DE102016119877A1 - Device for detection and communication - Google Patents

Abstract

The invention relates to a device (1) for detecting AC signals from a DC circuit of a circuit unit and having communication, a first (2.1) and a second terminal (2.2) for connection to the DC circuit of the circuit unit, a transformer (7) a primary winding (71p) arranged on a primary side (7p) of the transformer (7) and a secondary winding (71s) arranged on a secondary side (7s) of the transformer (7), wherein the first terminal (2.1) is connected via a series circuit of a capacitor (7) 6) and the secondary winding (71s) of the transformer (7) to the second terminal (2.2) is connected, a communication unit (8) which is designed to generate an AC signal as a communication signal and via the transformer (7) in the DC coupling circuit of the circuit unit, a detection unit (9) which is designed to receive a via the transformer (7) coupled out of the DC circuit AC signal n and to process, wherein the communication unit (8) and the detection unit (9) are connected in common to the primary side (7p) of the transformer (7), anda controller (10) for controlling the communication unit (8) and the detection unit (9) , characterized in that the controller (10) is adapted to put the communication unit (8) and the detection unit (9) respectively in an activated and a deactivated state, wherein a coupling of the communication signal only in the activated state of the communication unit (8) wherein reception and / or processing of the AC signal takes place only in the activated state of the detection unit (9), and

Description

TECHNICAL FIELD OF THE INVENTION

The invention relates to a device for detecting AC signals from a DC circuit of a circuit unit and for communication by means of coupled for the purpose of communication in the DC circuit of the circuit unit AC signals. The invention further relates to a photovoltaic (PV) system as a circuit unit with a DC circuit having a device according to the invention.

Conventional measuring devices often offer the possibility, in addition to detecting or measuring a physical quantity, to communicate the measurement results and / or a signal resulting from the measurement results to a higher-order control unit. Therefore, such measuring devices in addition to a detection unit, which operatively takes over the detection and evaluation of the variable to be measured, additionally a communication unit which is connected for the purpose of data exchange with the parent control unit and communicates with these measurement results, signals but also control instructions. In particular, the detection unit of the device according to the invention is designed to receive and process an AC signal coupled out of the DC circuit of the circuit unit. Such a detection unit can be formed, for example, by an arc detection unit which monitors the DC circuit of the circuit unit connected to the device for the eventual occurrence of an electric arc. Here, the property is exploited that an arc generates a high-frequency AC signal - the so-called arc noise - in the arc affected by the electric circuit. Likewise, the communication unit is adapted to couple an AC signal for the purpose of communication as a communication signal in the DC circuit of the circuit unit. Such a communication unit can be designed, for example, to carry out a so-called power-line communication (PLC), wherein information to be communicated is transmitted via a suitable modulation method - e.g. a frequency and / or amplitude modulation - the injected AC signal is impressed. A communication unit designed for the PLC uses lines of the DC circuit already present for energy transmission, which is why no additional communication lines have to be provided for connecting the device.

STATE OF THE ART

The DE 10 2013 108 166 A1 discloses an apparatus for detecting AC components of an electrical current flowing in a DC circuit. The device comprises an inductance arranged in the DC circuit, an AC path arranged electrically parallel to the inductance, which comprises a series connection of a capacitance and a primary-side winding of a transformer, and a voltage measuring device. A secondary-side winding of the transformer is connected via a low-pass circuit with the voltage measuring device. The device can be used for the detection of arcs and / or communication signals in a photovoltaic system.

From the DE 10 2012 112 921 A1 a circuit arrangement for coupling a high frequency (RF) signal for data transmission on DC lines of a photovoltaic system is known. The circuit arrangement comprises a signal generator for generating an RF signal, a coupling transformer having a primary winding and a secondary winding, and a looped into the DC circuit blocking member, such as an inductor. The signal generator is connected to the primary winding, a series circuit of the secondary winding and a capacitor is connected in parallel with the blocking member.

If both the device for detecting electric arcs and the circuit arrangement for coupling high-frequency signals are operated together in a DC circuit of a photovoltaic system, then the coupled-in RF signals can interfere with the arc detection. This is the case in particular when a frequency of the RF signal for data transmission corresponds at least approximately to a frequency of the alternating current component to be detected for arc detection. Furthermore, a simultaneous provision of both the device and the circuit arrangement requires a large space and is also associated with relatively high costs.

OBJECT OF THE INVENTION

The invention has for its object to provide a device for detection and communication according to the preamble of independent claim 1, which is designed on the one hand to decouple and process an AC signal from a DC circuit of a circuit unit connected to the device, and on the other hand is designed to generate an AC signal as a communication signal and to couple it into the DC circuit of the circuit unit. In this case, a disturbing influence between the detection and the communication unit should be excluded as far as possible, or at least significantly reduced. In addition, the device should be as possible have compact design and be as inexpensive as possible. The invention is further based on the object to show a photovoltaic (PV) system with such a device.

SOLUTION

The object of the invention is achieved by a device having the features of independent claim 1. The dependent claims 2 to 13 are directed to preferred embodiments of the device. The independent claim 14 relates to a photovoltaic (PV) system as a circuit unit with a DC circuit and a device connected to the DC circuit according to the invention. The dependent claims 15 to 16 relate to advantageous embodiments of the photovoltaic (PV) system.

DESCRIPTION OF THE INVENTION

• - einen ersten und einen zweiten Anschluss zum Anschluss an den Gleichstromkreis der Schaltungseinheit,
• - einen Übertrager mit einer auf einer Primärseite des Übertragers angeordneten Primärwicklung und einer auf einer Sekundärseite des Übertragers angeordneten Sekundärwicklung, wobei der erste Anschluss über eine Reihenschaltung aus einem Kondensator und der Sekundärwicklung des Übertragers mit dem zweiten Anschluss verbunden ist,
• - eine Kommunikationseinheit, die ausgelegt ist, ein AC-Signal als Kommunikationssignal zu erzeugen und über den Übertrager in den Gleichstromkreis der Schaltungseinheit einzukoppeln,
• - eine Detektionseinheit, die ausgelegt ist, ein über den Übertrager aus dem Gleichstromkreis ausgekoppeltes AC-Signal zu empfangen und zu verarbeiten,
• - wobei die Kommunikationseinheit und die Detektionseinheit gemeinsam an die Primärseite des Übertragers angeschlossen sind. Die Vorrichtung weist weiterhin eine Steuerung zur Steuerung der Kommunikationseinheit und der Detektionseinheit auf und ist dadurch gekennzeichnet,
• - dass die Steuerung ausgelegt ist, die Kommunikationseinheit und die Detektionseinheit jeweils in einen aktivierten und einen deaktivierten Zustand zu versetzen,
• - wobei eine Einkopplung des Kommunikationssignales durch die Kommunikationseinheit nur im aktivierten Zustand der Kommunikationseinheit erfolgt, und
• - wobei ein Empfang und/oder eine Verarbeitung des AC-Signales durch die Detektionseinheit nur im aktivierten Zustand der Detektionseinheit erfolgt. Dabei ist die Steuerung ausgelegt, die Zustände der Kommunikationseinheit und der Detektionseinheit derart zu steuern, dass zu jedem Zeitpunkt höchstens eine Einheit aus Kommunikationseinheit und Detektionseinheit in dem aktivierten Zustand ist.

An inventive device for detecting AC signals from a DC circuit of a circuit unit and for communication includes:

• a first and a second terminal for connection to the DC circuit of the circuit unit,
• a transformer having a primary winding arranged on a primary side of the transformer and a secondary winding arranged on a secondary side of the transformer, the first connection being connected to the second connection via a series connection of a capacitor and the secondary winding of the transformer,
• a communication unit which is designed to generate an AC signal as a communication signal and to couple it via the transformer into the DC circuit of the circuit unit,
• a detection unit which is designed to receive and process an AC signal coupled out of the DC circuit via the transformer,
• - Wherein the communication unit and the detection unit are connected in common to the primary side of the transformer. The apparatus further comprises a controller for controlling the communication unit and the detection unit, and is characterized
• in that the controller is designed to set the communication unit and the detection unit respectively in an activated and a deactivated state,
• - Wherein a coupling of the communication signal by the communication unit takes place only in the activated state of the communication unit, and
• - Receiving and / or processing of the AC signal by the detection unit is carried out only in the activated state of the detection unit. In this case, the controller is designed to control the states of the communication unit and of the detection unit in such a way that at most one unit of communication unit and detection unit is in the activated state at any one time.

By the detection unit and the communication unit are connected in common to the primary side of the same transformer, the decoupling of the AC signal to be detected, as well as the coupling of the AC signal to be communicated via the same transmitter takes place. Therefore, the transformer is to be provided only once within the device. However, this requires that the coupling of an AC signal generated by the communication unit as a communication signal via the transmitter at the same time superimposed on any existing and to be detected by the detection unit AC signal. Due to this, on the one hand the communication signal can be misinterpreted as an arcing signal. In addition, there is also the risk that an actually existing arc is not detected due to the superimposition of the communication signal and the arc signal emitted by the arc. In any case, there is a risk of misinterpretation of the AC signals detected by the detection unit. According to the invention, this misinterpretation of the AC signals detected by the detection unit in the device is eliminated by the two common control units. Thus, the controller for controlling the detection unit and the communication unit is configured to respectively set the communication unit and the detection unit in an activated and a deactivated state, such that at most one unit of communication and detection unit is in the activated state. In this way, first time periods are generated in which the detection unit, but not the communication unit is activated. Furthermore, second time periods are generated in which the communication unit, but not the detection unit is activated. The coupling of the communication signal through the communication unit takes place only in their activated - but not in their deactivated state. Accordingly, the detection and / or processing of the AC signal by the detection unit takes place only in the activated - but not in the deactivated state of the detection unit. Thus, a coupling of the communication signal is suppressed within the first period and therefore can not be misinterpreted in the reception and / or processing of the DC circuit cause disconnected AC signals within the detection unit. In the same way, it is ensured that within the second time periods within which a generation and coupling of the communication signal via the transmitter takes place, no reception and / or no processing of a possibly received AC signal by the detection unit takes place. A deactivated state of the detection unit can be easily brought about via the controller by the controller blocking the processing of AC signals by the detection unit for the corresponding period of time. In principle, a reception of AC signals by the detection unit can remain. Accordingly, an activated state of the detection unit can be brought about via the controller by the controller enabling or allowing the processing for the corresponding period of time. Accordingly, the controller may bring about the deactivated state of the communication unit by blocking the generation of the communication signal within the corresponding period of time. Likewise, it can bring about the deactivated state of the communication unit by allowing the generation of the communication signal within the respective period of time. Alternatively or cumulatively thereto, an activation and deactivation of the detection and / or communication unit can also take place via corresponding switches which, for example, prevent the reception of the AC signal at the detection unit or an output or the transmission of the communication signal of the communication unit.

The first and second periods follow one after the other alternately. In this case, the alternate activation or deactivation of both units - ie the switching from one state to the other - simultaneously and without time offset to each other. In this case, virtually every time a unit of communication and detection unit is activated. However, the alternate activation or deactivation of the detection and the communication unit can also be done with a time offset to each other. In this case, there are periods in which no unit of detection and communication unit is activated. The first and the second time periods are advantageously in a range from 1 ms to 2000 ms, particularly advantageously in a range from 5 ms to 1000 ms. They can have the same time durations relative to one another but also different durations of time.

Both the number and the design of the transformer significantly affect the design and thus the cost of the detection and communication device. A current flowing in the DC circuits in question is usually composed of a relatively high DC component and a comparatively small AC component. Although a high DC component can flow within the DC circuit, the device prevents the flow of a DC component through the secondary winding of the transformer due to the capacitor connected in series thereto. Rather, only AC signals whose frequency is within a preferred frequency range, passed through the secondary winding of the transformer by the series circuit of capacitor and secondary winding of the transformer. Since these are typically low-current AC signals, the transformer design can be made compact and inexpensive. In addition, since only one transformer is to be provided within the device, the entire device can also be kept compact and inexpensive. Other components that affect an activation and deactivation in an advantageous manner lead only apparently to a higher cost, as this is overcompensated by the advantageous construction of the transformer.

In one embodiment of the device, the transformer has, in addition to the primary winding, a further primary winding on the primary side. In this case, the communication unit is connected to the primary winding and the detection unit to the further primary winding. The embodiment may, but not necessarily, have a galvanic connection between the primary winding and the further primary winding. Such a connection can be formed for example by a common reference potential.

In an alternative embodiment of the device, the transformer has only a primary winding on its primary side. In this case, the communication unit and the detection unit are connected to the same primary winding of the transformer. It is possible that the communication unit and the detection unit are connected in parallel to each other to the same primary winding of the transformer. Alternatively, it is possible that the communication unit and the detection unit are connected in series with the same primary winding of the transformer. Since the detection unit and the communication unit are connected to the same primary winding, a galvanic connection between the detection unit and the communication unit is usually present, which can be used, for example, as a common reference potential.

In an advantageous embodiment of the device, the detection unit is designed to detect an arc in the DC circuit of the circuit unit. This is exploited that an arc generates a so-called arc noise in the circuit affected by it. The arc noise is a mixture of high-frequency AC signals with frequencies within a frequency range of about 1 kHz - 500 kHz. For arc detection, the DC circuit to be monitored for an arc is monitored for the existence of one AC signal or several AC signals of different frequencies within this frequency range. The high-frequency AC signal may be either an AC signal or an AC signal. The one or more possibly existing AC signals are decoupled by the transformer from the DC circuit connected to the device and provided for processing via the primary winding or the further primary winding of the detection unit. If a corresponding AC signal or corresponding AC signals are detected, this is interpreted as an indication of the existence of an arc in the DC circuit. Advantageously, a threshold value is stored within the detection unit, wherein when an AC signal detected by the detection unit exceeds the threshold value with respect to its intensity (eg, current or voltage), this is considered to be an arc in the DC circuit. In this case, a pattern recognition of the AC signals detected by the detection unit can be carried out as a plausibility check for the existence of an arc. In this way, a distinction can be made as to whether the AC signals detected by the detection unit are in fact to be assigned to an arc or to another interference event. Advantageously, the detection unit is designed as disclosed in WO 2015/014683 A1, and has a termination resistor connected in parallel with an input of the detection unit and a low-pass filter. The output of the low-pass filter is connected to a voltage measuring device, which in turn is coupled to an evaluation device. The detection unit may be configured to signal a result of the processing of the control. The controller, in turn, may cause the communication unit to communicate an alarm signal to a higher-level controller if there is an indication of an arc.

In an advantageous embodiment of the device, the communication unit or the detection unit is additionally designed for receiving and processing a decoupled via the transformer from the DC circuit further communication signal. The communication signal is also an AC signal, which is coupled from another unit, such as a higher-level controller in the DC circuit. In this way results in a bidirectional communication of the device with the higher-level control, in which the device can operate both as a receiver and as a transmitter in the context of communication. It is particularly advantageous if the detection unit is designed for receiving and processing the further communication signal, and it operates quasi in the context of bidirectional communication as a receiver of the further communication signal, while the communication unit as part of the bidirectional communication of the device with the other unit Sender of the communication signal operates. This design is particularly simple and inexpensive to implement, since the detection unit is designed anyway to receive and process the AC signal to be detected. For this reason, only little effort is required to get the detection unit to receive and process the further communication signal.

If the device is designed for bidirectional communication, in an advantageous embodiment, the communication unit or the detection unit is designed to pass on the further communication signal to the controller. Likewise, the controller is designed to control the detection unit and / or the communication unit as a function of the further communication signal. For example, the superordinate controller can remotely control the device by sending control commands in conjunction with the controller. Corresponding control commands may relate to the times for activating and / or deactivating the detection unit and / or the communication unit. Likewise, further parameters of the detection unit - for example the above-mentioned threshold value - can be communicated and set. The higher-level control can likewise remotely control further components present in the device, if appropriate together with the control. This can e.g. possibly existing in the device switch.

In one embodiment, the device further comprises a blocking member, which is connected in parallel to the series circuit of capacitor and secondary winding. The blocking member may be an inductance or a band-stop filter. This is particularly advantageous if a direct current as low impedance as possible from the first to the second terminal of the device, but not to be routed through the secondary winding of the transformer. This is the case, for example, if the device is arranged within a DC line of the DC circuit and should not interrupt the DC current flowing in the DC line. Within the DC circuits in question, a current typically flows with a relatively high DC component and a relatively low AC component. In this case, the alternating current component results, for example, from the deliberate coupling of the AC signal as a communication signal and / or from the existence of an AC signal to be detected in the DC circuit-for example as a result of an electric arc. In the case of the blocking element connected between the first and the second terminal, the DC component flows through the blocking element which is low-impedance for it, while the alternating current component-that is to say the AC signals to be detected, the communication signal and the further communication signal-is conducted via the series circuit of capacitor and secondary winding of the transformer become.

In an advantageous embodiment of the device, the capacitor and the secondary winding of the transformer are selected such that their series circuit at a frequency of the communication signal and / or the further communication signal has a resonant frequency - that is, an impedance minimum. In this way, the series connection is particularly low-impedance for AC signals having the frequency near the frequency of the communication signal or that of the further communication signal. Therefore, the communication signals can pass through the device between the first and the second connection as unhindered as possible. However, it is also within the scope of the invention that the communication signal has a frequency which differs from the resonant frequency of the series circuit of capacitor and secondary winding of the transformer. In this case, there is a somewhat greater attenuation of the communication signal and / or the further communication signal through the impedance of the series connection. Furthermore, however, a DC component is prevented by the secondary winding of the transformer by the capacitor.

In the event that the detection unit and the communication unit are connected in the form of a series circuit with the same primary winding of the transformer, the device in an advantageous embodiment additionally has a controllable by the controller first switch, which is designed, a first and a second signal terminal of Detection unit to connect or disconnect from each other. In this case, the device can optionally additionally have a second switch that can be controlled by the controller and that is designed to connect or disconnect a first and a second signal terminal of the communication unit. In this way, a deactivated state of the detection unit can be realized in a simple manner by short-circuiting the first and second signal terminals of the detection unit by closing the first switch. The reception of corresponding AC signals by the detection unit is thus blocked. Conversely, in the activated state of the detection unit, the first switch is opened and the reception of possibly existing AC signals by the detection unit is ensured. The same applies in a corresponding manner for the communication unit in conjunction with the second switch. In the deactivated state of the communication unit, a closed second switch blocks an injection of the communication signal, while in the activated state of the communication unit an opened second switch permits this.

In an alternative embodiment, when the detection unit and the communication unit are connected in series, the apparatus additionally has a first switch which can be controlled by the controller and is designed to connect or disconnect a first and a second signal terminal of the detection unit via a second capacitor. Furthermore, the device additionally has a controllable by the controller second switch, which is designed to connect a first signal terminal of the communication unit via a diode and a third capacitor to a DC voltage source or to separate from each other. The DC voltage source is used in conjunction with the second switch to shift at certain times a potential on the primary side of the transformer relative to a reference potential by an output voltage of the DC voltage source. Thus, lifting takes place when the second switch is closed when the detection unit is activated, while when the communication unit is activated the second switch is open and there is no lifting of the potential on the primary side. As in the description of the figures for 1b is explained in detail, can be realized in this way, the first and second switch particularly cost. In this case, the DC voltage source is not a separate component in most cases, but - for example, to supply the device - already exists.

Generally, the first and second switches may be electromechanical switches - e.g. Act relay or semiconductor switch. In the case of semiconductor switches, it should be noted that these are designed during their operation to block in both directions. If necessary, it is necessary for this purpose to implement the first and the second switch in each case in the form of two semiconductor switches which are connected in antiserial manner with respect to their intrinsic diode. However, in the latter embodiment, due to the temporary potential shift, it is possible to realize the first and second switches in the form of only one semiconductor switch.

In the event that the detection unit and the communication unit are connected in parallel to the same primary winding of the transformer, an advantageous embodiment of the device in addition to a controllable by the controller third switch, which is designed to connect the detection unit, in particular a signal terminal of the detection unit to the primary winding or to separate from each other. In the event that the communication unit to the primary winding and the detection unit are connected to the further primary winding of the transformer, an advantageous embodiment of the device additionally comprises a controllable by the third control switch, which is designed, the detection unit, or a signal terminal of the detection unit to connect or disconnect with the other primary winding. In both embodiments, the device may optionally additionally comprise a controllable by the controller fourth switch which is designed to connect the communication unit, in particular a signal terminal of the communication unit to the primary winding or separate from each other. In these cases, in each case a deactivated state of the detection unit is brought about via an open third switch, whereby the reception of an AC signal to be detected by the detection unit is prevented. An activated state of the detection unit is present when the third switch is closed. Analogous considerations apply to the activated state of the communication unit in conjunction with the fourth switch. An activated state of the communication unit is present when the fourth switch is closed, a deactivated state of the communication unit when the fourth switch is open. The third and the fourth switch may be electromechanical switches - eg relays - or semiconductor switches.

A photovoltaic (PV) plant according to the invention has a DC circuit. The DC circuit includes a photovoltaic (PV) generator, a positive DC link, a negative DC link and a DC input of an inverter. The DC input of the inverter is connected to the PV generator via the positive and the negative DC connection line. The inverter is designed to convert DC to AC and has its output connected to an AC grid. The photovoltaic (PV) system is characterized in that the DC circuit of the photovoltaic (PV) system further comprises a device according to the invention. This results in the advantages already mentioned in the description of the device.

In one embodiment of the PV system, the device is arranged within one of the DC connection lines, which connects one pole of the PV generator to a DC input connection of the inverter. In this case, the first and the second terminal of the device is only connected to one of the DC connection lines, either exclusively with the positive or exclusively with the negative DC connection line. In this case, it is desired that the DC component can pass through the device from the first terminal to the second terminal as unhindered as possible. Therefore, in this embodiment of the PV system, the device has a blocking member which connects the first terminal to the second terminal of the device and is connected in parallel with the series circuit of capacitor and secondary winding. The blocking member may be formed by an inductance or a band-stop filter.

In an alternative embodiment of the PV system, the device is connected with the first connection to the positive DC connection line and with the second connection to the negative DC connection line. In this embodiment of the PV system, it is undesirable for the DC component to pass unimpededly through the device from the first connection to the second connection, since in this way a short circuit of the PV generator would be generated. Accordingly, it is desirable here that the device for the DC component has the highest possible impedance. Only AC signals, for example the communication signal, the further communication signal and the AC signal to be detected should be able to pass through the device as unhindered as possible. Therefore, in this embodiment of the PV system, the device does not have a blocking member in parallel with the series circuit of capacitor and secondary winding. In this way, the capacitor prevents the DC component from passing unimpeded from the first terminal to the second terminal and the device has a high impedance for the DC component.

list of figures

• 1a zeigt eine erste Ausführungsform der erfindungsgemäßen Vorrichtung, bei der die Detektionseinheit und die Kommunikationseinheit in Form einer Reihenschaltung mit derselben Primärwicklung verbunden sind in einer ersten Variante; und
• 1b zeigt eine weitere Ausführungsform der erfindungsgemäßen Vorrichtung, bei der die Detektionseinheit und die Kommunikationseinheit in Form einer Reihenschaltung mit derselben Primärwicklung verbunden sind; und
• 2a zeigt eine zweite Ausführungsform der erfindungsgemäßen Vorrichtung, bei der die Detektionseinheit und die Kommunikationseinheit parallel zueinander an dieselbe Primärwicklung angeschlossen sind; und
• 2b zeigt eine dritte Ausführungsform der erfindungsgemäßen Vorrichtung, bei der die Detektionseinheit und die Kommunikationseinheit parallel zueinander an dieselbe Primärwicklung angeschlossen sind; und
• 3 zeigt eine vierte Ausführungsform der erfindungsgemäßen Vorrichtung, wobei ein Übertrager auf einer Primärseite eine Primärwicklung und eine weitere Primärwicklung aufweist; und
• 4 zeigt Zustandsverläufe der Kommunikationseinheit und der Detektionseinheit; und
• 5a zeigt eine erste Ausführungsform einer erfindungsgemäßen Photovoltaik (PV)-Anlage; und
• 5b zeigt eine zweite Ausführungsform einer erfindungsgemäßen Photovoltaik (PV)-Anlage

In the following the invention will be further explained and described with reference to preferred embodiments shown in the figures.

• 1a shows a first embodiment of the device according to the invention, in which the detection unit and the communication unit are connected in the form of a series circuit with the same primary winding in a first variant; and
• 1b shows a further embodiment of the device according to the invention, in which the detection unit and the communication unit are connected in the form of a series circuit with the same primary winding; and
• 2a shows a second embodiment of the device according to the invention, in which the Detection unit and the communication unit are connected in parallel to each other to the same primary winding; and
• 2 B shows a third embodiment of the device according to the invention, in which the detection unit and the communication unit are connected in parallel to each other to the same primary winding; and
• 3 shows a fourth embodiment of the device according to the invention, wherein a transformer on a primary side has a primary winding and a further primary winding; and
• 4 shows state curves of the communication unit and the detection unit; and
• 5a shows a first embodiment of a photovoltaic (PV) plant according to the invention; and
• 5b shows a second embodiment of a photovoltaic (PV) plant according to the invention

DESCRIPTION OF THE FIGURES

In 1a is a first embodiment of the device according to the invention 1 for detecting AC signals from a DC circuit of a circuit unit and for communication. The device 1 has a first 2.1 and a second connection 2.2 for connecting the DC circuit. The device 1 also has a communication unit 8th with a first 18.1 and a second signal terminal 18.2, a detection unit 9 with a first 19.1 and a second signal terminal 19.2 and a transformer 7 with a primary winding 71p on a primary page 7p and a secondary winding 71s on a secondary side 7s of the transformer 7 on. The transformer 7 is designed for coupling and decoupling of AC signals in and out of the DC circuit of the circuit unit. The communication unit 9 is designed to generate an AC signal as a communication signal and via the transmitter 7 to couple into the DC circuit. The detection unit 9 is designed, one from the DC circuit via the transformer 7 receive and process the decoupled AC signal. The communication unit 8th and the detection unit 9 are in the form of a series connection with the same primary winding 71p of the transformer 7 connected. Furthermore, the device includes 1 a controller 10 for controlling the communication unit 9 and the detection unit 8th that is designed, each of the units 8th . 9 to put each in an activated and a deactivated state. The device 1 has one through the controller 10 controllable first switch 11.1. The first switch 11.1 is designed, the first signal terminal 19.1 and the second signal terminal 19.2 of the detection unit 9 low-impedance connection to each other - and thus the signal terminals 19.1, 19.2 of the detection unit 9 to bridge - or to separate from each other. Furthermore, the device 1 one by the controller 10 drivable second switch 11.2, which is designed, the first 18.1 and the second signal terminal 18.2 of the communication unit 8th low-impedance connection to each other - and thus the signal terminals 18.1, 18.2 of the communication unit 8th to bridge - or to separate from each other. The first 11.1 and second switches 11.2 may each comprise a semiconductor switch or an electromechanical switch.

In the illustrated case, the first signal terminal 19.1 of the detection unit 9 and the second signal terminal 18.2 of the communication unit 8th to a reference potential 21 connected. The illustrated connection of the reference potential 21 However, this is only an example and not limiting. Alternatively to the illustrated variant, it is also possible that the reference potential 21 with the first signal terminal 18.1 of the communication unit or with the second signal terminal 19.2 of the detection unit 9 connected is. The first connection 2.1 is via a series connection of a capacitor 6 and the secondary winding 71s of the transformer 7 with the second connection 2.2 the device 1 connected. Parallel to the series connection of capacitor 6 and secondary winding 71s is a locking member 5 connected. The locking member 5 is realized here in the form of an inductance. However, it is also possible that the locking member 5 is formed by a band-stop filter. Likewise it is possible that the device 1 no locking link 5 that has the first port 2.1 with the second connection 2.2 combines.

In operation of the device 1 become the communication unit 8th and the detection unit 9 through the controller 10 are alternately set to an activated and a deactivated state, so that when the detection unit 9 in the activated state is the communication unit 8th is in the deactivated state. In particular, there is at most one of the units at any one time 8th . 9 in the activated state. Here is the communication unit 8th designed to perform a generation and / or coupling of the communication signal only in the activated state - but not in the deactivated state. For this purpose, in the deactivated state of the communication unit 8th the second switch 11.2 through the controller 10 closed while in the activated state of the communication unit 8th through the controller 10 is open. As a result, a coupling of the communication signal via the transformer 7 prevented in the DC circuit. In addition, through the controller 10 a generation of the communication signal by the communication unit 8th be suppressed. Both measures (ie "suppression of Generation of the communication signal "and" closing the second switch 11.2 ") each lead to a deactivation of the communication unit 8th and are so far redundant to each other. Although within the scope of the invention already one of the measures for deactivating the communication unit 8th is sufficient here, the redundancy of a one-fault security, which also in case of failure of one of the measures to deactivate the communication unit 8th leads.

Furthermore, the detection unit 9 designed to receive and / or process a decoupled from the DC circuit AC signal only in its activated state, but not in its deactivated state. For this purpose, in the deactivated state of the detection unit 9 the processing of possibly over the transformer 7 decoupled AC signal by the controller 10 suppressed. In addition, the first switch 11.1 - driven by the controller 10 - closed while in the activated state of the detection unit 9 - controlled by the controller 10 - is open. Also with the detection unit 9 Both measures (ie "suppression of processing" and "closing the first switch 11.1") in each case already lead to a deactivation of the detection unit 9 Therefore, one of the measures is already sufficient in the context of the invention. The redundancy is here - analogous to the communication unit 8th - chosen due to the one-fault-safety. That's the one from the detection unit 9 AC signals to be detected are usually small compared to those of the communication unit 8th generated communication signals is the detection unit 9 protected by the closed first switch 11.1 at the same time against overdriving and an associated eventual damage. Furthermore, this is done by the communication unit 8th not additionally generated by an input impedance of the detection unit 9 attenuated. Rather, the generated communication signal via the closed first switch 11.1 low-impedance to the detection unit 9 passed by.

In this way, first time periods arise, within which the detection unit 8th possibly received and processed in the DC circuit and decoupled AC signals. This is followed by second periods in which the detection unit 8th is disabled and due to the closed first switch 11.1 can not receive AC signals while the communication unit 8th in the activated state communication signals via the transmitter 7 coupled into the DC circuit. Since the first 19.1 and the second signal terminal 19.2 of the detection unit 8th is bridged low impedance by the first switch 11.1, an attenuation of the communication signal by an input impedance of the detection unit 9 prevented. Likewise, the input of the detection unit 9 protected against overdriving and associated eventual damage by the communication signal.

The 1b shows a further variant of the device 1 , which is largely the embodiment of the 1a is similar, so in the following only the differences from the embodiment according to 1a being represented. The same reference numbers indicate in the 1b as well as the following figures the same or equivalent elements. In contrast to 1a has the device 1 a DC voltage source 12 on, which is designed in conjunction with the second switch 11.2 a potential on the primary side 7p of the transformer 7 relative to a voltage value U _{21 of} the reference potential 21 to move temporarily. For this purpose, the first signal terminal 18.1 of the communication unit 8th via a series connection of a third capacitor 24 , a diode 13 and the second switch 11.2 with an output of the DC voltage source 12 connected. Furthermore, the device has a with the second signal terminal 19.2 of the detection unit 9 connected second capacitor 23 on. The first switch 11.1 is on one side with the first signal terminal 19.1 of the detection unit 9 and on the other side with the capacitor 23 connected. When the second switch 11.2 is closed, the potential of the primary side 7p of the transformer 7 relative to the voltage value U _{21 of} the reference potential 21 postponed. The second 23 and the third capacitor block 24 a DC component of the potential-shifted primary side 7p opposite the first signal terminal 18.1 of the communication unit 8th and the second signal terminal 19.2 of the detection unit 9 and thus prevent an override of the units ( 8th . 9 ).

In contrast to the embodiment of the device 1 according to 1a can be in the embodiment according to 1b Both the first 11.1 and the second switch 11.2 in the form of only one semiconductor switch - for example, a MOSFET - realize. To better understand the operation of the device 1 each intrinsic diodes of the respective semiconductor switches 11.1, 11.2 are shown. The diode 13 is antiserially connected to the intrinsic diode of the second semiconductor switch 11.2 with respect to its forward direction. The bidirectional blocking in the open state of the first switch 11.1 is ensured by the fact that the potential shift poles the intrinsic diode of the first semiconductor switch 11.1 in its open state in the reverse direction. For this purpose, advantageously, the potential shift and thus the output voltage U _{12 of} the DC voltage source 12 chosen so that an AC signal to be detected at any time completely above the reference potential 21 with the voltage value U ₂₁ . Here is the voltage drop across the diode 13 with the forward voltage U _{D, 13} and possibly that of the second switch 11.2 to be considered in the conductive state. For the output voltage U _{12 of} the DC voltage source 12 Thus U ₁₂ ≥ U _{0, AC} + U _{D, 13} + U ₂₁ where U _{0, AC} denotes a maximum permitted amplitude of the AC signal to be detected. The maximum permitted amplitude U _{0, AC of} the AC signal to be detected results from the individual design of the detection unit 9 and corresponds to a voltage value whose exceeding at the signal inputs 19.1, 19.2, for example, an override of the detection unit 9 entails. Specifically, the output voltage U _{12 of} the DC voltage source 12 for example, by at least 3.3V above the voltage value U _{21 of} the reference potential 21 lie. With such a choice of the output voltage U _{12 of} the DC voltage source 12 ensures that at a maximum allowable amplitude U _{0, AC} in the amount of 3V of the AC signal to be detected, the intrinsic diode of the first switch 11.1 associated semiconductor switch is always poled in the reverse direction when the forward voltage U _{D, 13 of} the diode 13 is below 0.3V. Therefore, here the first switch 11.1 can be realized in the form of only one semiconductor switch. A bidirectional blocking of the second semiconductor switch 11.2 in its open state takes place via the diode 13 , in particular via the direction of their passage relative to the intrinsic diode of the second semiconductor switch 11.2.

2a shows a second embodiment of the device according to the invention 1 , The basic construction corresponds to the device 1 of the 2a the in 1a illustrated embodiment. Therefore, in terms of the basic structure and the basic operation of the comments below 1a Reference is made and only the differences from the first embodiment are shown below.

Unlike the in 1a illustrated variant are in the device 1 according to 2a the communication unit 8th and the detection unit 9 parallel to each other to the same primary winding 71p of the transformer 7 connected. The device 1 has no first 11.1 and no second switch 11.2, which are designed, respectively, the first 18.1, 19.1 and the second signal terminal 18.2, 19.2 of the communication unit 8th or the detection unit 9 to connect or disconnect from each other. Instead, the device points 1 a third 11.3 and a fourth switch 11.4 on, each via the controller 10 are controllable. In this case, the first signal terminal 19.1 of the detection unit 9 via the third switch 11.3 with the first signal terminal 18.1 of the communication unit 8th connected. Furthermore, the second signal terminal 18.2 of the communication unit 8th via the fourth switch 11.4 with the second signal terminal 19.2 of the detection unit 9 connected. In this way, the third switch 11.3 is designed, the detection unit 9 with the primary winding 71s to connect or disconnect. Likewise, the fourth switch 11.4 is thus designed, the communication unit 8th with the primary winding 71p to connect or disconnect. In the activated state of the communication unit 8th is the fourth switch 11.4 by the controller 10 closed and in the deactivated state of the communication unit 8th open. Furthermore, in the activated state of the detection unit 9 the third switch 11.3 by the controller 10 closed and in the deactivated state of the detection unit 9 open. The third 11.3 and the fourth switch 11.4 may each comprise an electromechanical switch or a semiconductor switch.

Similar to 1a are also here in the operation of the device 1 the communication unit 8th and the detection unit 9 through the controller 10 are alternately set to an activated and a deactivated state, so that when the detection unit 9 in the activated state is the communication unit 8th is in the deactivated state. Due to the condition of the communication unit 8th linked switch position of the fourth switch 11.4 is the communication unit 8th only in the activated - but not in the deactivated state capable of a communication signal via the transmitter 7 to couple into the DC circuit connected to the device. Likewise, due to the condition of the detection unit 9 linked switch position of the third switch 11.3, the detection unit 9 only in the activated state - but not in the deactivated state able to transmit an AC signal via the transformer 7 is decoupled from the DC circuit to receive. In doing so, the controller 10 the detection unit 9 enable processing of an AC signal only in its activated state and suppress it in the deactivated state. The suppression of the processing of the AC signal within the deactivated state of the detection unit 9 through the controller 10 is useful for redundancy reasons, but not absolutely necessary, as the reception of one over the transformer 7 out of the DC circuit coupled AC signal in the deactivated state of the detection unit 9 already prevented due to the opened third switch 11.3. Likewise, a suppression of the generation of a communication signal in the deactivated state of the communication unit 8th for reasons of redundancy, but not necessarily within the scope of the invention, since due to the disabled state of the communication unit opened fourth switch 11.4 a coupling of a possibly within the communication unit 8th generated communication signal is already suppressed.

2 B shows a third embodiment of the device according to the invention 1 , The basic construction corresponds to the device 1 of the 2 B the in 2a illustrated embodiment. Therefore, in terms of the basic structure and the basic operation of the comments below 2a Reference is made and only the differences from the second embodiment are shown below.

• - einerseits das Kommunikationssignal ausreichend zu dämpfen und somit eine Übersteuerung der Detektionseinheit 9 zu vermeiden, und
• - andererseits über den Übertrager 7 aus dem Gleichstromkreis ausgekoppelte AC-Signale, sofern deren Frequenz einen ausreichenden Abstand zur Kommunikationsfrequenz aufweisen, noch in einer Stärke zu empfangen, die eine weitere Verarbeitung ermöglicht. Das Bezugspotential 21 ist beispielhaft mit dem zweiten Signalanschluss 18.2 der Kommunikationseinheit 8 und dem zweiten Signalanschluss 19.2 der Detektionseinheit 9 verbunden.

In contrast to 2a shows the third embodiment according to 2 B no third 11.3 and no fourth switch 11.4 on. Instead, a signal terminal - here the first signal terminal 19.1 - the detection unit 9 via a band-stop filter 20 with the primary winding 71p of the transformer 7 connected. Alternatively to the illustrated variant, however, it is also possible that the band-stop filter within a connecting line of the second signal terminal 19.2 of the detection unit 9 with the primary coil 71p is arranged. The band-stop filter 20 is realized in the form of a parallel connection of an inductance, a capacitor and an ohmic resistance and designed with respect to their impedance maximum to the frequency of the communication signal. The ohmic resistance of the band-stop filter is optional and can be omitted. The band-stop filter 20 has a very pronounced impedance maximum with a high slope and is thus able to:

• - On the one hand sufficient to dampen the communication signal and thus an override of the detection unit 9 to avoid, and
• - On the other hand, via the transformer 7 AC signals coupled out of the DC circuit, provided that their frequency is sufficiently far from the communication frequency, are still received at a level which allows further processing. The reference potential 21 is exemplary with the second signal terminal 18.2 of the communication unit 8th and the second signal terminal 19.2 of the detection unit 9 connected.

In the present embodiment, the disabled state of the communication unit 8th brought about by the generation of the AC signal as a communication signal by the controller 10 is suppressed or avoided and is allowed accordingly in the activated state. The deactivated state of the detection unit 9 is brought about by the processing of an AC signal by the controller 10 is blocked. Accordingly, the activated state of the detection unit 9 brought about by the controller 10 the detection unit allows the processing of an AC signal.

3 shows a fourth embodiment of the device according to the invention 1 , From the basic structure, this resembles the in 2a illustrated embodiment. Therefore, in terms of the basic structure and the basic operation of the comments below 2a Reference is made and only the differences from the embodiment according to 2a shown.

In contrast to 2a The embodiment according to FIG 3 on the primary side of the transformer 7 in addition to the primary winding 71p another primary winding 72p on. Here is the communication unit 8th over one by the controller 10 controllable fourth switch 11.4 with the primary winding 71p and the detection unit 9 over one by the controller 10 controllable third switch 11.3 with the other primary winding 72p connected. This variant allows winding ratios or transmission ratios between the primary side 7p and secondary side 7s of the transformer 7 for the communication unit 8th on the one hand and the detection unit 9 on the other hand interpreted differently to each other. So the detection unit needs 9 due to a desired gain in the coupling of the AC signal to be detected from the DC circuit usually a higher winding ratio between the primary side 7p and secondary side 7s as the communication unit 8th , In the activated state of the communication unit 8th the fourth switch 11.4 is closed while it is open in the deactivated state. The same applies to the activated or deactivated state of the detection unit 9 in conjunction with the third switch 11.3. In the case shown, the primary winding 71p galvanic from the other primary winding 72p separated. In the context of the invention, however, a variant is possible in which a connection of the primary winding 71p , the second signal terminal 18.2 of the communication unit 8th is assigned, with a connection of the other primary winding 72p connected to the first signal terminal 19.1 of the detection unit 9 assigned. This results in a galvanic connection of the primary winding with the other primary winding 72p that optionally with one of the communication unit 8th and the detection unit 9 assigned reference potential (in 3 not shown) can be connected.

Otherwise, the operation of the device corresponds 1 according to 3 the operation of the embodiment according to 2a , which is why reference is made here to the text passages listed there.

In 4 are state histories for the communication unit 8th and the detection unit 9 shown. The state history 32 indicates the time-dependent activation or deactivation state of the communication unit 8th on, while the state history 33 the corresponding time-dependent activation or deactivation state of the detection unit 9 represents. In the case shown, the deactivation times of one of the units 8th . 9 not with the corresponding activation times of the other unit 9 . 8th together and there are time spans 34 where none of the units are from communication unit 8th and detection unit 9 is present in the activated state. Alternative to the illustrated state progressions 32 . 33 However, it is within the scope of the invention also possible that the activation of one of the units 8th . 9 almost simultaneously with the deactivation of the other unit 9 . 8th he follows. In this case, the time periods are 34 while none of the units 8th . 9 is activated, negligible. In any case, however, that at most each time one of the units of communication unit 8th and detection unit 9 is present in the activated state.

In 5a a first embodiment of a photovoltaic (PV) plant according to the invention is shown. The PV system 17 has a DC circuit which is a PV generator 14 , a positive DC link 15 , a negative DC connection line 16 and a DC input of an inverter 3 includes. The inverter 3 is for feeding electrical power to a network 4 connected. In the example shown, it is a single-stage, three-phase inverter 3 , In the context of the invention, however, the inverter may also be single-phase and / or multi-stage (ie with a DC / DC converter arranged between the DC input and the DC-AC converter). The PV system 17 also has a device according to the invention 1 on that with her first 2.1 and her second connection 2.2 to the DC circuit of the PV system 17 is connected as a circuit unit. In the case shown, the device is 1 within the negative DC link 16 the PV system 17 arranged. Alternatively, however, it is also possible that the device 1 inside the positive DC connection line 15 the PV system 17 is arranged. The device 1 indicates as a detection unit 9 an arc detection unit and in the illustrated case corresponds to the second embodiment according to 2a in which the detection unit 9 and the communication unit 8th parallel to each other to the same primary winding 71p of the transformer 7 are connected. Unless the device 1 with her first 2.1 and her second connection 2.2 within one of the DC interconnections 15 . 16 is arranged, it is necessary that the device 1 between the first 2.1 and the second connection 2.2 is designed to be low impedance with respect to a DC component flowing in the DC circuit. For this reason, the device 1 a locking member 5 - here in the form of an inductance - on. The blocking member has a higher impedance with respect to an AC component, for example, an AC signal associated with arc noise and / or a communication signal to be detected. Due to this, an AC component flowing in the DC circuit - and thus the AC signal to be detected - becomes the secondary winding 71s of the transformer 7 directed.

The illustrated embodiment of the device 1 is merely an example. Alternatively, the other embodiments of the device 1 possible, this being due to their arrangement within one of the DC connecting lines 15 . 16 each a locking member 5 between the first connection 2.1 and the second port 2.2 exhibit.

In 5b a second embodiment of a photovoltaic (PV) plant according to the invention is shown. The PV system 17 In terms of its structure corresponds in principle to the first embodiment according to 5a , which is why reference is made to the statements made there in relation to the similarities.

Unlike the first embodiment, the device 1 according to 5b no longer within one of the DC connection lines 15 . 16 but rather between the positive 15 and the negative DC connection line 16 arranged. Specifically, this is the first connection 2.1 the device 1 with the positive DC connection line 15 and the second connection 2.2 the device 1 with the negative DC connection line 16 connected. In this arrangement, it is desirable that the device has the highest possible impedance with respect to the DC component flowing in the DC circuit. Therefore, here the device 1 between the first 2.1 and the second connection 2.2 although the series circuit of capacitor 6 and secondary winding 71s of the transformer 7 but not the blocking element connected in parallel with the series connection 5 , Optionally, the PV system 17 in one of the DC connection lines 15 . 16 - here inside the positive DC connection line 15 - between the connection of the device 1 and the inverter 3 still a band-stop filter 22 or an inductance which ensures that the AC signal to be detected and / or a communication signal as an AC signal via the device 1 - here the series connection of capacitor 6 and secondary winding 71s of the transformer 7 - And not an undesirable parallel to the device 1 switched path is passed.

Again, the illustrated embodiment of the device 1 merely by way of example, and it is alternatively the other embodiments of the device 1 possible. In contrast to 5a However, in this case have the devices 1 due to their arrangement between the positive 15 and the negative DC connecting line 16 each no locking member 5 between the first connection 2.1 and the second port 2.2 on. Rather, the devices in question have 1 in this arrangement within the PV system 17 with respect to a DC component, the highest possible impedance between the first 2.1 and the second connection 2.2 on.

LIST OF REFERENCE NUMBERS

1

contraption

2.1, 2.2

connection

3

inverter

4

network

5

locking member

6

capacitor

7

exchangers

7p

primary

7s

secondary side

71p, 72p

primary

71s

secondary winding

8th

communication unit

9

detection unit

10

control

11.1 - 11.4

switch

12

voltage source

13

diode

14

Photovoltaic (PV) generator

15

DC link

16

DC link

17

Photovoltaic (PV) plant

18

signal connection

19

signal connection

20

bandstop

21

reference potential

22

bandstop

23, 24

capacitor

32, 33

state history

34

Period of time

QUOTES INCLUDE IN THE DESCRIPTION

This list of the documents listed by the applicant has been generated automatically and is included solely for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions.

Cited patent literature

• DE 102013108166 A1 [0003]
• DE 102012112921 A1 [0004]

Claims (16)

Device (1) for detecting AC signals from a DC circuit of a circuit unit and having communication, - a first terminal (2.1) and a second terminal (2.2) for connection to the DC circuit of the circuit unit, - a transformer (7) with a on a primary side (7p) of the transformer (7) arranged primary winding (71p) and arranged on a secondary side (7s) of the transformer (7) secondary winding (71s), wherein the first terminal (2.1) via a series circuit of a capacitor (6 ) and the secondary winding (71s) of the transformer (7) to the second terminal (2.2), - a communication unit (8) which is designed to generate an AC signal as a communication signal and via the transformer (7) in the DC circuit of the circuit unit coupled, - a detection unit (9) which is designed to receive a via the transformer (7) coupled out of the DC circuit AC signal and z processing the communication unit (8) and the detection unit (9) together to the primary side (7p) of the transmitter (7), and - a controller (10) for controlling the communication unit (8) and the detection unit (9 ), characterized in that - the controller (10) is designed to put the communication unit (8) and the detection unit (9) in an activated and a deactivated state respectively, - wherein an injection of the communication signal only in the activated state of the communication unit ( 8), wherein reception and / or processing of the AC signal takes place only in the activated state of the detection unit (9), and wherein the controller (10) is designed to monitor the states of the communication unit (8) and the detection unit ( 9) in such a way that at most one unit of communication unit (8) and detection unit (9) is in the activated state at any one time. Device (1) according to Claim 1 , characterized in that the communication unit (8) and the detection unit (9) are connected to the same primary winding (71p) of the transformer (7). Device (1) according to Claim 1 , characterized in that the transformer (7) in addition to the primary winding (71p) has a further primary winding (72p) on the primary side (7p), wherein the communication unit (8) to the primary winding (71p) and the detection unit (9) the further primary winding (72p) of the transformer (7) is connected. Device (1) according to Claim 2 , characterized in that the communication unit (8) and the detection unit (9) are connected in parallel to each other to the same primary winding (71p) of the transformer (7). Device (1) according to Claim 2 , characterized in that the communication unit (8) and the detection unit (9) are connected in series with the same primary winding (71p) of the transformer (7). Device (1) according to one of Claims 1 to 5 , characterized in that the detection unit (9) is adapted to detect an arc in the DC circuit of the circuit unit. Device (1) according to one of Claims 1 to 6 , characterized in that the communication unit (8) or the detection unit (9) is additionally designed for receiving and processing a coupled via the transformer (7) from the DC circuit further communication signal. Device (1) according to Claim 7 , characterized in that the communication unit (8) or the detection unit (9) is adapted to pass the further communication signal to the controller (10), and wherein the controller (10) is designed, the detection unit (9) and / or the communication unit (8) to control in dependence of the further communication signal. Device (1) according to one of Claims 1 to 8th , characterized in that the device (1) further comprises a blocking member (5), which is connected in parallel to the series circuit of capacitor (6) and secondary winding (71s). Device (1) according to one of Claims 1 to 9 , characterized in that the capacitor (6) and the secondary winding (71s) of the transformer (7) are selected such that their series circuit at a frequency of the communication signal and / or the further communication signal has a resonant frequency. Device (1) according to one of Claims 1 to 10 , as far as related back to Claim 5 , characterized in that the device (1) additionally comprises a controllable by the controller (10) first switch (11.1) which is designed to connect a first (19.1) and a second signal terminal (19.2) of the detection unit (9) with each other or separate from each other, and wherein the device (1) optionally additionally comprises a controllable by the controller (10) second switch (11.2), which is designed, a first (18.1) and a second signal terminal (18.2) of the communication unit (8) to connect or disconnect from each other. Device (1) according to one of Claims 1 to 10 , as far as related back to Claim 5 , characterized in that the device (1) additionally comprises a first switch (11.1) which can be controlled by the controller (10) and which is designed to have a first (19.1) and a second signal terminal (19.2) of the detection unit (9) via a second Capacitor (23) to be connected to each other or to separate from each other, and - wherein the device (1) additionally comprises a controllable by the controller (10) second switch (11.2), which is designed, a first signal terminal (18.1) of the communication unit (8 ) via a diode (13) and a third capacitor (24) to a DC voltage source (12) to connect or disconnect. Device (1) according to one of Claims 1 to 10 , as far as related back to Claim 3 or 4 , characterized in that the device (1) additionally comprises a third switch (11.3) which can be controlled by the controller (10) and which is designed to connect the detection unit (9) to the primary winding (71p) or the further primary winding (72p) or optionally, and wherein the device (1) optionally additionally comprises a fourth switch (11.4) controllable by the controller (10) and arranged to connect or disconnect the communication unit (8) with the primary winding (71p) , Photovoltaic (PV) system (17) comprising a DC circuit comprising a photovoltaic (PV) generator (14), a positive (15) and a negative DC connection line (16) and a DC input of an inverter (3) , wherein the DC input via the positive (15) and the negative DC connecting line (16) to the PV generator (14) is connected, wherein the inverter (3) is designed for the conversion of direct current into alternating current and the output with a AC network (4) is connected, characterized in that the DC circuit of the PV system (17) further comprises a device (1) according to one of Claims 1 to 13 having. PV system (17) according to Claim 14 characterized in that the device (1) is disposed within one of the DC connection lines (15, 16) connecting one pole of the PV generator (14) to a DC input terminal of the inverter (3). PV system (17) according to Claim 14 , characterized in that the device (1) with the first connection (2.1) to the positive DC connection line (15) and with the second connection (2.2) to the negative DC connection line (16) is connected.

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