A kind of quench-detection circuit of high-temperature superconducting magnet
Technical field
The present invention relates to a kind of quench-detection circuit at high-temperature superconducting magnet.More specifically, the present invention relates to a kind of circuit whether high-temperature superconducting magnet quench (quench) takes place that is used to detect.
Background technology
Superconducting power device in the electric system will run into such as various dynamic processes such as system short-circuit faults, bear the impact of Short-Circuit High Current, out-of-balance current, wherein the superconducting magnet in the superconducting power device may be because of bearing excessive short-circuit current effect quench.The quench of superconducting magnet has not only changed the electric parameter of superconducting power device, also will produce bad influence to safe, stable, the economical operation of electric system.
For high-temperature superconducting magnet self, high-temperature superconducting magnet only could embody superconducting characteristic when satisfying certain conditions, in case condition is destroyed, high-temperature superconducting magnet will quench.The basic process of quench is the process that the electromagnetic energy that will store changes heat energy into, the heat energy of transformation mainly by external move can resistance and coil in normal district absorb.On the one hand since quench always from a bit, pass through ohm heat and heat conduction then to external diffusion, the location that changes normal state the earliest into is the longest in the time of Ohmic heating state, temperature rise is the highest, local overheating may be burnt insulation or be blown conductor, the while quench also may produce high voltage and cause insulation breakdown, the high-temperature superconducting magnet quench is accompanied by high-temperature superconductor excess current and heating, if untimely taking measures shifted energy stored in the high temperature superconductor coil, these energy will dissipate by the form of high temperature superconductor coil with heat energy, and serious local temperature rise may damage high-temperature superconducting magnet.
Superconducting magnet comprises high-temperature superconducting magnet and cryogenic magnet, in general, the quench propagation speed of high-temperature superconducting magnet is than slow two to three orders of magnitude of cryogenic magnet, the normal region velocity of propagation is too slow, be easy to make the local focus that forms of high-temperature superconducting magnet, heat can only spread in very little scope, thereby causes the high-temperature superconducting magnet permanent damage.So the quench detection of high-temperature superconducting magnet is bigger than cryogenic magnet difficulty, require higher.
The quench detection method of using both at home and abroad has temperature rise detection, pressure detection, ultrasound examination, flow rate detection and voltage detecting.What wherein be most widely used is voltage detecting, the bridge circuit detection method is to propose on the basis of voltage detecting method, simply be easy to realize but have the problem of noise, and outer meeting resistance can consume part energy, the active power detection method can solve the problem of noise, also without outer meeting resistance, Fig. 1 shows active power method testing circuit, superconducting coil L
1=L
2, resistance r
1And r
2Be two sections resistance after the superconducting coil quench.Definition power P=(v
1-v
2) i, wherein v
1And v
2Be superconducting coil L
1With superconducting coil L
2Voltage during quench, i are the electric current of superconducting coil.Not during quench, resistance r
1With resistance r
2Be zero, so the power P value also is zero.After the quench, power P=(r
1-r
2) i
2, promptly except resistance r
1=r
2Situation, quench all can detect by the power P value.Resistance r
1=r
2Be general non-existent special circumstances, can not consider usually.
Detection technique involved in the present invention is that the active power detection method that has now proposed is improved, use this testing circuit can quite good detecting to the quench signal of high-temperature superconducting magnet, prevent that high-temperature superconducting magnet from being burnt.
Summary of the invention
In view of the foregoing, the purpose of this invention is to provide a kind of quench-detection circuit at high-temperature superconducting magnet.
Concrete detection method is: per two high temperature superconductor coils are compared as one group, and under the normal condition, output voltage signal is zero, and when any one high temperature superconductor coil generation quench, output voltage is greater than zero.Output signal is isolated with linear optical coupling, produce a differential voltage through differential operational amplifier.Wherein quench all might take place in any one high temperature superconductor coil, and the differential voltage of generation may take absolute value to negative value on the occasion of also being negative value, with the quench signal be converted on the occasion of, use for the back circuit.Adopt the active power detection method, produce power P=(v by analog multiplier
1-v
2) i, wherein v
1And v
2Be the voltage after the high temperature superconductor coil quench, can detect the variation of electric current and voltage simultaneously, testing result is more accurate.Through second order Butterworth low-pass filter circuit, produce output signal with the reference voltage back of making comparisons, i.e. quench signal, the output result is a high level or low level.When the high-temperature superconducting magnet quench, will send high level signal and give digital signal processor, thereby digital signal processor action holding circuit makes magnet avoid damaging.
High-temperature superconducting magnet involved in the present invention is in series by a plurality of high temperature superconductor coils; per two high temperature superconductor coils compare as one group; the output terminal of every group of comparator circuit is carried out parallel connection; output quench signal; the quench signal is input to holding circuit, thereby makes high-temperature superconducting magnet avoid damaging.
Therefore, the present invention proposes a kind of quench-detection circuit of high-temperature superconducting magnet, it is characterized in that comprising high-temperature superconducting magnet, correcting circuit, optical coupling isolation circuit, calculus of differences amplifying circuit, absolute value circuit, analog multiplication circuit, current-voltage conversion circuit, filtering circuit, comparator circuit and output circuit, described high-temperature superconducting magnet by the series connection of at least two high temperature superconductor coils reach into, and have the accurate adjustable resistance VR that is in series with high temperature superconductor coil
1And/or accurate adjustable resistance VR
2, described accurate adjustable resistance VR
1And/or accurate adjustable resistance VR
2With power resistor R
1And/or power resistor R
2Series connection, described high temperature superconductor coil through correcting circuit and optical coupling isolation circuit after as the input of calculus of differences amplifying circuit, absolute value circuit takes absolute value to the output of calculus of differences amplifying circuit, the output of absolute value circuit is as the input of analog multiplication circuit, analog multiplication circuit detects the variation of the voltage and current on each high temperature superconductor coil simultaneously, analog multiplication circuit is output as current signal, be converted to the input of voltage signal through current-voltage conversion circuit as filtering circuit, filtering circuit adopts second order Butterworth low-pass filter, eliminate the noise in the circuit, through behind the comparator circuit as the output of quench-detection circuit.
The present invention has the following advantages:
1, can well solve the problem of noise in the quench detection, improve the accuracy that detects.The detected quench signal influence of signal that may be interfered from the high-temperature superconducting magnet 1, because the voltage that produces during high-temperature superconducting magnet 1 quench is very little, general criterion is that the quench voltage on every centimetre of superconducting tape is uV, so must take effective measures the quench signal is differentiated from undesired signal.In the present invention, the voltage that produces on high temperature superconductor coil 2 that two external diameters is identical and the high temperature superconductor coil 3 is made comparisons, and through optical coupling isolation circuit 5, calculus of differences amplifying circuit 6 and filtering circuit 10 can well reduce the influence of undesired signal.
2, circuit structure is simple, is easy to realize that circuit related among the present invention is formed by analog device, and speed is fast, is easy to realize.
3, the present invention has added correcting circuit 4 between high-temperature superconducting magnet 1 and optical coupling isolation circuit 5, and accurate adjustable resistance VR promptly connects
1With accurate adjustable resistance VR
2, can reduce the difference that causes output voltage between high temperature superconductor coil 2 and the high temperature superconductor coil 3 because of the difference of technique for coiling or wire rod itself like this, make testing result more accurate.
Description of drawings
Fig. 1 is the circuit diagram of active power method testing circuit;
Fig. 2 is the quench detection schematic flow sheet at high-temperature superconducting magnet of the present invention;
Fig. 3 shows the synoptic diagram according to correcting circuit 4 of the present invention, optical coupling isolation circuit 5 and calculus of differences amplifying circuit 6;
Fig. 4 shows the synoptic diagram of analog multiplication circuit 8 of the quench-detection circuit of high-temperature superconducting magnet of the present invention.
Embodiment
The present invention is further described below in conjunction with accompanying drawing.
Fig. 2 shows the quench detection synoptic diagram at high-temperature superconducting magnet, be made of following several parts: high-temperature superconducting magnet 1, high temperature superconductor coil 2, high temperature superconductor coil 3, correcting circuit 4, optical coupling isolation circuit 5, calculus of differences amplifying circuit 6, absolute value circuit 7, analog multiplication circuit 8, current-voltage conversion circuit 9, filtering circuit 10, comparator circuit 11 and output circuit 12, wherein high-temperature superconducting magnet 1 is composed in series by high-temperature superconductor coils such as high temperature superconductor coil 2, high temperature superconductor coils 3.With high temperature superconductor coil 2 and high temperature superconductor coil 3 is example, concrete embodiment is: high temperature superconductor coil 2 and high temperature superconductor coil 3 process correcting circuits 4 and optical coupling isolation circuit 5 backs are as the input of calculus of differences amplifying circuit 6, the output of 7 pairs of calculus of differences amplifying circuits 6 of absolute value circuit takes absolute value, the output of absolute value circuit 7 is as the input of analog multiplication circuit 8, analog multiplication circuit 8 can detect the variation of voltage and current on high temperature superconductor coil 2 and the high temperature superconductor coil 3 simultaneously, analog multiplication circuit 8 is output as current signal, be converted to the input of voltage signal through current-voltage conversion circuit 9 as filtering circuit 10, filtering circuit 10 adopts second order Butterworth low-pass filter, eliminate the noise in the circuit, through of the output of comparator circuit 11 backs as quench-detection circuit.Wherein absolute value circuit 7, current-voltage conversion circuit 9, filtering circuit 10 and comparator circuit 11 are mimic channels of using always, mainly introduce correcting circuit 4, optical coupling isolation circuit 5, calculus of differences amplifying circuit 6 and analog multiplication circuit 8 below.
Fig. 3 shows correcting circuit 4, optical coupling isolation circuit 5 and calculus of differences amplifying circuit 6.The design of this circuit is in order to detect high temperature superconductor coil L
1With high temperature superconductor coil L
2The voltage difference that produces after the quench.High temperature superconductor coil L ideally
1With high temperature superconductor coil L
2Be two identical high temperature superconductor coils of external diameter, owing in winding process, making high temperature superconductor coil L because of the reason of technique for coiling or superconducting wire coil itself
1With high temperature superconductor coil L
2Electrical specification fine distinction appears, when measuring, can produce the trickle difference of measuring voltage, just can well address this problem after adding correcting circuit.As high temperature superconductor coil L
1With high temperature superconductor coil L
2When being in the quench state and applying identical voltage, reconcile accurate adjustable resistance VR
1With accurate adjustable resistance VR
2, make output voltage identical, can eliminate the error that produces in the winding process like this.Wherein accurate adjustable resistance VR
1With accurate adjustable resistance VR
2Power generally below 1W, power resistor R
1With power resistor R
2To accurate adjustable resistance VR
1With accurate adjustable resistance VR
2Shield accurate adjustable resistance VR when preventing that power is excessive
1With accurate adjustable resistance VR
2Burnt.Regulate accurate adjustable resistance VR
1With accurate adjustable resistance VR
2Make linear optical coupling element U
1With linear optical coupling element U
2Be operated in the optimum linear stage, thus reflection high temperature superconductor coil L
1With high temperature superconductor coil L
2On voltage.R
3And R
4Be linear optical coupling element U
1With linear optical coupling element U
2Pull-up resistor, according to the principle of work of linear optical coupling, linear optical coupling element U
1With linear optical coupling element U
2Output terminal will produce respective output voltages.U
3Employing is the general purpose instrument amplifier INA128 of low power consumption high-precision, external boundary's resistance R between the pin 8 of the pin 1 of INA128 and INA128
7Can be provided with its gain, in the scope of gain is generally selected ten times.Resistance R
5And resistance R
6For the current-limiting resistance of differential operational amplifier INA128 input pin 2 and input pin 3, generally get 10k, capacitor C
1And capacitor C
2Be filter capacitor, generally get 0.1u, the Port1 end is calculated the output terminal of amplifying circuit for difference unit.
Fig. 4 shows analog multiplication circuit 8, and the Port2 end is the output of absolute value circuit 7, analog multiplier U
4Model be RC4200, wherein RC4200 has three input ends, is respectively input current pin 1, input current pin 5 and input current pin 8, output terminal is an output current pin 4.The wherein output that is input as absolute value circuit 7 of input current pin 1, input current pin 8 be input as the high temperature superconductor coil current i ,+5 volts of direct supplys provide input current for input current pin 5.Capacitor C
3And capacitor C
4Be filter capacitor, generally get 0.1u, resistance R
8Be current-limiting resistance.Analog multiplier RC4200 is output as current signal, through current-voltage conversion circuit 9 current signal is converted to voltage signal, as the input of filtering circuit 10.U wherein
5Be operational amplifier, resistance R
9Be transfer resistance, capacitor C
5And capacitor C
6Be filter capacitor, Port 3 ends are input ends of filtering circuit 10.
Invention has been described according to specific exemplary embodiment herein.It will be conspicuous carrying out suitable replacement to one skilled in the art or revise under not departing from the scope of the present invention.Exemplary embodiment only is illustrative, rather than to the restriction of scope of the present invention, scope of the present invention is by appended claim definition.