Power distribution network on-line loop closing control method and system based on current limiting and time delay

Abstract

The invention discloses a current limiting and time delay-based power distribution network on-line loop closing control method and a current limiting and time delay-based power distribution network on-line loop closing control system. Traditional loop closing control usually adopts an off-line or experience-based method, load switching is carried out in a mode of switching off first and then switching on, power consumption loss can be caused, adverse effects can be generated, complexity and changes in operation of a power system cannot be dealt with under some conditions, and quick response to real-time state changes cannot be achieved. According to the on-line loop closing control method for the power distribution network, a target circuit breaker is controlled to act in time according to current limiting and time delay through a loop closing control module of the power distribution network, thermal switching is carried out on a power distribution line needing loop closing operation, a power station to be switched and a power station to be switched are switched in time, and a power grid deployment and maintenance instruction is completed. On-line loop closing of the power distribution network line is realized through the loop closing control module, the power supply reliability and stability of the power system are enhanced by adopting a non-power-cut thermal inverse loop closing mode, and the operation and maintenance work of the power system is more flexible.

Description

Technical Field

[0001] The invention belongs to the technical field of closed-loop control of distribution network lines, and relates to an online closed-loop control method and system for a distribution network based on current limiting and time delay. Background Art

[0002] In the power system, ensuring continuous and stable power supply is essential to maintain the normal operation of society and key industries. However, the power system may face problems such as equipment failure, maintenance operations, or unexpected events, which may cause partial or entire power network outages. In order to solve these problems and ensure the robustness of the power system, loop closing operation has become a common response strategy.

[0003] Traditional closed-loop control systems usually use offline or experience-based methods to reverse loads by first disconnecting and then closing, which causes power loss and produces adverse effects. In some cases, it is not enough to cope with the complexity and changes in power system operation and cannot achieve rapid response to real-time status changes. Summary of the invention

[0004] In view of the problems existing in the above-mentioned prior art, the present invention provides an online closing-loop control method and system for a distribution network based on current limiting and time delay, so as to make the closing-loop operation more precise and flexible, thereby enhancing the power supply reliability and stability of the power system and making the operation and maintenance of the power system more flexible.

[0005] To achieve the above object, the technical solution adopted by the present invention is: an online closed-loop control method for a distribution network based on current limiting and time delay, which comprises the steps of:

[0006] S1, constructing a distribution network closing control module, which adopts a line closing control strategy;

[0007] S2, controlling the target circuit breaker to operate according to the line closing control strategy;

[0008] S3, after the target circuit breaker completes the action, the distribution line realizes online hot-closed loop power regulation, and timely switches the power station to be switched on and off, completing the power grid adjustment and maintenance instructions.

[0009] The present invention uses the distribution network closing control module to control the target circuit breaker to act in time according to the current limiting and time delay, implements thermal switching on the distribution lines that need to be closed, and timely switches the power stations to be switched and the power stations to be switched, completing the grid adjustment and maintenance instructions. The present invention realizes the online closing of the distribution network line through the closing control module, and the non-stop hot-switching closing method adopted enhances the power supply reliability and stability of the power system, and the operation and maintenance of the power system is more flexible.

[0010] Furthermore, in step S1, the distribution network closing control module includes a current limiting control module and a time delay module.

[0011] Furthermore, the current limiting control module is specifically used for:

[0012] The effective value of the current at the closing point after the loop is closed is compared with the current limiting threshold. If the effective value of the current at the closing point is greater than the current limiting threshold, the target circuit breaker at the power station to be cut off is disconnected in time; if the effective value of the current at the closing point is less than or equal to the current limiting threshold, the target circuit breaker at the power station to be cut off is kept closed.

[0013] Furthermore, the specific calculation method of the effective value of the closing point current is shown in formula (1):

[0014]

[0015] Among them, ΔU is the voltage difference between the two ends of the loop closing point; U L1 is the voltage of the first line; U L2 is the voltage of the second line; Z L is the equivalent impedance of the closed-loop line; R L is the equivalent resistance of the closed-loop circuit; X L is the equivalent reactance of the closed-loop line; I L is the effective value of the current at the closing point; I M is the effective value of the impact current; k is the impact coefficient.

[0016] Furthermore, the effective value of the current after the two lines are closed is shown in formula (2):

[0017]

[0018] Among them, I1 is the effective value of the current before the first line is looped; I1' is the effective value of the current after the first line is looped; I2 is the effective value of the current before the second line is looped; I2' is the effective value of the current after the second line is looped.

[0019] Furthermore, the delay module is specifically used for:

[0020] When the two-loop line circuit breaker is closed, if the closing time exceeds the time delay threshold of the target circuit breaker, the target circuit breaker is disconnected in time; if the closing time does not reach the time delay threshold of the target circuit breaker, the target circuit breaker is kept closed.

[0021] Furthermore, in step S1, the line closing loop control strategy is as follows:

[0022] The closing-loop control module is controlled by the A_control switch. The ON / 0 state indicates that the closing-loop control module is running, and the OFF / 1 state indicates that the closing-loop control module is not enabled. When receiving an instruction to close the loop and adjust the power, the A_control switch is adjusted to the ON / 0 state, and the closing-loop control module is in the running mode. The line closing is completed according to the closing-loop line status determined by the current limiting control module and the time delay module.

[0023] Furthermore, in step S2, the specific contents of controlling the target circuit breaker action are as follows:

[0024] When the effective value of the closing point current after the loop is closed is greater than the current limiting threshold, the current limiting control module issues a target circuit breaker disconnection instruction; when the effective value of the closing point current after the loop is closed is less than or equal to the current limiting threshold, the current limiting control module does not take action until the closing time of the closing line tie circuit breaker reaches the delay threshold, and the delay module issues a target circuit breaker disconnection instruction; when any module issues a disconnection instruction, that is, S1=1 or S2=1, the target circuit breaker is disconnected immediately, and the power station to be disconnected is out of operation;

[0025]

[0026] Among them, S1 is the logic value of the current limiting module, 1 means the circuit breaker is open, and 0 means it is closed; I L is the effective value of the current at the closing point; I L_set is the current limiting threshold; S2 is the logic value of the delay module, 1 means the circuit breaker is open, 0 means it is closed; T L is the delay time; T L_set The delay threshold.

[0027] Furthermore, the details of step S3 are as follows:

[0028] After the closing control device completes the control of the target circuit breaker, the target circuit breaker is disconnected, the power station to be cut off is shut down, the connecting circuit breaker of the two lines of the closing loop remains closed, and the power station to be put into operation supplies power to the closing line, and the closing hot reversal operation is completed.

[0029] The present invention also provides a distribution network online closed-loop control system based on current limiting and time delay, which comprises:

[0030] A closed-loop control module construction unit: constructs a distribution network closed-loop control module, which adopts a line closed-loop control strategy;

[0031] Target circuit breaker control unit: controls the action of the target circuit breaker according to the line closing control strategy;

[0032] Online thermal reversing loop power regulation implementation unit: After the target circuit breaker completes the action, the distribution line realizes online thermal reversing loop power regulation.

[0033] Compared with the prior art, the present invention has the following beneficial effects: the present invention realizes online closing of distribution network lines through the closing control module, and the hot-reversing closing method without power outage increases the power supply reliability and stability of the power system, making the operation and maintenance of the power system more flexible. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, for ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0035] Figure 1 It is a flow chart of a method for online closed-loop control of a distribution network based on current limiting and time delay of the present invention;

[0036] Figure 2 It is a topological schematic diagram of the closed-loop circuit model of the present invention;

[0037] Figure 3 is a schematic diagram of a closed-loop control module in an embodiment of the present invention;

[0038] Figure 4 is a simulation result diagram of a signal emitted by a closed-loop control module in an embodiment of the present invention;

[0039] Figure 5 1 is a diagram showing the simulation result of the effective value of the current at the closing point using the closing-loop control module in an embodiment of the present invention;

[0040] Figure 6 is a diagram of the simulation result of the signal sent in the embodiment of the present invention without using the closed-loop control module;

[0041] Figure 7 is a simulation result diagram of the effective value of the current at the closing point in the embodiment of the present invention without using the closing-loop control module;

[0042] Figure 8 It is a composition diagram of an online closed-loop control system for a distribution network based on current limiting and time delay of the present invention;

[0043] Figure 3 In the example, A_control is the closed-loop control switch, I n2 is the closing current, RMS is the current effective value module, TIME is the delay time setting module, BRK1 is the circuit breaker control signal, and Logic Breaker Timed is the line closing time control module. DETAILED DESCRIPTION

[0044] The following will be combined with the drawings in the specification of the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. 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.

[0045] Example 1

[0046] This embodiment provides a distribution network online closed-loop control method based on current limiting and time delay, such as Figure 1 As shown, it includes the steps of:

[0047] S1, constructing a distribution network closing control module, which adopts a line closing control strategy;

[0048] S2, controlling the target circuit breaker to operate according to the line closing control strategy;

[0049] S3, after the target circuit breaker completes the action, the distribution line realizes online hot-closed loop power regulation, and timely switches the power station to be switched on and off, completing the power grid adjustment and maintenance instructions.

[0050] In step S1, the distribution network closing control module includes a current limiting control module and a time delay module.

[0051] The current limiting control module is specifically used for:

[0052] The effective value of the closing point current after the loop is closed is compared with the current limiting threshold. The specific calculation method of the effective value of the closing point current is shown in formula (1). If the effective value of the closing point current is greater than the current limiting threshold, it indicates that the impact current is large and the target circuit breaker at the power station to be cut is disconnected in time; if the effective value of the closing point current is less than or equal to the current limiting threshold, the target circuit breaker at the power station to be cut is less impacted and does not meet the disconnection standard and remains closed. The effective value of the current after the two lines are closed is shown in formula (2).

[0053]

[0054] Among them, ΔU is the voltage difference between the two ends of the loop closing point; U L1 is the voltage of the first line; U L2 is the voltage of the second line; Z L is the equivalent impedance of the closed-loop line; R L is the equivalent resistance of the closed-loop circuit; X L is the equivalent reactance of the closed-loop line; I L is the effective value of the current at the closing point; I Mis the effective value of the impact current; k is the impact coefficient, which is 1.8-1.9; I1 is the effective value of the current before the first line is closed; I1' is the effective value of the current after the first line is closed; I2 is the effective value of the current before the second line is closed; I2' is the effective value of the current after the second line is closed.

[0055] The delay module is specifically used for:

[0056] When the two-loop line connecting circuit breaker is closed, if the closing time exceeds the time delay threshold of the target circuit breaker, the target circuit breaker is disconnected in time; if the closing time does not reach the time delay threshold of the target circuit breaker, the target circuit breaker remains closed.

[0057] In step S1, the line closing loop control strategy is as follows:

[0058] The closing-loop control module is controlled by the A_control switch. The ON / 0 state indicates that the closing-loop control module is running, and the OFF / 1 state indicates that the closing-loop control module is not enabled. When receiving an instruction to close the loop and adjust the power, the A_control switch is adjusted to the ON / 0 state, and the closing-loop control module is in the running mode. The line closing is completed according to the closing-loop line status determined by the current limiting control module and the time delay module.

[0059] In step S2, the specific contents of controlling the target circuit breaker action are as follows:

[0060] When the effective value of the closing point current after the loop is closed is greater than the current limiting threshold, the current limiting control module issues a target circuit breaker disconnection instruction; when the effective value of the closing point current after the loop is closed is less than or equal to the current limiting threshold, the current limiting control module does not take action until the closing time of the closing line contact circuit breaker reaches the delay threshold, and the delay module issues a target circuit breaker disconnection instruction. When any module issues a disconnection instruction, that is, S1=1 or S2=1, the target circuit breaker is disconnected immediately, and the power station to be disconnected is out of operation.

[0061]

[0062] Among them, S1 is the logic value of the current limiting module, 1 means the circuit breaker is open, and 0 means it is closed; I L is the effective value of the current at the closing point; I L_set is the current limiting threshold; S2 is the logic value of the delay module, 1 means the circuit breaker is open, 0 means it is closed; T L is the delay time; T L_set The delay threshold.

[0063] The specific contents of step S3 are as follows: after the closing loop control device completes the control of the target circuit breaker, the target circuit breaker is disconnected, the power station to be cut off is shut down, the connecting circuit breaker of the two lines of the closing loop remains closed, the power station to be put into operation supplies power to the closing loop line, and the closing loop hot reversal operation is completed.

[0064] Application Examples

[0065] This application example is based on the method described in Example 1. The closed-loop line model topology built in the PSCAD simulation software is as follows: Figure 2 As shown in Figure 1, the closed-loop line model includes two lines, which are composed of an external power grid, a transformer, a line load, a power station to be cut off, a power station to be put into operation, and a closed-loop switch. The closed-loop control module built in PSCAD is as follows: Figure 3 As shown in the figure, the closing control module can be controlled by toggling the A_control switch. ON / 0 represents the operation of the closing control module. It is used for closing the distribution network line. The relevant parameters are set to per-unit values ​​for calculation. The simulation time is set to 2s. The closing command is received at 1s, and the contact circuit breaker is closed. The delay threshold is set to 0.2s and the current limit threshold is set to 0.0028. The comparison diagrams of closing the loop using the closing control module and not using the closing control module are shown in the figure below. Figure 4-5 , Figure 6-7 As shown in Figure 2. control is the logic signal sent by the control module, 0 means the circuit breaker is closed, and 1 means the circuit breaker is open.

[0066] In the simulation using the closing-loop control module, after receiving the closing-loop instruction, the target circuit breaker is immediately disconnected when overcurrent is detected, causing a smaller impact and a shorter duration. The closing process is completed in 1.02s. In the simulation without the closing-loop control module, after receiving the closing-loop instruction, the target circuit breaker is not disconnected in time when overcurrent is detected. The target circuit breaker can only be disconnected after the delay is reached. The closing process ends at 1.2s. At this time, the impact current lasts for a period of time and has a greater impact.

[0067] In summary, this application example confirms the feasibility of the online closed-loop control method of the distribution network based on current limiting and time delay of the present invention. The closed-loop control module can timely control the rapid disconnection of the power station to be cut off, and ensure the continuous power supply of the distribution network through the hot inverted loop, which has little impact on the distribution system.

[0068] Example 2

[0069] This embodiment provides a distribution network online closed-loop control system based on current limiting and time delay, which is used to implement the distribution network online closed-loop control method described in Example 1. Figure 8 As shown, it includes:

[0070] A closed-loop control module construction unit: constructs a distribution network closed-loop control module, which adopts a line closed-loop control strategy;

[0071] Target circuit breaker control unit: controls the action of the target circuit breaker according to the line closing control strategy;

[0072] Online hot-loop switching power regulation implementation unit: After the target circuit breaker completes the action, the distribution line realizes online hot-loop switching power regulation, and timely switches the power stations to be switched on and off, completing the power grid adjustment and maintenance instructions.

[0073] It should be noted that each unit in the above-mentioned online closed-loop control system of a distribution network based on current limiting and time delay can be fully or partially implemented by software, hardware and a combination thereof. The above-mentioned units can be embedded in or independent of the processor in the computer device in the form of hardware, or can be stored in the memory of the computer device in the form of software, so that the processor can call and execute the operations corresponding to the above-mentioned units. For the specific definition of an online closed-loop control system of a distribution network based on current limiting and time delay, please refer to the definition of an online closed-loop control method of a distribution network based on current limiting and time delay (i.e., Example 1) above. The two have the same functions and effects, which will not be repeated here.

[0074] The above disclosure is only the preferred embodiment of the present invention, showing and describing the basic principle, main features and advantages of the present invention. However, the present invention is not limited thereto, and any transformation and changes made by any technician in the field without creative work and without departing from the principle of the present invention should fall within the protection scope of the present invention. The protection scope of the present invention is defined by the attached claims and their equivalents.

Claims

1. A distribution network online closed-loop control method based on current limiting and time delay, characterized in that: Includes steps: S1, constructing a distribution network closing control module, which adopts a line closing control strategy; S2, controlling the target circuit breaker to operate according to the line closing control strategy; S3, after the target circuit breaker completes the action, the distribution line realizes online hot-closed loop power regulation, and timely switches the power station to be switched on and off, completing the power grid adjustment and maintenance instructions.

2. The online closed-loop control method for a distribution network according to claim 1, characterized in that: In step S1, the distribution network closing control module includes a current limiting control module and a time delay module.

3. The online closed-loop control method for a distribution network according to claim 2, characterized in that: The current limiting control module is specifically used for: The effective value of the current at the closing point after the loop is closed is compared with the current limiting threshold. If the effective value of the current at the closing point is greater than the current limiting threshold, the target circuit breaker at the power station to be cut off is disconnected in time; If the effective value of the current at the closing point is less than or equal to the current limiting threshold, the target circuit breaker at the power station to be cut off is kept closed.

4. The online closed-loop control method for a distribution network according to claim 3, characterized in that: The specific calculation method of the effective value of the closing point current is shown in formula (1): Among them, ΔU is the voltage difference between the two ends of the loop closing point; U L1 is the voltage of the first line; U L2 is the voltage of the second line; Z L is the equivalent impedance of the closed-loop line; R L is the equivalent resistance of the closed-loop circuit; X L is the equivalent reactance of the closed-loop line; I L is the effective value of the current at the closing point; I M is the effective value of the impact current; k is the impact coefficient.

5. The online closed-loop control method for a distribution network according to claim 4, characterized in that: The effective value of the current after the two lines are closed is shown in formula (2): Among them, I1 is the effective value of the current before the first line is looped; I1' is the effective value of the current after the first line is looped; I2 is the effective value of the current before the second line is looped; I2' is the effective value of the current after the second line is looped.

6. The online closed-loop control method for a distribution network according to claim 2, characterized in that: The delay module is specifically used for: When the two-loop line circuit breaker is closed, if the closing time exceeds the time delay threshold of the target circuit breaker, the target circuit breaker is disconnected in time; if the closing time does not reach the time delay threshold of the target circuit breaker, the target circuit breaker is kept closed.

7. The online closed-loop control method for a distribution network according to claim 1, characterized in that: In step S1, the line closing loop control strategy is as follows: The closing-loop control module is controlled by the A_control switch. The ON / 0 state indicates that the closing-loop control module is running, and the OFF / 1 state indicates that the closing-loop control module is not enabled. When receiving an instruction to close the loop and adjust the power, the A_control switch is adjusted to the ON / 0 state, and the closing-loop control module is in the running mode. The line closing is completed according to the closing-loop line status determined by the current limiting control module and the time delay module.

8. The online closed-loop control method for a distribution network according to claim 1, characterized in that: In step S2, the specific contents of controlling the target circuit breaker action are as follows: When the effective value of the closing point current after the loop is closed is greater than the current limiting threshold, the current limiting control module issues a target circuit breaker disconnection instruction; when the effective value of the closing point current after the loop is closed is less than or equal to the current limiting threshold, the current limiting control module does not take action until the closing time of the closing line tie circuit breaker reaches the delay threshold, and the delay module issues a target circuit breaker disconnection instruction; when any module issues a disconnection instruction, that is, S1=1 or S2=1, the target circuit breaker is disconnected immediately, and the power station to be disconnected is out of operation; Among them, S1 is the logic value of the current limiting module, 1 means the circuit breaker is open, and 0 means it is closed; I L is the effective value of the current at the closing point; I L_set is the current limiting threshold; S2 is the logic value of the delay module, 1 means the circuit breaker is open, 0 means it is closed; T L is the delay time; T L_set The delay threshold.

9. The online closed-loop control method for a distribution network according to claim 1, characterized in that: The details of step S3 are as follows: After the closing control device completes the control of the target circuit breaker, the target circuit breaker is disconnected, the power station to be cut off is shut down, the connecting circuit breaker of the two lines of the closing loop remains closed, and the power station to be put into operation supplies power to the closing line, and the closing hot reversal operation is completed.

10. A distribution network online closed-loop control system based on current limiting and time delay, used to implement the distribution network online closed-loop control method according to any one of claims 1 to 9, characterized in that: include: A closed-loop control module construction unit: constructs a distribution network closed-loop control module, which adopts a line closed-loop control strategy; Target circuit breaker control unit: controls the action of the target circuit breaker according to the line closing control strategy; Online hot-loop switching power regulation implementation unit: After the target circuit breaker completes the action, the distribution line realizes online hot-loop switching power regulation, and timely switches the power stations to be switched on and off, completing the power grid adjustment and maintenance instructions.

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