JPH05176568A - Starting method of rotary electric machine - Google Patents

Abstract

PURPOSE:To simplify the starter of a superconducting synchronous machine by a method wherein damper start is applied in a low speed range in which the liquid surface of coolant is not formed and thyristor start is applied in a high speed range in which the liquid surface is formed. CONSTITUTION:A superconducting rotor is housed inside stator windings 7. The superconducting field windings 5 of the superconducting rotor and coolant are provided inside a normal temperature damper 1. The damper start of the rotor is performed by the rotary magnetic field 8 of the windings 7 and a magnetic field induced by an eddy current in the normal temperature damper 1 which is induced by the rotary magnetic field 8. With this constitution, the construction of a starter can be simplified and a shaft length can be reduced significantly, so that the size of a building can also be reduced.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for starting a rotary electric machine and an apparatus therefor, and more particularly to a method suitable for starting a thyristor of a superconducting synchronous machine.

[0002]

2. Description of the Related Art When a superconducting rotating electric machine is used as a synchronous phase modulator / synchronous generator, it is a starting method that is a problem.

There is no problem with a steam turbine that can be constantly supplied with driving steam from a boiler, but as with a gas turbine or a combined cycle in which a gas turbine and a steam turbine are combined, up to the ignition rotational speed of the gas turbine. A starting method for a system that cannot obtain a driving force, and further, for a system having no driving source such as a synchronous phase shifter becomes a serious problem.

In a gas turbine and a combined cycle, as shown in FIG. 5 (a), torque converter starting (torque converter starting), which brings a starting motor and a torque converter to a rated rotation speed, is currently the mainstream, and a synchronous adjustment is performed. In the phase machine, the induction motor and A shown in FIG.
Induction start with a VAF device is now commonly used.

However, in starting the torque converter or starting the induction motor, a starting motor, a torque converter, and an induction motor must be added for starting, and the shaft system becomes too long. In addition, there is a problem that the torque converter cannot be upsized.

Therefore, recently, a thyristor starting system using a synchronous generator and a synchronous phase shifter as a synchronous motor at the time of starting has attracted attention. 5 (b) and 6 (b)
As shown in FIG. 3, the thyristor starting is performed by a thyristor starting power supply 17 including an AVAF device on the stator of the generator and the phase shifter.
This is a method of generating a rotating magnetic field with a variable frequency and generating a starting torque in synchronization with the rotor magnetic field created by the field current of the rotor. The starting motor, torque converter, and induction motor are not required, and the shaft length is significantly increased. Shortened.

Even in the superconducting synchronous machine, if this thyristor start is applied, it is considered that, in combination with the compactness of the superconducting machine, the axial length is greatly shortened, which is very useful for downsizing of the building and simplification of the components. Be done.

[0008]

When the thyristor start is applied to the superconducting synchronous machine, the problem is cooling of the superconducting field winding in the rotor during low speed rotation. In order to energize the field winding, the field winding must be superconducting, and the field winding needs to be immersed in a refrigerant such as liquid helium.

In the case of the superconducting rotor 5, the liquid helium 16 is attached to the inner surface of the rotor by centrifugal force as shown in FIG. 4, and the field winding arranged on the outer diameter side of the rotor is immersed in the liquid helium. After sufficiently cooled, an exciting current can be passed.
Transition speed Nc where liquid helium clings to the inner surface of the rotor
Is the rated speed No. 3000/3600 (RPM)
It is about 500 (RPM) with respect to (50/60 (Hz)).

When the rotational speed is higher than Nc, an exciting current can be passed, so that the thyristor can be started. However, when the rotational speed is lower than Nc, the excitation of the rotor is difficult and the thyristor start becomes difficult.

For this reason, it is conceivable that the starting electric motor is used up to the number of revolutions Nc at which the liquid surface of liquid helium is formed, and then the thyristor is started, but the capacity is small, but it is for starting. Since the number of components such as the electric motor increases and the shaft length extends, the merits of starting the thyristor cannot be utilized. As a rotary electric machine of this type, there is JP-A-3-128663.

An object of the present invention is to provide a method for starting a rotary electric machine that can start a thyristor without adding auxiliary equipment such as a starting electric motor.

[0013]

According to the starting method of the present invention,
Up to the rotational speed Nc at which the liquid level of the refrigerant is formed, the damper is started by the induction torque induced in the room temperature damper of the superconducting rotor, and then the thyristor is started by exciting the field winding after the liquid level is formed. The starting method is to bring the rated speed No. to.

As another solution of the present invention, in order to prevent thermal bending of the rotor, a normally installed turning device is used and forced at a low rotational speed of about 5 (RPM) during turning. Liquid helium, etc. (liquid nitrogen etc.)
The refrigerant is injected, and it is intermittently immersed in the refrigerant and excited by a current smaller than the rated current that can be conducted to start the thyristor.After the liquid level is formed, the thyristor starts by exciting to the rated current. The starting method is to bring the rated speed No.

[0015]

According to the starting method of the present invention, in addition to the thyristor starting device such as the AVAF device required for starting the thyristor, no auxiliary starting electric motor or the like is required, and the starting speed to the rated speed is started. It is possible to

That is, up to the rotational speed at which the liquid surface of the refrigerant is formed, the rotational magnetic field generated by the stator accelerates the induction torque by the induction torque in the room temperature damper, and after the liquid surface is formed, The field is excited, and the rotating magnetic field and synchronizing force work to increase the speed to the rated speed.

In another method, a refrigerant is injected during turning. Refrigerant collects in the lower part of the rotor, but the field winding is turning and is therefore intermittently cooled by the refrigerant. Therefore, it is excited as much as possible with a current smaller than the rated current and synchronized with the rotating magnetic field. After the liquid surface of the refrigerant is formed, it is excited by the rated current and the speed is increased to the rated speed with a stronger synchronous force.

[0018]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described in detail below with reference to the drawings.

FIG. 1 is a sectional view of a superconducting rotor showing an embodiment of the present invention. There is a vessel 6 having a room temperature damper 1 and a low temperature damper 2 in which a superconducting field winding 5 held by a winding mounting shaft 3 and a wedge 4 is housed.

The superconducting rotor is in a cooled state during low speed turning of about 5 RPM. But,
Since the refrigerant has not been injected yet and the refrigerant has not accumulated inside the winding mounting shaft, the field is not excited. At that time,
When a starting current of a proper frequency is supplied from a thyristor starting power source composed of an AVAF device to the three-phase winding 7 of the stator outside the rotor, a rotating magnetic field 8 is generated on the rotor. The rotating magnetic field 8 induces an eddy current 9 and the induced magnetic field 10 on the room-temperature damper 1, and an induction torque acts between the rotating magnetic field 8 and the induced magnetic field 10 to start the damper and accelerate the rotor. The number of rotations is enough to reach the liquid level (about 500
RPM), then inject the refrigerant into the rotor,
The field winding is immersed in the coolant and an exciting current is passed. When the exciting current flows, a field magnetic field is formed, so that the field magnetic field and the rotating magnetic field 8 are synchronized with each other to generate a synchronizing force. Gradually raise the frequency of the thyristor starting power supply, and finally reach the rated frequency of 50/6.
If it goes up to 0 Hz, the rotor will be speeded up to the rated speed of 3000/3600 RPM in synchronization with it.

FIG. 2 shows a torque generated when the damper of FIG. 1 is started, when the rotor is in a stationary state, that is, at a frequency corresponding to 0 (Hz) with respect to the frequency of the three-phase current supplied from the thyristor starting power source. The relative values of the loss 12 of the room temperature damper, the field winding, and the loss 13 of the low temperature damper are plotted.

As can be seen from this, the torque 11 reaches its maximum at about 10 (Hz), and it can be seen that the loss of the damper and the field winding portion is still sufficiently small.

That is, at the time of starting the damper before starting the thyristor synchronous start, it is preferable to drive the damper at a frequency of about 10 (Hz) where the torque is maximum and the loss is sufficiently small. Of course, the rotation speed increases, and the rotation speed of the rotor is 5 (H
z), if a rotating magnetic field is generated at 15 (Hz), the rotating magnetic field of 15-5 = 10 (Hz) is generated on the rotor, and optimization is performed.

This is illustrated in FIG. The horizontal axis represents the rotational speed (RPM) of the rotor, and the vertical axis represents the frequency of the thyristor starting power supply. Number of rotations at which the liquid surface of the refrigerant is formed 50
The damper is started without excitation until 0 RPM. The power supply frequency f _B at that time is the number of revolutions f of the rotor (converted to Hz) plus about 10 (Hz) of the optimum frequency. That is, f _B = f rotor + 10 (Hz).
After 500 RPM, the field is excited and the normal thyristor starts.

The frequency for generating the maximum torque shown in FIG. 2 can be controlled to some extent by the structure and material of the damper. If this frequency is set too high, the loss will increase, so it is desirable to select a low frequency of 10 (Hz) or less.

Further, as shown in FIG. 3, when the damper is started, f _B
= F rotor +10 (Hz) may be optimized and the engine may not be started, but may be started with the power supply frequency f _B kept constant at 10 (Hz), for example.

By the way, in this method, it is possible to perform the turning with the induction torque by the thyristor starting power supply, and at that time, the turning device can be deleted. Next, a method different from the above will be described.

As shown in FIG. 4A, the rotor is 5R.
During turning at about PM, the coolant 1b is forcibly injected. As shown in FIG. 4A, the refrigerant accumulates in the lower part of the rotor and cools only part of the field winding 5. However, the rotor is turning, and about 5 times a minute,
Immersed in a refrigerant. In this state, the field is excited with a current that is smaller than the rated current and that can be excited. For example, about 1/2 to 1/3 of the rating. The thyristor synchronous start is applied by the rotor field generated there. When the refrigerant has a transition rotational speed Nc (Fig. 4 (b)) and sticks to the inner surface of the rotor to form a liquid level (Fig. 4 (c)), the field winding 5
Is completely immersed in the refrigerant. In this case, since the field winding 5 is completely cooled, it is possible to excite up to the rated current and perform the thyristor synchronous start.

[0029]

According to the present invention, at the time of starting the superconducting synchronous machine, it is not necessary to additionally add a starting electric motor, a torque converter, etc. to the shaft system, and the structure of the starting device can be simplified.
It is possible to greatly reduce the length of the shaft system. Also, the building where the synchronous machine is installed can be made smaller accordingly.

[Brief description of drawings]

FIG. 1 is a cross-sectional view of a superconducting rotor that is an embodiment of the present invention.

FIG. 2 is a characteristic diagram showing a relationship between a power supply frequency at the time of starting the damper of FIG. 1 and a relative value of a loss of an induction torque damper part.

FIG. 3 is a characteristic diagram showing the starting method of FIG.

FIG. 4 is a cross-sectional view showing the behavior of the refrigerant inside the superconducting rotor.

FIG. 5 is an explanatory diagram showing a conventional combined cycle starting method.

FIG. 6 is an explanatory diagram showing a method for starting a conventional synchronous phase modulator.

[Explanation of symbols]

1 ... Room temperature damper, 2 ... Low temperature damper, 3 ... Winding mounting shaft, 4
… Wedges, 5… Superconducting field windings, 6… Vessels, 7…
Stator three-phase winding, 8 ... rotating magnetic field, 9 ... induced current, 10 ...
Induced magnetic field, 11 ... Induction torque, 12 ... Room temperature damper loss (loss), 13 ... Field winding, low temperature damper loss (loss), 14 ... Power supply frequency, 15 ... Rotation speed, 16 ...
Refrigerant, 17 ... Thyristor starting power supply (AVAF).

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Kiyoshi Yamaguchi 4026 Kuji Town, Hitachi City, Ibaraki Prefecture Hitachi Research Laboratory, Nitate Manufacturing Co., Ltd.

Claims (6)

[Claims] 1. A method for starting a superconducting synchronous machine comprising a superconducting field winding and a vessel, a damper, etc. for accommodating the superconducting field winding, wherein the rotation is such that a liquid level of a refrigerant for cooling the superconducting field winding is formed. Up to the rated number of revolutions by thyristor starting, after the liquid level of the refrigerant has been formed, the field winding is excited and the field winding is not excited. A method for starting a rotating electric machine, characterized by: 2. The method of starting a rotating electric machine according to claim 1, wherein the frequency of the external starting power supply is fixed to a certain value when the damper is started. 3. The method for starting a rotary electric machine according to claim 1, wherein the difference between the frequency of the external starting power source and the rotation frequency of the rotor is fixed to a certain value when the damper is started. 4. The damper material according to claim 1,
A rotating electric machine characterized by optimizing the structure so that the maximum torque generated at the time of starting the damper is generated when the difference between the frequency of the external starting power supply and the rotation frequency of the rotor is 10 Hz or less. How to start. 5. A method of starting a rotating electric machine according to claim 1, wherein the damper starting device is used to perform turning of the rotating machine. 6. A method for starting a superconducting synchronous machine comprising a superconducting field winding, a vessel for accommodating the superconducting field winding, a damper, etc., wherein a refrigerant is injected into a rotor during turning, and the liquid level of the refrigerant is increased. Is lower than the rated current up to the number of revolutions at which the field winding is formed, but after the field winding is excited by exciting the field winding with a current that can be conducted and the liquid level of the refrigerant is formed, the field winding is turned on. A method for starting a rotating electric machine, characterized by exciting up to the rated current and increasing the speed to the rated speed by starting the thyristor.