초록 ▼

A method of controlling the output inverter of a microsource in a distributed energy resource system is disclosed. Embodiments of the invention include using unit or zone power controllers that reduce the operating frequency of the inverter to increase its unit output power. Preferred embodiments in

A method of controlling the output inverter of a microsource in a distributed energy resource system is disclosed. Embodiments of the invention include using unit or zone power controllers that reduce the operating frequency of the inverter to increase its unit output power. Preferred embodiments includes methods wherein the inverter reaches maximum output power and minimum operating frequency at the same time, and further comprising using a voltage controller implementing a voltage vs. reactive current droop. Other aspects of this embodiment relate to an inverter that implements such methods, and a microsource containing such an inverter. These methods can be extended to control inverters in a plurality of microsources, organized in a single zone or in a plurality of zones.

대표청구항 ▼

What is claimed is: 1. A method of controlling distributed energy resources, the method comprising: providing a microsource, wherein the microsource is located in a microgrid, and further wherein the micro source is configured to deliver a power P1 at a frequency ω1; operating the microsource

What is claimed is: 1. A method of controlling distributed energy resources, the method comprising: providing a microsource, wherein the microsource is located in a microgrid, and further wherein the micro source is configured to deliver a power P1 at a frequency ω1; operating the microsource in a grid mode in which the microsource is connected to a utility grid, wherein during operation in the grid mode the frequency ω1 is approximately equal to a frequency ωo and the power P1 is equal to a power P1o, wherein the frequency ωo is an operating frequency of the utility grid; and transferring the microsource from the grid mode to an island mode such that the microsource is disconnected from the utility grid, wherein ω1 is equal to ωisland and P1 is equal to P1island during the island mode; wherein ωisland>ω0, and P1island<P10 if the microgrid was exporting power prior to the transfer from the grid mode to the island mode; wherein ωisland<ω0, and P1island>P10 if the microgrid was importing power prior to the transfer from the grid mode to the island mode; and wherein the microsource delivers a maximum power output level P1max at a frequency ωmin, wherein the microsource has a slope switch frequency ωswitch, and ω island ≈ ω 0 ⁡ ( ω 0 - ω min P ⁢ ⁢ 1 0 - P ⁢ ⁢ 1 max ) ⁢ ( P ⁢ ⁢ 1 0 - P ⁢ ⁢ 1 island ) . ⁢ if ⁢ [ ω 0 - ( ω 0 - ω min P ⁢ ⁢ 1 0 - P ⁢ ⁢ 1 max ) ⁢ ( P ⁢ ⁢ 1 0 - P ⁢ ⁢ 1 island ) ] < ω max . 2. The method of claim 1, wherein the microsource delivers a maximum power output level P1max at a frequency ωmin, and wherein ω island ≈ ω 0 ⁡ ( ω 0 - ω min P ⁢ ⁢ 2 0 - P ⁢ ⁢ 2 max ) ⁢ ( P ⁢ ⁢ 2 0 - P ⁢ ⁢ 2 island ) . 3. The method of claim 1, wherein ⁢ ⁢ ω island ≈ ω 0 - ( ω 0 - ω min P ⁢ ⁢ 1 0 - P ⁢ ⁢ 1 max ) ⁢ ( P ⁢ ⁢ 1 0 - P ⁢ ⁢ 1 island ) if ⁢ [ ω 0 - ( ω 0 - ω min P ⁢ ⁢ 1 0 - P ⁢ ⁢ 1 max ) ⁢ ( P ⁢ ⁢ 1 0 - P ⁢ ⁢ 1 island ) ] ≥ ω switch . 4. The method of claim 1, wherein the microsource delivers a maximum output level P1max at a frequency ωmin wherein the microsource has a maximum operating frequency ωmax, wherein ⁢ ⁢ ω island ≈ ω 0 - ( ω 0 - ω min P ⁢ ⁢ 1 0 - P ⁢ ⁢ 1 max ) ⁢ ( P ⁢ ⁢ 1 0 - P ⁢ ⁢ 1 island ) if ⁢ [ ω 0 - ( ω 0 - ω min P ⁢ ⁢ 1 0 - P ⁢ ⁢ 1 max ) ⁢ ( P ⁢ ⁢ 1 0 - P ⁢ ⁢ 1 island ) ] < ω max ; and wherein ω island ≈ ω max ⁢ ⁢ if ⁢ [ ω 0 - ( ω 0 - ω min P ⁢ ⁢ 1 0 - P ⁢ ⁢ 1 max ) ⁢ ( P ⁢ ⁢ 1 0 - P ⁢ ⁢ 1 island ) ] ≥ ω max . 5. The method of claim 1, wherein the microsource delivers a maximum power output level P1max at a frequency ωmin, wherein the microsource has a slope switch frequency ωswitch, wherein the microsource has a maximum operating frequency ωmax, wherein ⁢ ⁢ ω island ≈ ω 0 - ( ω 0 - ω min P ⁢ ⁢ 1 0 - P ⁢ ⁢ 1 max ) ⁢ ( P ⁢ ⁢ 1 0 - P ⁢ ⁢ 1 island ) if ⁢ [ ω 0 - ( ω 0 - ω min P ⁢ ⁢ 1 0 - P ⁢ ⁢ 1 max ) ⁢ ( P ⁢ ⁢ 1 0 - P ⁢ ⁢ 1 island ) ] < ω switch ; wherein ⁢ ⁢ ω island < ω 0 - ( ω 0 - ω min P ⁢ ⁢ 1 0 - P ⁢ ⁢ 1 max ) ⁢ ( P ⁢ ⁢ 1 0 - P ⁢ ⁢ 1 island ) if ⁢ ⁢ ω switch ≤ [ ω 0 - ( ω 0 - ω min P ⁢ ⁢ 1 0 - P ⁢ ⁢ 1 max ) ⁢ ( P ⁢ ⁢ 1 0 - P ⁢ ⁢ 1 island ) ] < ω max ; and wherein ω island ≈ ω max ⁢ ⁢ if ⁢ [ ω 0 - ( ω 0 - ω min P ⁢ ⁢ 1 0 - P ⁢ ⁢ 1 max ) ⁢ ( P ⁢ ⁢ 1 0 - P ⁢ ⁢ 1 island ) ] ≥ ω max . 6. The method of claim 1, wherein the microsource delivers a maximum power output level P1max at a frequency ωmin, wherein the microsource has a minimum power output level P1min, wherein P ⁢ ⁢ 1 island ≈ P ⁢ ⁢ 1 0 - ( P ⁢ ⁢ 1 0 - P ⁢ ⁢ 1 max ω 0 - ω min ) ⁢ ( ω 0 - ω island ) if P ⁢ ⁢ 1 0 - ( P ⁢ ⁢ 1 0 - P ⁢ ⁢ 1 max ω 0 - ω min ) ⁢ ( ω 0 - ω island ) > P ⁢ ⁢ 1 min ; and ⁢ ⁢ wherein P ⁢ ⁢ 1 island ≈ P ⁢ ⁢ 1 min if P ⁢ ⁢ 1 0 - ( P ⁢ ⁢ 1 0 - P ⁢ ⁢ 1 max ω 0 - ω min ) ⁢ ( ω 0 - ω island ) ≤ P ⁢ ⁢ 1 min . 7. The method of claim 6, wherein the microsource includes power storage such that P1min<0. 8. The method of claim 1, further comprising: providing a second microsource, wherein the second microsource is located in the microgrid, and further wherein the second microsource is configured to deliver a power P2 at a frequency ω2; operating the second microsource in the grid mode in which the second microsource is connected to the utility grid, wherein during operation in the grid mode, the frequency ω2 is approximately equal to the frequency ωo and the power P2 is equal to a power P2o; and transferring the second microsource from the grid mode to the island mode such that the second microsource is disconnected from the utility grid, wherein ω2 is approximately equal to ωisland and P2 is equal to P2island during operation in the island mode; wherein ωisland>ωo and P2island<P2o if the microgrid was exporting power prior to the transfer from the grid mode to the island mode; and wherein ωisland<ωo and P2island>P2o if the microgrid was importing power prior to the transfer from the grid mode to the island mode. 9. The method of claim 8, wherein (P1island−P10)≈(P2island−P20) such that an amount of change of P1 when the microsource is transferred from the grid mode to the island mode is approximately equal to an amount of change of P2 when the second microsource is transferred from the grid mode to the island mode. 10. The method of claim 8, further comprising providing a power slope m, and wherein ωisland≈ω0−m(P10−P1island)≈ω0−m(P20−P2island). 11. The method of claim 8, further comprising providing a power slope m, wherein the microsource has a minimum operating frequency ωmin, wherein ωisland≈ω0−m(P10−P1island)>ωmin; and wherein ωisland≈ωmin if ω0−m (P10−P1island)≦ωmin. 12. The method of claim 8, further comprising providing a power slope m, wherein the microsource has a maximum operating frequency ωmax , wherein ωisland≈ω0−m(P10−P1island)>ωmax; and wherein ωisland≈ωmax if ω0−m(P10−P1island)≦ωmax. 13. The method of claim 8, further comprising providing a power slope m, wherein the microsource has a minimum operating frequency ωmin and a maximum operating frequency ωmax , wherein ωisland≈min if ω−m(P10−P1island )≦ωminwherein ωisland≈ωmax−m(P10−P1island)>ωmin; and wherein ωisland≈ωmax if ω0−m (P10−P1island)≦ωmax. 14. The method of claim 1, wherein the microsource has a maximum power output level P1max , a minimum power output level P1min, and a minimum operating frequency ωmin, and wherein ω island ≈ ω 0 - ( ω 0 - ω min P ⁢ ⁢ 1 min - P ⁢ ⁢ 1 max ) ⁢ ( P ⁢ ⁢ 1 0 - P ⁢ ⁢ 1 island ) . 15. The method of claim 1, wherein the microsource has a maximum power output level P1max, a minimum power output level P1min, and a minimum operating frequency ωmin, Wherein ⁢ P ⁢ ⁢ 1 island ≈ P ⁢ ⁢ 1 0 - ( P ⁢ ⁢ 1 min - P ⁢ ⁢ 1 max ω 0 - ω min ) ⁢ ( ω 0 - ω island ) if P ⁢ ⁢ 1 0 - ( P ⁢ ⁢ 1 min - P ⁢ ⁢ 1 max ω 0 - ω min ) ⁢ ( ω 0 - ω island ) > P ⁢ ⁢ 1 min and ⁢ ⁢ wherein P ⁢ ⁢ 1 island ≈ ⁢ P ⁢ ⁢ 1 min ⁢ if P ⁢ ⁢ 1 0 - ( P ⁢ ⁢ 1 min - P ⁢ ⁢ 1 max ω 0 - ω min ) ⁢ ( ω 0 - ω island ) ≤ P ⁢ ⁢ 1 min . 16. The method of claim 1, wherein the microsource has a maximum power output level P1max, a minimum power output level P1min, and a minimum operating frequency ωmin, wherein P ⁢ ⁢ 1 island ≈ ⁢ P ⁢ ⁢ 1 0 - ( P ⁢ ⁢ 1 min - P ⁢ ⁢ 1 max ω 0 - ω min ) ⁢ ( ω 0 - ω island ) if P ⁢ ⁢ 1 0 - ( P ⁢ ⁢ 1 min - P ⁢ ⁢ 1 max ω 0 - ω min ) ⁢ ( ω 0 - ω island ) < P ⁢ ⁢ 1 max and ⁢ ⁢ wherein P ⁢ ⁢ 1 island ≈ ⁢ P ⁢ ⁢ 1 max if P ⁢ ⁢ 1 0 - ( P ⁢ ⁢ 1 min - P ⁢ ⁢ 1 max ω 0 - ω min ) ⁢ ( ω 0 - ω island ) ≤ P ⁢ ⁢ 1 max . 17. The method of claim 1 wherein the microsource has a maximum power output level P1max, a minimum power output level P1min, and a minimum operating frequency ωmin, wherein P ⁢ ⁢ 1 island ≈ ⁢ P ⁢ ⁢ 1 min if P ⁢ ⁢ 1 0 - ( P ⁢ ⁢ 1 min - P ⁢ ⁢ 1 max ω 0 - ω min ) ⁢ ( ω 0 - ω island ) ≤ P ⁢ ⁢ 1 min ; wherein P ⁢ ⁢ 1 island ≈ ⁢ P ⁢ ⁢ 1 0 - ( P ⁢ ⁢ 1 min - P ⁢ ⁢ 1 max ω 0 - ω min ) ⁢ ( ω 0 - ω island ) if P ⁢ ⁢ 1 min < P ⁢ ⁢ 1 0 - ( P ⁢ ⁢ 1 min - P ⁢ ⁢ 1 max ω 0 - ω min ) ⁢ ( ω 0 - ω island ) < P ⁢ ⁢ 1 max ; and ⁢ ⁢ wherein P ⁢ ⁢ 1 island ≈ ⁢ P ⁢ ⁢ 1 max if P ⁢ ⁢ 1 0 - ( P ⁢ ⁢ 1 min - P ⁢ ⁢ 1 max ω 0 - ω min ) ⁢ ( ω 0 - ω island ) ≥ P ⁢ ⁢ 1 max . 18. A microgrid comprising: a microsource comprising a power controller configured to control a frequency ω1 and a power P1 of the microsource; operate the microsource in a grid mode in which the microsource is connected to a utility grid, and wherein the frequency ω1 is approximately equal to an operating frequency ωo of the utility grid and the power P1 is equal to P1o; and transfer the microsource to operate in an island mode in which the microsource is disconnected from the utility grid, wherein the frequency ω1 is equal to ωisland and the power P1 is equal to P1island in the island mode; wherein ωisland>ω0, and P1island<P10 if the microgrid was exporting power prior to the transfer from the grid mode to the island mode; wherein ωisland<ω0, and P1island>P10 if the microgrid was importing power prior to the transfer from the grid mode to the island mode; and wherein the microsource delivers a maximum power output level P1max at a frequency ωmin, wherein the microsource has a slope switch frequency ωswitch, wherein ω island ≈ ω 0 - ( ω 0 - ω min P ⁢ ⁢ 1 0 - P ⁢ ⁢ 1 max ) ⁢ ( P ⁢ ⁢ 1 0 - P ⁢ ⁢ 1 island ) if ⁢ [ ω 0 - ( ω 0 - ω min P ⁢ ⁢ 1 0 - P ⁢ ⁢ 1 max ) ⁢ ( P ⁢ ⁢ 1 0 - P ⁢ ⁢ 1 island ) ] < ω switch ; 19. The microgrid of claim 18, wherein the microsource delivers a maximum power output level P1max at a frequency ωmin, and wherein ω island ≈ ω 0 - ( ω 0 - ω min P ⁢ ⁢ 2 0 - P ⁢ ⁢ 2 max ) ⁢ ( P ⁢ ⁢ 2 0 - P ⁢ ⁢ 2 island ) . 20. The microgrid of claim 18, wherein ω island < ω 0 - ( ω 0 - ω min P ⁢ ⁢ 1 0 - P ⁢ ⁢ 1 max ) ⁢ ( P ⁢ ⁢ 1 0 - P ⁢ ⁢ 1 island ) if ⁢ [ ω 0 - ( ω 0 - ω min P ⁢ ⁢ 1 0 - P ⁢ ⁢ 1 max ) ⁢ ( P ⁢ ⁢ 1 0 - P ⁢ ⁢ 1 island ) ] ≥ ω switch . 21. The microgrid of claim 18, wherein the microsource delivers a maximum power output level P1max at a frequency ωmin, wherein the microsource has a slope switch frequency ωswitch, wherein the microsource has a maximum operating frequency ωmax, ⁢ wherein ω island ≈ ω 0 - ( ω 0 - ω min P ⁢ ⁢ 1 0 - P ⁢ ⁢ 1 max ) ⁢ ( P ⁢ ⁢ 1 0 - P ⁢ ⁢ 1 island ) ⁢ ⁢ if ⁢ [ ω 0 - ( ω 0 - ω min P ⁢ ⁢ 1 0 - P ⁢ ⁢ 1 max ) ⁢ ( P ⁢ ⁢ 1 0 - P ⁢ ⁢ 1 island ) ] < ω switch ; wherein ω island < ω 0 - ( ω 0 - ω min P ⁢ ⁢ 1 0 - P ⁢ ⁢ 1 max ) ⁢ ( P ⁢ ⁢ 1 0 - P ⁢ ⁢ 1 island ) if ⁢ ⁢ ω switch ≤ [ ω 0 - ( ω 0 - ω min P ⁢ ⁢ 1 0 - P ⁢ ⁢ 1 max ) ⁢ ( P ⁢ ⁢ 1 0 - P ⁢ ⁢ 1 island ) ] < ω max ; wherein ω island ≈ ω max ⁢ ⁢ if ⁢ [ ω 0 - ( ω 0 - ω min P ⁢ ⁢ 1 0 - P ⁢ ⁢ 1 max ) ⁢ ( P ⁢ ⁢ 1 0 - P ⁢ ⁢ 1 island ) ] ≥ ω max . 22. The microgrid of claim 18, wherein the microsource delivers a maximum power output level P1max at a frequency ωmin, wherein the microsource has a minimum power output level P1min, wherein P ⁢ ⁢ 1 island ≈ P ⁢ ⁢ 1 0 - ( P ⁢ ⁢ 1 0 - P ⁢ ⁢ 1 max ω 0 - ω min ) ⁢ ( ω 0 - ω island ) if ⁢ ⁢ P ⁢ ⁢ 1 0 - ( P ⁢ ⁢ 1 0 - P ⁢ ⁢ 1 max ω 0 - ω min ) ⁢ ( ω 0 - ω island ) > P ⁢ ⁢ 1 min ; and wherein P ⁢ ⁢ 1 island ≈ P ⁢ ⁢ 1 min ⁢ ⁢ if ⁢ ⁢ P ⁢ ⁢ 1 0 - ( P ⁢ ⁢ 1 0 - P ⁢ ⁢ 1 max ω 0 - ω min ) ⁢ ( ω 0 - ω island ) ≤ P ⁢ ⁢ 1 min . 23. The microgrid of claim 22, wherein the microsource further comprises a power storage unit such that P1min<0. 24. The microgrid of claim 18, wherein the microsource has a maximum power output level P1max, a minim urn power output level P1min, and a minimum operating frequency ωmin, and wherein ω island ≈ ω 0 - ( ω 0 - ω min P ⁢ ⁢ 1 min - P ⁢ ⁢ 1 max ) ⁢ ( P ⁢ ⁢ 1 0 - P ⁢ ⁢ 1 island ) . 25. The microgrid of claim 18, wherein the microsource has a maximum power output level P1max, a minimum power output level P1min, and a minimum operating frequency ωmin, P ⁢ ⁢ 1 island ≈ P ⁢ ⁢ 1 0 - ( P ⁢ ⁢ 1 min - P ⁢ ⁢ 1 max ω 0 - ω min ) ⁢ ( ω 0 - ω island ) if ⁢ ⁢ P ⁢ ⁢ 1 0 - ( P ⁢ ⁢ 1 min - P ⁢ ⁢ 1 max ω 0 - ω min ) ⁢ ( ω 0 - ω island ) > P ⁢ ⁢ 1 min ; and ⁢ ⁢ wherein P ⁢ ⁢ 1 island ≈ P ⁢ ⁢ 1 min ⁢ if ⁢ P ⁢ ⁢ 1 0 - ( P ⁢ ⁢ 1 min - P ⁢ ⁢ 1 max ω 0 - ω min ) ⁢ ( ω 0 - ω island ) ≤ P ⁢ ⁢ 1 min . 26. The microgrid of claim 25, wherein the microsource further comprises a power storage unit such that P1min<0. 27. The microgrid of claim 18, wherein the microsource has a maximum power output level P1max, a minimum power output level P1min, and a minimum operating frequency ωmin, P ⁢ ⁢ 1 island ≈ P ⁢ ⁢ 1 0 - ( P ⁢ ⁢ 1 min - P ⁢ ⁢ 1 max ω 0 - ω min ) ⁢ ( ω 0 - ω island ) if ⁢ ⁢ P ⁢ ⁢ 1 0 - ( P ⁢ ⁢ 1 min - P ⁢ ⁢ 1 max ω 0 - ω min ) ⁢ ( ω 0 - ω island ) < P ⁢ ⁢ 1 max ; and ⁢ ⁢ wherein P ⁢ ⁢ 1 island ≈ P ⁢ ⁢ 1 max ⁢ if ⁢ P ⁢ ⁢ 1 0 - ( P ⁢ ⁢ 1 min - P ⁢ ⁢ 1 max ω 0 - ω min ) ⁢ ( ω 0 - ω island ) ≥ P ⁢ ⁢ 1 max .