CN109270360B - Method for calculating online line loss with high precision - Google Patents
Method for calculating online line loss with high precision Download PDFInfo
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- CN109270360B CN109270360B CN201811398193.5A CN201811398193A CN109270360B CN 109270360 B CN109270360 B CN 109270360B CN 201811398193 A CN201811398193 A CN 201811398193A CN 109270360 B CN109270360 B CN 109270360B
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- G01R27/02—Measuring real or complex resistance, reactance, impedance, or other two-pole characteristics derived therefrom, e.g. time constant
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Abstract
The invention discloses a method for calculating online line loss with high precision, which is based on the measurement of power, voltage and current at two ends of a line at the same time (within 5 ms), and the accumulated amount of electricity within a period of time, and provides accurate data for line loss analysis. A plurality of electric energy meters in a wide area range can receive other external synchronous pulse sources through a digital input port through hardware and software configuration, and when a pulse (the digital input is changed from OFF to ON) is detected, a freezing program is started: and freezing the calculation cycle data, calculating the current accurate power, and starting to calculate the electricity amount for a period of time. The same time can be GPS time correction trigger or communication time correction signal trigger. Through the internal freezing calculation of the electric energy meter and the background data integration of the communication network, the accurate line loss calculation and load balance calculation are realized.
Description
Technical Field
The invention belongs to the field of on-line monitoring of power systems, and particularly relates to a method for calculating on-line loss with high precision.
Background
In the operation process of a power system line of a factory, the line loss problem reflects the failure rate of the power line operation to a great extent, so the research on the line loss calculation and the loss reduction method is the content of the key research on the power system, and the line loss research is a complicated subject, wherein the overhead line is greatly influenced by natural conditions, such as: the loss of the line is large due to rain and hail; unlike overhead cables, power cables are less affected by natural conditions, but have a certain relationship with cable resistance, line media, sheaths, and steel strips happy.
According to the regulations of 'guide rules on reasonable power utilization technology of evaluation enterprises' issued by China, the internal power grid bus loss rate (from the power receiving end of an enterprise to power utilization equipment) of the enterprise can reach the following indexes: the first transformation is less than 3.5 percent, the second transformation is less than 5.5 percent, and the third transformation is less than 7 percent. However, the bus loss of the internal power grid of the factory enterprise in China is far higher than the requirement of the national standard, the bus loss is up to 10%, and the bus loss is up to 14-15% of the verification, so that line loss monitoring, research and analysis are frequently carried out, and loss reduction measures are very necessary.
At present, line loss mainly refers to an active loss part of a power cable line, the loss of electric energy on the line is called line loss, and the percentage of the line loss in all transmitted electric energy is called line loss rate, which is an economic index for measuring internal power supply of enterprises. Enterprises generally adopt an alternating current power supply mode, and skin effect and proximity effect are easily generated through alternating current wires. The skin effect causes the current density in the central portion of the cross section of the wire to be lower than the current density across the edge of the wire, which is equivalent to a reduction in the effective cross section of the wire and an increase in the resistance of the wire.
In the traditional method, measuring instruments are generally arranged at a wire inlet end and an equipment side, a system reads the accumulated electric energy data of the measuring instruments for a period of time, and then simple difference calculation is carried out to obtain the loss of the line. According to the traditional method, time difference exists when a wire inlet end and a device side measuring instrument are read, whether manual meter reading or communication mechanism reading is conducted, the read data are not data at the same moment, the difference value of the data at different moments is simply calculated, and large deviation exists certainly.
Disclosure of Invention
In order to overcome the defects in the prior art, the invention provides a method for calculating the line loss with high precision, which can calculate the line loss more accurately.
In order to achieve the purpose, the invention adopts the technical scheme that: the method for realizing high-precision calculation on-line loss is characterized in that synchronous sampling, synchronous calculation and storage of electric energy meters in a wide area range are realized, latched data are read through a communication management unit, and a non-deviation line loss statistical analysis function is realized.
A method for realizing high-precision calculation of online line loss comprises the following steps:
the method comprises the following steps: the method comprises the steps that a data freezing function is achieved by collecting the electric energy meter on site, and the electric energy meter is guaranteed to be frozen at the same time point in a wide area range;
step two: after the CPU processor of the electric energy meter receives the trigger of the synchronous pulse signal, the central mark is sampled and interrupted, an independent sampling point recording and storing latch area is opened up, the previous complete sampling points of one cycle are all moved to a freezing sampling buffer area, and the latch time is recorded at the same time. The CPU of the subsequent electric energy meter calculates three-phase current, three-phase voltage, active power and reactive power values by using the latched sampling point values;
step three: electric energy meters in the wide area range start to calculate the electricity consumption of a period of time at the same freezing moment K1;
step four: the communication management unit with the breakpoint continuous transmission function collects the current, voltage, power, electric power accumulated value and the like frozen in the electric energy meter in the wide area range through the communication management unit in each area through the communication interface;
step five: the monitoring SCADA software system reads the collected data (stored in the MYSQL database) from the database according to the freezing time, and can intuitively calculate line loss, voltage drop, real-time current difference and the like by utilizing a preset line topological relation.
And (3) load balance calculation:
i is further I1+ I2+ I3+ I4+ … … + IN
P in-P1 + P2+ P3+ P4+ … … + PN
Loss of voltage
△U＝UPower supply terminal-ULoad terminal
Line loss calculation
Line loss rate (W1-W2)/W1%
Furthermore, the electric energy meter is additionally provided with a GPS timing module and a conventional communication interface on hardware, and software supports two data latching modes: and the network GPS timing pulse is started and the communication broadcast command is started.
The communication management unit automatically realizes a regular network broadcast timing command, supports the receiving of timing signals, and has the functions of storing analog quantity and electricity measurement information for at least 31 days, supporting a breakpoint continuous transmission function and calling a new stored and frozen calculated power, electricity, current and voltage values in priority.
The method for calculating line loss is further characterized by:
in the first step, the frozen data comprises: and the real-time values of power, current and voltage at the same moment and the accumulated value of the electric degree after a period of time from the freezing time point.
In the second step, the start command received by the electric energy meter needs to be set as the highest task, the low-level task is directly stopped through the external interrupt (IO port interrupt or communication interrupt) of the CPU, and the low-level task enters the interrupt processing task.
In step three, the electric power is an accumulated value of power for a period of time: w is P Δ t; and when the time delta t (K2-K1) is consistent with the time of the electric energy meters in the wide range, the same accumulated time period of each meter is ensured.
Further, the method for implementing the interrupt continuous transmission function in the communication management unit comprises the following steps: the local acquisition module calls the acquired electric energy meter information periodically and stores the information in an XML file mode, the centralized acquisition module receives and analyzes the XML file, the file is stored in the real-time area and the backup area after the format is judged to be correct, then the data is written into the MYSQL database, and the real-time area file is deleted.
Has the advantages that: the invention uses a simple and practical method to carry out linkage between the electric energy meter and the communication management unit, realizes synchronous sampling and measurement of power, voltage, current and electric quantity of each loop in a wide area range, and ensures the accuracy of line loss calculation.
Drawings
FIG. 1 is a schematic system wiring diagram of the present invention.
Fig. 2 is a schematic diagram of the electric energy meter of the present invention receiving a trigger pulse.
FIG. 3 is a schematic diagram of a data buffer of the electric energy meter according to the present invention.
Fig. 4 is a communication protocol point table added by the present invention.
Detailed Description
In order to facilitate understanding of those skilled in the art, the present invention will be further described with reference to the following examples and drawings, which are not intended to limit the present invention.
The implementation method for calculating the online line loss with high precision in the embodiment comprises the following specific technical implementation steps:
step 1: the invention relates to a field acquisition electric energy meter, which realizes a data freezing function by adding specific hardware equipment and an algorithm and ensures that the electric energy meter is frozen at the same time point in a wide area range, wherein the frozen data comprises the following steps: and the real-time values of power, current and voltage at the same moment and the accumulated value of the electric degree after a period of time from the freezing time point.
The field electric energy meter is additionally provided with a GPS timing module and a conventional communication interface on hardware, and software supports two data latching modes: and starting a network GPS timing pulse or starting a communication broadcast command. The start command received by the field electric energy meter needs to be set as the highest task, the low-level task is directly stopped through the external interruption (IO port interruption or communication interruption) of the CPU, and the low-level task enters the interruption processing task.
Step 2: after the CPU processor of the electric energy meter receives the trigger of the synchronous pulse signal, the mark is placed in the sampling interruption, an independent sampling point recording and storing latch area is opened up, the whole sampling points of the previous cycle are moved to the freezing sampling buffer area, and the latch time is recorded. And the CPU of the subsequent electric energy meter calculates three-phase current, three-phase voltage, active power and reactive power values by using the latched sampling point values. Because each electric energy meter is latched at the same time, the electric energy meters in the wide area range can calculate the analog quantity at the same time.
And step 3: the electric energy meters in the wide area all start to calculate the electric consumption of a period of time at the same freezing time K1, and the period of time can be set, for example, 10 minutes, 1 hour or 1 day.
The electrical degree is an integrated value of power over a period of time: w is P Δ t; and when the time delta t (K2-K1) is consistent with the time of the electric energy meters in the wide range, the same accumulated time period of each meter is ensured.
And 4, step 4: the communication management unit with the breakpoint continuous transmission function collects the current, voltage, power, electric power accumulated value and the like frozen in the electric energy meter in the wide area range through the communication management unit in each area through the communication interface, and the delay of communication calling is not considered because the data is frozen. The communication management unit supports a breakpoint continuous transmission function and a function of calling the power, the electric power, the current and the voltage calculation values of the new storage freezing calculation preferentially. The specific method comprises the following steps: the communication management unit of the site stores the data read by communication into an XML file table according to the time mark, and can store data for one month according to the size of the current storage space. The central station communication management unit is communicated with the site communication management units, because the central station needs to access data in the site communication management units with wide geographical range and large quantity, if a certain site link is broken, the stored data table can be re-registered to the central station after the link is recovered, and the central station communication management unit automatically judges which data are additionally registered and additionally registers the data in the MYSQL database according to a fixed format.
And 5: the monitoring SCADA software system reads the collected data (stored in the MYSQL database) from the database according to the freezing time, and can intuitively calculate line loss, voltage drop, real-time current difference and the like by utilizing a preset line topological relation.
And (3) load balance calculation:
i is further I1+ I2+ I3+ I4+ … … + IN
P in-P1 + P2+ P3+ P4+ … … + PN
Loss of voltage
△U＝UPower supply terminal-ULoad terminal
Line loss calculation
The line loss rate is (W1-W2)/W1 is 100%.
The above embodiments are only for illustrating the technical idea of the present invention, and the protection scope of the present invention is not limited thereby, and any modification made on the basis of the technical solution according to the technical idea of the present invention falls within the protection scope of the present invention. The technology not related to the invention can be realized by the prior art.
Claims (7)
1. A high-precision online line loss calculation implementation method is characterized by comprising the following steps: synchronous sampling, synchronous calculation and storage of the electric energy meter in a wide area range, reading latched data through a communication management unit, and realizing a non-deviation line loss statistical analysis function, wherein the specific steps comprise:
the method comprises the following steps: the method comprises the steps that a data freezing function is achieved by collecting the electric energy meter on site, and the electric energy meter is guaranteed to be frozen at the same time point in a wide area range;
step two: after receiving the trigger of the synchronous pulse signal, the CPU processor of the electric energy meter sets a mark in the sampling interruption, opens up an independent sampling point recording and storing latch area, moves all the previous complete sampling points of one cycle to a freezing sampling buffer area, simultaneously records the latch time, and calculates the three-phase current, the three-phase voltage, the active power and the reactive power value by the subsequent CPU of the electric energy meter by using the sampling point value of the latch area;
step three: electric energy meters in the wide area range start to calculate the electricity consumption of a period of time at the same freezing moment K1;
step four: the communication management unit with the breakpoint continuous transmission function collects the current, voltage, power and electric power accumulated values frozen in the electric energy meter in the wide area range together through the communication management units in a plurality of areas through the communication interface;
step five: the monitoring SCADA software system reads the collected data from the database according to the freezing time, and can intuitively calculate line loss, voltage drop and real-time current difference by utilizing the preset line topological relation.
2. The method of claim 1, wherein: the electric energy meter is additionally provided with a GPS timing module and a conventional communication interface on hardware, and has two data latching modes supported on software: and the network GPS timing pulse is started and the communication broadcast command is started.
3. The method of claim 1, wherein: the communication management unit automatically realizes a regular network broadcast timing command, supports the receiving of timing signals, and has the functions of storing analog quantity and electricity measurement information for at least 31 days, supporting a breakpoint continuous transmission function and calling a new stored and frozen calculated power, electricity, current and voltage values in priority.
4. The method of claim 1, wherein in step one:
the frozen data includes: and the real-time values of power, current and voltage at the same moment and the accumulated value of the electric degree after a period of time from the freezing time point.
5. The method according to claim 1, wherein in step two:
the starting command received by the electric energy meter needs to be set as the highest task, the low-level task is directly stopped through the external interruption of the CPU processor, and the low-level task enters the interruption processing task.
6. The method according to claim 1, characterized in that in step three:
the watt consumption is an accumulated value of power within a period of time, and the electric energy meters within a wide area within the period of time are consistent in time, so that the accumulated time periods of the electric energy meters are guaranteed to be the same.
7. The method of claim 3, wherein the breakpoint resume function is implemented by: the local acquisition module calls the acquired electric energy meter information periodically and stores the information in an XML file mode, the centralized acquisition module receives and analyzes the XML file, the file is stored in the real-time area and the backup area after the format is judged to be correct, then the data is written into the MYSQL database, and the real-time area file is deleted.
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| CN105842653A (en) * | 2016-06-13 | 2016-08-10 | 国网江苏省电力公司电力科学研究院 | Simultaneous acquisition test circuit used for electric energy and clock pulses of electric energy meter |
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- 2018-11-22 CN CN201811398193.5A patent/CN109270360B/en active Active
Patent Citations (7)
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|---|---|---|---|---|
| US6757628B1 (en) * | 1998-07-14 | 2004-06-29 | Landis+Gyr Inc. | Multi-level transformer and line loss compensator and method |
| CN102497030A (en) * | 2011-12-28 | 2012-06-13 | 山东电力研究院 | Line-loss actual-measurement and positioning method based on high-voltage electric energy meter and system thereof |
| CN103336171A (en) * | 2013-06-29 | 2013-10-02 | 国家电网公司 | Line loss analysis platform of electric quantity system |
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