JPH03251073A - Turning unit for superconducting generator - Google Patents

Abstract

PURPOSE:To prevent distortion at a rotor section due to thermal imbalance by sustaining high speed turning drive of a rotor, until inner cooling liquid is evaporized, upon tripping of a drive unit. CONSTITUTION:Upon function of an overcurrent relay 14 due to short circuit in the main circuit of a generator, for example, liquid helium supply to a superconducting field winding is interrupted and a generator circuit breaker 13 and a field circuit breaker 16 are tripped. Upon confirmation of tripping of the generator circuit breaker 13 and the field circuit breaker 16, a drive stop command is provided. At this time, a high speed rotation turning command is provided on condition that the liquid helium exists in the superconducting field winding and the temperature of the field winding is low, and a turning unit 19 keeps the rotational speed of the rotor of a superconducting generator 11 at such level as the liquid helium is brought centrifugally into tight contact with the field winding thus maintaining a uniform liquid level around the rotor.

Description

DETAILED DESCRIPTION OF THE INVENTION [Object of the Invention] (Industrial Application Field) The present invention relates to a control device for a superconducting generator that cools superconducting windings using a cooling liquid.

(Prior art) Generally, the rotor section (hereinafter referred to as rotor) inside a superconducting generator has a field winding disposed within a heat insulating vacuum layer, and the inside of the field winding is used for cooling. It has a structure that holds liquid.

A conceptual cross-sectional view of such a rotor is shown in FIG. The rotor includes a superconducting field winding 2 disposed inside a rotating body l formed airtight. The superconducting field winding 2 is also constructed airtight, and liquid helium is sealed inside to cool the winding portion. A space 3 between the rotating body 1 and the superconducting field winding 2 is evacuated by a vacuum pump (not shown) for heat insulation. Further, a plurality of temperature detectors 4 are arranged in the winding portion to check the temperature.

With this configuration, while the superconducting generator is in operation, the rotating body 1 and the superconducting generator R2 rotate integrally. At this time, Fig. 4 (a
) (A-A sectional view in Figure 3), liquid helium 5 supplied from the outside into the superconducting field winding 2 adheres to the inner surface of the superconducting field winding 2 on average due to centrifugal force. At the same time, the vaporized gas helium 6 accumulates inside, and the superconducting magnetizing winding 2 portion is uniformly cooled.

(Problem to be Solved by the Invention) However, when an accident occurs and the superconducting generator is tripped, as shown in FIG. Due to the decrease in centrifugal force, it accumulates in the lower part, and only gas helium 6 remains in the upper part. As a result, only the lower part of the field winding mounting shaft 7 is cooled unnecessarily,
An extreme temperature difference occurs between the upper and lower parts of the rotor, including the superconducting field windings 2. As a result, there is a problem in that stress is generated and the field winding mounting shaft 7 and the superconducting field winding 2 are distorted.

One object of the present invention is to provide a turning device for a superconducting generator that does not cause distortion to the rotor even when the generator is tripped due to an accident.

[Structure of the Invention (Means for Solving the Problems)] The present invention provides a method for cooling the rotor while the cooling liquid of the superconducting field winding remains when the drive machine that drives the rotor trips due to an accident. The lowest rotational speed (usually several tens of
It is equipped with a circuit that performs high-speed turning at 0 rotations) and switches to normal low-speed turning after all the cooling medium has evaporated.

(Function) When a superconducting generator is tripped due to an accident, the generator circuit breaker and excitation circuit breaker are opened, the supply of cooling liquid to the superconducting field winding is stopped, and the drive machine is tripped.
By maintaining the rotational speed of the rotor at a specified rotational speed through high-speed turning until the cooling liquid evaporates, distortion of the rotor due to thermal imbalance is prevented.

Furthermore, after the cooling liquid evaporates, only distortion occurs due to the rotor's own weight, so there is no need for high-speed turning, and instead switching to low-speed turning prevents distortion of the rotor.

(Embodiment) Hereinafter, an embodiment of the present invention will be described with reference to a schematic system diagram in FIG. 1 and a partial block diagram within a control device in FIG. 2.

In FIG. 1, the rotor of the superconducting generator 11 is the drive unit 1.
2, and a turning device 19 consisting of a turning motor etc. is further connected to the rotor portion, and its armature winding is connected to the system bus via a generator breaker 13, and the generator is also An overcurrent relay 14 is provided in front of the device 13. In addition, the field winding 1slX15 of the superconducting generator 11 includes a field breaker I6, an excitation transformer 17,
It is connected to the system bus through an excitation circuit breaker 18.

FIG. 2 shows a block diagram of a partial control section in the control device of the superconducting generator 11. During normal operation of the superconducting generator 11, various vJ commands are issued from the control block (not shown in the figure), and the power is generated. The machine breaker 13, the field circuit breaker 16, and the excitation circuit breaker 18 are closed, and the rotor of the superconducting generator 11 is driven to the rated rotation by the driver 12. Furthermore, liquid helium 5 is fed into the superconducting field winding 2 in the rotor to maintain superconducting power generation operation.

In this state, if the overcurrent relay 14 operates due to a short circuit in the main circuit of the generator (20), a command to stop the supply of liquid helium is generated (22), and the liquid helium 5 is supplied into the superconducting field winding 2. At the same time, the generator circuit breaker 13
, trips the field circuit breaker 16 (23.24). Next, tripping of the generator circuit breaker 13 and the field circuit breaker 16 is confirmed via the AND circuit 25, and the active machine stop command 21
Output. At this time, on condition that liquid helium 5 exists in the superconducting field winding 2 and the field winding temperature is low (26 outputs), a high-speed turning command is generated via the AND circuit 27 (28). The turning device 19 maintains the rotor rotational speed of the superconducting generator 11 at a rotational speed at which the liquid helium 5 can be brought into close contact with the field winding 2 by centrifugal force, so that a uniform liquid level can be maintained around the rotor.

As a result, even when the superconducting generator 11 is tripped, the liquid helium 5 inside the superconducting field winding 2 is removed as shown in Fig. 4 (a).
) can be maintained in the state shown in

Furthermore, liquid helium 5 attached to the inner surface of the superconducting field winding 2
When the temperature of the superconducting field winding 2 increases, the temperature detector 4 detects this and becomes a high temperature state (26 output inversion).
A low speed turning command is generated via the ND circuit 29.
0), the rotation of the rotor of the superconducting generator 11 is switched to a low speed at which distortion due to the rotor's own weight does not occur.

In this way, in the superconducting generator 11, even if the drive unit 12 trips due to an accident or the like, the rotation of the rotor of the superconducting generator 11 is maintained at a specified value by high-speed turning, and the field winding 16 is maintained by the centrifugal force. By preventing liquid helium 5, which is a cooling medium, from becoming unbalanced within the rotor, it is possible to solve the problem of rotor distortion due to thermal imbalance of the field windings.

In addition, in the embodiment of the present invention, an example was shown in which the temperature sensor was used to detect that the liquid helium had evaporated, but it is also possible to detect that the liquid helium level has disappeared using the liquid level detector and switch the turning speed. is also possible.

[Effects of the Invention] As explained above, according to the present invention, when the drive machine is tripped due to an accident, the rotor continues to rotate at high speed until the cooling liquid inside is vaporized. It becomes possible to prevent distortion from occurring in the rotor section due to unbalance.

[Brief explanation of drawings]

Fig. 1 is a schematic system diagram of a superconducting generator device to which the control device of the present invention is applied, Fig. 2 is a partial block diagram of a superconducting generator control device showing an embodiment of the present invention, and Fig. 3 is a general system diagram of a superconducting generator device to which the control device of the present invention is applied. A cross-sectional view of the rotor part of a typical superconducting generator, Fig. 4(a), (
b) is a sectional view taken along line A-^ of the rotor portion. 11...Superconducting generator, 12...Driver, 13...
- Generator circuit breaker, 15... Field winding, 16... Field circuit breaker, 19... Turning device.

Claims (3)

[Claims] (1) In a turning device for a superconducting generator equipped with a rotor section consisting of a vacuum layer and a superconducting winding section disposed within the vacuum layer and holding a cooling liquid inside, high-speed and low-speed rotation are possible. a turning motor having several switches; a temperature detector for detecting the temperature of the superconducting winding portion; and a temperature detector for detecting the temperature of the superconducting winding portion; A turning device for a superconducting generator, comprising means for rotating at high speed. (2) The turning device for a superconducting generator according to claim 1, wherein the rotor section is rotated at low speed turning when the temperature of the superconducting winding section is higher than a set value. (3) The turning device for a superconducting generator according to claim 1 or 2, further comprising a liquid level gauge in place of the temperature detector.