trigger 22, and the output of the differentiator 21 is connected to the input of the second

Schmitt trigger 23. The outputs of the triggers 22 and 23 are connected respectively to the inputs of the logical element AND-NOT 25, the output of which is connected to the input of the logical element HE 26 and the second input of the logical element AND 27, the first input of which is combined with the first input of the logical element And 28, forming the first input of the logic control unit 24 connected to the output

threshold block 17. Logical output

HE 26 is connected to the second input of AND 28. The outputs of the AND 27 and 28 logic elements form the outputs of block 24 and are connected respectively to the inputs of nodes 29 and 13. The second closing key 30 of the excitation force 13 is included in the starting circuit 10 connected to the thyristor anode 7. The opening keys 31 of the node 29 are connected between the opening control keys 12 of the unit 13 and the control electrodes of the bridge rectifier thyristors 1, and the closing key 32 of the excitation unit 29 is connected parallel to the key 18 of the node 13 of the forcing.

A device for driving a synchronous machine works as follows.

In the initial state at synchronous running of the machine in the engine mode, the opening keys 12 and 31 are closed, and the control 9 and start 10 circuits are open. The current in the excitation winding 2 of the synchronous machine 3 is determined by the signal of the current sensors 16, voltage 15 and power 14, as well as the initial setting of the bridge control unit 11, acting through excitation closures. When triggered

Chines 12 and 31 are at the opening angle of the thyristors of the cathode group of the rectifier 1. The forcing capacitor 6 is charged from block 8.

In the event of a short circuit in the power supply system, accompanied by a deep-fitting voltage or short-term power failure, synchronous machine 3 can be either in the mode of an engine or a generator, depending on the type of machine, the driven mechanism and the network parameters. Synchronous machines with a large supply of kinetic energy are transferred to the generator mode, they have an additional braking torque and intensively brake. Engines with a smaller supply of kinetic energy receive an additional moment due to feeding from the machines operating in the generator mode. Therefore, in order to ensure the conditions for successful self-starting synchronization

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It is necessary for the pioneer machine to either force an excitation, or to rapidly quench the magnetic field, depending on the mode of operation of the latter.

When landing, the voltage on the cortex of the synchronous machine 3 is below a predetermined level at the output of the threshold block 17

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node 13 opens controllable switches 12, switches 18 and 30, respectively, in control circuit 9 of switching thyristor 5 and starting circuit 10 of shunt thyristor 7. Switching thyristor 5 is switched on and the counter cathode group of thyristors of the bridge rectifier is counter-energized 1. The excitation winding 2 of the synchronous machine 3 is connected to an additional force source, formed by the group. separation diodes 4 and anode group of bridge rectifier valves. In the newly formed excitation circuit, capacitive compensation of the inductance of the excitation winding 2 occurs, a decrease in the time constant of the latter and a discharge of the boosting capacitor 6, leading to an intense increase in the current in this circuit. When the rechargeable capacitor 6 reaches a predetermined voltage level, a shunt thyristor 7 is turned on, which leads the forcing capacitor 6 from the excitation circuit. This creates a new excitation circuit: the power supply network

the level of the logical unit appears and is fed to the first inputs of the logical elements AND 27 and 28. At the same time, the sign of the active power of the core and its derivative is monitored.

With a positive sign of active power, i.e. When the machine is in engine mode, the output of the first Schmitt trigger 22 appears at the logical unit level and is fed to the first input of an AND-25 logic element. With a positive sign, the derivative from the jpToporo output of the Schmitt trigger 23 to the second input of the logical AND-NOT switch 25 enters the level of logical units. In this case, at the output of the logical element IS-NOT 25 a level of logical zero appears and arrives at the second input of the logical element AND 27, - and the second input of the logical element IS-NOT 25 receives the level of a logical unit inverted by the logical element NOT 26. As a result this, at the output of the logical element AND 27, a level of logical zero occurs, and at the input of the logical element AND 28, the level of the logical unit, which leads to the triggering of the node 13 of the excitation forcing. When triggered

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node 13 opens controllable switches 12, switches 18 and 30, respectively, in control circuit 9 of switching thyristor 5 and starting circuit 10 of shunt thyristor 7. Switching thyristor 5 is switched on and the counter cathode group of thyristors of the bridge rectifier is counter-energized 1. The excitation winding 2 of the synchronous machine 3 is connected to an additional force source, formed by the group. separation diodes 4 and anode group of bridge rectifier valves. In the newly formed excitation circuit, capacitive compensation of the inductance of the excitation winding 2 occurs, a decrease in the time constant of the latter and a discharge of the boosting capacitor 6, leading to an intense increase in the current in this circuit. When the rechargeable capacitor 6 reaches a predetermined voltage level, a shunt thyristor 7 is turned on, which leads the forcing capacitor 6 from the excitation circuit. This creates a new excitation circuit: the power supply network

alternating current - group of separation diodes 4 - switching thyristor 5 g - shunt thyristor 7 - excitation winding 2 - diodes of the anode group of a bridge chuck 1 - alternating current supply network, as a result of which the current in the excitation winding 2 is determined by the forcing voltage value bridge rectifier 1. After the power supply is restored and the voltage level is normal, the device returns to its original state,

When a synchronous machine fabot in the generator mode, as a result of a voltage landing in the network below a predetermined level, the output of the threshold unit 17 appears as a logical one and is fed to the first inputs of logic gates And 27 and 28. Since the active power of the core is negative, the first input the logical element IS-NOT 25, a logic zero level is applied, as a result of which the level of the logical unit appears at the output of the logic element AND 275, which leads to the activation of the node 29 and excitation. At the same time, the sign of the derivative of the active power does not have the meaning. The excitation node also works when the active power of the core is positive and its derivative is negative, which is characteristic of the transition of the synchronous machine 3 from the motor to the generator mode "When the unit 29 is operated, the keys 31 remove the control signals from the rectifier 1, close the key 32 in the control of the circuit 9 and turn on the switching thyristor 5. When the latter is turned on, the oppositely charged pre-charged voltage is switched on; the forcing capacitor 6 is locked by the cathode group of the thyristors of the bridge rectifier 1., the excitation winding 2 of the synchronous machine 3 switches to an additional source of the forcing voltage formed by a group of separation diodes 4 and the anode group of the diodes of the bridge rectifier 1, capacitive compensation of the inductance of the excitation circuit occurs, a decrease in the constant time of the winding 2 of the excitation and discharge of the forcing capacitor 6, leading to a short-term current surge in the compensated circuit. When resampling de capacitor 6 occurs

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an intensive decrease in the excitation current and when the current reaches zero value of the recharged forcing capacitor 6 closes the switching thyristor 5, excluding the source of charging voltage from the excitation circuit. Then, the capacitor 6 is discharged to the excitation winding 2 through the coupling capacitor & 20 and the damping resistor 19, changing the direction of the current in the winding.

Further operation of the synchronous machine occurs with a boosted magnetic field, and after the network voltage has been restored, favorable conditions are created for the successful resynchronization of the synchronous machine.

The circuit of resistor 19 and capacitor 20 is designed to prevent short circuit of rectifier 1 when switching on switching thyristor 5. When asynchronous start of synchronous masking is started, 3 extinguishing resistor 19 and capacitors 20 and 6 form an start-up protective circuit connected in parallel with winding 2- excitation.

As voltage sensors 15 and current 16, measuring transformers of voltage and current respectively can be used.

A standard current signal converter is used as the power sensor 14; and voltage to power.

In, the quality of the threshold block 17 can be applied Schmitt trigger.

As the control unit 11 of the bridge rectifier 1, a control system can be used, made according to any principle on semiconductor or other elements, or used as a serial one.

As keys 12,18,30-32, output devices of the first type of relay can be used, which are selected according to the number of thyristor control channels,

I.

 Control circuit 9 may contain

opposite-connected zener diode and diode, with the anode of the zener diode connected to the control electrode of the switching thyristor 5, a. the anode of the diode in series through two parallel-connected switching keys, connected in parallel with the combined cathodes of the separation diode group 4.

A starting circuit Y. contains an IT, for example, a threshold element (dynistor) connected in series with the key 30 of the node 13, and the cathode of the dynistor is connected to the control electrode of the shunt thyristor 7.

The charging unit 8 is made, for example, in the form of a single-phase transformer, the primary winding of which is connected to an independent AC mains, and the secondary winding is connected through a charging resistor and diode in parallel with the boost capacitor 6, and the anode of the charging diode is connected to the switching cathode thyristor 5.

Excitation forcing and excitation units 29 can be performed on any type of relay elements.

The differentiator 21, the 1Chmitt2d triggers of the current of the mentioned rectifier22 and 23, and the input of the logic unit 24 to the logic elements 25-28 can be performed, for example, using standard circuits on semiconductor elements or integrated circuits.

A device for emergency control of the excitation of a synchronous machine ensures that the latter is kept in synchronism by forcing the current in a compensated low-inertia excitation circuit when operating in the engine mode and intensive stimulation (damping of the magnetic field) of the synchronous machine due to the oscillatory decrease of the excitation current in the generator mode, which contributes to - to self-starting when the normal voltage level in the supply network is restored.

Thus, the positive effect of using a device for driving a synchronous machine consists in increasing the reliability of an electric drive, an entire series of responsible mechanisms with a continuous technological process.

Claims (1)

Invention Formula 25 thirty 35 40 45 l connected to the first output of the quenching resistor, the charging unit and the shunt thyristor with a starting circuit between the control electrode and the anode of the thyristor, connected in parallel to the boost capacitor, the control circuit composed of a zener diode, a diode and the first contact of the exciter unit, connected between the control electrode and the anode of the switching thyristor, which is different from the fact that, in order to increase reliability and speed in the emergency mode, a separating capacitor is inserted, one output ohm connected to the second output of the damping resistor, and another output connected to the connection point of the forcing capacitor and switching thyristor, a differentiator, two V1mitt flip-flops, a de-excitation unit with a tripping block contact connected between the tripping block of the excitation shaping unit and the control electrodes of the thyristors bridge rectifier, and a closing contact connected in parallel to the first closing contact of the forcing assembly, the second closing contact of which is included in the starting circuit of the shunt a thyristor, a control logic unit composed of AND-NOT, NOT elements and two AND elements, the first inputs of which form the first input of the logical control unit connected to the output of the threshold unit, and the outputs of the AND elements are the outputs of the logic control unit connected respectively to the inputs force knots50 A device for driving a synchronous machine, containing a three-phase bridge rectifier with thyristors in the cathode group and diodes in the anode group of gates and AC and DC terminals, current sensors 55 and the stator winding voltage of the synchronous machine, an active power sensor whose inputs are connected to the outputs Q five current and voltage sensors, threshold unit, input connected to voltage sensor output, field forcing unit with opening contact and two closing contacts, control unit, the input of which is connected to the output of active power sensor, and disconnecting unit installed at the output of control unit -contact of an excitation forcing unit, Consequently, a forcing capacitor, a switching thyristor and a separator diode grupp, connected by anodes to three-phase AC bridge terminals a rectifier whose cathode output DC is connected to a boost capacitor, and the anode output pos 25 thirty 35 40 45 50 55 l connected to the first output of the quenching resistor, the charging unit and the shunt thyristor with a starting circuit between the control electrode and the anode of the thyristor, connected in parallel to the boost capacitor, the control circuit composed of a zener diode, a diode and the first contact of the exciter unit, connected between the control electrode and the anode of the switching thyristor, which is different from the fact that, in order to increase reliability and speed in the emergency mode, a separating capacitor is inserted, one output ohm connected to the second output of the damping resistor, and another output connected to the connection point of the forcing capacitor and switching thyristor, a differentiator, two V1mitt flip-flops, a de-excitation unit with a tripping block contact connected between the tripping block of the excitation shaping unit and the control electrodes of the thyristors bridge rectifier, and a closing contact connected in parallel to the first closing contact of the forcing assembly, the second closing contact of which is included in the starting circuit of the shunt a thyristor, a control logic unit composed of AND-NOT, NOT elements and two AND elements, the first inputs of which form the first input of the logical control unit connected to the output of the threshold unit, and the outputs of the AND elements are the outputs of the logic control unit connected respectively to the inputs nodes forsirov9139A32210 excitation and de-excitation, automatically to the outputs of the triggers. The SM inputs of the I elements are connected, the input of one of which is directly responsible to the outputs of the AND-E, and the input of the other trigger and NOT, and the inputs of the element AND-NOT form, Schmitt through the differentiator of the second and third logical to the output of the sensor of the active power control unit connected to the correlation.