Voltage fluctuation on-line monitoring device for power system of thermal power plant and monitoring method thereof

Abstract

The application discloses an online voltage fluctuation monitoring device for a power system of a thermal power plant and a monitoring method thereof, and relates to the field of power monitoring of the thermal power plant. The method is based on the transmission characteristics of electric signals. The main monitor and the auxiliary monitor are arranged. When the voltage fluctuation signal occurs, the main monitor and the auxiliary monitor add time stamp labels synchronously when the signals are captured. Then, the distance difference between the signals and the main monitor and the auxiliary monitor is obtained according to the two time stamps. Then, the specific position of the voltage fluctuation is calculated according to the branch length and the signal propagation speed in the branch. Meanwhile, the characteristics of the signals are compared and analyzed. Then, the equipment causing the voltage fluctuation is determined according to the distribution positions of the electric appliances in the power grid distribution map. Thus, it is not necessary to independently monitor each equipment, and the monitoring cost and the deployment difficulty are reduced.

Description

Technical Field

[0001] This invention relates to the field of power monitoring systems for thermal power plants, and particularly to an online voltage fluctuation monitoring device and method for power systems in thermal power plants. Background Technology

[0002] Within a thermal power plant, there are numerous systems involved in power generation, primarily including boiler system equipment, turbine system equipment, electrical and control equipment, and auxiliary production equipment. These systems consume electricity during power generation. If any equipment malfunctions during operation, it can trigger a chain reaction, ultimately affecting the entire power generation operation and potentially leading to production accidents. Furthermore, abnormal voltage fluctuations during equipment operation can be caused by monitoring these fluctuations, allowing for a general assessment of the type of problem.

[0003] Existing technical solutions typically involve installing voltage monitoring modules on each device and then using an integrated cabinet for aggregated monitoring. This usually requires setting up an integrated cabinet for monitoring at each branch of the power equipment, and each integrated cabinet requires dedicated personnel for maintenance and inspection. This results in an overly large voltage fluctuation monitoring system, with excessively high costs for monitoring equipment and manpower. Therefore, this paper proposes an online voltage fluctuation monitoring device and monitoring method for thermal power plant power systems. Summary of the Invention

[0004] The purpose of this invention is to provide an online voltage fluctuation monitoring device and method for power systems in thermal power plants, so as to solve the problems mentioned in the background art.

[0005] To achieve the above objectives, the present invention provides the following technical solution: an online voltage fluctuation monitoring device and method for power systems in thermal power plants, comprising the following steps:

[0006] S1. Draw a power grid distribution map based on the voltage fluctuation monitoring range;

[0007] S2. Construct a voltage wave monitoring environment, including the main line main monitor and multiple branch line secondary monitors;

[0008] S3, the main and auxiliary monitors locate voltage fluctuations based on GPS clock;

[0009] S4. Determine the source of fluctuations based on the characteristics of voltage fluctuation signals.

[0010] Preferably, in step S1, the power system's line architecture is sorted out, with the power generation output end as the endpoint, and multiple branches are sorted out starting from boiler system equipment, steam turbine system equipment, electrical and control equipment, and auxiliary production equipment. Each electrical device in the branch line is identified, and the length of the entire feeder of the branch line and the main line is measured and counted with the electrical device as the node. Finally, the data is summarized to draw a fully identified power grid distribution map of the power system.

[0011] Preferably, in step S2, voltage fluctuation monitors are arranged according to the power grid distribution diagram drawn in step S1. A set of main monitors is set at the end of the main line, and a set of auxiliary monitors is set at the end of each of the multiple branches. The main monitors and auxiliary monitors adopt a three-level synchronization architecture of "monitor local clock + GPS / BeiDou dual-mode synchronization + monitoring center time synchronization" to ensure the consistency of the clocks of the two monitors and ensure that the clock deviation is less than 1 microsecond, thus avoiding time difference calculation errors. The monitors use high-frequency sampling to ensure that the start time of the fluctuation signal is captured and the time is accurately recorded.

[0012] Preferably, in step S2, signal blocking mechanisms are used to shield and block branch signals between multiple branches to prevent signal conduction between branches from causing interference. The signal blocking mechanism includes:

[0013] Shielded cables; double-shielded cables are used for all branch lines, with the outer shielding layer grounded at both ends and the inner shielding layer grounded at one end to isolate electromagnetic coupling signals between lines.

[0014] Isolation transformer; A small isolation transformer is installed near the bus node on each branch line to block transient fluctuation signals and zero-sequence current coupling signals that are directly transmitted between branches through the line;

[0015] EMI filter; A power EMI filter is installed at the front end of the branch monitor and at the connection port between the branch and the bus. The filter frequency range is preset to accurately filter out high-frequency fluctuation noise coupled between branches and retain the normal fluctuation signal of the branch itself.

[0016] Preferably, the specific implementation process of step S3 includes:

[0017] S31. Timing extraction and encapsulation of mainline signals

[0018] S311, the mainline monitor acquires voltage signals in real time. When it detects superimposed fluctuation signals, it automatically marks the complete time window from the start to the end of the signal. arrive Lasts for 200ms;

[0019] S312. Based on the preset signal propagation time of the farthest point of each branch line, the time segment in which the fluctuation signal of each branch line should appear on the main line is calculated in reverse. The formula is as follows:

[0020]

[0021] in Indicates dividing line Length, This indicates the propagation speed of voltage fluctuation signals;

[0022] If the dividing line The longest theoretical transmission time is Branch line for Then in the main line signal;

[0023] Cut + ~ + The fragment is encapsulated as a "signal fragment" "Candidate";

[0024] Cut + ~ + The fragment is encapsulated as a "signal fragment" "Candidate";

[0025] S313. Add metadata such as timestamps and line identifiers to each encapsulation segment for subsequent comparison and tracing.

[0026] S32. Compare and match with the branch monitor signal.

[0027] S321. Synchronously retrieve signals from all branch monitors within the corresponding time window, including... Monitor in ~ Signals over a period of time The monitor is ~ Signals within a time period;

[0028] S322, Encapsulate the "signal segment" of the main line. "candidate" and The monitor collects raw signals and performs feature comparison. If the matching degree is ≥90%, the segment is confirmed to originate from [the source]. Branch lines; similarly complete. Matching with other sub-lines, locking in all fluctuation sub-lines;

[0029] S323. Exclude non-fluctuating branches. If the matching degree between a candidate segment of a branch line extracted from the main line and the corresponding branch monitor signal is <90%, then the branch line is determined to be non-fluctuating and the segment is removed.

[0030] S33, Equipment positioning within the branch line

[0031] S331, For locked fluctuation lines ,extract Monitor signal timestamp Timestamps of segments corresponding to the main storyline Calculate the time difference ;

[0032] S332. Calculated using the speed and distance formula; the distance from the wave source to the branch monitor is:

[0033]

[0034] S333, combined with the power grid distribution map The device location identification information of the branch line is matched with the corresponding device unit to complete the final positioning.

[0035] Preferably, step S4 is based on step S3 to determine the branch line and the location, thereby accurately locating the specific location of the branch line where the voltage fluctuation occurs. Then, the voltage fluctuation characteristics of multiple electrical components at that location are compared and analyzed to finally determine the specific device where the voltage fluctuation occurs.

[0036] Preferably, the voltage fluctuation characteristics include frequency components, amplitude variation trends, and waveform inflection points. By performing feature analysis on each component in each group of equipment units, a feature database is established based on the voltage fluctuation characteristics caused by various faults and start-up / stop states that may occur in each component. A corresponding "feature set" identifier is set for each component according to the feature database, so that the component that ultimately causes voltage fluctuation can be determined by comparing the "feature set" after determining the coordinates of the equipment unit.

[0037] Preferably, both the main monitor and the secondary monitor are equipped with a three-level filtering architecture consisting of "preprocessing + core filtering + post-calibration", and the filtering scheme parameters are set in the same way to ensure that there is no deviation during comparison.

[0038] The preprocessing uses a hard RC low-pass filter;

[0039] The core filter adopts an adaptive FIR bandpass filter with a center frequency of 50Hz and a bandwidth of ±50Hz.

[0040] The subsequent calibration uses wavelet threshold denoising, where the wavelet is dB4 and the decomposition level is 3.

[0041] Preferably, when the main monitor processes superimposed fluctuation signals, it adds a timestamp when each fluctuation signal appears based on the GPS clock, and performs fluctuation signal stripping and decomposition based on the starting timestamp feature. Thus, when comparing the fluctuation signal features with the secondary monitors on the branch, it uses the timestamp to filter out non-target signals, and then compares them one by one to finally determine the matching fluctuation signals.

[0042] The voltage fluctuation online monitoring device for power systems in thermal power plants includes the monitor and the monitoring center. The monitor is an industrial-grade power quality monitor equipped with a GPS / BeiDou dual-mode synchronization module. The industrial-grade power quality monitor uses a frequency >50KHZ.

[0043] The monitoring center is an industrial-grade control host equipped with a core hardware filtering module and software filtering algorithm; it also provides computing power for the data processing of the monitors. The industrial-grade control host is a carrier of the power grid distribution map.

[0044] The technical effects and advantages of this invention are as follows:

[0045] 1. The online voltage fluctuation method used in the power system of this thermal power plant is based on the transmission characteristics of electrical signals; that is, the voltage fluctuation signal has the same transmission speed in the same conductor, and the voltage fluctuation signal is simultaneously propagated to both ends of the conductor from the point of occurrence. By deploying a main monitor and a secondary monitor, when a voltage fluctuation signal occurs, the signal is captured by the main monitor and the secondary monitor respectively when it is transmitted to both ends. At this time, the main monitor and the secondary monitor will add a timestamp tag when they capture the signal. Then, the distance difference between the signal and the main monitor and the secondary monitor is calculated based on the two timestamps. Then, the specific location of the voltage fluctuation is calculated based on the branch length and the signal propagation speed in the branch. Finally, the equipment that causes voltage fluctuation is determined according to the distribution location of each electrical appliance that causes voltage fluctuation in the power grid distribution diagram. Therefore, it is not necessary to monitor each device independently, reducing monitoring costs and deployment difficulty.

[0046] 2. The online voltage fluctuation method used in the power system of this thermal power plant involves the following steps: When the main monitor captures multiple superimposed signals, signal segments are cut based on the farthest distance the signal from each branch line propagates to the main monitor. This ensures that if a voltage fluctuation signal exists in that branch line, the cut signal segment will definitely contain that voltage signal. Then, the voltage fluctuation signals from each sub-monitor are acquired. By comparing and analyzing the frequency components, amplitude variation trends, and waveform inflection point characteristics of the signals, a matching degree threshold is designed. When the threshold is reached, it is judged as a valid comparison signal. At this time, the corresponding fluctuation samples can be effectively acquired when there are multiple voltage fluctuations, thereby realizing effective comparison samples in complex voltage fluctuation superposition environments.

[0047] 3. The online voltage fluctuation method used in the power system of this thermal power plant involves performing feature analysis on each component in each equipment unit. Based on the voltage fluctuation characteristics caused by various faults and start-up / shutdown states that may occur in each component, a feature database is established. According to the feature database, a corresponding "feature set" identifier is set for each component. After determining the coordinates of the equipment unit, the component causing the voltage fluctuation is determined by comparing the "feature set", thereby accurately understanding the faulty component.

[0048] 4. During signal acquisition, hardware shielding devices, including shielded cables, isolation transformers, and EMI filters, are installed on the branch lines to isolate signals between each branch line and prevent mutual interference. At the same time, the main and auxiliary monitors adopt high-frequency sampling and have a built-in three-stage filtering architecture of "preprocessing + core filtering + post-calibration". The filtering scheme parameters are set the same, which not only achieves effective filtering and eliminates messy voltage fluctuation signals, but also ensures that there is no deviation when the main and auxiliary monitors are compared. Attached Figure Description

[0049] Figure 1 This is a flowchart of the online voltage fluctuation monitoring method of the present invention;

[0050] Figure 2 This is a circuit topology diagram of the online voltage fluctuation monitoring method of the present invention. Detailed Implementation

[0051] 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.

[0052] Example 1: This embodiment of the invention provides, as follows Figures 1 to 2 The voltage fluctuation online monitoring device and monitoring method for the power system of a thermal power plant shown include the following steps:

[0053] S1. Draw a power grid distribution map based on the voltage fluctuation monitoring range;

[0054] S2. Construct a voltage wave monitoring environment, including the main line main monitor and multiple branch line secondary monitors;

[0055] S3, the main and auxiliary monitors locate voltage fluctuations based on GPS clock;

[0056] S4. Determine the source of fluctuations based on the characteristics of voltage fluctuation signals.

[0057] In step S1, the power system's line architecture is sorted out. Starting from the power generation output end, multiple branches are sorted out, with boiler system equipment, steam turbine system equipment, electrical and control equipment, and auxiliary production equipment as the starting points. Each electrical device in the branch line is identified. The length of the feeder of the branch line and the main line is measured and counted with the electrical device as the node. Finally, the data is summarized to draw a fully identified power grid distribution map of the power system.

[0058] In step S2, voltage fluctuation monitors are deployed according to the power grid distribution diagram drawn in step S1. A set of main monitors is set at the end of the main line, and a set of auxiliary monitors is set at the end of each of the multiple branches. The main and auxiliary monitors adopt a three-level synchronization architecture of "monitor local clock + GPS / BeiDou dual-mode synchronization + monitoring center time synchronization" to ensure the consistency of the clocks of the two monitors and ensure that the clock deviation is less than 1 microsecond, thus avoiding time difference calculation errors. The monitors use high-frequency sampling to ensure that the start time of the fluctuation signal is captured and the time is accurately recorded.

[0059] In step S2, signal blocking mechanisms are used to shield and block branch signals between multiple branches to prevent signal conduction and interference between branches. The signal blocking mechanisms include:

[0060] Shielded cables; double-shielded cables are used for all branch lines, with the outer shielding layer grounded at both ends and the inner shielding layer grounded at one end to isolate electromagnetic coupling signals between lines.

[0061] Isolation transformer; A small isolation transformer is installed near the bus node on each branch line to block transient fluctuation signals and zero-sequence current coupling signals that are directly transmitted between branches through the line;

[0062] EMI filter; A power EMI filter is installed at the front end of the branch monitor and at the connection port between the branch and the bus. The filter frequency range is preset to accurately filter out high-frequency fluctuation noise coupled between branches and retain the normal fluctuation signal of the branch itself.

[0063] The specific implementation process of step S3 includes:

[0064] S31. Timing extraction and encapsulation of mainline signals

[0065] S311, the mainline monitor acquires voltage signals in real time. When it detects superimposed fluctuation signals, it automatically marks the complete time window from the start to the end of the signal. arrive Lasts for 200ms;

[0066] S312. Based on the preset signal propagation time of the farthest point of each branch line, the time segment in which the fluctuation signal of each branch line should appear on the main line is calculated in reverse. The formula is as follows:

[0067]

[0068] in Indicates dividing line Length, This indicates the propagation speed of voltage fluctuation signals;

[0069] If the dividing line The longest theoretical transmission time is Branch line for Then in the main line signal;

[0070] Cut + ~ + The fragment is encapsulated as a "signal fragment" "Candidate";

[0071] Cut + ~ + The fragment is encapsulated as a "signal fragment" "Candidate";

[0072] S313. Add metadata such as timestamps and line identifiers to each encapsulation segment for subsequent comparison and tracing.

[0073] S32. Compare and match with the branch monitor signal.

[0074] S321. Synchronously retrieve signals from all branch monitors within the corresponding time window, including... The monitor is ~ Signals over a period of time The monitor is ~ Signals within a time period;

[0075] S322, Encapsulate the "signal segment" of the main line. "candidate" and The monitor collects raw signals and performs feature comparison. If the matching degree is ≥90%, the segment is confirmed to originate from [the source]. Branch lines; similarly complete. Matching with other sub-lines, locking in all fluctuation sub-lines;

[0076] S323. Exclude non-fluctuating branches. If the matching degree between a candidate segment of a branch line extracted from the main line and the corresponding branch monitor signal is <90%, then the branch line is determined to be non-fluctuating and the segment is removed.

[0077] S33, Equipment positioning within the branch line

[0078] S331, For locked fluctuation lines ,extract Monitor signal timestamp Timestamps of segments corresponding to the main storyline Calculate the time difference ;

[0079] S332. Calculated using the speed and distance formula; the distance from the wave source to the branch monitor is:

[0080]

[0081] S333, combined with the power grid distribution map The device location identification information of the branch line is matched with the corresponding device unit to complete the final positioning.

[0082] Step S4 determines the branch line and its location based on step S3, thereby accurately locating the specific location of the branch line where voltage fluctuations occur. Then, it compares and analyzes the voltage fluctuation characteristics of multiple electrical components at that location to finally determine the specific device where voltage fluctuations occur.

[0083] Voltage fluctuation characteristics include frequency components, amplitude variation trends, and waveform inflection points. By performing feature analysis on each component in each equipment unit, a feature database is established based on the voltage fluctuation characteristics caused by various faults and start-up / shutdown states that may occur in each component. A corresponding "feature set" identifier is set for each component according to the feature database, so that the component that ultimately causes voltage fluctuation can be determined by comparing the "feature set" after determining the coordinates of the equipment unit.

[0084] Both the main and secondary monitors are equipped with a three-stage filtering architecture consisting of "preprocessing + core filtering + post-calibration", and the filtering scheme parameters are set in the same way to ensure that there will be no deviation during comparison.

[0085] Preprocessing uses a hard RC low-pass filter;

[0086] The core filter uses an adaptive FIR bandpass filter with a center frequency of 50Hz and a bandwidth of ±50Hz.

[0087] The subsequent calibration uses wavelet threshold denoising, where the wavelet is dB4 and the decomposition level is 3.

[0088] When processing superimposed fluctuation signals, the main monitor adds a timestamp when each fluctuation signal appears based on the GPS clock. It then performs fluctuation signal stripping and decomposition based on the initial timestamp feature. When comparing the fluctuation signal features with the secondary monitors on the branch, it uses the timestamp to filter out non-target signals and then compares them one by one to finally determine the matching fluctuation signals.

[0089] Working principle: The online voltage fluctuation method used in the power system of this thermal power plant is based on the transmission characteristics of electrical signals; that is, the voltage fluctuation signal has the same transmission speed in the same conductor, and the voltage fluctuation signal is simultaneously transmitted to both ends of the conductor from the point of occurrence. A scheme design based on the theory of voltage fluctuation signal transmission time and cable length is proposed. By drawing a power grid distribution map of the entire voltage fluctuation monitoring range, and then setting monitors at the end nodes of each branch line and the bus node according to the power grid distribution map, the voltage fluctuation signal is captured by the monitors.

[0090] Meanwhile, the main and auxiliary monitors adopt a three-level synchronization architecture of "monitor local clock + GPS / BeiDou dual-mode synchronization + monitoring center time synchronization" to ensure the consistency of clocks at both ends. During the monitoring process, when a voltage fluctuation signal occurs, the signal is transmitted to both ends and captured by the main and auxiliary monitors respectively. At this time, the main and auxiliary monitors will add a timestamp tag synchronously when they capture the signal. Then, based on the two timestamps, the distance difference between the signal and the main and auxiliary monitors is calculated. Then, based on the branch length and the signal propagation speed in the branch, the specific location of the voltage fluctuation is calculated. Finally, based on the distribution location of each electrical appliance that may cause voltage fluctuations in the power grid distribution diagram, the device causing the voltage fluctuation is determined.

[0091] Furthermore, in the above process, when the main monitor captures multiple superimposed signals, it indicates that there are multi-point voltage fluctuations. At this time, the signal segment is cut based on the farthest distance that each branch signal propagates to the main monitor. This ensures that if there is a voltage fluctuation signal in that branch, the cut signal segment must contain that voltage signal. Then, the voltage fluctuation signals of each sub-monitor are acquired. By comparing and analyzing the frequency components, amplitude change trends, and waveform inflection point characteristics of the signals, and by designing a matching degree threshold, when the threshold is reached, it is judged as a valid comparison signal. At this time, the corresponding fluctuation samples can be effectively acquired when there are multi-point voltage fluctuations.

[0092] Furthermore, when the main monitor processes superimposed fluctuation signals, it adds a timestamp when each fluctuation signal appears based on the GPS clock, and performs fluctuation signal stripping and decomposition based on the starting timestamp feature. Thus, when comparing the fluctuation signal features with the secondary monitors on the branch, it uses the timestamp to filter out non-target signals, and then compares them one by one to finally determine the matching fluctuation signals.

[0093] Meanwhile, during signal acquisition, hardware shielding devices, including shielded cables, isolation transformers, and EMI filters, are installed on the branch lines to isolate signals between each branch line and prevent mutual interference. At the same time, the main and auxiliary monitors adopt high-frequency sampling and have a built-in three-stage filtering architecture of "preprocessing + core filtering + post-calibration". The filtering scheme parameters are set the same, which not only achieves effective filtering and eliminates messy voltage fluctuation signals, but also ensures that there is no deviation when the main and auxiliary monitors are compared.

[0094] Example 2: This example is based on an online voltage fluctuation monitoring device for power systems in thermal power plants, including a monitor and a monitoring center. The monitor is an industrial-grade power quality monitor equipped with a GPS / BeiDou dual-mode synchronization module. The industrial-grade power quality monitor uses a frequency >50KHZ.

[0095] The monitoring center is an industrial-grade control host equipped with core hardware filtering modules and software filtering algorithms; it also provides computing power for monitoring data processing and serves as a carrier for power grid distribution maps.

[0096] Working principle: This device is used to perform the monitoring method described in Example 1. By deploying monitors and a monitoring center, centralized control is achieved. Data interaction, signal comparison and clock synchronization control of the main and auxiliary monitors are realized through an industrial-grade control host. During signal processing and comparison, the industrial-grade control host provides the required computing power. At the same time, it provides a data encapsulation and storage environment for the power grid distribution map and the "feature set" of various components in the power grid distribution map.

[0097] More notably, if the actual power grid distribution system is too large in this solution, cloud servers can be deployed to provide more computing power for the local industrial-grade control host.

[0098] Finally, it should be noted that the above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art can still modify the technical solutions described in the foregoing embodiments or make equivalent substitutions for some of the technical features. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A method for online monitoring of voltage fluctuations in the power system of a thermal power plant, characterized in that, Includes the following steps: S1. Draw a power grid distribution map based on the voltage fluctuation monitoring range; S2. Construct a voltage wave monitoring environment, including the main line main monitor and multiple branch line secondary monitors; S3, the main and auxiliary monitors locate voltage fluctuations based on GPS clock; S4. Determine the source of fluctuations based on voltage fluctuation signal characteristics; In step S2, voltage fluctuation monitors are deployed according to the power grid distribution diagram drawn in step S1. A set of main monitors is set at the end of the main line, and a set of auxiliary monitors is set at the end of each of the multiple branches. The main and auxiliary monitors adopt a three-level synchronization architecture of "monitor local clock + GPS / BeiDou dual-mode synchronization + monitoring center time synchronization" to ensure the consistency of the clocks of the two monitors and ensure that the clock deviation is less than 1 microsecond, thus avoiding time difference calculation errors. The monitors use high-frequency sampling to ensure that the start time of the fluctuation signal is captured and the time is accurately recorded. The specific implementation process of step S3 includes: S31. Timing extraction and encapsulation of mainline signals S311, the mainline monitor acquires voltage signals in real time. When it detects superimposed fluctuation signals, it automatically marks the complete time window from the start to the end of the signal. arrive Lasts for 200ms; S312. Based on the preset signal propagation time of the farthest point of each branch line, the time segment in which the fluctuation signal of each branch line should appear on the main line is calculated in reverse. The formula is as follows: in Indicates dividing line Length, This indicates the propagation speed of voltage fluctuation signals; If the dividing line The longest theoretical transmission time is Branch line for Then in the main line signal; Cut + ~ + The fragment is encapsulated as a "signal fragment" "Candidate"; Cut + ~ + The fragment is encapsulated as a "signal fragment" "Candidate"; S313. Add metadata such as timestamps and line identifiers to each encapsulation segment for subsequent comparison and tracing. S32. Compare and match with the branch monitor signal. S321. Synchronously retrieve signals from all branch monitors within the corresponding time window, including... The monitor is ~ Signals over a period of time The monitor is ~ Signals within a time period; S322, Encapsulate the "signal segment" of the main line. "candidate" and The monitor collects raw signals and performs feature comparison. If the matching degree is ≥90%, the segment is confirmed to originate from [the source]. Branch lines; similarly complete. Matching with other sub-lines, locking in all fluctuation sub-lines; S323. Exclude non-fluctuating branches. If the matching degree between a candidate segment of a branch line extracted from the main line and the corresponding branch monitor signal is <90%, then the branch line is determined to be non-fluctuating and the segment is removed. S33, Equipment positioning within the branch line S331, For locked fluctuation lines ,extract Monitor signal timestamp Timestamps of segments corresponding to the main storyline Calculate the time difference ; S332. Calculated using the speed and distance formula; the distance from the wave source to the branch monitor is: S333, combined with the power grid distribution map The device location identification information of the branch line is matched with the corresponding device unit to complete the final positioning.

2. The online voltage fluctuation monitoring method for power systems in thermal power plants according to claim 1, characterized in that, In step S1, the power system's line architecture is sorted out. Starting from the power generation output end, multiple branches are sorted out, with boiler system equipment, steam turbine system equipment, electrical and control equipment, and auxiliary production equipment as the starting points. Each electrical device in the branch line is identified. The length of the feeder of the branch line and the main line is measured and counted with the electrical device as the node. Finally, the data is summarized to draw a fully identified power grid distribution map of the power system.

3. The online voltage fluctuation monitoring method for power systems in thermal power plants according to claim 1, characterized in that, In step S2, signal blocking mechanisms are used to shield and block branch signals between multiple branches to prevent signal interference between branches. The signal blocking mechanism includes: Shielded cables; double-shielded cables are used for all branch lines, with the outer shielding layer grounded at both ends and the inner shielding layer grounded at one end to isolate electromagnetic coupling signals between lines. Isolation transformer; A small isolation transformer is installed near the bus node on each branch line to block transient fluctuation signals and zero-sequence current coupling signals that are directly transmitted between branches through the line; EMI filter; A power EMI filter is installed at the front end of the branch monitor and at the connection port between the branch and the bus. The filter frequency range is preset to accurately filter out high-frequency fluctuation noise coupled between branches and retain the normal fluctuation signal of the branch itself.

4. The online voltage fluctuation monitoring method for power systems in thermal power plants according to claim 1, characterized in that, Step S4 is based on step S3 to determine the branch line and its location, thereby accurately locating the specific location of the branch line where voltage fluctuation occurs. Then, the voltage fluctuation characteristics of multiple electrical components at that location are compared and analyzed to finally determine the specific device where voltage fluctuation occurs.

5. The online voltage fluctuation monitoring method for power systems in thermal power plants according to claim 4, characterized in that, The voltage fluctuation characteristics include frequency components, amplitude variation trends, and waveform inflection points. By performing feature analysis on each component in each group of equipment units, a feature database is established based on the voltage fluctuation characteristics caused by various faults and start-up / shutdown states that may occur in each component. A corresponding "feature set" identifier is set for each component according to the feature database, so that the component that ultimately causes voltage fluctuation can be determined by comparing the "feature set" after determining the coordinates of the equipment unit.

6. The online voltage fluctuation monitoring method for power systems in thermal power plants according to claim 1, characterized in that, Both the main monitor and the auxiliary monitor are equipped with a three-stage filtering architecture consisting of "preprocessing + core filtering + post-calibration", and the filtering scheme parameters are set in the same way to ensure that there will be no deviation during comparison. The preprocessing uses a hard RC low-pass filter; The core filter adopts an adaptive FIR bandpass filter with a center frequency of 50Hz and a bandwidth of ±50Hz. The subsequent calibration uses wavelet threshold denoising, where the wavelet is dB4 and the decomposition level is 3.

7. The online voltage fluctuation monitoring method for power systems in thermal power plants according to claim 1, characterized in that, When processing superimposed fluctuation signals, the main monitor adds a timestamp when each fluctuation signal appears based on the GPS clock. It then performs fluctuation signal stripping and decomposition based on the starting timestamp feature. Thus, when comparing the fluctuation signal features with the secondary monitors on the branch, it uses the timestamp to filter out non-target signals and then compares them one by one to finally determine the matching fluctuation signals.

8. A voltage fluctuation online monitoring device for a thermal power plant power system, used to operate the voltage fluctuation online monitoring method for a thermal power plant power system according to any one of claims 1-7, characterized in that, Includes the monitor and the monitoring center. The monitor is an industrial-grade power quality monitor equipped with a GPS / BeiDou dual-mode synchronization module. The industrial-grade power quality monitor uses a frequency >50KHZ. The monitoring center is an industrial-grade control host equipped with a core hardware filtering module and software filtering algorithm; it also provides computing power for the data processing of the monitors. The industrial-grade control host is a carrier of the power grid distribution map.

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