Automatic control system for spare power automatic switching of low-voltage bus of power plant

Abstract

The invention relates to a power plant low-voltage bus spare power automatic switching automatic control system which comprises a spare power automatic switching function verification module which is provided with a condition or function block, a negation function block and a switch function block which are connected in sequence and used for verifying the spare power automatic switching function under the condition that a spare power automatic switching action signal, an incoming line switch protection action signal and an interconnection switch protection action signal do not exist. Outputting a spare power automatic switching function input allowing signal; the spare power automatic switching incoming line switch disconnection module is provided with a condition and function block and a first delay function block and is used for generating an incoming line switch disconnection driving signal through the first delay function block after the conditions of the condition and function block are met; and the spare power automatic switching upper interconnection switch module comprises a condition and module and a second voltage constraint condition function block, and is used for outputting a spare power automatic switching action signal after the condition of the condition and module is met, and is used for driving the interconnection switch to be switched on. Compared with the prior art, the error value and the fault probability of the spare power automatic switching function can be reduced, the response time is shortened, and the economical efficiency of a power plant is improved.

Description

Technical Field

[0001] This invention relates to the field of automatic transfer switch technology for power plants, and in particular to an automatic control system for automatic transfer switch of low-voltage busbars in power plants. Background Technology

[0002] The low-voltage busbars of power plant auxiliary power lines carry many critical loads that cannot be de-energized. When a sudden fault occurs and the low-voltage busbar loses power, the automatic transfer switch (ATS) is activated, allowing another busbar to take over the energized busbar. Implementing the ATS function presents several technical challenges. First, it's crucial to determine whether the energized busbar is truly faulty or if a load on that busbar is faulty, and whether the relay protection disconnects the faulty load to restore normal busbar operation. Second, the ATS function must coordinate with the upstream transformer's incoming switch; the incoming switch must be disconnected first to prevent the tie switch and the incoming switch from simultaneously energizing the same busbar. Third, after the protection system disconnects the fault, the tie switch must be closed as quickly as possible to achieve the ATS function.

[0003] Currently, the automatic transfer function is achieved by installing a set of automatic transfer hardware devices, such as the automatic transfer device for low-voltage systems disclosed in the utility model with publication number CN203135568U, and the three-section automatic transfer method for plant power with connecting busbar disclosed in the invention with publication number CN112701778A.

[0004] Its shortcomings are obvious: First, it requires the installation of an additional set of hardware equipment, especially in power plants with numerous low-voltage busbars, increasing economic expenditure due to the need for extra equipment. Second, to accurately implement the automatic transfer switch function, many additional measuring points are required, each increasing the probability of failure, error value, and response time. Third, the hardware-based automatic transfer switch cannot address the coordination issues between the high-voltage and low-voltage busbars of the entire power plant's auxiliary power system. Summary of the Invention

[0005] The purpose of this invention is to overcome the shortcomings of the existing technology, which requires the installation of an additional set of hardware control equipment and the addition of many extra measuring points, thereby increasing costs and the probability of failure, and to provide an automatic control system for the backup automatic transfer of low-voltage busbars in power plants.

[0006] The objective of this invention can be achieved through the following technical solutions:

[0007] An automatic control system for the standby automatic transfer switch of a low-voltage busbar in a power plant is provided for controlling the primary circuit of the low-voltage busbar in the power plant. The primary circuit includes a first low-voltage busbar equipped with an incoming line switch, a second low-voltage busbar equipped with a standby busbar incoming line switch, and a tie switch connecting the first and second low-voltage busbars respectively. The system includes:

[0008] The automatic transfer switch (ATS) verification module includes a condition or function block, an invert function block, and a switch function block connected in sequence. The inputs of the condition or function block include the ATS action signal, the incoming line switch protection action signal, and the tie switch protection action signal. It is used to output an ATS function enable signal when there is no ATS action signal, the incoming line switch protection action signal, or the tie switch protection action signal.

[0009] The automatic transfer switch module for disconnecting incoming lines includes a conditional and concurrent function block and a first delay function block connected in sequence. After the condition in the conditional and concurrent function block is met, the first delay function block generates an incoming line switch disconnect drive signal. The input connections of the conditional and concurrent function block are as follows:

[0010] The first voltage constraint condition function block, the input of which is the voltage value signal of the first low-voltage bus;

[0011] The current constraint condition function block takes the current value signal of the incoming switch as its input.

[0012] The closing constraint condition function block takes the incoming switch position signal as its input.

[0013] The tripping constraint condition function block takes the tripping position signal of the tie switch as its input.

[0014] And the automatic transfer switch function allows the input signal;

[0015] The automatic transfer switch closing module includes a conditional module and a second voltage constraint condition function block. It is used to output an automatic transfer action signal after the condition of the conditional module is met, which is used to drive the tie switch to close. The input of the second voltage constraint condition function block is the standby bus voltage value signal. The input of the conditional module includes the output of the second voltage constraint condition function block and the incoming line switch disconnection drive signal.

[0016] Furthermore, the first voltage constraint function block is used to set a constraint condition on the input voltage value signal of the first low-voltage bus, such that the voltage is less than 50% of the rated voltage.

[0017] Furthermore, the current constraint function block is used to set a constraint condition that the current value signal of the input line switch is less than 6A.

[0018] Furthermore, the second voltage constraint function block is used to set a constraint condition on the input standby bus voltage value signal that the voltage is greater than 80% of the rated voltage.

[0019] Furthermore, the first delay function block is used to set a delay of 5 seconds.

[0020] Furthermore, the system includes a second delay function block, which is used to input the automatic transfer action signal output by the automatic transfer switch closing module into the condition or function block of the automatic transfer function verification module after delay.

[0021] Furthermore, the second delay function block is used to set a 1-second delay.

[0022] Furthermore, the first low-voltage busbar is connected to the first high-voltage busbar via the low-voltage transformer of the first power plant, and the second low-voltage busbar is connected to the second high-voltage busbar via the low-voltage transformer of the second power plant.

[0023] Furthermore, the first low-voltage busbar and the second low-voltage busbar serve as backups for each other.

[0024] Furthermore, the automatic control system for the low-voltage busbar backup in the power plant is integrated into the control system software within the controller.

[0025] Compared with the prior art, the present invention has the following advantages:

[0026] (1) This invention constructs an automatic backup switch control system for the primary circuit of the low-voltage busbar in a power plant. By setting up a backup switch function verification module, it ensures that the backup switch function is allowed to be put into operation, eliminating the possibility that the incoming line switch and tie switch are in a faulty state. By setting up a backup switch disconnect incoming line switch module, it ensures that the switch has been opened when the backup switch is activated, preventing voltage collisions from different sources of incoming line switches. The constraints are that the busbar voltage is low, the incoming line switch has no current, and the incoming line switch is in the closed position and the tie switch is in the open position before the backup switch disconnect incoming line switch module is activated. Finally, the backup switch closes the tie switch module to achieve the ultimate goal of automatic and fast closing of the tie switch. The constraint is that the backup busbar voltage is normal.

[0027] Therefore, the automatic transfer switch function can be implemented through the control system software logic design, completely replacing the installation of automatic transfer switch hardware devices.

[0028] (2) The present invention provides an automatic control system for backup automatic transfer of low-voltage busbars in power plants, which reduces the hardware setup and control, and drives the system directly based on the generated signals. This reduces the error value and failure probability of the backup automatic transfer function, speeds up the response time, and significantly improves the economic efficiency of power plants by reducing hardware equipment. Attached Figure Description

[0029] Figure 1 This is a schematic diagram of the primary circuit of a low-voltage busbar in a power plant, provided in an embodiment of the present invention.

[0030] Figure 2 This is a schematic diagram of the structure of an automatic control system for backup automatic transfer of low-voltage busbars in a power plant, provided in an embodiment of the present invention.

[0031] In the diagram, 1 is the incoming line switch, 2 is the standby bus incoming line switch, 3 is the tie switch, 4 is the automatic transfer function verification module, 5 is the automatic transfer disconnect incoming line switch module, 6 is the automatic transfer close tie switch module, 101 is the automatic transfer action signal, 102 is the incoming line switch protection action signal, 103 is the tie switch protection action signal, 104 is the voltage value signal of the first low-voltage bus, 105 is the current value signal of the incoming line switch, 106 is the incoming line switch position signal, 107 is the tie switch open position signal, 108 is the standby bus voltage value signal, A is the invert function block, B is the switch function block, C is the first voltage constraint condition function block, D is the current constraint condition function block, E is the closing constraint condition function block, F is the opening constraint condition function block, G is the second voltage constraint condition function block, H is the first delay function block, I is the second delay function block, OR is the conditional OR function block, and AND is the conditional AND module. Detailed Implementation

[0032] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. The components of the embodiments of the present invention described and shown in the accompanying drawings can generally be arranged and designed in various different configurations.

[0033] Therefore, the following detailed description of the embodiments of the invention provided in the accompanying drawings is not intended to limit the scope of the claimed invention, but merely to illustrate selected embodiments of the invention. All other embodiments obtained by those skilled in the art based on the embodiments of the invention without inventive effort are within the scope of protection of the invention.

[0034] It should be noted that similar labels and letters in the following figures indicate similar items. Therefore, once an item is defined in one figure, it does not need to be further defined and explained in subsequent figures.

[0035] In the description of this invention, it should be noted that the terms "center," "upper," "lower," "left," "right," "vertical," "horizontal," "inner," and "outer," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings, or the orientation or positional relationship in which the product of this invention is usually placed during use. They are only for the convenience of describing this invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this invention.

[0036] It should be noted that the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Therefore, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of this application, "multiple" means two or more, unless otherwise explicitly specified.

[0037] Furthermore, terms such as "horizontal" and "vertical" do not imply that components must be absolutely horizontal or suspended, but rather that they can be slightly tilted. For example, "horizontal" simply means that its direction is more horizontal than "vertical," and does not mean that the structure must be completely horizontal, but can be slightly tilted.

[0038] Example 1

[0039] like Figure 1 As shown, this embodiment also provides an automatic control system for the backup automatic transfer of a low-voltage busbar in a power plant, used to control the primary circuit of the low-voltage busbar in the power plant. The primary circuit includes a first low-voltage busbar equipped with an incoming line switch 1, a second low-voltage busbar equipped with a backup busbar incoming line switch 2, and a connecting switch 3 that connects the first low-voltage busbar and the second low-voltage busbar respectively. Specifically, the first low-voltage busbar is connected to a first high-voltage busbar through a first low-voltage transformer in the power plant, and the second low-voltage busbar is connected to a second high-voltage busbar through a second low-voltage transformer in the power plant.

[0040] Normally, the tie switch 3 is in the open state. When the incoming switch 1 is disconnected due to operational needs or an unexpected situation, causing a power outage in bus section I, the tie switch 3 is closed, and bus section II supplies power to bus section I. Conversely, the same applies, thus enabling bus section I and bus section II to serve as backup power sources for each other when supplying power to the load. Figure 2 As shown, the system includes:

[0041] The automatic transfer switch function verification module 4 is provided with a conditional OR function block, an invert function block A, and a switch function block B connected in sequence. The inputs of the conditional OR function block include the automatic transfer switch action signal 101, the incoming line switch protection action signal 102, and the tie switch protection action signal 103. It is used to output an automatic transfer switch function enable signal when there is no automatic transfer switch action signal 101, the incoming line switch protection action signal 102, and the tie switch protection action signal 103.

[0042] The automatic transfer switch disconnection incoming line switch module 5 is equipped with a conditional AND function block and a first delay function block H connected in sequence. After the condition of the conditional AND function block is met, the first delay function block H generates an incoming line switch disconnection drive signal. The input connections of the conditional AND function block are:

[0043] The first voltage constraint function block C, whose input is the voltage value signal 104 of the first low-voltage bus;

[0044] Current constraint function block D, the input of which is the current value signal 105 of the incoming switch;

[0045] The closing constraint condition function block E has the incoming line switch position signal 106 as its input.

[0046] The input of the tripping constraint function block F is the tripping position signal 107 of the tie switch.

[0047] And the automatic transfer switch function allows the input signal;

[0048] The automatic transfer switch closing module 6 includes a condition AND module and a second voltage constraint condition function block G, which outputs an automatic transfer action signal 101 after the condition of the condition AND module is met, which drives the tie switch to close. The input of the second voltage constraint condition function block G is the standby bus voltage value signal 108. The input of the condition AND module includes the output of the second voltage constraint condition function block G and the incoming line switch disconnect drive signal.

[0049] Specifically, the backup automatic transfer function verification module 4 implements signal confirmation for the following three points:

[0050] 1. The incoming line switch protection has no operating signal;

[0051] 2. The interconnecting switch protection has no activation signal;

[0052] 3. No feedback when the automatic transfer switch is closed (automatic transfer switch closed).

[0053] The automatic transfer switch verification module 4 ensures that the automatic transfer switch function is allowed to be activated, excluding the possibility that the incoming line switch and tie switch themselves are in a faulty state.

[0054] Optionally, in the automatic transfer switch module 5, the first voltage constraint condition function block is used to set a constraint condition on the input voltage value signal 104 of the first low-voltage bus, such that the voltage is less than 50% of the rated voltage.

[0055] The current constraint function block is used to set a constraint condition that the current value signal 105 of the input switch is less than 6A.

[0056] The first delay function block H is used to set a 5-second delay. When the busbar is in an abnormal state, the automatic transfer switch module 5 is not immediately activated to disconnect the incoming line switch. There is a 5-second delay to allow the protection to clear the fault, avoid the impact of large load startup, avoid electromagnetic interference from the power cable, etc., until it is confirmed that the abnormal state of the busbar is so severe that it cannot be restored on its own.

[0057] Essentially, after confirming the following signals, the automatic transfer switch disconnection module 5 generates an incoming switch disconnection drive signal after a 1-second delay:

[0058] 1. Automatic input function verification module 4 actions (automatic input interlocking system);

[0059] 2. The bus voltage is lower than 50% of the rated voltage.

[0060] 3. The incoming line switch current is less than 6A;

[0061] 4. Incoming line switch closing position;

[0062] 5. Open position of the connecting switch.

[0063] The automatic transfer switch disconnection module 5 ensures that the switch has been opened when the automatic transfer switch is activated, preventing voltage collisions from different source switches. Its constraints are: low bus voltage, no current in the incoming switch, and the incoming switch being in the closed position and the tie switch being in the open position before the automatic transfer switch disconnection module 5 is activated.

[0064] Optionally, in the standby automatic switching switch module 6, the second voltage constraint function block is used to set a constraint condition on the input standby bus voltage value signal 108 such that the voltage is greater than 80% of the rated voltage.

[0065] Preferably, the system includes a second delay function block I, which is used to input the automatic transfer action signal 101 output by the automatic transfer closing contact switch module 6 after delay into the condition or function block OR of the automatic transfer function verification module 4.

[0066] The second delay function block is used to set a 1-second delay.

[0067] The automatic transfer switch module 6 can only be started once. After a 1-second delay to ensure successful start, a signal 101 is sent to the automatic transfer function verification module 4 to deactivate the automatic transfer function.

[0068] Essentially, after the automatic transfer switch closing tie switch module 6 confirms the following signal, it generates an incoming line switch disconnect drive signal and transmits it to the input terminal of the condition or function block of the automatic transfer switch function verification module 4 after a 5-second delay:

[0069] 1. The backup automatic transfer disconnect incoming line switch module 5 is activated (backup automatic transfer disconnect incoming line switch);

[0070] 2. The standby bus voltage is greater than 80% Un (rated voltage).

[0071] The automatic switching module 6 achieves the ultimate goal of automatically and quickly closing the tie switch, subject to the condition that the backup bus voltage is normal.

[0072] Preferably, the automatic control system for the low-voltage busbar backup automatic transfer in the power plant is integrated into the control system software within the controller.

[0073] The preferred embodiments of the present invention have been described in detail above. It should be understood that those skilled in the art can make numerous modifications and variations based on the concept of the present invention without creative effort. Therefore, all technical solutions that can be obtained by those skilled in the art based on the concept of the present invention through logical analysis, reasoning, or limited experimentation on the basis of existing technology should be within the scope of protection defined by the claims.

Claims

1. An automatic control system for the standby automatic transfer switch of a low-voltage busbar in a power plant, used to control the primary circuit of the low-voltage busbar in a power plant, the primary circuit including a first low-voltage busbar equipped with an incoming line switch (1), a second low-voltage busbar equipped with a standby busbar incoming line switch (2), and a connecting switch (3) connecting the first low-voltage busbar and the second low-voltage busbar respectively, characterized in that, The system includes: The automatic transfer function verification module (4) is provided with a condition or function block, an invert function block and a switch function block connected in sequence. The input of the condition or function block includes an automatic transfer action signal (101), an incoming line switch protection action signal (102) and a tie switch protection action signal (103). It is used to output an automatic transfer function enable signal when there is no automatic transfer action signal (101), an incoming line switch protection action signal (102) and a tie switch protection action signal (103). The automatic transfer switch disconnection incoming line switch module (5) is provided with a conditional and concurrent function block and a first delay function block connected in sequence. After the condition of the conditional and concurrent function block is met, the first delay function block generates an incoming line switch disconnection drive signal. The input connections of the conditional and concurrent function block are: The first voltage constraint function block, the input of which is the voltage value signal (104) of the first low-voltage bus; The current constraint condition function block is input to the current value signal of the incoming switch (105). The closing constraint condition function block is input to the incoming switch position signal (106). The input of the tripping constraint condition function block is the tripping position signal of the tie switch (107); And the automatic transfer switch function allows the input signal; The automatic transfer switch closing module (6) includes a conditional module and a second voltage constraint condition function block, which outputs an automatic transfer action signal (101) after the condition of the conditional module is met, which drives the tie switch to close. The input of the second voltage constraint condition function block is the standby bus voltage value signal (108). The input of the conditional module includes the output of the second voltage constraint condition function block and the incoming line switch disconnect drive signal.

2. The automatic control system for low-voltage busbar backup automatic transfer in a power plant according to claim 1, characterized in that, The first voltage constraint function block is used to set a constraint condition for the voltage value signal (104) of the input first low-voltage bus that is less than 50% of the rated voltage.

3. The automatic control system for low-voltage busbar backup automatic transfer in a power plant according to claim 1, characterized in that, The current constraint function block is used to set a constraint condition that the current value signal (105) of the input line switch is less than 6A.

4. The automatic control system for low-voltage busbar backup automatic transfer in a power plant according to claim 1, characterized in that, The second voltage constraint function block is used to set a constraint condition on the input standby bus voltage value signal (108) such that the voltage is greater than 80% of the rated voltage.

5. The automatic control system for low-voltage busbar backup automatic transfer in a power plant according to claim 1, characterized in that, The first delay function block is used to set a 5-second delay.

6. The automatic control system for low-voltage busbar backup automatic transfer in a power plant according to claim 1, characterized in that, The system includes a second delay function block, which is used to input the automatic transfer action signal (101) output by the automatic transfer switch closing contact switch module (6) into the automatic transfer function verification module (4) after delaying the signal.

7. The automatic control system for low-voltage busbar backup automatic transfer in a power plant according to claim 6, characterized in that, The second delay function block is used to set a 1-second delay.

8. The automatic control system for low-voltage busbar backup automatic transfer in a power plant according to claim 1, characterized in that, The first low-voltage busbar is connected to the first high-voltage busbar via the low-voltage transformer of the first power plant, and the second low-voltage busbar is connected to the second high-voltage busbar via the low-voltage transformer of the second power plant.

9. The automatic control system for low-voltage busbar backup automatic transfer in a power plant according to claim 1, characterized in that, The first low-voltage busbar and the second low-voltage busbar serve as backups for each other.

10. The automatic control system for low-voltage busbar backup automatic transfer in a power plant according to claim 1, characterized in that, The automatic control system for the low-voltage busbar backup in the power plant is integrated into the control system software within the controller.

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