CN204495932U - The electric Parameter Measuring device of power transmission and distribution circuit - Google Patents

Abstract

The utility model discloses the electric Parameter Measuring device of power transmission and distribution circuit, comprise multiple measuring unit, each measuring unit is all communicated with main station system by data concentrator, time synchronized is carried out by clock synchronization unit between measuring unit, measuring unit is corresponding measurement point synchronized phasor data under setting-up time is captured in same time point by a CT and current transformer and a PT and voltage transformer (VT), described measuring unit is also connected with protective current sensor with measurement current sensor by range switch circuit, utilize range switch circuit still can record corresponding waveform when circuit breaks down, image data is sent to main station system by data concentrator by measuring unit.The utility model adopts the synchronous phasor measurement terminal D PMU being specific to distribution system, improves real-time and the accuracy of distribution network data acquisition.

Description

The electric Parameter Measuring device of power transmission and distribution circuit

Technical field

The utility model relates to Operation Technique of Electric Systems field, particularly relates to the electric Parameter Measuring device and method of a kind of power transmission and distribution circuit.

Background technology

Operation of Electric Systems, the assurance of analyst to electrical network characteristic depend on the Real Time Monitoring based on electric network model.Electrical network parameter forms electric network model accurately to carry out the basis of power system computation accurately.Therefore, improve accuracy and the reliability of electrical network parameter, the safe and stable operation of short-term load is significant.

In view of every bar circuit concrete condition is different, and transmission line of electricity especially 220kV and the above circuit working line that nearly all has runs parallel with it or joint use, this brings very large interference and difficulty to the parameter measurement of transmission line of electricity.Because influence factor is more; in addition design theory is more or less considered in calculating to owe thorough; circuit actual parameter may be caused with design parameter to differ comparatively large, and then affect state estimation, Load flow calculation, Losses Analysis, fault analysis and the accuracy rate of relay protection setting calculation and the reliability of result of calculation.So DL/T584-95 " 3kV ~ 110kV grid relay protective apparatus runs code of adjusting " and DL/T559-94 " 220kV ~ 500kV grid relay protective apparatus runs code of adjusting " requires that 110 kilovolts of Above Transmission Lines all will provide power frequency parameter measured value; based on the reliability improving operation of power networks parameter and accuracy, ensure the calculating of the multiple link of electric system based on operation of power networks parameter, research and analysis work.

In line parameter circuit value actual measurement work, because circuit is long, the impact of the factor such as measurement mechanism off-capacity or parallel circuit mutual inductance, the actual measurement parameter that line outage metering system obtains often differs with theoretical value comparatively greatly, and thus accuracy is queried.In addition, current line parameter circuit value actual measurement device needs line outage in measuring process, and 110kV and Above Transmission Lines power failure can make electric network composition become weak, therefore, and the circuit actual measurement device that Regulation department needs are a kind of more accurately, online.

Generally speaking, the technical matters needing those skilled in the art urgently to solve at present is: under electrical power trans mission/distribution system normal operation, how to find a kind of work comprehensively, efficient device and method realizes the real-time online measuring of electric line.

Utility model content

For solving the deficiency that prior art exists, the utility model discloses the electric Parameter Measuring device and method of power transmission and distribution circuit, the utility model carries out real-time on-line measurement to electric line, it has energy Real-Time Monitoring line impedance, reasonable in design, practical, cost is low, the advantage that work efficiency is high.

For achieving the above object, concrete scheme of the present utility model is as follows:

The electric Parameter Measuring device of power transmission and distribution circuit, comprise multiple measuring unit, each measuring unit is all communicated with main station system by data concentrator, time synchronized is carried out by clock synchronization unit between measuring unit, measuring unit is corresponding measurement point synchronized phasor data under setting-up time is captured in same time point by a CT and current transformer and a PT and voltage transformer (VT), described measuring unit is also connected with protective current sensor with measurement current sensor by range switch circuit, utilize range switch circuit still can record corresponding waveform when circuit breaks down, image data is sent to main station system by data concentrator by measuring unit.

Described clock synchronization unit is used for providing clock accurately for measuring unit, comprises FPGA controller, time service module, constant-temperature crystal oscillator, optical transmitting set and optical receiver, described constant-temperature crystal oscillator is used for providing stable clock for FPGA controller, described FPGA controller communicates with time service module, time service module obtains the clock of measuring unit by time service antenna, time service module will be accurate to the time of second rank by serial ports, coordinate information is sent to FPGA controller, to be accurate to after other correct time of nanosecond is demarcated by Plush pulse signal and be sent to FPGA controller, clock signal is sent to measuring unit by optical transmitting set by FPGA controller again, described optical receiver is used for receiving the clock signal of extraneous standard when time service antenna erection is inconvenient and is sent to FPGA controller.

Described time service module is according to the one in application choice GPS pattern, Big Dipper pattern or this Three models of GPS+ Big Dipper pattern.

Described measuring unit comprises dsp controller, AD converter and network controller; Optical receiver is used for the clock signal that receive clock lock unit sends, described dsp controller communicates with network controller, network controller is W5100 type network interface chip, network controller and RJ45 interface communication, and RJ45 interface is by netting twine, WIFI or 3G correspondence with foreign country;

Described dsp controller and SD stick into Serial Communication; Dsp controller input end is also connected with AD converter, and the signal that AD converter receives is the line voltage distribution current-mode analog quantity that an outside CT and PT obtains.

Described dsp controller to the input of digital quantity by receiving after Phototube Coupling, to digital output by exporting after Phototube Coupling; Described dsp controller is also connected with optical receiver and optical transmitting set.

Described AD converter by range switch circuit and measurement CT with protect CT and be connected, measure CT to be connected with a road of AD converter by the first parallel circuit, first parallel circuit comprises two parallel units, and each parallel units comprises the amplifier and toggle switch that are in series; Measure CT and protect CT to be connected with the second parallel circuit respectively by toggle switch, the second parallel circuit is identical with the first parallel circuit structure.

Described multiple measuring unit is arranged on the two ends of power circuit respectively, and the measuring unit of the power circuit of every one end is all connected with main station system by data concentrator.

Measuring unit is for completing the parameter acquisition of electrical power distribution electric line, and this electric line parameter mainly comprises three-phase voltage and the current synchronization phasor data at circuit two ends.A clock synchronization unit can connect six measuring units, and as needed the more measuring unit of cascade, optical transmitting set is used for cascade measuring unit transmit clock signal.Measurement CT and protection CT is the secondary CT inside measurement mechanism, non-transforming plant primary CT.Here be not once the primary side of CT, but refer to the secondary electrical boundaries belonging to transforming plant primary electrical boundaries or control protective unit.

Power transmission and distribution circuit electric Parameter Measuring method: specific works step is as follows:

Step one: install and measure unit respectively at circuit two ends, obtain electric current, the voltage synchrophasor data at circuit two ends respectively, electric current, voltage synchrophasor data are sent to main station system by data concentrator;

Step 2: main station system receive that two ends measure with target phase angle time accurate, amplitude, frequency data storing;

Step 3: the positive sequence π type equivalent parameters and the zero sequence impedance that are calculated this circuit by the data at the circuit two ends recorded.

The concrete steps of described step one are:

(1-1) data collection station DPMU is arranged on circuit two ends as measuring unit;

(1-2) markers provided by GPS synchronous clock unit is put the synchronized phasor data of lower collection respective nodes at one time and transmits to main station system;

The concrete steps that the positive sequence π type equivalent parameters of described step 3 calculates are:

(3-1) employing sets up transmission line of electricity π type equivalent circuit based on distributed parameter model;

(3-2) according to phase component method, voltage and the electric current phasor of positive sequence is tried to achieve by the synchronizing voltage at circuit two ends and electric current phasor parameter;

The concrete steps that the zero sequence impedance of described step 3 calculates are:

(3-11) double back transmission line zero-sequence mutual inductance lumped parameter model is set up;

(3-12) residual voltage, the electric current at the circuit two ends recorded according to the measuring unit of the electric parameter measuring apparatus of circuit and obtain zero sequence self-impedance and zero sequence mutual impedance by the line admittance that open-circuit test obtains.

When the voltage of positive sequence and electric current phasor calculate: according to uniform charged ball, if known line length is l, the relation of head end positive sequence voltage and electric current and end positive sequence voltage and electric current that can obtain is such as formula shown in (1):

$\left[\begin{array}{c}{U}_1\\ I_1\end{array}\right]=\left[\begin{array}{cc}\cos \mathrm{\γl}& \mathrm{Zc}\sinh \mathrm{\γl}\\ \sinh \mathrm{\γl}& \cos \mathrm{\γl}\end{array}\right]\left[\begin{array}{c}{U}_2\\ I_2\end{array}\right]---\left(1\right)$

Circuit positive sequence propagation constant γ can be obtained by above formula _l, positive sequence wave impedance Z _cl:

$\left\{\begin{array}{c}{\mathrm{\γ}}_1=\frac{1}{l}\cos h^{-1}\frac{U_1{I}_1+U_2{I}_2}{U_1{I}_2+U_2{I}_1}\\ Z_{C1}=\sqrt{\frac{U_2^2-U_1^2}{I_2^2-I_1^2}}\end{array}\right.---\left(2\right)$

By the line propagation constant γ calculated _lwith wave impedance Z _clpositive sequence impedance and the admittance that can obtain transmission line of electricity are as follows:

Z _l＝Z _clγ _l(3)

$Y_1=\frac{{\mathrm{\γ}}_1}{Z_{c1}}---\left(4\right)$

In above-mentioned formula: l is the length of transmission line of electricity; U ₁for circuit head end positive sequence voltage; I _lfor circuit head end forward-order current; U ₂for line end positive sequence voltage; I ₂for line end forward-order current; γ _lfor electric transmission line positive sequence propagation constant; Z _clbe electric transmission line positive sequence wave impedance;

If positive sequence voltage and the forward-order current at synchronization transmission line of electricity two ends can be obtained, then obtain the positive order parameter of transmission line of electricity by formula (3) and formula (4), the positive order parameter of transmission line of electricity comprises: positive sequence resistance, forward-sequence reactance, positive sequence conductance, positive sequence susceptance.

Double back transmission line zero-sequence mutual inductance lumped parameter model: obtain:

$\left[\begin{array}{c}{U}_{a10}-U_{a20}\\ U_{b10}-U_{b20}\end{array}\right]=\left[\begin{array}{cc}{Z}_{a0}& Z_{m0}\\ Z_{m0}& Z_{b0}\end{array}\right]\left[\begin{array}{c}{I}_{a10}-U_{a10}\frac{Y_{a0}}{2}\\ I_{b10}-U_{b10}\frac{Y_{b0}}{2}\end{array}\right]---\left(5\right)$

Formula (5) is simplified,

$\left[\begin{array}{c}\mathrm{\Δ}{U}_{a0}\\ \mathrm{\Δ}{U}_{b0}\end{array}\right]=\left[\begin{array}{cc}{Z}_{a0}& Z_{m0}\\ Z_{m0}& Z_{b0}\end{array}\right]\left[\begin{array}{c}{I}_{a0}\\ I_{b0}\end{array}\right]---\left(6\right)$

Wherein, Δ U _a0=U _a10-U _a20; Δ U _b0=U _b10-U _b20;

$I_{a0}=I_{a10}-U_{a10}\frac{Y_{a0}}{2};I_{b0}=I_{b10}-I_{b10}\frac{Y_{b0}}{2}.$

In reality, in parallel erection double-circuit line, the self-impedance of two circuits is very close, i.e. Z _a0≈ Z _b0.By formula (6) double loop every kilometer zero sequence self-impedance and zero sequence mutual impedance are calculated as follows:

$Z_{a0}=Z_{b0}=\frac{1}{l}\frac{\mathrm{\Δ}{U}_{a0}{I}_{a0}-\mathrm{\Δ}{U}_{b0}{I}_{b0}}{{I_{a0}}^2-{I_{b0}}^2}---\left(7\right)$

$Z_{m0}=\frac{1}{l}\frac{\mathrm{\Δ}{U}_{a0}{I}_{b0}-\mathrm{\Δ}{U}_{b0}{I}_{a0}}{{I_{b0}}^2-{I_{a0}}^2}---\left(8\right)$

In above-mentioned formula: l is the length of double back transmission line; U _a10, U _a20be respectively circuit a head end residual voltage, circuit a end residual voltage; U _b10, U _b20be respectively circuit b head end residual voltage, circuit b end residual voltage; I _a10for circuit a head end zero-sequence current; I _b10for circuit b head end zero-sequence current; Z _a0for circuit a zero sequence self-impedance; Z _b0for circuit b zero sequence self-impedance; Z _m0for double loop zero-sequence mutual inductance; Y _a0for circuit a zero sequence admittance; Y _b0for circuit b zero sequence admittance.

Residual voltage, the electric current at circuit two ends all obtain by the measuring unit of the electric parameter measuring apparatus of circuit, line admittance obtains by open-circuit test, therefore, only need produce zero-sequence current at a wherein circuit of double loop, the Zero sequence parameter of double-circuit line can be measured.To produce when the mode of zero-sequence current comprises the compensation system, the line maintenance that excise a certain phase in short-term additional Injection Current and other artificially produce zero sequence conflicting mode.

The utility model, in reliability design process, takes into full account the factor affecting plant running.

In PCB design, adopt anti-interference device, use Transient Suppression Diode and voltage dependent resistor (VDR) to absorb surge voltage; At the noise that power unit adopts work mould choking coil to suppress power supply to bring; Use the undesired signal of the certain frequency ranges of filtering such as line filter; With the combination of the elements such as resistor, capacitor, inductor, the process such as bypass, absorption, isolation, filtering, decoupling are carried out to interference voltage or electric current.Concerning capacitor select and installing, the mode filtering height frequency interferences using high-quality tantalum electric capacity and ceramic condenser to coordinate.

In circuit layout, adopt the scheme of analog quantity and digital quantity being carried out isolating, adopt different Power supplies, reduce the mutual interference between device.Simultaneously by high-frequency component be subject to interfering component and carry out being separated layout.Device adopts the shielding case of high conductivity, high magnetic flux rate, the strong electromagnetic interference (EMI) produced when effectively can shield external switch action.The fastening foundation bolt of cabinet is added latex foam, vibration isolation rubber etc. to reach effectiveness in vibration suppression.

Host computer has the Storage and Processing function of data, and have the function being further analyzed data and processing, can carry out flexible configuration in conjunction with correlation computations, in addition, software has waveform Presentation Function, is conveniently shown by corresponding waveform.

The beneficial effects of the utility model:

1 the utility model adopts the synchronous phasor measurement terminal D PMU being specific to distribution system, improves real-time and the accuracy of distribution network data acquisition.

2 line parameter circuit value method for real-time measurement of the present utility model are more more accurate than conventional line parameter circuit value synchronizing calculation method, for systematic analysis provides accurate data basis.

3 can realize off-line, online two kinds of modes are run.

4 can preserve historical action, data.

Accompanying drawing explanation

Fig. 1 is device overall architecture of the present utility model;

Fig. 2 is clock synchronization unit structure of the present utility model;

Fig. 3 is collecting unit structural drawing of the present utility model;

Fig. 4 is passage bridge design drawing of the present utility model;

Fig. 5 is line parameter circuit value instrumentation plan of the present utility model;

Fig. 6 is upper computer software interface of the present utility model;

Fig. 7 is positive sequence parameter model of the present utility model;

Fig. 8 (a)-Fig. 8 (b) is double-circuit line Zero sequence parameter model of the present utility model.

Embodiment:

Below in conjunction with accompanying drawing, the utility model is described in detail:

The electric Parameter Measuring device of a kind of power transmission and distribution circuit, mainly comprises master station computer and supporting novel synchronous phasor measuring set.This novel synchronous phasor measuring set is made up of three parts such as clock synchronization unit, measuring unit, data concentrators.Wherein clock synchronization unit configuration high precision time service chip, for measuring unit provides clock accurately, optical fiber is utilized to carry out between measuring unit with clock synchronization unit synchronous, measuring unit is connected by Ethernet with data concentrator, and data concentrator is responsible for carrying out the work such as computing, process, analysis, forwarding to data.

Clock synchronization unit is primarily of part compositions such as FPGA controller, time service module, constant-temperature crystal oscillator, optical transmitting sets.

The main task of FPGA controller is the clock in holdout device, carries out segmenting the synchronous acquisition pulse generating 12.8KHz on the one hand to GPS pps pulse per second signal, on the other hand, and the accurate clock of holdout device when GPS loses clock signal because of environment or other factors.In order to ensure the precision of clock, use constant-temperature crystal oscillator to provide stable clock for FPGA controller, in device is kept time, performance can improve 50 times compared with conventional active crystal oscillator.Controller herein selects FPGA controller to be the advantage considering that the corresponding speed of FPGA controller is fast, use common CPU, need current operating data to be pressed into storehouse after external trigger occurs, reprocessing respective interrupt process function, the time used when different time trigger due to this process is different, therefore can bring relatively large deviation to clock.

Time service module is UM220 module, and obtain this utility model device clock by it, the time service precision of this module can reach 100ns, and this clock accuracy can meet the requirement to phase angle measurement completely.The pattern of this module output time information is the form of serial data+pulse signal, by serial ports, the information such as time, coordinate being accurate to second rank is sent to FPGA controller, is accurate to other correct time of nanosecond by Plush pulse signal and demarcates, ensure the time definitely accurately.This time service module compatible with GPS and the Big Dipper two kinds of time service modes, user can according to application choice GPS pattern, Big Dipper pattern, this Three models of GPS+ Big Dipper pattern.

Measuring unit is made up of parts such as dsp controller, AD converter, network controller, number connect test circuit, optical receiver, optical transmitting sets.

The TMS320F28335 type high-performance 32-bit processor that dsp controller adopts TIX to produce, inner integrated hardware floating point processing unit (FPU) of this processor, greatly can improve the arithmetic capability to floating data, with this can solve calculate phase angle time Fast Fourier Transform (FFT) (FFT) in a large amount of floating-point operations.In addition this processor has abundant external interface and can communicate with multiple external unit, and wherein SCIA is responsible for and the mutual time scale information of FPGA, time deviation information etc.; SCIB is responsible for being communicated with external host by MAX232 or RS485; SPI is responsible for being stored into Serial Communication with internal mass SD card, is responsible for the memory function of data; General address controls to communicate with data bus and Ethernet, data is transmitted by Ethernet, and the phase angle information calculated, amplitude information are sent to server host.

Network controller, the every 20ms of dsp controller calculates phase angle and the amplitude of a three-phase voltage and electric current, and the data calculated are sent to server end by Ethernet.Device uses W5100 type network interface chip, the integrated ICP/IP protocol stack of this chip internal, its agreement supported has TCP, UDP, IPv4, ICMP, ARP, IGMP, PPPoE etc., uses this chip to design by reduced data communication structure, removes the migration process of ICP/IP protocol from.Communication mode between chip and processor has SPI and parallel two kinds.Consider the content of the aspects such as the data volume of transmission, ensure that transmission speed DSP and network chip adopt the communication mode of parallel bus, the highest network transfer speeds can arrive 100Mpbs in this mode, can meet the rate request of device to network service.Network external interface adopts RJ45 interface, transmission mode can select netting twine, WIFI, 3G etc. by this interface.The upload frequencies user of data can arrange (1,5,10,25,50) secondary/second flexibly.

Analog to digital converter, as synchronized phase measurement device, has very high requirement to the precision of analog acquisition with the control gathering the moment, in this device, therefore adopt 16 8 Channel Synchronous sampling analog to digital converter AD7606.This chip internal contains second order frequency overlapped-resistable filter, can effectively filtering high frequency interference by this wave filter, makes the phase angle information of measurement more accurate.In addition, this chip can complete the absolute synchronization sampling of 8 passages, can ensure the absolute unification in each phase acquisition moment like this, reduce phase angle error from project organization.Because the clock of FPGA in device is the most accurate, therefore the beginning transition trigger signal of AD converter is provided by FPGA, after AD conversion completes can there is saltus step in its Busy signal, and dsp controller begins through 16 parallel bus after Busy signal being detected reads translation data.

In range switch circuit, consider the input range of measuring-signal, still can record corresponding waveform when circuit breaks down, concerning AD converter when fault measuring-signal can not expire partially, on circuit, therefore need the problem of consideration hyperchannel switching.The enlargement factor of amplifying circuit can be configured by toggle switch; user can realize measuring the configuration of CT with protection CT by adjustment toggle switch; the automatic switchover of range can also be realized for protection CT; now; same road signal is gathered by two-way AD; K1, K3, K6 are closed, and K2, K4, K5 disconnect, and can realize the dynamic range adjustment process to CT1.When input signal is less, for ensureing the acquisition precision of signal, processor adopts the value of ADC2 as signal value, when input signals are large, processor adopts the value of ADC1 as signal, can ensure the acquisition precision at signal like this, can ensure again the acquisition range of signal.

Storer is described as, device can by the data that collect by spi bus stored in Large Copacity SD card, user can according to the capacity of the time stored and sample frequency option and installment SD.8 tunnels analogy amount signals gather at every turn needs the byte taken to be 16Byte, amounts to 20Byte after adding time scale information.

Data volume=20*256*50*60*60=92160000Byte=878.9Mbyte hourly.

Data concentrator primary responsibility collects the image data of a harvester, and is further analyzed data and calculates, and stores after completing calculating in this locality, as requested data can be forwarded to each main website according to the requirement of specifying simultaneously.Data concentrator is the industrial control host with embedded system, the processor corresponding according to the size configure of calculated amount.

Parameter Measuring device as electric in Fig. 1 power transmission and distribution circuit, mainly comprises the part compositions such as clock synchronization unit, data concentrator, measuring unit, UPS power supply unit.

Clock synchronization unit configuration high precision time service chip, for harvester provides clock accurately; Measuring unit is responsible for the collection of voltage and current signal and is calculated corresponding vector data; Measuring unit is connected by optical fiber with clock unit, and therefore each unit can obtain correct time information; Data concentrator is responsible for carrying out the work such as computing, process, analysis, forwarding, storage, display to data.

If Fig. 2 clock synchronization unit is primarily of part compositions such as FPGA, time service module, constant-temperature crystal oscillator, optical transmitting sets.

As Fig. 3 time service module, the clock of device is obtained by UM220 module, and the time service precision of this module can reach 100ns, and this clock accuracy can meet the requirement to phase angle measurement completely.The pattern of this module output time information is the form of serial data+pulse signal, by serial ports, the information such as time, coordinate being accurate to second rank is sent to FPGA, is accurate to other correct time of nanosecond by Plush pulse signal and demarcates, ensure the time definitely accurately.This time service module compatible with GPS and the Big Dipper two kinds of time service modes, user can according to application choice GPS pattern, Big Dipper pattern, this Three models of GPS+ Big Dipper pattern.

As Fig. 3 measuring unit is made up of parts such as DSP, AD converter, network controller, number connect test circuit, optical receiver, optical transmitting sets.

As Fig. 4 considers the input range of measuring-signal, still can record corresponding waveform when circuit breaks down, concerning AD when fault measuring-signal can not expire partially, on circuit, therefore need the problem of consideration hyperchannel switching.In figure, the enlargement factor of amplifying circuit can be configured by toggle switch; user can realize measuring the configuration of CT with protection CT by adjustment toggle switch; the automatic switchover of range can also be realized for protection CT; now; same road signal is gathered by two-way AD; K1, K3, K6 are closed, and K2, K4, K5 disconnect, and can realize the dynamic range adjustment process to CT1.ADC1 is switched to when the signal value that ADC2 collects exceedes setting threshold value, signal is gathered, be specially: when input signal is less than setting threshold value, for ensureing the acquisition precision of signal, processor adopts the value of ADC2 as signal value, and when input signal is greater than setting threshold value, processor adopts the value of ADC1 as signal, the acquisition precision at signal can ensured like this, the acquisition range of signal can ensured again.

If Fig. 5 is line parameter circuit value On-line Measuring Method schematic diagram.The plant stand part that novel synchronous phasor measuring set is adopted as electric line on-line measurement device is arranged on circuit two ends; The markers provided by GPS is put the synchronized phasor data of lower collection respective nodes at one time and is transmitted to main station system; Server receive that two ends measure with data such as target phase angle, amplitude, frequencies time accurate, and to store; By two ends three-phase voltage and the analysis of current synchronization phasor data, the positive sequence π type equivalent parameters calculating this circuit and zero sequence impedance.

As Fig. 6 upper computer software has the Storage and Processing function of data, have the function being further analyzed data and processing, in addition, software has waveform Presentation Function, is conveniently shown by corresponding waveform.

Positive sequence parameter line model is as shown in Figure 7: according to uniform charged ball, if known line length is l, the relation of head end positive sequence voltage and electric current and end positive sequence voltage and electric current that can obtain is such as formula shown in (1):

$\left[\begin{array}{c}{U}_1\\ I_1\end{array}\right]=\left[\begin{array}{cc}\cos \mathrm{\γl}& \mathrm{Zc}\sinh \mathrm{\γl}\\ \sinh \mathrm{\γl}& \cos \mathrm{\γl}\end{array}\right]\left[\begin{array}{c}{U}_2\\ I_2\end{array}\right]---\left(1\right)$

Circuit positive sequence propagation constant γ can be obtained by above formula _l, positive sequence wave impedance Z _cl:

$\left\{\begin{array}{c}{\mathrm{\γ}}_1=\frac{1}{l}\cos h^{-1}\frac{U_1{I}_1+U_2{I}_2}{U_1{I}_2+U_2{I}_1}\\ Z_{C1}=\sqrt{\frac{U_2^2-U_1^2}{I_2^2-I_1^2}}\end{array}\right.---\left(2\right)$

By the line propagation constant γ calculated _lwith wave impedance Z _clpositive sequence impedance and the admittance that can obtain transmission line of electricity are as follows:

Z _l＝Z _clγ _l(3)

$Y_1=\frac{{\mathrm{\γ}}_1}{Z_{c1}}---\left(4\right)$

In above-mentioned formula: l is the length of transmission line of electricity; U ₁for circuit head end positive sequence voltage; I _lfor circuit head end forward-order current; U ₂for line end positive sequence voltage; I ₂for line end forward-order current; γ _lfor electric transmission line positive sequence propagation constant; Z _clbe electric transmission line positive sequence wave impedance;

If positive sequence voltage and the forward-order current at synchronization transmission line of electricity two ends can be obtained, then obtained the positive order parameter of transmission line of electricity by formula (3) and formula (4).

Double back transmission line zero-sequence mutual inductance lumped parameter model is as shown in Fig. 8 (a)-8 (b): obtained by figure:

$\left[\begin{array}{c}{U}_{a10}-U_{a20}\\ U_{b10}-U_{b20}\end{array}\right]=\left[\begin{array}{cc}{Z}_{a0}& Z_{m0}\\ Z_{m0}& Z_{b0}\end{array}\right]\left[\begin{array}{c}{I}_{a10}-U_{a10}\frac{Y_{a0}}{2}\\ I_{b10}-U_{b10}\frac{Y_{b0}}{2}\end{array}\right]---\left(5\right)$

Formula (5) is simplified,

$\left[\begin{array}{c}\mathrm{\Δ}{U}_{a0}\\ \mathrm{\Δ}{U}_{b0}\end{array}\right]=\left[\begin{array}{cc}{Z}_{a0}& Z_{m0}\\ Z_{m0}& Z_{b0}\end{array}\right]\left[\begin{array}{c}{I}_{a0}\\ I_{b0}\end{array}\right]---\left(6\right)$

Wherein, Δ U _a0=U _a10-U _a20; Δ U _b0=U _b10-U _b20;

$I_{a0}=I_{a10}-U_{a10}\frac{Y_{a0}}{2};I_{b0}=I_{b10}-I_{b10}\frac{Y_{b0}}{2}.$

In reality, in parallel erection double-circuit line, the self-impedance of two circuits is very close, i.e. Z _a0≈ Z _b0.By formula (6) double loop every kilometer zero sequence self-impedance and zero sequence mutual impedance are calculated as follows:

$Z_{a0}=Z_{b0}=\frac{1}{l}\frac{\mathrm{\Δ}{U}_{a0}{I}_{a0}-\mathrm{\Δ}{U}_{b0}{I}_{b0}}{{I_{a0}}^2-{I_{b0}}^2}---\left(7\right)$

$Z_{m0}=\frac{1}{l}\frac{\mathrm{\Δ}{U}_{a0}{I}_{b0}-\mathrm{\Δ}{U}_{b0}{I}_{a0}}{{I_{b0}}^2-{I_{a0}}^2}---\left(8\right)$

In above-mentioned formula: l is the length of double back transmission line; U _a10, U _a20be respectively circuit a head end residual voltage, circuit a end residual voltage; U _b10, U _b20be respectively circuit b head end residual voltage, circuit b end residual voltage; I _a10for circuit a head end zero-sequence current; I _b10for circuit b head end zero-sequence current; Z _a0for circuit a zero sequence self-impedance; Z _b0for circuit b zero sequence self-impedance; Z _m0for double loop zero-sequence mutual inductance; Y _a0for circuit a zero sequence admittance; Y _b0for circuit b zero sequence admittance.

Residual voltage, the electric current at circuit two ends all obtain by the measuring unit of the electric parameter measuring apparatus of circuit, line admittance obtains by open-circuit test, therefore, only need produce zero-sequence current at a wherein circuit of double loop, the Zero sequence parameter of double-circuit line can be measured.To produce when the mode of zero-sequence current comprises the compensation system, the line maintenance that excise a certain phase in short-term additional Injection Current and other artificially produce zero sequence conflicting mode.

By reference to the accompanying drawings embodiment of the present utility model is described although above-mentioned; but the restriction not to the utility model protection domain; one of ordinary skill in the art should be understood that; on the basis of the technical solution of the utility model, those skilled in the art do not need to pay various amendment or distortion that creative work can make still within protection domain of the present utility model.

Claims (7)

1. the electric Parameter Measuring device of power transmission and distribution circuit, it is characterized in that, comprise multiple measuring unit, each measuring unit is all communicated with main station system by data concentrator, time synchronized is carried out by clock synchronization unit between measuring unit, measuring unit is corresponding measurement point synchronized phasor data under setting-up time is captured in same time point by a CT and current transformer and a PT and voltage transformer (VT), described measuring unit is also connected with protective current sensor with measurement current sensor by range switch circuit, utilize range switch circuit still can record corresponding waveform when circuit breaks down, image data is sent to main station system by data concentrator by measuring unit.

2. the electric Parameter Measuring device of power transmission and distribution circuit as claimed in claim 1, it is characterized in that, described clock synchronization unit is used for providing clock accurately for measuring unit, comprises FPGA controller, time service module, constant-temperature crystal oscillator, optical transmitting set and optical receiver, described constant-temperature crystal oscillator is used for providing stable clock for FPGA controller, described FPGA controller communicates with time service module, time service module obtains the clock of measuring unit by time service antenna, time service module will be accurate to the time of second rank by serial ports, coordinate information is sent to FPGA controller, to be accurate to after other correct time of nanosecond is demarcated by Plush pulse signal and be sent to FPGA controller, clock signal is sent to measuring unit by optical transmitting set by FPGA controller again, described optical receiver is used for receiving the clock signal of extraneous standard when time service antenna erection is inconvenient and is sent to FPGA controller.

3. the electric Parameter Measuring device of power transmission and distribution circuit as claimed in claim 2, it is characterized in that, described time service module is according to the one in application choice GPS pattern, Big Dipper pattern or this Three models of GPS+ Big Dipper pattern.

4. the electric Parameter Measuring device of power transmission and distribution circuit as claimed in claim 1, it is characterized in that, described measuring unit comprises dsp controller, AD converter and network controller; Optical receiver is used for the clock signal that receive clock lock unit sends, described dsp controller communicates with network controller, network controller is W5100 type network interface chip, network controller and RJ45 interface communication, and RJ45 interface is by netting twine, WIFI or 3G correspondence with foreign country; Described dsp controller and SD stick into Serial Communication; Dsp controller input end is also connected with AD converter, and the signal that AD converter receives is the line voltage distribution current-mode analog quantity that an outside CT and PT obtains.

5. the electric Parameter Measuring device of power transmission and distribution circuit as claimed in claim 4, is characterized in that, described dsp controller to the input of digital quantity by receiving after Phototube Coupling, to digital output by exporting after Phototube Coupling; Described dsp controller is also connected with optical receiver and optical transmitting set.

6. the electric Parameter Measuring device of power transmission and distribution circuit as claimed in claim 4, it is characterized in that, described AD converter by range switch circuit and measurement CT with protect CT and be connected, measure CT to be connected with a road of AD converter by the first parallel circuit, first parallel circuit comprises two parallel units, and each parallel units comprises the amplifier and toggle switch that are in series; Measure CT and protect CT to be connected with the second parallel circuit respectively by toggle switch, the second parallel circuit is identical with the first parallel circuit structure.

7. the electric Parameter Measuring device of power transmission and distribution circuit as claimed in claim 1, it is characterized in that, described multiple measuring unit is arranged on the two ends of power circuit respectively, and the measuring unit of the power circuit of every one end is all connected with main station system by data concentrator.