CN111366876A

CN111366876A - Generator outlet PT disconnection early warning device and early warning method

Info

Publication number: CN111366876A
Application number: CN201911108608.5A
Authority: CN
Inventors: 马中荣; 成玉峰
Original assignee: Jiuquan Iron and Steel Group Co Ltd
Current assignee: Jiuquan Iron and Steel Group Co Ltd
Priority date: 2019-11-13
Filing date: 2019-11-13
Publication date: 2020-07-03

Abstract

The invention discloses a generator outlet PT disconnection early warning device and an early warning method, belongs to the technical field of protection and monitoring of power facilities of a thermal power plant, and solves the problem that early warning cannot be performed on initial faults of a voltage loop. The device comprises a voltage transmitter and an analog input module, wherein the voltage transmitter is provided with 3 voltage transmitters which are respectively connected to three secondary small buses of a voltage transformer, the analog input module comprises a voltage sampling module, a pressure difference module, an absolute value module, a comparison module, a one-out-of-three module, a delay module and an alarm module which are sequentially connected, and the voltage sampling module is connected with the voltage transmitter. The method comprises the following steps: and taking a voltage value, calculating a pressure difference, taking an absolute value, comparing, judging in a delayed manner, and giving an alarm. The device carries out logic calculation through the analog input module to obtain early warning information and send out an alarm signal, and when the voltage loop has initial failure, the early warning is sent out to remind operators on duty and maintainers to check the primary loop and the secondary loop of the PT, so that the accident expansion is prevented.

Description

Generator outlet PT disconnection early warning device and early warning method

Technical Field

The invention belongs to the technical field of protection and monitoring of electric power facilities of a thermal power plant, and particularly relates to a generator outlet PT disconnection early warning device and an early warning method.

Background

A generator outlet voltage transformer (PT) changes the primary voltage of 20KV at the outlet of the generator into secondary voltage of 100V, and supplies the secondary voltage to devices such as a generator-transformer group protection device, an excitation regulator, an electric energy meter and a power transmitter. When a voltage transformer is fused through primary fuse, faults such as poor contact of a primary loop and a secondary loop can cause inaccurate voltage acquisition, and results such as protection misoperation or failure, inaccurate electric energy metering and the like are caused. At present, a generator outlet voltage loop is mainly monitored by a PT (potential transformer) disconnection alarming function of a generator-transformer set protection device, the PT disconnection constant value is 8V, and the initial fault of the voltage loop cannot be effectively monitored.

Disclosure of Invention

The invention aims to provide a PT (potential transformer) disconnection early warning device at an outlet of a generator, which aims to solve the problem that early warning cannot be carried out on initial faults of a voltage loop.

The invention also aims to provide a PT wire breakage early warning method for the outlet of the generator.

The technical scheme of the invention is as follows: the utility model provides a generator export PT early warning device that breaks wire, includes voltage transmitter and analog input module, and voltage transmitter is equipped with 3 and connects respectively on voltage transformer's 3 little buses of secondary, and analog input module is including the voltage sampling module, pressure difference module, absolute value module, comparison module, three modules of getting, delay module and the alarm module that connect gradually, and voltage sampling module links to each other with voltage transmitter.

As a further improvement of the invention, the device also comprises a display module, and the voltage sampling module, the voltage difference module and the alarm module are all connected with the display module.

A generator outlet PT disconnection early warning method specifically comprises the following steps:

s1, each voltage transmitter sends voltage data on the secondary small bus to a voltage sampling module, and the voltage sampling module sends the received data to a differential pressure module;

s2, the pressure difference module calculates the difference value of every two of the three voltage data and sends the calculation result to the absolute value module, and the absolute value module takes the absolute value of the received pressure difference data and sends the result to the comparison module;

s3, the comparison module compares the received data with a preset differential pressure early warning value, and outputs an early warning signal to the one-out-of-three module when the absolute value of the differential pressure exceeds the preset differential pressure early warning value;

and S4, when the one-out-of-three module receives any one pressure difference early warning signal, outputting a signal to the delay module, and when the preset delay time is reached, outputting a signal to the alarm module by the delay module, and giving an alarm by the alarm module.

As a further improvement of the invention, the display module receives data information from the voltage sampling module, the voltage difference module and the alarm module and displays the voltage data, the voltage difference data and the alarm signal on the display.

The invention has the beneficial effects that:

the existing generator outlet PT disconnection monitoring function is generally realized by a generator microcomputer protection device, when PT disconnection faults occur, an alarm is given out and corresponding protection is locked, in order to prevent protection misoperation or refusal, a pressure difference alarm value is often set to be large, the method can only monitor faults such as complete fuse of a fuse, disconnection and the like, early warning cannot be carried out on initial faults such as slow fuse of the fuse, loosening of the connection and the like, and an operator on duty generally inspects the protection device once within 2 hours, cannot monitor voltage sampling in real time and confirms the operation condition of equipment. The device directly displays the voltage of the generator and the difference value thereof on the display, an operator can check the voltage and the difference value at any time, a series of logic calculations are carried out through the analog input module to obtain early warning information and send out an alarm signal, and early warning is sent out when the initial fault occurs in the voltage loop, so that operators on duty and maintainers are reminded to check the primary and secondary PT loops, and the accident expansion is prevented.

The method has simple operation and reasonable control, the pressure difference early warning value can be modified at any time, and the pressure difference early warning value is set to be slightly larger than the maximum value by acquiring the maximum value of the pressure difference during the normal operation of the equipment within a period of time, so that the sensitivity of alarming can be ensured, the false alarming can be prevented, and the method has extremely high reliability.

Drawings

FIG. 1 is a schematic structural diagram of a generator outlet PT wire breakage early warning device according to the present invention;

FIG. 2 is a schematic structural diagram of an analog input module in the generator outlet PT disconnection warning device according to the present invention;

fig. 3 is a display effect diagram in the method for early warning the PT disconnection at the generator outlet according to the present invention.

In the figure, 1-voltage transformer; 2-a generator; 3-generator outlet bus; 4-secondary small bus; 5-a voltage transmitter; 6-analog input module; 7-a voltage sampling module; 8-a differential pressure module; 9-absolute value module; 10-a comparison module; 11-one module from three; 12-a delay module; 13-an alarm module; 14-display module.

Detailed Description

The present invention will be described in detail below with reference to the accompanying drawings.

As shown in fig. 1 and 2, the generator outlet PT disconnection early warning device includes a voltage transmitter 5 and an analog input module 6, the voltage transmitter 5 is provided with 3 voltage transmitters and respectively connected to 3 secondary busbars 4 of a voltage transformer 1, the analog input module 6 includes a voltage sampling module 7, a differential pressure module 8, an absolute value module 9, a comparison module 10, a third-out-of-one module 11, a delay module 12 and an alarm module 13, which are sequentially connected, and the voltage sampling module 7 is connected with the voltage transmitter 5.

The voltage sampling module 7, the voltage difference module 8 and the alarm module 13 are all connected with the display module 14.

The analog input module 6 adopts DCS.

The voltage transformer 1 is connected to a generator outlet bus 3 of the generator 2.

A generator outlet PT disconnection early warning method comprises the following steps:

s1, the voltage transmitters 5 respectively define the voltage data on the secondary small bus 4 as Uab, Ubc and Uca and send the voltage data to the voltage sampling module 7, and the voltage sampling module 7 sends the received data to the differential pressure module 8;

s2, the pressure difference module 8 calculates two differences among the three voltage data, namely delta U (ab-bc), delta U (bc-ca) and delta U (ca-ab), and sends the calculation results to the absolute value module 9, and the absolute value module 9 takes the absolute value of the received pressure difference data and sends the results to the comparison module 10;

s3, the comparison module 10 compares the received data with a preset differential pressure early warning value, and outputs an early warning signal to the one-out-of-three module 11 when the absolute value of the differential pressure exceeds the preset differential pressure early warning value;

s4, when the one-out-of-three module 11 receives any one pressure difference early warning signal, outputting a signal to the delay module 12, when the preset delay time is reached, outputting a signal to the alarm module 13 by the delay module 12, and sending an alarm by the alarm module 13; if the preset delay time is not reached, no alarm is given.

The display module 14 receives data information from the voltage sampling module 7, the voltage difference module 8 and the alarm module 13, and displays the voltage data, the voltage difference data and the alarm signal on a display, as shown in fig. 3. When the alarm condition is not reached, the display is grey, and when the alarm signal trigger is reached, the display is red.

Claims

1. The utility model provides a generator export PT early warning device that breaks a line which characterized in that: including voltage transmitter (5) and analog input module (6), voltage transmitter (5) are equipped with 3 and connect respectively on 3 root secondary minibus (4) of voltage transformer (1), analog input module (6) are including voltage sampling module (7), pressure difference module (8), absolute value module (9), comparison module (10), three that connect gradually get one module (11), time delay module (12) and alarm module (13), voltage sampling module (7) link to each other with voltage transmitter (5).

2. The generator outlet PT wire breakage early warning device of claim 1, wherein: the voltage sampling module (7), the voltage difference module (8) and the alarm module (13) are all connected with the display module (14).

3. A generator outlet PT disconnection early warning method is characterized by comprising the following steps: the generator outlet PT wire breakage early warning device of claim 1 is used, and specifically comprises the following steps:

s1, each voltage transmitter (5) sends voltage data on the secondary small bus (4) to a voltage sampling module (7), and the voltage sampling module (7) sends the received data to a differential pressure module (8);

s2, the pressure difference module (8) calculates pairwise difference values in the three voltage data and sends the calculation results to the absolute value module (9), and the absolute value module (9) takes absolute values of the received pressure difference data and sends the results to the comparison module (10);

s3, the comparison module (10) compares the received data with a preset differential pressure early warning value, and outputs an early warning signal to the one-out-of-three module (11) when the absolute value of the differential pressure exceeds the preset differential pressure early warning value;

s4, when the one-out-of-three module (11) receives any one pressure difference early warning signal, a signal is output to the delay module (12), when the preset delay time is reached, the delay module (12) outputs the signal to the alarm module (13), and the alarm module (13) gives an alarm.

4. The early warning method for PT wire breakage at the outlet of the generator as claimed in claim 3, wherein: the display module (14) receives data information from the voltage sampling module (7), the voltage difference module (8) and the alarm module (13), and displays the voltage data, the voltage difference data and the alarm signal on a display.