Detection method of flexible direct current power transmission system

Abstract

The invention discloses a detection method of a flexible direct current power transmission system, and relates to the technical field of power control, comprising the following steps: acquiring sensor data in real time, and monitoring the change of power grid frequency; calculating power parameters of each node in the system based on the collected current and voltage data, performing real-time analysis on the power grid frequency, and calculating the frequency stability of the system; power abnormal conditions are identified, the abnormal conditions are predicted based on historical data, and early warning is generated; according to the real-time data and the prediction result, control parameters of the flexible direct-current power transmission system are adjusted; and generating an operation report, recording the operation state and the performance index of the system, and carrying out regular system inspection and calibration. According to the method, power prediction of the flexible direct-current power transmission system in the operation process is provided, the power in the next time period can be predicted, the danger of high power is predicted, power adjustment can be carried out in advance, and the safety of the model is improved.

Description

Technical Field

[0001] The present invention relates to the technical field of power control, and in particular to a detection method for a flexible direct current transmission system. Background Art

[0002] As a new generation of DC transmission technology, flexible DC transmission is similar to HVDC transmission in structure and is still composed of converter stations and DC transmission lines. The HVDC technology of voltage source converter is a new transmission technology based on voltage source converter, self-shutoff device and pulse width modulation technology. This transmission technology has the advantages of being able to supply power to passive networks, no commutation failure, no need for communication between converter stations and easy to form a multi-terminal DC system. The converter stations at both ends of the flexible DC transmission system use flexible DC transmission and are composed of converters, commutation transformer equipment, commutation reactor equipment, etc. The most critical core part is VSC, which is In the system composed of a rectifier bridge and a DC capacitor, taking into account the topology of its main circuit and the type of switching devices, sinusoidal pulse width modulation technology can be used. This technology compares the data of the modulated reference wave with the triangular carrier. When the latter data is relatively small, the lower bridge arm switch will be triggered to turn on and turn off the lower bridge arm. This is mainly because the floating value and phase can be intelligently adjusted using pulse width modulation technology. Therefore, the amplitude and phase of the fundamental frequency component of the VSC's AC output voltage can also be adjusted by pulse width. The flexible DC transmission system needs to regularly test its performance during operation to ensure the safety of circuit transportation.

[0003] The existing detection method of flexible DC transmission system usually finds problems during the detection process, and then solves and optimizes the problems, but cannot predict dangers in advance. Summary of the Invention

[0004] In order to solve the above technical problems, a detection method for a flexible direct current transmission system is provided. This technical solution solves the above problems.

[0005] In order to achieve the above objects, the technical solution adopted by the present invention is:

[0006] The detection method of the flexible direct current transmission system includes: S1: acquiring sensor data in real time and monitoring changes in the grid frequency; S2: calculating the power parameters of each node in the system based on the collected current and voltage data, performing real-time analysis of the grid frequency, and calculating the frequency stability of the system; S3: identifying power anomalies, predicting the anomalies based on historical data, and generating early warnings; S4: adjusting the control parameters of the flexible direct current transmission system based on real-time data and prediction results; S5: generating an operation report, recording the system operation status and performance indicators, and conducting regular system inspections and calibrations.

[0007] Preferably, S1 specifically includes:

[0008] Use a data collector to connect and configure the frequency sensor to obtain the data generated by the sensor in real time;

[0009] Set up monitoring programs and data collection tasks on the data acquisition equipment to regularly obtain data from the frequency sensor;

[0010] Set sampling frequency and data recording interval to monitor grid frequency changes in real time;

[0011] The frequency data collected in real time is transmitted to the central control center, and the data is transmitted instantly through the network connection.

[0012] Preferably, S2 specifically includes:

[0013] Calculate active and reactive power at each node using current and voltage data;

[0014] The active power calculation formula is:

[0015] [P=V·I·cos(θ)]

[0016] Where P is active power, V is voltage, I is current, and θ is the phase angle between voltage and current;

[0017] The reactive power calculation formula is:

[0018] [Q=V·I·sin(θ)]

[0019] Where, Q is reactive power, V is voltage, I is current, and θ is the phase angle between voltage and current;

[0020] Calculate the total complex power:

[0021] (S=P+jQ)

[0022] Where S is the total resumption rate, P is the active power, Q is the reactive power, and j is the imaginary unit;

[0023] Obtain the frequency data of the power grid in real time through the power grid frequency sensor;

[0024] Analyze the real-time changes and fluctuations of the grid frequency, and keep the grid frequency around 50Hz or 60Hz;

[0025] The frequency stability of the power grid is evaluated by using the real-time collected power grid frequency data and applying the frequency drift algorithm.

[0026] Preferably, using the real-time collected grid frequency data and applying the frequency drift algorithm to evaluate the frequency stability of the grid specifically includes:

[0027] Determine the standard frequency of the power grid;

[0028] For each sampling of frequency data, a frequency drift algorithm is applied to calculate the deviation between the actual frequency and the standard frequency;

[0029] The frequency drift algorithm formula is:

[0030]

[0031] Among them, J S is the real-time collected grid frequency, J B is the standard frequency of the power grid, J is the deviation between the actual frequency and the standard frequency;

[0032] The calculated frequency drift data is stored and analyzed;

[0033] The frequency stability of the power grid is evaluated based on the size of the J value. The larger the J value, the lower the frequency stability of the power grid.

[0034] Preferably, the S3 specifically includes:

[0035] Set the deviation threshold between the actual frequency and the standard frequency to determine whether the J value is within the threshold range. For a 50Hz system, the allowed frequency range is between 49.5 and 50.5Hz; for a 60Hz system, the allowed range is between 59.5 and 60.5Hz.

[0036] When the J value exceeds the threshold, the system automatically generates an early warning;

[0037] When the J value is within the normal range, abnormal situations are predicted based on historical data and real-time data;

[0038] Establish a regression model and train the model;

[0039] Use the trained model to predict power in the future time period;

[0040] Compare the predicted results with the actual observed values ​​to identify abnormal power conditions that are inconsistent with expectations. When there is a significant deviation between the predicted and actual values ​​and exceeds the set threshold, an early warning will be issued.

[0041] Preferably, a regression model is established and training the model specifically includes:

[0042] The power prediction regression model expression is:

[0043]

[0044] is the predicted power value, β0 is the intercept;

[0045] (β1,β2,β p ) is the coefficient of the model, which means that each feature (x, x2, x p ) on power, (x,x2,x p ) are the characteristic values ​​of the model input, which are the statistical characteristics, time characteristics and environmental factors of the historical power data;

[0046] Use the accuracy calculation formula to evaluate the performance of the model and tune the model;

[0047] The precision evaluation formula is:

[0048]

[0049] Where A is the precision, n is the number of predictions, and t is the total number of predictions.

[0050] Preferably, S4 specifically includes:

[0051] Setting optimization goals for adjusting control parameters, including maximizing transmission efficiency, minimizing voltage fluctuations, and minimizing energy;

[0052] Based on the model prediction and optimization objectives, a specific strategy for adjusting control parameters is developed using a PID controller, adjusting the operating mode of the power regulator and the parameter settings of the voltage controller;

[0053] According to the model prediction results, the control parameters of the flexible DC transmission system are actually adjusted.

[0054] 4. Preferably, based on the model prediction and optimization objectives, a specific strategy for adjusting the control parameters is formulated using a PID controller. Adjusting the operating mode of the power regulator and the parameter settings of the voltage controller include:

[0055] Set the steady-state values ​​of voltage, current and power;

[0056] Use sensors to obtain current actual values ​​in real time;

[0057] Compare the target value with the actual measured value and calculate the error;

[0058] The error calculation formula is:

[0059] t=t m -t h

[0060] Among them, t is the error value, t m is the target value, t h is the actual measured value;

[0061] Proportional control: The output is adjusted according to the size of the error. Proportional control produces a response by multiplying the proportional coefficient. The control output is proportional to the error itself. The output formula of the controller is:

[0062] [t p =K P ·t]

[0063] Among them, t p is the output value, t is the error value, K P is the proportional gain parameter;

[0064] Integral control: adjusts the output according to the accumulation of errors. The output formula is expressed as:

[0065] [t p =k i ·∫t,dt]

[0066] Among them, k i is the integral gain parameter, ∫t,dt is the integral of the error over time, t p is the output value;

[0067] Differential control: Differential control adjusts the output according to the rate of change of the error. Its output is expressed as:

[0068]

[0069] Among them, K d is the differential gain parameter, is the time derivative of the error, t p is the output value, t is the error value;

[0070] The final output of the PID controller is obtained by adding the outputs of the proportional, integral and differential functions. The output of the overall controller can be expressed as:

[0071]

[0072] Among them, K p , K i , K d are the proportional, integral and differential gain parameters, t p is the output value;

[0073] The output value calculated by the PID controller is used as the operating variable or regulating variable in the control system to adjust the control parameters of the flexible DC transmission system.

[0074] Preferably, S5 specifically includes:

[0075] Collect real-time data and adjust data;

[0076] Verify the collected data;

[0077] Store the processed data into the database;

[0078] Generate report templates, including report structure and content requirements;

[0079] Display the calculated performance indicators in the form of charts and tables;

[0080] Set time nodes for regular inspections;

[0081] Calibrate sensors and monitoring equipment in the system;

[0082] Submit the generated report;

[0083] Based on the analysis results in the report, suggestions and optimization measures for improving system performance are put forward, and the generated reports and related data are recorded and archived.

[0084] Preferably, setting the time nodes for regular inspections includes:

[0085] Conduct basic equipment operation status checks and data collection monthly;

[0086] A more in-depth inspection and assessment is conducted every quarter, including analysis of system performance indicators, inspection of equipment status, and adjustment and calibration of key parameters.

[0087] Compared with the prior art, the present invention has the following beneficial effects:

[0088] The present invention proposes a power prediction for a flexible direct current transmission system during operation, which can predict the power in the next time period, thereby foreseeing the danger of high power, enabling power adjustment in advance, and improving the safety of the model. BRIEF DESCRIPTION OF THE DRAWINGS

[0089] Figure 1 It is a process framework diagram of the present invention. DETAILED DESCRIPTION

[0090] The following description is intended to disclose the present invention so that those skilled in the art can implement the present invention. The preferred embodiments described below are merely examples, and those skilled in the art may conceive of other obvious variations.

[0091] Reference Figure 1As shown, the detection method of the flexible direct current transmission system includes: acquiring sensor data in real time to monitor changes in grid frequency; calculating the power parameters of each node in the system based on the collected current and voltage data, performing real-time analysis of the grid frequency, and calculating the frequency stability of the system; identifying power anomalies, predicting the anomalies based on historical data, and generating early warnings; adjusting the control parameters of the flexible direct current transmission system based on real-time data and prediction results; generating an operation report to record the system operation status and performance indicators, and conducting regular system inspections and calibrations.

[0092] The use process of the present invention is as follows: S1: acquiring sensor data in real time and monitoring changes in the power grid frequency;

[0093] S2: Based on the collected current and voltage data, the power parameters of each node in the system are calculated, the grid frequency is analyzed in real time, and the frequency stability of the system is calculated;

[0094] S3: Identify power anomalies, predict anomalies based on historical data, and generate warnings;

[0095] S4: Adjust the control parameters of the HVDC Flexible system based on real-time data and prediction results;

[0096] S5: Generate operation reports, record system operation status and performance indicators, and perform regular system inspections and calibrations.

[0097] Furthermore, S1 specifically includes:

[0098] Use a data collector to connect and configure the frequency sensor to obtain the data generated by the sensor in real time;

[0099] Set up monitoring programs and data collection tasks on the data acquisition equipment to regularly obtain data from the frequency sensor;

[0100] Set sampling frequency and data recording interval to monitor grid frequency changes in real time;

[0101] The frequency data collected in real time is transmitted to the central control center, and the data is transmitted instantly through the network connection.

[0102] Furthermore, S2 specifically includes:

[0103] Calculate active and reactive power at each node using current and voltage data;

[0104] The active power calculation formula is:

[0105] [P=V·I·cos(θ)]

[0106] Where P is active power, V is voltage, I is current, and θ is the phase angle between voltage and current;

[0107] The reactive power calculation formula is:

[0108] [Q=V·I·sin(θ)]

[0109] Where Q is the active power, V is the voltage, I is the current, and θ is the phase angle between the voltage and current. Calculate the total complex power:

[0110] (S=P+jQ)

[0111] Where S is the total resumption rate, P is the active power, Q is the reactive power, and j is the imaginary unit;

[0112] Obtain the frequency data of the power grid in real time through the power grid frequency sensor;

[0113] Analyze the real-time changes and fluctuations of the grid frequency, and keep the grid frequency around 50Hz or 60Hz;

[0114] The frequency stability of the power grid is evaluated by using the real-time collected power grid frequency data and applying the frequency drift algorithm.

[0115] Furthermore, without using the real-time collected grid frequency data, the frequency drift algorithm is applied to evaluate the frequency stability of the grid, specifically including:

[0116] Determine the standard frequency of the power grid;

[0117] For each sampling of frequency data, a frequency drift algorithm is applied to calculate the deviation between the actual frequency and the standard frequency;

[0118] The frequency drift algorithm formula is:

[0119]

[0120] Among them, J S is the real-time collected grid frequency, J B is the standard frequency of the power grid, J is the deviation between the actual frequency and the standard frequency;

[0121] The calculated frequency drift data is stored and analyzed;

[0122] The frequency stability of the power grid is evaluated based on the size of the J value. The larger the J value, the lower the frequency stability of the power grid.

[0123] Furthermore, the S3 specifically includes:

[0124] Set the deviation threshold between the actual frequency and the standard frequency to determine whether the J value is within the threshold range. For a 50Hz system, the allowed frequency range is between 49.5 and 50.5Hz; for a 60Hz system, the allowed range is between 59.5 and 60.5Hz.

[0125] When the J value exceeds the threshold, the system automatically generates an early warning;

[0126] When the J value is within the normal range, abnormal situations are predicted based on historical data and real-time data;

[0127] Establish a regression model and train the model;

[0128] Use the trained model to predict power in the future time period;

[0129] Compare the predicted results with the actual observed values ​​to identify abnormal power conditions that are inconsistent with expectations. When there is a significant deviation between the predicted and actual values ​​and exceeds the set threshold, an early warning will be issued.

[0130] Furthermore, a regression model is established and the training of the model specifically includes:

[0131] The power prediction regression model expression is:

[0132]

[0133] is the predicted power value, β0 is the intercept;

[0134] (β1,β2,β p ) is the coefficient of the model, which means that each feature (x, x2, x p ) on power, (x,x2,x p ) are the characteristic values ​​of the model input, which are the statistical characteristics, time characteristics and environmental factors of the historical power data;

[0135] Use the accuracy calculation formula to evaluate the performance of the model and tune the model;

[0136] The precision evaluation formula is:

[0137]

[0138] Where A is the precision, n is the number of predictions, and t is the total number of predictions.

[0139] Furthermore, the S4 specifically includes:

[0140] Setting optimization goals for adjusting control parameters, including maximizing transmission efficiency, minimizing voltage fluctuations, and minimizing energy;

[0141] Based on the model prediction and optimization objectives, a specific strategy for adjusting control parameters is developed using a PID controller, adjusting the operating mode of the power regulator and the parameter settings of the voltage controller;

[0142] According to the model prediction results, the control parameters of the flexible DC transmission system are actually adjusted.

[0143] 5. Furthermore, based on the model prediction and optimization objectives, a specific strategy for adjusting the control parameters is developed using the PID controller. The operating mode of the power regulator and the parameter settings of the voltage controller are adjusted, including:

[0144] Set the steady-state values ​​of voltage, current and power;

[0145] Use sensors to obtain current actual values ​​in real time;

[0146] Compare the target value with the actual measured value and calculate the error;

[0147] The error calculation formula is:

[0148] t=t m -t h

[0149] Among them, t is the error value, t m is the target value, t h is the actual measured value;

[0150] Proportional control: The output is adjusted according to the size of the error. Proportional control produces a response by multiplying the proportional coefficient. The control output is proportional to the error itself. The output formula of the controller is:

[0151]

[0152] Among them, t p is the output value, t is the error value, K P is the proportional gain parameter;

[0153] Integral control: adjusts the output according to the accumulation of errors. The output formula is expressed as:

[0154] [t p =k i ·∫t,dt]

[0155] Among them, k i is the integral gain parameter, ∫t,dt is the integral of the error over time, t p is the output value;

[0156] Differential control: Differential control adjusts the output according to the rate of change of the error. Its output is expressed as:

[0157]

[0158] Among them, K d is the differential gain parameter, is the time derivative of the error, t p is the output value, t is the error value;

[0159] The final output of the PID controller is obtained by adding the outputs of the proportional, integral and differential functions. The output of the overall controller can be expressed as:

[0160]

[0161] Among them, K p , K i , K d are the proportional, integral and differential gain parameters, t p is the output value;

[0162] The output value calculated by the PID controller is used as the operating variable or regulating variable in the control system to adjust the control parameters of the flexible DC transmission system.

[0163] Furthermore, S5 specifically includes:

[0164] Collect real-time data and adjust data to generate reports;

[0165] Verify the collected data;

[0166] Store the processed data into the database;

[0167] Generate report templates, including report structure and content requirements;

[0168] Display the calculated performance indicators in the form of charts and tables;

[0169] Set time nodes for regular inspections;

[0170] Calibrate sensors and monitoring equipment in the system;

[0171] Submit the generated report;

[0172] Based on the analysis results in the report, suggestions and optimization measures for improving system performance are put forward, and the generated reports and related data are recorded and archived.

[0173] Furthermore, the time nodes for setting regular inspections include:

[0174] Conduct basic equipment operation status checks and data collection monthly;

[0175] A more in-depth inspection and assessment is conducted every quarter, including analysis of system performance indicators, inspection of equipment status, and adjustment and calibration of key parameters.

[0176] In summary, the advantages of the present invention are that it can predict the power in the next time period, thereby foreseeing the danger of high power, adjusting the power in advance, and improving the safety of the model.

[0177] The basic principles, main features, and advantages of the present invention are shown and described above. Those skilled in the art should understand that the present invention is not limited to the above embodiments. The above embodiments and descriptions merely illustrate the principles of the present invention. Various changes and modifications are possible without departing from the spirit and scope of the present invention. These changes and modifications fall within the scope of the invention as claimed.

Claims

1. A detection method for a flexible direct current transmission system, characterized in that: Detection methods include: S1: Acquire sensor data in real time and monitor changes in grid frequency; S2: Based on the collected current and voltage data, the power parameters of each node in the system are calculated, the grid frequency is analyzed in real time, and the frequency stability of the system is calculated; S3: Identify power anomalies, predict anomalies based on historical data, and generate warnings; S4: Adjust the control parameters of the flexible DC transmission system according to the real-time data and prediction results; S5: Generate operation reports, record system operation status and performance indicators, and perform regular system inspections and calibrations.

2. The detection method of the flexible direct current transmission system according to claim 1, characterized in that: The S1 specifically includes: Use the data collector to connect and configure the frequency sensor to obtain the data generated by the sensor in real time; Set up monitoring programs and data collection tasks on the data collection equipment to regularly obtain data from the frequency sensor; Set sampling frequency and data recording interval to monitor grid frequency changes in real time; The frequency data collected in real time is transmitted to the central control center, and the data is transmitted instantly through the network connection.

3. The detection method of the flexible DC transmission system according to claim 1, characterized in that: The S2 specifically includes: Use current and voltage data to calculate active and reactive power at each node; The active power calculation formula is: [P=V·I·cos(θ)] Where P is active power, V is voltage, I is current, and θ is the phase angle between voltage and current; The reactive power calculation formula is: [Q=V·I·sin(θ)] Where Q is reactive power, V is voltage, I is current, and θ is the phase angle between voltage and current; Compute the total complex power: (S=P+jQ), Among them, S is the total resumption rate, P is the active power, Q is the reactive power, and j is the imaginary unit; Obtain the frequency data of the power grid in real time through the power grid frequency sensor; Analyze the real-time changes of the grid frequency and keep the grid frequency around 50Hz or 60Hz; The frequency stability of the power grid is evaluated by using the real-time collected power grid frequency data and applying the frequency drift algorithm.

4. The detection method of the flexible DC transmission system according to claim 3, characterized in that: Using the real-time collected grid frequency data and applying the frequency drift algorithm, the frequency stability of the grid is evaluated, including: Determine the standard frequency of the power grid; For each sampled frequency data, a frequency drift algorithm is applied to calculate the deviation between the actual frequency and the standard frequency; The frequency drift algorithm formula is: Among them, J S is the real-time collected grid frequency, J B is the standard frequency of the power grid, J is the power grid deviation evaluation rate; The calculated power grid deviation rating is stored and analyzed; The frequency stability of the power grid is evaluated based on the size of the J value. The larger the J value, the lower the frequency stability of the power grid.

5. The detection method of the flexible DC transmission system according to claim 1, characterized in that: The S3 specifically includes: Set the deviation threshold between the actual frequency and the standard frequency to determine whether the J value is within the threshold range. For a 50Hz system, the allowable deviation threshold range is between 49.5 and 50.5Hz. For a 60Hz system, the allowable deviation threshold range is between 59.5 and 60.5Hz. When the J value exceeds the threshold, the system automatically generates an early warning; When the J value is within the normal range, abnormal situations are predicted based on historical data and real-time data; Establish a regression model and train the model; Use the trained model to predict power in future time periods; Compare the predicted results with the actual observed values ​​to identify abnormal power conditions that are inconsistent with expectations. When the difference between the predicted value and the actual value exceeds the set threshold, an early warning is issued.

6. The detection method of the flexible DC transmission system according to claim 5, characterized in that: Establish a regression model and train the model including: The power prediction regression model expression is: is the predicted power value, β0 is the intercept; (β1,β2,β p ) are the coefficients of the model, (x,x2,x p ) is an influencing factor.

7. The detection method of a flexible DC transmission system according to claim 1, characterized in that: The S4 specifically includes: Setting optimization goals for adjusting control parameters, including maximizing transmission efficiency, minimizing voltage fluctuations, and minimizing energy; According to the model prediction and optimization objectives, a specific strategy for adjusting the control parameters is developed using the PID controller, adjusting the working mode of the power regulator and the parameter settings of the voltage controller; According to the model prediction results, the control parameters of the flexible DC transmission system are actually adjusted.

8. The detection method of the flexible DC transmission system according to claim 7, characterized in that: According to the model prediction and optimization objectives, a specific strategy for adjusting the control parameters is formulated using the PID controller. The working mode of the power regulator and the parameter settings of the voltage controller are adjusted, including: Set steady-state values ​​for voltage, current, and power; Use sensors to obtain current actual values ​​in real time; Compare the target value with the actual measured value and calculate the error; The error calculation formula is: t=t m -t h Among them, t is the error value, t m is the target value, t h is the actual measured value; Proportional control: adjust the output according to the size of the error. Proportional control produces a response by multiplying the proportional coefficient. The control output is proportional to the error itself. The output formula of the controller is: Among them, t p is the output value, t is the error value, K P is the proportional gain parameter; Integral control: adjust the output according to the accumulation of errors. The output formula is: [t p =k i ·∫t,dt] Among them, k i is the integral gain parameter, ∫t,dt is the integral of the error over time, t p is the output value; Differential control: Differential control adjusts the output according to the rate of change of the error. The output is expressed as: Among them, K d is the differential gain parameter, is the time derivative of the error, t p is the output value, t is the error value; The outputs of the proportional, integral and differential are added together to get the final output of the PID controller. The output of the overall controller can be expressed as: Among them, K p , K i , K d are proportional, integral and differential gain parameters respectively, t p is the output value; The output value calculated by the PID controller is used as the operating variable or regulating variable in the control system to adjust the control parameters of the flexible DC transmission system.

9. The detection method of a flexible DC transmission system according to claim 1, characterized in that: The S5 specifically includes: Collect real-time data and adjust data, and generate reports; Based on the analysis results in the report, put forward suggestions and optimization measures to improve system performance, record and archive the generated reports and related data.

10. The detection method of the flexible direct current transmission system according to claim 9, characterized in that: The time nodes for setting regular inspections include: Conduct basic equipment operation status checks and data collection on a monthly basis; A more in-depth inspection and assessment is performed every quarter, including analysis of the system's performance indicators, inspection of equipment status, and adjustment and calibration of key parameters.

Images