CN101149408A - T-shaped transmission line zero-sequence resistance parameter live line measurement method and device - Google Patents
T-shaped transmission line zero-sequence resistance parameter live line measurement method and device Download PDFInfo
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Abstract
The zero-sequence impedance parameter measure method of the T type electric transmission line, the method lets the load current provide the zero-sequence current for measurement by cutting the single-phase switch in a certain branch of T type electric transmission line to make run without phase, then resumes the normal run in 0.5 second to 1 second. Uses the GPS technology realize the multi-terminal zero-sequence voltage, zero-sequence current synchromesh collection of T type electric transmission line; collects the data of each measurement point to the center computer by using the modem or Ethernet network; gets the zero-sequence impedance parameter of the mutual inductance circuit by using the least square law solute the algebraic equations, differential equations or integral equations; this equipment is composed of GPS antenna and OEM board, signal input connection interface, signal transducer, embedded DPS synchromesh data collection card, launch amount card, relay group, relay group input interface, embed PC card, the electrical source card, electrical source signal bus motherboard.
Description
Technical Field
The invention belongs to the technical field of power system transmission line parameter measurement, and particularly relates to a method and a device for live line measurement of a T-shaped transmission line zero sequence parameter.
Background
With the development of the scale of an electric power system, outgoing lines of power plants (transformer substations) are increased, and T-connection power transmission lines are more and more;
the zero sequence impedance of the T-shaped power transmission line can affect the line fault state, particularly the magnitude of zero sequence current, and the influence on zero sequence current protection is great; the zero sequence impedance of the T-shaped circuit is influenced by a plurality of factors, such as the line trend, the grounding resistance rate of a zero sequence current flowing area and the like; the theoretical calculation value cannot meet the precision requirement of the relay protection setting value calculation, and if the calculation value is used as the basis of the setting calculation, the protection can be rejected or mistakenly operated when the system fails, which directly threatens the safe and stable operation of the system; therefore, in the standards of the power industry of the people's republic of China, regulations on relay protection setting in the 220kV-500kV power grid relay protection operation regulations (DL/T559-94, 1995-05-01 implementation) indicate that: the zero sequence impedance of the overhead line and the cable and other parameters which have large influence on relay protection should use measured values.
The traditional method for determining the zero sequence parameter of the power transmission line comprises a formula calculation method and a power failure measurement method; the calculation result of the formula is inaccurate because the calculation formula involves uncertain parameters such as earth resistivity and the like.
The method for measuring the T-type line parameters by the outage measurement method requires that the measured line is powered off; it is often impossible to measure a T-line outage; in addition, the measurement is carried out according to the traditional power failure mode, the equipment amount and the workload are too large to bear in a wider region, and the measurement simultaneity cannot be guaranteed; therefore, a new T-shaped line parameter live line measurement method is sought, a corresponding test system is developed, and the method is urgently needed by an electric power system operation department, and has not only important theoretical value but also great economic and social benefits.
Disclosure of Invention
The invention aims to overcome the defects of the existing method for measuring the zero sequence impedance parameter of the T-shaped power transmission line by using the power failure measurement method, provides the electrified measuring method for the zero sequence impedance parameter of the T-shaped power transmission line, develops the electrified measuring device for the zero sequence impedance parameter of the T-shaped power transmission line based on the GPS according to the electrified measuring method, and realizes accurate measurement of the zero sequence impedance parameter when the T-shaped power transmission line is electrified.
In order to realize the purpose of the invention, the technical scheme provided by the invention is as follows: a T-shaped transmission line zero sequence impedance parameter live line measurement method comprises the following steps:
generating zero-sequence heavy current for live line measurement by the running mode of a T-shaped power transmission line during live line measurement, disconnecting a single-phase switch of any branch of the T-shaped line for live line operation by a relay protection device on the T-shaped line to cause phase-lacking operation, supplying the zero-sequence current for measurement by load current, and after 0.5-1 second, generating the zero-sequence heavy current for the live line measurement by a method of recovering the normal operation of the line by an automatic reclosing device on the T-shaped line;
during live-line measurement, the operation mode of the T-shaped transmission line is shown in table I:
TABLE I
| Operation of the device (Mode) | T-shaped line | ||
| Branch 1 | Branch 2 | Branch 3 | |
| 1 | Single-phase trip, 0.5 seconds & Reclosing after 1.0 second | Normal operation | Normal operation |
| 2 | Normal operation | Single phase trip, 0.5 second-1.0 Reclosing after second | Normal operation |
| 3 | Normal operation | Normal operation | Single-phase trip, 0.5 seconds & Reclosing after 1.0 second |
(II) realizing synchronous sampling of voltage signals and current signals of the T-shaped power transmission line by utilizing a GPS technology, and acquiring zero-sequence current and zero-sequence voltage data of the T-shaped power transmission line
Acquiring a time reference with an error less than 1 mu s by utilizing a time service function of a global satellite positioning system, simultaneously acquiring a zero sequence current instantaneous value of each branch and a zero sequence voltage instantaneous value of each branch endpoint before and after zero sequence current injection under the time synchronization of the global satellite positioning system, and storing the zero sequence current instantaneous values and the zero sequence voltage instantaneous values into an acquisition device in a file manner;
thirdly, summarizing the data of each measuring point into a central computer by utilizing a modem or an Ethernet;
after obtaining the sampling data of the zero-sequence current instantaneous value and the zero-sequence voltage instantaneous value of the T-shaped power transmission line, the central computer calculates the zero-sequence impedance parameter of the T-shaped power transmission line by adopting the following algebraic equation method, differential equation method or integral equation method:
(1) Algebraic equation method
The algebraic equation set for a T-shaped transmission line is written as follows:
(1-1) formula (I), wherein Z n Impedance of the nth branch, including resistance r n And reactance x n Two parts, n =1,2,3;
respectively is a zero sequence current vector value of each branch,
zero sequence voltage vector values at the power supply of each branch end point are respectively obtained;
adopting Fourier filtering algorithm to obtain corresponding zero-sequence current vector value and zero-sequence voltage vector value for the zero-sequence current instantaneous value and zero-sequence voltage instantaneous value collected in the step (II);
for an algebraic equation set (1-1), generating sampling data according to any one operation mode in a table I to obtain 2 independent equations; generating sampling data according to any one or more than one other operation modes in the table I to obtain 2 or more than 2 independent equations; thus, at least 4 independent equations are obtained, and 3 unknown zero-sequence parameters are solved by adopting a least square method: z 1 ，Z 2 ，Z 3 ；
Solving by a least square method to obtain
In the above formula:
in the measurement matrixes I and U in the formula (1-2), the upper labels of the zero sequence current vectors and the zero sequence voltage vectors are independent measurement times, p is more than or equal to 2 and less than or equal to 3, and the lower labels are branch numbers of T-shaped circuits.
(2) Method of differential equations
The differential equation set for a T-type transmission line is written as follows:
(2-1) wherein r n Is the resistance of the nth branch, L n N =1,2,3 for the inductance of the nth branch;
are respectively zero sequence current instantaneous value u of each branch 1 ，u 2 ，u 3 Respectively representing zero sequence voltage instantaneous values at the power supply of each branch circuit endpoint;
the steady state process of the current and voltage signals after the single-phase switch of any branch of the T-type circuit is tripped is taken as a data window for acquiring the zero sequence current instantaneous value and the zero sequence voltage instantaneous value in the differential equation set;
by using
Replacing derivative terms in a system of differential equations
Wherein n =1,2,3;
writing the system of differential equations (2-1) in discrete form:
and
zero sequence current instantaneous values u of two adjacent sampling moments in the steady state process of zero sequence current and zero sequence voltage signals after zero sequence current injection n (k-1) and u n (k) Zero sequence voltage instantaneous values, T, of two adjacent sampling moments in the steady state process of zero sequence current and zero sequence voltage signals after zero sequence current injection S Is a sampling period;
for the differential equation set (2-2), generating sampling measurement data according to any one operation mode in the table I, and randomly selecting zero-sequence current instantaneous values and zero-sequence voltage instantaneous values corresponding to 3 adjacent sampling points k-1, k and k +1 to obtain 2 independent equations; taking zero-sequence current instantaneous values and zero-sequence voltage instantaneous values corresponding to 3 adjacent sampling points k, k +1 and k +2, and then obtaining 2 independent equations; each independent measurement mode can obtain 4 independent equations; generating sampling data according to any one or more operation modes in the table I to obtain 4 or more than 4 independent equations; thus, at least 8 independent equations are obtained, and 6 unknown zero-sequence parameters are solved by adopting a least square method: r is a radical of hydrogen 1 ，L 1 ，r 2 ，L 2 ，r 3 ，L 3 ；
Solving by a least square method to obtain
In the above formula:
in the formula (2-3), the superscript of each zero-sequence current and zero-sequence voltage instantaneous value is an independent measuring time, p is more than or equal to 2 and less than or equal to 3, and the subscript is a branch number; k is the number of sampling points; t is s Is the sampling period.
(3) Method of integral equation
The left side and the right side of the differential equation system (2-1) are integrated to obtain an integral equation system:
taking a steady-state process of a zero-sequence current signal and a zero-sequence voltage signal after the single-phase switch of any branch of the T-shaped transmission line is tripped for a data window for acquiring the zero-sequence current instantaneous value and the zero-sequence voltage instantaneous value in the integral equation set;
by [ u ] n (k)+u n (k-1)]T s A combination of/2 andrespectively replacing integral terms in integral equation set t1 t2 u n dt and- t1 t2 i n dt; wherein n =1,2,3;
the system of integral equations (3-1) is written in discrete form:
For an integral equation set (3-2), generating sampling measurement data according to any one operation mode in a table I, and randomly selecting zero-sequence current instantaneous values and zero-sequence voltage instantaneous values corresponding to 3 adjacent sampling points k-1, k and k +1 to obtain 2 independent equations; taking zero-sequence current instantaneous values and zero-sequence voltage instantaneous values corresponding to 3 adjacent sampling points k, k +1 and k +2, and then obtaining 2 independent equations; each independent measurement mode can obtain 4 independent equations; generating sampling data according to any one or more operation modes in the table I to obtain 4 or more than 4 independent equations; thus, at least 8 independent equations are obtained, and 6 unknown zero-sequence parameters are solved by adopting a least square method: r is 1 ，L 1 ，r 2 ，L 2 ，r 3 ，L 3 ；
Solving by a least square method to obtain,
in the above formula:
in the formula (3-3), the superscript of each zero-sequence current and zero-sequence voltage instantaneous value is an independent measuring time, p is more than or equal to 2 and less than or equal to 3, and the subscript is a branch number; k is the number of sampling points; t is s Is the sampling period.
The invention also provides a T-shaped transmission line zero sequence impedance parameter live-line measurement device which is composed of a GPS antenna, an OEM board, a signal input wiring terminal, a signal transmitter, an embedded DSP synchronous data acquisition card, an output card, a relay group, a relay output interface, an embedded PC card, a power supply signal bus bottom board, a liquid crystal display, a hard disk, a keyboard, a mouse and a case; voltage signals of a voltage transformer and current signals of a current transformer of the power transmission line are connected to the embedded DSP synchronous data acquisition card after passing through a signal input wiring terminal and a signal transmitter, and a GPS antenna is connected with an output PPS signal of an OEM board and a DSP interrupt input of the embedded DSP synchronous data acquisition card; the GPS antenna and the output GPS serial time signal of the OEM board are input into a serial port on the embedded PC card; the data collected by the DSP synchronous data collection card is connected with the embedded PC card through the double-port RAM; the hard disk is connected with the embedded PC card and used for storing the sampling data; the keyboard and the mouse are connected with the embedded PC card and are used for inputting information such as characters, numbers and the like; the circuit tripping and closing commands sent by the embedded PC card are connected with a circuit breaker of the power transmission line through the output card and a relay output interface in the relay group; the embedded PC card is connected with the output card and other relays in the relay group; the gear size is used for switching the input signal of the signal transmitter; the power supply card provides working power supply for the device; the power signal bus bottom board provides a power supply and signal connection channel for the embedded DSP synchronous data acquisition card, the output card and the embedded PC card; the liquid crystal display is connected with a video signal interface of the embedded PC card and is used for displaying output contents such as graphics, characters and the like; the data in the hard disk is connected with a computer by an embedded PC card through Ethernet or a modem and is sent to a central computer for the zero sequence parameter live measurement calculation software of the T-shaped power transmission line to use; the case plays a role in fixing each measuring component and shielding external interference.
The method of the invention is characterized in that:
(1) The method can be used for live line measurement and also can be used for power failure measurement;
(1) Zero-sequence resistance and zero-sequence reactance of the T-shaped line can be measured simultaneously;
(2) Besides the measurement under the condition of reclosing after short-time single-phase tripping of the T-shaped line, the measurement can also be carried out under the fault conditions of unbalanced load of the branch line, single-phase short circuit grounding of the branch line, two-phase short circuit grounding and the like.
The invention has the following advantages and positive effects:
1. the traditional measuring method can only carry out measurement when the T-shaped transmission line is powered off, but the measuring method can carry out measurement when the T-shaped transmission line is in live operation, thereby reducing the power failure loss and improving the economic benefit and the social benefit;
2. the measurement utilizes the GPS to solve the problem of simultaneity of remote measurement;
3. the least square method is adopted, so that the problem of an over-determined equation in measurement is solved;
4. the method adopts a Fourier filtering algorithm, so that the measurement precision is improved;
5. the device adopts a design method of an embedded system, has a delicate structure and has the function of a virtual instrument;
6. the gear of the input signal of the device is automatically switched by software, so that the device is more convenient to use.
Drawings
FIG. 1 is a schematic diagram of a T-shaped power transmission line represented by a vector symbol;
fig. 2 is a schematic diagram of a T-shaped transmission line represented by a scalar symbol;
FIG. 3 is a schematic diagram of the charged measuring device of the present invention;
fig. 4 is a schematic diagram of a live measurement process.
Detailed Description
When T-shaped line parameter live line measurement is carried out, the method for acquiring the zero sequence current of each branch of the T-shaped line and the zero sequence voltage of each branch end point is as follows:
as shown in FIG. 1, Z n The impedance of the nth branch is measured as a zero sequence impedance parameter and comprises a resistor r n And reactance x n Two parts, where n =1,2,3;
respectively is a zero sequence current vector value of each branch,respectively as the zero sequence voltage vector value at each branch end point,
is the zero sequence voltage vector value at the T junction;
in FIG. 2, r n Is the resistance of the nth branch, L n The inductance of the nth branch is measured as a zero sequence impedance parameter, wherein n =1,2,3;are respectively the zero sequence current instantaneous value u of each branch 1 ，u 2 ，u 3 And zero sequence voltage instantaneous values, u, at the end points of the branches T Is the zero sequence voltage instantaneous value at the T junction;
in the attached figures 1 and 2 of the drawings,zero sequence current signal on each branch circuit of T-shaped circuit
Connecting into current signal input channel of each live line measurement device, and connecting zero sequence voltage signal u at each branch end point of T-shaped line 1 ，u 2 ，u 3 The voltage signal input channel is connected into the live measurement device, and under the synchronization of GPS time, each synchronous measurement device simultaneously acquires the zero sequence current signal on each branch
Instantaneous value of and zero sequence voltage signal u at each branch end point 1 ，u 2 ，u 3 The instantaneous value of (a); in order to improve the measurement accuracy, the data sampling rate is generally more than 4000 points/second, namely 80 points are collected in each power frequency period;
for collected zero sequence current instantaneous value
And zero sequence voltage instantaneous value u 1 ，u 2 ，u 3 Obtaining corresponding zero sequence current vector value by adopting Fourier filtering algorithm
And zero sequence voltage vector value
The connection relationship of each component and related signals of the live measurement device is as follows:
as shown in figure 3 (in figure 3, TV represents a voltage transformer, TA represents a current transformer), the live line measuring device is composed of a GPS antenna, an OEM board, a signal input terminal, a signal transmitter, an embedded DSP synchronous data acquisition card, a measurement card, a relay set, a relay output interface, an embedded PC card, a power signal bus backplane, a liquid crystal display, a hard disk, a keyboard, a mouse, and a chassis; voltage signals of a voltage transformer and current signals of a current transformer of the power transmission line are respectively connected to the embedded DSP synchronous data acquisition card through a signal input wiring terminal and a signal transmitter, and output PPS signals of a GPS antenna and an OEM board are connected with DSP interrupt input of the embedded DSP synchronous data acquisition card; the GPS antenna and the output GPS serial time signal of the OEM board are input into a serial port on the embedded PC card; the data collected by the DSP synchronous data collection card is connected with the embedded PC card through the double-port RAM; the hard disk is connected with the embedded PC card and used for storing the sampling data; the keyboard and the mouse are connected with the embedded PC card and are used for inputting information such as characters, numbers and the like; the embedded PC card sends out a line tripping and closing command which is connected with a breaker of the transmission line through a relay output interface; the embedded PC card is connected with the output card and the relay set and is used for switching the gear size of the input signal of the signal transmitter; the power supply card provides working power supply for the device; the power signal bus bottom board provides a connecting channel for the embedded DSP synchronous data acquisition card, the output card and the embedded PC card to supply power and signals; the liquid crystal display is connected with a video signal interface of the embedded PC card and is used for displaying output contents such as graphics, characters and the like; the data in the hard disk is connected with a computer by an embedded PC card through Ethernet or a modem and is transmitted to a central computer for the use of T-shaped transmission line zero sequence parameter live line measurement and calculation software; the case has the functions of fixing various measuring components and shielding external interference.
The measurement implementation process of the charged measurement device is as follows:
1. the measurement signals are zero sequence voltage of a bus or a line TV and zero sequence current of a line TA;
2. after the signals are subjected to isolation transformation and analog filtering links, the signals are subjected to A/D transformation and then are processed by an embedded DSP data acquisition card;
3. when the GPS time received by the embedded PC card is consistent with the setting time, the embedded PC card on the measuring device of the main measuring station sends a tripping command of the circuit breaker, then the tripping command is sent to an auxiliary tripping contact of the circuit breaker through the output card for output, and meanwhile, the synchronous measuring devices of all measuring points start synchronous sampling data when the setting time is up; each side measuring point simultaneously acquires data of 0.5 second before tripping and 1 second after tripping;
4. the embedded PC card reads the time information of the GPS from the serial port every second, controls A/D conversion under the synchronization of PPS signals sent by the GPS receiver, marks GPS time marks on the data after the A/D conversion and stores the data into a double-port RAM on the embedded DSP card;
5. the embedded PC card reads sampling data from the dual-port RAM and stores the sampling data into the hard disk, and takes characteristic parameters such as time during sampling, line number and the like as the file name of the measurement;
6. after all the measurements are finished, the data collected by each measuring point are sent to a specified central computer through an INTERNET network or a MODEM, the central computer collects all the sampled data, then the parameters are calculated, and the calculation results are printed;
the invention and the measuring device are further illustrated below with reference to an embodiment (fig. 4):
a T-shaped power transmission line is arranged, the branch numbers of the T-shaped power transmission line are 1,2 and 3 respectively, and each branch is in a live running state; the method is characterized in that a short-time trip is carried out on a branch 1, a zero-sequence current for measurement is generated in a way of reclosing a line after 1 second, the branch 2 and the branch 3 still run in a charged state, as shown in the attached figure 4 (in the figure 4, TV represents a voltage transformer, TA represents a current transformer), and the charged measurement steps are as follows:
1. firstly, after each measuring station (such as A, B, C station) withdraws the protection related to each line and the zero sequence, the measuring device is connected according to the measuring wiring diagram shown in the attached figure 2; 3U of bus TV open triangle 0 And 3I of line TA zero sequence loop 0 Respectively connecting the voltage channels and the current channels of the synchronous acquisition device, and adjusting the gears of the channels to proper gears by using relays;
2. when the GPS receiver receives more than 4 satellite information, the GPS time is synchronous; each station uses software to set the synchronous sampling starting time of each measuring device under the instruction of the station A;
3. when the setting time arrives, the live measurement device sends a trip signal, a certain phase (such as C phase) of the operation circuit is tripped through the relay protection device, and the trip circuit is closed again after 1 second; the acquisition device of each measuring point simultaneously acquires data of 0.5 second (25 cycles) before tripping and 1 second (50 cycles) after tripping of the line, and marks GPS time marks;
4. after the data acquisition is finished, the embedded PC card on each device (A, B, C) transmits the acquired data to the hard disk through the dual-port RAM, and the GPS time is used as a file name for storage; meanwhile, the information of the CT of each circuit, the transformation ratio of the PT of the bus, the channel number, the gear and the like is stored into a corresponding file;
5. changing the measuring (running) mode according to the table I, respectively adopting a mode of jumping off a certain phase of the line on the branch 2 and the branch 3, and repeating the steps 1-4 after 1 second and then overlapping the line;
6. after all measurements are completed, data of the B station and the C station are sent to the A station through a MODEM or INTERNET network, and after all measurement data are summarized by the A station, zero sequence impedance parameters of the T-shaped line are calculated by a calculation software package.
Claims (2)
1. A T-shaped transmission line zero sequence impedance parameter live line measurement method comprises the following steps:
generating zero sequence large current for live line measurement by the following operation mode of T-shaped transmission line during live line measurement
The method comprises the steps that a relay protection device on a T-shaped power transmission line is used for disconnecting a single-phase switch on any branch of the T-shaped power transmission line which runs in a live-line mode to cause phase-lacking running, load current is used for supplying zero-sequence current for measurement, and after 0.5-1 second, a method for recovering normal running of the line through an automatic reclosing device on the T-shaped power transmission line is used for generating zero-sequence large current for live-line measurement;
during live-line measurement, the operation mode of the T-shaped power transmission line is shown in table 1:
TABLE 1
(II) synchronous sampling of voltage signals and current signals of the T-shaped power transmission line is realized by utilizing a GPS technology, and zero sequence current and zero sequence voltage data of the T-shaped power transmission line are obtained
Acquiring a time reference with an error less than 1 mu s by utilizing a time service function of a global satellite positioning system, simultaneously acquiring a zero sequence current instantaneous value of each branch and a zero sequence voltage instantaneous value of each branch end point before and after zero sequence current injection under time synchronization of the global satellite positioning system, and storing the zero sequence current instantaneous values and the zero sequence voltage instantaneous values into an acquisition device in a file mode;
thirdly, summarizing the data of each measuring point into a central computer by utilizing a modem or an Ethernet;
after obtaining the data of the zero-sequence current instantaneous value and the zero-sequence voltage instantaneous value of the T-shaped power transmission line, the central computer calculates the zero-sequence impedance parameter of the T-shaped power transmission line by adopting the following algebraic equation method, differential equation method or integral equation method:
(1) Algebraic equation method
The algebraic equation set for a T-shaped transmission line is written as follows:
(A1) In the formula, Z n Is zero sequence self-impedance of the nth branch, including a resistor r n And reactance x n Two parts, n =1，2，3； 
Respectively is a zero sequence current vector value of each branch,zero sequence voltage vector values at the power supply of each branch end point are respectively obtained;
adopting a Fourier filtering algorithm to obtain corresponding zero-sequence current vector values and zero-sequence voltage drop vector values for the zero-sequence current instantaneous values and the zero-sequence voltage instantaneous values acquired in the step (II);
for an algebraic equation set (A1), generating sampling data according to any one operation mode in table 1 to obtain 2 independent equations; generating sampling data according to any one or more than one other operation modes in the table 1 to obtain 2 or more than 2 independent equations; thus, at least 4 independent equations are obtained, and 3 unknown zero-sequence parameters are solved by adopting a least square method: z 1 ，Z 2 ，Z 3 ；
Solving by using a least square method to obtain,
(A2)
in the above formula:
(A2) In the measurement matrixes I and U, the upper mark of each zero-sequence current and zero-sequence voltage drop vector is an independent measurement frequency, p is more than or equal to 2 and less than or equal to 3, and the lower mark is the branch number of the T-shaped power transmission line;
(2) Method of differential equations
The differential equation set for a T-shaped transmission line is written as follows:
(B1) In the formula, r n Is the resistance of the nth branch, L n The inductance of the nth branch, n =1,2,3; i.e. i 1 ，i 2 ，i 3 Are respectively zero sequence current instantaneous value u of each branch 1 ，u 2 ，u 3 Respectively representing zero sequence voltage instantaneous values at the power supply of each branch circuit endpoint;
taking the steady state process of the zero sequence current and zero sequence voltage signals after the single-phase switch of any branch of the T-type circuit is tripped out for a data window for acquiring the zero sequence current instantaneous value and the zero sequence voltage instantaneous value in the differential equation set;
by using
Replacing derivative terms in a system of differential equations
Wherein n =1,2,3;
writing the system of differential equations (B1) in discrete form:
i n (k-1) and i n (k) Zero-sequence current instantaneous value u of two adjacent sampling moments in the steady-state process of zero-sequence current and zero-sequence voltage signals after zero-sequence current injection n (k-1) and u n (k) Zero sequence voltage instantaneous values, T, at two adjacent sampling moments in the steady-state process of the current-voltage signal after zero sequence current injection S Is a sampling period;
for the differential equation set (B2), generating sampling measurement data according to any one operation mode in the table 1, and randomly selecting zero-sequence current instantaneous values and zero-sequence voltage instantaneous values corresponding to 3 adjacent sampling points k-1, k and k +1 to obtain 2 independent equations; another 3 adjacent to each otherObtaining 2 independent equations according to the zero-sequence current instantaneous values and the zero-sequence voltage instantaneous values corresponding to the sampling points k, k +1 and k + 2; each independent measurement mode can obtain 4 independent equations; generating sampling data according to any one or more than one other operation modes in the table 1 to obtain 4 or more than 4 independent equations; thus, at least 8 independent equations are obtained, and 6 unknown zero-sequence parameters are solved by adopting a least square method: r is 1 ，L 1 ，r 2 ，L 2 ，r 3 ，L 3 ；
Solving by a least square method to obtain
(B3) In the formula:
(B3) In the formula, the upper mark of each zero sequence current and zero sequence voltage instantaneous value is independent measuring times, p is more than or equal to 2 and less than or equal to 3, and the lower mark is branch number; k is the number of sampling points; t is s Is a sampling period;
(3) Method of integral equation
Integrating the left side and the right side of the differential equation set (B1) to obtain an integral equation set:
taking the steady state process of the zero sequence current and zero sequence voltage signals after the single-phase switch of any branch of the T-type circuit is tripped out for a data window for acquiring the zero sequence current instantaneous value and the zero sequence voltage instantaneous value in the integral equation set;
by [ u ] n (k)+u n (k-1)]T s [ 2 ] and [ i ] n (k)+i n (k-1)]T s Respectively replacing integral terms in integral equation set by 2
The system of integral equations (C1) is written in discrete form:
i n (k-1) and i n (k) Zero sequence current instantaneous values u of two adjacent sampling moments in the steady state process of zero sequence current and zero sequence voltage signals after zero sequence current injection n (k-1) and u n (k) Zero sequence voltage instantaneous values, T, at two adjacent sampling moments in the steady-state process of the current-voltage signal after zero sequence current injection S Is a sampling period; t is s ＝t 2 -t 1 ；
For an integral equation set (C2), generating sampling measurement data according to any one operation mode in table 1, and randomly selecting zero-sequence current instantaneous values and zero-sequence voltage instantaneous values corresponding to 3 adjacent sampling points k-1, k and k +1 to obtain 2 independent equations; taking another zero-sequence current instantaneous value and zero-sequence voltage instantaneous value corresponding to 3 adjacent sampling points k, k +1 and k +2, and obtaining 2 independent sampling points k, k +1 and k +2An equation; each independent measurement mode can obtain 4 independent equations; generating sampling data according to any one or more than one other operation modes in the table 1 to obtain 4 or more than 4 independent equations; thus, at least 8 independent equations are obtained, and 6 unknown zero-sequence parameters are solved by adopting a least square method: r is 1 ，L 1 ，r 2 ，L 2 ，r 3 ，L 3 ；
Solving by using a least square method to obtain,
in the above formula:
(C3) In the formula, the upper mark of each zero sequence current and zero sequence voltage instantaneous value is independent measuring times, p is more than or equal to 2 and less than or equal to 3, and the lower mark is branch number; k is the number of sampling points; t is a unit of s Is the sampling period.
2. A T-shaped line zero sequence impedance parameter live line measurement device is characterized in that: the system is composed of a GPS antenna, an OEM board, a signal input wiring terminal, a signal transmitter, an embedded DSP synchronous data acquisition card, an output card, a relay group, a relay output interface, an embedded PC card, a power supply signal bus bottom board, a liquid crystal display, a hard disk, a keyboard, a mouse and a case; the voltage signal of the voltage transformer and the current signal of the current transformer of the power transmission line are respectively accessed to the embedded DSP synchronous data acquisition card through a signal input wiring terminal and a signal transmitter, and the output PPS signal of the GPS antenna and the OEM board is connected with the DSP interrupt input of the embedded DSP synchronous data acquisition card; the GPS antenna and the output GPS serial time signal of the OEM board are input into a serial port on the embedded PC card; the data collected by the DSP synchronous data collection card is connected with the embedded PC card through the dual-port RAM; the hard disk is connected with the embedded PC card; the keyboard and the mouse are connected with the embedded PC card; a line tripping and closing command sent by the embedded PC card is connected with a circuit breaker of a power transmission line through the output card and one relay output interface in the relay group; the embedded PC card is connected with the output card and other relays in the relay group; the power supply card provides working power supply for the device; the power signal bus bottom board provides a power supply and signal connection channel for the embedded DSP synchronous data acquisition card, the output card and the embedded PC card; the liquid crystal display is connected with the video signal interface of the embedded PC card.
Priority Applications (1)
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Cited By (6)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN101419253B (en) * | 2008-12-17 | 2011-02-16 | 河南电力试验研究院 | Uhv transmission line positive sequence and zero sequence parameter measurement method and system |
| CN101699301B (en) * | 2009-10-29 | 2011-08-10 | 江苏省电力试验研究院有限公司 | Method for measuring line parameter through induced electricity |
| CN103353568A (en) * | 2013-06-18 | 2013-10-16 | 国家电网公司 | Teed line fault branch selection method |
| CN103675565A (en) * | 2014-01-09 | 2014-03-26 | 武汉大学 | Method for measuring power frequency parameters of superhigh/extrahigh-voltage alternating-current (direct-current) power transmission circuit |
| CN106324347A (en) * | 2015-06-16 | 2017-01-11 | 云南电网有限责任公司玉溪供电局 | T-type connection transmission line power frequency positive-sequence impedance measurement method |
| CN107153142A (en) * | 2017-05-23 | 2017-09-12 | 武汉大学 | A kind of T-shaped transmission line parameter measuring method of asymmetrical three-phase |
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2007
- 2007-10-31 CN CNB2007100536998A patent/CN100552459C/en not_active Expired - Fee Related
Cited By (10)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN101419253B (en) * | 2008-12-17 | 2011-02-16 | 河南电力试验研究院 | Uhv transmission line positive sequence and zero sequence parameter measurement method and system |
| CN101699301B (en) * | 2009-10-29 | 2011-08-10 | 江苏省电力试验研究院有限公司 | Method for measuring line parameter through induced electricity |
| CN103353568A (en) * | 2013-06-18 | 2013-10-16 | 国家电网公司 | Teed line fault branch selection method |
| CN103353568B (en) * | 2013-06-18 | 2016-04-20 | 国家电网公司 | The system of selection of T link fault branch |
| CN103675565A (en) * | 2014-01-09 | 2014-03-26 | 武汉大学 | Method for measuring power frequency parameters of superhigh/extrahigh-voltage alternating-current (direct-current) power transmission circuit |
| CN103675565B (en) * | 2014-01-09 | 2016-09-14 | 武汉大学 | Ultra-high/extra-high voltage transmission line of alternation current power frequency parameters measuring method |
| CN106324347A (en) * | 2015-06-16 | 2017-01-11 | 云南电网有限责任公司玉溪供电局 | T-type connection transmission line power frequency positive-sequence impedance measurement method |
| CN106324347B (en) * | 2015-06-16 | 2019-01-25 | 云南电网有限责任公司玉溪供电局 | T-type wiring transmission line power frequency positive sequence impedance measurement method |
| CN107153142A (en) * | 2017-05-23 | 2017-09-12 | 武汉大学 | A kind of T-shaped transmission line parameter measuring method of asymmetrical three-phase |
| CN107153142B (en) * | 2017-05-23 | 2020-01-07 | 武汉大学 | Three-phase asymmetric T-shaped power transmission line parameter measurement method |
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| CN100552459C (en) | 2009-10-21 |
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Assignee: Foshan Electric Power Design Institute Co., Ltd. Assignor: Wuhan University Contract record no.: 2010990001004 Denomination of invention: T-shaped transmission line zero-sequence resistance parameter live line measurement method and device Granted publication date: 20091021 License type: Exclusive License Open date: 20080326 Record date: 20101224 |
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