Electricity distribution network and related control method

Abstract

It is an object of the present invention to provide an electricity distribution network comprising an automation system which, following the occurrence of a fault on the electrical network, allows the electrical network to be re-powered net of the portion of the electrical network affected by the fault, without the need for intervention by the operator and without the need to be integrated into a central system. This excellent result is achieved by virtue of a network automation unit, connected to the high voltage to medium voltage electrical transformation station and to the medium voltage to low voltage electrical transformation substations, configured to transmit automation logic instructions and / or automation parameters to the high voltage to medium voltage electrical transformation station and to the medium voltage to low voltage electrical transformation substations. A method is further disclosed of controlling such electricity distribution network, implementable by through a related software.

Description

[0001] ELECTRICITY DISTRIBUTION NETWORK AND RELATED CONTROL METHOD

[0002] TECHNICAL FIELD

[0003] This disclosure relates to electricity distribution networks and, more specifically, to an electricity distribution network comprising a network automation unit which allows implementing a control method using a related software.

[0004] BACKGROUND

[0005] The increased presence of distributed generation also in the distribution system adds challenges when preventing the presence of generators from affecting the operation of existing systems. For this reason, it is particularly important to control the network by means of the main electromechanical components located in the network itself. Thereby, it is necessary to monitor the status of the network and transmit the measured quantities to a control center.

[0006] Even if the distribution network is managed with a central system, some drawbacks are still there, which are to be possibly overcome, such as, for example, long intervention times, since the central system shall communicate to the operator the presence of the fault in the electrical substation and the operator shall intervene to resolve such fault, as well as the fact that the portion of the electrical network connected to the line section affected by the fault is not powered again until the operator intervenes.

[0007] To better understand the issue, reference should be made to the case of an electrical network in which two high voltage to medium voltage electrical transformation stations (HV / MV) power two medium voltage line sections (MV), which, in turn, power medium voltage to low voltage electrical transformation stations (MV / LV).

[0008] A high voltage to medium voltage electrical transformation station (HV / MV) conventionally comprises: at least one HV / MV transformer; a plurality of switches for the respective medium voltage transmission lines; a peripheral supervision and control unit; at least one protection panel, configured to open at least one switch when a fault current is detected on a respective line.

[0009] Each medium voltage to low voltage electrical transformation substation (MV / LV) conventionally comprises: at least one MV / LV transformer; a plurality of switches for the respective low voltage transmission lines and for connecting / disconnecting the substation to / from the medium voltage line; a directional fault and measurement detector or electrical transducer, configured to detect a fault along the medium voltage line.

[0010] The two medium voltage line sections are electrically separated by an open switch, so that each HV / MV station powers a respective medium voltage line section. When a fault occurs on one of the two medium voltage line sections, the protection switch of the relevant high voltage to medium voltage transformation station interrupts the line section, thus isolating all the downstream MV / LV substations. To power the utility units which may still be powered as they are located upstream of the fault, close to the high voltage to medium voltage transformation station, it is necessary for the switch of the medium voltage to low voltage transformation station closest to the fault to open, so as to allow the portion of the line upstream of the fault to be powered.

[0011] To power the medium voltage to low voltage transformation substations downstream of the fault, so as to isolate only the medium voltage line section subject to the fault, it is necessary to decide which other high voltage to medium voltage transformation station shall power not only the respective line section which it was already powering, but also those medium voltage to low voltage transformation substations which were initially part of the line section which experienced the fault and which may still be powered via another route.

[0012] A central system which supervises the electrical network helps operators understand how to reconfigure the network so that only the medium voltage line section affected by the fault between two MV / LV transformation substations remains isolated. In particular, the central system allows the peripheral units in the Secondary Cabin (RTU) to be managed and the faults to be resolved along the network by means of network automations through the following operations:

[0013] 1. Acquiring information from the field;

[0014] 2. Determining the maneuvers to be performed;

[0015] 3. Giving commands to the peripheral units (RTU).

[0016] However, this activity increases the work that must be done by the central system, which must also manage the automation of the electrical network in addition to the electrical network monitoring activities thereof and must also communicate to the operator the presence of the fault in the electrical substation concerned.

[0017] SUMMARY

[0018] It is an object of the present invention to provide an electricity distribution network comprising an automation system which, following the occurrence of a fault on the electrical network, allows the electrical network to be re-powered net of the portion of the electrical network affected by the fault, without the need for intervention by the operator and without the need for replacing the central system, being integrable therewithin without any need for modification. This excellent result is achieved by virtue of a network automation unit, connected to the high voltage to medium voltage electrical transformation station and to the medium voltage to low voltage electrical transformation substations, configured to transmit automation logic instructions and / or automation parameters to the high voltage to medium voltage electrical transformation station and to the medium voltage to low voltage electrical transformation substations.

[0019] A method is further disclosed for controlling such electricity distribution network, implementable through a related software.

[0020] This and other advantages are achieved by the present invention, as defined in the accompanying claims.

[0021] BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figures 1 to 5 diagrammatic ally show a sequence of control operations to restore the electric power supply on a medium voltage electricity distribution network following a fault.

[0023] Figure 6 shows a diagrammatic representation of the automation system of the present disclosure.

[0024] DESCRIPTION OF ILLUSTRATIVE EMBODIMENTS

[0025] The automation system of this disclosure is based on a distributed, rather than centralized, automation concept: the peripheral units (RTUs) are programmed to perform fault selection by means of fault detection devices independently of the central system, so that automation logics may be provided without the need to modify the central system itself.

[0026] This result is obtained by installing at least one automation unit along the electrical network, connected to an HV / MV electrical transformation station and to a plurality of MV / LV electrical transformation substations powered by such HV / MV electrical transformation substation.

[0027] More specifically, an electrical network according to the present disclosure comprises: at least one high voltage to medium voltage electrical transformation station 1 (HV / MV) for transforming high voltage electricity (HV) into medium voltage electricity (MV); a plurality of medium voltage to low voltage electrical transformation substations 2 (MV / LV), powered by the electrical station 1, for transforming medium voltage (MV) electricity into low voltage (LV) electricity and powering low voltage lines 3; a network automation unit, connected to the electrical station 1 and to the electrical substations 2, for transmitting automation logics and / or automation parameters; and a central control unit, connected to the electrical station 1, to the electrical substations 2 and to the automation unit, for supervising the electrical network.

[0028] According to one aspect, the HV / MV electrical transformation station 1 comprises: at least one HV / MV transformer 4; a plurality of switches for the respective transmission lines; a peripheral unit (Primary Cabin RTU), connected to each switch and to the network automation manager, and capable of: o detecting current and / or voltage values; o transmitting switch status and possible alarm signals to the automation unit; o extending network topology information to protection devices 5 on the medium voltage network (MV); and at least one protection panel 6.

[0029] According to an aspect, each MV / LV electrical transformation substation 2 comprises: at least one MV / LV transformer 7; a plurality of switches for the respective transmission lines; a peripheral unit (UP, or Secondary Cabin RTU), connected to each switch and to the network automation manager, and capable of: o detecting current and / or voltage values; o transmitting switch status and possible alarm signals to the network automation unit; o receiving commands from the network automation unit to control each switch; a fault detector or electrical transducer 5.

[0030] Primary Cabin RTUs are remote control and supervision apparatuses for high voltage to medium voltage conversion stations 1 (primary cabins). UP devices (Peripheral Units) are Remote Terminal Unit devices (RTUs) for the remote control of medium voltage to low voltage transformation substations (secondary cabins), capable of sending information (for example, information relating to measurements, the status of switches, etc.) and receiving commands (for example, opening and closing of switches, disconnectors, etc.).

[0031] Usually, when a fault 8 occurs along the line, the entire route powers the short circuit, from the primary cabin 1. By means of the algorithms, the individual UPs are able to identify the point affected by the fault, thus ensuring that it is no longer powered, by means of commands sent to the maneuvering devices present in the secondary cabins 2. Thereby, the electrical network becomes a more resilient system since faults are quickly identified and repaired.

[0032] To understand how the isolation of a medium voltage line section subject to a fault occurs, reference should be made to Figures 1 to 5.

[0033] Figure 1 shows two medium voltage line sections powered by respective high voltage to medium voltage transformation stations 1. Each medium voltage line section in turn powers a plurality of medium voltage to low voltage transformation substations 2, which power the low voltage lines 3 of the users. The two line sections join at a switch, which keeps them separated so that each medium voltage line section is powered by a respective high voltage to medium voltage transformation station 1. Each medium voltage to low voltage transformation substation 2 comprises a respective directional and measuring fault detector 5 which is configured to detect the presence of a fault on a medium voltage line section which connects two medium voltage to low voltage transformation substations 2 arranged one after the other along the medium voltage line section.

[0034] When a fault 8 occurs along a medium voltage line section (Figure 1), by virtue of the fact that the various directional and measuring fault detectors 5 are in communication with one another and with the protection panel 6 of the high voltage to medium voltage transformer station, for example by means of the IEC61850 protocol in force as of November 10, 2023, it is possible to identify (Figure 2) which medium voltage to low voltage transformer substation 2 is closest to the fault 8 and such information is shared with the upstream transformer substations 2 and with the high voltage to medium voltage transformer station 1 which powers the medium voltage line section affected by the fault 8. By means of temporary inhibition signals (Figure 3) provided to the transformer substations 2 upstream of the fault and to the high voltage to medium voltage transformer station 1, it is ensured that only the switch immediately upstream of the fault 8 opens (Figure 4), so as to power the part of the medium voltage line section upstream of the fault 8.

[0035] To allow the power supply of the portion of the medium voltage line section which is downstream of the fault 8 and which is intact, it is necessary (Figure 5) to open the switch downstream of the fault 8 and to close the switch in the connection node between the two medium voltage line sections, so that another high voltage to medium voltage transformation station 1 may power, by means of the other section, that part of medium voltage line which is not affected by the fault.

[0036] The automation system of this disclosure is positioned between the peripheral units and a central system and the main object thereof consists in governing the automation functions of the field devices and in presenting the remote control functions thereof to the central system.

[0037] In the automation system of this disclosure, two main software components may be identified:

[0038] ■ First component: user interface for the operator of the automation system and contains the business logic which implements both the configuration and monitoring workflows;

[0039] ■ Second component: field component which implements all the logics currently present in the central remote control system with regard to configuration and real-time management of the automation with the UPs.

[0040] The automation system of this disclosure conveniently uses automations for the automatic search of the fault and sectioning thereof: these are based on automatic search algorithms residing in the equipment of the secondary cabin. Such automations are based on the configuration of the UP devices present in the secondary cabins by the central remote control system, where the UP devices are capable of detecting the fault 8 on the medium voltage electrical network and section it, therefore isolate it, while the central remote control system is the system which configures the local equipment and is in charge of the real-time management in the event of a change in the actual structure of the network.

[0041] The choice of parameters by the user for the automation of the UPs of interest may be guided and will be subordinated to the features of the route and the type of fault detectors present. In fact, depending on such variables, different types of automation may be applied, described below. Automation types

[0042] The automations applicable to the UPs present in the secondary cabins are of two types:

[0043] • FRG, FNC: these are simpler automations, based on fixed parameterization, they must be adapted in case of a change in the network topology. Although this is initially imported, the individual automata do not know the mutual position thereof in the sequence of the distribution network in the actual status, but they behave respecting a series of parameters sent by the center, so as to isolate the identified fault. The times for identifying and restoring the interruption are longer than those of the second family of automations.

[0044] • FSL, SFS, SHA: these are automation models in logical selectivity, which are more advanced, as each automated node knows the position thereof with respect to the others in the actual status.

[0045] For such reason, in this case, it is necessary to know the continuous variations which may occur on the network topology, e.g., faults or maneuvers in the field which update the actual status thereof. In this perspective, it is important that the automation system of this disclosure transfers in real time not only the information related to the automation and the directions to be automated, but also those related to the non-automated part to reconstruct the entire topology and keep it aligned following each variation in the actual status of the network.

[0046] The automation of the electricity distribution network will be designed with the help of a graphical user interface and the elements involved will be presented and updated in a transparent manner. Figure 6 is a diagrammatic view of an exemplary embodiment of the automation system of this disclosure which cooperates with a central system (SCADA). The topological scheme (Topology Domain) of the distribution network is imported into the database of the automation system of this disclosure in the entirety thereof, thus considering both the automated (AUTO managed Field) portions as well as the non-automated (Non AUTO Field) portions of the electrical network. Once the topology has been imported, the management of the automation parameters of the peripheral units may occur partly in the first component and partly in the second component (GAM_rt).

[0047] According to an aspect, an operator accesses the first component, selects the route to be automated and the type of automation. This opens a graphic tool with the topological representation of the chosen route from which the user may select the primary cabin upright by entering the relative general parameters. Subsequently, it selects the nodes (secondary cabins) to remotely control and, for each thereof, depending on the devices present, through configuration sheets, it establishes the automation parameters. Once the parameters associated with each element have been set, the user may save the configuration. Conveniently, after such saving, other changes and new savings may be made. Finally, the operator will send the desired configuration to the second component, and, following the database update, the latter will be transmitted to the UPs.

[0048] The first component will conveniently be provided with a section (Decoupling) in which the business services functional to data recovery and business logic updating are developed. In particular, a specific interface (GAM Configurator Solution) will be conveniently provided which will allow the following functions to be performed:

[0049] • Graphical support for the definition of the network to be automated, so as to select the network elements and define the boundaries of the automation;

[0050] • Support for the configuration of non-evolved automations, with precise definition of the elements on which to apply simple automations;

[0051] • Configuration wizard, with possible explanatory aids for the selection of the parameters on each element, provision of limits and choices for individual entries;

[0052] • Configuration saving management, with presentation of the entered configurations, relative status of authorization and dissemination to the second component;

[0053] • Management of the authorization process and of the roles of the operators authorized for the various operations;

[0054] • Dissemination of the parameterization towards the second component.

[0055] By means of a further section (Platform) the parameters and configurations are sent to the second component.

[0056] The second component (GMA_rt) is the component that disseminates the defined automation strategy. The main function thereof, in fact, is to send the automation parameters chosen by the user to the UPs, but also to manage in real time the position of each single automation node so as to redefine the priorities or sequences of intervention following possible updates of the actual status of the network. The second component therefore controls the part of the network relating to the automated UPs, of which it directly reads the variations and the changes of status.

[0057] The automation system of this disclosure will conveniently provide the operator with a graphical interface to allow the operator to configure only what is necessary: the simplified network diagram with the automated nodes, the IP addresses of the RTUs and a limited number of parameters necessary to manage the automation logics. Conveniently, the automation system of this disclosure will present to the central system the virtual RTUs thereof generated as if they were devices compliant with the standard used by the central system, thus hiding any type of complexity from the operator. This set of devices is configured on the central system as if they were usual RTUs compliant with the central system standard.

[0058] The technical steps of the solution implemented by the automation system of this disclosure are structured as follows:

[0059] • A georeferenced topographic diagram of the distribution network of the customer (typically a file) is imported inside the database of the automation system;

[0060] • A user-friendly web interface is accessed, which guides the user when preparing the automations as quickly and easily as possible;

[0061] • A real-time database is generated based on information received from the web interface of the user and the topographic diagram;

[0062] • The automation rules file is created to be sent to the RTUs so that they may be independent when applying the automation rules;

[0063] • Real-time integration with the central system and the automated network occurs without any need to modify the pre-existing central system.

[0064] More specifically, when a fault occurs on a medium voltage transmission line of the electrical network (short circuit or ground fault): a fault detector 5 detects the presence of a fault on the transmission line with four nodes; such fault detector 5 sends a detected fault signal to all equivalent devices installed in the Secondary Cabins 2) of the four nodes, the latter correctly knowing the position thereof within the network, confirm the received message and inhibit the functions thereof.

[0065] Such fault detector 5, remained active, propagates the information relating to the detected fault to the RTU thereof the engaged RTU activates the automation process the peripheral units exchange their respective status signals; the automation unit identifies the peripheral unit (previously engaged Secondary Cabin RTU) upstream of the fault and the peripheral unit (Secondary Cabin RTU) downstream of the fault; the automation unit sends a command signal to the peripheral unit (Secondary Cabin RTU) upstream of the fault to open the switch to which it is connected; the automation unit sends a control signal to the peripheral unit (Secondary Cabin RTU) downstream of the fault to open the switch to which it is connected, thus isolating the faulty network section; the automation unit of each Secondary Cabin 2 involved transmits to the central system the position of the switches and the type of fault (short circuit or ground fault) so that the central control system may inform the operator about the position of the faulty network section. Furthermore, the automation unit downstream of the faulty section sends a control signal to the peripheral unit (Secondary Cabin RTU) of the border node to close the switch to which it is connected, re-powering the network downstream of the fault.

[0066] According to one aspect, the timing of the control signals is established on the basis of the following parameters: ordinal position of the Secondary Cabins 2 in the network; type of switches; status of the protections of the Primary Cabin 1.

[0067] According to an aspect, to define the automation parameters that are used to create the configuration files to be sent to the peripheral units, the following is necessary: o Internal rules and graphical interfaces for the management of the data input by the operator, o Definition of timers and parameters adapted to describe the behavior of the protection in the primary cabin 1, o Definition of automata sequence (ordinal position of the automation within the feeder), o Definition of timers and specific parameters for each automated medium voltage MV line disconnector / switch, o Definition of possible priority orders in the event of the co-presence of multiple maneuvering devices.

[0068] In the event of a variation in the network topology, the automation system of this disclosure generates a message, sends it to the Primary Cabin RTU 1 (CP), which transmits it to the Secondary Cabin RTU 2 (CS).

[0069] By virtue of the automation system of this disclosure, it is possible to discriminate different types of fault: this allows to intervene in different ways depending on the type of network and the type of fault. Furthermore, the central system is not modified since the automation is distributed and no longer centralized: in the event of faults on the line, the central system continues to carry out the activities thereof without having to be in charge of the automation. Since the automation logics are directly connected to the fault detector in the cabin, intervention times are reduced and fault detection accuracy increases, thus reducing the stress on the network (reduced number of attempts to identify the faulty line section).

Claims

CLAIMS1. An electricity distribution network, comprising: at least one high voltage to medium voltage electrical transformation station (1), functionally connected to a high voltage line and to at least one medium voltage line; a plurality of medium voltage to low voltage electrical transformation substations (2), powered by the high voltage to medium voltage electrical transformation station (1) through said medium voltage line; a network automation unit, connected to the high voltage to medium voltage electrical transformation station (1) and to the medium voltage to low voltage electrical transformation substations (2), configured to transmit automation logic instructions and / or automation parameters to the high voltage to medium voltage electrical transformation station (1) and to the medium voltage to low voltage electrical transformation substations (2); and a central control system, functionally connected to the high voltage to medium voltage electrical transformation station (1), to the medium voltage to low voltage electrical transformation substations (2) and to the network automation unit to update in real time a topological scheme of the electricity distribution network and of a present state of operation of the electricity distribution network; wherein said network automation unit is configured to: receive from the central control system information signals representative of said topological scheme of the electricity distribution network and of the present state of operation of the electricity distribution network, execute a first software component, configured to define a central user interface, to allow a user to select at least one medium voltage line to be automated and to select each substation of said medium voltage to low voltage electrical transformation substations (2) connected to the medium voltage line to be automated, as well as to set said respective automation logic instructions and / or said respective automation parameters, execute a second software component, configured to transmit to each substation of said medium voltage to low voltage electrical transformation substations (2) said respective automation logic instructions and / or said respective automation parameters, to receive information on the status of switches and possible alarm signals and to transmit said information on the status of said switches and said possible alarm signals to said central control system, said second software component being integrable with said central control system.

2. An electricity distribution network of claim 1, wherein said first software component is configured to define said central user interface as a graphical interface of the electricity distribution network to be automated.

3. An electricity distribution network according to one of the preceding claims, wherein said high voltage to medium voltage electrical transformation station (1) comprises:- at least one high voltage to medium voltage electric transformer (4),- a plurality of switches each connected to a respective medium voltage line,- at least one protection panel (6) for said at least one medium voltage line,- a primary peripheral unit, connected to each switch and to the network automation unit, configured to: sense current and / or voltage values in said high voltage to medium voltage electrical transformation station (1), transmit said information on the status of said switches and said possible alarm signals to the network automation unit.

4. An electricity distribution network according to one of the preceding claims, wherein each substation of said medium voltage to low voltage electrical transformation substations (2) comprises:- at least one medium voltage to low voltage electric transformer (7), configured to power a plurality of low voltage lines (3),- a respective plurality of switches for said plurality of low voltage lines (3),- a fault detector (5), functionally connected to detect a fault along said medium voltage line,- a secondary peripheral unit, connected to each switch and to the network automation unit, configured to: o sense current and / or voltage values in said medium voltage to low voltage electrical transformation substation (2), o transmit said information on the status of said plurality of switches and said possible alarm signals to the network automation unit, o receive commands from the network automation unit to open / close each switch.

5. A method of controlling an electricity distribution network according to one of the precedingclaims, comprising carrying out the following operations with said network automation unit: receiving information signals, from the central control system, representative of the topological scheme of the electricity distribution network and of the present state of operation of the electricity distribution network, executing a first software component to define a central user interface, to allow a user to select at least one medium voltage line to be automated and to select each substation of said medium voltage to low voltage electrical transformation substations (2) connected to the medium voltage line to be automated, as well as setting the respective automation logic instructions and / or the respective automation parameters, executing a second software component to transmit to each substation of said medium voltage to low voltage electrical transformation substations (2) the respective automation logic instructions and / or the respective automation parameters, to receive the information on the status of said switches and the possible alarm signals and to transmit the information on the status of said switches and the possible alarm signals to said central control unit, said second software component being integrable with said central control system.

6. A method of controlling, according to claim 5, the electricity distribution network as defined in claim 3, comprising performing the following operations with the primary peripheral unit: sensing current and / or voltage values in said high voltage to medium voltage electrical transformation station (1), transmitting information on the status of said switches and possible alarm signals to the network automation unit.

7. A method of controlling, according to claim 5 or 6, an electricity distribution network as defined in claim 4, comprising performing the following operations with the secondary peripheral unit of each medium voltage to low voltage electrical transformation substation (2): sensing current and / or voltage values in said medium voltage to low voltage electrical transformation substation (2), transmitting information on the status of said plurality of switches and possible alarm signals to the network automation unit, receiving commands from the network automation unit to open / close each switch.

8. A computer program loadable into an internal memory of a microprocessor unit, comprising a software code configured to cause the microprocessor unit to perform the operations of the methodof claim 5.

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