CN104407200B - An open fault transient current sensor - Google Patents

Abstract

The invention discloses an open-type fault transient current sensor, which comprises: a first semi-circular body, a wire is wound from the head end of the first semi-circular body to its tail end according to the first winding direction, and then from the first semi-circular body The tail end of the half ring body is wound back to its head end according to the first winding direction; for the second half ring body, the head end of the first half ring body is spliced with the head end of the second half ring body, and the tail end of the first half ring body end and the tail end of the second half-ring body to form a complete circle; the wire is wound from the head end of the second half-ring body to the tail end in the second winding direction opposite to the first winding direction, Then wind back to its head end from the tail end of the second half-ring body according to the second winding direction; the wires wound on the first half-ring body and the second half-ring body all have a winding starting point and a terminal end, both The terminal terminals are connected to each other, and the two starting terminals are output terminals. The open-type fault transient current sensor of the present invention is easy to install, and eliminates the influence of the disturbing magnetic field in the vertical direction.

Description

An open fault transient current sensor

technical field

The invention relates to the field of transmission line fault detection, in particular to a transient current sensor.

Background technique

Transmission line fault transient current traveling wave contains a large amount of fault information, which is the basis of transmission line fault diagnosis. At present, flexible coils are commonly used in fault current sensors, but their disadvantages are that they are expensive and difficult to install. PCB Rogowski coils (Rogowski coils made of printed circuit boards) have excellent characteristics such as small size, light weight, and high accuracy.

The problems of PCB Rogowski coils in the field of fault current detection mainly focus on how to resist interference. In practical applications, because it is on the power line, in addition to the adjacent phase wires, there may be other interference magnetic fields in the space. The magnetic field generated by other interference sources can be decomposed into a component parallel to the plane where the PCB Rogowski coil skeleton is located, and a component B _Z perpendicular to it. The influence of the parallel component on the PCB Rogowski coil is the same as that of the adjacent phase wires, and the integral result is 0, so only the influence of the magnetic field B _Z in the vertical direction needs to be considered, as shown in Figure 1.

B _Z is parallel to the section where each small turn of the PCB Rogowski coil is located, so no corresponding induced electromotive force will be generated in the small turns, but the small turns are helically wound on the entire coil skeleton, forming a ring-like The solenoid advances helically along the ring shape of the frame, and after a circle, an equivalent large turn along the direction of the circle is formed, as shown in Figure 2 .

Since B _Z is perpendicular to the plane where the large wire turns are located, when B _Z changes with time, the magnetic flux passing through the large wire changes accordingly and generates an induced electromotive force e _Z in the PCB Rogowski coil. Although there is only one turn of the large wire turn, the area of the large wire turn is usually much larger than the cross-sectional area of the small wire turn. significant error. Therefore, in actual use, it is necessary to consider adding a loop L to the PCB Rogowski coil to avoid the interference of the vertical magnetic field _BZ . The plane of the loop L is parallel to the plane where the PCB Rogowski coil skeleton is located, as shown in Figure 3.

As shown in Figure 4, the radius of the circle surrounded by the _loop is R, the equivalent radius of the large wire is _Req , the induced electromotive force generated by B _Z in the _loop is e, and the final output induced electromotive force is e ′ _Z , then e′ _Z is equal to the sum of e _times and e _Z. If R is equal _{to Req} , since the direction of the current in the _loop is opposite to that of the equivalent large coil, then e and e _Z are equal in magnitude and opposite in direction, and the two cancel each other out, and e′ _Z is zero.

However, considering the convenience of device installation in actual use, it is necessary to adopt the structural design of double semi-circular rings to synthesize the entire coil. The structure of the above scheme is inconvenient to arrange the loop of the entire large coil.

The publication number is CN102445588A, and the publication date is May 9, 2012. The Chinese patent document titled "Short-time slowly changing large current measuring device based on PCB-type Rogowski coil" proposes to eliminate electromagnetic interference by using symmetrical wiring and setting loops , because the loop and the coil are not strictly offset, the interference signal can still enter the Rogowski coil.

The document "Error Analysis of PCB Type Rogowski Coil (Rogowski Coil)" proposes to connect two wires to opposite coils in series to realize the loop function in ordinary air-core coils and increase the coil output voltage at the same time, but the closer the coil distance , the self-inductance and stray capacitance will be larger, which will also affect the accuracy and frequency response of the coil.

The publication number is CN201465698U, and the publication date is May 12, 2010. The Chinese patent document titled "A High-precision Open Rogowski Coil" proposes to use four semicircles to form two semicircular coils with opposite directions to realize the open transformer. , realize the return line at the same time, the above method solves the problem of installation, but the two mirror semicircles are loosely coupled, and can not realize the cancellation in the strict sense, so the shielding effect on the interference signal is limited, and the realization is more complicated at the same time.

Contents of the invention

In order to overcome the deficiencies in the prior art above, the present invention provides an open-type fault transient current sensor, which is easy to install, has high sampling accuracy, good linearity, and strong anti-interference ability.

Based on the above purpose, the present invention provides an open fault transient current sensor, which comprises:

The first half-ring body has a head end and a tail end along the direction of circular extension; the first half-ring body is wound with wires, and the wires are wound from the head end of the first half-ring body according to the first winding direction After reaching the tail end, wind from the tail end of the first half-ring body back to the head end according to the first winding direction;

The second half-ring body has a head end and a tail end along the direction of circular extension, the head end of the first half-ring body is spliced with the head end of the second half-ring body, and the tail end of the first half-ring body Splicing with the tail end of the second half-ring body to form a complete circle; the second half-ring body is wound with wires, and the wires start from the head end of the second half-ring body in the direction opposite to the first winding direction After the second winding direction of the second winding is wound to its tail end, the tail end of the second half-ring body is wound back to its head end according to the second winding direction;

The wires wound on the first half-ring body and the second half-ring body both have a winding starting point and an ending point, the two ending points are connected to each other, and the two starting points are output ends.

The open-type fault transient current sensor of the present invention uses the first semi-annular body and the second semi-annular body which can be spliced into a whole ring as the skeleton of the coil. When installing, the ring is first opened, and the circuit to be tested Put it into the middle hole of the ring, and then close the ring, which is convenient for installation and use. In this technical solution, the wires are wound from the head end of the first semi-annular body and the second semi-annular body to the tail end (hereinafter referred to as "sequential winding") and then from the tail end to the head end (hereinafter referred to as "wrapping" for short). ) mode, the equivalent large turn of the winding coil is replaced by the return line of the Rogowski coil with the return line in the prior art, so as to offset the induced electromotive force generated by the equivalent large turn of the forward winding coil. function, thereby eliminating the influence of the vertical disturbing magnetic field. The open-type fault transient current sensor described in the present invention can be a PCB Rogowski coil, and as a kind of Rogowski coil, it is usually used with an integrator.

Further, in the open-type fault transient current sensor of the present invention, at least two rows of outer ring via holes and at least two rows of inner ring via holes are provided on the first half ring body and the second half ring body , the outer ring via hole is set close to the outer edge of the first half ring body and the second half ring body, the inner ring via hole is set close to the inner edge of the first half ring body and the second half ring body, and the wire The outer ring via hole and the inner ring via hole are wound on the first half ring body and the second half ring body.

In the above scheme, if the open-type fault transient current sensor described in the present invention is a PCB Rogowski coil, then the first semi-annular body and the second semi-annular body are printed circuit boards, and the via hole itself is a conductor. Instead of the wires, printed lines between the holes and the vias together form turns.

Furthermore, in the above-mentioned open-type fault transient current sensor, the via holes of each row of outer ring via holes and each row of inner ring via holes are evenly distributed in the circumferential direction of the ring.

Furthermore, in the above-mentioned open-type fault transient current sensor, the outer ring vias include two rows of outer ring vias arranged as the Mth row of outer ring vias and the Nth row of outer ring vias, and the inner ring The ring vias include three rows; the wire passes through the Mth row of outer ring vias and inner ring vias on the path from the head end to the tail end, and the wire passes through the Nth row on the path from the tail end to the head end. Outer ring vias and inner ring vias.

Furthermore, in the above open-type fault transient current sensor, the Nth row of outer ring via holes is arranged outside the Mth row of outer ring via holes in the radial direction of the ring.

Furthermore, in the above-mentioned open-type fault transient current sensor, the three rows of inner ring via holes include the A-th row of inner-ring via holes, the B-th row of inner ring via holes arranged sequentially from the inside to the outside in the radial direction of the ring. The first row of inner ring vias and the Cth row of inner ring vias; the wire connects the Mth row of outer ring vias with the Ath row of inner ring vias and the Cth row of inner ring vias on the path from the head end to the tail end. holes and the B-th row of inner-ring vias are circularly connected in turn, and the wire connects the N-th row of outer-ring vias with the C-th row of inner-ring vias, the A-th row of inner-ring vias and the The inner ring via holes in row B are sequentially connected in a circular manner.

The above scheme increases the arrangement and distribution space of the via holes, reduces the difficulty of processing, and also ingeniously ensures the consistency of the equivalent large turn radius of the forward-wound coil and the back-wound coil structure, and achieves strict control of the electromotive force generated by the disturbing magnetic field. offset, ensuring good anti-jamming capability.

Furthermore, in the above-mentioned open-type fault transient current sensor, the number of outer ring vias in each row of outer ring vias is set to 58, and the number of inner ring vias in each row of inner ring vias Set to 39.

The open-type fault transient current sensor described in the present invention has the following beneficial effects:

1) Since the first half ring body and the second half ring body can be opened and closed, when installing, first open the ring, put the circuit to be tested into the middle hole of the ring, and then close the ring, which makes the installation very convenient;

2) Due to the consistency of the equivalent large turn radius of the forward-wound coil and the back-wound coil structure, the electromotive force generated by the interfering magnetic field can be strictly offset to ensure good anti-interference ability;

3) When a PCB Rogowski coil is used, it has higher sampling accuracy and better linearity.

Description of drawings

FIG. 1 is a schematic structural view of an existing Rogowski coil in an embodiment.

FIG. 2 is a schematic diagram of an equivalent large turn in FIG. 1 .

Fig. 3 is a structural schematic diagram of an existing Rogowski coil with a loop wire in an embodiment.

FIG. 4 is a schematic diagram of an equivalent large turn in FIG. 3 .

Fig. 5 is a schematic structural diagram of an open fault transient current sensor according to an embodiment of the present invention.

FIG. 6 is a schematic diagram of the location of via holes on the first half-ring body in an embodiment of the present invention.

FIG. 7 is a schematic diagram of an equivalent large turn in FIG. 5 .

FIG. 8 is a schematic structural diagram of the linearity testing scheme of this embodiment.

FIG. 9 is an input and output waveform diagram under the linearity test scheme of this embodiment.

FIG. 10 is an output curve diagram of an equivalent input of 0-12000A under the linearity test scheme of this embodiment.

FIG. 11 is a schematic structural diagram of a test scheme for interference of adjacent phase wires in this embodiment.

detailed description

The open-type fault transient current sensor of the present invention will be further described in detail below in conjunction with the accompanying drawings and embodiments.

Fig. 5 shows the structure of an open-type fault transient current sensor according to an embodiment of the present invention.

As shown in Figure 5, the open-type fault transient current sensor of this embodiment is a double half-turn (winding and winding half-turn) PCB Rogowski coil, which includes: a first half ring body and a second half ring as a printed circuit board The ring body has a plurality of via holes passing through the printed circuit board. The via holes are conductors, and printed wires are connected between the via holes according to certain rules. The via holes and the printed wires together form coil turns. Wherein, the first half-ring body has a head end H and a tail end E, the second half-ring body has a head end H' and a tail end E', the head end H of the first half-ring body and the head end of the second half-ring body H' splicing, the tail end E of the first half-ring body and the tail end E' of the second half-ring body are spliced to form a complete circle.

Specifically, please continue to refer to FIG. 5 for the distribution position of the vias, and refer to FIG. 6 in combination. Taking the first semi-annular body as an example, two rows of vias are provided on one side of the outer edge, and three rows of vias are provided on one side of the inner edge. From the outside to the inside, there are N row, M row, C row, B row and A row, and the distances of each row of via holes to the center of the circle are R _N , R _M , R _C , R _B , R _A . The head end H of the first semi-annular body has the starting via hole X and the terminal via hole Y of the turn; the N row and the M row each have 58 via holes, and are spaced at an equal radian interval of π/58 around the first semi-annular body Evenly distributed upward; row C, row B and row A each have 39 via holes, which are evenly distributed in the circumferential direction of the first semi-annular body at an equal arc interval of π/39.

Specifically, please continue to refer to Figure 5 for the connection between the via hole and the printed wire. The connection on the front side is represented by a solid line, and the connection on the back side is represented by a dotted line. Hollow dots represent vias on the winding path, and solid dots represent the winding path. vias on the Taking the first half ring body as an example, the vias are labeled as Np, Mp, Cq, Bq, Aq, where the first letter represents the row where the via is located, and the second letter represents the via from the head end H to the end E where the range of p is from 1 to 58, the range of q is from 1 to 39, and the path around is X-A1-M1-C1-M2-B2-M3-A3-M4-C3…, that is, M The row of via holes is connected to row A, row C, and row B in turn through printed wires until the front M58 is connected to C39, and the winding path ends; C39 is connected to N58 on the back, and N58 starts to wrap around, and the wrapping path is N58- B39-N57-C38-N56-A38..., that is, the N row of vias is connected to the C row, A row, and B row of vias in sequence through the printed wires, until B1 is connected to Y and then the wrapping ends. Among them, when the N row on the front is connected to the C, A, and B rows, it first crosses from the outside of the M row along a small arc; The outer side spans, the arc radii of the front and back sides are equal, and the total span is equal.

The structure of this embodiment is described above using the first half-ring body as an example. In fact, the second half-ring body has the same structure as the first half-ring body, but it is placed opposite to the first half-ring body during splicing. When measuring, connect the Y via hole of the first semi-annular body to the Y' via hole of the second semi-annular body, and the X via hole of the first semi-annular body and the X' via hole of the second semi-annular body are used as output terminals .

The equivalent large wire turn of this embodiment is shown in Figure 7, and the interference magnetic field B _Z in the vertical direction generates induced electromotive forces of the same size and opposite directions in the parallel _winding equivalent large wire turn L and the _reverse winding equivalent large wire turn L. , the two cancel each other out, and the output e′ _Z is zero, thereby eliminating the influence of the disturbing magnetic field in the vertical direction. The difference between the forward-winding equivalent large wire turn L _shun and the return-winding equivalent large wire turn L _return radius shown in the figure is only used to distinguish the two. The radius of the equivalent large wire turn Lshun and the equivalent large wire turn _Lcircle can be considered _to be equal.

The performance and implementation effect of the open-type fault transient current sensor of this embodiment will be tested through experiments.

First, the linearity of the open-type fault transient current sensor of this embodiment is tested according to the test scheme shown in FIG. 8 . The impulse current generator can generate an impulse current with an amplitude not greater than 2500A, and the output is connected with a wire 1 with a high withstand voltage level passing through the coil 2 of this embodiment. In order to obtain accurate linearity test results, the measured current range of this test must be relatively large, so the method of winding the output wire of the impulse current generator five times, so that the actual induced magnetic field passing through the coil is enlarged by five times, which is equivalent to the impact The current generator outputs the equivalent impulse current in the range of 0-12000A. The output of the coil in this embodiment is connected to the conditioning circuit. The conditioning circuit is an S1 type precision integrator powered by a lithium battery with a voltage of 7.72V. The conditioning circuit has a good function of restoring the original waveform. Connect the output of the impulse current generator and the output of the conditioning circuit to CH1 and CH2 of the DPO5204 digital oscilloscope respectively, and compare and observe the waveforms. The input and output waveforms when the impulse current generator outputs 2032A are shown in Figure 9, and it can be seen that the input and output waveforms are basically the same.

Table 1 is the output data and fitting data of the impulse current generator outputting the equivalent impulse current in the range of 0-12000A. Figure 10 is the output data diagram and fitting curve diagram of Table 1. It can be seen that the input and output have good linearity.

Table 1 Linearity test results

serial number Equivalent current (A) CH2 peak-to-peak value (V) Fitting voltage (V) Residual (V) 1 1160 2.02 1.76 0.26 2 2280 4.12 3.92 0.20 3 3400 6.00 6.07 -0.07 4 4580 8.24 8.35 -0.11 5 5720 10.1 10.54 -0.44 6 6880 12.5 12.78 -0.28 7 8020 14.8 14.97 -0.17 8 9120 17.4 17.09 0.31 9 10160 19.4 19.09 0.31 10 11160 twenty one 21.02 -0.02

Record the input current as I(KA) and the output voltage as U(V), the fitting relationship can be obtained as

U=1.92602I-0.47575

The correlation coefficient of the data fitting is 0.99992, indicating that there is a good linear correlation between the output voltage and the primary current. The maximum nonlinear error is It can be seen that the open-type fault transient current sensor of this embodiment has good linearity within the measuring range, and the non-linear error is small.

Secondly, according to the test scheme shown in FIG. 11 , the interference of adjacent phase wires of the open-type fault transient current sensor of this embodiment is tested. Use an impulse current generator to generate an impulse current with an amplitude of 2310A, and straighten and elongate the conductor passing the impulse current to simulate the adjacent phase conductor in the actual line. The coil of the open-type fault transient current sensor of this embodiment is not connected with any wire, and the output is connected with a conditioning circuit. Connect the output of the impulse current generator and the output of the conditioning circuit to CH1 and CH2 of the DPO5204 digital oscilloscope respectively, control the distance d _AB between the wire and the coil to be 3cm and 6cm, and change the relative direction of the coil and the wire. The measured data are shown in Table 2.

Table 2 Interference test of adjacent phase wires

CH1 peak-to-peak V 94.4 94.4 91.2 91.2 96 96 CH2 peak-to-peak mV 220 220 140 140 120 160 error% 0.233 0.233 0.153 0.153 0.125 0.167

It can be drawn from Table 2 that when the interference source is very close to the coil of the open-type fault transient current sensor of this embodiment, and the input is large, the output is also very weak, and the change is very small, indicating that the opening of the present embodiment Type fault transient current sensor has good anti-interference performance.

Finally, in order to test the influence of the vertical wire on the open-type fault transient current sensor of this embodiment, an impulse current generator is used to generate an interference current, and the wire conducting the interference current is wound on a cylinder to form a solenoid to generate a vertical horizontal plane a uniformly distributed magnetic field. The coil of the open-type fault transient current sensor in this embodiment is not connected to any current.

The impulse current generated by the impulse current generator is set to three values: 1030A, 1565A, and 2020A, and the coils are placed vertically and parallel to the magnetic field respectively, and the output of the conditioning circuit is measured. The test results are shown in Table 3.

Table 3 Test results of magnetic field interference in the vertical direction

According to Table 3, considering the difficulty of high-frequency measurement, the inherent error of the instrument, and the incomplete shielding in the actual measurement process, there is a certain error coupling. It can be concluded that the open-type fault transient current sensor of this embodiment has good resistance to the external magnetic field. Anti-interference performance.

The above-mentioned embodiment is a preferred embodiment of the present invention, but the embodiment of the present invention is not limited by the above-mentioned embodiment, and any other changes, modifications, substitutions, combinations, Simplifications should be equivalent replacement methods, and all are included in the protection scope of the present invention.

Claims (7)

1. a kind of open-type fault transient state current sensor, it is characterised in that including：

First hemizonid, it has head end and tail end along the direction that annular extends；Wire is wound with first hemizonid, institute State wire to be wound to after its tail end according to the first direction of winding from the head end of the first hemizonid, then pressed from the tail end of the first hemizonid Its head end is wound back according to the first direction of winding；

Second hemizonid, its direction along annular extension has a head end and tail end, the head end of first hemizonid and the second half The head end splicing of ring body, the tail end of first hemizonid and the tail end of the second hemizonid splice to form a complete annulus； It is wound with wire on second hemizonid, the wire is from the head end of the second hemizonid according to opposite with the first direction of winding Second direction of winding is wound to after its tail end, then winds back its head end from the tail end of the second hemizonid according to the second direction of winding；

The wire wound on first hemizonid and the second hemizonid is respectively provided with starting point end and the destination terminal of winding, described in two eventually Point end is connected with each other, and starting point end described in two is output end.

2. open-type fault transient state current sensor according to claim 1, it is characterised in that：First hemizonid and At least two exclusive ring vias and at least two row's inner ring vias are equipped with second hemizonid, the outer shroud via is close to the first semi-ring The outward flange of body and the second hemizonid is set, and the inner ring via is set close to the inward flange of the first hemizonid and the second hemizonid Put, the wire is wound on first hemizonid and the second hemizonid by outer shroud via and inner ring via.

3. open-type fault transient state current sensor according to claim 2, it is characterised in that：Each exclusive ring via and Each via of each row's inner ring via is uniform in the circumferential direction of the annulus.

4. the open-type fault transient state current sensor according to Claims 2 or 3, it is characterised in that：The outer shroud via The two exclusive ring vias including being set to the exclusive ring vias of M and the exclusive ring vias of N, the inner ring via includes three rows；Institute State wire to be wound on the path of tail end by the exclusive ring vias of M and inner ring via from head end, the wire is from tail end Wind on the path at end of turning one's head by the exclusive ring vias of N and inner ring via.

5. open-type fault transient state current sensor according to claim 4, it is characterised in that：The exclusive ring mistakes of N Hole is in the outside for being located at the exclusive ring vias of M in the radial direction of the annulus.

6. open-type fault transient state current sensor according to claim 5, it is characterised in that：The three rows inner ring via It is included in the A set gradually from inside to outside in the radial direction row's inner ring via, B row's inner ring vias and the C of the annulus Arrange inner ring via；The wire from head end be wound on the path of tail end by the exclusive ring vias of M and A rows inner ring via, C arranges inner ring via and B row's inner ring vias circulate connection successively, and the wire will on the path that end of turning one's head is wound from tail end The exclusive ring vias of N circulate be connected successively with C row's inner ring via, A row's inner ring vias and B row's inner ring vias.

7. open-type fault transient state current sensor according to claim 6, it is characterised in that：Each exclusive ring mistake The inner ring number of vias that the quantity of outer shroud via is set in 58, each row's inner ring via in hole is set to 39.