Multi-energy complementary micro-grid system based on ocean power generation

Abstract

The invention belongs to the technical field of renewable energy utilization, and particularly relates to a multi-energy complementary micro-grid system based on ocean energy power generation. Ocean energy which has continuity and is not influenced by illumination and climate is added in a traditional ocean power supply micro-grid system. The ocean energy generator is used for continuously converting ocean energy into electric energy, clean energy is provided for the multi-energy complementary micro-grid, the use of a diesel generating set is further reduced and avoided, the maintenance frequency and the maintenance cost of the multi-energy complementary micro-grid system are reduced, and the environmental friendliness of the multi-energy complementary micro-grid system is improved. A traditional ocean power supply micro-grid system architecture is optimized, a multi-stage energy conversion mode combining direct-current grid connection and alternating-current grid connection is adopted, direct direct-current grid connection of preceding-stage energy is carried out through a power diode, an alternating-current grid connection cabinet which is complex in structure and high in cost is not needed, the equipment cost and the system complexity of the multi-energy complementary micro-grid system are reduced, and the system reliability is improved. And meanwhile, the reliability of the multi-energy complementary system can be improved.

Description

Technical Field

[0001] This invention belongs to the field of renewable energy utilization technology, specifically relating to a multi-energy complementary microgrid system based on ocean energy power generation. Background Technology

[0002] The development and utilization of marine renewable energy is a hot topic and a challenge for major maritime nations around the world. Tidal energy and wave energy are widely distributed renewable energy sources in the ocean.

[0003] In response to marine pollution and marine resource development, marine energy is a clean and renewable energy source. Microgrid systems based on marine energy power generation can replace traditional power generation systems and be used to supply power to marine engineering platforms, navigation aids, marine ranches, and other isolated marine islands. This enables the development and utilization of renewable and clean energy, reduces or eliminates emissions pollution from chemical fuels in power supply systems for marine islands and marine ranches, and also compensates for the intermittent nature of solar and wind power generation.

[0004] In existing technologies, a combination of traditional diesel generator sets and solar (photovoltaic) power is used to provide electricity for marine ranches, platforms, and islands. Small-scale domestic electricity use photovoltaic power, while diesel generator sets are used for high-power production operations or when sunlight is insufficient. However, existing technologies still have the following problems: 1. Solar power supply is low and unstable, requiring frequent switching of power supply methods, and occasional power outages occur during the automatic switching process; 2. Solar power cannot be used when sunlight is insufficient or at night; 3. Diesel generator sets have high maintenance costs, pollute the environment with emissions, and generate vibration and noise.

[0005] In view of this, the present invention is proposed to solve the problems existing in the prior art. Summary of the Invention

[0006] The purpose of this invention is to overcome the shortcomings of the prior art and provide a multi-energy complementary microgrid system based on ocean energy power generation.

[0007] To achieve the above objectives, the present invention provides the following technical solution: This invention provides a multi-energy complementary microgrid system based on ocean energy power generation, comprising: The DC input network includes a first DC bus and a second DC bus. A normally open first bus tie switch is provided between the first DC bus and the second DC bus. The first DC bus is connected to an AC wind turbine and an AC ocean energy generator, respectively. The second DC bus is connected to multiple photovoltaic panel arrays. A DC-DC conversion network includes a third DC bus and a fourth DC bus. A normally closed second bus tie switch is provided between the third DC bus and the fourth DC bus. The third DC bus is connected to the first DC bus through a first power conversion module. The second DC bus is connected to the fourth DC bus through a second power conversion module. The fourth DC bus is also connected to a battery pack for storing and discharging energy. A 400Vac AC network, comprising a first AC bus, which is connected to a third DC bus via a first DC-AC bidirectional conversion system and to a fourth DC bus via a second DC-AC bidirectional conversion system. The first AC bus is also connected to multiple diesel generator sets and to a 380V load. The 230Vac AC network includes a second AC bus, which is connected to a first AC bus via multiple second transformers. The second AC bus is connected to a 220V load, and the second transformer is a household transformer.

[0008] Specifically, the AC wind turbine is connected to the first DC bus via a first diode module and a first fast fuse in sequence, and the AC ocean energy generator is connected to the first DC bus via a second diode module and a second fast fuse; each photovoltaic panel array is connected to the second DC bus via a third fast fuse.

[0009] Specifically, both the first DC-AC bidirectional conversion system and the second DC-AC bidirectional conversion system include a third power conversion module connected to the DC conversion network and a first transformer connected to the first AC bus. The third power conversion module is connected to the first transformer, and the first transformer is an isolation transformer.

[0010] Specifically, the first power conversion module and the second power conversion module are both choppers, and the third power conversion module is an inverter.

[0011] Specifically, the DC conversion network is connected to the third power conversion module in sequence through the first load switch and the first DC fast fuse, and the first transformer is connected to the first AC bus in sequence through the first electric control and the first AC fast fuse.

[0012] Specifically, the diesel generator set is connected to the first AC bus via a second electric control and a second AC fast fuse in sequence, and the diesel generator set consists of a diesel engine and a generator.

[0013] Specifically, the second transformer is connected to the second AC bus via a circuit breaker.

[0014] Specifically, the battery pack is connected to the fourth DC bus in sequence through the second DC fast fuse and the second load switch.

[0015] Specifically, both ends of the first bus tie switch and the second bus tie switch are equipped with a fourth fast fuse.

[0016] Specifically, this also includes EMS (Engineering Management System) used to coordinate the operation of key equipment in the control system.

[0017] Specifically, the 400Vac AC grid is connected to the DC-DC conversion grid via an inverter and an isolation transformer. The inverter converts the DC power from the DC-DC conversion grid into 400Vac AC power at a frequency of 50Hz to supply power to the 380Vac, 50Hz power load. The inverter's output can be adjusted within a range based on transmission line losses, adjusting the voltage and frequency accordingly. The diesel generator set's power is connected to the 400Vac AC grid, allowing for temporary starting of the diesel generator set in case of high-power loads or system emergencies. The 230Vac AC network is connected to the 400Vac AC network through a daytime transformer, and the daytime transformer converts the 400Vac, 50Hz power supply to the 230Vac, 50Hz power supply to power the 220Vac, 50Hz daily electrical loads.

[0018] Compared with the prior art, the technical solution provided by the present invention has the following beneficial effects: 1) This invention adds continuous ocean energy, unaffected by sunlight or weather, to traditional marine power microgrid systems. Ocean energy generators continuously convert ocean energy into electrical energy, providing clean energy for the multi-energy complementary microgrid. This further reduces and eliminates the use of diesel generator sets, lowers the maintenance frequency and cost of the multi-energy complementary microgrid system, and improves its environmental friendliness. 2) Optimize the traditional marine power supply microgrid system architecture by adopting a multi-stage energy conversion mode that combines DC grid connection and AC grid connection. Power diodes are used for direct DC grid connection of the front-end energy, eliminating the need for complex and costly AC grid connection cabinets. This reduces the equipment cost and system complexity of the multi-energy complementary microgrid system, while also improving the reliability of the multi-energy complementary system. 3) By adding an energy storage system, the system stores the electrical energy converted from wind and solar energy under surplus operating conditions and releases the electrical energy when wind and solar energy are scarce. This regulates the energy balance of the multi-energy complementary microgrid system, reduces wind and solar curtailment, maximizes the application of renewable and clean energy, and ensures that the energy storage system is connected to the grid for a long time and can avoid power outages. 4) The diesel generator set in the multi-energy complementary microgrid system changes its operating mode from normal output to emergency output, and only connects to the grid for a short time when the system is supplying power at high power, which greatly reduces the emissions of the diesel generator set. Attached Figure Description

[0019] The accompanying drawings are incorporated in and form part of this specification, and together with the description serve to explain the principles of the invention.

[0020] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, those skilled in the art can obtain other drawings based on these drawings without creative effort.

[0021] Figure 1 This is a schematic diagram of the multi-energy complementary microgrid system based on ocean energy power generation according to the present invention. Detailed Implementation

[0022] Exemplary embodiments will now be described in detail, examples of which are illustrated in the accompanying drawings. The embodiments described in the following exemplary embodiments do not represent all embodiments consistent with the present invention. Rather, they are merely examples consistent with some aspects of the invention as detailed in the appended claims.

[0023] To enable those skilled in the art to better understand the technical solutions of the present invention, the present invention will be further described in detail below with reference to the accompanying drawings and embodiments.

[0024] This embodiment provides a multi-energy complementary microgrid system based on ocean energy power generation. The energy sources can include wind energy, ocean energy, solar energy, fossil fuels, and electrochemical energy, which are converted into electrical energy through conversion devices such as wind turbines, ocean energy generators, photovoltaic panels, diesel generator sets, and lithium iron phosphate battery packs. Specifically, as follows... Figure 1 As shown, the microgrid system is divided into four layers of the power grid, which, from top to bottom according to the energy flow direction, are the DC input grid, DC conversion grid, 400Vac AC grid, and 230Vac AC grid, specifically including: The DC input network includes a first DC bus (designed voltage of 260~590Vdc) and a second DC bus (designed voltage of 90~550Vdc). A normally open first bus tie switch is provided between the first and second DC buses. The first DC bus is connected to a single AC wind turbine (30kW) and a single AC ocean energy generator (a single AC tidal current generator of 60kW). The second DC bus is connected to multiple photovoltaic panel arrays (each photovoltaic panel array has a power of 45kW and an output voltage of 100~550Vdc). Since the original input energy types of the first and second DC buses and the output voltage range of the conversion device are different, the first bus tie switch between them is normally open. Specifically, the AC wind turbine is connected to the first DC bus via a first three-phase full-bridge rectifier diode module and a first fast fuse (100A); the AC ocean energy generator is connected to the first DC bus via a second three-phase full-bridge rectifier diode module and a second fast fuse (200A); each photovoltaic panel array is connected to the second DC bus via a third fast fuse (150A). A DC-DC conversion network includes a third DC bus and a fourth DC bus. A normally closed second bus tie switch is provided between the third and fourth DC buses. The third DC bus is connected to the first DC bus via a first chopper, converting the 260~590Vdc voltage of the first DC bus to a 640Vdc level voltage. The second DC bus is connected to the fourth DC bus via a second chopper, converting the 90~550Vdc voltage of the second DC bus to an adjustable voltage of 640Vdc. The first and second choppers have the same specifications, with an input voltage of 90~750Vdc and a power of 100kW. The terminal connected to the DC input network is defined as the input terminal of the chopper, and the terminal connected to the DC conversion network is defined as the output terminal. After the DC conversion network voltage is converted, regulated, and output by the chopper, the voltage ranges of the third and fourth DC buses are the same, and the second bus tie switch between them is normally closed. The fourth DC bus is also connected to a battery pack for storing and discharging energy in sequence through a second load switch and a second DC fast fuse. The battery pack uses lithium iron phosphate batteries with an energy capacity of 196 kWh and a voltage range of 580~734 Vdc. It is connected to the fourth DC bus via a second load switch and a second DC fast fuse of appropriate specifications. The charging and discharging of the battery pack is controlled by controlling the grid-connected output voltage of two choppers, thereby achieving power smoothing for the entire microgrid. Furthermore, the energy storage battery pack can smooth power fluctuations in the microgrid system, reduce wind and solar curtailment, and maximize the utilization of renewable clean energy. The energy storage system can operate on the grid for a long time and avoid power outages. The battery pack can use various charging methods, including wind power, ocean energy, solar clean energy, and diesel generator sets, to maximize the energy storage function of the battery pack. The 400Vac AC network includes a first AC bus, which is connected to a third DC bus via a first DC-AC bidirectional conversion system and to a fourth DC bus via a second DC-AC bidirectional conversion system. The first AC bus is also connected to two identical diesel generator sets for emergency power supply. Each generator set has a power output of 300kW and an output voltage of 400Vac at 50Hz. The generator sets have automatic start / stop and automatic AC paralleling and disconnection functions, allowing seamless connection and disconnection when the microgrid needs high-power external power supply. If the load increases and the system is overloaded (e.g., the output power of a single generator set exceeds 90% of its rated power for 30 seconds), the standby generator set is started and automatically paralleled. If the load decreases (e.g., the output power of a single generator set is below 30% of its rated load for 5 minutes), the paralleled diesel generator set automatically transfers the load and disconnects from the system. The first AC bus is connected to a 380V load. Specifically, both the first and second DC-AC bidirectional conversion systems include a third power conversion module connected to the DC conversion network and a first transformer connected to the first AC bus. The third power conversion module is connected to the first transformer, which is an isolation transformer. The third power conversion module is an inverter with a single inverter power of 100kW and an output voltage of 400Vac at 50Hz. The isolation transformer has a capacity of 80kVA and a turns ratio of 400V / 400V. Specifically, the DC conversion network is connected to the third power conversion module in sequence through the first load switch, the first DC fast fuse, and the first transformer is connected to the first AC bus in sequence through the first electric operating circuit breaker and the first AC fast fuse. Specifically, the diesel generator set is connected to the first AC bus via a second electric control and a second AC fast fuse in sequence, and the diesel generator set consists of a diesel engine and a generator; Specifically, when the diesel generator set is put into operation, the battery pack can be charged through the DC-AC bidirectional conversion system. At this time, the inverter works in active rectification mode and can be used as a charger according to the working needs of the battery and the generator set, thereby improving the working efficiency of the generator set and making it work near the optimal fuel point, reducing emissions. In severe weather or severe sea conditions, the generator set can be put into operation to supply power, and the wind turbine and ocean energy generator can be stopped to prevent generator overload damage. The 230Vac AC network includes a second AC busbar, which is connected to a first AC busbar via multiple second transformers and circuit breakers. The second AC busbar is connected to a 220V load. The second transformer is a day-use transformer with a capacity of 30kVA and a turns ratio of 400V / 230V.

[0025] Specifically, both ends of the first bus tie switch and the second bus tie switch are equipped with a fourth fast fuse.

[0026] Specifically, it also includes an Energy Management System (EMS) for coordinating the operation of key equipment in the control system. This EMS can control the operation of wind turbines and ocean-powered generators according to system needs, and can control the chopper's output voltage, battery charging and discharging, inverter inversion and rectification, and the connection, disconnection, and paralleling / splitting of diesel generator sets. Specifically, the 400Vac AC grid is connected to the DC-DC converter grid via an inverter and isolation transformer. The inverter converts the DC power from the DC-DC converter grid into 400Vac AC power at a frequency of 50Hz to supply power to the 380Vac, 50Hz power load. The inverter's output can be adjusted within a range based on transmission line losses for voltage and frequency. The diesel generator sets' power is connected to the 400Vac AC grid, allowing for temporary starting of the diesel generator sets when high-power loads are applied or during system emergencies. The 230Vac AC network is connected to the 400Vac AC network through a daytime transformer, and the daytime transformer converts the 400Vac, 50Hz power supply to the 230Vac, 50Hz power supply to power the 220Vac, 50Hz daily electrical loads.

[0027] The above description is merely a specific embodiment of the present invention, enabling those skilled in the art to understand or implement the invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the invention.

[0028] It should be understood that the present invention is not limited to the content already described above, and various modifications and changes can be made without departing from its scope. The scope of the present invention is limited only by the appended claims.

Claims

1. A multi-energy complementary microgrid system based on ocean energy power generation, characterized in that, include: The DC input network includes a first DC bus and a second DC bus. A normally open first bus tie switch is provided between the first DC bus and the second DC bus. The first DC bus is connected to an AC wind turbine and an AC ocean energy generator, respectively. The second DC bus is connected to multiple photovoltaic panel arrays. A DC-DC conversion network includes a third DC bus and a fourth DC bus. A normally closed second bus tie switch is provided between the third DC bus and the fourth DC bus. The third DC bus is connected to the first DC bus through a first power conversion module. The second DC bus is connected to the fourth DC bus through a second power conversion module. The fourth DC bus is also connected to a battery pack for storing and discharging energy. A 400Vac AC network, comprising a first AC bus, which is connected to a third DC bus via a first DC-AC bidirectional conversion system and to a fourth DC bus via a second DC-AC bidirectional conversion system. The first AC bus is also connected to multiple diesel generator sets and to a 380V load. The 230Vac AC network includes a second AC bus, which is connected to a first AC bus via multiple second transformers, and the second AC bus is connected to a 220V load.

2. The multi-energy complementary microgrid system according to claim 1, characterized in that, The AC wind turbine is connected to the first DC bus via a first diode module and a first fast fuse in sequence; the AC ocean energy generator is connected to the first DC bus via a second diode module and a second fast fuse; each of the photovoltaic panel arrays is connected to the second DC bus via a third fast fuse.

3. The multi-energy complementary microgrid system according to claim 1, characterized in that, Both the first power conversion module and the second power conversion module are choppers.

4. The multi-energy complementary microgrid system according to claim 1, characterized in that, Both the first DC-AC bidirectional conversion system and the second DC-AC bidirectional conversion system include a third power conversion module connected to the DC conversion network and a first transformer connected to the first AC bus. The third power conversion module is connected to the first transformer.

5. The multi-energy complementary microgrid system according to claim 4, characterized in that, The DC conversion network is connected to the third power conversion module in sequence through the first load switch, the first DC fast fuse, and the first transformer is connected to the first AC bus in sequence through the first electric control and the first AC fast fuse.

6. The multi-energy complementary microgrid system according to claim 1, characterized in that, The diesel generator set is connected to the first AC bus via the second electric control and the second AC fast fuse in sequence.

7. The multi-energy complementary microgrid system according to claim 1, characterized in that, The second transformer is connected to the second AC bus via a circuit breaker.

8. The multi-energy complementary microgrid system according to claim 1, characterized in that, The battery pack is connected to the fourth DC bus in sequence through the second DC fast fuse and the second load switch.

9. The multi-energy complementary microgrid system according to claim 1, characterized in that, Both ends of the first bus tie switch and the second bus tie switch are equipped with a fourth fast fuse.

10. The multi-energy complementary microgrid system according to claim 1, characterized in that, It also includes EMS, which is used to coordinate the operation of key equipment in the control system.

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