DE102012205155A1 - Method of controlling power in low-voltage network used in e.g. thermal power station, involves transmitting information signal with power feed information from local area network station to prosumer at preset frequency - Google Patents

Abstract

The method involves connecting local area network station (ONS) to prosumer (PE) of low-voltage network (NSN) over phase spacer. An information signal (IS) is generated by signal generating unit in local area network station of low-voltage network, and is transmitted to prosumer at preset master frequency. The control information which represents power fed into low-voltage network is included in the information signal. An independent claim is included for a device for controlling power in low-voltage network.

Description

The invention relates to a method and a device for regulating a power in a low-voltage network, which allows active network operation.

Conventional power grids are mostly developed hierarchically, with a high-voltage network serving as a transmission network and medium-voltage networks and low-voltage networks are provided as distribution networks. Due to the increase in distributed feed-in systems, such as combined heat and power plants, photovoltaic systems or small wind turbines, the originally unidirectional hierarchy of electrical power supply networks, which have a central power generator and a plurality of energy consumers, is broken. In particular, energy feeders based on renewable energy sources are mainly connected to the medium-voltage grid as well as to the low-voltage grid. While ultra-high voltage networks typically operate with a high transmission voltage of more than 100 kV, medium voltage networks have a voltage of 10, 20 or 30 kV and low voltage networks have a lower voltage of 230/400 V. As well as energy consumers, electricity customers are increasingly becoming energy and power producers. A power customer, who becomes a producer through the operation of a decentralized power generation plant, is also called a prosumer, whereby Prosumer is an artificial word from the words "producer" and "consumer". Prosumereinheiten are thus units that consume both electrical energy consume as well as produce or produce decentralized.

Conventional hierarchical power grids are designed based on assumptions resulting from a passive supply hierarchy and parameters such as the length of the power lines. The resulting impedance ratios yield via the known physical relationships voltage and load flow conditions in the hierarchical power grid.

In the case of conventional rural hierarchical grids, it is above all necessary to ensure that the voltage limits in the grid are maintained. If there is a central feed-in point, usually a local network station, and a power line to the customers or electricity consumers, for example, to private households, this results in a line load along the power line. Especially in the vast rural grids, therefore, the effect that the electric voltage continues to decrease as one moves away from the feeding point at which the voltage is fed into the low-voltage network is prevailing. Even at the farthest participant or power consumers, the minimum lower voltage limit loud 50160 Therefore, a voltage with a certain overvoltage from the higher-level medium-voltage network is conventionally fed into the respective low-voltage network. In this case, the setpoint voltage is usually selected such that, even with a minimum load, a permissible upper maximum voltage limit is not exceeded. In such a conventional low-voltage network, however, if electrical power is fed into the low-voltage network at a connection point located near the feed-in point by means of a feed-in unit of a prosumer unit, the upper voltage limit can be exceeded by unwanted transients, which in turn has disadvantageous consequences. If the upper voltage limit is exceeded, it is possible that protective circuits are activated at nearby feed-in systems. The result is that renewable energy, which is to be fed, for example, from a small wind turbine as feed system of a Prosumereinheit in the low-voltage grid, can not be fully fed into the affected low-voltage network.

In contrast to rural networks, urban networks tend to have shorter line lengths due to the load density. Therefore, in urban networks, there is less need for voltage maintenance in the low voltage network, but the need to sufficiently utilize existing resources. Decentralized feed-in systems initially reduce the high utilization of lines and transformers of local network stations. Therefore, the performance limits of energy recovery are rarely violated. However, co-ordination of the feed-in systems is also necessary in urban networks, since they can contribute to a reduction of asymmetries within the network, in which feed-in systems of prosumer units in particular should not exacerbate an already existing asymmetry in the network. In a power supply network, for example, in suburban areas, network sections within the network area may have both a rural and an urban character.

Especially in urban low-voltage networks, the measure to compensate for congestion cases solely by changing the tap position of a transformer provided at the local power station is often insufficient. Also in rural network sections can be due to the spread between different network strands of the low voltage network or the spread in the various Phase alone, the use of a variable transformer in the local network station will not be sufficient.

There is therefore a need for a method and apparatus that allows active grid operation in which feed-in systems are acted upon.

This object is achieved by a method having the features specified in claim 1.

The invention accordingly provides a method for regulating a power in a low-voltage network,
wherein a local network station of the low-voltage network by means of an information signal having a predetermined master frequency, information for controlling the in the low-voltage network (NSN) to be fed or transmitted power to Prosumereinheiten the low-voltage network transmits.

In one possible embodiment of the method according to the invention, the information signal has an amplitude with a predetermined amplitude gradation.

The amplitude preferably indicates an absolute or relative change in the electrical power or energy to be supplied by the prosumer units of the low-voltage network or to be drawn therefrom.

The indicated electrical power may be an active power and / or a reactive power.

In one possible embodiment of the method according to the invention, the information signal is transmitted to the prosumer units via at least one phase line of the low-voltage network.

In a possible embodiment of the method according to the invention, the power supply and / or the power reference by the Prosumereinheiten to reduce phase imbalances in the low-voltage network is phase-specific.

In one possible embodiment of the method according to the invention, the information signal at a first master frequency causes the prosumer units to feed more or less electrical reactive power into the low-voltage network.

Furthermore, in a further embodiment variant, the information signal at a second master frequency can cause the prosumer units to feed more or less active electrical power into the low-voltage network.

In a further possible embodiment of the method according to the invention, the information signal of the first master frequency has a known gradation of the amplitude for the reactive power.

In a possible embodiment of the method according to the invention, the amplitude of the first master frequency indicates a degree of the required adaptation of the reactive power reference or feed required by the prosumeration units.

In one possible embodiment variant, the information signal of the second master frequency has a known graduation of the amplitude for the active power.

In this case, the amplitude of the second master frequency in one embodiment variant can indicate a degree of the required adaptation of the active power supply or reference demanded by the prosumeration units.

In one possible embodiment of the method according to the invention, an amplitude of the information signal additionally indicates the proportion of the active power at the fed or related electrical power.

In a further possible embodiment of the method according to the invention, the prosumers units are each connected to the local network station via at least one phase line and receive the information signal with the master frequency via the latter, the information signal being filtered by a corresponding adjusted signal filter for evaluation by the prosumer units.

In a further possible embodiment variant of the method according to the invention, the prosumeration units additionally transmit in each case via the at least one phase line an associated amplitude-modulated pilot signal to the local network station of the low-voltage network.

In this case, an amplitude of the transmitted pilot signal can specify the amount of power fed into the low-voltage network from a feed-in system of the respective prosumeration unit.

Furthermore, in a further possible embodiment variant of the method, a fundamental frequency of the transmitted pilot signal indicates the entry location and in particular a network strand the power is fed through the feeder unit of the Prosumereinheit into the low-voltage grid.

In a further possible embodiment of the method according to the invention, the master frequency of the information signal is in a different frequency range than the fundamental frequency of the pilot signal.

In a further possible embodiment variant of the method according to the invention, the low-voltage network has a plurality of parallel network strings, wherein the local network station uses different master frequencies for information signals for the different network strings, which are directed to or transmitted to the prosumer units of the different network branches of the low-voltage network.

In a further possible embodiment variant of the method according to the invention, the master frequencies for different network lines of the low-voltage network are multiple frequencies of a network-wide base master frequency.

The invention further provides a device for controlling a power in a low-voltage network with the features specified in claim 13.

The invention accordingly provides a device for regulating a power in a low-voltage network,
wherein at least one Prosumereinheit is connected via at least one phase line to a local network station of the low-voltage network, wherein the local network station has a signal generating means for generating at least one information signal having a predetermined master frequency,
wherein the information signal contains information for controlling the power to be fed into or from the low-voltage network,
wherein the generated information signal is transmitted by the local network station via the at least one phase line to the Prosumereinheiten of the low voltage network.

In one possible embodiment variant of the device according to the invention, the information signal has an amplitude from a predetermined amplitude level,
wherein the amplitude indicates an absolute or relative change in the power to be injected or derived therefrom by the prosumer units of the low-voltage network,
where the power is an active power and / or a reactive power.

In one possible embodiment of the device according to the invention, the information signal is transmitted to the prosumer units via at least one phase line of the low-voltage network.

In a further possible embodiment of the device according to the invention, the power supply and / or the power reference by the Prosumereinheiten to reduce phase imbalances in the low-voltage network is phase-specific.

In a further possible embodiment of the device according to the invention, the low-voltage network has a plurality of parallel network strands, to each of which Prosumereinheiten are connected.

In one possible embodiment of the device according to the invention, the signal generating device generates an information signal with a different master frequency for each network strand of the low-voltage network.

In a further possible embodiment of the device according to the invention, the prosumer units are each designed to feed more or less power into the low-voltage network as a function of the information signal received from the local network station, in particular as a function of its amplitude and / or master frequency.

In a further possible embodiment of the device according to the invention, the network strands are connected to a busbar of the low-voltage network with three phase conductors and a PEN conductor.

In the following, possible embodiments of the method according to the invention and of the power control device according to the invention will be explained in more detail with reference to the attached figures.

Show it:

1 a circuit diagram for illustrating a basic structure of a low-voltage network, in which the inventive method and apparatus for power control can be used;

2 a block diagram of a possible embodiment of a local network station, which is provided in a low-voltage network;

3 a circuit diagram for illustrating a possible embodiment of a Low voltage network with three phase lines and a neutral conductor;

4 a circuit diagram for displaying an asymmetric wiring of Prosumereinheiten within a low-voltage network;

5 a diagram illustrating a voltage drop within a low voltage network;

6 a circuit diagram for representing a low-voltage network [NSN] with multiple power lines.

How to get out 1 can recognize, the low-voltage network NSN has a local network station ONS. A Prosumereinheit PE is connected via at least one phase line L _i to the local network station ONS. The low voltage network NSN may comprise a plurality of phase conductors L ₁ , L ₂ , L ₃ and a PEN neutral, as in FIG 6 shown. Furthermore, a plurality of power lines NS can be connected to a busbar, wherein on each network line NS several Prosumereinheiten PE ₁ ... PE _{N are} provided. Each Prosumereinheit PE is connected via at least one phase line L and a neutral conductor to the busbar, as in 6 shown. Each of the n-net strands NS may have a different number m of prosumer units PE, as in FIG 6 shown. The prosumer units PE can be connected to the busbar via one or more phase lines L _i . For example, the first Prosumereinheit PE ₁ in the network strand n is connected to all three phase lines L ₁ , L ₂ , L ₃ , while z. B. the last Prosumereinheit PE _m2 in the network strand n is connected only to the phase line L1. The number n of the network strings NS of the low-voltage network is typically in a range from 2 to 10. The busbar connects the phase lines L to a local network station ONS, in which a transformer T can be located. In the method according to the invention, the power in the low-voltage network NSN is regulated. In this case, the local network station ONS of the low-voltage network by means of an information signal IS having a predetermined master frequency f _M , information or data for controlling the fed into the low-voltage network NSN or electrical power P to be transferred to the Prosumereinheiten PE of the low-voltage network NSN. In one possible embodiment, the information signal IS or control signal, which is transmitted from the local network station ONS to the prosumer units PE, has an amplitude with a predetermined amplitude graduation. In this case, the amplitude may indicate an absolute or relative change in the power or energy to be fed in or to be drawn from the prosumer units PE of the low-voltage network NSN. The amplitude may indicate an absolute or relative change in active power or reactive power to be fed into the low-voltage network NSN, or indicate active power or reactive power to be sourced from the low-voltage network NSN by the prosumer units PE. The information or control signal IS is transmitted from the local network station ONS via at least one phase line L of the low-voltage network NSN to the Prosumereinheiten PE. The prosumer units PE can be pure consumers, but also units which both receive power and can feed power into the low-voltage network NSN, for example photovoltaic systems. The prosumer units PE may, for example, be e-mobility charging points or the like, which are connected to the low-voltage network NSN via a phase line L. Furthermore, the prosumer units PE can also be units that are connected to all three phase lines L ₁ , L ₂ , L ₃ , such as the first prosumeration unit PE ₁ in the last network string n of the low-voltage network NSN, as in the exemplary embodiment of FIG 6 is shown.

The information or control signal IS has a predetermined master frequency f _M with a standardized amplitude with a defined graduation, which tells the prosumer units PE to draw inductive reactive power in certain steps in order to lower the voltage in the low-voltage network NSN or indicates a capacitive reactive power reference. to allow a voltage increase in the low voltage network NSN. The gradation of the amplitude can be absolute, for example, by predetermining reactive power values, or relatively via the power factor cosφ. Furthermore, the grading can also be based on the current active power feed. In one possible embodiment, the prosumer units PE recognize from the amplitude level of the received information or control signal IS which reactive power settings are required. If, for example, A is the output amplitude of the information signal IS, the following assignment can be made, for example, in the case of the embodiment variant:
0.25 A: cosφ = 0.8 ind .;
0.5 A: cosφ = 0.9 ind .;
1 A: cosφ = 1;
2 A: cosφ = 0.9 cap .;
3 A: cosφ = 0.8 kap.

Various variants of the method and the device according to the invention are possible. In one embodiment, the information signal at a first master frequency causes the prosumer units PE to have more or less active power in the Low-voltage network NSN feed and causes at a second master frequency, the Prosumereinheiten PE to feed more or less reactive power in the low-voltage network NSN. In one embodiment variant, the information signal may have an amplitude which indicates a degree of the change in the power reference or power supply demanded by the prosumer units PE (depending on the master frequency for active power or reactive power). The degree of the power reference or the power supply is thus indicated by the amplitude of the respective information signal IS, which has the first or second master frequency. The Prosumereinheiten PE are each connected via at least one phase line L to the local network station ONS and receive about the information signal with the respective master frequency. In this case, the information signal IS can be filtered by an appropriately set signal filter SF Prosumereinheit PE for evaluation by an evaluation of Prosumereinheit PE.

As in 6 illustrated, the low-voltage network NSN may have multiple parallel network strands NS. In one embodiment variant, the local network station ONS uses different master frequencies f _M for information signals IS, which are directed to the prosumer units PE of the different network lines NS of the low-voltage network NSN. In one embodiment variant, the master frequencies for different network lines NS of the low-voltage network NSN can be multiple frequencies of a network-wide base network frequency f _M. In one embodiment, the local network station ONS has a signal generating device which generates an information signal IS with a different master frequency for each network line NS of the low-voltage network NSN. The prosumer units PE are designed to feed more or less power into the low-voltage network NSN depending on the information signal IS received by the local network station ONS, in particular as a function of its amplitude A and / or master frequency f _M.

In one possible embodiment of the method according to the invention, an information signal IS at a certain master frequency can cause the reduction of an active power feed by a prosumer unit PE. Especially in urban cable networks with a pronounced ohmic character, a pure reactive power reduction for power control is often insufficient. The additional active power reduction can also be documented by specifying the master frequency, wherein this documented information can be made available to the plant operator, in particular for any compensation regulations or the like.

By using further master frequencies, a line-specific regulation of the mains voltage can be carried out. In this way, the spreading can be actively reduced, for example, by making blind power specifications by the local network station ONS only in one network strand NS. In this case, the prosumeration unit PE is preferably informed beforehand in which network strand of the low-voltage network NSN the prosumeration unit PE is located and to which master frequency the prosumulation unit PE has to react. In order to keep the number of necessary master frequencies f _M for the different network strings small, it is possible in one embodiment to carry out a grouping of several network strings NS with respect to the master frequency, which are similar with respect to load and generation situations. In a possible embodiment variant not only the network strands NS are grouped with respect to the master frequency, but also the existing therein Prosumereinheiten PE grouped as whether they are in the vicinity of the local network station ONS or far away from the local network station ONS. An existing in the local network station ONS higher-level control unit has in this way more degrees of freedom to perform the most optimal feed-in control for the low-voltage network NSN.

The coupling of the information signals with the various master frequencies can also be phase-specific in a possible embodiment variant for influencing any phase imbalances. In this case, the prosumer units PE have reception devices which listen for all three phases L ₁ , L ₂ , L ₃ . Furthermore, the receiving devices of the prosumeration units PE in this embodiment can recognize the respective phase for which the current power influencing is valid on the basis of reduced crosstalk signals in the respectively other two phases. The respective Prosumereinheit PE knows to which phase L of the low voltage network NSN it is connected and participates in accordance with the respective power control. If the prosumer unit PE is a unit which is connected to all three phases L ₁ , L ₂ , L _{3 of} the low-voltage network NSN, the use of the phases can be varied according to the specifications. It should be noted that in a low-voltage network NSN the operation is usually not three-phase symmetry, but for example, in the case of photovoltaic systems in each case according Lichteinstrahlungsverhältnissen the power of one phase after another can be added.

The method according to the invention or the device according to the invention for regulating a power in a low-voltage network NSN can in one possible embodiment variant be extended to the effect that the Prosumereinheiten PE each transmit at least one of the phase lines L an associated amplitude-modulated pilot signal PS to the local network station ONS of the low-voltage network NSN. In this case, an amplitude of the transmitted pilot signal PS can specify the amount of power fed into the low-voltage network NSN from a feed-in system of the respective prosumeration unit PE. Furthermore, a fundamental frequency of the transmitted pilot signal PS can specify the entry location and in particular a network strand, at which the power is fed into the low-voltage network NSN by the feed-in system of the prosumeration unit PE. Preferably, the master frequencies f _{M of} the information signal lie in a different frequency range than the fundamental frequencies of the pilot signal PS transmitted by the prosumer units PE to the local network station ONS.

In the method according to the invention and the device according to the invention, no additional communication and measuring devices need to be provided, in particular no complex communication mechanisms, such as, for example, packet-based powerline communication. In the apparatus according to the invention, in addition to the regulation of the voltage at the local network transformer for regulating the voltage level, the feed-in powers at specific points of the low-voltage network NSN can also be used for the targeted reduction of the spread.

In one embodiment of the method according to the invention, the prosumeration unit PE transmits, via the phase line L to which it is connected, an associated amplitude-modulated pilot signal PS to the local network station ONS of the low-voltage network NSN. In this case, the amplitude of the transmitted pilot signal PS fed from a feed system of the respective Prosumereinheit PE in the low-voltage network NSN amount of power or energy quantities. The fundamental frequency f of the transmitted pilot signal PS can indicate the entry point at which the electrical power or energy is fed into the low-voltage network NSN through the feed-in system of the prosumeration unit PE. The voltage at the feed point of the feed system is thus superimposed in this embodiment, a high-frequency pilot signal PS. The amplitude A of the superposed amplitude-modulated pilot signal PS in this case reflects the fed-in electrical power.

In a further possible embodiment of the method according to the invention, each feed-in system of a prosumeration unit PE generates an overlay or pilot signal PS with a frequency f characteristic of the feed-in system. For this purpose, a card is distributed to the Prosumereinheiten in one possible embodiment by a network operator of the low-voltage network NSN, which can be seen at what frequency f the superimposed signals or the amplitude-modulated pilot signals PS are to be fed. This card or table can be distributed in electronic form to users of the Prosumereinheit PE or directly to the Prosumereinheit PE. In one possible embodiment, the frequency f removed from the card can then be set manually by the operator or user of the prosumulating unit PE. In a further possible embodiment, the characteristic frequency f of the amplitude-modulated pilot signal PS can be derived from geospatial data. If the relationship between the distance of the prosumeration unit PE from the main insertion point, i. H. the local network station ONS of the low voltage network NSN, and the frequency f is known, at the main feed point, i. H. the local network station ONS, using a model of the power grid or low-voltage network NSN a characteristic load profile can be specified. The characteristic load curve shows how the voltage U in the entire low-voltage network NSN behaves due to the current feed situation. The relationship between the distance of the feed station to the local network station ONS and the frequency f can be illustrated by means of a simple example. In a linear topology of the low-voltage network NSN, for example, the frequency f increase at 10 Hz per meter. In one possible embodiment, a prosumer unit PE, which is for example 100 m away from the main feed point or the local network station ONS, then generates a pilot signal PS which has a fundamental frequency f of 100 × 10 Hz = 1 kHz.

In one possible embodiment of the method according to the invention, a transformer T provided at the local network station ONS is additionally set as a function of the stated power quantity and the specified feed location for regulating a voltage level in the low-voltage network NSN. If there are over- or under-voltages or overcurrents depending on the type of low-voltage network, a change of a tap changer to the transformer T can be triggered in order to set a lower target voltage to the busbar of the low voltage network NSN.

In one possible embodiment of the method according to the invention, the transmission of the amplitude-modulated pilot signal PS by the prosumer unit PE to the local network station ONS begins a predetermined period of time before an actual feed of the power through the prosumulator unit PE into the low-voltage network NSN. In this way, the setting of the transformer T at the local network station ONS proactive be performed. In this way predicative control approaches can be pursued or possible critical transition states in the low-voltage network NSN can be prevented. For example, the pilot signal PS can be transmitted to the local network station ONS with a pre-warning time of one minute before the actual supply of the power in the low-voltage network NSN. In one possible embodiment of the method according to the invention, the fundamental frequency f of the superposition signal or pilot signal PS can be calculated by means of a predetermined function, the fundamental frequency f unambiguously indicating the distance of the respective feed system of the prosumeration unit PE from the main feed point or the local network station ONS. An example of such a function is the multiplication of the distance d of the feed system from the main feed point or the local network station ONS in meters with a predetermined base frequency f0 of, for example, 100 Hz. The fundamental frequency f of the pilot signal PS coupled in by the prosumer unit PE depends on the distance d between the prosumeration unit PE and the local network station ONS of the low-voltage network NSN. The fundamental frequency f of the pilot signal PS coupled in by the prosumer unit PE preferably depends linearly on the distance d between the prosumer unit PE and the local network station ONS.

In one possible embodiment of the method according to the invention, the amplitude-modulated pilot signal PS injected by the prosumeration unit PE into the phase conductor L of the low-voltage network NSN has two signal sections. In a first signal section of the amplitude-modulated pilot signal PS, the amplitude of the pilot signal PS indicates the amount of power fed into the low-voltage network NSN by the prosumulator unit PE. In a second signal section of the amplitude-modulated pilot signal PS, a reference amplitude indicates a specific reference power quantity. The amplitude of the first signal section thus indicates the current feed-in power or the feed-in current. In the second signal section of the pilot signal PS, the signal amplitude for a previously agreed feed, for example 1 kW, is selected. This makes it possible to determine the injected power even if the impedance of the low-voltage network NSN changes over time.

In a further possible embodiment of the method according to the invention, the pilot signal PS has a fundamental frequency f and one or more harmonics. In this embodiment, the superposition signal or the pilot signal PS is generated by the Prosumereinheit PE with a fundamental frequency f and at one or more harmonics. Due to the frequency dependent attenuation of signals in the power grid, in this embodiment, the ratio of the measured signal strength ratios at different frequencies, i. H. at the fundamental frequency f and their harmonics, the distance d of the prosumeration unit PE to the main feed point or the local network station ONS are closed. In one possible variant, the frequencies are selected such that the harmonics do not coincide with the fundamental frequencies and harmonics of other prosumer units. An example of such a choice are frequencies whose ratio to a common fundamental frequency is described by a unique prime number. It is necessary that these primes are greater than the highest atomic number of the generated harmonics. Another way to avoid coincidence with fundamental frequencies and harmonics of other prosumer units is to avoid generating prime-order harmonics.

In the case of the abovementioned variant of a pilot signal with harmonics, it is possible for the pilot signal PS to be transmitted or superposed by a feed system of the prosumer unit PE for a predetermined or agreed period of time before the actual supply of the power, in order in this way to reduce the main supply voltage at the main feed location or to proactively change the local network station ONS, if necessary.

In another possible variant, the feed-in system of the prosumer unit PE selects the fundamental frequency f independently by monitoring or monitoring the transmitted frequencies of the feed systems for a longer period of time and, after analyzing them, selecting a previously unoccupied frequency for transmitting its own amplitude-modulated pilot signal PS.

In one possible embodiment, the measurement accuracy of the injected power or the injected current can be increased by the transmission of a normalized reference amplitude at a designated signal portion of the pilot signal PS. The same applies to the distance between the Prosumereinheit PE and a central feed.

2 shows a block diagram illustrating a possible embodiment of a provided in the local network station ONS device for the detection of feeders that feed power into a low-voltage network NSN. At the in 2 In the embodiment shown, the device V for detecting the feed systems is located within a local network station ONS of the low-voltage network. How to get out 2 can recognize, the device V has a decoupling unit AE for decoupling an amplitude-modulated pilot signal PS received by a prosumer unit PE via a phase line L of the low-voltage network NSN. The decoupled pilot signal is transmitted from the decoupling unit AE to a signal evaluation unit SAE, which carries out a signal evaluation of the received amplitude-modulated pilot signal PS. In this case, the amplitude of the received amplitude-modulated pilot signal PS indicates the amount of power fed by a feed-in system of the respective prosumulator unit PE. Furthermore, the fundamental frequency f of the received and coupled-out amplitude-modulated pilot signal PS indicates the entry point at which the feed-in system of the respective prosumeration unit PE has fed the power into the low-voltage network NSN. At the in 2 In the embodiment shown, the signal evaluation unit SAE has access to a local data memory DS. At the in 2 illustrated embodiment, the data storage DS is integrated in the device V. Alternatively, the signal evaluation unit SAE can also have access to a remote data memory via a data network, for example the Internet. A table is stored in the data memory DS, in which each fundamental frequency f of a pilot signal PS is assigned a prosumer unit PE and its feed point in the low-voltage network NSN. This table can also be transmitted by a network operator to the Prosumereinheit PE.

In a possible embodiment of the in 2 Device V shown controls the signal evaluation unit SAE a transformer T within the local network station ONS. In this case, the signal evaluation unit SAE of the device V sets the transformer T of the local network station ONS of the low-voltage network NSN as a function of the stated power quantities and the specified feed locations of the prosumer units PE connected to the low-voltage network NSN for regulating a voltage level U in the low-voltage network NSN. In this case, the signal evaluation unit SAE can set a transmission ratio of the transformer T as a function of the quantities of power read from the data memory DS and feed locations of the prosumer units PE connected to the low-voltage network NSN.

3 shows an embodiment of a low-voltage network NSN with three phase lines L1, L2, L3 and a neutral N. Each of the illustrated Prosumereinheiten PE is connected to one of the three phase lines L1, L2, L3 and the neutral N of the low-voltage network NSN. 3 shows a symmetrical case in which the Prosumereinheiten PE almost equally distributed to the different phase lines L1, L2, L3 of the low-voltage network NSN are connected. The pilot signal PS generated by a prosumer unit PE is coupled by the prosumer unit PE to that phase conductor L to which the prosumeration unit PE is connected. The pilot signal PS of the prosumer unit PE coupled into one of the phase conductors L and transmitted to the local network station ONS causes crosstalk pilot signals in the other phase conductors of the low-voltage network which have a lower amplitude than the transmitted amplitude-modulated pilot signal PS. By comparing the amplitudes of the transmitted pilot signal PS and the crosstalk pilot signals produced by this pilot signal PS, in one possible embodiment it can be determined to which of the phase conductors L of the low-voltage network NSN the respective prosumer unit PE is connected. In this way, it can easily be detected at the local network station ONS, into which phase line L energy or power is fed by a Prosumereinheit PE. If the frequency of the superimposed signal or the pilot signal PS chosen low enough, the resulting crosstalk pilot signal in the other phase lines is much smaller than in that phase line L, in which the respective Prosumereinheit PE has fed power.

4 shows another example of a low-voltage network NSN, in which the various prosumers PE are all connected to the same phase line L1, so that there may be significant asymmetries due to feeding power or energy into the low-voltage network NSN. By evaluating the transmitted from the Prosumereinheiten PE to the local network station ONS pilot signals PS and their crosstalk pilot signals, it is possible in the inventive method V, in the in 4 shown case that all prosumers PE are connected to a phase line L1. In this case, the signal evaluation unit SAE of the device V within the local network station ONS can evaluate this information and, if necessary, send corresponding control signals to correspondingly automated switching devices which ensure that the prosumer units PE are switched largely uniformly on the three different phase lines Li of the low-voltage network NSN. so as to avoid asymmetries in the low-voltage network NSN. If no correspondingly automated switching devices are available, the change can be initiated manually by the distribution system operator after appropriate readout (eg from log file) of detection of an asymmetry.

5 shows a signal diagram for representing a voltage drop U (x) via a line of a low voltage network NSN. At location x = 0 is the main feed point or the local network station ONS of the low-voltage network NSN. The X coordinate indicates the distance d from the main supply ONS. The local network station ONS can additionally the transformer T as a function of the specified power levels and the specified feed points for controlling a voltage level U within the low-voltage network NSN. In this case, the voltage U is adjusted so that the farthest Prosumereinheit PEn, in the case of heavy load, still receives a necessary minimum voltage Umin. Furthermore, the regulation of the voltage level in the low-voltage network NSN takes place in such a way that a defined maximum voltage Umax is not exceeded at the supply location, with high supply in the case of low load. The curve I shows a voltage curve at low load with high feed. Curve II shows a curve at high load with low feed. The inventive method can be determined or demonstrated by cooperative use of the power grid or connected to the low-voltage network NSN units, which Prosumereinheit PE feeds or feed at which Einspeisort how much network power in the low-voltage network NSN. The inventive method has the advantage that no additional communication and network facilities are necessary, in particular no complex communication mechanisms, such as packet-based powerline communication mechanisms.

Furthermore, the method according to the invention represents a measuring method for networks for which no smart meters or the like are provided. In the method according to the invention, the changes to be made to a conventional low-voltage network NSN are minimal, so that the method according to the invention offers itself for the efficient rectification of already existing low-voltage networks NSN. On the basis of the information determined in the superimposition signals or pilot signals PS, a main feeder or a local network station can draw conclusions about how, if necessary, the feed or the feed-in current has to be changed in order to remain within predefined boundary values in the entire network.

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Cited non-patent literature

• EN50160 [0004]

Claims (16)

A method for regulating a power in a low-voltage network (NSN), wherein a local network station (NSS) by means of an information signal having a predetermined master frequency (f _M ), information for controlling the fed into the low-voltage network (NSN) or from power to be transferred to Prosumeration Units (PE) of the Low Voltage Network (NSN). Method according to claim wherein the information signal has an amplitude of a predetermined amplitude level, wherein the amplitude indicates an absolute or relative change in the power to be fed thereto or to be drawn therefrom by the prosumer units (PE) of the low-voltage network (NSN), in particular active and / or reactive power. The method of claim 1 or 2, wherein the information signal via at least one phase line (L) of the low voltage network (NSN) is transmitted to the Prosumereinheiten (PE). The method of claim 3, wherein the power supply and / or the power reference by the Prosumereinheiten (PE) to reduce phase imbalances in the low-voltage network (NSN) is phase-specific. The method of claim 1, wherein the information signal having a first master frequency (f _M1 ) causes the prosumer units (PE) to feed more or less electrical reactive power into the low voltage network (NSN), and wherein the information signal having a second master frequency (f _M2 ) is the Prosumers (PE) to feed more or less electrical active power in the low voltage network (NSN). The method of claim 5, wherein at the first master frequency (f _M1 ) the information signal has an amplitude indicative of a degree of reactive power demand required by the prosumer units (PE), wherein at the second master frequency (f _M2 ) the information signal has an amplitude which indicates one degree of the active power supply or active power demand demanded by the prosumer units (PE). Method according to one of the preceding claims 1 to 6, wherein an amplitude of the information signal additionally indicates the proportion of the active power to the supplied or related power, wherein the reactive power is defined relative to the indication of a power factor cosφ. Method according to one of the preceding claims 1 to 7, wherein the Prosumereinheiten (PE) in each case via at least one phase line (L) to the local network station (ONS) are connected and above the information signal with the master frequency (f _M ) received, the information signal by a corresponding adjusted signal filter (SF) for evaluation by the Prosumereinheit (PE) is filtered. Method according to one of the preceding claims 1 to 8, wherein the prosumer units (PE) in each case transmit an associated amplitude-modulated pilot signal (PS) to the local network station (ONS) of the low-voltage network (NSN) via the at least one phase line (L), wherein the amplitude (A) of the transmitted pilot signal (PS) fed from a feed system of the respective Prosumereinheit (PE) in the low voltage network (NSN) power amount and a fundamental frequency of the transmitted pilot signal (PS) indicates the point of entry, and in particular a network line, at which the power is fed into the low-voltage network (NSN) through the feed-in system of the prosumeration unit (PE). A method according to claim 9, wherein the master frequency (f _M ) of the information signal is in a different frequency range than the fundamental frequencies of the pilot signals (PS). Method according to one of the preceding claims 1 to 10, wherein the low-voltage network (NSN) comprises a plurality of network lines for which the local network station (ONS) uses different master frequencies (f _M ) for information signals which are sent to the prosumer units (PE) of the different network lines of the low-voltage network (NSN ) are directed. Method according to Claim 11, wherein the master frequencies (f _M ) for different network lines of the low-voltage network (NSN) are multiple frequencies of a network-wide basic master frequency (f _M0 ). Device for regulating a power in a low-voltage network (NSN), wherein a local network station (ONS) of the low-voltage network (NSN) via at least one phase line (L) to Prosumereinheiten (PE) is connected and a signal generating means for generating at least one information signal with a predetermined master frequency (f _M ), the information to control the fed into the low-voltage network (NSN) or from The generated information signal is transmitted by the local network station (ONS) via the at least one phase line (L) to the prosumeration units (PE) of the low-voltage network (NSN). Device according to claim 13, wherein the low-voltage network (NSN) has a plurality of network lines which are respectively connected to the prosumer units (PE) via at least one phase line (L), wherein the signal generating device generates an information signal with a different master frequency for each network strand of the low-voltage network (NSN). The device according to claim 13, wherein the prosumer units (PE) are each designed to have more or less power in relation to the information signal received from the local network station (ONS), in particular as a function of its amplitude and / or master frequency (f _M ) Low-voltage network (NSN). The apparatus of claim 15, wherein the power lines are connected to a bus bar of the low voltage network (NSN) having a plurality of phase conductors (L) and a PEN conductor.

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