US6297977B1
Expired / Lapsed
US
⏱️ 0.0 years remaining
Parallel operation of multiple generators
Assignee: Hybrid Power Generation Systems LLC
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Filing: 2000-09-12
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Granted: 2001-10-02
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Expires: 2020-09-12
Abstract
Abstract A power generation system includes multiple generators that are operated in parallel. An inverter of one of the generators is always operated in voltage mode. Inverters of the other generators are switched between voltage and current modes.
Inventors
- 👤 Colin E. Huggett
- 👤 David C. Lewis
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-02 10:52
CPC Classifications
H; H02; H02M; H02M7/00; H02M7/42; H02M7/44; H02M7/48; H02M7/493
Claims Analysis
Total Claims: 24
Claim 1
Independent Claim
59 words
A power generating system comprising: a group of generators, each generator including an inverter that is operable in a voltage mode and a current mode; and a control system for switching at least one inverter between a current mode and a voltage mode, the control system switching between the two modes in response to a change in demanded power.
Claim 2
Dependent Claim
59 words
A power generating system comprising: a group of generators, each generator including an inverter that is operable in a voltage mode and a current mode; and a control system for switching at least one inverter between a current mode and a voltage mode, the control system switching between the two modes in response to a change in demanded power.
Claim 3
Dependent Claim
15 words
The system of claim 1 , wherein each generator is part of a microturbine generator.
Claim 4
Dependent Claim
56 words
The system of claim 1 , wherein at least one of the generators is designated as a follower; wherein the control system operates a maximum number of follower inverters in current mode at maximum power output without exceeding the demanded power; and wherein the control system operates the remaining inverters of active generators in voltage mode.
Claim 5
Dependent Claim
21 words
The system of claim 3 , wherein the control system uses a synchronization signal to phase-lock the inverters of the followers.
Claim 6
Dependent Claim
38 words
The system of claim 4 , wherein one of the generators is designated as a master; wherein the synchronization signal is provided by the master; and wherein the inverter of the master is always operated in voltage mode.
Claim 7
Dependent Claim
38 words
The system of claim of claim 5 , wherein one of the generators is designated as a slave, the slave providing the synchronization signal if the master fails; and wherein the slave is always operated in voltage mode.
Claim 8
Dependent Claim
29 words
The system of claim 5 , further comprising a plurality of sensors for determining when the inverters should be switched between current and voltage modes, the sensors being cascaded.
Claim 9
Dependent Claim
20 words
The system of claim 1 , further comprising a voltage regulator for sending the same voltage command to each inverter.
Claim 10
Dependent Claim
31 words
The system of claim 1 , wherein the control system operates all of the inverters in voltage mode when demanded power is below the full power-generating capacity of a single generator.
Claim 11
Dependent Claim
68 words
The system of claim 1 , further comprising at least one current sensor for comparing line current to first and second thresholds; wherein a corresponding inverter is switched from voltage mode to current mode when the first threshold is crossed; wherein the corresponding inverter is switched from current mode to voltage mode when the second threshold is crossed; and wherein the first and second thresholds are not equal.
Claim 12
Dependent Claim
29 words
The system of claim 1 , further comprising a plurality of sensors for determining when the inverters should be switched between current and voltage modes, the sensors being cascaded.
Claim 13
Dependent Claim
27 words
The method of claim 11 , wherein each sensor corresponds to an inverter; and wherein each inverter is switched solely on information provided by its corresponding sensor.
Claim 14
Dependent Claim
15 words
The system of claim 1 , wherein the inverters are switched according to a hierarchy.
Claim 15
Independent Claim
62 words
A method of using a set of generators to supply a power demand, the generators having inverters, the method comprising the steps of: operating as many generators as possible at maximum power output without exceeding demanded power, wherein the inverters of the generators providing maximum power output are operated in current mode; and operating inverters of the remaining generators in voltage mode.
Claim 16
Independent Claim
62 words
A method of using a set of generators to supply a power demand, the generators having inverters, the method comprising the steps of: operating as many generators as possible at maximum power output without exceeding demanded power, wherein the inverters of the generators providing maximum power output are operated in current mode; and operating inverters of the remaining generators in voltage mode.
Claim 17
Dependent Claim
28 words
The method of claim 14 , further comprising the step of switching selected inverters between the current and voltage modes in response to changes in the power demand.
Claim 18
Dependent Claim
28 words
The method of claim 14 , further comprising the step of supplying a reference signal to the generators, and phase-locking outputs of the inverters to the reference signal.
Claim 19
Dependent Claim
21 words
The method of claim 14 , further comprising the step of sending the same voltage command to each of the inverters.
Claim 20
Dependent Claim
66 words
The method of claim 14 , wherein the generators supply power to a distribution line; wherein at least one generator inverter is switched from voltage mode to current mode when line current crosses a first threshold; and wherein the at least one generator inverter is switched from current mode to voltage mode when line current crosses a second threshold, the first and second thresholds being different.
Claim 21
Dependent Claim
38 words
The method of claim 14 , further comprising the step of sensing line current at the output of each generator; and wherein each inverter is switched solely according to sensed current on the output of the corresponding generator.
Claim 22
Dependent Claim
17 words
The method of claim 14 , wherein the generator inverters are independently switched according to a hierarchy.
Claim 23
Independent Claim
93 words
A method of using a group of microturbine generators to supply current to a load, the method comprising the steps of: operating one of the microturbine generators in the group as a master, the master always being operated in a voltage mode; operating other microturbine generators in the group as followers; combining power outputs of the master and the followers; and switching a follower from voltage mode to current mode when load balance is greater than that follower's maximum power rating, the follower then being operated in current mode at maximum power output.
Claim 24
Independent Claim
93 words
A method of using a group of microturbine generators to supply current to a load, the method comprising the steps of: operating one of the microturbine generators in the group as a master, the master always being operated in a voltage mode; operating other microturbine generators in the group as followers; combining power outputs of the master and the followers; and switching a follower from voltage mode to current mode when load balance is greater than that follower's maximum power rating, the follower then being operated in current mode at maximum power output.
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USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 2004-10-01 | 2005-04-02 | 2005-10-02 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 2008-10-01 | 2009-04-02 | 2009-10-02 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2012-10-01 | 2013-04-02 | 2013-10-02 | $7700.00 | Window Closed / Lapsed |