Ship load test electric energy recovery device and working method thereof

Abstract

The present application relates to the technical field of ship electricity, and discloses a ship load test electric energy recovery device and a working method thereof, which comprises a 10KV micro-grid part, a system input side, a current conversion unit part and a system output side. The 10KV micro-grid is connected through the system input side and the current conversion unit part. The current conversion unit part comprises a main machine structure and a standby machine structure, which are connected in parallel and controlled by a PLC control system. The current conversion unit part is connected with the system output side. The method comprises a forward shore power supply mode and a reverse energy feedback mode. A fully controllable power electronic topology replaces an uncontrollable rectification structure, realizes bidirectional energy flow, and solves the pain point that a traditional shore power supply cannot feed reverse power back to a power grid. The feedback electric energy is preferentially supplied to enterprise production loads, and the surplus part is stored in an energy storage device through a micro-grid interface. When the energy storage device is discharged, it can smooth the peak-valley difference of the power grid, and the safety threat of reverse power to shore power equipment is eliminated from the root.

Description

Technical Field

[0001] This invention relates to the field of marine electrical technology, specifically to a marine load test energy recovery device and its working method. Background Technology

[0002] To address fuel pollution at port terminals, my country has been vigorously developing shore power in recent years. However, when shore power systems supply power to ships for load characteristic tests, reverse power often occurs due to the test loads on board, posing a threat to the safety of shore power equipment. Therefore, the following technical problems are frequently encountered in the actual use of shore power in ports: The traditional method of preventing reverse power is to use dry resistors placed in the DC bus of the inverter. When reverse power occurs, the resistors absorb this power and dissipate it as heat. However, the disadvantages of dry resistor loads are: all electrical energy is wasted as heat, and the resistor temperature can reach hundreds of degrees Celsius when reverse power occurs, posing a significant safety risk to shore power equipment.

[0003] With the global transformation towards green ports and increasingly stringent regulations from the International Maritime Organization (IMO) regarding ship emissions during berthing, the application of shore power is becoming increasingly widespread. Simultaneously, shipbuilding is showing a significant trend towards larger vessels, with giant container ships and oil tankers emerging. Furthermore, the various loads required to maintain the operation of equipment while ships are berthed often generate reverse power flow back to the shore power system during normal operation or load testing, reaching megawatt-level scale and still showing a further growth trend, impacting the normal and stable operation of the shore power system. Against this backdrop, energy recovery technology from ship loads has become another core direction in the development of ship-to-shore power technology.

[0004] In one invention, a method, apparatus, and electronic device for controlling reverse power from shore power (publication number CN113507109A), the method and related apparatus use the excitation electromotive force of the ship's generator as a basis to precisely adjust the output voltage of the shore power supply, reduce the possibility of reverse power surges, and achieve stable grid connection. However, the problem of reverse power recovery and utilization is still not solved, and the goal of true energy saving cannot be achieved. Therefore, we propose a ship load test energy recovery device.

[0005] Traditional methods for preventing reverse power surges involve using dry-resistance devices placed in the DC bus of the inverter. When reverse power occurs, the resistors absorb this power and dissipate it as heat. However, dry-resistance loads have several drawbacks: all electrical energy is wasted as heat, and the resistor temperature can reach hundreds of degrees Celsius during reverse power surges, posing a significant safety risk to shore power equipment. As described in CN113507109A, software-based control adjusts the output voltage of the shore power supply to reduce the possibility of reverse power surges. However, this method still does not solve the problem of reverse power recovery and utilization.

[0006] Therefore, a new technical solution is needed to solve the above-mentioned technical problems. Summary of the Invention

[0007] To address the aforementioned problems, this invention discloses a ship load test energy recovery device and its operating method.

[0008] The technical solution of the present invention is as follows: a ship load test power recovery device, comprising a 10KV microgrid section, a system input side, a converter unit section, and a system output side. The 10KV microgrid is connected to the system input side and the converter unit section. The converter unit section includes a main unit structure and a backup unit structure, which are connected in parallel and controlled by a PLC. The converter unit section is connected to the system output side.

[0009] Preferably, the 10kV microgrid includes an energy management module, an energy storage converter, an energy storage battery pack, and enterprise production loads. The energy storage battery pack and the energy storage converter are connected in parallel with the enterprise production loads, and a microgrid interface is connected between the energy storage converter and the enterprise production loads.

[0010] The above technical solution is used to provide 10kV / 50HZ power to the 10kV high-voltage circuit breaker QF1.

[0011] Preferably, the system input side includes a 10KV high-voltage circuit breaker QF1, a phase-shifting transformer TR1, and a low-voltage circuit breaker QF2 connected in sequence. The 10KV high-voltage circuit breaker QF1 is connected to the microgrid interface, and the low-voltage circuit breaker QF2 is connected to the converter unit.

[0012] By adopting the above technical solution, the 10kV high-voltage circuit breaker QF1 is used to connect to the 10kV / 50HZ power supplied by the segmented 10kV microgrid, the phase-shifting transformer is used to step down the 10kV / 50Hz power to 480V low-voltage power and input it into the low-voltage circuit breaker, and the low-voltage circuit breaker QF2 is used to connect to the 480V / 50HZ power supplied by the segmented phase-shifting transformer.

[0013] Preferably, the converter unit adopts a three-level PWM rectification and a five-level H-bridge cascaded inverter bidirectional topology. The five-level H-bridge cascaded inverter bidirectional topology consists of 15 bidirectional power modules cascaded, with 5 modules per phase.

[0014] Preferably, the converter unit adopts a dual-machine hot standby system, that is, it is configured with two sets of converter units with the same parameters, and the parameters are synchronized in real time through the PLC control system, with a fault switching time of <50ms.

[0015] By adopting the above technical solution, the low-voltage power received through the low-voltage circuit breaker is converted into stable DC by the three-level PWM rectifier unit, and then accurately outputs 6.6kV / 60Hz and 11kV / 60Hz power through the five-level H-bridge inverter module to meet the power needs of ships of different tonnages when berthing.

[0016] Preferably, the system output side includes an output isolation transformer TR2, a 440V / 60HZ output circuit QF3, a 690V / 60HZ output circuit QF4, and 6.6kV / 60HZ and 11kV / 60HZ output circuits. The 6.6kV / 60HZ and 11kV / 60HZ output circuits include an excitation inrush current cabinet and a high-voltage output circuit breaker QF5.

[0017] By adopting the above technical solution, the inrush current cabinet includes an inrush current suppression resistor R and a high-voltage contactor KM1. Its function is to suppress the inrush current of the ship's transformer at the moment the high-voltage switchgear is closed after high-voltage power is supplied to the ship. The high-voltage outgoing cabinet includes a high-voltage vacuum circuit breaker QF5, which is used to disconnect and connect the high-voltage power from the converter unit, serving as a high-voltage power supply output to external loads.

[0018] Preferably, the operating method of a ship load test energy recovery device includes two modes: a forward shore power supply mode and a reverse energy feedback mode. I. The working method of forward shore power supply mode includes the following steps: Step 1: First, connect the 10kV / 50HZ high-voltage input power supply to the incoming side of the 10kV high-voltage circuit breaker QF1; Step 2: Operate and close the 10kV high-voltage circuit breaker QF1. Subsequently, the 10kV / 50HZ electrical energy is sent to the primary side of the phase-shifting transformer through the high-voltage connection cable. The 10kV / 50HZ high-voltage electrical energy is stepped down to 480V / 50Hz low-voltage electricity through the phase-shifting transformer and sent to the incoming side of the low-voltage circuit breaker QF2. Step 3: Operate to close the low-voltage circuit breaker QF2, then the three-level PWM rectifier section of the main unit of the converter unit is energized, the DC bus voltage is established, and the five-level H-bridge cascaded inverter can be started at any time; Step 4: Start the five-level H-bridge cascaded inverter of the host, and the inverter outputs 6.6kV / 60HZ or 11kV / 60HZ electrical energy to the primary side of the output isolation transformer on the system output side. The high voltage electrical energy is stepped down to 440V / 60HZ and 690V / 60HZ electrical energy through the output isolation transformer, and is also transmitted to the incoming side of the high voltage output circuit breaker through the resistor R of the excitation inrush current cabinet. Step 5: Operate and close the high-voltage circuit breaker QF5 to supply 6.6kV / 60HZ or 11kV / 60HZ power to the ship side to meet the power needs of ships of different tonnages when berthing. After the high-voltage power supply is supplied to the ship, the resistor is used to suppress the inrush current of the ship's transformer when the high-voltage switch cabinet is closed. Before the load is transferred from the ship side to the shore power, operate and close KM1 to prevent the resistor from burning out. Step 6: If the 440V / 60HZ circuit breaker QF4 is closed, 440V / 60HZ power will be supplied to the ship's side. If the 690V / 60HZ circuit breaker QF3 is closed, 440V / 60HZ power will be supplied to the ship's side. II. The working method of the reverse energy feedback mode, which replaces the core function of the traditional dry-type resistance box, realizes energy recovery during the ship load characteristic test phase, including the following steps: Step 1, Energy Harvesting: The feedback power output from the ship's generator is connected to the shore power equipment via the ship's base junction box. The feedback power is then connected to the five-level H-bridge unit of the main engine via the high-voltage output circuit breaker QF5, the 440V / 60HZ circuit breaker QF4, or the 690V / 60HZ circuit breaker QF3. The main engine's five-level H-bridge unit then rectifies the power into DC. Step 2, grid adaptation: The three-level PWM inverter unit converts DC to 0.48kV / 50Hz low-voltage power frequency, which is then fed back to the 10KV microgrid via a phase-shifting transformer and a 10KV high-voltage circuit breaker QF1. The power factor can be adjusted to 0.95-1.0. Step 3: Feedback power is prioritized for supplying the enterprise's production load, and the surplus is stored in the energy storage device through the microgrid interface. When the energy storage device discharges, it can smooth out the peak-valley difference of the power grid.

[0019] The advantages of this invention are as follows: 1. This invention enables bidirectional and efficient conversion: the fully controllable power electronic topology replaces the uncontrollable rectifier structure, realizing bidirectional energy flow and solving the pain point that traditional shore power sources cannot feed back reverse power to the grid. Moreover, the fed-back power is prioritized for supplying enterprise production loads, and the surplus is stored in the energy storage device through the microgrid interface. When the energy storage device discharges, it can smooth out the peak-valley difference of the grid, thus eliminating the safety threat of reverse power to shore power equipment from the root.

[0020] 2. This invention adopts a redundant and reliable design with dual-machine hot standby and a modular structure. When a single module fails, the system operates at reduced capacity, eliminating the risk of single point of failure. This is of great significance for the safe and stable operation of the equipment.

[0021] 3. This invention can output low-voltage power at 440V / 60Hz and 690V / 60Hz, as well as high-voltage power at 6kV / 50Hz, 6.6kV / 60Hz, 10kV / 50Hz, and 11kV / 60Hz. The voltage levels and electrical systems that can be output cover all the low / high voltage levels and electrical systems commonly used by ships in port in the actual application scenarios of existing ship shore power, and can meet the power supply needs of almost all ship types after berthing.

[0022] 4. This invention adopts a control strategy based on V / f droop to achieve frequency / voltage coordinated regulation with the enterprise microgrid, and feedback power is connected to the grid without impact. Attached Figure Description

[0023] Figure 1 This is a schematic diagram of the primary system of the ship load test energy recovery device of the present invention; Detailed Implementation

[0024] The technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present invention.

[0025] like Figure 1 As shown, a ship load test power recovery device includes a 10kV microgrid, a system input side, a converter unit, and a system output side. The 10kV microgrid is connected to the system input side and the converter unit. The converter unit includes a main unit structure and a backup unit structure, which are connected in parallel and controlled by a PLC. The converter unit is connected to the system output side.

[0026] The 10kV microgrid includes an energy management module, an energy storage converter, an energy storage battery pack, and enterprise production loads. The energy storage battery pack and the energy storage converter are connected in parallel with the enterprise production loads, and a microgrid interface connects the energy storage converter and the enterprise production loads.

[0027] It is used to supply 10kV / 50HZ power to the 10kV high-voltage circuit breaker QF1.

[0028] The system input side includes a 10kV high-voltage circuit breaker QF1, a phase-shifting transformer TR1, and a low-voltage circuit breaker QF2 connected in sequence. The 10kV high-voltage circuit breaker QF1 is connected to the microgrid interface, and the low-voltage circuit breaker QF2 is connected to the converter unit.

[0029] The 10kV high-voltage circuit breaker QF1 is used to connect to the 10kV / 50HZ power supplied by the segmented 10kV microgrid. The phase-shifting transformer is used to step down the 10kV / 50Hz power to 480V low-voltage power and input it into the low-voltage circuit breaker. The low-voltage circuit breaker QF2 is used to connect to the 480V / 50HZ power supplied by the segmented phase-shifting transformer.

[0030] The converter unit adopts a three-level PWM rectification and a five-level H-bridge cascaded inverter bidirectional topology. The five-level H-bridge cascaded inverter bidirectional topology consists of 15 bidirectional power modules cascaded, 5 per phase.

[0031] The converter unit adopts a dual-machine hot standby system, that is, it is equipped with two sets of converter units with the same parameters. The parameters are synchronized in real time through the PLC control system, and the fault switching time is <50ms.

[0032] It receives low-voltage power connected via a low-voltage circuit breaker, converts it into stable DC power through a three-level PWM rectifier unit, and then accurately outputs 6.6kV / 60Hz and 11kV / 60Hz power through a five-level H-bridge inverter module to meet the power needs of ships of different tonnages when berthing.

[0033] The system output side includes an output isolation transformer TR2, a 440V / 60HZ output circuit QF3, a 690V / 60HZ output circuit QF4, and 6.6kV / 60HZ and 11kV / 60HZ output circuits. The 6.6kV / 60HZ and 11kV / 60HZ output circuits include an excitation inrush current cabinet and a high-voltage output circuit breaker QF5.

[0034] The inrush current cabinet contains an inrush current suppression resistor R and a high-voltage contactor KM1. Its function is to suppress the inrush current of the ship's transformer when the high-voltage switchgear is closed after high-voltage power is supplied to the ship. The high-voltage outgoing line cabinet contains a high-voltage vacuum circuit breaker QF5, which is used to disconnect and connect the high-voltage power from the converter unit, providing high-voltage power output to external loads.

[0035] A method for operating a ship load test energy recovery device includes two modes: a forward shore power supply mode and a reverse energy feedback mode. I. The working method of forward shore power supply mode includes the following steps: Step 1: First, connect the 10kV / 50HZ high-voltage input power supply to the incoming side of the 10kV high-voltage circuit breaker QF1; Step 2: Operate and close the 10kV high-voltage circuit breaker QF1. Subsequently, the 10kV / 50HZ electrical energy is sent to the primary side of the phase-shifting transformer through the high-voltage connection cable. The 10kV / 50HZ high-voltage electrical energy is stepped down to 480V / 50Hz low-voltage electricity through the phase-shifting transformer and sent to the incoming side of the low-voltage circuit breaker QF2. Step 3: Operate to close the low-voltage circuit breaker QF2, then the three-level PWM rectifier section of the main unit of the converter unit is energized, the DC bus voltage is established, and the five-level H-bridge cascaded inverter can be started at any time; Step 4: Start the five-level H-bridge cascaded inverter of the host, and the inverter outputs 6.6kV / 60HZ or 11kV / 60HZ electrical energy to the primary side of the output isolation transformer on the system output side. The high voltage electrical energy is stepped down to 440V / 60HZ and 690V / 60HZ electrical energy through the output isolation transformer, and is also transmitted to the incoming side of the high voltage output circuit breaker through the resistor R of the excitation inrush current cabinet. Step 5: Operate and close the high-voltage circuit breaker QF5 to supply 6.6kV / 60HZ or 11kV / 60HZ power to the ship side to meet the power needs of ships of different tonnages when berthing. After the high-voltage power supply is supplied to the ship, the resistor is used to suppress the inrush current of the ship's transformer when the high-voltage switch cabinet is closed. Before the load is transferred from the ship side to the shore power, operate and close KM1 to prevent the resistor from burning out. Step 6: If the 440V / 60HZ circuit breaker QF4 is closed, 440V / 60HZ power will be supplied to the ship's side. If the 690V / 60HZ circuit breaker QF3 is closed, 440V / 60HZ power will be supplied to the ship's side. II. The working method of the reverse energy feedback mode, which replaces the core function of the traditional dry-type resistance box, realizes energy recovery during the ship load characteristic test phase, including the following steps: Step 1, Energy Harvesting: The feedback power output from the ship's generator is connected to the shore power equipment via the ship's base junction box. The feedback power is then connected to the five-level H-bridge unit of the main engine via the high-voltage output circuit breaker QF5, the 440V / 60HZ circuit breaker QF4, or the 690V / 60HZ circuit breaker QF3. The main engine's five-level H-bridge unit then rectifies the power into DC. Step 2, grid adaptation: The three-level PWM inverter unit converts DC to 0.48kV / 50Hz low-voltage power frequency, which is then fed back to the 10KV microgrid via a phase-shifting transformer and a 10KV high-voltage circuit breaker QF1. The power factor can be adjusted to 0.95-1.0. Step 3: Feedback power is prioritized for supplying the enterprise's production load, and the surplus is stored in the energy storage device through the microgrid interface. When the energy storage device discharges, it can smooth out the peak-valley difference of the power grid.

[0036] Those skilled in the art should understand that the embodiments of the present invention described above and shown in the accompanying drawings are merely examples and do not limit the present invention; the objectives of the present invention have been fully and effectively achieved. The functions and structural principles of the present invention have been demonstrated and explained in the embodiments, and any modifications or variations of the embodiments of the present invention may be made without departing from the stated principles.

Claims

1. A ship load test energy recovery device, comprising a 10KV microgrid section, a system input side, a converter unit section, and a system output side, characterized in that: The 10kV microgrid is connected to the system input side and the converter unit section. The converter unit section includes a main unit structure and a standby unit structure, which are connected in parallel and controlled by a PLC. The converter unit section is connected to the system output side.

2. The energy recovery device for ship load testing according to claim 1, characterized in that: The 10kV microgrid includes an energy management module, an energy storage converter, an energy storage battery pack, and enterprise production loads. The energy storage battery pack and the energy storage converter are connected in parallel with the enterprise production loads, and a microgrid interface is connected between the energy storage converter and the enterprise production loads.

3. The energy recovery device for ship load testing according to claim 1, characterized in that: The system input side includes a 10KV high-voltage circuit breaker QF1, a phase-shifting transformer TR1, and a low-voltage circuit breaker QF2 connected in sequence. The 10KV high-voltage circuit breaker QF1 is connected to the microgrid interface, and the low-voltage circuit breaker QF2 is connected to the converter unit.

4. The energy recovery device for ship load testing according to claim 1, characterized in that: The converter unit adopts a three-level PWM rectification and a five-level H-bridge cascaded inverter bidirectional topology. The five-level H-bridge cascaded inverter bidirectional topology consists of 15 bidirectional power modules cascaded, with 5 modules per phase.

5. The energy recovery device for ship load testing according to claim 1, characterized in that: The converter unit adopts a dual-machine hot standby system, that is, it is configured with two sets of converter units with the same parameters, and the parameters are synchronized in real time through the PLC control system, with a fault switching time of <50ms.

6. The energy recovery device for ship load testing according to claim 1, characterized in that: The system output side includes an output isolation transformer TR2, a 440V / 60HZ output circuit QF3, a 690V / 60HZ output circuit QF4, and 6.6kV / 60HZ and 11kV / 60HZ output circuits. The 6.6kV / 60HZ and 11kV / 60HZ output circuits include an excitation inrush current cabinet and a high-voltage output circuit breaker QF5.

7. The operating method of the ship load test energy recovery device according to claim 1, comprising two modes, wherein the two modes are a forward shore power supply mode and a reverse energy feedback mode, characterized in that: I. The working method of forward shore power supply mode includes the following steps: Step 1: First, connect the 10kV / 50HZ high-voltage input power supply to the incoming side of the 10kV high-voltage circuit breaker QF1; Step 2: Operate and close the 10kV high-voltage circuit breaker QF1. Subsequently, the 10kV / 50HZ electrical energy is sent to the primary side of the phase-shifting transformer through the high-voltage connection cable. The 10kV / 50HZ high-voltage electrical energy is stepped down to 480V / 50Hz low-voltage electricity through the phase-shifting transformer and sent to the incoming side of the low-voltage circuit breaker QF2. Step 3: Operate to close the low-voltage circuit breaker QF2, then the three-level PWM rectifier section of the main unit of the converter unit is energized, the DC bus voltage is established, and the five-level H-bridge cascaded inverter can be started at any time; Step 4: Start the five-level H-bridge cascaded inverter of the host, and the inverter outputs 6.6kV / 60HZ or 11kV / 60HZ electrical energy to the primary side of the output isolation transformer on the system output side. The high voltage electrical energy is stepped down to 440V / 60HZ and 690V / 60HZ electrical energy through the output isolation transformer, and is also transmitted to the incoming side of the high voltage output circuit breaker through the resistor R of the excitation inrush current cabinet. Step 5: Operate and close the high-voltage circuit breaker QF5 to supply 6.6kV / 60HZ or 11kV / 60HZ power to the ship side to meet the power needs of ships of different tonnages when berthing. After the high-voltage power supply is supplied to the ship, the resistor is used to suppress the inrush current of the ship's transformer when the high-voltage switch cabinet is closed. Before the load is transferred from the ship side to the shore power, operate and close KM1 to prevent the resistor from burning out. Step 6: If the 440V / 60HZ circuit breaker QF4 is closed, 440V / 60HZ power will be supplied to the ship's side. If the 690V / 60HZ circuit breaker QF3 is closed, 440V / 60HZ power will be supplied to the ship's side. II. The working method of the reverse energy feedback mode includes the following steps: Step 1, Energy Harvesting: The feedback power output from the ship's generator is connected to the shore power equipment via the ship's base junction box. The feedback power is then connected to the five-level H-bridge unit of the main engine via the high-voltage output circuit breaker QF5, the 440V / 60HZ circuit breaker QF4, or the 690V / 60HZ circuit breaker QF3. The main engine's five-level H-bridge unit then rectifies the power into DC. Step 2, grid adaptation: The three-level PWM inverter unit converts DC to 0.48kV / 50Hz low-voltage power frequency, which is then fed back to the 10KV microgrid via a phase-shifting transformer and a 10KV high-voltage circuit breaker QF1. The power factor can be adjusted to 0.95-1.

0. Step 3: Feedback power is prioritized for supplying the enterprise's production load, and the surplus is stored in the energy storage device through the microgrid interface. When the energy storage device discharges, it can smooth out the peak-valley difference of the power grid.

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