Patent US4354800A successfully refreshed from Google Patents.
US4354800A
Expired / Lapsed
US
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Method of controlling pump turbine
Assignee: Hitachi Ltd
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Filing: 1979-04-05
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Granted: 1982-10-19
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Expires: 1999-04-05
Abstract
Abstract A method of controlling a pump-turbine having an S-section in its characteristic curve. The behavior of the operation point tracing up the S-section is judged and discriminated through detection of the rotation speed N of the pump-turbine or the acceleration dN/dt of the same. More specifically, it is judged that the operation point of the pump-turbine is tracing the S-section in the flow-rate reducing direction, through detections of the conditions that the acceleration dN/dt is materially negative and that the rotation speed N is greater than a predetermined speed. At the same time, it is judged that the operation point has commenced to trace the S-section in the flow-rate increasing direction, through detecting that the rotation speed has come down below the predetermined speed.
Inventors
- 👤 Takao Kuwabara
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-30 21:20
CPC Classifications
F; F03; F03B; F03B15/00; F03B15/02; F03B15/04; F03B15/06; F03B15/08; F03B15/12; Y; Y02; Y02E; Y02E10/00; Y02E10/20
Claims Analysis
Total Claims: 17
Claim 1
Independent Claim
82 words
A method of controlling a pump-turbine having an S-section in its characteristic curve, characterized in that wicket gates of said pump-turbine are controlled upon judging that the operation point of said pump-turbine has commenced to trace said S-section in a flow-rate increasing direction, said judgement being made through a detection of the fact that the rotation speed of said pump-turbine, during the tracing of said S-section up to its end in a flow-rate reducing direction, has come down below a predetermined speed.
Claim 2
Independent Claim
82 words
A method of controlling a pump-turbine having an S-section in its characteristic curve, characterized in that wicket gates of said pump-turbine are controlled upon judging that the operation point of said pump-turbine has commenced to trace said S-section in a flow-rate increasing direction, said judgement being made through a detection of the fact that the rotation speed of said pump-turbine, during the tracing of said S-section up to its end in a flow-rate reducing direction, has come down below a predetermined speed.
Claim 3
Dependent Claim
65 words
A method of controlling a pump-turbine having an S-section in its characteristic curve as in claim 1, characterized in that said wicket gates are closed, on condition that said judgement is made, at a rate greater than the rate at which said wicket gates are closed during the tracing up of said S-section by said operation point of said pump-turbine in the flow-rate reducing direction.
Claim 4
Independent Claim
138 words
A method of controlling a pump-turbine having an S-section in its characteristic curve, characterized by comprising the steps of: detecting that the rotation speed of said pump-turbine has increased beyond a predetermined speed which is higher than the rated speed, due to an acceleration of said pump-turbine after a removal or loss of the load; detecting that the rotation speed of said pump-turbine which has commenced to trace up said S-section in a flow-rate reducing direction within a short time after detection of said predetermined speed has come down below a preset speed; judging at least from the second of said foregoing two detections that the operation point of said pump-turbine has commenced to trace down said S-section in a flow-rate increasing direction; and then controlling the wicket gates of said pump-turbine upon said judgement having been made.
Claim 5
Independent Claim
138 words
A method of controlling a pump-turbine having an S-section in its characteristic curve, characterized by comprising the steps of: detecting that the rotation speed of said pump-turbine has increased beyond a predetermined speed which is higher than the rated speed, due to an acceleration of said pump-turbine after a removal or loss of the load; detecting that the rotation speed of said pump-turbine which has commenced to trace up said S-section in a flow-rate reducing direction within a short time after detection of said predetermined speed has come down below a preset speed; judging at least from the second of said foregoing two detections that the operation point of said pump-turbine has commenced to trace down said S-section in a flow-rate increasing direction; and then controlling the wicket gates of said pump-turbine upon said judgement having been made.
Claim 6
Independent Claim
74 words
A method of controlling a pump-turbine having an S-section in its characteristic curve, characterized in that the wicket gates of said pump-turbine are controlled upon judging that the operation point of said pump-turbine is tracing said S-section in the flow-rate reducing direction, said judgement being made through detections of the facts that the acceleration dN/dt of said pump-turbine is negative and that the rotation speed N of said pump-turbine has exceeded a predetermined speed.
Claim 7
Independent Claim
74 words
A method of controlling a pump-turbine having an S-section in its characteristic curve, characterized in that the wicket gates of said pump-turbine are controlled upon judging that the operation point of said pump-turbine is tracing said S-section in the flow-rate reducing direction, said judgement being made through detections of the facts that the acceleration dN/dt of said pump-turbine is negative and that the rotation speed N of said pump-turbine has exceeded a predetermined speed.
Claim 8
Dependent Claim
75 words
A method of controlling a pump-turbine having an S-section in its characteristic curve as claimed in claim 4, comprising the subsequent step of determining that said operation point of said pump-turbine has commenced to trace said S-section in the flow-rate increasing direction, through a detection of the fact that said rotation speed of said pump-turbine has returned below said predetermined speed, and adjusting the manner in which said wicket gates are controlled in response thereto.
Claim 9
Dependent Claim
56 words
A method of controlling a pump-turbine having an S-section in its characteristic curve as claimed in claim 1, 2, 3, 4 or 5, wherein said predetermined speed at which tracing of the S-section in the flow-rate increasing direction has commenced is changed in response to a change in the level of load imposed on said pump-turbine.
Claim 10
Dependent Claim
22 words
A method according to claim 3, wherein a rapid closing of said wicket gates is commenced when said judgement has been made.
Claim 11
Dependent Claim
34 words
A method according to claim 3 or 7, wherein said preset speed is independently adjustable and lower relative to said predetermined speed and said judgement is made on the basis of both said detections.
Claim 12
Dependent Claim
30 words
A method according to claim 3, wherein said judgement is made on the basis of a detection that pump acceleration dn/dt is materially negative in addition to said second detection.
Claim 13
Dependent Claim
30 words
A method according to claim 9, wherein, between said acceleration detection and the detection of said rotation speed having come down below said preset speed, said wicket gates are opened.
Claim 14
Dependent Claim
34 words
A method according to claim 9, wherein, between said acceleration detection and the detection of said rotation speed having come down below said preset speed, a closing speed of said wicket gates is reduced.
Claim 15
Dependent Claim
60 words
A method according to claim 9, wherein said predetermined and preset speeds are the same, said detecting of the rotation speed of the pump-turbine having increased beyond said predetermined speed being performed by switching of a speed switch and the detecting of said rotation speed having come down below said preset speed being performed by resetting of said speed switch.
Claim 16
Dependent Claim
19 words
A method according to claim 9 or 12, wherein the acceleration detection is performed by an acceleration detecting switch.
Claim 17
Dependent Claim
26 words
A method according to claim 1 or 11 or 12, wherein a rapid closing of said wicket gates is commenced when said judgement has been made.
References Cited (Backward Citations)
US3403888A
Cited
US4201925A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1985-10-18 | 1986-04-19 | 1986-10-19 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1989-10-18 | 1990-04-19 | 1990-10-19 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1993-10-18 | 1994-04-19 | 1994-10-19 | $7700.00 | Window Closed / Lapsed |