Method for Modeling a Network Topology of a Low-Voltage Network

Abstract

A method for modeling a network topology of a subarea of a low-voltage network, wherein the network topology of the subarea of the low-voltage network is dynamically changeable by switching on, over and/or off components and/or by adding or removing components, where the network topology is modeled as a graph with nodes and edges, states valid for all edges of the graph at an initialization time are determined and assigned to the edges as the respective first state instance, with each subsequent change to the network topology, the respective current states valid for the respective edge from a time of the change to the network topology are determined for the edges of the graph, and each edge of the graph is assigned the respective state determined and currently valid from the time of the respective change to the network topology as a respective further state instance together with a timestamp.

Claims

1. A computer-implemented method for modeling a network topology of at least a subarea of a low-voltage network comprising components connected to at least the subarea of the low-voltage network via connecting points, the network topology of at least the subarea of the low-voltage network being changed by at least one of (i) switching on, over, or off components comprising lines and (ii) adding or removing components comprising at least one of operating equipment, consumers and energy generators or energy storage units, the method comprising: modeling the network topology of at least the subarea of the low-voltage network as a graph with nodes and edges, the components connected to at least the subarea of the low-voltage network via connecting points being represented as at least one of edges and edges with an associated start or end node and the connecting points being represented as nodes; determining a state valid at an initialization time for each edge and assigning said determined state to a respective edge as the first state instance; determining a respective current state which is valid for a respective edge of the graph from a time of a respective change to the network topology is determined for each edge of the graph in an event of the respective change to the network topology; and assigning each edge of the graph the respective state determined and currently valid from the time of the respective change to the network topology as a respective further state instance together with a timestamp which indicates the time of the respective change to the network topology.

2. The method as claimed in claim 1, wherein an assignment of respective further state instances with an associated timestamp is reduced to those edges of the graph (104) whose respective current state was changed by the respective change to the network topology in the event of the respective change to the network topology.

3. The method as claimed in claim 1, wherein the respective change to the network topology of at least the subarea of the low-voltage network is combined to form an event.

4. The method as claimed in claim 2, wherein the respective change to the network topology of at least the subarea of the low-voltage network is combined to form an event.

5. The method as claimed in claim 1, wherein the timestamps of the respective state instances assigned to the respective edges in the graph are utilized to derive a network topology of at least the subarea of the low-voltage network which is valid for a specifiable time.

6. The method as claimed in claim 1, wherein the timestamps of the respective state instances assigned to the respective edges in the graph are utilized to determine a list of changes to the network topology of at least the subarea of the low-voltage network for a specifiable period of time.

7. The method as claimed in claim 1, wherein an active state or a deactivated state is assigned to an edge as the respective state instance.

8. The method as claimed in claim 1, wherein connectors of the respective edges to the nodes and state changes to the connectors or the respective edges are taken into account in the graph when the components connected to at least the subarea of the low-voltage network via connecting points are represented as at least one of (i) edges and (ii) edges with an associated start or end node.

9. The method as claimed in claim 1, wherein a direction of an energy flow between the components and the associated connecting points in at least the subarea of the low-voltage network is taken into account (102, 104) when the components connected to at least the subarea of the low-voltage network via connecting points are represented as at least one of (i) edges and (ii) edges with an associated start or end node in the graph.

10. The method as claimed in claim 1, wherein the graph of at least the subarea of the low-voltage network is modeled based on network planning data.

11. The method as claimed in claim 1, wherein the graph of at least the subarea of the low-voltage network is stored and processed in a graph database.

Description

BRIEF DESCRIPTION OF THE DRAWING

[0026] The invention is explained below in an exemplary manner with reference to the accompanying figures, in which:

[0027] FIG. 1 is a schematic exemplary sequence of the method for modeling at least a subarea of a low-voltage network in accordance with the invention;

[0028] FIG. 2 is a schematic and exemplary graph model of an exemplary low-voltage network created according to a modeling step of the method in accordance with the invention;

[0029] FIGS. 3a to 3c are schematic and exemplary modelings of a subarea of the exemplary low-voltage network represented in FIG. 2;

[0030] FIG. 4 is a schematic and exemplary embodiment of the modeling in accordance with the invention of the subarea of the exemplary low-voltage network represented in FIG. 2; and

[0031] FIG. 5 is a schematic and exemplary further variant of the modeling in accordance with the invention of at least a subarea of an exemplary low-voltage network.

DETAILED DESCRIPTION OF THE EXEMPLARY EMBODIMENTS

[0032] FIG. 1 shows, in a schematic manner, an exemplary sequence of the method in accordance with the invention for modeling at least a subarea of a low-voltage network. For this purpose, in a modeling step 101, a (static) network topology of at least a subarea of a low-voltage network, which is, for example, to be monitored or in which, for example, changes are to be analyzed and evaluated together with measurement data from the low-voltage network (for example, measurement data for electric current, voltage and/or power), is modeled as a graph with nodes and edges. A representation of the (static) network topology, i.e. the low-voltage network-subarea or the low-voltage network with its components (for example, consumers, energy feeders, energy generators, energy storage units and operating equipment, such as transformers, and/or lines) and connecting points (for example, busbars, loop boxes, and/or disconnection boxes), as a graph or graph model with edges and nodes uses, for example, network planning data from a corresponding database and/or a corresponding network simulation tool or network planning tool, such as PSS®Sincal.

[0033] In the graph or graph model, which is created in the modeling step 101, components of the low-voltage network are represented as edges or as edges with an associated start or end point and connecting points of the components in the low-voltage network are represented as nodes. The edges represent, for example, operating equipment of the low-voltage network, such as transformers in transformer stations, lines, and/or cables. Components, such as consumers (for example, single or multiple households, and/or buildings), energy generators connected to the network (for example, a PV power station, and/or small wind turbine), energy feeders from a higher-level network, etc., which, for example, form a boundary or an end point of the low-voltage network, are, for example, represented as an edge with an associated start or end point. Finished modeling of the (static) network topology of at least the subarea of the low-voltage network as a graph can then, for example, be stored in a graph database, such as Neo4j, and subsequently further processed.

[0034] In an initialization step 102, a state of the edge or the component represented by the edge that is valid at an initialization time is first determined for each edge of the graph. Here, an edge can, for example, have an active state or a deactivated state. The state of the respective edge determined at the initialization time is assigned to the respective edge as the first state instance or initialization instance. This first state instance of the graph edges can, for example, be provided with a timestamp in which the initialization time is held. Furthermore, the initialization instances of all graph edges can be combined to form a first event, i.e., the initialization event. This initialization event represents an initial network topology of at least the subarea of the low-voltage network.

[0035] Subsequently, in a determination step 103, in the event of a change to the network topology of at least the subarea of the low-voltage network, a respective current state that is valid for the respective edge of the graph from a time of the change to the network topology is determined for each edge of the graph. Changes to the network topology occur if, for example, one or more edges change their respective current state. This means, for example, that a line is switched on or off by a circuit in the network, or a fault or interruption occurs, for example, in a line as a result of which another deactivated line must be switched on. This means that the current state of the respective component or the associated edge in the graph changes from a new state that is currently valid after the topology change (for example, from the state “active” to the state “deactivated”, or, for example, from the state “deactivated” to the state “active”). Edges that are not affected by the topology change have the same state after the topology change as before. This means that an active edge remains active even after the topology change, or a deactivated edge remains deactivated even after the topology change, where the current state before the topology change thus remains identical to the currently valid state after the topology change.

[0036] The new and currently valid states of the edges (for example, active or deactivated) after the topology change from the determination step 103 are then assigned to the edges in the graph as further state instances in an assignment step 104. Here, the further state instances are provided with a timestamp indicating the time of the change to the network topology depicted by the state instances. The further state instances can then be combined on the basis of their time stamp to form a new event representing a network topology of at least the subarea of the low-voltage network represented by the graph that is valid at the time indicated in the timestamp.

[0037] The determination step 103 and the assignment step 104 must be run through for each further topology change of the low-voltage network that is to be processed in the modeling. This means that, in the case of a plurality of topology changes, in addition to the initialization state instance, a further state instance with an associated timestamp is, for example, assigned to the edges in the graph model for each topology change, where the timestamp always indicates the time of the respective topology change.

[0038] For purposes of simplicity, in the assignment step 104, a further state instance together with a corresponding timestamp can only be assigned to the edges for which the respective topology change has also led to a state change, i.e., for example, from “active” to “deactivated”, or from “deactivated” to “active”. Thus, only edges affected by the respective topology change receive a new further state instance with a corresponding timestamp. Thus, edges that, for example, never change their state due to topology changes, for example, only have the initialization instance. For example, the state instances of the edges that have the respective most recent time stamp are then combined for the corresponding event.

[0039] In a derivation step 105, for example, a network management system or network monitoring system then accesses the graph model which, after the execution of the method for modeling the network topology, in addition to the static network topology of at least the subarea of the low-voltage network, also comprises the dynamic network topology changes. A network topology valid for a specifiable time can now be derived based on the timestamps of the state instances assigned to the edges represented in the graph. Here, for example, the event or state instances of the edges selected are those whose timestamp or timestamps match the prespecified time or, in a time series, is/are the shortest before the prespecified time. This means that the state instances of the edges selected are those which, in a time series, are the shortest in the past before the prespecified time. Furthermore, it is possible that, in derivation step 105, a list of changes to the network topology for a specifiable period of time is determined based on the timestamps of the state instances of the edges or on the basis of the time stamp of the associated event. This list then comprises all events whose timestamps are comprised by the prespecified period of time.

[0040] FIG. 2 shows a schematic exemplary representation of a graph of a network topology of an exemplary low-voltage network NV, which was created with the modeling step 101 of the method in accordance with the invention for modeling a network topology. Here, the low-voltage network NV is supplied from a higher-level network (for example, a medium-voltage network) via an energy feeder ES. The energy fed in is brought to the corresponding voltage level via a transformer station TS or the transformer located there and distributed via a busbar N4 and, for example, via a loop box N5 and line strands K4, K5, K7 to two exemplary consumers V1, V2 connected, for example, to the low-voltage network NV via so-called disconnection boxes N6, N7. An energy generator EE (for example, PV power station) is, for example, connected to the low-voltage network NV on a further line strand K10, which links the busbar N4 to a further connecting point N10.

[0041] In the modeling step 101, a graph or graph model in which the components ES, TS, V1, V2, EE and lines K3, K4, K5, K6, K7, K10 are represented as edges K3, K4, K5, K6, K7, K10 or edges K1, K8, K9, K11 with an associated start or end node N1, N8, N9, N11 and the connecting points N4, N5, N6, N7, N10 are represented as nodes N4, N5, N6, N7, N10 is modeled from the exemplary low-voltage network NV with its components ES, TS, V1, V2, EE, lines K3, K4, K5, K6, K7, K10 and connecting points N4, N5, N6, N7, N10.

[0042] The energy feeder ES forms, for example, a boundary of the low-voltage network. As a result, this is, for example, represented as a start node N1 with an associated edge K1 to which, for example, the respective state instances are then assigned in the further method. The energy feeder ES is, for example, linked via a connecting point N2 to the transformer station TS or to the transformer, where the transformer station TS or the transformer has a further connecting point N3 on the low-voltage side. Therefore, the two connecting points N2, N3 of the transformer station TS are represented as nodes N2, N3 in the graph and the transformer of the transformer station TS, which can assume different states, for example by means of circuits, is modeled as edge K2. The line K3, which links the transformer station TS to the busbar N4, is again represented as edge K3.

[0043] The busbar N4 at which a plurality of line strands K3, K4, K10 meet or which forms the connecting point N4 for these line strands K3, K4, K10 is modeled as node N4. The lines K4, K10 leading away from the busbar N4 or the node N4 are again represented as edges K4, K10. Here, for example, a first line K4 or edge K4 leading away from the busbar N4 or the node N4 leads to a loop box N5, which is again represented as node N5. A second line K10 or edge K10 leading away from the node N4 leads to a connecting point N10 modeled as node N10. The energy generator EE is, for example, connected to the network at this connecting point N10. The energy generator EE represents, for example, an end point for the line strand K10. As a result, the energy generator EE is modeled as edge K11 with the associated end node N11 in the graph. The edge K11 can, for example, subsequently then be assigned different states of the energy generator EE.

[0044] Connecting points or so-called disconnection boxes N6, N7 for the consumers V1, V2 (for example, household, and/or building) are connected to the loop box K5 represented as node K5, for example, via two exemplary line strands K5, K7, where the line strands K5, K7 are again represented as edges K5, K7 and the connecting points N6, N7 are represented as nodes N6, N7. The two consumers V1, V2 connected to the nodes N6, N7 again represent end points for the respective line strands K5, K7 and are therefore modeled as edges K8, K9 with the associated end node N8, N9. Furthermore, for example, a line, which is modeled as the edge K6 is provided between the connecting points N6, N7. This line K6 is, for example, only activated in the event of a fault or is usually deactivated. Accordingly, the corresponding edge is shown as a dashed line in FIG. 2.

[0045] The following explains the further steps of the method for modeling, i.e., the initialization step 102, the determination step 103, the assignment step 104 and an exemplary derivation of a current network topology from the graph model by means of derivation step 105, with reference to FIGS. 3a, 3b and 3c, where, for purposes of simplicity/clarity, FIGS. 3a to 3c only show a subarea TB of the exemplary graph of the low-voltage network represented in FIG. 2. This subarea TB comprises the busbar or the node K4 with the first outgoing line strand K4 or the edge K4, the loop box or the node N5 with the lines or edges K5, K7, which lead to the connecting points or nodes N6, N7, the linking line or edge K6 between the nodes N6, N7 and the two connected consumers V1, V2, which are represented as edges K8, K9 with the associated end nodes N8, N9.

[0046] FIG. 3a now shows a schematic and exemplary graph of the subarea TB after the initialization step 102. For this purpose, in the initialization step 102, a current state of the respective edges K4, K5, K6, K7 and the consumer edges K8, K9 at the initialization time t0 is determined. Here, for example, all edges K4, K5, K7, K8, K9, except for the edge K6, which links the nodes N6 and N7, have, for example, an active state. The edge K6 between the nodes N6, N7 is, for example, deactivated and therefore shown as a dashed line. The state determined at the initialization time t0 is then assigned to the respective edges K4, K5, K6, K7, K8, K9 as the first state instance or as an initialization instance S40(t0), S50(t0), S60(t0), S70(t0), S80(t0) and S90(t0) together with a timestamp t0. Here, the timestamp t0 represents the initialization time to. Furthermore, the initialization instances S40(t0), S50(t0), S60(t0), S70(t0), S80(t0) and S90(t0) of all graph edges K4, K5, K6, K7, K8, K9 can be combined to form a first event (the “initialization event”) which represents a network topology of the subarea TB at the initialization time t0.

[0047] FIG. 3b now shows an exemplary and schematic implementation of the determination step 103 and the assignment step 104 in the event of an exemplary change to the network topology of the subarea TB of the low-voltage network under consideration, which, for example, occurs or is performed at a time t1. Here, at the time t1, the line K7 is, for example, deactivated by a fault and, for example, the line K6 is activated in order to ensure a further power supply to the second consumer V2. The line or edge K6, which is now active due to the topology change, is therefore represented as a solid line. The line or edge K7, which was, for example, deactivated by a failure or shutdown at the time t1, is now represented as a dashed line.

[0048] The new and currently valid states of the edges K4, K5, K6, K7, K8, K9 (for example, active or deactivated) after the topology change, which were determined in the determination step 103, are then, in the assignment step 104, assigned to the edges K4, K5, K6, K7, K8, K9 in the graph of the subarea TB as further state instances S41(t1), S51(t1), S61(t1), S71(t1), S81(t1) and S91(t1). Here, the further state instances S41(t1), S51(t1), S61(t1), S71(t1), S81(t1) and S91(t1) are provided with a timestamp t1, which indicates the time t1 of the change to the network topology. The further state instances S41(t1), S51(t1), S61(t1), S71(t1), S81(t1) and S91(t1) can then be combined based on their time stamp t1 to form a new event representing the network topology of at least the subarea TB of the low-voltage network represented by the graph valid at the time t1 indicated in the timestamp t1.

[0049] FIG. 3c shows an exemplary network topology of the exemplary subarea, which can be determined from the graph model, for example, for the time t1, as currently valid network topology in the derivation step 105. Here, the state instances S41(t1), S51(t1), S61(t1), S71(t1), S81(t1) and S91(t1) of the edges with the timestamp t1 for the time t1 or the corresponding event can, for example, be accessed in order to determine the currently valid network topology of the subarea TB at the time t1. The currently valid network topology of the subarea TB again shows the busbar N4 or the node N4 with the connected line or edge K4 leading to the loop box or node N5. Furthermore, it can be seen from the network topology of the subarea TB that the first outgoing line K5 or edge K5 from the loop box N5 is active and supplies the first consumer V1 with energy via the connecting point N6. Furthermore, it can also be identified that the second outgoing line K7 or edge K7 from the loop box N5 is deactivated and the second consumer V2 is now supplied with energy via the first line K5, the connecting point N6 and the line K6 between the connecting points N6, N7, since the line K6 or edge K6 has been activated.

[0050] FIG. 4 shows an exemplary embodiment of the implementation of the assignment step 104 in the modeling in accordance with the invention of the subarea TB of the exemplary low-voltage network NV represented in FIG. 2 via which a number of state instances assigned to the edges K4, K5, K6, K7, K8, K9 can be reduced. Similarly to FIG. 3a, in the initialization step 102, the edges K4, K5, K6, K7, K8, K9 are again assigned the first state instances or initialization instances 540(t0), S50(t0), S60(t0), S70(t0), S80(t0) and S90(t0) together with a timestamp to. For the sake of simplicity, however, in the assignment step 104, a further state instance S61(t1), S71 (t1) together with a corresponding timestamp t1 is only assigned to the edges K6, K7 in which the topology change at the time t1 has also led to a state change, i.e., for example, from “active” to “deactivated”, or from “deactivated” to “active”. Thus, this means that the edge K6 between the nodes N6, N7 is assigned a further state instance S61(t1) in addition to the initialization instance S60(t0), since these were switched to active by the topology change at the time t1. Furthermore, the edge K7 between the nodes N5, N7 is assigned a further state instance S71(t1) in addition to the initialization instance S70(t0), since this had failed due to a topology change at the time t1, for example, due to a fault, or had been deactivated due to a circuit. The corresponding event representing the topology change of the subarea TB for the time t1 then, for example, combines the edges K6, K7, the state instance S61(t1), S71(t1) with the timestamp t1 and, for the remaining edges K4, K5, K8, K9, the initialization instances S40(t0), S50(t0), S80(t0) and S90(t0) with the timestamp t0 representing the respective most current state instance for the remaining edges K4, K5, K8, K9.

[0051] FIG. 5 represents an exemplary subarea of a low-voltage network. This subarea has, for example, three exemplary nodes N51, N52, N53. In this context, the first node N51 can, for example, be a busbar, which is linked to a second node N52 (for example a loop box) via a first line or edge K51. A third node N53, such as an end node of a consumer is, for example, connected to the second node N52 or the loop box via a second line or edge K52. Here, the first and the second node N51, N52 have connectors or terminals A50, A51, A52, A53. Here, a first end of the line or edge K51 is connected to a first connector A51 of the first nodes N51. The second end of the line or edge K51 is connected to a first connector A52 of the second node N52. The consumer (represented as a second edge K52 and end node N53) is, for example, connected to the second connector A53 of the second node N52. A second connector A50 of the first node N51 is only shown for purposes of completeness and can, for example, represent a connector for a link to a transformer station.

[0052] In the exemplary embodiment of the method for modeling a network topology of a low-voltage network represented in FIG. 5, instead of edges K51, K521 and their respective state changes, due to topology changes, the connectors A51, A52, A53 or the terminals A51, A52, A53 and thus the corresponding ends of the lines K51, K52 are considered. In this context, changes at the level of the terminals A51, A52, A53 are acquired by creating a state instance S510, S511, S512, S520, S521, S522 for each change to the terminals in the graph model and assigning it to the respective terminal A51, A52. Based on this, each change in the state of a connector or a terminal A51, A52, A53 over a period of time under consideration can be represented and stored in the graph model. Terminals, such as the second terminal A53 of the second node N52, for which no state changes occur over the period of time under consideration, are not assigned a state instance.

[0053] In these state instances S510, S511, S512, S520, S521, S522, states, such as “active”, and/or “deactivated”, of the terminal A51, A52 and at least the time t510, t511, t512, t520, t521, t522 at which a change to the respective state “active”, and/or “deactivated”, has occurred, can, for example, be held as information. Depending upon the application, additional information can be added to these state instances S510, S511, S512, S520, S521, S522, such as details of a technician who has executed a state change or the quality of information (for example, whether the respective state was already registered in a database at the indicated time t510, t511, t512, t520, t521, t522 or whether the state change was, for example, executed by the technician on site).

[0054] Based on the exemplary embodiment illustrated in FIG. 5, the respective valid state of the respective connector or terminal A51, A52, A53 and thus a correspondingly valid network topology can likewise be extracted by a corresponding query at any time in the past. For example, a corresponding query can be used to query all terminals A51, A52, A53 that are active at a prespecified time and thus to infer a network topology that was current at the prespecified time. Furthermore, in the exemplary modeling embodiment represented in FIG. 5, it is also, for example, possible to take account of a direction of the energy flow between the components or between the connectors A51, A52, A53 in the modeled low-voltage network.

[0055] Thus, while there have been shown, described and pointed out fundamental novel features of the invention as applied to a preferred embodiment thereof, it will be understood that various omissions and substitutions and changes in the form and details of the methods described and the devices illustrated, and in their operation, may be made by those skilled in the art without departing from the spirit of the invention. For example, it is expressly intended that all combinations of those elements and/or method steps which perform substantially the same function in substantially the same way to achieve the same results are within the scope of the invention. Moreover, it should be recognized that structures and/or elements and/or method steps shown and/or described in connection with any disclosed form or embodiment of the invention may be incorporated in any other disclosed or described or suggested form or embodiment as a general matter of design choice. It is the intention, therefore, to be limited only as indicated by the scope of the claims appended hereto.