Voltage type fault tripping protection device and protection method thereof

Abstract

The present invention relates to a voltage-type fault disconnection protection method, which solves the problems of the prior art. The key points of its technical solution are: it is applicable to a substation of a new energy power source, adopts a voltage-type fault disconnection protection device as an execution device, and when the voltage-type fault disconnection protection device is working, adopts a low voltage or zero-sequence overvoltage judgment method to perform fault disconnection protection, and also performs the following steps: S1, a processor collects three-phase voltage data at the outlet of the substation through a three-phase voltage data collector, and the processor collects high-voltage side current data of the substation through a high-voltage side current collector of the substation; S2, when the three-phase voltages are simultaneously lower than a set threshold and there is no current on the high-voltage side of the main transformer of the substation, the low-voltage judgment criterion of the fault disconnection protection is locked.

Description

Technical Field

[0001] The invention relates to a method for quickly analyzing and judging a fault point, and in particular to a voltage-type fault tripping protection device and a protection method thereof. Background Art

[0002] With the advancement of new power system construction, large-scale renewable energy power sources are being connected to the grid from 35 kV (10 kV side) 110 kV substations. To ensure successful reclosing of the 110 kV substation's main power supply line in the event of a fault, it is required to disconnect (trip) the connected renewable energy power source line before reclosing. Therefore, fault disconnect devices are installed in 110 kV substations. Currently, voltage-type fault disconnect devices are typically used for fault disconnection, according to State Grid's standardized design specifications.

[0003] Existing problems: From the perspective of configuration strategy, a fault disconnecting device is configured in the 110 kV substation as a backup for the fault disconnecting protection on the grid-connected renewable energy power supply side. When the fault disconnecting protection (or anti-islanding protection) on the renewable energy power supply side fails to operate for some reason, the fault disconnecting device in the 110 kV substation will cut off the grid-connected line.

[0004] Under normal circumstances, the fault disconnection protection (or anti-islanding protection) on the renewable energy power supply side can operate correctly. At this time, it is not desirable for the fault disconnection device in the 110 kV substation to operate and cut off the grid-connected line, because after the renewable energy power supply is disconnected by itself, it will not affect the reclosing of the 110 kV line. Not cutting off the grid-connected line can ensure the power supply to the T-connected users on the line and increase the speed of the renewable energy power supply being reconnected to the grid.

[0005] However, the current voltage-type fault disconnection protection is implemented by using low voltage or zero-sequence overvoltage criteria. When the new energy power source disconnects itself, the zero-sequence overvoltage criterion can return, but the low voltage criterion will inevitably act to cut off the grid-connected line, causing the cut-off range to expand, which is not conducive to user power supply and the rapid restoration of new energy power source to the grid. Summary of the Invention

[0006] In view of the above technical solution, there is a problem in the existing technology that there is a current voltage-type fault disconnection protection, which is implemented by adopting low voltage or zero-sequence overvoltage judgment. When the new energy power supply is disconnected by itself, the zero-sequence overvoltage judgment can be returned, but the low voltage judgment will inevitably act to cut off the grid-connected line, resulting in an expansion of the cut-off range, which is not conducive to the power supply to users and the rapid restoration of the new energy power supply to the grid. The present invention provides a voltage-type fault disconnection protection device and a protection method thereof.

[0007] The technical solution adopted by the present invention to solve its technical problem is: a voltage-type fault decoupling protection device, which is suitable for a substation of a new energy power supply. The voltage-type fault decoupling protection device includes a memory, a processor, an LCD display, a network communication module, an RS485 module, a three-phase voltage data collector, a substation high-voltage side current collector, an isolation protection module, and a human-machine input module. The processor is connected to the main console through the network communication module, the three-phase voltage data collector and the substation high-voltage side current collector are respectively connected to the processor through the isolation protection module, the memory, the LCD display, and the human-machine input module are all electrically connected to the processor, and the processor is connected to the execution device of the grid-connected line through the RS485 module;

[0008] When the voltage-type fault tripping protection device is in operation, it uses the low voltage or zero-sequence overvoltage judgment method to perform fault tripping protection, and also performs the following judgment steps:

[0009] S1. The processor collects the three-phase voltage data of the substation outlet through the three-phase voltage data collector, and the processor collects the high-voltage side current data of the substation through the high-voltage side current collector of the substation;

[0010] S2. When the three-phase voltage is lower than the set threshold at the same time and there is no current on the high-voltage side of the substation main transformer, the low voltage criterion for fault tripping protection is locked.

[0011] The present invention mainly proposes an improved method for the principle of voltage-type fault disconnection protection and its supporting implementation equipment. When the new energy power source disconnects itself, the low voltage criterion of the fault disconnection protection can return correctly and the grid-connected line will no longer be cut off. A three-phase simultaneous lower limit threshold for the low voltage criterion is set, that is, when the three-phase voltage is lower than a certain value at the same time, it can be considered that the new energy power source has disconnected itself, and the low voltage criterion is locked. Taking into account that the three-phase short-circuit fault at the transformer substation outlet also presents a three-phase low voltage, in order to distinguish this working condition, the main transformer high-voltage side current criterion can be introduced. Because the three-phase short-circuit fault at the transformer substation outlet presents a three-phase low voltage at the same time, the main transformer has a fault current flowing through it, while the three-phase low voltage after the new energy power source disconnects itself will not have current flowing through the main transformer. That is, when the three-phase voltage is low and the main transformer has no current, the low voltage criterion of the fault disconnection protection is locked.

[0012] Preferably, the processor performs a logical judgment on the current state of the fault tripping protection and displays it through the LCD display.

[0013] Preferably, the control signal sent by the processor controls the execution device of the grid-connected line through the RS485 module, and the manual input control of the processor is input by the network communication module or the human-machine input module.

[0014] Preferably, in S2, the set threshold is set manually, and the set threshold and process data are stored in a memory.

[0015] Preferably, when the voltage-type fault tripping protection device adopts the low voltage or zero-sequence overvoltage judgment method and performs fault tripping protection through the judgment steps, the processor uploads the data in the current memory to the main console through the network communication module.

[0016] Preferably, the memory is divided and stored with preset programs for low voltage or zero sequence overvoltage judgment method, and the selection of low voltage or zero sequence overvoltage judgment method is determined by the main control console.

[0017] A method for voltage-type fault disconnection protection is applicable to a substation of a new energy power source. A voltage-type fault disconnection protection device is used as an execution device. When the voltage-type fault disconnection protection device is in operation, a low voltage or zero-sequence overvoltage judgment method is used to perform fault disconnection protection. The following steps are also performed:

[0018] S1. The processor collects the three-phase voltage data of the substation outlet through the three-phase voltage data collector, and the processor collects the high-voltage side current data of the substation through the high-voltage side current collector of the substation;

[0019] S2. When the three-phase voltage is lower than the set threshold at the same time and there is no current on the high-voltage side of the substation main transformer, the low voltage criterion for fault tripping protection is locked.

[0020] The substantial effect of the present invention is: the present invention mainly proposes an improved method of the voltage-type fault disconnection protection principle and its supporting implementation equipment. When the new energy power supply disconnects itself, the low voltage criterion of the fault disconnection protection can return correctly and no longer cut off the grid-connected line. Set a three-phase simultaneous lower limit threshold for the low voltage criterion, that is, when the three-phase voltage is lower than a certain value at the same time, it can be considered that the new energy power supply has disconnected itself, and then the low voltage criterion is locked. Taking into account that the three-phase short-circuit fault at the transformer substation outlet also presents a three-phase low voltage, in order to distinguish this working condition, the main transformer high-voltage side current criterion can be introduced, because the three-phase short-circuit fault at the transformer substation outlet presents a three-phase low voltage while the main transformer has a fault current flowing through it, while the three-phase low voltage after the new energy power supply disconnects itself will not have current flowing through the main transformer. That is, when the three-phase voltage is low and the main transformer has no current, the low voltage criterion of the fault disconnection protection is locked. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 , is a schematic diagram of the overall structure of this embodiment;

[0022] In the figure: 1. Main control console, 2. Processor, 3. Isolation protection module, 4. Three-phase voltage data collector, 5. Substation high-voltage side current collector, 6. RS485 module, 7. Memory, 8. LCD display, 9. Human-machine input module, 10. Network communication module, 11. Power supply module. DETAILED DESCRIPTION

[0023] The technical solution of the present invention is further described in detail below through specific embodiments.

[0024] Example 1:

[0025] A voltage type fault tripping protection device (see attached Figure 1 ), suitable for substations with new energy power sources, the voltage-type fault decoupling protection device is powered by a power module 11, including a memory 7, a processor 2, an LCD display 8, a network communication module 10, an RS485 module 6, a three-phase voltage data collector 4, a substation high-voltage side current collector 5, an isolation protection module 3 and a human-machine input module 9, the processor is connected to the main console 1 through the network communication module, the network communication module generally does not adopt wireless transmission, the three-phase voltage data collector and the substation high-voltage side current collector are respectively connected to the processor through the isolation protection module, the memory, the LCD display and the human-machine input module are all connected to the processor Electrical connection, the processor is connected to the execution device of the grid-connected line through the RS485 module; in this embodiment, the memory 7 adopts a TF card for storage, the processor 2 adopts an ARM architecture processor, the LCD display 8 can be replaced by other low-power display elements, the RS485 module 6 can also be replaced by an RS232 module or other execution device connection module as needed, the three-phase voltage data collector 4 and the substation high-voltage side current collector 5 are all existing technologies, the isolation protection module 3 mainly plays an isolation protection role, and also belongs to the existing conventional technology, and the human-machine input module 9 is configured in the form of an ordinary array keyboard in this embodiment.

[0026] When the voltage-type fault tripping protection device is in operation, it uses the low voltage or zero-sequence overvoltage judgment method to perform fault tripping protection, and also performs the following judgment steps:

[0027] S1. The processor collects the three-phase voltage data of the substation outlet through the three-phase voltage data collector, and the processor collects the high-voltage side current data of the substation through the high-voltage side current collector of the substation;

[0028] S2. When the three-phase voltage is simultaneously lower than the set threshold and there is no current on the high-voltage side of the substation main transformer, the low-voltage criterion for the fault tripping protection is locked. In S2, the set threshold is manually set, and the set threshold and process data are stored in the memory. The selection and setting of the set threshold can refer to the already set substation or be configured accordingly according to the substation equipment. Since the threshold in this embodiment has a large adjustment space, it only needs to be a certain low voltage. For the specific value, the impact is not significant. Therefore, it is also advisable to set it based on experience. In this embodiment, when the voltage-type fault tripping protection device adopts the low voltage or zero-sequence overvoltage criterion method and performs fault tripping protection through the judgment step, the processor uploads the data currently in the memory to the main control console via the network communication module. Furthermore, the memory is divided and stored with preset programs for the low voltage or zero-sequence overvoltage criterion method, and the selection of the low voltage or zero-sequence overvoltage criterion method is determined by the main control console.

[0029] This embodiment mainly proposes an improved method for the principle of voltage-type fault disconnection protection and its supporting implementation equipment. When the new energy power supply is disconnected by itself, the low voltage criterion of the fault disconnection protection can be correctly returned and the grid-connected line will no longer be cut off. A three-phase simultaneous lower limit threshold for the low voltage criterion is set. That is, when the three-phase voltage is simultaneously lower than a certain value, it can be considered that the new energy power supply has been disconnected by itself, and the low voltage criterion is locked. Considering that the three-phase short circuit fault at the substation outlet also presents a three-phase low voltage, in order to distinguish this working condition, the main transformer high-voltage side current criterion can be introduced. Because the three-phase short circuit fault at the substation outlet presents a three-phase low voltage while the main transformer has a fault current flowing through it, while the three-phase low voltage after the new energy power supply is disconnected by itself will not have current flowing through the main transformer. That is, when the three-phase voltage is low and the main transformer has no current, the low voltage criterion of the fault disconnection protection is locked. In this embodiment, the processor performs a logical judgment on the current state of the fault disconnection protection and displays it on the LCD display. The control signal sent by the processor controls the execution device of the grid-connected line through the RS485 module, and the manual input control of the processor is input through the network communication module or the human-machine input module.

[0030] A method for voltage-type fault disconnection protection is applicable to a substation of a new energy power source. A voltage-type fault disconnection protection device is used as an execution device. When the voltage-type fault disconnection protection device is in operation, a low voltage or zero-sequence overvoltage judgment method is used to perform fault disconnection protection. The following steps are also performed:

[0031] S1. The processor collects the three-phase voltage data of the substation outlet through the three-phase voltage data collector, and the processor collects the high-voltage side current data of the substation through the high-voltage side current collector of the substation;

[0032] S2. When the three-phase voltage is lower than the set threshold at the same time and there is no current on the high-voltage side of the substation main transformer, the low voltage criterion for fault tripping protection is locked.

[0033] The embodiment described above is only a preferred solution of the present invention and does not limit the present invention in any form. Other variations and modifications are possible without exceeding the technical solution described in the claims.

Claims

1. A voltage type fault tripping protection device, characterized in that: Applicable to substations with new energy power sources, the voltage-type fault decoupling protection device includes a memory, a processor, an LCD display, a network communication module, an RS485 module, a three-phase voltage data collector, a substation high-voltage side current collector, an isolation protection module, and a human-machine input module. The processor is connected to the main console through the network communication module, the three-phase voltage data collector and the substation high-voltage side current collector are respectively connected to the processor through the isolation protection module, the memory, LCD display, and human-machine input module are all electrically connected to the processor, and the processor is connected to the execution device of the grid-connected line through the RS485 module; When the voltage-type fault tripping protection device is in operation, it uses the low voltage or zero-sequence overvoltage judgment method to perform fault tripping protection, and also performs the following judgment steps: S1. The processor collects the three-phase voltage data of the substation outlet through the three-phase voltage data collector, and the processor collects the high-voltage side current data of the substation through the high-voltage side current collector of the substation; S2. When the three-phase voltage is lower than the set threshold at the same time and there is no current on the high-voltage side of the substation main transformer, the low voltage criterion for fault tripping protection is locked.

2. The method for voltage-type fault disconnection protection according to claim 1, characterized in that: The processor performs a logical judgment on the current fault tripping protection state and displays it through the LCD display.

3. The method for voltage-type fault disconnection protection according to claim 2, characterized in that: The control signal sent by the processor controls the execution device of the grid-connected line through the RS485 module, and the manual input control of the processor is input through the network communication module or the human-machine input module.

4. The method for voltage-type fault disconnection protection according to claim 3, characterized in that: In S2 , the set threshold is set manually, and the set threshold and process data are stored in a memory.

5. The method for voltage-type fault disconnection protection according to claim 4, characterized in that: When the voltage-type fault tripping protection device adopts the low voltage or zero-sequence overvoltage judgment method and performs fault tripping protection through the judgment steps, the processor uploads the data in the current memory to the main console through the network communication module.

6. The method for voltage-type fault disconnection protection according to claim 5, characterized in that: The memory stores preset programs for low voltage or zero sequence overvoltage judgment methods, and the selection of low voltage or zero sequence overvoltage judgment method is determined by the main control console.

7. A method for voltage type fault disconnection protection, characterized in that: Applicable to substations with new energy power sources, a voltage-type fault disconnection protection device is used as an execution device. When the voltage-type fault disconnection protection device is working, it adopts the low voltage or zero-sequence overvoltage judgment method to perform fault disconnection protection, and also performs the following steps: S1. The processor collects the three-phase voltage data of the substation outlet through the three-phase voltage data collector, and the processor collects the high-voltage side current data of the substation through the high-voltage side current collector of the substation; S2. When the three-phase voltage is lower than the set threshold at the same time and there is no current on the high-voltage side of the substation main transformer, the low voltage criterion for fault tripping protection is locked.

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