CN105871193A - A method of controlling transformer bidirectional soft start based on PLC - Google Patents

Abstract

A method for controlling bidirectional soft start of a transformer based on a PLC. The invention can realize the technical purposes of bidirectional starting, automatic switching, voltage conversion and excitation surge current reduction of the transformer because of the design and the use of the input and output series resistance starting circuit of the transformer and the special software program of the PLC. Has practical use effect and market potential.

Description

A method of controlling transformer bidirectional soft start based on PLC

technical field

A method for controlling bidirectional soft start of a transformer based on PLC.

Background technique

At the moment of transformer startup, an excitation inrush current that is several times or even ten times higher than the rated current of the transformer will be generated. This exciting current will instantly have a harmful impact on the power grid, causing damage to the power grid equipment, causing the adjacent circuit breaker to malfunction, etc., causing unnecessary accidental damage.

In order to solve the above technical problems, there used to be technical measures of resistance switching device and radio wave detection device. Although it can solve the problem of the above damage caused by the instantaneous super large excitation inrush current to a certain extent, it cannot start in both directions, and cannot automatically switch and switch. Voltage and other problems and shortcomings.

Contents of the invention

The purpose of the present invention is to realize the technical effects of transformer bidirectional starting, automatic switching, switching voltage and reducing excitation inrush current through the design of the PLC-connected transformer input and output series resistance starting circuit.

The transformer input and output series resistance starting circuit of the present invention is composed of an input side and an output side. The input side is a three-phase terminal, and the three-phase terminal is connected with a contactor. The other end of the resistor is connected to the input side of the transformer; the three-phase end of the input side is connected in parallel with the universal frame circuit breaker and then connected to the input side of the transformer; the three-phase end of the output side is connected to the contactor, and the contactor is connected in series with three winding resistors One end of the winding resistance, the other end of the winding resistance is connected to the output end of the transformer; the three-phase end of the output side is connected in parallel with the universal frame circuit breaker and then connected to the output side of the transformer; the tap joint on the output side of the transformer is connected to the contactor, and the contactor Connect with three wire-wound resistors connected in parallel and the universal frame circuit breaker; the PLC output point is connected with the input side of the transformer input and output series resistance starting circuit in the following way: Y1 is connected to the input soft start contactor coil, Y2 is connected to the input side universal frame Type circuit breaker closing coil, Y3 is connected to the input side universal frame type circuit breaker opening coil; the PLC output point is connected to the output side of the transformer output series resistance starting circuit in the following way: Y4 is connected to the output soft start contactor coil, Y5 is connected to the output side The closing coil of the universal frame circuit breaker, Y6 is connected to the opening coil of the universal frame circuit breaker on the output side; Y7 is connected to one of the three sets of coils of the transformer to connect the contactor coil of the joint, and Y10 is connected to the second set of the three sets of coils of the transformer to be connected Joint contactor coil, Y11 is connected to the third group of the three sets of coils of the transformer to be connected to the joint contactor coil; the PLC input point is connected to the input side of the transformer input series resistance starting circuit in the following way: X1 is connected to the input soft start button, X2 is connected to the input branch Brake button; the PLC input point is connected to the output side of the transformer output series resistance starting circuit in the following way: X3 is connected to one group of the three groups of coils of the output soft start to connect the start button, and X4 is connected to one group of the three groups of coils of the output soft start to connect the branch Brake button; X5 is connected to one of the three groups of coils for the output soft start and connected to the start button; X6 is connected to one of the three groups of coils for the output soft start to connect the opening button; X7 is connected to one of the three groups of coils for the output soft start to connect the start Button, X10 is connected to one of the three sets of output soft start coils connected to the opening button.

The special software program that PLC uses among the present invention is as follows:

The operation process of the present invention is as follows: the above-mentioned software program is written in the PLC, and the transformer input series resistance is driven to start the circuit according to the following program, so as to realize the two-way soft start of the control transformer. The specific operation process is as follows: the starting circuit of the transformer input series resistance is first connected with the three-phase power supply, press the input soft start button, X1 is connected to the input contactor coil through Y1, the coil is energized, and the input contactor is closed; the series resistance soft start, delay For 2 seconds, Y2 energizes the closing coil of the input universal frame circuit breaker, and the main contact of the input universal frame circuit breaker closes. After a delay of 2 seconds, the input contactor coil loses power; press the input opening button , Y3 makes the opening coil of the input universal frame circuit breaker energized, and the main contact of the input universal frame circuit breaker is disconnected; press the switch start button of one of the three sets of output soft start coils, and the Y4 output contactor coil is energized , the main contact of the Y4 output contactor is closed, Y7 makes one of the three groups of coils of the output soft start the contactor coil energized, and the main contact of one group of the three groups of coils is closed, and the delay is 2 seconds. Make Y5 energize the closing coil of the output universal frame circuit breaker, the main contact of the output universal frame circuit breaker is energized, delay for 2 seconds, the coil of the Y4 output contactor is de-energized, and the main contact of the output contactor of Y4 is disconnected ;Press one of the three groups of coils to switch the opening button, X4 will energize the output universal frame circuit breaker opening coil through Y6, and at the same time through Y7 will make one of the output soft start three groups of coils to switch off the contactor coil Electricity, the main contact of the opening coil of the universal frame circuit breaker is disconnected, and Y7 makes the main contact of a group of contactors in the three groups of coils of the output soft start disconnected. After the above-mentioned software is driven and operated, one of the three groups of coils on the output side is connected to the voltage soft-start and break-off. The circuit is started by different control points of the PLC and the input and output series resistors of the transformer, and the contactor and circuit breaker on the output side are jointly controlled to realize the voltage switching and soft start of the other two groups of the three groups of coils on the output side.

Because of the design and use of the transformer input and output series resistance starting circuit and the above-mentioned PLC special software program, the present invention can realize the technical purpose of transformer bidirectional starting, automatic switching, switching voltage and reducing excitation inrush current. It has practical application effect and market potential.

Description of drawings

Accompanying drawing 1 is the electrical principle diagram of the starting circuit of transformer input and output series resistance of the present invention, also is the figure with specification summary; Accompanying drawing 2 is the schematic diagram of PLC external contact point, and the code of Y+ Arabic numeral and X+ Arabic numeral shown in the figure is PLC external contact point code , consistent with the contacts and related codes used in the manual. The labels in the figure are: (1) input side, (2) output side, (3) soft start input contactor, (4) universal frame type input circuit breaker (5), (6), (7) resistors, (8) Soft start output contactor, (9) Universal frame type output circuit breaker, (10), (11), (12) resistors, (13), (13¹), (13²) one set of voltage in three sets of coils Switching contactor, (14), (14¹), (14²) one set of voltage switching contactors among the three sets of coils, (15) (15¹) (15²) one set of voltage switching contactors among the three sets of coils, (16) three Phase power input terminal, (17) transformer output terminal.

detailed description

An embodiment is now given in conjunction with the accompanying drawings to further illustrate the present invention.

Example

The input side 1 of the transformer input and output series resistance starting circuit is a three-phase terminal, and the three-phase terminal is connected to the contactor 3, and the contactor 3 is a CJ20--100 type contactor; the contactor 3 is connected in series with three winding resistors 5, One end of 6 and 7, the three wire-wound resistors 5, 6, and 7 are the same 20 ohm 2KW resistors; the other ends of the three wire-wound resistors 5, 6, and 7 are connected to the input side 1 of the transformer, and the transformer is an isolation transformer. The group is YNd11; the three-phase terminal 16 on the input side is connected in parallel with the universal frame circuit breaker 4 and then connected to the input side of the transformer. The model of the universal frame circuit breaker 4 is NA1-1500/3; 8 are connected, the contactor 8 model is CJ20-100, the contactor 8 is connected in series with one end of three wire-wound resistors 10, 11, 12, and the three wire-wound resistors 10, 11, 12 are the same 20 ohms 2KW resistor, wound The other end of the line resistance is connected to the output terminal of the transformer; the three-phase terminal 17 on the output side is connected in parallel with the universal frame circuit breaker 9 and then connected to the output side of the transformer. The model of the universal frame circuit breaker 9 is NA1-1800/3; the output side of the transformer The tap joints of the contactors are connected to the contactors 13, 14, 15, the model of the contactors 13, 14, 15 is CJ 20-800, and the contactors 13, 14, 15 are connected with three wire-wound resistors 10, 11, 12 in parallel It is connected with the universal frame circuit breaker 9; the PLC model is FX2N-48MR; the PLC output point is connected with the input side 1 of the transformer input and output series resistor starting circuit in the following way: Y1 is connected to the input soft start contactor 3 coil, Y2 is connected to the input side Universal frame circuit breaker 4 closing coil, universal frame circuit breaker 4 model is NA1-1800/3, Y3 is connected to the input side universal frame circuit breaker 4 opening coil; PLC output point and transformer output series resistance start circuit output side 2. Connect in the following way: Y4 is connected to the 8 coils of the output soft-start contactor, Y5 is connected to the 9 closing coils of the universal frame circuit breaker on the output side, Y6 is connected to the 9 opening coils of the output side universal frame circuit breaker; Y7 is connected to the three sets of coils of the transformer One set of tap joint contactor coils 13, 13, 13, Y10 is connected to the second set of tap joint contactor coils 14, 14, 14 of the three sets of coils of the transformer, Y11 is connected to the third set of tap joints of the three sets of transformer coils Coils of contactors 15, 15, and 15, contactors 13, 14, and 15 are CJ20-800, and the PLC input point is connected with the input side 1 of the transformer input series resistance starting circuit in the following way: X1 is connected to the input soft start button, and X2 is connected to Input switch-off button; PLC input point and output side 2 of the transformer output series resistance starting circuit are connected in the following way: X3 is connected to one of the three groups of coils for output soft start and connected to the start button, X4 is connected to one of the three groups of coils for output soft start Tap the opening button; X5 is connected to one of the three groups of coils for the output soft start to connect the start button; X6 is connected to one of the three groups of coils for the output soft start to connect the opening button; X7 is connected to one of the three groups of coils for the output soft start Tap the start button, X10 is connected to the output soft start three groups of coils, and one group is connected to the opening button.

Claims (2)

1. A method for two-way soft start of a transformer based on PLC control, characterized in that: the transformer input and output series resistance starting circuit is composed of an input side and an output side, the input side is a three-phase terminal, and the three-phase terminal is connected with a contactor, and the contactor One end of the three wire-wound resistors is connected in series, and the other end of the three wire-wound resistors is connected to the input side of the transformer; the three-phase end of the input side is connected in parallel with the universal frame circuit breaker and then connected to the input side of the transformer; the three-phase end of the output side The contactor is connected with one end of three wire-wound resistors in series, and the other end of the wire-wound resistor is connected with the output end of the transformer; the three-phase end of the output side is connected in parallel with the universal frame circuit breaker at the same time and then connected with the output side of the transformer; The tap on the output side of the transformer is connected to the contactor, and the contactor is connected to the three wire-wound resistors connected in parallel and the universal frame circuit breaker; the PLC output point is connected to the input side of the transformer input and output series resistance starting circuit in the following way: Y1 is connected to the coil of the input soft start contactor, Y2 is connected to the closing coil of the universal frame circuit breaker on the input side, and Y3 is connected to the opening coil of the universal frame circuit breaker on the input side; the PLC output point and the transformer output series resistor start the circuit output side in the following way Connection: Y4 is connected to the coil of the output soft-start contactor, Y5 is connected to the closing coil of the universal frame circuit breaker on the output side, Y6 is connected to the opening coil of the universal frame circuit breaker on the output side; Y7 is connected to one of the three groups of coils of the transformer to be contacted by a tap joint Y10 is connected to the second group of tap joint contactor coils among the three sets of coils of the transformer, and Y11 is connected to the third group of tap joint contactor coils among the three sets of transformer coils; the PLC input point and the input side of the transformer input string resistance start circuit are used Connect in the following way: X1 is connected to the input soft start button, X2 is connected to the input opening button; the PLC input point is connected to the output side of the transformer output series resistor start circuit in the following way: X3 is connected to the output soft start three groups of coils and one group is connected to the start button , X4 is connected to one of the three sets of coils for the output soft start to connect the opening button; X5 is connected to one of the three sets of coils for the output soft start to connect the start button, X6 is connected to one of the three sets of coils for the output soft start to connect the opening button ; X7 is connected to one of the three sets of coils for output soft start and connected to the start button, and X10 is connected to one of the three sets of coils for output soft start to be connected to the opening button. 2. a kind of method based on PLC control transformer two-way soft start as claimed in claim 1, is characterized in that: the special software program that PLC uses is as follows: .