JP2013236480A - Induction brushless ac excitation system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an induction brushless AC excitation system capable of thyristor start by a brushless AC excitation system, and capable of DC control in rated operation.SOLUTION: The induction brushless AC excitation system of an embodiment includes a three-phase AC power supply, a first rectifier, and first changeover connection means. The three-phase AC power supply generates a three-phase AC output. The first rectifier rectifies the three-phase AC output and supplies a DC current to the field winding of an induction brushless AC exciter. The first changeover connection means connects the three-phase AC power supply and the field winding of the induction brushless AC exciter at startup of a generator, and switches the connection to an open state to connect the input side of the first rectifier with two-phases out of three-phases of the three-phase AC power supply at the time of rated speed of the generator.

Description

  Embodiments described herein relate generally to an inductive brushless AC excitation system.

  Generally, a synchronous generator supplies a direct current to a rotor field winding and outputs an induced electromotive force generated by a magnetic flux generated on the rotor side on the stator side. As a typical method for exciting a rotor field winding by supplying a direct current, there are a thyristor excitation method and a brushless AC excitation method.

  In the thyristor excitation method, a direct current from the outside is brought into contact with a slip ring on a rotating body so that the brush is brought into contact with the field winding of the generator to excite it.

  In the brushless AC excitation method, the AC output from the armature winding of the rotary armature type AC exciter directly connected to the generator field winding, which is the main machine, is converted to DC by a rotary rectifier mounted on the same rotating shaft. Convert and excite by supplying direct current to the field winding of the generator without using slip ring or brush.

  Each excitation method has its advantages. For example, the thyristor excitation method has an advantage that the shaft length of the generator is shorter than that of the brushless excitation method.

  On the other hand, compared with the thyristor excitation method, the brushless excitation method has an advantage that maintenance is easy because a brush is not used, and an excitation panel can be simplified because the excitation capacity is small.

Japanese Patent Laid-Open No. 7-245998

  Conventionally, in a gas turbine, a starting method using an electric motor and a torque converter has been used. In recent years, with an increase in the capacity of a single gas turbine, it has become difficult to realize a torque converter with a large capacity in the conventional starting system. Since the compressor operates at a rotational speed higher than a certain value, the gas turbine does not operate unless the rotational speed reaches a certain number. Therefore, the starting method becomes a problem in the gas turbine.

  Generally, a thyristor starting method is used in a gas turbine. The thyristor starting method is a method in which the generator is pulled in synchronously at the time of low-speed rotation, and the frequency of the armature current of the generator is gradually increased by an inverter device to increase the rotational speed of the rotor to the synchronous speed. Since the thyristor starting method uses brushes and slip rings, application of the brushless excitation method is desired.

  However, in the brushless excitation method, when the generator is started as an electric motor, such as a gas turbine, the rotating armature AC exciter and the permanent magnet are stationary at the time of starting, and no voltage is generated. Since the exciting current cannot be supplied to the windings and the generator cannot be excited, it cannot be used for starting a thyristor.

  However, as described above, the brushless excitation method has the advantage that maintenance is easy because no brush is used, and that the excitation panel can be simplified because the excitation capacity is small compared to the thyristor excitation method. . Further, since it is desired to use an automatic voltage regulator that controls direct current, it is desirable to control with direct current during rated operation of the generator.

  The present invention has been made in view of the above circumstances, and an object of the present invention is to provide an induction brushless AC excitation system capable of starting a thyristor by a brushless excitation method and capable of being controlled by a direct current during rated operation.

  The induction type brushless AC excitation system of the embodiment includes a generator, an induction type brushless AC excitation machine, and a rotary rectifier.

  The generator is started by a thyristor starting system.

  The induction-type brushless AC exciter has a rotor connected to a rotor of the generator.

  The rotary rectifier is attached to a rotor of the generator, rectifies the AC output generated by the induction brushless AC exciter, and supplies the rectified current to the field winding of the generator.

  Here, the inductive brushless AC excitation system includes a three-phase AC power source, a first rectifier, and first switching connection means.

  The three-phase AC power source generates a three-phase AC output.

  The first rectifier is a rectifier for rectifying the three-phase AC output and supplying a DC current to the field winding of the induction brushless AC exciter.

  The first switching connection means connects the three-phase AC power source and the three-phase field winding of the induction-type brushless AC exciter when the generator is started, and the connection when the generator is at a rated rotational speed. Is switched to the open state to connect the input side of the first rectifier and two phases of the three phases of the three-phase AC power source.

  As described above, according to the present invention, it is possible to provide an induction type brushless AC excitation system capable of starting a thyristor by a brushless excitation method and capable of being controlled by a DC during rated operation.

It is a schematic diagram which shows the structure of the electric circuit of the induction type brushless alternating current exciter system which concerns on 1st Embodiment. It is a schematic diagram which shows arrangement | positioning of each apparatus of the induction type brushless alternating current exciter system in the embodiment. It is a schematic diagram which shows the connection of the electric circuit at the time of the low speed rotation (including the time of a start) and the rated rotational speed in the embodiment. It is a schematic diagram which shows the structure of the electric circuit of the induction type brushless alternating current exciter system which concerns on 2nd Embodiment. It is a schematic diagram which shows arrangement | positioning of each apparatus of the induction type brushless alternating current exciter system in the embodiment. It is a schematic diagram which shows the structure of the electric circuit of the induction type brushless alternating current exciter system which concerns on 3rd Embodiment. It is a schematic diagram which shows arrangement | positioning of each apparatus of the induction type brushless alternating current exciter system in the embodiment. It is a schematic diagram which shows the structure of the electric circuit of the induction type brushless alternating current exciter system which concerns on 4th Embodiment. It is a schematic diagram which shows the connection of the electric circuit at the time of the low speed rotation (including the time of a start) and the rated rotational speed in the embodiment. It is a schematic diagram which shows the structure of the electric circuit of the induction type brushless alternating current exciter system which concerns on 5th Embodiment. It is a schematic diagram which shows the structure of the electric circuit of the induction type brushless alternating current exciter system which concerns on 6th Embodiment.

  Each embodiment will be described below with reference to the drawings.

<First Embodiment>
1 and 2 are schematic diagrams showing the configuration of the electric circuit and the arrangement of each device of the induction-type brushless AC exciter system according to the first embodiment, and FIG. It is a schematic diagram which shows the connection of the electric circuit at the time of a rated rotational speed. As shown in FIG. 1, this induction-type brushless AC exciter system includes a generator 1, a rotary rectifier 2, an induction-type brushless exciter 3, a three-phase AC power source 4, a first rectifier 5, a switch 6 and three Connection switchers 7 to 9 are provided. In addition, the switch 6 and the three connection switchers 7-9 comprise the 1st switching connection means.

  Here, the generator 1 has a field winding 1f and an armature winding 1a, and is started by a thyristor starting system. In the present specification, the subscript “f” represents a field winding, and the subscript “a” represents an armature winding.

  The rotary rectifier 2 is attached to the rotor of the generator 1, rectifies the AC output generated by the induction brushless AC exciter 3, and supplies it to the field winding 1 f of the generator 1. Note that the rotor provided with the field winding 1f and the rotary rectifier 2 of the generator 1 and the rotor provided with the armature winding 3f of the induction-type brushless exciter 3 are rotating parts of the same rotating shaft. r.

  The induction type brushless exciter 3 is a rotary armature type electric motor, and includes a three-phase field winding 3f and an armature winding 3a, and a rotor connected to the rotor of the generator 1. Yes.

  The three-phase AC power source 4 generates a three-phase AC output.

  The first rectifier 5 is a rectifier for rectifying the three-phase AC output and supplying a DC current to the field winding 3 f of the induction brushless AC exciter 3.

  The switch 6 and the connection switches 7 and 8 connect the three-phase AC power source 4 and the three-phase field winding 3f of the induction brushless AC exciter 3 during the low-speed rotation from the start of the generator 1 to generate power. At the rated rotational speed of the machine 1, the connection is switched to the open state, and the input side of the first rectifier 5 and the two phases of the three phases of the three-phase AC power supply 4 are connected.

  At the rated rotational speed of the generator 1, the connection switch 9 shorts two phases of the three phases of the field winding 3 f of the induction type AC brushless exciter 3 on the output side of the first rectifier 5, and The short-circuited two phases and the output side of the first rectifier 5 are further connected.

  Next, the operation of the induction brushless AC exciter system configured as described above will be described.

  When the generator 1 is started, as shown on the left side of FIG. 3, the field winding 3f of the induction brushless AC exciter 3 is used as a three-phase winding. The induction brushless AC exciter 3 is configured so that an AC magnetic field opposite to the fixed side is generated in the three-phase winding of the induction brushless AC exciter 3. An AC output is generated on the rotating side of the induction brushless exciter 3 by this rotating magnetic field, and the AC output is rectified by the rotary rectifier 2 to excite the generator.

  At this time, a low-frequency current is input to the armature winding 1a of the generator 1 to synchronize during low-speed rotation. Thereafter, the generator 1 is increased to the rated rotational speed.

  At the rated rotation speed, as shown on the right side of FIG. 3, by switching the connection of the field winding 3f of the induction brushless AC exciter 3, the three-phase AC current 4 is rectified and the DC current is converted to the induction brushless AC. By supplying the field winding 3 f of the exciter 3, direct current control is possible.

  As described above, according to the present embodiment, as shown in FIG. 3, the three-phase field winding 3 f of the three-phase AC power source 4 and the induction-type brushless AC exciter 3 during the low-speed rotation from the start of the generator 1. And connecting the input side of the first rectifying device 5 to two of the three phases of the three-phase AC power source 4 at the rated rotational speed of the generator 1 and induction. Of the three phases of the field winding 3f of the AC brushless exciter 3 is short-circuited on the output side of the first rectifier 5, and the short-circuited two phases are further connected to the output side of the first rectifier 5. According to the connection configuration, it is possible to provide an inductive brushless AC excitation system that can start a thyristor by a brushless excitation method and can be controlled by DC during rated operation.

  Supplementally, the field winding 3f of the induction-type brushless AC exciter 3 is a three-phase winding during the low-speed rotation from the start of the generator 1, and a structure that generates a rotating magnetic field opposite to the fixed side is generated. A thyristor starting method based on a brushless excitation method that can be used even in an automatic voltage regulator (AVR) that controls direct current by applying a direct current to the field winding 3f of the induction brushless alternating current exciter 3 at a rotational speed. An inductive brushless AC excitation system can be provided.

  In addition, according to the present embodiment, by providing an induction type brushless AC excitation system, it is possible to start thyristors with the brushless excitation method and control with direct current at the rated rotation speed, and to maintain the brush with the thyristor activation method. It becomes unnecessary, and the excitation panel can be simplified because the excitation capacity is small.

<Second Embodiment>
4 and 5 are schematic views showing the configuration of the electric circuit and the arrangement of each device of the induction-type brushless AC exciter system according to the second embodiment. The detailed explanation is omitted here, and the different parts are mainly described here.

  The second embodiment is a modification of the first embodiment, and further includes a rotary armature type AC exciter 10 and a second rectifier 11 in addition to the configuration shown in FIGS. 1 and 2. ing.

  Here, the rotary armature type AC exciter 10 includes a rotor connected to the rotor of the induction-type brushless AC exciter 3 and a direct current supplied from the rotary rectifier 2 to the rotor. And a field winding 10f to which the part is supplied. The AC exciter 10 has an armature winding 10a provided on the stator. The rotor provided with the field winding 1f and the rotary rectifier 2 of the generator 1 and the rotor provided with the armature winding 3f of the induction brushless exciter 3 are a rotary armature AC. The rotor provided with the field winding 10f of the exciter 10 constitutes a rotating part r of the same rotating shaft.

  The second rectifier 11 is a rectifier that rectifies the AC output generated by the rotary armature AC exciter 10 and supplies it to the field winding 3 f of the induction brushless AC exciter 3.

  Next, the operation of the induction brushless AC exciter system configured as described above will be described.

  The starting method of the generator 1 and the connection of the field winding 3f of the induction brushless AC exciter 3 in the induction type brushless AC excitation type thyristor start are the same as those in the first embodiment.

  On the other hand, at the rated rotation speed of the generator 1, the AC output from the induction brushless AC exciter 3 is rectified, and a part of the DC current input to the field winding 1f of the generator 1 is converted into a rotating armature AC. It is input to the field winding 10 f of the exciter 10, the AC output from the rotary armature AC exciter 10 is rectified, and a direct current is supplied to the field winding 3 f of the induction brushless AC exciter 3.

  As described above, according to the present embodiment, in addition to the effects of the first embodiment, the AC output from the rotary armature AC exciter 10 is rectified at the rated rotational speed of the generator 1 to induce brushless AC. A direct current can be supplied to the field winding 3 f of the exciter 3.

<Third Embodiment>
6 and 7 are schematic diagrams showing the configuration of the electric circuit and the arrangement of each device of the induction-type brushless AC exciter system according to the third embodiment.

  The third embodiment is a modification of the first embodiment, and further includes a permanent magnet generator 20, a third rectifier 21, and two switches 22 in addition to the configuration shown in FIGS. 1 and 2. ing.

  Here, the permanent magnet generator 20 includes a rotor connected to the rotor of the induction brushless AC exciter 3 and a permanent magnet (PM) 20p provided on the rotor. The permanent magnet generator 20 has an armature winding 20a provided on the stator. The rotor provided with the field winding 1 f and the rotary rectifier 2 of the generator 1 and the rotor provided with the armature winding 3 f of the induction brushless exciter 3 are the same as those of the permanent magnet generator 20. The rotor provided with the permanent magnet 20p constitutes the rotating part r of the same rotating shaft.

  The third rectifier 21 is a rectifier for rectifying the AC output generated by the permanent magnet generator 20 and supplying it to the field winding 3 f of the induction brushless AC exciter 3.

  The switch 22 opens the output side of the third rectifier 21 and the field winding 3f of the induction-type brushless AC exciter 3 when the generator 1 starts rotating at a low speed, and when the generator 1 is rated at the rated rotational speed. The output side of the third rectifier 21 is connected to the field winding 3f of the induction brushless AC exciter 3.

  Next, the operation of the induction brushless AC exciter system configured as described above will be described.

  The starting method of the generator 1 and the connection of the field winding 1f of the induction type brushless AC exciter 3 in the induction type brushless AC excitation type thyristor start are the same as those in the first embodiment.

  On the other hand, at the rated rotational speed of the generator 1, the AC output from the permanent magnet generator 20 is rectified and a direct current is supplied to the field winding 3 f of the induction brushless AC exciter 3.

  As described above, according to the present embodiment, in addition to the effects of the first embodiment, the AC output from the permanent magnet generator 20 is rectified at the rated rotational speed of the generator 1 to A direct current can be supplied to the field winding 3f.

<Fourth Embodiment>
FIG. 8 is a schematic diagram showing the configuration of the electric circuit of the induction-type brushless AC exciter system according to the fourth embodiment, and FIG. 9 shows the electric circuit at the low speed rotation (including the start time) and at the rated rotation speed. It is a schematic diagram which shows a connection.

  The fourth embodiment is a modification of the first embodiment. Instead of the switch 6 and the connection switches 7 to 9 (first switching connection means) shown in FIGS. 1 and 3, a switch 30 is provided. And two connection switchers 31 and 32 (second switch connection means).

  Here, the switch 30 and the connection switches 31 and 32 connect the three-phase AC power source 4 and the field winding 3f of the induction-type brushless AC exciter 3 during the low-speed rotation from the start of the generator 1 to generate power. At the rated rotational speed of the machine 1, the connection is switched to an open state to connect two phases of the three phases on the input side of the first rectifier 5 and two phases of the three phases of the three-phase AC power supply 4. To do.

  Next, the operation of the induction brushless AC exciter system configured as described above will be described.

  When the generator 1 is started, the field winding 5 of the induction-type brushless AC exciter 3 is used as a three-phase winding, as shown on the left side of FIG. The induction brushless AC exciter 3 is configured so that an AC magnetic field opposite to the fixed side is generated in the three-phase winding of the induction brushless AC exciter 3. An AC output is generated on the rotating side of the induction brushless exciter 3 by this rotating magnetic field, and the AC output is rectified by the rotary rectifier 2 to excite the generator.

  At this time, a low-frequency current is input to the armature winding 1a of the generator 1 to synchronize during low-speed rotation. Thereafter, the generator 1 is increased to the rated rotational speed.

  At the rated rotation speed, as shown on the right side of FIG. 9, by switching the connection of the field winding 3f of the induction brushless AC exciter 3, the three-phase AC current 4 is rectified and the DC current is converted to the induction brushless AC. By supplying the field winding 3 f of the exciter 3, direct current control is possible.

  Here, by using the two-phase series winding shown on the right side of FIG. 9, the three-phase series-parallel winding in which the two-phase parallel winding shown on the right side of FIG. Compared with the wire, the input current to the field winding 3f of the brushless AC exciter 3 is small.

  As described above, according to the present embodiment, as shown in FIG. 9, the three-phase AC power source 4 and the field winding 3 f of the induction brushless AC exciter 3 are connected when the generator 1 is started at a low speed. Then, at the rated rotational speed of the generator 1, the connection is switched to the open state, so that two of the three phases on the input side of the first rectifier 5 and two of the three phases of the three-phase AC power supply 4 are switched. In addition to the effects of the first embodiment, the input current to the field winding 3f of the brushless AC exciter 3 can be made small.

<Fifth Embodiment>
FIG. 10 is a schematic diagram showing a configuration of an electric circuit of the induction-type brushless AC exciter system according to the fifth embodiment.

  The fifth embodiment is an example in which the second embodiment and the fourth embodiment are combined, and instead of the switch 6 and the connection switches 7 to 9 (first switching connection means) shown in FIG. The switch 30 and the two connection switchers 31 and 32 (second switch connection means) are provided.

  According to the configuration as described above, the effect of the second embodiment and the effect of the fourth embodiment can be obtained simultaneously.

<Sixth Embodiment>
FIG. 11 is a schematic diagram showing a configuration of an electric circuit of an induction type brushless AC exciter system according to the sixth embodiment.

  The sixth embodiment is an example in which the third embodiment and the fourth embodiment are combined, and instead of the switch 6 and the connection switches 7 to 9 (first switching connection means) shown in FIG. The switch 30 and the two connection switchers 31 and 32 (second switch connection means) are provided.

  According to the configuration as described above, the effect of the third embodiment and the effect of the fourth embodiment can be obtained simultaneously.

  In addition, although some embodiment of this invention was described, these embodiment is shown as an example and is not intending limiting the range of invention. These novel embodiments can be implemented in various other forms, and various omissions, replacements, and changes can be made without departing from the scope of the invention. These embodiments and modifications thereof are included in the scope and gist of the invention, and are included in the invention described in the claims and the equivalents thereof.

  DESCRIPTION OF SYMBOLS 1 ... Generator, 1f, 3f, 10f ... Field winding, 1a, 3a, 10a, 20a ... Armature winding, 2 ... Rotary rectifier, 3 ... Induction type brushless exciter, 4 ... Three-phase alternating current power supply, 5 , 11 ... Rectifier, 6, 22 ... Switch, 7 to 9 ... Connection switcher, 10 ... Rotating armature type AC exciter, 20 ... Permanent magnet generator.

Claims (7)

A generator started by a thyristor starting system, an induction brushless AC exciter having a rotor coupled to the rotor of the generator, and the induction brushless AC exciter attached to the rotor of the generator An inductive brushless alternating current excitation system comprising a rotary rectifier that rectifies the alternating current output generated in step 1 and supplies it to the field winding of the generator,
A three-phase AC power source that generates a three-phase AC output;
A first rectifier for rectifying the three-phase AC output and supplying a DC current to a field winding of the induction brushless AC exciter;
The three-phase AC power source and the three-phase field winding of the induction type brushless AC exciter are connected at the time of low speed rotation from the start of the generator, and the connection is opened at the rated rotation speed of the generator. A first switching connection means for switching and connecting the input side of the first rectifier and two phases of the three phases of the three-phase AC power source;
An inductive brushless AC excitation system characterized by comprising: The induction-type brushless AC excitation system according to claim 1,
The first switching connection means short-circuits two phases of the three phases of the field winding of the induction-type AC brushless exciter at the output side of the first rectifier at the rated rotational speed of the generator; and An inductive brushless AC excitation system, wherein the short-circuited two phases are further connected to the output side of the first rectifier. In the induction type brushless alternating current excitation system according to claim 1 or 2,
A rotating electrical machine having a rotor connected to a rotor of the induction-type brushless AC exciter and a field winding provided in the rotor and supplied with a part of a direct current supplied from the rotary rectifier Child AC exciter,
A second rectifier that rectifies the AC output generated by the rotary armature AC exciter and supplies the rectified current to the field winding of the induction brushless AC exciter;
An inductive brushless AC excitation system characterized by further comprising: In the induction type brushless alternating current excitation system according to claim 1 or 2,
A permanent magnet generator having a rotor connected to a rotor of the induction-type brushless AC exciter, and a permanent magnet provided on the rotor;
A third rectifier for rectifying the AC output generated by the permanent magnet generator and supplying it to the field winding of the induction brushless AC exciter;
The output side of the third rectifier and the field winding of the induction-type brushless AC exciter are opened at the time of low speed rotation from the start of the generator, and the third rectifier of the third rectifier at the rated rotation speed of the generator. Opening and closing means for connecting the output side and the field winding of the induction type brushless AC exciter,
An inductive brushless AC excitation system characterized by further comprising: The induction-type brushless AC excitation system according to claim 2,
Instead of the first switching connection means,
At the time of low-speed rotation from the start of the generator, connect the three-phase AC power source and the field winding of the induction type brushless AC exciter, switch the connection to the open state at the rated rotation speed of the generator, A second switching connection means for connecting two phases of the three phases on the input side of the first rectifier and two phases of the three phases of the three-phase AC power supply;
An inductive brushless AC excitation system characterized by comprising: The induction-type brushless AC excitation system according to claim 5,
A rotating electrical machine having a rotor connected to a rotor of the induction-type brushless AC exciter and a field winding provided in the rotor and supplied with a part of a direct current supplied from the rotary rectifier Child AC exciter,
A second rectifier that rectifies the AC output generated by the rotary armature AC exciter and supplies the rectified current to the field winding of the induction brushless AC exciter;
An inductive brushless AC excitation system characterized by further comprising: The induction-type brushless AC excitation system according to claim 5,
A permanent magnet generator having a rotor connected to a rotor of the induction-type brushless AC exciter, and a permanent magnet provided on the rotor;
A third rectifier for rectifying the AC output generated by the permanent magnet generator and supplying it to the field winding of the induction brushless AC exciter;
The output side of the third rectifier and the field winding of the induction-type brushless AC exciter are opened at the time of low speed rotation from the start of the generator, and the third rectifier of the third rectifier at the rated rotation speed of the generator. Opening and closing means for connecting the output side and the field winding of the induction type brushless AC exciter,
An inductive brushless AC excitation system characterized by further comprising:

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