阅读说明：本技术 一种台区低压配电网拓扑及线路阻抗识别方法 (Method for identifying topology and line impedance of distribution room low-voltage power distribution network ) 是由 巴祎 于 2019-09-11 设计创作，主要内容包括：一种台区低压配电网拓扑及线路阻抗识别方法,属于低压配电网技术领域。该方法首先在台区低压配电网中增加一个边缘计算终端及若干个电气测量装置；在每次台区低压配电网拓扑识别时,根据测量装置与边缘计算终端之间的电力线载波通信关系,确定测量装置台区归属关系及通信接入相的相别,每个测量装置与边缘计算终端进行时间同步后进行电压和电流波形采样并上传边缘计算终端,边缘计算终端依据波形数据识别出同一母线测量装置及母线上级测量装置；多次拓扑识别后,得到最终的拓扑识别结果并进行阻抗计算。本发明对低压配电网拓扑及线路阻抗识别准确率高、速度快,且充分利用低压配电网智能设备的采集信息能力,设备成本低,对电能质量无影响。(A method for identifying topology and line impedance of a transformer area low-voltage power distribution network belongs to the technical field of low-voltage power distribution networks. The method comprises the steps that firstly, an edge computing terminal and a plurality of electrical measuring devices are added in a low-voltage distribution network of a transformer area; when the topology of the low-voltage distribution network of each distribution area is identified, the affiliation relationship of the distribution area of the measuring device and the phase of a communication access phase are determined according to the power line carrier communication relationship between the measuring device and the edge computing terminal, each measuring device and the edge computing terminal perform time synchronization, then voltage and current waveform sampling is performed, the voltage and current waveform sampling is uploaded to the edge computing terminal, and the edge computing terminal identifies the same bus measuring device and a bus higher-level measuring device according to waveform data; and after multiple times of topology identification, obtaining a final topology identification result and carrying out impedance calculation. The method has high accuracy and high speed for identifying the topology and the line impedance of the low-voltage distribution network, fully utilizes the information acquisition capability of intelligent equipment of the low-voltage distribution network, has low equipment cost and has no influence on the quality of electric energy.)

1. A method for identifying topology of a low-voltage distribution network in a transformer area is characterized by comprising the following steps:

1) arranging an edge computing terminal in each distribution box of the low-voltage distribution network of the distribution area, and arranging a corresponding electrical measuring device at each outgoing line of each distribution box and each incoming line of each metering box in the low-voltage distribution network of the distribution area; the electrical measuring device is used for acquiring three-phase or single-phase voltage waveforms at corresponding positions and each corresponding current waveform; each electrical measuring device is communicated with the edge computing terminal of the platform area respectively; synchronous time synchronization is carried out between the edge calculation terminal and each measuring device, so that the relative time error between the edge calculation terminal and each measuring device is less than +/-10 ms;

2) making a counter i equal to 1;

3) when the topology identification of the low-voltage distribution network of the station area is carried out for the ith time in each station area, determining the attribution relationship of each measuring device station area and the phase of the communication access phase of the measuring device according to the communication between each measuring device and the edge computing terminal of the station area;

4) time synchronization is carried out on all the measuring devices in the transformer area, so that the relative time error of any two measuring devices in each transformer area is within +/-10 ms;

5) utilizing the result of the step 3), each platform area edge computing terminal sends a voltage waveform sampling requirement and a corresponding current waveform sampling requirement to each measuring device of the platform area;

6) each measuring device in the transformer area intercepts corresponding voltage waveform samples and current waveform samples according to the requirements received in the step 5) and uploads the voltage waveform samples and the current waveform samples to an edge computing node terminal of the transformer area;

7) the edge computing terminal of each station area is accessed to phase voltage waveform zero crossing time according to received communication of each measuring device, the voltage waveforms of each measuring device are aligned in time, relative time errors of each measuring device are eliminated, and the measuring device for collecting three-phase voltage determines the corresponding phase of the other two phases according to the zero crossing time of the voltage waveforms of the other two phases;

8) and each platform area edge computing terminal judges all the measuring devices in the platform area based on the received voltage waveform samples of the measuring devices:

if the fundamental wave amplitude relative deviation of the same phase voltage waveforms of any two measuring devices is within a set first fundamental wave amplitude deviation threshold value, and the jth harmonic amplitude relative deviation of the same phase voltage waveforms of the two measuring devices is within a set first jth harmonic amplitude deviation threshold value, the two measuring devices are measuring devices on the same bus; wherein j is sequentially 2,3 … n, n is the upper limit of harmonic frequency, n is less than or equal to 50

After all the measuring devices in the transformer area are judged, all the buses are numbered in sequence;

9) each distribution area edge computing terminal judges all the measuring devices in the distribution area based on the received current waveform samples of the measuring devices:

based on the current waveform sample sent by each measuring device, calculating the current fundamental wave measuring vector sum value of each measuring device in the same bus as A1 and k-order harmonic current vector sum value Ak according to the judgment result of the step 8), wherein k is 2,3 … n in sequence, and searching the superior measuring device corresponding to the bus based on the values from A1 to An; the specific method comprises the following steps:

randomly selecting a current waveform of a measuring device, and calculating a current fundamental wave vector value of the device as B1, a k-th harmonic current vector value and a Bk value, wherein k is 2,3 … n in sequence; if the relative deviation of the amplitudes A1 and B1 is within the range of the set second fundamental wave amplitude deviation threshold value, the relative deviation of the amplitudes Ak and Bk is within the range of the set corresponding second ik harmonic amplitude deviation threshold value, and k is 2 and 3 … n, the selected measuring device is considered as the bus superior measuring device;

10) forming the ith topology identification result of the low-voltage distribution network of each distribution area by using the result of the step 9), marking the measurement devices which are not connected with other measurement devices of the distribution area in the topology result as isolated measurement devices, and removing the isolated measurement devices from the distribution area topology range;

11) making i equal to i +1, then returning to the step 2), and performing next topology identification until i equal to m, and obtaining topology identification results of the low-voltage distribution network of each distribution area m times in total, wherein m is the upper limit of the number of times of topology identification;

and in the m-time identification results, identifying the measuring device which is positioned on the same bus each time as the final measuring device positioned on the same bus, renumbering the bus corresponding to each measuring device, and if any measuring device is the same bus higher-level measuring device in each identification result, judging the measuring device as the final bus higher-level measuring device to obtain the final station area topology identification result.

2. A line impedance identification method for a low-voltage distribution network in a transformer area is characterized by comprising the following steps:

1) arranging an edge computing terminal in each distribution box of the low-voltage distribution network of the distribution area, and arranging a corresponding electrical measuring device at each outgoing line of each distribution box and each incoming line of each metering box in the low-voltage distribution network of the distribution area; the electrical measuring device is used for acquiring three-phase or single-phase voltage waveforms at corresponding positions and each corresponding current waveform; each electrical measuring device is communicated with the edge computing terminal of the platform area respectively; synchronous time synchronization is carried out between the edge calculation terminal and each measuring device, so that the relative time error between the edge calculation terminal and each measuring device is less than +/-10 ms;

2) making a counter i equal to 1;

3) when the topology identification of the low-voltage distribution network of the station area is carried out for the ith time in each station area, determining the attribution relationship of each measuring device station area and the phase of the communication access phase of the measuring device according to the communication between each measuring device and the edge computing terminal of the station area;

4) time synchronization is carried out on all the measuring devices in the transformer area, so that the relative time error of any two measuring devices in each transformer area is within +/-10 ms;

5) utilizing the result of the step 3), each platform area edge computing terminal sends a voltage waveform sampling requirement and a corresponding current waveform sampling requirement to each measuring device of the platform area;

6) each measuring device in the transformer area intercepts corresponding voltage waveform samples and current waveform samples according to the requirements received in the step 5) and uploads the voltage waveform samples and the current waveform samples to an edge computing node terminal of the transformer area;

7) the edge computing terminal of each station area is accessed to phase voltage waveform zero crossing time according to received communication of each measuring device, the voltage waveforms of each measuring device are aligned in time, relative time errors of each measuring device are eliminated, and the measuring device for collecting three-phase voltage determines the corresponding phase of the other two phases according to the zero crossing time of the voltage waveforms of the other two phases;

8) and each platform area edge computing terminal judges all the measuring devices in the platform area based on the received voltage waveform samples of the measuring devices:

if the fundamental wave amplitude relative deviation of the same phase voltage waveforms of any two measuring devices is within a set first fundamental wave amplitude deviation threshold value, and the jth harmonic amplitude relative deviation of the same phase voltage waveforms of the two measuring devices is within a set first jth harmonic amplitude deviation threshold value, the two measuring devices are measuring devices on the same bus; wherein j is sequentially 2,3 … n, n is the upper limit of harmonic frequency, n is less than or equal to 50

After all the measuring devices in the transformer area are judged, all the buses are numbered in sequence;

9) each distribution area edge computing terminal judges all the measuring devices in the distribution area based on the received current waveform samples of the measuring devices:

based on the current waveform sample sent by each measuring device, calculating the current fundamental wave measuring vector sum value of each measuring device in the same bus as A1 and k-order harmonic current vector sum value Ak according to the judgment result of the step 8), wherein k is 2,3 … n in sequence, and searching the superior measuring device corresponding to the bus based on the values from A1 to An; the specific method comprises the following steps:

randomly selecting a current waveform of a measuring device, and calculating a current fundamental wave vector value of the device as B1, a k-th harmonic current vector value and a Bk value, wherein k is 2,3 … n in sequence; if the relative deviation of the amplitudes of A1 and B1 is within the range of the set second fundamental wave amplitude deviation threshold value, the relative deviation of the amplitudes of Ak and Bk is within the range of the set corresponding second k-th harmonic amplitude deviation threshold value, and k is 2 and 3 … n, the selected measuring device is considered as the bus superior measuring device;

10) forming the ith topology identification result of the low-voltage distribution network of each distribution area by using the result of the step 9), marking the measurement devices which are not connected with other measurement devices of the distribution area in the topology result as isolated measurement devices, and removing the isolated measurement devices from the distribution area topology range;

11) making i equal to i +1, then returning to the step 2), and performing next topology identification until i equal to m, and obtaining topology identification results of the low-voltage distribution network of each distribution area m times in total, wherein m is the upper limit of the number of times of topology identification;

identifying the measuring device which is positioned on the same bus in the m-time identification results each time as the final measuring device positioned on the same bus, renumbering the buses corresponding to the measuring devices, and if any measuring device is the same bus higher-level measuring device in each identification result, judging the measuring device as the final bus higher-level measuring device to obtain the final station area topology identification result;

12) utilizing the result of the step 11), based on the voltage waveform and the current waveform measured by the measuring devices at two ends of each line in any topology identification, aligning each waveform of each measuring device in each line according to the current waveform, and calculating the amplitude and the phase of the fundamental wave and the L-th harmonic wave of each phase voltage current waveform at two ends of each line, and the amplitude and the phase of each sequence component fundamental wave and the L-th harmonic wave of each sequence component voltage current waveform at two ends of each line, wherein L is 2 and 3 … n in sequence; and calculating the impedance of the fundamental wave and each subharmonic of each line and the impedance of each sequence component according to the circuit principle.

Technical Field

The invention belongs to the technical field of low-voltage power distribution networks, and particularly relates to a method for identifying topology and line impedance of a distribution room low-voltage power distribution network.

Background

The topological relation of the low-voltage distribution networks in the transformer area is the basis for developing intelligent services of the low-voltage distribution networks in other transformer areas, and can help to solve various power grid services such as accurate judgment of power failure ranges, line loss statistics and the like. Along with the construction of the intelligent power grid, devices such as switches and monitoring terminals of a low-voltage power distribution network in a transformer area have the voltage and current acquisition and external communication capabilities.

The distribution area low-voltage distribution network has the characteristics of wide distribution and complex topology types, so that the technical problem in the field of low-voltage distribution is how to accurately and quickly obtain the topology of the low-voltage distribution network.

The topology of the low-voltage distribution network in the transformer area is obtained through a manual method, which is troublesome and labor-consuming and difficult to ensure accuracy.

The power line carrier communication mode is additionally arranged at the electric meter, so that only the relation between a user and a transformer and the phase splitting relation of the user can be identified, and the branch relation at the distribution box equipment in low-voltage distribution and the subordinate and line upstream and downstream relations of the equipment are difficult to identify.

The branch relation identification of the low-voltage distribution network can be solved by injecting signals into the low-voltage equipment, but the method has the defects of high equipment cost and influence of the injected signals on the electric energy quality.

The branch relation of the low-voltage distribution network can be identified through the minute-level voltage and current effective value information of the operating equipment, but the method has the defects of low accuracy and long consumed time.

The existing low-voltage line impedance identification method generally identifies based on the existing topological information, but the topological relation of a low-voltage transformer area is generally not available in the actual situation, so that the low-voltage line impedance identification cannot be carried out. In addition, the existing impedance identification method is mainly used for calculating based on the voltage, current effective value and power value acquired by each node, and due to the lack of simultaneity of data acquisition, the calculated line impedance error is easy to be larger due to some random interference factors.

Disclosure of Invention

The invention aims to overcome the defects of the prior art and provides a method for identifying topology and line impedance of a low-voltage distribution network of a transformer area. The method has the advantages of high accuracy and high speed of topology and line impedance identification, fully utilizes the information acquisition capability of intelligent equipment of the low-voltage distribution network, has low equipment cost and has no influence on the power quality of a power grid.

The invention provides a method for identifying the topology of a low-voltage distribution network in a distribution area, which is characterized by comprising the following steps of:

1) arranging an edge computing terminal in each distribution box of the low-voltage distribution network of the distribution area, and arranging a corresponding electrical measuring device at each outgoing line of each distribution box and each incoming line of each metering box in the low-voltage distribution network of the distribution area; the electrical measuring device is used for acquiring three-phase or single-phase voltage waveforms at corresponding positions and each corresponding current waveform; each electrical measuring device is communicated with the edge computing terminal of the platform area respectively; synchronous time synchronization is carried out between the edge calculation terminal and each measuring device, so that the relative time error between the edge calculation terminal and each measuring device is less than +/-10 ms;

2) making a counter i equal to 1;

3) when the topology identification of the low-voltage distribution network of the station area is carried out for the ith time in each station area, determining the attribution relationship of each measuring device station area and the phase of the communication access phase of the measuring device according to the communication between each measuring device and the edge computing terminal of the station area;

4) time synchronization is carried out on all the measuring devices in the transformer area, so that the relative time error of any two measuring devices in each transformer area is within +/-10 ms;

5) utilizing the result of the step 3), each platform area edge computing terminal sends a voltage waveform sampling requirement and a corresponding current waveform sampling requirement to each measuring device of the platform area;

6) each measuring device in the transformer area intercepts corresponding voltage waveform samples and current waveform samples according to the requirements received in the step 5) and uploads the voltage waveform samples and the current waveform samples to an edge computing node terminal of the transformer area;

7) the edge computing terminal of each station area is accessed to phase voltage waveform zero crossing time according to received communication of each measuring device, the voltage waveforms of each measuring device are aligned in time, relative time errors of each measuring device are eliminated, and the measuring device for collecting three-phase voltage determines the corresponding phase of the other two phases according to the zero crossing time of the voltage waveforms of the other two phases;

8) and each platform area edge computing terminal judges all the measuring devices in the platform area based on the received voltage waveform samples of the measuring devices:

if the fundamental wave amplitude relative deviation of the same phase voltage waveforms of any two measuring devices is within a set first fundamental wave amplitude deviation threshold value, and the jth harmonic amplitude relative deviation of the same phase voltage waveforms of the two measuring devices is within a set first jth harmonic amplitude deviation threshold value, the two measuring devices are measuring devices on the same bus; wherein j is sequentially 2,3 … n, n is the upper limit of harmonic frequency, n is less than or equal to 50

After all the measuring devices in the transformer area are judged, all the buses are numbered in sequence;

9) each distribution area edge computing terminal judges all the measuring devices in the distribution area based on the received current waveform samples of the measuring devices:

based on the current waveform sample sent by each measuring device, calculating the current fundamental wave measuring vector sum value of each measuring device in the same bus as A1 and k-order harmonic current vector sum value Ak according to the judgment result of the step 8), wherein k is 2,3 … n in sequence, and searching the superior measuring device corresponding to the bus based on the values from A1 to An; the specific method comprises the following steps:

randomly selecting a current waveform of a measuring device, and calculating a current fundamental wave vector value of the device as B1, a k-th harmonic current vector value and a Bk value, wherein k is 2,3 … n in sequence; if the relative deviation of the amplitudes A1 and B1 is within the range of the set second fundamental wave amplitude deviation threshold value, the relative deviation of the amplitudes Ak and Bk is within the range of the set corresponding second ik harmonic amplitude deviation threshold value, and k is 2 and 3 … n, the selected measuring device is considered as the bus superior measuring device;

10) forming the ith topology identification result of the low-voltage distribution network of each distribution area by using the result of the step 9), marking the measurement devices which are not connected with other measurement devices of the distribution area in the topology result as isolated measurement devices, and removing the isolated measurement devices from the distribution area topology range;

11) making i equal to i +1, then returning to the step 2), and performing next topology identification until i equal to m, and obtaining topology identification results of the low-voltage distribution network of each distribution area m times in total, wherein m is the upper limit of the number of times of topology identification;

and in the m-time identification results, identifying the measuring device which is positioned on the same bus each time as the final measuring device positioned on the same bus, renumbering the bus corresponding to each measuring device, and if any measuring device is the same bus higher-level measuring device in each identification result, judging the measuring device as the final bus higher-level measuring device to obtain the final station area topology identification result.

The invention provides a line impedance identification method for a low-voltage distribution network in a transformer area, which is characterized by comprising the following steps of:

1) arranging an edge computing terminal in each distribution box of the low-voltage distribution network of the distribution area, and arranging a corresponding electrical measuring device at each outgoing line of each distribution box and each incoming line of each metering box in the low-voltage distribution network of the distribution area; the electrical measuring device is used for acquiring three-phase or single-phase voltage waveforms at corresponding positions and each corresponding current waveform; each electrical measuring device is communicated with the edge computing terminal of the platform area respectively; synchronous time synchronization is carried out between the edge calculation terminal and each measuring device, so that the relative time error between the edge calculation terminal and each measuring device is less than +/-10 ms;

2) making a counter i equal to 1;

3) when the topology identification of the low-voltage distribution network of the station area is carried out for the ith time in each station area, determining the attribution relationship of each measuring device station area and the phase of the communication access phase of the measuring device according to the communication between each measuring device and the edge computing terminal of the station area;

4) time synchronization is carried out on all the measuring devices in the transformer area, so that the relative time error of any two measuring devices in each transformer area is within +/-10 ms;

5) utilizing the result of the step 3), each platform area edge computing terminal sends a voltage waveform sampling requirement and a corresponding current waveform sampling requirement to each measuring device of the platform area;

6) each measuring device in the transformer area intercepts corresponding voltage waveform samples and current waveform samples according to the requirements received in the step 5) and uploads the voltage waveform samples and the current waveform samples to an edge computing node terminal of the transformer area;

7) the edge computing terminal of each station area is accessed to phase voltage waveform zero crossing time according to received communication of each measuring device, the voltage waveforms of each measuring device are aligned in time, relative time errors of each measuring device are eliminated, and the measuring device for collecting three-phase voltage determines the corresponding phase of the other two phases according to the zero crossing time of the voltage waveforms of the other two phases;

8) and each platform area edge computing terminal judges all the measuring devices in the platform area based on the received voltage waveform samples of the measuring devices:

if the fundamental wave amplitude relative deviation of the same phase voltage waveforms of any two measuring devices is within a set first fundamental wave amplitude deviation threshold value, and the jth harmonic amplitude relative deviation of the same phase voltage waveforms of the two measuring devices is within a set first jth harmonic amplitude deviation threshold value, the two measuring devices are measuring devices on the same bus; wherein j is sequentially 2,3 … n, n is the upper limit of harmonic frequency, n is less than or equal to 50

After all the measuring devices in the transformer area are judged, all the buses are numbered in sequence;

9) each distribution area edge computing terminal judges all the measuring devices in the distribution area based on the received current waveform samples of the measuring devices:

based on the current waveform sample sent by each measuring device, calculating the current fundamental wave measuring vector sum value of each measuring device in the same bus as A1 and k-order harmonic current vector sum value Ak according to the judgment result of the step 8), wherein k is 2,3 … n in sequence, and searching the superior measuring device corresponding to the bus based on the values from A1 to An; the specific method comprises the following steps:

randomly selecting a current waveform of a measuring device, and calculating a current fundamental wave vector value of the device as B1, a k-th harmonic current vector value and a Bk value, wherein k is 2,3 … n in sequence; if the relative deviation of the amplitudes of A1 and B1 is within the range of the set second fundamental wave amplitude deviation threshold value, the relative deviation of the amplitudes of Ak and Bk is within the range of the set corresponding second k-th harmonic amplitude deviation threshold value, and k is 2 and 3 … n, the selected measuring device is considered as the bus superior measuring device;

10) forming the ith topology identification result of the low-voltage distribution network of each distribution area by using the result of the step 9), marking the measurement devices which are not connected with other measurement devices of the distribution area in the topology result as isolated measurement devices, and removing the isolated measurement devices from the distribution area topology range;

11) making i equal to i +1, then returning to the step 2), and performing next topology identification until i equal to m, and obtaining topology identification results of the low-voltage distribution network of each distribution area m times in total, wherein m is the upper limit of the number of times of topology identification;

identifying the measuring device which is positioned on the same bus in the m-time identification results each time as the final measuring device positioned on the same bus, renumbering the buses corresponding to the measuring devices, and if any measuring device is the same bus higher-level measuring device in each identification result, judging the measuring device as the final bus higher-level measuring device to obtain the final station area topology identification result;

12) utilizing the result of the step 11), based on the voltage waveform and the current waveform measured by the measuring devices at two ends of each line in any topology identification, aligning each waveform of each measuring device in each line according to the current waveform, and calculating the amplitude and the phase of the fundamental wave and the L-th harmonic wave of each phase voltage current waveform at two ends of each line, and the amplitude and the phase of each sequence component fundamental wave and the L-th harmonic wave of each sequence component voltage current waveform at two ends of each line, wherein L is 2 and 3 … n in sequence; and calculating the impedance of the fundamental wave and each subharmonic of each line and the impedance of each sequence component according to the circuit principle.

The invention has the characteristics and beneficial effects that:

according to the method, the identification of the subordinate station areas of the equipment is realized by utilizing a power line carrier, the time synchronization of each voltage and current measuring device is realized by utilizing the power line carrier communication/Beidou/GPS technology, the time synchronization relative error requirement is less than +/-10 ms, then the simultaneous and different characteristics of three-phase voltage and three-phase current waveforms of each measuring device in a low-voltage distribution network are fully utilized, the identification of the phase and topological position of each measuring device is completed by extracting the characteristic numerical values of the voltage and current waveforms, and the low-voltage topological relation of the station areas is formed. And simultaneously, calculating the impedance of each section of line by using the generated topological relation and the voltage and current waveform information at two sides of the line.

The method has the characteristics of rapid and accurate topology and impedance identification, fully utilizes the voltage and current waveform information of each measuring point, does not need to additionally install a device, saves the cost, and has no electric energy quality influence on the low-voltage distribution network.

Drawings

FIG. 1 is an overall flow diagram of the method of the present invention.

FIG. 2 is a schematic diagram of the connection between the edge computing terminal and the electrical quantity measuring device according to the embodiment of the present invention.

Fig. 3 is a schematic diagram of an actual topology identification result of the low-voltage distribution network in the embodiment of the invention.

Detailed Description

The invention provides a method for identifying topology and line impedance of a low-voltage distribution network in a transformer area, and the invention is further described in detail below by combining the accompanying drawings and specific embodiments.

The invention provides a method for identifying topology and line impedance of a low-voltage distribution network in a transformer area, wherein the low voltage is 1000V or less, the overall flow of the method is shown in figure 1, and the method comprises the following steps:

1) adding an edge computing terminal and a plurality of electrical measuring devices in each transformer area low-voltage distribution network;

an edge computing terminal is arranged in each distribution box of the low-voltage distribution network of the distribution area, the edge computing terminal can be arranged in the distribution box or at other positions capable of realizing power line carrier communication, and corresponding electrical measuring devices (hereinafter referred to as measuring devices) are respectively arranged at the outgoing lines of each distribution box and the incoming lines of each metering box in the low-voltage distribution network of the distribution area and are used for collecting three-phase or single-phase voltage waveforms and current waveforms corresponding to the three-phase or single-phase voltage waveforms and the current waveforms. And each electrical measuring device is communicated with the edge computing terminal of the station area through a power line carrier communication mode. The electric measuring device can adopt conventional equipment and comprises a voltage current sensor, an external power line carrier communication module, a data acquisition module, a main control module, a power supply module, a Beidou/GPS time synchronization module and the like, and the relative time error is smaller than +/-10 ms when time synchronization is carried out between the measuring devices through the Beidou/GPS or power line carrier communication.

The edge computing terminal can adopt conventional equipment and comprises a main control CPU, a power line carrier communication unit, a power supply module and the like. The edge computing terminal can have electrical measurement capability and can also comprise a voltage and current sensor and an AD acquisition circuit. The invention can adopt edge computing terminals of any type.

Each electrical measuring device has the voltage and current waveform acquisition capacity and can upload the acquired waveforms according to the requirements of the edge computing terminal; the edge computing terminal and each measuring device have synchronous time setting capability, and the relative time error is less than +/-10 ms.

2) Making a counter i equal to 1;

3) when the topology identification of the low-voltage distribution network of the station area is carried out for the ith time in each station area, determining the affiliation relationship of each measuring device station area and the phase of the communication access phase of the measuring device according to the power line carrier communication between each measuring device and the edge computing terminal of the station area (if the measuring device collects single-phase voltage, the single phase is the communication access phase; if the measuring device collects three-phase voltages, one phase is a communication access phase);

4) the time synchronization of each measuring device in the transformer area is realized by using any one of the power line carrier communication/GPS/Beidou modes, so that the relative time error of any two measuring devices in each transformer area is within +/-10 ms;

5) utilizing the result of the step 3), each platform area edge computing terminal sends a voltage waveform sampling requirement and a corresponding current waveform sampling requirement to each measuring device of the platform area; the waveform sampling requirement can adopt a mode of time interval requirement or initial time plus cycle number requirement;

for example, the period requirement: the edge computing terminal may require each measuring device of the local area to send a voltage waveform and a corresponding current waveform of between 2019, 8, 30, 15:00:00:000 and 2019, 8, 30, 15:00:00: 100; the requirement of adding the number of waveforms at the starting time is as follows: the edge computing terminal may request that each measurement device of the local area send a voltage waveform and corresponding current waveform for 5 cycle times from 30/8/2019 and 15:00:00: 000.

6) Each measuring device of the transformer area intercepts corresponding voltage waveform samples and current waveform samples (each phase voltage corresponds to one waveform, each phase current corresponds to one waveform, and if the electric measuring device collects three-phase voltages, the measuring device intercepts six corresponding waveforms; if the electric measuring device collects single-phase voltage, the measuring device intercepts two corresponding waveforms) and uploads the two waveforms to an edge computing node terminal of the local area;

7) the edge computing terminal of each station area is accessed to phase voltage waveform zero crossing time according to received communication of each measuring device, the voltage waveforms of each measuring device are aligned in time, relative time errors of each measuring device are eliminated, and the measuring device for collecting three-phase voltage determines the corresponding phase of the other two phases according to the zero crossing time of the voltage waveforms of the other two phases;

8) and each platform area edge computing terminal judges all the measuring devices in the platform area based on the received voltage waveform samples of the measuring devices:

if the fundamental wave amplitude relative deviation of the same phase voltage waveforms of any two measuring devices is within a set first fundamental wave amplitude deviation threshold value, and the jth harmonic amplitude relative deviation of the same phase voltage waveforms of the two measuring devices is within a set first jth harmonic amplitude deviation threshold value, the two measuring devices are measuring devices on the same bus; wherein j is sequentially 2,3 … n, n is the upper limit of harmonic frequency, n is less than or equal to 50

After all the measuring devices in the transformer area are judged, all the buses are numbered in sequence;

in this embodiment, both the first fundamental amplitude deviation threshold and the first j-th harmonic amplitude deviation threshold are ± 0.5%;

9) and each platform area edge computing terminal judges all the measuring devices in the platform area according to the same line current equality principle based on the received current waveform sample of the measuring device:

based on the current waveform sample sent by each measuring device, calculating the current fundamental wave measuring vector sum value of each measuring device in the same bus as A1 and k-order harmonic current vector sum value Ak according to the judgment result of the step 8), wherein k is 2,3 … n in sequence, and searching the superior measuring device corresponding to the bus based on the values from A1 to An; the specific method comprises the following steps:

randomly selecting a current waveform of a measuring device, and calculating a current fundamental wave vector value of the device as B1, a k-th harmonic current vector value and a Bk value, wherein k is 2,3 … n in sequence; if the relative deviation of the amplitudes A1 and B1 is within the range of the set fundamental wave amplitude deviation threshold value, the relative deviation of the amplitudes Ak and Bk is within the range of the set corresponding second k-th harmonic amplitude deviation threshold value, and k is 2 and 3 … n, the selected measuring device is considered as the bus superior measuring device; wherein n is the upper limit of the harmonic frequency, and n is less than or equal to 50;

in this embodiment, both the second fundamental amplitude deviation threshold and the second k-th harmonic amplitude deviation threshold are ± 0.2%;

10) forming the ith topology identification result of the low-voltage distribution network of each distribution area by using the result of the step 9), and rejecting the topology range of each distribution area by using an isolated measuring device in the topology result of each distribution area, wherein the isolated measuring device is not connected with all other measuring devices of the distribution area (the non-connection means that no other measuring device is positioned on the same bus or no superior measuring device is positioned), and the isolated measuring device is considered as an interference signal, so that the topology range is rejected;

11) making i equal to i +1, then returning to the step 2), performing next topology identification until i equal to m, and obtaining topology identification results of the low-voltage distribution network of each distribution area m times, wherein m is the upper limit of the number of times of topology identification (the value of m is 5-10 times);

in the m-time identification results, the measuring device which is positioned on the same bus in each time of identification is identified as the final measuring device positioned on the same bus; and the buses corresponding to the measuring devices are renumbered, if any measuring device is the same bus higher-level measuring device in each identification result, the measuring device is judged as the final bus higher-level measuring device, and the final station topology identification result is obtained.

12) Utilizing the result of the step 11), based on the voltage waveform and the current waveform measured by the measuring devices at two ends of each line in any topology identification, aligning each waveform of each measuring device in each line according to the current waveform, calculating the amplitude and the phase of the fundamental wave and the i-th harmonic wave of each phase voltage current waveform at two ends of each line, and the amplitude and the phase of each sequence component fundamental wave and the i-th harmonic wave of each sequence voltage current waveform at two ends of each line, wherein i takes the value of 2 and 3 … n in sequence; and calculating the impedance of the fundamental wave and each subharmonic of each line and the impedance of each sequence component according to the circuit principle.

The present invention is further described in detail below with reference to a specific example.

The embodiment provides a method for identifying topology and line impedance of a low-voltage distribution network in a transformer area, which comprises the following steps:

1) adding an edge computing terminal and a plurality of electrical measuring devices in a low-voltage distribution network of a transformer area;

FIG. 2 is a schematic diagram of the connection between the edge computing terminal and the electrical quantity measuring device according to the embodiment of the present invention. In fig. 2, the low-voltage distribution network includes an edge computing terminal (in this embodiment, the edge computing terminal includes a measuring device M0) and measuring devices M1-M14, and M1-M14 communicate with the edge computing terminal in a power line carrier manner.

2) Making a counter i equal to 1;

3) when the topology identification of the low-voltage distribution network of the station area is carried out for the ith time in the station area, determining the affiliation relationship of the station area of each measuring device and the phase of a communication access phase of the measuring device according to power line carrier communication between each measuring device (intelligent switch) and an edge computing terminal of the station area;

4) the time synchronization of each measuring device is realized by using any one of the power line carrier communication/Beidou/GPS communication modes, so that the relative time error between any two measuring devices in each station area is less than +/-10 ms;

5) utilizing the result of the step 3), each platform area edge computing terminal sends a voltage waveform sampling requirement and a corresponding current waveform sampling requirement to each measuring device of the platform area; in this embodiment, the waveform sampling requirement is a mode of adding a waveform number requirement to a starting time, where the starting time is t1 and the cycle number is a;

6) each measuring device of the transformer area intercepts a corresponding voltage waveform sample and a corresponding current waveform sample according to the requirements received in the step 5) (each phase voltage corresponds to one waveform, each phase current corresponds to one waveform, and if the electric measuring device acquires three-phase voltage, the measuring device intercepts six corresponding waveforms; if the electric measuring device collects single-phase voltage, the measuring device intercepts two corresponding waveforms) and uploads the two waveforms to an edge computing node terminal of the local area;

7) the edge computing terminal of each station area is accessed to phase voltage waveform zero crossing time according to the received communication of each measuring device, the voltage waveforms of each measuring device are aligned in time, the time error of each measuring device is eliminated, and the measuring device for collecting three-phase voltage determines the corresponding phase of the other two phases according to the zero crossing time of the voltage waveforms of the other two phases;

8) and each platform area edge calculation terminal judges according to the same principle of the same bus voltage based on the received voltage waveform sample of the measuring device:

if the fundamental wave amplitude relative deviation of the same phase voltage waveforms of any two measuring devices is within a set first fundamental wave amplitude deviation threshold value, and the jth harmonic amplitude relative deviation of the same phase voltage waveforms of the two measuring devices is within a set first jth harmonic amplitude deviation threshold value, the two measuring devices are measuring devices on the same bus; wherein j is sequentially 2,3 … n, n is the upper limit of harmonic frequency, n is less than or equal to 50

After all the measuring devices in the transformer area are judged, all the buses are numbered in sequence;

in this embodiment, both the first fundamental amplitude deviation threshold and the first j-th harmonic amplitude deviation threshold are ± 0.5%;

9) and each station area edge calculation terminal judges according to the same line current equality principle based on the received current waveform sample of the measuring device:

based on the current waveform sample sent by each measuring device, calculating the current fundamental wave measuring vector sum value of each measuring device in the same bus as A1 and k-order harmonic current vector sum value Ak according to the judgment result of the step 8), wherein k is 2,3 … n in sequence, and searching the superior measuring device corresponding to the bus based on the values from A1 to An; the specific method comprises the following steps:

randomly selecting a current waveform of a measuring device, and calculating a current fundamental wave vector value of the device as B1, a k-th harmonic current vector value and a Bk value, wherein k is 2,3 … n in sequence; if the relative deviation of the amplitudes of A1 and B1 is within the range of the set second fundamental wave amplitude deviation threshold value, the relative deviation of the amplitudes of Ak and Bk is within the range of the set corresponding second k-th harmonic amplitude deviation threshold value, and k is 2 and 3 … n, the selected measuring device is considered as the bus superior measuring device;

in this embodiment, both the second fundamental amplitude deviation threshold and the second k-th harmonic amplitude deviation threshold are ± 0.2%;

10) forming the ith topology identification result of the low-voltage distribution network of each distribution area by using the result of the step 9), and rejecting the topology range of each distribution area by using an isolated measuring device in the topology result of each distribution area, wherein the isolated measuring device is not connected with all other measuring devices of the distribution area (the non-connection means that no other measuring device is positioned on the same bus or no superior measuring device is positioned), and the isolated measuring device is considered as an interference signal, so that the topology range is rejected;

11) making i equal to i +1, then returning to the step 2), performing next topology identification until i equal to m, and obtaining topology identification results of the low-voltage distribution network of each distribution area m times, wherein m is the upper limit of the number of times of topology identification (the value of m is 5-10 times);

and in the m-time identification results, identifying the measuring device which is positioned on the same bus each time as the final measuring device positioned on the same bus, renumbering the bus corresponding to each measuring device, and if any measuring device is the same bus higher-level measuring device in each identification result, judging the measuring device as the final bus higher-level measuring device to obtain the final station area topology identification result.

Fig. 3 is a schematic diagram of an actual topology identification result of the low-voltage distribution network in the embodiment of the invention.

Wherein, M0, M1 and M2 are positioned on the bus 1, M3, M4 and M5 are positioned on the bus 2, M6, M7 and M8 are positioned on the bus 3, M9 is positioned on the bus 4, M10 is positioned on the bus 5, M11 is positioned on the bus 6, M12 is positioned on the bus 7, M13 is positioned on the bus 8, and M14 is positioned on the bus 9; the bus 2 upper-level measuring device is M1, the bus 3 upper-level measuring device is M2, the bus 4 upper-level measuring device is M3, the bus 5 upper-level measuring device is M4, the bus 6 upper-level measuring device is M5, the bus 7 upper-level measuring device is M6, the bus 8 upper-level measuring device is M7, and the bus 9 upper-level measuring device is M8.

12) Utilizing the result of the step 11), based on the voltage waveform and the current waveform measured by the measuring devices at two ends of each line in any topology identification, aligning each waveform of each measuring device in each line according to the current waveform, calculating the amplitude and the phase of the fundamental wave and the i-th harmonic wave of each phase voltage current waveform at two ends of each line, and the amplitude and the phase of each sequence component fundamental wave and the i-th harmonic wave of each sequence voltage current waveform at two ends of each line, wherein i takes the value of 2 and 3 … n in sequence; and calculating the impedance of the fundamental wave and each subharmonic of each line and the impedance of each sequence component according to the circuit principle.