US3883792A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Optimum control system for minimizing harmonic effects in HVDC power converters
Assignee: CGEE ALSTHOM NORTH AMERICA Inc
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Filing: 1973-06-28
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Granted: 1975-05-13
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Expires: 1993-06-28
Abstract
Abstract A real-time system for reducing the effects of harmonics reflected onto the a. c. supply line of a High Voltage Direct Current power converter by continuous measurement of various current and voltage fundamental, harmonic and d. c. components as reflected onto the supply line, calculation of an overall harmonic performance index based upon the necessary ones of the measured components, and on-line control of the firing angles at which various switching functions occur in the HVDC power converter to optimize the value of the performance index.
Inventors
- 👤 Frederick J Ellert
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-25 08:44
CPC Classifications
H; H02; H02M; H02M1/00; H02M1/12; H02M7/00; H02M7/66; H02M7/68; H02M7/72; H02M7/75; H02M7/757; H02M7/7575; H02M1/126; Y; Y02; Y02E; Y02E60/00; Y02E60/60
Claims Analysis
Total Claims: 11
Claim 1
Independent Claim
192 words
In a system for controlling HVDC power converters connected to alternating voltage electric power lines, the HVDC converters comprising a plurality of controllable electric current conducting valves arranged to be periodically fired in a predetermined sequence in timed relation to the alternating voltage cycle, the firing angles at which said valves respectively are switched from nonconducting to conducting states being controllable, the alternating voltage on said lines having a certain fundamental frequency and a plurality of harmonic components which occur therein due to the switching action of said valves, the improvement comprising: a. detecting means for detecting said harmonic components of the alternating voltage on said lines and for providing an electrical representation of the magnitude of each of said harmonic components, b. calculating means responsive to said electrical representations for calculating performance indexes representing the degree of undesirability of a certain intensity of harmonic component occurrence, and c. control means responsive to said performance indexes operating to vary the relative firing angles of the respective ones of said valves for changing the value of said performance indexes toward an optimum value, thereby minimizing the undesirable effects of said harmonic component occurrence.
Claim 2
Dependent Claim
192 words
In a system for controlling HVDC power converters connected to alternating voltage electric power lines, the HVDC converters comprising a plurality of controllable electric current conducting valves arranged to be periodically fired in a predetermined sequence in timed relation to the alternating voltage cycle, the firing angles at which said valves respectively are switched from nonconducting to conducting states being controllable, the alternating voltage on said lines having a certain fundamental frequency and a plurality of harmonic components which occur therein due to the switching action of said valves, the improvement comprising: a. detecting means for detecting said harmonic components of the alternating voltage on said lines and for providing an electrical representation of the magnitude of each of said harmonic components, b. calculating means responsive to said electrical representations for calculating performance indexes representing the degree of undesirability of a certain intensity of harmonic component occurrence, and c. control means responsive to said performance indexes operating to vary the relative firing angles of the respective ones of said valves for changing the value of said performance indexes toward an optimum value, thereby minimizing the undesirable effects of said harmonic component occurrence.
Claim 3
Dependent Claim
26 words
A system according to claim 1 wherein said electric power lines comprise a polyphase alternating current system and wherein valves are provided for each phase thereof.
Claim 4
Dependent Claim
47 words
A system according to claim 2 wherein said valves are controlled rectifier devices and the system further includes firing time modulator means controlling the controlled rectifier devices and responsive to the control means for firing the controlled rectifier devices at firing angles controlled by said control means.
Claim 5
Dependent Claim
58 words
A system according to claim 3 wherein said detecting means comprises a plurality of tuned circuits tuned to pass signals of various harmonic frequencies and connected to measure harmonic values of current and voltage in each phase of the polyphase system, thereby providing said electrical representations representative of the harmonic values in each phase of the polyphase system.
Claim 6
Dependent Claim
60 words
A system according to claim 4 wherein said calculating means comprises: i. analog to digital converter means responsive to the electrical representations of the harmonic values for providing digital signals representative of the harmonic values, and ii. digital logic means responsive to said digital signals for solving equations including said digital signal values as parameters to derive said performance indexes.
Claim 7
Dependent Claim
56 words
A system according to claim 5 wherein said control means includes an optimizer responsive to the calculating means output and controlling said firing time modulator means in conjunction with other control inputs to the firing time modulator for optimizing the values of the performance indexes in accordance with a preset weighted program determined by user requirements.
Claim 8
Dependent Claim
69 words
A system according to claim 6 wherein the HVDC converters include a power transformer connected to said polyphase system and the performance indexes calculated by the calculating means include at least a term that is functionally dependent on the d. c. components in the transformer secondary windings, a telephone interference factor (TIF), a current harmonic factor (IT) and a voltage distortion factor (D) calculated accordIng to the following equations:
Claim 9
Dependent Claim
43 words
A system according to claim 2 wherein said control means includes an optimizer responsive to the calculating means and controlling the relative firing angles of the respective ones of said valves for changing the value of the performance indexes toward an optimum value.
Claim 10
Dependent Claim
40 words
A system according to claim 8 wherein the performance indexes calculated by the calculating means include at least a telephone interference factor (TIF), a current harmonic factor (IT) and a voltage distortion factor (D) calculated according to the following equations:
Claim 11
Dependent Claim
42 words
A system according to claim 9 wherein the performance indexes calculated by the calculating means further include a term that is functionally dependent on any d. c. component of the alternating currents in addition to the TIF, the IT and D factors.
References Cited (Backward Citations)
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1978-05-12 | 1978-11-11 | 1979-05-13 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1982-05-12 | 1982-11-11 | 1983-05-13 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1986-05-12 | 1986-11-11 | 1987-05-13 | $7700.00 | Window Closed / Lapsed |