System for connecting and synchronizing a supplemental power source to a power grid
First Claim
1. A method for connecting a supplemental power supply having three-phase output voltages to a power grid having three-phase grid voltages, the supplemental power supply having a DC power source, an electronic inverter, a controller, a three-phase AC line filter and a three-phase circuit contactor, said method comprising the steps of:
- detecting the three-phase grid voltages;
converting the three-phase grid voltages into voltages on a d-q plane;
detecting the three-phase output voltages of the supplemental power supply;
converting the detected output voltages into voltages on a d-q plane;
determining a voltage command to control the three-phase output voltages as close as possible to the three-phase grid voltages.
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Accused Products
Abstract
A system (10) and method (100) for connecting and synchronizing a supplemental power supply (10) and a power grid. The present invention detects current feedback signals ia and ib and grid phase voltage input signals Ua
96 Citations
17 Claims
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1. A method for connecting a supplemental power supply having three-phase output voltages to a power grid having three-phase grid voltages, the supplemental power supply having a DC power source, an electronic inverter, a controller, a three-phase AC line filter and a three-phase circuit contactor, said method comprising the steps of:
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detecting the three-phase grid voltages;
converting the three-phase grid voltages into voltages on a d-q plane;
detecting the three-phase output voltages of the supplemental power supply;
converting the detected output voltages into voltages on a d-q plane;
determining a voltage command to control the three-phase output voltages as close as possible to the three-phase grid voltages. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8)
converting the detected grid voltages to a rotating vector on an α
-β
plane; and
deriving a rotating angle from said grid voltage vector.
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4. The method as claimed in claim 3 wherein said step of converting the three-phase output voltages into voltages on a d-q plane further comprises the steps of converting the detected output voltages into a rotating vector.
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5. The method as claimed in claim 1 wherein said step of detecting the grid voltages further comprises detecting the grid voltages with a y-connected resistor network and the step of detecting the output voltages further comprise detecting the output voltages with a y-connected resistor network.
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6. The method as claimed in claim 1 wherein said step of detecting the grid voltages further comprises detecting the grid voltages with a y-connected transformer and the step of detecting the output voltages further comprise detecting the output voltages with a y-connected transformer.
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7. The method as claimed in claim 1 further comprising the step of calculating the change in a rotating angle over time to determine a rotating angle frequency.
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8. The method as claimed in claim 7 further comprising the step of determining a phase sequence for the grid voltage from the sign of said rotating angle frequency.
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9. A method for connecting a supplemental power supply having three-phase output voltages, Ua
— -
p, Ub
— p, and Uc— p, to a power grid having three-phase grid voltages, Ua— g, Ub— g, and Uc— g, the supplemental power supply having a DC power source, an electronic inverter, a controller, a three-phase AC line filter and a three-phase circuit contactor, said method comprising the steps of;detecting the three-phase grid voltages, Ua — g, Ub— g, and Uc— g;
converting the detected grid voltages to a rotating vector, Uα — g, Uβ— g, on an α
-β
. plane;
deriving a rotating angle, γ
u— g, from said grid voltage vector;
converting said grid voltage vector into three-phase voltages on a d-q plane according to;
- View Dependent Claims (10, 11, 12, 13, 14, 15, 16, 17)
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p, Ub
Specification