Differential voltage detection device for voltage transformer

Abstract

The utility model relates to the technical field of voltage transformers, in particular to a voltage transformer differential voltage detection device, which comprises a voltage transformer, an optical coupler, an optical modulator, a laser, a photoelectric detector, a pre-amplification circuit, a band-pass filter and a differential amplification circuit, and is characterized in that the voltage transformer comprises a primary winding and a secondary winding; a primary winding and a secondary winding of the voltage transformer are electrically connected with the optical couplers respectively, the optical couplers are electrically connected with the input end of the optical modulator, the output end of the optical modulator is electrically connected with the laser, the laser is connected with the photoelectric detector through an optical fiber, and the photoelectric detector is connected with the voltage transformer. The photoelectric detector is electrically connected with the input end of the differential amplification circuit through the pre-amplification circuit and the band-pass filter. The voltage signals of the primary side and the secondary side of the voltage transformer are subjected to photoelectric conversion, and the voltage conversion value of the voltage transformer is detected by optical signal transmission, so that the anti-interference capability of signal transmission is improved, and the influence of loop impedance on the detection result is effectively eliminated.

Description

Technical Field

[0001] The utility model relates to the technical field of voltage transformers, and particularly relates to a voltage transformer differential pressure detection device. Background Technique

[0002] In a modern power system, as an instrument for realizing voltage transformation, a voltage transformer is a key electrical measurement device, and the stability and accuracy of its performance directly affect the normal operation of the power system and the accuracy of electric energy metering.

[0003] During the operation of the power system, outdoor voltage transformers need to withstand the impact of high voltage and large current, and it is necessary to detect the performance status of the voltage transformers to avoid power system failures caused by voltage transformer failures. However, when using a traditional voltage transformer calibrator to detect a voltage transformer at present, in the electric energy metering circuit of a power plant and a substation, there are devices such as a wiring terminal block, a switch, and a fuse on the circuit. There is contact resistance and wire resistance during operation, so that there is a loop impedance in the loop where the voltage transformer is located, resulting in a voltage drop on the secondary side of the voltage transformer, affecting the normal detection of the voltage transformer and causing inaccurate detection results. Content of the Utility Model

[0004] To solve the above problems, the utility model provides a voltage transformer differential pressure detection device, which includes a voltage transformer, an optical coupler, an optical modulator, a laser, a photodetector, a preamplifier circuit, a band-pass filter, and a differential amplifier circuit. The voltage transformer includes a primary winding and a secondary winding; the primary winding and the secondary winding of the voltage transformer are respectively electrically connected to an optical coupler, the optical coupler is electrically connected to the input end of the optical modulator, the output end of the optical modulator is electrically connected to the laser, the laser is connected to the photodetector through an optical fiber, and the photodetector is electrically connected to the input end of the differential amplifier circuit through the preamplifier circuit and the band-pass filter.

[0005] In order to prevent interference between the detection signals of the primary side and the secondary side of the voltage transformer, the differential amplifier circuit is provided with two input ends, and two optical modulators, lasers, photodetectors, preamplifier circuits, and band-pass filters are provided.

[0006] In a specific embodiment, the differential amplifier circuit includes two phase compensation circuits and a differential amplifier, and the two phase compensation circuits are respectively electrically connected to the positive input end and the negative input end of the differential amplifier.

[0007] The phase compensation circuit includes capacitors C1, C2, C3, C4, and resistors R1, R2, R3, R4. Capacitors C1 and C2 are connected in parallel and serially connected to one end of resistor R1. The serial node is connected to the inverting input terminal of the differential amplifier, and the other end of resistor R1 is serially connected to resistor R2 and grounded. Capacitors C3 and C4 are connected in parallel and serially connected to one end of resistor R3. The serial node is connected to the non-inverting output terminal of the differential amplifier, and the other end of resistor R3 is serially connected to resistor R4 and grounded.

[0008] The voltage transformer differential pressure detection device further includes an analog-to-digital converter and a data communication module. The analog-to-digital converter is electrically connected to the output terminal of the differential amplification circuit, and the analog-to-digital converter is electrically connected to the data communication module.

[0009] In the specific implementation manner, a second-order band-pass filter is adopted for the band-pass filter.

[0010] The model of the analog-to-digital converter is ADC-LTC2325.

[0011] Beneficial effects: The present utility model is a voltage transformer differential pressure detection device. By performing photoelectric conversion on the voltage signals of the primary side and the secondary side of the voltage transformer, and using optical signal transmission to detect the voltage transformation value of the voltage transformer, the anti-interference ability of signal transmission is improved, and the loss during signal transmission is also reduced. At the same time, by modulating the intensity and phase of the photoelectric conversion signal optically, accurate measurement of the voltage signals of the primary side and the secondary side of the voltage transformer can be achieved, effectively eliminating the influence of loop impedance on the detection result of the voltage transformer, and improving the accurate measurement of the differential pressure signal of the voltage transformer. Description of the Drawings

[0012] Figure 1 It is a diagram of the voltage transformer differential pressure detection device;

[0013] Figure 2 It is a circuit diagram of the phase compensation. Specific Implementation Manner

[0014] The exemplary embodiments of the present disclosure will be described in more detail below with reference to the drawings.

[0015] See Figure 1 , this embodiment provides a voltage transformer differential pressure detection device, including a voltage transformer, an optical coupler, a laser, an optical modulator, a photodetector, a preamplification circuit, a band-pass filter, and a differential amplification circuit. The voltage transformer includes a primary winding and a secondary winding. The primary winding is used to connect to the power supply input terminal, and voltage transformation is performed on the secondary winding through the mutual inductance principle. The secondary winding outputs the transformed voltage signal for power metering detection.

[0016] In order to achieve on-site real-time detection of the voltage transformation value between the primary side and the secondary side of a voltage transformer, and to avoid the voltage signal being obtained by a remote electric energy meter for electric energy metering after the voltage output of the secondary side is stepped down by the impedance of devices such as wires and switches, resulting in inaccurate detection of the voltage transformer ratio (abbreviated as PT ratio). A photocoupler is electrically connected to the primary winding and the secondary winding of the voltage transformer respectively, and the photocoupler is electrically connected to an optical modulator. The photocoupler can perform optoelectronic conversion according to the voltage signals of the primary winding and the secondary winding. By converting the voltage signal into an optical signal and then outputting an electrical signal from the optical signal to the optical modulator, the output end of the optical modulator is electrically connected to a laser. The optical modulator can generate a driving modulation signal acting on the laser according to the input electrical signal, so that the laser generates an optical signal. There are two optical modulators and two lasers, and the models and powers of the two lasers are the same. By using the voltage signals of the primary winding and the secondary winding, two optical signals are generated respectively, and the differential pressure signal between the primary side voltage signal and the secondary side voltage signal is detected by using the optical signal, which can reduce the voltage drop effect of the loop impedance on the voltage signal. The laser is connected to a photodetector through an optical fiber. The optical signal modulated by the output voltages of the primary side and the secondary side of the voltage transformer is transmitted to the photodetector through the optical fiber. Using optical fiber transmission can reduce the loss of the optical signal during transmission. The photodetector can receive the optical signal and convert the optical signal into an electrical signal.

[0017] In order to prevent interference between the optical signals on the primary side and the secondary side of the voltage transformer, there are two photodetectors, two preamplifier circuits, and two band-pass filters, and the differential amplifier circuit has two input terminals. Each photodetector is electrically connected to the input terminal of the differential amplifier circuit through a preamplifier circuit and a band-pass filter respectively. The preamplifier circuit can amplify the electrical signal converted by the photodetector and transmit it to the band-pass filter for filtering and noise reduction. The band-pass filter uses a second-order band-pass filter.

[0018] Such as Figure 2As shown, in order to detect the differential pressure signal on the primary side and secondary side of the voltage transformer and determine the state performance of the voltage transformer. The differential amplification circuit includes two-phase compensation circuits and a differential amplifier. The phase compensation circuit includes capacitors C1, C2, C3, C4, and resistors R1, R2, R3, R4. Capacitors C1 and C2 are connected in parallel and serially connected to one end of resistor R1, and the series node is connected to the inverting input terminal of the differential amplifier. The other end of resistor R1 is serially connected to resistor R2 and grounded; similarly, capacitors C3 and C4 are connected in parallel and serially connected to one end of resistor R3, and the series node is connected to the non-inverting output terminal of the differential amplifier. The other end of resistor R3 is serially connected to resistor R4 and grounded. Since the transmission of optical signals and the circuit delay of photodetectors and other components will cause a phase difference between the two signals, the two electrical signals are kept in phase through the phase compensation circuit, and differential processing is performed through the differential amplifier to obtain the differential pressure value between the primary side voltage signal and the secondary side voltage signal of the current transformer.

[0019] At the same time, the differential pressure detection device of the voltage transformer further includes an analog-to-digital converter and a data communication module. The analog-to-digital converter is electrically connected to the differential amplification circuit, and its input terminal is connected to the output terminal of the differential amplifier. The model of the analog-to-digital converter is ADC-LTC2325, which can digitally convert the differential pressure value signal of the differential amplifier; the analog-to-digital converter is electrically connected to the data communication module. The data communication module can receive the digital signal of the analog-to-digital converter for communication transmission, and is connected to the remote terminal through wireless communication, and can upload the differential pressure detection data of the voltage transformer to the remote terminal in real time, which is convenient for operation and maintenance personnel to monitor the performance state of the voltage transformer and determine the actual PT ratio of the voltage transformer.

Claims

1. A differential voltage detection device for a voltage transformer, characterized in that, It includes a voltage transformer, an optical coupler, an optical modulator, a laser, a photodetector, a preamplifier circuit, a band-pass filter, and a differential amplifier circuit. The voltage transformer includes a primary winding and a secondary winding; The primary winding and the secondary winding of the voltage transformer are respectively electrically connected to an optical coupler. The optical coupler is electrically connected to the input end of the optical modulator. The output end of the optical modulator is electrically connected to the laser. The laser is connected to the photodetector via an optical fiber. The photodetector is electrically connected to the input end of the differential amplifier circuit via the preamplifier circuit and the band-pass filter.

2. The differential pressure detection device for a voltage transformer according to claim 1, characterized in that, The differential amplifier circuit is provided with two input ends, and there are two each of the optical modulator, the laser, the photodetector, the preamplifier circuit, and the band-pass filter.

3. The differential voltage detection device for a voltage transformer according to claim 2, wherein, The differential amplifier circuit includes two phase compensation circuits and a differential amplifier. The two phase compensation circuits are respectively electrically connected to the positive input end and the negative input end of the differential amplifier.

4. The differential voltage detection device for a voltage transformer according to claim 3, characterized in that, The phase compensation circuit includes capacitors C1, C2, C3, C4, and resistors R1, R2, R3, R4. Capacitors C1 and C2 are connected in parallel and are in series with one end of resistor R1. The series node is connected to the negative input end of the differential amplifier. The other end of resistor R1 is in series with resistor R2 and grounded. Capacitors C3 and C4 are connected in parallel and are in series with one end of resistor R3. The series node is connected to the positive output end of the differential amplifier. The other end of resistor R3 is in series with resistor R4 and grounded.

5. The differential voltage detection device for a voltage transformer according to claim 1, characterized in that It further includes an analog-to-digital converter and a data communication module. The analog-to-digital converter is electrically connected to the output end of the differential amplifier circuit, and the analog-to-digital converter is electrically connected to the data communication module.

6. The differential voltage detection device for a voltage transformer according to claim 1, characterized in that, The band-pass filter uses a second-order band-pass filter.

7. The differential voltage detection device for a voltage transformer according to claim 5, characterized in that, The model of the analog-to-digital converter is ADC-LTC2325.

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