CN103336190B - Bis-mistake detection methods arranged side by side of PT - Google Patents

Abstract

The present invention relates to a kind of Relay Protection Technology in Power System field, particularly relate to a kind of bis-mistakes of PT and detect device side by side, belong to Relay Protection Technology in Power System field.It is about Secondary Circuit of Potential Transformer problem, mainly solves power system voltage transformer secondary circuit problem arranged side by side by mistake.Bis-mistakes of PT detect device side by side, are to be connected with detected analog quantity by analog-to-digital conversion, and the output of analog-to-digital conversion is connected with the input of CPU microprocessor, and the output of CPU microprocessor is connected with Automatic monitoring systems and display and loudspeaker respectively.The present invention has been effectively ensured power train and has unified the safe and stable operation of secondary device, can become a device adapting to intelligent grid requirement, plays a role for ensureing that power system safety and stability runs.

Description

PT Secondary False Parallel Detection Method

technical field

The invention relates to the technical field of electric power system relay protection, in particular to a PT secondary misparallel detection device, which belongs to the technical field of electric power system relay protection. It is about the problem of the secondary circuit of the voltage transformer, mainly to solve the problem of wrong paralleling of the secondary circuit of the voltage transformer in the power system.

Background technique

At present, a basic common sense of relay protection in power systems is: if the bus tie switch between the first bus and the second bus of two busbars in a substation is in the disconnected state, then the No. 1 voltage transformer connected to the first bus It is not allowed to parallel with the secondary output terminal of the No. 2 voltage transformer connected to the No. 2 busbar. Only when the bus tie switch between the two bus sections is in the closing position, it is allowed to parallel two voltage transformers of the same type on the secondary side. Although it is allowed to be paralleled, it is not necessary to be paralleled. Only when one of the voltage transformers in the two busbars has a problem is out of operation or when it is overhauled, it is carried out under the principle of paralleling the primary side first and then paralleling the secondary side. 1. Parallel operation on the secondary side.

If the principle of paralleling first and then paralleling the second time is violated, when the primary side is separated, the secondary side is wrongly paralleled, and when a grounding or phase-to-phase fault occurs in the system where a certain section of the busbar is located, the secondary The measured voltage cannot truly reflect the situation of the primary voltage, and at least the protection will refuse to operate and the voltage transformer will be damaged. If it is serious, the voltage transformer will be damaged, and the insulation of the voltage transformer will be damaged, resulting in a bus failure, resulting in a large-scale power outage.

Analysis from the technical level: There are many reasons for the wrong paralleling: 1. The failure of the secondary automatic paralleling device of the voltage transformer and the cause of the wrong use; 2. The reason why the two-stage bus voltage automatic switching circuit with automatic control of the isolating switch is not working properly ; 3. Reasons for misoperation by operation and maintenance personnel, etc.

Shenyang Power Supply Company and all power supply departments across the country have experienced accidents and abnormalities caused by secondary mis-paralleling of voltage transformers. It is imminent to develop a device that can automatically report mis-parallel information, and it is also compatible with the development of smart grids.

Contents of the invention

In order to solve the above-mentioned existing technical problems, the present invention provides a PT secondary misparallel detection device, the purpose of which is to automatically send out the acousto-optic signal of the secondary misparallel of voltage transformers according to the detection results when the two busbars of the power system are split and running. Prompt the operation and scheduling personnel to deal with it in time.

The PT secondary misparallel detection device is connected by the analog-to-digital conversion and the detected analog quantity, the output of the analog-to-digital conversion is connected to the input of the CPU microprocessor, and the output of the CPU microprocessor is respectively connected to the automatic monitoring system and the display. Connect to the speaker.

The detected analog quantity is the secondary coil of the voltage transformer.

Described microprocessor is ARM-LPC4357 chip.

The analog-to-digital conversion has two groups of four-phase voltage detection and comparison; the detected analog quantity is the A, B, C, and L terminals of the secondary coils of two groups of voltage transformers; wherein the analog-to-digital converter is connected to two On the A, B, C, L terminals of the secondary coil of the group voltage transformer.

The detection method of the PT secondary misparallel detection device is: an analog-to-digital converter with two sets of four-phase voltage detection and comparison is connected to the A, B, C, and L terminals of the two sets of voltage transformer secondary coils to collect two sets of voltages Then the sampling information is output to the CPU microprocessor in the form of digital quantities. The CPU microprocessor analyzes and processes the two sets of data, and then drives the display and speakers to send out sound and light signals. The conclusions are sent to the automated monitoring system.

A specific frequency voltage source U0 is added to one of the phases of one of the two sets of secondary coils of the two sets of voltage transformers; and then a "U0 measurement" device with single-phase voltage detection is used to measure the other set of voltage mutual inductance Sampling and analysis of the phase voltage of the same name of the device, if the voltage of this frequency and magnitude is collected, it is considered that the two voltages have been mis-paralleled, and the sound and light signals are output.

The voltage source U0 is a non-power frequency signal source.

The specific frequency voltage source U0 distributes the voltage to the resistor R through the resistors R1 and R2, and determines whether the secondary coils of the two sets of voltage transformers are mistakenly paralleled by detecting the voltage drop on the middle R resistor; the specific frequency voltage The frequency of the source U0 is a non-power frequency voltage, and U0 is a DC voltage.

The secondary coil of the voltage transformer is judged by the sudden change of the phase voltage difference of the same name.

Advantage of the present invention and beneficial effect are:

The present invention is to detect the secondary coils of the voltage transformers that should not be paralleled when the two sections of the busbars of the power system are split, and automatically send out the sound and light signal that the secondary coils of the voltage transformers are incorrectly paralleled according to the detection results, and transmit the information to the automation The scheduling system prompts the operation and scheduling personnel to deal with it in a timely manner. Effectively guarantee the safe and stable operation of primary and secondary equipment in the power system. The device of the invention can be a device that meets the requirements of the smart grid, and can play a certain role in ensuring the safe and stable operation of the power system.

The present invention will be further described in detail below in conjunction with the accompanying drawings and specific embodiments, but the protection scope of the present invention is not limited by the embodiments.

Description of drawings

Fig. 1 is a schematic circuit diagram of the present invention;

Fig. 2 is a structural representation of the present invention;

Fig. 3 is a schematic diagram of another embodiment of the present invention.

In the figure: the detected analog quantity 1, the analog-to-digital converter 2, the display 3, the speaker 4, the CPU microprocessor 5, the automatic monitoring system 6, the U0 voltage adding part 7, and the U0 voltage measuring part 8.

detailed description

Example 1:

As shown in Figure 1 and Figure 2, the present invention provides a PT secondary error parallel detection device, the specific structure is as follows:

The analog-to-digital converter 2 with two sets of four-phase voltage detection and comparison is connected to the A, B, C, and L terminals of the secondary coils of the two sets of voltage transformers to collect the magnitude and phase of the two sets of voltages, and then in the form of digital quantities Output the sampling information to the CPU microprocessor 5, and the CPU microprocessor 5 analyzes and processes the two sets of data, then drives the display 3 and the speaker 4 to send out sound and light signals, and at the same time transmits the conclusion of whether there is a wrong parallel to the automatic monitoring system 6 .

The device is suitable for two sets of voltage transformers that are not paralleled at one time, and the primary voltage has a large deviation, or the two sets of voltage transformers have a large characteristic difference, resulting in a large difference in the voltage on the secondary terminals of the two sets of voltage transformers. Condition.

During specific implementation, the analog-to-digital conversion 2 described in the present invention is connected with the detected analog quantity 1, the output end of the analog-to-digital conversion 2 is connected with the input end of the CPU microprocessor 5, and the output ends of the CPU microprocessor 5 are respectively Connect with automation system 6 and display 3 and loudspeaker 4. The detected analog quantity 1 is a secondary coil of a voltage transformer. Described microprocessor 5 is ARM-LPC4357 chip.

Example 2:

Yet another embodiment of the present invention utilizes the applied voltage method. As shown in Figure 3, specifically, a voltage source U0 of a specific frequency is added to one of the phases of one of the secondary coils of the two sets of voltage transformers, and then a "U0 measurement" device with single-phase voltage detection is used Sampling and analyzing the phase voltage of the same name of another group of voltage transformers, if the voltage of this frequency and magnitude is collected, it is considered that the two voltages have been wrongly juxtaposed, and the sound and light signals are output.

The external specific frequency excitation voltage should be very small, so as not to affect the protection, metering, and work of related devices.

Example 3:

The following circuit is used: the specific frequency signal source U0 distributes the voltage to the resistor R through the resistors R1 and R2, and by detecting the voltage drop on the middle R resistor, it is determined whether the secondary coils of the two sets of voltage transformers are incorrectly paralleled.

When the two groups of voltages are wrongly paralleled for the second time, the voltage of the specific voltage U0 frequency at both ends of R is zero, and U0 can be a DC voltage.

Example 4:

Through the feature that the variation of the voltage difference of the phases with the same name before and after paralleling is a sudden change, the software program is used to judge whether the secondary wrong paralleling of voltage transformers has occurred.

During specific implementation, one or more OR gate or AND gate logics that constitute the result of the above four example methods can be used to draw a conclusion on whether the secondary voltages are incorrectly paralleled.

Which logical combination to use can be completely determined according to the specific operating conditions of the voltage transformer on site and the long-term secondary numerical statistical data of the secondary voltage.

Claims (1)

1. The PT secondary error parallel detection method is characterized in that: the detection device used in this method has the following structure, the analog-to-digital converter (2) is connected to the detected analog quantity (1), and the output terminal of the analog-to-digital converter (2) It is connected with the input end of the CPU microprocessor (5), and the output end of the CPU microprocessor (5) is respectively connected with the automatic monitoring system (6) and the display (3) and the loudspeaker (4); the microprocessor (5) is an ARM-LPC4357 chip; the analog-to-digital converter (2) has two sets of four-phase voltage input terminals; the detected analog quantity (1) is A of the secondary coil of two sets of voltage transformers , B, C, L terminal output voltage; where the analog-to-digital converter (2) is connected to the A, B, C, L terminals of the two sets of voltage transformer secondary coils; The method of PT secondary misparallel detection is: the analog-to-digital converter (2) with two sets of four-phase voltage input terminals is connected to the A, B, C, and L terminals of the two sets of voltage transformer secondary coils to collect two sets of voltages The size and phase of the sample, and then output the sampling information to the CPU microprocessor (5) in the form of digital quantities, and the CPU microprocessor (5) analyzes and processes the two sets of data, and then drives the display (3) and speaker (4) Send out sound and light signals, and at the same time transmit the conclusion of whether there is a wrong parallel to the automatic monitoring system (6); A specific frequency voltage source U0 is added to one of the phases of one of the two sets of secondary coils of the two sets of voltage transformers; and then a "U0 measurement" device with single-phase voltage detection is used to measure the other set of voltage mutual inductance Sampling and analysis of the phase voltage of the same name of the device, if the voltage of this frequency and magnitude is collected, it is considered that the two voltages have been mis-paralleled, and output sound and light signals; or the voltage source U0 is a non-power frequency The frequency signal source, the voltage source U0 distributes the voltage to the resistor R through the series resistors R1 and R2, and determines whether the secondary coils of the two sets of voltage transformers are incorrectly paralleled by detecting the voltage drop on the middle R resistor; In the secondary coil of the voltage transformer, it is judged whether there is a wrong paralleling according to the sudden change of the phase voltage difference of the same name.