CROSS-REFERENCE TO RELATED APPLICATIONS

This application is filed under 35 U.S.C. 371, filed from PCT/EP2018/066808 having a filing date of Jun. 22, 2018, which claims priority from DE 10 2017 122 283.9 having a filing date of Sep. 26, 2017, each of which are hereby incorporated by reference in their entirety for all purposes.

The present invention relates to a monitoring device for monitoring an energy parameter in a distribution station, a readout device for querying a monitoring device in a distribution station, a monitoring system for monitoring energy parameters as well as a method for monitoring an energy parameter and a method for querying a monitoring device in a distribution station.

Substations (also called grid stations) represent the link in a power network between medium voltage (10, 20 or 30 kV) and low voltage (230 or 400 V). Such substations usually comprise a medium-voltage switchgear, a transformer and a low-voltage distribution board (LVDB), which are installed in a housing (station building). The low-voltage distribution board consists of an infeed and several cable outlets that supply connected consumers with low voltage and/or collect fed-in energy from connected infeeders. There are usually five to ten cable outlets within the substation, wherein an individual cable connected to a cable outlet supplies several end customers (consumers and/or infeeders) along its course down a street of houses. So-called cable distribution cabinets (CDC), which usually comprise three to nine cable outlets, are available for subdividing the cable harnesses outside the substation. Individual dwelling or commercial units in turn are connected to the power network via a house connection box (HCB). Large commercial units can also be connected directly to a cable outlet in the substation.

Present-day power networks are primarily geared to a power generation that almost exclusively takes place centrally. Historically, electricity was generated centrally in large power stations, which allowed for the medium voltage to be kept relatively constant and a voltage drop to occur only between substation and consumer. Today, however, energy is increasingly also generated from regenerative sources. Part of the energy generation takes place locally in small feed-in stations. In particular, the locally generated share continues to increase. As a result, the load situation of the individual cable outlets in the substation as well as in the CDCs or HCBs can vary considerably. The load situation of the various medium-voltage lines can also vary considerably. For example, several photovoltaic plants for feeding in energy into the low-voltage system can be connected to one cable outlet, which can lead to a voltage increase above the admissible level (overvoltage).

New challenges are also unfolding on the side of the consumers. For example, when charging electric vehicles or stationary energy storage devices, short-term high loads and strong fluctuations in consumption can occur. If several charging points for electric vehicles are connected to a single cable outlet, a high strain is exerted on the cable outlet during charging. This can lead to a voltage depression (undervoltage) and an overloading of the cable harnesses.

As the technology used mostly still originates from a time in which no local generation and no time-dependent and/or short-term large-scale consumption had to be taken into account, neither the substations nor the CDCs and HCBs have an integrated measuring technology. Knowledge of the actual loads and load peaks of the individual cable outlets in the low-voltage system can therefore only be obtained on the basis of individual measurements on site.

Due to the large number of cable outlets and the large number of medium-voltage lines, a comprehensive and area-wide monitoring and measurement is currently considered to be uneconomical. Usually, measurements are only carried out selectively on problematic outlets and/or lines that have become known, for example, because of disturbances. As no real-life measurement data is available, development of the networks is mostly based on load assumptions on the basis of load curves, synchronisms and predictions. However, such instruments are often no longer applicable in the age of electromobility and in view of the use of local energy storage and local feeding-in of energy. This can lead to shortages in the provision of services as well as to voltage problems.

Measurement in the low-voltage and medium-voltage networks is usually carried out manually by maintenance personnel on site at the substations. For example, inductive current transformers, clamp-on ammeters, permanently installed inductive transformers on vertical fuse switch disconnectors or on low-voltage distribution boards, Rogowski coils with suitable signal processing, and Hall effect sensors are used. In addition to these measuring devices, a corresponding offset evaluation device and/or a data collector, a data concentrator or a head station usually has to be used, which can be designed, for example, as a control cabinet or as a portable measuring device. The sensors (transformers) are then connected to the corresponding evaluation device by cable. Attaching the sensors directly to a voltage potential, i.e. to a non-insulated part, is to be avoided since this can lead to potential carryover due to the necessary cable connection.

When using such wired solutions, the dangers for the maintenance personnel when connecting and removing the devices should not be underestimated. Manual handling requires compliance with safety standards. Because of the high voltages, it is often necessary for the maintenance personnel to be especially trained. On the one hand, the combination of sensor and evaluation device is expensive to buy, on the other hand, the application is also complex and expensive.

More recently, as an alternative to wired solutions, measuring devices have become known that can be read out via the mobile network and thus enable automatic monitoring without the deployment of operating personnel. The disadvantages of such solutions include, in particular, the high price as well as the fact that a large amount of data is collected that is unnecessary for network planning and monitoring.

In addition, the parallel use of different systems often results in disadvantages with respect to the manageability and a comparatively high error-proneness during installation and start-up.

DE 10 2011 075 353 A1 discloses an error control system for a distribution network station of a power grid. The error control system is intended for a distribution network station fed by a feed-in point of, for instance, a substation of an electric power grid, wherein the distribution network station comprises at least one inlet side facing the feed-in point with a corresponding inlet-side load switch and at least one outlet side facing away from the inlet side with a corresponding outlet-side load switch. The error control system comprises a measuring device which is locally allocated to the distribution network station for recording both inlet-side load flow information on the inlet side of the distribution network station and outlet-side load flow information on the outlet side of the distribution network station. The load flow information can particularly be information on the electrical current flow, which can optionally be accompanied by information on the electrical voltage.

DE 20 2008 017 797 U1 discloses a counting and measuring point system for counting and measuring the consumption or the generation of electrical energy. The system comprises a number of stationary connection devices which are connected to the power network and are suitable for withdrawal or feeding-in of electrical energy via consumption and/or generation units, which are provided with an identifier by means of which the connection holder can be identified, and at least one identifiable stationary functional unit for measuring and counting the electrical energy which is withdrawn or fed in by consumption and/or generation units at one or more stationary connection devices via an electrical conductor, wherein the functional unit comprises: aa. a device for detecting the identifier of the connection device, bb. an identifiable device for counting and measuring the electrical energy withdrawn from and/or fed into the connection device recorded according to (aa.), cc. a device for storing the counting and measurement data determined in accordance with (bb.) as well as the identifier of the connection device used as recorded in accordance with (aa.)

WO 2012/119 648 A1 discloses an energy automation system and a method for operating an energy automation system. In order to simplify the configuration of, in particular, an energy automation system with a comparatively large number of energy automation devices and to develop it in such a way that, as far as possible, no interruption of operation is necessary, a method for operating an energy automation system is proposed, wherein the energy automation system comprises a plurality of energy automation devices and at least one superordinate system control device for controlling and/or monitoring the energy automation devices. It is intended that an additional energy automation device is connected to the concentrator appliance and an automatic configuration of the concentrator device is carried out by integrating a device description file of the additional energy automation device into a concentrator data model of the concentrator appliance. The invention also relates to a corresponding energy automation system.

On this basis, the present invention addresses the problem of realizing a monitoring of energy parameters, which takes into account the actual requirements of energy suppliers for monitoring as well as the structure of the current networks and the existing operational procedures of energy suppliers. A kind of monitoring is to be realized that is inexpensive with regard to the installation and operating effort as well as with regard to the device costs and at the same time allows for a monitoring of relevant energy parameters with a low error-proneness and a high operational reliability.

According to the invention, this problem is solved by a monitoring device for monitoring an energy parameter in a distribution station. The monitoring device is designed to be attached to a voltage conductor in the distribution station and comprises: a device identifier for uniquely identifying the monitoring device, which device identifier is designed to be read out from immediate spatial proximity; a measurement unit for measuring an electrical current and/or a voltage of an alternating current flowing through the voltage conductor; an evaluation unit for determining the energy parameter based on the measured electrical current and/or voltage; and a communication unit for receiving a request from a readout device and for transmitting the energy parameter to the readout device if the received request comprises access information that is based on the device identifier.

In a further aspect, the problem illustrated above is solved by a readout device for querying a monitoring device in a distribution station, comprising: an interface for receiving a device identifier of the monitoring device, an access unit for determining access information that is based on the device identifier; and an interrogation unit for transmitting a query to the monitoring device and for receiving an energy parameter from the monitoring device, wherein the query comprises access information and wherein the interface is preferably designed to transmit the energy parameter to a central information collection point.

A further aspect of the present invention relates to a monitoring system for monitoring energy parameters in a distribution station, comprising at least one monitoring device and one readout device as described above as well as comprising a system identifier for uniquely identifying the monitoring system, which system identifier is designed to be read out from immediate spatial proximity.

In a further aspect, the invention relates to a method for monitoring an energy parameter in a distribution station, comprising a monitoring device designed to be attached to a voltage conductor in the distribution station, comprising the steps of: measuring an electrical current and/or a voltage of an alternating current flowing through the voltage conductor; determining an energy parameter based on the measured electrical current and/or voltage; receiving a request from a readout device; and transmitting the energy parameter to the readout device if the received request comprises access information that is based on a device identifier for uniquely identifying the monitoring device, wherein the device identifier is designed to be read out from immediate spatial proximity. In addition, an aspect of the invention relates to a method for querying a monitoring device in a distribution station, comprising the steps of: receiving a device identifier of the monitoring device; determining access information that is based on the device identifier; and transmitting a query to the monitoring device, wherein the query comprises access information; and receiving an energy parameter from the monitoring device.

Preferred embodiments of the invention are described in the dependent claims. It is understood that the monitoring device, the readout device, the monitoring system as well as the methods for monitoring and querying can be designed in accordance with the embodiments described for the monitoring device, the readout device, the monitoring system and the methods in the dependent claims.

According to the invention, the use of an integrated monitoring device is proposed. The device is designed to be attached to a voltage conductor in a distribution station and allows for the monitoring of an energy parameter which is based on an electrical current or a voltage. Herein, a distribution station is preferably understood to mean a substation, but also a CDC, an HCB or another component of the power network accessibly housed in a housing or box. The monitoring device has a compact design so that it can be fitted into existing distribution stations with little effort and so that it can remain in the distribution station during its operation. A permanent measurement and/or monitoring is made possible.

Starting from a measurement of an electrical current and/or voltage, the measured value is further processed in an evaluation unit and an energy parameter is determined. For example, filters can be used, averages can be formed or time stamps can be assigned. The energy parameter determined is transmitted to a readout device for further use. A request from the readout device is received via a communication unit of the monitoring device. It is checked whether this received request contains access information in order to ensure that no unauthorized retrieving of the energy parameter can occur. For this purpose, the monitoring device comprises a device identifier. If this device identifier is known to the readout device, retrieving of the energy parameter is enabled. If the access information is based on a device identifier of the monitoring device, the energy parameter is transmitted to the readout device via the communication unit. The device identifier is designed as a part of the monitoring device in such a way that it can only be detected from immediate spatial proximity to the monitoring device.

In the corresponding readout device, access information is generated in an access unit based on the device identifier, which access information is then used to transmit the corresponding request in order to receive the energy parameter from the monitoring device. The interface of the readout device can comprise, for example, a wireless communication interface or a plug connection.

A monitoring system comprises at least one monitoring device and one readout device. In addition, a system identifier is provided which uniquely identifies the monitoring system and which is also designed in such a way that it can only be read out from immediate spatial proximity.

Such a monitoring system is usually used to monitor several cable outlets in a distribution station, wherein, for each cable outlet, all three phases as well as the neutral conductor and/or protective conductor are monitored by separate monitoring devices. Monitoring devices which can be read out by a common readout device are then attached to all individual voltage conductors. The communication units of the monitoring devices and the interrogation unit of the readout device are in contact with one another. The system identifier of the monitoring system allows for a common approaching and/or reading out of the multiple monitoring devices of the monitoring system, which allows for efficient querying with little effort.

Herein, attachment to a voltage conductor in the distribution station is particularly understood to mean attachment to a voltage conductor within the distribution station, i.e. in the interior of a corresponding housing. Reading out from immediate spatial proximity is understood to mean registering an identifier in an immediate surrounding area. In particular, reading out if there is direct visual contact. Immediate spatial proximity is preferably understood to mean an area with a radius of a few centimeters around the monitoring device, for example an area within a radius of up to 10 cm, up to 20 cm, up to 50 cm or up to one meter. An energy parameter of an alternating current is measured, the voltage of the alternating current is understood to mean in particular the effective voltage.

In comparison with previous approaches for monitoring energy parameters in the context described above, the monitoring device according to the invention is considerably easier to assemble and start-up. The integrated, readable device identifier of the monitoring device as well as the corresponding system identification and the security of the communication between the monitoring device and the interrogation device based thereupon, to a large extent lead to configuration freedom. As the designations and/or identification features are factory-set, ease of installation is guaranteed. The demands made on assembly and operating personnel in terms of qualification are low.

Media breaks are prevented by retrieving the energy parameter and directly forwarding it via the interface of the interrogation device. The energy parameter can be fed directly into a corresponding computer system so that errors during manual data transmission are prevented. As the device identification and the system identification can be read out from immediate spatial proximity, a high level of data security and a low level of error proneness are achieved. The energy parameter can only be retrieved by reading out an identifier on site. Incorrect handling by assembly personnel is prevented.

As a long-distance communication module is not necessary, production costs remain low. As it is possible to attach an integrated compact device to a voltage conductor, installation can take place even in tight spaces in existing distribution stations. Easy retrofitting and use is possible in various situations in low-voltage and medium-voltage networks.

In a preferred embodiment of the monitoring device, the measurement unit is designed to measure the electrical current, and the evaluation unit is designed to determine an energy parameter that represents a maximum electrical current within a predefined time interval. For example, the maximum electrical current can be determined within an interval of 15 minutes. Monitoring the maximum electrical current is particularly relevant and meaningful with regard to network planning. Starting from a monitoring of the maximum electrical current alone, conclusions can be drawn that are relevant for network planning. In most cases it is not necessary to monitor a time course and a cost-efficient monitoring of the maximum values is sufficient.

In a further preferred embodiment, the device identifier is designed to be read out optically, preferably as a QR code or bar code; and/or the device identifier is attached to an outside of the monitoring device. By using a device identifier that can be read out optically, it is ensured that reading out is only possible when there is visual contact. Data security is increased. Unauthorized access to the energy parameter is not possible since the device identifier can only be read out if there is access to the distribution station. The use of a bar code or a QR code allows for easy handling. It can be attached to an outside of the housing of the monitoring device, for example, in the form of a sticker or by direct printing. The system identifier is preferably designed accordingly. The system identifier can then be attached to the inside of the station housing so that it can only be read out when the housing is open.

Preferably, the measurement unit is designed to measure the electrical current and comprises an inductive converter with a core surrounding the voltage conductor, which is designed divisibly to be attachable to the voltage conductor. A sensor based on the inductive measuring principle can be used for the actual measurement. For this purpose, it is necessary for the voltage conductor to be surrounded by or enclosed with a conductive core. In order to enable such an enclosure or to allow the monitoring device to be attached subsequently, the core is preferably designed to be divisible, i.e. it can be divided or separated for attachment in order to receive or enclose the voltage conductor. High measuring accuracy as well as simple, subsequent installability and a compact design are achieved.

In one embodiment, the monitoring device further preferably comprises an inductive converter for generating energy based on the alternating current in the voltage conductor. The same converter as for the measurement can be used as inductive converter. Energy generation is then also based on the alternating current in the voltage conductor. A voltage is induced. The energy gained can be used directly to supply the monitoring device. The monitoring device can also comprise an energy store for storing the energy gained, for example a rechargeable battery or a capacitor, in order to enable buffering and/or time-delayed operation. A direct supply of the monitoring device (without battery/capacitor) from the converter is preferred. By integrating energy generation, the maintenance effort is reduced. Replacement of a battery is not necessary. Efficient maintenance can be warranted.

Preferably, the monitoring device further comprises a memory unit for regularly storing the energy parameter, wherein the communication unit is designed to transmit at least one stored energy parameter. Advantageously, the energy parameter can be stored regularly so that the monitoring device can be operated in the form of a data logger. Reading out is then carried out at irregular intervals, wherein several stored energy parameters are transmitted during read-out. Operating costs are reduced.

Preferably, the communication unit is designed for wireless communication, preferably as a Bluetooth or wake-up transceiver. Correspondingly, the interrogation unit of the readout device is also preferably designed for wireless communication. Wireless communication between monitoring device and readout device allows for an efficient read-out. Using the readout device, operating personnel on site can read out the data of the monitoring device wirelessly and with little effort. By using a Bluetooth or wake-up transceiver, an energy-saving communication is achieved. The access information then corresponds, for example, to a Bluetooth pairing code or a wake-up sequence of a wake-up transceiver. This is particularly advantageous if, as described above, the energy supply is to be provided by energy harvesting by means of an inductive converter.

Further preferably, the monitoring device comprises a display unit for displaying the energy parameter, wherein the display unit is preferably designed as an e-ink display. For example, the display unit can be designed in such a manner that it displays the current measuring value when a control element (e.g. push button) is operated. This allows for quick and uncomplicated on-site reading out of the current value. A performance test can thus be simplified.

In a further embodiment, the monitoring device comprises a time measurement unit for defining measurement instants, wherein the measurement unit is designed to measure the electrical current and/or the voltage at the measurement instants; and/or wherein the evaluation unit is designed to determine the energy parameter at the measurement instants. When a time measurement unit is used, measurements can be carried out at predefined instants of time. Thus, relevant times can be examined more closely.

Additionally or alternatively to measuring the electrical current and/or the voltage, the measurement unit of the monitoring device can optionally also be designed to measure a temperature. It is also possible that a separate additional temperature sensor is provided in the monitoring device, which, for example, allows for the determination of a temperature of the voltage conductor and/or of a transformer. Based on the determined temperature, further relevant additional information can be obtained.

In an advantageous embodiment, the monitoring device is designed to be coupled to the voltage conductor by means of a fixing element, and is preferably arranged in a fully encapsulated housing to be protected from dirt, moisture and other environmental influences. For example, a holding band or a screw secured against loosening can be used as fixing element. The fixing element allows for easy attachment of the monitoring device to the voltage conductor. Efficient installation is achieved that can be carried out subsequently and that does not require any special skills or special tools and is therefore inexpensive to implement.

In an advantageous embodiment of the monitoring system according to the invention, the readout device comprises a readout unit for reading out the device identifier and the system identifier; and the interface is designed to transmit the device identifier and the system identifier to a central information collection point for storing an allocation between device identifier and system identifier. By means of the readout unit (e.g. bar code or QR code reader or smartphone camera), both the device identifier and the system identifier can be read out. Then an allocation between device identifiers of the at least one monitoring device, the monitoring system and the system identifier can be carried out. This allocation is stored centrally. The central information collection point can be designed as a local or remote (Internet) database. For subsequent read-out processes, it is no longer necessary to identify each individual monitoring device on the basis of the device identifier. It is sufficient for the system identifier to be read out and a composition of device identifiers of the different monitoring devices allocated to the monitoring system to be requested from the central information collection point. Operation efficiency is thus further increased. Several monitoring devices can be read out at once. A quick read-out with low demands on the operating personnel can take place.

In a further embodiment, the monitoring system comprises at least one device set to which at least one monitoring device is allocated; and at least one set identifier for uniquely identifying the at least one device set, which set identifier is designed to be read out from immediate spatial proximity, wherein the readout unit is designed to read out the set identifier; and the interface is designed to transmit the set identifier to the central information collection point and to receive the device identifier of the at least one monitoring device allocated to the device set from the central information collection point. For example, the different voltage conductors of a cable outlet (three phases, a neutral and/or protective conductor) can be monitored with one device set. The use of a set identifier along with the device identifier and the system identifier results in a further hierarchy level for monitoring and for querying. The multiple monitoring devices of a set belong to the same monitoring system and form a subunit within this monitoring system. By reading out the set identifier, the device identifiers of the individual monitoring devices allocated to the device set can be requested. Reading out the set identifier is sufficient and it is not necessary to read out each device identifier separately. Operability is further improved.

In an advantageous embodiment, the monitoring system comprises a central information collection point for storing an allocation between device identifier and system identifier, which central information collection point is designed to receive a system identifier and/or a set identifier, and to transmit at least one device identifier allocated to the monitoring system or the device set. In response to a query by the readout device including the system or set identifier, the device identifiers allocated to the monitoring system or the device set are transmitted. An efficient handling is ensured.

In an advantageous embodiment, the method for monitoring an energy parameter according to the invention comprises the steps of the method described above for querying the monitoring device as well as the following further steps: reading out a system identifier for uniquely identifying a monitoring system from immediate spatial proximity; and transmitting the system identifier to a central information collection point for storing an allocation between device identifier and system identifier, wherein the step of receiving the device identifier of the monitoring device comprises receiving the device identifier of the at least one monitoring device allocated to the monitoring system from the central information collection point. The information collection point is used to answer a query in order to make the corresponding allocated device identifiers available for the query on the basis of a read out system identifier. Separate reading out is no longer required after a one-time installation or start-up of the monitoring system. Read-out efficiency is increased.

For a start-up of a monitoring system, the following steps are preferably carried out: attaching the monitoring device to a voltage conductor in the distribution station; attaching the system identifier to the distribution station; reading out the device identifier and the system identifier from immediate spatial proximity; and transmitting the device identifier and the system identifier to a central information collection point for storing an allocation between device identifier and system identifier. Only for the start-up is it necessary to read out both the device identifier and the system identifier. After the device identifier and the system identifier have been transmitted to the central information collection point, an allocation can be made there. For future read-out processes, only the system identifier needs to be read out. The allocated monitoring devices can be obtained from the information collection point on the basis of the stored allocation.

In a further aspect, the invention relates to a computer program product with a data carrier on which program code is stored, which is designed to carry out the methods with the steps as described above when the program code is executed.

