CN113270944A - Low-voltage power distribution user side state evaluation method - Google Patents

Low-voltage power distribution user side state evaluation method Download PDF

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Publication number
CN113270944A
CN113270944A CN202110634665.8A CN202110634665A CN113270944A CN 113270944 A CN113270944 A CN 113270944A CN 202110634665 A CN202110634665 A CN 202110634665A CN 113270944 A CN113270944 A CN 113270944A
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voltage
low
user side
state
user
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赵辉
王飞行
戴小敏
邓建岗
王佩霞
徐保红
赵志海
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Tianshui Power Supply Co Of State Grid Gansu Electric Power Co
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Tianshui Power Supply Co Of State Grid Gansu Electric Power Co
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    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02J—CIRCUIT ARRANGEMENTS OR SYSTEMS FOR SUPPLYING OR DISTRIBUTING ELECTRIC POWER; SYSTEMS FOR STORING ELECTRIC ENERGY
    • H02J13/00—Circuit arrangements for providing remote indication of network conditions, e.g. an instantaneous record of the open or closed condition of each circuitbreaker in the network; Circuit arrangements for providing remote control of switching means in a power distribution network, e.g. switching in and out of current consumers by using a pulse code signal carried by the network
    • H02J13/00001—Circuit arrangements for providing remote indication of network conditions, e.g. an instantaneous record of the open or closed condition of each circuitbreaker in the network; Circuit arrangements for providing remote control of switching means in a power distribution network, e.g. switching in and out of current consumers by using a pulse code signal carried by the network characterised by the display of information or by user interaction, e.g. supervisory control and data acquisition systems [SCADA] or graphical user interfaces [GUI]
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
    • G01R31/00—Arrangements for testing electric properties; Arrangements for locating electric faults; Arrangements for electrical testing characterised by what is being tested not provided for elsewhere
    • G01R31/08—Locating faults in cables, transmission lines, or networks
    • G01R31/081—Locating faults in cables, transmission lines, or networks according to type of conductors
    • G01R31/086—Locating faults in cables, transmission lines, or networks according to type of conductors in power transmission or distribution networks, i.e. with interconnected conductors
    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02J—CIRCUIT ARRANGEMENTS OR SYSTEMS FOR SUPPLYING OR DISTRIBUTING ELECTRIC POWER; SYSTEMS FOR STORING ELECTRIC ENERGY
    • H02J13/00—Circuit arrangements for providing remote indication of network conditions, e.g. an instantaneous record of the open or closed condition of each circuitbreaker in the network; Circuit arrangements for providing remote control of switching means in a power distribution network, e.g. switching in and out of current consumers by using a pulse code signal carried by the network
    • H02J13/00002—Circuit arrangements for providing remote indication of network conditions, e.g. an instantaneous record of the open or closed condition of each circuitbreaker in the network; Circuit arrangements for providing remote control of switching means in a power distribution network, e.g. switching in and out of current consumers by using a pulse code signal carried by the network characterised by monitoring
    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02J—CIRCUIT ARRANGEMENTS OR SYSTEMS FOR SUPPLYING OR DISTRIBUTING ELECTRIC POWER; SYSTEMS FOR STORING ELECTRIC ENERGY
    • H02J13/00—Circuit arrangements for providing remote indication of network conditions, e.g. an instantaneous record of the open or closed condition of each circuitbreaker in the network; Circuit arrangements for providing remote control of switching means in a power distribution network, e.g. switching in and out of current consumers by using a pulse code signal carried by the network
    • H02J13/00006—Circuit arrangements for providing remote indication of network conditions, e.g. an instantaneous record of the open or closed condition of each circuitbreaker in the network; Circuit arrangements for providing remote control of switching means in a power distribution network, e.g. switching in and out of current consumers by using a pulse code signal carried by the network characterised by information or instructions transport means between the monitoring, controlling or managing units and monitored, controlled or operated power network element or electrical equipment
    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02J—CIRCUIT ARRANGEMENTS OR SYSTEMS FOR SUPPLYING OR DISTRIBUTING ELECTRIC POWER; SYSTEMS FOR STORING ELECTRIC ENERGY
    • H02J3/00—Circuit arrangements for ac mains or ac distribution networks
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02B—CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO BUILDINGS, e.g. HOUSING, HOUSE APPLIANCES OR RELATED END-USER APPLICATIONS
    • Y02B90/00—Enabling technologies or technologies with a potential or indirect contribution to GHG emissions mitigation
    • Y02B90/20—Smart grids as enabling technology in buildings sector
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
    • Y02E60/00—Enabling technologies; Technologies with a potential or indirect contribution to GHG emissions mitigation
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y04—INFORMATION OR COMMUNICATION TECHNOLOGIES HAVING AN IMPACT ON OTHER TECHNOLOGY AREAS
    • Y04S—SYSTEMS INTEGRATING TECHNOLOGIES RELATED TO POWER NETWORK OPERATION, COMMUNICATION OR INFORMATION TECHNOLOGIES FOR IMPROVING THE ELECTRICAL POWER GENERATION, TRANSMISSION, DISTRIBUTION, MANAGEMENT OR USAGE, i.e. SMART GRIDS
    • Y04S40/00—Systems for electrical power generation, transmission, distribution or end-user application management characterised by the use of communication or information technologies, or communication or information technology specific aspects supporting them
    • Y04S40/12—Systems for electrical power generation, transmission, distribution or end-user application management characterised by the use of communication or information technologies, or communication or information technology specific aspects supporting them characterised by data transport means between the monitoring, controlling or managing units and monitored, controlled or operated electrical equipment

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  • Engineering & Computer Science (AREA)
  • Power Engineering (AREA)
  • Human Computer Interaction (AREA)
  • Physics & Mathematics (AREA)
  • General Physics & Mathematics (AREA)
  • Remote Monitoring And Control Of Power-Distribution Networks (AREA)

Abstract

The invention discloses a low-voltage distribution user side state evaluation method which comprises the following steps of collecting voltage, current, active power and reactive power of a low-voltage distribution user side by a low-voltage user load and state sensing terminal connected to an A-phase live wire and a zero line of a low-voltage side of a distribution transformer; performing data modeling, generating loop impedance through the change rate of current and voltage according to voltage and current data acquired by the online monitoring terminal of the state of the low-voltage user side power supply loop, and evaluating and analyzing the running state of the low-voltage power distribution network through the change of the impedance of the low-voltage user side power supply loop; according to the method and the device, the state evaluation terminal of the low-voltage power distribution user side can be used for effectively monitoring the distribution network user side, so that active operation and maintenance are realized, and the power supply reliability is improved. The fault type is found and positioned in advance, on-site maintenance is arranged in time, equipment faults are reduced, and the working efficiency and the user satisfaction are improved.

Description

Low-voltage power distribution user side state evaluation method
Technical Field
The invention relates to the technical field of industrial controllers, in particular to a low-voltage power distribution user side state evaluation method based on a narrow-band Internet of things (NB-IoT).
Background
With the rapid development of distribution network loads, users have higher and higher requirements on power supply reliability. At present, a power supply company carries out low-voltage network fault processing on low-voltage side power supply loop state information mainly by depending on a '95598' customer service telephone which is called by a user after power failure and matching with systems such as distribution network automation, power failure management and the like. Meanwhile, the position of a fall fuse or a switch can be pre-judged only according to the description of a power failure user, the power failure scale, the personnel strength and the emergency repair plan are analyzed, the emergency repair priority is determined, the work strength required by the site is calculated, the recovery time is pre-estimated, and the site work is managed. The phenomena of incomplete fault judgment, untimely emergency repair, high working strength, high implementation cost and the like generally exist in fault treatment.
The prior art lacks the state information of the low-voltage side power supply loop which is rapidly, accurately and comprehensively collected, and the running state information of the low-voltage side power supply loop of the distribution network cannot be mastered in real time.
Disclosure of Invention
The invention aims to provide a low-voltage distribution user side state evaluation method, which comprises the steps of collecting voltage, current, active power and reactive power of a low-voltage distribution user side by a low-voltage user load and state sensing terminal connected to an A-phase live wire and a zero line of a low-voltage side of a distribution transformer;
a low-voltage distribution user side state evaluation method comprises the following steps:
(1) acquiring voltage, current, active power and reactive power of a low-voltage distribution user side by using a low-voltage user load and state sensing terminal connected to an A-phase live wire and a zero line on the low-voltage side of a distribution transformer;
low-voltage application for configuring low-voltage distribution networkThe household load and state sensing terminal comprises i state sensing terminals, and each state sensing terminal forms a loop with the distribution transformer through a live wire, a T connection circuit, a user load, a zero line and the I state sensing terminal; rSIncluding the equivalent impedance, R, of the distribution transformer for configuring the low-voltage distribution networkdiThe 2i-1 contact T of the adjacent user side of the phase A live wire2i-1At the 2i +1 th contact point T2i+1The equivalent impedance of the feeder line between the two phases, i is 1, 2, 3, …, n, n represents the number of access users of the A-phase live line user side (also the access number of the user-side smart meters), and R represents the number of access users of the A-phase live line user sideli2i-1 contacts T for A-phase live wire2i-1Equivalent impedance between the first state sensing terminal and the ith state sensing terminal; rziFor the 2 i-th access point T on the zero line2iEquivalent impedance between the first state sensing terminal and the ith state sensing terminal; rfiLeading out a zero line of a distribution transformer to the 2 i-th access point T of a user side2iThe low-voltage feeder line equivalent impedance; i iss、Idi、Ili、IziAnd IfiRespectively corresponding to the flow of each impedance RS、Rdi、Rli、Rzi、RfiThe current value of (a);
(2) carrying out data modeling:
establishing a real-time low-voltage distribution user side current value matrix MDRVMThe method comprises the following steps of recording real-time voltage measurement information collected by all low-voltage side intelligent electric meters to which the distribution transformers belong:
Figure BDA0003105025110000021
MDRVMrepresenting a low-voltage distribution user side voltage value matrix;
establishing a real-time low-voltage distribution user side current value matrix MDRCMThe method is characterized in that real-time current measurement information collected by all low-voltage side intelligent electric meters to which one distribution transformer belongs is recorded, and the specific description is as follows:
Figure BDA0003105025110000031
MDRCMrepresenting a low-voltage distribution user side current value matrix;
establishing a resistance value matrix M of a low-voltage distribution user side of a real-time loop of a demand sideDRRMRecording impedance information of all low-voltage side real-time loops to which one distribution transformer belongs, specifically describing as follows:
Figure BDA0003105025110000032
MDRRMrepresenting a low-voltage distribution user side resistance value matrix;
Figure BDA0003105025110000033
wherein, Vw,k+1Is the effective value of voltage of the (k + 1) th time of the w-th user, VwkFor the kth voltage effective value of the w user, Iw,k+1The effective value of current of the w user (k +1 times)wkFor the current effective value of the kth time of the w-th user, RwkThe calculated k-th power supply loop impedance;
(3) voltage and current data acquired by the online monitoring terminal for the state of the low-voltage user side power supply loop generate loop impedance through the change rate of current and voltage, and the running state of the low-voltage power distribution network is evaluated and analyzed through the change of the impedance of the low-voltage user side power supply loop;
when R iswkIn order to realize the purpose,
Figure BDA0003105025110000041
analyzing the state of a power supply loop at the power distribution user side according to the k-th power supply loop impedance;
when R iswkA value of-1 indicates that the user side has power failure;
when R iswkAnd 2, the user side does not turn on the electric equipment.
The circuit structure of the low-voltage user load and state perception terminal of the low-voltage distribution network is as follows:
equivalent impedance R of distribution transformerSAnd A phase live wire2i-1 th contact point T of adjacent user side2i-1Equivalent impedance R of the feed line therebetweendiSequentially connected in series, the ith state sensing terminal is connected with 2i-1 contact T of A-phase live wire2i-1Equivalent impedance R between the ith state sensing terminal and the ith state sensing terminalli2i access point T with zero line2iEquivalent impedance R between the ith state sensing terminal and the ith state sensing terminalziThe ith state sensing terminal is connected with the ith user load RziOne end of the power distribution transformer is connected with the ith state sensing terminal, and the other end of the power distribution transformer is connected with a zero line outgoing line of the power distribution transformer and a 2i access point T at the user side2iLow voltage feeder equivalent impedance Rfi。
The state perception terminal carries out information communication based on a cellular Narrow-Band Internet of Things (NB-IoT);
the NB-IoT is constructed in a cellular network, only consumes about 180KHz of bandwidth, and can be directly deployed in a GSM network, a UMTS network or an LTE network so as to reduce the deployment cost and realize smooth upgrading. NB-IoT is an emerging technology in the IoT domain that supports cellular data connectivity for low power devices over wide area networks, also known as low power wide area networks (LPWA). NB-IoT supports efficient connectivity for devices with long standby time and high requirements for network connectivity. The NB-IoT remote meter reading inherits the GPRS remote meter reading function and also has mass capacity, and the capacity of a communication user of the same base station is 10 times of that of the GPRS remote meter reading. Under the same use environment condition, the standby time of the NB-IoT module can be more than 10 years, the signal coverage of the new technology is stronger, and the new technology can cover indoor and basement.
When the state sensing terminal detects that the power supply is interrupted, the terminal transmits power failure alarm event information to a power failure management system in a narrowband Internet of things (NB-IoT) mode, power failure time of a user is shortened, active operation and maintenance of a transformer area are achieved, and power supply reliability is improved.
The working mode of the state sensing terminal comprises an instruction mode and a transparent transmission mode;
the instruction mode uses the 3GPP standard instruction set, and NB modules are universally compatible. The AT command is packaged to send data, and the polling AT command inquires received data. Supplementing Chinese and English; 3GPP Chinese name: the third generation partnership project; the foreign language name: 3rd Generation Partnership Project
NB-IoT, Narrow Band Internet of Things (IoT)
AT instruction, the AT instruction is an instruction applied to connection and communication between the terminal device and the PC application. AT is Attention.
Transparent data transmission is carried out in a transparent transmission mode, and AT instructions do not need to be operated, and what is sent by a serial port and what is received by a network terminal.
The state perception terminal adopts a real-time multitask embedded operating system;
the state sensing terminal comprises a sampling follower circuit, a signal sampling/holding circuit and an A/D conversion circuit; the sampling follower circuit independently samples the voltage, current and frequency parameters of the power grid, and the sampling follower circuit, the signal sampling/holding circuit and the A/D conversion circuit are sequentially connected.
The signal sampling/holding circuit comprises a synchronous sampling data acquisition unit and an analog signal memory; the synchronous sampling data acquisition unit is connected with the analog signal memory.
The beneficial effects of the invention include:
the invention discloses a low-voltage power distribution user side state evaluation method, which can effectively monitor a distribution network user side by using a low-voltage power distribution user side state evaluation terminal, thereby realizing active operation and maintenance and improving power supply reliability. The fault type is found and positioned in advance, on-site maintenance is arranged in time, equipment faults are reduced, and the working efficiency and the user satisfaction are improved.
The fault pre-judgment monitors the power supply state of a user, and timely identifies the increase of the line impedance, thereby greatly reducing the faults caused by the aging of circuits and equipment. The loop impedance measurements can be used for user potential wire breakage anticipation.
Drawings
In order to illustrate embodiments or prior art solutions of the present invention more clearly, the embodiments or prior art solutions are briefly described below by means of drawings, the drawings in the following description are only some embodiments of the present invention, and other drawings can be obtained by those skilled in the art without inventive effort.
FIG. 1 is a schematic diagram of a low voltage user load and status aware terminal configuration for a low voltage distribution network;
FIG. 2 is a schematic diagram of a sample follower circuit;
the technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the embodiments of the present invention, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. Other embodiments, which can be derived by one of ordinary skill in the art from the embodiments given herein without making any creative effort, are within the scope of the present invention.
Detailed Description
In order to make the objects, technical solutions and advantages of the present invention more apparent, embodiments of the present invention will be described in detail below with reference to the accompanying drawings.
While the embodiments of the present invention will be described and illustrated in detail with reference to the accompanying drawings, it is to be understood that the invention is not limited to the specific embodiments disclosed, but is intended to cover various modifications, equivalents, and alternatives falling within the scope of the invention as defined by the appended claims.
A low-voltage distribution user side state evaluation method comprises the following steps:
(1) acquiring voltage, current, active power and reactive power of a low-voltage distribution user side by using a low-voltage user load and state sensing terminal connected to an A-phase live wire and a zero line on the low-voltage side of a distribution transformer;
the low-voltage distribution user side state evaluation terminal is internally provided with a voltage signal acquisition unit and a current signal acquisition unit (the embodiment reads the data of the intelligent electric meter in an RS485 mode), the voltage signal acquisition unit is used for judging the power supply condition of the current loop, and the power failure and fault voltage threshold value is set in multiple intervals. The difficulty is that the wide-area low-voltage user side senses multiple points and processes mass data.
By researching the low-voltage power distribution user side power supply loop state evaluation technology and developing the terminal, the rapid, accurate and comprehensive power distribution station state information acquisition is realized, and the online measurement of the user side power supply loop state is realized. For the power failure alarm event, the terminal transmits the information to a power failure management system in a narrowband Internet of things (NB-IoT) mode, so that the power failure time of a user is shortened,
through the automatic deepening transformation of distribution network in recent years, a large amount of smart electric meters with remote meter reading function are widely applied to the low-voltage user side, and the voltage, the current and the power of the low-voltage user can be collected and transmitted in real time.
Configuring a low-voltage user load and a state sensing terminal of a low-voltage distribution network, wherein the low-voltage user load and state sensing terminal comprises i state sensing terminals, and each state sensing terminal forms a loop with a distribution transformer through a live wire, a T-connection circuit, a user load, a zero line; rSIncluding the equivalent impedance, R, of the distribution transformer for configuring the low-voltage distribution networkdiThe 2i-1 contact T of the adjacent user side of the phase A live wire2i-1At the 2i +1 th contact point T2i+1The equivalent impedance of the feeder line between the two phases, i is 1, 2, 3, …, n, n represents the number of access users of the A-phase live line user side (also the access number of the user-side smart meters), and R represents the number of access users of the A-phase live line user sideli2i-1 contacts T for A-phase live wire2i-1Equivalent impedance between the first state sensing terminal and the ith state sensing terminal; rziFor the 2 i-th access point T on the zero line2iEquivalent impedance between the state sensing terminal i and the impedance; rfiLeading out a zero line of a distribution transformer to the 2 i-th access point T of a user side2iThe low-voltage feeder line equivalent impedance; i iss、Idi、Ili、IziAnd IfiRespectively corresponding to the flow of each impedance RS、Rdi、Rli、Rzi、RfiThe current value of (a);
fig. 1 is a simplified diagram of a low-voltage distribution network showing low-voltage user load and status sensing terminals connected to the phase a live and neutral wires on the low-voltage side of a distribution transformer.
Gen is the upstream of the distribution transformerEquivalent power supply, RSFor equivalent impedance, R, of distribution transformersd1A phase A outgoing line of the distribution transformer is connected to a first contact T of a user side T1Equivalent impedance of the feed line, T1～TiThe method comprises the steps that a user side is connected to an access point of an A-phase live wire and a zero line through a state sensing terminal;
each state perception terminal forms a loop through a live wire, a zero line, a T-connection circuit, a load and a distribution transformer, the impedance of the load changes according to the number and power of electric equipment, but the loop impedance formed by the live wire, the zero line, the T-connection circuit and the distribution transformer at the upstream of the state perception terminal does not change in a short time, if the loop impedance changes suddenly, the operation state of the loop is abnormal, and the operation state of the low-voltage distribution network can be evaluated according to the principle. The loop impedance may be approximated by the rate of change of voltage and current measured at the state-sensing terminal.
(2) Performing data modeling
The data modeling is the whole process of explaining actual problems through the result obtained by calculation and accepting actual inspection to establish a data model. When a practical problem needs to be analyzed and researched from a quantitative point of view, a data model needs to be established by using mathematical symbols and languages as expressions on the basis of the work of deep investigation and research, object information understanding, simplified assumption making, internal rule analysis and the like.
Establishing a real-time voltage data array MDRVMThe method comprises the following steps of recording real-time voltage measurement information collected by all low-voltage side intelligent electric meters to which the distribution transformer belongs, wherein the specific description is as follows:
Figure BDA0003105025110000081
establishing a real-time current data array MDRCMThe method is characterized in that real-time current measurement information collected by all low-voltage side intelligent electric meters to which the distribution transformer belongs is recorded, and the specific description is as follows:
Figure BDA0003105025110000091
establishing a demand side real-time loop impedance data array MDRRMRecording impedance information of all low-voltage side real-time loops to which the distribution transformer belongs, specifically describing as follows:
Figure BDA0003105025110000092
wherein, Vw,k+1Is the effective value of voltage of the (k + 1) th time of the w-th user, VwkFor the kth voltage effective value of the w user, Iw,k+1The effective value of current of the w user (k +1 times)wkFor the current effective value of the kth time of the w-th user, RwkIs the calculated k-th power supply loop impedance.
Figure BDA0003105025110000093
The method comprises the steps that voltage and current data collected by a low-voltage user side power supply loop state online monitoring terminal generate loop impedance through the change rate of current and voltage, and the running state of a low-voltage power distribution network is evaluated and analyzed through the change of the low-voltage user side power supply loop impedance.
(3) Voltage and current data acquired by the online monitoring terminal for the state of the low-voltage user side power supply loop generate loop impedance through the change rate of current and voltage, and the running state of the low-voltage power distribution network is evaluated and analyzed through the change of the impedance of the low-voltage user side power supply loop;
when R iswkIn order to realize the purpose,
Figure BDA0003105025110000101
analyzing the state of a power supply loop at the power distribution user side according to the k-th power supply loop impedance; the power supply loop impedance result is used for potential line breakage prejudgment of a user. The threshold value of the disconnection criterion needs to consider resistance change, noise/error and aging rate under the normal operation condition, so that operation and maintenance personnel have enough processing time after sending out the warning signal and before the disconnection of the client power supply loop;
when R iswkA value of-1 indicates that the user side has power failure;
when R iswkAnd 2, the user side does not turn on the electric equipment.
The circuit structure of the low-voltage user load and state perception terminal of the low-voltage distribution network is as follows:
equivalent impedance R of distribution transformerSThe 2i-1 th contact T adjacent to the A phase live wire on the user side2i-1Equivalent impedance R of the feed line therebetweendiSequentially connected in series, the ith state sensing terminal is connected with 2i-1 contact T of A-phase live wire2i-1Equivalent impedance R between the ith state sensing terminal and the ith state sensing terminalli2i access point T with zero line2iEquivalent impedance R between the ith state sensing terminal and the ith state sensing terminalziThe ith state sensing terminal is connected with the ith user load RziOne end of the power distribution transformer is connected with the ith state sensing terminal, and the other end of the power distribution transformer is connected with a zero line outgoing line of the power distribution transformer and a 2i access point T at the user side2iLow voltage feeder equivalent impedance Rfi。
The state perception terminal carries out information communication based on a cellular Narrow-Band Internet of Things (NB-IoT);
the NB-IoT is constructed in a cellular network, only consumes about 180KHz of bandwidth, and can be directly deployed in a GSM network, a UMTS network or an LTE network so as to reduce the deployment cost and realize smooth upgrading. NB-IoT is an emerging technology in the IoT domain that supports cellular data connectivity for low power devices over wide area networks, also known as low power wide area networks (LPWA). NB-IoT supports efficient connectivity for devices with long standby time and high requirements for network connectivity. The NB-IoT remote meter reading inherits the GPRS remote meter reading function and also has mass capacity, and the capacity of a communication user of the same base station is 10 times of that of the GPRS remote meter reading. Under the same use environment condition, the standby time of the NB-IoT module can be more than 10 years, the signal coverage of the new technology is stronger, and the new technology can cover indoor and basement.
When the state sensing terminal detects that the power supply is interrupted, the terminal transmits power failure alarm event information to a power failure management system in a narrowband Internet of things (NB-IoT) mode, power failure time of a user is shortened, active operation and maintenance of a transformer area are achieved, and power supply reliability is improved.
The working mode of the state sensing terminal comprises an instruction mode and a transparent transmission mode;
the instruction mode uses the 3GPP standard instruction set, and NB modules are universally compatible. The AT command is packaged to send data, and the polling AT command inquires received data.
3GPP Chinese name: the third generation partnership project; the foreign language name: 3rd Generation partnershift project NB: NB-IoT, Narrow Band Internet of Things
AT instruction, the AT instruction is an instruction applied to connection and communication between the terminal device and the PC application. AT is Attention.
Transparent data transmission is carried out in a transparent transmission mode, and AT instructions do not need to be operated, and what is sent by a serial port and what is received by a network terminal.
The state perception terminal adopts a real-time multitask embedded operating system;
the state sensing terminal comprises a sampling follower circuit (shown in figure 2), a signal sampling/holding circuit and an A/D conversion circuit; the sampling follower circuit independently samples the voltage, current and frequency parameters of the power grid, and the sampling follower circuit, the signal sampling/holding circuit and the A/D conversion circuit are sequentially connected.
The signal sampling/holding circuit comprises a synchronous sampling data acquisition unit and an analog signal memory; the synchronous sampling data acquisition unit is connected with the analog signal memory.
In the description provided herein, numerous specific details are set forth. It is understood, however, that embodiments of the invention may be practiced without these specific details. In some instances, well-known methods, structures and techniques have not been shown in detail in order not to obscure an understanding of this description.
Similarly, it should be appreciated that in the foregoing description of exemplary embodiments of the invention, various features of the invention are sometimes grouped together in a single embodiment, figure, or description thereof for the purpose of streamlining the disclosure and aiding in the understanding of one or more of the various inventive aspects. However, the disclosed method should not be interpreted as reflecting an intention that: that the invention as claimed requires more features than are expressly recited in each claim. Rather, as the following claims reflect, inventive aspects lie in less than all features of a single foregoing disclosed embodiment. Thus, the claims following the detailed description are hereby expressly incorporated into this detailed description, with each claim standing on its own as a separate embodiment of this invention.
Those skilled in the art will appreciate that the modules or units or groups of devices in the examples disclosed herein may be arranged in a device as described in this embodiment, or alternatively may be located in one or more devices different from the devices in this example. The modules in the foregoing examples may be combined into one module or may be further divided into multiple sub-modules.
Those skilled in the art will appreciate that the modules in the device in an embodiment may be adaptively changed and disposed in one or more devices different from the embodiment. Modules or units or groups in embodiments may be combined into one module or unit or group and may furthermore be divided into sub-modules or sub-units or sub-groups. All of the features disclosed in this specification (including any accompanying claims, abstract and drawings), and all of the processes or elements of any method or apparatus so disclosed, may be combined in any combination, except combinations where at least some of such features and/or processes or elements are mutually exclusive. Each feature disclosed in this specification (including any accompanying claims, abstract and drawings) may be replaced by alternative features serving the same, equivalent or similar purpose, unless expressly stated otherwise.
Furthermore, those skilled in the art will appreciate that while some embodiments described herein include some features included in other embodiments, rather than other features, combinations of features of different embodiments are meant to be within the scope of the invention and form different embodiments. For example, in the following claims, any of the claimed embodiments may be used in any combination.
Furthermore, some of the described embodiments are described herein as a method or combination of method elements that can be performed by a processor of a computer system or by other means of performing the described functions. A processor having the necessary instructions for carrying out the method or method elements thus forms a means for carrying out the method or method elements. Further, the elements of the apparatus embodiments described herein are examples of the following apparatus: the apparatus is used to implement the functions performed by the elements for the purpose of carrying out the invention.
The various techniques described herein may be implemented in connection with hardware or software or, alternatively, with a combination of both. Thus, the methods and apparatus of the present invention, or certain aspects or portions thereof, may take the form of program code (i.e., instructions) embodied in tangible media, such as floppy diskettes, CD-ROMs, hard drives, or any other machine-readable storage medium, wherein, when the program is loaded into and executed by a machine, such as a computer, the machine becomes an apparatus for practicing the invention.
In the case of program code execution on programmable computers, the computing device will generally include a processor, a storage medium readable by the processor (including volatile and non-volatile memory and/or storage elements), at least one input device, and at least one output device. Wherein the memory is configured to store program code; the processor is configured to perform the method of the invention according to instructions in said program code stored in the memory.
By way of example, and not limitation, computer readable media may comprise computer storage media and communication media. Computer-readable media includes both computer storage media and communication media. Computer storage media store information such as computer readable instructions, data structures, program modules or other data. Communication media typically embodies computer readable instructions, data structures, program modules or other data in a modulated data signal such as a carrier wave or other transport mechanism and includes any information delivery media. Combinations of any of the above are also included within the scope of computer readable media.
As used herein, unless otherwise specified the use of the ordinal adjectives "first", "second", "third", etc., to describe a common object, merely indicate that different instances of like objects are being referred to, and are not intended to imply that the objects so described must be in a given sequence, either temporally, spatially, in ranking, or in any other manner.
While the invention has been described with respect to a limited number of embodiments, those skilled in the art, having benefit of this description, will appreciate that other embodiments can be devised which do not depart from the scope of the invention as described herein. Furthermore, it should be noted that the language used in the specification has been principally selected for readability and instructional purposes, and may not have been selected to delineate or circumscribe the inventive subject matter. Accordingly, many modifications and variations will be apparent to those of ordinary skill in the art without departing from the scope and spirit of the appended claims. The present invention has been disclosed in an illustrative rather than a restrictive sense, and the scope of the present invention is defined by the appended claims.
The above is only a preferred embodiment of the present invention, and it should be noted that: it will be apparent to those skilled in the art that various modifications and adaptations can be made without departing from the principles of the invention and these are intended to be within the scope of the invention.
In the description provided herein, numerous specific details are set forth. It is understood, however, that embodiments of the invention may be practiced without these specific details. In some instances, well-known methods, structures and techniques have not been shown in detail in order not to obscure an understanding of this description.
Similarly, it should be appreciated that in the foregoing description of exemplary embodiments of the invention, various features of the invention are sometimes grouped together in a single embodiment, figure, or description thereof for the purpose of streamlining the disclosure and aiding in the understanding of one or more of the various inventive aspects. However, the disclosed method should not be interpreted as reflecting an intention that: that the invention as claimed requires more features than are expressly recited in each claim. Rather, as the following claims reflect, inventive aspects lie in less than all features of a single foregoing disclosed embodiment. Thus, the claims following the detailed description are hereby expressly incorporated into this detailed description, with each claim standing on its own as a separate embodiment of this invention.
Those skilled in the art will appreciate that the modules or units or groups of devices in the examples disclosed herein may be arranged in a device as described in this embodiment, or alternatively may be located in one or more devices different from the devices in this example. The modules in the foregoing examples may be combined into one module or may be further divided into multiple sub-modules.
Those skilled in the art will appreciate that the modules in the device in an embodiment may be adaptively changed and disposed in one or more devices different from the embodiment. Modules or units or groups in embodiments may be combined into one module or unit or group and may furthermore be divided into sub-modules or sub-units or sub-groups. All of the features disclosed in this specification (including any accompanying claims, abstract and drawings), and all of the processes or elements of any method or apparatus so disclosed, may be combined in any combination, except combinations where at least some of such features and/or processes or elements are mutually exclusive. Each feature disclosed in this specification (including any accompanying claims, abstract and drawings) may be replaced by alternative features serving the same, equivalent or similar purpose, unless expressly stated otherwise.
Furthermore, those skilled in the art will appreciate that while some embodiments described herein include some features included in other embodiments, rather than other features, combinations of features of different embodiments are meant to be within the scope of the invention and form different embodiments. For example, in the following claims, any of the claimed embodiments may be used in any combination.
Furthermore, some of the described embodiments are described herein as a method or combination of method elements that can be performed by a processor of a computer system or by other means of performing the described functions. A processor having the necessary instructions for carrying out the method or method elements thus forms a means for carrying out the method or method elements. Further, the elements of the apparatus embodiments described herein are examples of the following apparatus: the apparatus is used to implement the functions performed by the elements for the purpose of carrying out the invention.
The various techniques described herein may be implemented in connection with hardware or software or, alternatively, with a combination of both. Thus, the methods and apparatus of the present invention, or certain aspects or portions thereof, may take the form of program code (i.e., instructions) embodied in tangible media, such as floppy diskettes, CD-ROMs, hard drives, or any other machine-readable storage medium, wherein, when the program is loaded into and executed by a machine, such as a computer, the machine becomes an apparatus for practicing the invention.
In the case of program code execution on programmable computers, the computing device will generally include a processor, a storage medium readable by the processor (including volatile and non-volatile memory and/or storage elements), at least one input device, and at least one output device. Wherein the memory is configured to store program code; the processor is configured to perform the method of the invention according to instructions in said program code stored in the memory.
By way of example, and not limitation, computer readable media may comprise computer storage media and communication media. Computer-readable media includes both computer storage media and communication media. Computer storage media store information such as computer readable instructions, data structures, program modules or other data. Communication media typically embodies computer readable instructions, data structures, program modules or other data in a modulated data signal such as a carrier wave or other transport mechanism and includes any information delivery media. Combinations of any of the above are also included within the scope of computer readable media.
As used herein, unless otherwise specified the use of the ordinal adjectives "first", "second", "third", etc., to describe a common object, merely indicate that different instances of like objects are being referred to, and are not intended to imply that the objects so described must be in a given sequence, either temporally, spatially, in ranking, or in any other manner.
While the invention has been described with respect to a limited number of embodiments, those skilled in the art, having benefit of this description, will appreciate that other embodiments can be devised which do not depart from the scope of the invention as described herein. Furthermore, it should be noted that the language used in the specification has been principally selected for readability and instructional purposes, and may not have been selected to delineate or circumscribe the inventive subject matter. Accordingly, many modifications and variations will be apparent to those of ordinary skill in the art without departing from the scope and spirit of the appended claims. The present invention has been disclosed in an illustrative rather than a restrictive sense, and the scope of the present invention is defined by the appended claims.
The above is only a preferred embodiment of the present invention, and it should be noted that: it will be apparent to those skilled in the art that various modifications and adaptations can be made without departing from the principles of the invention and these are intended to be within the scope of the invention.

Claims (6)

1. A low-voltage distribution user side state evaluation method is characterized by comprising the following steps:
(1) acquiring voltage, current, active power and reactive power of a low-voltage distribution user side by using a low-voltage user load and state sensing terminal connected to an A-phase live wire and a zero line on the low-voltage side of a distribution transformer;
(2) carrying out data modeling:
establishing a real-time low-voltage distribution user side current value matrixMDRVMRecording real-time voltage measurement information collected by all low-voltage side intelligent electric meters to which the distribution transformer belongs:
Figure FDA0003105025100000011
MDRVMrepresenting a low-voltage distribution user side voltage value matrix;
establishing a real-time low-voltage distribution user side current value matrix MDRCMRecording real-time current measurement information collected by all low-voltage side intelligent electric meters to which the distribution transformer belongs:
Figure FDA0003105025100000012
MDRCMrepresenting a low-voltage distribution user side current value matrix;
establishing a resistance value matrix M of a low-voltage distribution user side of a real-time loop of a demand sideDRRMRecording impedance information of all low-voltage side real-time loops to which the distribution transformer belongs:
Figure FDA0003105025100000021
MDRRMrepresenting a low-voltage distribution user side resistance value matrix;
Figure FDA0003105025100000022
wherein, Vw,k+1Is the effective value of voltage of the (k + 1) th time of the w-th user, VwkFor the kth voltage effective value of the w user, Iw,k+1The effective value of current of the w user (k +1 times)wkFor the current effective value of the kth time of the w-th user, RwkThe calculated k-th power supply loop impedance;
(3) voltage and current data acquired by the online monitoring terminal for the state of the low-voltage user side power supply loop generate loop impedance through the change rate of current and voltage, and the running state of the low-voltage power distribution network is evaluated and analyzed through the change of the impedance of the low-voltage user side power supply loop;
when R iswkIn order to realize the purpose,
Figure FDA0003105025100000023
analyzing the state of a power supply loop at the power distribution user side according to the k-th power supply loop impedance;
when R iswkA value of-1 indicates that the user side has power failure;
when R iswkAnd 2, the user side does not turn on the electric equipment.
2. The low-voltage distribution user side state evaluation method according to claim 1,
configuring a low-voltage user load and a state sensing terminal of a low-voltage distribution network, wherein the low-voltage user load and state sensing terminal comprises i state sensing terminals, and each state sensing terminal forms a loop with a distribution transformer through a live wire, a T-connection circuit, a user load, a zero line; rSIncluding the equivalent impedance, R, of the distribution transformer for configuring the low-voltage distribution networkdiThe 2i-1 contact T of the adjacent user side of the phase A live wire2i-1At the 2i +1 th contact point T2i+1The equivalent impedance of the feeder line between i is 1, 2, 3, …, n, n represents the number of user access of A phase live wire user side, and R represents the number of user access of A phase live wire user sideli2i-1 contacts T for A-phase live wire2i-1Equivalent impedance between the first state sensing terminal and the ith state sensing terminal; rziFor the 2 i-th access point T on the zero line2iEquivalent impedance between the first state sensing terminal and the ith state sensing terminal; rfiLeading out a zero line of a distribution transformer to the 2 i-th access point T of a user side2iThe low-voltage feeder line equivalent impedance; i iss、Idi、Ili、IziAnd IfiRespectively corresponding to the flow of each impedance RS、Rdi、Rli、Rzi、RfiThe current value of (1).
3. The low-voltage distribution user side state evaluation method according to claim 1,
the circuit structure of the low-voltage user load and state perception terminal of the low-voltage distribution network is as follows:
equivalent impedance R of distribution transformerSThe 2i-1 th contact T adjacent to the A phase live wire on the user side2i-1Equivalent impedance R of the feed line therebetweendiSequentially connected in series, the ith state sensing terminal is connected with 2i-1 contact T of A-phase live wire2i-1Equivalent impedance R between the ith state sensing terminal and the ith state sensing terminalli2i access point T with zero line2iEquivalent impedance R between the ith state sensing terminal and the ith state sensing terminalziThe ith state sensing terminal is connected with the ith user load RziOne end of the power distribution transformer is connected with the ith state sensing terminal, and the other end of the power distribution transformer is connected with a zero line outgoing line of the power distribution transformer and a 2i access point T at the user side2iLow voltage feeder equivalent impedance Rfi。
4. The low-voltage distribution user side state evaluation method according to claim 1,
the state perception terminal carries out information communication based on the narrow-band Internet of things of the honeycomb;
the state perception terminal is internally provided with a capacitance power supply module.
5. The low-voltage distribution user side state evaluation method according to claim 1,
the working mode of the state sensing terminal comprises an instruction mode and a transparent transmission mode;
the instruction mode uses a 3GPP standard instruction set, and NB modules are universal and compatible; transmitting data by packaging the AT command, and polling the AT command to inquire the received data; supplementing Chinese and English;
and the transparent transmission mode carries out transparent data transmission without operating AT instructions.
6. The low-voltage distribution user side state evaluation method according to claim 1,
the state perception terminal adopts a real-time multitask embedded operating system;
the state sensing terminal comprises a sampling follower circuit, a signal sampling/holding circuit and an A/D conversion circuit; the sampling follower circuit independently samples the voltage, current and frequency parameters of the power grid, and the sampling follower circuit, the signal sampling/holding circuit and the A/D conversion circuit are sequentially connected.
The signal sampling/holding circuit comprises a synchronous sampling data acquisition unit and an analog signal memory; the synchronous sampling data acquisition unit is connected with the analog signal memory.
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