AU755717B2 - Electrical distribution system automation - Google Patents

Description

PCT/AU00/00074 Received 14 November 2000 TITLE OF THE INVENTION ELECTRICAL DISTRIBUTION SYSTEM AUTOMATION BACKGROUND OF THE INVENTION Field of the Invention This invention relates to distribution networks for electric power systems. The invention particularly relates to control arrangements and methods for network devices, such as switches, transformers and capacitors, involved in medium voltage network operations which aim to provide secure supply of electricity to consumers.

Discussion of the Background Art Existing control arrangements for medium voltage network devices, notably those downstream from distribution substations operating between about 10kV and 75kV, can be conveniently considered in a number of categories. First there are manual remote type arrangements wherein network devices in the field, including circuit breakers and tapchangers for transformers, are manually controlled by an operator at a regional control centre. Operators generally make decisions in these circumstances based on historical knowledge of the distribution network and real-time status information transmitted from network transducers to the control centre. This is clearly not an efficient or reliable arrangement for a complex distribution network requiring coordinated control.

Secondly, the control arrangement can include control units at selected network devices which operate in response to predetermined network conditions. Sectionalising switches which open after a predetermined number of passages of fault current are example of this arrangement, as are automatically reclosing circuit breakers ("reclosers") which operate in accordance with protection settings having selected timecurrent characteristics. For network devices having control units which are independently maintaind the protection settinngs oin these must hbe carefully individually co-ordinated and can generally only cope with a limited number of network faults or abnormal conditions.

Thirdly, there exists the fully automatic type of control arrangement operating under algorithmic control wherein, in one form, a central or master control unit communicates with remote terminal units for 4operating a respective network device and, in another form, each remote terminal unit operates autonomously. Whilst such arrangements which calculate appropriate network alteration strategies reactively are generally AMEND2D

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PCT/AU00/00074 Received 14 November 2000 2 highly flexible, known algorithms do not appear to extend beyond those for protecting simple radial or open ring electricity networks.

Although the third control arrangements may be programmed to adapt to many abnormal network conditions in simple networks, there are also difficulties testing algorithms implemented by such a control program adequately. Extensive computer-based simulations of electricity networks may be created in order to test the program logic of the control algorithm in a variety of circumstances. However, this introduces a further layer of uncertainty with regard to how reliably the simulation recreates actual network conditions. Even after an extensive series of simulations, it is always a serious step when fully automatic remote control programs are commissioned. Accordingly, automatic control arrangements for electric power distribution are costly to develop and test, and ultimately lack user confidence.

BRIEF SUMMARY OF THE INVENTION Object of the Invention It is an object of the present invention to provide an apparatus and method for controlling network devices in an electricity distribution network which ameliorates or overcomes at least some of the problems associated with the prior art.

It is another object of the invention to provide an apparatus and method for controlling network devices in an electricity distribution network which conveniently facilitates user configuration and modification of network protection or switching schemes, thereby substantially reducing the requirement for traditional simulation and testing.

It is yet another object of the invention to provide, in at least some embodiments of the invention, an apparatus and method for controlling network devices in an electricity distribution network which obviates the need for a central or master control station.

Further objects will be evident from the following description.

Disclosure of the Invention In one form, the invention resides in a method for controlling at least a portion of an electricity distribution network including conductors and a plurality of network devices cooperating with the conductors to facilitate distribution of electricity, wherein control apparatus are co-located with selected network devices and communications apparatus are 4, AK4END=D SHEET PCT/AU00/00074 Received 14 November 2000 3 associated with each control apparatus to provide a communications link therebetween, said method including the steps of: monitoring of distribution network state by the control apparatus co-located with the selected network devices; and upon detection of an abnormal condition in the distribution network, one of the control apparatus checks whether the network state matches an expected abnormal operating pattemrn and temporarily assumes coordinating control of the network portion; whereby said one control apparatus issues commands to. other control apparatus over the communications link in accordance with a predetermined automation scheme.

Suitably the step of monitoring distribution network state includes monitoring status of the network devices associated with the control apparatus.

If required, monitoring the status of network devices includes monitoring voltage, current and other electrical parameters proximate to said network device.

Preferably the control method involves the further step of the control devices communicating the status of respective network devices to each other over the communications link.

In preference, coordinating control of the network devices is assumed by the control apparatus that detects the abnormal condition proximate to an associated network device.

The control apparatus may include network switching sequences for addressing respective abnormal operating patterns, which sequences are programmed by a user to implement the automation scheme adapted to the distribution network configuration.

In another aspect, the invention resides in a control arrangement for an electricity distribution network including conductors and a pnhurlitv nf network dr\irin rnnnratinn lith the conductors ton facilitate distribution of electricity, which control arrangement includes: control apparatus co-located with selected network devices for controlling the operation of each network device in accordance with a predetermined automation scheme; and communications apparatus associated with each control apparatus for providing a communications link between respective control apparatus; AMENDED SHEET

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PCT/AU00/00074 Received 14 November 2000 4 whereby distribution network state is monitored by said control apparatus for the occurence of expected abnormal operating patterns in order to effect decentralized coordination of network device operations using the communications link.

Suitably the control apparatus are each arranged to detect an abnormal condition in the distribution network proximate to the network device associated with an individual control apparatus.

In preference, the individual control apparatus which detects the abnormal network condition temporarily assumes coordination by issuing commands to other network devices.

Preferably the control arrangement is temporarily coordinated by any one control apparatus in the event of an abnormal condition in the network.

The control apparatus may be further arranged for loading with user programmable switching sequences for addressing respective abnormal operating pattems, which sequences implement the predetermined automation scheme adapted to the distribution network configuration.

In a further aspect, the invention resides in a method for controlling switchgear in at least a portion of an electricity distribution network, which network portion includes a group of switches, sources of supply and interconnections between the sources of supply and the switches, wherein at least two of said switches include control apparatus co-located therewith and the respective control apparatus can communicate, the method including the steps of: monitoring distribution network state by each control apparatus for switches in the group; if an abnormal condition is detected in the distribution network by a control apparatus, the control apparatus checks whether the network state matches one of a plurality of abnormal operating pattemrns expected in the group of switches; (ii) if the network state matches an expected abnormal operating pattern, then said control apparatus communicates with respective control apparatus for other switches in the group to AMENDED SHEET tP~4i~a$ PCT/AU00/00074 Received 14 November 2000 execute a predetermined switching sequence prepared for addressing the abnormal operating condition corresponding to said matching pattem.

Preferably, the abnormal condition in step is loss of supply at a predefined place in the network portion and the control apparatus for the switch assumes control after a predetermined time delay.

The control apparatus preferably assumes control of the group of switches when the network state matches an abnormal operating pattern.

AMEDED -SHErL--7 Ir-iI4u WO 00/48288 PCT/AUOO/00074 If required the control apparatus assumes control after a predetermined time delay.

Suitably, the step of checking network state includes one or more of the steps of: checking that all control apparatus are programmed with an equivalent automation scheme; and/or checking that no other control apparatus is already in control of the group of switches.

The expected abnormal operating patterns may include one or more of the following patterns in the group of switches: an expected fault pattern; an expected tripped pattern; and/or an expected source supply pattern.

If required, the method can include the following steps subsequent to step if the control apparatus has assumed control and a normal condition is detected in the distribution network, then the control apparatus of said switch checks whether the network state matches one of a plurality of patterns expected in the group of switches; (ii) if the network state does match an expected pattern, then said control apparatus communicates with respective control apparatus for other switches in the group to execute a predetermined switching sequence prepared for recovering from the abnormal operating condition and releases control of the group of switches.

in preference the normal condition in step is the restoration of supply to a switch for a pre-determined time delay.

In a further aspect the invention resides in a method for controlling switchgear in at least a portion of an electricity distribution network, which network portion includes a group of switches, sources of supply and interconnections between the sources of supply and the switches, wherein Substitute Sheet (Rule 26) RO/AU WO 00/48288 PCT/AUOO/00074 6 the switches are associated with a control apparatus, the method including the steps of: monitoring distribution network state by the control apparatus for switches in the group; if an abnormal condition is detected in the distribution network, the control apparatus checks whether the network state matches one of a plurality of abnormal operating patterns expected in the group of switches; (ii) if the network state matches an expected abnormal operating pattern, then said control apparatus assumes control of the group of switches and communicates with the group to execute a predetermined switching sequence prepared for addressing the abnormal operating condition corresponding to said matching pattern.

Preferably, the abnormal condition in step is loss of supply at a predefined place in the network portion.

The control apparatus for the switches preferably assumes control after a predetermined time delay.

The expected abnormal operating patterns may include one or more of the following patterns in the group of switches: an expected fault pattern; an expected tripped pattern; and/or an expected source supply pattern.

If required, the method can further include the following steps subsequent to step if the control apparatus has assumed control and a normal condition is detected in the distribution network proximate to a switch, then the control apparatus for the switches checks whether the network state matches one of a plurality of patterns expected in the group of switches; if the network state does match an expected pattern, then said control apparatus communicates with the switches in the group to execute a predetermined switching sequence prepared for recovering from the abnormal operating condition.

Substitute Sheet (Rule 26) RO/AU PCT/AU00/00074 Received 14 November 2000 7 In preference, the normal condition in step is the restoration of supply to the switch for a pre-determined time delay.

If required, a control apparatus is co-located each switch in the group and a predetermined control apparatus always assumes control by issuing commands over a communications link to the control apparatus co-located with other switches.

Suitably the predetermined control apparatus includes a gateway to an external communications network for providing status information to external supervisory control and data acquisition systems.

Alternatively, a slave control apparatus is co-located with each switch in the group and a master control apparatus, located remotely from said group of switches, always assumes control by issuing commands over a communications link to the slave control apparatus.

In another aspect, the invention resides in a control apparatus for controlling a network device which cooperates with conductors in an electricity distribution network, said control apparatus including: a detection module for monitoring distribution network conditions at the network device; a processor interfaced to the detection module for receiving information about the distribution network conditions; memory means accessible by the processor for storing a common control program, operating parameters for the network device and a plurality of expected abnormal operating patterns which occur during abnormal network conditions; an actuator for operating the network device, which actuator is controlled by the processor; and Ca1 111 IUI II% UI IZ PP LU II ItelI IfacedIU LU LI I po1 UL oU I-or providing a communications link with other control apparatus associated with other network devices in a portion of the electricity distribution network; wherein the control program effects operation of the network device and facilitates communications with the other control apparatus in accordance with a predetermined automation scheme.

AMENDED SHEET 1PA"'AU PCT/AU00/00074 Received 14 November 2000 8 Suitably the memory includes a database for storing the plurality of expected abnormal operating patterns.

Preferably, the network devices include switches.

Most preferably, the memory includes a database for storing a plurality of switching sequences for operating the network devices to address respective abnormal network conditions.

In a still further aspect, the invention resides in a method for configuration of control apparatus co-located with a network device, which network device is one of a group of network devices in an electricity distribution network, said method including the steps of: creating a representation of at least a portion of the distribution network including the group of network devices, which representation defines sources of supply and interconnections between the sources and network devices in said distribution network; defining a normal operating pattem of the distribution network by recording a corresponding normal status of each network device in said group of devices; defining a plurality of abnormal operating patterns, relative to said one network device, which impact adversely on distribution network integrity; preparing a reconfiguration sequence for said group of network devices for each abnormal operating event for limiting adverse effects thereof, which sequences are automatically initiated in response to an abnormal condition in the network portion; and loading said reconfiguration sequences into the control apparatus for said one network device.

In one form, the control apparatus is co-located with respective network devices.

In an alternative form the control apparatus is located remotely from said group of network devices.

The group of network devices suitably includes switches.

Suitably at least one of the switches in the group includes source voltage sensing.

If required, at least one of the switches in the group includes through-fault current detection facilities.

AMENDED SHEET WO 00/48288 PCT/AUOO/00074 9 Preferably the representation of the distribution network is a diagram which graphically illustrates the group of switches, the sources of supply and the interconnections therebetween.

Suitably the status of each switch includes whether the switch is normally open or normally closed, along with the maximum load current able to be carried by the network proximate to the switch.

Preferably the abnormal conditions are detectable proximate said one network device.

In preference the plurality of abnormal operating patterns are defined by selecting the position of an abnormal event on the representation and simulating the response of the group of network devices to the event in order to generate an abnormal operating pattern.

The switching sequences are suitably defined by selecting the network devices on the representation in the desired sequence for a respective abnormal operating pattern.

In preference, a set of suggested steps for addressing a particular abnormal operating pattern is automatically generated to assist definition of a switching sequence.

The representation created by the user may be analysed in order to automatically produce further abnormal operating patterns to a user.

In a yet further aspect of the invention, there is provided an automated tool for configuration of control apparatus associated with a network device, which device is one of a group of devices in an electricity distribution network; said tool including: a graphical user interface for creating a representation of at least a portion of the distribution network including the group of network devices and identifying at least one normal operating pattern; a database coupled to the user interface for storing the representation of the network portion, characteristics of each network device in the group and said at least one normal operating pattern; a protection and load flow engine coupled to the database for Substitute Sheet (Rule 26) RO/AU WO 00/48288 PCT/AU00/00074 simulating the operation of the group of network devices based on the operational parameters of each device and their interconnections to user specified abnormal events; and (ii) solves the load flow for the representation of the network whereby an abnormal operating pattern is defined for each abnormal event; and wherein the automated tool facilitates definition of a switching sequence for the group of network devices for limiting the adverse effects of each abnormal operating pattern.

BRIEF DESCRIPTION OF THE DRAWINGS To assist in understanding the invention preferred embodiments will now be described with reference to the following figures in which: FIG. 1 is a line diagram of a portion of an electricity distribution network; FIG. 2 is an enlarged diagram of the network portion of FIG. 1; FIG. 3 is a block diagram of a network device including control apparatus of a first embodiment; FIG. 4 shows the user interface for an automation scheme configuration tool; FIG. 5 shows a network diagram of the network portion of FIGS 1 and 2; FIG. 6 is a block diagram of a software tool for configuring switching sequences for the control apparatus of the first embodiment; and FIG. 7 is a flow chart illustrating a method of configuring switching ser'une. fnr the automation scheme used in relation to the first embodiment.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Referring to FIG 1, there is shown a line diagram of portion of a distribution network including a substation bus-bar 11 fed from a source 12 of electrical power. Two supply lines 13 and 14 are connected to the bus-bar 11 by respective substation circuit breakers 15 and 16.

There are several connection points 17 on each supply line to which loads Substitute Sheet (Rule 26) RO/AU WO 00/48288 PCT/AUOO/00074 11 are connected. Network devices, which in the present example are reclosing switches are disposed between the connection points. Two reclosing switches 18 and 19 are on supply line 13, whilst two reclosing switches are on supply line 14. A load break switch 22 bridges supply lines 13 and 14. In the present embodiment, control of the network devices in the portion of the network bounded by the broken line 23 is of particular interest. The manner in which the loads 24 happen to be connected outside of network portion 23 is not of particular interest.

An arrangement and method of controlling a plurality of network devices will now be described with reference to the group of switches including the reclosers 18, 19, 20 and 21, along with the load break switch 22. The embodiment allows coordinated operation of the network devices without requiring a central or master control station, although in some instances there may be passive data acquisition by a central station for remote monitoring purposes only. An enlarged diagram of the network portion 23 is illustrated in FIG. 2, wherein each of the load carrying spurs is omitted and only the connection points 17 representative of the loads remain. In this diagram like reference numerals refer to like parts.

Each of the reclosers includes a set of contacts 25 and a close/trip actuator 26, along with control apparatus 27 co-located with the recloser. The control apparatus 27 is interfaced to a detection module 28 and a communications apparatus 29, which provides a radio communications link between the respective control apparatus for the reclosers and also the controller/actuator 30 for the load break switch 22.

The communications apparatus may employ the Harris DNP-3.0 protocol or the IEC 870-5-101 protocol as required. The detection module preferably includes a current transformer and a capacitive voltage transformer, which may be either external or internal to the switchgear. It will be appreciated that the communications link may alternatively be implemented using optical fibre, land line or other communications technologies known to persons skilled in communications systems. This arrangement might also include a secure virtual private network utilising the Internet or similar global telecommunications network.

The control apparatus 27 includes a memory module for storing a program for implementing an automation scheme which includes a number of network checking and switching sequences configured by a user, typically a utility engineer, to respond to various abnormal or fault conditions that may adversely effect the network. The control method effected by the program executes the sequences in a regular fashion, with Substitute Sheet (Rule 26) RO/AU WO 00/48288 PCT/AU00/00074 12 the outcomes being determined by the user configured parameters. Each sequence addresses a predetermined abnormal condition in the network portion.

The load break switch 22 does not include a control apparatus 27 as do the reclosers and accordingly is termed a passive device, whereas the network devices with control apparatus are termed active.

The controller/actuator 30 for the load break switch maintains a limited set of status information, including and may be operated in response to commands received over the communications link from any of the control apparatus 27.

In the present embodiment, when loss of supply is detected at one of the reclosers, the control apparatus may temporarily assume control of the other network devices in the network portion in order to reconfigure the network. Commands, specified in the switching sequence, are issued over the communications link to the respective control means for switching or otherwise adjusting network devices to isolate the fault. In a preferred form, further commands may be issued in order to switch the network back to its normal condition upon restoration of supply. The operation of the automation scheme utilising the control arrangement of the embodiment will become apparent with reference to a particular example.

In the example it is assumed that there is a loss of supply detected at recloser 18 caused by a fault 31 which results in the circuit breaker 15 opening or tripping. When this occurs, the control apparatus 27 for recloser 18 first confirms that the network portion is not already in an reconfigured state (in which case another network device may have already control). If not, the control apparatus causes the network portion to enter the reconfigured state after a user set time delay (DS) and temporarily assumes control of the other network devices 19, 20, 21 and 22 in the portion 23 of interest.

It is pertinent to observe that a normal expecte operating pattern for the network portion has been previously configured by the user as follows: all reclosers (18, 19, 20 and 21) normally closed with supply present; and load break switch (22) normally open. Upon assuming control, the control apparatus 27 for recloser 18 interrogates the status of the remaining network devices to discover that the present reconfigured state is: reclosers 18 and 19 closed, but with no supply; reclosers 20 and 21 closed with supply present; and load break switch open. Each of the respective control apparatus monitors the status Substitute Sheet (Rule 26) RO/AU WO 00/48288 PCT/AUOO/00074 13 of its associated network device for this purpose. The present reconfigured state corresponds to an expected reconfigured state for which a network checking and switching sequence has been configured by the user.

The relevant switching sequence is then initiated by the control apparatus for recloser 18, as follows: open recloser 18; and (ii) close load break switch 22. It will be appreciated that this sequence isolates the faulted section adjacent the fault 31 on line 13, whilst supplying the remaining loads, in a preferred form of the invention, the status of each network device may include the load carried in order to facilitate load checking calculations by the control apparatus 27. In a more complex switching sequence, the control apparatus 27 at recloser 18 could also have adjusted the protection settings on reclosers 20 and 21 to prevent undesired tripping due to higher currents drawn through line 14 during abnormal operation with a heavier load.

Subsequent to operation of the switching sequence, the control apparatus 27 for recloser 18 continues to monitor the state of the network portion. Should the detection module 28 sense that supply is restored to recloser 18 for a user set time delay the control apparatus checks the status of the other reclosers to ensure that it is appropriate to revert the network portion to its normal condition In accordance with the user configured switching sequence, the control apparatus 27 for recloser 18 initiates opening of load break switch 22 and (ii) closing of recloser 18. The coordinating control apparatus then releases control of the network devices.

The control arrangement will now be described in more detail to assist understanding of the invention. In the initial design phase, a user identifies a group of network devices in a particular portion of the distribution system. Some of these devices are deemed passive, in that they are to supply status information and respond to operating commands, wrhiist the remainder are deemed active in that they further include control apparatus which may temporarily assume coordinating control of the other network devices in the group. Suitably all devices participating in the automation scheme are associated with a communications apparatus to facilitate interrogation of status information and receipt of commands from a control apparatus at a remote location.

Preferably the active network devices are switches, including reclosers, sectionalisers and load break switches, which include source voltage sensing and through fault detection, such as provided by the Substitute Sheet (Rule 26) RO/AU WO 00/48288 PCT/AUOO/00074 14 voltage transformer 28v and the current transformer 28c portions of the detection module 28 depicted in FIG. 3. Each control apparatus 27 for the active network devices includes a common control program 33 stored in a first memory portion 34 which is executed by a processor 35. However, the parameters 36 for the common control program are different for each network device and may be configured by the user. The parameters, stored in a second memory portion 37, include the checking and switching sequences which may be initiated by the control apparatus 27 co-located with a network device in the present diagram recloser 18.

Execution of the common control program using the parameters implements user configured switching sequences for isolating a faulted section of the network portion. Suitably the switching sequences included in the automation scheme operates on the underlying assumption that the control apparatus closest to the faulted section will temporarily assume coordinating control of all network devices in the group.

The control apparatus 27 for each network device maintains status information about its respective device, which might be conveniently stored in a database 38 in the second memory portion 37, for access by processor 35. A preferred set of status data is set out below, with symbolic abbreviations for respective control program parameters.

Description Requirement Symbol (type) Through Fault Flag Mandatory F (boolean) Tripped (not closed) Recloser or T (boolean) Sectionaliser Source Supply Present Mandatory for active S (boolean) devices Reconfigured State Flag Mandatory A (boolean) Protection Relay Pickup Optional R (boolean) Protection Sequence in Mandatory P (boolean) Progress Flag In Control Flag Mandatory C (boolean) Healthy Flag Mandatory H (boolean) Enabled Flag Mandatory E (boolean) Load Prior to Trip Optional L (integer, Amps) Capability Mandatory CAP (integer bit mask) Substitute Sheet (Rule 26) RO/AU WO 00/48288 PCT/AUOO/00074 Table 1 Device Status Data Each participating network device and co-located control apparatus should be capable of performing the appropriate operations in response to the following commands, as set out in Table 2 below: Command Requirement TRIP (OPEN) Mandatory CLOSE Mandatory ACTIVATE PROTECTION SET Optional CLEAR THROUGH FAULT FLAG Mandatory Table 2 Device Capabilities Furthermore, when a switching sequence is being carried out, the control apparatus which has assumed coordinating control issues commands to all network devices in the group via the communications link (or locally for the co-located network device) to initiate the desired operations. In other embodiments, such as those controlling network devices such as transformers and/or capacitors, commands such as MOVE UP TAP and MOVE DOWN TAP could be added as required.

The control program executes on the basis of parameters which may be configured for each individual network device by the user.

User configured expected fault patterns are checked and a corresponding switching sequence initiated via the communications link. If the fault pattern is unexpected, the program aborts and the control apparatus releases control of the network devices. The relevant user configured parameters for switching sequences in the present embodiment are as follows: Scheme Identifier: SID (8 bytes) Each automation scheme is uniquely identified by this parameter, allocated by the user. The program will not execute unless all devices have the same scheme loaded.

Number of Participating Devices: N (integer, 1..31) Communication Address of Participating Devices: CAPD (16 bytes [by device]) Each participating device must be able to communicate with all other devices, this table provides the addressing information required by the protocol in use.

Substitute Sheet (Rule 26) RO/AU WO 00/48288 PCT/AUO/00074 16 Delay to Start Algorithm: DS (integer, Seconds) Upon loss of supply for DS seconds the device will begin execution of the algorithm to reconfigure the network to the Reconfigured State.

0 Delay to Reversion: DR (integer, Seconds) Upon restoration of supply for DR seconds the controlling device will begin execution of the algorithm to revert the network back to the Normal State.

SExpected Fault Pattern: NEXPF (boolean [by device]) The Though Fault Status, F, of each participating device after the expected fault has occurred and before the network is reconfigured.

Expected Tripped Pattern: NEXPT (boolean [by device]) The Tripped Status, T, of each participating device after the expected fault has occurred and before the network is reconfigured.

Expected Source Supply Pattern: NEXPS (boolean [by device]) The Source Supply Status, S, of each participating device after the expected fault has occurred and before the network is reconfigured.

Reconfigured Expected Tripped Pattern: AEXPT (boolean [by device]) The required Tripped Status, T, of each participating device after the network has been reconfigured and when the controlling device has detected restoration of supply.

Maximum Load Capacity: M (integer, Amps) The maximum load this device is capable of supplying.

Load Checks A number of load checks, expressed as sums or differences of L values and constants and the device the load sum is to be checked against, e.g.: 2M 3L 4L 200 Sequence Required to Reconfigure (Normal to Abnormal) The sequence of Commands required for reconfiguring to the abnormal network state.

Sequence Required to Revert (Abnormal to Normal) The sequence of Commands required for reverting back to the normal network state.

Common Control Program A function called AutoSwitch() is one embodiment of a main routine of the common control program. The main routine is split into two Substitute Sheet (Rule 26) RO/AU WO 00/48288 PCT/AU00/00074 17 major states: the Normal State: A and the Reconfigured State: A. The Normal State characterises the "normal" state of the distribution network.

When a continuous loss of supply, is detected at a participating device for the Delay to Start period, DS, the checking process begins. The control program executing in the co-located control apparatus calls CheckReconfigurationConditions(, and if that succeeds continues to ExecuteReconfigureSteps( and then finally the Abnormal flag is set TRUE The Reconfigured State flag characterises the reconfigured state of the network after the control program has successfully dealt with an abnormal network condition. When the controlling device detects restoration of supply, S, for the Delay to Revert period, DR, the function CheckReversionConditions( is called, and if successful the function ExecuteReversionSteps( is called and then finally the A and C flags are set back to FALSE. The psuedo-code for the functions described is set out below, beginning with the main routine: Function AutoSwitch( forever if (not in the reconfigured state) if for DS seconds) (if no supply for DS seconds) C TRUE; take control if (CheckReconfigurationConditions( TRUE) if (ExecuteStepsToReconfigure( TRUE) A TRUE; enter the reconfigured state Log(LT_AutoSw, EC_ABNORMAL); else C FALSE; abort, release control else C FALSE; conditions not met, release control else Substitute Sheet (Rule 26) RO/AU WO 00/48288 PCT/AU00/00074 18 device is in the reconfigured state if (S for DR seconds) //if (supply detected for DR seconds) if (CheckReversionConditions() TRUE) ExecuteReversionSteps(); A FALSE; leave the reconfigured state C FALSE; network back to normal, release control Log(LT_AutoSw, EC_NORMAL); Summarising the steps taken by the routine of the embodiment when in the Normal State: The Supply State S is monitored; When supply fails for DS seconds; The Control Flag is asserted; The reconfiguration conditions are checked using CheckReconfigurationConditions); If conditions are met, the Steps to Reconfigure are executed by ExecuteReconfigurationSteps); Finally the Reconfigured State Flag is asserted; and The network is now in the Reconfigured State.

Similarly, summarising the steps taken in the Reconfigured State: The Supply State is monitored When supply is restored for DR seconds The reversion conditions are checked using CheckReversionConditions( If conditions are met, the Steps to Revert are executed by ExecuteReversionStepso Finally the Abnormal and Control flags are cleared The network is now restored to the Normal State.

In a particularly preferred arrangement tracing or event logging is used by the control apparatus for participating devices to provide information to the user about the operation of the control program. It is intended that all devices should support a single, consistent set of logged items to the extent that each device is capable. Events logged will include Substitute Sheet (Rule 26) RO/AU WO 00/48288 PCT/AUOO/00074 19 successful reconfiguration and reversion operations, unsuccessful operations including all reasons for failure, and significant status events such as changes to the E or H status flags.

A logged event will comprise either three or four pieces of data, a date and time stamp, a logging tag (LT) which indicates the function the event was detected by, an Event Code for the specific event being logged, and optionally some associated data. The relationship between the detecting function and logging tag is as follows: Function Name Logging Tag AutoSwitch LTAutoSw CheckReconfigureConditions LT_ChkRecon ExecuteReconfigureSteps LT_ExecRecon CheckReversionConditions LT_ChkRevers ExecuteReversion Steps LT_ExecRevers The codes for the events that may be logged by the control apparatus are as follows: Event Event Code Logging Tag Associated Description Data (optional) AutoSwitch ECENABLE LTAutoSw enabled AutoSwitch EC_DISABLE LT_AutoSw disabled The network has successfully reverted back to normal after a fault cleared C flag of another device is TRUE A flag of another device is TRUE

ECNORMAL

LT AutoSw ECCFLAG LT ChkRecon Device IU

EC

EC

E flag of any IEC _AFLAG LT_ChkRecon Device ID _EFLAG LTChkRecon Device ID Substitute Sheet (Rule 26) RO/AU WO 00/48288 PCT/AU00/00074 Event Event Code Logging Tag Associated Description Data (optional) device is FALSE LT_ChkRevers H flag of any EC_HFLAG LT ChkRecon Device ID device is FALSE LTChkRevers Check NEXPF EC NEXPF LT ChkRecon Device ID fails Check NEXPT EC NEXPT LT ChkRecon Device ID fails Check NEXPS EC NEXPS LT ChkRecon Device ID fails Load Check fails EC CHKLOAD LTChkRecon Load Check No.

Check AEXPT EC AEXPT LTChkRevers Device ID fails Command fails EC CTRLACT LTExecRecon Step No.

LT ExecRevers The psuedo-code for the function called by AutoSwitch which checks that conditions in the network portion are suitable for reconfiguration (eg. upon detection of a fault in the network, the fault pattern is expected and devices have tripped as expected) is as follows: Function CheckReconfigurationConditions() result TRUE; if (SID of any other device is different from SID of Controlling Device) Log(LT_ChkRecon, EC_CFLAG, device id); for each failed device result FALSE; I UOU IlL I if (C flag of any other device is TRUE) Log(LT_ChkRecon, EC_CFLAG, device id); for each failed device result FALSE; if (E flag of any device is FALSE) Log(LT_ChkRecon, EC_EFLAG, Device ID); for each failed device result FALSE; Substitute Sheet (Rule 26) RO/AU WO 00/48288 PCT/AU00/00074 21 if (H flag of any device is FALSE) Log(LT_ChkRecon, EC_HFLAG, Device ID); for each failed device result FALSE; if (P flag of any device is FALSE) Log(LT_ChkRecon, EC_PFLAG, Device ID); //for each failed device result FALSE; if (check NEXPF fails) Log (LT_ChkRecon, EC_NEXPF, Device ID); for each failed device result FALSE; if (check NEXPT fails) Log(LT_ChkRecon, EC_NEXPT, Device ID); for each failed device result FALSE; if (check NEXPS fails) Log(LTChkRecon, EC_NEXPS, Device ID); for each failed device result FALSE; if (check Load Checks fails) //log an event for each failed load check Log(LT_ChkRecon, EC_CHKLOAD, Load Check No.); result FALSE; return result; In summary, CheckReconfigurationConditions provides the following checks which, if failed, set the In Control Flag C back to false and control is released: SAll devices must ibe executing the same Automation Scheme. If any other participating device is not executing the same Scheme control of the network devices is not assumed.

Only one participating device can be in control at any time. If any other participating device is In Control, control of the network devices is not assumed.

If any participating device is not Enabled control of the network devices is not assumed.

If any participating device is not Healthy control of the network devices is not assumed.

Substitute Sheet (Rule 26) RO/AU WO 00/48288 PCT/AU00/00074 22 If any participating device has a Protection Sequence in Progress control of the network devices is not assumed.

If the Expected Fault Pattern is not correct, control of the network devices is not assumed.

If the Expected Tripped Pattern is not correct, control of the network devices is not assumed.

If the Expected Source Supply Pattern is not correct, control of the network devices is not assumed.

Any Load Checks specified are carried out, if any one fails control of the network devices is not assumed.

Function ExecuteReconfigureSteps() result TRUE; for (each step) ExecuteStep(); if (VerifyStepO FALSE) Log(LT_ExecRecon, EC_CTRLACT, Step No.); result FALSE; indicate failure break; unable to execute a step, abort return result; Each step (Command) is executed and verified in the sequence specified.

If a step fails to verify, the algorithm aborts at that point returning a failure result to the main routine.

Similarly, the psuedo-code for the function called by AutoSwitch which checks that conditions in the network portion are suitable for reversion (eg. when conditions indicate that a network fault has cleared) is as follows: Function CheckReversionConditions() result TRUE; for (each device) if (E flag of device is FALSE) Substitute Sheet (Rule 26) RO/AU WO 00/48288 PCT/AUOO/00074 23 Log(LT_ChkRevers, EC_EFLAG, Device ID); result FALSE; for (each device) if (H flag of device is FALSE) Log (LT_ChkRevers, EC_HFLAG, Device ID); result FALSE; if (check AEXPT fails) Log(LTChkRevers, EC_AEXPT, Device ID); result FALSE; return result; Again, in summary: If any participating device is not Enabled, control of the network devices is not assumed.

If any participating device is not Healthy, control of the network devices is not assumed.

If the Abnormal Expected Tripped Pattern is not correct, control of the network devices is not assumed.

Substitute Sheet (Rule 26) RO/AU WO 00/48288 PCT/AUOO/00074 24 Function ExecuteReversionStepso result TRUE; for (each step) ExecuteStep(); if (VerifyStep() FALSE) Log(LT_ExecRevers, EC_CTRLACT, Step No.); result FALSE; indicate failure break; unable to execute a step, abort return result; Each step (Command) is executed and verified in the sequence specified.

If a step fails verification, the algorithm aborts at that point, returning a failure result to the main routine.

It will be appreciated that secure functioning of the communications link between the participating network devices is important. Each of the control apparatus may request device status data, as summarised in Table 1 above, or transmit status data in response and also transmit device commands, see Table 2, or receive commands when in service. From time to time, each device may also receive new or updated automation scheme, identified by scheme identifier SID, over the communications link for loading into memory.

In the present embodiment, device status data is shared between devices using a packetised communications protocol, wherein two packet types: Device Status Request and the Device Status Response. The Device Status Request causes the receiving device to transmit a Device Status Response to the requesting device. Each device must also be able to process unsolicited Device Status Response packets.

Whenever an unsolicited Device Status Response is received, the receiving device will update a Device Status Table entry for the transmitting device. The Device Status Table is part of the database 38 held in the control apparatus 27 of the receiving device. When a network device assumes or releases control, it will transmit an unsolicited Device Status Response to each other device. When a device commences Substitute Sheet (Rule 26) RO/AU WO 00/48288 PCT/AU00/00074 operation (boots) it will transmit an unsolicited Device Status Response to each other device. When a device that is not currently In Control has a change in any of the Device Status Response data items, except the Load Prior to Trip L, an unsolicited Device Status Response will be sent to the current controlling device.

Although the control method and apparatus of the invention have been described in relation to a first embodiment wherein the control apparatus and automation scheme are suited to an arrangement of distributed control apparatus that are co-located with network switching devices, other arrangements are feasible. For example, a selected control apparatus could always assume control of switches in a particular portion of the distribution network. This would overcome the issue of determining which of the distributed controllers should assume control upon an abnormal condition arising in the network. The selected control apparatus could also include a gateway to an external communications network for providing status information to external supervisory control and data acquisition (SCADA) systems.

In a further alternative arrangement, a slave control apparatus could be co-located with each switch in the group and a master control apparatus, located at a station remote from the group of switches in the network portion. The master control station always assumes control by issuing commands directly over a communications link to the slave control apparatus. The slave control apparatus could be minimally functional, with all control processes executing on a computer system in a secure environment at the master station. This arrangement would need to take account of any communications delays introduced by a more complex communications link.

Confiquration Tool The manner in which the steps of a automation scheme may be configured and loaded by a user will be described in relation to a second aspect of the present invention. The second aspect is a automation scheme configuration tool, that is preferably a software application which Substitute Sheet (Rule 26) RO/AU WO 00/48288 PCT/AUOO/00074 26 can run on a personal computer to create, edit and validate switching sequences to be implemented in network devices arranged in a group for coordinated control. As mentioned above, a preferred network device is a switching device with co-located control apparatus and communications apparatus. The configuration tool suitably provides an interactive graphical user interface through which the user represents the network portion of interest by a network diagram, such as illustrated in FIG. 4. The network diagram defines, in a simplified form, the network connections between the group of switches and their normal and if appropriate alternate sources of supply.

The configuration tool preferably provides a graphical user interface 40, suitably in a windowed environment such as facilitated by application programs using the Microsoft WindowsTM operating system, for creating network diagrams. Distribution network components are placed on the diagram by users "dragging and dropping" them from a network component toolbar bar 41 provided by the user interface. Connections (lines, cables, etc.) are drawn between components by dragging a line between them after making a selection of the appropriate switch or connection type from the tool-bar. Directional arrow-buttons 42 on the toolbar enable rapid extensions to be made to a network diagram 43 consisting of switches or connections and other network components from the presently selected part of the network in the direction indicated by the arrow button.

At any time the network can be re-arranged by "dragging" components to new positions using a pointing device without breaking existing connections to other network components. With reference to FIG.

4, the available network components typically include reclosers 44, load break switches 45, circuit breakers 46, sources of supply 47, substation bus-bars 48 and connection nodes 49. Sectionalisers and actuator-driven switches are also available to the user. Connections between network components are kept as simple as possible by reducing them to their simplest schematic equivalent. For example, a connection consisting of many kilometres of aerial line, with any number of radial spur lines connected, may be represented as a simple connecting line 49a, or even Substitute Sheet (Rule 26) RO/AU WO 00/48288 PCT/AU00/00074 27 be reduced to a point by representing a cable as a simple connection node.

Once a graphical representation of the portion of the network of interest is created 71 the user can then specify, with reference to the flow chart of the configuration method 70 in FIG. 7, the following: any number of normal operating states of the network 72, including the open and closed states of each one of the group of switches; and (ii) any number of abnormal events, including faults 73 at different locations, in the network for each normal operating state; (iii) a switching sequence 74 for each abnormal state; and (iv) output a controller configuration 75 to disc or other media for loading into the switch controller.

The switching sequences are defined by the user to respond to various fault conditions that may affect the network and are aimed at limiting the extent and severity of any outage caused by the fault and to also define the subsequent sequence of steps to restore the network to its normal status once a set of defined network conditions have been met to initiate the restoration sequence.

The software tool suitably assists the user by validating parts of the proposed sequences and gives feed-back to the user by clearly indicating the parts of the network that are connected to supply at each stage of the switching. In some embodiments the configuration tool can analyse a fault condition in the context of the network topology created by the user and suggest, by a series of directed questions, suitable switching steps that should be considered as a response to the fault condition. The questions are suitably structured to reflect those which a protection engineer would normally ask when configuring equipment of this type, thereby facilitating easy and clear configuration which engenders confidence in the user. More typically the tool also generates a list of load checks for the user to consider and automatically identifies abnormal network conditions overlooked by the user.

In a particularly preferred arrangement, the user can view a demonstration of the currently defined switching sequence by playing it Substitute Sheet (Rule 26) RO/AU WO 00/48288 PCT/AUOO/00074 28 back, step-by-step, through an on-screen animation of the network diagram on a display screen of the personal computer 60, as illustrated in FIG. 6. The configuration tool can be used to create "data objects" that encapsulate information about the network and the user-defined switching sequences. These "data objects" can then be loaded by communicating to the control apparatus for switches in the group. This provides the common control program with the parameters needed for the network devices to be able to respond to predetermined faults which give rise to abnormal patterns in the network.

FIG. 6 is a block diagram for the configuration toolkit software of a preferred embodiment of the second aspect of the invention. The software consists of a database 61 which holds all the information about the network topology, and the devices in the network along with the normal configurations, abnormal events, expected abnormal switching sequences. This data is used in three ways in the toolkit of the embodiment: I) To drive a graphical user interface 62 (GUI) to provide a convenient and intuitive interface for the user. Through the GUI the user can create a representation of a portion of the network and define switching sequences.

II) To drive and be driven by a protection and load flow engine 63 which simulates protection operation of the network devices. The engine also performs network load flow calculations in response to the current network configuration and so allows energisation and power flow direction to be displayed on the GUI 62.

III) To generate the controller configurations by way of an output filter 64. These are a sub-set of the data in the database and hold all the runtime data required by the individual controllers. The configuartions may be stored on a magnetic disc 65 or other suitable media. in an alternative arrangement, the controller configurations may be transmitted directly to the control apparatus via a communications link.

In order to illustrate user configuration of switching sequences, reference is made to FIG. 5 which shows the network diagram corresponding to the portion of the network illustrated in FIGS. 1 and 2. It Substitute Sheet (Rule 26) RO/AU WO 00/48288 PCT/AUOO/00074 29 should be recalled that the two substation circuit breakers 51 are not part of the group of network devices of interest, which includes reclosers having DevicelDs R001, R002, R003 and R004, along with load break switch with DevicelD LB005.

User Configured Parameters The user configured parameters for each of the devices, which can be prepared with the configuration tool, are set out below. In the interests of brevity the DevicelDs are abbreviated 1 to 5, respectively, in the following discussion. The parameters are loaded into the memory of the control apparatus co-located with the respective devices.

DevicelD: R001 (device 1) DS 20 seconds DR 40 seconds NEXPF NEXPT NEXPS no through fault flags only device 5 tripped supply on all devices except AEXPT device 1 tripped M 6000 Amps Load Checks: 1. 3M>= 3L+ 1L 2. 4M>= 4L+ 1L 3. 5M 1L 4. 2M>= 1L-2L Switching Required to Reconfigure: 1. TRIP 1 2. CLOSE Switching Required to Revert: 1. TRIP 2. CLOSE 1 Substitute Sheet (Rule 26) RO/AU WO 00/48288 DevicelD R002 (device 2) DS 40 seconds DR 80 seconds NEXPF NEXPT NEXPS AEXPT M 6000 Amps Load Checks: 1. 3M>=3L +2L 2. 4M>=4L+2L 3. 5M 2L Switching Required to Reconfigure: 1.TRIP 2 2.CLOSE 3. CLEAR THOUGH FAULT FLAG 1 Switching Required to Revert: 1. TRIP 2. CLOSE 2 DevicelD R003 (device 3) DS 20 seconds DR 40 seconds NEXPF NEXPT NEXPS AEXPT M 6000 Amps Load Checks: 1. 1M>=3L+1L Substitute Sheet (Rule 26) RO/AU PCT/AUOO/00074 WO 00/48288 PCT/AUOO/00074 31 2. 2M>= 3L 2L 3. 5M 3L 4. 4M>=3L-4L Switching Required to Reconfigure; ie.called by ExecuteReconfigureSteps(): 4. TRIP 3 CLOSE Switching Required to Revert; ie. called by ExecuteReversionSteps(): 3. TRIP 4. CLOSE 3 DevicelD: R004 (device 4) DS 40 seconds DR 80 seconds NEXPF NEXPT NEXPS AEXPT M 6000 Amps Load Checks: 1. 1M>=4L+1L 2. 2M>= 4L+2L 3. 5M>= 4L Switching Required to Reconfigure: 1. TRIP 4 2. CLOSE 3. CLEAR THOUGH FAULT FLAG 3 Switching Required to Revert: 1. TRIP 2. CLOSE 4 Substitute Sheet (Rule 26) RO/AU WO 00/48288 PCT/AUOO/00074 32 DevicelD: LB005 (device M 4000 Amps Example Fault Scenarios A number of network fault scenarios are now provided to exemplify the functioning of the control arrangement of the embodiment.

Fault scenario 1: An unknown condition causes loss of supply to R001. At the time of this fault the Load Prior to Trip, L, values for each device are: 1L 2000 Amps 2 L 1000 Amps 3L 1500 Amps 4 L 500 Amps 0 Amps No device is initially in control or in the reconfigured state.

All devices are healthy.

After 20 seconds (1DS 20 Seconds) R001 (device 1) begins executing the algorithm by setting 1C TRUE.

Function CheckAllReconfigurations( is called: Control state shows only R001 is in control.

Through Fault state matches the NEXPF.

Tripped state matches the NEXPT.

Load checks are performed: 1. 6000 (3M) 1500 (3L) 2000 (1L) Pass 2. 6000 (4M) 500 (4L) 2000 (1L) Pass 3. 4000 (5M) 2000 (1L) Pass 4 6000 (2M) 2000 (1L) 1000 (2L) Pass CheckAllReconfigurationConditions() returns TRUE Substitute Sheet (Rule 26) RO/AU WO 00/48288 PCT/AUOO/00074 33 Function ExecuteStepsToReconfigure is called and executes and verifies the two configured steps in order to Trip R001 and then Close LB005, thus restoring supply to the loads normally supplied through R001.

Fault Scenario 2: A fault condition causes R001 to Trip with the Through Fault Flag set to TRUE, supply is lost to R002 and LB005. At the time of this fault the Load Prior to Trip, L, values for each device are: 1L 2000 Amps 2L 1000 Amps 3L 1500 Amps 4 L 500 Amps 0 Amps No device is initially in control or in the reconfigured state.

All devices are healthy.

After 40 seconds (2DS 40 Seconds) R002 (device 2) begins executing the algorithm by setting 2C TRUE.

Function CheckAllReconfigurations( is called: Control state shows only R002 is in control.

Through Fault state matches the NEXPF.

Tripped state matches the NEXPT.

Load checks are performed: 6000 (3M) 1500 (3L) 2000 (1L) Pass 6. 6000 (4M) 500 (4L) 2000 (1L) Pass 7. 4000 (5M) 2000 (1L) Pass 8. 6000 (2M) 2000 (1L) 1000 (2L) Pass CheckAIIReconfigurationConditions() returns TRUE Function ExecuteStepsToReconfigure( is called and executes and verifies the two configured steps in order to Trip R002 and then Close LB005, thus restoring supply to the loads normally supplied through R002.

Substitute Sheet (Rule 26) RO/AU PI 1/AUuuuuu/VI+ Received 14 November 2000 The distributed control arrangement of the first aspect of the invention is desirably arranged such that unfaulted sections of a feeder in a distribution network may be restored when there is an alternative source of supply beyond the faulted section. The control software of the preferred embodiment may be configured to support two to seven network devices in fixed topology network configurations. Optionally, the control arrangement can automatically revert to "normal" operating conditions upon the restoration of supply or clearance of the fault.

Throughout the specification the aim has been to describe the preferred embodiments of the invention without limiting the invention to any one embodiment. The intended scope of the invention is instead set out in the accompanying claims. Various alternative arrangements within the spirit of the invention and falling within the scope of the claims will occur to those of appropriate skill in the relevant art.

AMENDED

SHEET

IE2NA/U

Claims (38)

1. A method for controlling at least a portion of an electricity distribution network including conductors and a plurality of network devices cooperating with the conductors to facilitate distribution of electricity, wherein control apparatus are co-located with selected network devices and communications apparatus are associated with each control apparatus to provide a communications link therebetween, said method including the steps of: monitoring of distribution network state by the control apparatus co-located with the selected network devices; and upon detection of an abnormal condition in the distribution network, one of the control apparatus checks whether the network state matches an expected abnormal operating pattern and temporarily assumes coordinating control of the network portion; whereby said one control apparatus issues commands to other control apparatus over the communications link in accordance with a predetermined automation scheme.

2. The control method of claim 1 wherein the step of monitoring distribution network state includes monitoring status of the network devices associated with the control apparatus.

3. The control method of claim 2 wherein monitoring the status of network devices includes monitoring voltage, current and other electrical parameters proximate to said network device.

4. The control method of any one of claims 1 to 3 wherein the control method involves the further step of said control devices communicating the status of respective network devices to each other over the communications link. The control method of any one of claims 1 to 4 wherein coordinating control of the network devices is assumed by the control apparatus that detects the abnormal condition proximate to an associated network device.

6. The control method of any one of claims 1 to 5 wherein said v control apparatus include a plurality of network switching sequences for AMENDFI -SHEET PC'I'/AUUU/UUU 14 Received 14 November 2000 36 addressing said abnormal operating patterns, which sequences are programmed by a user to implement the automation scheme adapted to the distribution network configuration.

7. A control arrangement for an electricity distribution network including conductors and a plurality of network devices cooperating with the conductors to facilitate distribution of electricity, which control arrangement includes: control apparatus co-located with selected network devices for controlling the operation of each network device in accordance with a predetermined automation scheme; and communications apparatus associated with each control apparatus for providing a communications link between the control apparatus; whereby distribution network state is monitored by each said control apparatus for the occurence of expected abnormal operating patterns in order to effect decentralised coordination of network device operations.

8. The control arrangement of claim 7 wherein the control apparatus are each arranged to detect abnormal conditions in the distribution network proximate to the network device associated with an individual control apparatus.

9. The control arrangement of either claim 7 or claim 8 wherein the individual control apparatus which detects an abnormal network condition temporarily assumes coordination by issuing commands to other network devices via the communications link.

10. The control arrangement of any one of claims 7 to 9 wherein the control arrangement is temporarily coordinated by any one control apparatus in the event of an abnormal condition in the network.

11. The control arrangement of any one of claims 7 to 10 wherein the control apparatus may be further arranged for loading with user programmable switching sequences for addressing said abnormal operating pattemrns, which sequences implement the predetermined )automation scheme adapted to the distribution network configuration. IME2fd, sjE- I$EA/AU PC'I'/AUUU/UUU/4 Received 14 November 2000 37

12. A method for controlling switchgear in at least a portion of an electricity distribution network, which network portion includes a group of switches, sources of supply and interconnections between the sources of supply and the switches, wherein at least two of said switches include control apparatus co-located therewith and the respective control apparatus can communicate, the method including the steps of: monitoring distribution network state by each control apparatus for switches in the group; if an abnormal condition is detected in the distribution network by a control apparatus, the control apparatus checks whether the network state matches one of a plurality of abnormal operating pattemrns expected in the group of switches; (ii) if the network state matches an expected abnormal operating pattern, then said control apparatus communicates with respective control apparatus for other switches in the group to execute a predetermined switching sequence prepared for addressing the abnormal operating condition corresponding to said matching pattem.

13. The switchgear control method of claim 12 wherein the abnormal condition in step is loss of supply at a predefined place in the network portion.

14. The switchgear control method of either claim 12 or 13 wherein the expected abnormal operating pattems include one or more of the following patterns in the group of switches: an expected fault pattern; and/or an expected tripped pattern; and/or an expected source supply patternm. The switchgear control method of any one of claims 12 to 14 )wherein the control apparatus for the switch assumes control of the group AMENDED SHE2ET PCT/AU00/00074 Received 14 November 2000 38 of switches when the network state matches an expected abnormal operating patternm.

16. The switchgear control method of claim 15 wherein the control apparatus assumes control after a predetermined time delay.

17. The switchgear control method of any one of claims 12 to 16 wherein the step of checking network state in sub-step includes the steps of: checking that all control apparatus are programmed with an equivalent automation scheme; and/or checking that no other control apparatus is already in control of the group of switches.

18. The switchgear control method of any one of claims 12 to 17 further including the following steps subsequent to step if the control apparatus has assumed control and a normal condition is detected in the distribution network, then the control apparatus of said switch checks whether the network state matches one of a plurality of patterns expected in the group of switches; (ii) if the network state does match an expected pattern, then said control apparatus communicates with respective control apparatus for other switches in the group to execute a predetermined switching sequence prepared for recovering from the abnormal operating condition and releases control of the group of switches.

19. The switchgear control method of claim 18 wherein the normal condition in step is the restoration of supply to a switch for a pre- determined time delay. A method for controlling switchgear in at least a portion of an electricity distribution network, which network portion includes a group of AMEN DD SHEET PCI'/AUUU/UUU /4 Received 14 November 2000 39 switches, sources of supply and interconnections between the sources of supply and the switches, wherein the switches are associated with a control apparatus, the method including the steps of: monitoring distribution network state by the control apparatus for switches in the group; if an abnormal condition is detected in the distribution network, the control apparatus checks whether the network state matches one of a plurality of abnormal operating pattemrns expected in the group of switches; (ii) if the network state matches an expected abnormal operating pattemrn, then said control apparatus assumes control of the group of switches and communicates with the group to execute a predetermined switching sequence prepared for addressing the abnormal operating condition corresponding to said matching pattern.

21. The switchgear control method of claim 20 wherein the abnormal condition in step is loss of supply at a predefined place in the network portion.

22. The switchgear control method of either claim 20 or claim 21 wherein the control apparatus for the switches assumes control in sub- step (ii) after a predetermined time.

23. The switchgear control method of any one of claims 20 to 22 wherein the expected abnormal operating patterns include one or more of the following patterns in the group of switches: an expected fault pattern; and/or an expected tripped pattern; and/or an expected source supply patternm.

24. The switchgear control method of any one of claims 20 to 23 Sfurther including the following steps subsequent to step -v PCT/AU00/00074 Received 14 November 2000 if the control apparatus has assumed control and a normal condition is detected in the distribution network, then the control apparatus checks whether the network state matches one of a plurality of patterns expected in the group of switches; (ii) if the network state does match an expected pattern, then said control apparatus communicates with the switches in the group to execute a predetermined switching sequence prepared for recovering from the abnormal operating condition. The switchgear control method of claim 24 wherein the normal condition in step is the restoration of supply to a switch for a pre- determined time delay.

26. The switchgear control method of any one of claims 20 to wherein a control apparatus is co-located with each switch in the group and a predetermined control apparatus always assumes control by issuing commands over a communications link to the control apparatus co-located with other switches.

27. The switchgear control method of any one of claims 20 to wherein a slave control apparatus is co-located with each switch in the group and a master control apparatus, located remotely from said group of switches, always assumes control by issuing commands over a communications link to the slave control apparatus.

28. A control apparatus for controlling a network device which cooperates with conductors in an electricity distribution network, said control apparatus including: a detection module for monitoring distribution network conditions at the network device; a processor interfaced to the detection module for receiving information about the distribution network conditions; memory means accessible by the processor for storing a common control program, operating parameters for the network device and plurality ,MM6DE0 -HEET IPNAULI PCT/AU00/00074 Received 14 November 2000 41 of expected abnormal operating patterns which occur during abnormal network conditions; an actuator for operating the network device, which actuator is controlled by the processor; and a communications apparatus interfaced to the processor for providing a communications link with other control apparatus associated with other network devices in a portion of the electricity distribution network; wherein the control program effects operation of the network device and facilitates communications with the other control apparatus in accordance with a predetermined automation scheme.

29. The control apparatus of claim 28 wherein the memory includes a database for storing the plurality of expected abnormal operating patterns. The control apparatus of either claim 28 or claim 29 wherein the network devices include switches.

31. The control apparatus of any one of claims 28 to 30 wherein the memory stores a plurality of switching sequences for operating the network devices to address respective abnormal network conditions.

32. A method for configuration of control apparatus associated with a group of network devices, which devices are in an electricity distribution network, said method including the steps of: creating a representation of at least a portion of the distribution network including the group of network devices, which representation defines sources of supply and interconnections between the sources and network devices in said distribution network; (hb defining one or more normal operating patterns of the distribution network by recording a corresponding normal status of each network device in said group of devices; defining a plurality of abnormal operating patterns, for each normal operating pattemrn, which impact adversely on distribution network integrity; defining a switching sequence for said group of network devices for each abnormal operating pattern for limiting adverse effects IAMPENDEr LHEET ,!EAJAL! PCT/AU00/00074 Received 14 November 2000 42 thereof, which sequences may be automatically initiated in response to an abnormal condition in the network portion; automatically generating a controller configuration file, including the abnormal operating patterns and the switching sequences; and loading said controller configuration file into the control apparatus.

33. The configuration method of claim 32 wherein the control apparatus is co-located with respective network devices.

34. The configuration method of claim 32 wherein the control apparatus is located remotely from said group of switches.

35. The configuration method of any one of claims 32 to 34 wherein the group of network devices includes switches.

36. The configuration method of claim 35 wherein at least one of the switches in the group includes a voltage sensing facility for sensing an abnormal condition.

37. The configuration method of either claim 35 or claim 36 wherein at least one of the switches in the group includes a through-fault current detection facility for sensing an abnormal condition.

38. The configuration method of any one of claims 35 to 37 wherein the representation of the distribution network is a diagram which graphically illustrates the group of switches, the sources of supply and the interconnections therebetween.

39. The configuration method of any one of claims 35 to 38 wherein the status of each switch includes whether the switch is normally open or normally closed and the maximum load current able to be carried by the 2network proximate to the switch. .SHEET PCT/AU00/00074 Received 14 November 2000 43 The configuration method of any one of claims 33 to 39 wherein the plurality of abnormal operating patterns are defined by selecting the position of an abnormal event on the representation and simulating the response of the group of network devices to the event in order to generate an abnormal operating pattern.

41. The configuration method of any one of claims 33 to 40 wherein the switching sequences are defined by selecting the network devices on the representation in the desired sequence for a respective abnormal operating patternm.

42. The configuration method of any one of claims 33 to 41 wherein a set of suggested steps for addressing a particular abnormal operating pattern is automatically produced to assist definition of the switching sequence.

43. The configuration method of any one of claims 33 to 42 wherein, upon analysis of the representation created by the user, further abnormal operating patterns are automatically produced and presented to a user.

44. An automated tool for configuration of control apparatus associated with a network device, which device is one of a group of devices in an electricity distribution network; said tool including: a graphical user interface for creating a representation of at least a portion of the distribution network including the group of network devices and identifying at least one normal operating pattern; a database coupled to the user interface for storing the representation of the network portion, characteristics of each network device in the group and said at least one normal operating pattern; a protection and load flow engine coupled to the database for simulating the operation of the group of network devices based on the operational parameters of each device and PCT/AU00/00074 Received 14 November 2000 their interconnections to user specified abnormal events; and (ii) solving the load flow for the representation of the network whereby an abnormal operating pattem is defined for each abnormal event; and wherein the automated tool facilitates definition of a switching sequence for the group of network devices for limiting the adverse effects of each abnormal operating pattern. AMENDED SHEET IFEA/ALE