CN107329052A - A kind of electric discharge electromagnetic wave time delay value evaluation method based on analog signal - Google Patents

Abstract

The invention belongs to the technical field of electric equipment fault diagnosis, and in particular relates to a method for estimating the delay value of discharge electromagnetic waves based on analog signals. The present invention is that two sensors receive the electromagnetic wave signal generated by the discharge and record it as a default analog signal; the received analog signal is converted into two sine wave signals through a band-pass filter with a bandwidth of 400-600MHz; the two sine wave signals Then pass through the local oscillator (300MHz); then pass the signal passing through the local oscillator through a low-pass filter with an intermediate frequency of 100MHz; perform quadrature detection on the obtained signal and the signal v ₂₁ (t) and pass through the low-pass again Filter; the obtained signal uses the above formula to calculate the phase difference between the signals, that is, the delay value of the original signal. The invention can avoid the use of digital signal recording devices such as oscilloscopes, and greatly reduces the size, weight and economic cost of the algorithm supporting devices.

Description

An Estimation Method of Discharge Electromagnetic Wave Time Delay Based on Analog Signal

technical field

The invention belongs to the technical field of electric equipment fault diagnosis, and in particular relates to a method for estimating the delay value of discharge electromagnetic waves based on analog signals.

Background technique

In the power system, partial discharge or spark discharge is a precursor to the aging and failure of insulating materials. At the same time, the high-frequency radiation electromagnetic waves generated by the discharge will also cause electromagnetic interference to transmission and distribution lines, communication equipment near substations, and TV broadcasting signals. . Therefore, in order to find the aging part of the insulating material early, avoid insulation failure and avoid interference to the surrounding electromagnetic environment, it is necessary to accurately locate the position of the discharge source. In the traditional algorithm based on discharge electromagnetic wave diagnosis, the common antenna receives the electromagnetic wave signal, and then records the waveform of the electromagnetic wave through the A/D conversion device, and then estimates the delay value through a specific algorithm. Although this method can effectively record waveforms, it often takes some time for A/D conversion and oscilloscope recording waveforms, which cannot meet the needs of rapid analysis and diagnosis.

Contents of the invention

The purpose of the present invention is to provide a method for estimating the time delay value of discharge electromagnetic waves based on analog signals, and the purpose is to obtain accurate time delay values between signals from recorded analog waveforms without using an A/D conversion device.

In order to achieve the above-mentioned purpose of the invention, the present invention is achieved through the following technical solutions:

A method for estimating the time delay value of discharge electromagnetic waves based on analog signals, the operation steps are as follows:

(1) The electromagnetic wave signal generated by the discharge is received by two sensors and recorded as the default analog signal;

(2) The received analog signal is converted into two sine wave signals through a bandpass filter with a bandwidth of 400-600MHz;

(3) Pass the two sine wave signals in step 2 through the local oscillator (300MHz);

(4) passing through the signal of the local oscillator in the step 3 is the low-pass filter of 100MHz through the intermediate frequency;

(5) Carry out quadrature detection with the signal obtained in step 4 and the signal v ₂₁ (t) and pass through the low-pass filter again;

(6) The obtained signal uses the above formula to calculate the phase difference between the signals, that is, the delay value of the original signal.

The distance between the two sensors is 10cm-30cm.

The electromagnetic wave signal received by the sensor is converted into two sine wave signal waveforms s ₁ (t) and s ₂ (t) through a bandpass filter with a bandwidth of 400-600 MHz, so that the time delay between the original received electromagnetic wave signal can still be maintained The value is proportional to the phase difference.

The two sine wave signal waveforms are respectively multiplied with two signals v ₁ (t) and v ₂ (t) output by a local oscillator (300MHz) with a phase difference of π/2, and are filtered through a low pass The oscillator outputs vs ₁₂ (t), vs ₁₁ (t) and vs ₂₁ (t) signals with an intermediate frequency of 100MHz; among them: v ₁ (t) represents the signal 1 output by the local oscillator, and v ₂ (t) represents the local oscillator The signal 2 output by the machine oscillator, and there is a phase difference of π/2 between it and the signal 1, vs ₁₂ (t) represents the signal output through the low-pass filter after multiplying v ₁ (t) and s ₂ (t) , vs ₁₁ (t) represents the output signal through the low-pass filter after multiplication of v ₁ (t) and s ₁ (t), vs ₂₁ (t) represents the multiplication of v ₂ (t) and s ₁ (t) The signal output by the low-pass filter, t represents time; the signal vs ₁₁ (t) and vs ₁₂ (t) are used as a reference, and the signal v ₂₁ (t) is subjected to quadrature detection, and the obtained signal is obtained by the low-pass filter again The signal can be expressed as us _12-21 (t) and us _11-21 (t);

The phase difference θ between the two sine wave signals s ₁ (t) and s ₂ (t) can be obtained by the following formula:

In the above formula: θ represents the phase difference between the signals s ₁ (t) and s ₂ (t); us _12-21 (t) represents the quadrature detection of the signals vs ₁₂ (t) and v ₂₁ (t) and passed The signal output by the low-pass filter; us _11-21 (t) indicates that the signal vs ₁₁ (t) and v ₂₁ (t) perform quadrature detection and output the signal through the low-pass filter; t indicates time;

The obtained phase difference is obtained by a set of data at a certain moment after the antenna receives the trigger action.

Advantage of the present invention and beneficial effect are:

The invention can omit the A/D conversion device and directly analyze the analog signal waveform to obtain the required time delay value, avoiding the use of digital signal recording devices such as oscilloscopes, and greatly reducing the size, weight and economic cost of the algorithm matching device.

detailed description

The invention is a method for estimating the delay value of discharge electromagnetic waves based on analog signals, which is specifically realized by two sensors, a band-pass filter, a local oscillator and a low-pass filter.

The distance between the two sensors is 10cm-30cm;

The electromagnetic wave signal received by the sensor is converted into two sine wave signal waveforms s ₁ (t) and s ₂ (t) through a bandpass filter with a bandwidth of 400-600 MHz, so that the time delay between the original received electromagnetic wave signal can still be maintained The value is proportional to the phase difference;

The two sine wave signal waveforms are respectively multiplied with two signals v ₁ (t) and v ₂ (t) output by a local oscillator (300MHz) with a phase difference of π/2, and are filtered through a low pass The oscillator outputs vs ₁₂ (t), vs ₁₁ (t) and vs ₂₁ (t) signals with an intermediate frequency of 100MHz; among them: v ₁ (t) represents the signal 1 output by the local oscillator, and v ₂ (t) represents the local oscillator The signal 2 output by the machine oscillator, and there is a phase difference of π/2 between it and the signal 1, vs ₁₂ (t) represents the signal output through the low-pass filter after multiplying v ₁ (t) and s ₂ (t) , vs ₁₁ (t) represents the output signal through the low-pass filter after multiplication of v ₁ (t) and s ₁ (t), vs ₂₁ (t) represents the multiplication of v ₂ (t) and s ₁ (t) The signal output through the low-pass filter, t represents time.

The signals vs ₁₁ (t) and vs ₁₂ (t) are used as a reference, the signal v ₂₁ (t) is subjected to quadrature detection, and the signal obtained through the low-pass filter can be expressed as us _12-21 (t) and us _11-21 (t);

The phase difference θ between the two sine wave signals s ₁ (t) and s ₂ (t) can be obtained by the following formula:

In the above formula: θ represents the phase difference between the signals s ₁ (t) and s ₂ (t); us _12-21 (t) represents the quadrature detection of the signals vs ₁₂ (t) and v ₂₁ (t) and passed The signal output by the low-pass filter; us _11-21 (t) indicates that the signal vs ₁₁ (t) and v ₂₁ (t) perform quadrature detection and output the signal through the low-pass filter; t indicates time.

The obtained phase difference only needs to be obtained by a set of data at a certain moment after the antenna receives the trigger action, instead of using the traditional A/D conversion device to record the original waveform of the electromagnetic wave.

When the present invention is concretely implemented, its operating steps are as follows:

(1) The electromagnetic wave signal generated by the discharge is received by two sensors and recorded as the default analog signal;

(2) The received analog signal is converted into two sine wave signals through a bandpass filter with a bandwidth of 400-600MHz;

(3) Pass the two sine wave signals in step 2 through the local oscillator (300MHz);

(4) passing through the signal of the local oscillator in the step 3 is the low-pass filter of 100MHz through the intermediate frequency;

(5) Carry out quadrature detection with the signal obtained in step 4 and the signal v ₂₁ (t) and pass through the low-pass filter again;

(6) The obtained signal uses the above formula to calculate the phase difference between the signals, that is, the delay value of the original signal.

Claims (5)

1. a kind of electric discharge electromagnetic wave time delay value evaluation method based on analog signal, it is characterized in that：Operating procedure is as follows：

(1) electromagnetic wave signal for generation of discharging is received by two sensors and the analog signal of acquiescence is recorded as；

(2) analog signal received is converted to two sine wave signals by the bandpass filter with a width of 400-600MHz；

(3) two sine wave signals in step 2 are passed through into local oscillator (300MHz) again；

(4) signal in step 3 by local oscillator is passed through into low pass filter of the intermediate frequency for 100MHz again；

(5) by the signal obtained in step 4 and signal v₂₁(t) orthogonal detection is carried out and again by low pass filter；

(6) gained signal utilizes above-mentioned formula, calculates the time delay value of the phase difference between signal, i.e. primary signal.

2. a kind of electric discharge electromagnetic wave time delay value evaluation method based on analog signal according to claim 1, it is characterized in that： Described two sensor spacing are the distance between 10cm -30cm.

3. a kind of electric discharge electromagnetic wave time delay value evaluation method based on analog signal according to claim 1, it is characterized in that： The electromagnetic wave signal that the sensor is received is transformed into two sine waves by the bandpass filter with a width of 400-600MHz to be believed Number waveform s₁And s (t)₂(t) phase difference of the time delay value equal proportion between primary reception electromagnetic wave signal, so can still be kept.

4. a kind of electric discharge electromagnetic wave time delay value evaluation method based on analog signal according to claim 3, it is characterized in that： Two signals that described two sine wave signal waveforms are exported with the local oscillator (300MHz) with pi/2 phase difference respectively v₁And v (t)₂(t) it is multiplied, the vs that intermediate frequency is 100MHz is being exported by low pass filter₁₂(t)、vs₁₁And vs (t)₂₁(t) Signal；Wherein：v₁(t) signal 1, v of local oscillator output is represented₂(t) represent local oscillator output signal 2, and with letter There is the phase difference of pi/2, vs between number 1₁₂(t) v is represented₁And s (t)₂(t) signal exported after being multiplied by low pass filter, vs₁₁(t) v is represented₁And s (t)₁(t) signal exported after being multiplied by low pass filter, vs₂₁(t) v is represented₂And s (t)₁(t) phase The signal exported after multiplying by low pass filter, t represents the time；

The signal vs₁₁And vs (t)₁₂(t) as reference, to signal v₂₁(t) orthogonal detection is carried out, again by LPF The signal that device is obtained can be expressed as us_12-21And us (t)_11-21(t)。

5. a kind of electric discharge electromagnetic wave time delay value evaluation method based on analog signal according to claim 3, it is characterized in that： Described two sine wave signal s₁And s (t)₂(t) phase difference θ between can be drawn by following formula：

In above formula：θ represents signal s₁And s (t)₂(t) phase difference between；us_12-21(t) signal vs is represented₁₂And v (t)₂₁(t) enter Row orthogonal detection and the signal exported by low pass filter；us_11-21(t) signal vs is represented₁₁And v (t)₂₁(t) orthogonal inspection is carried out Ripple and the signal exported by low pass filter；T represents the time；

1 group of data that resulting phase difference receives a certain moment after trigger action by antenna are tried to achieve.