阅读说明：本技术 一种ct极性检测仪及其检测方法 (CT polarity detector and detection method thereof ) 是由 柳明 廖华 苏晓 朱伟 姜宪彬 李黄河 何山 兰福生 邱杰昌 崔堂山 曹超 陈 于 2019-10-30 设计创作，主要内容包括：本发明公开了一种CT极性检测仪及其检测方法,CT极性检测仪包括电源模块、处理器、采样电阻、AD采样单元、放大电路、极性检测电路、电压显示单元和LED显示单元,所述电源模块分别连接处理器和CT一次绕组,CT二次绕组连接所述采样电阻,所述采样电阻分别连接所述AD采样单元和所述放大电路,所述AD采样单元连接所述处理器,所述处理器连接所述LED显示单元,所述放大电路连接所述电压显示单元以及极性检测电路,所述极性检测电路连接所述处理器。本发明的CT极性检测仪,实现瞬间接通后自动关断锂电池供电电源从而保护电池。(The invention discloses a CT polarity detector and a detection method thereof, wherein the CT polarity detector comprises a power supply module, a processor, a sampling resistor, an AD sampling unit, an amplifying circuit, a polarity detection circuit, a voltage display unit and an LED display unit, the power supply module is respectively connected with the processor and a CT primary winding, a CT secondary winding is connected with the sampling resistor, the sampling resistor is respectively connected with the AD sampling unit and the amplifying circuit, the AD sampling unit is connected with the processor, the processor is connected with the LED display unit, the amplifying circuit is connected with the voltage display unit and the polarity detection circuit, and the polarity detection circuit is connected with the processor. The CT polarity detector of the invention realizes that the power supply of the lithium battery is automatically turned off after instant connection, thereby protecting the battery.)

1. A CT polarity detector is characterized by comprising a power module, a processor, a sampling resistor, an AD sampling unit, an amplifying circuit, a polarity detection circuit, a voltage display unit and an LED display unit, wherein the power module is respectively connected with the processor and a CT primary winding, a CT secondary winding is connected with the sampling resistor, the sampling resistor is respectively connected with the AD sampling unit and the amplifying circuit, the AD sampling unit is connected with the processor, the processor is connected with the LED display unit, the amplifying circuit is connected with the voltage display unit and the polarity detection circuit, and the polarity detection circuit is connected with the processor; the power supply module comprises a lithium battery power supply circuit, a lithium battery charging circuit and a mains supply conversion power supply circuit, the lithium battery power supply circuit comprises a first lithium battery power supply circuit and a second lithium battery power supply circuit, the first lithium battery power supply circuit is connected with a CT primary winding, the second lithium battery power supply circuit is connected with the processor, the lithium battery charging circuit comprises a first lithium battery charging circuit and a second lithium battery charging circuit, the first lithium battery charging circuit is connected with the first lithium battery power supply circuit, the second lithium battery charging circuit is connected with the second lithium battery power supply circuit, and the mains supply conversion power supply circuit is respectively connected with the first lithium battery charging circuit, the second lithium battery charging circuit and the CT primary winding; the CT primary winding, the first lithium battery power supply circuit and the mains supply conversion power supply circuit are respectively provided with a switch device, and the switch devices are connected with the processor.

2. The CT polarity detector of claim 1, wherein the first lithium battery charging circuit and the second lithium battery charging circuit both employ TC 4056.

3. The CT polarity detector of claim 1, wherein a boost switching regulator and a low dropout voltage regulator are further connected between the second lithium battery power supply circuit and the processor.

4. The CT polarity detector of claim 3, wherein the boost switching regulator employs ME2109 and the low dropout voltage regulator employs LM 1117.

5. The CT polarity detector of claim 1, wherein a lithium battery protection integrated circuit is disposed in each of the first lithium battery charging circuit and the second lithium battery charging circuit, and DW01 is adopted for the lithium battery protection integrated circuits.

6. The CT polarity detector of claim 1, wherein said switching device is a field effect transistor.

7. A CT polarity detection method using the CT polarity detector of any one of claims 1 to 6, comprising the steps of: the first lithium battery power supply module and the commercial power conversion power supply circuit can select any power supply mode to supply power to the CT primary winding; one side of the CT secondary winding acquires a sampling signal through a sampling resistor, the sampling signal is converted through an AD sampling unit and then sent to a processor, and the processor receives the testing signal sent by the processor and then turns off power supply connected with the CT primary winding through a switching device; on the other hand, the signal amplified by the amplifying circuit is displayed by the voltage display unit, and the swing condition of the voltage pointer can be observed when the voltage display unit displays the signal so as to judge the polarity of the CT; the signals after passing through the amplifying circuit are processed by a polarity detection circuit to provide input signals for an AD sampler of the processor, and finally the polarity of the CT is judged by the processor.

Technical Field

The invention belongs to the technical field of testing of electric windings, and particularly relates to a CT polarity detector and a CT polarity detection method thereof.

Background

Current Transformers (CTs) are important electrical components of power systems, and play a role in isolating high and low voltage systems and converting high voltage to low voltage. Whether the wiring is correct or not has extremely important significance for the normal work of equipment such as protection, measurement, metering and the like of the system. When a CT is newly installed and a CT secondary cable is put into operation or replaced, the correctness of the CT polarity measurement is already an indispensable working procedure for relay protection workers.

The traditional CT polarity measurement method uses a battery and a pointer meter, judges the polarity by short-circuiting the battery and then looking at the swinging of the pointer meter, and has the defects of instant disappearance, larger battery loss ratio and poorer convenience.

Disclosure of Invention

The invention aims to: the CT polarity detector can be used for carrying out data sampling analysis on a test, can record a test result on a display screen, is convenient to record the test result, and can also be used for observing the swing effect of a test pointer in real time through a pointer meter.

In order to achieve the purpose, the invention adopts the technical scheme that:

a CT polarity detector comprises a power module, a processor, a sampling resistor, an AD sampling unit, an amplifying circuit, a polarity detection circuit, a voltage display unit and an LED display unit, wherein the power module is respectively connected with the processor and a CT primary winding, a CT secondary winding is connected with the sampling resistor, the sampling resistor is respectively connected with the AD sampling unit and the amplifying circuit, the AD sampling unit is connected with the processor, the processor is connected with the LED display unit, the amplifying circuit is connected with the voltage display unit and the polarity detection circuit, and the polarity detection circuit is connected with the processor; the power supply module comprises a lithium battery power supply circuit, a lithium battery charging circuit and a mains supply conversion power supply circuit, the lithium battery power supply circuit comprises a first lithium battery power supply circuit and a second lithium battery power supply circuit, the first lithium battery power supply circuit is connected with a CT primary winding, the second lithium battery power supply circuit is connected with the processor, the lithium battery charging circuit comprises a first lithium battery charging circuit and a second lithium battery charging circuit, the first lithium battery charging circuit is connected with the first lithium battery power supply circuit, the second lithium battery charging circuit is connected with the second lithium battery power supply circuit, and the mains supply conversion power supply circuit is respectively connected with the first lithium battery charging circuit, the second lithium battery charging circuit and the CT primary winding; the CT primary winding, the first lithium battery power supply circuit and the mains supply conversion power supply circuit are respectively provided with a switch device, and the switch devices are connected with the processor.

Optionally, the first lithium battery charging circuit and the second lithium battery charging circuit both use TC 4056.

Optionally, a boost switching regulator and a low dropout voltage regulator are further connected between the second lithium battery power supply circuit and the processor.

Optionally, the boost switching regulator adopts ME2109, and the low dropout voltage regulator adopts LM 1117.

Optionally, a lithium battery protection integrated circuit is disposed in each of the first lithium battery charging circuit and the second lithium battery charging circuit, and DW01 is adopted in the lithium battery protection integrated circuit.

Optionally, the switching device is a field effect transistor.

A CT polarity detection method using the CT polarity detector as described above, comprising the steps of: the first lithium battery power supply module and the commercial power conversion power supply circuit can select any power supply mode to supply power to the CT primary winding; one side of the CT secondary winding acquires a sampling signal through a sampling resistor, the sampling signal is converted through an AD sampling unit and then sent to a processor, and the processor receives the testing signal sent by the processor and then turns off power supply connected with the CT primary winding through a switching device; on the other hand, the signal amplified by the amplifying circuit is displayed by the voltage display unit, and the swing condition of the voltage pointer can be observed when the voltage display unit displays the signal so as to judge the polarity of the CT; the signals after passing through the amplifying circuit are processed by a polarity detection circuit to provide input signals for an AD sampler of the processor, and finally the polarity of the CT is judged by the processor.

Due to the adoption of the technical scheme, the invention has the beneficial effects that:

the CT polarity detector and the detection method thereof can carry out polarity detection by being connected with commercial power, and can also carry out detection by providing power supply through a lithium battery under the condition of no external power supply; when generating test current to the short circuit battery, can provide test signal through AD sampling unit to thereby can realize switching on in the twinkling of an eye the back automatic shutdown lithium cell power supply protection battery, the lithium cell is provided with charging source, and it is enough repetitious usage to charge once electric energy.

Drawings

FIG. 1 is a schematic block diagram of the circuit of the CT polarity detector of the present invention;

FIG. 2 is a circuit diagram of the CT secondary winding connection of the present invention;

FIG. 3 is a circuit diagram of the polarity detection circuit of the present invention;

fig. 4 is a circuit diagram of a first lithium battery charging circuit of the present invention;

FIG. 5 is a circuit diagram of a second lithium battery charging circuit of the present invention;

FIG. 6 is a circuit diagram of the 5V power supply of the present invention;

FIG. 7 is a 3.3V supply circuit diagram of the present invention;

fig. 8 is a lithium battery charging protection circuit of the present invention.

Reference numerals: 100-a power module, 101-a mains supply conversion power supply circuit, 102-a first lithium battery charging circuit, 103-a first lithium battery power supply circuit, 104-a second lithium battery charging circuit, 105-a second lithium battery power supply circuit, 106-a switching device, 300-a sampling resistor, 400-an amplifying circuit, 500-an AD sampling unit, 600-a voltage display unit, 700-a polarity detection circuit, 800-a processor and 900-an LED display unit.

Detailed Description

Referring to fig. 1, the CT polarity detector of the present invention includes a power module 100, a processor 800, a sampling resistor 300, an AD sampling unit 500, an amplifying circuit 400, a polarity detecting circuit 700, a voltage display unit 600, and an LED display unit 900, where the power module 100 is connected to the processor 800 and a CT primary winding, the CT secondary winding is connected to the sampling resistor 300, the sampling resistor 300 is connected to the AD sampling unit 500 and the amplifying circuit 400, the AD sampling unit 500 is connected to the processor 800, the processor 800 is connected to the LED display unit 900, and the amplifying circuit 400 is connected to the voltage display unit 600 and the polarity detecting circuit 700. The power module 100 provides the power for the primary winding of the CT, and one end of the secondary winding of the CT completes the sampling signal by connecting the sampling resistor 300. As shown in fig. 2, in this embodiment, the stm32 single chip microcomputer is used as the processor 800, the voltmeter is used as the voltage display unit 600, the triode Q is used as the amplifying circuit 400 in this embodiment, the optical coupler U15 is used as the AD sampling unit 500, the sampling signal can pass through the AD sampling unit 500, that is, the optical coupler U15, the sampling signal is transmitted to the processor 800 after being converted, the processor 800 can obtain power connection through the signal, and then the power supply of the primary winding of the CT is controlled by outputting the control signal instantaneously, so as to protect the power supply. The sampling signal can be amplified by the amplifying circuit 400, i.e. the triode Q, and then is connected to the voltage display unit 600, i.e. the voltmeter, and the pointer deflection condition of the voltmeter is observed by a manual observation method, so as to judge whether the cable connection of the CT secondary winding is correct. The signal passing through the transistor Q is also connected to the polarity detection circuit 700, and after being amplified by the polarity detection circuit 700, the signal is input to the processor 800, so as to provide an input for the AD sampler of the processor 800.

As shown in fig. 3, the polarity detection circuit 700 includes a first amplifier and a second amplifier connected in series, the first amplifier employs an OP2177, and the second amplifier employs a TL072 JFET. The OP2177 is composed of an amplifier with extremely high precision, and has the characteristics of extremely low offset voltage and drift, low input bias current, low noise, low power consumption and the like. The output is stable when capacitive loads above 1000pF are used, and no external compensation is required. The supply current of each amplifier is less than 500 mua at a supply voltage of 30V. The built-in 500 omega series resistor can protect input signals, allows the level of the input signals to be higher than the power supply voltage by a plurality of volts, and ensures no phase reversal. The TL072JFET input operational amplifier integrates well-matched high-voltage JFET and bipolar transistors in a monolithic integrated circuit. These devices have high slew rate, low input bias and offset current, and low offset voltage temperature coefficient, are used to form the CT polarity detection circuit 700, and provide input to the AD sampler of the CPU. The TPS60403 is a 60mA charge pump voltage inverter with fixed 250kHz operation to provide-5V power for the op-amp.

The power module 100 comprises a lithium battery power supply circuit, a lithium battery charging circuit and a mains supply conversion power supply circuit 101, wherein the lithium battery power supply circuit comprises a first lithium battery power supply circuit 103 and a second lithium battery power supply circuit 105, the first lithium battery power supply circuit 103 is connected with a CT primary winding, the second lithium battery power supply circuit 105 is connected with the processor 800, the lithium battery charging circuit comprises a first lithium battery charging circuit 102 and a second lithium battery charging circuit 104, the first lithium battery charging circuit 102 is connected with the first lithium battery power supply circuit 103, the second lithium battery charging circuit 104 is connected with the second lithium battery power supply circuit 105, and the mains supply conversion power supply circuit 101 is respectively connected with the first lithium battery charging circuit 102, the second lithium battery charging circuit 104 and the CT primary winding; the CT primary winding, the first lithium battery power supply circuit 103 and the commercial power conversion power supply circuit 101 are respectively provided with a switching device 106, and the switching device 106 is connected to the processor 800.

The power supply connected to the CT primary winding may be a power supply directly provided by the commercial power conversion power supply circuit 101, or may be supplied by the first lithium battery power supply circuit 103. The utility power conversion power supply circuit 101 mainly converts 220V ac power into dc 5V-20A, and then can be directly used by other 5V devices, and can also be reduced to a 3.7V dc circuit by the voltage reduction circuit to be used by other 3.7V devices, and the utility power conversion power supply circuit 101 can be realized by adopting the existing circuit structure, and this embodiment is not described in detail. The CT polarity detector of the embodiment can complete CT polarity detection in a lithium battery power supply mode in a place without supplying commercial power.

The first lithium battery charging circuit 102 is shown in fig. 4, the second lithium battery charging circuit 104 is shown in fig. 5, both charging circuits adopt TC4056 charging ICs, and TC4056 is a complete single lithium battery linear charging IC adopting constant current/constant voltage.

In the embodiment, two groups of lithium batteries are adopted to form two groups of lithium battery power supply circuits, namely a first lithium battery power supply circuit 103 and a second lithium battery power supply circuit 105, wherein the first lithium battery power supply circuit 103 is connected with a primary winding of a CT and is used for supplying power to the CT; the second lithium battery power supply circuit 105 is connected with the processor 800 and is used for supplying power to the processor 800, so that mutual interference can be effectively prevented. Still be connected with switching device 106 between first lithium cell supply circuit 103 and the CT primary winding, switching device 106 is the field effect transistor who sets up between lithium cell and CT primary winding in this embodiment, through processor 800 output control signal, can in time break off the power supply of lithium cell to CT to play the effect of protection lithium cell. Of course, the switching device 106 may also be disposed between the commercial power conversion power supply circuit 101 and the CT, so that the processor 800 can control the output signal to cut off the power supply.

A boost switching regulator and a low dropout voltage regulator are also connected between the second lithium battery power supply circuit 105 and the processor 800. As shown in fig. 6 and fig. 7, the boost switching regulator adopts ME2109 series, and ME2109 series adopts CMOS boost switching regulator, which mainly includes a reference voltage source, an oscillation circuit, an error amplifier, a phase compensation circuit, and a PWM/PFM switching control circuit. The product is suitable for the application needing high efficiency and high output current with the external N-channel power MOS with low on-resistance. The ME2109 series switch operation PFM control circuit has the duty ratio of a PWM/PFM switching control circuit under 15% light load, and the working current efficiency of an IC is prevented from being reduced. The voltage provided by the second lithium battery power supply circuit 105 can be stabilized at 5V by the boost switching regulator, and then regulated to 3.3V by the low dropout voltage regulator, which uses LM1117, for the processor 800.

As shown in fig. 8, lithium battery protection integrated circuits are disposed in the first lithium battery charging circuit 102 and the second lithium battery charging circuit 104, and DW01 is adopted for the lithium battery protection integrated circuits.

The CT polarity detection method of the CT polarity detector of the present embodiment includes the following steps: the first lithium battery power supply module and the commercial power conversion power supply circuit 101 can select any power supply mode to supply power to the CT primary winding; one side of the CT secondary winding acquires a sampling signal through the sampling resistor 300, the sampling signal is converted through the AD sampling unit 500 and then sent to the processor 800, and the processor 800 receives the testing signal sent by the processor 800 and then turns off power supply connected with the CT primary winding through the switching device 106; on the other hand, the sampled signal is displayed by the voltage display unit 600 after being amplified by the amplifying circuit 400, and the swing condition of the voltage pointer can be observed when the voltage display unit 600 displays the sampled signal so as to judge the polarity of the CT; the signal after passing through the amplifying circuit 400 is processed by the polarity detection circuit 700 to provide an input signal for the AD sampler of the processor 800, and finally the polarity of CT is determined by the processor 800.

The CT polarity detector comprises the following operation steps:

1. the OLED display screen (namely the LED display unit 900) displays the test result;

2. the pointer meter (namely a voltmeter) displays the swing condition of the test pointer in real time;

3. the test key is used for testing by pressing the key when the equipment is in a test interface;

4. the 'clear' button is pressed before the next test is carried out, and the next test is ready;

5. an instrument power switch;

6. the test power supply is selected, the 'power supply' is selected to test the conversion power supply supplied by the external AC220V for testing, and the 'battery' is selected to test the internal battery power supply for testing.