CN114089044B - Line impedance measurement method, computer equipment and storage medium - Google Patents
Line impedance measurement method, computer equipment and storage medium Download PDFInfo
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- CN114089044B CN114089044B CN202111387458.3A CN202111387458A CN114089044B CN 114089044 B CN114089044 B CN 114089044B CN 202111387458 A CN202111387458 A CN 202111387458A CN 114089044 B CN114089044 B CN 114089044B
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- G01R27/02—Measuring real or complex resistance, reactance, impedance, or other two-pole characteristics derived therefrom, e.g. time constant
Abstract
The embodiment of the invention provides a line impedance measuring method, computer equipment and a storage medium, wherein the method comprises the following steps: the concentrator sends a first measurement sampling instruction to the modularized terminal according to a preset measurement sampling period, the modularized terminal responds to the first measurement sampling instruction to determine a first sampling moment and sends the first sampling moment to the concentrator, the concentrator sends a second measurement sampling instruction to slave equipment positioned in the measuring line, the slave equipment responds to the second measurement sampling instruction, current and voltage are sampled at the first sampling moment and uploaded to the modularized terminal respectively, and impedance of the measuring line is calculated through the modularized terminal. In the embodiment of the invention, the clocks at different node devices are calibrated by using the global positioning system, and the unified sampling time is predetermined, so that the slave terminal device collects data at the unified sampling time, the sampling synchronization degree of the slave terminal device is improved, the sampling data are data of all the slave terminal devices in the same frequency, the reliability of the sampling data is improved, and the accuracy of impedance calculation is improved.
Description
Technical Field
The embodiment of the invention relates to the technical field of impedance measurement, in particular to a line impedance measurement method, computer equipment and a storage medium.
Background
Modern power systems mainly consist of power generation links, power transmission links, power distribution links and other links. The distribution link is an important link for connecting a power grid with vast residents, and the distribution network corresponding to the distribution link receives electric energy from a power transmission grid or a regional power plant and distributes the electric energy to various users in situ or step by step according to voltage through a distribution facility. The power distribution network is divided into a high-voltage power distribution network, a medium-voltage power distribution network and a low-voltage power distribution network according to different voltage grades. The power receiving party of the low-voltage power distribution network is usually a town and country residential area, so that the low-voltage power distribution network is not only a terminal in the whole power grid, but also a front end directly facing the market, and has the characteristics of wide distribution and complex power supply environment.
Under the large trend of power grid intellectualization, in order to improve the experience of power grid power receivers and further improve energy efficiency, the running stability and safety of a low-voltage power distribution network are increasingly concerned. In daily life, the line aging and the private connection of the wire are easy to bring potential safety hazards to the operation of the low-voltage distribution network, so that the occurrence of power failure accidents can be prevented and solved in advance according to the two conditions, and the reliability of power supply is improved.
Checking whether the circuit is aged and the private connection is carried out normally by measuring the impedance of the circuit, when the circuit is aged and the private connection is carried out in a power supply loop, the circuit is short-circuited or broken, the impedance calculation result of the circuit is deviated from the impedance of the circuit under normal operation, the current method for measuring the impedance of the circuit of the low-voltage distribution network mainly comprises 1) a non-interference method, the non-interference method divides the power supply circuit into a plurality of sections according to node equipment existing in the circuit, voltage values and current values are acquired aiming at transformer nodes and end equipment nodes of the sections, the multi-point multi-time value taking is carried out, and then mean square error calculation is introduced to obtain the impedance value of the circuit between the nodes. 2) The injection method is based on the completion of the establishment of the network topology structure of the low-voltage distribution network, harmonic current is injected into a circuit where the node is located by using a device at the node for a plurality of times, then a low-voltage distribution network model is simplified, the established low-voltage distribution network model comprises a system power supply, a system impedance, a line impedance and a harmonic source, a plurality of equations are listed by using the Thevenin theorem, the system power supply and the system impedance are reduced by the plurality of equations, and finally the voltage and the current generated by the harmonic power supply represent the impedance of the line between the nodes.
However, when the non-interference method is used for calculating the line impedance, as the plurality of node devices are involved, the plurality of node devices are difficult to complete sampling at the same time after sending the measurement instruction, namely, the operation data of the plurality of node devices in the same cycle are difficult to collect, so that the accuracy of the impedance calculation result of the line between the node devices is low, and the troubleshooting and the overhaul of the fault line are not facilitated. When line impedance is calculated using injection, measurement accuracy is related to the injected harmonic current frequency: if the frequency of the injected harmonic current is higher, the proportion of the capacitance resistance of the power distribution network to the ground in the total impedance of the measurement loop is smaller, so that larger capacitance measurement error to the ground is caused, meanwhile, the measured zero sequence current signal on the open triangle side is weak, the pulse current is difficult to capture, and the impedance of each circuit in the power distribution network is difficult to accurately calculate; if the pulse current frequency is reduced, the excitation impedance of the transformer is reduced, the shunt of the excitation branch is increased, the measurement error of the earth leakage current is increased, and the calculation of the line impedance is inaccurate. When the injection method is adopted to measure the line impedance, the voltage division effect of the impedance in the voltage transformer on the injection characteristic signal is obvious, so that the measurement accuracy is limited.
Disclosure of Invention
The embodiment of the invention provides a line impedance measuring method, computer equipment and a storage medium, which are used for solving the problem that accurate synchronous sampling is difficult to realize for a plurality of node equipment due to the fact that the plurality of node equipment exist in a line when a traditional non-interference method is adopted.
In a first aspect, an embodiment of the present invention provides a line impedance measurement method, which is applied to a concentrator, a modularized terminal and a slave device in a transformer area of the same transformer, where the concentrator is located on an incoming line side of the transformer, the modularized terminal is located on an outgoing line side of the transformer, and the slave device includes a branch switch box and a meter box, and the method includes:
the concentrator sends a first measurement sampling instruction to the modularized terminal according to a preset measurement sampling period;
the modularized terminal responds to the first measurement sampling instruction, determines a first sampling moment and sends the first sampling moment to the concentrator;
the concentrator transmits a second measurement sampling instruction to slave end equipment positioned in a preselected measurement line, wherein the second measurement sampling instruction comprises the first sampling moment;
the slave terminal equipment responds to the second measurement sampling instruction, samples electric power data of current and voltage at the first sampling moment to serve as sampling data, and uploads the sampling data to the modularized terminal;
And the modularized terminal calculates the impedance of the measuring line according to the sampling data.
In a second aspect, an embodiment of the present invention further provides a computer apparatus, including:
one or more processors;
a memory for storing one or more programs,
the one or more programs, when executed by the one or more processors, cause the one or more processors to implement the line impedance measurement method as described in the first aspect.
In a third aspect, embodiments of the present invention further provide a computer readable storage medium having stored thereon a computer program which, when executed by a processor, implements the line impedance measurement method according to the first aspect.
According to the embodiment of the invention, time calibration is uniformly carried out on all node equipment in a power distribution network line through a global positioning system, after a concentrator sends a first measurement sampling instruction to a modularized terminal according to a preset sampling period, the modularized terminal determines uniform sampling time and sends the uniform sampling time to the concentrator, the concentrator includes the determined uniform sampling time in a second measurement sampling instruction, and then the second measurement instruction is sent to each slave equipment positioned in a preselected measurement line, so that each slave equipment collects operation data at the same time as sampling data and uploads the sampling data to the modularized terminal, and the modularized terminal calculates the impedance value of the measurement line according to the sampling data. In the embodiment of the invention, the clock at each node device in the low-voltage distribution network is calibrated by using the time of the global positioning system, the unified sampling time is predetermined, the sampling time is obtained by analysis when the slave device receives the second measurement sampling instruction, and the operation data is collected when the determined sampling time arrives instead of starting to sample when the second measurement sampling instruction is received, so that the synchronization degree of the slave device in the sampling process is improved, the operation data of each slave device in the same cycle is ensured, the reliability of the sampling data for calculating the impedance is improved, and the accuracy of the calculated impedance is improved. In addition, the embodiment of the invention does not need to inject harmonic current into the line where the slave terminal equipment is located, so that the impedance calculation is not influenced by the frequency of the injected harmonic current, and the accuracy of the impedance calculation is ensured.
Drawings
Fig. 1 is a flowchart of a line impedance measurement method according to a first embodiment of the present invention;
fig. 2 is a schematic diagram of a topological relation of a cell according to a first embodiment of the present invention;
fig. 3 is a positive sequence equivalent circuit diagram of a measurement circuit according to a first embodiment of the present invention;
fig. 4 is a zero sequence equivalent circuit diagram of a measurement circuit according to a first embodiment of the present invention;
fig. 5 is a schematic structural diagram of a line impedance measurement system according to a second embodiment of the present invention;
fig. 6 is a schematic structural diagram of a computer device according to a third embodiment of the present invention.
Detailed Description
The invention is described in further detail below with reference to the drawings and examples. It is to be understood that the specific embodiments described herein are merely illustrative of the invention and are not limiting thereof. It should be further noted that, for convenience of description, only some, but not all of the structures related to the present invention are shown in the drawings.
Example 1
Fig. 1 is a flowchart of a line impedance measurement method provided in a first embodiment of the present invention, where the present embodiment is applicable to a situation that when a traditional non-interference method is used to perform line impedance measurement calculation, sampling moments of node devices are not synchronized due to a plurality of node devices in a transformer area, so that impedance calculation of a line is inaccurate, the method may be applied to a concentrator, a modularized terminal, and a slave device in the same transformer area, where the concentrator is located on an incoming line side of a transformer, the modularized terminal is located on an outgoing line side of the transformer, and the slave device includes a branch switch box and a meter box, and specifically includes the following steps:
In this embodiment, the whole low-voltage distribution transformer area to which the transformer belongs is hierarchically divided according to a 4-layer structure of a 'transformer-line-table-household'. The "transformer" is the part of the transformer from the low voltage outlet side to the line, which part includes equipment with concentrators. The part from the total outgoing line switch of the transformer to the branch box comprises the outgoing line switch, the branch line, the branch switch and the part from the outgoing line switch to the branch box, and the layer can be divided into one layer or two layers according to the existence of the outgoing line switch. The meter, namely the part of the line from the branch box to the user load meter box, comprises a user load meter box and a meter box outgoing line; the household is a household inlet wire, a household ammeter and a household switch of each household. The devices in the middle layer, the table box layer, are summarized as slave devices in their entirety. In this embodiment, the concentrator, the modularized terminal and the slave terminal are all configured with GPS (Global Positioning System ) receivers for receiving GPS satellite signals. Specifically, the concentrator further comprises a communication main node, and in the running process of the system, the concentrator sends a first measurement sampling instruction to the modularized terminal through the communication main node when a preset sampling period arrives or according to an artificial instruction, wherein the first measurement sampling instruction is used for indicating the modularized terminal to determine the sampling moment.
In one embodiment of the present invention, the concentrator, the modularized terminal and the slave device can perform time synchronization according to the configured GPS receiver, which is specifically expressed as follows:
the concentrator receives a first satellite signal of the global positioning system, the first satellite signal is used for carrying out first time synchronization calibration on the concentrator, the modularized terminal receives a second satellite signal of the global positioning system, the second satellite signal is used for carrying out second time synchronization calibration on the modularized terminal, the slave terminal receives a third satellite signal of the global positioning system, and the third satellite signal is used for carrying out third time synchronization calibration on the slave terminal. In this embodiment, since the GPS satellite is equipped with the high-precision atomic clock, the reference signal and the time standard can be generated, and the service with a large range to the world can be provided, the embodiment uses the GPS time synchronization method to perform time synchronization for the concentrator, the modularized terminal and the slave device, for example, when the GPS receiver configured on the concentrator receives the GPS satellite signal, a pulse is output every second, and the embodiment can set the time of the rising edge of the pulse to perform clock synchronization calibration for the concentrator, and the clock calibration process of the modularized terminal and the slave device is the same as that of the concentrator, so that the clocks of the respective devices are kept in high-precision synchronization.
In one embodiment of the present invention, to implement computation of the impedance between lines, the concentrator will collect operation data to the slave devices in the lines, and the plurality of slave devices and the concentrator form a topology network, where each slave device has a unique terminal identifier, and the topology network is obtained as follows:
after the first measurement sampling instruction is sent to the modularized terminal, the modularized terminal sends a topology identification instruction to the slave terminal equipment. After receiving the topology identification instruction, the slave terminal equipment inquires equipment information of the slave terminal equipment in response to the topology identification instruction, encapsulates the equipment information of the slave terminal equipment into a topology identification signal, and sends the topology identification signal to a line where the slave terminal equipment is located so as to send the topology identification signal to other slave terminal equipment or modularized terminals located on the line. In this embodiment, since the number of slave devices in the line and the condition of being intact or damaged are dynamically changed, each time the impedance calculation of the line is measured, that is, the topology identification of the slave devices is performed once, and when the slave devices receive the topology identification instruction, a topology identification signal is generated. And encapsulating the device information of the slave terminal device into the topology identification signal, and then injecting the topology identification signal into a line where the slave terminal device is located. The modulation results in a topology identification signal, and the feature code specification can be derived from industry related specifications. When the topology identification signal enters the line, the slave terminal equipment at the upper level of the slave terminal equipment generating the topology identification signal can monitor the topology identification signal through a demodulation algorithm, when monitoring is successful, namely the upper and lower level relations of different slave terminal equipment are confirmed, at the moment, the slave terminal equipment serving as the upper level also packages the equipment information of the slave terminal equipment into the topology identification signal, and continues to send the equipment information into the line where the slave terminal equipment at the upper level is located until the modularized terminal receives the topology identification signal, and the upper and lower level relations and the equipment information of all the slave terminal equipment are obtained from the topology identification signal.
The modularized terminal reads the equipment information of all the slave terminal equipment from the topology identification signal, and builds a topology network diagram by using the equipment information.
In this embodiment, when the device information of all the slave devices can be read from the topology signal received by the modular terminal, the modular terminal can generate a topology network representing the upper-lower relationship between the slave devices according to the device information, and numbers each slave device in the topology network as a terminal identifier of the slave device in the topology network. The topology network generated in this embodiment includes, as shown in fig. 2, a transformer 210, a concentrator 220, a modularized terminal 230, a slave device 240, and a monitoring apparatus 250 for monitoring the slave device 240.
In this embodiment, after receiving the first measurement instruction, the modularized terminal selects the time when the slave device starts to sample as the first sampling time, and the modularized terminal may determine the first sampling time according to the time when the first measurement instruction is received, or may determine the first sampling time according to human input after receiving the first measurement instruction, and return the first sampling time to the concentrator.
In this embodiment, after receiving the first sampling time determined by the modularized terminal, the concentrator sends a second sampling instruction to the slave devices located in the preselected measurement line, where different slave devices have multiple different lines, and for the preselected measurement line to be measured in impedance, the current value and the voltage value at the slave devices can be acquired by searching the slave devices at two ends of the line in the topology network, so as to acquire the impedance value of the line between the slave devices. In this embodiment, when the concentrator sends the second measurement sampling instruction to the slave device through the communication master node, the first sampling time may be further embedded in the instruction, for example, when the communication master node sends the second measurement sampling instruction in the format of a central beacon, a 32-bit beacon timestamp may be embedded in frame control of a beacon frame, where the beacon timestamp is generated according to the determined first sampling time.
In one embodiment of the present invention, the concentrator, when sending the second measurement sampling instruction, is embodied as:
The method comprises the steps that a topological network diagram is inquired for a modularized terminal, a concentrator inquires for the modularized terminal aiming at a measuring line of impedance to be calculated, the modularized terminal receives a first measuring sampling instruction corresponding to the second measuring sampling instruction and then generates the topological network diagram, and a slave terminal device in the topological network diagram has a unique terminal identifier.
. The concentrator then looks up the terminal identification of the slave device located in the preselected measurement line in the topology network map, and the concentrator can send a second measurement sampling instruction to the slave device in the measurement line according to the terminal identification. Furthermore, the concentrator can also package the first sampling time into the second sampling instruction, so that the slave device receiving the second measurement sampling instruction can sample at the first sampling time. And finally, the concentrator transmits a second measurement sampling instruction to the slave terminal equipment indicated by the terminal identification.
And 104, responding to the second measurement sampling instruction by the slave terminal equipment, respectively sampling the electric power data of the current and the voltage at the first sampling moment as sampling data, and uploading the sampling data to the modularized terminal.
In this embodiment, after receiving the second measurement sampling instruction, the slave device analyzes the second measurement sampling instruction to obtain a first sampling time, and then samples the current and the voltage at the slave device at the first sampling time to obtain power data such as a current value of the slave device and a voltage value of the slave device, and uploads the power data as sampling data to the modularized terminal.
In one embodiment of the present invention, the process of the slave device responding to the second measurement sampling instruction is embodied as:
and reading the first sampling moment in the second measurement sampling instruction, and after the concentrator sends the second measurement to the corresponding slave terminal equipment according to the terminal identification, the slave terminal equipment can analyze the second measurement sampling instruction, including analyzing to obtain the first sampling moment.
In this embodiment, the slave device may start sampling at the rising edge of the second pulse at the first sampling time according to the received gps satellite signal, and continue for two cycles to obtain the original sampled data, where the original sampled data includes the current value and the voltage value at the slave device. In this embodiment, a monitoring device may be configured at each slave device to monitor the current and the voltage at the slave device, and a GPS receiver may be further configured to configure the monitoring device to enable the monitoring device of the slave device to start sampling at the first sampling time according to the received satellite signal of the global positioning system under the condition of obtaining the first sampling time, where in this embodiment, the sampling may be further set to start at the rising edge of the second pulse at the first sampling time, and in order to ensure that the zero crossing point data for calculating the measured line impedance is acquired, the sampling may be further set to continuously sample two cycles from the rising edge of the second pulse at the first sampling time. And then taking the current value and the voltage value at the slave end equipment in the two cycles obtained by sampling as original sampling data, and further effectively calculating the impedance value of the measuring line, wherein the slave end equipment can also screen the current value and the voltage value of the zero crossing point from the original sampling data to be taken as the sampling data.
In one embodiment of the present invention, after obtaining the sampled data from the terminal device, the sampled data is not directly uploaded to the modular terminal, and the process of obtaining the sampled data by the modular terminal is specifically:
after the sampling of the slave device is finished, the modularized terminal sends a sampling data reading signal to the concentrator, in this embodiment, the modularized terminal may preset a sampling end time, for example, estimate the time spent by sampling the slave device after determining the first sampling time, add the time spent by sampling to the first sampling time to obtain the preset sampling end time, and when the modularized terminal reaches the sampling end time, send the sampling data reading signal to the concentrator, so that the concentrator communicates with the slave device to inform the transmission of the sampling data to the modularized terminal.
The concentrator forwards the sampled data reading signal to the slave device positioned on the measuring line, and in the embodiment, the concentrator forwards the data reading instruction to the slave device indicated by the terminal identifier according to the terminal identifier of the slave device obtained before after receiving the sampled data reading signal. And after receiving the sampled data reading signal, the slave terminal equipment uploads the sampled data to the modularized terminal. In this embodiment, the slave device uploads the collected sample data to the modularized terminal after receiving the sample data reading signal.
In this embodiment, the modularized terminal may calculate the impedance of the measurement line including the slave device according to the sampling data after obtaining the sampling data, that is, the current value and the voltage value at the slave device.
In one embodiment of the invention, the impedance calculation of the measurement line is embodied as:
the modular terminal extracts a first three-relative neutral fundamental voltage phasor value, a four-wire fundamental current phasor value and a second three-relative neutral fundamental voltage phasor value at the tail end of the measuring line from the sampling data. In this embodiment, the measurement line may be a section of line located in a three-phase four-wire low-voltage distribution network, and the ac power produced, delivered and distributed by the current power plant and the power grid is three-phase ac power. This is because three-phase alternating current has many advantages. In terms of power generation equipment, a three-phase alternator has a larger output power than a single-phase alternator of the same size; in terms of power transmission, the three-phase power supply system also saves materials compared with the single-phase power supply system; compared with a direct current motor and other types of alternating current motors, the three-phase alternating current motor widely used in production has the advantages of excellent performance, simple structure, low price and the like from the aspect of electricity utilization. The principle of the three-phase alternating current generator is as follows: inside the generator there is a rotor (rotating magnetic field) driven by the engine. There is a sub-winding outside the magnetic field, the winding has 3 groups of coils (three-phase windings), the three-phase windings are separated from each other by 120 electrical degrees. When the rotor rotates, the rotating magnetic field causes the fixed stator winding to cut magnetic force lines (or causes the magnetic flux passing through the electromotive force winding to change) so as to generate electromotive force, and the magnitude of the electromotive force generated by the electromotive coil is proportional to the intensity of the coil flux and the rotating speed of the magnetic poles. The three-phase alternating currents with the same voltage and the same frequency and 120 degrees of mutual difference can be obtained by configuring 3 groups of coils at 120 degrees.
In the embodiment, when the measuring circuit is positioned in the three-phase four-wire low-voltage distribution network, the voltage is low by 0.4kVThe voltage distribution network has short line distance (rural requirement is not more than 500m, urban requirement is not more than 250 m) and low voltage, and the shunt of fundamental wave capacitance to ground and interphase capacitance is small, so that the influence is not great, and therefore, the capacitance branch is ignored. Assuming that the impedance parameters of the three-phase line of each section of line ABC are symmetrical, the embodiment can realize measurement sampling of the segmented branches, for example, the monitoring device can obtain the fundamental voltage value and the current value of each phase sequence of different slave devices by monitoring the slave devices positioned at the head end of the measurement line and the slave devices positioned at the tail end of the measurement line, thereby obtaining the fundamental voltage phase value (U Ai 、U Bi 、U Ci )，U Ai Representing the voltage value of the slave device positioned at the head end of the measuring line at the A phase line in three phase lines, U Bi Representing the voltage value of the slave device at the head end of the measuring line at the B phase line in the three phase lines, U Ci Representing the voltage value of the slave device at the head end of the measuring line at the C-phase line of the three-phase lines, and the second three-phase-to-neutral-line fundamental voltage phase value (U A(i+1) 、U B(i+1) 、U C(i+1) )，U A(i+1) Representing the voltage value at A phase line in three phase lines of slave end equipment at the end of measuring line, U B(i+1) Representing the voltage value at the B-phase line of the three-phase line of the slave device at the end of the measuring line, U C(i+1) Representing the voltage value at the C-phase line of the three-phase line of the slave located at the end of the measuring line, the phasor value of the four-wire fundamental current of the measuring line (I Ai 、I Bi 、I Ci 、I Ni )，I Ai Indicating the current value of the measuring line at the A phase line, I Bi Indicating the current value of the measuring line at the B phase line, I Ci Indicating the current value of the measuring line at the C phase line, I Ni The current value of the measuring line at the N-phase line, i.e. the neutral line, is indicated. And the active value and the reactive value of each phase sequence, and then carrying out impedance calculation of the interval line, wherein the specific steps are as follows:
the modular terminal decomposes the positive sequence component, the negative sequence component and the zero sequence component of the first three-phase neutral line fundamental wave voltage phasor value, the four-wire fundamental wave current phasor value and the second three-phase neutral line fundamental wave voltage phasor value, and the decomposition formula in the embodiment can be:
The modular terminal takes the positive sequence component and the zero sequence component of the first three-phase neutral line fundamental voltage phasor value as the first voltage positive sequence component and the first voltage zero sequence component respectively, and for the convenience of calculation and simplicity of naming, the positive sequence component and the zero sequence component of the first three-phase neutral line fundamental voltage phasor value are taken as the first voltage positive sequence component and the first voltage zero sequence component respectively in the embodiment.
The modular terminal takes the positive sequence component and the zero sequence component of the four-wire fundamental wave current phasor value as the first current positive sequence component and the first current zero sequence component respectively, and can also take the positive sequence component and the zero sequence component of the second three-phase neutral line fundamental wave voltage phasor value as the second voltage positive sequence component and the second voltage zero sequence component respectively, and the renaming reason is the same as the above.
The modularized terminal calculates the phase line impedance of the measuring circuit through the first voltage positive sequence component, the first current positive sequence component and the second voltage positive sequence component. The positive sequence equivalent circuit diagram of the measurement circuit in this embodiment may be represented as fig. 3, and the phase line impedance 310 is calculated as follows:
firstly, calculating the positive sequence complex power of a measuring line, wherein the calculation formula is as follows:
The positive sequence complex power calculation formula of the measurement line can also be expressed as:
It will be appreciated from the foregoing that,
the modular terminal can obtain the phase impedance of the measurement line based on the sampled data.
The modularized terminal calculates zero line impedance of the measuring circuit through the first voltage zero sequence component, the first current zero sequence component and the second voltage zero sequence component. In this embodiment, the zero sequence equivalent circuit diagram of the measurement circuit is shown in fig. 4, fig. 4 includes 3 times zero line impedance 410, phase line impedance 420, and the calculation method of the zero line impedance is as follows:
firstly, calculating zero sequence complex power of the head end of a measuring line, wherein the formula is as follows:
The zero sequence complex power calculation formula of the measurement line can also be expressed as:
In one embodiment of the present invention, since the calculated impedance may also be calibrated to obtain a more accurate impedance value between the measurement lines, the calibration process is as follows:
the modular terminal obtains M times of sampling data for the measurement circuit, in this embodiment, the impedance of the same measurement circuit may be calculated by obtaining the sampling data multiple times, for example, M times of sampling data for the selected measurement circuit may be obtained, then the modular terminal may calculate M phase line impedances and/or zero line impedances according to the M times of sampling data, the phase line impedances and/or the zero line impedances may be substituted into the parameter estimation formula by the modular terminal, in this embodiment, the parameter estimation formula may be expressed as follows:
It should be noted that, for simplicity of description, the method embodiments are shown as a series of acts, but it should be understood by those skilled in the art that the embodiments are not limited by the order of acts, as some steps may occur in other orders or concurrently in accordance with the embodiments. Further, those skilled in the art will appreciate that the embodiments described in the specification are presently preferred embodiments, and that the acts are not necessarily required by the embodiments of the invention.
According to the embodiment of the invention, time calibration is uniformly carried out on all node equipment in a power distribution network line through a global positioning system, after a concentrator sends a first measurement sampling instruction to a modularized terminal according to a preset sampling period, the modularized terminal determines uniform sampling time and sends the uniform sampling time to the concentrator, the concentrator includes the determined uniform sampling time in a second measurement sampling instruction, and then the second measurement instruction is sent to each slave equipment positioned in a preselected measurement line, so that each slave equipment collects operation data at the same time as sampling data and uploads the sampling data to the modularized terminal, and the modularized terminal calculates the impedance value of the measurement line according to the sampling data. In the embodiment of the invention, the clock at each node device in the low-voltage distribution network is calibrated by using the time of the global positioning system, the unified sampling time is predetermined, the sampling time is obtained by analysis when the slave device receives the second measurement sampling instruction, and the operation data is collected when the determined sampling time arrives instead of starting to sample when the second measurement sampling instruction is received, so that the synchronization degree of the slave device in the sampling process is improved, the operation data of each slave device in the same cycle is ensured, the reliability of the sampling data for calculating the impedance is improved, and the accuracy of the calculated impedance is improved. In addition, the embodiment of the invention does not need to inject harmonic current into the line where the slave terminal equipment is located, so that the impedance calculation is not influenced by the frequency of the injected harmonic current, and the accuracy of the impedance calculation is ensured.
Example two
Fig. 5 is a schematic structural diagram of a line impedance measurement system according to a second embodiment of the present invention, which may specifically include the following modules:
the concentrator 510 is configured to send a first measurement sampling instruction to the modularized terminal 520 according to a preset measurement sampling period;
the modularized terminal 520 is configured to determine a first sampling time in response to the first measurement sampling instruction, and send the first sampling time to the concentrator 510;
the concentrator 510 is further configured to send a second measurement sampling instruction to a slave device located in a preselected measurement line, where the second measurement sampling instruction includes the first sampling time;
the slave device 530 is configured to respond to the second measurement sampling instruction, sample the current and voltage at the first sampling moment as sampling data, and upload the sampling data to the modularized terminal 520;
the modularized 520 terminal is further configured to calculate an impedance of the measurement line according to the sampled data.
In one embodiment of the present invention, the concentrator 510 is further configured to:
receiving a first satellite signal of the global satellite positioning system, wherein the first satellite signal is used for performing first time synchronization calibration on the concentrator 510;
The modular terminal 520 is further configured to receive a second satellite signal of the global positioning system, where the second satellite signal is used to perform a second time synchronization calibration on the modular terminal 520;
the slave device 530 is further configured to receive a third satellite signal of the global positioning system, where the third satellite signal is used to perform a third time synchronization calibration on the slave device 530.
In one embodiment of the present invention, the modular terminal 520 is further configured to:
transmitting a topology identification instruction to the slave device 530;
in response to the topology identification instruction, the slave device 530 is further configured to query device information of the slave device 530, encapsulate the device information of the slave device 530 into a topology identification signal, and send the topology identification signal to a line where the slave device 530 is located, so as to send the topology identification signal to other slave devices 530 or the modularized terminals 520 located on the line;
the modularized terminal 520 reads the device information of all the slave devices 530 from the topology identification signal, and constructs a topology network graph using the device information.
In one embodiment of the present invention, the concentrator 510 is further configured to:
Querying the modular terminal for the topology network map，The slave terminal equipment in the topological network diagram has a unique terminal identifier;
looking up the terminal identity of the slave device 530 located in a preselected measurement line in the topology network map;
packaging the first sampling moment into a second sampling instruction;
and sending the second measurement sampling instruction to the slave device 530 indicated by the terminal identification.
In one embodiment of the present invention, the slave end device 530 is further configured to:
reading the first sampling moment in the second measurement sampling instruction;
starting sampling at the second pulse rising edge of the first sampling moment according to the received GPS satellite signal, and continuing for two cycles to obtain original sampling data, wherein the original sampling data comprises a current value and a voltage value at the slave terminal equipment 530;
and screening the current value and the voltage value of the zero crossing point from the original sampling data as sampling data.
In one embodiment of the present invention, the modular terminal 520 is further configured to:
after the slave device 530 finishes sampling, sending a sampled data reading signal to the concentrator 510;
The concentrator 510 is further configured to forward the sampled data read signal to the slave device 530 located on the measurement line;
the slave device 530 is further configured to upload the sampled data to the modularized terminal 520 after receiving the sampled data read signal.
In one embodiment of the present invention, the modular terminal 520 is further configured to:
extracting a first three-relative neutral fundamental voltage phasor value, a four-wire fundamental current phasor value and a second three-relative neutral fundamental voltage phasor value at the tail end of the measuring line from the sampling data;
decomposing positive sequence components, negative sequence components and zero sequence components of the first three-phase neutral line fundamental wave voltage phasor value, the four-wire fundamental wave current phasor value and the second three-phase neutral line fundamental wave voltage phasor value;
the positive sequence component and the zero sequence component of the first three relative neutral line fundamental voltage phasor value are respectively used as a first voltage positive sequence component and a first voltage zero sequence component;
the positive sequence component and the zero sequence component of the four-wire fundamental wave current phasor value are respectively used as a first current positive sequence component and a first current zero sequence component;
The positive sequence component and the zero sequence component of the fundamental voltage phasor value of the second three relative neutral wires are respectively used as a second voltage positive sequence component and a second voltage zero sequence component;
calculating the phase line impedance of the measuring circuit through the first voltage positive sequence component, the first current positive sequence component and the second voltage positive sequence component;
and calculating zero line impedance of the measurement circuit through the first voltage zero sequence component, the first current zero sequence component and the second voltage zero sequence component.
In one embodiment of the invention, the modular terminal is further configured to:
obtaining M times of sampling data for the measuring circuit;
calculating M phase line impedance and/or zero line impedance according to the M times of sampling data;
substituting the phase line impedance and/or the zero line impedance into a parameter estimation formula, wherein the parameter estimation formula is used for obtaining a calibration phase line impedance and/or a calibration zero line impedance according to the phase line impedance and/or the zero line impedance.
The line impedance measuring device provided by the embodiment of the invention can execute the line impedance measuring method provided by any embodiment of the invention, and has the corresponding functional modules and beneficial effects of the executing method.
Example III
Fig. 6 is a schematic structural diagram of a computer device according to a third embodiment of the present invention. FIG. 6 illustrates a block diagram of an exemplary computer device 12 suitable for use in implementing embodiments of the present invention. The computer device 12 shown in fig. 6 is merely an example and should not be construed as limiting the functionality and scope of use of embodiments of the present invention.
As shown in FIG. 6, the computer device 12 is in the form of a general purpose computing device. Components of computer device 12 may include, but are not limited to: one or more processors or processing units 16, a system memory 28, a bus 18 that connects the various system components, including the system memory 28 and the processing units 16.
The system memory 28 may include computer system readable media in the form of volatile memory, such as Random Access Memory (RAM) 30 and/or cache memory 32. The computer device 12 may further include other removable/non-removable, volatile/nonvolatile computer system storage media. By way of example only, storage system 34 may be used to read from or write to non-removable, nonvolatile magnetic media (not shown in FIG. 6, commonly referred to as a "hard disk drive"). Although not shown in fig. 6, a magnetic disk drive for reading from and writing to a removable non-volatile magnetic disk (e.g., a "floppy disk"), and an optical disk drive for reading from or writing to a removable non-volatile optical disk (e.g., a CD-ROM, DVD-ROM, or other optical media) may be provided. In such cases, each drive may be coupled to bus 18 through one or more data medium interfaces. Memory 28 may include at least one program product having a set (e.g., at least one) of program modules configured to carry out the functions of embodiments of the invention.
A program/utility 40 having a set (at least one) of program modules 42 may be stored in, for example, memory 28, such program modules 42 including, but not limited to, an operating system, one or more application programs, other program modules, and program data, each or some combination of which may include an implementation of a network environment. Program modules 42 generally perform the functions and/or methods of the embodiments described herein.
The computer device 12 may also communicate with one or more external devices 14 (e.g., keyboard, pointing device, display 24, etc.), one or more devices that enable a user to interact with the computer device 12, and/or any devices (e.g., network card, modem, etc.) that enable the computer device 12 to communicate with one or more other computing devices. Such communication may occur through an input/output (I/O) interface 22. Moreover, computer device 12 may also communicate with one or more networks such as a Local Area Network (LAN), a Wide Area Network (WAN) and/or a public network, such as the Internet, through network adapter 20. As shown, network adapter 20 communicates with other modules of computer device 12 via bus 18. It should be appreciated that although not shown, other hardware and/or software modules may be used in connection with computer device 12, including, but not limited to: microcode, device drivers, redundant processing units, external disk drive arrays, RAID systems, tape drives, data backup storage systems, and the like.
The processing unit 16 executes various functional applications and data processing by running programs stored in the system memory 28, for example, implementing the line impedance measuring method provided by the embodiment of the present invention.
Example IV
The fourth embodiment of the present invention further provides a computer readable storage medium, on which a computer program is stored, where the computer program when executed by a processor implements each process of the line impedance measurement method described above, and the same technical effects can be achieved, so that repetition is avoided, and no further description is given here.
The computer readable storage medium may include, for example, but is not limited to, an electronic, magnetic, optical, electromagnetic, infrared, or semiconductor system, apparatus, or device, or a combination of any of the foregoing. More specific examples (a non-exhaustive list) of the computer-readable storage medium would include the following: an electrical connection having one or more wires, a portable computer diskette, a hard disk, a Random Access Memory (RAM), a read-only memory (ROM), an erasable programmable read-only memory (EPROM or flash memory), an optical fiber, a portable compact disc read-only memory (CD-ROM), an optical storage device, a magnetic storage device, or any suitable combination of the foregoing. In this document, a computer readable storage medium may be any tangible medium that can contain, or store a program for use by or in connection with an instruction execution system, apparatus, or device.
Note that the above is only a preferred embodiment of the present invention and the technical principle applied. It will be understood by those skilled in the art that the present invention is not limited to the particular embodiments described herein, but is capable of various obvious changes, rearrangements and substitutions as will now become apparent to those skilled in the art without departing from the scope of the invention. Therefore, while the invention has been described in connection with the above embodiments, the invention is not limited to the embodiments, but may be embodied in many other equivalent forms without departing from the spirit or scope of the invention, which is set forth in the following claims.
Claims (10)
1. A line impedance measurement method, characterized by being applied to a concentrator, a modularized terminal and a slave device in a transformer area of the same transformer, wherein the concentrator is located on an incoming line side of the transformer, the modularized terminal is located on an outgoing line side of the transformer, and the slave device comprises a branch switch box and a meter box, and the method comprises:
the concentrator sends a first measurement sampling instruction to the modularized terminal according to a preset measurement sampling period;
the modularized terminal responds to the first measurement sampling instruction, determines a first sampling moment and sends the first sampling moment to the concentrator;
The concentrator transmits a second measurement sampling instruction to slave end equipment positioned in a preselected measurement line, wherein the second measurement sampling instruction comprises the first sampling moment;
the slave terminal equipment responds to the second measurement sampling instruction, samples electric power data of current and voltage at the first sampling moment to serve as sampling data, and uploads the sampling data to the modularized terminal;
and the modularized terminal calculates the impedance of the measuring line according to the sampling data.
2. The method as recited in claim 1, further comprising:
the concentrator receives a first satellite signal of a global satellite positioning system, wherein the first satellite signal is used for carrying out first time synchronization calibration on the concentrator;
the modularized terminal receives a second satellite signal of the global positioning system, wherein the second satellite signal is used for carrying out second time synchronization calibration on the modularized terminal;
the slave terminal equipment receives a third satellite signal of the global positioning system, wherein the third satellite signal is used for carrying out third time synchronization calibration on the slave terminal equipment.
3. The method of claim 1, further comprising, after said sending said first measurement sampling instruction to a modular terminal:
The modularized terminal sends a topology identification instruction to the slave terminal equipment;
responding to the topology identification instruction, the slave terminal equipment inquires equipment information of the slave terminal equipment, packages the equipment information of the slave terminal equipment into a topology identification signal, and sends the topology identification signal to a line where the slave terminal equipment is located so as to send the topology identification signal to other slave terminal equipment or the modularized terminal located on the line;
and the modularized terminal reads the equipment information of all the slave equipment from the topology identification signal and constructs a topology network diagram by using the equipment information.
4. The method of claim 1, wherein the concentrator transmits a second measurement sampling instruction to a slave device located in a preselected measurement line, comprising:
inquiring a topological network diagram from the modularized terminal, wherein a slave terminal device in the topological network diagram has a unique terminal identifier;
searching the topological network diagram for the terminal identification of the slave terminal equipment positioned in a preselected measuring line;
packaging the first sampling moment into a second sampling instruction;
and sending the second measurement sampling instruction to the slave terminal equipment indicated by the terminal identification.
5. The method according to claim 1, wherein after the slave device receives the second measurement sampling instruction, sampling the current and the voltage at the first sampling time as sampling data, respectively, includes:
reading the first sampling moment in the second measurement sampling instruction;
starting sampling at the second pulse rising edge of the first sampling moment according to the received GPS satellite signal, and continuing for two cycles to obtain original sampling data, wherein the original sampling data comprises a current value and a voltage value at the slave terminal equipment;
and screening the current value and the voltage value of the zero crossing point from the original sampling data as sampling data.
6. The method according to any one of claims 1-5, wherein the slave device, in response to the second measurement sampling instruction, samples the current and voltage power data as sampling data at the first sampling time, and uploads the sampling data to the modularized terminal, respectively, including:
after the end of the sampling of the slave terminal equipment, the modularized terminal sends a sampling data reading signal to the concentrator;
the concentrator forwards the sampled data reading signal to the slave end equipment positioned on the measuring line;
And the slave terminal equipment uploads the sampling data to the modularized terminal after receiving the sampling data reading signal.
7. The method according to any one of claims 1-5, wherein the modular terminal calculating the impedance of the measurement line from the sampled data comprises:
extracting a first three-relative neutral fundamental voltage phasor value, a four-wire fundamental current phasor value and a second three-relative neutral fundamental voltage phasor value at the tail end of the measuring line from the sampling data;
decomposing positive sequence components, negative sequence components and zero sequence components of the first three-phase neutral line fundamental wave voltage phasor value, the four-wire fundamental wave current phasor value and the second three-phase neutral line fundamental wave voltage phasor value;
the positive sequence component and the zero sequence component of the first three relative neutral line fundamental voltage phasor value are respectively used as a first voltage positive sequence component and a first voltage zero sequence component;
the positive sequence component and the zero sequence component of the four-wire fundamental wave current phasor value are respectively used as a first current positive sequence component and a first current zero sequence component;
the positive sequence component and the zero sequence component of the fundamental voltage phasor value of the second three relative neutral wires are respectively used as a second voltage positive sequence component and a second voltage zero sequence component;
Calculating the phase line impedance of the measuring line through the first voltage positive sequence component, the first current positive sequence component and the second voltage positive sequence component;
and calculating zero line impedance of the measurement line through the first voltage zero sequence component, the first current zero sequence component and the second voltage zero sequence component.
8. The method of any of claims 1-5, wherein the modular terminal calculates an impedance of the measurement line from the sampled data, further comprising:
obtaining M times of sampling data for the measuring circuit;
calculating M phase line impedance and/or zero line impedance according to the M times of sampling data;
substituting the phase line impedance and/or the zero line impedance into a parameter estimation formula, wherein the parameter estimation formula is used for obtaining a calibration phase line impedance and/or a calibration zero line impedance according to the phase line impedance and/or the zero line impedance.
9. A computer device, the computer device comprising:
one or more processors;
a memory for storing one or more programs,
the one or more programs, when executed by the one or more processors, cause the one or more processors to implement the method of line impedance measurement of any of claims 1-8.
10. A computer readable storage medium, characterized in that the computer readable storage medium has stored thereon a computer program which, when executed by a processor, implements the line impedance measurement method according to any of claims 1-8.
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