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

• US 8,756,449 B2
• Filed: 03/08/2011
• Issued: 06/17/2014
• 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:
  US13/043,213
• Publication Number:
  US 20120233485A1
• Time in Patent Office: 1,197 Days
• Field of Search: None
• US Class Current: 713/340
• 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 frequency-hopping computer network, the power source being part of a polyphase power source system;

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

determining 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.

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

joining, by the device, a directed acyclic graph (DAG) specific to the particular phase.

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

receiving a demand response (DR) message 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.

5. 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 frequency hopping 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;

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

determine a particular phase of the polyphase power source system at the power supply based on the time of the zero crossing relative to a corresponding location within a frequency hopping superframe of the computer network.

6. The apparatus as in claim 5, wherein the process when executed to is further operable to:

join a directed acyclic graph (DAG) specific to the particular phase via the network interface.

7. The apparatus as in claim 5, wherein the process when executed to is further operable to:

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

react to the DR message.

8. The apparatus as in claim 5, 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.

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

monitor 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;

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

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.

10. The computer-readable media as in claim 9, wherein the software when executed is further operable to:

join the device to a directed acyclic graph (DAG) specific to the particular phase.

11. The computer-readable media as in claim 9, wherein the software when executed is further operable to:

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

react to the DR message.

12. The computer-readable media as in claim 9, 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.