Optical isolation type electric signal transmission and transformation system based on voltage-frequency conversion mode

Abstract

The invention relates to an optical isolation type electric signal transmission and transformation system based on a voltage-frequency conversion mode, and belongs to the field of high-voltage sensor design and manufacturing. The system comprises a primary high-voltage side voltage-frequency conversion unit and a secondary side acquisition device, the primary high-voltage side voltage-frequency conversion unit comprises a voltage-frequency conversion module, a light emitting module and a photocell, and the secondary side acquisition device comprises a light receiving module, a frequency-voltage conversion module and a laser energy supply module; an input end of the voltage-frequency conversion module is used for accessing a high-voltage electrical signal, an output end of the voltage-frequency conversion module is used for connecting an input end of the light emitting module, a light output port of the light emitting module is connected with a light receiving port of the light receiving module through an optical fiber, and an output end of the light receiving module is connected with an input end of the frequency-voltage conversion module; the photocell is used for supplying power to the voltage-frequency conversion module, and the input end of the photocell is connected with the laser energy supply module through an optical fiber. According to the invention, the anti-interference performance of signal transmission and the insulation reliability between the first side and the second side are improved.

Description

Technical Field

[0001] The present invention belongs to the field of high-voltage sensor design and manufacturing, and in particular relates to an optically isolated electrical signal transmission system based on a voltage-frequency conversion mode. Background Art

[0002] High-voltage sensors are used to measure high-voltage signals, and then transmit the measured voltage or current signals through long-distance shielded cables to the secondary side for real-time monitoring or wave recording analysis. Since the transmitted analog signals are easily interfered by the external environment, and the high-voltage side and the low-voltage side are not completely electrically isolated, the high-voltage measurement system has not been developed towards digitalization and intelligence.

[0003] The measurement principle of an existing high-pressure sensor is as follows: Figure 1 As shown, the high-voltage sensor is based on the principle of capacitive voltage division. It adopts the form of stacked primary capacitors in series. Voltage division is achieved by connecting multiple capacitors in series, converting the primary high-voltage signal into a low-voltage signal, and then inputting it into the electronic unit through a shielded cable to realize digital signal processing and output digital quantity. The high-voltage sensor is mainly used in AC smart substations. After the primary voltage is divided by a capacitor string, an electronic unit is used to convert the analog low-voltage signal into a digital quantity output on site. Since the electronic unit needs to provide a working 220V DC power supply remotely, the primary and secondary cannot be completely isolated directly, and there is an insulation unreliability problem. Summary of the invention

[0004] The purpose of the present invention is to provide an optically isolated electrical signal transmission system based on a voltage-frequency conversion mode to solve the problems of unreliable transmission and unreliable primary and secondary insulation when existing high-voltage sensors collect and transmit high-voltage electrical signals.

[0005] The optically isolated electrical signal transmission system based on the voltage-frequency conversion mode provided by the present invention to solve the above-mentioned technical problems includes a primary high-voltage side voltage-frequency conversion unit and a secondary side acquisition device, wherein the primary high-voltage side voltage-frequency conversion unit includes a voltage-frequency conversion module, an optical transmitting module and a photocell, and the secondary side acquisition device includes an optical receiving module, a frequency-voltage conversion module and a laser power supply module; the input end of the voltage-frequency conversion module is used to access the high-voltage electrical signal, the output end of the voltage-frequency conversion module is used to connect the input end of the optical transmitting module, the optical output port of the optical transmitting module is connected to the optical receiving port of the optical receiving module through an optical fiber, and the output end of the optical receiving module is connected to the input end of the frequency-voltage conversion module; the photocell is used to power the voltage-frequency conversion module, and the input end of the photocell is connected to the laser power supply module through an optical fiber.

[0006] Furthermore, the primary high-voltage side voltage-frequency conversion unit also includes a signal conditioning circuit, which is used to condition the high-voltage electrical signal to realize the voltage-frequency conversion module in the optimal linear conversion range; the input end of the signal conditioning circuit is used to connect the output end of the high-voltage sensor, the output end of the signal conditioning circuit is connected to the input end of the voltage-frequency conversion module, and the photocell powers the signal conditioning circuit.

[0007] Furthermore, the signal conditioning circuit is composed of a resistor network and a voltage bias chip, the resistor network is composed of a first resistor, a second resistor and a third resistor, one end of the first resistor is used to connect to the output end of the high-voltage sensor, the other end of the first resistor is connected to one end of the third resistor, the other end of the third resistor is grounded, the connection point between the first resistor and the third resistor is connected to the second resistor and the input end of the voltage bias chip in sequence, and the output end of the voltage bias chip is grounded.

[0008] Furthermore, an operational amplifier is provided between the signal conditioning circuit and the voltage-frequency conversion module, the connection point between the first resistor and the third resistor is connected to the input end of the operational amplifier, and the output end of the operational amplifier is connected to the input end of the voltage-frequency conversion module.

[0009] Furthermore, the frequency-voltage conversion module is composed of a frequency-voltage conversion chip and a voltage-frequency conversion chip to form a phase-locked loop, and the demodulation of the received optical signal is achieved through the phase-locked loop.

[0010] Furthermore, the secondary side acquisition device is a 4U-sized standard chassis structure, and the optical receiving module, frequency-voltage conversion module and laser energy supply module are integrated in the chassis.

[0011] Furthermore, a power module and a signal acquisition circuit are integrated in the chassis, and the power module supplies power to the laser function module and the signal acquisition module composed of the light receiving module, the frequency-voltage conversion module and the signal acquisition circuit.

[0012] Furthermore, the resistance values ​​of the second resistor and the third resistor are the same, and the resistance value of the second resistor is twice the resistance value of the first resistor.

[0013] Furthermore, the amplification factor of the operational amplifier is 2.

[0014] The beneficial effects of the present invention are: using optical signals to replace analog signal transmission schemes can prevent analog signals, especially weak signals, from being interfered with by electromagnetic interference from the external environment, thereby improving the anti-interference performance of signal transmission; the laser function module on the secondary side transmits the laser signal to the photocell on the primary side through optical fiber, thereby avoiding the transmission of 220V DC voltage signals and causing the primary and secondary sides to be unable to be completely isolated. Therefore, whether it is the transmission of high-voltage electrical signals collected by high-voltage sensors or the power supply signals provided to the voltage-frequency conversion module, the insulation isolation between the primary high-voltage side and the secondary low-voltage side is achieved through optical signal transmission, providing insulation reliability for system transmission, so the present invention improves the anti-interference performance of signal transmission and the insulation reliability between the primary and secondary sides. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] Figure 1 This is a measurement principle block diagram of an existing high-voltage sensor; Figure 2 Schematic diagram of an optically isolated electrical signal transmission system based on a voltage-frequency conversion mode according to an embodiment of the present invention; Figure 3 is a circuit schematic diagram of a signal conditioning circuit according to an embodiment of the present invention; Figure 4 It is a structural diagram of a frequency-voltage conversion module according to an embodiment of the present invention. DETAILED DESCRIPTION

[0016] The specific implementation of the present invention will be further described below in conjunction with the accompanying drawings.

[0017] The basic idea of ​​the present invention is to achieve complete electrical insulation isolation between the high voltage side and the low voltage side of the high voltage signal acquisition device, thereby improving the anti-interference performance of high voltage measurement signal transmission and the insulation reliability between the high voltage side and the low voltage side.

[0018] Based on the above basic ideas, Figure 2 As shown, the optically isolated electrical signal transmission system based on the voltage-frequency conversion mode of the present invention includes a primary high-voltage side voltage-frequency conversion unit and a secondary side acquisition device, the primary high-voltage side voltage-frequency conversion unit includes a voltage-frequency conversion module, an optical transmitting module and a photocell, the secondary side acquisition device includes an optical receiving module, a frequency-voltage conversion module and a laser power supply module; the input end of the voltage-frequency conversion module is used to access the high-voltage electrical signal, the output end of the voltage-frequency conversion module is used to connect to the input end of the optical transmitting module, the optical output port of the optical transmitting module is connected to the optical receiving port of the optical receiving module through an optical fiber, and the output end of the optical receiving module is connected to the input end of the frequency-voltage conversion module; the photocell is used to power the voltage-frequency conversion module, and the input end of the photocell is connected to the laser power supply module through an optical fiber.

[0019] The high-voltage sensor (also called a primary sensor) of the present invention is installed on the primary high-voltage side to realize the collection of high-voltage current or voltage signals. The high-voltage electrical signal collected by the high-voltage sensor is converted into an optical signal of the corresponding frequency, which is transmitted to the secondary side collection device on the secondary side through the optical fiber. The secondary side collection device completes the demodulation and collection conversion of the voltage-frequency signal, thereby realizing the reliable transmission and optical isolation of the high-voltage sensor measurement signal. At the same time, the voltage-frequency conversion module of the present invention is powered by a photocell, and the optical signal of the photocell is obtained by the secondary side collection device using optical fiber transmission, which again realizes the isolation of the power supply for the voltage-frequency conversion module, so that the voltage-frequency signal conversion module can realize the insulation isolation of the primary high voltage and the secondary side collection device. Therefore, while realizing the insulation isolation of the primary high voltage and the secondary side collection device, the present invention improves the anti-interference performance of the signal transmission after converting the analog signal converted by the high-voltage sensor into an optical signal.

[0020] As a preferred implementation, the primary high-voltage side voltage-frequency conversion unit further includes a signal conditioning circuit, which is used to condition the high-voltage electrical signal to achieve the voltage-frequency conversion module in the optimal linear conversion range; Figure 2 As shown, the input end of the signal conditioning circuit is used to connect the output end of the high-voltage sensor, the output end of the signal conditioning circuit is connected to the input end of the voltage-frequency conversion module, and the photocell is used to power the signal conditioning circuit. Preferably, the signal conditioning circuit provides a DC voltage bias V for the voltage-frequency conversion module. p , superimposed with the rated output voltage V1 of the high-voltage sensor to realize the voltage-frequency conversion module in the optimal linear conversion range.

[0021] As a preferred implementation, the voltage-frequency conversion module (VFC chip) adopts an industrial-grade chip, and the linearity reaches 0.05% in the frequency range of 10~100kHz.

[0022] As a preferred implementation mode, Figure 3 As shown, the signal conditioning circuit is composed of a resistor network and a voltage bias chip. The resistor network is composed of a first resistor R1, a second resistor R2 and a third resistor R3. One end of the first resistor R1 is used to connect to the output end of the high-voltage sensor, the other end of the first resistor R1 is connected to one end of the third resistor R3, the other end of the third resistor R3 is grounded, the connection point between the first resistor R1 and the third resistor R3 is connected to the second resistor R2 and the input end of the voltage bias chip in sequence, and the output end of the voltage bias chip is grounded.

[0023] As a preferred implementation, an operational amplifier is further provided between the signal conditioning circuit and the voltage-frequency conversion module, the connection point between the first resistor R1 and the third resistor R3 is connected to the input of the operational amplifier, and the output of the operational amplifier is connected to the input of the voltage-frequency conversion module.

[0024] Preferably, the second resistor R2 and the third resistor R3 have the same resistance, and the resistance of the second resistor R2 is twice that of the first resistor R1, that is, resistance R2 = R3 = 2R1. Preferably, the amplification factor of the operational amplifier is 2, that is, the input voltage signal is amplified twice.

[0025] Based on the above signal conditioning circuit structure, assuming that the voltage signal output by the high-voltage sensor is V1, the voltage of the DC voltage bias chip is Vp, the frequency of the optical signal output by the voltage-frequency conversion chip after voltage-frequency conversion is Fout, and the output voltage of the signal conditioning circuit composed of the resistor network and the DC voltage bias chip is V2, then the calculation formula of V2 is: V2 = V1 / 2 + Vp / 4 (1) After the operational amplifier amplifies the voltage by 2 times, the voltage Vin output to the VFC chip is: Vin=2×(V1 / 2+Vp / 4)= V1+ Vp / 2 (2) According to the high-voltage sensor output voltage signal V1 and the VFC chip working linear frequency range, based on the above transmission principle diagram, the circuit parameters can be designed for optimal matching. Taking the ADVFC32BH voltage-frequency conversion chip as an example, in the frequency range of 10~100kHz, the linearity reaches 0.05%, and the design parameters are controlled so that the VFC chip output optical signal frequency Fout meets: Fout=(V1+ Vp / 2)×100kHz (3) Based on the above signal conditioning circuit and VFC conversion circuit, the voltage signal output by the high-voltage sensor is converted into an optical signal for transmission.

[0026] As a preferred implementation, the secondary side acquisition device adopts a 4U-sized standard chassis structure design, and integrates the optical receiving module, the frequency-voltage conversion module and the laser power supply module in the chassis.

[0027] The output signal of the frequency-voltage conversion module is input into the signal acquisition circuit, which implements high-speed sampling of the FVC demodulated voltage signal at least 200kHz, and outputs a digital signal that complies with the IEC60044-8 protocol to meet the requirements of engineering applications. Therefore, the secondary side acquisition device also includes a signal acquisition circuit, which is integrated into the chassis.

[0028] In addition, the secondary side acquisition device is also provided with a power module for powering the laser function module and the signal acquisition module composed of the optical receiving module, the frequency-voltage conversion module and the signal acquisition circuit, so the power module is also integrated in the chassis.

[0029] As a preferred implementation, the frequency-voltage conversion module is composed of a phase-locked loop composed of a frequency-voltage conversion chip and a voltage-frequency conversion chip, and the demodulation of the received optical signal is realized through the phase-locked loop. Figure 4 As shown, the optical signal Fout output by the VFC conversion module is converted into an analog voltage signal Vout through the FVC module. Based on the selected device, the relationship between the output voltage and the input frequency is: Vout=Fout*2 / 100kHz (V) Based on the above signal transmission process, the signal transmitted from the high-voltage side is isolated and transmitted through the VFC-FVC to achieve optical isolation of the primary and secondary signals.

[0030] The present invention solves the problem of reliable transmission of electrical signals output by existing high-voltage sensors, especially weak voltage signals, and realizes isolation of the primary high-voltage side and the secondary low-voltage side through optical signal transmission, thereby improving the anti-interference performance of signal transmission and the insulation reliability between the primary and secondary sides.

Claims

1. An optically isolated electrical signal transmission system based on a voltage-frequency conversion mode, characterized in that: The system includes a primary high-voltage side voltage-frequency conversion unit and a secondary side collection device, wherein the primary high-voltage side voltage-frequency conversion unit includes a voltage-frequency conversion module, an optical transmission module and a photocell, and the secondary side collection device includes a photoreceiving module, a frequency-voltage conversion module and a laser power supply module; the input end of the voltage-frequency conversion module is used to access a high-voltage electrical signal, and the output end of the voltage-frequency conversion module is used to connect to the input end of the optical transmission module, the optical output port of the optical transmission module is connected to the optical receiving port of the optical receiving module through an optical fiber, and the output end of the optical receiving module is connected to the input end of the frequency-voltage conversion module; the photocell is used to power the voltage-frequency conversion module, and the input end of the photocell is connected to the laser power supply module through an optical fiber.

2. The optically isolated electrical signal transmission system based on voltage-frequency conversion mode according to claim 1 is characterized in that: The primary high-voltage side voltage-frequency conversion unit also includes a signal conditioning circuit, which is used to condition the high-voltage electrical signal to achieve the voltage-frequency conversion module in the optimal linear conversion range; the input end of the signal conditioning circuit is used to connect the output end of the high-voltage sensor, the output end of the signal conditioning circuit is connected to the input end of the voltage-frequency conversion module, and the photocell is used to power the signal conditioning circuit.

3. The optically isolated electrical signal transmission system based on voltage-frequency conversion mode according to claim 2 is characterized in that: The signal conditioning loop is composed of a resistor network and a voltage bias chip. The resistor network is composed of a first resistor, a second resistor and a third resistor. One end of the first resistor is used to connect to the output end of the high-voltage sensor, the other end of the first resistor is connected to one end of the third resistor, and the other end of the third resistor is grounded. The connection point between the first resistor and the third resistor is connected to the second resistor and the input end of the voltage bias chip in sequence, and the output end of the voltage bias chip is grounded.

4. The optically isolated electrical signal transmission system based on voltage-frequency conversion mode according to claim 3 is characterized in that: An operational amplifier is also provided between the signal conditioning circuit and the voltage-frequency conversion module, the connection point between the first resistor and the third resistor is connected to the input end of the operational amplifier, and the output end of the operational amplifier is connected to the input end of the voltage-frequency conversion module.

5. The optically isolated electrical signal transmission system based on voltage-frequency conversion mode according to claim 1 is characterized in that: The frequency-voltage conversion module is composed of a frequency-voltage conversion chip and a voltage-frequency conversion chip to form a phase-locked loop, and the demodulation of the received optical signal is achieved through the phase-locked loop.

6. The optically isolated electrical signal transmission system based on voltage-frequency conversion mode according to claim 1 is characterized in that: The secondary side acquisition device is a 4U standard chassis structure, and the optical receiving module, frequency-voltage conversion module and laser energy supply module are integrated in the chassis.

7. The optically isolated electrical signal transmission system based on voltage-frequency conversion mode according to claim 6 is characterized in that: The chassis also integrates a power module and a signal acquisition circuit, wherein the power module supplies power to connect the laser function module and the signal acquisition module composed of a light receiving module, a frequency-voltage conversion module and a signal acquisition circuit.

8. The optically isolated electrical signal transmission system based on voltage-frequency conversion mode according to claim 3 is characterized in that: The second resistor and the third resistor have the same resistance value, and the resistance value of the second resistor is twice the resistance value of the first resistor.

9. The optically isolated electrical signal transmission system based on voltage-frequency conversion mode according to claim 4 is characterized in that: The amplification factor of the operational amplifier is 2.

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