CN102269787B - Detection method of harmonic characteristic of electronic voltage transformer and detection device thereof - Google Patents

Abstract

The invention provides a method for detecting harmonic characteristics of an electronic voltage transformer and a detection device thereof. The detection device includes a voltage regulator T 1 connected to a power frequency test power supply on the input side, and a voltage regulator T ₁ connected to the output side of T ₁ to connect the power supply voltage The single-phase step-up transformer T ₂ that is boosted to the test voltage is connected in parallel to the capacitive voltage divider on the output side of T ₂ , the voltage transformer to be tested and the single-phase step-down transformer T ₃ , connected to the capacitive voltage divider and the voltage transformer to be tested. The measuring device at the low-voltage end of the voltage transformer is connected to the single-phase fully-controlled rectifier bridge load on the output side of _T3 . The harmonic characteristic detection method of the electronic voltage transformer provided by the present invention, its harmonic source part can generate the primary voltage that can simulate the rated voltage of the real grid harmonic voltage and the superimposed harmonic voltage of each order, and its detection device can measure The frequency characteristics of each harmonic voltage of the electronic voltage transformer are obtained, so as to realize the accurate measurement of the harmonic voltage in the power system.

Description

Electronic voltage transformer harmonic characteristic detection method and its detection device

technical field

The invention relates to a method for detecting harmonic characteristics of an electronic voltage transformer and a detection device thereof, belonging to the technical field of electric power measurement, in particular to a method capable of accurately detecting the harmonic characteristics of an electronic voltage transformer, and finally realizing the harmonic voltage measurement. A detection method for accurate measurement and a detection device thereof.

Background technique

At present, with the continuous increase of non-linear loads, the harmonic problem in the power system is becoming more and more serious, which has a very significant impact on electric energy metering, causing many problems such as metering mode, metering algorithm, and increasing the metering error of existing metering devices. question. In addition to the factors that the harmonic active power is not zero, the main cause of these problems is the difference in the harmonic response characteristics of the metering devices. In addition, harmonics will also affect relay protection, causing measurement errors in the protection algorithm with power frequency as a parameter, affecting the accuracy of the protection algorithm, and causing protection to malfunction or refuse to operate. Power transformer is the core component of electric energy metering, and its harmonic response characteristics are the key factors for accurate harmonic measurement. Therefore, it is of great theoretical and practical significance to detect the harmonic characteristics of power transformers and master their harmonic response performance.

At present, there are not many domestic standards for the detection of harmonic characteristics of transformers. "GB/T20840.8-2007 Transformers Part 8: Electronic Current Transformers" proposes the harmonic response and Harmonic accuracy requirements stipulate that "from practical considerations, it is acceptable to apply only a single harmonic frequency to the primary side in the test of the accuracy of each harmonic measurement." However, for electronic current transformers, the standard also points out that ideally, for harmonic tests, the required harmonic frequency components should be superimposed on the rated frequency and the rated primary current. This is because the superposition of each harmonic component of the rated primary current is an objective reflection of the real harmonics in the grid, and the same is true for the harmonic voltage.

In view of this, it is necessary to provide a detection method and a detection device that can accurately detect the harmonic characteristics of the electronic voltage transformer, and finally realize accurate measurement of the harmonic voltage, so as to meet the needs of industrial applications.

Contents of the invention

The technical problem to be solved by the present invention is: In order to solve the problem that the current harmonic characteristic detection of electronic voltage transformer lacks effective detection methods and detection devices, the present invention provides a harmonic characteristic detection of electronic voltage transformer method, its harmonic source part can generate a primary voltage that can simulate the rated voltage of the real power grid harmonic voltage and the superposition of each harmonic voltage, and its detection device can measure the frequency of each harmonic voltage of the electronic voltage transformer Features, in the power system to achieve accurate measurement of harmonic voltage.

The technical solution adopted in the present invention is: a harmonic characteristic detection device of an electronic voltage transformer, which consists of a voltage regulator, a single-phase step-up transformer, a capacitor voltage divider, a voltage transformer to be detected, a measuring device, a single-phase Composed of a step-down transformer and a single-phase full-control rectifier bridge load, it is characterized in that:

The input side of the voltage regulator is connected to the power frequency test power supply, and its output side provides an adjustable input voltage for the single-phase step-up transformer; the input side of the single-phase step-up transformer is connected to the output side of the voltage regulator to boost the power supply voltage to the test voltage; the capacitive voltage divider is the measurement traceability standard, and is connected to the output side of the single-phase step-up transformer to provide traceability signals for the measuring device; the voltage transformer to be detected is connected to the output side of the single-phase step-up transformer, and The output side provides the detected signal for the measuring device; the single-phase step-down transformer is connected to the output side of the single-phase step-up transformer to step down the output voltage of the single-phase step-up transformer to the rated value of the AC side of the load of the single-phase fully-controlled rectifier bridge. voltage; the load of the single-phase full-control rectifier bridge is connected to the output side of the single-phase step-down transformer, and through the change of the DC side load and the adjustment of the trigger angle, the harmonic current of the AC side is changed, so that the output of the single-phase step-up transformer can be The changing harmonic voltage; the measuring device receives the traceable signal from the low-voltage side of the capacitive voltage divider and the output signal of the voltage transformer to be tested, and performs spectrum and difference analysis to obtain the harmonic characteristics of the transformer to be tested.

The harmonic characteristic detection device of the electronic voltage transformer as described above is characterized in that the measuring device is mainly composed of four parts: power supply, signal acquisition, data processing, keyboard and liquid crystal display, wherein: the power supply part provides the measuring device DC working power supply; the signal acquisition part completes the transformation, amplification and acquisition of the traceability signal and the measurement signal, and converts it into a digital signal for the data processing part; the data processing part performs Fourier analysis on the digital signal corresponding to the traceability signal and the measurement signal, Spectrum comparison and difference measurement and other processing; the keyboard and liquid crystal display part realize human-computer interaction.

The present invention also provides a method for detecting harmonic characteristics of an electronic voltage transformer, using the detection device as described above, and the detection method includes the following steps:

Step 1, boosting the output of the voltage regulator to the primary rated voltage of the single-phase step-up transformer;

Step 2. When the load conditions of the fully-controlled rectifier bridge are successively selected as resistive load, resistive-inductive series load and resistive-capacitive parallel load, gradually change the trigger angle so that the harmonic components and content in the AC side current of the fully-controlled rectifier bridge Changes, when flowing through the internal impedance of the power frequency power supply and voltage regulator and the short-circuit impedance of the single-phase step-up transformer, a harmonic voltage with variable composition and content, similar to the actual operation of the power grid, is generated. The harmonic voltage is applied On the capacitive voltage divider and the voltage transformer to be tested;

Step 3: The traceable signal measured at the low-voltage end of the capacitor voltage divider and the output signal of the voltage transformer to be tested are input into the measurement device, and the measurement device performs Fourier analysis on the two signals to decompose the fundamental wave and The amplitude and phase information of each harmonic, so as to obtain the frequency spectrum of the two signals, including the amplitude spectrum and phase spectrum. Based on the traceability signal, the amplitude sum of the fundamental wave and each harmonic of the two signals is obtained. The phase difference is used to obtain the harmonic characteristics of the voltage transformer to be detected.

The beneficial effects of the present invention are: the electronic voltage transformer harmonic characteristic detection method and its detection device of the present invention utilize the change of the full-control rectifier bridge load and the adjustment of the trigger angle to generate components and Harmonic current with variable content, the current generates harmonic voltage with variable composition and content on the internal impedance of power frequency power supply and voltage regulator T1 and the short-circuit impedance of single-phase step-up transformer T2, which is applied to the capacitive voltage divider and On the transformer to be tested. This voltage truly simulates the actual situation of the harmonic voltage of the power grid. Through the comparison and analysis of the frequency spectrum and difference measurement of the low-voltage side traceability signal of the capacitor voltage divider and the output signal of the voltage transformer to be tested by the measuring device, the harmonic of the voltage transformer can be accurately grasped. Wave response characteristics, so as to achieve accurate measurement of harmonic voltage.

Description of drawings

Fig. 1 is a schematic circuit diagram of a method for detecting harmonic characteristics of an electronic voltage transformer according to an embodiment of the present invention.

Detailed ways

Hereinafter, the present invention will be further described through specific embodiments in conjunction with the accompanying drawings.

Please refer to Fig. 1, the harmonic characteristic detection device of the electronic voltage transformer provided by the embodiment of the present invention consists of a voltage regulator T1, a single-phase step-up transformer T2, a capacitive voltage divider, a voltage transformer to be detected, a measuring device, a single Phase step-down transformer T3 and single-phase full-control rectifier bridge load.

The input side of the voltage regulator T1 is connected to a power frequency test power supply, and its output side provides an adjustable input voltage for the single-phase step-up transformer T2.

The input side of the single-phase step-up transformer T2 is connected to the output side of the voltage regulator T1 to boost the power supply voltage to the test voltage.

The capacitive voltage divider is a measurement traceability standard, and is connected to the output side of the single-phase step-up transformer T2 to provide a traceability signal for the measurement device.

The voltage transformer to be detected is connected to the output side of the single-phase step-up transformer T2, and its output side provides the detected signal for the measuring device.

The measuring device receives the traceable signal from the low-voltage side of the capacitive voltage divider and the output signal of the voltage transformer to be tested, and performs frequency spectrum and difference analysis to obtain the harmonic characteristics of the transformer to be tested. The measurement device is mainly composed of four parts: power supply, signal acquisition, data processing, keyboard and liquid crystal display. Among them, the power supply part provides DC working power for the measuring device; the signal acquisition part completes the transformation, amplification, and acquisition of the traceability signal and the measurement signal, and converts it into a digital signal for the data processing part; the data processing part compares the traceability signal and the measurement signal The corresponding digital signals are processed by Fourier analysis, spectrum comparison and difference measurement; the keyboard and liquid crystal display part realize human-computer interaction.

The single-phase step-down transformer T3 is connected to the output side of the single-phase step-up transformer T2, and steps down the output voltage of the single-phase step-up transformer T2 to the rated voltage of the AC side of the load of the single-phase fully-controlled rectifier bridge.

The load of the single-phase full-control rectifier bridge is connected to the output side of the single-phase step-down transformer T3, and through the change of the DC side load and the adjustment of the trigger angle, the harmonic current of the AC side is changed, so that the output of the single-phase step-up transformer T2 can be Changing harmonic voltage.

Please refer to Fig. 1, the method for detecting harmonic characteristics of an electronic voltage transformer provided by an embodiment of the present invention adopts the above-mentioned device for detecting harmonic characteristics of an electronic voltage transformer, and the detection method includes the following steps:

Step 1, boosting the output of the voltage regulator T1 to the primary rated voltage of the single-phase step-up transformer T2;

Step 2. When the load conditions of the fully-controlled rectifier bridge are sequentially selected as resistive load, resistive-inductive series load, and resistive-capacitive parallel load, gradually change the trigger angle so that the harmonic components and content in the AC side current of the fully-controlled rectifier bridge Changes, when flowing through the internal impedance of the power frequency power supply and the voltage regulator T1 and the short-circuit impedance of the single-phase step-up transformer T2, a harmonic voltage with variable composition and content, similar to the actual operation of the power grid, is generated. The voltage is applied to the capacitive voltage divider and the voltage transformer to be detected;

Step 3: The traceable signal measured at the low-voltage end of the capacitor voltage divider and the output signal of the voltage transformer to be tested are input into the measurement device, and the measurement device performs Fourier analysis on the two signals to decompose the fundamental wave and The amplitude and phase information of each harmonic, so as to obtain the frequency spectrum of the two signals, including the amplitude spectrum and phase spectrum. Based on the traceability signal, the amplitude sum of the fundamental wave and each harmonic of the two signals is obtained. The phase difference is used to obtain the harmonic characteristics of the voltage transformer to be detected.

The electronic voltage transformer harmonic characteristic detection method and its detection device of the present invention utilize the change of the full-control rectifier bridge load and the adjustment of the trigger angle to generate a harmonic current with variable composition and content on the AC side of the full-control rectifier bridge , the current generates harmonic voltages with variable composition and content on the internal impedance of the power frequency power supply and the voltage regulator T1 and the short-circuit impedance of the single-phase step-up transformer T2, and is applied to the capacitive voltage divider and the transformer to be tested. This voltage truly simulates the actual situation of the harmonic voltage of the power grid. Through the comparison and analysis of the frequency spectrum and difference measurement of the low-voltage side traceability signal of the capacitor voltage divider and the output signal of the voltage transformer to be tested by the measuring device, the harmonic of the voltage transformer can be accurately grasped. Wave response characteristics, so as to achieve accurate measurement of harmonic voltage.

Claims (3)

1. A harmonic characteristic detection device of an electronic voltage transformer, comprising a voltage regulator, a single-phase step-up transformer, a capacitive voltage divider, a voltage transformer to be detected, a measuring device, a single-phase step-down transformer and a single-phase full Controlled rectifier bridge load composition, characterized in that: The input side of the voltage regulator is connected to the power frequency test power supply, and its output side provides an adjustable input voltage for the single-phase step-up transformer; the input side of the single-phase step-up transformer is connected to the output side of the voltage regulator to boost the power supply voltage to the test voltage; the capacitive voltage divider is the measurement traceability standard, and is connected to the output side of the single-phase step-up transformer to provide traceability signals for the measuring device; the voltage transformer to be detected is connected to the output side of the single-phase step-up transformer, and The output side provides the detected signal for the measuring device; the single-phase step-down transformer is connected to the output side of the single-phase step-up transformer to step down the output voltage of the single-phase step-up transformer to the rated value of the AC side of the load of the single-phase fully-controlled rectifier bridge. voltage; the load of the single-phase full-control rectifier bridge is connected to the output side of the single-phase step-down transformer, and through the change of the DC side load and the adjustment of the trigger angle, the harmonic current of the AC side is changed, so that the output of the single-phase step-up transformer can be The harmonic voltage changed; the measuring device receives the traceable signal from the low-voltage side of the capacitive voltage divider and the output signal of the voltage transformer to be tested, and performs spectrum and difference analysis to obtain the harmonic characteristics of the transformer to be tested. 2. The harmonic characteristic detection device of electronic voltage transformer according to claim 1, wherein said measuring device is mainly composed of four parts: power supply, signal acquisition, data processing, keyboard and liquid crystal display, wherein: power supply The part provides DC working power for the measurement device; the signal acquisition part completes the transformation, amplification, and acquisition of the traceability signal and the measurement signal, and converts it into a digital signal for the data processing part; The signal is processed by Fourier analysis, spectrum comparison and difference measurement; the keyboard and liquid crystal display part realize human-computer interaction. 3. a harmonic characteristic detection method of electronic voltage transformer, adopts detection device as claimed in claim 1, and described detection method comprises the following steps: Step 1, boosting the output of the voltage regulator to the primary rated voltage of the single-phase step-up transformer; Step 2. When the load conditions of the fully-controlled rectifier bridge are successively selected as resistive load, resistive-inductive series load and resistive-capacitive parallel load, gradually change the trigger angle so that the harmonic components and content in the AC side current of the fully-controlled rectifier bridge Changes, when flowing through the internal impedance of the power frequency power supply and voltage regulator and the short-circuit impedance of the single-phase step-up transformer, a harmonic voltage with variable composition and content, similar to the actual operation of the power grid, is generated. The harmonic voltage is applied On the capacitive voltage divider and the voltage transformer to be tested; Step 3: The traceable signal measured at the low-voltage end of the capacitor voltage divider and the output signal of the voltage transformer to be tested are input into the measurement device, and the measurement device performs Fourier analysis on the two signals to decompose the fundamental wave and The amplitude and phase information of each harmonic, so as to obtain the frequency spectrum of the two signals, including the amplitude spectrum and phase spectrum. Based on the traceability signal, the amplitude sum of the fundamental wave and each harmonic of the two signals is obtained. The phase difference is used to obtain the harmonic characteristics of the voltage transformer to be detected.

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