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NZ760097B2 - Method and system for extracting excess power - Google Patents

Method and system for extracting excess power

Info

Publication number
NZ760097B2
NZ760097B2 NZ760097A NZ76009718A NZ760097B2 NZ 760097 B2 NZ760097 B2 NZ 760097B2 NZ 760097 A NZ760097 A NZ 760097A NZ 76009718 A NZ76009718 A NZ 76009718A NZ 760097 B2 NZ760097 B2 NZ 760097B2
Authority
NZ
New Zealand
Prior art keywords
power
energy storage
converter
output
controller
Prior art date
Application number
NZ760097A
Other versions
NZ760097A (en
Inventor
Gysler Castelino
Apurva Somani
Anup Thapa
Xiaorong Xia
Original Assignee
Dynapower Company Llc
Filing date
Publication date
Application filed by Dynapower Company Llc filed Critical Dynapower Company Llc
Priority claimed from PCT/US2018/032711 external-priority patent/WO2018213273A1/en
Publication of NZ760097A publication Critical patent/NZ760097A/en
Publication of NZ760097B2 publication Critical patent/NZ760097B2/en

Links

Classifications

    • G—PHYSICS
    • G05—CONTROLLING; REGULATING
    • G05B—CONTROL OR REGULATING SYSTEMS IN GENERAL; FUNCTIONAL ELEMENTS OF SUCH SYSTEMS; MONITORING OR TESTING ARRANGEMENTS FOR SUCH SYSTEMS OR ELEMENTS
    • G05B19/00—Programme-control systems
    • G05B19/02—Programme-control systems electric
    • G05B19/04—Programme control other than numerical control, i.e. in sequence controllers or logic controllers
    • G05B19/042—Programme control other than numerical control, i.e. in sequence controllers or logic controllers using digital processors
    • G—PHYSICS
    • G05—CONTROLLING; REGULATING
    • G05B—CONTROL OR REGULATING SYSTEMS IN GENERAL; FUNCTIONAL ELEMENTS OF SUCH SYSTEMS; MONITORING OR TESTING ARRANGEMENTS FOR SUCH SYSTEMS OR ELEMENTS
    • G05B2219/00—Program-control systems
    • G05B2219/20—Pc systems
    • G05B2219/26—Pc applications
    • G05B2219/2639—Energy management, use maximum of cheap power, keep peak load low
    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02J—CIRCUIT ARRANGEMENTS OR SYSTEMS FOR SUPPLYING OR DISTRIBUTING ELECTRIC POWER; SYSTEMS FOR STORING ELECTRIC ENERGY
    • H02J2300/00—Systems for supplying or distributing electric power characterised by decentralized, dispersed, or local generation
    • H02J2300/20—The dispersed energy generation being of renewable origin
    • H02J2300/22—The renewable source being solar energy
    • H02J2300/24—The renewable source being solar energy of photovoltaic origin
    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02J—CIRCUIT ARRANGEMENTS OR SYSTEMS FOR SUPPLYING OR DISTRIBUTING ELECTRIC POWER; SYSTEMS FOR STORING ELECTRIC ENERGY
    • H02J2300/00—Systems for supplying or distributing electric power characterised by decentralized, dispersed, or local generation
    • H02J2300/20—The dispersed energy generation being of renewable origin
    • H02J2300/22—The renewable source being solar energy
    • H02J2300/24—The renewable source being solar energy of photovoltaic origin
    • H02J2300/26—The renewable source being solar energy of photovoltaic origin involving maximum power point tracking control for photovoltaic sources
    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02J—CIRCUIT ARRANGEMENTS OR SYSTEMS FOR SUPPLYING OR DISTRIBUTING ELECTRIC POWER; SYSTEMS FOR STORING ELECTRIC ENERGY
    • H02J3/00—Circuit arrangements for AC mains or AC distribution networks
    • H02J3/28—Arrangements for balancing of the load in a network by storage of energy
    • H02J3/32—Arrangements for balancing of the load in a network by storage of energy using batteries with converting means
    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02J—CIRCUIT ARRANGEMENTS OR SYSTEMS FOR SUPPLYING OR DISTRIBUTING ELECTRIC POWER; SYSTEMS FOR STORING ELECTRIC ENERGY
    • H02J3/00—Circuit arrangements for AC mains or AC distribution networks
    • H02J3/38—Arrangements for parallely feeding a single network by two or more generators, converters or transformers
    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02J—CIRCUIT ARRANGEMENTS OR SYSTEMS FOR SUPPLYING OR DISTRIBUTING ELECTRIC POWER; SYSTEMS FOR STORING ELECTRIC ENERGY
    • H02J3/00—Circuit arrangements for AC mains or AC distribution networks
    • H02J3/38—Arrangements for parallely feeding a single network by two or more generators, converters or transformers
    • H02J3/381—Dispersed generators
    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02J—CIRCUIT ARRANGEMENTS OR SYSTEMS FOR SUPPLYING OR DISTRIBUTING ELECTRIC POWER; SYSTEMS FOR STORING ELECTRIC ENERGY
    • H02J3/00—Circuit arrangements for AC mains or AC distribution networks
    • H02J3/38—Arrangements for parallely feeding a single network by two or more generators, converters or transformers
    • H02J3/46—Controlling of the sharing of output between the generators, converters, or transformers
    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02J—CIRCUIT ARRANGEMENTS OR SYSTEMS FOR SUPPLYING OR DISTRIBUTING ELECTRIC POWER; SYSTEMS FOR STORING ELECTRIC ENERGY
    • H02J7/00—Circuit arrangements for charging or depolarising batteries or for supplying loads from batteries
    • H02J7/34—Parallel operation in networks using both storage and other DC sources, e.g. providing buffering
    • H02J7/35—Parallel operation in networks using both storage and other DC sources, e.g. providing buffering with light sensitive cells
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
    • Y02E10/00—Energy generation through renewable energy sources
    • Y02E10/50—Photovoltaic [PV] energy
    • Y02E10/56—Power conversion systems, e.g. maximum power point trackers
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
    • Y02E60/00—Enabling technologies; Technologies with a potential or indirect contribution to GHG emissions mitigation
    • Y02E60/16—Mechanical energy storage, e.g. flywheels or pressurised fluids

Abstract

power system for connecting a power source (110), an energy storage unit (140) and a grid (150) includes a power inverter (120), an energy storage power converter (130) and a controller. The power inverter is electrically coupled to the power source through a DC bus and converts DC power from the DC bus to AC power output to the grid. The power converter is electrically coupled between the DC bus and the energy storage unit and stores power in the energy storage unit and discharges power from the energy storage unit. The controller controls the power converter to store excess power from the power source that cannot be output to the grid because of inverter curtailment, e.g. clipping, in the energy storage unit, and control the energy storage power converter to discharge power stored in the energy storage unit to the power inverter to output to the grid.

Claims (13)

Claims:
1. A power system for connecting a power source, an energy storage unit and a grid, the power system comprising a power inverter electrically coupled to the power source through a DC bus, wherein the power inverter converts DC power from the DC bus to AC power output to the grid; an energy e power converter electrically coupled between the DC bus and the energy storage unit, wherein the energy storage power converter stores power in the energy e unit and discharges power from the energy e unit; and a controller for lling the energy e power converter to capture excess power from the power source while maintaining the inverter near the inverter's maximum output power, the controller being configured to: control the energy storage power converter to store excess power from the power source that cannot be output to the grid in the energy storage unit; control the energy storage power converter to discharge power stored in the energy storage unit to the power inverter to output to the grid. includes: determining whether the power inverter is not curtailed; and when the power inverter is not curtailed: ining whether an output power of the power source has decreased; and adjusting a discharge power d for commanding the energy storage power converter to discharge an amount of power from the energy storage unit according to whether the output power of the power source has decreased, wherein the controller is configured to ively adjust the discharge power command by a predetermined power discharge adjustment value whose sign is reversed from positive to negative or from ve to positive according to whether the output power of the power source has decreased.
2. The power system of claim 1, wherein the controller being configured to control the energy storage power converter to capture excess power from the power source comprises the controller being configured to: determine if the power inverter is curtailed; when the power inverter is curtailed, increase a charge command of the power converter to store excess power in the energy storage unit; and when the power inverter is not curtailed, decrease a charge command of the power converter.
3. The power system of claim 1 wherein the controller is a converter controller for controller the energy storage power converter, and the controller being ured to control the energy storage power converter to capture excess PV power from the PV array includes the controller being configured to: autonomously detect curtailment on the power inverter without input from a power inverter controller; and when curtailment is detected, control the energy storage power converter to store the excess power in the energy storage unit up to the maximum power source power point.
4. The power system of claim 1, wherein the controller is a converter ller for lling the energy storage power converter, and the controller being configured to control the energy storage power converter to capture excess PV power from the PV array comprises the control system being configured to: determine a change in an output power of the energy storage power converter; determine a change in a voltage at the DC bus; adjust a high voltage limit on the DC bus according to the change in the output power of the energy e power converter and the change in the e at the DC
5. The power system of claim 1, wherein the controller being configured to control the energy storage power converter to discharge power stored in the energy storage unit to the power er to output to the grid includes the controller being ured to discharge power from the energy e unit while giving priority to any power available from the power source.
6. The power system of claim 5, wherein the controller being configured to adjust the power being discharged from the energy storage unit according to whether the output power of the power source has decreased includes the controller being configured to adjust a discharge power command for the energy storage power ter to discharge an amount of power by a power discharge adjustment value whose sign is changed according to whether the output power of the power source has decreased.
7. The power system of claim 1, wherein the power source is a photovoltaic power source, and the controller being configured to control the energy storage power converter to discharge power stored in the energy storage unit to the power inverter to output to the grid includes the controller being ured to control the energy storage power converter to e the power output of the photovoltaic power source.
8. The power system of claim 7, wherein the ller emulates the photovoltaic power source through a look up table mmed to emulate the power-voltage characteristics of the photovoltaic power source.
9. The power system of claim 7, wherein the controller emulates the photovoltaic power source by controlling a power command of the energy storage unit power ter based on a droop parameter.
10. The power system of claim 1, wherein the ller is a converter ller of the energy storage unit converter, and the converter controller communicates with a controller of the power inverter to obtain information about the output power of the power inverter.
11. A method of ing excess power from a power source in a power system comprising a power inverter coupled to the power source through a DC bus, and an energy storage power converter coupled between the DC bus and an energy storage unit, the method comprising: autonomously detecting curtailment on the power inverter without utilizing information concerning the operation of the power inverter, wherein autonomously detecting curtailment includes: ining a change in an output power of the energy storage power converter; determining a change in a voltage at the DC bus; controlling the energy storage power converter to capture excess power from the power source while maintaining the inverter power output near the inverter's maximum power output, wherein said controlling includes: adjusting a charge command of the power converter to store excess power from the power source that cannot be output to the grid in the energy storage unit; adjusting a high e limit on the DC bus according to the change in the output power of the energy storage power converter and the change in the voltage at the DC bus, wherein the high voltage limit is iteratively adjusted by a predetermined e change value.
12. The method of claim 11, wherein ing a charge command of the power converter to store excess power from the power source that cannot be output to the grid in the energy storage unit comprises: determining if a current output power of the power source is less than a previous output power of the power source; and adjusting a high voltage limit on the DC bus according to the determination as to whether the t output power of the power source is less than the previous output power of the power source to track a maximum power point of the power source.
13. The method of 12, n the high voltage limit is adjusted by a voltage change value, and the sign of the voltage change value is reversed when the output power of the power source is less than the previous output power of the power source. -. .x-7
NZ760097A 2018-05-15 Method and system for extracting excess power NZ760097B2 (en)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
US201762506363P 2017-05-15 2017-05-15
PCT/US2018/032711 WO2018213273A1 (en) 2017-05-15 2018-05-15 Method and system for extracting excess power

Publications (2)

Publication Number Publication Date
NZ760097A NZ760097A (en) 2025-07-25
NZ760097B2 true NZ760097B2 (en) 2025-10-29

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