CN110208603A - A kind of transformer voltage phase difference measuring apparatus and measurement method - Google Patents

Abstract

The invention discloses a transformer voltage phase difference measuring instrument and a measuring method, comprising a digital signal processor, a voltage measuring unit, a voltage zero-crossing comparison circuit and a display screen; The input terminal is input; the output terminals of the voltage measuring unit and the voltage zero-crossing comparison circuit are connected to the input terminal of the digital signal processor, and the output terminal of the digital signal processor is connected to the interface of the display screen. The input voltage is converted into a pulse signal through the voltage zero-crossing comparison circuit, and the first time point when the primary side pulse signal changes from low level to high level is detected, and the clock starts counting; the secondary side pulse signal is detected from low level to high level. At the first time point of flatness, the clock cuts off timing, and the voltage phase difference is calculated and displayed according to the timing time difference and clock frequency. The invention saves long wiring, reduces the cost, reduces the danger in the operation process, is simple and convenient to operate, and has strong practicability.

Description

A transformer voltage phase difference measuring instrument and measuring method

technical field

The invention belongs to the field of power systems, in particular to a measuring instrument for measuring the magnitude and phase difference of phase voltages at both ends of a transformer.

Background technique

In order to obtain the phase difference of the voltage on both sides of the transformer, the current voltage phase difference measuring instrument on the market needs to connect the primary side and the secondary side of the transformer through wiring at the same time for measurement.

The transformer voltage phase difference measuring instruments on the market are connected to both sides of the transformer at the same time through wired methods. Since the primary side and secondary side of some transformers are far away, the wired connection process is cumbersome, which will increase the danger and complexity of the actual operation process. sex.

Contents of the invention

Purpose of the invention: In order to solve the problem in the prior art that measuring the transformer phase difference must measure the primary side and the secondary side at the same time, the connection is long and the operation is dangerous and complicated. The present invention provides a transformer voltage phase difference measuring instrument.

The invention provides a transformer voltage phase difference measurement method.

Technical solution: a transformer voltage phase difference measurement method, comprising the following steps:

(1) Measure the voltage value of a certain phase voltage on the primary side of the transformer, and at the same time output the primary side voltage signal through the zero-crossing comparator to obtain the primary side voltage pulse signal, and detect the first time the primary side voltage pulse signal changes from low level to high level A time point, as the starting timing point of the internal clock of the digital signal processor, starts counting;

(2) Measure the voltage value of the same phase voltage on the secondary side of the transformer, and output the voltage signal of the secondary side through the zero-crossing comparator to obtain the voltage pulse signal of the secondary side; detect the voltage pulse signal of the secondary side from low level to high The first time point of the level is used as the cut-off timing point of the internal clock of the digital signal processor, and the time difference T between the two measurements is obtained when the timing is cut off;

(3) Provide the frequency f of the primary side phase voltage of the transformer, take the remainder c of T/(1/f), and calculate the voltage phase difference by the formula:

in, is the voltage phase difference between the primary side and the secondary side of the transformer;

(4) Display the voltage phase difference, the voltage value of the primary side voltage and the voltage value of the secondary side voltage on the display screen.

Further, the clock adopts the internal clock of the digital signal processor, and the maximum operating frequency is 150MHz.

A transformer voltage phase difference measuring instrument, comprising a digital signal processor, a voltage measuring unit, a voltage zero-crossing comparison circuit and a display screen; an input voltage signal is simultaneously input from the input end of the voltage measurement unit and the input end of the voltage zero-crossing comparison circuit; The output terminal of the voltage measurement unit and the output terminal of the voltage zero-crossing comparison circuit are connected to the input terminal of the digital signal processor, and the output terminal of the digital signal processor is connected to the interface of the display screen; the digital signal processor is used for calculating the voltage phase difference.

Further, the voltage zero-crossing comparison circuit includes a voltage transformer and a voltage zero-crossing comparator, the input voltage signal is input from the voltage transformer, the output signal of the voltage transformer is input from the voltage zero-crossing comparator, and the voltage zero-crossing comparator The output signal of the device is input to the digital signal processor.

Further, the voltage zero-crossing comparator adopts an LM339 comparator, and the input voltage signal is input to the inverting input terminal of the comparator through a resistor R1; the comparison voltage signal is connected to the same input terminal of the comparator through a resistor R _f1 ; the output terminal of the comparator is connected to A resistor R _f2 is connected between the same-direction input terminals; a pull-up resistor is also included, and the pull-up resistor is connected between the output terminal of the comparator and the power supply terminal.

Further, the digital signal processor adopts TMS320F28335 chip.

Further, a built-in oscillator is used; a 30MHz quartz crystal oscillator is connected between clock pins X1 and X2 of the TMS320F28335 chip; and pins X1 and X2 are grounded through electrolytic capacitors CL1 and CL2 respectively.

Further, the display screen is an LCD display screen.

Further, the voltage measuring unit is a voltage measuring instrument.

Further, the voltage measuring instrument is integrated into a transformer voltage phase difference measuring instrument.

Beneficial effects: the present invention provides a transformer voltage phase difference measuring instrument and measuring method. Compared with the prior art, the voltage phase difference can be obtained by separately measuring the corresponding phase voltages of the primary side and the secondary side of the transformer, avoiding simultaneous connection of the measuring transformer once The phase voltage between the side and the secondary side saves a long wiring, reduces the cost, reduces the danger in the operation process, the operation is simple and convenient, and the practicability is strong.

Description of drawings

Figure 1 is a block diagram of the system;

Figure 2 is a clock design schematic diagram of the TMS320F28335 chip;

Figure 3 is a schematic diagram of the voltage zero-crossing comparison circuit.

Detailed ways

The present invention will be further described below in conjunction with the accompanying drawings and specific embodiments.

As shown in Figure 1, a transformer voltage phase difference measuring instrument includes a digital signal processor (DSP), a voltage measuring unit, a voltage zero-crossing comparison circuit and an LCD display; the voltage measuring unit is a voltage measuring instrument integrated in the measuring instrument, The numerical value of the phase voltage is obtained by a voltage measuring instrument; the input voltage signal is input from the input terminal of the voltage measurement unit and the input terminal of the voltage zero-crossing comparison circuit at the same time; the output terminal of the voltage measurement unit and the output terminal of the voltage zero-crossing comparison circuit are connected to digital The input end of the signal processor and the output end of the digital signal processor are connected to the interface of the display screen; the digital signal processor is used for calculating the voltage phase difference.

The internal integrated voltage measurement unit can measure the value of the phase voltage, and finally display the value through the LCD display.

The voltage zero-crossing comparator circuit includes a step-down circuit and a voltage zero-crossing comparator. The step-down circuit is realized by a voltage transformer. The function of the voltage transformer is to isolate high voltage and convert the voltage to a voltage that the voltage zero-crossing comparator can bear range, and then input the voltage zero-crossing comparator to get a series of pulse signals. As shown in Figure 3, the voltage zero-crossing comparator uses an LM339 comparator, and the input voltage signal is input to the inverting input terminal of the comparator through the resistor R1; the comparison voltage signal is connected to the same input terminal of the comparator through the resistor R _f1 ; the output terminal of the comparator A resistor R _f2 is connected between the same input terminal and a pull-up resistor connected between the output terminal of the comparator and the power supply terminal. The voltage zero-crossing comparison circuit can convert the measured voltage analog signal of the transformer into a pulse signal and input it to the DSP for subsequent processing.

The main control chip of the digital signal processor adopts the TMS320F28335 chip. This embodiment adopts a built-in oscillator, and a 30MHz quartz crystal oscillator is connected between the clock pins X1 and X2 of the TMS320F28335 chip; Programming selects the PLL function of 5 times frequency, which can realize the highest working frequency of F28335 150MHz.

The transformer voltage phase difference measuring instrument can measure the corresponding phase voltages of the primary side and the secondary side of the transformer respectively (for example, phase A of the primary side of the transformer must strictly correspond to the voltage of phase a of the secondary side of the transformer), and finally obtain it through internal DSP calculation. The phase difference of the two measured voltages is displayed on the LCD display of the measuring instrument. It avoids connecting the phase voltage of the primary side and the secondary side of the measuring transformer at the same time, saves a long wiring operation, and has strong practicability.

A transformer voltage phase difference measurement method, comprising the following steps:

(1) Measure the voltage value of a certain phase voltage on the primary side of the transformer, and at the same time output the primary side voltage signal through the zero-crossing comparator to obtain the primary side voltage pulse signal, and detect the first time the primary side voltage pulse signal changes from low level to high level A time point, as the starting timing point of the internal clock of the digital signal processor, starts counting;

(2) Measure the voltage value of the same phase voltage on the secondary side of the transformer, and output the voltage signal of the secondary side through the zero-crossing comparator to obtain the voltage pulse signal of the secondary side; detect the voltage pulse signal of the secondary side from low level to high The first time point of the level is used as the cut-off timing point of the internal clock of the digital signal processor, and the time difference T between the two measurements is obtained when the timing is cut off;

(3) Provide the frequency f of the primary side phase voltage of the transformer, such as the national standard 50Hz under normal circumstances, take the remainder c of T/(1/f), and calculate the voltage phase difference by the formula:

in, is the voltage phase difference between the primary side and the secondary side of the transformer;

(4) Display the voltage phase difference, the voltage value of the primary side voltage and the voltage value of the secondary side voltage on the display screen.

Claims (10)

1. a transformer voltage phase difference measurement method, is characterized in that, comprises the following steps: (1) Measure the voltage value of a certain phase voltage on the primary side of the transformer, and at the same time output the primary side voltage signal through the zero-crossing comparator to obtain the primary side voltage pulse signal, and detect the first time the primary side voltage pulse signal changes from low level to high level A time point, as the starting timing point of the clock, starts timing; (2) Measure the voltage value of the same phase voltage on the secondary side of the transformer, and output the voltage signal of the secondary side through the zero-crossing comparator to obtain the voltage pulse signal of the secondary side; detect the voltage pulse signal of the secondary side from low level to high The first time point of the level is used as the cut-off timing point of the clock, and the time difference T between the two measurements is obtained when the timing is cut off; (3) Provide the frequency f of the primary side phase voltage of the transformer, take the remainder c of T/(1/f), and calculate the voltage phase difference by the formula: in, is the voltage phase difference between the primary side and the secondary side of the transformer; (4) Display the voltage phase difference, the voltage value of the primary side voltage and the voltage value of the secondary side voltage on the display screen. 2. The method for measuring the phase difference of transformer voltage according to claim 1, wherein the clock adopts an internal clock of a digital signal processor with a maximum operating frequency of 150MHz. 3. A transformer voltage phase difference measuring instrument, characterized in that, comprises a digital signal processor, a voltage measuring unit, a voltage zero-crossing comparison circuit and a display screen; the input voltage signal is compared with the voltage zero-crossing input terminal of the voltage measuring unit simultaneously The input terminal of the circuit is input; the output terminal of the voltage measurement unit and the output terminal of the voltage zero-crossing comparison circuit are connected to the input terminal of the digital signal processor, and the output terminal of the digital signal processor is connected to the interface of the display screen. 4. The transformer voltage phase difference measuring instrument according to claim 3, wherein the voltage zero-crossing comparison circuit comprises a voltage transformer and a voltage zero-crossing comparator, the input voltage signal is input from the voltage transformer, and the voltage The output signal of the transformer is input from the voltage zero-crossing comparator, and the output signal of the voltage zero-crossing comparator is input into the digital signal processor. 5. The transformer voltage phase difference measuring instrument according to claim 4, wherein the voltage zero-crossing comparator adopts an LM339 comparator, and the input voltage signal passes through the reverse input terminal of the resistor R1 input comparator; the comparison voltage signal passes through the resistor R1. R _f1 is connected to the non-inverting input terminal of the comparator; a resistor R _f2 is connected between the output terminal of the comparator and the non-inverting input terminal; a pull-up resistor is also included, and the pull-up resistor is connected between the output terminal of the comparator and the power supply terminal. 6. The transformer voltage phase difference measuring instrument according to claim 3, wherein the digital signal processor adopts a TMS320F28335 chip. 7. transformer voltage phase difference measuring instrument according to claim 6, is characterized in that, adopts built-in oscillator; Insert the quartz crystal oscillator of 30MHz between the clock pin X1 of TMS320F28335 chip and X2; And pin X1 and pin X2 They are respectively grounded through electrolytic capacitors CL1 and CL2. 8. The transformer voltage phase difference measuring instrument according to claim 3, wherein the display screen is an LCD display screen. 9. The transformer voltage phase difference measuring instrument according to claim 3, wherein the voltage measuring unit is a voltage measuring instrument. 10. The transformer voltage phase difference measuring instrument according to claim 3, characterized in that, the voltage measuring instrument is integrated in the transformer voltage phase difference measuring instrument.