Method for positioning power quality disturbance source of power distribution network containing distributed power supply

Abstract

The invention relates to the technical field of intelligent management of a power distribution network, in particular to a method for positioning a power quality disturbance source of a power distribution network containing a distributed power supply, which comprises the following steps of: S1, setting monitoring points: setting monitoring equipment on each line of the power distribution network according to power input and output data of the power distribution network; s2, dividing a disturbance source: obtaining previous power distribution network data, analyzing the previous power distribution network data, and confirming the type of the disturbance source; s3, constructing a calculation model: constructing a disturbance source signal model, a normal voltage model and a disturbance-normal comparison model according to the acquired disturbance source type; according to the positioning method designed by the invention, by analyzing the comparison trend of the peak value and the peak valley value of the voltage waveform when the normal voltage and the disturbance source are generated, rapid positioning of the disturbance source in the power distribution network is realized, the positioning speed of the disturbance source is greatly improved, so that an electric power worker can timely obtain the problem of disturbance of the power distribution network, and the working efficiency of the power distribution network is improved. And the problem of unstable power supply of the power distribution network caused by untimely processing is avoided.

Description

Technical Field

[0001] The present invention relates to the technical field of intelligent management of distribution networks, and particularly to a method for locating power quality disturbance sources in a distribution network with distributed power sources. Background Art

[0002] A distribution network refers to a power network that receives electric energy from a transmission network or a regional power plant and distributes it locally through distribution facilities or step by step according to voltage levels to various users. A distribution network disturbance source refers to the source that causes power quality problems in the distribution network. These disturbances may be caused by various factors, including but not limited to transformer energization, short - circuit faults, induction motor starting, and the interaction between distributed power sources and constant - power loads in the distribution network. In order to accurately locate the disturbance sources in the distribution network and master the distribution of the voltage sag area in the distribution network, various methods have been proposed in the prior art to achieve accurate location of the disturbance sources.

[0003] For example, a method for locating power quality disturbance sources in a distribution network with distributed power sources, with the application number CN201810091638.9 and the publication date of June 26, 2018, locates the disturbance sources by using the genetic algorithm to solve the position of the power quality disturbance sources with distributed power sources based on the disturbance direction monitored by the power quality monitor. The present invention considers the influence caused by distributed power sources during the operation of the distribution network. Considering the monitoring error of the power quality monitor, the genetic algorithm is used to obtain the optimal position of the power quality disturbance sources that conforms to the monitoring state, improving the fault tolerance rate and accuracy of the power quality disturbance source location, and solving the problems of large error and low accuracy in the existing disturbance source location methods.

[0004] Currently, most of the methods for locating distribution network disturbance sources in the market detect the disturbance sources by calculating voltage, current, and power. However, this process has a large amount of calculation and is time - consuming, resulting in the detection of the disturbance source only after a period of time after the disturbance source appears, and preventing power workers from promptly dealing with the generated disturbance source, leading to unstable power supply in the distribution network. Therefore, it is urgent to design a method for locating power quality disturbance sources in a distribution network with distributed power sources to solve the above problems. Summary of the Invention

[0005] The purpose of the present invention is to provide a method for locating power quality disturbance sources in a distribution network with distributed power sources to solve the above - mentioned deficiencies in the prior art.

[0006] To achieve the above purpose, the present invention provides the following technical solutions: A method for locating power quality disturbance sources in a distribution network with distributed power sources, comprising the following steps: Step S1. Set monitoring points: According to the power input and output data of the distribution network, set monitoring devices on each line of the distribution network. The monitoring device is selected as a power quality monitor, and the monitoring device is set at the power input point, transfer node, and power output point on each line of the distribution network; Step S2. Divide the disturbance sources: Obtain the past distribution network data, analyze the past distribution network data, and confirm the types of disturbance sources. The types of disturbance sources are as follows: (1) Voltage sag, (2) Voltage swell, (3) Voltage interruption, (4) Impulse interference, (5) Oscillation, (6) Harmonics; Step S3. Build a calculation model: Build a disturbance source signal model, a normal voltage model, and a disturbance-normal comparison model based on the types of disturbance sources obtained above. The disturbance source signal model is built according to the waveform formulas of various types of disturbance sources, and the waveform formulas of various types of disturbance sources are as follows: Voltage sag: Where, is the angular frequency, is a parameter, , is the voltage sag time point; Voltage swell: Where, is the angular frequency, is a parameter, , is the voltage sag time point; Voltage interruption: Where, is the angular frequency, is a parameter, , is the voltage sag time point; Impulse interference: Where, is the angular frequency, is a parameter, , is the voltage sag time point; Oscillation: Where, is the angular frequency, a, c, and d are all parameters, is the time, is the period Harmonics: Where, is the angular frequency, , is the harmonic time point, A is the normalized amplitude, is the harmonic phase angle; The normal voltage model is constructed based on the normal voltage waveform formula, and the normal voltage waveform formula is as follows: Where, is the angular frequency, is the time, The disturbance-normal comparison model is constructed through the waveform comparison algorithm and the disturbance source location algorithm, and the calculation steps of the disturbance-normal comparison model are as follows: S1-1. Filter the voltage waveform signals output by the normal voltage model and the disturbance source signal model to remove noise and interference signals; S1-2. Normalize the data of the filtered voltage waveform signals to ensure that the amplitude and phase differences between the two groups of data are small; S1-3. Sample the processed voltage waveform signal data to obtain the peak and valley data of the voltage waveform at the same time point; S1-4. Compare the magnitudes of the peak and valley data of the two groups of voltage waveforms, confirm the magnitude trend between the peak and valley data of the two groups of voltage waveforms, and initially determine the disturbance direction according to the trend relationship. If the peak and valley of the voltage waveform of the normal voltage model are larger than those of the disturbance source signal model, and the trend relationship will always increase, it indicates that there is a disturbance upstream, and the disturbance source is determined to be a disturbance type that absorbs energy. On the contrary, if the peak and valley of the voltage waveform of the normal voltage model are smaller than those of the disturbance source signal model, and the trend relationship will always decrease, it indicates that there is a disturbance downstream, and the disturbance source is determined to be a disturbance type that injects energy. The disturbance source location algorithm selects the multi-measurement point location algorithm, and the specific steps are as follows: S2-1. Construct the coverage matrix A and the direction measure column vector B. The coverage matrix is as follows: Where, L is the number of distribution network branches; M is the number of monitoring points, The direction measure column vector B is as follows: Where, is the direction measure value at the monitoring point n, and is specifically obtained by inputting the disturbance power and disturbance energy into the membership function; S2-2. Numerical calculation. If the line is located in the downstream area of the nth monitoring point, then let , if the line is located in the upstream area of the jth monitoring point, then let . Multiply the coverage matrix A by the disturbance direction measure column vector B to obtain the synthetic measure column vector C. C is a 1×L matrix, and the elements in the matrix C are the reliability values of the corresponding branches where there may be a disturbance source. The larger the reliability value, the greater the reliability that there is a disturbance source on this line.

[0007] Step S4. Obtain monitoring point data: Acquire the data collected at each monitoring point through monitoring devices, and classify and summarize the data. This process classifies the data collected at the monitoring points according to the differences in the power transmission lines of the distribution network and the types of distributed power sources, and performs secondary classification and induction processing through the power supply objects of the distribution network. Step S5. Solve the data: Input the obtained monitoring point data into the normal voltage model for calculation. If the calculation result conforms to the normal voltage model, directly output the result. If the calculation result does not conform to the normal voltage model, input the monitoring point data into the disturbance source signal model for calculation to determine the type of disturbance source, and then input it into the disturbance-normal comparison model for waveform comparison. Locate the disturbance direction according to the comparison result, and the solved result will be displayed through visualization technology.

[0008] In the above technical solution, a method for locating power quality disturbance sources in a distribution network with distributed power sources provided by the present invention has the following beneficial effects: (1) The positioning method designed by the present invention analyzes the comparison trends of the peak values and peak-to-valley sizes of the voltage waveforms during normal voltage and when the disturbance source occurs, realizing the rapid positioning of the disturbance source in the distribution network, greatly improving the speed of disturbance source positioning, enabling power workers to promptly obtain the problems of disturbances in the distribution network, and avoiding the problem of unstable power supply in the distribution network due to untimely handling.

[0009] (2) The positioning method designed by the present invention can also calculate the disturbance source a second time through the disturbance source positioning algorithm, and can obtain detailed disturbance source data on the distribution network, facilitating power workers to find the cause of the disturbance source for maintenance.

[0010] (3) The present invention can quickly judge and identify the disturbance source, improve the rapidity of disturbance direction judgment, and can also obtain the type of disturbance source through calculation, facilitating power workers to quickly select maintenance tools to adjust the distribution network during maintenance. BRIEF DESCRIPTION OF THE DRAWINGS

[0011] In order to more clearly illustrate the technical solutions in the embodiments of the present application or the prior art, the following will briefly introduce the drawings required for use in the embodiments. Obviously, the drawings described below are only some embodiments recorded in the present invention, and those of ordinary skill in the art can also obtain other drawings based on these drawings.

[0012] Figure 1 It is a flowchart of the method provided by an embodiment of a method for locating power quality disturbance sources in a distribution network with distributed power sources of the present invention.

[0013] Figure 2 It is a flowchart of the calculation steps of the disturbance-normal comparison model provided by an embodiment of a method for locating power quality disturbance sources in a distribution network with distributed power sources of the present invention. Detailed implementation mode

[0014] In order to enable those skilled in the art to better understand the technical solution of the present invention, the present invention will be further described in detail below with reference to the accompanying drawings.

[0015] As Figure 1-2 shown, a method for locating power quality disturbance sources in a distribution network with distributed power sources provided by an embodiment of the present invention includes the following steps: Step S1. Set monitoring points: According to the power input and output data of the distribution network, monitoring devices are set on each line of the distribution network. The monitoring devices are selected as power quality monitors, and the monitoring devices are set at the power input points, transfer nodes, and power output points on each line of the distribution network; Step S2. Divide disturbance sources: Obtain the past distribution network data, analyze the past distribution network data, and confirm the types of disturbance sources. The types of disturbance sources are as follows: (1) Voltage sag, (2) Voltage swell, (3) Voltage interruption, (4) Impulse interference, (5) Oscillation, (6) Harmonics; Step S3. Build a calculation model: Build a disturbance source signal model, a normal voltage model, and a disturbance-normal comparison model according to the types of disturbance sources obtained above. The disturbance source signal model is built based on the waveform formulas of various types of disturbance sources, and the waveform formulas of various types of disturbance sources are specifically as follows: Voltage sag: Wherein, is the angular frequency, is a parameter, , is the voltage sag time point; Voltage swell: Wherein, is the angular frequency, is a parameter, , is the voltage sag time point; Voltage interruption: Wherein, is the angular frequency, is a parameter, , is the voltage sag time point; Impulse interference: Wherein, is the angular frequency, is a parameter, , is the voltage sag time point; Oscillation: wherein is the angular frequency, and a, c, and d are all parameters, is time, is the period Harmonic: wherein is the angular frequency, , is the harmonic time point, A is the normalized amplitude, is the harmonic phase angle; The normal voltage model is constructed based on the normal voltage waveform formula, and the normal voltage waveform formula is as follows: wherein is the angular frequency, is time, The disturbance-normal comparison model is constructed through the waveform comparison algorithm and the disturbance source location algorithm, and the calculation steps of the disturbance-normal comparison model are as follows: S1-1. Filter the voltage waveform signals output by the normal voltage model and the disturbance source signal model to remove noise and interference signals; S1-2. Normalize the filtered voltage waveform signal data to ensure that the amplitude and phase differences between the two groups of data are small; S1-3. Sample the processed voltage waveform signal data to obtain the peak and valley data of the voltage waveform at the same time point; S1-4. Compare the magnitudes of the peak and valley data of the two groups of voltage waveforms, confirm the magnitude trend between the peak and valley data of the two groups of voltage waveforms, and preliminarily determine the disturbance direction according to the trend relationship. If the peak and valley of the voltage waveform of the normal voltage model are larger than those of the disturbance source signal model, and the trend relationship keeps increasing, it indicates that there is a disturbance upstream, and the disturbance source is determined to be the disturbance type that absorbs energy. On the contrary, if the peak and valley of the voltage waveform of the normal voltage model are smaller than those of the disturbance source signal model, and the trend relationship keeps decreasing, it indicates that there is a disturbance downstream, and the disturbance source is determined to be the disturbance type that injects energy. The disturbance source location algorithm selects the multi-measurement point location algorithm, and the specific steps are as follows: S2-1. Construct the coverage matrix A and the direction measure column vector B. The coverage matrix is as follows: wherein, L is the number of distribution network branches; M is the number of monitoring points, The direction measure column vector B is as follows: wherein is the direction measure value at the monitoring point n, and it is specifically obtained by inputting the disturbance power and disturbance energy into the membership function. It should be noted that the membership function is as follows: Among them, h is the ratio of the absolute value of the initial and final values of the disturbance energy to the absolute value of the peak value of the disturbance energy; S2-2. Numerical calculation. If the line is located in the downstream area of the nth monitoring point, then let , if the line is located in the upstream area of the jth monitoring point, then let . Multiply the coverage matrix A by the column vector B of the disturbance direction measure, and the synthetic measure column vector C can be obtained. C is a matrix of order 1×L. The elements in matrix C are the credibility values of the possible disturbance sources corresponding to the branches. The greater the credibility value, the greater the reliability of the existence of a disturbance source in this line.

[0016] Step S4. Obtain the monitoring point data: Obtain the data collected by each monitoring point through monitoring devices, and classify and summarize the data. This process classifies the data collected by the monitoring points according to the differences in the distribution network transmission lines and the types of distributed power sources, and performs secondary classification and induction processing through the power supply objects of the distribution network; Step S5. Solve the data: Input the obtained monitoring point data into the normal voltage model for calculation. If the calculation result conforms to the normal voltage model, directly output the result. If the calculation result does not conform to the normal voltage model, input the monitoring point data into the disturbance source signal model for calculation to determine the type of disturbance source, and then input it into the disturbance-normal comparison model for waveform comparison. Locate the disturbance direction according to the comparison result, and the solved result will be displayed through visualization technology.

[0017] Only some exemplary embodiments of the present invention have been described above by way of illustration. Without doubt, for those of ordinary skill in the art, various different ways can be used to modify the described embodiments without departing from the spirit and scope of the present invention. Therefore, the above drawings and descriptions are illustrative in nature and should not be construed as limiting the protection scope of the claims of the present invention.

Claims

1. A method for locating power quality disturbance sources in a distribution network containing distributed power sources, characterized in that: The following steps are involved: Step S1. Setting monitoring points: Setting monitoring equipment on each line of the distribution network according to the power input and output data of the distribution network; Step S2. Classify disturbance sources: obtain previous distribution network data, analyze the previous distribution network data, and confirm the type of disturbance source; Step S3. Constructing a calculation model: constructing a disturbance source signal model, a normal voltage model and a disturbance-normal comparison model according to the disturbance source types obtained above; Step S4. Obtaining monitoring point data: Obtaining data collected at each monitoring point through monitoring equipment, and summarizing and classifying the data; Step S5. Solve the data: input the obtained monitoring point data into the normal voltage model for calculation. If the calculation result conforms to the normal voltage model, directly output the result. If the calculation result does not conform to the normal voltage model, input the monitoring point data into the disturbance source signal model for calculation to determine the type of disturbance source. Then input the disturbance-normal comparison model for waveform comparison and locate the disturbance direction according to the comparison result.

2. The method for locating power quality disturbance sources in a distribution network containing distributed power sources according to claim 1, characterized in that: The monitoring device in step S1 is a power quality monitor, and the monitoring device in step S1 is set at the power input point, transfer node, and power output point on each line of the distribution network.

3. The method for locating power quality disturbance sources in a distribution network containing distributed power sources according to claim 1, characterized in that: The types of disturbance sources divided in step S2 are as follows: (1) Voltage sag; (2) Temporary voltage rise; (3) Voltage interruption; (4) Pulse interference; (5) Oscillation; (6) Harmonics.

4. The method for locating power quality disturbance sources in a distribution network containing distributed power sources according to claim 1, characterized in that: The disturbance source signal model in step S3 is constructed according to various types of disturbance source waveform formulas, and the various types of disturbance source waveform formulas are specifically as follows: Voltage sag: in, is the angular frequency, As parameters, , is the voltage sag time point; Voltage swell: in, is the angular frequency, As parameters, , is the voltage sag time point; Voltage interruption: in, is the angular frequency, As parameters, , is the voltage sag time point; Pulse interference: in, is the angular frequency, As parameters, , is the voltage sag time point; oscillation: in, is the angular frequency, a, c, d are all parameters, For time, For cycle harmonic: in, is the angular frequency, , is the harmonic time point, A is the normalized amplitude, is the harmonic phase angle.

5. The method for locating power quality disturbance sources in a distribution network containing distributed power sources according to claim 1, characterized in that: The normal voltage model in step S3 is constructed according to the normal voltage waveform formula, and the normal voltage waveform formula is as follows: in, is the angular frequency, For time.

6. The method for locating power quality disturbance sources in a distribution network containing distributed power sources according to claim 1, characterized in that: In step S3, the disturbance-normal contrast model is constructed by a waveform contrast algorithm and a disturbance source positioning algorithm, and the disturbance-normal contrast model calculation steps are as follows: S1-1. Filter the voltage waveform signal output by the normal voltage model and the disturbance source signal model to remove noise and interference signals; S1-2. Normalize the filtered voltage waveform signal data to ensure that the amplitude and phase differences between the two sets of data are small; S1-3. Sample the processed voltage waveform signal data to obtain the voltage waveform peak and valley data at the same time point; S1-4. Compare the size of the two sets of voltage waveform peaks and peak-to-valley data, confirm the size trend of the two sets of voltage waveform peaks and peak-to-valley data, and preliminarily determine the disturbance direction based on the trend relationship; S1-5. Combined with the disturbance source positioning algorithm, the location of the disturbance source is further determined.

7. A method for locating power quality disturbance sources in a distribution network containing distributed power sources according to claim 6, characterized in that: If the peak value and peak-to-valley value of the voltage waveform of the normal voltage model are larger than the peak value and peak-to-valley value of the voltage waveform of the disturbance source signal model, and the trend relationship will continue to increase, it indicates that a disturbance occurs upstream, and the disturbance source is determined to be a disturbance type that absorbs energy. Conversely, if the peak value and peak-to-valley value of the voltage waveform of the normal voltage model are smaller than the peak value and peak-to-valley value of the voltage waveform of the disturbance source signal model, and the trend relationship will continue to decrease, it indicates that a disturbance occurs downstream, and the disturbance source is determined to be a disturbance type that injects energy.

8. The method for locating power quality disturbance sources in a distribution network containing distributed power sources according to claim 6, characterized in that: The disturbance source positioning algorithm uses a multi-point positioning algorithm, and the specific steps are as follows: S2-1. Construct the covering matrix A and the direction measure column vector B. The covering matrix is ​​as follows: Where, L is the number of distribution network branches; M is the number of monitoring points, The direction measure column vector B is as follows: in, The direction measurement value at the monitoring point n is calculated by inputting the disturbance power and disturbance energy into the membership function; S2-2. Numerical calculation, if the line Located in the downstream area of ​​the nth monitoring point, let , if the line Located in the upstream area of ​​the jth monitoring point, let , by multiplying the covering matrix A by the disturbance direction measure column vector B, we can get the synthetic measure column vector C, which is an LX1-order matrix. The elements in the matrix C are the confidence values ​​of the possible disturbance sources in the corresponding branches. The larger the confidence value, the greater the reliability of the existence of disturbance sources in this line.

9. The method for locating power quality disturbance sources in a distribution network containing distributed power sources according to claim 1, characterized in that: In the step S4, the data collected by the monitoring points are classified according to the different transmission lines of the distribution network and the types of distributed power sources, and secondary classification and summarization are performed according to the power supply objects of the distribution network.

10. The method for locating power quality disturbance sources in a distribution network containing distributed power sources according to claim 1, characterized in that: The result of the solution in step S5 will be displayed through visualization technology.

Images