Description

The present invention relates to an apparatus for use in a circuit breaker, a circuit breaker, a method for controlling a circuit breaker as well as a computer program product related thereto.

Generic circuit breakers are provided in power grids which serve for the distribution of electrical energy, e.g. a power plant generating electric energy to be supplied to consumers consuming this energy. Safe and reliable operation of such power grids is important, especially, in view of decentralization of power generation. Power transmission is effected by one or more power lines which are usually provided by cable of metal such as copper, silver, aluminium, alloys thereof, or the like. The power cables can be provided with an insulative coating of less electric conductivity such as plastics, lacquer, or the like. Essential components of the power grid are circuit breakers performing physical connection and/or disconnection of a power line according to a predefined rule. The circuit breaker can interrupt current flow, keep a power line voltage idle, and/or the like.

Circuit breakers can be provided with automatic operation properties, namely, vacuum reclosers. Such reclosers are used for adaptive breaking of power lines in case of a detected failure. The reclosers provide automatic reconnection after disconnection if the electrical conditions of the connected circuits are acceptable. As far as the power generation is concentrated on a few power plants, the power grid operates sufficiently. However, more and more localized power generation is provided, wherein the distributed power generation may result in misoperation of reclosers.

It is therefore the object of the invention, to improve circuit breakers and methods for their operation such that they can better handle complex power grid structures.

According to a first apparatus-related aspect of the invention, there is provided an apparatus for use in a circuit breaker, the apparatus comprising: a control module configured to control a switch unit electrically connected with two power ports, wherein the switch unit is configured to provide a switchable connection between the two power ports; detect a first identification (ID) allocated to said circuit breaker and first status information of the circuit breaker; and cause a transceiver to transmit said first ID and said first status information, wherein said first ID and said first status information are transmitted via at least one of the power lines connected to the power ports.

According to a second aspect, a circuit breaker is provided, comprising: two electric power ports, each being configured to be connected with a power line of a power grid; a switch unit electrically connected with both power ports, wherein the switch unit is configured to provide a switchable connection between the two power ports; an ID allocated to said circuit breaker; and an apparatus according to the first aspect. According to a third method-related aspect, there is provided a method for controlling a circuit breaker, the method comprising the steps of: controlling a switch unit electrically connected with two power ports, wherein the switch unit is configured to provide a switchable connection between the two power ports; detecting a first ID allocated to said circuit breaker and first status information of the circuit breaker; and transmitting said first ID and said first status information, wherein said first ID and said first status information are transmitted via at least one of the power lines connected to the power ports .

According to a fourth aspect of the present invention, there are provided one or more computer program products including a program for a processing device, comprising software code portions of a program for performing the steps of the method according to the second method-related aspect when the program is run on the processing device. The computer program products comprise further computer- executable components which, when the program is run on a computer, are configured to carry out the respective method as referred herein above. The above computer program product may further comprise computer-executable components which, when the program is run on a computer, perform the method aspects mentioned above in connection with the method aspects. The above computer program product/products may be embodied as a computer-readable storage medium. Further aspects of at least some exemplary embodiments of the aspects of the invention are set out in the respective dependent claims. A circuit breaker is a kind of a switch device which is adapted to be used in an electric power supply network, or power grid, respectively. The circuit breaker is an automatically operated electrical switch designed to protect an electrical circuit from damage caused by overload or short circuit, or the like. Consequently, the circuit breaker is configured to detect a fault condition in a connected portion of the network and to provide interruption of current flow upon detection of the before mentioned fault conditions. Deviant from simple fuse operation, which can provide interruption of the current flow only once and then needs to be replaced, the circuit breaker can be reset manually or automatically to resume normal operation. Circuit breakers adapted for automatic resumption of the normal operation are also referred to as reclosers .

The size of the circuit breaker depends on the number of poles of the switch unit and power ports connected therewith, the voltage ratings and the nominal current ratings which the circuit breaker is adapted to operate with. Although all circuit breakers have common features in their operation, details may vary substantially depending on the voltage class, the current rating and the type of circuit breaker. The circuit breaker must be able to detect a fault condition as mentioned before. Circuit breakers for large currents or high voltages may be usually arranged with pilot devices in order to sense a fault current and to operate a trip opening mechanism. A trip solenoid that releases a latch, is usually energized by a separate battery in order to provide a proper operation independent from any grid-depending power supply. Once a fault is detected, contacts of the switch unit within the circuit breaker open in order to interrupt the circuit. The energy for opening the contacts may be mechanically stored such as energy of a spring or may be received from the fault current itself, or the like.

The contacts of the switch unit of the circuit breaker must carry the load count without excessive heating and must also withstand the heat of arc produced when opening or interrupting, respectively, the circuit. Circuit breakers are subject of standardization such as IEC68898-1 and the like .

According to the invention, new emergency automation approaches can be achieved which allow a reliable operation of a decentralized power grid or power network, respectively, such as a smart grid. Moreover, the invention allows local control of installed local circuit breakers of a power grid having complex topologies. Thus, different online control strategies can be implemented with the circuit breakers using certain algorithms, modern communication technologies and available measurements. Electrical network emergency automation in a smart grid, self-organizing way, enhancing the quality of provided power inside the scope of modern power systems can be achieved .

The invention can be advantageously be implemented in circuit breakers or the like devices. That is, it can be implemented as/in chip sets to connected devices and/or modems thereof. More generally, various systems which allow for a circuit breaker operation mode, especially relying on safety functions may see performance improvement, especially in view of complex network topologies, with the invention being implemented thereto.

The circuit breaker usually comprises at least two electric power ports depending on the desired switching operation such as simple on-off-switching, double-pole-double-throw, or the like, each power ports being configured to be connected with a power line of a power grid. Generally, the circuit breaker controls and provides for connection between the at least two power ports. The power ports can be implemented as metal contact parts that are often made from copper, aluminium, silver, combinations thereof, alloys thereof, and the like. The power ports or power poles, respectively, are adapted to be connected each with a power line between which the circuit breaker controls an electric connection. The circuit breaker and moreover the switch unit can have more than two power ports, for example three, four or more. Consequently, various connection schemes can be implemented by the circuit breaker or the switch unit, respectively.

The switch unit is preferably a component of the circuit breaker and is configured to provide a switchable connection between the at least two power ports.

Moreover, the circuit breaker of the invention comprises an apparatus for use in said circuit breaker, which apparatus is provided for controlling at least the switch unit. The apparatus can be provided as a chip set, a hardware circuitry, combinations thereof, or the like, that provides some ^' computing and measurement processing. For this purpose, the apparatus is controllably connected with the switch unit and preferably integrated in the circuit breaker, especially a housing of the circuit breaker.

Consequently, the apparatus comprises a control module configured to control the switch unit electrically connected with the power ports, wherein the switch unit is configured to provide a switchable connection between the two power ports. Moreover, the control module of the apparatus is configured to detect a first ID allocated to said circuit breaker and first status information of the circuit breaker. Generally, the ID of the circuit breaker is an identification (ID) and can be any combination of characters which is unique to this certain circuit breaker. Consequently, the ID allows identifying the circuit breaker in a plurality of circuit breakers. The ID can be read automatically by the control module of the apparatus from a portion of the circuit breaker containing its ID. Consequently, the ID is present in the control module. Moreover, the control module detects first status information of the circuit breaker which can be the connecting status of the switch unit, current information, especially rated current information, voltage information, especially rated voltage information, further operational information, and/or the like.

The control module is, according to one exemplary embodiment, integral with the apparatus or it is, according to another exemplary embodiment, a separate component of the apparatus. The apparatus and/or the control module are established as a hardware circuitry, a computer running a program, and/or the like. The apparatus and/or the control module may be a hardware circuitry, a computer or a processing device running a program, combinations thereof, or the like. So, the apparatus and/or the control module may also be provided as a chip such as a semiconductor chip which may form a component of the device for use in diagnostics of bearings, a respective expert system, or it may be integral therewith.

The circuit breaker further comprises a transceiver which is adapted to provide a communication link via at least one of the power lines connected to the power ports of the circuit breaker, or switch unit, respectively. So, the circuit breaker can exchange information with other circuit breakers via the power grid. Without departing from the scope of the invention, the communication link can also be provided via radio, a communication network such as the Internet, combinations thereof, or the like.

According to the invention, the control module causes the transceiver to transmit said first ID and said first status information of the present circuit breaker. The transceiver transmits this information, for example, such as broadcast, device-to-device, combinations thereof, or the like.

This allows any other circuit breaker to receive important information about this circuit breaker, which is why this circuit breaker is also referred to as the first circuit breaker. This information can be used for sophisticated control according to the invention.

According to another embodiment of the invention, the control module is further configured to detect receipt of a second ID allocated to a second circuit breaker, and second status information of the second circuit breaker by the transceiver via at least one of the power lines connected to the first circuit breaker. So, the first circuit breaker . . , _{w i}

9 can receive information of other circuit breakers such as the second circuit breaker, in order to receive information about the status of the power grid or parts thereof. Preferably, the second status information refers to the same or similar items as the first status information of the first circuit breaker.

Moreover, according to another embodiment of the invention, said first ID and said first status information are transmitted upon a predefined condition. The predefined condition can be a certain time of a day, a week, a month, or the like, or it can be initiated upon receipt of status information of a certain other circuit breaker such as the second circuit breaker. Such conditions are preferably predefined in the apparatus.

For the various purposes of providing and receiving information and processing, the apparatus preferably comprises a storage which is suited to store the relevant data, especially the IDs of the various circuit breakers and the corresponding status information. The storage is communicatively connected with the apparatus, especially with the control module. The storage can be any suitable storage such as Random Access Memory (RAM) , hard disc drive, compact disc, combinations thereof, and/or the like.

According to a further exemplary embodiment, the control module is configured to cause detection of a voltage status. The voltage status refers to at least one of the power lines connected to the circuit breaker. For example, the voltage status can be idle, in case of all connecting circuit breakers interrupt energy supply because of failure, overload, and/or the like. According to yet another embodiment, the apparatus comprises a control module which is configured to determine circuit breakers, especially other circuit breakers, that may be affected when changing the voltage status, especially such of a certain power line. Preferably, such circuit breakers are determined which are electrically connected with a power line connected to the first circuit breaker that is intended to change its voltage status. So, all circuit breakers connected to this certain power line are determined. Their IDs can be stored in the storage. Moreover, a certain request can be transmitted by the transceiver requesting circuit breakers connected to this certain power line to respond with a corresponding response .

According to another exemplary embodiment, the control module is further configured to detect receipt of a status change request signal including the first ID; and, in response thereto, cause the switch unit of the circuit breaker to switch. This embodiment is directed to the situation that the present first circuit breaker is regarded as a slave operating circuit breaker that switches its switch unit upon command received from a master-circuit breaker. So, the master-circuit breaker controls the whole situation, for example, for a local operation mode of one or more power lines. The master-circuit breaker can be a host-circuit breaker which is generally determined to control this region. However, the master-circuit breaker can be also calculated and varying from the present situation of operation, for example, depending on power lines to be switched, various parameters of operation, and/or the like. The transceiver surveys the communication traffic on the power lines and, as far as information transmitted from other receivers arrive at the control module including the first ID, the control module acts as requested. The request including the ID may alternatively request the apparatus to transmit circuit breaker-related information such as status of the switch unit, various ratings, various actual parameters, combinations thereof, and/or the like.

Moreover, according to a certain exemplary embodiment, the control module is configured to process at least the first and the second status information; determine whether the apparatus is responsible to act; and, if determination results in the apparatus being responsible to act, generate a status change request signal including one of the IDs as calculated ID. This embodiment deals with the situation that the present apparatus is operating as a master so that the corresponding first circuit breaker is a master-circuit breaker. In order to determine whether the apparatus is operating as a slave, the first and the second status information are processed, which can be established by a computer being included by the apparatus, especially by the control module. For example, the apparatus can be determined to be a master previously. However, this can also be calculated upon parameters included in the first and the second status information. However, processing needs not to be limited to the first and the second status information, but it can also include further information, especially status information of other relevant circuit breakers. The result of the process is the determination whether the apparatus is responsible to act. The responsibility to action defines the master which operates the corresponding situation. If the result of the processing is that the present apparatus is not the master, the apparatus, or the control module, respectively, acts as a slave and awaits corresponding requests. If, however, determination results in the apparatus being responsible to act, that is, the apparatus is the master, processing further identifies a circuit breaker to be operated so that in response hereto a status change request signal is generated, which includes the corresponding ID as calculated ID. This calculated ID is transmitted via the transceiver to the corresponding circuit breaker, or broadcast. Anyway, the addressed circuit breaker receives the status change request signal including its ID and reacts by corresponding operation as requested. The operation can be that the switch unit switches, for example, in order to provide a connection between its power ports .

According to another exemplary embodiment, the control module is configured to cause the switch unit of the circuit breaker to switch if the calculated ID corresponds to the first ID. In this case, processing, as mentioned before, results in the present apparatus being a slave. Therefore, the control module does not operate by itself, but awaits corresponding request. The corresponding request is identified by a calculated ID, which corresponds to the first ID, which is the ID of the present first circuit breaker .

The teachings of the present invention can be readily understood and at least some additional specific details will appear by considering the following detailed description of some exemplary embodiments in conjunction with accompanying drawings, in which: IG 1 shows schematically a block diagram of a structure of a power grid provided with circuit breakers according to the invention; IG 2 shows schematically a block diagram of an apparatus, which is comprised by a circuit breaker of the invention; IG 3 shows schematically a block diagram of a recloser including the apparatus according to FIG 2;

FIG 4 shows schematically a diagram, wherein a graph indicates weighting of the current; and

FIG 5 shows schematically a diagram, wherein a graph indicates weighting of the time.

FIG 1 shows a block diagram schematically including a plurality of substations 10, 36, 38, 40 and buildings F, HH, 12, 14, 16, 18, 20, 42, 48 which are connected via power lines of a power grid 34 which supplies electric power from the substations 10, 36, 38, 40 to the buildings F, HH, 12, 14, 16, 18, 20, 42, 48. In the power lines, circuit breakers in the form of reclosers R are provided in order to provide a reliable operation of the power grid 34 even in cases of local failures related to the power lines. In the non-operating status, the various reclosers R are operated such that each of the buildings F, HH, 12, 14, 16, 18, 20, 42, 48 is properly supplied with electric energy from at least one of the corresponding substations 10, 36, 38, 40. s can be seen from FIG 1, groups of buildings can be supplied with electric energy from one or more of the substations 10, 36, 38, 40. For example, the buildings indicated by reference character 16 can be supplied from substation 36 and/or substation 40. Similarly, building 14 can be supplied from substation 10 and/or substation 36. Only the buildings 42 can be supplied exclusively from substation 38. The buildings F, HH, 12, 18, 20, 48 can be supplied by substations 10, 36, and 38. The energy flow from the substations 10, 36, 38, 40 to the buildings F, HH, 12, 14, 16, 18, 20, 42, 48 is controlled by the reclosers R. Preferably, the reclosers R are switched in such a way that a certain building F, HH, 12, 14, 16, 18, 20, 42, 48 is supplied with electric energy from only one of the substations 10, 36, 38, 40. Consequently, the reclosers R are correspondingly switched.

In the present case, the reclosers R are designed to protect overhead lines supplying the substations 10, 36, 38, 40 with electric energy from power plants which are not indicated in the figures.

In the majority of cases, power line faults are formed by transient and can be fixed by auto reclosing. Consequently, the circuit breaker in the form of reclosers, which may use vacuum reclosing technology, comprises two main parts, namely, a switch unit 44, which is capable of interrupting the current flow between power lines connected with the switch unit 44, and an apparatus 22 (FIG 3), which may be established by a programmable controller, preferably comprising a processing device. In this embodiment, each recloser R has its own default control strategy or recloser cycle, respectively: 1. Quick reclosing within 300 ms,

2. Delayed reclosing so that downstream overcurrent devices will have a chance to operate and localize the fault,

3. Quick reclosing in order to check if external bodies on the power line have been removed,

4. Lockout .

The recloser R is able to measure a variety of network parameters such as current, line and phase voltages, phase angles, real and reactive powers, power factor, and/or the like. Moreover, each recloser R is provided with the ability to store grid state information, especially, some events and failures happened on the power lines which the certain recloser is connected with.

Therefore, each recloser R provides strong protective functionality. However, misoperation may appear because of, for example, electromagnetic compatibility issues (EMC) . The invention addresses these and other deficiencies by providing additional operation logic in the reclosers R. Especially, a possibility to establish cooperative control of all available reclosers R is provided so that more intelligent operation can be achieved.

Considering the power grid of FIG 1, which is, in this embodiment, operating at a rated voltage of 12 kV, each of the buildings 12, 14, 16, 18, 20, 42, 48 symbolizes a group of consumers such as private households, municipal buildings, industry facilities, and the like. According to a further exemplary embodiment, the rated voltage is 400 V, 1 kV, 20 kV, another rated value, preferably, a standardized rated value for the voltage. The inventive concept for coordinated reclosers' R operation is intended to use the following technical features :

1. Simple Broadband Power Line Communication (BPLC) modem installed at every recloser R,

2. Control algorithm installed at every apparatus 22.

A general scheme of a BPLC modem corresponds to the apparatus 22. The apparatus 22 in turn is a component of the recloser R and, preferably, incorporated in a housing of the recloser R. However, in an alternate embodiment, the apparatus 22 can be arranged distal from the recloser R.

As can be seen from FIG 3, the apparatus 22 comprises a control module 32, which is presently formed by a control unit, which controls the switch unit 44 and is further communicatively coupled with a transceiver 24, which is in this embodiment included in the apparatus 22. The transceiver 24 forms the BPLC modem (FIG 2) . However, in an alternative embodiment, the transceiver may be excluded from the apparatus 22 and form a separate component of the recloser R. In this case, a certain communication link may be established between the control unit 32 and the transceiver 24. Moreover, the apparatus 22 comprises a computer and storage unit 30 as a processing device, which may be provided by a conventional microprocessor having a flash RAM coupled thereto so that the computer and storage unit 30 may provide operation by running a certain program according to a suited algorithm thereon. Optionally, in this embodiment the computer and storage unit 30 may be coupled to an Ethernet network 28, which in turn is coupled with the Internet. FIG 3 shows the recloser R with its main components in a schematic block diagram. As can be seen from FIG 3, the recloser R includes the switch unit 44, which is connected with power ports 50, 52 so that the switch unit 44 can control electric connection between the power ports 50, 52. The switch unit 44 is controlled by the control unit 32 of the apparatus 22. Moreover, the control unit 32 is communicatively connected with the transceiver 24.

Further, as can be seen from FIG 3, the transceiver 24 is communicatively connected with the power ports 50, 52 so that communication over power lines connected to the power ports 50, 52 is established.

The control unit 32 is configured to detect a first ID allocated to said recloser R and first status information of the same recloser which is the recloser R to which the apparatus 22 belongs. The first ID may be stored in the storage of the computer and storage unit 30. It may be programmed to the storage but, in an alternative embodiment, the apparatus 22 has a reader which is suited to read the ID from, for example, an ID tag or the like provided in the recloser R.

Moreover, the control unit 32 causes the transceiver 24 to transmit said first ID and said first status information, wherein said first ID and said first status information are transmitted via at least one of the power lines connected to the recloser R at its power ports 50, 52. Transmission may be directed to other known circuit breakers R, but it may also be broadcast. This operation is the same for all reclosers R. The control unit 32 detects receipt of second IDs allocated to second reclosers R and second status information of the second reclosers R by the transceiver 24 via at least one of the power lines connected to the power ports 50, 52 of the recloser R.

In order to provide a proper communication between the reclosers R, each recloser R has a certain time window when transmitting its ID and status information. The time window can be determined by a certain time of a day, which is unique for each of the reclosers R. The time window and the time are determined such that the time windows preferably do not overlap. For example, the time may be calculated by the apparatus 22, especially by the computer and storage unit 30, based on the unique identity of the certain recloser R. However, in an alternative embodiment, the time for transmitting may be determined by receipt of a previous ID of another recloser R. So, for example, a sequence of transmissions of the various reclosers R can be provided which preferably depends on the unique IDs of all of the reclosers R. Also, in an alternate exemplary embodiment, communication procedures such as defined by the 3gpp standard, LTE-advanced standard or the like is implemented in order to establish the wire-bound communication link between the reclosers R, preferably over the power line.

In the present embodiment, the control unit 32 is further configured to provide various measurements, especially, a voltage status of each of the power ports 50, 52. Moreover, the control unit 32 is aware of ratings corresponding to its circuit breaker, or recloser R, respectively. Additionally, the control unit 32 is configured to determine other reclosers R that may be affected when changing the switching status. For example, the recloser R ₄ determines that the reclosers Ri, R2, and R ₃ may be affected according to FIG 1.

The control unit 32 is further configured to detect receipt of a status change request signal including the first ID, that is, the ID of the present recloser R. In response thereto, the control unit 32 is configured to switch the switch unit 44 of the recloser R. This corresponds to a slave-operation, where one other of the reclosers R operates as a master. Determination of the master recloser R may vary from time to time and from certain operational requirements as will become apparent in the proceeding embodiment .

The control unit 32 is further configured to process its own first status information and further receive second status information of other reclosers R. Consequently, the control unit 32 determines whether the own apparatus 22 is responsible to act in the present case. That is, the control unit 32 determines whether to act as a slave or as a master.

If determination results in the apparatus 22 being responsible to act as a master, the control unit 32 generates a status change request signal including one ID as a calculated ID of a recloser R, which is requested to act correspondingly as a slave. Action is preferably provided by switching of the switch unit 44 of the corresponding recloser R. In this case, the control unit 32 determines the present recloser R as a master. Consequently, the control unit 32 is configured to cause the transceiver 24 to transmit the status change request signal if the calculated ID differs from the first ID, which is why the present recloser R is the master. The transceiver 24 provides transmission of the status change request signal via the power ports 50, 52 so that this signal can be received by the corresponding recloser R having its ID respectively to the calculated ID.

If the result of processing is the own first ID, the control unit 32 causes the switch unit 44 of its recloser R to switch.

The transmitter 24 is provided as the BPLC modem coupled to the power grid 34 near the respective recloser R and connected to its digital input. The BPLC modem sends, upon request of the control unit 32, a simple signal according to an embodiment, which includes a coded number as an ID of the recloser R and its state via the power line. Moreover, it receives similar signals from other BPLC modems associated with other reclosers R in communication range, preferably neighbouring reclosers.

In this embodiment, the signals are simple so that they can be operated by a control unit 32 formed by a field programmable gate array (FPGA) component so that small costs can be achieved. So, in this embodiment, each recloser R recognizes its neighbouring reclosers and acts depending on their states. At every sample time, i.e. in the corresponding time window, the apparatus 22 receives the information about the other reclosers R or their absence in case of fault. Moreover, the apparatus 22 receives measured data from a host recloser R. Then, the computer and storage unit 30 processes the data received and generates a control signal for the present recloser R.

Recloser' s intelligence consists of its ability to communicate with other reclosers R and, preferably, with smart buildings such as the buildings F, HH, 12, 14, 16, 18, 20, 42, 48. Communication is preferably established via power line communication (PLC) including transmitting of signals, and receiving of signals including consumers' importance indices. An index indicates an importance of the certain consumer to be considered how harmful a breakdown of this consumer may be. Each of the buildings is expected to be equipped with a respective device broadcasting its own importance index. For example, municipal buildings such as hospitals, kindergardens, and the like, may have values that are inherently high. Alternatively, private households and other groups of consumers may include a variable part to be introduced in the calculation of the index, depending on, e.g., how accurately this consumer pays for the delivered energy. In the present embodiment, since hereby medium voltage level is considered, averaged index is proposed to be calculated for each group of consumers (FIG 1) . More specifically according to an exemplary embodiment, the power grid 34 includes as many reclosers R as needed. Each recloser R transmits a unique signal combination of numbers to all other reclosers R once a day. This process is also referred to as reclosers' synchronization. During synchronization, each recloser R receives through the PLC codes or numbers of preferably all other reclosers R. Since the transmission time of the signal is known, for example, every day at 12 p.m., and all codes are coming in a certain order, it is possible to know the neighbouring reclosers R to the present recloser R.

According to a certain embodiment, only the closest ten, in terms of connection line length, reclosers R are called recloser' s neighbourhood. So, each recloser R is aware of its neighbouring reclosers R for the current day. Consequently, each recloser R is enabled to adjust its actions with the neighbouring reclosers R if required.

For example, a recloser R consults its neighbouring reclosers R whether it shall close or open. According to an exemplary embodiment, this is provided in the following way. A particular recloser R knows about the importance of the line it belongs to. The importance can be ascertained based on historical measurements of voltage and current, for example, during a couple of previous days, wherein based hereon, its importance can be calculated. For example, if transmission currents are high for the considered history and voltage slightly decreases, the importance is high and some corresponding importance coefficient can be calculated.

According to a certain embodiment, if a certain recloser R wants to open that is, to switch off the switch unit 44, it contacts its neighbouring reclosers R, whether they can open. For this embodiment, it is referred to the example in FIG 1. In the following exemplary embodiment, the consumer F in Fig. 1 has a high importance index and requires more energy. An overload condition is provided in the power grid 34. In order to avoid an emergency shut-down of the complete power grid 34 caused by the overload condition, there must be decided fast, how the overload condition can be handled by switching off one or more reclosers R in advance that supply consumers having low importance index. In this embodiment, the households HH have a low importance index. Generally, recloser R ₄ is provided as a recloser for maintenance and service purposes so that this recloser is usually open that is, switched off.

Consequently, the overload condition is to be handled by the reclosers Ri, R ₂ , and R ₃ . They form a neighbourhood.

The message broadcast by the reclosers Ri, R ₂ , and R ₃ is: "ID: 1; state: closed (switched on); action: opening (switch off) with importance 92; present current: 100 A; voltage: 12 kV" . The reclosers Ri, R ₂ , in the neighbourhood receive this information and react by responding in the following way: "ID: 2; state: closed; action: better I open; importance: 26; current: 20 A", "ID: 3; state: closed; action: better I open; importance: 74; current: 50 A". All reclosers Ri, R ₂ , and R ₃ calculated whether they are master or slave. For this purpose, the present currents of the reclosers Ri, R ₂ , and R ₃ are measured and weighted factors are resulted by considering a weighting function according to FIG 4. The same is calculated for the time according to FIG 5 considering how long the current was present. The curves 1, 2 and 3 belong to one day, two days, or three days in this embodiment. This is provided in every recloser so that each recloser, having in mind that each recloser knows about its neighbourhood, can determine whether it is master or slave. In this embodiment, recloser Rx is the master and reclosers R ₂ and R ₃ are slaves. The recloser Ri having the corresponding ID 1, which has been responsible for the closing action request, compares importance and current of each recloser Ri, R ₂ , and R3 in its neighbourhood and chooses that one to close, based on importance and current, with the following message: "ID: 1; state: open; action: close ID: 2; reason: lowest current and importance". Consequently, the recloser R having the ID 2 closes on request. Selection is based on the importance indices as discussed above. In this embodiment, the consumer F has a higher importance than the households HH. Consequently, the recloser Ri decides that recloser R ₂ is to be opened. So, a command including the ID of the recloser R ₂ is transmitted by the recloser Ri causing recloser R ₂ to open or switch off, respectively.

Then, after some time, the reclosers Ri, R ₂ , and R3 discuss whether the taken action has been successful. If not, the system based on the previously mentioned reclosers Ri, R ₂ , and R3 is doing backup, that is, going to a previous state, and in the following, closes a second ranked. This process is ongoing as long as the fault is not isolated. This prevents important lines from being closed and saves heavily loaded lines in operation.

Such process has global convergence to an optimum structure of reclosers' states due to the internal setup of the algorithm. This algorithm is also referred to as Uproar Algorithm for Reclosers Management (UARM) .

The main advantages of the invention

1. smart reclosing extension of circuit breakers such as vacuum reclosers life cycle length by avoidance of unnecessary actions, especially, reclosings for fault localization in power networks;

2. all fault-causing information is available after any circuit interruption;

3. boost of power supply reliability; and

4. cheap solution with low operation requirements.

Generally, it is noted that, while the above describes example embodiments of the invention, this description should not be viewed in a limiting manner. Rather, there are several variations and modifications, which may be made without departing from the scope of the present invention as defined in the appended claims.

If desired, the different functions and embodiments discussed herein may be performed in a different or deviating order and/or currently with each other in various ways. Furthermore, if desired, one or more of the above- described functions and/or embodiments may be optional or may be combined, preferably in an arbitrary manner.

Although various aspects of the invention are set out in the independent claims, other aspects of the invention comprise other combinations of features from the described embodiments and/or the dependent claims with the features of the independent claims, and not solely the combinations explicitly set out in the claims.

It is also observed herein that, while the above describes exemplary embodiments of the invention, this description should not be regarded as limiting the scope. Rather, there are several variations and modifications which may be made without departing from the scope of the present invention as defined in the appended claims.