Method for determining an asymmetrical oscillation of an electrical device in operation connected to a high-voltage network
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- SIEMENS ENERGY GLOBAL GMBH & CO KG
- Filing Date
- 2021-01-12
- Publication Date
- 2026-06-02
Smart Images
Figure CN115039311B_ABST
Abstract
Description
Technical Field
[0001] The present invention relates to a method for determining asymmetric oscillations during operation of electrical equipment connected to a high-voltage network. Background Technology
[0002] In electrical transformers used, for example, in energy transmission and distribution networks, unwanted direct currents may feed into the windings. Power electronic components in the network, such as controllers for electrical drives, converters for flexible AC transmission systems, or high-voltage DC transmission, may also generate direct currents in electrical equipment. Another cause of direct current generation may be so-called "geomagnically induced currents" (GIC).
[0003] The DC component generates a DC flux component in the transformer core, which is superimposed on the AC flux. This results in asymmetric modulation of the magnetic material within the core, leading to a series of drawbacks. A few milliamps of DC current can cause flux saturation in the core. This is associated with a significant increase in core losses (e.g., 20-30%). Overheating problems may occur, especially with large GICs (Gas Inductance Capacities). Furthermore, when the transformer is installed near residential areas, it generates increased noise emissions during operation, which is particularly bothersome.
[0004] Various active and passive devices are known for DC current compensation or to reduce operating noise of transformers as electrical equipment. However, before taking cost-intensive measures for DC current compensation, it is necessary to determine whether such DC current components actually exist. It is known that when electrical equipment, such as a transformer, is in operation, the DC current component flowing in the transformer causes asymmetric oscillations in the transformer. Summary of the Invention
[0005] Therefore, the technical problem to be solved by the present invention is to provide a method of the type mentioned at the beginning, which enables a simple, fast and reliable determination of whether electrical equipment oscillates asymmetrically when operating in a high-voltage power supply network.
[0006] The present invention solves the above-mentioned technical problems by means of an oscillation sensor to detect vibrations generated during the operation of electrical equipment. The oscillation sensor provides a measurement value on the output side. The measurement value and / or the value derived from the measurement value are transmitted to the communication unit via a short-range communication connection. The measurement value and / or the value derived from the measurement value are transmitted from the communication unit to the data processing cloud via a long-range communication connection (13). The data processing cloud decomposes the measurement value and / or the value derived from the measurement value into its frequency components by means of Fourier transform to obtain the spectrum. The even and odd frequency components of the spectrum are determined according to the fundamental frequency of the high-voltage power supply network, and the ratio R relative to each other is determined. When the ratio R exceeds a predetermined threshold, it is deduced that there is an asymmetric oscillation.
[0007] According to the present invention, it is possible to determine with high reliability, in a rapid and simple manner, whether asymmetric oscillations occur in electrical equipment such as power transformers during operation. To date, the confirmation of asymmetric oscillations has been performed through complex electrical measurements or a series of acoustic measurements on the electrical equipment. Analysis of the measurement data must be performed by experts. In other words, as a result, previously known methods are very costly. In contrast, the method according to the present invention is not only inexpensive but also can be easily performed without requiring special expertise. Therefore, it can be performed by any user, such as the operator of the electrical equipment. If the presence of asymmetric oscillations is confirmed, appropriate measures can be taken to suppress these asymmetric oscillations.
[0008] Within the scope of this invention, the electrical equipment is connected to a high-voltage network during operation. Therefore, the electrical equipment is designed for high voltages between 1kV and 1300kV, and is, for example, a transformer, particularly a power transformer, or a choke. Such a transformer or choke preferably has a tank filled with an insulating fluid. Active components are arranged in this tank, including a magnetizable magnetic core and at least one winding. At least one winding is connected to the high-voltage network carrying AC voltage during operation. The insulating fluid is, for example, an ester liquid or mineral oil. Besides electrically insulating the active components relative to the tank at ground potential, it also serves to cool the components.
[0009] In contrast, electrical equipment includes, for example, resin-cast transformers or dry-type transformers. In a dry-type transformer, the windings are arranged in a resin block or sheet. The resin serves as the solid insulating material. In the case of a dry-type transformer, there is no tank filled with an insulating fluid.
[0010] Mathematically, the method according to the present invention for verifying asymmetric oscillations can be described as follows. Assume S... xNLet f be the signal value of any unit frequency spectrum, where x represents an even number (x = g), an odd number (x = u), or noise (x = n). N is the ordinal number of the signal, where N = 1 corresponds to the fundamental oscillation, and N = 2, 3, 4, ..., Nmax corresponds to harmonic oscillations. With a feed voltage of 50Hz, according to f... gN =50*2*N, to obtain the even frequency f gN According to f uN =50*(2*N+1), yielding the odd-numbered frequencies. The DC current component in the electrical equipment creates additional odd-numbered components in the total frequency spectrum. If we now calculate the ratio R of the sum of all odd-numbered components in the total frequency spectrum to the even-numbered components in the total frequency spectrum, and this ratio R exceeds a predetermined threshold, then the existence of asymmetric oscillations can be inferred. The magnitude of R indicates the effect of the asymmetric oscillations on the magnetic core. Asymmetric oscillations can indicate the DC current component flowing in the electrical equipment.
[0011] Within the scope of this invention, the communication unit, for example, has at least one analog input and at least one digital input. Therefore, multiple sensors can be connected to the communication unit. Not all sensors must be acoustic sensors. The communication unit can also be connected to current sensors, voltage sensors, temperature sensors, or pressure sensors. The communication unit, for example, has a main processor, an auxiliary processor, and a storage unit, which can store preprocessed measurements or values derived therefrom in the storage unit and process them, for example, by averaging. Therefore, measurements from different sensors can be jointly transmitted by the communication unit to a data processing cloud via a long-distance communication connection.
[0012] Users of the method according to the present invention are, for example, operators of energy supply networks who are responsible for a large number of transformers, circuit breakers, capacitor batteries, spark discharge devices, etc.
[0013] As an electrical oscillation sensor, or in other words, a sensor within the scope of this invention, consider any sensor capable of detecting vibrations or oscillations of an electrical device at the input side and providing an electrical signal at the output side based on the amplitude of the vibration. These electrical signals are referred to herein as measured values. The electrical signal can be an analog electrical signal, such as current or voltage, the magnitude of which corresponds to the amplitude of the received sound wave. However, within the scope of this invention, the measured value can also be a digital value, generated, for example, by sampling an analog signal to obtain sampled values and digitizing the sampled values.
[0014] Within the scope of this invention, each oscillation sensor is connected to the communication unit via a short-range communication connection. This short-range communication connection can be, for example, a simple cable. Alternatively, it can be a ZigBee, Bluetooth, wireless, Ambus, or WiFi communication connection. The short-range communication connection can extend up to 100 meters.
[0015] Within the scope of this invention, the connection between the communication unit and the data processing cloud is established via a long-distance communication connection. To establish this connection, the communication unit has a long-distance communication device, such as a mobile radio module according to GPRS or UMTS standards. This mobile radio module is used to establish a long-distance communication connection with the data processing cloud, preferably an IP-based data connection. Here, for example, a mobile radio service provider or telecommunications provider can connect between them, and the long-distance communication connection can be established at least partially via the provider's communication network and / or at least partially via the Internet. Establishing the connection thus requires only very little configuration or parameterization overhead. Apart from configuring the long-distance communication device (e.g., installing a SIM card from a telecommunications provider) using the information required to establish the long-distance communication connection, no further overhead is required for a single communication unit.
[0016] The cloud, or data processing cloud, should be understood here as an arrangement having one or more data storage devices and one or more data processing devices, which can be configured, through appropriate programming, to perform arbitrary data processing procedures. Here, the data processing devices are typically general-purpose data processing devices, such as servers, which initially have no specific design in terms of their architecture or programming. Only through programming can these general-purpose data processing devices be trained to perform specific functions.
[0017] If a cloud has multiple individual components, these components are interconnected in a suitable manner, such as through a communication network, for data communication. Any data can be fed into the data processing cloud for storage and / or processing only. The data processing cloud itself then provides the stored data and / or the results of the data processing to other devices, such as computer workstations, laptops, and smartphones connected to the cloud. The data processing cloud can be provided, for example, by a computing center or multiple networked computing centers. Data processing clouds are typically constructed to be spatially isolated from high-voltage equipment.
[0018] Within the scope of this invention, electrical equipment is designed for operation in a power grid or high-voltage power grid, for example, designed for operating voltages between 1 kV and 1200 kV, particularly between 50 kV and 800 kV. The high-voltage power grid is preferably an AC power grid.
[0019] According to the present invention, electrical equipment includes, for example, transformers, particularly power transformers, chokes, etc.
[0020] In a variation of the method according to the invention, the communication unit is a mobile phone. A so-called "smartphone" is particularly suitable as a mobile phone. A smartphone should be understood here as a high-performance mobile phone. Such a mobile phone is typically equipped with a microphone as an acoustic sensor. Furthermore, such a mobile phone has a memory and a programmable unit, such as at least one processor. However, here, the entire mobile phone is not used to perform the method according to the invention. One aspect of it is used to connect to a data processing cloud. The mobile phone detects transformer noise using its microphone and stores the measured values obtained therein in its storage unit. Connections to the data processing cloud are established at predetermined time intervals, and the measured values are sent to the data processing cloud individually or after averaging.
[0021] In a particularly preferred design, the communication unit is a communication box. The communication box is, for example, fixed to an electrical device. Specifically, the communication box is fixed to the outer wall of the electrical device. Therefore, the communication box can be accessed from the outside.
[0022] In one variation of the method, measurements from multiple oscillation sensors are transmitted together to a data processing cloud. However, the measurements can be preprocessed beforehand, for example, by averaging over the measurement period.
[0023] Mobile phones, or other communication units, advantageously have a storage unit on which measured values or values derived from measured values are stored. The storage unit simplifies any preprocessing of the measured values that may be desired.
[0024] Vibration is preferably detected at different locations on the electrical equipment. To do this, the user records the vibration of the electrical equipment at different points. Then, the average value is calculated over the measurements performed, taking all frequency segments from the correspondingly obtained spectrum. Here, the software preferably guides the user interactively so that the correct steps are performed at the right time.
[0025] Vibrations can be advantageously detected within a pre-given duration. For each measurement, the duration is preferably in the range of 10 to 60 seconds.
[0026] In an advantageous variation of the invention, the geographical location of the corresponding communication unit and the electrical equipment connected thereto is determined by means of an antenna arranged in the communication unit for location determination and transmitted to the data processing cloud.
[0027] In another advantageous embodiment of the invention, acoustic signals are detected at locations (A, B, C, D) on the electrical equipment. For this purpose, multiple oscillation sensors are fixedly mounted within the electrical equipment. Attached Figure Description
[0028] Other suitable designs and advantages of the invention are the subject of the following description of embodiments of the invention with reference to the accompanying drawings, wherein like reference numerals indicate like functional components, and wherein,
[0029] Figure 1 An embodiment of the method according to the invention is illustrated schematically, and
[0030] Figure 2 Another embodiment of the invention is illustrated schematically. Detailed Implementation
[0031] Figure 1 An embodiment of the method according to the invention is shown, wherein a transformer 1 is schematically illustrated as an electrical device. The transformer 1 has a tank 2 filled with an insulating fluid such as an ester liquid or mineral oil. A magnetizable magnetic core 3 is arranged in the tank 2, forming a closed magnetic circuit. The legs of the magnetic core 3 are each surrounded by two windings arranged concentrically relative to each other, with only the outer high-voltage winding 4 visible. The windings are respectively connected to a high-voltage network carrying alternating current through insulating bushings 5.
[0032] Expansion vessel 6 is used to balance the volume fluctuations of the insulating fluid in tank 2 of transformer 1 caused by temperature. A Buchholz relay 7 can be seen in the connection line between tank 2 and expansion vessel 6.
[0033] also, Figure 1 An oscillation sensor 2, shown only schematically, detects vibrations of transformer 1 at two different locations, A and B. The oscillation sensor 8 is connected to a communication unit 12, here referred to as a communication box, via a Bluetooth connection 11, which serves as a short-range communication link. The communication box 12 is fixedly mounted on the outer side of the wall of tank 2. The communication box 12 has a storage unit on which the measurements provided by the oscillation sensor 8 are stored in a position-resolved manner. Every 2 minutes, the communication box 12 connects to a data processing cloud 9 via a long-range communication connection 13 and transmits the measurements stored on its hard drive to the data processing cloud 9 via the long-range communication connection 13. The data processing cloud 9 performs the analysis method described above to detect asymmetric oscillations of electrical equipment 1.
[0034] The data processing cloud 9 has software that performs a Fourier transform on the transmitted measurements. Then, the ratio R, as described above, is formed. According to the method of the invention, the magnitude of R is used to deduce whether and to what extent asymmetric oscillations exist, and if necessary, at what order of magnitude a DC current component load is applied to the transformer. The user uses the results from the method to determine the certainty regarding the DC current component, and at this point, appropriate countermeasures can be initiated to suppress the potentially determined DC current component.
[0035] You can use a laptop or computer to access the data processing cloud to obtain analysis results.
[0036] Figure 2 Another embodiment for carrying out the method according to the invention is shown, and transformer 1 can be seen as an electrical device, which substantially corresponds to... Figure 1 The transformer shown in the image. However, compared to... Figure 1 The transformer shown is different, according to Figure 2 The transformer 1 has four oscillation sensors 8 arranged inside the tank 2. Each oscillation sensor 8 is connected to a communication unit 12, implemented as a communication box, via a short-range communication connection 11 configured as a Bluetooth connection. In the illustrated embodiment, the communication unit 12 is not fixedly attached to the transformer 1. Instead, the communication unit 12 is located in a nearby housing (not shown) at a distance of approximately 20 m from the transformer 1.
[0037] The communication unit 12 has four input terminals, allowing all four sensors 8 to be connected simultaneously. The sensors 8 detect vibrations generated during the operation of the transformer 1, and generate analog electrical signals (current, in this case) based on the amplitude of the vibration or oscillation. These analog signals are sampled, and the resulting sampled values are digitized. These digitized values are referred to as measured values.
[0038] The measured values are transmitted to the communication unit 12 via the short-range communication connection 11. The communication unit 12 has a storage unit (not shown in the figure) on which the measured values are stored.
[0039] In a variation of the method according to the invention, the measured values are preprocessed, for example, by averaging the measured values transmitted at 2-second intervals over a 2-minute time period, and the average value is stored in a storage unit. The communication unit 12 establishes a connection with the data processing cloud 9 every 2 minutes via a long-distance communication connection 13. The measured values, averaged measured values, or values derived from the measured values are transmitted to the data processing cloud 9. The data processing cloud 9 then examines the measured values using suitable software; in other words, it performs a Fourier transform and checks the resulting spectrum for the presence of asymmetric oscillations. The analysis method has been described in more detail above.
Claims
1. A method for determining asymmetric oscillations during operation of a transformer or choke (1), said transformer or choke being connected to a high-voltage network, wherein, The asymmetric oscillation during the operation of the transformer or choke is caused by the DC current component flowing in the transformer or choke, wherein, - The oscillations generated during the operation of the transformer or choke (1) are detected by multiple oscillation sensors (8), which detect oscillations at different locations (A, B, C, D) of the transformer or choke (1) respectively, and provide measurement values on the output side. - The measured value and / or the value derived from the measured value are transmitted to the communication unit (12) via a short-range communication connection (11). - The measured value and / or the value derived from the measured value are transmitted from the communication unit (12) to the data processing cloud (9) via the long-distance communication connection (13). - The data processing cloud (9) uses Fourier transform to decompose the measured value and / or the value derived from the measured value into its frequency components to obtain the spectrum. - The even and odd frequency components of the spectrum are determined based on the fundamental frequency of the high-voltage power supply network, and the ratio R relative to each other is determined. - When the ratio R exceeds a predetermined threshold, it is deduced that asymmetric oscillation exists.
2. The method according to claim 1, Its features are, Each communication unit (12) has a storage unit on which the measured value and / or the value derived from the measured value are stored.
3. The method according to claim 2, Its features are, Using an antenna arranged in the communication unit (12) for location determination, the geographical location of the corresponding communication unit (12) and the transformer or choke (1) connected thereto is determined and transmitted to the data processing cloud (9).
4. The method according to claim 2 or 3, Its features are, The communication unit (12) is a mobile phone.
5. The method according to any one of claims 1 to 3, Its features are, Oscillations are detected over a pre-defined time period.
6. A computer program for a computing device, Its features are, The computer program is suitable for performing the method according to any one of claims 1 to 5.
7. A storage medium, Its features are, The storage medium stores the computer program according to claim 6.