US20050251296A1 - Method and apparatus for control of an electric power distribution system in response to circuit abnormalities - Google Patents

Method and apparatus for control of an electric power distribution system in response to circuit abnormalities Download PDF

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Publication number
US20050251296A1
US20050251296A1 US11/102,379 US10237905A US2005251296A1 US 20050251296 A1 US20050251296 A1 US 20050251296A1 US 10237905 A US10237905 A US 10237905A US 2005251296 A1 US2005251296 A1 US 2005251296A1
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switch
contract
node
team
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William Tracy Nelson
Kenneth Biallas
Eddie Brasher
Thomas Fix
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Priority to US11/102,379 priority Critical patent/US20050251296A1/en
Publication of US20050251296A1 publication Critical patent/US20050251296A1/en
Priority to US11/516,279 priority patent/US7860615B2/en
Priority to US12/950,595 priority patent/US20110066296A1/en
Abandoned legal-status Critical Current

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    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02H—EMERGENCY PROTECTIVE CIRCUIT ARRANGEMENTS
    • H02H7/00—Emergency protective circuit arrangements specially adapted for specific types of electric machines or apparatus or for sectionalised protection of cable or line systems, and effecting automatic switching in the event of an undesired change from normal working conditions
    • H02H7/26—Sectionalised protection of cable or line systems, e.g. for disconnecting a section on which a short-circuit, earth fault, or arc discharge has occured
    • G—PHYSICS
    • G06—COMPUTING OR CALCULATING; COUNTING
    • G06Q—INFORMATION AND COMMUNICATION TECHNOLOGY [ICT] SPECIALLY ADAPTED FOR ADMINISTRATIVE, COMMERCIAL, FINANCIAL, MANAGERIAL OR SUPERVISORY PURPOSES; SYSTEMS OR METHODS SPECIALLY ADAPTED FOR ADMINISTRATIVE, COMMERCIAL, FINANCIAL, MANAGERIAL OR SUPERVISORY PURPOSES, NOT OTHERWISE PROVIDED FOR
    • G06Q50/00—Information and communication technology [ICT] specially adapted for implementation of business processes of specific business sectors, e.g. utilities or tourism
    • G06Q50/06—Energy or water supply
    • G—PHYSICS
    • G06—COMPUTING OR CALCULATING; COUNTING
    • G06Q—INFORMATION AND COMMUNICATION TECHNOLOGY [ICT] SPECIALLY ADAPTED FOR ADMINISTRATIVE, COMMERCIAL, FINANCIAL, MANAGERIAL OR SUPERVISORY PURPOSES; SYSTEMS OR METHODS SPECIALLY ADAPTED FOR ADMINISTRATIVE, COMMERCIAL, FINANCIAL, MANAGERIAL OR SUPERVISORY PURPOSES, NOT OTHERWISE PROVIDED FOR
    • G06Q10/00—Administration; Management
    • G06Q10/06—Resources, workflows, human or project management; Enterprise or organisation planning; Enterprise or organisation modelling
    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02H—EMERGENCY PROTECTIVE CIRCUIT ARRANGEMENTS
    • H02H1/00—Details of emergency protective circuit arrangements
    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02H—EMERGENCY PROTECTIVE CIRCUIT ARRANGEMENTS
    • H02H1/00—Details of emergency protective circuit arrangements
    • H02H1/0092—Details of emergency protective circuit arrangements concerning the data processing means, e.g. expert systems, neural networks
    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02H—EMERGENCY PROTECTIVE CIRCUIT ARRANGEMENTS
    • H02H3/00—Emergency protective circuit arrangements for automatic disconnection directly responsive to an undesired change from normal electric working condition with or without subsequent reconnection ; integrated protection
    • H02H3/02—Details
    • H02H3/06—Details with automatic reconnection
    • H02H3/063—Details concerning the co-operation of many similar arrangements, e.g. in a network
    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02H—EMERGENCY PROTECTIVE CIRCUIT ARRANGEMENTS
    • H02H7/00—Emergency protective circuit arrangements specially adapted for specific types of electric machines or apparatus or for sectionalised protection of cable or line systems, and effecting automatic switching in the event of an undesired change from normal working conditions
    • H02H7/26—Sectionalised protection of cable or line systems, e.g. for disconnecting a section on which a short-circuit, earth fault, or arc discharge has occured
    • H02H7/261—Sectionalised protection of cable or line systems, e.g. for disconnecting a section on which a short-circuit, earth fault, or arc discharge has occured involving signal transmission between at least two stations
    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02H—EMERGENCY PROTECTIVE CIRCUIT ARRANGEMENTS
    • H02H7/00—Emergency protective circuit arrangements specially adapted for specific types of electric machines or apparatus or for sectionalised protection of cable or line systems, and effecting automatic switching in the event of an undesired change from normal working conditions
    • H02H7/26—Sectionalised protection of cable or line systems, e.g. for disconnecting a section on which a short-circuit, earth fault, or arc discharge has occured
    • H02H7/28—Sectionalised protection of cable or line systems, e.g. for disconnecting a section on which a short-circuit, earth fault, or arc discharge has occured for meshed systems
    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02J—ELECTRIC POWER NETWORKS; CIRCUIT ARRANGEMENTS OR SYSTEMS FOR SUPPLYING OR DISTRIBUTING ELECTRIC POWER; SYSTEMS FOR STORING ELECTRIC ENERGY
    • H02J13/00—Circuit arrangements for providing remote monitoring or remote control of equipment in a power distribution network
    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02J—ELECTRIC POWER NETWORKS; CIRCUIT ARRANGEMENTS OR SYSTEMS FOR SUPPLYING OR DISTRIBUTING ELECTRIC POWER; SYSTEMS FOR STORING ELECTRIC ENERGY
    • H02J13/00—Circuit arrangements for providing remote monitoring or remote control of equipment in a power distribution network
    • H02J13/18—Circuit arrangements for providing remote monitoring or remote control of equipment in a power distribution network characterised by the remotely-controlled equipment, e.g. converters or transformers
    • H02J13/333—Circuit arrangements for providing remote monitoring or remote control of equipment in a power distribution network characterised by the remotely-controlled equipment, e.g. converters or transformers the equipment forming part of substations
    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02J—ELECTRIC POWER NETWORKS; CIRCUIT ARRANGEMENTS OR SYSTEMS FOR SUPPLYING OR DISTRIBUTING ELECTRIC POWER; SYSTEMS FOR STORING ELECTRIC ENERGY
    • H02J13/00—Circuit arrangements for providing remote monitoring or remote control of equipment in a power distribution network
    • H02J13/18—Circuit arrangements for providing remote monitoring or remote control of equipment in a power distribution network characterised by the remotely-controlled equipment, e.g. converters or transformers
    • H02J13/34—Circuit arrangements for providing remote monitoring or remote control of equipment in a power distribution network characterised by the remotely-controlled equipment, e.g. converters or transformers the equipment being switches, relays or circuit breakers
    • H02J13/36—Circuit arrangements for providing remote monitoring or remote control of equipment in a power distribution network characterised by the remotely-controlled equipment, e.g. converters or transformers the equipment being switches, relays or circuit breakers specially adapted for protection systems
    • H—ELECTRICITY
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    • H02J3/00—Circuit arrangements for AC mains or AC distribution networks
    • H02J3/001—Arrangements for handling faults or abnormalities, e.g. emergencies or contingencies
    • H02J3/0012—Arrangements for handling faults or abnormalities, e.g. emergencies or contingencies characterised by the contingency detection means in AC networks, e.g. using phasor measurement units [PMU], synchrophasors or contingency analysis
    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
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    • H02J3/00—Circuit arrangements for AC mains or AC distribution networks
    • H02J3/007—Arrangements for selectively connecting one or more loads to one or more power sources or power lines
    • H02J3/0073—Arrangements for selectively connecting one or more loads to one or more power sources or power lines by providing alternative feeding paths when the main path fails
    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02J—ELECTRIC POWER NETWORKS; CIRCUIT ARRANGEMENTS OR SYSTEMS FOR SUPPLYING OR DISTRIBUTING ELECTRIC POWER; SYSTEMS FOR STORING ELECTRIC ENERGY
    • H02J13/00—Circuit arrangements for providing remote monitoring or remote control of equipment in a power distribution network
    • H02J13/13—Circuit arrangements for providing remote monitoring or remote control of equipment in a power distribution network characterised by the transmission of data to equipment in the power network
    • H02J13/1321—Circuit arrangements for providing remote monitoring or remote control of equipment in a power distribution network characterised by the transmission of data to equipment in the power network using a wired telecommunication network or a data transmission bus
    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02J—ELECTRIC POWER NETWORKS; CIRCUIT ARRANGEMENTS OR SYSTEMS FOR SUPPLYING OR DISTRIBUTING ELECTRIC POWER; SYSTEMS FOR STORING ELECTRIC ENERGY
    • H02J13/00—Circuit arrangements for providing remote monitoring or remote control of equipment in a power distribution network
    • H02J13/13—Circuit arrangements for providing remote monitoring or remote control of equipment in a power distribution network characterised by the transmission of data to equipment in the power network
    • H02J13/1331—Circuit arrangements for providing remote monitoring or remote control of equipment in a power distribution network characterised by the transmission of data to equipment in the power network using wireless data transmission
    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02J—ELECTRIC POWER NETWORKS; CIRCUIT ARRANGEMENTS OR SYSTEMS FOR SUPPLYING OR DISTRIBUTING ELECTRIC POWER; SYSTEMS FOR STORING ELECTRIC ENERGY
    • H02J2103/00—Details of circuit arrangements for mains or AC distribution networks
    • H02J2103/30—Simulating, planning, modelling, reliability check or computer assisted design [CAD] of electric power networks
    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02J—ELECTRIC POWER NETWORKS; CIRCUIT ARRANGEMENTS OR SYSTEMS FOR SUPPLYING OR DISTRIBUTING ELECTRIC POWER; SYSTEMS FOR STORING ELECTRIC ENERGY
    • H02J2103/00—Details of circuit arrangements for mains or AC distribution networks
    • H02J2103/30—Simulating, planning, modelling, reliability check or computer assisted design [CAD] of electric power networks
    • H02J2103/35—Grid-level management of power transmission or distribution systems, e.g. load flow analysis or active network management
    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02J—ELECTRIC POWER NETWORKS; CIRCUIT ARRANGEMENTS OR SYSTEMS FOR SUPPLYING OR DISTRIBUTING ELECTRIC POWER; SYSTEMS FOR STORING ELECTRIC ENERGY
    • H02J2105/00—Networks for supplying or distributing electric power characterised by their spatial reach or by the load
    • H02J2105/10—Local stationary networks having a local or delimited stationary reach
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02B—CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO BUILDINGS, e.g. HOUSING, HOUSE APPLIANCES OR RELATED END-USER APPLICATIONS
    • Y02B70/00—Technologies for an efficient end-user side electric power management and consumption
    • Y02B70/30—Systems integrating technologies related to power network operation and communication or information technologies for improving the carbon footprint of the management of residential or tertiary loads, i.e. smart grids as climate change mitigation technology in the buildings sector, including also the last stages of power distribution and the control, monitoring or operating management systems at local level
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
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    • Y02B70/3225—Demand response systems, e.g. load shedding, peak shaving
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    • Y04—INFORMATION OR COMMUNICATION TECHNOLOGIES HAVING AN IMPACT ON OTHER TECHNOLOGY AREAS
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    • Y04S20/14—Protecting elements, switches, relays or circuit breakers
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
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Definitions

  • the present invention generally relates to improvements in control of commodity distribution systems, e.g. an electric power distribution system, and more specifically to the use of intelligent autonomous nodes for isolating faulted sections of distribution lines, restoring service to end customers, improving circuit protection and allocation of system resources.
  • commodity distribution systems e.g. an electric power distribution system
  • a distribution system comprises one or more sources connected through a distribution network to one or more delivery points.
  • abnormalities e.g., faults
  • a distribution system will typically have nodes at various locations throughout the network which operate to monitor or control the flow of the commodity through the system. It is desirable to not only minimize the loss of the commodity when an abnormality occurs, but also to minimize the number of users who experience an interruption of the delivery of the commodity due to any abnormality.
  • the nodes in a system may have the capability to respond individually to system abnormalities without coordinating with other nodes.
  • nodes can prevent the commodity from flowing through the part of the distribution system where the abnormality exists.
  • this system may interrupt service to more users than is absolutely necessary.
  • the power distribution systems for which this invention is most useful are generally of low to medium-voltage distribution feeders (ranging from approximately 4 KV to 69 KV) originating in power distribution substations and leading to the source of supply for end customers of an electrical supply utility or agency.
  • low to medium-voltage distribution feeders ranging from approximately 4 KV to 69 KV
  • the methodologies for building, operating and maintaining the lower voltage systems are different. These methodologies are dictated by much larger quantities and geographical dispersion of distribution equipment, and by much lower quantities of electrical power supplied per mile of circuit. This creates requirements for lower cost, modular, standardized equipment, which can be installed, operated and maintained with minimal labor and human supervision.
  • failures of the distribution feeder occur due to downed power lines, excavation of underground cable or other causes and are typically detectable by sensing excess (short circuit/overcurrent) current, and occasionally by detecting loss of voltage.
  • a loss of voltage complaint by the customer is the means by which the utility senses the outage, responding by dispatching a crew to isolate the fault and reconfigure the distribution system.
  • the typical devices for isolating these faults are circuit breakers located primarily in distribution substations and fuses located on tap lines or at customer transformers.
  • the substation breakers are generally provided with reclosing relays that cause the breaker to close several times after the breaker has detected an overcurrent condition and tripped open.
  • sectionalizer refers to a specific family of automatic, fault isolating devices described below, while the terms “sectionalizing” and sectionalize” are used to describe the process of isolating a faulted section of line, which can be performed by all of the classes of switches described above.
  • the “line recloser” is typically a pre-packaged, version of the substation breaker with reclosing relay.
  • Line reclosers typically consist of a fault-break switching device with integrated current sensing, plus a control enclosure containing fault detection hardware, control logic, user interface module, and battery-backed power supply.
  • a line recloser When placed on the distribution line between the substation and customer loads, a line recloser is typically set up with fault detection settings coordinated to operate before the substation breaker trips and to correspondingly prevent the substation breaker from tripping. This has the effect of reducing the number of customers affected by an end of line fault. On very long feeders, the more sensitive settings can be used to protect the feeder from faults of a magnitude too low to be detected reliably by the substation circuit breaker.
  • Multiple line reclosers can be placed on a distribution line in series, although it becomes increasingly difficult or impossible to coordinate their settings such that only the nearest recloser on the source side of the fault operates.
  • the “interrupter” is typically a pre-packaged breaker and fault relay without automatic reclosing capability. Interrupters are used primarily in underground power distribution systems.
  • the “automatic line sectionalizer” or “sectionalizer” is typically a prepackaged combination of a load-break switch used in conjunction with a device known as a “line sectionalizer control”.
  • the sectionalizer senses current (and optionally voltage) such that the operation of the circuit and the source-side protective device can be monitored.
  • the sectionalizer is configured to open its switch under certain circumstances when the circuit is de-energized after some number of pre-configured voltage losses have occurred within a brief time interval. The circumstances vary from product to product, but are always based upon sensing of conditions caused by faults followed shortly by voltage losses.
  • Sectionalizers are designed to coordinate with the operation of the circuit's protective devices. Typical sectionalizers are devices such as the Cooper Power Systems Sectionalizer type GV or GW manufactured by Cooper Industries, Inc, or the EnergyLine Systems Model 2801-SC Switch Control manufactured by S&C Electric Company.
  • each node may communicate with a central control location which gathers information from each node and coordinates a system-wide response.
  • the central controller typically maintains a detailed map of the system topology, and this map must be updated whenever the system is reconfigured or new nodes are added. This can make such centrally controlled systems less reliable and more difficult and costly to implement and maintain. Additionally, for small systems with few nodes, the need to include a central controller can significantly add to the cost of the system.
  • the nodes typically must be transitioned to a normal state or to a specified state. Once the abnormality is corrected, it is generally desired to place the nodes in the original configuration or a specified configuration, at present this is typically done manually.
  • a primary aspect of the present invention is to provide methodology and related system apparatus for using and coordinating the use of information conveyed over communications to most efficiently and flexibly respond to abnormalities to isolate faults and restore service to end customers (circuit reconfiguration); i.e. to enhance the reconfigurability of the distribution system.
  • methodology is provided in a system that responds to faults in a distribution system having a plurality of nodes to optimally reconfigure the distribution system and appropriately allocate system resources of the distribution system via resources at each node and communications of source allocation data or messages to other nodes to request and establish an appropriate allocation of system resources.
  • “teams” of nodes are defined in the distribution system having associated switching controls with the various teams communicating amongst each other to “negotiate” or work out the most efficient and expeditious reconfiguration of the system in response to a fault conditions and other circuit abnormalities.
  • FIG. 1 shows a conventional distribution system in which nodes of an illustrative distribution system have been identified
  • FIG. 2 is a block diagram of a node of an illustrative embodiment of the present invention.
  • FIGS. 3-8 are flow charts showing various routines employed by the embodiment of FIG. 2 ;
  • FIGS. 9 and 10 show alternate configurations of a distribution system illustrating enhanced control features and improved fault isolation capabilities, along with flow charts for supporting the configurations;
  • FIG. 11 shows a logical block diagram of an alternative embodiment of node controller 200 , in which the circuit reconfiguration intelligence is contained in an add-on microprocessor board;
  • FIGS. 12-14 show overall logical organization and the data structure of another alternate embodiment of the present invention.
  • FIGS. 15-21 are representations of system operation and response of the embodiment of the present invention of FIGS. 12-14 to an Overcurrent Fault Event in an illustrative distribution system describing the response of the present invention to reconfigure and restore service;
  • FIG. 22 is an illustrative flow diagram that may be employed and representative of typical operations performed by the present invention of FIGS. 12-15 at a single team member;
  • FIGS. 23-55 are representations of system operation and response of the present invention of FIGS. 12-15 and 22 occasioned by the loss of a substation identified as S 1 ;
  • FIGS. 56-59 are illustrative logical flow diagrams that may be employed and representative of typical operations performed at a single team member in accordance with source allocation methodology.
  • the present invention comprises novel improvements to a method and system for controlling a distribution system, e.g. an electric power distribution system.
  • a distribution system e.g. an electric power distribution system.
  • the following description is presented to enable any person skilled in the art to make and use the invention, and is provided in the context of particular applications and their requirements.
  • Various modifications to the preferred embodiment will be readily apparent to those skilled in the art, and the generic principles defined herein may be applied to other embodiments and applications without departing from the spirit and scope of the invention.
  • the present invention is not intended to be limited to the embodiment shown, but is to be accorded the widest possible scope consistent with the principles and features disclosed herein.
  • the present invention is applicable to various distributed commodities in addition to electricity such as fluid flow etc.
  • switch locations are any one of a variety of devices including reclosers, breakers, sectionalizers or other protective devices.
  • FIG. 1 shows a simplified view of a portion of an exemplary electrical power distribution system that can be controlled by the present invention.
  • the distribution system comprises a plurality of sources of electrical power 102 connected to a plurality of users 104 (e.g., factories, homes, etc.) through an electrical distribution line 106 such as conventional electrical power lines.
  • Distribution line 106 has a plurality of nodes 108 placed at predetermined points along the line 106 .
  • the depiction of the number of sources, users, lines and nodes in FIG. 1 is arbitrary and there may be a different configuration or number of each of these components in any given distribution system.
  • the present invention enables more efficient and flexible response to abnormalities especially in larger distribution systems to reconfigure and restore service to end customers (circuit reconfiguration) and to allocate system resources such as to prevent the overloading of electrical sources; i.e. to enhance the appropriate reconfigurability of the distribution system.
  • methodology is provided via resources at each node and communications of source allocation data or messages to other nodes to request and establish an appropriate allocation of system resources.
  • “teams” of nodes are defined in the distribution system having associated switching controls with the various teams communicating amongst each other to “negotiate” or work out the most efficient and expeditious reconfiguration of the system in response to a fault conditions and other circuit abnormalities. In this manner, more intelligent local decision making and inter-team coordination can be performed.
  • FIG. 2 depicts an illustrative embodiment of a node 200 .
  • Distribution line 202 passes through switch 204 which can open and close the distribution line at this point.
  • the switch 204 can be replaced by other devices capable of performing power sensing, control or conditioning functions such as voltage regulation (voltage regulators) reactive power control, (switched capacitor banks), fault sensing, etc.
  • the node 200 may also be of a type for controlling two (dual), three, or more switches, with customer loads or alternate sources between the switches.
  • the distribution line 202 would pass through two or more switches 204 which can open and close independently under the control of the single node 200 .
  • node 200 is a single node from the standpoint of communications, but is multiple nodes from the standpoint of the power system and the control algorithms of the present invention. In this circumstance, the information flow is unchanged, but the communication step is simply bypassed.
  • Node controller 206 controls distribution switch 204 .
  • Node controller 206 includes a control computer 208 , a display 209 , and an associated memory 210 .
  • Memory 210 stores the programming to control the node in response to sensed conditions and communicated information from other nodes and stores information about the system.
  • the present invention also includes features for team operation when node 200 has protective (overcurrent protection/fault break) capabilities.
  • distribution switch 204 can have different operating capabilities which may enhance or detract from its ability to participate in circuit reconfiguration.
  • the lowest-cost switches may not be capable of interrupting high currents, or may not be outfitted with both voltage and current sensors.
  • node 200 may be programmed not to open the switch under high interrupting currents (sectionalizing switch control), or alternatively may be programmed as a “circuit protective device” (recloser or breaker). When programmed as a protective device, the switch is opened under overcurrent conditions (fault current) to prevent fire or damage to the circuit or to customer equipment, and also for safety concerns.
  • Control computer 208 is connected to AC waveform processor 212 .
  • AC waveform processor 212 is connected through field interface connector 214 to distribution line 202 . This allows the processor to measure various critical parameters of the electricity on the distribution line such as, voltage and current, digitally convert them, and send them to the control computer for processing, communications, or storage in memory.
  • Digital I/O interface 216 is connected to control computer 208 , switch 204 and distribution line 202 .
  • Digital I/O interface 216 allows computer controller 206 to receive switch position sensing information and other inputs, and to output control outputs to the switch.
  • Communications device 218 is connected to control computer 208 and allows it to communicate with other nodes on the system through communications channel 110 of FIG. 1 .
  • the communications devices can be connected to any communications network that is conveniently available and has the desired characteristics; e.g. a Metricom Radio Radio (now manufactured by Schlumberger Industries and marketed under the UtilinetTM product line) has been found suitable in one implementation.
  • a second, optional, communications device 220 can be included in the node 200 , if desired, for use by systems other than the present invention. An example of this would be a SCADA gateway.
  • Power is supplied to the node through power supply/battery backup 222 .
  • the battery can be charged from solar power, an AC potential transformer, or from power supplied through the voltage sensors.
  • Each of the nodes is connected to a communications channel 110 .
  • Any type of communications channel can be used.
  • the communications channel could be telephone, radio, the Internet, or fiber optic cable.
  • FIG. 3 is a flow diagram which illustrates the operation of a synchronization counter and state selection process run by each node.
  • the nodes update their timer and database sequence counter which are used to synchronize the nodes with each other.
  • the nodes then check for error conditions and set error flags if errors are found and determine from their database which state they are in: synchronization, integrity check, or reconfiguration event.
  • An enhancement to the synchronization process is the addition of step 315 to provide protective devices with “advance notice” of their protective characteristics prior to a reconfiguration even such that initial restoration of the circuit may begin prior to adjustment of protective device profiles if the prior settings are adequate.
  • FIG. 4 is a flow diagram which illustrates the operation of the synchronization process state run by each node in accordance with the presently preferred embodiment.
  • the nodes construct a database of critical control information about the distribution system. All nodes contribute to the construction of a database. Each node stores in its memory a copy of the database.
  • the steps in constructing the database in accordance with the presently preferred embodiment are as follows: each node receives the database from the previous node, adds its own record of information and passes the database on to the next node. This process continues until all nodes have received a record from every other node. Once this process is compete, each node then proceeds to the integrity check state shown in FIG. 5
  • FIG. 5 is a flow diagram which illustrates the operation of the integrity check state process run by each node. When a node runs this process, it checks the records it has received from all the other nodes to ensure that the records reflect a timely version of the state of the system.
  • FIG. 6 is a flow diagram which illustrates the operation of the transfer process state. This flow diagram describes the process used by each node upon the occurrence of a fault in the system followed by standalone sectionalization. This process is also started in a node when the node receives a message that another node has entered this process. In order to restore electric power service to as many users as possible after a fault has occurred, each node will use this process to determine if it can close its associated switch(es). These features extend the functionality of the transfer logic to insure that the protection settings match the requirements of the transfer (steps 645 - 654 ).
  • FIG. 7 describes the logic used by each node to return the distribution system to its normal state once the fault has been cleared. This extends the functionality of the return-to-normal logic to insure that the protection settings match the requirements of the return-to-normal transition, particularly when the “closed” transition is used (steps 722 and 750 - 752 ).
  • FIG. 8 is a flow diagram which illustrates the operation of a task timer that is used during the transfer process state of FIG. 6 and the return to normal process state of FIG. 7 in order ensure that the system does not take too much time to complete the steps required in either of these processes. This extends the functionality of the return-to-normal logic to reset the protection settings when the return-to-normal transition, and in particular when the “closed” transition return-to-normal is used (steps 830 - 831 ).
  • memory 210 stores the programming to control the node and stores a database of node records about each node in the system (team database).
  • Each record includes a number of fields which include information that allows the node controller to control the node's switch(es) to alter the distribution line characteristics in response to distribution system demands.
  • the record includes protective characteristics, facilitating coordination of protection settings during load transfer/restoration.
  • the ordering of the node records in the database corresponds to the physical ordering of the nodes in the distribution system. It would not deviate from the present invention to have the node records in the database ordered in some other fashion and to include information in each node record of the node's actual or relative physical position in the distribution system. If the node controller is of a dual or multiple switch type, the position of each switch is represented in the database and may be ordered independently.
  • a single, dual or multiple switch node from the standpoint of communications can be used as the only member of the team.
  • a dual switch node may act as the only member of the team when it is the only member physically installed (other members may be installed later), when other members of the team have been temporarily removed from the team, or when errors at other nodes in the team prevent the entire team from acting upon an outage condition.
  • the present invention is suitable for controlling a loop distribution system as in FIG. 1 in which there are two sources and a normally open switch (a “tie” switch) in the distribution line between the two sources, or a radial distribution system in which there is one source and no tie switch. It would not deviate from the present invention for the database to represent simpler or more complex distribution system topologies and for the invention to be able to work on such topologies.
  • the tie switch can close to restore load (backfeed) from either side, depending on which side of the switch is energized and which side is deenergized.
  • the circuit is described as having a “right” side and a “left” side, with the tie switch between the right and left sides.
  • the lowest numbered node is designated as being closest to the source on the left side of the circuit, and the highest numbered node as being closest to the source on the right side.
  • the circuit traversed between each of two adjacent nodes is referred to as a “transfer segment” or “segment”.
  • each node's database record includes: (1) record currently in use flag, (2) indication of the type of device represented by each individual record, (3) the node's communication address, (4) its normal switch(es) state(s) (open or closed), (5 present switch(es) state(s), (6) the voltage state (is voltage present on the line or not)(by position if applicable), (7) the fault state (has a fault been detected)(by position if applicable), (8) the present time stamp (9) the database sequence number, (10) the logic process state (what state and step is the switch in), (11) error condition status flags, (12) automatic/manual operation mode status (by position if applicable), (13) average of the sensed loads on each phase (by position if applicable), (14) time stamp at start of event process, (15) indication of method of return to normal (open or closed transition), (16) indication of whether the node was within the affected portion of the circuit, (17) maximum number of segments that can be adequately protected with the current protective settings when feeding the circuit from
  • a segment represents the distribution line between two adjacent team nodes of FIG. 1 .
  • the number of segments counts the load between any two switch positions along the main distribution line as an additional segment.
  • the “maximum number of segments” is obtained using a methodology outlined below. It will be appreciated that in other implementations of the invention different node data may be stored in the database record for each node without departing from the scope of the invention.
  • the team local record database (above) allows each node to have enough information about the state of the distribution system to intelligently control its local switch. Additionally, since the database is locally stored in the node, the node need not ask other nodes for information or wait to receive operating instructions from other nodes.
  • the record currently in use flag can be used to remove a node from coordinated system activities or allow a node to resume coordinated system activities.
  • the decision to remove or resume activity of a node may be made by, but is not limited to an external decision making entity, or by the node itself.
  • the present invention includes the representation of additional attributes in the protective device profiles. These attributes enhance the ability of the protection engineer to convey the intended operating range or purpose of the settings to the team nodes. In addition, these attributes support additional, team-related functionality not otherwise represented in the protection settings of the individual device as will become clear below.
  • the attributes are: (1) “Profile Type” Indicates the intended use of this profile. For the preferred implementation, the possible values are: (a) “Team Mode/Normal” for use when the nodes are in their normal operating state, with the normally open switch open, and all others closed. In the preferred embodiment, there is only one Team Mode/Normal profile, although it would not deviate from the scope of this invention to have multiple profiles, selected dynamically based upon operating parameters such as the season of the year or load-based criteria.
  • This number may assume a value greater than the direct reach of the device if the system includes other protective devices with profiles that protect the end of line. In this case, if the other devices are team members, one of the features of the present invention is to maintain consistency among the profiles.
  • (4) “Maximum Load” Indicates the maximum amount of customer load that the profile is intended to protect. This value is typically predefined by the user and compared against real time load data to insure that the profile is not used in circumstances where false tripping of the protective device could occur.
  • “Protection Selection Key” This is an index or internal pointer to the actual configuration settings associated with the profile.
  • This index allows the user-specified entries to be linked to a collection of device settings either preloaded in the device or maintained as a separate database.
  • Those skilled in the art will be able to appreciate other attributes and attribute values that could be used to characterize the configuration of protective device settings.
  • Sectionalizing Switch On initialization, the number of segments that can be protected is set to an indefinitely large number. When the team database or local record is transferred (during synchronization or during a transfer event), the count is reduced to the number of segments protected by the sectionalizer's source-side nearest adjacent node, decremented by one. For example, for the local record corresponding to the second node, if the first node can protect three segments on its load side when power is distributed from the left (left-side segment count), and the second node is a sectionalizing switch, it sets its left-side distribution segment count to two.
  • the sectionalizing switch at node two sets its right-side segment count to one. Special provisions must be made for the first node (left-hand distribution) and last node (right hand distribution), since they have no source side nodes.
  • the count can be predetermined (configured) based upon worst-case loading protection studies for the circuit as seen by the source side protective device, (b) it can be predetermined to an arbitrarily high value (to defeat the prevention of additional circuit loading based upon inadequate segment count), or (c) it may be acquired over communications from the source side protective device (see sideline team member functionality below).
  • the terminal nodes are protective devices rather than sectionalizers (see below).
  • the number of segments may be configured or dynamically calculated based in part on the capabilities of the node as described below.
  • the breaker or recloser's active profile attributes are used in the derivation of the “number of segments” fields in the node's local record.
  • the number of segments is calculated as the lesser of the number of segments protected by the source-side adjacent node (minus one), or the number of segments that can be protected based on the local device's active profile (the profile currently in use).
  • the most-recent load data stored in the team's local copy of the team's database is used to determine whether or not the potential, calculated load (based on real-time load data) corresponding to the number of segments handled by the profile exceeds the maximum load configured for the profile. If it does, the “number of segments” for the profile is reduced until the load can be handled.
  • the logic for making this calculation must be sensitive to the load measured locally, as well as to the direction of present current flow (left or right), and the present measured load of each individual segment on the opposite side of the normally open switch. For example, for calculation of the number of segments for left hand distribution, if the count extends the protection one segment beyond the position of the normally-open switch, the measured circuit load at the switch to the right of the normally open switch would be added to the locally measured load for comparison with the profile. It will be appreciated by those skilled in the art, that the reduction of segments based upon load can be defeated if the end user configures an arbitrarily high value of the load current that can be carried through the node with the specified profile.
  • This process is invoked whenever the number of segments handled by the presently active profile is recalculated during a load transfer, return-to-normal, or error processing or recovery event. Updates to the team database during these events trigger a profile search/selection process.
  • the process identified below is a simplified approach for selecting the appropriate profile, although it would not deviate from the scope of this invention to use a more elaborate process based on calculations of line impedance, line loading or other factors, or to trigger the selection process based on different events.
  • the events that trigger the selection process are: (1) Completion of a synchronization interval (see below) with no errors and a transition of the circuit configuration into its “normal” state, with all switches in their correct normally closed or open positions. This event causes the “Team Mode/Normal” profile to be selected. (2) Transition to a team “stop transfer” condition which causes selection of the “Standalone” profile, assuming the last known configuration of the circuit was such that all switches were in their specified “normal” positions. (Note: Other errors do not alter the selection of the presently active profile.) (3) Transition to the “return to normal” state (see below) causes selection of the “Team Mode/Return to Normal” profile. (4) During a transfer event (see below), detection that a transfer is in progress, and the maximum number of segments that the local switch will have to handle is greater than the number handled by the presently active profile.
  • the node scans through the list of “Team Operation/Transfer” profiles searching for the first entry that can carry the maximum number of segments and pre-fault operating load. This allows the profile reselection process to occur at most, only once during typical transfers. It would not deviate from the scope of this invention to provide the nodes with additional information during the notification process regarding the location of the fault such that the profile selection could be more closely matched to the requirements. In addition, it would not deviate from the scope of this invention for the selection process (and associated communications) to be carried out each time a segment was picked up.
  • the change is initiated and verified. Only after positive verification is the local record in the team database updated. If the verification fails, an error condition is generated, and the logic reattempts the selection. If a transfer is in progress, this is repeated indefinitely until the transfer process times out.
  • Steps 310 to 318 of FIG. 3 comprise a synchronization routine that is often called by steps in other processes run by a node, especially when a node is waiting for a specified event to occur.
  • the node's free running tenth counter is incremented.
  • a free running counter is used to establish a reference for time stamped logic. As will be seen shortly, these counters are used to ensure synchronization among the nodes.
  • the node checks the free running counter to determine if it has reached its maximum. When the maximum count is reached, the synchronization interval expires.
  • step 314 is executed and the sequence number for the database recorded by the node is incremented and a time stamp is recorded in the node's database to help ensure synchronization.
  • the illustrative embodiment also calculates/recalculates the “number of segments” fields for both right hand and left hand distribution using the methodology shown above. The database sequence number is increased by one count on each synchronization interval and each node includes the database sequence number in its local record.
  • each node should be the same if all of the nodes are properly functioning and synchronized. Therefore, the inclusion of each node's database sequencing number in its record allows nodes in the present invention to be certain that the data being received from other nodes is timely and reliable. In this way each node can ascertain for itself whether the system as a whole is functioning properly.
  • the node After step 314 , or if the synchronization interval has not expired then the node checks to determine if communications are allowed. Communications will be prevented in certain situations. An example of when communications are not allowed in a illustrative embodiment is when a team of nodes is initially being configured, all other nodes must be silent except for the node distributing the configuration information. If communication is not allowed for the node, then the node returns to step 310 and is in effect on its own for the moment.
  • step 320 is executed.
  • the node will check for errors and events and set a flag if an error or event is detected. Then each node determines which of three states it is in: synchronizing, integrity check, or reconfiguration event.
  • Each node determines on its own, independently of the other nodes, which of the three states it should be in based on its own internal sensors and the database records that it has received from the other nodes. Typically, all nodes will be in the same state unless the system is transitioning from one state to another. However, any particular node can only be in one state at a time.
  • the node must determine if it is the first active node.
  • the node just after either source can be configured to be the first active node in the database and the other node would be the last active node in the database.
  • the nodes in between would be ordered in the database to reflect their physical ordering in the distribution system. It would not deviate from the present invention to have the nodes ordered in the database in an order other than their physical order and to include data in each node's record that allows the node's absolute or relative physical ordering to be determined.
  • the first node will proceed to step 414 and will start the process of constructing the database of records for the nodes.
  • the first node will put its local record in the database and then send the database to the next node listed in the database.
  • This database is called the “ball” as it is sent around the system from node to node.
  • the record added to the database by each node contains the 18 items of information listed above for the currently passing node.
  • this database could be constructed and communicated
  • the present incarnation of the invention constructs the database by sending it to each successive node to have that node's record added onto the database.
  • the database could be constructed in other ways without deviating from the present invention. For example, each node could simply broadcast its record on the communications channel for reception by all other nodes.
  • step 420 the node determines if it is time to exercise its link.
  • a node exercises its link by signaling another node to signal it back. This allows a node to determine if its communications system is working.
  • a node checks the synchronization interval timer to determine if the synchronization process has taken more than a predetermined used defined period of time. This prevents the node from getting stuck in this state if there is a communications failure.
  • step 422 the node executes steps 310 to 318 of FIG. 3 and checks for errors and events. If an error or event is detected, a flag is set and, if necessary, the process that is active is ended. This is called a “synchronization and error checking loop.” Once this is completed, the node returns to the synchronization process and proceeds to step 424 and checks to determine if it has received the ball. When the synchronization process is run by nodes other than the first node, they go from step 412 directly to step 424 .
  • step 424 if the node has not received the ball, it will return to step 420 and continue this cycle until it is either time to exercise the link or the ball has been received. If the ball is received then the node goes from step 424 to step 426 . At step 426 the node includes its local record with the ball and sends the ball on to the next device. (The last listed node will send the ball to the first listed node.) The node proceeds to step 418 and checks whether it has received the ball twice. If not, then the node proceeds to step 420 again and continues in that loop.
  • the node When the ball is received the second time, the node goes from step 424 to 426 to 418 and then to step 428 and schedules a link exercise message to another node in order to test the communications link to ensure that it is working. This is the same step the node jumps to if the time to exercise the link counter in step 420 expires.
  • step 430 the node goes to step 430 and checks the integrity check counter to determine if it is time to enter the integrity check state as illustrated by the flow chart in FIG. 5 . If it is not yet time for the node to enter the integrity check state, then the node will proceed to step 432 where it performs a synchronization and error checking loop. The node then cycles back to step 430 and will continue this loop until it is time for an integrity check.
  • the synchronization process occurs once per predetermined interval.
  • the length of the predetermined interval is based on the number of nodes in the system. This interval could be larger or smaller, or based on something other than the number of nodes in the system, without deviating from the present invention.
  • the synchronization process illustrated by the flow diagram in FIG. 4 periodically updates the information in each node's database. This process allows each node to contain up to date information on the status of all the other nodes.
  • FIG. 5 shows the flow chart which illustrates a process employed for the integrity check state.
  • each node checks to ensure that the database records contained in its memory appear to be synchronized, that there are no error conditions, and that the nodes are in the correct states.
  • the node checks the database sequence numbers to ensure that they all match. In this way, the node can ensure that the records in the database from each node are all from the same synchronization process.
  • step 514 a flag is set for the sequence numbers to be reset to re-synchronize them. This error flag will prevent any coordinated team activities from taking place until another synchronizing interval has taken place and the database sequence numbers match.
  • step 516 the node checks each of the database records to ensure that they were all time stamped within one second of each other. This requirement ensures that the records in the database accurately reflect a picture of the system at roughly one point in time. If the records are not time stamped within one second of each other, then the node goes to step 518 and sets a flag for a new time stamp. This flag will not allow synchronized team activities if the time stamps are out of synchronization with each other by more than a predetermined amount set by the user. In one embodiment, if the time stamps are 5 seconds out of synchronization then an error flag is set. It will be appreciated that the allowable discrepancy of the time stamps is an implementation dependent parameter.
  • this strict implementation of the integrity check could be considered a “safe mode.” It will be appreciated that consistent with the present invention other modes may exist that would allow the continued operation of team activities even with various levels of integrity check failures.
  • the node checks for stop transfer errors, and if any exist, it tries to determine if the error can be cleared. Examples of errors are: (1) an out of synchronization error in which the database sequence numbers for the nodes do not match, and (2) a reconfiguration process occurred and was unable to be fully completed due to external conditions such as a malfunctioning switch.
  • step 522 a flag is set in step 522 for the error to be cleared.
  • the node then continues on to step 524 .
  • the node determines if it is all ready for transfers. After a reconfiguration event, the node must make sure that all of the nodes are synchronized and that other necessary conditions are met. For example, in one embodiment, the node checks its database to determine if all of the nodes have an average 3 phase load that is within a predetermined user defined limit. If the node determines that it is all ready for transfer, then it will go to step 526 and set a flag indicating that it is all ready for transfer.
  • the node goes to step 528 to determine if it is in the correct ready state.
  • Each node can be either ready for a transfer process or ready for a return to normal process, and all nodes should be in the same ready state.
  • the node will compare which ready state it thinks it should be in based on its local information and the state that other nodes are in based upon information in the database. If the node is not in the correct ready state then it goes to step 530 and determines the correct ready state and changes to it.
  • step 532 it checks to determine if there is a return to normal mode mismatch.
  • the node checks to make sure that all of the nodes are set to the same return to normal mode: open transition, closed transition, or function disabled. If all the nodes are not set to the same return to normal mode, then, there is a mismatch and at step 534 an error flag is set.
  • the node returns to step 310 in FIG. 3 .
  • FIG. 6 The transfer process state flow diagram of FIG. 6 will be described with the aid of a simple example.
  • a fault develops in distribution line 106 between nodes 108 A and 108 B.
  • typical electrical distribution systems will have either a breaker or a recloser (reclosing breaker) at the source of supply for safety and for protection of the circuit.
  • sectionalizers may be placed at switch locations 108 A-F as shown in the FIG. 1 .
  • the “sectionalizer” described here is based on the EnergyLine Model 2801, with additional features added to support operation under a illustrative embodiment of the invention.
  • the standard sectionalizer logic will open (trip) the switch if: 1) its sectionalizing logic is enabled and the device is operational, 2) a pre-configured number of voltage losses (typically 1-3) on all sensed phases have been counted within a brief time period (typically 45 seconds), 3) an overcurrent condition was sensed just prior to the first voltage loss, and 4) the switch is presently closed.
  • An additional option in the conventional software allows the switch to trip if voltage, sensed on all three phases, becomes grossly unbalanced, and remains unbalanced continuously for a configured time period (typically 30 seconds).
  • sectionalizer may be one of many types, including but not limited to multi-switch operators, fault interrupting switches, and air-break switches, without deviating from the intent of the present invention.
  • the single switch sectionalizer described here will be used.
  • An optional feature that can be provided in a illustrative embodiment of the invention causes the switch to open on a configured count of voltage losses even if a fault was not sensed just prior to the loss of voltage. This allows the first step of isolating both sides of the faulted section of line to be executed immediately without communication to other devices.
  • Another optional feature causes the configured count on voltage losses (subsequent to sensed faults) to be dynamically calculated locally based upon the position of the switch relative to the presently designated open tie switch. Configuration parameters allow this dynamically calculated range of counts to be further constrained by the user to always fall between a minimum and maximum number. Another option allows the switch to open after a single extended voltage loss.
  • the counting of faults followed by voltage losses can be configured to count each event as a fault either: 1) if the first voltage loss was preceded by a fault, or 2) if all voltage losses were preceded by faults.
  • Another unique feature of a illustrative embodiment of the invention is its modified one-shot-to-lockout capability. If a switch is closed as part of any automatic operation (or manually closed by a human operator), some sectionalizers, including the EnergyLine Model 2801-SC, can be configured to automatically re-open the switch if a voltage loss is detected during a brief interval following the operation (typically 5 seconds). A illustrative embodiment of the invention has the additional capability to avoid opening the switch until two counts of voltage loss have been detected. This becomes a benefit when the circuit's breaker reclose pattern includes an initial instantaneous close operation following a trip operation due to a fault.
  • reclosers could also be substituted such that the switch was opened/operated one or more times under load to clear the fault. Although this would require modifications to the prepackaged, commercially available recloser products to support the team coordination functions, comparable functionality to that provided by the sectionalizer could be achieved. It should also be noted that a variation of the one-shot-to-lockout capability implemented in the sectionalizer implementation is available in many reclosers as the “block reclose” option. The challenge with the approach of substituting reclosers for sectionalizers, as mentioned in the introduction, would be to coordinate the protective settings of these reclosers to prevent excessive switching or tripping/lockout of the wrong device.
  • the sectionalizing logic will be set up to open all switches between the fault and the normally open tie switch 108 G. This allows the present embodiment of the invention to reclose switches one at a time to gradually increase the load seen by the distribution system to aid the system in resuming service to users.
  • the node Once any node has finished sectionalization the node enters the transfer process state illustrated in flow diagram of FIG. 6 in which a node will attempt to close its switch. Also a node will enter the transfer process when it receives a communication that another node or team of nodes has entered the transfer process.
  • the transfer process state could be initiated by an event other than finishing sectionalization.
  • an event other than finishing sectionalization it may be desirable to have other events trigger the system into action.
  • Each node is continually updating the record in its database concerning its own status information.
  • the ball is sent to each node only in the synchronization process state, each node maintains an updated record on its own status.
  • the node executes step 612 and starts the end process timer task.
  • This timer ensures that the nodes do not spend too long trying to complete the task. Should something prevent the node from completing the task in the allotted time, the timer will end the transfer process state.
  • Each node will use the same start time for its timer as the node that first initiated the transfer process. In this way, all nodes in the transfer process will “time out” at the same time. The operation of this timer and the task it calls are shown in FIG. 8 and will be discussed below.
  • the length of the timer can be set by the system operator to meet the needs of the particular system being controlled. For example, to ensure the safety of repairmen working on the power lines after a fault has occurred, the timer could be set to remove the nodes from the transfer process a known period of time after the fault occurred. In this way, even if the conditions in the transfer process state are met which would have allowed a switch to close and energize a power line, repairmen who have begun to service the system are not put in danger because the transfer process has timed out and the switch will not close.
  • each of these three nodes enters the transfer process on its own, triggered by its own logic, stored data and sensor readings.
  • the presently illustrative embodiment of the invention does not require central control, communication, or approval for any of the nodes to enter this state.
  • the node proceeds to step 616 and determines if the switch it is controlling is closed during the normal operation of the distribution network.
  • switches 108 A, 108 B, 108 C, 108 D, 108 E, and 108 F are closed during normal operation of distribution system
  • switch 108 G a tie switch, is open during the normal operation of the system. Since switches 108 A, 108 B, and 108 C are each normally closed during the operation of the system, these nodes will continue on to step 618 .
  • each of the nodes that has entered the transfer process state will transmit its updated record to the next active node listed in the database and the previous active node listed in the database.
  • node 108 A will transmit to node 108 B
  • node 108 B will transmit to nodes 108 A and 108 C
  • node 108 C will transmit to nodes 108 B and 108 G.
  • each switch that has entered the transfer process state will inform its nearest neighbors of its progress.
  • each switch that has entered the transfer process state will inform its nearest neighbors of its progress.
  • each switch that has entered the transfer process state will inform its nearest neighbors of its progress.
  • each switch that has entered the transfer process state will inform its nearest neighbors of its progress.
  • each switch that has entered the transfer process state will inform its nearest neighbors of its progress.
  • each switch that has entered the transfer process state will inform its nearest neighbors of its progress.
  • each switch that has entered the transfer process state will inform its nearest neighbors of its progress.
  • each switch that has entered the transfer process state will inform its nearest neighbors of its progress.
  • each switch that has entered the transfer process state will inform its nearest neighbors of its progress.
  • each switch that has entered the transfer process state will inform its nearest neighbors of its progress.
  • a “nearest neighbor” may be one of the switch positions within the node itself.
  • a nearest neighbor database is assembled from the information contained in the internal team database. The transfer logic is then executed using the information in the nearest neighbor database. If the node is a multi-switch node, separate nearest neighbor databases will be constructed for each switch position.
  • the nearest neighbor database consists of information from the local node and the two nodes that are physically adjacent to it.
  • node 108 G When node 108 G receives the communication from node 108 C, node 108 G will start the transfer process state. In general, when one node receives a communication from another node that the other node has entered the transfer process state, the node receiving the communication will itself enter the transfer process state. This procedure allows the system to self organize, eventually putting each node of the system into the transfer process state without requiring any communication from a central office or any interaction with a human.
  • each node of the present invention can operate based only on its sensors and the communicated information. Due to this simple operating structure, the present invention can be easily expanded or reconfigured by simply reordering the nodes in the database without the need to change the programming or logic of the present invention. For example, to add a new node between nodes 108 B and 108 C of FIG. 1 , the system operator would physically insert the new node into the system at the appropriate place and program it into the database between nodes 108 B and 108 C. This is accomplished by moving the records for all of the nodes in the database after node 108 B down one space and inserting the record for the new node in this newly created space in the database.
  • Node 108 G executes step 612 , starts the end transfer process timer, sets it to end at the same time as the node(s) that initiated the transfer process, and then goes to step 616 . Since node 108 G controls a switch that is normally open it will go to step 638 . At step 638 node 108 G will observe its sensors, the information in its database, and the information sent to it by node 108 C to determine whether it can close. In the illustrative embodiment of the invention, the conditions listed in Table 1 are checked by the node in order to determine if it can close. The conditions used at step 4 in Table 1 are shown in Table 2. Other sets of conditions could be used without departing from the invention.
  • one valid closed switch and one valid open switch In order to close the normally open switch associated with a node, one valid closed switch and one valid open switch must be detected as the adjacent switches associated with adjacent nodes on either side of the normally open switch.
  • the following rules define the conditions that must be met for the normally open switch to validate the state of adjacent switches.
  • a normally open switch on the load side of a faulted line section may close for the purpose of restoring load if:
  • the process uses the total load to be transferred compared to the capacity of the alternate circuit.
  • Three basic set points are used by an engineer to limit transferred load. They are:
  • the transfer process utilizes, if available, the real time total load on the associated feeders.
  • This real time total load value may come over communications from any source such as a substation RTU.
  • the two set points that work with this process are the “Maximum Capacity for Transfer” and the “Maximum Rated Feeder Capacity”.
  • the “Maximum Capacity for Transfer” is the configured amount of load that may be transferred to an alternate feeder when that feeder is lightly loaded.
  • the “Maximum Rated Feeder Capacity” is used in combination with the actual real time load. The difference between these two is the present real time capacity the alternate feeder can handle. In order for a transfer to occur, the load that was reported to exist before the reconfiguration event began by the next open switch must be less than both the present real time capacity and the “Maximum Capacity for Transfer”.
  • the real time load must be sent to the switch controls at least once every 20 minutes. After 20 minutes past the last reception of real time load the value goes to undefined. An undefined value causes the fall back process to take affect. This prevents old load data from allowing transfers to occur when the source of this data fails to report it.
  • the fall back process uses the “Capacity for Transfer (total feeder load N/A).” This value is intended to be a conservative value. When configuring this value the engineer should take into account average loading, peak loading, and the emergency load capacity on the alternate feeder. The engineer should feel comfortable that a transfer of this amount of load can occur at any time and still be accommodated by the alternate feeder.
  • the switch at node 108 G can be able to close.
  • the node can determine on its own whether or not it can close its associated switch. Additionally, only one message had to be sent to enable node 108 G to act to restore service—the message from 108 C.
  • the normally-open switch is thus closed with the additional assurance that the protective settings of all of the source-side team members have been preselected to handle the additional load.
  • node 108 G would go to step 640 and execute the synchronization and error check routine. If an error is detected during this time then at step 642 it is recorded and the transfer is stopped. Otherwise, at step 652 a check is made to see if this is the first iteration of the loop. If it is the first iteration the local record is transmitted to the nearest neighbors at step 653 . If it is not the first iteration then the process continues at step 638 to determine whether the normally open switch can be closed.
  • node 108 D will receive the notification and enter the transfer process state at step 610 . Node 108 D will continue through the transfer process (steps 612 , 616 , 618 as stated elsewhere) and since it is on the unaffected portion of the circuit it will pass through step 644 and into step 645 .
  • steps 645 - 651 provide notification and enable nodes that were otherwise unaffected by the transfer event to adjust their protection settings to pick up additional load during the transfer process. It would not deviate from the scope of this invention for the adjustments to include other settings or operations related to switched capacitor banks, voltage regulators or other devices.
  • node 108 D If node 108 D is the last member of the team (only one neighbor exists), it will calculate the segment count allowed in step 647 and transmit its local record, including new segment count, to its neighbor in step 649 . Then, node 108 D will enter step 632 where it will wait for the transfer process to end, along with checking for errors in step 634 .
  • node 108 D If node 108 D is not the last member of the team (it has two neighbors), it will enter step 646 to transmit its local record to its nearest neighbors. Before it can continue through the transfer process, it must receive a notification back from node 108 E with 108 E indicating it has progressed into step 632 (node 108 E has entered the transfer process and followed the same process as node 108 D). Until that indication is received, node 108 D will cycle through the error detection step 650 . Once the data is received, node 108 D can continue to step 647 to calculate a new segment number, step 649 to transmit its local record to its neighbors, and to the step 632 and step 634 , looping until the transfer process is complete.
  • Node 108 G will receive the updated local record from node 108 D when node 108 D has passed through step 649 and into step 632 . Node 108 G can now use this updated record to determine if it can close in step 638 . If node 108 G is still not allowed to close it will continue with the error detection loop which includes step 640 . If node 108 G is allowed to close, it will continue to step 626 to close its switch.
  • the node will continue to cycle between steps 638 , 640 and 650 until the switch can be closed, an error is detected, or the end transfer process timer expires. It should be noted that in the case of teams containing only sectionalizing switches without protective capabilities, the number of segments criteria will always be satisfied without additional communication, and the only typical condition that would delay closing of the switch would be a wait for the other affected nodes to reach the correct transfer process state. This distinction allows the support for profile modification in protective devices to be added to prior reconfiguration products in a compatible manner.
  • node 108 G determines that it can close, its associated switch it will proceed to step 626 and attempt to close it.
  • switches will have safety devices called lockout logic, as detailed above during the discussion of sectionalization, that will force the switch back open and keep it open if an anomaly such as a voltage loss is detected when the switch is closed.
  • the switch determines if the closing operation was successful. If it was not then at step 624 an error flag is set and the transfer process is stopped. If the close operation was successful, then power is restored to users 104 C and node 108 G continues to step 630 .
  • node 108 G sends its updated record to its nearest neighbors, nodes 108 C and 108 D.
  • Node 108 D now enters the transfer process state, and as nodes 108 A, 108 B, and 108 C did, node 108 D will proceed down the flow chart to step 618 and send its updated record to nodes 108 G and 108 E. This will cause node 108 E to enter the transfer process state and signal nodes 108 D and 108 F causing 108 F to enter the transfer process state and signal node 108 E with its updated recorded.
  • one feature of the invention is that from only the ordering of the nodes in the database and the rules of the flow charts, each node can determine the appropriate actions to take independently of actions taken by other nodes. Nodes do not command other nodes to take any given action, nor is central control or human intervention necessary to coordinate the response of the entire system. The decisions made by each node are based solely on information it has stored in its database and sensors attached to it.
  • Nodes 108 A, 108 B, 108 C, 108 D, 108 E, and 108 F all will proceed to step 644 . Since the switches at nodes 108 D, 108 E, 108 F are normally closed switches and they were not affected by the fault, they will be sent to step 632 at step 644 and will wait for the process to time out while they perform the synchronization and error checking loop with steps 634 and 636 .
  • the switches at nodes 108 A, 108 B, and 108 C were affected by the event, they each proceed to step 620 .
  • the conditions listed in Table 3 are checked by the node in order to determine if it can reclose.
  • the conditions used at step 4 in Table 3 are shown in Table 2. Other sets of conditions could be used without departing from the invention.
  • step 622 If these switches cannot be reclosed, then, the nodes will go to step 622 and perform synchronization and error checking. In the illustrative embodiment if an error is detected, then in step 624 a flag will be set, and the transfer process state will be stopped. It will be appreciated that in other implementations of the invention error flags may cause different results. In one example, error flags may be prioritized so that lower priority errors may not stop the transfer process.
  • step 654 the number of segments that can be picked up is recalculated using the rules for calculating the number of segments field during transfer events. If the result of this recalculation may allow the normally closed switch to reclose, at step 620 the logic will exit from the loop and reclose the switch at step 626 . Otherwise, each node will cycle through steps 620 , 622 and 654 until the switch can be reclosed or the process timer expires.
  • one valid closed switch and one valid open switch must be detected as the adjacent switches associated with adjacent nodes on either side of the normally closed switch.
  • the following rules define the conditions that must be met for the normally closed switch to validate the state of adjacent switches.
  • a presently open switch on the load side of a faulted line section may close for the purpose of restoring load if:
  • a normally closed switch on the source side of a faulted line section may reclose if:
  • a node can determine on its own whether or not it can close its associated switch. Assume that all of the conditions are met to allow the switch at node 108 C to be able to reclose its switch. The switch will then be reclosed at step 626 .
  • node 108 C will determine if the switch was successfully reclosed. If it was not, then an error flag is set and the transfer process is stopped in step 624 . If the switch was successfully reclosed, then the node proceeds to step 630 and informs its nearest neighbors, nodes 108 B and 108 G, of its progress by sending them an updated version of its record. Node 108 C then enters the loop between steps 632 and 634 where it performs the synchronization and error checking routine while it waits for the end transfer process timer to time out. If an error is detected, step 636 is executed and a flag is set and the transfer process is stopped. An example of an error is if the lockout logic causes a switch to reopen.
  • one benefit of the present invention is its ability to operate by systematically closing only one switch at a time so that the load to the system is brought on line gradually, one segment at a time. This helps ensure that the power source will not be overloaded due to too rapid an increase in demand.
  • node 108 B When node 108 B receives the communication from node 108 C, assume that node 108 B will have enough information to know that according to the conditions listed in Table 3, it should not close since node 108 A detected a fault and node 108 B did not. This must mean that the fault was between nodes 108 A and 108 B. Therefore, node 108 B will cycle between states 620 and 622 until an error is detected or the end transfer process timer expires. Node 108 A, since it has detected a fault, will also not be allowed to close and will cycle though steps 620 and 622 until an error is detected or the process timer times out.
  • the nodes When the end transfer process task timer times out, the nodes will all return to step 310 of FIG. 3 and resume synchronization, error and integrity checks until the original fault is repaired. If the fault is repaired, the system will enter the return to normal process state of FIG. 7 discussed below. If another fault occurs before the previous one has been corrected, it would not deviate from the present invention for the system to re-enter the transfer process state and again reclose switches to return service to as many users as possible.
  • the return to normal process state can return the system to its normal operating configuration.
  • This process can also be used to reconfigure the distribution system to any desired system set up of open and closed switches without deviating from the present invention.
  • the fault in distribution line 106 has been repaired or cleared and switch 108 A has been manually reclosed, power will be restored to users 104 A.
  • node 108 B will sense that normal voltage has been restored to the distribution line between nodes 108 A and 108 B and it will be triggered to enter the return to normal process state after node 108 B has detected stable 3 phase voltage on the channel for a predetermined time and no errors exist and the normally open switch has not detected a fault. Once any switch in the system has entered the return to normal state, it will signal all other switches to enter the return to normal state.
  • a node without voltage sensors on the normal source side of the switch may use information from the nearest source side neighbor to determine if voltage has been restored. To do this, the node assumes that voltage has been restored if the nearest source side neighbor node has a closed switch and is detecting good voltage. The local node must see this condition continue for a predetermined time to validate that voltage has returned.
  • the return to normal process can be triggered on demand by an external device or human. It will be appreciated that this on demand activation of return to normal can be used for, but not limited to, starting the return to normal process before the predetermined time has elapsed, or as a one step method of return to normal without manually closing any team switches.
  • an open transition is one in which the source of supply of power to users is interrupted in the process of switching between alternate sources of supply. For instance, in this example, if tie switch 108 G was opened up before switch 108 B was closed then users 104 B and 104 C would momentarily lose power. This would be an open transition. In a closed transition, switch 108 B is closed before switch 108 G is opened and users 104 B and 104 C do not lose power.
  • the system operator can configure the system to operate in either an open or closed transition mode.
  • the normally open device During a closed transition, the normally open device must reopen following the allowed transfer time whether it has heard from the normally closed but presently open device or not. This is done to prevent the parallel of lines for an extended period of time. Also, if the node with the normally open switch detects that a parallel condition exists before the return to normal process has begun, the node will begin the return to normal process and open its switch to break the parallel.
  • the node starts the end transfer process task timer.
  • Each node will use the same start time for its end transfer process timer. This timer ensures that the system does not spend too much time attempting to execute the return to normal process.
  • the timer is set to run for a predetermined time set by the system operator. In one embodiment, this timer is set to run for one minute.
  • the node next executes step 716 . Since nodes 108 A-F are normally closed switches, each of these nodes continues on to step 718 .
  • Switches 108 D-F are normally closed switches that were not open so they will each go to step 750 , where if the transition method is closed the nodes will continue to step 751 to perform actions that will prepare them for the closed transition. The nodes then continue to step 730 and perform a synchronization and error checking loop while they wait for the process to end. If the transition method is open, the node will simply progress from step 750 to step 730 to perform the synchronization and error-checking loop.
  • Switches 108 A and 108 C are normally closed switches that were reclosed by the transfer process so each of these nodes will also go to step 750 , where if the transition method is closed the nodes will continue to step 751 to perform actions that will prepare them for the closed transition (as stated previously). The nodes then continues to step 730 and performs a synchronization and error checking loop while they wait for the process to end. If the transition method is open the nodes will simply progress from step 750 to step 730 to perform the synchronization and error checking loop.
  • Node 108 B is a normally closed switch that is open so it moves on to step 720 to determine if it is an open transition.
  • node 108 B goes from step 720 to step 752 to perform actions that will prepare it for the closed transition (as stated previously), then to step 722 .
  • the normally open switch, 108 G is armed to reopen (see below)
  • the switch on the supply side of switch 108 B, switch 108 A is closed, and communication of the initial start return to normal process message was successful to all members of the team, then node 108 B will continue on to step 724 and close its switch.
  • the requirement of the reply to the initial start return to normal process message insures that all nodes within the team have prepared themselves for the closed transition state.
  • the normally open switch is armed to reopen when it has entered the return to normal process, the method used will be a closed transition, and it has informed all other nodes in the team of its state, as will be seen in greater detail below.
  • node 108 B will perform a synchronization and error-checking loop and return to step 722 . This loop will continue until either all conditions are met or the end transfer process timer expires.
  • step 726 the node checks to see if the switch is closed. The switch could have been reopened by lockout logic or any other safety feature on the switch that might force it back open. If the switch is closed then at step 728 , the node will inform its nearest neighbors and the normally open switch, 108 G, by sending them an updated version of its record. The node then goes to step 730 where it performs the synchronization and error checking loop while waiting for the end transfer process timer to time out. If the switch is not closed at step 726 , then at step 732 an error flag is set and at step 734 the node informs all other nodes that an error has occurred and the node then goes on to step 730 .
  • step 720 the node will go to step 746 . If the normally open switch is open and the supply side switch, switch 108 A, is closed then the node will continue on to step 724 . If either of these conditions is not met, then the node will perform a synchronization and error-checking loop between steps 744 and 746 .
  • Switch 108 G is a normally open switch so at step 716 it will proceed to step 736 . If the system is undergoing a closed transition, the node goes to step 753 to perform actions that will prepare it for the closed transition (as stated previously), then to step 754 where it will arm itself to open and send its local database record to all other team members, and then to step 738 where if all the other switches are closed, node 108 G will open the normally open switch at step 740 . The node will then check if the switch is actually open at step 742 . If the switch is open it will send its updated record to all the nodes at step 734 and then enter the loop at step 730 and wait for the process timer to end. If the switch is not open at step 742 then an error flag will be recorded at step 732 and the node will proceed to step 734 .
  • step 738 if all the other switches were not closed, then the node will loop to step 744 and perform synchronization and error checking and look back to step 738 . This loop continues until all the switches are closed, an error is recorded or the timer expires.
  • step 736 node 108 G would not look to see if other switches were closed and it would skip to step 740 , open the switch and continue the flow chart from that step.
  • the node Whenever a node enters either the transfer process or the return to normal process, the node starts the end process timer task.
  • the flow diagram for this task is show in FIG. 8 .
  • the node loops until the timer expires.
  • the timer is initiated when the node enters the task and from the information sent to the node by other nodes, each node will know the time at which the first node to enter the task in question began the task. In this way, all of the nodes can set their end process timers to expire at the same time. It would not deviate from the invention to have the end process task timer be of different durations for the transfer process and the return to normal process.
  • step 814 the node will stop the process it is in at step 814 .
  • step 830 if the process that was stopped was a closed transition return to normal event, the node will continue to step 831 to return settings that were changed to prepare for the closed transition (for example unblocking the ground relay if applicable). It should be appreciated by those skilled in the art that the reset of the closed transition settings could also be accomplished after step 734 or at any time when the normally open switch has been verified to be successfully reopened. From both step 830 and 831 , the node will continue to step 816 and look to see if the switch is in the proper position for the end of the process that was stopped. For example, is the switch in its normal position at the end of the return to normal state. If the switch is not in the correct position, then step 818 is executed and an error flag is set and the node returns to the synchronization process at step 820 .
  • step 816 the node goes to step 822 and checks to see if the circuit is in the normal configuration. If it is, then the node goes to step 820 . If it is not in the normal configuration, then the node goes to step 824 and checks if the return to normal is enabled. If the system does not have the return to normal enabled it will go to step 826 and change its operation state to no operation and wait for further instructions before it can re-enter the ready to transfer state. From step 826 , the system will go to 820 .
  • step 828 the node changes its operation state to ready for return to normal and then proceeds on to step 820 .
  • the sideline team node may be distinguished from active team nodes mentioned previously in two ways; 1) the sideline team node is not active within the synchronization and integrity check process, 2) the sideline team node does not itself directly execute a process associated with the reconfiguration process described previously. Instead, the sideline team node is used by an active team node to acquire additional data about the environment around the team. This data can then be used to alter the process within the team. This will become clear with the use of two examples below.
  • the method for acquiring the additional data will usually involve data communications. This may be achieved using various communications technologies for point-to-point communications or may be achieved by sharing the same communication infrastructure used by the team communication channel, 110 . In addition, in the case of dual or multiple switch nodes, the communication step may be bypassed entirely.
  • each active team node may be responsible for one sideline team node.
  • the addressing of sideline team nodes is contained within a table similar to the database of node records.
  • the address data for the sideline team node is contained in the record with the same device number as the record in the database of node records for the active team node that is responsible for the sideline node.
  • Other means for storing sideline team node addressing is also possible without deviating from the intent of the present invention.
  • the table storing sideline node information to include identifiers that would specifically associate a sideline team node with an active team node, thereby allowing the number of sideline team members per active team node to be greater than one.
  • S 1 - 3 ( 901 , 902 , 904 , 1001 , 1002 ) are all sources of supply for the circuits.
  • Nodes 903 A, 903 C, 1003 A, 1003 C, 1003 D and 1003 E are all normally closed switches.
  • Nodes 903 B, 903 D and 1008 B are all normally open switches. It will be obvious to those skilled in the art that these simple examples were chosen for the purpose of illustrating the possible uses of sideline team nodes, and that much more complex applications are possible. For example, it would be consistent with the present invention to utilize sideline team node communications to allow multiple teams to interact in order to reconfigure circuits with more than two possible sources.
  • the data available from the sideline team members could also be more complex.
  • This data could include protection data such as present load readings, maximum available load current, etc. to prevent an impermissible amount of load to be picked up, power quality data such as voltage or harmonic content that could also be used to block transfer if it would negatively impact customers on the alternate source, or other device-specific data such as abnormal conditions in the sideline node controller.
  • the first example refers to sideline node 903 C and team nodes 903 A and 903 B in FIG. 9 .
  • Team node 903 B is responsible for collecting data from sideline node 903 C, and using that data to make decisions about the operation of the team.
  • the circuit containing team nodes 903 A and 903 B is normally fed from source 901 , and uses the mid-point of circuit fed from source 902 as its alternate source such that if 903 A were to be opened by a reconfiguration event, and 903 B closed, the load served between nodes 903 A and 903 B would be fed from the alternate source 902 .
  • source 904 is not capable of handling the additional load between 903 A and 903 B if node 903 D were closed and 903 C were open, and a reconfiguration event were to occur. For this reason the data that 903 B retrieves from 903 C is used to determine the alternate source that is presently available. If 903 B finds that 903 C is closed, source 902 must be the present alternate source, therefore, the load between 903 A and 903 B could be transferred to the alternate source if necessary. If 903 B finds that 903 C is open, source 904 would be the present alternate source, therefore a reconfiguration event can not be allowed.
  • This logic is illustrated in the flow diagram in FIG. 9 .
  • the steps in this flow diagram are executed in parallel to, but not connected with, the synchronization and integrity check process running in node 903 B. It is assumed that upon start of the node's logic execution that a sideline node has been configured into the sideline table in node 903 B. Node 903 B begins polling the sideline node at step 921 . With the data retrieved node 903 B checks whether the sideline node is closed at step 922 . If the sideline node is not closed, or the closed status of 903 C cannot be positively verified for any reason, the logic proceeds to step 923 to set a flag to prevent automatic circuit reconfiguration from occurring.
  • the polling loop, 921 - 926 could be replaced by a spontaneous report by exception scheme or other means to acquire the state of 903 C, subject to the restriction that the data must be acquired and validated within a period of time comparable to the configurable polling delay referred to at 926 .
  • step 922 If in step 922 it is found that the sideline node is closed, node 903 B continues to step 924 where if the flag to prevent reconfigurations is set, it can be cleared in step 925 , otherwise no further action is required. In all cases, node 903 B will go to step 926 to wait a preconfigured amount of time before going back to step 921 to begin the polling cycle again.
  • node 903 B could be used as a sideline node off of either node 903 C or node 903 D. In this way each of the two teams could prevent the other team from automatically reconfiguring its circuit if either team was already in a reconfigured state. It can also be appreciated that as teams grow in nodes, many more interconnection possibilities arise, each being consistent with the present invention.
  • node 1003 E is a sideline node (a simple, SCADA operable switch with fault detectors) installed on a tap line that feeds to a dead-end.
  • Sideline node 1003 E is contained in the sideline table of node 1003 D such that node 1003 D is responsible for retrieving data from node 1003 E and using the data to enhance team operation.
  • the settings of the breaker at source 1002 are configured such that the breaker will go to lockout on the third operation. It is also desirable to prevent any switches from opening on the first operation of the breaker to allow temporary faults to clear. This implies that nodes 1003 C and 1003 D must open their switches after the second operation in order for the fault to be cleared, a reconfiguration to begin, and as much of the load to be picked up as possible.
  • source breaker 1002 would operate twice, after which nodes 1003 C and 1003 D would open to begin the reconfiguration process. As described earlier, node 1003 B would close into open node 1003 C, the breaker would close into open node 1003 D, leaving the fault apparently isolated between nodes 1003 C and 1003 D.
  • node 1003 D will poll sideline node 1003 E for data. This data will include the indication of a fault past sideline node 1003 E. Knowing the normal configuration of the circuit, and the more specific location of the fault, node 1003 D can further isolate the fault by sending a command to sideline node 1003 E to open its switch. Upon verification that the sideline node's switch is open, node 1003 D can automatically begin the return to normal process, restoring load to the customers bordered by the three nodes 1003 C, 1003 D and the now open node 1003 E.
  • This logic is illustrated in the flow diagram in FIG. 10 . As stated previously, the logic is only executed following the end of a reconfiguration event, and before a return to normal event.
  • the node enters the logic and polls the sideline node at step 1021 . If the data retrieved indicates that no fault was detected by the sideline node at step 1022 , or any other abnormal condition is detected such that the location of the fault cannot be verified to be on the load side of 1003 E, the node proceeds to 1023 to end the logic. If a fault was detected at step 1022 , the node then determines if the sideline node is presently open in step 1024 .
  • step 1025 the node continues to step 1025 to where it sends an open command to the sideline node.
  • the node then again checks if the sideline node is open in step 1026 and if not can stop the logic at step 1027 , or optionally retry the open command. If the sideline node is now open at step 1026 , it will continue to step 1028 where it will signal the return to normal logic to begin. If the node were to find the sideline node 1003 E initially open at step 1024 , it would immediately continue to step 1028 to signal the return to normal logic. In both cases, this logic ends at step 1029 after the return to normal logic has been signaled.
  • node 1003 E can be associated with an automatic sectionalizer, contained in another team, or backed up by an alternate source without deviating from the present invention.
  • the method disclosed above is incorporated into the operating instructions or stored program of the team node controller 200 .
  • Alternate embodiments in the form of microprocessor-based add-on boards support retrofit of products configured according to existing, prepackaged line recloser controls and substation breakers.
  • FIG. 11 A block diagram of the recloser version of the add-on board is shown in FIG. 11 .
  • the board consists of a small electronic microprocessor-based circuit board, which can be provided for mounting inside an existing recloser control cabinet, or in a nearby auxiliary cabinet.
  • the power for the board is supplied by the recloser's power supply/battery backup system 1104 .
  • the team reconfiguration logic is entirely contained in the memory 1105 and CPU 1106 of the add-on board, while the circuit protection logic and active switching functions remain in the recloser control.
  • the interface between the add-on board and the recloser is based entirely on digital communications.
  • node controller of FIG. 2 can be partitioned between the add-on board and the retrofit recloser control as follows:
  • the team communication functions 110 , 218 , 220 are provided by one or two of the communication channels 1101 and 1102 on the add-on board.
  • the third channel, 1103 is used to communicate with the recloser.
  • the team coordination logic performed by 208 and 210 including maintenance of the team database 210 is performed by the processor 1106 and memory 1105 of the add-on board.
  • the node's user interface for team functions 209 remains with the add-on board 1107 , while the recloser's user interface can still be used for accessing its standard functions.
  • All of the recloser protection features including overcurrent fault detection 212 , switch monitoring and control 216 are utilized, with the add-on board receiving status from all of these features over communications.
  • Supervisory control over the recloser's associated switch (breaker) is provided to the add-on board via the communication protocol.
  • Power management and battery backup 1104 must be provided separately for the additional add-on board/communication equipment, although this may in some circumstances be shared with the recloser's power supply 222 .
  • the recloser point list is utilized.
  • load data required to support load pickup at steps 620 and 638 can be periodically sampled by the recloser, transferred to the add-on board using the point list and averaged inside the add-on board.
  • An additional benefit of the add-on board is its ability to extend the capabilities of the recloser's basic functions.
  • the Cooper Form 4C recloser supports only two protection profiles. Because of the additional storage and processing capabilities of the add-on board, additional profiles can be stored in the add-on board and loaded into the recloser when needed.
  • the extensions to the representations of protection profiles presented in this invention can be applied uniformly to all retrofit reclosers without regard to the capabilities of the individual device.
  • add-on board is provided by including the optional analog and digital I/O block 1108 .
  • This embodiment could be utilized for interfacing to a substation breaker lacking an adequate digital communication capability to support the team functions.
  • the digital I/O would then be connected to the breaker's status and override control points.
  • the analog I/O would be connected to current and voltage sensing devices to allow the node to provide the load and voltage monitoring functions of a team member.
  • the breaker's protection profile would be dictated by the breaker's independent settings and configured into the memory 1105 of the add-on board.
  • FIGS. 12-14 illustrate the overall logical organization and the data structure wherein more efficient and flexible response to abnormalities is provided to reconfigure and restore service to end customers (circuit reconfiguration); i.e. to enhance the reconfigurability of the distribution system especially in larger distribution systems.
  • “teams” of nodes or team members are defined in the distribution system having associated switching controls with the various teams communicating amongst each other to “negotiate” or work out the most efficient and expeditious reconfiguration of the system in response to a fault conditions and other circuit abnormalities.
  • FIG. 12 illustrates a representation of the overall logic of a single team member.
  • the Sectionalizing logic block in the Switch and Sectionalizer box is the same as described earlier in connection with the embodiment of FIGS. 1-8 and in U.S. Pat. No. 6,018,449 and based on EnergyLine Model 2801 or 2801-SC.
  • FIG. 13 illustrates the data structure for the overall system.
  • FIG. 14 represents an illustrative representation of the overall logic flow to accomplish the basic functions of the invention at a single team member location as shown in FIG. 12 based on the system data that is obtained as will be explained in more detail hereinafter.
  • the distribution system is organized or defined by fields, e.g. Field B including Team members Switches 6 , 7 8 and 9 and Field C including Switches 8 and 23 such that team member Switch 8 is a member of both Fields B and C.
  • resources are provided for each field that move between or visit each team member and cooperate and coordinate operation and system response of the team members.
  • the resources may be referred to as a “Coach” or “Agent” for each field, the term Coach being utilized hereafter for simplicity but not to be interpreted in any limiting sense.
  • the team members may also be referred to as “players” on the team.
  • the communicated information includes not only data on adjacent team members and data from other external teams representing system information, but also includes task identifiers and functional representations on how to respond to particular system conditions as sensed and in accordance with a plan of response per “negotiations” amongst teams.
  • the task identifiers and functional representations may also be characterized as instructions, responses and implementation rules.
  • the “primary mission” (function) of a Coach is to keep service to its respective (his being used hereafter for simplicity) Field, and will do so using information from his Field and from Coaches on adjacent Fields.
  • a secondary mission of the Coach is to restore a Field back to its normal state, and will do so immediately if that option exists. If the normal source is not available, the Coach will look to alternate sources as a temporary means to restore service to his Field. In addition, a Coach cannot act by himself. To insure coordination and structure a Coach must consult with the Coach from the adjacent Field, and they must agree on the course of action.
  • the Coach can be characterized in various ways for understanding and illustrative purposes, e.g. 1) a resource which is communicated or moves around and visits team members to control and coordinate tasks; 2) a token that gives a Switch Control the power to make decisions, provided the Switch Control has all the necessary tokens.
  • Fields link to other Fields at Team member locations. Any single Team member will be part of one or more Fields, and so will be visited by one or more Coaches.
  • a Field must contain at least two Team members.
  • a substation breaker can be one of those Team members, provided that an interface module exists at the breaker. Information will be passed between Fields using the Team members as semaphores. In this way the status of any single Field can be propagated throughout the associated part of the distribution system.
  • the rules for restoring service are very similar to the rules that exist in the prior IntelliTEAM product as discussed hereinbefore.
  • the presence or absence of voltage and fault current on adjacent line sections will remain as the key to service restoration.
  • Previous rules for coordination of logic will be replaced by similar rules related to the Coach process.
  • a Coach will carry the necessary state machine information, and along with the state machine information from an adjacent Coach, coordination will be guaranteed.
  • Time synchronization over a wide area will be replaced by individual activity timers.
  • a Coach needing additional information from an adjacent Field will allow the adjacent Coach a limited time to retrieve that information. If the timer expires, the first Coach has the option to find another solution at another Team member.
  • a Coach can dynamically prioritize the strategy for restoration of the Field.
  • the Coach will be required to visit each team member on a predetermined time interval. During quiescent periods this means the Coach will travel between Team members on some regular interval (maybe 3 minutes). If a Team member does not hear from the Coach in this period of time, the Team member will flag an error condition. Each Team member will have a separate timer associated with it that will be updated with any visit. Due to the lack of a common clock, the coach will try to visit every team member in half the configured time. This should handle the potential communications propagation delay (which will be assumed to be zero).
  • Each Team member will also be able to call out to the Coach, and all other Team members on the Field, when a local event occurs that will affect the Field. For example, manually placing a Switch Control in Disable Automatic mode will initiate a message to the other Team members. This will cause the Coach to also learn of this change in status, and use this new information when other events occur. All events categorized as critical will be immediately propagated in this way.
  • Coaches contains necessary and desirable data to perform the tasks.
  • the Coach carries a set of task identifiers along with the data. These task identifiers will cause specific logic paths to run in the switch control when the Coach arrives as discussed further in connection with FIG. 22 . Both the task identifiers and the data will change as the Coach travels from team member to team member.
  • a Coach has a coach ID number and an incrementing visit counter. Normally the coach roams the field at will. He must visit every team member in a prescribed period of time though. If he arrives at a team member that has already received that ID and visit counter (the counter must be greater than the last if the ID is the same), the coach assumes he is a duplicate and dies. If the coach arrives to find another coach with a higher ID has visited, again, this coach dies. If a team member doesn't hear from the coach within a prescribed period (2 ⁇ the visit time), that team member can spawn a new coach with an ID number one higher than the last coach he heard from, and a new visit counter. The new coach must determine the state of the field and begin to take action if necessary.
  • the Coach will carry task identifiers (numbers) that a task manager will perform.
  • the tasks that need to be performed at each team member will change as the conditions change in the field.
  • Each coach includes a list of active tasks that he is working on. At each team member he will evaluate the list of tasks, perform any action possible, and add or remove tasks as necessary.
  • the software facilities for the coach function e.g. coach logic executable code, will reside at each team member.
  • the task list will contain records that consist of a task number, the coach that owns it, and a priority of the task.
  • Tasks have attributes which include the Coach ID, Task Owner (the team member where the task was originated), a Task Sequence (unique ID #), and a Time-to-Run attribute.
  • Task Owner the team member where the task was originated
  • Task Sequence unique ID #
  • Time-to-Run attribute a Time-to-Run attribute.
  • the evaluation of team readiness can be broken down into the following four categories.
  • the user may enable or disable funcationlity on a per-team basis.
  • the setup parameter will be available as a SETUP function of Team Configuration, once for each team on each team setup.
  • the parameter must be a global parameter so that it is set the same in all members of the team.
  • the term global is used herein to mean overall controlled system. The coach will be responsible for verifying that all team members on the field contain the same status, and will issue an error if they do not.
  • a team member (switch) will be operational if the following are true:
  • the Ready to Transfer indication is primarily a user interface issue. A team will be Ready when all team members are Operational. The Ready to Transfer indication displayed at any one team member will not exactly follow the true ready state of the team. It will be delayed in transition between on and off for the amount of time it takes the coach to return to the team member.
  • the operational status of the team members will be indicated by the state of the TEAM mode bit in the automatic operation byte the coach carries for each switch.
  • the Ready to Transfer indication is on a team basis. For example, a Scada-Mate team member associated with two fields will show one Ready to Transfer indication for each field/team.
  • This source can be any open switch around the field, including the source switch that originally tripped open. The coach must visit as many team members as necessary to collect the information needed to make this determination. The rules for the selection of an alternate source follow.
  • the coach must first assume his field is faulted and set the fault indication flag. He must then look for a load switch on his field that also detected an overcurrent. If he finds another team member indicating overcurrent, the coach can assume the fault is downstream in an adjacent field, and clear the fault indication flag for his field.
  • a field is considered to contain a fault condition if one and only one team switch on that field indicates an overcurrent fault.
  • the first choice for restoring service to the field should be the normal source switch.
  • the coach must first verify that all necessary load switches on the field are open, then he should return to the normal source switch to request a close operation from the player. If the player can close the switch, the coach's primary responsibility is complete.
  • the coach will immediately look to the first alternate source team member to restore service to the field. Using the Switch Availability Rules (below) the coach will determine whether the first alternate switch is available, and if not, continue searching through the alternate source sequence list. If none of the switches on the alternate source sequence list are available, or the list is empty, the coach will use the Switch Availability Rules to search through all switches in the team.
  • the coach will travel to that switch and ask the player to close the switch. If successful, the coach's primary responsibility is complete. If not, the coach will again search for another switch in the team to close.
  • the switch can be used as a good alternate source if:
  • RTN return-to-normal
  • a process can be started to detect the restoration of this field by external forces (humans, scada, etc.). When this process has detected a stable restoration, an event can be generated for the coach to receive.
  • the process will include the monitoring for return of voltage, and a timer to determine the stability of the voltage.
  • the rules for the operation of an individual switch are similar to that as discussed in connection with the prior embodiment of FIGS. 1-9 .
  • the following is a list of the existing rules, modified only slightly. There are rules for single switch operation, dual switch operation, and recloser operation.
  • a team with one or more reclosers will be Ready to Transfer if:
  • the settings group consists of:
  • FIGS. 15-21 depicted therein are representations of system operation and response to an Overcurrent Fault Event occurring between two Switches 5 and 6 in the illustrative distribution system depicted in FIGS. 15-21 .
  • FIG. 16 An overcurrent fault occurs between switches 5 and 6 on Field A, causing operations of the breaker on feeder 22 . Fields A, B and D are all affected, but only switches 6 and 7 detect the overcurrent condition.
  • FIG. 17 Switches 6 and 7 both open on 2 counts of voltage loss with overcurrent. The breaker on feeder 22 closes back into open switch 7 and holds good. At this point Field A truly has a faulted line condition, but Field B only thinks it has a faulted line condition.
  • FIG. 18 Switch 9 is configured for 3 counts of voltage loss without fault, so it is presently waiting for an extended voltage loss in order to trip open. In the mean time, Team Coaches on Fields A, B and D are all trying to restore service to load within their fields.
  • FIG. 19 The coach's job on Field A is easy. He can determine the fault is within his field and simply prevent the closing of either switches 5 or 6 . Likewise, the coach on Field D can do nothing until a sectionalizing event has taken place, so he is waiting for the expiration of the extended voltage loss timer in switch 9 .
  • FIG. 20 The coach on Field B, on the other hand, can use his team members to save the day. Coach B knows that the overcurrent was detected by both switches 6 and 7 , so he knows the fault is not within Field B. His first choice for restoring service to the field is the normal source, so he visits switch 7 to see if service has been restored from the source.
  • FIG. 21 Coach B finds that switch 7 is energized and ready to close. With no other coach to consult with, and no problem within his field, Coach B closes switch 7 . This immediately restores all of Field B load from the normal source, and restores service to Field D so that switch 9 no longer needs to sectionalize. Field A is left to be repaired and returned to its normal state manually.
  • FIG. 22 described therein is an illustrative flow diagram that may be employed and representative of typical operations performed by the present invention of FIGS. 12-15 at a single team member or player.
  • the various tasks called out therein are performed only while a coach is present. In this way, the coach can supervise the process and also leave after a sutiable visit time with updated global data including an updated events list.
  • Some of the basic functional requirements applicable to and achieved by the transfer tasks of this flow diagram include:
  • the switch shall only close, if all automatic-mode switches are opened. Each field is only responsible for seeking its source. All switches in a field must be opened, to conform with the “transfer” method of allocating one fields' load at a time, to a source. However, non-automatic-mode switches in the field may be closed, because of user action. In this case, the field shall add this switches' “other” field” load to the field's load requirements. If any Source switch trips open due to sectionalizing or to loss of source (extended volt loss) then all switches in that field will trip open, since the sectionalizing logic will trip open all switches downstream of the faulted switch. Therefore, if an overcurrent fault occurs within the field or upstream of the field, the source switch will trip open on this fault. Since all other field nodes are downstream of this fault, they will trip open through sectionalizing logic. An extended Loss of Energy timer condition (LOE) also causes switches to be opened through a process called accelerated tripping.
  • LEO Loss of Energy timer condition
  • a switch shall close only its negotiated-source switch.
  • Reason the load switches are closed by their field's Coach after a negotiation process.
  • a Coach attempts to restore an open switch state to its previous close state, after detecting voltage present, following the expiration of a Loss of Energy timer.
  • a Lineman or SCADA operator closes one of two open switches that bracket a faulted line segment—this cause the other open switch to seek an Return To Normal, since it should be closed, yet it is energized, with no fault present.
  • the software must close the switch AND open the normally open switch that must exist between the switch and its present source. This requires travel to the normally open switch to either open it (open transition) or set a timer to open it (close transition), and then travel back to the switch requiring a close to close it. And then travel back to the normally open switch to open it and cancel the timer.
  • the travel direction will always be towards the present source, when traveling to the normally open switch and towards the RTN source when traveling to the switch that desires a close. So, first travel in the present source direction to the normally open switch, by selecting this switch's field that doesn't have this switch as its source switch; this must be the source field of the switch's “source switch” field.
  • FIGS. 23-55 there is depicted representations of system operation and response of the present invention to the loss of a substation identified as S 1 , e.g. due to transmission failure.
  • S 1 a substation identified as S 1
  • the following notes apply to explaining the system response:
  • a coach has a coach ID number and an incrementing visit counter. Normally the coach roams the field at will. He must visit every team member in a prescribed period of time though. If he arrives at a team member that has already received that ID and visit counter (the counter must be greater than the last if the ID is the same), the coach assumes he is a duplicate and dies. If the coach arrives to find another coach with a higher ID has visited, again, this coach dies. If a team member does not hear from the coach within a prescribed period (2 ⁇ the visit time), that team member can spawn a new coach with an ID number one higher than the last coach he heard from, and a new visit counter. The new coach must determine the state of the field and begin to take action if necessary.
  • any team member that has witnessed the event may call out to the coach and the other team members within that field.
  • This call includes a sequence number, the nature of the event, and which team member made the call.
  • Each team member contains a process that continually monitors for these calls. If the call is to restore service to the local field, the coach must first visit the other normally closed team members to verify that they are open. Then he will move to normally open switches that can be used to restore service, going to the First Alternate if configured. If the call is to allow service to be restored to an adjacent field, the coach will immediately move to the calling team member.
  • the decision to restore a field (circuit segment) based only on loading will be done without prior contract for those resources.
  • the criteria will be the available ampacity of the feeder, updated as the reconfiguration progresses, and any restrictions placed on a field due to wire size or other limiting factors. The lesser of the two will be used.
  • the loading information is assumed to be up to date and accurate. This method does not prevent the overloading of a circuit when disjoint fields (such as on a bifurcated circuit) assume the loading information is correct, and both close to restore independent loads at the same time, or near to the same time.
  • the decision to restore a field when a segment restriction has been configured requires prior contract for the resource. This involves setting a simple lock if the adjacent field is the field with the segment restriction. If the field with the segment restriction is further toward the source, a coach may need to daisy chain, possibly through more than one field, down to field with the restriction in order to verify the resource still exists. He may then secure a contract for the resource. This may add time to the restoration process, but is necessary to prevent the overload of a feeder.
  • FIG. 24 Each feeder is limited to 600 amps of emergency capacity. This is the limiting factor for the first field on each feeder. For simplicity, each field has a peak loading of 100 amps, but at the time of the event every field was loaded only to 50 amps. Some restrictions on capacity and circuit segments will be included in a later Figure.
  • FIG. 25 The loss of transmission feeding substation S 1 has left feeders F 11 , F 12 , and F 13 without service. With no reclose counts, each of the sectionalizing switches can only wait for their extended voltage loss logic to time out and cause the switches to open. As soon as the event began, though, the loading averaging stopped so that the load prior to the event would be used during the reconfiguration process.
  • FIG. 26 Since there is presently 50 amps on each field in the system (for simplicities sake), and there are no other limitations configured by the user other than the original 600 amp limitation on the feeder, the available capacity of each of the alternate feeders can be easily determined. The available capacity of each of the fields on the alternate circuits is indicated below.
  • FIG. 27 For illustrative purposes, assume that the user has placed ampacity restrictions on some of the fields. There is still 50 amps on each field in the system, but fields K and T are each configured with an ampacity restriction of 300 amps.
  • FIG. 28 Also for illustrative purposes, assume that the user has placed additional circuit segment restrictions on field I. Fields downstream are limited by this “remote” restriction, therefore they must verify the availability of segments to add, and place a contract on that resource.
  • FIG. 29 Based on the foregoing, the extended voltage loss timers have expired causing all normally closed switches on feeders F 11 , F 12 and F 13 to open.
  • FIG. 30 Where only one normally open switch exists in a field, that switch becomes the “First Alternate” by default. Where a field has more than one normally open switch (field Q), the “First Alternate” can be configured by the user if desired. A field with no normally open switches will take service from where ever he can get it. The arrows indicate the likely movement of the coaches when the event begins, based on the rules for coaches.
  • FIG. 31 When the coach arrives at the switch that he would like to close, if the coach from the adjacent field is not already there, he can make a call to that coach to alert him. The coach will travel to the team member from where the call was made. With both coaches at the switch, a decision can be made as to whether to close the switch.
  • FIG. 32 At switches 2 , 5 , 8 and 29 , the restoring field has plenty of capacity, and no other restrictions, so those switches may close immediately. Although the loading is acceptable, the coach for field K knows that only one segment may be picked up by feeder 32 (as configured in Field I). Therefore, the coach for K must verify the segment is still available, and secure a contract for that segment, with field I.
  • FIG. 33 Coach K moves to switch 16 and calls for coach I. With the two coaches at switch 16 it is determined that no contract exists for the one line segment. At the same time, coaches for fields O and P are looking for restoration service from the alternate fields. Field P got the attention of coach Q first, so both coaches are now at switch 39 . Since field Q also had 50 amps on it, the available capacity of field Q is now 450 amps, with no other restrictions. Therefore, switch 39 can close.
  • FIG. 34 With a contract for the one line segment secured, coach K can move back to switch 20 , where a decision can now be made to close the switch. Note the movement of coach O back to switch 24 in an attempt to find a good source to restore service to his field.
  • FIG. 35 Coach L now moves to switch 22 where coach N is trying to get service restored. This request is denied by coach L based on the segment restriction. The same thing happens at switch 24 .
  • Coach P can also move to switch 27 where it can decide to restore service on its own, since there is no adjacent field.
  • FIG. 36 Coach O again moves back to switch 28 .
  • coaches O and Q are able to make the quick decision to close switch 28 .
  • Coach P also knowing of the same present available capacity, decides to close switch 27 . Notice the lack of prior coordination between fields allowed load to be picked up simultaneously, possibly overloading the feeder.
  • FIG. 37 Notice that the only load that was unable to be restored was Field N. Also notice the updating of the available capacity on feeders that were used to restore service.
  • FIG. 38 With so much of the load restored, a number of switches feel that they should start the Return to Normal process. Switches 4 , 23 and 24 are in this category. While the RTN timer can count down, RTN is not allowed to begin due to the two-coach rule. A coach that knows his field is not being fed from its normal source will not allow a coach from an adjacent field to start RTN.
  • FIG. 39 The transmission system is now restored, providing service to substation S 1 and feeders F 11 , F 12 and F 13 . Switches 1 , 25 and 26 can now begin to time down their RTN timers.
  • FIG. 40 The RTN timers expire, allowing the coaches to begin the process of returning each field to normal.
  • Field Q is configured for an Open transition, while all the other fields that include normally open switches are configured for Closed transitions.
  • the RTN process must take place first at the fields closest to the normal source, then work outwardly.
  • a Closed transition RTN requires notification of the normally open switch before it may continue (M-Situation).
  • FIG. 41 Although the RTN process will be occurring simultaneously on the three feeders, let's talk about feeder 11 by itself first.
  • Coach B finds out at switch 1 that the RTN process can start. Since it is a closed transition he must notify normally open switch 2 . This notification starts a timer in switch 2 which will force it to open after a prescribed timeout. This insures that a circuit parallel can not be left in place indefinitely, but it is expected that switch 2 will be opened prior to the timeout by the RTN process.
  • FIG. 42 With an acknowledgement back from switch 2 , switch 1 can now close.
  • FIG. 43 Coach B can now move back to switch 2 to force the open operation. This open operation does not require the “two coach” rule.
  • FIG. 44 Coach B then moves on to any normally closed but presently open load side switches.
  • Field C has been ready to RTN since the source side of switch 4 was reenergized by field B. Both coaches B and C arrive at switch 4 . Since the RTN timer had timed out earlier, only the notification process is needed.
  • FIG. 45 Coach C moves to switch 5 to notify of the impending RTN process. Switch 5 starts the “M-Situation Timer.”
  • FIG. 46 Coach C then moves back to switch 4 where the decision can be made to close. Field B is now back to normal.
  • FIG. 47 Coach C quickly moves again back to switch 5 where it can open the switch immediately. Field C is now also back to normal.
  • FIG. 48 At the same time as feeder 11 was returning to normal, feeders 12 and 13 were performing similar actions. In this case, though, field Q requires an Open transition back to normal. To accommodate this coaches O and P must get approval from all their presently closed team members that are connected to other fields before closing their normal source switches. Switch 28 denies the request because switch 29 requires an open transition.
  • FIG. 49 Since switch 39 is normally open, and it knows a normally open switch that requires an open transition is closed in field Q, it will open immediately in order to facilitate the RTN process on field P. After receiving this request for RTN, the coach on field Q can move to switch 29 to perform the open there. Load is ultimately dropped on all three fields O, P and Q.
  • FIG. 50 Coach P can quickly move back to switch 26 to close, returning field P back to normal right away. Coach Q may then move back to switch 28 to approve the RTN request.
  • FIG. 51 Coach O can now move to switch 25 , close it, restoring service to fields O and Q. Field Q is now also back to its normal state. Notice the available capacity for feeder 41 gets updated.
  • FIG. 52 Now coach O moves to switch 24 .
  • the “M-Situation Timer” process is completed by coach L, and switch 24 is allowed to close. Field O is now back to normal.
  • FIG. 53 Coach L moves to switch 20 to open that normally open switch, then goes to switch 22 .
  • FIG. 54 Three areas of activity are now occurring. 1) Coach N is able to go to switch 21 and immediately close, returning field N back to normal. 2) Coach K moves to switch 16 to remove the contract with field I for the one line segment. 3) And Coach L moves to switch 23 to allow the RTN process to commence. After Coach M sets the “M-Situation Timer” in switch 8 , switch 23 is able to close.
  • FIG. 55 Finally, coach M moves back to switch 8 to open it. The system is now back to normal.
  • the CA implemented as an autonomous processing task, i.e. independent of the Coach functionality and the Player functionality that manages the local switch, is employed to manage both the addition of load during load transfer, and the reduction of load on return-to-normal.
  • the CA may be characterized as a process that is active or enabled in each switch control and that manages only “Contract-related activities” as described hereinafter.
  • the CA functions by communicating locally with the Player task, and remotely with other CA's via CA-specific messages. It should also be understood that while the CA will be discussed in connection with a single-switch configuration, the CA is applicable to all devices such as dual switches, reclosers, etc.
  • the CA will be active to control the management of the line segment restrictions.
  • the CA is also active if a valid line segment limit has been announced (propagated down) from the source.
  • the line segment limit is continuously propagated out from the source (field) as the coach travels from team player to team player, as an independent process. As the line segment limit propagates outward (from the source field), lower set counts of line segment limits take precedence and are then propagated further. If load restrictions have been set based upon maximum amperage, the CA is then active in response to this setting.
  • the discussion of the CA functionality hereinafter is based on one of these settings or specifications such that the CA functionality has been enabled.
  • the Player does not request a Contract unless the circuit segment being energized is being fed from an alternate source, either directly or indirectly.
  • the closing of a source/sub switch would never require a Contract, but the closing of a tie switch (between sources) would always require a Contract.
  • the general rule (as will be explained in more detail hereinafter) is that a Contract is required if the present source Field, or granting Field, indicates it is being fed from an alternate source.
  • the indication of alternate source is initially set by the Coach that closes a normally-open tie switch. From that point the indication of alternate source is propagated out each time an additional circuit segment is restored. This way all teams will know they are on an alternate source, even if the switch that was closed to restore service was the normal source switch for that field (for example switched radial tap lines).
  • the logic at the Player (team member) level requires that if the granting field is already fed by an alternate source, or the local switch is a “last-load-only” position and the requesting field is being fed from an alternate source, or the local switch is a tie switch for the requesting field, the Coach will be informed so that he/she can take appropriate action regarding transfer restrictions. In this way an “alternate-source” flag (condition/indication) will propagate as necessary to subsequent fields energized from the same alternate source.
  • the Coach When the alternate-source flag is set, the Coach also performs a task (running on a periodic basis) to initiate a check for the ability to remove the alternate-source flag (condition). Since this task requires information from an adjacent team, the Coach will request the Player to perform the check and report back. The Player will look to see whether this switch on the requesting field is not a tie switch, and the other field still has its alternate source flag set, or, if this switch is a last-load-only switch and this field still has its alternate-source flag set, or, if this is a tie switch on the requesting field and current switch state is still closed. If any of these conditions are true the Player reports back that the Coach must continue checking. Otherwise the report is that the alternate-source flag may be cleared.
  • the flag In order for the clearing process to begin the flag must be cleared at the normal7ly-open switch first. During the return-to-normal process, when a normally-open switch is able to reopen, the alternate-source flag can be cleared without question.
  • the CA is effective to:
  • the CA ID's above are simply the communication address of the team member at which the CA resides. Since the team member may take part in two or more Fields, and there is only a single CA at each team member, the Field number must be included to further qualify the identification of the CA.
  • the time that the Contract was originally requested at the CR serves two purposes. It is used to uniquely identify the Contract (along with CA IDs and Field number). Unique identification of the Contract is used during maintenance of the Contract to be sure the Contract still exists in the locations where it is supposed to exist. In a modification to the present implementation the Contract time may also be used to determine the maintenance interval and mortality of the Contract.
  • the routing table included in the Contract is a simple list of the switch control RTU addresses that, when combined, will form the path between the CR and the CG. This creates a simple, connect-the-dots form of routing. Initially the only routing data that is known is the starting team member and the present source of each Field. The Contract's route during the first pass to the ultimate present source Field is along the path of present source team members. The communication address of each present source team member on each Field through which the Contract passes is appended to the Contract routing table. When the Contract arrives at the ultimate source Field (CG) it will contain all the information necessary to route both directions, regardless of the present state of the system.
  • CG ultimate source Field
  • the routing table has finite resources, and cannot store an unlimited amount of routing information. If during the course of routing back to the present source a CA finds that the routing table has overflowed, the CA must reject the Contract and route it back to the origin. The coach on the requesting Field will ultimately be notified through the Player and must then look for another alternate source.
  • the Field associated with each Contract route is saved in the Contract record as a required value in the data transmit process, and allows the CA to update the line segment count in the Coach record.
  • the CA's primary goal is to manage its local database of Contracts. This management includes the job of accepting a Player's request for a new Contract, obtaining control over the Contracted resource by communicating through CI's to a potential CG, maintaining the integrity of Contracts once issued, and dissolving Contracts once they are no longer needed.
  • the CA's resources for doing this consists of a Contract database containing Contract records, a CT which allows the CA to convey Contract information to other CA's, and the Field database.
  • the Player makes a request to the CA to obtain the Contract.
  • the CA creates a CT including a copy of a “draft” version of the Contract with all available information filled in, and sends it toward the present source, normally all the way to the present source Field.
  • the Contract State field is used to influence the processing of the Contract as it arrives at the recipient CA.
  • the Contract may stop at an intermediate CA if the next source side Field does not have a valid Line Segment Limit. In this way the CT process may be more efficient, allowing a CI to become a CG. Otherwise, CT's must pass through a CI in every Field on the way to the present source. CA's at each Field direct and forward the CT, indicating the Contract's present processing state, from the CR to the CG and then back to the CR. It should be noted that the independence of the Coach process and the Contract process simplifies, or eliminates the issues related to restoring Contract status for Coaches recovering from synchronization failures.
  • the CR has the primary responsibility to maintain, and possibly dissolve, accepted Contracts. Normally the CR is notified by the Coach through the Player when a Contract is no longer required. The CR may then dissolve the Contract by deleting its local copy and issuing a CT containing a “dissolve” status to the CIs and CG, traversing the Contract route.
  • the CR In general, the CR, with the assistance of the CG and all CI's, maintain the integrity of existing Contracts. This is accomplished by monitoring a Contract's activity timer, Contract Timer, and periodically informing all other CA's of the Contract's presence. To reduce the number of communication transactions necessary to do this, the Timeout of the Contract in the CR is set to be shorter than the timeout in CI's or the CG. Thus the CR can notify the CI's and CG of the continued need for the Contract and prevent them from having to make unnecessary inquiries. However, if for some reason the CR fails to make the notification, the other CA's can initiate sequences of communication transactions to either validate the Contract or delete it from their databases.
  • the CR starts the normal Maintenance Timer by sending a CT (Contract Maintenance Travel) toward the granting CA.
  • CT Constract Maintenance Travel
  • the effect of the receipt of this transaction at intermediate CA's is to restart the Contract's local timer, and to forward the Contract Maintenance Travel CT toward the Contract Grantor.
  • the Contract's local timer is restarted and the maintenance sequence is complete.
  • the CG and CI's assist in this process by monitoring their maintenance timers. If a CG or CI's maintenance timer expires, the CA “Tickles” the CR through the CI's (if present), thus attempting to initiate a timer maintenance sequence by the CR.
  • CI's and the CG assist in the determination of the continued validity of a Contract.
  • An example of this would be if a CI, in the process of forwarding the Maintenance Request, determined that the source for the circuit had changed. This would most likely occur if a normally-open switch along the alternate circuit path had reopened. That CI would then set the Contract status to “Contract Dissolve Start”, thus indicating that the Contract is no longer valid and should be dissolved. CT's would then be generated to dissolve the Contract.
  • an intermediate CA may be able to determine that the line segment limit has already been met, possibly due to segments that have been added on another branch of the circuit. In this case the intermediate CA can reject the Contract and send it back to the CR.
  • FIGS. 56-59 described therein are illustrative flow diagram that may be employed and representative of typical operations performed by the present invention at each player, e.g. a single team member.
  • implementation of a CA also includes many routine tasks and functions as generally discussed hereinafter. For example, any CA activity resulting in the need to send a CT over communications might require a built-in delay or retransmission time to allow a busy communication channel to become available. At any time a database or routing table is updated it is possible that the available size of the database or routing table could be exceeded. As is typical in such illustrations, in the flow diagrams of FIGS.
  • 56-59 logical flow is generally from top to bottom (unless otherwise indicated) and where no exit is shown from a processing box, this means that the immediate processing of the incoming message by the CA has been completed.
  • a number of the logical branches in the flow diagrams are annotated with designated Contract States. This means that the branch is conditional on a match between that indicated State(s) and the State found in the CT's Contract State field or the State field of the Contract database entry, whichever respective State is being processed. That is, for the flowchart showing the processing of incoming CT's, the State is the state of the incoming CT, rather than the state of a Contract in the Contract database.
  • the CA enters its processing loop in processing box 1400 to look for more processing to be performed. Specifically, the CA periodically begins a processing cycle by first processing any incoming CT's received via communications (Yes flow path to FIG. 57 ), and then requests for new Contracts from Player tasks in processing block 1402 against a local copy of the Contract database (Yes flow path to FIG. 58 ), and finally in processing block 1404 , Contract database entries via flow path to FIG. 59 (based on the contents of the State and Timer data elements).
  • the results of the three types of processing include updating the local Contract database, reporting to Player and Coach tasks, and passing CT's along to other CA's when necessary to secure, maintain, release or reject the Contract, as will be explained in more detail hereinafter.
  • FIG. 58 shows the processing applied to incoming Contract processing requests for a new Contract originating from the local Player task. If the request is to create a new Contract, the Contract data structure is zeroed, initialized with the illustrated data elements and then inserted into the database. Specifically, in processing block 1406 , the Field number of the Player requesting the additional capacity via Contract is entered in the database. In processing block 1408 , the Temp Field data element is filled in with the source Field where the capacity is being sought. This will be one of the adjacent Fields if one exists. A non-zero (or valid) value in this entry provides additional information to facilitate the ability of the CA to determine where to send the CT.
  • the Contract Allocation Mechanism is not selecting from one of several alternate sources, but rather is attempting to allocate a limited resource (distribution capacity) from an energized source specified by the Player when the Contract request was issued.
  • each CA will modify the Temp Field to direct the request toward the present energized source of the circuit.
  • a zero or invalid entry indicates that the CT has reached the nearest Player and nearest Field to the circuit's source.
  • the Required Quantity and Capacity data elements include the Segment count if capacity restrictions based on segment count (Required Quantity) is being requested, and/or capacity restrictions based on load amperage (Capacity).
  • the Timestamp function in processing block 1412 adds a degree of uniqueness to the Contract because it is set only once, here at the CR and never modified. If for any reason, a duplicate copy of the Contract appears in the database, the timestamp can be used to verify the problem.
  • the CR will (at a later point in processing) see this Contract in the database and send a Contract Request towards the CG.
  • Each CA is monitoring its database's Contract Timers, counting them down, and at this present step in the processing, the CA is looking for an expired timer. Modifying the State to Contract Maintenance Start will subsequently cause the CA to start a maintenance sequence.
  • the “Contract Request Pending” state flow path to processing block 1420 indicates that a request to initiate a Contract is outstanding. No further action is taken unless the Contract's local timer expires, in which case the request is dropped. Since this state only appears in the CR, the player is informed that the request has timed out without being completed.
  • the “Contract Request Unsent” state flow path to processing block 1422 only occurs at the CR and initiates a sequence as shown to travel to a potential CG if not there now, flow path proceeding via “No” determination path to the process block 1424 ( FIG. 59 a ). If there is no travel required, flow proceeds via the “Yes” determination path to the processing block 1426 since this is a potential CG and either the request is granted or denied based on the availability of resources.
  • a “Contract Request Travel” database entry indicates that a request is enroute from a CR toward a potential CG, processing block 1428 .
  • local capacity must exist to accommodate the additional load (processing block 1428 , FIG. 59 b ). If it does not, the determination in the processing block 1428 is No and the flow proceeds to the processing block 1430 where the request is rejected by altering its state as shown and returned to the CR.
  • flow proceeds via the Yes determination of the processing block 1428 to the processing block 1432 where it is accepted and therefore designated to be the CG, flow proceeding via the Yes determination of the processing block 1432 to the processing block 1434 . Otherwise, flow proceeds via the No determination path of the processing block 1432 to the processing block 1436 , where the determination is made “Is the adjacent source-side Field's source defined.” If Yes, flow will proceed to processing block 1438 to travel toward the potential CG. If No, flow proceeds to the processing block 1440 to decline the request because it has nowhere else to go, again being returned to the CR.
  • the “Contract Request Accepted” State is encountered as a notification of a granted Contract being returned to the CR. This flow for this state proceeds to processing block 1442 . At each step along the path to the CR, this means that the State should now be “Active”, and that it is now time to account for the granted resource by informing the Coach. If we're at the CR, flow proceeds to a processing block 1444 and we do not need to send the message any further but we do need to inform the Player. If we are at the CG or a CI, the flow proceeds to a processing block 1446 where the path to the CR continues with appropriate updating and incrementing.
  • the “Contract Dissolve Start” state proceeds to a processing block 1454 and is initiated when a previously existing Contract is no longer needed. This can be determined and is therefore initiated by a Player at any point along the Contract route of an existing Active Contract. In particular, if it is determined that a line segment is no longer being fed from an alternate source, the Contract is unnecessary. This causes a unique determination in the processing block 1454 to convey the need to dissolve the contract in one of two different directions or both directions via the processing blocks 1456 , 1458 or 1460 dependent upon whether the determination in the processing block 1454 is CR, CG, or CI respectively. Once the messages have been sent, the local copy of the Contract is deleted and the resources de-allocated via the processing block 1462 .
  • the “Contract Dissolve Continue” state encountered via receipt of a CT requesting that a Contract be dissolved, proceeds to a processing block 1464 If the relative position along the route as determined in the processing block 1464 is at the CR or CG, terminal points of the route, flow proceeds to a processing block 1466 to terminate the communication sequence, deleting the local Contract copy and requesting the Coach to reduce its contracted reservation of capacity. If the relative position is at a CI, flow proceeds to a processing block 1468 causing it to forward the CT along the present route (up or down) in addition to doing the other steps performed at the CG and CR.
  • the “Contract Maintenance Start” and “Contract Maintenance Tickle Start” States convey the need for the CR to initiate a Maintenance sequence via the flow path to a processing block 1470 . If the CR and CG are determined to be the same in the processing block 1470 , flow proceeds to a processing block 1472 where the Timer is reset and the Contract State is set to Contract Active. If not, flow proceeds to a processing block 1474 . If these States are encountered at the CR, the Contract State is set to Contract Active, the Timer is reset and a Contract Maintenance Travel CT is sent toward the CG. If these states encountered at the CG or a CI, the Contract State is set to Contract Active, the Timer is reset and a Contract Maintenance Tickle CT is sent toward the CR to start a Maintenance sequence.
  • a “Contract Maintenance Travel” state is entered when a CT was received with that State, and flow proceeds to a processing block 1476 where the Contract's maintenance Timer is reset, its State is reset to Contract Active. If not at the CG, the CT is retransmitted toward the CG. If, as this CT is received at a CI or the CG, the Contract is not in the database (shown in FIG. 57 , block 1407 ), a “Contract Maintenance Travel Not Found” state will be substituted with flow proceeding to a processing block 1478 . This causes a “Contract Maintenance Travel Return Not Found” CT to be sent back toward the CR, and the local copy of the Contract to be deleted.
  • a “Contract Maintenance Travel Return Not Found” state will be encountered in the database with flow proceeding to a processing block 1480 as the “lost Contract” indication is being sent toward the CR. If the database entry is encountered at a CA other than the CR, the Contract is set Active and its timer is reset. If the entry is encountered at the CR, the State is changed to “Contract Maintenance Reactivate Continue” discussed further in connection with FIG. 59 f.
  • the CA determines that the Contract is lost in either the CR or a CI along the path to the CR, the CA will have inserted a Contract into the database with a State of “Contract Maintenance Tickle Not Found”, flow proceeding to a processing block 1482 . This is then deleted and a CT with State “Contract Maintenance Tickle Return Not Found” is sent toward the CG. Both of these database entries cause the local copy of the Contract to be deleted, and at all CAs other than the one where the Contract was discovered missing, the Coach is instructed to release the contracted resource.
  • initial processing of the “Contract Maintenance Reactivate” and “Contract Maintenance Reactivate Continue” database entries proceeds to a processing block 1484 . If we're not at the CG, flow proceeds to a processing block 1486 where a CT with State Contract Maintenance Reactivate must be sent toward the CG. If we are at the CG or after the processing block 1486 , flow proceeds to a processing block 1488 where the Contract becomes reactivated by setting its state to Contract Active and resetting its timer. If the reactivation is being performed at any CA other than the CR, the Coach must be informed to allocate (reallocate) the Contracted resource.
  • FIGS. 29 through 39 illustrate one example of how the logic operated in to reconfigure a complex distribution system, e.g. based on a simple “contract” feature to limit each circuit segment to one segment of additional load from an adjacent segment.
  • the CA methodology is not so restricted or limited and instead seeks out and finds the ultimate source of supply across multiple segments, by being able to allocate and deallocate more than one segment of additional load from that supply, and by being able to account for the allocation along the entire route from load to source.
  • This example is useful to illustrate the CA methodology in the decision making process associated with FIG. 29 , i.e.
  • the CA methodology prevents any potential circuit overload that may be caused by the possibility that other switches in the distribution system might concurrently close to restore service to their own areas of the circuit.
  • the CA methodology also overcomes the necessity of the customer to know in advance that each alternate source can be relied on without regard to the real-time configuration of the distribution system.
  • the CA methodology is operative in the flow of the Player at FIG. 22 b (at the Yes output of the processing block “Is Switch Open?” etc.) corresponding to the Switch 20 being open (It's a Source/Tie or Load/Tie switch or other switch which is energized and could serve as an alternate source to the circuit), and of course, is presently configured to be part of the system.
  • the Coach in Field L has selected Switch 20 as the best source for the Field and so directs the Player to attempt to restore power to the Field.
  • the Player in Field L at Switch 20 would now like to close the switch.
  • the Player requests the CA to determine if the anticipated capacity can be allocated, and to either return that the capacity exists and has been secured, or to return that the capacity cannot be secured for some reason. If the capacity is contracted, the Player will close the switch. If it is not, the Player will inform the Coach which may then attempt to locate and contract for the capacity with another alternate source.
  • processing block 1402 the CA at the requesting Player in Switch 20 , which is therefore a CR, determines that a new Contract is needed.
  • the logic now moves to FIG. 58 , processing block 1405 and in processing blocks 1406 - 1414 (excluding block 1407 ) fills in some details forming what will be the equivalent of a new Contract “application”.
  • the contract By setting the Contract State to “unsent” (processing block 1414 ), the contract, which will be placed in the Contract database, will later be recognized as an “application” which needs to be processed (forwarded towards a potential CG).
  • the destination address of the CA in the adjacent Field along the route to the CG is obtainable from the configuration data base ( FIG. 13 , Present Source Team Member).
  • the configuration data base FIG. 13 , Present Source Team Member.
  • Switch 10 in Field G could be simultaneously attempting to pick up load due to an outage affecting Field F. It is a feature of the CA methodology to facilitate this determination in a complex, dynamically varying distribution system.
  • the unsent Contract will now be processed by the CR.
  • the Contract will be recognized as unsent, and the CR will determine if the request can be fully satisfied locally or needs to be communicated to a CA at another location.
  • a feature of the CA methodology is that it provides a generic capability to determine if the necessary capacity exists in a complex distribution network. By handling local requests as well as those requiring communication and coordination with other devices, the CA methodology serves to simplify the overall resource allocation process.
  • the CR may allocate the resource and grant the Contract.
  • the Contract “application” must be forwarded to another CA in an adjacent field, the CR changes the Contract State field to “Contract Request Pending”, and also copies the Contract “application” to an “outbox”, changing its State to “Contract Request Travel”. By leaving a copy of the Contract at the CR, with an activity Timer running, the CR will be able to monitor the as yet unfilled Contract and handle lost Contract “applications”.
  • a requirement of the implementation is to be able to handle a wide variety of typical failure modes due to lost communication messages or processing bottlenecks in such a way as to avoid overloading the circuit, misallocating resources or losing track of resources such that the system is unable to reallocate or redirect the resources at a future time.
  • the “Contract Request Travel” message will arrive at the next CA along the path leading from the selected energized source toward the head of the circuit, in this case it is FIG. 29 , Switch 16 in Field K.
  • the logic flow in FIG. 57 at the processing block 1409 will add the copy of the Contract, presently in “Contract Request Travel” State, to the database, since the Contract is new.
  • the CA inspects the database it will find the Travel message and process it at processing block 1428 of FIG. 59 b . Note that the logic at this point requires that there be adequate capacity at this point, and every subsequent CA along the route to the alternate source. If not, the Contract is denied.
  • the request will continue to be routed as a Contract Request Travel message through the system until the message can travel no further and has thus reached the ultimate source switch.
  • that switch will be Switch 14 in Field I.
  • the logic at processing block 1434 of FIG. 59 b will be executed to accept the Contract.
  • This CA is now designated the CG for this Contract.
  • the Contract's routing table has been built such that the return path to the CR is known and incorporated in the Contract.
  • the Contract State is set to Contract Active and its maintenance timer is initialized.
  • the Coach is informed that the Contracted amount of load is now committed to the Contract and is therefore subtracted from the Field's available capacity.
  • the Player is notified of Contract acceptance and the Player will close the switch to restore the circuit segment. If for some reason the Contract could not be issued, the Contract is declined, the Player and Coach are notified and can either attempt to pick up the load from a different source, retry the request indefinitely or give up trying to restore service.
  • a task is included for the requesting CA to watch for any reason to dissolve the Contract directly.
  • a manual switching operation that moves this circuit segment to another source would be grounds to dissolve the Contract.
  • This may be a manual operation on the Field that was the origin of the Contract, or a manual operation at another Field seen locally only by the clearing of the alternate source flag.
  • the Contract would then be dissolved in accordance with the foregoing discussion.
  • capacity is temporarily allocated as the CT traverses intermediate line segments that may be limiting segments.
  • a timer is assigned to the temporary allocation such that if the Contract is not granted, the temporary allocation is assured of eventually being utilized or deleted. This would account for the remote possibility where two Contracts have been sent to a common CG upstream from a CI with the two Contracts requiring capacity at an intermediate line segment, which, in combination, exceeds its capacity.

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CA2503583A1 (en) 2004-05-13
BRPI0314881B1 (pt) 2019-01-08
EP2511997A3 (en) 2013-11-20
KR20050070084A (ko) 2005-07-05
AU2003286462B2 (en) 2008-10-23
CN100440665C (zh) 2008-12-03
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CN101325326B (zh) 2017-06-16
US7860615B2 (en) 2010-12-28
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WO2004040731A1 (en) 2004-05-13
MXPA05004409A (es) 2005-07-26

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