A device for testing the differential coordination of protection switches in an AC power supply system

Abstract

The invention provides a differential coordination test device for an AC power system protection switch, which is used to verify the differential coordination of distribution switches at various levels under different short-circuit currents. The device comprises: a PLC, a pulse application port, a drive circuit, an adjustable resistor group, and an adjustable capacitor and inductor group. The adjustable resistor group and the adjustable capacitor and inductor group are connected to a three-phase AC power circuit with a multi-level distribution switch, and the adjustable resistor group and the adjustable capacitor and inductor group are adjusted through the pulse application port and the drive circuit controlled by the PLC, so that the current in the circuit is adjusted to perform a differential coordination test. A three-phase AC contactor is provided, and when the adjusted current is too large, the circuit is disconnected to ensure safety. A communication module is provided, and the experimental data collected by the PLC is uploaded to a network to facilitate analysis and processing.

Description

Technical Field

[0001] The invention belongs to the field of differential coordination of AC power supply protection switches, and in particular relates to a differential coordination testing device for AC power supply system protection switches. Background Art

[0002] AC circuit breakers are important components of the AC system power supply network. The AC circuit breakers in the AC power supply system of the substation are generally small air circuit breakers. They are switch devices that integrate operation and protection. They are easy to install and maintain, flexible to operate, and have high stability. They have been widely used in the power supply network of substations. Improper matching of the circuit breaker level difference or failure will directly affect the safe power supply of the AC power supply system and bring great harm to the safe operation of the power grid. Generally, the three-phase AC power supply is equipped with a primary distribution switch, a secondary distribution switch, and a tertiary distribution switch. The current required to trigger the primary distribution switch is greater than the current required to trigger the secondary distribution switch. The current required for triggering the secondary distribution switch is greater than the current required for triggering the tertiary distribution switch. For example, the tertiary distribution switch will trip first after reaching a certain current value. If this current value reaches the value that can cause the secondary distribution switch to trip, the tertiary and secondary distribution switches will trip at the same time. This is the differential coordination of the distribution switches at each level under different short-circuit currents, but in actual applications, over-tripping may occur. This is often because the quality of the distribution switch does not meet the standards or is damaged. At this time, the staff needs to repair and replace it, but due to over-tripping, the staff may be in danger during maintenance and waste time. Summary of the invention

[0003] The object of the present invention is to provide a differential coordination testing device for protection switches in an AC power supply system, which is used to verify the differential coordination of distribution switches at various levels under different short-circuit currents.

[0004] The technical solution for solving the technical problem of the present invention is: a differential coordination test device for a protection switch of an AC power supply system, comprising: a PLC, a pulse application port, a drive circuit, an adjustable resistor group, and an adjustable capacitor and inductor group for adjusting the direction of current and voltage, wherein the output end of the PLC is connected to the input end of the pulse application port, the output end of the pulse application port is connected to the input end of the drive circuit, the output end of the drive circuit is respectively connected to the input ends of the adjustable resistor and the adjustable capacitor and inductor group, the A phase, the B phase, and the C phase of the three-phase power supply are connected in series with one end of the adjustable capacitor and inductor group through the adjustable resistor, and the other end of the adjustable capacitor and inductor group is connected to the N phase of the three-phase power supply, a command is sent to the pulse application port through the PLC to control the pulse application port to send a pulse, and the adjustable resistor group and the adjustable capacitor and inductor group are adjusted through the drive circuit, thereby adjusting the current in the circuit, and then verifying the differential coordination of distribution switches at all levels under different short-circuit currents.

[0005] The adjustable resistor includes a first adjustable resistor, a second adjustable resistor, and a third adjustable resistor, and the first adjustable resistor, the second adjustable resistor, and the third adjustable resistor are connected in series to phase A, phase B, and phase C of a three-phase AC power supply.

[0006] The adjustable capacitor-inductor group includes a first adjustable inductor, a first adjustable capacitor, a second adjustable inductor, a second adjustable capacitor, a third adjustable inductor, and a third adjustable capacitor. After the first adjustable inductor and the first adjustable capacitor are connected in parallel, one end is connected to the A phase of the three-phase AC power supply, and the other end is connected to the N phase of the three-phase AC power supply. After the second adjustable inductor and the second adjustable capacitor are connected in parallel, one end is connected to the B phase of the three-phase AC power supply, and the other end is connected to the N phase of the three-phase AC power supply. After the third adjustable inductor and the third adjustable capacitor are connected in parallel, one end is connected to the C phase of the three-phase AC power supply, and the other end is connected to the N phase of the three-phase AC power supply.

[0007] In order to measure the adjusted current and voltage, a main circuit measurement module for measuring the adjusted voltage and current is also included. The main circuit measurement module includes a first current transformer, a second current transformer, a third current transformer, a first voltage transformer, a second voltage transformer, a third voltage transformer, a measurement circuit, and an AD conversion module. The first current transformer, the second current transformer, and the third current transformer are respectively connected in series to the A phase, the B phase, and the C phase between the three-phase power supply and the adjustable resistor. One end of the first voltage transformer is connected to the A phase between the three-phase power supply and the adjustable resistor, and the other end is connected to the three-phase power supply. and the N phase between the three-phase power supply and the adjustable resistor, one end of the second voltage transformer is connected to the B phase between the three-phase power supply and the adjustable resistor, and the other end is connected to the N phase between the three-phase power supply and the adjustable resistor, one end of the third voltage transformer is connected to the C phase between the three-phase power supply and the adjustable resistor, and the other end is connected to the N phase between the three-phase power supply and the adjustable resistor, the output ends of the first current transformer, the second current transformer, the third current transformer, the first voltage transformer, the second voltage transformer, and the third voltage transformer are connected to the AD conversion module through the measurement loop, and the output end of the AD conversion module is connected to the PLC.

[0008] In order to measure the current and voltage before adjustment, a branch loop measurement module for measuring the voltage and current before adjustment is also included, and the branch loop measurement module includes a fourth current transformer, a fifth current transformer, a sixth current transformer, a fourth voltage transformer, a fifth voltage transformer, and a sixth voltage transformer. The fourth current transformer, the fifth current transformer, and the sixth current transformer are respectively connected in series with the first adjustable inductor, the second adjustable inductor, and the third adjustable inductor, and then connected in parallel with the first adjustable capacitor, the second adjustable capacitor, and the third adjustable capacitor. One end of the fourth voltage transformer is connected to the A phase between the adjustable resistor and the adjustable capacitor and inductor group, and the other end is connected to the adjustable resistor and N phases between the adjustable capacitor and inductor groups, one end of the fifth voltage transformer is connected to the B phase between the adjustable resistor and the adjustable capacitor and inductor group, and the other end is connected to the N phase between the adjustable resistor and the adjustable capacitor and inductor group, one end of the sixth voltage transformer is connected to the C phase between the adjustable resistor and the adjustable capacitor and inductor group, and the other end is connected to the N phase between the adjustable resistor and the adjustable capacitor and inductor group, the output ends of the fourth current transformer, the fifth current transformer, the sixth current transformer, the fourth voltage transformer, the fifth voltage transformer, and the sixth voltage transformer are connected to the AD conversion module through a measurement loop, and the output end of the AD conversion module is connected to the PLC.

[0009] In order to disconnect the circuit when the adjusted current is too high, it also includes a three-phase AC contactor for disconnecting the circuit when the set voltage and current values ​​exceed the specified values. The three-phase AC contactor is arranged on phases A, B, and C between the first current transformer, the second current transformer, the third current transformer and the three-phase AC power supply. The input end of the three-phase AC contactor is connected to the output end of the drive circuit, and the input end of the drive circuit is connected to the output end of the pulse application port.

[0010] In order to collect and process the experimental data, a communication module for sending the experimental data to the network is also included, and the input end of the communication module is connected to the output end of the PLC.

[0011] The beneficial effects of the present invention are as follows: by connecting an adjustable resistor group and an adjustable capacitor and inductor group to a three-phase AC power supply circuit with a multi-stage power distribution switch, the adjustable resistor group and the adjustable capacitor and inductor group are adjusted through a pulse application port and a drive circuit controlled by a PLC, thereby adjusting the current in the circuit, providing currents of different sizes required for a differential test, and performing a differential coordination test; by setting a branch circuit measurement module, the current and voltage before adjustment are measured before the differential test; by setting a main circuit measurement module, the current and voltage after adjustment during the differential test are measured; by setting a three-phase AC contactor, when the adjusted current is too large during the differential test, the circuit is disconnected to ensure safety; by setting a communication module, the differential experiment data collected by the PLC is uploaded to the network for easy analysis and processing. BRIEF DESCRIPTION OF THE DRAWINGS

[0012] Figure 1 It is a schematic diagram of the present invention.

[0013] Figure 2 It is a usage state diagram of the present invention. DETAILED DESCRIPTION

[0014] The technical solutions in the embodiments of the present invention will be described clearly and completely below in conjunction with the accompanying drawings in the embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0015] like Figure 1 As shown, the present invention includes: a PLC, a pulse application port, a drive circuit, an adjustable resistor group, and an adjustable capacitor and inductor group for adjusting the direction of current and voltage. The output end of the PLC is connected to the input end of the pulse application port, and the output end of the pulse application port is connected to the input end of the drive circuit. The output end of the drive circuit is respectively connected to the input ends of the adjustable resistor and the adjustable capacitor and inductor group. Phase A, phase B, and phase C of the three-phase power supply are connected in series with one end of the adjustable capacitor and inductor group through the adjustable resistor, and the other end of the adjustable capacitor and inductor group is connected to phase N of the three-phase power supply. A command is sent to the pulse application port through the PLC to control the pulse application port to send a pulse. The adjustable resistor group and the adjustable capacitor and inductor group are adjusted through the drive circuit, thereby adjusting the current in the circuit, and then verifying the differential coordination of distribution switches at all levels under different short-circuit currents.

[0016] The adjustable resistor includes a first adjustable resistor R1, a second adjustable resistor R2, and a third adjustable resistor R3, which are connected in series to phases A, B, and C of a three-phase AC power supply.

[0017] The adjustable capacitor-inductor group includes a first adjustable inductor L1, a first adjustable capacitor C1, a second adjustable inductor L2, a second adjustable capacitor C2, a third adjustable inductor L3, and a third adjustable capacitor C3. The first adjustable inductor L1 and the first adjustable capacitor C1 are connected in parallel, and one end is connected to the A phase of the three-phase AC power supply, and the other end is connected to the N phase of the three-phase AC power supply. The second adjustable inductor L2 and the second adjustable capacitor C2 are connected in parallel, and one end is connected to the B phase of the three-phase AC power supply, and the other end is connected to the N phase of the three-phase AC power supply. The third adjustable inductor L3 and the third adjustable capacitor C3 are connected in parallel, and one end is connected to the C phase of the three-phase AC power supply, and the other end is connected to the N phase of the three-phase AC power supply.

[0018] In order to measure the adjusted current and voltage, a main circuit measurement module for measuring the adjusted voltage and current is also included, and the main circuit measurement module includes a first current transformer A1, a second current transformer A2, a third current transformer A3, a first voltage transformer V1, a second voltage transformer V2, a third voltage transformer V3, a measurement circuit, and an AD conversion module. The first current transformer A1, the second current transformer A2, and the third current transformer A3 are respectively connected in series to the A phase, the B phase, and the C phase between the three-phase power supply and the adjustable resistor. One end of the first voltage transformer V1 is connected to the A phase between the three-phase power supply and the adjustable resistor, and the other end is connected to the three-phase N phase between the power supply and the adjustable resistor, one end of the second voltage transformer V2 is connected to the B phase between the three-phase power supply and the adjustable resistor, and the other end is connected to the N phase between the three-phase power supply and the adjustable resistor, one end of the third voltage transformer V3 is connected to the C phase between the three-phase power supply and the adjustable resistor, and the other end is connected to the N phase between the three-phase power supply and the adjustable resistor, the output ends of the first current transformer A1, the second current transformer A2, the third current transformer A3, the first voltage transformer V1, the second voltage transformer V2, and the third voltage transformer V3 are connected to the AD conversion module through the measurement loop, and the output end of the AD conversion module is connected to the PLC.

[0019] In order to measure the current and voltage before adjustment, a branch loop measurement module for measuring the voltage and current before adjustment is also included, and the branch loop measurement module includes a fourth current transformer A4, a fifth current transformer A5, a sixth current transformer A6, a fourth voltage transformer V4, a fifth voltage transformer V5, and a sixth voltage transformer V6. The fourth current transformer A4, the fifth current transformer A5, and the sixth current transformer A6 are respectively connected in series with the first adjustable inductor L1, the second adjustable inductor L2, and the third adjustable inductor L3, and then connected in parallel with the first adjustable capacitor C1, the second adjustable capacitor C2, and the third adjustable capacitor C3. One end of the fourth voltage transformer V4 is connected to the A phase between the adjustable resistor and the adjustable capacitor and inductor group, and the other end is connected to the A phase between the adjustable resistor and the adjustable capacitor and inductor group. The N phase between the adjustable resistor and the adjustable capacitor-inductor group is terminated, one end of the fifth voltage transformer V5 is connected to the B phase between the adjustable resistor and the adjustable capacitor-inductor group, and the other end is connected to the N phase between the adjustable resistor and the adjustable capacitor-inductor group, one end of the sixth voltage transformer V6 is connected to the C phase between the adjustable resistor and the adjustable capacitor-inductor group, and the other end is connected to the N phase between the adjustable resistor and the adjustable capacitor-inductor group, the output ends of the fourth current transformer A4, the fifth current transformer A5, the sixth current transformer A6, the fourth voltage transformer V4, the fifth voltage transformer V5, and the sixth voltage transformer V6 are connected to the AD conversion module through the measurement loop, and the output end of the AD conversion module is connected to the PLC.

[0020] In order to disconnect the circuit when the adjusted current is too high, it also includes a three-phase AC contactor for disconnecting the circuit when the set voltage and current values ​​exceed the specified values. The three-phase AC contactor is arranged on the A phase, B phase, and C phase between the first current transformer A1, the second current transformer A2, the third current transformer A3 and the three-phase AC power supply. The input end of the three-phase AC contactor is connected to the output end of the drive circuit, and the input end of the drive circuit is connected to the output end of the pulse application port.

[0021] In order to collect and process the experimental data, a communication module for sending the experimental data to the network is also included, and the input end of the communication module is connected to the output end of the PLC.

[0022] When in use, the device is connected to the three phases (A, B, C) and N phase of the three-phase AC power supply through the primary distribution switch, the secondary distribution switch, the tertiary distribution switch to form a loop. The fourth current transformer A4, the fifth current transformer A5, the sixth current transformer A6, the fourth voltage transformer V4, the fifth voltage transformer V5, and the sixth voltage transformer V6 of the branch measurement module respectively measure the current and voltage of each phase, and send them to the AD conversion module through the measurement loop. The AD conversion module converts the analog signal into a digital signal and sends it to the PLC, and then determines the level difference test. The required current (i.e. the current that triggers the three-level distribution switch but does not trigger the first and second level distribution switches) is generated by the PLC control pulse application port, which sends a pulse signal to adjust the adjustable resistance group and the adjustable capacitance and inductance group to change the current in the circuit. The changed current and voltage are measured by the main circuit measurement module, and sent to the PLC through the measurement circuit and the AD conversion module, so as to test the level difference coordination, and then repeat the verification of the second distribution switch and the first distribution switch. All experimental data are sent to the communication module via the PLC, and the communication module sends the data to the network for analysis.

[0023] When the adjusted current is too large, in order to prevent danger, when the current measured by the main circuit measurement module reaches a dangerous value, the PLC controls the pulse application port and sends a signal to the three-phase AC contactor through the drive circuit to disconnect the circuit.

[0024] By connecting an adjustable resistor group and an adjustable capacitor and inductor group to a three-phase AC power supply circuit with a multi-stage distribution switch, the adjustable resistor group and the adjustable capacitor and inductor group are adjusted through a pulse application port and a drive circuit controlled by a PLC, thereby adjusting the current in the circuit, providing currents of different sizes required for a differential test, and conducting a differential coordination test; by setting a branch circuit measurement module, the current and voltage before adjustment are measured before the differential test; by setting a main circuit measurement module, the current and voltage after adjustment during the differential test are measured; by setting a three-phase AC contactor, when the adjusted current is too large during the differential test, the circuit is disconnected to ensure safety; by setting a communication module, the differential experiment data collected by the PLC is uploaded to the network for easy analysis and processing.

Claims

1. A device for testing the differential coordination of protection switches in an AC power supply system, characterized in that: include: PLC, pulse application port, drive circuit, adjustable resistor group, adjustable capacitor and inductor group for adjusting the direction of current and voltage, the output end of the PLC is connected to the input end of the pulse application port, the output end of the pulse application port is connected to the input end of the drive circuit, the output end of the drive circuit is respectively connected to the input end of the adjustable resistor and the adjustable capacitor and inductor group, the A phase, B phase and C phase of the three-phase power supply are connected in series with one end of the adjustable capacitor and inductor group through the adjustable resistor, and the other end of the adjustable capacitor and inductor group is connected to the N phase of the three-phase power supply; it also includes a main circuit measurement module for measuring the adjusted voltage and current, the main circuit measurement module includes a first current transformer, a second current transformer, a third current transformer, a first voltage transformer, a second voltage transformer, a third voltage transformer, a measurement circuit, an AD conversion module, the first current transformer The first voltage transformer, the second current transformer, and the third current transformer are respectively connected in series to the A phase, the B phase, and the C phase between the three-phase power supply and the adjustable resistor, one end of the first voltage transformer is connected to the A phase between the three-phase power supply and the adjustable resistor, and the other end is connected to the N phase between the three-phase power supply and the adjustable resistor, one end of the second voltage transformer is connected to the B phase between the three-phase power supply and the adjustable resistor, and the other end is connected to the N phase between the three-phase power supply and the adjustable resistor, one end of the third voltage transformer is connected to the C phase between the three-phase power supply and the adjustable resistor, and the other end is connected to the N phase between the three-phase power supply and the adjustable resistor, the output ends of the first current transformer, the second current transformer, the third current transformer, the first voltage transformer, the second voltage transformer, and the third voltage transformer are connected to the AD conversion module through the measurement loop, and the output end of the AD conversion module is connected to the PLC; It also includes a branch loop measurement module for measuring the voltage and current before adjustment, the branch loop measurement module includes a fourth current transformer, a fifth current transformer, a sixth current transformer, a fourth voltage transformer, a fifth voltage transformer, and a sixth voltage transformer, the fourth current transformer, the fifth current transformer, and the sixth current transformer are respectively connected in series with the first adjustable inductor, the second adjustable inductor, and the third adjustable inductor, and then connected in parallel with the first adjustable capacitor, the second adjustable capacitor, and the third adjustable capacitor, one end of the fourth voltage transformer is connected to the A phase between the adjustable resistor and the adjustable capacitor and inductor group, and the other end is connected to the adjustable resistor and the adjustable capacitor and inductor group. The output ends of the fourth current transformer, the fifth current transformer, the sixth current transformer, the fourth voltage transformer, the fifth voltage transformer and the sixth voltage transformer are connected to the AD conversion module through the measurement loop, and the output end of the AD conversion module is connected to the PLC.

2. The AC power system protection switch differential coordination test device according to claim 1, characterized in that: The adjustable resistor includes a first adjustable resistor, a second adjustable resistor, and a third adjustable resistor, and the first adjustable resistor, the second adjustable resistor, and the third adjustable resistor are connected in series to phase A, phase B, and phase C of a three-phase AC power supply.

3. The AC power system protection switch differential coordination test device according to claim 1, characterized in that: The adjustable capacitor-inductor group includes a first adjustable inductor, a first adjustable capacitor, a second adjustable inductor, a second adjustable capacitor, a third adjustable inductor, and a third adjustable capacitor. After the first adjustable inductor and the first adjustable capacitor are connected in parallel, one end is connected to the A phase of the three-phase AC power supply, and the other end is connected to the N phase of the three-phase AC power supply. After the second adjustable inductor and the second adjustable capacitor are connected in parallel, one end is connected to the B phase of the three-phase AC power supply, and the other end is connected to the N phase of the three-phase AC power supply. After the third adjustable inductor and the third adjustable capacitor are connected in parallel, one end is connected to the C phase of the three-phase AC power supply, and the other end is connected to the N phase of the three-phase AC power supply.

4. The AC power system protection switch differential coordination test device according to claim 1, characterized in that: It also includes a three-phase AC contactor for disconnecting the circuit when the set voltage and current values ​​exceed the specified values. The three-phase AC contactor is arranged on phase A, phase B, and phase C between the first current transformer, the second current transformer, the third current transformer and the three-phase AC power supply. The input end of the three-phase AC contactor is connected to the output end of the drive circuit, and the input end of the drive circuit is connected to the output end of the pulse application port.

5. The AC power system protection switch differential coordination test device according to claim 1, characterized in that: It also includes a communication module for sending experimental data to a network, and an input end of the communication module is connected to an output end of the PLC.

Images