Method and system for detecting faults in a controllable local network transformer

Abstract

The invention relates to a method for detecting faults in a controllable local network transformer (1), wherein one or more power systems (4) are connected to the local network transformer (1) via a three-phase power network (2), and each of the power systems (4) comprises a measuring device (41) for detecting the voltage of each phase and a monitoring unit (42) for analysing the detected voltages. The method is characterised by the following steps: - detecting the voltage for each of the phases by means of the measuring device (41); - transmitting the detected voltages to the monitoring unit (42); - transmitting an error message relating to the local network transformer (1) to a network control unit (6) of the power network (2) using the monitoring unit (42) if, within a defined time range, only voltage jumps below a defined threshold value are detected by the monitoring unit (42). The invention also relates to a system (10) for detecting faults in a controllable local network transformer (1).

Description

[0001] Description

[0002] Method and system for fault detection of a controllable local network transformer

[0003] The invention relates to a method according to the preamble of patent claim 1 and a system according to the preamble of patent claim 11.

[0004] Several connected devices (energy systems) are each connected to an electrical distribution network (power grid) via a grid connection point. Below their grid connection point, the energy systems may have one or more energy systems for generating, consuming, and / or storing electrical energy, as well as devices for controlling, regulating, and / or communicating (edge ​​devices). An example of such an energy system is a private household with a photovoltaic system and a battery storage system.

[0005] To regulate the power grid, it includes active network components, such as adjustable distribution transformers (rONT). An adjustable distribution transformer can adjust its transformation ratio in specified steps without interrupting the voltage at the secondary busbar. This can resolve voltage problems on the low-voltage side.

[0006] The tapping of an adjustable distribution transformer is controlled by a local control system, which detects the voltage on the busbar on the low-voltage side and sets the transformation ratio of the transformer based on the status.

[0007] However, if the control of a regulated distribution transformer fails or does not behave as desired, this transformer malfunction remains undetected. This is the case because, particularly in low-voltage networks, few measuring points are permanently installed.

[0008] One consequence of such an unnoticed failure of the transformer control can be a violation of the permissible voltage range in the low-voltage network (according to EN 50160). This could cause damage to connected devices, such as white goods, drives, heat pumps, and the like.

[0009] Furthermore, modern energy systems feature various measuring devices, control devices, and / or regulating devices. In particular, energy systems integrated into a local energy market typically feature intelligent devices, such as so-called edge devices, for their connection to the local energy market platform. Such an energy market platform is known, for example, from document EP 3518369 A1.

[0010] The present invention is based on the object of providing a method and a system for fault detection of a controllable local network transformer, which in particular uses the infrastructure available through a local energy market.

[0011] The object is achieved by a method having the features of independent patent claim 1 and by a system having the features of independent patent claim 11. Advantageous embodiments and further developments of the invention are specified in the dependent patent claims.

[0012] The method according to the invention for fault detection of a controllable local network transformer, wherein one or more energy systems are connected to the local network transformer via a three-phase power network, and each of the energy systems comprises a measuring device for detecting the voltage of each phase and a monitoring unit for evaluating the detected voltages, is characterized by at least the following steps: - detecting the voltage for each of the phases by means of the measuring unit;

[0013] - Transmitting the detected voltages to the monitoring unit;

[0014] - Transmission of an error message regarding the local network transformer to a network control unit of the power grid by the monitoring unit if only voltage jumps below a specified threshold value are detected by the monitoring unit within a specified time range.

[0015] The method according to the invention and / or one or more functions, features, and / or steps of the method according to the invention and / or one of its embodiments can be computer-aided. For example, the monitoring unit for analyzing the detected voltages is designed as a computing device.

[0016] From a structural point of view, in particular the IPCC Fift Assessment Report defines an energy system as: "All components related to the production, transformation, delivery and use of energy" (Annex I, page 1261).

[0017] Energy systems typically comprise a number of components, in particular energy technology systems, for example energy conversion systems, consumption systems and / or storage systems. Energy systems can generate and / or provide a number of forms of energy (multimodal energy systems). In particular, such an energy system provides one or more forms of energy for a consumer, for example a building, an industrial plant or private facilities, the provision being carried out in particular by converting different forms of energy, by transporting different forms of energy and / or by stored forms of energy. In other words, the different forms of energy, for example heat, cold or electrical energy, are coupled by means of the multimodal energy system with regard to their generation, their provision and / or their storage.Energy systems include, for example, buildings, particularly residential buildings and / or office buildings, and / or industrial facilities.

[0018] As an energy technology plant, the energy system can comprise one or more of the following components: power generators, combined heat and power plants, in particular block heat and power plants, gas boilers, diesel generators, heat pumps, compression chillers, absorption chillers, pumps, district heating networks, energy transfer lines, wind turbines or wind power plants, photovoltaic systems, energy storage systems, in particular battery storage systems, biomass plants, biogas plants, waste incineration plants, industrial plants, conventional power plants and / or the like.

[0019] In a first step of the method according to the invention, the voltage of each phase is recorded by means of the measuring device. Recording can take place continuously or in predetermined time steps. Thus, a current voltage of each phase is preferably recorded, which is recorded by the measuring device, for example, every minute. The measuring device can be comprised of an edge device or be designed as an edge device. The recorded voltages are typically available as measurement data, for example in the form of a time series.

[0020] In a second step of the method according to the invention, the measuring device transmits the detected voltage(s) to the monitoring unit. The measuring device can transmit the measured data directly or indirectly, for example, through and / or via additional components that transmit the voltages in the form of measured data to the monitoring unit.

[0021] In a third step of the method according to the invention, the measurement data or the measured values ​​relating to the voltages are analyzed by the monitoring unit. According to the invention, the voltage jumps are analyzed here. A basic idea of ​​the present invention is that the voltage jumps caused by the control of the local network transformer can also be measured on the low-voltage side. For the data analysis of the recorded voltages, the monitoring unit can comprise a computer-assisted analysis software module. According to the invention, the analysis is carried out by the monitoring unit in such a way that it is checked whether, within a defined time range, only voltage jumps below a defined threshold value are present by the monitoring unit.If no voltage surges above the threshold value occur for the specified period, the monitoring unit transmits an error message to a grid control unit of the power grid. The error message can be transmitted directly or indirectly, for example, through and / or via other components.

[0022] It is therefore a further fundamental idea of ​​the present invention that a fault or malfunction of the transformer can be detected by the absence of voltage jumps of a certain magnitude. Whether this is an intervention in the transformer's control system or a normal voltage fluctuation is determined according to the invention by the threshold value for the voltage jumps.

[0023] An error message in the sense of the present invention can be any data set and / or any signal which contains the information for the grid control unit that a fault in the local grid transformer has been detected.

[0024] According to the present invention, the voltage jumps that occur due to the regulation of the distribution network transformer are analyzed according to their magnitude.

[0025] The present invention thus makes it possible to detect malfunctions in the distribution network transformer or its control system. This can advantageously reduce or prevent damage to electrical systems, components, and / or devices in the energy system.

[0026] Furthermore, the error message advantageously informs the grid control unit about the transformer's malfunction, allowing it to take appropriate measures to correct the fault. For example, suitable spare parts can be procured. This eliminates the need for additional maintenance to diagnose the damage.

[0027] Furthermore, additional sensors within the power grid for fault detection can be eliminated by using components already present within the energy systems. This is particularly possible when the energy systems are integrated into a local energy market. Thus, no further or additional infrastructure is required. This allows the grid operator to eliminate redundant hardware and software, leading to greater sustainability.

[0028] The system according to the invention for fault detection of a controllable distribution transformer comprises one or more power systems connected to the distribution transformer via a three-phase power grid, each of the power systems comprising a measuring device for detecting the voltage of each phase and a monitoring unit for evaluating the detected voltages. The system according to the invention is characterized in that:

[0029] - the measuring device is designed to measure the voltage for each of the phases;

[0030] - the measuring device is designed to transmit the measured voltages to the monitoring unit; and

[0031] - the monitoring unit is designed to transmit an error message relating to the local network transformer to a network control unit of the power grid if, within a specified time range, only voltage jumps below a specified threshold value are detected by the monitoring unit.

[0032] The method according to the invention results in similar, equivalent and equivalent advantages and / or embodiments of the system according to the invention.

[0033] Alternatively and / or additionally, the monitoring unit can be configured centrally for multiple energy systems, i.e., the device comprises a central monitoring unit for one or more energy systems. As a result, these energy systems do not comprise the monitoring unit, but instead have communication units (edge ​​devices) with this central monitoring unit.

[0034] According to an advantageous embodiment of the invention, the error message is only transmitted if, in addition, a permissible voltage range is violated by the detected voltages.

[0035] In other words, the monitoring unit also checks whether the permissible voltage range has been violated. Thus, the conditions for transmitting the error message are determined by, first, no voltage jumps above the threshold value, and, second, the voltage range being violated. This advantageously increases the probability that the error is actually a control error.

[0036] The permissible voltage range is preferably defined by the voltage range from 207 volts to 253 volts.

[0037] This corresponds to the low voltage range in Germany.

[0038] Advantageously, the voltage range is defined by ± 10 percent of a voltage setpoint. In an advantageous development of the invention, an error description regarding the error message is additionally transmitted by the monitoring unit to the grid control unit.

[0039] This advantageously informs the grid control unit about the type of fault. This allows the grid control unit to take more appropriate and targeted measures to correct the fault.

[0040] According to an advantageous embodiment of the invention, a repair and / or maintenance of the local network transformer is carried out based on the error message.

[0041] The repair and / or maintenance is initiated by the grid control unit. The repair and / or maintenance can also be based on the submitted fault description.

[0042] In an advantageous development of the invention, the measuring device is further designed to detect the active power and / or reactive power of each phase.

[0043] This advantageously allows for the recording of additional parameters relevant to the power grid's status. In particular, in addition to the voltage, the current at the grid connection point is recorded. This additional data can then be transmitted, for example, by the monitoring unit, to the grid control unit. This advantageously allows for an improved distribution system state estimator.

[0044] It is therefore advantageous for the grid control unit to perform a grid status assessment, taking into account the error message and / or other data transmitted by the monitoring unit. This grid status assessment can advantageously detect a possible violation of the voltage range at unmetered grid connection points and make this information available to the distribution system operator.

[0045] Furthermore, the switching status of the power grid can be estimated, which is typically unknown in low-voltage systems because the switches are not telemetrically connected to a control system, such as the grid control unit, and are typically switched manually. This can also assist in fault localization and / or troubleshooting.

[0046] According to an advantageous embodiment of the invention, the error message is transmitted by the monitoring unit to a local energy market platform, wherein the local energy market platform forwards the error message to the grid control unit.

[0047] This is advantageous because it utilizes an existing infrastructure for fault detection. This is possible because local energy market platforms typically already have a data interface to the grid control unit.

[0048] Preferably, the additional data will also be forwarded to the grid control unit via the local energy market platform.

[0049] In this case, they can also be used for network planning when questions arise about the technical feasibility of installing new systems, photovoltaic systems or charging stations for electric vehicles. Furthermore, for medium and long-term network planning, the recorded and possibly stored data can support the technical question of whether and at which point an expansion of the network operating resources is necessary. In an advantageous development of the invention, the monitoring unit forms a component of a trading agent unit, wherein the trading agent unit is designed to determine offers and / or bids relating to an energy exchange via the power grid and to transmit these, along with the error message, to the local energy market platform.

[0050] In other words, the trading agent unit or the trading agent of the local energy market is advantageously used as the monitoring unit. The trading agent first transmits the error message to the local energy market platform. The local energy market platform then forwards the error message to the grid control unit. This advantageously utilizes the existing infrastructure for error detection in the local energy market.

[0051] According to an advantageous embodiment of the invention, the power grid is designed as a medium-voltage grid or low-voltage grid.

[0052] This is an advantage because typically no sensors or measuring devices are available for the power grids mentioned.

[0053] However, according to a preferred embodiment of the present invention, the measuring devices, modules, trading agents, etc. of a local energy market, which has a data interface to the grid control unit, can be used for fault detection.

[0054] Further advantages, features, and details of the invention will become apparent from the exemplary embodiments described below and from the drawing. The figure schematically shows a system according to a preferred embodiment of the present invention. Similar, equivalent, or equivalently effective elements may be provided with the same reference numerals in the figure.

[0055] The figure shows a system 10 comprising a plurality of energy systems 4 connected to a common power grid 2, in particular a low-voltage grid, via a respective grid connection point 3. For clarity, only one of the energy systems 4 is shown. The energy systems typically comprise a plurality of energy-related installations 40.

[0056] The power grid 2 has at least one controllable local network transformer 1, via which the energy systems 4 are connected to a higher voltage network.

[0057] Furthermore, the system 10 comprises a local energy market platform 5 and a grid control unit 6 .

[0058] The local energy market platform 5 enables a local energy exchange between the energy systems 4 and has, indicated by an arrow, a data interface to the grid control unit 6. Using its data interface, the local energy market platform 5 can transmit data / information to the grid control unit 6 or exchange it with it.

[0059] The grid control unit 6 is designed to control the power grid 2, for example, by controlling the local grid transformer 1. For this purpose, the grid control unit 6 can specify a control signal or setpoints for the local control of the local grid transformer 1. This is indicated by an arrow pointing from the grid control unit 6 to the transformer 1.

[0060] The energy systems 4 or system 10 further comprise a measuring device 41 and a monitoring unit 42. The monitoring unit 42 is designed as a trading agent unit of the local energy market 5. In other words, the monitoring unit 42 already forms the data interface between the energy system 4 and the local energy market 5.

[0061] The trading agent 42 or the monitoring unit 42 is designed to exchange data / information with the local energy market platform 5. This data exchange is indicated by an arrow from the monitoring unit 42 to the local energy market platform 5. In other words, the energy system 4 is already integrated into a local energy market or is a participant in the local energy market 5. For this participation, the energy system 4 thus already has the components required for this, namely the measuring device 41 and the trading agent unit 42.

[0062] Typically, within the local energy market 5, the trading agent 42 serves only to determine offers and / or bids for energy exchanges and to transmit them to the local energy market platform 5. In this case, the trading agent 42 additionally trains the technical monitoring unit 42, which is designed to analyze the voltage or its measured values, which the measuring device 41 records, and thus to detect a fault or malfunction of the local network transformer 1.

[0063] According to the present exemplary embodiment, the existing data interface of the trading agent 42 with the local energy market platform 5 and the existing data interface of the local energy market platform 5 with the grid control unit 6 are used to transmit an error message to the grid control unit 6 if, within a specified time range, no voltage jumps above the specified threshold value are detected by the monitoring unit 42 or if, within the specified time range, only voltage jumps below the specified threshold value are present. For this purpose, the measuring device 41 records one or more measured values ​​of the voltage of each phase of the power grid 2 and transmits these to the monitoring unit 42 or to the trading agent 42.

[0064] The present embodiment of the invention thus makes it possible to detect a fault or malfunction of the local grid transformer 1 and to use the components already present due to the participation of the energy system 4 in the local energy market 5 for fault detection and for a corresponding error message (error message) to the grid control unit 6. This avoids wasting resources and redundant grid expansion.

[0065] Based on the error message transmitted to the grid control unit 6 via the local energy market platform 5, the latter can take or initiate measures to rectify the error. For example, it can transmit appropriate setpoints or control signals to the controllable distribution transformer 1 and / or initiate repair and / or maintenance.

[0066] By further technically developing the commercial agent 42 as a monitoring unit 42, fault detection with regard to the local network transformer 1 can thus be carried out.

[0067] Although the invention has been illustrated and described in detail by the preferred embodiments, the invention is not limited by the disclosed examples, and other variations may be derived therefrom by those skilled in the art without departing from the scope of the invention. List of reference symbols

[0068] 1 local network transformer

[0069] 2 Power grid 3 Grid connection point

[0070] 4 Energy system

[0071] 5 Energy market platform

[0072] 6 Grid control unit

[0073] 10 System 40 systems

[0074] 41 Measuring device

[0075] 42 Monitoring unit

Claims

Patent claims 1. A method for fault detection of a controllable distribution network transformer (1), wherein one or more energy systems (4) are connected to the distribution network transformer (1) via a three-phase power network (2), and each of the energy systems (4) comprises a measuring unit (41) for detecting the voltage of each phase and a monitoring unit (42) for evaluating the detected voltages, characterized by the following steps: - detecting the voltage for each of the phases by means of the measuring unit (41); - transmitting the detected voltages to the monitoring unit ( 42 ); - Transmitting an error message regarding the local network transformer (1) to a network control unit (6) of the power grid (2) by the monitoring unit (42) if, within a specified time range, only voltage jumps below a specified threshold value are detected by the monitoring unit (42).

2. Method according to claim 1, characterized in that the error message is transmitted only if, in addition, a permissible voltage range is violated by the detected voltages.

3. Method according to claim 2, characterized in that the permissible voltage band is defined by the voltage range from 207 volts to 253 volts.

4. Method according to one of the preceding claims, characterized in that an error description relating to the error message is additionally transmitted by the monitoring unit (42) to the network control unit (6).

5. Method according to one of the preceding claims, characterized in that based on the error message a repair and / or maintenance of the distribution network transformer (1) is carried out.

6. Method according to one of the preceding claims, characterized in that the measuring unit (41) is further designed to detect the active power and / or reactive power of each phase.

7. Method according to claim 6, characterized in that the monitoring unit (42) transmits the detected active power and / or reactive power to the network control unit (6).

8. Method according to one of the preceding claims, characterized in that the network control unit (6) carries out a network status estimation taking into account the error message and / or further data transmitted by the monitoring unit (42).

9. Method according to one of the preceding claims, characterized in that the error message is transmitted by the monitoring unit (42) to a local energy market platform (5), wherein the local energy market platform (5) forwards the error message to the grid control unit (6).

10. The method according to claim 9, characterized in that the monitoring unit (42) forms a component of a trading agent unit, wherein the trading agent unit is designed to determine offers and / or bids with regard to an energy exchange via the power grid (2) and to transmit these and the error message to the local energy market platform (5).

11. System (10) for fault detection of a controllable local network transformer (1), which comprises one or more energy systems (4) connected to the local network transformer (1) via a three-phase power network (2), wherein each of the energy systems (4) has a measuring unit (41) for detecting the voltage of each phase and a monitoring unit (42) for evaluating the detected voltages, characterized in that: - the measuring unit (41) is designed to detect the voltage for each of the phases; - the measuring unit (41) is designed to transmit the detected voltages to the monitoring unit (42); and - the monitoring unit (42) is configured to transmit an error message regarding the local network transformer (1) to a network control unit (6) of the power grid (2) if, within a specified time range, only voltage jumps below a specified threshold value are detected by the monitoring unit (42).

12. System (10) according to claim 11, characterized in that the power grid (2) is configured as a medium-voltage network or a low-voltage network.

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