# US 2021/0344199 A1 · Load re-balancing on a multi-phase power system

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- Number: US 2021/0344199 A1
- Document ID: US20210344199A1
- Status: Published application
- Kind: A1
- Application number: 16/865,961
- Filed: 2020-05-04
- Published: 2021-11-04
- Earliest claimed: 2020-05-04
- Assignees: American Superconductor Corporation
- Applicants: American Superconductor Corporation
- Inventors: Patrick S. Flannery; Robert McFetridge
- Web page: https://patentgrep.com/patent/US20210344199A1

## CPC

- H02J 3/26: Arrangements for eliminating or reducing asymmetry in polyphase networks
- H01F 38/14: Inductive couplings
- H01F 38/18: Rotary transformers
- H02J 3/14: by switching loads on to, or off from, the networks, e.g. progressively balanced loading
- H02J 3/44: with means for ensuring correct phase sequence
- H02K 11/0094: {Structural association with other electrical or electronic devices}
- H02K 19/26: characterised by the arrangement of exciting windings
- H02K 19/36: Structural association of synchronous generators with auxiliary electric devices influencing the characteristic of the generator or controlling the generator, e.g. with impedances or switches
- H02K 47/20: Motor/generators
- H02M 5/4585: {having a rectifier with controlled elements}
- Y02B 70/3225: Demand response systems, e.g. load shedding, peak shaving
- Y02E 40/50: Arrangements for eliminating or reducing asymmetry in polyphase networks
- Y04S 20/222: Demand response systems, e.g. load shedding, peak shaving
- H02J: ELECTRIC POWER NETWORKS; CIRCUIT ARRANGEMENTS OR SYSTEMS FOR SUPPLYING OR DISTRIBUTING ELECTRIC POWER; SYSTEMS FOR STORING ELECTRIC ENERGY
- H01F: MAGNETS; INDUCTANCES; TRANSFORMERS; SELECTION OF MATERIALS FOR THEIR MAGNETIC PROPERTIES
- H02K: DYNAMO-ELECTRIC MACHINES (dynamo-electric relays H01H53/00; conversion of DC or AC input power into surge output power {H03K3/53})
- 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)
- Y02B: CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO BUILDINGS, e.g. HOUSING, HOUSE APPLIANCES OR RELATED END-USER APPLICATIONS
- Y02E: REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
- Y04S: SYSTEMS INTEGRATING TECHNOLOGIES RELATED TO POWER NETWORK OPERATION, COMMUNICATION OR INFORMATION TECHNOLOGIES FOR IMPROVING THE ELECTRICAL POWER GENERATION, TRANSMISSION, DISTRIBUTION, MANAGEMENT OR USAGE, i.e. SMART GRIDS

## Abstract

A system for load balancing on a multi-phase power line connected to a single phase lateral power line, includes a contactor configured to selectively connect each phase of the multi-phase power line to the single phase lateral power line. There is a phase change device connected in parallel with the contactor and a controller. During the phase change state, the controller connects the input of the phase change device to the multi-phase power line and connects the output of the phase change device the single phase lateral power line. The controller causes the phase change device to output a voltage to the single phase lateral line initially aligned with the first phase and then rotated to align with the second phase and causes the contactor changes connection to the second phase of the multi-phase power line and disconnect the phase change device from the power lines.

## Claims

### Claim 1

A system for load balancing on a multi-phase power line connected to a single phase lateral power line, the system comprising:
a phase rotating transformer having a stator and a rotor; wherein the stator includes a plurality of primary coils, each primary coil configured to be connected to one phase of the multi-phase power line and wherein the rotor includes a secondary coil configured to be connected to the single phase lateral power line;
a rotary actuator operably connected to the rotor; and
a controller configured to cause the rotary actuator to rotate the rotor to selectively electromagnetically couple the secondary coil with each of the plurality of primary coils, so as to enable electrical connection of each phase of the multi-phase power line with the single phase lateral power line.

### Claim 2 (depends on 1)

The system of claim 1 wherein the multi-phase power line comprises three phases.

### Claim 3 (depends on 1)

The system of claim 1 wherein the phase rotating transformer comprises a wound field synchronous generator.

### Claim 4 (depends on 1)

The system of claim 1 wherein when the controller is configured to cause the rotary actuator to rotate the rotor to selectively electromagnetically couple the secondary coil with each of the plurality of primary coils, while the plurality of primary coils of the stator are energized.

### Claim 5 (depends on 1)

The system of claim 1 wherein the controller is configured to rotate the rotary actuator across a range of +/−120 degrees.

### Claim 6 (depends on 1)

The system of claim 1 wherein the rotary actuator comprises a worm gear driven by an electric motor.

### Claim 7 (depends on 4)

The system of claim 4 wherein the controller is configured to rotate the rotary actuator and the secondary coil on the rotor from one of the primary coils to another of the primary coils in approximately 0.2 seconds or less.

### Claim 8 (depends on 1)

The system of claim 1 further including a current in-rush limiting circuit disposed between the multi-phase power line and the primary coils of the stator of the phase rotating transformer.

### Claim 9 (depends on 1)

The system of claim 1 further including a multi-phase by-pass circuit having a multi-phase to single-phase contactor device connected electrically in parallel to the phase rotating transformer.

### Claim 10

A method for load balancing on a multi-phase power line connected to a single phase lateral power line, the method comprising:
providing a phase rotating transformer having a stator and a rotor; wherein the stator includes a plurality of primary coils, each primary coil configured to be connected to one phase of the multi-phase power line and wherein the rotor includes a secondary coil configured to be connected to the single phase lateral power line;
providing a rotary actuator operably connected to the rotor; and
causing the rotary actuator to rotate the rotor to selectively change the electromagnetic coupling of the secondary coil from a first of the plurality of primary coils to a second of the plurality of primary coils, so as to change the electrical connection between the multi-phase power line and the single phase lateral power line from a first phase to a second phase.

### Claim 11 (depends on 10)

The method of claim 10 wherein the multi-phase power line comprises three phases.

### Claim 12 (depends on 10)

The method of claim 10 wherein the phase rotating transformer comprises a wound field synchronous generator.

### Claim 13 (depends on 10)

The method of claim 10 wherein when the rotary actuator is caused to rotate the rotor to selectively change the electromagnet coupling of the secondary coil from a first of the plurality of primary coils to a second of the plurality of primary coils, the plurality of primary coils of the stator are energized.

### Claim 14 (depends on 10)

The method of claim 10 wherein the rotary actuator is capable of causing the rotor to rotate across a range of +/−120 degrees.

### Claim 15 (depends on 10)

The method of claim 10 wherein the rotary actuator comprises a worm gear driven by an electric motor.

### Claim 16 (depends on 13)

The method of claim 13 wherein the rotary actuator causes the rotor and the secondary coil on the rotor to rotate from one of the primary coils to another of the primary coils in approximately 0.2 seconds or less.

### Claim 17 (depends on 10)

The method of claim 10 further including disposing a current in-rush limiting circuit between the multi-phase power line and the primary coils of the stator of the phase rotating transformer.

### Claim 18 (depends on 10)

The method of claim 10 further including disposing a multi-phase by-pass circuit having a multi-phase to single-phase contactor device electrically in parallel to the phase rotating transformer.

### Claim 19

A system for load balancing on a multi-phase power line connected to a single phase lateral power line, the system comprising:
a contactor configured to selectively connect each phase of the multi-phase power line to the single phase lateral power line; wherein in a normal operating state, the contactor is configured to connect a first phase of the multi-phase power line to the single phase lateral power line and during a phase change state, the contactor is configured to change connection from the first phase to a second phase of the multi-phase power line;
a power electronics device, having an input and an output, connected in parallel with the contactor between the multi-phase power line and the single phase lateral power line; wherein, during the phase change state, the input is configured to be connected to the multi-phase power line and the output is configured to be connected to the single phase lateral power line; and wherein in the normal operating state, the input is configured to be disconnected from the multi-phase power line and the output is configured to be disconnected from the single phase lateral power line; and
a controller, during the phase change state, configured to:
connect the input of the power electronics device to the multi-phase power line and connect the output of the power electronics device the single phase lateral power line;
cause the power electronics device to output a voltage to the single phase lateral line aligned with the first phase;
cause the power electronics device to output the voltage to the single phase lateral line aligned with the second phase;
cause the contactor to change connection from the first phase of the multi-phase power line to the second phase of the multi-phase power line; and
disconnect the input of the power electronics device from the multi-phase power line and disconnect the output of the power electronics device from the single phase lateral power line.

### Claim 20

A method for load balancing on a multi-phase power line connected to a single phase lateral power line, the method comprising:
providing a contactor configured to selectively connect each phase of the multi-phase power line to the single phase lateral power line; wherein in a normal operating state, the contactor is configured to connect a first phase of the multi-phase power line to the single phase lateral power line and during a phase change state, the contactor is configured to change connection from the first phase to a second phase of the multi-phase power line;
providing a power electronics device, having an input and an output, connected in parallel with the contactor between the multi-phase power line and the single phase lateral power line; wherein, during the phase change state, the input is configured to be connected to the multi-phase power line and the output is configured to be connected to the single phase lateral power line; and wherein in the normal operating state, the input is configured to be disconnected from the multi-phase power line and the output is configured to be disconnected from the single phase lateral power line; and
during the phase change state:
connecting the input of the power electronics device to the multi-phase power line and connecting the output of the power electronics device the single phase lateral power line;
causing the power electronics device to output a voltage to the single phase lateral line aligned with the first phase;
causing the power electronics device to output the voltage to the single phase lateral line rotated to align with the second phase;
causing the contactor to change connection from the first phase of the multi-phase power line to the second phase of the multi-phase power line; and
disconnecting the input of the power electronics device from the multi-phase power line and disconnecting the output of the power electronics device from the single phase lateral power line.

### Claim 21

A system for load balancing on a multi-phase power line connected to a single phase lateral power line, the system comprising:
a contactor configured to selectively connect each phase of the multi-phase power line to the single phase lateral power line; wherein in a normal operating state, the contactor is configured to connect a first phase of the multi-phase power line to the single phase lateral power line and during a phase change state, the contactor is configured to change connection from the first phase to a second phase of the multi-phase power line;
a phase change device, having an input and an output, connected in parallel with the contactor between the multi-phase power line and the single phase lateral power line; wherein, during the phase change state, the input is configured to be connected to the multi-phase power line and the output is configured to be connected to the single phase lateral power line; and wherein in the normal operating state, the input is configured to be disconnected from the multi-phase power line and the output is configured to be disconnected from the single phase lateral power line; and
a controller, during the phase change state, configured to:
connect the input of the phase change device to the multi-phase power line and connect the output of the phase change device the single phase lateral power line;
cause the phase change device to output a voltage to the single phase lateral line initially aligned with the first phase and then rotated to align with the second phase;
cause the contactor to change connection from the first phase of the multi-phase power line to the second phase of the multi-phase power line; and
disconnect the input of the phase change device from the multi-phase power line and disconnect the output of the phase change device from the single phase lateral power line.

### Claim 22 (depends on 21)

The system of claim 21 wherein the phase change device comprises one of a power electronics device or a phase rotating transformer.

### Claim 23

A method for load balancing on a multi-phase power line connected to a single phase lateral power line, the system comprising:
providing a contactor configured to selectively connect each phase of the multi-phase power line to the single phase lateral power line; wherein in a normal operating state, the contactor is configured to connect a first phase of the multi-phase power line to the single phase lateral power line and during a phase change state, the contactor is configured to change connection from the first phase to a second phase of the multi-phase power line;
providing a phase change device, having an input and an output, connected in parallel with the contactor between the multi-phase power line and the single phase lateral power line; wherein, during the phase change state, the input is configured to be connected to the multi-phase power line and the output is configured to be connected to the single phase lateral power line; and wherein in the normal operating state, the input is configured to be disconnected from the multi-phase power line and the output is configured to be disconnected from the single phase lateral power line; and
during the phase change state:
connecting the input of the phase change device to the multi-phase power line and connecting the output of the phase change device the single phase lateral power line;
causing the phase change device to output a voltage to the single phase lateral line initially aligned with the first phase and then rotated to align with the second phase;
causing the contactor to change connection from the first phase of the multi-phase power line to the second phase of the multi-phase power line; and
disconnecting the input of the phase change device from the multi-phase power line and disconnect the output of the phase change device from the single phase lateral power line.

### Claim 24 (depends on 21)

The method of claim 21 wherein the phase change device comprises one of a power electronics device or a phase rotating transformer.