CN105116213A - On line measuring device for voltage and current differential signals - Google Patents
On line measuring device for voltage and current differential signals Download PDFInfo
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Abstract
An on line measuring device for voltage and current differential signals comprises a hollow coil and a voltage transducer, wherein the hollow coil is connected with an A/D converter through a low-pass filter circuit and outputs a first differential signal of a bus current after collecting a signal, and the first differential signal is subjected to high-frequency interference elimination through the low-pass filter circuit, and then is conveyed to the A/D converter. The voltage transducer is connected with the A/D converter through the low-pass filter circuit and outputs a first differential signal of a bus voltage after collecting a signal, and the first differential signal is subjected to high-frequency interference elimination through the low-pass filter circuit, and then is conveyed to the A/D converter. The A/D converter is connected with a temperature sensor and is connected with a microprocessor, wherein the microprocessor is connected with a merging unit, and the merging unit is connected with a PC machine. According to the device provided by the invention, the first differential signals of the voltage and the current in the circuit are output after measuring, and are provided for the PC machine to perform fault location or to calculate a transition resistance, and the device is more accurate than a traditional method of taking a difference value as a quotient to solve a differential.
Description
Technical field
A kind of electric current and voltage differential signal of the present invention on-line measurement device, for measuring the once differentiation signal of electric current and voltage in electric system.
Background technology
The front end of measuring and protection device mainly mutual inductor in current electric system, in order to measuring voltage current signal, supply relay protection or measuring system use.As the electronic mutual inductor progressively promoted, the signal that electronic current mutual inductor (ECT) based on air core coil and electronic type voltage transformer (EVT) sensing head based on capacitance current type principle export is the differential value of primary side measured signal, for restoring tested voltage and current signal, generally integral element is added in electronic mutual inductor, bring the regular hour to postpone and phase offset thus, and frequency response bandwidth sum increase high-pressure side power consumption can be reduced.In addition, no matter be analog integration or digital integration, currently all there is certain defect.For analog integration technology, there is error in traditional analog device and theoretical value, the drift of amplifier, the leakage of electric capacity and loss, time float, temperature is floated etc., and problem all can affect last precision, cannot fundamentally overcome these problems to the research of analog device.For digital integration techniques, current defect is that high frequency response is poor, is therefore used for power frequency component and measures in short-term.
The output of air core coil and capacitive transducer is differential signal, if do not add integral element, directly utilizes its differential to export and carries out observing and controlling and protection, then can improve the accuracy of measuring accuracy and relay protection to a great extent.The research of related direction that had some scholars to carry out at present: wherein; Chinese patent CN201210049142.8 proposes " a kind of modified R-L modal distance protection algorism based on differential signal ", utilizes the once differentiation value of electric current and voltage and the second differential value of electric current can realize fault localization and distance protection function accurately.Similar differential signal purposes is also widely studied gradually; as Xu Yan, king increase equality people the tranformer protection based on transformer voltage current differential waveform characteristic that proposes, the differential under-voltage protection as D.C. high voltage transmission new road main protection relies on and detects voltage, current differential value and voltage magnitude level and realize protection.For the impedance algorithms based on the differential equation, directly obtain differential signal and can save iteration or Integration Solving, both can save time and also can improve measuring accuracy, increase sensitivity and the accuracy of relay equipment.
Although progressively promoting for the research of differential signal, but differential signal du/dt required in engineering at present, usual employing difference does the principle of business, voltage sample value is utilized to do difference, business is again with sampling interval duration, although sampling number raising measuring accuracy can be increased by reducing sampling interval, but the differential signal that the mode of this (u1-u2)/(t1-t2) does not obviously have electronic mutual inductor sensing head to export is accurate, degree of accuracy is also limited by sampling time interval, so a kind of electric current and voltage differential signal of current urgent need high precision online measuring device.
Summary of the invention
Problems existing in measuring for current electric current and voltage differential signal, comprise lack a kind of directly can obtain differential signal high precision measuring system, adopt difference to do commercial law accuracy is poor, difference do business's precision by sampling time interval restriction, have passed through integral element in the measurements for the protection of the signal of algorithm and there is the problems such as error.The invention provides a kind of electric current and voltage differential signal on-line measurement device; the once differentiation signal of the electric current and voltage after this measurement device in output circuit; supply PC carries out fault localization or solves transition resistance; to carry out protection act; the accuracy doing the method that business differentiates than traditional difference is high, also without the need to considering the error that integral element is brought.The differential signal provided effectively can simplify some fault localization using the differential equation or Distance Protection Algorithms, improves sensitivity and the accuracy of relay equipment; The electronic mutual inductor structure comparing measuring voltage current signal wants simple.
The technical solution adopted in the present invention is:
A kind of electric current and voltage differential signal on-line measurement device, comprise air core coil, voltage sensor, described air core coil connects A/D converter by low-pass filter circuit, the once differentiation signal of bus current is exported after air core coil collection signal, this once differentiation signal is eliminated after high frequency interference through low-pass filter circuit, is delivered to A/D converter.
Described voltage sensor connects A/D converter by low-pass filter circuit, exports the once differentiation signal of busbar voltage after voltage sensor collection signal, and this once differentiation signal is eliminated after high frequency interference through low-pass filter circuit, is delivered to A/D converter.A/D converter connects temperature sensor.Described A/D converter connects microprocessor, and microprocessor connects merge cells, and merge cells connects PC.
A/D converter is used for simulating signal to transfer digital signal to, and deliver in microprocessor through optical fiber, microprocessor, for adjusting signal magnitude, carries out error compensation according to temperature sensor, finally delivers to merge cells, delivers to PC use by merge cells.
Described microprocessor is controlled by merge cells, and microprocessor connects a synchronous optical fiber, for receiving synchronizing signal; Microprocessor connects a single data optical fiber, for sending the electric current and voltage differential signal collected; Microprocessor connects a cable, provides working power by merge cells.
The advantages such as described air core coil is Rogowski coil, has measurement range wide, and frequency bandwidth is high, and volume is little.
Described voltage sensor equivalent electrical circuit is: electric capacity C
1resistance in series R ground connection, the resistance size of resistance R is relative to electric capacity C
1can ignore, if the voltage in bus L is u (t), then electric capacity C
1in the electric current that flows through be equivalent to the once differentiation signal of voltage u (t).
The bandwidth Design of described low-pass filter circuit is 400Hz, has superposed DC level on the input signals, before filter network, has added attenuation network, added the input range of A/D converter.
Described temperature sensor uses the TMP006 in TI series, carries out error compensation in the microprocessor, thus effectively resist because ambient temperature changes the error interference brought by measuring exterior temperature change to signal.
Described A/D converter 4 selects A/D7685, and precision is 16, after receiving the control signal that microprocessor transmits, 2 tunnel simulating signals is converted to digital signal and flows to microprocessor.
Described microprocessor is DSP56200, microprocessor is for receiving the sampling pulse signal transmitted by merge cells, after capturing sampling pulse rising edge, control A/D converter to sample, 2 circuit-switched data transmitted by A/D converter scale up the frame format of rear composition regulation, then by electro-optical conversion module, then merge cells is passed to.Electro-optical conversion module Main Function is that the electric signal in microprocessor is converted to light signal, directly uses for merge cells, and microprocessor through cable power supply, directly sends the signal collected by merge cells from data optical fiber.
Described microprocessor needs two paths of data to adjust in proportion, and the differential signal exported all needs to adjust in proportion.The scale-up factor that electric current once differentiation signal need reduce is the coefficient of mutual inductance M of air core coil, and the scale-up factor that voltage once differentiation signal need reduce is RC
1.
Described merge cells to be gone forward side by side row relax for the data receiving multi-microprocessor, sends follow-up PC to according to IEC61850-9 Hierarchy format.Merge cells sends sampling pulse signal control microprocessor and sends synchronizing signal to A/D converter, the signal received is sent to PC simultaneously.
A kind of electric current and voltage differential signal On-line Measuring Method, air core coil and voltage sensor are as primary side sensing head, measure and export the once differentiation signal of voltage and current in bus L, low-pass filter circuit eliminates high-frequency interferencing signal, temperature sensor is by electric current once differentiation signal subdifferential exporting again, after two-way simulating signal is converted to digital signal by A/D converter reception synchronous acquisition signal, be transported in microprocessor and carry out ratio adjustment, temperature error compensation, after microprocessor adjustment signal, merge cells is delivered to through data optical fiber, merge cells gives PC more further.
A kind of electric current and voltage differential signal of the present invention on-line measurement device, technique effect is as follows:
1), for the relay protection algorithm set up based on the differential equation as the improvement R-L modal distance protection algorism etc. exported based on differential; direct acquisition differential signal can save iteration or Integration Solving; eliminate error and delay that integral element brings; both can save time and also can improve measuring accuracy, increase sensitivity and the accuracy of relay equipment.
2), do relative to difference the method that business differentiates, designed electric current and voltage differential signal on-line measurement device precision is higher, it is more accurate to export, difference is done the differentiate value in two moment of needs of business and is done subtraction division arithmetic, designed system only needs to do multiplication operation in the microprocessor, and calculated amount is less.
3), three scale-up factors in microprocessor: the coefficient of mutual inductance M of air core coil, the electric capacity C of voltage sensor
1, precision resister resistance R, all less by temperature disturbance, add temperature sensor again in addition, changed the temperature error compensation realized in the microprocessor measurement result by measuring tempeature, therefore designed device can resist temperature disturbance to a certain degree, and suitable for outdoors uses.
4), designed device can measure and the once differentiation signal of output voltage and the once differentiation signal of electric current simultaneously, compares independent measurement and to calculate two differential signal costs low, and structure is wanted simply.
5) the once differentiation value of what, air core coil and voltage sensor exported is electric current and voltage; to differentiate method relative to difference business in Practical Project; because there is not integral element so precision is higher in the differential signal of direct measurement; for the protective relaying device set up based on the differential equation; direct acquisition differential signal can save iteration or Integration Solving; both can save time and also can improve measuring accuracy, increase sensitivity and the accuracy of relay equipment.The temperature sensor added can carry out error compensation to measurement result in the microprocessor according to temperature variation, thus makes device have the effect of opposing temperature variation interference.A kind of electric current and voltage differential signal of the present invention on-line measurement device, directly can export the once differentiation signal of tested electric current and voltage, in electric measurement and relay protection, have vital role.
Accompanying drawing explanation
Fig. 1 is structural representation of the present invention.
Fig. 2 is low-pass filter circuit schematic diagram in the present invention.
Embodiment
A kind of electric current and voltage differential signal on-line measurement device, structure is as shown in Figure 1: comprise air core coil 1, voltage sensor 2, described air core coil 1 connects A/D converter 4 by low-pass filter circuit 3, the once differentiation signal of bus current is exported after air core coil 1 collection signal, this once differentiation signal, after low-pass filter circuit 3 eliminates high frequency interference, is delivered to A/D converter 4.
Described voltage sensor 2 connects A/D converter 4 by low-pass filter circuit 3, exports the once differentiation signal of busbar voltage after voltage sensor 2 collection signal, and this once differentiation signal, after low-pass filter circuit 3 eliminates high frequency interference, is delivered to A/D converter 4.
A/D converter 4 connects temperature sensor 6.Signal is carried out to the error compensation of relevant temperature after temperature sensor 6 measuring tempeature in microprocessor 5.Employ temperature sensor 6 and carry out monitor temperature, carry out real-Time Compensation according to temperature variation, thus avoid temperature disturbance to the full extent, be therefore suitable for outdoor use.
Described A/D converter 4 connects microprocessor 5, and microprocessor 5 connects merge cells 7, and merge cells 7 connects PC 8.A/D converter 4, for simulating signal is transferred to digital signal, is delivered in microprocessor 5 through optical fiber, and microprocessor 5, for adjusting signal magnitude, carries out error compensation according to temperature sensor 6, finally delivers to merge cells 7, delivers to PC 8 use by merge cells 7.
Air core coil 1 and voltage sensor 2, as primary side sensing head, are measured and export the once differentiation signal of electric current and voltage in bus L.The once differentiation signal of what air core coil 1 measured rear output is bus current, the once differentiation signal of busbar voltage that what voltage sensor 2 measured rear output is, two differential signals adjusting size in proportion in microprocessor 5, and realize the error compensation to temperature variation.
Described microprocessor 5 is controlled by merge cells 7, and microprocessor 5 connects a synchronous optical fiber 9, for receiving synchronizing signal; Microprocessor 5 connects a single data optical fiber 10, for sending the electric current and voltage differential signal collected; Microprocessor 5 connects a cable 11, provides working power by merge cells 7.Merge cells 7 controls microprocessor 5 and sends synchronizing signal, controls 2 road A/D converters 4 and carries out synchronized sampling.Microprocessor 5 needs the digital signal to 2 tunnels gather proportionally to adjust, to ensure to output signal the electric current and voltage differential value for required.
Described air core coil 1 is Rogowski coil, the advantages such as have measurement range wide, frequency bandwidth is high, and volume is little, if the current signal in bus L is i (t), air core coil mutual inductor coefficient is M, then the signal exported is:
Described voltage sensor 2 equivalent electrical circuit is: electric capacity C
1resistance in series R ground connection.If the voltage in bus L is u (t), then the resistance size of resistance R is relative to electric capacity C
1can ignore, electric capacity C
1in the electric current that flows through be equivalent to the once differentiation signal of voltage, so the voltage on resistance R exports be:
The bandwidth Design of described low-pass filter circuit 3 is 400Hz, and superposed DC level on the input signals, before filter network, added attenuation network, added the input range of A/D converter 4, circuit diagram as shown in Figure 2.
Described temperature sensor 6 uses the TMP006 in TI series, carries out error compensation, thus effectively resist because ambient temperature changes the error interference brought by measuring exterior temperature change in microprocessor 5 to signal.
Described A/D converter 4 selects A/D7685, and precision is 16, after receiving the control signal that microprocessor 5 transmits, 2 tunnel simulating signals is converted to digital signal and flows to microprocessor 5.
Described microprocessor 5 is DSP56200, microprocessor 5 is for receiving the sampling pulse signal transmitted by merge cells 7, after capturing sampling pulse rising edge, control A/D converter 4 to sample, 2 circuit-switched data transmitted by A/D converter 4 scale up the frame format of rear composition regulation, then by electro-optical conversion module, then pass to merge cells 7, microprocessor 5 is powered through cable 11 by merge cells 7, directly sends the signal collected from data optical fiber 10.Electro-optical conversion module adopts HFBR1414 element, realizes electro-optical conversion.Described microprocessor 5 needs two paths of data to adjust in proportion, and from formula (1), (2), the differential signal exported all needs to adjust in proportion.The scale-up factor that electric current once differentiation signal need reduce is the coefficient of mutual inductance M of air core coil 1, and the scale-up factor that voltage once differentiation signal need reduce is RC
1.
Described merge cells 7 controls microprocessor 5 by sending sampling pulse signal, makes it send synchronizing signal to A/D converter 4, the signal received is sent to PC 8 simultaneously.Merge cells 7 plays the effect connecting sensing head and follow-up PC 8, and power supply and transmission synchronizing signal are to microprocessor 5, and synchronous optical fiber 9 sends synchronizing signal, and data optical fiber 10 receives the signal that conversion comes.
Apparatus of the present invention are mainly used in measuring nose signal, for fault localization, solve the purposes such as transition resistance, so can be unified in other coding in PC 8 to carry out subsequent arithmetic.
A kind of electric current and voltage differential signal On-line Measuring Method, air core coil 1 and voltage sensor 2 are as primary side sensing head, measure and export the once differentiation signal of voltage and current in bus L, low-pass filter circuit 3 eliminates high-frequency interferencing signal, temperature sensor 6 is by electric current once differentiation signal subdifferential exporting again, A/D converter 4 receives after two-way simulating signal is converted to digital signal by synchronous acquisition signal, be transported in microprocessor 5 and carry out ratio adjustment, temperature error compensation, after microprocessor 5 adjusts signal, merge cells 7 is delivered to through data optical fiber 10, merge cells 7 gives PC 8 more further.Because A/D converter 4 directly gathers the differential signal of a sensing head output; not containing links such as integrations; so output signal has high precision; can be used in the multiple relay protection algorithm based on the differential equation; the various protection algorism of effective simplification, also can directly use as a part for relay protection or fault location device.Temperature sensor measurement also carries out error compensation in microprocessor 5, and device can be allowed to resist temperature disturbance to a certain extent, and therefore apparatus of the present invention are suitable for outdoor use.
Merge cells 7:MergingUnit, is called for short MU.Merging and synchronous process are carried out to the electric parameters that mutual inductor transmits, and the digital signal after process is transmitted to according to specific format the device that bay device uses.Merge cells 7 is interface arrangements of electronic current, voltage transformer (VT).Merge cells 7 achieves sharing and digitizing of process layer data to a certain extent, and it is as following the digital substation interval layer of IEC61850 standard, the Data Source of station level equipment.Concrete model has: southern auspicious relay protection PCS-221 and south are from PSMU602 etc.
Claims (10)
1. an electric current and voltage differential signal on-line measurement device, comprise air core coil (1), voltage sensor (2), it is characterized in that, described air core coil (1) connects A/D converter (4) by low-pass filter circuit (3), the once differentiation signal of bus current is exported after air core coil (1) collection signal, this once differentiation signal, through low-pass filter circuit (3), is delivered to A/D converter (4); Described voltage sensor (2) connects A/D converter (4) by low-pass filter circuit (3), the once differentiation signal of busbar voltage is exported after voltage sensor (2) collection signal, this once differentiation signal is eliminated after high frequency interference through low-pass filter circuit (3), is delivered to A/D converter (4); A/D converter (4) connects temperature sensor (6); Described A/D converter (4) connects microprocessor (5), and microprocessor (5) connects merge cells (7), and merge cells (7) connects PC (8); A/D converter (4) is for transferring digital signal to simulating signal, deliver in microprocessor (5), microprocessor (5) is for adjusting signal magnitude, error compensation is carried out according to temperature sensor (6), finally deliver to merge cells (7), deliver to PC (8) by merge cells (7) and use.
2. a kind of electric current and voltage differential signal on-line measurement device according to claim 1, it is characterized in that, described microprocessor (5) is controlled by merge cells (7), microprocessor (5) connects a synchronous optical fiber (9), for receiving synchronizing signal; Microprocessor (5) connects a single data optical fiber (10), for sending the electric current and voltage differential signal collected; Microprocessor (5) connects a cable (11), provides working power by merge cells (7).
3. a kind of electric current and voltage differential signal on-line measurement device according to claim 1, it is characterized in that, described air core coil (1) is Rogowski coil.
4. a kind of electric current and voltage differential signal on-line measurement device according to claim 1, it is characterized in that, described voltage sensor (2) equivalent electrical circuit is: electric capacity C1 resistance in series R ground connection.
5. a kind of electric current and voltage differential signal on-line measurement device according to claim 1, it is characterized in that, the bandwidth Design of described low-pass filter circuit (3) is 400Hz, has superposed DC level on the input signals, before filter network, has added attenuation network.
6. a kind of electric current and voltage differential signal on-line measurement device according to claim 1, it is characterized in that, described temperature sensor (6) is the TMP006 in TI series, and temperature sensor (6) for carrying out error compensation to signal by measuring exterior temperature change in microprocessor (5).
7. a kind of electric current and voltage differential signal on-line measurement device according to claim 1, it is characterized in that, described microprocessor (5) is DSP56200, microprocessor (5) is for receiving the sampling pulse signal transmitted by merge cells (7), after capturing sampling pulse rising edge, control A/D converter (4) to sample, 2 circuit-switched data that A/D converter (4) transmits are scaled up the frame format of rear composition regulation, then by electro-optical conversion module, pass to merge cells (7) again, microprocessor (5) is powered through cable (11) by merge cells (7), the signal collected directly is sent from data optical fiber (10).
8. adopt the electric current and voltage differential signal On-line Measuring Method as any one electric current and voltage differential signal on-line measurement device of claim 1 ~ 7, it is characterized in that, air core coil (1) and voltage sensor (2) are as primary side sensing head, measure and export the once differentiation signal of voltage and current in bus (L), low-pass filter circuit (3) eliminates high-frequency interferencing signal, temperature sensor (6) is by electric current once differentiation signal subdifferential exporting again, after two-way simulating signal is converted to digital signal by A/D converter (4) reception synchronous acquisition signal, be transported in microprocessor (5) and carry out ratio adjustment, temperature error compensation, after microprocessor (5) adjustment signal, merge cells (7) is delivered to through data optical fiber (10), merge cells (7) gives PC (8) more further.
9. a kind of electric current and voltage differential signal On-line Measuring Method as claimed in claim 8, is characterized in that, the application in the relay protection system set up based on the differential equation and fault localization.
10. a kind of electric current and voltage differential signal On-line Measuring Method as claimed in claim 8, is characterized in that, the application in the multiple relay protection algorithm based on the differential equation.
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| CN105548769A (en) * | 2016-01-13 | 2016-05-04 | 江苏省电力公司电力科学研究院 | Relay protection action delay time grading test system and method |
| CN106093547A (en) * | 2016-08-04 | 2016-11-09 | 贵州电网有限责任公司电力科学研究院 | Rogowski coil current transformer measuring device and method based on auxiliary coil correction |
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