CN106055757A - AC circuit power frequency magnetic field interference resistance design method based on finite element analysis - Google Patents

Abstract

The present invention discloses an AC circuit power frequency magnetic field interference resistance design method based on finite element analysis, comprising the steps of (1) establishing a simulation model of an AC sampling circuit of a protection measurement and control apparatus, and obtaining the magnetic flux density of an X axis, a Y axis and a Z axis; (2) outputting a sampling value I0 by the protection measurement and control apparatus when power frequency magnetic field interference is not present; (3) outputting a sampling value I1 by the protection measurement and control apparatus when the power frequency magnetic field interference is applied, and obtaining a function relationship between the power frequency interference and the apparatus output sampling value; (4) changing PCB layout wiring of each AC sampling circuit module to enable [Delta]I<X>, [Delta]I<Y> and [Delta]I<Z> to satisfy requirements of 5-grade tests in the GB/T 17626.8-2006; and (5) analyzing and obtaining a PCB layout wiring method of a mutual inductor AC sampling circuit, and proposing anti-interference measures. Power frequency magnetic field interference resistance immunity of the mutual inductor AC sampling circuit of the protection measurement and control apparatus is improved.

Description

The method for designing of ac circuit based on finite element analysis anti-power frequency magnetic field interference

Technical field

The present invention relates to the method for designing of a kind of ac circuit based on finite element analysis anti-power frequency magnetic field interference, belong to electricity Force system protection device anti-power frequency magnetic field technical field.

Background technology

Protection supervisory equipment is the Important Components in intelligent substation, its accuracy and the reliability peace to power system Full stable operation has important impact.In transformer station, electrical equipment operating frequency is 50Hz, is easily generated power frequency magnetic field, and is difficult to screen Cover.Power frequency magnetic field produces magnetic flux and is added on the AC sampling loop of protection supervisory equipment, and the induction electromotive force of generation easily makes Sampling precision produces error, causes the problems such as the malfunction of protection device, tripping.Therefore, protection supervisory equipment needs to pass through GB/T In 17626.8-2006 5 grades, the requirement that 1000 (A/m) test.

Summary of the invention

In order to solve above-mentioned technical problem, the invention provides a kind of anti-power frequency magnetic of ac circuit based on finite element analysis The method for designing of field interference.

In order to achieve the above object, the technical solution adopted in the present invention is:

The method for designing of ac circuit based on finite element analysis anti-power frequency magnetic field interference, comprises the following steps,

Step 1, sets up the phantom in the AC sampling loop of protection supervisory equipment, by Biot Savart law, method Draw the law of electromagnetic induction, draw magnetic flux density B of X-axis_X, magnetic flux density B of Y-axis_Y, magnetic flux density B of Z axis_Z；

Step 2, when disturbing without power frequency magnetic field, protection supervisory equipment output sampled value I₀；

Step 3, when applying power frequency magnetic field interference, protection supervisory equipment output sampled value I₁, obtain power frequency magnetic field interference Variation delta I in X-axis_X, variation delta I of Y-axis_Y, variation delta I of Z axis_Z, according to the numerical analysis method of Matlab, Go out B_XWith Δ I_XEmpirical coefficient k_X、B_YWith Δ I_YEmpirical coefficient k_Y、B_ZWith Δ I_ZEmpirical coefficient k_Z；

Step 4, according to k_X、k_Y、k_ZSize, change the PCB placement-and-routing of each AC sampling loop module, make Δ I_X、Δ I_Y、ΔI_ZMeet the requirement of 5 grades of tests in GB/T 17626.8-2006；

Step 5, analyzes the PCB placement-and-routing method drawing transformer AC sampling loop, proposes interference protection measure.

The AC sampling loop of protection supervisory equipment is mainly made up of exchange module, CPU module, motherboard module.

The beneficial effect that the present invention is reached: the present invention improves the anti-power frequency in the AC sampling loop of protection supervisory equipment Magnetic field immunity to interference.

Accompanying drawing explanation

Fig. 1 is the flow chart of the present invention.

Fig. 2 is the AC sampling circuit diagram of protection supervisory equipment.

Detailed description of the invention

The invention will be further described below in conjunction with the accompanying drawings.Following example are only used for clearly illustrating the present invention Technical scheme, and can not limit the scope of the invention with this.

As it is shown in figure 1, the method for designing of ac circuit based on finite element analysis anti-power frequency magnetic field interference, including following step Rapid:

Step 1, sets up the phantom in the AC sampling loop of protection supervisory equipment, uses ANSYS software " Electric " defines simulation parameters, by Biot Savart law, Faraday law of electromagnetic induction, draws the magnetic of X-axis Flux density B_X, magnetic flux density B of Y-axis_Y, magnetic flux density B of Z axis_Z。

As in figure 2 it is shown, the AC sampling loop of protection supervisory equipment is mainly by exchange module, CPU module, motherboard module group Become.

In power frequency magnetic field is tested, solve constant current I at a P (x, y, magnetic z) produced according to Biot Savart law Flux density, such as formula (1), (2), wherein x, y, z is respectively the X, Y, Z axis coordinate of some P.

Biot Savart law:

$dB=\frac{{\mathrm{\&mu;}}_{0}Idl\&times;R}{4{\mathrm{\&pi;R}}^3}---\left(1\right)$

$B=\frac{{\mathrm{\&mu;}}_0}{4\mathrm{\&pi;}}{\&Integral;}_c\frac{Idl\&times;R}{R^3}---\left(2\right)$

Wherein, B is the magnetic flux density that constant current wire produces at distance R, μ₀=4 π × 10^-7H/m is permeability of vacuum, I For constant current, dl is the wire line element of the sense of current, and R is for put distance from dl to P.

According to Faraday law of electromagnetic induction, solve and produce induction electromotive force e in closed-loop path, such as formula (3).

Faraday law of electromagnetic induction:

$e=-\frac{d\mathrm{\&Phi;}}{dt}=-\frac{Bds}{dt}---\left(3\right)$

Wherein, Φ is magnetic flux, and s is loop area, and t is the time.

The induction electromotive force e produced in power frequency magnetic field is tested is added on AC sampling loop.Adopting in exchange module Sample loop area s_ABB'A', sampling circuit area s in motherboard module_BCC'B', sampling circuit area s in CPU module_CDD'C', work The induction electromotive force that frequency interference produces at the loop area S of three pieces of area compositions is e.

Step 2, when disturbing without power frequency magnetic field, protection supervisory equipment output sampled value I₀。

Step 3, when applying power frequency magnetic field interference, protection supervisory equipment output sampled value I₁, obtain power frequency magnetic field interference Variation delta I in X-axis_X, variation delta I of Y-axis_Y, variation delta I of Z axis_Z, according to the numerical analysis method of Matlab, Go out B_XWith Δ I_XEmpirical coefficient k_X、B_YWith Δ I_YEmpirical coefficient k_Y、B_ZWith Δ I_ZEmpirical coefficient k_Z。

Step 4, according to k_X、k_Y、k_ZSize, change the PCB placement-and-routing of each AC sampling loop module, make Δ I_X、Δ I_Y、ΔI_ZMeet the requirement of 5 grades of tests in GB/T 17626.8-2006.

Step 5, analyzes the PCB placement-and-routing method drawing transformer AC sampling loop, proposes interference protection measure.

Said method improves the anti-power frequency magnetic field noise immunity in AC sampling loop of protection device.

The above is only the preferred embodiment of the present invention, it is noted that for the ordinary skill people of the art For Yuan, on the premise of without departing from the technology of the present invention principle, it is also possible to make some improvement and deformation, these improve and deformation Also should be regarded as protection scope of the present invention.

Claims (2)

1. the method for designing of ac circuit based on finite element analysis anti-power frequency magnetic field interference, it is characterised in that: include following step Suddenly,

Step 1, sets up the phantom in the AC sampling loop of protection supervisory equipment, by Biot Savart law, faraday The law of electromagnetic induction, draws magnetic flux density B of X-axis_X, magnetic flux density B of Y-axis_Y, magnetic flux density B of Z axis_Z；

Step 2, when disturbing without power frequency magnetic field, protection supervisory equipment output sampled value I₀；

Step 3, when applying power frequency magnetic field interference, protection supervisory equipment output sampled value I₁, obtain power frequency magnetic field and disturb in X-axis Variation delta I_X, variation delta I of Y-axis_Y, variation delta I of Z axis_Z, according to the numerical analysis method of Matlab, draw B_XWith ΔI_XEmpirical coefficient k_X、B_YWith Δ I_YEmpirical coefficient k_Y、B_ZWith Δ I_ZEmpirical coefficient k_Z；

Step 4, according to k_X、k_Y、k_ZSize, change the PCB placement-and-routing of each AC sampling loop module, make Δ I_X、ΔI_Y、Δ I_ZMeet the requirement of 5 grades of tests in GB/T 17626.8-2006；

Step 5, analyzes the PCB placement-and-routing method drawing transformer AC sampling loop, proposes interference protection measure.

The method for designing of the anti-power frequency magnetic field of ac circuit based on finite element analysis the most according to claim 1 interference, its It is characterised by: the AC sampling loop of protection supervisory equipment is mainly made up of exchange module, CPU module, motherboard module.