EP2845287A1

EP2845287A1 - Method and device for monitoring an energy feed-in point of an energy supply network

Info

Publication number: EP2845287A1
Application number: EP12735831.5A
Authority: EP
Inventors: Stefan LANGEMEYER; Johannes Reinschke
Original assignee: Siemens AG
Current assignee: Siemens AG
Priority date: 2012-07-05
Filing date: 2012-07-05
Publication date: 2015-03-11
Also published as: RU2015103726A; BR112014032845A2; IN2014DN10663A; CN104396110A; WO2014005642A1; CN104396110B; US20150185750A1; RU2608181C2

Abstract

The invention describes a method for monitoring an energy feed-in point (ESP) of an energy supply network (EVN), particularly in the low voltage range, a number of first and second nodes (K11, K12, K13, K2) being connected or connectable to the energy feed-in point, the respective nodes (K11, K12, K13, K2) being an energy producer, an energy consumer or a prosumer. In the method according to the invention, an actual current which represents the current consumption or current output is detected at the energy feed-in point (ESP) by a measuring and monitoring device. A piece of current information (SI) received from one of the first nodes (K11, K12, K13), which represents an intended and/or a maximum possible current consumption or output of the first node (K11, K12, K13), is processed by checking whether a current value in the piece of current information (SI) fulfils a predetermined criterion in respect of a possible current value (MW) of the energy feed-in point (ESP). The possible current value (MW) is determined by a differential formed from the predetermined maximum current of the energy feed-in point (ESP) and the actual current. Finally, depending on whether the criterion at the first node (K11, K12, K13) is fulfilled or not, a message is transferred which confirms or denies the current consumption or output to the first node (K11, K12, K13).

Description

description

Method and device for monitoring an energy supply point of a power supply network

The invention relates to a method and a device for monitoring an energy supply point of a power supply network, in particular in the low-voltage range. A number of first and second nodes can be connected or connectable to the energy supply point, wherein a respective node is a power generator, an energy consumer or a prosumer.

In the present description, first nodes are those nodes which have communication means and can communicate with a device carrying out the method. Second nodes are those nodes which have no means of communication and therefore can not communicate with the device executing the method.

A prosumer is understood to mean a component that can both generate energy and feed it into the energy supply network as well as consume energy and absorb it from the energy supply network. An example of this is, for example, electrically powered motor vehicles, which draw energy from the energy supply network for charging their battery or can feed energy from their storage into the energy supply network at peak load times.

Via a (central) energy supply point, a plurality of electrical loads or sources can be connected to the energy supply network. Loads and sources represent nodes in the sense of the invention. For example, several charging stations can be used for such an energy infeed point

Electric vehicles and / or photovoltaic systems and / or generators to be connected. As a rule, not all nodes simultaneously with maximum power consumption or abgäbe ak- tive, the energy supply point of the power grid is often designed so that the summed, maximum possible power consumption or output (or current consumption or output) of all nodes is greater than the maximum possible or permissible power (or current) on Energieeinspeisepunkt. A protective device at the energy supply point, eg in the form of a fuse or protection, ensures that the maximum permissible power at the energy supply point can not be exceeded. The protection device triggers at the latest when a predetermined maximum current is exceeded, interrupting the electrical connection of the nodes connected to the energy supply point to the energy supply network. In order to avoid a sudden triggering of the protective device, in the simplest case individual nodes which are connected to the energy supply point can be designed such that the maximum current consumption or discharge of all nodes basically remains below the predetermined maximum current of the energy supply point. In this case, no control is required. However, such a design is unfavorable for cost reasons.

It is also possible to provide communication between a monitoring device at the power supply point and the node connected to it for controlling the power flow. Such a procedure proves to be difficult if the nodes and / or the monitoring device at the power feed point are in the sphere of different operators. Here, a smooth communication must be ensured in order to avoid an overload due to the communication between the monitoring device and the node. It is an object of the present invention to provide a method and an apparatus for monitoring an energy supply point of a power supply network, with which with high reliability an overload case at the energy supply point can be avoided, but at the same time the system should be able to operate as close to the predetermined maximum current of the Energieeinspeisepunkts.

This object is achieved by a method according to the features of claim 1 and a device according to the features of claim 14. Advantageous embodiments will be apparent from the dependent claims.

The invention provides a method for monitoring a power feed point of a power grid, wherein a number of first and second nodes are connected or connectable to the power feed point, wherein a respective node is a power generator, an energy consumer or a prosumer. In particular, the energy supply network is an energy supply network in the low-voltage range. The voltages for a single-phase and three-phase network vary from country to country. In Germany, the voltage is 230 V for a single-phase network and 400 V for a three-phase network. In other countries, other voltage values are sometimes selected.

In the method, the following steps are carried out: a) At the energy infeed point, an actual current representing the current consumption or output is detected by a measuring and monitoring device.

b) A current information obtained from a first node representing an intended and / or a maximum possible current consumption or output of the first node is processed by checking whether a current value of the current information is a predetermined criterion with respect to a possible current value of the current information Energieeinspeisepunkts met.

c) The possible current value is determined by a difference formation from the predetermined maximum current of the energy supply point and the actual current. d) Finally, depending on the fulfillment or

Not fulfilling the criterion to the first node transmit a message which the first node the

Current consumption or surrender confirms or refuses.

The invention further provides a device for monitoring an energy supply point of a power supply network, in particular in the low-voltage range, wherein a number of first and second nodes is connected or connectable to the energy supply point, wherein a respective

Node is an energy producer, an energy consumer or a prosumer. The device comprises a measuring and monitoring device for measuring an actual current representing the current input or output at the energy supply point. A communication device is provided for exchanging data with the first node. A computing unit is used for processing a current information obtained from one of the first nodes, which represents an intended and / or a maximum possible current consumption or output of the first node. It is verifiable by the arithmetic unit, whether a current value of the current information meets a predetermined criterion with respect to a possible current value of the Energieeinspeisepunkts. In this case, the possible current value can be determined by the arithmetic unit by subtraction of the predetermined maximum current of the energy supply point and the actual current. Depending on the fulfillment or non-fulfillment of the criterion, a message can be transmitted to the first node by the communication device, which message confirms or rejects the power consumption or output to the first node.

The proposed procedure allows a dynamic adaptation of the maximum power / power consumption or output at the power supply point. As a result, preventive impending overloads, but also bottlenecks can be detected and avoided. The procedure makes use of the fact that in the future some of the electricity purchasers and / or suppliers have the possibility of using a device for energy input. sepunkt to communicate. The purpose of the communication is merely to confirm or reject the current consumption or output as a function of the current state on the basis of the metrological detection of the actual current that is being carried out on a continuous basis for individual nodes that wish to connect to the energy supply point. This means that the nodes ask at the energy infeed point whether their intended power input or output is possible. On the basis of the measured actual current, the power supply point decides whether the requesting node can electrically connect to the energy infeed point or not.

Instead of the current consideration could also be a performance consideration. If in the following description of the processing of a current is mentioned, could also take place a consideration of the performance instead.

In contrast to technically more complex solutions from the prior art, no control of individual nodes takes place through the energy infeed point or the device monitoring the energy infeed point. The nodes merely receive information as to whether and, if so, in what amount they can receive or deliver electricity. To what extent the nodes implement this information is not influenced by the method or the device. As a result, only a small exchange of data between the device and the requesting node is required. This makes it possible, in particular, for such components, which originate from different manufacturers or find themselves in the sphere of different operators, to communicate with one another. Elaborate, proprietary communication protocols are dispensable.

The procedure ensures that at least the first nodes can not cause an overload case. At the same time, however, it is possible to get closer to the load limits of the power supply point while reducing the number of overload power cuts. In addition, as will become apparent from the further description, it is also possible to connect those nodes to the energy supply point which can not participate in the communication with the device. The consideration of the energy drawn or supplied by these second nodes from the energy supply point is implicitly effected by measuring the actual current on the one hand and the knowledge of the first node connected to the energy supply point and the maximum current reference or output known from previous communication ,

In an expedient embodiment, the criterion is satisfied if the current value of the current information is smaller than the amount of the possible current value. I want the first

Node relate current from the energy supply point, so this indicates by means of the current information a current value, which he wants to relate. If this current value is smaller than a difference value determined from the difference between the predetermined maximum current and the actual current, then the first node can electrically connect to the energy supply point without an overload condition occurring.

On the other hand, the criterion is not satisfied if the current value of the current information is greater than the amount of the possible current value. In this case, the power feed point is already operating close to or at its load limit. The difference value between the predetermined maximum current and the measured actual current is already so small that the reference of a further current, as transmitted by the current value of the current information, would exceed the maximum current at the energy supply point after electrical connection. This would lead to an undesirable overload case. The above-described steps a) to d) are expediently run through separately for each first node that wishes to receive or deliver current. This allows the device implementing the method of the energy supply For each first node, it decides whether or not it can connect to the energy infeed point. Thereby, the communication between the first node and the device can be restricted to the exchange of only two messages (a request of the first node and a response of the device to the first node). In addition, the dynamics of the current reference or the current output by the energy supply point monitoring device can be kept low.

In order to be able to address individual first nodes in the event of impending overload in order to reduce their current consumption or output, provision is made for the current information to be supplied together with an identifier of the first node. This can be done for example in a local memory of the device performing the method. Alternatively, a central memory of the energy supply network could also be used, in which case the information mentioned must be transmitted to a central processing unit of the central storage.

The current information comprises either a current value measured by the first node or a current value stored in the first node or information representing the current value, wherein in the latter case a computing unit of the energy supply point can close the information on the current value. Such information could, for example, be a type designation of the node which is directly linked to a connected value. For example, a database may be provided for this purpose in which the connection values of components from different manufacturers are stored. A corresponding information can then be used to determine the regularly occurring during operation power value.

In the message which confirms or rejects the first node the current consumption or Abgabäbe, is transmitted a maximum allowable amount of power consumption or Abgäbe, where at the maximum allowable height is less than or equal to the current value contained in the current information. This embodiment allows the device executing the method not only to confirm or reject a requested current value with only "yes" or "no", but also to transmit a current level deviating from the one in the request of the first node as the maximum allowable current value. If, for example, the first node asks for a current of 50 A, the device can transmit a current value of 25 A to the first node as the maximum allowable current. The first node can then decide for itself whether he wants to carry out the removal of electricity in the amount of 25 A or not. Likewise, a factor can be transmitted in response. For example, "0.6" or "1.3" in response to the requested current of 50A means that 30A (ie, 0.6 times) and 65A (ie, 1.3 times ) may be transferred.

It is further contemplated that an electrical connection of the Energieeinspeisepunkts is separated to the power grid when the measured actual current reaches or exceeds the maximum current. This may be the case, for example, if too large a number of second nodes, which do not communicate with the device carrying out the method with respect to a current input or output, are connected to the energy supply point.

Likewise, an overload case can occur if, according to a further embodiment, a message is transmitted to individual or all first nodes to reduce or terminate the power consumption or output when the actual current has reached a current threshold which is less than or equal to the predetermined maximum Maximum current is. Since the first node can automatically decide on such a message, whether it reduces or terminates the power consumption or Abgabäbe, it can come to disregard the request for the mentioned overload case. In one embodiment, it is possible to transmit the above message for reducing or terminating the power consumption or output as a broadcast message to the first nodes. On the other hand, the communication as to whether a node is allowed to connect to the power supply point for power input or output is done individually.

According to a further embodiment, it is checked whether, in the course of time, a, in particular approximately constant, deviation between the difference obtained from the current information

Current value and a measured by the arithmetic unit actual current value is present when the first node after the message, which confirms the first node, the current consumption or Abgabäbe or rejects, in accordance with the specification of the Nach- rheingest receives or delivers power, the arithmetic unit at a deviation determined above the predetermined barrier replaces the current information associated with the first node with a current information corrected in accordance with the actual current value determined by the arithmetic unit. Such discrepancies can occur, for example, due to the dynamics of the operation of the first node. Likewise, however, such discrepancies can also be efficiency-related. For example, the first node may only perform at a much lower efficiency, e.g. due to external circumstances, the actual current consumption or output may deviate from the previously agreed current value. With such a deviation, the device executing the method is monitored and documented in a memory in order to have an exactly available "remaining flow quantity" for further first nodes.

On the current consumption or Abgabäbe of the totality of the second node, which are not capable of message transmission or message reception, from the difference between see the actual current and the sum of the current information of the first node, which absorb or deliver power closed. As a result, the statistically fluctuating current values of the second nodes can be determined. From the statistics of the fluctuating current value and the measured actual current value of all second nodes can be determined which maximum current value can be released for the sum of all first nodes. The current values of all second nodes can be determined from the difference of the actual current value and the current values stored in the memory for all registered first nodes.

It can furthermore be provided that the maximum current of the energy supply point is predetermined by a higher-level unit of the energy supply network.

The device according to the invention has, via the components mentioned above, a protective device by means of which an electrical connection to the energy supply network can be separated if the actual current measured by the measuring device reaches or exceeds the maximum current.

In addition, the device has further means for

Carrying out the method described above.

The invention will be explained in more detail below with reference to an embodiment in the drawing. Show it:

1 is a schematic representation of a device according to the invention for monitoring a Energieeinspeisepunkts a power supply network to which a plurality of nodes are connected, and

2 is a flowchart illustrating the procedure of the method according to the invention.

1 shows a schematic representation of a device according to the invention for monitoring an energy supply point ESP of a power supply network EVN. The device represents a protection device SG, which can be regarded as a combination of a power monitoring device and a protection switch. The guard SG is arranged between the power supply point ESP and the power supply network EVN. For example only, the line between the protective device SG and the power supply point ESP is formed in three phases, which are supplied to the energy supply point ESP nodes KU, K12, K13 and K2, for example, with a voltage of 400 V. Likewise, the lines connecting the nodes KU, K12, K13, K2 with the protective device SG could be single-phase. In this case, the nodes KU, K12, K13, K2 would be supplied with a supply voltage of 230 V, for example. The specified voltage values apply to a low-voltage power supply network in Germany. In other countries, the voltages of a three-phase and a single-phase power supply network are partly chosen differently in a manner known to those skilled in the art.

The protective device SG comprises a circuit breaker SV, a communication device KOM, a measuring device ME and a computing unit RE. If in the present description of a circuit breaker SV is mentioned, this can be understood by a controlled switch, but also a fuse or a contactor. Generally come as

Circuit breaker such components into consideration, which at a current flowing through the circuit breaker SV current exceeds a predetermined maximum current, disconnect the electrical connection of the Energieeinspeisepunkts to the power supply network EVN.

The task of the measuring unit ME is to detect the current flowing through the circuit breaker SV (actual current). This corresponds to the energy input point at the power supply point by current consumption or Abgäbe the nodes KU, K12, K13, K2 flowing stream. If the actual current exceeds the predetermined maximum current, then the circuit breaker SV triggers either independently or disconnects, controlled by the arithmetic unit RE, the connection between the energy supply network EVN and the energy supply point ESP. The communication device KOM is set up to communicate with the first node KU, K12, K13. The first nodes have corresponding communication means (not shown). By contrast, the node K2 represents, for example, a second node which has no communication means and therefore can not perform the communication described below. The second node K2 could also be designed in such a way that it has communication means which, however, are not suitable for communicating with the communication device KOM of the protection device SG.

The communication between the protection device SG and the first node KU, K12, K13 may optionally be circuit-based or wireless. The communication channel is indicated schematically in the figure by L2.

Advantageously, the communication between the protection device SG and the first node KU, K12, K13 is based on an open standard, such as a Powerline Communication (PLC), WiFi or ZigBee. Preferably, a communication via PLC takes place, in which case the power lines can be used for the transmission of data signals. The use of an open standard is expedient, since the protection device SG on the one side and the first nodes KU, K12, K13 connected thereto on the other side may belong to different owners or operators, of different types or may be provided by different manufacturers. Typically, the protection device SG is operated by the operator of the power supply network EVN or is in its sovereignty. By contrast, the first nodes KU, K12, K13 communicating with the protection device via the communication channel L2 are frequently in the hands of customers of the operator of the energy supply network EVN. The first and second nodes KU, K12, K13, K2 are, for example, either energy producers (for example a photovoltaic system), energy consumers (for example a battery of an electric vehicle to be charged) or a so-called prosumer. A prosumer is a component that consumes energy but can also generate energy and feed it into the power grid. For example, the battery of an electrically operated vehicle can also be used as a source, for example for reducing short-term peak loads.

In addition, via a schematically indicated communication channel LI, which may be wired or wireless, the protection device SG can optionally communicate with a control room (not shown) of the energy supply network EVN. By way of example, the predetermined maximum current flowing via the energy supply point ESP can be preset or changed via this communication channel LI. The arithmetic unit RE processes the actual current detected by the measuring device ME and the information exchanged in the context of a communication.

The sequence of the method for monitoring the energy input point ESP is explained in more detail below with reference to FIG. 2. The procedure assumes that the first nodes KU, K12, K13, which have communication means for exchanging data with the communication device KOM of the protection device SG, at least before their activation, i. Before taking or giving off power, ask the guard SG how much power they can or may transmit.

In the sequence shown in FIG. 2, the first nodes KU and K12 as well as the second node K2 are shown by way of example in addition to the protective device SG. The flow of communication takes place in Fig. 2 in chronological order from top to bottom. The first node KU, an energy consumer, would like to draw a current of, for example, 50A. The exemplified current value of 50 A is transmitted as current information SI in a message R (SI_K11) to the protection device SG. The current value may correspond to a nominal or maximum current value of the node KU. Likewise, the current value transmitted to the protection device SG in the message R (SI_K11) can be lower than the nominal or maximum current value, for example because the operation of the first node KU can or should be carried out with this lower current.

The protection device SG (ie its arithmetic unit RE) now performs a check as to whether the current value transmitted in the message R (SI_K11) can be released to the first node KU. For this purpose, a difference is first determined from the predetermined maximum current, eg 1000 A, of the energy supply point ESP and the measured actual current at the present time. For example, the actual current current is 800 A, so that until the occurrence of an overload case, a current reference in the amount of 200 A is possible. The release of the current consumption by the first node KU, since the possible current (200 A) is greater than the requested current value (50 A), take place without the overload case occurs. In a response A (MW_K11) of the protection device SG to the first node KU, therefore, the requested current of 50 A is released. The release can be done in the simplest variant by a binary information which corresponds to a "yes" or a "no". Likewise, the maximum current obtainable by the requesting first node KU can be transmitted, in this case 50 A. Due to the positive confirmation, the setting of a current consumption, SCD1, is effected by the first node KU. At the same time, the protection device SG stores the current value (50 A) requested by the first node KU or released by the protection device in conjunction with an identifier of the first node KU. In the further course of the process described above is also carried out by the first node K12, for example, would like to obtain current in the amount of 100 A. The current value is transmitted as current information SI of the first node K12 in the detection R (SI_K12) to the protective device SG. According to the test described above, a residual current of 150 A remains until the overload occurs. Since the requested current level is smaller than the difference value of maximum current and actual current, the request of the first node K12 can be granted. The protection device SG therefore transmits in a message A (MW_K12) the current value MW = 100 A as a possible current. At the same time saves the

Guard SG the requested by the first node K12 or released by the protection device current value (100 A) in conjunction with an identifier of the first node K12. Subsequently, the first node K12 sets a current consumption of 100 A.

Instead of transmitting a current value in the current information, a value representing the current value could also be used

Information from the requesting first node KU, K12 are transmitted to the protection device SG. For example, a manufacturer and type designation of the first node KU, K12 could be transmitted in the stream information. From a table which is stored, for example, locally in the protection device SG, an assignment of this information to a requested current value, for example a rated current, could then take place. The protection device SG checks by analyzing the time course of the actual current, whether the requested by the first node KU, K12 current values are plausible or if there are deviations. In the case of systematic deviations, the protection device can replace the current information assigned to the relevant node by the determined current value. Likewise, correction factors could be used. Specifically, this means that, for example, the first node K12, which has queried current value of 100 A, actually 80 A current refers. As a result, not only 50 A but also 50 A + 20 A = 70 A are actually available as residual current until the overload is reached. Although actually only the current flowing through the power supply point ESP current is determined by the protection device, an assignment to the individual devices is possible, since a sequential communication and connection of individual first node takes place at the Energieeinspeisepunkt. For example, the communication or the answer to the request of another first node can only take place if, after a certain grace period, the difference between a requested current level and the actual current reference of the last added node could be determined. In the flowchart of FIG. 2, the second node K2 now goes to the network in the further course and draws a current in a height initially unknown to the protective device SG. It is assumed that the second node is a plurality of smaller loads. These are operated statis- tically. From the difference between that of the

Protection device SG measured actual current value and the current information transmitted from the first node, the protection device SG determines the statistically fluctuating current value of all the second node K2. From the statistics of the fluctuating current value and the current actual current value of all non-communicating second nodes, the protection device SG determines which maximum current value it can release for the sum of all communicating loads. For example, the time profile of a fluctuating current value that the current value of the second node varies a maximum of ± 50 A, in a time interval in which the first node can be safely switched off. Of the

The current value of the second node is currently, for example, 100 A. This allows the protection device to release up to 850 A current drain or 1050 A backfeed. In the example of the flowchart according to FIG. 2, the additional current reference of the second node K2 causes an imminent overload to be detected, DOTC1. This is done by the evaluation of the actual current value by the protection device SG. Subsequently, the protection device SG transmits a message R1 (RED_K12) targeted to the first node K12 to reduce the power consumption. Since the first nodes KU, K12, K13 are not controlled or regulated by the protection device, the first node KU is free to respond to this request or not. In the present exemplary embodiment, the first node K12 reduces the current consumption by setting a new, lower current reference value SCD2 ¹ . Shortly thereafter, the second node K2 increases its power consumption. The guard SG then registers again an imminent overload, DT0C2. In a short time or at the same time are now messages R2 (RED_K11) and

R3 (RED_K12) to the first node KU, K12, to reduce the power consumption transmitted. While the first node K12 responds and shuts off, SO, the first node KU does not respond. After the protection SG now has an overload, i. a current of more than 1000 A in the present embodiment, detected (DOC), via the

Circuit breaker SV a mains separation, DISC.

With the described protection device is the consideration connected that larger loads, such as DC fast charging stations, and sources, such as photovoltaic systems, may only be connected to the power grid EVN, if they have the communication means described. This is to prevent charging stations for electric vehicles with a high power consumption to go online and immediately trigger the circuit breaker SV. This is the case in particular when several charging stations are already active in parallel and the power supply point is loaded with a high current. The same applies in the reverse direction when several energy producers want to feed electricity into the energy supply network via the same energy supply point.

The proposed approach allows the maximum power consumption or output of the energy infeed point to be dynamically adjusted. The procedure is advantageous so that the network operator can react preventatively due to overloads or bottlenecks in higher-level subareas of the energy supply network.

The protective device can be equipped with a data memory. This can be used for the statistical evaluation of the fluctuating current of non-communicating loads, i. the second node. The memory can be used to detect errors or information about defects

Store node. This can also be realized if necessary, an error analysis after switching off or a further shutdown after restoring a network connection can be prevented.

The protective device according to the invention makes it possible to go closer to the load limit of the energy distribution network. Likewise, the number of overload-related power shutdowns can be reduced.

All components necessary for carrying out the method according to the invention can be integrated in the protective device at the energy infeed point. In this case, a realization with low complexity is possible.

The protection device does not directly control the nodes, but only provides them with information regarding the maximum current of a power consumption or Abgäbe. The connected nodes control themselves based on the information received from the protection device.

Claims

claims

1. A method for monitoring an energy supply point (ESP) of a power supply network, in particular in the low voltage range, wherein the energy supply point (ESP) a number of first and second nodes (KU, K12, K13, K2) is connected or connectable, wherein a respective node (KU, K12, K13, K2) is a power generator, an energy consumer or a prosumer, in which:

a) at the power feed point (ESP) an actual current representing the current consumption or Abgäbe is detected by a measuring and monitoring device;

b) a current information (SI) obtained from one of the first nodes (KU, K12, K13), which includes an intended and / or a maximum possible current consumption or output of the first

Node (KU, K12, K13) is processed by checking whether a current value of the current information (SI) meets a predetermined criterion with respect to a possible current value (MW) of the power supply point (ESP);

c) the possible current value (MW) is determined by a difference formation from the predetermined maximum current of the energy supply point (ESP) and the actual current;

d) depending on the fulfillment or non - fulfillment of the

Criteria at the first node (KU, K12, K13) is transmitted a message that the first node (KU, K12, K13) confirms or rejects the power consumption or Abgabäbe.

2. The method of claim 1, wherein the criterion is satisfied when the current value of the current information (SI) is smaller than the amount of the possible current value (MW).

3. The method of claim 1 or 2, wherein the criterion is not satisfied when the current value of the current information

(SI) is greater than the amount of the possible current value (MW).

4. The method according to any one of the preceding claims, wherein the steps a) to d) for each first node (KU, K12, K13), which would like to take or deliver power, will be traversed separately.

5. The method according to any one of the preceding claims, wherein the current information (SI) is stored together with an identifier of the first node (KU, K12, K13).

6. The method according to any one of the preceding claims, wherein the current information (SI) measured by the first node (KU, K12, K13) or stored in the first node (KU, K12, K13) current value or a current value representing information wherein an arithmetic unit (RE) of the power input point (ESP) can close the information on the current value.

7. The method according to any one of the preceding claims, wherein in the message which the first node (KU, K12, K13), the power consumption or Abgabäbe confirmed or rejects, a maximum allowable amount of current consumption or Abgäbe is transmitted, the maximum permitted height is less than or equal to the current value contained in the current information (SI).

8. The method according to any one of the preceding claims, wherein an electrical connection of the power supply point (ESP) to the power grid (EVN) is separated when the measured actual current reaches or exceeds the maximum current.

9. Method according to one of the preceding claims, in which a message is transmitted to individual or all first nodes (KU, K12, K13) to reduce or end the current consumption or output when the actual current has reached a current threshold which is lower than the predetermined maximum current.

10. The method according to claim 9, that the message is transmitted as a broadcast message to the first node (KU, K12, K13).

11. The method according to any one of the preceding claims, wherein it is checked whether in the course of time, in particular approximately constant, deviation between the current information obtained from the current information (SI) and an actual current value measured by the arithmetic unit, if the first Node after the message, which is the first node

(KU, K12, K13) confirms or rejects the current input or output, receives or outputs current in accordance with the specification of the message, wherein the arithmetic unit detects the deviation associated with the first node (KU, K12, K13) above a predetermined limit Current information (SI) replaced by an according to the determined by the arithmetic unit actual current value corrected current information.

12. Method according to one of the preceding claims, in which the current consumption or output of the entirety of the second nodes which are not capable of message transmission or of message reception is calculated from the difference between the actual current and the sum of the current information of the first node (KU, K12, K13) which receive or deliver power is closed.

13. The method according to any one of the preceding claims, wherein the maximum current is predetermined by a higher-level unit of the power grid.

14. An apparatus for monitoring an energy supply point (ESP) of a power supply network (EVN), in particular in the low-voltage range, wherein a number of first and second nodes is connected or connectable to the energy infeed point (ESP), wherein a respective node is a power generator, an energy consumer or is a prosumer, comprising: a measuring and monitoring device (ME) for measuring an actual current representing the current consumption or Abgäbe at the energy supply point (ESP);

a communication device (KOM) for exchanging data with the first nodes (KU, K12, K13);

an arithmetic unit (RE) for processing a current information (SI) obtained from one of the first nodes (KU, K12, K13) representing an intended and / or a maximum possible current consumption or output of the first node (KU, K12, K13) .

in which

it can be checked by the arithmetic unit (RE) whether a current value of the current information (SI) meets a predetermined criterion with regard to a possible current value (MW) of the energy supply point (ESP);

the possible current value (MW) can be determined by the arithmetic unit (RE) by a subtraction from the predetermined maximum current of the energy input point (ESP) and the actual current;

- By the communication device (KOM) depending on the fulfillment or non-fulfillment of the criterion to the first node (KU, K12, K13) a message is transferable, which the first node (KU, K12, K13) confirms the power consumption or -abgäbe or rejects.

15. The device according to claim 14, characterized in that it comprises a protective device through which an electrical connection to the power grid is separable when the measured by the measuring device (ME) actual current reaches or exceeds the maximum current.

16. The device according to claim 14 or 15, characterized in that it comprises further means for carrying out the method according to one of the preceding claims.