WO2013149784A1

WO2013149784A1 - Arrangement for transmitting data in a power supply grid

Info

Publication number: WO2013149784A1
Application number: PCT/EP2013/054624
Authority: WO
Inventors: Janos Gila; Leopold Resel; Martin Schiefer
Original assignee: Siemens Ag Österreich
Priority date: 2012-04-04
Filing date: 2013-03-07
Publication date: 2013-10-10
Also published as: AT512668B1; AT512668A1

Abstract

The invention relates to an arrangement for transmitting data in a power supply grid (L, N), in particular for power line communication. The arrangement according to the invention has at least two communication units (KE1, KE2), as signal emitters and/or signal receivers, and a power supply grid (L, N). Data can be transmitted between communication units (KE1, KE2) by means of a data signal via the power supply grid (L, N). The data signal is transmitted by a modulation on the carrier frequency of the power supply grid (L, N). Each communication unit (KE1, KE2) provides a signal reference potential (S1, S2) in the arrangement according to the invention. A connection (V1, V2) is provided between the signal reference potential (S1, S2) and at least one protective grounding conductor (PE) of the power supply grid (L, N). Advantageously, the protective grounding conductor (PE) of the power supply grid is coupled to other conductors (L, N), in particular the outer conductors (L) and/or the neutral conductor (N) of the power supply grid. In this manner, the data transmission is not disrupted and the transmission quality is improved in a simple manner in the event of possible interruptions of the conductors (L, N).

Description

Besehreibung

Arrangement for transmitting data in a power supply network

Technical area

The present invention relates to an arrangement for transmitting data in a power supply network, in particular for so-called powerline communication, wherein the arrangement has at least two communication units as a signal transmitter and / or signal receiver and a power supply network. In this case, the data can be transmitted by a data signal modulated onto a carrier frequency of the power supply network.

State of the art

In a transmission of data by means of conventional radio technology, in which data and / or information is transmitted by means of electromagnetic waves in a so-called radio network, it can be used in highly metallic environments such as e.g. when used in the industrial sector to disturbances. Therefore, such a transmission in a metallic environment difficult and possibly can be realized only with great effort.

One way to solve this problem or to improve the transmission of data in a highly metallic environment, for example, the so-called capacitive near-field technology, of which, for example, a metallic infrastructure (eg water pipes, electrical lines, etc.) for a transmission of Data, information or data signals is used. In this technique, a communication unit for coupling and decoupling the data signals to the metallic infrastructure is capacitively coupled. For this purpose, the communication unit, for example, via electrodes to the infrastructure of a power supply network as asymmetric communication connected on unit. This means that a data signal transmission from this communication unit is carried out as an asymmetrical signal transmission, for example via a conductor of a power supply network.

In asymmetric signal transmission, the transmission of a data signal is performed by a voltage which varies from a reference potential. Asymmetric signal transmission is thus one of the simplest ways of transmitting data signals or data. It is performed on a conductor, a voltage which is changed according to the respective data signal with respect to a reference conductor, usually the so-called mass. In a power supply network, an asymmetric communication unit uses, for example, a phase conductor for the signal voltage and another conductor (for example, neutral conductor, etc.) as a reference conductor. A connection of the communication unit can be used in the near-field technique, e.g. directly - i. wired - done by means of a discrete component, in particular a capacitor or a coil.

However, the near-field capacitive technique has some

Disadvantages. In the case of asymmetric signal transmission, in particular due to differences in the reference voltage level between the transmitter and receiver unit or due to electromagnetic interference, data signal transmission may be disturbed. Furthermore, asymmetric communication units with direct coupling in a power grid (i.e., with coupling via discrete components such as capacitors or coils which are directly connected to the mains) must not be used for approval reasons. In this case, only communication units for a symmetrical signal transmission in a power supply network may be used.

In symmetric signal transmission, the transmission of data signals does not take place as with asymmetrical signal transmission with a signal conductor but via a pair of signal conductors. Thus, an influence of the data signal to be transmitted on the transmission path on both conductors is almost identical, so that, for example, by means of subtraction of the two potentials conductor disturbances can be easily eliminated. Since two conductors are always used in the symmetrical signal transmission, a symmetrical communication unit is usually connected to two conductors such as a phase or outer conductor and the neutral conductor during data transmission via a power supply network. However, it is also possible, for example, to use two phase conductors or outer conductors for the symmetrical transmission.

For the transmission of data or data signals there are in a power supply network as a method for symmetrical signal transmission, the so-called Powerline Communication or PLC short. Powerline communication or PLC refers to a technology in which existing power lines or an existing power supply network for the construction of a network for the transmission of data at least be shared. It is therefore no additional wiring for a transmission of data necessary. In PLC, the data or data signals to be transmitted, e.g. by means of communication units (eg special adapters, etc.) modulated onto the lines (eg phase or outer conductor, neutral) of the power supply network or filtered down again by these, without the communication units for data transmission by the voltage prevailing on the power supply voltage and / or Mains frequency is disturbed.

Technically speaking, PLC is a carrier frequency system which is realized via communication units such as special adapters, which are plugged into a socket and, for example, via a built-in interface (eg Ethernet interface, etc.) with a terminal (eg PC, printer, Measuring point, etc.). The data signal is from a transmitting communication unit in the high frequency range (eg between 2 to 30 MHz) on the Lines of the power supply network modulated and demodulated by a receiving communication unit again. Symmetrical transmission systems such as Powerline Communication, etc., however, have the disadvantage that a data transmission is interrupted or at least significantly disturbed when one of the two lines (eg outer conductor or neutral conductor) is disturbed for the transmission. Because the modulated data is always available only in these lines. Common power grids (low voltage grids), such as those used in the private sector or for simple power supply, are so-called three-phase networks. In these, in addition to a neutral conductor and a protective conductor - the so-called protective earth - usually three outer or phase conductors are provided.

However, the three phase conductors are suitable for powering to different areas within, e.g. Housing units, etc. divided. This is in the various areas ei ner residential unit, etc. in addition to neutral and protective ground always only a phase or outer conductor for the Datenübertragun available or modulated on the power supply data can only be received if this phase conductor is present. In particular, a disturbance of the outer conductor leads to a reduction of the transmission quality, restrictions and / or interruptions in the data transmission via the power supply network.

In order to ensure data transmission in a power supply network with a plurality of external or phase conductors, such as, for example, a three-phase network, so-called phase-couplers are used, for example. A phase coupler is an electronic circuit with at least one capacitor, which is used to a high-frequency bridging the Außenbzw. To allow phase conductors for a trouble-free data transmission. Due to the high-frequency bridging of the outer conductors, data transmission via corresponding communication units (eg PLC adapter, carrier frequency modem, etc.) is possible over several outer conductors. The use However, of phase coupler has the disadvantage that phase couplers already in the installation of a power supply network - especially in three-phase - must be provided and installed. Subsequent installation is usually expensive and expensive. In addition, interruptions of an external or phase conductor and / or a neutral conductor for the data transmission by a phase coupler are only canceled if it is positioned between the interruption and those communication units which are used as signal transmitters and / or signal receivers. Thus, even when installed in the installation of a power supply network - especially in the industrial sector - a planning for the positioning of phase coupler difficult and expensive.

Presentation of the invention

The invention is therefore based on the object of specifying an arrangement for the transmission of data in a power supply network, through which a trouble-free transmission of data in the power supply network at any time with symmetrical transmission systems or communication units can be carried out without additional effort.

The solution of this object is achieved by an arrangement of the type mentioned, in which each communication unit has a signal reference potential, and in which a connection between each signal reference potential and at least one protective earth conductor of the power supply network is provided.

The main aspect of the arrangement according to the invention is that in a simple manner and without additional effort symmetric communication units such as standardized powerline communication modems or other proprietary symmetric transmission systems in a power grid - especially in a multi-phase network or in a three-phase network - can be installed. By an optionally However, the interruption or malfunction of an external or phase conductor and / or the neutral conductor of this power supply network does not adversely affect the data transmission - ie there is no disruption or interruption of the data communication

The protective earth conductor in a power supply network is an electrical conductor for the purpose of safety such as e.g. for protection against electric shock, contact voltages, etc. in the event of a fault in the power supply network. The abbreviation for the protective earth conductor is PE, which stands for "protective earth." In the case of plug connections to the power supply network, the protective earth conductor is connected, for example, to special protective contacts which are arranged in such a way that they are connected in front of the other contacts (eg to outer conductor and neutral conductor) and separated according to the other contacts.

By connecting a signal reference potential of a communication unit with at least one protective earth conductor of the power supply network, an additional line is created, which can be used for the transmission of data - especially in the event of a fault. The additional line for data transmission resulting from the connection to the protective earth conductor has, in particular via capacitive coupling capacitances existing in the power supply network, a capacitive coupling with phase or outer conductor and neutral conductor, which are used for the symmetrical transmission of the data or data signals. The use of the protective earth conductor improves, above all, the quality but also the range of the symmetrical data transmission in a power network - in particular for the case in which different phase or outer conductors for the respective coupling are used by the communication units used as signal transmitters and signal receivers the power supply network are used. By the connection of the signal reference potential of a communication unit with at least one protective earth conductor of the power supply network, so to speak, a distributed phase coupling is realized for a symmetrical transmission of data. This distributed phase coupling also ensures that a position of an optionally occurring interruption of an external or phase conductor or the neutral conductor in the power supply network plays a significantly smaller role, since the coupling of the lines - in particular by parasitic coupling capacities in the high-frequency range - always exists.

It is advantageous if the connection with the protective earth conductor of the power supply network is designed as a ground terminal. This means that the communication units have their own ground connection, via which the respective communication unit can be easily connected to the protective earth conductor, so that this as an additional line for the transmission of data in case of interruption of the symmetric transmission (eg in case of a fault of an external conductor or the neutral conductor, etc.) is available.

It is also conceivable to connect the grounding connection with metallic infrastructure elements (for example housings, etc.). Therefore, it is also advantageous if the communication units each have a housing made of metal, which can be used for connection to the protective earth conductor of the power supply network.

Ideally, an isolating transformer is provided for inputting and decoupling the data signals into the power supply network. Via a so-called isolation transformer, a symmetrical transmission of the data or data signals in the power supply network can be realized. This means that the data or data signals are switched in and out via the isolating transformer on the phase and neutral conductors as a signal line and transmitted in parallel thereto. As an isolating trans- Formator is referred to in the narrow sense of a network transformer, in which a mains voltage in the ratio 1: 1 is transmitted to a secondary winding. However, it is also possible to choose a ratio 1: N for the isolating transformer. This has the advantage that in this case an optimum voltage for the power supply of the communication unit can be set. The secondary winding is separated by a so-called protective separation of a mains voltage leading to the so-called ground potential related primary winding. This ensures that the communication units are potential-free. By using the isolation transformer, the signal reference potential internal to the communication unit (eg a so-called device ground) can then be implemented as a ground connection for the connection to the protective earth conductor.

In a preferred embodiment of the arrangement according to the invention, high-voltage capacitors with symmetrical output stages can alternatively be provided for inputting and decoupling the data signals into the power supply network. By using high-voltage capacitors with a symmetrical output stage, a symmetrical transmission of the data or data signals in the power supply network can likewise be implemented-as by means of an isolating transformer. The high-voltage capacitors with balanced output stages also make the communication unit floating, and in this case too, the signal reference potential internal to the communication unit (e.g., a so-called device ground) can be easily used as a ground terminal for connection to the protective ground conductor.

Brief description of the drawing

The invention is explained schematically below by way of example with reference to the attached FIG. FIG. 1 shows schematically and by way of example an arrangement according to the invention for the transmission of data in a power supply network. Embodiment of the invention

FIG. 1 shows, in a schematic and exemplary manner, the arrangement according to the invention for transmitting data in a power supply network. The power grid is, for example, a multi-phase system such as a multi-phase system. Three-phase network, which usually consists of three phase and outer conductors L, a neutral conductor N and a protective earth conductor PE. For the sake of simplicity, only an exemplary external or phase conductor L, a neutral conductor N and a protective earth conductor PE are shown in FIG. 1 in the exemplary illustration of the arrangement according to the invention.

The conductors L, N and PE have ohmic resistances R, Rl, R2 and RL, respectively. In this case, the outer or phase conductor L is represented by the line resistances R and Rl, wherein the resistor Rl also represents the resistance for the transmission of the data or data signals on the outer or phase conductor L. The neutral conductor is represented by the line resistances R or R2. The resistance R2 is also the resistance for the transmission of the data signals on the neutral conductor N. The protective earth conductor PE know the symbolic line resistances RL. Furthermore, the arrangement according to the invention consists of two exemplary communication units KEl, KE2, although more than two communication units can be provided. In the arrangement shown by way of example in FIG. 1, a first communication unit KE1 is used, for example, as a signal transmitter, and a second communication unit KE2 is used, for example, as a signal receiver. For example, so-called field devices (FID), transmitting / receiving units for industrial controls or transmitting / receiving units for so-called powerline communication (eg PLC adapter, PLC modem, etc.) can be used as communication units KE1, KE2. For an emkopplung of data signals, a first isolation transformer Tl is provided on the side of the first communication unit KE1. On the receiver side or on the side of the second communication unit KE2, the coupling to the power supply network or to the outer conductor L and the neutral conductor N is also carried out via a second isolation transformer T2. By using the first or second isolating transformer T1, T2, a symmetrical transmission system is formed by the communication units KE1, KE2 with the power supply network or with the outer conductor L and the neutral conductor N. This means that the data or data signals are coupled via the isolating transformers Tl, T2 on outer conductor L and neutral conductor N as a signal line or coupled and transferred to this parallel. Instead of isolating transformers Tl, T2, it is also conceivable for the coupling of the communication units KE1, KE2 high-voltage capacitors with symmetrical output stage to use.

By means of the isolating transformers T1, T2 or also by high-voltage capacitors with a symmetrical output stage, it is ensured that the respective communication unit KE1 or KE2 is potential-free. The communication units KE1, KE2 thus have an internal signal reference potential S1, S2. The first communication unit KE1 in this case has a first internal signal reference potential S1. The second communication unit KE2 has a second internal signal reference potential S2. The signal reference potentials S1, S2 can also be regarded as so-called device ground and are each designed as ground connections for a connection VI, V2 with the communication unit KE1, KE2 with the protective earth conductor PE. The signal reference potentials S1, S2 can additionally be connected to the embodiment as a ground connection or alternatively to a housing of the respective communication unit KE1, KE2. The housing of the communication unit KE1, KE2 is then ideally made of metal, in which case, for example, the housing of the respective communication unit KE1, KE2 can be used for the connection VI, V2 to the protective earth conductor PE. In the example of the arrangement according to the invention shown in FIG. 1, the first communication unit KE1 or the first signal reference potential of the first communication unit KE1 is connected to the protective earth conductor PE via a first connection VI, ie either a ground connection or via the metallic housing of the first communication unit KE1 connected. The second communication unit KE2 has the second signal reference potential S2, which is connected to the protective earth conductor PE via a second connection V2 (eg ground connection and / or metallic housing).

Through the connections VI, V2 of the signal reference potentials S1, S2 of the communication units KE1, KE2 to the protective earth conductor PE, the protective earth conductor PE is coupled by parasitic coupling capacitances C existing in the power supply network to the neutral conductor N as well as to the outer conductor L. This implements a distributed phase coupling for the symmetrical transmission system formed by communication units KE1, KE2 and outer conductor L and neutral conductor N.

If, in a transmission, e.g. the neutral conductor N is disturbed or interrupted - that is to say that the resistor R 1 would be missing, for example, in the arrangement according to the invention a capacitive coupling C between the protective earth conductor PE and the neutral conductor N ensures that a transmission is possible without interference. If, in the case of a transmission of data or data signals, the outgoing conductor L is interrupted or absent because the second communication unit KE2 is coupled to another phase conductor L of the polyphase system (ie in both cases the resistor R2 is missing), a capacitive coupling C between them Protective earth conductor PE and the outer conductors L of the power supply network, the transmission of data or data signals still allows.

Due to the capacitive phase coupling C between protective earth conductor PE and outer conductor L or neutral conductor N, which by the connections VI, V2 of the communication units KE1, KE2 is made with the protective earth conductor PE, the position of an interruption or disturbance in the neutral conductor N or outer conductor L is irrelevant for the transmission of the data or data signals. In multi-phase systems, it also does not matter to which outer conductor L the respective communication unit KE1, KE2 is coupled. It is possible without any additional effort or precise prior planning to couple the communication units KE1, KE2 as desired to the power supply network for the data transmission. The data transmission is disturbed, hindered or interrupted by the use of the arrangement according to the invention neither by interruptions to neutral N or outer conductor L nor by using different outer conductor L.

As an alternative to a connection VI, V2 of the communication units KE1, KE2 with the protective earth conductor PE of the power supply network, it is also conceivable to use metallic infrastructure elements (for example water pipe, etc.) for this connection VI, V2. The signal reference potential S1, S2 of the respective communication unit KE1, KE2 is then connected to the corresponding metallic infrastructure element via the respective earth connection and / or the respective housing of the communication unit KE1, KE2.

Claims

claims

1. Arrangement for transmitting data in a power supply network (N, L), in particular for so-called powerline communication, with at least two communication units

(KE1, KE2) as a signal transmitter and / or signal receiver and a power supply network (N, L), via which data can be transmitted by a modulated onto a carrier frequency data signal between the at least two Kommunikationsseinhei- thes (KE1, KE2), characterized in that each Communication unit (KE1, KE2) has a signal reference potential (Sl, S2), and that a connection (VI, V2) between each signal reference potential (Sl, S2) and at least one protective earth conductor (PE) of the power supply network (L, N) is provided.

2. Arrangement according to claim 1, characterized in that the connection (VI, V2) with the protective earth conductor (PE) of the power supply network (L, N) is designed as grounding connection.

3. Arrangement according to one of claims 1 to 2, characterized

in that the communication units (KE1, KE2) each have a housing made of metal, which for connection (VI, V2) to the protective earth conductor

(PE) of the power grid (L, N) is usable.

4. Arrangement according to one of claims 1 to 3, characterized

in that an isolating transformer (T1, T2) is provided for inputting and decoupling the data signals into the power supply network (L, N).

5. Arrangement according to one of claims 1 to 3, characterized

characterized in that for an input and a decoupling of the data signals into the power supply network (L, N)

High-voltage capacitors are provided with balanced amplifiers.