A multi-port flexible interconnect and power mutual assistance device
Through multi-port flexible interconnection and power mutual assistance devices, mutual assistance and seamless power transfer between AC and DC distribution networks are realized, solving the problems of unidirectional power supply in traditional low-voltage distribution network areas and the problem of new energy consumption, improving the stability and economic benefits of the power grid, and possessing power quality management functions.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- SUZHOU AIKE BORUI POWER SUPPLY TECH
- Filing Date
- 2026-04-22
- Publication Date
- 2026-06-02
- Estimated Expiration
- Not applicable · inactive patent
AI Technical Summary
The traditional low-voltage distribution network's unidirectional power supply mode and the difficulty in integrating new energy sources lead to grid instability and low economic benefits. Furthermore, seamless power transfer is difficult, and existing solutions suffer from high investment, low economic efficiency, or significant power outages for users.
The device employs a multi-port flexible interconnection and power exchange system, including AC/DC power distribution section, STS module, TRAN isolation transformer and Converter main power unit, to achieve AC/DC power exchange and seamless power transfer. Through grid-connected, off-grid and grid-connected-off-grid switching modes, combined with bidirectional anti-parallel thyristors and main control unit, it realizes grid voltage detection and fast switching.
It realizes mutual support between AC and DC distribution networks, solves the problems of grid stability and new energy consumption, improves power supply reliability and economic benefits, avoids power outages during transformer maintenance, and has power quality management functions.
Smart Images
Figure CN122136878A_ABST
Abstract
Description
Technical Field
[0001] This invention belongs to the field of AC / DC microgrids, specifically relating to a multi-port flexible interconnection and power mutual assistance device. Background Technology
[0002] Traditional low-voltage distribution networks typically employ a unidirectional radial power supply method from the transformer output side. This means power flow can only occur in one direction, and seamless power transfer cannot be achieved to ensure uninterrupted power supply in the event of transformer malfunctions or voltage flicker. Furthermore, as the grid connection coverage of new energy sources gradually increases, distribution areas face challenges in absorbing these resources and addressing photovoltaic power generation limitations, impacting grid stability and the economic benefits of new energy grid connection.
[0003] Meanwhile, with the development of the power energy internet, DC power grids have experienced rapid growth due to their higher power quality and natural adaptability to distributed energy sources and modern loads. The integrated application of DC and AC power grids has become a hot topic, with AC / DC interoperability and maximized energy utilization contributing to improved power quality and operational reliability of AC / DC distribution networks.
[0004] To address the aforementioned problems and needs, the commonly used solutions currently include: 1) To address the issue of photovoltaic power grid integration in the distribution area, a distribution area energy storage solution is adopted, with time-of-use charging and discharging. This solution suffers from high investment and low economic benefits. 2) Regarding the issue of seamless power transfer in a ring connection of an AC power grid, the traditional solution is to use line branch switches to perform switching operations. This operation will cause users to have a noticeable power outage and the operation time is long. Solving the aforementioned technical problems is a research direction that those skilled in the art are dedicated to. Summary of the Invention
[0005] The purpose of this invention is to overcome the shortcomings of the prior art and provide a multi-port flexible interconnection and power mutual assistance device.
[0006] To achieve the above objectives, the technical solution adopted by the present invention is: a multi-port flexible interconnection and power mutual assistance device, comprising an AC / DC power distribution section, an STS module, a TRAN isolation transformer, and a Converter main power unit, wherein the AC / DC power distribution section includes a QF1 AC side circuit breaker, a QF2 bypass circuit breaker, a QF3 uninterruptible power supply circuit breaker, an AC side surge protection device, a QF4 DC circuit breaker, and a DC side surge protection device; the STS module consists of bidirectional anti-parallel thyristors, a heat dissipation assembly, and a main control unit; the Converter main power unit is composed of multiple single-stage AC / DC bidirectional topologies connected in parallel; The QF1 AC side circuit breaker, STS module, and QF3 uninterruptible power supply circuit breaker are connected in series. The input terminal of the QF2 bypass circuit breaker is connected to the input terminal of the QF1 AC side circuit breaker, and the output terminal is connected to the output terminal of the QF3 uninterruptible power supply circuit breaker. The input terminal of the QF1 AC side circuit breaker is connected to the transformer substation, and the output terminal of the QF3 uninterruptible power supply circuit breaker is connected to the AC load. The TRAN isolation transformer, the Converter main power unit, and the QF4 DC circuit breaker are connected in series. The input terminal of the TRAN isolation transformer is connected to the output terminal of the STS module, and the output terminal of the QF4 DC circuit breaker is connected to the DC output. The AC-side surge protection device is connected to the output terminal of the QF1 AC-side circuit breaker, and the DC-side surge protection device is connected to the input terminal of the QF4 DC circuit breaker.
[0007] In one specific implementation, multiple stations are connected together, with the DC output terminals within each station area connected together.
[0008] As one specific implementation, the converter main power unit, under regulated state, has three modes: grid-connected, off-grid, and grid-connected / off-grid switching. In grid-connected mode, QF1 AC circuit breaker, STS module, QF3 uninterruptible power supply circuit breaker and QF4 DC circuit breaker are closed, and QF2 bypass circuit breaker is open. In off-grid mode, the QF1 AC circuit breaker, QF3 uninterruptible power supply circuit breaker, and QF4 DC circuit breaker are closed, while the STS module and QF2 bypass circuit breaker are open. On-grid and off-grid switching includes two processes: switching from on-grid to off-grid and switching from off-grid to on-grid. Specifically, During the switch from grid connection to off-grid, if the transformer area loses power, the main power unit of the Converter will detect the power failure and control the STS module to disconnect, changing the power supply from the transformer area to the off-grid output of the Converter. During the switch from off-grid to grid-connected operation, the voltage in the transformer area recovers. After the main power unit of the Converter detects the grid recovery, it controls the off-grid output voltage to synchronize with the phase of the grid in the transformer area. Once the two are in sync, the main power unit of the Converter controls the STS module to close, changing the power draw from the off-grid output of the Converter to direct power draw from the transformer area.
[0009] Due to the application of the above technical solution, the present invention has the following advantages compared with the prior art: This invention employs an interconnected approach between two or more devices to address the inability of traditional power distribution substations to handle voltage dips and prolonged low voltage. Each device includes an AC / DC power distribution section, an STS module, a TRAN isolation transformer, and a Converter main power unit. When two or more devices are interconnected, they integrate the AC / DC power distribution network, achieving mutual support between AC and DC, and between AC and DC, maximizing energy utilization. Simultaneously, this connection method solves the problem of power outages during transformer maintenance and power transfer, while also providing power quality management functions. Attached Figure Description
[0010] Figure 1 This is a topology diagram of a single multi-port flexible interconnection and power mutual assistance device. Figure 2 This is a scene diagram showing the interconnection of two of the aforementioned multi-port flexible interconnection and power mutual assistance devices; Figure 3 This diagram illustrates the access method of the AC / DC distribution network after the two multi-port flexible interconnection and power mutual assistance devices are interconnected. Figure 4 for Figure 3 Diagram showing the AC power flow direction after the two multi-port flexible interconnection and power mutual assistance devices are interconnected. Figure 5 This is a schematic diagram of the power flow direction under AC / DC power mutual assistance state after the two multi-port flexible interconnection and power mutual assistance devices are interconnected. Figure 6 This is a schematic diagram of the power flow direction under the AC single-port power failure and power transfer state after the two multi-port flexible interconnection and power mutual assistance devices are interconnected. Figure 7 This is a schematic diagram of the power flow direction under the AC multi-port power failure and power transfer state after the two multi-port flexible interconnection and power mutual assistance devices are interconnected. Detailed Implementation
[0011] The technical solution of the present invention will be further described below with reference to the accompanying drawings and specific embodiments.
[0012] This invention proposes a multi-port flexible interconnection and power mutual assistance device, including an AC / DC power distribution section, an STS module, a TRAN isolation transformer, and a Converter main power unit.
[0013] The AC / DC power distribution section includes QF1 AC side circuit breaker, QF2 bypass circuit breaker, QF3 uninterruptible power supply circuit breaker, AC side surge protection device, QF4 DC circuit breaker, and DC side surge protection device. This section mainly serves as the main component for connecting the system to the external DC power grid, while the QF2 bypass circuit breaker is used as a backup bypass protection switch in case of STS module failure.
[0014] The STS module consists of bidirectional anti-parallel thyristors, a heat dissipation assembly, and a main control unit. The STS module primarily functions as a grid voltage detection and judgment unit, achieving isolation between the internal units of the device and the grid. When an abnormal grid voltage is detected (exceeding the set high or low threshold range), it automatically disconnects from the grid; when the grid voltage is detected to be normal, it achieves seamless grid connection.
[0015] The main purpose of TRAN isolation transformers is to achieve isolation between power units and the power grid. The main considerations for configuring them are: 1) When special conditions such as short circuits occur on the grid side, they can slow down the current rise rate of the converter, thereby lengthening the response time of module protection and improving safety; 2) Isolating DC components; 3) Improving the ability to carry unbalanced loads off the grid.
[0016] The converter's main power unit is composed of multiple single-stage AC / DC bidirectional topologies connected in parallel, enabling black start on both AC and DC sides. It operates in two modes: voltage regulation mode and PQ mode. The voltage regulation mode further includes three modes: grid-connected, off-grid, and grid-connected / off-grid switching. Specifically, in grid-connected mode, the QF1 AC circuit breaker, STS module, QF3 uninterruptible power supply circuit breaker, and QF4 DC circuit breaker are closed, while the QF2 bypass circuit breaker is open. In off-grid mode, the QF1 AC circuit breaker, QF3 uninterruptible power supply circuit breaker, and QF4 DC circuit breaker are closed, while the STS module and QF2... When the bypass circuit breaker trips, and the transformer area loses power during the switch from grid-connected to off-grid operation, the main power unit of the Converter detects the power outage and controls the STS module to disconnect, changing the power draw from the transformer area to the off-grid output of the Converter. During the switch from off-grid to grid-connected operation, when the transformer area voltage recovers, the main power unit of the Converter detects the grid recovery and controls the off-grid output voltage to synchronize with the phase of the transformer area's grid. Once they are synchronized, the main power unit of the Converter controls the STS module to close, changing the power draw from the off-grid output of the Converter to direct power draw from the transformer area.
[0017] See Figure 1 As shown, in this multi-port flexible interconnection and power mutual assistance device, the QF1 AC side circuit breaker, STS module, and QF3 uninterruptible power supply circuit breaker are connected in series. The input terminal of the QF2 bypass circuit breaker is connected to the input terminal of the QF1 AC side circuit breaker, and the output terminal is connected to the output terminal of the QF3 uninterruptible power supply circuit breaker. The input terminal of the QF1 AC side circuit breaker is connected to the transformer substation, and the output terminal of the QF3 uninterruptible power supply circuit breaker is connected to the AC load. The TRAN isolation transformer, Converter main power unit, and QF4 DC circuit breaker are connected in series. The input terminal of the TRAN isolation transformer is connected to the output terminal of the STS module, and the output terminal of the QF4 DC circuit breaker is connected to the DC output. The AC side surge protection device is connected to the output terminal of the QF1 AC side circuit breaker, and the DC side surge protection device is connected to the input terminal of the QF4 DC circuit breaker.
[0018] Example
[0019] See Figure 2 As shown, Figure 2 The two devices are interconnected via the DC side, enabling flexible AC-DC-AC distribution network connections and multi-port routing. Detailed access methods for the devices and AC / DC distribution networks can be found in [link to documentation]. Figure 3 As shown.
[0020] There are two application scenarios for interconnecting two devices: 1) AC power mutual assistance; 2) AC-DC power mutual assistance; 3) AC single-port power failure transfer; 4) AC multi-port power failure transfer.
[0021] I. When AC power is mutually supplied, the power flow direction is as follows: Figure 4 As shown.
[0022] When two devices are interconnected, the DC source load on the DC line is not selected. At this time, there are two main circuits (taking device 1 in the figure as an example, device 2 is the same as device 1): 1) The first circuit is: Area I → QF1 AC side circuit breaker → STS module → QF3 uninterruptible power supply circuit breaker → AC load; 2) The second circuit is: Substation I → QF1 AC side circuit breaker → STS module → TRAN isolation transformer → Converter main power unit → QF4 DC circuit breaker → DC line.
[0023] The DC lines of the two transformer areas are interconnected, so that under normal operating conditions, the power of transformer area I and transformer area II can flow through the DC lines. The magnitude and direction of the power flow are controlled by the main power unit.
[0024] II. When AC and DC power are mutually balanced, the power flow direction is as follows: Figure 5 As shown.
[0025] The two devices are interconnected, and a DC source load is configured on the DC line. At this time, there are 3 main circuits (taking device 1 in the figure as an example, device 2 is the same as device 1): 1) The first circuit is: Area I → QF1 AC side circuit breaker → STS module → QF3 uninterruptible power supply circuit breaker → AC load; 2) The second circuit is: Substation I → QF1 AC side circuit breaker → STS module → TRAN isolation transformer → Converter main power unit → QF4 DC circuit breaker → DC line; 3) The third circuit is: the DC output lines of device 1 and device 2 are connected and then connected to the DC source load; After the two district DC lines are interconnected, a DC power source is connected to achieve the following under normal operating conditions: When the DC load is heavy and the DC source power is insufficient, power can flow through the DC lines of transformer area I or transformer area II to support the DC side. The magnitude and direction of the power flow are controlled by the main power unit. When the DC load is light and the DC source has a large surplus, power can flow through the DC lines of transformer area I or transformer area II to support the AC side. The magnitude and direction of the power flow are controlled by the main power unit.
[0026] III. When switching power from a single AC port after a power outage, refer to the power flow direction. Figure 6 As shown.
[0027] A DC power source is configured on the DC line. When the AC side single-port transformer area I loses power, the STS module in device 1 detects the power loss of the AC port and quickly and actively disconnects from the grid. At the same time, the main power unit quickly switches from the original power mutual assistance mode to the off-grid output mode to obtain energy from the DC line. The STS module uses an electronic switch to ensure uninterrupted power supply to the AC load of transformer area I during the switching process.
[0028] At this point, there are 3 main circuits: 1) The first circuit is: Area II → QF1 AC side circuit breaker → STS module → QF3 uninterruptible power supply circuit breaker → AC load; 2) The second circuit is: Substation II → QF1 AC side circuit breaker → STS module → TRAN isolation transformer → Converter main power unit → QF4 DC circuit breaker → DC line; 3) After the DC output lines of Device 1 and Device 2 are connected, they are connected to the DC source load.
[0029] After power loss in transformer area I, the following two operating modes can be achieved: When the DC load is heavy and the DC source power is insufficient, power can flow through the DC line of transformer area II to support the DC side load and supply the off-grid inverter output of the main power unit of transformer area I to power the AC load of transformer area I. The magnitude and direction of the power flow are controlled by the main power unit of device II. When the DC load is light and the DC source has a large surplus, the DC source can support the DC side load and supply the AC load of the main power unit of the transformer substation I to the off-grid inverter output. The magnitude and direction of power flow are affected by the power of the DC source.
[0030] IV. When switching power from AC multi-port to AC after a power outage, refer to the power flow direction. Figure 7 As shown.
[0031] A DC power source is configured on the DC line. When the AC side multi-port transformer area I and transformer area II lose power, the STS modules in device 1 and device 2 detect the power loss of the AC port and quickly and actively disconnect from the grid. At the same time, the main power unit quickly switches from the original power mutual assistance mode to the off-grid output mode to obtain energy from the DC line. Electronic switches are used in the STS module to ensure uninterrupted power supply to the AC loads of transformer area I and transformer area II during the switching process.
[0032] At this point, there are 2 main circuits: 1) The first circuit is: DC source to transformer area I: DC source → QF4 DC circuit breaker → Converter main power unit → TRAN isolation transformer → QF3 uninterruptible power supply circuit breaker → AC load of transformer area I; 2) The second circuit is: DC source to transformer area II: DC source → QF4 DC circuit breaker → Converter main power unit → TRAN isolation transformer → QF3 uninterruptible power supply circuit breaker → transformer area II AC load.
[0033] The above embodiments are only for illustrating the technical concept and features of the present invention, and are intended to enable those skilled in the art to understand the content of the present invention and implement it accordingly. They should not be construed as limiting the scope of protection of the present invention. All equivalent changes or modifications made in accordance with the spirit and essence of the present invention should be covered within the scope of protection of the present invention.
Claims
1. A multi-port flexible interconnection and power mutual assistance device, characterized in that, The system includes an AC / DC power distribution section, an STS module, a TRAN isolation transformer, and a Converter main power unit. The AC / DC power distribution section includes a QF1 AC-side circuit breaker, a QF2 bypass circuit breaker, a QF3 uninterruptible power supply circuit breaker, an AC-side surge protection device, and a QF4 DC circuit breaker and a DC-side surge protection device. The STS module consists of bidirectional anti-parallel thyristors, a heat dissipation assembly, and a main control unit. The Converter main power unit is composed of multiple single-stage AC / DC bidirectional topologies connected in parallel. The QF1 AC side circuit breaker, STS module, and QF3 uninterruptible power supply circuit breaker are connected in series. The input terminal of the QF2 bypass circuit breaker is connected to the input terminal of the QF1 AC side circuit breaker, and the output terminal is connected to the output terminal of the QF3 uninterruptible power supply circuit breaker. The input terminal of the QF1 AC side circuit breaker is connected to the transformer substation, and the output terminal of the QF3 uninterruptible power supply circuit breaker is connected to the AC load. The TRAN isolation transformer, the Converter main power unit, and the QF4 DC circuit breaker are connected in series. The input terminal of the TRAN isolation transformer is connected to the output terminal of the STS module, and the output terminal of the QF4 DC circuit breaker is connected to the DC output. The AC-side surge protection device is connected to the output terminal of the QF1 AC-side circuit breaker, and the DC-side surge protection device is connected to the input terminal of the QF4 DC circuit breaker.
2. The multi-port flexible interconnection and power mutual assistance device according to claim 1, characterized in that, Multiple stations are connected together, with the DC output terminals within each station area connected together.
3. The multi-port flexible interconnection and power mutual assistance device according to claim 1, characterized in that, The converter's main power unit, under regulated conditions, has three modes: grid-connected, off-grid, and grid-connected / off-grid switching. In grid-connected mode, QF1 AC circuit breaker, STS module, QF3 uninterruptible power supply circuit breaker and QF4 DC circuit breaker are closed, and QF2 bypass circuit breaker is open. In off-grid mode, the QF1 AC circuit breaker, QF3 uninterruptible power supply circuit breaker, and QF4 DC circuit breaker are closed, while the STS module and QF2 bypass circuit breaker are open. On-grid and off-grid switching includes two processes: switching from on-grid to off-grid and switching from off-grid to on-grid. Specifically, During the switch from grid connection to off-grid, if the transformer area loses power, the main power unit of the Converter will detect the power failure and control the STS module to disconnect, changing the power supply from the transformer area to the off-grid output of the Converter. During the switch from off-grid to grid-connected operation, the voltage in the transformer area recovers. After the main power unit of the Converter detects the grid recovery, it controls the off-grid output voltage to synchronize with the phase of the grid in the transformer area. Once the two are in sync, the main power unit of the Converter controls the STS module to close, changing the power draw from the off-grid output of the Converter to direct power draw from the transformer area.