An energy storage type ac-ac power converter system with peak shaving function

Abstract

The utility model discloses a kind of energy storage type AC-AC power converter systems with peak clipping and valley filling function, be set in the power supply side of high-frequency ac distribution system, with high power density, can be synergic control, conversion link is less, electric power loss is low and the characteristics and advantages of low etc. Including wind driven generator, AC / DC current source type converter, DC / DC battery energy storage system and DC / AC current source type high-frequency resonant converter, by synergic control so that energy storage type AC-AC power converter system can be flexibly switched between power transmission mode and energy storage mode, to show higher power conversion efficiency, more optimal volume and weight design, faster dynamic response speed, lower transmission loss and stronger fault removal capacity.

Description

Technical Field

[0001] This utility model belongs to the technical field of high-frequency AC power distribution systems, specifically relating to an energy storage AC-AC power converter system with peak shaving and valley filling functions. Background Technology

[0002] Traditional power systems rely heavily on fossil fuel power generation, resulting in significant environmental pollution. Therefore, the current mainstream approach is to drive power system transformation with a focus on reducing carbon emissions ("dual carbon") as the primary goal. With the development of semiconductor devices (such as SiC and GaN power devices), power electronics technology, the large-scale integration of renewable energy generation, and the increasing demand for power system stability, structural reforms are underway in the power system.

[0003] Compared to traditional power distribution systems, high-frequency AC power distribution systems have attracted widespread attention due to their inherent advantages such as high power density, high conversion efficiency, better adaptability to renewable energy integration, improved grid stability and reliability, and fast dynamic response. A high-frequency AC power distribution system consists of three parts: the high-frequency power supply side, the high-frequency transmission line, and the resonant rectifier load side. The high-frequency power supply side typically comprises AC / AC voltage-source converters with power factor correction. Compared to voltage-source converters, current-source resonant inverters have lower requirements for the voltage and current withstand levels of power devices, require no short-circuit protection, and have relatively simpler load matching, reducing the requirements for power devices and resulting in more stable circuit operation. In-depth research and utilization of these inverters will have high practical value.

[0004] However, current-source resonant inverters still have problems in high-frequency AC power distribution systems, such as complex control and high cost. Utility Model Content

[0005] This utility model addresses the various problems existing in the prior art by providing an AC-AC power converter system that is used for peak shaving and valley filling, located on the power supply side of a high-frequency AC power distribution system, capable of energy storage, and features high power density, coordinated control, fewer conversion stages, and low loss.

[0006] The specific technical solution adopted in this utility model is as follows:

[0007] An energy storage AC-AC power converter system with peak shaving and valley filling functions includes a wind turbine, an AC / DC current source converter, a DC / DC battery energy storage system, a DC / AC current source high-frequency resonant converter, and a low-frequency AC bus, a DC bus, and a high-frequency AC bus; wherein:

[0008] The wind turbine is connected to the low-frequency AC bus, the input terminal of the AC / DC current source converter is connected to the low-frequency AC bus, the output terminal of the AC / DC current source converter is connected to the DC bus, the input and output terminals of the DC / DC battery energy storage system are both connected to the DC bus, one end of the DC / AC current source high-frequency resonant converter is connected to the DC bus, and the other end of the DC / AC current source high-frequency resonant converter is connected to the high-frequency AC bus.

[0009] The AC / DC current source converter, the DC / DC battery energy storage system, and the DC / AC current source high-frequency resonant converter exchange electrical energy bidirectionally through the DC bus.

[0010] The energy storage AC-AC power converter system includes two operating modes: power transmission mode and energy storage mode.

[0011] Furthermore, in the power supply mode, the DC / DC battery energy storage system is further adjusted to store energy or supply power depending on whether the electrical energy generated by the wind turbine is sufficient.

[0012] Preferably, in the power supply mode, a first sensor monitors whether the electrical energy generated by the wind turbine is sufficient. If the first sensor detects that the electrical energy generated by the wind turbine is sufficient, the electrical energy generated by the wind turbine is transmitted to the DC bus via the low-frequency AC bus and the AC / DC current source converter. Then, it flows through the DC bus to the DC / DC battery energy storage system and the DC / AC current source high-frequency resonant converter, respectively. Thus, the DC / DC battery energy storage system completes the storage of excess electrical energy, and the DC / AC current source high-frequency resonant converter completes grid power supply via the high-frequency AC bus.

[0013] Preferably, in the power supply mode, the first sensor monitors whether the electrical energy generated by the wind turbine is sufficient. If the first sensor detects that the electrical energy generated by the wind turbine is insufficient, then on the one hand, the electrical energy generated by the wind turbine is transmitted to the DC bus through the low-frequency AC bus via the AC / DC current source converter, and then flows to the DC / AC current source high-frequency resonant converter through the DC bus. On the other hand, the DC / DC battery energy storage system releases the stored electrical energy, which flows to the DC / AC current source high-frequency resonant converter through the DC bus. After the electrical energy generated by the wind turbine and the electrical energy released by the DC / DC battery energy storage system converge on the DC bus, they are supplied to the grid through the DC / AC current source high-frequency resonant converter and the high-frequency AC bus.

[0014] Preferably, in the energy storage mode, the electrical energy generated by the wind turbine is transmitted to the DC bus via the low-frequency AC bus and the AC / DC current source converter; the electrical energy on the high-frequency AC bus is transmitted to the DC bus via the DC / AC current source high-frequency resonant converter; the electrical energy generated by the wind turbine and the electrical energy on the high-frequency AC bus are combined on the DC bus and then flow to the DC / DC battery energy storage system to complete energy storage.

[0015] Preferably, in the energy storage mode, a second sensor monitors whether the DC / DC battery energy storage system is full of stored energy. If the DC / DC battery energy storage system is full of stored energy, the DC / AC current source type high-frequency resonant converter is controlled to stop supplying energy to the DC bus.

[0016] Preferably, the power storage status of the DC / DC battery energy storage system is continuously recorded by a cloud server. If the DC / DC battery energy storage system is frequently in a fully charged state, a battery energy storage capacity expansion plan is executed.

[0017] Preferably, the DC / AC current source type high-frequency resonant converter has bidirectional flow function, operating in inverter mode in the power supply mode and in rectification mode in the energy storage mode.

[0018] Preferably, the DC / AC current source type high-frequency resonant converter adopts a CLLC architecture.

[0019] Preferably, the DC / AC current source type high-frequency resonant converter is a bidirectional full-bridge structure, and its load includes a first capacitor, a second capacitor, a first inductor, and a first resistor.

[0020] Preferably, the first capacitor forms the first branch, and the second capacitor, the first inductor, and the first resistor are connected in series to form the second branch.

[0021] Compared with the prior art, the present invention has the following beneficial effects:

[0022] (1) Because high-frequency AC systems allow the use of smaller and lighter passive components (such as inductors and transformers), the physical size and weight of the entire power distribution system can be significantly reduced, thereby increasing power density and giving the system a faster dynamic response capability.

[0023] (2) Compared with low-voltage DC power distribution, high-frequency AC schemes have fewer transmission links and higher power density, thus significantly reducing energy loss during energy transmission and providing stronger fault clearing capabilities. Attached Figure Description

[0024] Figure 1 This is a general framework diagram of an energy storage AC-AC power converter system with peak shaving and valley filling functions;

[0025] Figure 2 This is a schematic diagram of the operating mode of an energy storage AC-AC power converter system with peak shaving and valley filling functions. Detailed Implementation

[0026] The present invention will now be described in further detail with reference to the accompanying drawings, so that those skilled in the art can implement it based on the description. It should be understood that terms such as "having," "comprising," and "including" as used herein do not exclude the presence or addition of one or more other elements or combinations thereof.

[0027] The techniques described below can be modified in various ways and have multiple embodiments, which are described in detail below with reference to the accompanying drawings. However, this does not mean that the techniques described below are limited to the specific embodiments. It should be understood that this utility model includes all similar modifications, equivalents, and substitutions without departing from the spirit and scope of the techniques described below.

[0028] This invention provides an energy storage-type AC-AC power converter system with peak shaving and valley filling functions. It features high power density, coordinated control, fewer conversion stages, low loss, and fewer faults, and is used on the power supply side of high-frequency AC power distribution systems. The overall system framework is as follows: Figure 1 As shown.

[0029] This energy storage AC-AC power converter system with peak shaving and valley filling capabilities includes a wind turbine, an AC / DC current source converter, a DC / DC battery energy storage system, a DC / AC current source high-frequency resonant converter, and low-frequency AC buses, DC buses, and high-frequency AC buses; among which:

[0030] The wind turbine is connected to the low-frequency AC bus, the input terminal of the AC / DC current source converter is connected to the low-frequency AC bus, the output terminal of the AC / DC current source converter is connected to the DC bus, the input and output terminals of the DC / DC battery energy storage system are both connected to the DC bus, one end of the DC / AC current source high-frequency resonant converter is connected to the DC bus, and the other end of the DC / AC current source high-frequency resonant converter is connected to the high-frequency AC bus.

[0031] The AC / DC current source converter, the DC / DC battery energy storage system, and the DC / AC current source high-frequency resonant converter exchange electrical energy bidirectionally through the DC bus.

[0032] In other words, the electrical energy generated by the wind turbine enters the input terminal of the AC / DC current source converter through the low-frequency AC bus, and then enters the DC bus through the output terminal of the AC / DC current source converter. The DC / DC battery energy storage system can receive electrical energy from the DC bus through its input terminal to store electrical energy, and can also release the stored electrical energy to the DC bus through its output terminal to supply electrical energy. The DC / AC current source high-frequency resonant converter can flow bidirectionally. When it receives electrical energy from the DC bus and outputs it to the high-frequency AC bus, it supplies power to the grid; when it receives electrical energy from the high-frequency AC bus and outputs it to the DC bus, it stores energy for the battery.

[0033] like Figure 2 As shown, the energy storage AC-AC power converter system includes two operating modes: power transmission mode and energy storage mode.

[0034] Furthermore, in the power supply mode, the DC / DC battery energy storage system is further adjusted to store energy or supply power depending on whether the electrical energy generated by the wind turbine is sufficient.

[0035] In other words, this energy storage AC-AC power converter system can flexibly switch operating modes based on the relationship between power supply and power consumption. Specifically, during peak electricity consumption periods, when the wind turbine's power generation is sufficient and the power supply exceeds the power consumption, the overall power flow is as follows: from the wind turbine, through the AC / DC current source converter, to the DC bus; from the DC bus, it flows to the DC / DC battery energy storage system and the DC / AC current source high-frequency resonant converter; the DC / DC battery energy storage system stores excess power; and the DC / AC current source high-frequency resonant converter connects to the high-frequency AC bus to complete the required power transmission. When the wind turbine's power generation is insufficient and the power supply is less than the power consumption, the overall power flow is as follows: the power released from the wind turbine through the AC / DC current source converter and the DC / DC battery energy storage system flows into the DC bus; from the DC bus, it flows to the DC / AC current source high-frequency resonant converter; and finally, the DC / AC current source high-frequency resonant converter connects to the high-frequency AC bus to complete the required power transmission.

[0036] In more detail, under the power supply mode, the first sensor monitors whether the electrical energy generated by the wind turbine is sufficient. If the first sensor detects that the electrical energy generated by the wind turbine is sufficient, the electrical energy generated by the wind turbine is transmitted to the DC bus through the low-frequency AC bus via the AC / DC current source converter. Then, it flows through the DC bus to the DC / DC battery energy storage system and the DC / AC current source high-frequency resonant converter, respectively. Thus, the DC / DC battery energy storage system completes the storage of excess electrical energy, and the DC / AC current source high-frequency resonant converter completes the grid power supply through the high-frequency AC bus.

[0037] Furthermore, in the power supply mode, the first sensor monitors whether the electrical energy generated by the wind turbine is sufficient. If the first sensor detects that the electrical energy generated by the wind turbine is insufficient, on the one hand, the electrical energy generated by the wind turbine is transmitted to the DC bus through the low-frequency AC bus via the AC / DC current source converter, and then flows to the DC / AC current source high-frequency resonant converter through the DC bus. On the other hand, the DC / DC battery energy storage system releases the stored electrical energy, which flows to the DC / AC current source high-frequency resonant converter through the DC bus. After the electrical energy generated by the wind turbine and the electrical energy released by the DC / DC battery energy storage system converge on the DC bus, they are supplied to the grid through the DC / AC current source high-frequency resonant converter and the high-frequency AC bus.

[0038] When the power grid is in a low-demand period, the DC / DC battery energy storage system receives electrical energy through the DC bus at its input side. The DC / AC current source high-frequency resonant converter transmits electrical energy through the high-frequency AC bus, while the AC / DC current source converter transmits electrical energy to the wind turbine through the low-frequency AC bus. The AC / DC current source converter and the DC / AC current source high-frequency resonant converter then feed the electrical energy into the DC / DC battery energy storage system through the DC bus, completing the energy storage process.

[0039] In more detail, under the energy storage mode, the electrical energy generated by the wind turbine is transmitted to the DC bus via the low-frequency AC bus and the AC / DC current source converter; the electrical energy on the high-frequency AC bus is transmitted to the DC bus via the DC / AC current source high-frequency resonant converter; the electrical energy generated by the wind turbine and the electrical energy on the high-frequency AC bus are combined on the DC bus and then flow to the DC / DC battery energy storage system to complete energy storage.

[0040] Furthermore, in the energy storage mode, a second sensor monitors whether the DC / DC battery energy storage system is full. If the DC / DC battery energy storage system is full, the DC / AC current source type high-frequency resonant converter is controlled to stop supplying energy to the DC bus.

[0041] The DC / DC battery energy storage system can operate in either the first energy storage mode or the second energy storage mode. In the first energy storage mode, it simultaneously receives electrical energy from the wind turbine and the high-frequency AC bus, while in the second energy storage mode, it only receives electrical energy from the wind turbine.

[0042] The system continuously records the electrical energy stored in the DC / DC battery energy storage system via a cloud server. If the DC / DC battery energy storage system is frequently in a fully charged state, a battery energy storage capacity expansion plan is executed.

[0043] Both the first and second sensors communicate wirelessly with the cloud server. The cloud server continuously monitors the system status and historical operating data, performs intelligent analysis and prediction based on big data, adjusts the system's operating mode in a timely manner, and provides improvement suggestions based on the actual situation, thereby adjusting the system architecture and further improving the effective utilization rate of electrical energy.

[0044] The DC / AC current source type high-frequency resonant converter has bidirectional flow function, operating in inverter mode in power transmission mode and in rectification mode in energy storage mode.

[0045] The DC / AC current source type high-frequency resonant converter adopts a CLLC architecture.

[0046] The DC / AC current source type high-frequency resonant converter is a bidirectional full-bridge structure, and its load includes a first capacitor, a second capacitor, a first inductor, and a first resistor.

[0047] The first capacitor forms the first branch, and the second capacitor, the first inductor, and the first resistor are connected in series to form the second branch.

[0048] Compared to traditional DC power distribution systems, the high-frequency AC solution adopted in this utility model patent exhibits higher power conversion efficiency, more optimized size and weight design, faster dynamic response speed, lower transmission loss, and stronger fault clearing capability under the same input conditions. Its advantages are mainly reflected in the following aspects: First, because the high-frequency AC system allows the use of smaller and lighter passive components (such as inductors and transformers), the physical size and weight of the entire power distribution system can be significantly reduced, thereby increasing power density and giving the system faster dynamic response capability. Second, compared with low-voltage DC power distribution methods, the high-frequency AC solution has fewer transmission links and higher power density, thus significantly reducing losses during energy transmission.

[0049] Although the present invention has been described in detail above with general descriptions and specific embodiments, some modifications or improvements can be made to it. The above description is only a preferred embodiment of the present invention and is not limited to the scope of the present invention. Other changes and modifications made by those skilled in the art without departing from the spirit and protection scope of the present invention are still included within the protection scope of the present invention.

Claims

1. A storage-type AC-AC power converter system with peak shaving and valley filling functions, comprising a wind turbine generator, an AC / DC current source converter, a DC / DC battery energy storage system, a DC / AC current source high-frequency resonant converter, and a low-frequency AC bus, a DC bus, and a high-frequency AC bus; characterized in that: The wind turbine is connected to the low-frequency AC bus, the input terminal of the AC / DC current source converter is connected to the low-frequency AC bus, the output terminal of the AC / DC current source converter is connected to the DC bus, the input and output terminals of the DC / DC battery energy storage system are both connected to the DC bus, one end of the DC / AC current source high-frequency resonant converter is connected to the DC bus, and the other end of the DC / AC current source high-frequency resonant converter is connected to the high-frequency AC bus. The AC / DC current source converter, the DC / DC battery energy storage system, and the DC / AC current source high-frequency resonant converter exchange electrical energy bidirectionally through the DC bus. The energy storage AC-AC power converter system includes two operating modes: power transmission mode and energy storage mode. Furthermore, in the power supply mode, the DC / DC battery energy storage system is further adjusted to store energy or supply power depending on whether the electrical energy generated by the wind turbine is sufficient.

2. The system according to claim 1, characterized in that, It also includes a first sensor configured to monitor whether the electrical energy generated by the wind turbine is sufficient.

3. The system according to claim 2, characterized in that, It also includes a second sensor configured to monitor whether the DC / DC battery energy storage system is fully charged.

4. The system according to claim 3, characterized in that, It also includes a cloud server, which continuously records the electrical energy stored in the DC / DC battery energy storage system.

5. The system according to claim 4, characterized in that, Both the first and second sensors communicate wirelessly with the cloud server, which continuously monitors the system's status and historical operating data.

6. The system according to claim 1, characterized in that, The DC / AC current source type high-frequency resonant converter adopts a CLLC architecture.

7. The system according to claim 6, characterized in that, The DC / AC current source type high-frequency resonant converter is a bidirectional full-bridge structure, and its load includes a first capacitor, a second capacitor, a first inductor, and a first resistor.

8. The system according to claim 7, characterized in that, The first capacitor forms the first branch, and the second capacitor, the first inductor, and the first resistor are connected in series to form the second branch.

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