# US 9,882,424 B2 · Redundant uninterruptible power supply systems > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 9,882,424 B2 - Document ID: US9882424B2 - Status: Granted - Kind: B2 - Application number: 14/186,159 - Filed: 2014-02-21 - Published: 2015-08-27 - Granted: 2018-01-30 - Earliest claimed: 2014-02-21 - Assignees: General Electric Company - Applicants: General Electric Company - Inventors: Yashomani Kolhatkar; Pradeep Vijayan; Silvio Colombi; Rajendra Naik; Viswanathan Kanakasabai - Web page: https://patentgrep.com/patent/US9882424B2 ## CPC - H02J 9/062: {for AC powered loads} - G06F 1/26: Power supply means, e.g. regulation thereof (for memories G11C) - G06F 1/30: Means for acting in the event of power-supply failure or interruption, e.g. power-supply fluctuations (for resetting only G06F1/24) - H02J 3/08: Synchronisation of networks - H02M 5/42: by static converters - H02J 9/068: {Electronic means for switching from one power supply to another power supply, e.g. to avoid parallel connection} - H02J 2105/425: {the loads being an Information and Communication Technology [ICT] facility} - H02J: ELECTRIC POWER NETWORKS; CIRCUIT ARRANGEMENTS OR SYSTEMS FOR SUPPLYING OR DISTRIBUTING ELECTRIC POWER; SYSTEMS FOR STORING ELECTRIC ENERGY - G06F: ELECTRIC DIGITAL DATA PROCESSING (computer systems based on specific computational models G06N) - H02M: APPARATUS FOR CONVERSION BETWEEN AC AND AC, BETWEEN AC AND DC, OR BETWEEN DC AND DC, AND FOR USE WITH MAINS OR SIMILAR POWER SUPPLY SYSTEMS; CONVERSION OF DC OR AC INPUT POWER INTO SURGE OUTPUT POWER; CONTROL OR REGULATION THEREOF (transformers H01F; dynamo-electric converters H02K47/00; controlling transformers, reactors or choke coils, control or regulation of electric motors, generators or dynamo-electric converters H02P) ## Abstract A system is provided. The system includes a plurality of uninterruptible power supplies (UPSs), a ring bus, at least one load electrically coupled to the plurality of UPSs and the ring bus, and a controller communicatively coupled to the plurality of UPSs. The controller is configured to calculate a phase angle for each UPS of the plurality of UPSs, wherein the phase angle is calculated relative to a common reference angle, and control operation of each UPS based on the respective calculated phase angles. ## Claims ### Claim 1 A system comprising: a plurality of uninterruptible power supplies (UPSs) electrically coupleale to at least one load; a ring bus electrically coupleable to the at least one load; and a controller communicatively coupled to said plurality of UPSs, said controller configured to: calculate a phase angle for each UPS of said plurality of UPSs, wherein the phase angle is calculated relative to a common reference angle; and control operation of each UPS based on the respective calculated phase angles by gradually adjusting a phase angle of each UPS using a slow power transfer algorithm to prevent transient oscillations. ### Claim 2 (depends on 1) A system in accordance with claim 1, further comprising a plurality of chokes such that one choke of said plurality of chokes is electrically coupled between each UPS and said ring bus. ### Claim 3 (depends on 1) A system in accordance with claim 1, wherein said controller is further configured to control operation of each UPS in accordance with a swapping-in algorithm that facilitates adding an additional UPS to said system during operation of said system. ### Claim 4 (depends on 1) A system in accordance with claim 1, wherein said controller is further configured to control operation of each UPS in accordance with a swapping-out algorithm that facilitates removing one of said plurality of UPSs from said system during operation of said system. ### Claim 5 (depends on 1) A system in accordance with claim 1, wherein said controller is further configured to control operation of each UPS in accordance with a no load algorithm that facilitates operating said system upon removal of a local load that was previously electrically coupled to one of said plurality of UPSs. ### Claim 6 (depends on 1) A system in accordance with claim 1, where to calculate a phase angle for each UPS, said controller is configured to utilize a look up table that stores values calculated from a two-dimensional relationship between the phase angle and power supplied by a UPS. ### Claim 7 (depends on 1) A system in accordance with claim 1, where to calculate a phase angle for each UPS, said controller is configured to calculate the phase angle using δ = ASIN ⁡ ( ( P_Full ⁢ _Load 2 - P_Local ⁢ _Load ) ⁢ ω * L V 2 ) , where δ is the phase angle, ASIN is the arcsin function, P_Full_Load is a predetermined power that can be supplied by said UPS, P_Local_Load is a power to be delivered to a local load electrically coupled to said UPS, ω is a frequency of power output by said UPS, L is the inductance of a choke electrically coupled between said UPS and said ring bus, and V is the root mean square of a voltage output by said UPS. ### Claim 8 A controller for controlling a power supply system that includes a plurality of uninterruptible power supplies (UPSs), a ring bus, and at least one load electrically coupled to the plurality of UPSs and the ring bus, said controller comprising: a processor; and a memory device communicatively coupled to said processor, said memory device storing executable instructions configured to cause said processor to: calculate a phase angle for each UPS of the plurality of UPSs, wherein the phase angle is calculated relative to a common reference angle; and control operation of each UPS based on the respective calculated phase angles by gradually adjusting a phase angle of each UPS using a slow power transfer algorithm to prevent transient oscillations. ### Claim 9 (depends on 8) A controller in accordance with claim 8, wherein said executable instructions are configured to further cause said processor to control operation of each UPS in accordance with a swapping-in algorithm that facilitates adding an additional UPS to the power supply system during operation of the power supply system. ### Claim 10 (depends on 8) A controller in accordance with claim 8, wherein said executable instructions are configured to further cause said processor to control operation of each UPS in accordance with a swapping-out algorithm that facilitates removing one of the plurality of UPSs from the power supply system during operation of the power supply system. ### Claim 11 (depends on 8) A controller in accordance with claim 8, wherein said executable instructions are configured to further cause said processor to control operation of each UPS in accordance with a no load algorithm that facilitates operating the power supply system upon removal of a local load that was previously electrically coupled to one of the plurality of UPSs. ### Claim 12 (depends on 8) A controller in accordance with claim 8, wherein to calculate a phase angle for each UPS, said executable instructions are configured to cause said processor to calculate the phase angle using a look up table that stores values calculated from a two-dimensional relationship between the phase angle and power supplied by a UPS. ### Claim 13 (depends on 8) A controller in accordance with claim 8, wherein to calculate a phase angle for each UPS, said executable instructions are configured to cause said processor to calculate the phase angle using δ = ASIN ⁡ ( ( P_Full ⁢ _Load 2 - P_Local ⁢ _Load ) ⁢ ω * L V 2 ) , where δ is the phase angle, ASIN is the arcsin function, P_Full_Load is a predetermined power that can be supplied by the UPS, P_Local_Load is a power to be delivered to a local load electrically coupled to the UPS, ω is a frequency of power output by the UPS, L is the inductance of a choke electrically coupled between the UPS and the ring bus, and V is the root mean square of a voltage output by the UPS. ### Claim 14 (depends on 8) A controller in accordance with claim 8, wherein to calculate a phase angle for each UPS, said executable instructions are configured to cause said processor to calculate each phase angle such that each phase angle is no greater than 9° and no less than −9°. ### Claim 15 A method of controlling a power supply system that includes a plurality of uninterruptible power supplies (UPSs), a ring bus, and at least one load electrically coupled to the plurality of UPSs and the ring bus, the method comprising: calculating, using a controller communicatively coupled to the plurality of UPSs, a phase angle for each UPS of the plurality of UPSs, wherein the phase angle is calculated relative to a common reference angle; and controlling operation of each UPS based on the respective calculated phase angles by gradually adjusting a phase angle of each UPS using a slow power transfer algorithm to prevent transient oscillations. ### Claim 16 (depends on 15) A method in accordance with claim 15, further comprising controlling operation of each UPS in accordance with a swapping-in algorithm that facilitates adding an additional UPS to the power supply system during operation of the power supply system. ### Claim 17 (depends on 15) A method in accordance with claim 15, further comprising controlling operation of each UPS in accordance with a swapping-out algorithm that facilitates removing one of the plurality of UPSs from the power supply system during operation of the power supply system.