Phase-based operation of devices on a polyphase electric distribution system

• US 9,128,689 B2
• Filed: 05/01/2014
• Issued: 09/08/2015
• Est. Priority Date: 03/08/2011
• Status: Active Grant

• Current Assignee: Cisco Technology, Inc. (Cisco Systems, Inc.)
• Original Assignee: Cisco Technology, Inc. (Cisco Systems, Inc.)
• Inventors: Shaffer, Shmuel, Vasseur, Jean-Philippe, Shetty, Sandeep Jay
• Primary Examiner(s): YANCHUS III, PAUL B
• Application Number:
  US14/267,205
• Publication Number:
  US 20140245055A1
• Time in Patent Office: 495 Days
• Field of Search: None
• US Class Current: 1/1
• CPC Class Codes: G01R 29/16 Measuring asymmetry of polyphase networks
• CPC Class Codes: G01R 29/18 Indicating phase sequence; Indicating synchronism
• CPC Class Codes: G06F 1/26 Power supply means, e.g. regulation thereof for memories G11C
• CPC Class Codes: H02J 2310/60 Limiting power consumption in the network or in one section of the network, e.g. load shedding or peak shaving
• CPC Class Codes: H02J 3/144 Demand-response operation of the power transmission or distribution network
• CPC Class Codes: H02J 3/26 Arrangements for eliminating or reducing asymmetry in polyphase networks
• CPC Class Codes: Y02B 70/3225 Demand response systems, e.g. load shedding, peak shaving
• CPC Class Codes: Y02E 40/50 Arrangements for eliminating or reducing asymmetry in polyphase networks
• CPC Class Codes: Y04S 20/222 Demand response systems, e.g. load shedding, peak shaving

Abstract

In one embodiment, a device in a computer network monitors an alternating-current (AC) waveform of an electrical power source at the device, where the power source is part of a polyphase power source system. Once the device determines a particular phase of the polyphase power source system at the device, then the device joins a directed acyclic graph (DAG) specific to the particular phase. In another embodiment, a device detects a time of a zero crossing of the AC waveform, and may then determine a particular phase of the polyphase power source system at the device based on the time of the zero crossing relative to a corresponding location within a frequency hopping superframe of the computer network.

Claims

1. A method, comprising:

monitoring an alternating-current (AC) waveform of an electrical power source at a device in a computer network, the power source being part of a polyphase power source system;

determining a particular phase of the polyphase power source system at the device based on the AC waveform; and

in response to determining the particular phase of the device, joining, by the device, a directed acyclic graph (DAG) specific to the particular phase until the device detects that the particular phase of the devices has changed.

2. The method as in claim 1, wherein determining the particular phase comprises:

detecting a time of a zero crossing of the AC waveform; and

determining the particular phase based on the time of the zero crossing relative to a corresponding location within a frequency hopping superframe of the computer network.

3. The method as in claim 1, further comprising:

receiving a demand response (DR) message on the DAG specific to the particular phase; and

reacting to the DR message.

4. The method as in claim 1, further comprising:

detecting a phase change at the device based on the AC waveform to a second phase; and

invoking a DAG migration by the device to a second DAG specific to the second phase.

5. The method as in claim 1, further comprising:

joining a multicast group established on the DAG, the multicast group specific to the particular phase.

6. The method as in claim 1, wherein a virtual local area network (VLAN) is configured on the DAG.

7. The method as in claim 1, further comprising:

notifying an external source of the AC waveform at the device; and

receiving a notification from the external source, wherein determining the particular phase of the polyphase power source system at the device based on the notification from the external source.

8. An apparatus, comprising:

a power supply adapted to receive an alternating-current (AC) waveform of an electrical power source, the power source being part of a polyphase power source system;

a network interface adapted to communicate in a computer network;

a processor coupled to the network interface and adapted to execute one or more processes; and

a memory configured to store a process executable by the processor, the process when executed operable to;

monitor the AC waveform;

determine a particular phase of the polyphase power source system at the power supply based on the AC waveform; and

in response to a determination of the particular phase of the device, join a directed acyclic graph (DAG) specific to the particular phase via the network interface until the device detects that the particular phase of the devices has changed.

9. The apparatus as in claim 8, wherein the process when executed to determine the particular phase is operable to:

detect a time of a zero crossing of the AC waveform; and

determine the particular phase based on the time of the zero crossing relative to a corresponding location within a frequency hopping superframe of the computer network used by the network interface.

10. The apparatus as in claim 8, wherein the process when executed to is further operable to:

receive a demand response (DR) message on the DAG specific to the particular phase; and

react to the DR message.

11. The apparatus as in claim 8, wherein the process when executed to is further operable to:

detect a phase change at the power supply based on the AC waveform to a second phase; and

invoking a DAG migration by the apparatus to a second DAG specific to the second phase.

12. A tangible, non-transitory, computer-readable media having software encoded thereon, the software when executed by a processor on a device in a computer network operable to:

monitor an alternating-current (AC) waveform of an electrical power source at the device, the power source being part of a polyphase power source system;

determine a particular phase of the polyphase power source system at the device based on the AC waveform; and

in response to a determination of the particular phase of the device, join the device to a directed acyclic graph (DAG) specific to the particular phase until the device detects that the particular phase of the devices has changed.

13. The computer-readable media as in claim 12, wherein the software when executed to determine the particular phase is operable to:

detect a time of a zero crossing of the AC waveform; and

determine the particular phase based on the time of the zero crossing relative to a corresponding location within a frequency hopping superframe of the computer network.

14. The computer-readable media as in claim 12, wherein the software when executed is further operable to:

receive a demand response (DR) message on the DAG specific to the particular phase; and

react to the DR message.

15. The computer-readable media as in claim 12, wherein the software when executed is further operable to:

detect a phase change at the device based on the AC waveform to a second phase; and

invoke a DAG migration by the device to a second DAG specific to the second phase.