Magnetic field inrush current suppression device, method and ship energy storage system

Abstract

The application relates to an excitation inrush current suppression device and method and a ship energy storage system. When a processor detects a power-on voltage signal on the primary side of a transformer, the device transmits a first conduction signal to a contactor, and then the contactor turns on a signal channel between a photovoltaic inverter and the primary side of the transformer according to the first conduction signal. When the contactor is closed, the processor transmits a first control signal to the photovoltaic inverter, and then the photovoltaic inverter outputs a first modulated electric signal with a preset voltage amplitude and a preset duration according to the first control signal, so that the photovoltaic inverter transmits the first modulated electric signal to the primary side of the transformer for magnetizing, provides reactive compensation for the transformer for demagnetization, suppresses the excitation inrush current generated by transformer closing, avoids the misoperation of a protection device, improves power supply quality, and reduces additional loss of the transformer.

Description

Technical Field

[0001] This application relates to the field of energy storage and power supply technology, and in particular to an excitation inrush current suppression device, method and ship energy storage system. Background Technology

[0002] For new energy ships, the combination of lithium batteries and the power system constitutes a small-scale power storage system, with energy transfer occurring through DC grid connections. In large ships, the transformers in the DC power distribution system typically have large capacities, accounting for a significant proportion of the ship's load and serving as crucial equipment in the ship's power system. During normal ship operation, the power transformer generates a steady-state magnetic flux. When the transformer is de-energized, due to the conservation of the circuit flux, the steady-state flux does not immediately disappear but retains a residual magnetism equal in magnitude and polarity to the final steady-state flux. When the transformer is switched on under no-load conditions, due to the effects of core flux saturation, hysteresis, and nonlinearity, if the direction of the magnetic flux generated by the applied normal operating voltage is the same as the original residual magnetism polarity, magnetic circuit saturation may occur due to the bias and residual magnetism, potentially inducing inrush current (e.g., an inrush current 7-8 times the rated current). Excessive residual magnetism leads to large inrush currents, which can cause transformer protection devices to malfunction. Since inrush currents contain a large number of harmonics, they are a source of harmonics in the power grid, reducing power quality. Residual magnetism can also increase additional losses in the transformer, and the harmonics generated by transformer waveform distortion can cause strong damage to sensitive electronic components.

[0003] Existing methods for suppressing inrush current caused by transformer closing have high hardware costs, low reliability in suppressing inrush current, and are still prone to causing malfunctions of protection devices, increasing additional losses in the transformer. Summary of the Invention

[0004] Based on this, it is necessary to address the problems existing in the above-mentioned methods for suppressing inrush current caused by transformer closing, and to provide an inrush current suppression device, method, and ship energy storage system that can enable the primary side of the transformer to quickly reach a steady-state magnetic flux, suppress the inrush current caused by transformer no-load closing, avoid malfunction of protection devices, improve power supply quality, and reduce the additional losses of the transformer.

[0005] In a first aspect, this application provides an inrush current suppression device, comprising:

[0006] A photovoltaic inverter is configured to output a first modulated electrical signal with a preset voltage amplitude and a preset duration according to a first control signal.

[0007] A contactor is connected between the photovoltaic inverter and the primary side of the transformer; the contactor is configured to open the signal channel between the photovoltaic inverter and the primary side of the transformer according to a first conduction signal, so that the photovoltaic inverter transmits a first modulated electrical signal to the primary side of the transformer for magnetization.

[0008] The processor is connected to the photovoltaic inverter, the contactor, and the primary side of the transformer. The processor is configured to transmit a first conduction signal to the contactor when it detects the power-on voltage signal on the primary side of the transformer. The processor is also configured to transmit a first control signal to the photovoltaic inverter when the contactor is closed.

[0009] Optionally, the first control signal includes a first control sub-signal, a second control sub-signal, a third control sub-signal, and a fourth control sub-signal;

[0010] The processor sequentially transmits the first control sub-signal, the second control sub-signal, the third control sub-signal, and the fourth control sub-signal to the photovoltaic inverter;

[0011] The photovoltaic inverter transmits a first modulated electrical signal with a first preset voltage amplitude and a preset duration to the primary side of the transformer according to a first control sub-signal; the photovoltaic inverter transmits a first modulated electrical signal with a second preset voltage amplitude and a preset duration to the primary side of the transformer according to a second control sub-signal; the photovoltaic inverter transmits a first modulated electrical signal with a third preset voltage amplitude and a preset duration to the primary side of the transformer according to a third control sub-signal; the photovoltaic inverter transmits a first modulated electrical signal with a fourth preset voltage amplitude and a preset duration to the primary side of the transformer according to a fourth control sub-signal; the first preset voltage amplitude is less than the second preset voltage amplitude, the second preset voltage amplitude is less than the third preset voltage amplitude, and the third preset voltage amplitude is less than the fourth preset voltage amplitude.

[0012] Optionally, the processor is also used to acquire the electrical parameters of the primary side of the transformer and transmit a second control signal to the photovoltaic inverter based on the electrical parameters; the photovoltaic inverter generates a second modulated electrical signal based on the second control signal and transmits the second modulated electrical signal to the primary side of the transformer for phase compensation.

[0013] Optionally, the primary side of the transformer is connected to the AC side of the power grid via a first circuit breaker;

[0014] The processor is also used to control the first circuit breaker to close when the results of magnetization and phase compensation meet preset conditions, and to transmit a first disconnect signal to the contactor after a preset delay time, so that the contactor disconnects the signal channel between the photovoltaic inverter and the primary side of the transformer.

[0015] Optionally, the photovoltaic inverter includes photovoltaic modules, a photovoltaic boost circuit, a bidirectional DC-DC converter circuit, an inverter circuit, and a first energy storage module;

[0016] The input terminal of the photovoltaic boost circuit is connected to the photovoltaic module, and the output terminal of the photovoltaic boost circuit is connected to the first terminal of the bidirectional DC-DC converter circuit and the input terminal of the inverter circuit, respectively; the second terminal of the bidirectional DC-DC converter circuit is connected to the first energy storage module; and the output terminal of the inverter circuit is connected to the contactor.

[0017] Optionally, the photovoltaic inverter also includes a first filter circuit; the first filter circuit is connected between the inverter circuit and the contactor.

[0018] Optionally, the photovoltaic inverter also includes a second circuit breaker; the second circuit breaker connects the first energy storage module and the first load.

[0019] Secondly, this application provides a method for suppressing inrush current, which includes the following steps;

[0020] When the voltage signal on the primary side of the transformer is detected, a first conduction signal is transmitted to the contactor; the first conduction signal is used to instruct the contactor to open the signal channel between the photovoltaic inverter and the primary side of the transformer, so that the photovoltaic inverter transmits the first modulated electrical signal to the primary side of the transformer for magnetization.

[0021] When the contactor is closed, a first control signal is transmitted to the photovoltaic inverter; the first control signal is used to instruct the photovoltaic inverter to output a first modulated electrical signal with a preset voltage amplitude and a preset duration.

[0022] Thirdly, this application provides a ship energy storage system, including a second energy storage module, a power conversion module, a first circuit breaker, a transformer, and any one of the above-mentioned inrush current suppression devices; the transformer includes the primary side of the transformer;

[0023] The second energy storage module is connected to the power conversion module, the power conversion module is connected to the first circuit breaker, and the first circuit breaker is connected to the primary side of the transformer.

[0024] The inrush current suppression device is connected to the primary side of the transformer.

[0025] Optionally, the ship energy storage system also includes a second filter circuit; the second filter circuit is connected between the power conversion module and the first circuit breaker.

[0026] One of the above technical solutions has the following advantages and beneficial effects:

[0027] The aforementioned inrush current suppression device includes a photovoltaic inverter, a contactor, and a processor. The contactor is connected between the photovoltaic inverter and the primary side of the transformer. The processor is connected to the photovoltaic inverter, the contactor, and the primary side of the transformer. When the processor detects the power-on voltage signal on the primary side of the transformer, it transmits a first conduction signal to the contactor. The contactor then conducts the signal channel between the photovoltaic inverter and the primary side of the transformer according to the first conduction signal. When the contactor is closed, the processor transmits a first control signal to the photovoltaic inverter. The photovoltaic inverter then outputs a first modulated electrical signal with a preset voltage amplitude and a preset duration according to the first control signal. This allows the photovoltaic inverter to transmit the first modulated electrical signal to the primary side of the transformer for magnetization, thereby providing reactive power compensation for demagnetization and suppressing the inrush current generated when the transformer is closed. This application achieves this by controlling the reactive power compensation of the photovoltaic inverter to magnetize the primary side of the transformer during the initial power-on phase on the AC grid side, before the transformer is switched on. This allows the primary side of the transformer to quickly reach a steady-state magnetic flux, thereby suppressing the inrush current caused by no-load switching on the transformer, preventing malfunctions of the protection device, improving power supply quality, and reducing additional losses of the transformer. Attached Figure Description

[0028] Figure 1 This is a schematic diagram of the first structure of the excitation inrush current suppression device in the embodiments of this application;

[0029] Figure 2 This is a schematic diagram of the second structure of the excitation inrush current suppression device in the embodiments of this application;

[0030] Figure 3 This is a schematic diagram of the third structure of the excitation inrush current suppression device in the embodiments of this application;

[0031] Figure 4 This is a schematic diagram of the fourth structure of the excitation inrush current suppression device in the embodiments of this application;

[0032] Figure 5 This is a flowchart illustrating the inrush current suppression method in the embodiments of this application;

[0033] Figure 6 This is a schematic diagram of the ship energy storage system in the embodiments of this application. Detailed Implementation

[0034] To enable those skilled in the art to better understand the present application, the technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present application, and not all embodiments. Based on the embodiments in the present application, all other embodiments obtained by those of ordinary skill in the art without creative effort should fall within the scope of protection of the present application.

[0035] It should be noted that the terms "first," "second," etc., in the specification, claims, and accompanying drawings of this application are used to distinguish similar objects and are not necessarily used to describe a specific order or sequence. It should be understood that such data can be interchanged where appropriate for the embodiments of this application described herein. Furthermore, the terms "comprising" and "having," and any variations thereof, are intended to cover non-exclusive inclusion; for example, a process, method, system, product, or apparatus that comprises a series of steps or units is not necessarily limited to those steps or units explicitly listed, but may include other steps or units not explicitly listed or inherent to such processes, methods, products, or apparatus.

[0036] In addition, the term "multiple" should mean two or more.

[0037] Traditional methods for suppressing inrush current caused by transformer closing mainly include the following two approaches: The first involves connecting a resistor in series between the primary side of the main transformer and the power grid. Adjusting the resistor suppresses the large inrush current. However, this method is difficult to control in terms of resistor value and the timing of the bypass resistor connection. Additionally, the resistor generates heat during pre-charging. The second approach involves connecting a small-capacity pre-magnetizing transformer in series between the primary side of the main transformer and the power grid. This pre-magnetizes the main transformer, establishing a steady-state magnetic flux before closing the main transformer. After this pre-magnetizing circuit is established, the pre-magnetizing circuit is disconnected, closing the main transformer circuit and thus suppressing the inrush current. However, this method can still result in a large inrush current if the timing of the main transformer closing is not chosen appropriately. Furthermore, if the pre-magnetizing transformer is connected to shore power, a separate medium-voltage switchgear is required, increasing hardware costs.

[0038] The inrush current suppression device, method, and ship energy storage system provided in this application can be applied to new energy ships, such as those with a passenger capacity of 50 passengers or more, or a length of 20 meters or more. In new energy ships, the combination of lithium batteries and the power system constitutes a small-scale power storage system, with energy transfer occurring through DC grid connections. This application utilizes reactive power compensation from a photovoltaic inverter to quickly achieve steady-state magnetic flux on the primary side of the transformer, suppressing inrush current caused by no-load switching of the transformer, preventing malfunctions of protection devices, improving power supply quality, and reducing additional transformer losses. Furthermore, the application of ship energy storage systems in new energy ships can improve the utilization rate of renewable energy, convert solar energy into electricity, reduce electricity costs, and reduce harmonics in the electricity generated by the photovoltaic power generation system. The output reactive power not only achieves energy conservation and emission reduction but also improves the quality of the power grid.

[0039] In one embodiment, such as Figure 1As shown, an inrush current suppression device is provided, which includes a photovoltaic inverter 100, a contactor 200 and a processor 300.

[0040] The photovoltaic inverter 100 is configured to output a first modulated electrical signal with a preset voltage amplitude and a preset duration according to a first control signal; the contactor 200 is connected between the photovoltaic inverter 100 and the primary side of the transformer; the contactor 200 is configured to conduct the signal channel between the photovoltaic inverter 100 and the primary side of the transformer according to a first conduction signal, so that the photovoltaic inverter 100 transmits the first modulated electrical signal to the primary side of the transformer for magnetization; the processor 300 is connected to the photovoltaic inverter 100, the contactor 200, and the primary side of the transformer respectively; the processor 300 is configured to transmit a first conduction signal to the contactor 200 when it detects the power-on voltage signal on the primary side of the transformer; the processor 300 is also configured to transmit a first control signal to the photovoltaic inverter 100 when the contactor 200 is closed.

[0041] In this context, photovoltaic inverter 100 refers to a photovoltaic energy storage inverter, which converts solar energy into electrical energy, stores the converted electrical energy, inverts the converted electrical energy, and feeds the inverted electrical energy back to the primary side of the transformer. Contactor 200 is an AC contactor 200. By connecting contactor 200 between photovoltaic inverter 100 and the primary side of the transformer, the signal channel between the photovoltaic inverter 100 and the primary side of the transformer can be opened or closed by controlling the on / off state of contactor 200. The transformer includes a primary side and a secondary side.

[0042] The processor 300 can be used for data acquisition and processing. For example, the processor 300 is connected to the photovoltaic inverter 100, the contactor 200, and the primary side of the transformer. The processor 300 can acquire the voltage signal from the primary side of the transformer, process the voltage signal, and control the on / off state of the contactor 200 based on the processing result. The processor 300 can also be used to control the operating state of the photovoltaic inverter 100, causing the photovoltaic inverter 100 to output a first modulated electrical signal with a preset voltage amplitude and preset duration to the primary side of the transformer.

[0043] For example, the inrush current suppression device can be applied to a ship energy storage system. The ship energy storage system may include a ship's AC power grid, a transformer, and a high-voltage load. The transformer includes a primary side and a secondary side. The high-voltage load refers to a 220V or 380V load. A first circuit breaker is installed between the ship's AC power grid and the primary side of the transformer, and a third circuit breaker is installed between the secondary side of the transformer and the high-voltage load. A contactor 200 is connected between the photovoltaic inverter 100 and the primary side of the transformer; a processor 300 is connected to the photovoltaic inverter 100, contactor 200, and the primary side of the transformer. When the ship energy storage system receives a power-on command from the bridge, each unit of the system begins self-testing. After each unit completes its self-test (without faults), the ship's AC power grid is powered on, at which point the first and third circuit breakers are in the open state. The processor 300 detects the voltage signal on the primary side of the transformer. Upon detecting this signal, it transmits a first conduction signal to the contactor 200. The contactor 200 then establishes the signal channel between the photovoltaic inverter 100 and the primary side of the transformer based on this first conduction signal. The processor 300 monitors the state of the contactor 200 in real time. When the contactor 200 is closed, it transmits a first control signal to the photovoltaic inverter 100. The photovoltaic inverter 100 then outputs a first modulated electrical signal with a preset voltage amplitude and a preset duration based on the first control signal. This allows the photovoltaic inverter 100 to transmit the first modulated electrical signal to the primary side of the transformer for magnetization, providing reactive power compensation, eliminating residual magnetism, and suppressing inrush current caused by no-load switching. Furthermore, after magnetizing the transformer, the processor 300 can control the first circuit breaker to conduct and the contactor 200 to disconnect, thus achieving grid connection of the transformer. Before the transformer is connected to the grid, the processor 300 controls the third circuit breaker to turn on, thereby completing the full power-on of the ship's energy storage system and supplying high-quality power to the high-voltage load side.

[0044] In the above embodiments, by controlling the reactive power compensation of the photovoltaic inverter 100 to magnetize the primary side of the transformer during the initial power-on phase of the AC grid side and before the transformer is closed, the primary side of the transformer can quickly reach a steady-state magnetic flux, thereby suppressing the inrush current caused by the transformer being closed under no-load conditions, avoiding maloperation of the protection device, thus improving the power supply quality and reducing the additional losses of the transformer.

[0045] In one example, the first control signal includes a first control sub-signal, a second control sub-signal, a third control sub-signal, and a fourth control sub-signal; the processor 300 sequentially transmits the first control sub-signal, the second control sub-signal, the third control sub-signal, and the fourth control sub-signal to the photovoltaic inverter 100.

[0046] The photovoltaic inverter 100 transmits a first modulated electrical signal with a first preset voltage amplitude and a preset duration to the primary side of the transformer according to a first control sub-signal; the photovoltaic inverter 100 transmits a first modulated electrical signal with a second preset voltage amplitude and a preset duration to the primary side of the transformer according to a second control sub-signal; the photovoltaic inverter 100 transmits a first modulated electrical signal with a third preset voltage amplitude and a preset duration to the primary side of the transformer according to a third control sub-signal; the photovoltaic inverter 100 transmits a first modulated electrical signal with a fourth preset voltage amplitude and a preset duration to the primary side of the transformer according to a fourth control sub-signal; the first preset voltage amplitude is less than the second preset voltage amplitude, the second preset voltage amplitude is less than the third preset voltage amplitude, and the third preset voltage amplitude is less than the fourth preset voltage amplitude.

[0047] The first control sub-signal, the second control sub-signal, the third control sub-signal, and the fourth control sub-signal can be PWM signals with different duty cycles. The first modulated electrical signal can be a three-phase sinusoidal AC signal.

[0048] Based on the premise that the first preset voltage amplitude is less than the second preset voltage amplitude, the second preset voltage amplitude is less than the third preset voltage amplitude, and the third preset voltage amplitude is less than the fourth preset voltage amplitude, the first, second, third, and fourth preset voltage amplitudes can be obtained by system preset; the preset duration can also be obtained by system preset. For example, the first preset voltage amplitude can be set to 25% of the transformer's rated voltage; the second preset voltage amplitude can be 50% of the transformer's rated voltage; the third preset voltage amplitude can be 75% of the transformer's rated voltage; the fourth preset voltage amplitude can be 100% of the transformer's rated voltage; and the preset duration can be set to 3 minutes (min).

[0049] For example, when the contactor 200 is closed, the processor 300 can transmit a first control sub-signal to the photovoltaic inverter 100. The photovoltaic inverter 100 then transmits a first modulated electrical signal with a first preset voltage amplitude and a preset duration to the primary side of the transformer according to the first control sub-signal, achieving the first magnetization of the primary side of the transformer. Upon completion of the first magnetization, the processor 300 transmits a second control sub-signal to the photovoltaic inverter 100. The photovoltaic inverter 100 then transmits a first modulated electrical signal with a second preset voltage amplitude and a preset duration to the primary side of the transformer according to the second control sub-signal, achieving the second magnetization of the primary side of the transformer. Upon completion of the second magnetization, the processor 300 transmits a third control sub-signal to the photovoltaic inverter 100. The photovoltaic inverter 100 then transmits a first modulated electrical signal with a third preset voltage amplitude and a preset duration to the primary side of the transformer according to the third control sub-signal, achieving the third magnetization of the primary side of the transformer. Upon completion of the third magnetization, the processor 300 transmits a fourth control sub-signal to the photovoltaic inverter 100. The photovoltaic inverter 100 then transmits a first modulated electrical signal with a fourth preset voltage amplitude and a preset duration to the primary side of the transformer according to the fourth control sub-signal, thereby achieving a fourth magnetization of the primary side of the transformer. By sequentially increasing the preset voltage amplitude to magnetize the primary side of the transformer, the effect of eliminating residual magnetism in the transformer can be improved.

[0050] In one example, when the contactor 200 is closed, the processor 300 can transmit a first control sub-signal to the photovoltaic inverter 100. Then, the photovoltaic inverter 100 performs SPWM modulation on the input DC power signal according to the first control sub-signal and adjusts the modulation amplitude value so that the output voltage of the first modulated electrical signal (i.e., the three-phase sinusoidal AC signal) of the photovoltaic inverter 100 gradually increases to 25% of the rated voltage (50HZ), magnetizes the primary winding of the transformer, and after holding for 3 minutes, the output voltage of the first modulated electrical signal of the photovoltaic inverter 100 slowly decreases to 0, realizing the first magnetization of the primary side of the transformer.

[0051] When the processor 300 completes the first magnetization, it transmits a second control sub-signal to the photovoltaic inverter 100. Then, the photovoltaic inverter 100 performs SPWM modulation on the input DC power signal according to the second control sub-signal and adjusts the modulation amplitude value, so that the output voltage of the first modulation electrical signal (i.e., the three-phase sinusoidal AC signal) of the photovoltaic inverter 100 gradually increases to 50% of the rated voltage (50HZ), magnetizing the primary coil of the transformer. After maintaining this for 3 minutes, the output voltage of the first modulation electrical signal of the photovoltaic inverter 100 slowly decreases to 0, realizing the second magnetization of the primary side of the transformer.

[0052] When the processor 300 completes the second magnetization, it transmits a third control sub-signal to the photovoltaic inverter 100. Then, the photovoltaic inverter 100 performs SPWM modulation on the input DC power signal according to the third control sub-signal and adjusts the modulation amplitude value, so that the output voltage of the first modulation electrical signal (i.e., the three-phase sinusoidal AC signal) of the photovoltaic inverter 100 gradually increases to 75% of the rated voltage (50HZ), magnetizing the primary coil of the transformer. After maintaining this for 3 minutes, the output voltage of the first modulation electrical signal of the photovoltaic inverter 100 slowly decreases to 0, realizing the third magnetization of the primary side of the transformer.

[0053] When the processor 300 completes the third magnetization, it transmits a fourth control sub-signal to the photovoltaic inverter 100. The photovoltaic inverter 100 then performs SPWM modulation on the input DC power signal according to the fourth control sub-signal and adjusts the modulation amplitude. This causes the output voltage of the first modulated electrical signal (i.e., the three-phase sinusoidal AC signal) of the photovoltaic inverter 100 to gradually increase to 100% of the rated voltage (50Hz), magnetizing the primary winding of the transformer. After maintaining this state for 3 minutes, the output voltage of the first modulated electrical signal of the photovoltaic inverter 100 slowly decreases to 0, achieving the fourth magnetization of the primary side of the transformer. This significantly improves the effect of eliminating residual magnetism in the transformer, suppressing inrush current caused by no-load switching of the transformer, preventing malfunctions of protection devices, thereby improving power supply quality and reducing additional transformer losses.

[0054] In one example, the processor 300 is also used to acquire electrical parameters on the primary side of the transformer and transmit a second control signal to the photovoltaic inverter 100 based on the electrical parameters; the photovoltaic inverter 100 generates a second modulated electrical signal based on the second control signal and transmits the second modulated electrical signal to the primary side of the transformer for phase compensation.

[0055] The electrical parameters can be the phase, frequency, and amplitude of the voltage signal on the primary side of the transformer. The processor 300 can collect electrical parameters such as the phase, frequency, and amplitude of the voltage on the primary side of the transformer, and transmit a second control signal to the photovoltaic inverter 100 according to each electrical parameter. The photovoltaic inverter 100 generates a second modulated electrical signal according to the second control signal, and transmits the second modulated electrical signal to the primary side of the transformer to provide an output voltage that slowly rises from zero to the rated voltage, thereby performing phase compensation on the primary side of the transformer.

[0056] In one example, based on the fact that the primary side of the transformer is connected to the ship's AC power grid through the first circuit breaker, the processor 300 can also obtain the phase, frequency, and amplitude electrical parameters of the voltage on the ship's AC power grid side, and perform phase-locking on each electrical parameter; the processor 300 transmits a second control signal to the photovoltaic inverter 100 according to each electrical parameter; the photovoltaic inverter 100 generates a second modulation electrical signal whose voltage amplitude slowly rises from zero to the rated voltage of the transformer according to the second control signal, and transmits the second modulation electrical signal to the primary side of the transformer to realize phase compensation on the primary side of the transformer.

[0057] In one example, the primary side of the transformer is connected to the AC side of the power grid via a first circuit breaker. The processor 300 is also configured to, based on the results of magnetization and phase compensation, control the first circuit breaker to close when the results of magnetization and phase compensation meet preset conditions, and transmit a first disconnect signal to the contactor 200 after a preset delay time, so that the contactor 200 disconnects the signal channel between the photovoltaic inverter 100 and the primary side of the transformer.

[0058] The preset delay time can be obtained from the system preset, for example, the preset delay time can be set to 30 milliseconds (ms).

[0059] For example, the processor 300 can collect electrical parameters from the primary side of the transformer and the AC grid side of the ship. When the electrical parameters from the primary side of the transformer and the AC grid side of the ship are in the same frequency, amplitude, and phase, it determines that the results of magnetizing the primary side of the transformer and the phase compensation meet preset conditions, and then controls the first circuit breaker to close. When the processor 300 detects that the first circuit breaker is closed, it transmits a first disconnection signal to the contactor 200 after a preset delay time, so that the contactor 200 disconnects the signal channel between the photovoltaic inverter 100 and the primary side of the transformer.

[0060] It should be noted that the photovoltaic inverter 100 outputs reactive power during the demagnetization process on the primary side of the transformer. After the transformer is switched on, the photovoltaic inverter 100 can also output active power to supply power to the high-voltage load if necessary.

[0061] In one embodiment, such as Figure 2 As shown, the photovoltaic inverter 100 includes a photovoltaic module 110, a photovoltaic boost circuit 120, a bidirectional DC-DC converter 130, an inverter circuit 140, and a first energy storage module 150. The input terminal of the photovoltaic boost circuit 120 is connected to the photovoltaic module 110, and the output terminal of the photovoltaic boost circuit 120 is connected to the first terminal of the bidirectional DC-DC converter 130 and the input terminal of the inverter circuit 140, respectively. The second terminal of the bidirectional DC-DC converter 130 is connected to the first energy storage module 150, and the output terminal of the inverter circuit 140 is connected to the contactor 200.

[0062] The photovoltaic module 110 is the core and most important component of the solar power generation system. It converts solar energy into electrical energy. The photovoltaic boost circuit 120, based on the BUS bus voltage, boosts the DC voltage output from the photovoltaic module 110 to the DC voltage required for control by the inverter circuit 140, while also filtering the DC voltage output from the photovoltaic module 110.

[0063] The bidirectional DC-DC converter circuit 130 (i.e., bidirectional DC-DC circuit) can adopt a BUCK / BOOST circuit topology and has a bidirectional buck-boost conversion function, i.e. a buck-boost chopper circuit. The first energy storage module 150 and the photovoltaic module 110 side have bidirectional buck-boost, which can be compatible with the first energy storage module 150 with a variety of different voltage ranges.

[0064] The inverter circuit 140 enables bidirectional energy transfer between the ship's AC grid power and the first energy storage module 150. It also provides reactive power compensation to mitigate current conflicts, stabilize voltage drops, reduce reactive power losses, and ensure power quality. The first energy storage module 150 can be a lithium battery module. For example, the first energy storage module 150 can use a small-capacity lithium battery pack to provide temporary power to the ship. When sunlight is strong, it converts solar energy into electrical energy for storage, reducing electricity costs.

[0065] For example, when the processor 300 detects the power-on voltage signal on the primary side of the transformer, it determines that the ship has completed the first half of the power-on process. Then, it transmits a first conduction signal to the contactor 200, causing the contactor 200 to close. At the same time, it controls the photovoltaic boost circuit 120 to be in a non-working state and controls the inverter circuit 140 and the bidirectional DC-DC converter circuit 130 to be in a working state. By transmitting a first control signal to the inverter circuit 140, the inverter circuit 140 outputs a first modulated electrical signal with a preset voltage amplitude and a preset duration according to the first control signal. This allows the inverter circuit 140 to transmit the first modulated electrical signal to the primary side of the transformer for magnetization, thereby providing reactive power compensation for the ship's transformer to demagnetize it and suppress the transformer's inrush current during closing.

[0066] In one example, when the ship has many converter devices with high power, the processor 300 controls the contactor 200 to close, simultaneously controlling the photovoltaic boost circuit 120 to be in a non-operating state, and controlling the inverter circuit 140 and the bidirectional DC-DC converter circuit 130 to be in an operating state. Then, the first energy storage module 150 provides reactive power compensation to the ship's AC power grid side to improve the power factor of the ship's AC power grid.

[0067] In one example, such as Figure 3As shown, the photovoltaic inverter 100 also includes a first filter circuit 160; the first filter circuit 160 is connected between the inverter circuit 140 and the contactor 200.

[0068] The first filter circuit 160 can be an LC low-pass filter circuit. The first filter circuit 160 can filter the AC signal output by the inverter circuit 140, filter out interference signals, reduce the harmonic interference of the output sine wave, and obtain a first modulated electrical signal (i.e., AC sine wave signal) of better quality.

[0069] Since the first filter circuit 160 is connected between the inverter circuit 140 and the contactor 200, the processor 300 can transmit a first control signal to the photovoltaic inverter 100 when the contactor 200 is closed. The photovoltaic inverter 100 outputs a first modulated electrical signal with a preset voltage amplitude and a preset duration according to the first control signal. After the first modulated electrical signal is filtered by the first filter circuit 160, the filtered first modulated electrical signal is transmitted to the primary side of the transformer to magnetize the primary side of the transformer, thereby improving the effect of eliminating residual magnetism in the transformer.

[0070] In one example, such as Figure 4 As shown, the photovoltaic inverter 100 also includes a second circuit breaker 170; the second circuit breaker 170 is connected between the first energy storage module 150 and the first load 180.

[0071] The first load 180 can be a low-voltage load on the ship with a power supply voltage of 24VDC, such as signal lights, buzzers, displays and lighting equipment.

[0072] For example, in a ship energy storage system based on an excitation inrush current suppression device applied to a new energy ship, by installing photovoltaic modules 110 on the new energy ship, during the ship's operation, when the sunlight is good, the processor 300 controls the contactor 200 to open and the second circuit breaker 170 to close, while controlling the photovoltaic boost circuit 120 and the bidirectional DC-DC converter circuit 130 to be in working state, and controlling the inverter circuit 140 to be in non-working state, the photovoltaic modules 110 can then supply power to the first load 180. When the photovoltaic modules 110 have surplus energy, they can convert solar energy into electrical energy and store it in the first energy storage module 150.

[0073] During the ship's operation, when the sunlight is insufficient to meet the power supply requirements of the first load 180, the processor 300 controls the contactor 200 to open and the second circuit breaker 170 to close. At the same time, it controls the photovoltaic boost circuit 120 and the bidirectional DC-DC converter circuit 130 to be in working state, and controls the inverter circuit 140 to be in non-working state. Thus, the photovoltaic module 110 and the first energy storage module 150 can simultaneously supply power to the first load 180.

[0074] During the ship's voyage, when the lighting is poor and cannot meet the power supply requirements of the first load 180, the processor 300 controls the contactor 200 to open and the second circuit breaker 170 to close. At the same time, it controls the photovoltaic boost circuit 120, the bidirectional DC-DC converter circuit 130 and the inverter circuit 140 to be in a non-working state, thereby supplying power to the first load 180 through the first energy storage module 150.

[0075] When the ship is anchored and sunlight is abundant, the processor 300 controls the contactor 200 to open and the second circuit breaker 170 to close. Simultaneously, it controls the photovoltaic boost circuit 120 and the bidirectional DC-DC converter circuit 130 to operate, and controls the inverter circuit 140 to operate in a non-operating state. Thus, the photovoltaic module 110 can convert solar energy into electrical energy and store it in the first energy storage module 150. Furthermore, the photovoltaic module 110 can also supply power to the first load 180.

[0076] When the ship is moored and the sunlight is normal, the processor 300 controls the contactor 200 to open and the second circuit breaker 170 to close. At the same time, it controls the photovoltaic boost circuit 120 and the bidirectional DC-DC converter circuit 130 to be in working state, and controls the inverter circuit 140 to be in non-working state. Since the first load 180 has low power demand when the ship is moored, it can be powered by the photovoltaic module 110.

[0077] When the ship is anchored, and the lighting is poor, and the photovoltaic module 110 cannot supply power to the first load 180, the processor 300 controls the contactor 200 to open and the second circuit breaker 170 to close. At the same time, it controls the photovoltaic boost circuit 120, the bidirectional DC-DC converter circuit 130 and the inverter circuit 140 to be in a non-working state, and then supplies power to the first load 180 through the first energy storage module 150.

[0078] When the ship starts up, the processor 300 controls the contactor 200 to open and the second circuit breaker 170 to close, while controlling the photovoltaic boost circuit 120, the bidirectional DC-DC converter circuit 130 and the inverter circuit 140 to be in a non-operating state, and provides starting power to the ship control equipment through the first energy storage module 150.

[0079] In the above embodiments, the photovoltaic inverter 100 flexibly converts energy between solar energy and electrical energy, which can improve the utilization rate of renewable energy and convert solar energy into electrical energy, thereby reducing the cost of electricity. In addition, the electrical energy generated by the photovoltaic inverter 100 has fewer harmonics, and the reactive power output not only achieves energy conservation and emission reduction, reduces costs, and improves energy utilization, but also improves the quality of the power grid.

[0080] In one embodiment, such as Figure 5 As shown, a method for suppressing inrush current is provided, which includes the following steps;

[0081] In step S510, when the power-on voltage signal on the primary side of the transformer is detected, a first conduction signal is transmitted to the contactor; the first conduction signal is used to instruct the contactor to conduct the signal channel between the photovoltaic inverter and the primary side of the transformer, so that the photovoltaic inverter transmits the first modulated electrical signal to the primary side of the transformer for magnetization.

[0082] In step S520, when the contactor is closed, a first control signal is transmitted to the photovoltaic inverter; the first control signal is used to instruct the photovoltaic inverter to output a first modulated electrical signal with a preset voltage amplitude and a preset duration.

[0083] For example, the inrush current suppression method can be applied to a ship's energy storage system. When the ship's energy storage system receives a power-on command from the bridge, each unit begins self-testing. After each unit completes its self-test (without faults), the ship's AC power grid is powered on, at which point the first circuit breaker is in the open state. The processor detects the power-on voltage signal on the primary side of the transformer. Upon detecting this signal, it transmits a first conduction signal to the contactor. The contactor, based on the first conduction signal, opens the signal channel between the photovoltaic inverter and the primary side of the transformer. The processor monitors the contactor's status in real time. When the contactor is closed, it transmits a first control signal to the photovoltaic inverter. The photovoltaic inverter, based on the first control signal, outputs a first modulated electrical signal with a preset voltage amplitude and preset duration. This allows the photovoltaic inverter to transmit the first modulated electrical signal to the primary side of the transformer for magnetization, providing reactive power compensation to the transformer, eliminating residual magnetism, and suppressing inrush current caused by no-load switching on the transformer.

[0084] In the above embodiments, by controlling the reactive power compensation of the photovoltaic inverter to magnetize the primary side of the transformer during the initial stage of power-on on the AC grid side and before the transformer is closed, the primary side of the transformer can quickly reach a steady-state magnetic flux, thereby suppressing the inrush current caused by the transformer being closed under no-load conditions, avoiding maloperation of the protection device, thus improving the power supply quality and reducing the additional losses of the transformer.

[0085] It should be understood that, although Figure 5 The steps in the flowchart are shown sequentially as indicated by the arrows, but these steps are not necessarily executed in the order indicated by the arrows. Unless otherwise specified herein, there is no strict order in which these steps are executed, and they can be performed in other orders. Figure 5 At least some of the steps in the process may include multiple sub-steps or multiple stages. These sub-steps or stages are not necessarily completed at the same time, but can be executed at different times. The execution order of these sub-steps or stages is not necessarily sequential, but can be executed in turn or alternately with other steps or at least some of the sub-steps or stages of other steps.

[0086] In one embodiment, such as Figure 6 As shown, a ship energy storage system is also provided, including a second energy storage module 20, a power conversion module, a first circuit breaker 40, a transformer 50, and any one of the above-mentioned inrush current suppression devices 10; the transformer 50 includes a primary side; the second energy storage module 20 is connected to the power conversion module, the power conversion module is connected to the first circuit breaker 40, and the first circuit breaker 40 is connected to the primary side of the transformer 50; the inrush current suppression device is connected to the primary side of the transformer 50.

[0087] The second energy storage module 20 may be a lithium battery (BAT) system, and the power conversion module may include a fuse 330, a DC-DC module 310, and a DC-AC module 320. The DC-DC module 310 is connected between the second energy storage module 20 and the fuse 330, and the DC-AC module 320 is connected between the fuse 330 and the first circuit breaker 40.

[0088] For example, the marine energy storage system further includes a second filter circuit 60; the second filter circuit 60 is connected between the power conversion module and the first circuit breaker 40. The second filter circuit 60 can be an LCL filter circuit, which can be used to filter the AC sine wave output from the DC-AC module 320, thereby outputting a filtered signal. The marine energy storage system also includes a third circuit breaker, which is located between the secondary side of the transformer 50 and the high-voltage load.

[0089] When the system receives the power-on command from the bridge, each unit of the system begins self-testing. After each unit completes its self-test (without faults), the second energy storage module 20 closes the high-voltage relay. When a high-voltage signal is detected from the output of the second energy storage module 20, the DC-DC module 310 is controlled to start automatically. When a high voltage is detected on the output side of the DC-DC module 310, the DC-AC module 320 is controlled to start automatically. At this point, the first half of the power-on process of the ship's energy storage system ends, and the first circuit breaker 40 and the third circuit breaker are in the open state.

[0090] The contactor 200 is connected between the photovoltaic inverter and the primary side of the transformer 50. The processor is connected to the photovoltaic inverter, contactor 200, and the primary side of the transformer 50. The processor detects the voltage signal on the primary side of the transformer 50. When the voltage signal is detected, it transmits a first conduction signal to the contactor 200. The contactor 200 then conducts the signal channel between the photovoltaic inverter and the primary side of the transformer 50 according to the first conduction signal. The processor monitors the state of the contactor 200 in real time. When the contactor 200 is closed, it transmits a first control signal to the photovoltaic inverter. The photovoltaic inverter then outputs a first modulated electrical signal with a preset voltage amplitude and a preset duration according to the first control signal. This allows the photovoltaic inverter to transmit the first modulated electrical signal to the primary side of the transformer 50 for magnetization, thereby providing reactive power compensation for the transformer 50, eliminating residual magnetism in the transformer 50, and suppressing inrush current caused by no-load closing of the transformer 50. Furthermore, after magnetizing transformer 50, the processor can control the first circuit breaker 40 to conduct and control the contactor 200 to disconnect, thereby achieving grid connection of transformer 50. Before grid connection of transformer 50, the processor controls the third circuit breaker to conduct, thus completing the full power-on of the ship's energy storage system and supplying high-quality power to the high-voltage load side.

[0091] In the above embodiments, by controlling the reactive power compensation of the photovoltaic inverter to magnetize the primary side of the transformer 50 during the initial power-on phase of the AC grid side and before the transformer 50 is closed, the primary side of the transformer 50 is quickly brought to a steady-state magnetic flux, thereby suppressing the inrush current caused by the no-load closing of the transformer 50, avoiding maloperation of the protection device, thus improving the power supply quality and reducing the additional losses of the transformer 50.

[0092] In one embodiment, this application provides a computer storage medium storing a computer program thereon, which, when executed by a processor, implements the steps of the excitation inrush current suppression method described above.

[0093] In one example, when a computer program is executed by a processor, it performs the following steps:

[0094] When an on-voltage signal is detected on the primary side of the transformer, a first conduction signal is transmitted to the contactor. This first conduction signal instructs the contactor to open the signal channel between the photovoltaic inverter and the primary side of the transformer, enabling the photovoltaic inverter to transmit a first modulated electrical signal to the primary side of the transformer for magnetization. When the contactor closes, a first control signal is transmitted to the photovoltaic inverter. This first control signal instructs the photovoltaic inverter to output a first modulated electrical signal with a preset voltage amplitude and a preset duration.

[0095] Those skilled in the art will understand that all or part of the processes in the above embodiments can be implemented by a computer program instructing related hardware. The computer program can be stored in a non-volatile computer-readable storage medium. When executed, the computer program can include the processes of the embodiments of the division operations described above. Any references to memory, storage, databases, or other media used in the embodiments provided in this application can include non-volatile and / or volatile memory. Non-volatile memory may include read-only memory (ROM), programmable ROM (PROM), electrically programmable ROM (EPROM), electrically erasable programmable ROM (EEPROM), or flash memory. Volatile memory may include random access memory (RAM) or external cache memory. By way of illustration and not limitation, RAM is available in a variety of forms, such as static RAM (SRAM), dynamic RAM (DRAM), synchronous DRAM (SDRAM), dual data rate SDRAM (DDRSDRAM), enhanced SDRAM (ESDRAM), synchronous link DRAM (SLDRAM), RAMbus direct RAM (RDRAM), direct memory bus dynamic RAM (DRDRAM), and memory bus dynamic RAM (RDRAM).

[0096] The technical features of the above embodiments can be combined in any way. For the sake of brevity, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0097] The embodiments described above are merely illustrative of several implementation methods of this application, and while the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the patent application. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of this application, and these all fall within the protection scope of this application. Therefore, the protection scope of this patent application should be determined by the appended claims.

Claims

1. An excitation inrush current suppression device, characterized in that, include: A photovoltaic inverter, the photovoltaic inverter being configured to output a first modulated electrical signal with a preset voltage amplitude and a preset duration according to a first control signal; A contactor is connected between the photovoltaic inverter and the primary side of the transformer; the contactor is configured to open a signal channel between the photovoltaic inverter and the primary side of the transformer according to a first conduction signal, so that the photovoltaic inverter transmits the first modulated electrical signal to the primary side of the transformer for magnetization; The processor is connected to the photovoltaic inverter, the contactor, and the primary side of the transformer. The processor is configured to transmit the first conduction signal to the contactor when the first circuit breaker between the primary side of the transformer and the AC side of the power grid is open. The processor is also configured to transmit the first control signal to the photovoltaic inverter when the contactor is closed.

2. The excitation inrush current suppression device according to claim 1, characterized in that, The first control signal includes a first control sub-signal, a second control sub-signal, a third control sub-signal, and a fourth control sub-signal; The processor sequentially transmits the first control sub-signal, the second control sub-signal, the third control sub-signal, and the fourth control sub-signal to the photovoltaic inverter; The photovoltaic inverter transmits a first modulated electrical signal with a first preset voltage amplitude and a preset duration to the primary side of the transformer according to the first control sub-signal; The photovoltaic inverter transmits a first modulated electrical signal with a second preset voltage amplitude and a preset duration to the primary side of the transformer according to the second control sub-signal; The photovoltaic inverter transmits a first modulated electrical signal with a third preset voltage amplitude and a preset duration to the primary side of the transformer according to the third control sub-signal; The photovoltaic inverter transmits a first modulated electrical signal with a fourth preset voltage amplitude and preset duration to the primary side of the transformer according to the fourth control sub-signal; The first preset voltage amplitude is less than the second preset voltage amplitude, the second preset voltage amplitude is less than the third preset voltage amplitude, and the third preset voltage amplitude is less than the fourth preset voltage amplitude.

3. The excitation inrush current suppression device according to claim 2, characterized in that, The processor is further configured to acquire electrical parameters on the primary side of the transformer and transmit a second control signal to the photovoltaic inverter based on the electrical parameters; the photovoltaic inverter generates a second modulated electrical signal based on the second control signal and transmits the second modulated electrical signal to the primary side of the transformer for phase compensation.

4. The excitation inrush current suppression device according to claim 3, characterized in that, The primary side of the transformer is connected to the AC side of the power grid via a first circuit breaker; The processor is further configured to, based on the obtained magnetization result and the phase compensation result, control the first circuit breaker to close when the magnetization result and the phase compensation result meet preset conditions, and transmit a first disconnect signal to the contactor after a preset delay time, so that the contactor disconnects the signal channel between the photovoltaic inverter and the primary side of the transformer.

5. The inrush current suppression device according to any one of claims 1 to 4, characterized in that, The photovoltaic inverter includes a photovoltaic module, a photovoltaic boost circuit, a bidirectional DC-DC converter circuit, an inverter circuit, and a first energy storage module; The input terminal of the photovoltaic boost circuit is connected to the photovoltaic module, and the output terminal of the photovoltaic boost circuit is connected to the first terminal of the bidirectional DC-DC converter circuit and the input terminal of the inverter circuit, respectively; the second terminal of the bidirectional DC-DC converter circuit is connected to the first energy storage module; and the output terminal of the inverter circuit is connected to the contactor.

6. The excitation inrush current suppression device according to claim 5, characterized in that, The photovoltaic inverter also includes a first filter circuit; the first filter circuit is connected between the inverter circuit and the contactor.

7. The inrush current suppression device according to claim 6, characterized in that, The photovoltaic inverter also includes a second circuit breaker; the second circuit breaker connects the first energy storage module and the first load.

8. A method for suppressing inrush current, characterized in that, Includes the following steps: With the first circuit breaker between the primary side of the transformer and the AC side of the power grid open, a first conduction signal is transmitted to the contactor when an on-voltage signal is detected on the primary side of the transformer. The first conduction signal is used to instruct the contactor to conduct the signal channel between the photovoltaic inverter and the primary side of the transformer, so that the photovoltaic inverter transmits the first modulated electrical signal to the primary side of the transformer for magnetization; When the contactor is closed, a first control signal is transmitted to the photovoltaic inverter; The first control signal is used to instruct the photovoltaic inverter to output a first modulated electrical signal with a preset voltage amplitude and a preset duration.

9. A ship energy storage system, characterized in that, It includes a second energy storage module, a power conversion module, a first circuit breaker, a transformer, and the inrush current suppression device according to any one of claims 4 to 7; the transformer includes the primary side of the transformer; The second energy storage module is connected to the power conversion module, the power conversion module is connected to the first circuit breaker, and the first circuit breaker is connected to the primary side of the transformer. The inrush current suppression device is connected to the primary side of the transformer.

10. The ship energy storage system according to claim 9, characterized in that, It also includes a second filter circuit; the second filter circuit is connected between the power conversion module and the first circuit breaker.

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