CN120908567A

CN120908567A - Telemetry loop, measurement and control device and telemetry method

Info

Publication number: CN120908567A
Application number: CN202511054944.1A
Authority: CN
Inventors: 王健梅; 薛国龙; 赵佳怡; 李宁芳; 宋鑫
Original assignee: Huaneng Gansu Energy Development Co ltd 803 Branch
Current assignee: Huaneng Gansu Energy Development Co ltd 803 Branch
Priority date: 2025-07-30
Filing date: 2025-07-30
Publication date: 2025-11-07

Abstract

This invention relates to the field of measurement and control, and mainly discloses a telemetry loop, a measurement and control device, and a telemetry method. The device includes a PT terminal box, which is connected to the input terminals of current transformers Ua, Ub, and Uc within the line measurement and control system via lines Ua, Ub, and Uc, respectively. The output terminals of the current transformers Ua, Ub, and Uc are all connected to the PT terminal box via line Un. By connecting lines Ua, Ub, and Uc to line Un to form a loop, with line Un serving as a common reference point, it ensures that each phase voltage measurement has a common reference point, thereby improving the accuracy and stability of the measurement. A rotary switch, by switching different positions, can flexibly select different voltage signal paths to meet the line voltage and phase voltage measurement requirements during normal operation, and to provide more comprehensive diagnostic information during fault analysis.

Description

Telemetry loop, measurement and control device and telemetry method

Technical Field

The invention relates to the field of measurement and control, in particular to a telemetry loop, a measurement and control device and a telemetry method.

Background

The measurement and control cabinet can measure and monitor the electrical parameters such as current, voltage, power, frequency and the like of the line in real time, and provides accurate data support for the stable operation of the power system. For example, the load condition of the circuit can be judged by monitoring the current, and the electric equipment can be ensured to work in a proper voltage range according to the voltage value.

In a three-phase power system, most of line measurement and control in a measurement and control device directly monitors three-phase power, reference voltage is not provided, so that measured voltages of all phases are not accurate enough, and the conventional measurement and control device cannot realize switching between line voltage measurement and phase voltage measurement, so that more comprehensive diagnosis information is difficult to provide during fault analysis.

Disclosure of Invention

Therefore, the invention aims to solve the technical problems that the measured voltages of all phases are not accurate enough and the line voltage measurement and the switching of the phase voltage measurement cannot be realized.

The technical problems are solved by the invention, which provides a telemetry loop comprising,

The PT terminal box is connected with the input ends of the Ua transformer, the Ub transformer and the Uc transformer in the line measurement and control through the Ua line, the Ub line and the Uc line respectively;

The output ends of the Ua transformer, the Ub transformer and the Uc transformer are connected with the PT terminal box through Un wires;

The opening and closing of the Ua line, the Ub line and the Uc line are controlled by rotary switches.

In a preferred embodiment of the telemetry circuit of the present invention, the rotary switch includes contact one, contact two, contact three, contact four, contact five and contact six;

The first contact and the second contact are connected to the Ua wire, the third contact and the fourth contact are connected to the Ub wire, and the fifth contact and the sixth contact are connected to the Uc wire.

In a preferred embodiment of the telemetry circuit, a Uo transformer is arranged in the circuit measurement and control, the input end of the Uo transformer is connected with a PT terminal box through a Uo wire, the output end of the Uo transformer is connected with a Uon wire, and the Uon wire is connected with a Un wire.

In a preferred embodiment of the telemetry loop, the telemetry loop further comprises a CT terminal box, wherein the CT terminal box is respectively connected with input ends of an Ia mutual inductor, an Ib mutual inductor and an Ic mutual inductor in line measurement and control through an Ia line, an Ib line and an Ic line, output ends of the Ia mutual inductor, the Ib mutual inductor and the Ic mutual inductor are respectively connected with an Ian line, an Ibn line and an Icn line, the Ian line is connected with the Ibn line, the Ibn line is connected with the Icn line, and the Ian line, the Ibn line or the Icn line is connected with the CT terminal box.

In a preferred embodiment of the telemetry loop, an Io transformer is arranged in the line measurement and control, the input end of the Io transformer is connected with the CT terminal box through an Io line, and the output end of the Io transformer is connected with the CT terminal box through an Ion line.

The invention provides a measurement and control device which comprises a cabinet body, wherein a line measurement and control device is arranged in the cabinet body and comprises a Ua transformer, a Ub transformer, a Uc transformer, a Uo transformer, an Ia transformer, an Ib transformer, an Ic transformer and an Io transformer, and the line measurement and control device is respectively connected with a PT terminal box and a CT terminal box.

The invention provides a telemetry method of a measurement and control device, which comprises the following steps:

S1, line measurement and control receives each phase voltage signal and zero sequence voltage signal transmitted by a PT terminal box, and each phase current signal and zero sequence current signal transmitted by a CT terminal box;

S2, calculating effective values of line voltage, phase voltage and current, power factor and frequency according to the collected voltage and current signals;

And S3, monitoring the running state of the power system in real time, and judging whether overload, short circuit or ground fault occurs.

In a preferred embodiment of the telemetry method of the measurement and control device, in step S1, line measurement and control receives voltage signals of each phase from a PT terminal box through Ua line, ub line and Uc line, receives zero sequence voltage signals through Uo line, receives current signals of each phase from a CT terminal box through Ia line, ib line and Ic line, and receives zero sequence current signals through Io line.

In a preferred implementation mode of the telemetry method of the measurement and control device, in step S2, line measurement and control performs preliminary processing on collected voltage signals and zero sequence voltage signals of each phase, and performs preliminary processing on collected current signals and zero sequence current signals of each phase;

the line measurement and control converts the processed voltage signals, zero sequence voltage signals, current signals and zero sequence current signals of each phase into digital signals;

and calculating the effective values of line voltage, phase voltage and current, and power, power factor and frequency according to the converted digital signals.

In a preferred implementation mode of the telemetry method of the measurement and control device, in step S3, line measurement and control monitors the running state of the power system in real time through the PT terminal box and the CT terminal box, when the monitored voltage or current exceeds a preset threshold value, the system is judged to be likely to have overload or short-circuit faults, and when the monitored zero-sequence voltage or zero-sequence current exceeds the preset threshold value, the system is judged to be likely to have ground faults;

when detecting the system fault, the measurement and control device sends out an alarm signal and adopts corresponding protection measures according to the preset protection logic.

The invention has the beneficial effects that the Ua line, the Ub line and the Uc line are connected to the Un line to form a loop, the Un line is used as a common reference point, and the measurement of each phase voltage can be ensured to have a common reference point, thereby improving the accuracy and the stability of the measurement;

When the phase voltage needs to be measured, the rotary switch is switched to the corresponding position, so that the two-phase voltage signal of the PT terminal box is transmitted to the measurement and control device, the measurement and control device calculates the outlet voltage according to the received two-phase voltage signal, and when the phase voltage needs to be measured, the rotary switch is switched to the corresponding position, a certain phase voltage signal of the PT terminal box and the neutral point are transmitted to the measurement and control device through the rotary switch, and the measurement and control device directly measures the voltage value of the phase voltage relative to the neutral point;

the rotary switch can flexibly select different voltage signal paths by switching different positions, thereby meeting the line voltage and phase voltage measurement requirements in normal operation and providing more comprehensive diagnosis information in fault analysis.

Drawings

In order to more clearly illustrate the technical solution of the embodiments of the present invention, the following description will briefly explain the drawings of the embodiments of the present invention. It will be apparent that the figures in the following description relate only to some embodiments of the invention and are not limiting of the invention. Wherein:

FIG. 1 shows a schematic connection of a PT terminal box to line measurement and control;

FIG. 2 shows a schematic diagram of the connection of a CT terminal box to line measurement and control;

Fig. 3 shows a layout of the measurement and control device.

FIG. 4 shows a flow chart of a telemetry method of the measurement and control device.

Detailed Description

In order that those skilled in the art will better understand the present invention, the present invention will be described in further detail with reference to the detailed description and the accompanying drawings.

The terms used in the present invention are those general terms that are currently widely used in the art in view of the functions of the present invention, but may vary according to the intention, precedent, or new technology in the art of the person of ordinary skill in the art. Furthermore, specific terms may be selected by the applicant, and in this case, detailed meanings thereof will be described in the detailed description of the present invention. Accordingly, the terms used in the specification should not be construed as simple names, but are based on meanings of the terms and general description of the present invention.

Referring to fig. 1, the present embodiment provides a telemetry circuit including a PT terminal box 100, a line measurement and control 200, and a rotary switch 300.

The PT terminal box 100 is connected to input ends of a Ua transformer 201, a Ub transformer 202 and a Uc transformer 203 in the line measurement and control 200 through a Ua line 101, a Ub line 102 and a Uc line 103, respectively. The output ends of the Ua transformer 201, the Ub transformer 202 and the Uc transformer 203 are all connected with the PT terminal box 100 through Un wires 104. The opening and closing of the Ua line 101, ub line 102, and Uc line 103 are controlled by the rotary switch 300.

The PT terminal box 100 is a terminal box of a voltage transformer, which is used to convert line voltage into a signal suitable for measurement by a measurement and control device, and connect the voltage transformer with the measurement and control device through the terminal box. The voltage transformer is installed on the high-voltage transmission line, and the primary side of the voltage transformer is directly connected to the high-voltage transmission line and used for sensing the voltage on the high-voltage transmission line. The secondary side of the voltage transformer converts the induced high voltage into a low voltage signal, and the low voltage signal is suitable for measurement by a measurement and control device. The output of the secondary side is connected to the PT terminal box 100 through a cable. The PT terminal box 100 is a concentrated connection point of the secondary side output of the voltage transformer. In the present invention, the PT terminal box 100 is connected to input ends of a Ua transformer 201, a Ub transformer 202, and a Uc transformer 203 in the measurement and control apparatus through a Ua line 101, a Ub line 102, and a Uc line 103, respectively.

The cable extends from the PT terminal box 100 to the measurement and control device, and transmits a voltage signal to an input terminal of the measurement and control device. In the measurement and control device, these voltage signals are respectively input to corresponding Ua transformers 201, ub transformers 202, and Uc transformers 203 via Ua lines 101, ub lines 102, and Uc lines 103. The Ua transformer 201, ub transformer 202, and Uc transformer 203 in the measurement and control device further process these signals and convert them into signals suitable for measurement by the measurement and control device. The processed signal can be received by the measurement and control device and used for measuring and displaying the voltage value. And after receiving the voltage signal, the measurement and control device performs amplification, filtering and analog-to-digital conversion, and converts the analog signal into a digital signal. The measurement and control device calculates the voltage value and displays the voltage value on the panel.

Through the above steps, the voltage signal is transmitted from the PT terminal box 100 to the measuring and controlling device, and is finally measured and processed by the measuring and controlling device. The voltage measurement of the power system is ensured to be safe and accurate.

By connecting the Ua line 101, the Ub line 102, and the Uc line 103 to the Un line 104 to form a loop, the influence of external electromagnetic interference can be reduced. Moreover, the Un line 104 is used as a common reference point, so that it can be ensured that the measurement of each phase voltage has a common reference point, thereby improving the accuracy and stability of the measurement, and if the Un line 101 is not connected with the Un line 104 to form a loop, the output end of the Ua transformer 201 is directly connected with the PT terminal box 100 to form a loop, the measurement loop may be unstable and easily disturbed.

In a three-phase system, the Un line 104 has a stable potential as a neutral point, close to zero. Reference to this neutral point for each phase voltage measurement ensures that the measurement signal has a uniform reference voltage. If there is no common reference point, the measurement of the voltages of each phase may be affected by other factors in the system, such as load changes, system faults, etc., resulting in unstable measured potentials. While the stability of the neutral point helps to reduce such fluctuations, providing a more reliable measurement.

Rotary switch 300 includes contact one 301, contact two 302, contact three 303, contact four 304, contact five 305, and contact six 306.

Wherein, contact one 301, contact two 302 connect to Ua line 101, contact three 303, contact four 304 connect to Ub line 102, contact five 305, contact six 306 connect to Uc line 103.

The first contact 301, the third contact 303 and the fifth contact 305 can be opened or closed so as to control the connection of the Ua line 101, the Ub line 102 and the Uc line 103, wherein the Ua line 101 is used for transmitting an a-phase voltage signal, the Ub line 102 is used for transmitting a B-phase voltage signal and the Uc line 103 is used for transmitting a C-phase voltage signal.

When the line voltage needs to be measured, the first contact 301 and the third contact 303 of the rotary switch 300 are closed. The a-phase voltage signal of the PT terminal box 100 is transmitted to the input end of the Ua transformer 201 through the first contact 301 and the second contact 302, the B-phase voltage signal of the PT terminal box 100 is transmitted to the input end of the Ub transformer 202 through the third contact 303 and the fourth contact 304, and the measurement and control device calculates the outlet voltage according to the received two-phase voltage signals.

The first contact 301 and the fifth contact 305 of the rotary switch 300 are closed. The a-phase voltage signal of the PT terminal box 100 is transmitted to the input end of the Ua transformer 201 through the first contact 301 and the second contact 302, the C-phase voltage signal of the PT terminal box 100 is transmitted to the input end of the Uc transformer 203 through the fifth contact 305 and the sixth contact 306, and the measurement and control device calculates the outlet voltage according to the received two-phase voltage signal.

The third contact 303 and the fifth contact 305 of the rotary switch 300 are closed. The B-phase voltage signal of the PT terminal box 100 is transmitted to the input end of the Ub transformer 202 through the contact three 303 and the contact four 304, the C-phase voltage signal of the PT terminal box 100 is transmitted to the input end of the Uc transformer 203 through the contact five 305 and the contact six 306, and the measurement and control device calculates the outlet voltage according to the received two-phase voltage signal.

When the phase voltage needs to be measured, the contact one 301 of the rotary switch 300 is closed, the A-phase voltage signal of the PT terminal box 100 is transmitted to the input end of the Ua transformer 201 through the contact one 301 and the contact two 302, the A-phase voltage signal of the PT terminal box 100 and the neutral point are transmitted to the measurement and control device through the Ua line 101 and the Un line 104, and the measurement and control device directly measures the voltage value of the phase voltage relative to the neutral point.

The contact three 303 of the rotary switch 300 is closed, the B-phase voltage signal of the PT terminal box 100 is transmitted to the input end of the Ub transformer 202 through the contact three 303 and the contact four 304, the B-phase voltage signal of the PT terminal box 100 and the neutral point are transmitted to a measurement and control device through the Ub line 102 and the Un line 104, and the measurement and control device directly measures the voltage value of the phase voltage relative to the neutral point.

The contact five 305 of the rotary switch 300 is closed, the C-phase voltage signal of the PT terminal box 100 is transmitted to the input end of the Uc transformer 203 through the contact five 305 and the contact six 306, the C-phase voltage signal of the PT terminal box 100 and the neutral point are transmitted to the measurement and control device through the Uc line 103 and the Un line 104, and the measurement and control device directly measures the voltage value of the phase voltage relative to the neutral point.

When the three-phase voltage needs to be measured simultaneously and the three-phase voltage needs to be measured simultaneously, all the contact one 301, the contact three 303 and the contact five 305 are closed.

The a-phase voltage signal of the PT terminal box 100 is transmitted to the input of the Ua transformer 201 through the contact one 301 and the contact two 302, and the B-phase voltage signal is transmitted to the input of the Ub transformer 202 through the contact three 303 and the contact four 304. And the measurement and control device calculates the outlet voltage Uab according to the received A-phase and B-phase voltage signals.

The B-phase voltage signal of the PT terminal box 100 is transmitted to the input of the Ub transformer 202 through the contact three 303 and the contact four 304, and the C-phase voltage signal is transmitted to the input of the Uc transformer 203 through the contact five 305 and the contact six 306. And the measurement and control device calculates the outlet voltage Ubc according to the received B-phase and C-phase voltage signals.

The C-phase voltage signal of the PT terminal box 100 is transmitted to the input terminal of the Uc transformer 203 through the contact five 305 and the contact six 306, and the a-phase voltage signal is transmitted to the input terminal of the Ua transformer 201 through the contact one 301 and the contact two 302. And the measurement and control device calculates the outlet voltage Uca according to the received C-phase and A-phase voltage signals.

The a-phase voltage signal of the PT terminal box 100 is transmitted to the input terminal of the Ua transformer 201 through the contact one 301 and the contact two 302, and the neutral point is connected to the output terminal of the Ua transformer 201 through the Un line 104. The measurement and control device calculates the phase voltage Ua according to the received A-phase voltage signal and the neutral point voltage.

The B-phase voltage signal of the PT terminal box 100 is transmitted to the input of the Ub transformer 202 through the contact three 303 and the contact four 304, while the neutral point is connected to the output of the Ub transformer 202 through the Un line 104. And the measurement and control device calculates the phase voltage Ub according to the received B-phase voltage signal and the neutral point voltage.

The C-phase voltage signal of the PT terminal box 100 is transmitted to the input terminal of the Uc transformer 203 through the contact five 305 and the contact six 306, and the neutral point is connected to the output terminal of the Uc transformer 203 through the Un line 104. And the measurement and control device calculates the phase voltage Uc according to the received C-phase voltage signal and the neutral point voltage.

When the first contact 301, the third contact 303 and the fifth contact 305 are all closed, the measurement and control device can measure the line voltage and the phase voltage of three phases at the same time, so that the voltage state of the power system is comprehensively monitored.

By setting the rotary switch 300, the measurement and control device can flexibly adapt to different measurement requirements, and powerful support is provided for stable operation and fault analysis of the power system.

The circuit measurement and control 200 is internally provided with a Uo transformer 204, the input end of the Uo transformer 204 is connected with the PT terminal box 100 through a Uo line 105, the output end of the Uo transformer 204 is connected with a Uon line 106, and the Uon line 106 is connected with a Un line 104.

The input of the Uo transformer 204 is connected to the output of the open delta winding of the PT terminal box 100 through the Uo line 105 for receiving the zero sequence voltage signal. The output end is connected with the Un line 104 through the Uon line 106 to form a complete measuring loop, so that the signal can be accurately measured by the measuring and controlling device.

The Uo transformer 204 is connected to the output of the open delta winding of the PT terminal box 100. The open delta winding functions to provide a zero sequence voltage signal. When the three-phase voltages are balanced, the output voltage of the open delta winding is close to zero, and when the ground fault occurs, the output voltage of the open delta winding can rise, and the voltage is zero sequence voltage.

Uon line 106 is connected to Un line 104, ensuring consistency of the measurement references. The Uo line 105 is used as a neutral line and provides a stable reference potential, so that the measurement and control device can measure zero sequence voltage based on a uniform reference point, and the accuracy and stability of measurement are improved.

The Uo transformer 204 is used to detect zero sequence voltages, which rise when the system fails to ground. By means of the connection mode, the measurement and control device can monitor the change of zero sequence voltage in real time, timely detect the ground fault and take corresponding protection measures.

Referring to fig. 2, a telemetry circuit further includes a CT terminal box 400.

The CT terminal box 400 is connected to input ends of the Ia transformer 205, the Ib transformer 206, and the Ic transformer 207 in the line measurement and control 200 through Ia lines 401, ib lines 402, and Ic lines 403, respectively, output ends of the Ia transformer 205, the Ib transformer 206, and the Ic transformer 207 are connected to an Ian line 404, an Ibn line 405, and an Icn line 406, respectively, the Ian line 404 is connected to the Ibn line 405, the Ibn line 405 is connected to the Icn line 406, and the Ian line 404, the Ibn line 405, or the Icn line 406 is connected to the CT terminal box 400.

Next, an explanation is given as to how the line measurement and control 200 monitors the current in the circuit.

The current transformer is arranged in a main circuit with larger current, and the primary side of the current transformer is connected in series in a tested circuit. When current flows in the main circuit, the primary side of the current transformer generates a current proportional thereto. The secondary side of the current transformer converts the large current of the primary side into small current which is suitable for measurement by the measurement and control device. The output of the secondary side is connected to the CT terminal box 400 by a cable. The CT terminal box 400 is a centralized connection point of the secondary side output of the current transformer, and is connected to the input ends of the Ia transformer 205, the Ib transformer 206 and the Ic transformer 207 in the line measurement and control 200 through the Ia line 401, the Ib line 402 and the Ic line 403 respectively.

The cable extends from the CT terminal box 400 to the measurement and control device, transmitting the current signal to the input terminal of the measurement and control device. In the measurement and control device, these current signals are input to the corresponding Ia transformers 205, ib transformers 206, ic transformers 207 via Ia lines 401, ib lines 402, ic lines 403, respectively. The Ia transformer 205, ib transformer 206, ic transformer 207 in the line measurement and control 200 further processes these current signals, converting them into signals suitable for measurement by the measurement and control device. The processed signal can be received by a measurement and control device and used for measuring and displaying the current value. The measurement and control device amplifies and filters the acquired current signals to improve the quality and accuracy of the signals. The processed analog current signal is converted to a digital signal for subsequent digital signal processing and computation. And calculating various electrical parameters such as effective value of current, power and the like according to the converted digital signals.

An Io transformer 208 is arranged in the line measurement and control 200, the input end of the Io transformer 208 is connected with the CT terminal box 400 through an Io line 407, and the output end of the Io transformer 208 is connected with the CT terminal box 400 through an Ion line 408.

And the non-homonymous ends of the secondary sides of the three current transformers in the CT terminal box 400 are connected together to form an output end of the open delta winding. The input of the Io transformer 208 is then connected to this output. The output end of the Io transformer 208 is connected back to the connection point of the secondary side homonymous ends of the three current transformers in the CT terminal box 400, namely, the neutral point, through the connection mode, the zero sequence current signal can form a complete loop, so that the Io transformer 208 can accurately detect the zero sequence current, and the zero sequence current can be transmitted to a measurement and control device for further processing and analysis.

In a three-phase system, the zero sequence current is the vector sum of the three-phase currents. In normal operation, the vector sum of the three phase currents is zero, so the zero sequence current should also be zero. When a ground fault occurs, zero sequence current will rise significantly. The Io transformer 208 is used to detect this zero sequence current, which rises when the system fails to ground. Through the connection of the open delta winding and the Io transformer 208, the measurement and control device can monitor the change of zero sequence current in real time and timely detect the ground fault.

Referring to fig. 3, a measurement and control device includes a cabinet 200A, wherein the front layout of the cabinet 200A is shown as a face a in fig. 3, and the back layout of the cabinet 200A is shown as a face b in fig. 3.

The circuit measurement and control 200 is arranged in the cabinet body 200A, and the circuit measurement and control 200 comprises a Ua transformer 201, a Ub transformer 202, a Uc transformer 203, a Uo transformer 204, an Ia transformer 205, an Ib transformer 206, an Ic transformer 207 and an Io transformer 208, and the circuit measurement and control 200 is respectively connected with the PT terminal box 100 and the CT terminal box 400.

The circuit measurement and control 200 can be provided in plurality, each circuit measurement and control 200 is internally provided with a plurality of current transformers and voltage transformers, and the voltage and the current of the circuit are monitored through the connection ports of the circuit measurement and control 200, namely the input ports and the output ports of the voltage transformers and the current transformers in the circuit measurement and control 200, and the connection ports are connected with the circuit to be monitored.

Referring to fig. 4, a telemetry method of a measurement and control device includes the steps of:

s1, line measurement and control 200 receives each phase voltage signal and zero sequence voltage signal transmitted by PT terminal box 100, and each phase current signal and zero sequence current signal transmitted by CT terminal box 400.

And S2, calculating the effective values of line voltage, phase voltage and current, and power, power factor and frequency according to the collected voltage and current signals.

The steps S1-S3 comprise signal acquisition, signal processing, signal conversion, parameter calculation, system monitoring and protection actions.

Signal acquisition, namely line measurement and control 200 receives voltage signals of each phase from the PT terminal box 100 through Ua line 101, ub line 102 and Uc line 103 and receives zero sequence voltage signals through Uo line 105. Line measurement and control 200 receives the current signals of each phase from CT terminal box 400 via Ia line 401, ib line 402, ic line 403, and receives the zero sequence current signal via Io line 407.

The Ua transformers 201, 202, 203 and 204 in the measurement and control device receive voltage signals of each phase from the PT terminal box 100 through the Ua line 101, the Ub line 102, the Uc line 103 and the Uo line 105 respectively, the Ua line 101 and the Un line 104 form a loop, the Ua transformer 201 receives an a-phase voltage signal, the Ub line 102 and the Un line 104 form a loop, the Ub transformer 202 receives a B-phase voltage signal, the Uc line 103 and the Un line 104 form a loop, the Uc transformer 203 receives a C-phase voltage signal, the Uo line 105 and the Uon line 106 form a loop, and the Uo transformer 204 receives a zero sequence voltage signal.

The Ia transformer 205, the Ib transformer 206, the Ic transformer 207 and the Io transformer 208 in the measurement and control device receive current signals of each phase from the CT terminal box 400 through an Ia line 401, an Ib line 402, an Ic line 403 and an Io line 407 respectively, so that the Ia transformer 205 receives a current signal of each phase, the Ib line 402 and the Ibn line 405 form a loop, the Ib transformer 206 receives a current signal of each phase, the Ic line 403 and the Icn line 406 form a loop, the Ic transformer 207 receives a current signal of each phase, the Io line 407 and the Ion line 408 form a loop, and the Io transformer 208 receives a zero sequence current signal.

And the signal processing, namely the line measurement and control 200 performs preliminary processing on the collected voltage signals and zero sequence voltage signals of each phase, and performs preliminary processing on the collected current signals and zero sequence current signals of each phase, including signal amplification and filtering, so as to improve the quality and the accuracy of the signals.

The line measurement and control 200 converts the processed voltage signals, zero sequence voltage signals, current signals and zero sequence current signals of each phase into digital signals, and converts continuous analog signals into discrete digital signals through a built-in analog-to-digital conversion module so as to facilitate subsequent digital signal processing and calculation.

And calculating effective values of line voltage, phase voltage and current, and power, power factor and frequency according to the converted digital signals.

The line voltage can be obtained by calculating the difference value of the two phase voltages. The effective value of the current can be obtained by performing a root mean square calculation on the current signal. The power may be calculated from the product integral of the voltage and current signals. The power factor can be obtained by calculating the phase difference of the voltage and the current. The frequency may be calculated by periodic measurements of the voltage or current signal.

The system monitoring is that the line measurement and control 200 monitors the operation state of the power system in real time through the PT terminal box 100 and the CT terminal box 400, and judges that overload or short circuit fault may occur to the system when the monitored voltage or current exceeds a preset threshold value. When the zero sequence voltage or zero sequence current is monitored to exceed a preset threshold value, the system is judged to be likely to have the ground fault.

And the protection action is that when the system fault is detected, the measurement and control device sends out an alarm signal and adopts corresponding protection measures according to preset protection logic.

Finally, it should be pointed out that the above detailed method and apparatus are only examples, which can be modified in different ways by a person skilled in the art without departing from the scope of the invention.

Claims

1. A telemetry circuit is characterized by comprising,

The PT terminal box (100), the PT terminal box (100) is connected with input ends of a Ua transformer (201), a Ub transformer (202) and a Uc transformer (203) in the line measurement and control (200) through a Ua line (101), a Ub line (102) and a Uc line (103) respectively;

the output ends of the Ua transformer (201), the Ub transformer (202) and the Uc transformer (203) are connected with the PT terminal box (100) through Un wires (104);

The opening and closing of the Ua line (101), the Ub line (102) and the Uc line (103) are controlled by a rotary switch (300).

2. The telemetry circuit of claim 1 wherein said rotary switch (300) comprises contact one (301), contact two (302), contact three (303), contact four (304), contact five (305), and contact six (306);

The first contact (301) and the second contact (302) are connected to the Ua line (101), the third contact (303) and the fourth contact (304) are connected to the Ub line (102), and the fifth contact (305) and the sixth contact (306) are connected to the Uc line (103).

3. The telemetry circuit of claim 2, wherein a Uo transformer (204) is arranged in the circuit measurement and control (200), an input end of the Uo transformer (204) is connected with the PT terminal box (100) through a Uo wire (105), an output end of the Uo transformer (204) is connected with a Uon wire (106), and the Uon wire (106) is connected with the Un wire (104).

4. The telemetry circuit of claim 3, further comprising a CT terminal box (400), wherein the CT terminal box (400) is connected with input ends of an Ia transformer (205), an Ib transformer (206) and an Ic transformer (207) in the line measurement and control (200) through an Ia line (401), an Ib line (402) and an Ic line (403) respectively, output ends of the Ia transformer (205), the Ib transformer (206) and the Ic transformer (207) are connected with an Ian line (404), an Ibn line (405) and an Icn line (406) respectively, the Ian line (404) is connected with the Ibn line (405), the Ibn line (405) is connected with the Icn line (406), and the Ian line (404), the Ibn line (405) or the Icn line (406) is connected with the CT terminal box (400).

5. The telemetry circuit of claim 4, wherein an Io transformer (208) is disposed in the line measurement and control (200), an input end of the Io transformer (208) is connected with the CT terminal box (400) through an Io line (407), and an output end of the Io transformer (208) is connected with the CT terminal box (400) through an Ion line (408).

6. A measurement and control device is characterized by being applied to a telemetry loop according to any one of claims 1-5, the measurement and control device comprises a cabinet body (200A), the line measurement and control device (200) is arranged in the cabinet body (200A), the line measurement and control device (200) comprises a Ua transformer (201), a Ub transformer (202), a Uc transformer (203), a Uo transformer (204), an Ia transformer (205), an Ib transformer (206), an Ic transformer (207) and an Io transformer (208), and the line measurement and control device (200) is respectively connected with a PT terminal box (100) and a CT terminal box (400).

7. A telemetry method of a measurement and control device is used for the measurement and control device of claim 6, and is characterized by comprising the following steps:

s1, line measurement and control (200) receives each phase voltage signal and zero sequence voltage signal transmitted by a PT terminal box (100), and each phase current signal and zero sequence current signal transmitted by a CT terminal box (400);

8. The method according to claim 7, wherein in step S1, the line measurement and control (200) receives the respective phase voltage signals from the PT terminal box (100) through the Ua line (101), the Ub line (102) and the Uc line (103), receives the zero sequence voltage signals through the Uo line (105), and the line measurement and control (200) receives the respective phase current signals from the CT terminal box (400) through the Ia line (401), the Ib line (402) and the Ic line (403), and receives the zero sequence current signals through the Io line (407).

9. The telemetry method of the measurement and control device of claim 8, wherein in step S2, the line measurement and control (200) performs preliminary processing on the collected voltage signals and zero sequence voltage signals of each phase, and performs preliminary processing on the collected current signals and zero sequence current signals of each phase;

the line measurement and control (200) converts the processed voltage signals, zero sequence voltage signals, current signals and zero sequence current signals of each phase into digital signals;

10. The telemetry method of measurement and control device according to claim 9, wherein in step S3, the line measurement and control (200) monitors the operation state of the power system in real time through the PT terminal box (100) and the CT terminal box (400), and when the monitored voltage or current exceeds a preset threshold value, it is judged that overload or short circuit fault is likely to occur in the system, and when the monitored zero sequence voltage or zero sequence current exceeds the preset threshold value, it is judged that ground fault is likely to occur in the system;