A method, system and device for suppressing ferroresonance in electromagnetic voltage transformers

Abstract

This invention discloses a method, system, and device for suppressing ferroresonance in electromagnetic voltage transformers, relating to the field of suppressing ferroresonance in electromagnetic voltage transformers. The method includes: acquiring the three-phase excitation current of the electromagnetic voltage transformer using a Rogowski coil, and calculating the power frequency excitation impedance of each phase of the electromagnetic voltage transformer based on the three-phase excitation current and three-phase excitation voltage; determining whether the electromagnetic voltage transformer is resonating based on the open delta zero-sequence voltage; if the electromagnetic voltage transformer is resonating, determining the resonance type of the electromagnetic voltage transformer based on the open delta zero-sequence voltage and the power frequency excitation impedance; eliminating the resonance by adding a harmonic suppression resistor to the open delta of the electromagnetic voltage transformer according to the resonance type; if the electromagnetic voltage transformer is not resonating, determining that the electromagnetic voltage transformer has experienced a single-phase grounding fault or an open-circuit fault. This invention can improve the accuracy of fault type determination and avoid problems such as failed harmonic suppression or damage to the harmonic suppression resistor.

Description

Technical Field

[0001] This invention relates to the field of suppressing ferroresonance in electromagnetic voltage transformers, and in particular to a method, system, and device for suppressing ferroresonance in electromagnetic voltage transformers. Background Technology

[0002] For unconnected systems in low-voltage distribution networks, after a ground fault disappears, since only the neutral point of the electromagnetic voltage transformer is grounded, the charge stored in the system's ground capacitance can only be discharged through the electromagnetic voltage transformer. This often causes the electromagnetic voltage transformer to have ferroresonance, leading to frequent faults such as fuse blowout and overheating damage.

[0003] To limit the ferroresonant overvoltage in electromagnetic voltage transformers, the following measures are commonly used:

[0004] (1) The open delta-connected damping resistor of the electromagnetic voltage transformer is equivalent to a resistor connected in parallel across the excitation winding of the electromagnetic voltage transformer. Its drawbacks are: if the resistor is too large, it will not have a harmonic suppression effect; if the resistor is too small, when a single-phase ground fault occurs and the system operates continuously for 1-2 hours, the electromagnetic voltage transformer needs a sufficiently large heat capacity. Therefore, incandescent lamps are generally chosen as damping resistors, taking advantage of their low cold resistance and high hot resistance. However, ferroresonance is often triggered after the single-phase ground fault disappears. If the single-phase ground fault lasts for a long time, the incandescent lamp's resistance increases significantly due to heat, and it usually cannot suppress ferroresonance.

[0005] (2) A nonlinear resistor is connected in series between the neutral point and ground on the primary side of the electromagnetic voltage transformer. This device has limitations in application: it can only ensure that the electromagnetic voltage transformer itself does not saturate, and it is ineffective for other electromagnetic voltage transformers in the system. Therefore, each electromagnetic voltage transformer must be equipped with a nonlinear resistor to achieve the harmonic elimination effect.

[0006] (3) The wiring method using 4 electromagnetic voltage transformers. This method also has its own problems: similar to adding a nonlinear resistor harmonic suppressor, it can only ensure that the electromagnetic voltage transformer does not saturate, but cannot suppress the ferroresonance of the entire system.

[0007] It is evident that secondary harmonic suppression is more economical than primary harmonic suppression, which is why microprocessor-based harmonic suppression devices are widely used in domestic power systems. The core technical problem currently is that electromagnetic voltage transformers often experience one or more phases of saturation during operation, such as grounding, lightning strikes, and closing. In actual production, two phases are usually saturated. If parameters are matched, power frequency resonance occurs, resulting in a decrease in the voltage between the unsaturated phases and the increased voltage between the saturated phases and the ground. Simultaneously, the high zero-sequence voltage at the open delta output is similar to the voltage characteristics of a single-phase grounding fault, a so-called illusory grounding fault. Under these conditions, the excitation impedance of the saturated phase decreases, and the excitation current increases. Without harmonic suppression, this can lead to the high-voltage side fuse of the saturated transformer blowing or even the high-voltage winding overheating and burning out. On the other hand, for ungrounded systems, maintaining operation for 2 hours during a single-phase grounding fault to improve power supply reliability is a significant advantage. However, activating harmonic suppression resistors under single-phase grounding conditions can cause them to thermally collapse and burn out; therefore, activating harmonic suppression resistors is not permitted. Currently, the fault type is usually determined by the difference between the open delta voltage of the voltage transformer during power frequency resonance and single-phase grounding. However, this method has low accuracy and often leads to failure of harmonic suppression or damage to the harmonic suppression resistor. Summary of the Invention

[0008] The purpose of this invention is to provide a method, system, and device for suppressing ferroresonance in electromagnetic voltage transformers, in order to solve the problem that existing resonance suppression methods have low accuracy in judging fault types, often leading to failure of resonance suppression or damage to the resonance suppression resistor.

[0009] To achieve the above objectives, the present invention provides the following solution:

[0010] A method for suppressing ferroresonance in an electromagnetic voltage transformer includes adding a Rogowski coil to the electromagnetic voltage transformer, comprising:

[0011] Obtain the zero-sequence voltage at the opening angle and the three-phase excitation voltage of the electromagnetic voltage transformer;

[0012] The three-phase excitation current of the electromagnetic voltage transformer is collected using the Rogowski coil, and the power frequency excitation impedance of each phase of the electromagnetic voltage transformer is calculated based on the three-phase excitation current and the three-phase excitation voltage.

[0013] Determine whether the electromagnetic voltage transformer resonates based on the open delta zero-sequence voltage.

[0014] If the electromagnetic voltage transformer resonates, the resonance type of the electromagnetic voltage transformer is determined based on the open delta zero-sequence voltage and the power frequency excitation impedance; the resonance type includes frequency division resonance, power frequency resonance, and fundamental frequency resonance.

[0015] According to the resonance type, a harmonic suppression resistor is inserted into the open delta of the electromagnetic voltage transformer to eliminate the resonance;

[0016] If the electromagnetic voltage transformer does not resonate, it is determined that the electromagnetic voltage transformer has experienced a single-phase grounding fault or a broken wire fault.

[0017] Optionally, determining whether the electromagnetic voltage transformer resonates based on the open delta zero-sequence voltage specifically includes:

[0018] When the open delta zero-sequence voltage is in the first voltage range, it is determined that the electromagnetic voltage transformer is operating normally;

[0019] When the open delta zero-sequence voltage is in the second voltage range, it is determined that the electromagnetic voltage transformer has a broken wire fault.

[0020] When the zero-sequence voltage of the open delta is in the third voltage range, it is determined that the electromagnetic voltage transformer is in resonance.

[0021] Optionally, determining the resonance type of the electromagnetic voltage transformer based on the open delta zero-sequence voltage and the power frequency excitation impedance specifically includes:

[0022] Calculate the frequency division and frequency doubling of the zero-sequence voltage of the open delta;

[0023] When the power frequency excitation impedance of one or more phases is less than the power frequency excitation impedance threshold and the frequency division amount is greater than the voltage threshold, it is determined that the electromagnetic voltage transformer has undergone frequency division resonance.

[0024] When the power frequency excitation impedance of one or more phases is less than the power frequency excitation impedance threshold and the frequency multiplication factor is greater than the voltage threshold, it is determined that the electromagnetic voltage transformer has power frequency resonance.

[0025] When the power frequency excitation impedance of one or more phases is less than the power frequency excitation impedance threshold, and the frequency division is less than or equal to the voltage threshold, and the frequency doubling is less than or equal to the voltage threshold, it is determined that the electromagnetic voltage transformer has undergone fundamental frequency resonance.

[0026] When the power frequency excitation impedance of each phase is greater than or equal to the power frequency excitation impedance threshold, it is determined that the electromagnetic voltage transformer has experienced a single-phase grounding.

[0027] Optionally, the resistance value R of the harmonic suppression resistor is:

[0028]

[0029] Among them, X m K represents the excitation impedance of the single-phase winding of the electromagnetic voltage transformer under the line voltage.13 The transformation ratio of the primary winding to the open delta winding of the electromagnetic voltage transformer is given.

[0030] Optionally, the step of eliminating resonance by inserting a harmonic-suppressing resistor into the open delta of the electromagnetic voltage transformer according to the resonance type specifically includes:

[0031] When the frequency division is less than or equal to the voltage threshold and the frequency harmonic is less than or equal to the voltage threshold, the frequency division resonance and the frequency harmonic harmonic are eliminated, and the open delta harmonic elimination resistor is removed.

[0032] When the power frequency excitation impedance of any phase is less than the power frequency excitation impedance threshold, it is determined that the power frequency resonance has not been eliminated. The harmonic elimination resistor is kept in the engaged state until the power frequency resonance is eliminated, and then the open delta harmonic elimination resistor is deactivated.

[0033] A ferroresonant suppression system for an electromagnetic voltage transformer, comprising adding a Rogowski coil to the electromagnetic voltage transformer, including:

[0034] The voltage acquisition module is used to acquire the zero-sequence voltage at the opening angle and the three-phase excitation voltage of the electromagnetic voltage transformer.

[0035] The current acquisition module is used to acquire the three-phase excitation current of the electromagnetic voltage transformer using the Rogowski coil, and to calculate the power frequency excitation impedance of each phase of the electromagnetic voltage transformer based on the three-phase excitation current and the three-phase excitation voltage.

[0036] The resonance judgment module is used to determine whether the electromagnetic voltage transformer is resonating based on the open delta zero-sequence voltage.

[0037] The resonance type determination module is used to determine the resonance type of the electromagnetic voltage transformer based on the open delta zero-sequence voltage and the power frequency excitation impedance if the electromagnetic voltage transformer resonates; the resonance type includes frequency division resonance, power frequency resonance and fundamental frequency resonance.

[0038] A resonance cancellation module is used to eliminate resonance by inserting a resonance cancellation resistor into the open delta of the electromagnetic voltage transformer according to the resonance type.

[0039] The normal operation or open circuit fault determination module is used to determine whether the electromagnetic voltage transformer has experienced a single-phase grounding fault or an open circuit fault if the electromagnetic voltage transformer does not resonate.

[0040] Optionally, the resonance determination module specifically includes:

[0041] The normal operation determination unit is used to determine that the electromagnetic voltage transformer is operating normally when the open delta zero-sequence voltage is in the first voltage range.

[0042] The open-circuit fault detection unit is used to determine that the electromagnetic voltage transformer has experienced an open-circuit fault when the open delta zero-sequence voltage is in the second voltage range.

[0043] The resonance generating unit is used to determine that the electromagnetic voltage transformer resonates when the open delta zero-sequence voltage is in the third voltage range.

[0044] Optionally, the resonance type determination module specifically includes:

[0045] The frequency division and multiplication calculation unit is used to calculate the frequency division and multiplication of the open delta zero-sequence voltage.

[0046] The frequency division resonance determination unit is used to determine that the electromagnetic voltage transformer has undergone frequency division resonance when the power frequency excitation impedance of one or more phases is less than the power frequency excitation impedance threshold and the frequency division amount is greater than the voltage threshold.

[0047] The power frequency resonance determination unit is used to determine that the electromagnetic voltage transformer has power frequency resonance when the power frequency excitation impedance of one or more phases is less than the power frequency excitation impedance threshold and the frequency doubling is greater than the voltage threshold.

[0048] The fundamental frequency resonance determination unit is used to determine that the electromagnetic voltage transformer has fundamental frequency resonance when the power frequency excitation impedance of one or more phases is less than the power frequency excitation impedance threshold, the frequency division amount is less than or equal to the voltage threshold, and the frequency doubling amount is less than or equal to the voltage threshold.

[0049] A single-phase grounding determination unit is used to determine that the electromagnetic voltage transformer has experienced a single-phase grounding when the power frequency excitation impedance of each phase is greater than or equal to the power frequency excitation impedance threshold.

[0050] An electronic device includes a memory and a processor, the memory storing a computer program, and the processor running the computer program to cause the electronic device to perform the above-described electromagnetic voltage transformer ferromagnetic resonance suppression method.

[0051] A computer-readable storage medium storing a computer program that, when executed by a processor, implements the above-described method for suppressing ferromagnetic resonance in an electromagnetic voltage transformer.

[0052] According to specific embodiments provided by the present invention, the following technical effects are disclosed: The present invention provides a method, system, and device for suppressing ferroresonance in an electromagnetic voltage transformer. It utilizes a Rogowski coil to directly acquire the open-delta zero-sequence voltage, three-phase excitation current, and three-phase excitation voltage of the electromagnetic voltage transformer. The acquired voltage and current are used to determine the power frequency excitation impedance of each phase of the electromagnetic voltage transformer. Based on the open-delta zero-sequence voltage and the power frequency excitation impedance of each phase, the resonance type of the electromagnetic voltage transformer is determined. Based on the resonance type, a harmonic suppression resistor is applied to eliminate resonance. The present invention is based on the fundamental electromagnetic principle that the excitation impedance of a transformer inevitably decreases when the transformer is saturated. By using the excitation impedance to determine whether the transformer is resonating, it has high sensitivity and accuracy, obtaining a more accurate resonance type. Harmonic suppression is performed for different resonance types, avoiding problems such as harmonic suppression identification or damage to the harmonic suppression resistor. Attached Figure Description

[0053] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0054] Figure 1 This is a schematic diagram of the product structure provided by the present invention;

[0055] Figure 2 The flowchart of the electromagnetic voltage transformer ferroresonance suppression method provided by the present invention is shown below.

[0056] Figure 3 The flowchart for determining the resonance type provided by this invention is shown. Detailed Implementation

[0057] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0058] The purpose of this invention is to provide a method, system, and device for suppressing ferroresonance in electromagnetic voltage transformers, which can improve the accuracy of fault type identification and avoid problems such as failure of harmonic suppression or damage to the harmonic suppression resistor.

[0059] To make the above-mentioned objects, features and advantages of the present invention more apparent and understandable, the present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments.

[0060] Figure 1 This is a schematic diagram of the product structure provided by the present invention, such as... Figure 1 As shown, the human-machine interface system is used for displaying, inputting data, or sending various commands; the MCU is used for data interaction, calculation, and storage; the analog input system is used to acquire current and voltage data; the thyristor trigger signal is used for switching the harmonic suppression resistor; and the communication interface is used for interaction with the outside world.

[0061] Example 1

[0062] Figure 2 The flowchart of the electromagnetic voltage transformer ferroresonance suppression method provided by the present invention is as follows: Figure 2 As shown, a method for suppressing ferroresonance in an electromagnetic voltage transformer involves adding a Rogowski coil to the electromagnetic voltage transformer, including:

[0063] Step 201: Obtain the zero-sequence voltage at the opening angle and the three-phase excitation voltage of the electromagnetic voltage transformer.

[0064] Step 202: Use the Rogowski coil to collect the three-phase excitation current of the electromagnetic voltage transformer, and calculate the power frequency excitation impedance of each phase of the electromagnetic voltage transformer based on the three-phase excitation current and the three-phase excitation voltage.

[0065] Compared with traditional current measuring devices, Rogowski coils have outstanding advantages such as no saturation, good linearity, easy calibration, outstanding transient response capability, wide frequency range of the measured current (from 0.1Hz to 1MHz), large range of the measured current (from 1mA to 1mA), and small phase difference.

[0066] Step 203: Determine whether the electromagnetic voltage transformer resonates based on the open delta zero-sequence voltage. If yes, proceed to step 204; otherwise, proceed to step 206.

[0067] In practical applications, step 203 specifically includes: when the open delta zero-sequence voltage is in the first voltage range, determining that the electromagnetic voltage transformer is operating normally; when the open delta zero-sequence voltage is in the second voltage range, determining that the electromagnetic voltage transformer has experienced a wire breakage fault; when the open delta zero-sequence voltage is in the third voltage range, determining that the electromagnetic voltage transformer has experienced resonance or single-phase grounding; the first voltage range is 0–15V; the second voltage range is 31–35V; and the third voltage range is 85–110V.

[0068] Step 204: Determine the resonance type of the electromagnetic voltage transformer based on the open delta zero-sequence voltage and the power frequency excitation impedance; the resonance type includes frequency division resonance, power frequency resonance and fundamental frequency resonance.

[0069] In practical applications, step 204 specifically includes: calculating the frequency division and frequency multiplication of the open delta zero-sequence voltage; determining that the electromagnetic voltage transformer has undergone frequency division resonance when the power frequency excitation impedance of one or more phases is less than the power frequency excitation impedance threshold and the frequency division is greater than the voltage threshold; determining that the electromagnetic voltage transformer has undergone power frequency resonance when the power frequency excitation impedance of one or more phases is less than the power frequency excitation impedance threshold and the frequency multiplication is greater than the voltage threshold; determining that the electromagnetic voltage transformer has undergone fundamental frequency resonance when the power frequency excitation impedance of one or more phases is less than the power frequency excitation impedance threshold and the frequency division is less than or equal to the voltage threshold and the frequency multiplication is less than or equal to the voltage threshold; determining that the electromagnetic voltage transformer has undergone single-phase grounding when the power frequency excitation impedance of each phase is greater than or equal to the power frequency excitation impedance threshold; the voltage threshold is 85V.

[0070] Step 205: According to the resonance type, add a harmonic suppression resistor to the open delta of the electromagnetic voltage transformer to eliminate resonance.

[0071] In practical applications, the resistance value R of the harmonic suppression resistor is:

[0072]

[0073] Among them, X m K represents the excitation impedance of the single-phase winding of the electromagnetic voltage transformer under the line voltage. 13 The transformation ratio of the primary winding to the open delta winding of the electromagnetic voltage transformer is given.

[0074] In practical applications, step 205 specifically includes: when the frequency division is less than or equal to the voltage threshold and the frequency doubling is less than or equal to the voltage threshold, it is determined that the frequency division resonance and the frequency doubling resonance are eliminated, and the open delta harmonic elimination resistor is removed; when the power frequency excitation impedance of any phase is less than the power frequency excitation impedance threshold, it is determined that the power frequency resonance is not eliminated, and the harmonic elimination resistor is kept in the engaged state until the power frequency resonance is eliminated, and the open delta harmonic elimination resistor is removed.

[0075] Step 206: Determine whether the electromagnetic voltage transformer has experienced a single-phase grounding fault or a wire breakage fault.

[0076] This invention uses a coil to collect the actual excitation current of an electromagnetic voltage transformer, calculates the actual excitation impedance of the transformer, and compares it with the excitation impedance at rated voltage to determine whether the transformer is resonating. By performing Fourier analysis on the open delta voltage of the transformer, the voltage waveform spectrum characteristics are obtained. Based on the voltage waveform spectrum characteristics, the resonance type of the transformer is determined, achieving the goal of timely switching on and off the harmonic elimination resistor and rapid harmonic elimination. The voltage waveform spectrum characteristics include frequency division and harmonic harmonics.

[0077] This invention utilizes Rogowski coils to directly measure the amplitude, frequency, and harmonic content of the actual excitation current of a current transformer.

[0078] This invention can accurately determine whether a current transformer is experiencing ferroresonance by comparing the three-phase excitation current with that during normal operation.

[0079] This invention can further improve the sensitivity of determining whether a current transformer is experiencing ferroresonance by comparing the excitation impedance with that under normal operation.

[0080] This invention can accurately determine the resonant frequency of a current transformer by performing harmonic analysis on the three-phase excitation current.

[0081] Based on the judgment result, this invention enables rapid harmonic elimination by switching the harmonic elimination resistor on or off the open delta terminal of the electromagnetic voltage transformer.

[0082] The entire system of this invention only requires the selection of one current transformer for control, making maintenance and management convenient.

[0083] Example 2

[0084] Figure 3 The flowchart for determining the resonance type provided by this invention is as follows: Figure 3 As shown, in this embodiment, the present invention specifically includes the following steps:

[0085] Step 1: Install three Rogowski coils on the electromagnetic voltage transformer. Hereinafter referred to as the transformer.

[0086] Step 2: Collect the open delta zero-sequence voltage U0. If this voltage is in the first voltage range, the system is considered to be operating normally. If this voltage is in the second voltage range, the phase is considered to have a broken wire fault. If this voltage is in the third voltage range, perform a Fourier transform on this voltage wave to obtain the voltage wave spectrum characteristics.

[0087] It should be noted that the first voltage range, the second voltage range, and the third voltage range do not overlap.

[0088] Step 3: When the zero-sequence voltage U0 is in the third voltage range, calculate the power frequency excitation impedance of each phase of the transformer by measuring the effective values ​​of the three-phase voltage and the effective values ​​of the three-phase current. If the first condition is met, it is determined that the transformer has undergone frequency division resonance. The first condition is that the excitation impedance of one or more phases of the transformer is less than the power frequency excitation impedance threshold, and the calculated zero-sequence voltage frequency division is greater than the voltage threshold.

[0089] Step 4: When the zero-sequence voltage U0 is in the third voltage range, calculate the power frequency excitation impedance of each phase of the transformer by measuring the effective values ​​of the three-phase voltage and the effective values ​​of the three-phase current. If the second condition is met, it is determined that the transformer has power frequency resonance. The second condition is that the excitation impedance of one or more phases of the transformer is less than the power frequency excitation impedance threshold, and the calculated zero-sequence voltage frequency multiplication factor is greater than the voltage threshold.

[0090] Step 5: When the zero-sequence voltage U0 is in the third voltage range, calculate the power frequency excitation impedance of each phase of the transformer by measuring the effective values ​​of the three-phase voltage and the effective values ​​of the three-phase current. If the third condition is met, it is determined that the transformer has undergone fundamental frequency resonance. The third condition is that the excitation impedance of one or more phases of the transformer is less than the power frequency excitation impedance threshold, and the calculated frequency division of the zero-sequence voltage U0 is less than or equal to the voltage threshold, and the frequency harmonic of the zero-sequence voltage U0 is less than or equal to the voltage threshold.

[0091] Step 6: When the zero-sequence voltage U0 is in the third voltage range, calculate the power frequency excitation impedance of each phase of the transformer by measuring the effective values ​​of the three-phase voltage and the effective values ​​of the three-phase current. If the fourth condition is met, it is determined that a single-phase grounding has occurred in the system. The fourth condition is that the excitation impedance of each phase of the transformer is greater than or equal to the power frequency excitation impedance threshold.

[0092] Step 7: Based on the above judgment, if the electromagnetic voltage transformer resonates at low frequency, fundamental frequency, or harmonic frequency, a harmonic suppression resistor is connected in the open delta of the electromagnetic voltage transformer.

[0093] The resistance value is recommended to be selected according to GB / T50064-2014 "Code for Design of Overvoltage Protection and Insulation Coordination of AC Electrical Installations":

[0094] Among them, X m K represents the excitation impedance of a single-phase winding of a voltage transformer under line voltage. 13 Let X be the transformation ratio of the primary winding to the open delta winding of the current transformer. If multiple electromagnetic voltage transformers operate in parallel in the system, then X... m These are values ​​that are run in parallel.

[0095] Step 8: Analyze the frequency division and frequency doubling of the zero-sequence voltage U0. If the frequency division is less than or equal to the voltage threshold and the frequency doubling is less than or equal to the voltage threshold, then the frequency division resonance and frequency doubling resonance of the transformer are eliminated.

[0096] Step 9: Calculate the power frequency excitation impedance of each phase of the current transformer by measuring the effective values ​​of the three-phase voltage and the effective values ​​of the three-phase current. If the excitation impedance of each phase of the current transformer is greater than or equal to the power frequency excitation impedance threshold, it is determined that the power frequency resonance has been eliminated, and the open delta harmonic elimination resistor is removed.

[0097] Step 10: Calculate the power frequency excitation impedance of each phase of the transformer by measuring the effective values ​​of the three-phase voltage and the effective values ​​of the three-phase current. If the excitation impedance of any phase of the transformer is less than the power frequency excitation impedance threshold, it is determined that the power frequency resonance of the transformer has not been eliminated. Keep the open delta resistor in the working state and repeat step 9 until the power frequency resonance is eliminated, and then remove the open delta harmonic elimination resistor.

[0098] Example 3

[0099] In order to implement the method corresponding to Embodiment 1 above and achieve the corresponding functions and technical effects, an electromagnetic voltage transformer ferromagnetic resonance suppression system is provided below.

[0100] A ferroresonant suppression system for an electromagnetic voltage transformer, comprising adding a Rogowski coil to the electromagnetic voltage transformer, including:

[0101] The voltage acquisition module is used to acquire the zero-sequence voltage at the opening angle and the three-phase excitation voltage of the electromagnetic voltage transformer.

[0102] The current acquisition module is used to acquire the three-phase excitation current of the electromagnetic voltage transformer using the Rogowski coil, and to calculate the power frequency excitation impedance of each phase of the electromagnetic voltage transformer based on the three-phase excitation current and the three-phase excitation voltage.

[0103] The resonance judgment module is used to determine whether the electromagnetic voltage transformer is resonating based on the open delta zero-sequence voltage.

[0104] In practical applications, the resonance judgment module specifically includes: a normal operation determination unit, used to determine that the electromagnetic voltage transformer is operating normally when the open delta zero-sequence voltage is in the first voltage range; a wire breakage fault occurrence unit, used to determine that the electromagnetic voltage transformer has experienced a wire breakage fault when the open delta zero-sequence voltage is in the second voltage range; and a resonance occurrence unit, used to determine that the electromagnetic voltage transformer has experienced resonance when the open delta zero-sequence voltage is in the third voltage range.

[0105] The resonance type determination module is used to determine the resonance type of the electromagnetic voltage transformer based on the open delta zero-sequence voltage and the power frequency excitation impedance if the electromagnetic voltage transformer resonates; the resonance type includes frequency division resonance, power frequency resonance and fundamental frequency resonance.

[0106] In practical applications, the resonance type determination module specifically includes: a frequency division and harmonic calculation unit, used to calculate the frequency division and harmonic of the open delta zero-sequence voltage; a frequency division resonance determination unit, used to determine that the electromagnetic voltage transformer has undergone frequency division resonance when the power frequency excitation impedance of one or more phases is less than the power frequency excitation impedance threshold and the frequency division is greater than the voltage threshold; and a power frequency resonance determination unit, used when the power frequency excitation impedance of one or more phases is less than the power frequency excitation impedance threshold and the harmonic is greater than the voltage threshold. At a voltage threshold, the electromagnetic voltage transformer is determined to have experienced power frequency resonance; the fundamental frequency resonance determination unit is used to determine that the electromagnetic voltage transformer has experienced fundamental frequency resonance when the power frequency excitation impedance of one or more phases is less than the power frequency excitation impedance threshold, and the frequency division is less than or equal to the voltage threshold, and the frequency harmonic is less than or equal to the voltage threshold; the single-phase grounding determination unit is used to determine that the electromagnetic voltage transformer has experienced single-phase grounding when the power frequency excitation impedance of each phase is greater than or equal to the power frequency excitation impedance threshold.

[0107] The resonance cancellation module is used to eliminate resonance by inserting a harmonic cancellation resistor into the open delta of the electromagnetic voltage transformer according to the resonance type.

[0108] The normal operation or open circuit fault determination module is used to determine whether the electromagnetic voltage transformer has experienced a single-phase grounding fault or an open circuit fault if the electromagnetic voltage transformer does not resonate.

[0109] Example 4

[0110] This invention provides an electronic device including a memory and a processor. The memory stores a computer program, and the processor runs the computer program to enable the electronic device to perform the electromagnetic voltage transformer ferromagnetic resonance suppression method provided in Embodiment 1.

[0111] In practical applications, the aforementioned electronic devices can be servers.

[0112] In practical applications, electronic devices include: at least one processor, memory, bus, and communication interface.

[0113] The processor, communication interface, and memory communicate with each other via a communication bus.

[0114] A communication interface is used to communicate with other devices.

[0115] The processor is used to execute programs, specifically the methods described in the above embodiments.

[0116] Specifically, the program may include program code, which includes computer operation instructions.

[0117] The processor may be a central processing unit (CPU), an application-specific integrated circuit (ASIC), or one or more integrated circuits configured to implement embodiments of the present invention. The electronic device may include one or more processors of the same type, such as one or more CPUs; or it may include processors of different types, such as one or more CPUs and one or more ASICs.

[0118] Memory is used to store programs. Memory may include high-speed RAM, and may also include non-volatile memory, such as at least one disk drive.

[0119] Based on the description of the above embodiments, this application provides a storage medium storing computer program instructions thereon, which can be executed by a processor to implement the methods described in any embodiment.

[0120] The electromagnetic voltage transformer ferroresonance suppression system provided in this application exists in various forms, including but not limited to:

[0121] (1) Mobile communication devices: These devices are characterized by their mobile communication capabilities and primarily aim to provide voice and data communication. These terminals include: smartphones (e.g., iPhones), multimedia phones, feature phones, and low-end phones, etc.

[0122] (2) Ultra-mobile personal computer devices: These devices fall under the category of personal computers, possessing computing and processing capabilities, and generally also have mobile internet access capabilities. These terminals include PDAs, MIDs, and UMPCs, such as the iPad.

[0123] (3) Portable entertainment devices: These devices can display and play multimedia content. This category includes: audio and video players (such as iPods), handheld game consoles, e-books, as well as smart toys and portable car navigation devices.

[0124] (4) Other electronic devices with data interaction functions.

[0125] Specific embodiments of the subject matter have now been described. Other embodiments are within the scope of the appended claims. In some cases, the actions described in the claims can be performed in a different order and still achieve the desired result. Furthermore, the processes depicted in the drawings do not necessarily require a specific or sequential order to achieve the desired result. In some embodiments, multitasking and parallel processing can be advantageous.

[0126] The systems, devices, modules, or units described in the above embodiments can be implemented by computer chips or entities, or by products with certain functions. A typical implementation device is a computer. Specifically, a computer can be, for example, a personal computer, laptop computer, cellular phone, camera phone, smartphone, personal digital assistant, media player, navigation device, email device, game console, tablet computer, wearable device, or any combination of these devices.

[0127] For ease of description, the above apparatus is described by dividing it into various functional units. Of course, in implementing this application, the functions of each unit can be implemented in one or more software and / or hardware components. Those skilled in the art will understand that embodiments of this application can be provided as methods, systems, or computer program products. Therefore, this application can take the form of a completely hardware embodiment, a completely software embodiment, or an embodiment combining software and hardware aspects. Furthermore, this application can take the form of a computer program product implemented on one or more computer-usable storage media (including but not limited to disk storage, CD-ROM, optical storage, etc.) containing computer-usable program code.

[0128] This application is described with reference to flowchart illustrations and / or block diagrams of methods, apparatus (systems), and computer program products according to embodiments of this application. It will be understood that each block of the flowchart illustrations and / or block diagrams, and combinations of blocks in the flowchart illustrations and / or block diagrams, can be implemented by computer program instructions. These computer program instructions can be provided to a processor of a general-purpose computer, special-purpose computer, embedded processor, or other programmable data processing apparatus to produce a machine, such that the instructions, which execute via the processor of the computer or other programmable data processing apparatus, create a machine for implementing the flowchart illustrations and / or block diagrams. Figure 1 One or more processes and / or boxes Figure 1 A device that provides the functions specified in one or more boxes.

[0129] These computer program instructions may also be stored in a computer-readable storage medium that can direct a computer or other programmable data processing device to function in a particular manner, such that the instructions stored in the computer-readable storage medium produce an article of manufacture including instruction means, which are implemented in a process Figure 1 One or more processes and / or boxes Figure 1 The function specified in one or more boxes.

[0130] These computer program instructions may also be loaded onto a computer or other programmable data processing equipment to cause a series of operational steps to be performed on the computer or other programmable equipment to produce a computer-implemented process, thereby providing instructions that execute on the computer or other programmable equipment for implementing the process. Figure 1 One or more processes and / or boxes Figure 1 The steps of the function specified in one or more boxes.

[0131] In a typical configuration, a computing device includes one or more processors (CPU), input / output interfaces, network interfaces, and memory.

[0132] Memory may include non-persistent storage in computer-readable media, such as random access memory (RAM) and / or non-volatile memory, such as read-only memory (ROM) or flash RAM. Memory is an example of computer-readable media.

[0133] Computer-readable media, including both permanent and non-permanent, removable and non-removable media, can store information using any method or technology. Information can be computer-readable instructions, data structures, program modules, or other data. Examples of computer storage media include, but are not limited to, phase-change memory (PRAM), static random access memory (SRAM), dynamic random access memory (DRAM), other types of random access memory (RAM), read-only memory (ROM), electrically erasable programmable read-only memory (EEPROM), flash memory or other memory technologies, and CD-ROM.

[0134] Digital multifunction optical disc (DVD) or other optical storage, magnetic cassette tape, magnetic tape, disk storage or other magnetic storage devices

[0135] Or any other non-transmission medium that can be used to store information that can be accessed by a computing device. As defined herein, computer-readable media does not include transient media, such as modulated data signals and carrier waves.

[0136] It should also be noted that the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus. Without further limitation, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes said element.

[0137] This application can be described in the general context of computer-executable instructions that are executed by a computer, such as program modules. Generally, program modules include routines, programs, objects, components, data structures, etc., that perform specific transactions or implement specific abstract data types. This application can also be practiced in distributed computing environments where transactions are performed by remote processing devices connected via a communication network. In distributed computing environments, program modules can reside in local and remote computer storage media, including storage devices.

[0138] The various embodiments in this specification are described in a progressive manner, with each embodiment focusing on its differences from other embodiments. Similar or identical parts between embodiments can be referred to interchangeably. For the systems disclosed in the embodiments, since they correspond to the methods disclosed in the embodiments, the descriptions are relatively simple; relevant parts can be referred to the method section.

[0139] This document uses specific examples to illustrate the principles and implementation methods of the present invention. The descriptions of the above embodiments are only for the purpose of helping to understand the method and core ideas of the present invention. Furthermore, those skilled in the art will recognize that, based on the ideas of the present invention, there will be changes in the specific implementation methods and application scope. Therefore, the content of this specification should not be construed as a limitation of the present invention.

Claims

1. A method for suppressing ferroresonance in an electromagnetic voltage transformer, characterized in that, Adding a Rogowski coil to an electromagnetic voltage transformer includes: Obtain the open delta zero-sequence voltage and three-phase excitation voltage of the electromagnetic voltage transformer; The three-phase excitation current of the electromagnetic voltage transformer is collected using the Rogowski coil, and the power frequency excitation impedance of each phase of the electromagnetic voltage transformer is calculated based on the three-phase excitation current and the three-phase excitation voltage. Determine whether the electromagnetic voltage transformer resonates based on the open delta zero-sequence voltage. If the electromagnetic voltage transformer resonates, the resonance type of the electromagnetic voltage transformer is determined based on the open delta zero-sequence voltage and the power frequency excitation impedance, specifically including: Calculate the frequency division and frequency doubling of the zero-sequence voltage of the open delta; When the power frequency excitation impedance of one or more phases is less than the power frequency excitation impedance threshold and the frequency division amount is greater than the voltage threshold, it is determined that the electromagnetic voltage transformer has undergone frequency division resonance. When the power frequency excitation impedance of one or more phases is less than the power frequency excitation impedance threshold and the frequency multiplication factor is greater than the voltage threshold, it is determined that the electromagnetic voltage transformer has power frequency resonance. When the power frequency excitation impedance of one or more phases is less than the power frequency excitation impedance threshold, and the frequency division is less than or equal to the voltage threshold, and the frequency multiplication is less than or equal to the voltage threshold, it is determined that the electromagnetic voltage transformer has undergone fundamental frequency resonance. When the power frequency excitation impedance of each phase is greater than or equal to the power frequency excitation impedance threshold, it is determined that the electromagnetic voltage transformer has experienced a single-phase grounding; the resonance type includes frequency division resonance, power frequency resonance, and fundamental frequency resonance; According to the resonance type, a harmonic suppression resistor is inserted into the open delta of the electromagnetic voltage transformer to eliminate the resonance; If the electromagnetic voltage transformer does not resonate, it is determined that the electromagnetic voltage transformer has experienced a single-phase grounding fault or a broken wire fault.

2. The method for suppressing ferroresonance in an electromagnetic voltage transformer according to claim 1, characterized in that, The step of determining whether the electromagnetic voltage transformer resonates based on the open delta zero-sequence voltage specifically includes: When the open delta zero-sequence voltage is in the first voltage range, it is determined that the electromagnetic voltage transformer is operating normally; When the open delta zero-sequence voltage is in the second voltage range, it is determined that the electromagnetic voltage transformer has a broken wire fault. When the open delta zero-sequence voltage is in the third voltage range, it is determined that the electromagnetic voltage transformer is resonating or experiencing a single-phase grounding.

3. The method for suppressing ferroresonance in an electromagnetic voltage transformer according to claim 1, characterized in that, The resistance value of the harmonic suppression resistor for: in, The value of the excitation impedance of the single-phase winding of the electromagnetic voltage transformer under the line voltage; K 13 The transformation ratio of the primary winding to the open delta winding of the electromagnetic voltage transformer.

4. The method for suppressing ferroresonance in an electromagnetic voltage transformer according to claim 1, characterized in that, The step of eliminating resonance by inserting a harmonic-suppressing resistor into the open delta of the electromagnetic voltage transformer according to the resonance type specifically includes: When the frequency division is less than or equal to the voltage threshold and the frequency harmonic is less than or equal to the voltage threshold, it is determined that the frequency division resonance and the fundamental frequency resonance are eliminated, and the open delta harmonic elimination resistor is removed. When the power frequency excitation impedance of any phase is less than the power frequency excitation impedance threshold, it is determined that the power frequency resonance has not been eliminated. The harmonic elimination resistor is kept in the engaged state until the power frequency resonance is eliminated, and then the open delta harmonic elimination resistor is deactivated.

5. A ferroresonance suppression system for an electromagnetic voltage transformer, characterized in that, Adding a Rogowski coil to an electromagnetic voltage transformer includes: The voltage acquisition module is used to acquire the open delta zero-sequence voltage and the three-phase excitation voltage of the electromagnetic voltage transformer. The current acquisition module is used to acquire the three-phase excitation current of the electromagnetic voltage transformer using the Rogowski coil, and to calculate the power frequency excitation impedance of each phase of the electromagnetic voltage transformer based on the three-phase excitation current and the three-phase excitation voltage. The resonance judgment module is used to determine whether the electromagnetic voltage transformer is resonating based on the open delta zero-sequence voltage. A resonance type determination module is used to determine the resonance type of the electromagnetic voltage transformer based on the open delta zero-sequence voltage and the power frequency excitation impedance if the electromagnetic voltage transformer resonates; the resonance type includes frequency division resonance, power frequency resonance, and fundamental frequency resonance; the resonance type determination module specifically includes: The frequency division and multiplication calculation unit is used to calculate the frequency division and multiplication of the open delta zero-sequence voltage. The frequency division resonance determination unit is used to determine that the electromagnetic voltage transformer has undergone frequency division resonance when the power frequency excitation impedance of one or more phases is less than the power frequency excitation impedance threshold and the frequency division amount is greater than the voltage threshold. The power frequency resonance determination unit is used to determine that the electromagnetic voltage transformer has power frequency resonance when the power frequency excitation impedance of one or more phases is less than the power frequency excitation impedance threshold and the frequency doubling is greater than the voltage threshold. The fundamental frequency resonance determination unit is used to determine that the electromagnetic voltage transformer has fundamental frequency resonance when the power frequency excitation impedance of one or more phases is less than the power frequency excitation impedance threshold, the frequency division is less than or equal to the voltage threshold, and the frequency doubling is less than or equal to the voltage threshold. A single-phase grounding determination unit is used to determine that the electromagnetic voltage transformer has experienced a single-phase grounding when the power frequency excitation impedance of each phase is greater than or equal to the power frequency excitation impedance threshold. A resonance cancellation module is used to eliminate resonance by inserting a resonance cancellation resistor into the open delta of the electromagnetic voltage transformer according to the resonance type. The normal operation or open circuit fault determination module is used to determine whether the electromagnetic voltage transformer has experienced a single-phase grounding fault or an open circuit fault if the electromagnetic voltage transformer does not resonate.

6. The electromagnetic voltage transformer ferroresonance suppression system according to claim 5, characterized in that, The resonance determination module specifically includes: The normal operation determination unit is used to determine that the electromagnetic voltage transformer is operating normally when the open delta zero-sequence voltage is in the first voltage range. The open-circuit fault detection unit is used to determine that the electromagnetic voltage transformer has experienced an open-circuit fault when the open delta zero-sequence voltage is in the second voltage range. The resonance generating unit is used to determine that the electromagnetic voltage transformer resonates when the open delta zero-sequence voltage is in the third voltage range.

7. An electronic device, characterized in that, The device includes a memory and a processor, the memory being used to store a computer program, and the processor running the computer program to cause the electronic device to perform the electromagnetic voltage transformer ferromagnetic resonance suppression method as described in any one of claims 1-4.

8. A computer-readable storage medium, characterized in that, It stores a computer program, which, when executed by a processor, implements the method for suppressing ferromagnetic resonance in an electromagnetic voltage transformer as described in any one of claims 1-4.

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