CN101354825A - Method and device for wireless ultra-high voltage current measurement - Google Patents

Abstract

A wireless ultra-high voltage current measurement method and device, which obtains a measurement signal of a high-voltage line current through a current sensor on the high potential side, outputs it through an effective value processing circuit and an analog-to-digital conversion circuit, and controls the acquisition and processing of the measurement signal through a computer on the high potential side wireless transmission. On the ground potential side, the signal is received by the radio receiving device, and then processed by the computer on the ground potential side and then output. The invention solves the technical problems of bulky volume, heavy weight, high price and relatively poor operation accuracy and stability existing in the prior art. The invention has flexible control and transmission, convenient use, simple structure and easy installation. The frequency response range is wide, and it can measure the grid current transient state and high frequency and large current, which complies with the development needs of power metering and relay protection automation and microcomputerization.

Description

Method and device for wireless ultra-high voltage current measurement

technical field

The invention relates to a current measurement method and device for an ultra-high voltage power transmission and transformation line, in particular to a wireless ultra-high voltage current measurement method and device.

Background technique

With the rise of the voltage level of the power system and the continuous increase of the transmission capacity, the shortcomings of the traditional ultra-high voltage current measurement device are becoming more and more prominent.

The traditional current transformer is an electromagnetic induction current transformer (CT). Its primary winding is a power line cable, and the external circuit of the secondary winding is connected to a measuring instrument or a relay protection and automatic control device. The structure is similar to that of a transformer. Its iron core is wound with primary and secondary windings, and the information is transmitted from the primary side to the secondary side by means of electromagnetic coupling between the primary and secondary windings. Between the iron core and the winding, and between the primary and secondary windings, there is an insulation structure with sufficient electric strength to ensure that all low-voltage equipment is isolated from high voltage. Current transformer has high measurement accuracy, the industrial application has reached 0.2%, and it can run stably in the power system for a long time. However, the high-voltage bus bar of the electromagnetic induction current transformer and the secondary coil are coupled through an iron core. The insulation structure between them is complex, bulky, and heavy. Some ultra-high-voltage current measuring devices even weigh several tons, which is not only difficult to manufacture. , It is difficult to use and install, occupies a large area, and is expensive. The cost increases exponentially with the voltage level. For conventional oil-immersed current transformers, the price of 500kV products is twice as high as that of 300kV products. The 5A or 1A output of the electromagnetic induction current transformer must adopt optical isolation technology to connect with the computer, which is inconvenient for control and transmission. In addition, the electromagnetic induction current transformer has an iron core and is non-linear. When a short circuit occurs in the power system, the high-amplitude short-circuit current will saturate the transformer, and the output secondary current will be seriously distorted, resulting in misalignment of protection and causing power system failure. serious accident. Moreover, the waveform distortion caused by transformer saturation has poor frequency band response characteristics, narrow frequency band, and poor high-frequency response of the system, which makes it difficult to realize the new fast protection based on high-frequency transient components. The secondary circuit of the electromagnetic induction current transformer cannot be open circuited, and there is a danger of open circuit on the low voltage side. Electromagnetic induction current transformers generally use insulating oil isolation to solve the insulation problem, and there are inevitably dangers such as flammability and explosion.

There are many types of optoelectronic current transformers (OCT), which are roughly divided into two types: active type and passive type. The sensing head part of the active type has an electronic circuit that requires a power supply, and the sensing head part of the passive type does not need a power supply. Both have the advantages of the traditional electromagnetic current transformer. The active photoelectric current transformer is newly developed, and its structure is relatively simple. The laser light source is used to send the light energy from the ground potential side to the high potential side through the optical fiber, and then the photoelectric conversion device converts the light energy into electrical energy, and after passing through the power supply stabilization circuit, it supplies power to the electronic circuit of the sensor head. All electronics are used in the sensor head on the high potential side. The high-potential side uses an air-core coil (Rogowski coil) to convert the bus current into an analog voltage signal, which is converted into a digital signal by an analog-to-digital conversion circuit (A/D), and then converted into an optical signal by an electro-optical conversion (LED) circuit, and then passed through An insulated optical fiber sends the optical signal to the ground potential side. On the ground potential side, the optical signal is converted into a digital electrical signal by a photoelectric conversion device (PIN), which is used for relay protection and electric energy measurement. Where an analog quantity is required, a digital-to-analog conversion circuit (D/A) can be used to convert the digital quantity to an analog quantity. However, photoelectric current transformers are relatively poor in operation accuracy and long-term stability due to the birefringence of optical materials caused by temperature and vibration. At present, there is no photoelectric current transformer applied to ultra-high voltage lines above 1000KV.

Contents of the invention

The purpose of the present invention is to provide a wireless ultra-high voltage current measurement method and device, which solves the technical problems of bulky, heavy, expensive, or relatively poor operation accuracy and stability existing in the prior art.

Technical scheme of the present invention is:

A wireless ultra-high voltage current measurement method, which is special in that the implementation steps of the method include:

(I) Measure the high-voltage line current on the high-potential side and transmit it by radio signal:

(i) Obtain the measurement signal of the high-voltage line current through the current sensor;

(ii) After signal processing such as rectification, filtering, and amplification, the measurement signal of the high-voltage line current becomes an analog current signal on the high potential side;

(iii) After the analog current signal on the high potential side is processed by analog-to-digital conversion, it is converted into a digital current signal on the high potential side;

(iv) Control the collection of measurement signals on the high potential side and the emission of measurement signals on the high potential side through the computer on the high potential side; shoot out

(II) Receive the high-voltage line measurement signal on the ground potential side:

(i) Receive the radio digitized current signal emitted from the high potential side through the radio receiving device;

(ii) The received radio digitized current signal is processed by the computer on the ground potential side and then output.

The above-mentioned received radio digitized current signal is processed by the computer on the ground potential side and then output is a digital signal directly, or the received radio digitized current signal is processed by the computer on the ground potential side and then output means that it is converted into an analog signal by a digital-to-analog conversion circuit Then output.

Above-mentioned step (1) also comprises the power source that obtains high-potential side measurement transmitting device; The step that obtains high-potential side measurement transmitting device power comprises: at first draw power supply by current transformer from high-voltage line, then through the rectification of power signal processing circuit, After filtering and voltage stabilization processing, the power supply of the high-potential side measurement transmitter is obtained.

The above-mentioned step of obtaining the power supply of the measuring and transmitting device at the high potential side further includes: balancing the power supply voltage of the measuring and transmitting device at the high potential side through a rechargeable battery connected in parallel with the power signal processing circuit. When the current of the high-voltage line is low, the high-potential side measurement transmitter can be powered by a rechargeable battery for balancing.

A wireless ultra-high voltage current measurement device, comprising a high potential side device, a high potential side power supply 2 and a ground potential side device, the special feature is: the high potential side device is a high potential side measurement transmitter 1, the The high potential side measurement transmitting device 1 comprises a current sensor 101 connected in series in the high-voltage line or arranged outside the high-voltage line, an effective value processing circuit 102 connected to the output end of the current sensor 101, and an analog-to-digital conversion connected to the output end of the effective value processing circuit 102 Circuit 103, connected to the high potential side computer 104 at the output end of the analog-to-digital conversion circuit 103, connected to the radio conversion transmitting device 105 at the output end of the high potential side computer 104; the ground potential side device is the ground potential side receiving device 3, and the The ground potential side receiving device 3 includes a radio receiving device 301 that receives the radio conversion transmitter 105 signal, and is connected to a ground potential side computer 302 at the output end of the radio receiving device 301; the effective value processing circuit 102 connected to the output end of the current sensor 101 includes rectification circuit, filter circuit and amplification processing circuit.

The above-mentioned high potential side power supply 2 includes a current transformer 201 connected to the high-voltage line, and a power signal processing circuit 202 connected to the output end of the current transformer 201; the power signal processing circuit 202 includes a rectifying circuit, a filter circuit and a voltage stabilizing circuit .

The above-mentioned power signal processing circuit 202 can also be connected in parallel with a rechargeable battery 203 to balance the power supply voltage.

The computer 104 on the high potential side and the computer 302 on the ground potential side may use a single chip microcomputer or a data signal processor DSP or the like.

The output end of the computer 302 on the ground potential side may be connected with an RS-232 output port, an RS-485 output port or a digital-to-analog conversion circuit 303 .

The present invention has the following advantages:

(1) The steady-state accuracy of the measurement is high. The invention utilizes the electromagnetic current transformer for measurement, so it can obtain higher measurement accuracy and can run stably for a long time in the power system.

(2) Since the signal transmission between the high potential side and the ground potential side is radio transmission and reception, there is no tangible physical connection, and the high voltage end is naturally insulated from the ground, so a huge high voltage insulation device is omitted, and the insulation reliability is high. Safe to use.

(3) Simple structure, small size, light weight, easy to use, transport and install, and low cost. The weight of the high-voltage side of the present invention is generally less than 1 kilogram, while the oil-immersed current transformer of the same voltage level is 5.3 meters high and weighs 2300 kilograms.

(4) There is no tangible physical connection between the high potential side and the ground potential side, and has good insulation performance, which can ensure that the high voltage circuit and the secondary circuit are completely isolated electrically, and there is no risk of open circuit high voltage on the ground potential side, and the anti-interference ability is strong.

(5) The invention has a wide frequency response range, can measure harmonics on high-voltage power lines, and can also measure power grid current transients, high-frequency large currents, and direct currents.

(6) The present invention integrates current digital measurement, wireless data transmission, ultra-high-voltage line stealing electricity, high-voltage line and ground insulation, and multi-interface output technologies. The control and transmission are flexible and convenient, and the measurement has nothing to do with the voltage level. Electricity metering and relay automation, the development demand of microcomputerization.

Description of drawings

Fig. 1 is a block diagram of the structure and principle of the high potential side measuring and transmitting device of the present invention.

Fig. 2 is a structural principle block diagram of the receiving device at the ground potential side of the present invention.

Description of drawings: 1- measuring and transmitting device on high potential side, 101- current sensor, 102- effective value processing circuit, 103- analog-to-digital conversion circuit, 104- computer on high potential side, 105- radio conversion transmitting device; 2- High potential side power supply, 201-current transformer, 202-power signal processing circuit, 203-rechargeable battery; 3-ground potential side receiving device, 301-radio receiving device, 302-ground potential side computer, 303-digital-to-analog conversion circuit .

Detailed ways

The implementation steps of the wireless ultra-high voltage current measurement method of the present invention are as follows:

(1.) Measure the high-voltage line current on the high-potential side and transmit it by radio signal:

(1.1) On the high potential side, the high-precision current sensor 101 is used to obtain the measurement signal of the current of the high-voltage line bus. See Figure 1.

(1.2) The measurement signal of the high-voltage line current is converted into an analog current signal on the high potential side after being rectified, filtered, amplified and other signal processed by the effective value processing circuit 102 .

(1.3) After the analog current signal on the high potential side is processed by analog-to-digital conversion, it is converted into a digital current signal on the high potential side.

(1.4) The high potential side digital current signal is input to the high potential side computer 104, and the high potential side computer 104 controls the acquisition of the measurement signal on the high potential side.

(1.5) High potential side The measurement signal on the high potential side output by the computer 104 is converted into a radio signal by the radio conversion transmitter 105 and transmitted. The high potential side computer 104 can control the transmission of the measurement signal on the high potential side. The insulation between the high-potential side and the ground-potential side is an open space without tangible physical connection, which is a kind of natural insulation.

(2.) Measure the power supply of the transmitting device on the high potential side:

Firstly, the high-voltage power is drawn from the high-voltage line through the current transformer 201, and then the signal processing such as rectification, filtering, and voltage stabilization by the power signal processing circuit 202 is performed to obtain the power supply for the measuring and transmitting device on the high potential side. The rechargeable battery 203 connected in parallel with the power signal processing circuit 202 is used to balance the power supply voltage of the high potential side measurement transmitter. When there is no current in the circuit, the rechargeable battery 203 can also supply power to the measuring and transmitting device 1 at the high potential side.

(3.) Receive the high-voltage line measurement signal on the ground potential side:

On the ground potential side, the radio receiving device 301 receives the radio digitized current signal, see Fig. 2, and directly outputs the digital signal after being processed by the computer 302 on the ground potential side, which is used for relay protection and electric energy measurement; or the computer 302 on the ground potential side outputs The digital signal is converted into an analog signal output by a digital-to-analog conversion circuit, and then converted into a current and voltage signal required for work.

The wireless ultra-high voltage current measuring device of the present invention is mainly composed of a high-potential-side measuring and transmitting device 1 , a high-potential-side power supply 2 and a ground-potential-side receiving device 3 .

Referring to FIG. 1 , the current sensor 101 of the high-potential-side measuring and transmitting device 1 is connected in series in the high-voltage line, or arranged outside the bus bar of the high-voltage line. The output of the current sensor 101 is connected to the effective value processing circuit 102 , and the output of the effective value processing circuit 102 is connected to the high potential side computer 104 through the analog-to-digital conversion circuit 103 . The computer 104 on the high potential side can adopt a single chip microcomputer or a data signal processor DSP or the like. The output of the high potential side computer 104 is converted into a radio signal by the radio conversion transmitting device 105 and transmitted.

The high potential side power supply 2 includes a current transformer 201 connected to the high voltage line, and its output is connected to a power signal processing circuit 202 . The power signal processing circuit 202 may be connected in parallel with a rechargeable battery 203 with a balanced power voltage.

Referring to Fig. 2, the receiving device 3 on the ground potential side, the output of the radio receiving device 301 corresponding to the radio conversion transmitting device 105 is connected to the ground potential side computer 302, and the output of the ground potential side computer 302 has RS-232, RS-485 The output port or the digital-to-analog conversion circuit 303 outputs.

The computer 104 on the high potential side and the computer 302 on the ground potential side of the present invention can use a single chip microcomputer or a data signal processor DSP or the like.

Claims (9)

1. a wireless ultra-high pressure current measuring method is characterized in that, the performing step of this method comprises:

(I) measuring the high-tension line electric current at hot side also launches with the radio signal mode:

(i) obtain the measuring-signal of high-tension line electric current by current sensor;

(ii) the measuring-signal of high-tension line electric current after comprising that rectification, filtering, amplifying signal are handled, becomes the hot side analog current signal;

(iii) the hot side analog current signal is converted to hot side digital current signal after analog-to-digital conversion process;

The (iv) emission of the measuring-signal of the collection of the measuring-signal by hot side computer control hot side and hot side; The measuring-signal of the hot side of hot side computing machine output is converted to radiodigital galvanic current signal and launches through the radio conversion emitter;

(II) receive the high-tension line measuring-signal at the earth potential side joint:

(i) receive the radiodigital galvanic current signal that hot side is launched by radio system;

(ii) the radiodigital galvanic current signal that receives is exported after by earth potential side Computer Processing.

2. wireless ultra-high pressure current measuring method according to claim 1, it is characterized in that, the radiodigital galvanic current signal of described reception by earth potential side Computer Processing after output be directly to export digital signal, or the radiodigital galvanic current signal of described reception by earth potential side Computer Processing after output be meant through D/A converting circuit is converted to simulating signal after again and export.

3. wireless ultra-high pressure current measuring method according to claim 1 and 2 is characterized in that, measuring the high-tension line signal and launch at hot side in the described step (I) also comprises and obtain the power supply that hot side is measured emitter; The described hot side that obtains is measured the step of emitter power supply and is comprised: at first by current transformer by drawing power supply in the high-tension line, after rectification, filtering, the voltage stabilizing of power supply signal treatment circuit are handled, obtain the power supply that hot side is measured emitter then.

4. wireless ultra-high pressure current measuring method according to claim 3, it is characterized in that the described step of obtaining hot side measurement emitter power supply comprises: come the balance hot side to measure the supply voltage of emitter by the rechargeable battery in parallel with the power supply signal treatment circuit.

5. device of realizing the described wireless ultra-high pressure current measuring method of claim 1, comprise the hot side device, hot side power supply (2) and earth potential side device, it is characterized in that: described hot side device is that hot side is measured emitter (1), described hot side is measured emitter (1) and is comprised the current sensor (101) that is series in the high-tension line or is arranged at the high-tension line outside, be connected to the effective value treatment circuit (102) of current sensor (101) output terminal, be connected to the analog to digital conversion circuit (103) of effective value treatment circuit (102) output terminal, be connected to the hot side computing machine (104) of analog to digital conversion circuit (103) output terminal, be connected to the radio conversion emitter (105) of hot side computing machine (104) output terminal; Described earth potential side device is an earth potential side joint receiving apparatus (3), described earth potential side joint receiving apparatus (3) comprises the radio system (301) that receives radio conversion emitter (105) signal, is connected to the earth potential side computing machine (302) of radio system (301) output terminal; The described effective value treatment circuit (102) that is connected to current sensor (101) output terminal comprises rectification circuit, filtering circuit and amplification treatment circuit.

6. wireless ultra-high pressure current measurement mechanism according to claim 5, it is characterized in that: described hot side power supply (2) comprises the current transformer (201) that is connected with high-tension line, is connected to the power supply signal treatment circuit (202) of current transformer (201) output terminal; Described power supply signal treatment circuit (202) comprises rectification circuit, filtering circuit and mu balanced circuit.

7. according to claim 5 or 6 described wireless ultra-high pressure current measurement mechanisms, it is characterized in that: described power supply signal treatment circuit (202) is parallel with the rechargeable battery (203) of balance supply voltage.

8. wireless ultra-high pressure current measurement mechanism according to claim 7 is characterized in that: described hot side computing machine (104) and earth potential side computing machine (302) are single-chip microcomputer or data signal processor DSP.

9. wireless ultra-high pressure current measurement mechanism according to claim 8 is characterized in that: the output terminal of described earth potential side computing machine (302) is connected to RS-232 output port, RS-485 output port or D/A converting circuit (303).

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