JPH0828987B2 - AC excitation power generator - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to an alternating-current excitation generator / motor device, and particularly contributes to system stability by taking operating energy of a rotating part into and out of a power system, such as a variable speed pumped storage power generation system. The present invention relates to an AC excitation generator-motor device suitable for realizing stable and low-loss start-up.

[Conventional technology]

As a conventional AC excitation power generator, Japanese Patent Publication Sho 53-76
As described in No. 28 and Japanese Patent Publication No. 57-60645, there is a method of controlling active power and reactive power by controlling the secondary current of an AC exciter. These methods are suitable as a power adjustment device and a power factor adjustment device that respond quickly while preventing disturbance and out-of-step. A variable-speed pumped-storage generator that uses a cycloconverter as a frequency converter to compose an AC-excited generator motor and a pump turbine is directly connected to an AC-excited synchronous machine is announced at the Kansai Branch Joint Conference of the Electrical Association of Japan in 1985. It is suitable for adjusting the frequency of a power system.

On the other hand, when starting the AC-excited generator motor, the normal operation method in which AC excitation is performed by the frequency conversion device can only operate in a certain speed range centered on the synchronous speed of the AC excitation synchronous machine, so another start-up operation method should be used. Must be used.

When the AC excitation power generator is used as a pumping power generator, it is possible to accelerate the speed from the stopped state to the AC excitation operable speed by adjusting the guide vane opening of the turbine during the operation of the turbine. In the pumping operation, there is a method of using a starting electric motor as in the conventional starting method of a DC excitation synchronous machine.

In each of the above conventional techniques, a special device is required for starting, but there is JP-A-59-63988 as a method of using the frequency converter for AC excitation at the time of starting. FIG. 6 shows an embodiment of an AC excitation generator-motor apparatus using this conventional technique. An example in which a non-circulating current type cycloconverter is used as a frequency converter that supplies a current to each secondary side winding of the AC excitation synchronous machine 1 will be described. The non-circulating current type cycloconverter has a configuration in which a positive group thyristor converter 3 and a negative group thyristor converter 4, which are fed from an AC system through a transformer 2, are connected in antiparallel. When the variable speed generator-motor with the above configuration is started,
Up to 50% speed, the switch 6 is closed and the switches 5 and 8 are opened. At this time, the AC excitation synchronous machine becomes an induction machine whose primary side is short-circuited, and can be accelerated by increasing the output frequency of the frequency converter according to the rotation speed. After accelerating the rotation speed to about 50% of the synchronous speed,
When accelerating to near the minimum speed at which normal AC excitation can be performed, the switches 5 and 6 are opened, the switch 8 is closed, and the voltage is reduced to the primary side of the AC excitation synchronous machine 1 via the transformer 7. AC excitation is performed by the frequency converter while the system voltage is applied. At this time, since the primary side voltage is stepped down, it is possible to operate in a wider speed range than the range in which normal AC excitation operation centered on the synchronous speed is possible. In this state, after accelerating to the vicinity of the minimum speed at which the AC excitation operation is possible, the switches 6 and 8 are opened and the switch 5 is closed to start the steady operation. With the above method, the output frequency of the frequency converter
It can be activated while keeping it below 50%.

[Problems to be solved by the invention]

Among the above-mentioned conventional techniques, the method using the starting electric motor has a large loss generated by the resistor provided on the secondary side of the starting electric motor, and the starting electric motor has the same shaft end as the current collecting ring of the AC excitation synchronous machine. However, there is a problem that the structure is complicated because it is provided in the.

Also, the method using the frequency converter for start-up has a problem that the equipment installation place becomes large because of the same device.

Further, in the conventional example of FIG. 6, it is necessary to operate the switchgear in order to switch the operation mode at around 50% of the synchronous speed. Because of this, there was a problem that it could not be started smoothly. This problem can be solved by using a circulating current type cycloconverter as a frequency converter. This is because in the case of the circulating current type cycloconverter, the output current frequency can be increased to near the AC system frequency. Therefore, in the conventional example shown in FIG. 6, the connection at the time of accelerating to about 50% of the synchronous speed is not changed. This is because it is possible to accelerate to near the synchronous speed. However, if a circulating current type cycloconverter is used, the capacity of the transformer for isolating from the AC system must be increased in proportion to the magnitude of the circulating current, and the transformers for the positive group thyristor converter and the negative group thyristor converter must be increased. There is a problem that the equipment becomes large by having to separate the coil winding.

An object of the present invention is an AC suitable for realizing a function of smoothly starting and accelerating to an AC excitation operating speed range using the AC excitation frequency converter without increasing the capacity of the AC excitation frequency converter. It is to provide an excitation generator motor.

[Means for solving problems]

The above-mentioned purpose focuses on the fact that the capacity of the frequency converter required at start-up is generally smaller than the capacity of the AC exciter frequency converter, and from the common insulation transformer winding that constitutes the non-circulating current type cycloconverter. One of the positive group thyristor converter and the negative group thyristor converter that are fed is opened from the transformer winding, and the two polarities that are fed from the other transformer windings have opposite polarities. Open the
This is achieved by using a circulating current type cycloconverter.

[Action]

In order to achieve the above object, the operation of each part when the circulating current type cycloconverter is used only at the time of starting will be described with reference to FIG.

In FIG. 7, the positive group thyristor converter composed of thyristors 9a and the positive group thyristor converter composed of thyristors 9b are fed by transformer windings 13a and 13b which are insulated from each other. On the other hand, a current limiting reactor 10a is provided between the negative group converter and the positive group converter composed of the thyristors 9c and 9d.
And 10b are connected. The cycloconverter connected in this manner operates as a non-circulating current type cycloconverter during normal AC excitation operation. At this time, switch 11
The a and 11b are closed and the switches 12a and 12b are opened. On the other hand, at the time of startup, the switches 11a and 11b are opened and the switches 12a and 12b are closed to operate as a circulating current type cycloconverter. As a result, only the converter composed of thyristors 9a operates as a positive group thyristor converter, and only the converter composed of thyristors 9d operates as a negative group thyristor converter. AC windings 13a and 1 to power these two converters
Since 3b is insulated from each other, circulating current can flow between the converters of the positive and negative groups. Circulating current is a current limiting reactor
Suppressed by 10a and 10b.

To open the thyristors 9b and 9c, the switches 11a and 1
Instead of providing 1b, there is a method of forcibly blocking the ignition signal to thyristors 9b and 9c.

According to the method explained above, the output voltage is reduced to about half by using the circulating current type cycloconverter, but it is possible to secure sufficient capacity for start-up.
The output frequency can be raised to a frequency close to the AC system.

〔Example〕

Hereinafter, embodiments of the present invention will be described with reference to the drawings. In FIG. 2, the AC excitation synchronous machine 1 is AC-excited by the frequency converters 14a, 14b, 14c. During normal operation, the switch 15 is closed and the switch 16 is opened to connect the primary side of the AC excitation synchronous machine 1 to the AC system. The control mode switch 17a is closed and 17b
Open the circuit. Open the control mode switch 18a and 18c, and
And 18d are closed.

In the above state, the slip phase signal θ _s obtained from the difference between the detection signal θ _v of the AC system voltage phase detector 19 and the detection signal θ _r of the rotation phase detector 20 is input to the current controller 21 as the phase signal θ. . On the other hand, the voltage controller 23 controls the current command signal I _d * so that the deviation between the voltage signal of the voltage detector 22 and the command value becomes zero.
Is output to the current control device 21. In addition, the active power detector 24
The power control device 25 outputs the current command signal I _q * to the current control device 21 so that the deviation between the detection signal and the command value becomes zero.
Further, the power control device 25 has a function of correcting the active power command signal when the detection signal of the rotation speed detection device 26 falls within the setting range or when the rate of change of the signal falls within the setting range. ing.

The current command signals I _q * and I _d * are current command values expressed in Cartesian coordinates whose origin is the center of rotation on the coordinate system that rotates with the phase signal θ. The current command for each secondary side phase is given by orthogonal projection onto a straight line on the stationary coordinate system having a direction corresponding to the phase difference from the reference winding.

At start-up, the switch 15 is opened, the switch 16 is closed, and the short circuit 27 short-circuits the primary side of the AC excitation synchronous machine 1. The embodiment shown in FIG. 2 shows an example in which the starting torque is easily generated through the resistor 27a. The control mode switch 17a is opened and 17b is closed. The control mode switches 18a and 18c are closed and 18b and 18d are opened.

In the above state, the sum of the detection signal θ _r of the rotational phase detector 20 and the slip phase command signal θ _t from the starting speed control device 28 is input to the current control device 21 as the phase signal θ. Here, the frequency of the slip phase signal θ _t is adjusted according to the torque command. Further, the current command signals I _q * and I _d * are configured so that the signal from the speed control device for start-up 28 is input to the current control device 21.

FIG. 1 shows the structure of one frequency converter 14a, 14b, 14c. Transformer winding 29,301,302 for insulation from AC system
With the three-phase AC voltage adjusted to a predetermined voltage as an input, an AC current is supplied to the secondary winding of the AC excitation synchronous machine 1 by two groups of antiparallel thyristor converters. When the normal AC excitation operation is performed with the configuration of FIG. 1, the switches 311 and 312 are closed, but are divided into two operation modes. The first operation mode is a case where two anti-parallel converter groups are operated in parallel, in which the switches 321 and 322 are closed and the switch 33 is opened. The positive group thyristor converter 341 and the negative group thyristor converter 351 operate as a first group non-circulating current type cycloconverter. Also thyristor converter 342
And 352 operate as a second group of non-circulating current type cycloconverters. The two cycloconverters consist of thyristor converters with the same specifications and are controlled so as to share the output current equally. Circulating current between the two groups of cycloconverters is suppressed by current limiting reactors 361 and 362. The current limiting reactors 361 and 362 are magnetically coupled so that a component supplied as an output current to the secondary winding has a low impedance and a circulating current component has a high impedance. The thyristor converters 341, 342, 351, 352 input the current signals I ₁ , I ₂ of each group detected by the current detectors 371, 372 to the current control device 21, and phase control the control voltage command signal and the gate blocking signal output from the current control device 21. Device 381,
Input to 382. Since the phase control device 381 for the first group and the phase control device 382 for the second group have exactly the same configuration, the function of the one for the first group will be described. The control voltage command signals EP ₁ and EN ₁ are reference signals for determining the thyristor firing phase of the positive group thyristor converter 341 and the negative group thyristor converter 351 respectively. When the gate blocking signal GP ₁ is level 1, all the firing pulses to the thyristor of the positive group thyristor converter 341 are blocked, and when GP ₁ is level 0, the firing pulse is generated at the timing determined by the control voltage command signal EP _1. Occurs. Gate block signal GN ₁ is configured to block all firing pulses to negative group thyristor converter 351 when at level 1.

Next, in the second operation mode, when the two groups of non-circulation type cycloconverters are operated in series, the switches 321 and 322 are opened and the switch 33 is closed. This results in current signals I ₁ and I ₂
Are both input to the current controller 21 as a measurement signal of the output current. Functionally, only one of the current signals I ₁ and I ₂ may be used.
The functions of the phase controllers 381 and 382 are the same as in the parallel operation.

FIG. 3 is a diagram showing an embodiment of the current control device 21, in which the start signal SW is maintained at level 0 in the normal operation mode. Signal SW
When the level is zero, the current command generator 39 operates. The current command generator 39 uses the current commands I _q * and I _d * and the phase signal θ to output the current command signals I _a *, I _b *, for each secondary side of the AC excitation synchronous machine 1.
Outputs I _c *. This output current command signal is input to the gate blocking signal generator 40 and the control voltage command signal generator 41. When the signal SW is at level 0, the switch 43 is closed by the switch 42 and the switch 43b is opened. As a result, the output current command signal and the detected current value I _a1 ,
A control voltage command signal is generated so that the deviations of I _a2 , I _b1 , I _b2 , I _c1 , and I _c2 become zero. When the two groups of non-circulating current type cycloconverters are in the parallel operation mode, the output current command value is multiplied by 1/2 by a mode switching signal (not shown) and then the deviation from the current detection signal is obtained.

The operation of the frequency converter 14 and the current control device 21 during normal operation has been described above with reference to FIGS. 1 and 3. Next, a case of operating as a circulating current type cycloconverter at the time of startup will be described.

In Fig. 1, the switches 311 and 312 are opened, and the thyristor converter 3
Pause 51 and 342. Switch 321,322 closed, switch
33 is opened and the positive group thyristor converter 341 and the negative group thyristor converter 352 operate as a circulating current type cycloconverter.

In FIG. 3, the activation signal SW becomes level 1 at the time of activation, and the switch 43a is opened and the switch 43b is closed by the switch operator 42. When the signal SW is at level 1, the starting current command generator 44 operates and the current command signals I _a1 *, I _a2 for operating as a circulating current type cycloconverter
Generates *, I _b1 *, I _b2 *, I _c1 *, I _c2 *. The operation of the control voltage command generator 41 is the same as in the normal operation, and the activation can be realized. When the signal SW is at level 1, the gate blocking signal generator always sets GP _a1 , GP _b1 , GP _c1 , GN _a2 , GN _b2 , GN _c2 to level 0 and GPa2,
GP _b2 , GP _c2 , GN _a1 , GN _b1 , and GN _c1 are held at level 1.

According to the present embodiment, particularly for a variable speed pumped storage power generation device, it is possible to realize a highly reliable AC excitation generator-motor device with a minimum device capacity. This is because, according to this embodiment, as described in Japanese Patent Application No. 60-80176, the two groups of cycloconverters are connected in parallel during the turbine operation, and the two groups of cycloconverters are connected in series during the pumping operation. As a result, high efficiency turbine operation and large pumping AFC capacity can be obtained while keeping the pump turbine runner diameter, AC excitation synchronous machine capacity, and cycloconverter capacity to a minimum. Further, according to the present embodiment, since the gate circuit to the thyristor converter which is inactive when operating as a circulating current type cycloconverter is blocked and the input circuit is opened at the same time, the positive group and negative group thyristor converters due to malfunctions are caused. From a short circuit between 2
High reliability can be obtained by protecting it. Theoretically, either the gate signal blocking or the input circuit opening can be omitted. Generally, the open circuit function of the input circuit is omitted and the switch 311
It is economically advantageous to omit and 312.

An embodiment of the second aspect of the present invention will be described below with reference to the drawings. The overall structure of the AC excitation generator-motor apparatus is the same as that shown in FIG. 2 described in the embodiment of claim 1, and the description thereof is omitted.

FIG. 4 shows the structure for one phase of the frequency converters 14a, 14b, 14c. Transformer winding 29,301,302 for insulation from AC system
Thus, the three-phase AC voltage is fed to the antiparallel thyristor converter. When performing normal AC excitation operation with the configuration of FIG. 4, open the output short-circuits 501, 502, connect the positive group thyristor converters 451 and 452 in series, and connect the negative group thyristor converters 461 and 462 in series. The positive and negative groups are connected by current limiting reactors 471 and 472. The current combiners 481 and 482 combine the input currents of the positive group thyristor converters 451 and 452 to combine the converter output currents. Current combiner 491,49 for negative group
2 is used. These output current composite values I ₁ and I ₂ are input to the current control device 21, and the control voltage command signal and the gate blocking signal output from the current control device 21 are applied to the phase control devices 481 and 4
It is configured to input to 82. Since the phase control device 481 for the positive side thyristor converter and the phase control device 482 for the negative side thyristor converter have exactly the same configuration, the function for the positive group will be described. The control voltage command signal EP serves as a reference signal for determining the thyristor firing phase of the positive group thyristor converter 451 and the positive group thyristor converter 452, respectively. Positive gate thyristor converter 451 when gate block signal GP ₁ is level 1
All firing pulses to the thyristor are blocked, and when GP ₁ is at level 0, the firing pulse is generated at the timing determined by the control voltage command signal EP. Gate blocking signal GP ₂ is configured to block all firing pulses to positive group thyristor converter 452 when at level 1.

FIG. 5 is a diagram showing another embodiment of the current control device 21, and only parts different from FIG. 3 will be described. Signal SW during normal operation
Is maintained at level 0, and the control voltage command signal generator 51 outputs signals to the positive and negative thyristor converters of each phase. Unlike the case of FIG. 3, since there is no mode for operating the two groups of non-circulating current type cycloconverters in parallel, it is not necessary to generate another control voltage command signal for the thyristor converters 451 and 452 of FIG. 4, for example. Absent. In addition, the current command value
It is not necessary to multiply by 1/2 to obtain the deviation from the current detection signal.

The operation of the frequency converter 14 and the current control device 21 during normal operation has been described above with reference to FIGS. 4 and 5. Next, a case of operating as a circulating current type cycloconverter at the time of startup will be described.

In FIG. 4, the output short circuits 501 and 502 are closed, and the thyristor converters 451 and 462 are deactivated. Positive group thyristor converter 452
The negative group thyristor converter 461 operates as a circulating current type cycloconverter.

In FIG. 5, the activation signal SW becomes level 1 at the time of activation, and the switch 43a is opened and the switch 43b is closed by the switch operator 42. When the signal SW is at level 1, the starting current command generator 44 operates and the current command signals I _a1 *, I _a2 for operating as a circulating current type cycloconverter
Generates *, I _b1 *, I _b2 *, I _c1 *, I _c2 *. The operation of the control voltage command generator 51 is the same as that during normal operation, and the startup can be realized. When the signal SW is at level 1, the gate block signal generator always sets GP _a1 , GP _b1 , GP _c1 , GN _a2 , GN _b2 , GN _c2 to level 1, GP _a2 ,
The GP _b2 , GP _c2 , GN _a1 , GN _b1 , and GN _c1 are held at level 0.

According to the present invention, even when the serial-parallel switching of the cycloconverter is not performed, smooth start-up can be realized simply by adding the output short circuiter.

〔The invention's effect〕

According to the present invention, during normal operation, AC excitation is performed by the non-circulating current type cycloconverter, and only when starting, the circulating current type cycloconverter is used to accelerate to the normal operating speed range by the circulating current type cycloconverter without using another power conversion device. Since there is no loss and the structure is not complicated, reliability is maintained, the installation location is small, and smooth starting is achieved. Further, since the capacity of the non-circulating current type cycloconverter determines the capacity of the thyristor for the frequency converter, there is an effect that the size of the frequency converter can be reduced.

[Brief description of drawings]

FIG. 1 is a diagram showing the configuration of a frequency converter according to an embodiment of the first aspect of the present invention, FIG. 2 is a diagram showing the overall configuration of the embodiment, and FIG. 3 is an embodiment of a current control system. FIG. 4 is a diagram showing a configuration of a frequency converter according to an embodiment of claim 2 of the present invention, FIG. 5 is a diagram showing an embodiment of a current control system, and FIG. 6 is a diagram showing a conventional example. FIG. 7 is a diagram showing the configuration, and FIG. 7 is a diagram for explaining the principle of the present invention. 1 …… AC excitation synchronous machine, 2,7 …… Transformer, 3,341,451 ……
Positive group thyristor converter, 4,342,452 …… Negative group thyristor converter, 361,362,471,472 …… Current limiting reactor, 501,502
...... Output short circuiter, 39 …… Current command generator, 44 …… Starting current command generator.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Akira Bando 3-1-1, Saiwaicho, Hitachi-shi, Ibaraki Hitachi Ltd. Hitachi factory (72) Inventor Akio Ito 5-chome, Omika-cho, Hitachi, Ibaraki No. 1 Incorporated company Hitachi Ltd. Omika factory (72) Inventor Osamu Nagura 3-1-1 1-1 Sachimachi, Hitachi city, Ibaraki prefecture Hitachi Ltd. Hitachi factory (72) Inventor Junichi Shiozaki Ichiaki Hitachi city, Ibaraki prefecture 3-1-1, Machi, Hitachi, Ltd., Hitachi Factory (72) Inventor: Shigehiro Agawa, 3--1, 1-1, Saiwaicho, Hitachi, Ibaraki Hitachi, Ltd., Hitachi, Ltd. (72) Inventor, Keiji Saito 3-1-1 Sachimachi, Hitachi City, Ibaraki Hitachi Ltd. Hitachi factory (72) Inventor Hiroshi Kashiwazaki 3-1-1 1-1 Sachimachi, Hitachi City, Ibaraki Hitachi Manufacturing Within the Hitachi Plant (72) inventor Onji Yozo Osaka, Osaka, Higashi-ku Honcho 4-chome 15 address of 1 Hitachi, Ltd. Kansai in the Branch

Claims (2)

[Claims] 1. An AC exciter synchronous machine whose primary side terminal is connected to an AC system via a first switch, and a transformer 3 for adjusting the AC system to a predetermined voltage for insulation from the AC system. A non-circulating current type cycloconverter composed of two sets of anti-parallel connection circuits of a positive group thyristor converter and a negative group thyristor converter, which receives a phase AC voltage as an input, converts an AC current into each phase on the secondary side of the AC excitation synchronous machine. A frequency converter for supplying a current by being connected to a secondary current command generator that generates an output current command value of a non-circulating current type cycloconverter that constitutes the frequency converter; and a secondary of the AC excitation synchronous machine. AC excitation power generation including a current detector that detects a current and a phase control device that controls an ignition phase of the thyristor converter so that a deviation between the secondary current command value and the secondary current detection value becomes zero. Electric equipment And a current limiting reactor provided between the positive group thyristor converter and the negative group thyristor converter, the short circuit device being connected to the primary side terminal of the AC excitation synchronous machine via a second switch. , The positive group thyristor converter and the negative group thyristor converter in each of the anti-parallel connection circuit of each one of the converter is suspended, the frequency converter to operate as a circulating current type cycloconverter, the thyristor converter An AC excitation generator-motor apparatus is provided with a starting current command generator that generates a current command signal that is supplied to a control voltage command signal generator that generates a control voltage command signal that determines the firing phase of the. 2. The output shunter according to claim 1, wherein an output short-circuiter is provided at an output terminal of the thyristor converter which is stopped during start-up, and the output short-circuiter is operated when operating as a circulating current type cycloconverter during start-up. An alternating-current excitation generator-motor device characterized by being configured to be short-circuited.