A control method and system for suppressing shore power magnetizing inrush, a terminal and a medium

Abstract

The application discloses a kind of control method, system, terminal and medium of inhibiting shore power excitation inrush, relate to ship shore power control technology technical field, solve the problem that existing technology carries out the switching of inrush suppression cabinet circuit breaker, staff operation difficulty is big, system adaptability is poor, its technical scheme main point is: a kind of control method of inhibiting shore power excitation inrush, by detecting the mutation of instantaneous value of shore side shore power supply output current, identify the closing operation of ship side input switch, then by closing delay counter delay a certain time, inrush suppression circuit breaker is closed, bypass inrush suppression resistance, reach the purpose that inrush suppression cabinet circuit breaker is closed by shore side shore power supply automatically under the condition that there is no communication between ship shore, simultaneously, by closing delay counter delay timing, reach the purpose that inrush suppression circuit breaker closing time is controlled, reduce the probability of suppression resistance burnout.

Description

Technical Field

[0001] This invention relates to the field of shore power control technology, and more specifically, to a control method, system, terminal, and medium for suppressing shore power excitation inrush current. Background Technology

[0002] Shore power technology uses the port power grid as its power source and is divided into shore-side shore power and ship-side shore power. Shore-side shore power is mainly responsible for generating a stable voltage source and outputting stable power; ship-side shore power is mainly responsible for the synchronization and grid connection between ship and shore, ensuring a stable power supply when ship and shore are connected to the grid, and preventing power outages.

[0003] For shore power systems using a high-voltage onboard method, a stable high-voltage power supply is mainly output from the shore power source. This power is then transmitted to the receiving port on the ship via the ship-to-shore connection system. From there, it is connected to the ship's power system via a step-down transformer. Simultaneously, an inrush current suppression cabinet is installed at the output end of the shore power source. This cabinet consists of an inrush current suppression resistor and a circuit breaker connected in parallel. Before the ship-side step-down transformer is closed, the circuit breaker is tripped, and the inrush current is suppressed by the inrush current suppression resistor within the allowable current range of the shore power source. After the ship-side step-down transformer is closed, the circuit breaker is closed again, bypassing the inrush current suppression resistor, allowing the shore power system to operate normally.

[0004] In the aforementioned process, the opening and closing of the inrush suppression cabinet circuit breaker can only be performed when there is communication between the ship and the shore. If communication cables are used to notify the shore side for automatic opening and closing, both the shore power supply on the shore side and the shore power supply on the ship side must have this function, and the systems must be compatible for successful operation. However, many times foreign ships dock, using non-standard communication protocols, making it impossible to adapt to each ship individually, thus leading to inapplicability. Furthermore, if ship and shore personnel communicate via walkie-talkies and manually open and close the circuit breaker, it increases the operational difficulty for staff and carries the risk of misoperation, language barriers, and other risks. Moreover, the timing of closing the inrush suppression cabinet circuit breaker is critical; it is necessary to determine when to activate the ship-side step-down transformer. Closing cannot be performed before activation, otherwise the inrush suppression effect will not be achieved. It is also necessary to determine when to begin closing; if closing is too late, the ship side has already started to carry the load, and most of the load current will pass through the inrush suppression resistor, causing it to burn out. Therefore, how to automatically control high-voltage shore power inrush suppression under conditions without ship-shore communication is an urgent problem to be solved. Summary of the Invention

[0005] The purpose of this invention is to provide a control method, system, terminal, and medium for suppressing shore power inrush current. By detecting sudden changes in the instantaneous value of the shore power output current, the closing operation of the ship-side input switch is identified. After a certain delay by a closing delay counter, the inrush current suppression circuit breaker is closed, bypassing the inrush current suppression resistor. This achieves the goal of automatically completing the closing operation of the inrush current suppression cabinet circuit breaker by the shore power supply when there is no communication between the ship and the shore. At the same time, the closing delay counter is used to control the closing time of the inrush current suppression circuit breaker, thereby reducing the probability of the suppression resistor burning out.

[0006] The above-mentioned technical objective of the present invention is achieved through the following technical solution:

[0007] A control method for suppressing shore power inrush current includes the following steps:

[0008] S1. Detect the status of the high-voltage output switch in the shore power supply. If the high-voltage output switch is in the closed state, execute S2.

[0009] S2. Detect the status of the circuit breaker in the inrush current suppression cabinet. If the circuit breaker is in the open state, execute S3.

[0010] S3. Obtain the current state of the closing delay counter. If the current state of the closing delay counter satisfies the first state, execute S4; if the current state of the closing delay counter satisfies the second state, execute S5.

[0011] S4. Collect the instantaneous value of the output current of the shore power source. If the instantaneous value of the output current of the shore power source is greater than the first preset current value, execute S5.

[0012] S5. The closing delay counter continues to count at a preset frequency until the count value of the closing delay counter is greater than the preset value, and then closes the inrush current suppression cabinet circuit breaker.

[0013] Furthermore, if the instantaneous value of the output current of the shore power supply on the shore side is not greater than the first preset current value;

[0014] Then, the effective value of the output current of the shore power source is collected, and when the effective value of the output current of the shore power source is greater than the second preset current value, S5 is executed.

[0015] Furthermore, the first preset current value is obtained based on the current coefficient, the shore power supply capacity, and the rated output voltage of the shore power supply.

[0016] Furthermore, the current coefficient is obtained based on the rated load and minimum load of the shipside shore power supply.

[0017] Furthermore, the current coefficient is not greater than the ratio of the minimum load to the rated load of the shore power supply on the ship side.

[0018] Furthermore, the shore power capacity is the minimum shore power capacity when the shore power system is operating in a high-voltage onboard mode.

[0019] Furthermore, the first state is that there is a count value on the closing delay counter;

[0020] The second state is when there is no count value on the closing delay counter.

[0021] A control system for suppressing shore power inrush current includes:

[0022] The first execution module is used to execute S1, which detects the status of the high-voltage output switch in the shore power supply.

[0023] The second execution module is used to execute S2, which detects the status of the inrush current suppression cabinet circuit breaker when the high-voltage output switch is in the closed state.

[0024] The third execution module is used to execute S3, which obtains the current state of the closing delay counter when the circuit breaker is in the open state;

[0025] The fourth execution module is used to execute S4, which, if the current state of the closing delay counter satisfies the first state, collects the instantaneous value of the output current of the shore power supply on the shore side.

[0026] The fifth execution module is used to execute S5, when the current state of the closing delay counter satisfies the second state.

[0027] Alternatively, when the instantaneous value of the output current of the shore power supply on the shore side is greater than the first preset current value, the closing delay counter continues to count at a preset frequency until the count value of the closing delay counter is greater than the preset value, and the inrush current suppression cabinet circuit breaker is closed.

[0028] An electronic terminal includes: a memory for storing a computer program; and a processor for executing the computer program stored in the memory to cause the electronic terminal to perform the control method for suppressing shore power inrush current.

[0029] A computer-readable storage medium storing a computer program that, when executed by a processor, implements the aforementioned control method for suppressing shore power inrush current.

[0030] Compared with the prior art, the present invention has the following beneficial effects:

[0031] A control method for suppressing shore power inrush current involves detecting sudden changes in the instantaneous value of the shore power supply output current to identify the closing operation of the ship-side input switch. After a certain delay using a closing delay counter, the inrush current suppression circuit breaker is closed, bypassing the inrush current suppression resistor. This achieves the goal of automatically closing the circuit breaker of the inrush current suppression cabinet by the shore power supply when there is no communication between the ship and the shore. Simultaneously, the closing delay counter is used to control the closing time of the inrush current suppression circuit breaker, thereby reducing the probability of the suppression resistor burning out. Attached Figure Description

[0032] The accompanying drawings, which are included to provide a further understanding of embodiments of the invention and form part of this application, do not constitute a limitation thereof. In the drawings:

[0033] Figure 1 This is a schematic diagram of the flow structure of a control method for suppressing shore power excitation inrush current in this embodiment;

[0034] Figure 2 This is a schematic diagram of a typical high-voltage shore power system provided in this embodiment. Detailed Implementation

[0035] To make the objectives, technical solutions, and advantages of the present invention clearer, the present invention will be further described in detail below with reference to the embodiments and accompanying drawings. The illustrative embodiments and descriptions of the present invention are only used to explain the present invention and are not intended to limit the present invention.

[0036] Furthermore, 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. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of this invention, "a plurality of" means two or more, unless otherwise explicitly specified.

[0037] Example: A control method, system, terminal, and medium for suppressing shore power inrush current.

[0038] A control method for suppressing shore power inrush current includes the following steps: S1. Detecting the status of the high-voltage output switch in the shore power supply. If the high-voltage output switch is in the closed state, execute S2; S2. Detecting the status of the circuit breaker in the inrush current suppression cabinet. If the circuit breaker is in the open state, execute S3; S3. Obtaining the current status of the closing delay counter. If the current status of the closing delay counter satisfies a first state, execute S4; if the current status of the closing delay counter satisfies a second state, execute S5; S4. Acquiring the instantaneous value of the shore power supply output current. If the instantaneous value of the shore power supply output current is greater than a first preset current value, execute S5; if the instantaneous value of the shore power supply output current is not greater than the first preset current value, then acquire the effective value of the shore power supply output current, and execute S5 when the effective value of the shore power supply output current is greater than a second preset current value; S5. The closing delay counter continues to count at a preset frequency until the count value of the closing delay counter is greater than the preset value, and then the circuit breaker in the inrush current suppression cabinet is closed. The first preset current value is obtained based on the current coefficient, the shore power supply capacity, and the rated output voltage of the shore power supply. The current coefficient is obtained based on the rated load and minimum load of the ship-side shore power supply. The current coefficient is not greater than the ratio of the minimum load to the rated load of the ship-side shore power supply. The shore power supply capacity is the minimum capacity of the shore power supply. The first state is that there is a count value on the closing delay counter; the second state is that there is no count value on the closing delay counter. The preset value is time, which depends on the actual transformer capacity. Usually, the time is 1 second. Assuming a counting frequency of 5000Hz, the preset value should be set to 5000, but different transformer capacities need to be dynamically adjusted as needed. However, the maximum time should not exceed 10 seconds. The preset frequency is the frequency for detecting whether the current is overcurrent, and it needs to meet the time requirement of quickly detecting whether the instantaneous current value exceeds the threshold. The shore power system mainly operates in two frequency bands: 50Hz and 60Hz. Therefore, the preset frequency should be much larger than the two frequencies, preferably 50 to 100 times, that is, the frequency can be between 3000Hz and 6000Hz.

[0039] like Figure 2This is a typical high-voltage shore power system. The solid line represents the shore power supply section, which mainly draws power from the shore 6kV / 10kV grid via the incoming switch load. It includes a phase-shifting transformer, power unit cabinet, filter, inrush current suppression cabinet, isolation transformer, high-voltage output switch, and high-voltage shore power junction box. The dashed line represents the ship-side shore power supply section, which mainly includes the ship-side input switch, ship-side step-down transformer, ship-side shore power system, and the ship's diesel generator set and electrical equipment. When the entire shore power system is operating, the shore power supply starts by keeping the inrush current suppression circuit breaker open, and then closing the high-voltage output switch. At this time, the shore power supply is input to the upper port of the ship-side input switch. After the ship-side personnel check that the phase sequence, voltage, and frequency are correct, they control the input switch to close. This will generate an excitation inrush current impact on the shore power supply. After the input switch closes, the ship-side shore power supply automatically synchronizes with the grid and transfers the load. After the load transfer is completed, the diesel generator is disconnected, completing the process of converting diesel power to shore power.

[0040] Before the ship-side input switch is closed, the output current of the shore power supply is a relatively small value near zero. At the instant the ship-side input switch is closed, the shore power supply magnetizes the ship-side step-down transformer, generating a momentary inrush current. This current is limited to the rated current range by the inrush current suppression resistor and only lasts for half a cycle of the output voltage frequency, a very short time. However, compared to the small current before closing, this is a significant change, and under normal system conditions, this inrush current can only be generated due to the magnetization of the ship-side step-down transformer. Therefore, this embodiment provides a control method for suppressing shore power inrush current. By detecting sudden changes in the instantaneous value of the shore power supply output current, it identifies the closing operation of the ship-side input switch. After a certain delay using a closing delay counter, it closes the inrush current suppression circuit breaker, bypassing the inrush current suppression resistor. Furthermore, if no sudden change in the instantaneous value of the shore power supply output current is detected, the effective value of the shore power supply output current is monitored. Once the effective value reaches a certain threshold, the inrush current suppression circuit breaker is also closed, bypassing the inrush current suppression resistor. This achieves the goal of automatically closing the inrush current suppression cabinet circuit breaker using the shore power supply when there is no ship-shore communication. Simultaneously, the closing delay counter controls the closing time of the inrush current suppression circuit breaker, reducing the probability of the suppression resistor burning out.

[0041] Specifically: Step 1: Check if the high-voltage output switch is closed. If closed, proceed to Step 2; if not closed, it means the shore power supply has not yet been output to the ship, and no action is required. Step 2: Check if the inrush current suppression circuit breaker is in the open state. If open, proceed to Step 3; if not, it means the shore power inrush current suppression circuit breaker is closed, and no action is required. Step 3: Check if the closing delay counter has a value. If not, proceed to Step 4; if a value is present, it means the closing delay counting has started, proceed directly to Step 6 to continue counting. Step 4: Sample the instantaneous value of the shore power supply output current. Step 5: Detect whether the instantaneous value of the shore power supply output current is greater than the threshold th1. If greater than th1, proceed to Step 6; otherwise, detect whether the effective value of the shore power supply output current is greater than the threshold th2. If greater than th2, proceed to Step 6. Step 6: Delay counting, the counting frequency is 5000Hz, increment by 1 for each entry; Step 7: Check if the delay count value is greater than the threshold time. If it is greater than time, proceed to the next step; otherwise, end the function processing directly; Step 8: Close the inrush current suppression circuit breaker, and then end the function processing.

[0042] The selection of the first preset current value (the instantaneous threshold value th1 of the output current) is based on the following points:

[0043] (1) According to the standards GB / T 51305, JTS 155, IEC / IEEE 8005, etc., for shore power systems with a capacity greater than 630kVA, it is advisable to use the high-voltage shipboard power supply method. That is, the minimum capacity of a shore power system using the high-voltage shipboard power supply method is 630kVA.

[0044] (2) According to the design method of the inrush current suppression resistor, the rated current is calculated after the shore power supply output voltage is fully applied across the inrush current suppression resistor. That is, the maximum current flowing through the system at the instant the ship-side step-down transformer is closed is the rated current of the shore power system.

[0045] (3) For shore power systems, the minimum load on the shipside foundation is approximately 20% of the rated load. That is, when the shore power supply is fully operational and operating with the shipside load, the minimum load current is approximately 20% of the rated current.

[0046] Therefore, the instantaneous current threshold th1 can be calculated based on a 630kVA shore power system. The maximum peak current flowing through the inrush current suppression resistor is calculated, and then multiplied by a current coefficient of 10%–20% to obtain the instantaneous current threshold th1. The calculation method for th1 is as follows: th1 = 630000 / 1.732 / Un*1.414*15% (where Un is the rated output voltage of the shore power system). Because th1 is calculated using a high-voltage shore power system with the minimum capacity, other shore power capacities can only be larger than this value. Therefore, this threshold is easily achievable, making th1 applicable to shore power systems of any capacity. Simultaneously, the instantaneous current threshold th1 considers the case of the lowest load on the ship side. When the inrush current is not successfully identified, the system will operate with the lowest load for a very short time. However, this threshold, set below the lowest load current, can still identify the load and close the inrush current suppression circuit breaker, preventing the inrush current suppression resistor from burning out.

[0047] The selection of the second preset current value (the effective value threshold th2 of the output current) is mainly based on the following two points:

[0048] (1) Under normal circumstances, the power of the inrush current suppression resistor R under long-term load is 1 / 3 of the rated power P.

[0049] (2) The main purpose of current effective value detection is to prevent the inrush current suppression circuit breaker from being closed when no inrush current is detected, which would cause the inrush current suppression resistor to continue to operate in the main circuit.

[0050] Based on the above two points, the effective current detection threshold can be set to the maximum current value that the inrush current suppression resistor can withstand for extended periods of operation. The calculation method is as follows:

[0051] th2=√(P / 3 / R)

[0052] The th2 calculated by this method can still effectively identify the loaded status of the shore power system by the change in the effective value even when no inrush current is detected. Since the effective value threshold is selected as the maximum value of the inrush current suppression resistor that can be operated under load for a long time, it can effectively ensure that the resistor will not be damaged.

[0053] The control method for suppressing shore power excitation inrush current provided in this embodiment has the following advantages: (1) The remaining steps are only executed when the shore-side high-voltage output circuit breaker is closed and the inrush current suppression circuit breaker is open, which can save a lot of program execution time. (2) The output instantaneous current magnitude is collected cyclically at a frequency of 5000Hz during high-speed interruption and judgment is made, which can quickly detect current changes. Taking the 50Hz grid frequency as an example, its half-cycle time is 10ms, but the current sampling time of this invention is 0.2ms, which can accurately and quickly identify the inrush current. (3) The instantaneous value threshold th1 of the output current is set based on the minimum shore power system capacity of the high-voltage onboard method. After the threshold is set, it can be applied to all ships using the high-voltage onboard method and will not be dynamically set due to changes in ship capacity. (4) The instantaneous value threshold th1 of the output current is set by multiplying the minimum shore power system capacity current in the high-voltage onboard mode by a certain current coefficient. This ensures that the inrush current suppression circuit breaker can still be closed after the shore power supply carries the minimum load on the ship side when no inrush current is detected, thus ensuring the safety of the inrush current suppression resistor. (5) The selection of the instantaneous value threshold th1 of the output current can also prevent false identification caused by interference from the sampling circuit, and prevent the inrush current suppression circuit breaker from closing prematurely. (7) Under the condition of no ship-shore communication, the shore power supply can automatically control the high-voltage shore power inrush current suppression circuit breaker to close. (6) The selection of the effective value threshold th2 of the output current can ensure that the shore power system can still be effectively identified by the change of the effective value when no inrush current is detected. Since the effective value threshold is selected as the maximum value that the inrush current suppression resistor can carry for a long time, it can effectively ensure that the resistor will not be damaged.

[0054] For example Figure 2The typical high-voltage shore power system shown operates using a high-voltage onboard method. First, the shore-side high-voltage junction box is reliably connected to the ship's input side via cable. The shore-side power system is then started normally. Once operational, shore-side personnel can remotely close the high-voltage output switch, at which point the shore-side power system outputs voltage to the ship's input switch. At this point, the shore-side power system enters a high-speed interruption, continuously executing the high-voltage shore power inrush current suppression logic control method function described in this invention under shipless shore communication. This execution is performed at a high frequency of 5000Hz, continuously sampling the instantaneous value of the shore-side power supply output current and comparing it with a threshold th1. Ship-side personnel confirm the input voltage, frequency, and phase sequence load requirements, and remotely manually close the ship's input switch. The input voltage then magnetizes the ship's step-down transformer. Under the action of the inrush current suppression resistor, the peak inrush current is controlled within the rated current range of the shore power supply output. At this time, the high-speed operation function of the shore power supply will detect the sudden change in current and determine that the instantaneous current value exceeds the threshold. After a certain delay, the inrush current suppression circuit breaker will be closed, bypassing the inrush current suppression resistor. After the ship-side personnel remotely close the input switch, the ship-side shore power supply will be started to perform synchronous grid connection and power transfer. After the transfer is completed, the diesel generator will be taken out of operation, and the shore power supply will then be fully responsible for the load. This completes the process of the high-voltage shore power supply system transitioning from grid connection to independent operation.

[0055] This embodiment also provides a control system for suppressing shore power inrush current, comprising: a first execution module for executing S1, detecting the state of the high-voltage output switch in the shore power supply; a second execution module for executing S2, detecting the state of the circuit breaker in the inrush current suppression cabinet when the high-voltage output switch is in the closed state; a third execution module for executing S3, acquiring the current state of the closing delay counter when the circuit breaker is in the open state; a fourth execution module for executing S4, acquiring the instantaneous value of the output current of the shore power supply if the current state of the closing delay counter satisfies the first state; and a fifth execution module for executing S5, continuously counting at a preset frequency when the current state of the closing delay counter satisfies the second state, or when the instantaneous value of the output current of the shore power supply is greater than a first preset current value, until the count value of the closing delay counter is greater than the preset value, and closing the circuit breaker in the inrush current suppression cabinet.

[0056] This embodiment also provides an electronic terminal, including: a memory for storing a computer program; and a processor for executing the computer program stored in the memory, so that the electronic terminal executes the control method for suppressing shore power inrush current.

[0057] This embodiment also provides a computer-readable storage medium storing a computer program: when executed by a processor, the program implements the aforementioned control method for suppressing shore power inrush current.

[0058] The specific embodiments described above further illustrate the purpose, technical solution, and beneficial effects of the present invention. It should be understood that the above description is only a specific embodiment of the present invention and is not intended to limit the scope of protection of the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A control method for suppressing shore power inrush current, characterized in that, Includes the following steps: S1. Detect the status of the high-voltage output switch in the shore power supply. If the high-voltage output switch is in the closed state, execute S2. S2. Detect the status of the circuit breaker in the inrush current suppression cabinet. If the circuit breaker is in the open state, execute S3. S3. Obtain the current state of the closing delay counter. If the current state of the closing delay counter satisfies the first state, execute S4; if the current state of the closing delay counter satisfies the second state, execute S5. The first state is that there is a count value on the closing delay counter, and the second state is that there is no count value on the closing delay counter. S4. Collect the instantaneous value of the output current of the shore power source. If the instantaneous value of the output current of the shore power source is greater than the first preset current value, execute S5. S5. The closing delay counter continues to count at a preset frequency until the count value of the closing delay counter is greater than the preset value, and then closes the inrush current suppression cabinet circuit breaker.

2. The control method for suppressing shore power inrush current according to claim 1, characterized in that: If the instantaneous value of the output current of the shore power supply on the shore side is not greater than the first preset current value; Then, the effective value of the output current of the shore power source is collected, and when the effective value of the output current of the shore power source is greater than the second preset current value, S5 is executed.

3. The control method for suppressing shore power inrush current according to claim 1, characterized in that: The first preset current value is obtained based on the current coefficient, the shore power supply capacity, and the rated output voltage of the shore power supply.

4. The control method for suppressing shore power inrush current according to claim 3, characterized in that: The current coefficient is obtained based on the rated load and minimum load of the shore power supply on the ship side.

5. The control method for suppressing shore power inrush current according to claim 4, characterized in that: The current coefficient is not greater than the ratio of the minimum load to the rated load of the shore power supply on the ship side.

6. The control method for suppressing shore power inrush current according to claim 3, characterized in that: The shore power capacity is the minimum shore power capacity when the shore power system is operating in a high-voltage onboard mode.

7. A control system for suppressing shore power inrush current, characterized in that, include: The first execution module is used to execute S1, which detects the status of the high-voltage output switch in the shore power supply. The second execution module is used to execute S2, which detects the status of the inrush current suppression cabinet circuit breaker when the high-voltage output switch is in the closed state. The third execution module is used to execute S3, which obtains the current state of the closing delay counter when the circuit breaker is in the open state; The fourth execution module is used to execute S4, which, if the current state of the closing delay counter satisfies the first state, collects the instantaneous value of the output current of the shore power supply on the shore side; the first state is that there is a count value on the closing delay counter. The fifth execution module is used to execute S5. When the current state of the closing delay counter meets the second state, the second state is that there is no count value on the closing delay counter; or, when the instantaneous value of the output current of the shore power supply is greater than the first preset current value, the closing delay counter continues to count at a preset frequency until the count value of the closing delay counter is greater than the preset value, and the inrush current suppression cabinet circuit breaker is closed.

8. An electronic terminal, characterized in that, include: The memory is used to store computer programs; A processor for executing a computer program stored in the memory to cause an electronic terminal to perform a control method for suppressing shore power inrush current as described in any one of claims 1-6.

9. A computer-readable storage medium storing a computer program thereon, characterized in that: When the program is executed by the processor, it implements a control method for suppressing shore power excitation inrush current as described in any one of claims 1-6.

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