Electric power supply management system

• US 6,151,330 A
• Filed: 12/04/1997
• Issued: 11/21/2000
• Est. Priority Date: 12/04/1996
• Status: Expired due to Term

• Current Assignee: Itron, Inc.
• Original Assignee: Powercom Control Systems Limited
• Inventors: Liberman, Isidor
• Primary Examiner(s): Vu, Huy D.
• Assistant Examiner(s): BOAKYE, ALEXANDER O
• Application Number:
  US08/984,997
• Time in Patent Office: 1,083 Days
• Field of Search: 370/449, 370/451, 370/453, 370/457, 370/254, 713/300
• US Class Current: 370/449
• CPC Class Codes: H02J 13/00007 using the power network as support for the transmission
• CPC Class Codes: H04B 2203/5408 using protocols
• CPC Class Codes: H04B 2203/5466 using three phases conductors
• CPC Class Codes: H04B 3/54 Systems for transmission via power distribution lines
• CPC Class Codes: H04L 45/02 Topology update or discovery
• CPC Class Codes: Y02E 60/00 Enabling technologies; Technologies with a potential or indirect contribution to GHG emissions mitigation
• CPC Class Codes: Y04S 40/121 using the power network as support for the transmission

Abstract

A communication protocol, designed for centralized power line networks, provides a solution for: automatic network mapping and adaptive routing, for automatic log-on of remote nodes and also for optimization of communication routes and control of the traffic volume.

A Central Unit (CU) permanent polls all the known Remote Nodes (RN) and a polled RN replies with a message. A new Remote Node (RN), which hears any polling command from the CU, transmits a Burst Log-On Message direct to the CU. A new RN, which hears a reply of polled RN, but not the polling message itself, transmits a Burst Log-On Message, using the replying RN as a relay. There maybe a route of several relays between the new RN and the CU and all of them are registered in the Log On message itself. When the CU receives the message from the new RN, it performs a log on of the RN, stores its route, and starts to poll it.

This process continues all the time, enabling an addition of new nodes. RN with no communication behaves as a new one and creates a new route, when the previous is no more available.

A permanent improving of the existing routes is achieved by using a special field in a message, that indicates the time the message has already traveled via the network. This field is incremented by each relay on the route, and further used by each RN, which hears the message, to improve its route to the CU. The criteria used by RN is the less the time--the better the route.

For data, such as a power demand, which is a function of time and should cover all the day, the quantity of data depends on the resolution in use. The system always tries to achieve the highest possible resolution, but if the collection cycle is too long, and the transmitted data doesn'"'"'t cover the required period of time, the resolution and the quantity of data are automatically reduced to provide a continuous coverage of time.

Claims

1. A process for communication via electronic power lines comprising:

(a) constantly performing a mapping process by a central unit in both polling and burst modes of operation, wherein a difference is in an expected quantity of new nodes, there being no special mode for mapping;

wherein, in the beginning, all nodes are in a new/lost mode and there are no known nodes in the central unit data base, the central unit starting a polling cycle by sending a polling message to an imaginary node, with a reserved node ID, there being no influence on the process if such an ID really exists;

wherein the polling message contains a time for a start of bursts and a number of available time slots;

wherein each node, which receives the message, stores the central unit as its neighbor, enters a known mode, and waits for a time to transmit a log-on burst message, a time for burst being computed by each new/lost node by way of time for burst start, as received from the message, plus some function of node ID, in a range of the number of slots; and

wherein the central unit enters the burst mode, waits, and, upon receiving a reply message, records the replying node in the data base as one that has a direct connection with the central unit;

(b) computing new parameters and entering the polling mode when the burst mode is finished, the new parameters being, for the burst mode, start time and a number of slots, the control unit performing its first real interrogation cycle when it enters the polling mode and transmitting polling messages to all the nodes in its data base, all the nodes at this stage being in direct connection, without relays in route;

wherein each new/lost node that receives the message stores again the central unit as its neighbor, each new/lost node which did not get this message, but is done receiving the polling node reply, storing the last heard node as its neighbor;

wherein all nodes wait for the time of burst and transmit the log-on burst message to their neighbors;

wherein when a neighbor is the central unit, the procedure is as before;

wherein if the neighbor is another node, it acts as a relay and sends, in turn, the received message to its neighbor; and

wherein the relay may be only a node which already did respond to the central unit polling message and has a direct connection with the central unit;

(c) storing each new node received by the central unit in the data base together with the route;

(d) interrogating, in the polling mode, all nodes by sending to them a polling message via stored routes;

(e) registering each new/lost node, which receives some node reply to the central unit, or its transmission as relay, as its neighbor; and

(f) transmitting a log-on message to its neighbor when the burst time comes;

wherein each node that receives a message transmits it again to its neighbor until the message arrives at the central unit.

2. A process as claimed in claim 1, wherein optimization of routes is achieved by:

(a) sending polling messages from the central unit to all the nodes in its data base, each message containing the number of retries performed for the message;

wherein the central unit initializes the field to 0 and increments it with each new transmission until receiving acknowledgment from the first relay on the route;

wherein each relay on the route also increments this field with each re-transmission as does the target node, when replying to the central unit command;

wherein each message contains a unique ID, built up from two fields, namely, a cycle number and a message sequence number in the cycle; and

wherein each node processes all the messages in the network, even when it itself should not respond to them, as a relay or a target, each node maintaining a list of routes, where each route keeps a message ID from which it has achieved the route and the number of retries specified in the message and the first time received;

(b) sorting the routes by a node according to the number of retries, wherein, from the node point of view, supposing the received message was addressed to it, the number of retries in the message is also the number of retries required for the central unit to connect it, such that the route with the smallest number of retries received is the best one for the node;

wherein the next time the node responds to the central unit command, or connects the central unit by a burst message, it will do so via the new route, the central unit, in turn, saving the last received route for its next polling command; and

(c) preventing a route which accidentally succeeds in some specific point of time from being the best one by having the node and the central unit compute statistics for the known routes which take into account the number of retries from the previous cycles, when their weights are smaller and smaller as time progresses.