Self-energy-taking interconnection device and control method thereof

Abstract

The invention relates to the technical field of power electronic power conversion, in particular to a self-energy-taking interconnection device and a control method thereof. The device comprises a three-phase current conversion chain, an energy taking system and a voltage transformer, the three-phase current conversion chain is connected with an alternating current system through an alternating current switch, the primary side of the voltage transformer is connected with the alternating current system, each phase current conversion chain in the three-phase current conversion chain comprises a plurality of sub-modules, the alternating current ends of the sub-modules are connected in series, and the alternating current ends of the sub-modules are connected in series. The energy taking system comprises a main loop energy taking unit and a control loop energy taking unit, the main loop energy taking unit is connected with the sub-module, and the control loop energy taking unit is connected with a control unit and the voltage transformer. According to the self-energy-taking interconnection device and the control method thereof, the problems that the occupied space is large, the cost is high, address taking is difficult, and self-energy-taking starting is difficult are solved, and the purposes that reliability is high, the cost is low, the occupied area is small, and self-energy-taking starting can be achieved under the condition that no external secondary power source exists are achieved.

Description

Technical Field

[0001] The present invention relates to the technical field of power electronic power conversion, and in particular to a self-energy interconnection device and a control method thereof. Background Art

[0002] As users' requirements for power quality, power demand and power supply reliability continue to increase, the use of power systems for closed-loop operation is becoming more and more common. The closed-loop operation of power systems is based on a dual-power supply mode, which connects lines, transformers or circuit breakers to form a closed network operation mode. The benefit of closed-loop operation of power grids is that power grids can transmit power to each other, support each other, adjust each other, and serve as backup for each other; this can not only improve the reliability of the power grid or power supply, but also ensure the power consumption of important loads. However, the conditions for closed-loop operation are relatively harsh, and the voltage amplitude and phase of the two power supplies must be basically consistent so that the closed-loop operation will not cause overload of the components in the ring network. However, in actual systems, due to the influence of system impedance distribution or transformer connection groups, there are actual amplitude and phase differences between the two power supplies, and direct interconnection of the two power supplies will cause overcurrent. There are already solutions in the prior art for using power electronic interconnection devices to achieve flexible interconnection, but in actual projects, there is still the problem of selecting the installation location of the device. In addition to considering the actual footprint of the device, the installation location also needs to consider the electrical distance between the installation point and the two substations and the amplitude difference and phase difference of the equivalent power supplies on both sides of the installation point. Taking all the above factors into consideration, it is a better choice to install it between the two substations and away from the two substations.

[0003] For example, the Chinese patent with publication number CN106357009B discloses a self-power supply device for a power equipment status detection sensor, and provides the following technical solution: the present invention discloses a self-power supply device for a power equipment status detection sensor, including a voltage energy acquisition unit, a current energy acquisition unit, an energy storage unit and an energy storage control unit; the voltage energy acquisition unit and the current energy acquisition unit obtain high voltage and low current energy from the power equipment respectively or simultaneously, realize low voltage and high current conversion through the energy storage unit, and store electric energy; when the power equipment status detection sensor needs electric energy to operate, the energy storage control unit controls the energy storage unit to provide electric energy for the power equipment status detection sensor; when the power storage unit is insufficient, the energy storage control unit closes the discharge circuit in time, and the energy storage control unit continues to store energy. The present invention has low cost and long service life, and can provide reliable energy supply for the sensor. However, the above-mentioned self-power supply device for power equipment status detection sensors usually has no installation space in the built substations. On the other hand, if an installation point is selected on the communication line between substations, it is better to choose a middle position, so that the electrical distance between the interconnected device and the two substations is equal, the impedance distribution is more balanced, and the amplitude difference and voltage difference here are also relatively small. If the installation location is far away from the substation, there is a problem of obtaining power for the device. Usually, remote places do not have the conditions for external power supply. Therefore, the interconnected device is required to have the ability to self-collect energy and be able to start by itself without relying on an external secondary power supply. The prior art does not yet have a solution to the above technical problems. Summary of the invention

[0004] In response to the problems of large space occupation, high cost, difficulty in addressing and difficulty in self-power start-up described in the background technology, the present invention proposes a self-power interconnection device and a control method thereof, which achieves the purposes of high reliability, low cost, small footprint and self-power start-up without an external secondary power supply.

[0005] To achieve the above object, the present invention adopts the following technical solution: a self-powered interconnection device, comprising: A three-phase commutation chain, an energy extraction system and a voltage transformer, wherein the three-phase commutation chain is connected to the AC system via an AC switch, the primary side of the voltage transformer is connected to the AC system, each phase of the commutation chain in the three-phase commutation chain includes a plurality of submodules, and the AC ends of each submodule are connected in series with each other, and the energy extraction system includes a main circuit energy extraction unit and a control circuit energy extraction unit, wherein the main circuit energy extraction unit is connected to the submodule, and the control circuit energy extraction unit connects the control unit and the voltage transformer.

[0006] The characteristic of this self-energy interconnection device is that it is realized through a combination of a three-phase commutation chain, an energy extraction system and a voltage transformer. The benefit is that it can effectively extract energy from the AC system and convert it into DC energy that can be used for power supply.

[0007] A control method for a self-powered interconnection device comprises the following steps: S1: Power on the first AC system and the second AC system; S2: The control circuit energy taking unit starts running and supplies power to the control unit; S3: Detect whether the voltage transformer fails, and the control unit automatically controls the first AC switch and the second AC switch to close or open, and selects the normally operating voltage transformer to take energy; S4: The main circuit energy taking unit starts to run and charges the DC capacitor in the commutation chain module; S5: The power semiconductor devices in the three-phase commutation chain module are unlocked.

[0008] By gradually detecting and controlling each component, the normal operation of the system can be ensured and faults can be handled in a timely manner, thus improving the reliability and stability of the system.

[0009] Preferably, the main circuit energy extraction unit includes a multi-winding transformer and several rectifier units, the multi-winding transformer includes a primary winding and several secondary windings, the sub-module is an H-bridge circuit composed of several groups of power semiconductor devices and DC capacitors, the primary side of the multi-winding transformer is connected to the AC system, the secondary winding is connected to the rectifier unit, the rectifier unit converts the AC into DC and then connects to the DC capacitor of the sub-module, the number of the rectifier units is several times the number of the sub-modules, and the number of the secondary windings is greater than the number of the rectifier units.

[0010] The main circuit energy taking unit adopts a combination of a multi-winding transformer and a rectifier unit, which can effectively convert AC power into DC power. This design is conducive to improving the conversion efficiency and stability of energy.

[0011] Preferably, the AC system includes a first AC system and a second AC system, one end of the three-phase commutation chain is connected to the first AC system through a first AC switch, and the other end is connected to the second AC system through a second AC switch, the voltage transformer includes a first voltage transformer and a second voltage transformer, the primary side of the first voltage transformer is connected to the first AC system, and the primary side of the second voltage transformer is connected to the second AC system, the first voltage transformer and the second voltage transformer are respectively placed in the same switch cabinet as the first AC switch and the second AC switch, and the control loop energy acquisition unit provides energy for the first AC switch and the second AC switch.

[0012] By dividing the AC system into the first and second AC systems and equipping them with corresponding voltage transformers and AC switches, system redundancy and backup can be achieved, thereby improving the reliability and stability of the system.

[0013] Preferably, the control loop energy acquisition unit includes an automatic switching switch and an uninterruptible power supply, the automatic switching switch is composed of several groups of switches that cannot be closed at the same time, the uninterruptible power supply includes an energy storage unit, and the three-phase commutation chain is connected in series with a three-phase reactor.

[0014] The control circuit energy taking unit combines an automatic transfer switch and an uninterruptible power supply, which can achieve rapid switching and power supply when the voltage transformer fails, ensuring continuous operation and fault recovery of the system.

[0015] Preferably, the first voltage transformer includes a first secondary winding and a second secondary winding, the second voltage transformer includes a third secondary winding and a fourth secondary winding, the second secondary winding and the fourth secondary winding are connected to the input end of the sampling unit, and the output end of the sampling unit is connected to the control unit.

[0016] The use of sampling units and control units to monitor and control the output of the voltage transformer helps to promptly detect and handle faults and improves the maintainability and controllability of the system.

[0017] Preferably, the rectifier unit is a three-phase half-bridge rectifier circuit composed of several groups of power semiconductor devices.

[0018] The rectifier unit adopts a three-phase half-bridge rectifier circuit, which can achieve efficient rectification of AC power, thereby improving energy utilization and stability.

[0019] Preferably, the rectifier unit is a full-bridge rectifier circuit composed of several groups of power semiconductor devices.

[0020] The rectifier unit adopts a full-bridge rectifier circuit, which can better rectify and regulate the AC power and is suitable for energy conversion needs under various working conditions.

[0021] Preferably, the input side of the control loop energy acquisition unit is connected to the first secondary winding of the first voltage transformer.

[0022] The input side of the control loop energy taking unit is connected to the first secondary winding of the first voltage transformer, which helps to achieve accurate control and monitoring of the system and improves the stability and reliability of the system.

[0023] Preferably, the input side of the control loop energy acquisition unit is connected to the first secondary winding of the first voltage transformer and the third secondary winding of the second voltage transformer.

[0024] The input side of the control loop energy taking unit is connected to the first secondary winding of the first voltage transformer and the third secondary winding of the second voltage transformer, which can realize fine control of different parts of the system and improve the flexibility and adjustability of the system.

[0025] Preferably, the input side of the control loop energy acquisition unit is connected to the third secondary winding of the second voltage transformer.

[0026] The input side of the control loop energy taking unit is connected to the third secondary winding of the second voltage transformer, which can realize fast switching and power supply to the standby voltage transformer and ensure continuous and stable operation of the system.

[0027] Preferably, step S3 comprises: S3.1: Detect whether the voltage transformer fails. If so, proceed to step S3.2. If not, the control unit automatically selects one AC switch to close and another AC switch to open; S3.2: Detect whether the first voltage transformer fails. If so, the control unit automatically controls the first AC switch to be disconnected and enters step S3.4. If not, the control unit automatically controls the first AC switch to be closed and enters step S3.3. S3.3: Detect whether the second voltage transformer fails. If so, the control unit automatically controls the second AC switch to disconnect. If not, return to step S3.1; S3.4: Detect whether the second voltage transformer fails. If so, the energy storage element provides short-time power supply, and the control unit records the fault information and disconnects the AC switch. If not, the control unit automatically controls the second AC switch to close.

[0028] It can quickly judge and take corresponding measures according to the actual situation, effectively reducing the impact of faults on the system and improving the system's automation level and response speed.

[0029] Compared with the prior art, the present invention has the following beneficial effects: 1. The technical solution proposed in the present invention divides the energy acquisition system into a main circuit energy acquisition unit and a control circuit energy acquisition unit. The main circuit energy acquisition unit provides energy for the submodule, and the control circuit energy acquisition unit supplies power to the control unit. The two energy acquisition modes cooperate with each other and are isolated from each other. In the proposed control method, the control circuit energy acquisition unit is started first, and then the AC switch is closed to complete the energy acquisition of the submodule. The step-by-step energy acquisition and power-on method improves the reliability of startup.

[0030] 2. The control circuit energy taking unit of the device of the present invention takes energy from two voltage transformers, and the two energy taking paths are redundant. When the grid voltage is normal, a secondary winding of one voltage transformer is selected for access. When an abnormality occurs in the energy taking of the voltage transformer, a good power supply is selected for access through an automatic switching switch. An uninterruptible power supply is also configured. Even if both energy taking paths fail, short-term power supply can be provided through the energy storage element, providing sufficient time for the control unit to record the fault information and separate the AC switch.

[0031] 3. The voltage transformer of the device of the present invention provides two sets of secondary windings, which are used for energy extraction and voltage sampling respectively, thus realizing the reuse of the primary winding; the voltage transformer can be integrated with the AC switch cabinet without occupying additional space, which has significant advantages in cost and space. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] Figure 1 A schematic diagram of a self-powered interconnection device according to an embodiment of the present invention; Figure 2 A schematic diagram of a main circuit energy taking unit according to an embodiment of the present invention; Figure 3 A specific schematic diagram of a rectifier circuit and submodules according to an embodiment of the present invention; Figure 4 The present invention is a method flow chart of an embodiment of the present invention.

[0033] Illustration: three-phase commutation chain 1, first AC switch 2, second AC switch 3, first voltage transformer 4, second voltage transformer 5, control unit 6, main circuit energy acquisition unit 7, control circuit energy acquisition unit 8, submodule 10, multi-winding transformer 11, rectifier unit 12, sampling unit 13, automatic switching switch 14, uninterruptible power supply 15, three-phase reactor 16, primary side T0 of the second voltage transformer, first secondary winding T1, second secondary winding T2. DETAILED DESCRIPTION

[0034] In order to make the purpose, technical scheme and advantages of the present disclosure clearer, the following will further describe the embodiments of the present disclosure in detail with reference to the accompanying drawings. The proportions of the components are not drawn according to the actual proportions, and the proportions and sizes shown in the accompanying drawings should not limit the substantial technical scheme of the present invention. These embodiments do not describe all the details in detail, nor do they limit the invention to the specific embodiments described.

[0035] See also Figure 1-4As shown, the device of the present invention can effectively utilize the energy in the power system through the self-energy extraction mechanism, thereby improving the overall energy utilization efficiency. By controlling the operation of the loop energy extraction unit 8 and the main loop energy extraction unit 7, the device can extract and convert energy at the optimal time and conditions, reducing energy waste; the equipment adopts multiple fault detection and automatic switching mechanisms, such as detecting the working state of the voltage transformer, and automatically selecting the transformer in normal operation for energy extraction. This design can greatly improve the stability and reliability of the system and reduce downtime and losses caused by faults; through the intelligent scheduling of the control unit 6, the device can flexibly respond to different working scenarios and needs, dynamically adjust the energy extraction strategy according to the actual situation, and ensure that the system can operate efficiently under various conditions and adapt to different load changes; the design of the self-energy extraction interconnection device makes the system more intelligent and automated, reducing the need for manual intervention. At the same time, through preventive fault detection and automatic switching, problems can be discovered and solved in time, reducing maintenance costs and maintenance cycles; by improving energy utilization efficiency and reducing energy waste, the device helps to reduce the impact on the environment and conforms to the concept of sustainable development. At the same time, through intelligent scheduling and optimized energy management, it can minimize the consumption of traditional energy resources and promote the application and development of green energy.

[0036] like Figure 1 In one embodiment shown, Figure 1This is a schematic diagram of a self-powered interconnection device according to an embodiment of the present invention. This device includes three modules: a three-phase commutation chain 1, an energy extraction system, and a voltage transformer. First, the AC system consists of a first and a second AC system, each of which has an AC switch. The three-phase commutation chain 1 connects the two AC systems through these AC switches, wherein each phase commutation chain consists of a number of submodules 10, and their AC ends are connected in series. Next is the energy extraction system, which is divided into a main circuit energy extraction unit 7 and a control circuit energy extraction unit 8, which are respectively connected to the submodule 10 and the voltage transformer. The voltage transformer includes a first and a second voltage transformer 5, which are respectively connected to the first and second AC systems, and are also connected to their respective AC switches, and are all installed in the same switch cabinet. The control circuit energy extraction unit 8 includes an automatic switching switch 14 and an uninterruptible power supply 15, and the automatic switching switch 14 is composed of a number of groups of switches that cannot be closed at the same time, and the uninterruptible power supply 15 includes an energy storage unit. Finally, the first voltage transformer 4 has two windings, namely the first and second secondary windings; and the second voltage transformer 5 also has two windings, namely the third and fourth secondary windings. The second and fourth secondary windings are connected to the input end of the sampling unit 13, and the output end of the sampling unit 13 is connected to the control unit 6. In different embodiments, the input end of the control loop energy taking unit 8 is respectively connected to the first secondary winding of the first voltage transformer 4, the third secondary winding of the second voltage transformer 5, or is simultaneously connected to the first secondary winding of the first voltage transformer 4 and the third secondary winding of the second voltage transformer 5. In one embodiment, the input side of the control loop energy taking unit 8 is connected to the first secondary winding of the first voltage transformer 4; in another embodiment, the input side of the control loop energy taking unit 8 is connected to the third secondary winding of the second voltage transformer 5; in another embodiment, the input side of the control loop energy taking unit 8 is connected to the first secondary winding of the first voltage transformer 4 and the third secondary winding of the second voltage transformer 5.

[0037] The present embodiment relates to a self-powered interconnection device, which includes a three-phase commutation chain 1, a first AC switch 2, a second AC switch 3, a first voltage transformer 4, a second voltage transformer 5, a control unit 6, a main circuit energy acquisition unit 7, and a control circuit energy acquisition unit 8; one end of the three-phase commutation chain 1 is connected to the first AC system through the first AC switch 2, and the other end is connected to the second AC system through the second AC switch 3; each phase commutation chain in the three-phase commutation chain 1 includes N submodules 10, and the AC ends of the N submodules 10 are connected in series, and N is greater than or equal to 1 integer; the submodule 10 is an H-bridge circuit composed of four groups of power semiconductor devices and DC capacitors; the DC capacitor of the submodule 10 is connected to the main circuit energy taking unit 7, and the main circuit energy taking unit 7 provides energy for the submodule 10; the primary sides of the first voltage transformer 4 and the second voltage transformer 5 are respectively connected to the first AC system and the second AC system; the input side of the control circuit energy taking unit 8 is connected to the first secondary winding T1 of the first voltage transformer 4 and / or the second voltage transformer 5, and the output side is connected to the control unit 6 to provide energy for the normal operation of the control unit 6. By connecting the three-phase commutation chain 1 with two independent AC systems, the system has higher reliability. Even if one AC system fails, the other system can still provide power, thereby ensuring the operation of the system; since each AC system has an independent AC switch, the system can switch to different AC systems as needed. This flexibility allows seamless switching to another system when a system is maintained or fails; the design of the main circuit energy acquisition unit 7 and the control circuit energy acquisition unit 8 in the energy acquisition system allows effective recovery of electrical energy, which helps to improve the energy efficiency of the system and reduce energy waste; the automatic switching switch 14 in the control circuit energy acquisition unit 8 ensures that it can quickly switch to another system when a system fails, thereby maintaining the stable operation of the system, which is particularly important for key application areas such as power systems and industrial production; integrating components such as voltage transformers, AC switches and energy acquisition systems in the same switch cabinet helps to better utilize space and simplify the layout and maintenance of the system; by adopting a design of multiple voltage transformer windings, the control circuit energy acquisition unit 8 can be selectively connected to different voltage transformers, providing more control flexibility and diverse operating modes.

[0038] like Figure 2 and Figure 3 In one embodiment shown, Figure 2 This is a schematic diagram of a main circuit energy taking unit 7 according to an embodiment of the present invention. Figure 3The figure is a specific schematic diagram of a rectifier circuit and a submodule 10 in an embodiment of the present invention. The described system includes a three-phase commutation chain 1, an energy extraction system and a voltage transformer. The three-phase commutation chain 1 is connected to the AC system through an AC switch, and the primary side of the voltage transformer is connected to the AC system. The commutation chain in each three-phase commutation chain 1 is composed of a plurality of submodules 10, and the AC ends of these submodules 10 are connected in series. The energy extraction system is composed of a main circuit energy extraction unit 7 and a control circuit energy extraction unit 8. The main circuit energy extraction unit 7 is connected to the submodule 10, and the control circuit energy extraction unit 8 connects the control unit 6 and the voltage transformer. The main circuit energy extraction unit 7 includes a multi-winding transformer 11 and a plurality of rectifier units 12, and the multi-winding transformer 11 includes a primary winding and a plurality of secondary windings. The submodule 10 is an H-bridge circuit composed of a power semiconductor device and a DC capacitor. The primary side of the multi-winding transformer 11 is connected to the AC system, and the secondary winding is connected to the rectifier unit 12, which converts the AC into DC and connects to the DC capacitor of the submodule 10. The number of rectifier units 12 is several times the number of submodules 10, and the number of secondary windings is greater than the number of rectifier units 12. The AC system includes a first and a second AC system. One end of the three-phase commutation chain 1 is connected to the first AC system through a first AC switch 2, and the other end is connected to the second AC system through a second AC switch 3. The voltage transformer includes a first and a second voltage transformer 4, 5, whose primary sides are respectively connected to the first and second AC systems. The first and second voltage transformers 4, 5 are respectively placed in the same switch cabinet with the first and second AC switches 2, 3. The control loop energy extraction unit 8 provides energy for the first and second AC switches 2, 3, and includes an automatic switching switch 14 and an uninterruptible power supply 15. The automatic switching switch 14 is composed of switches that cannot be closed at the same time, and the uninterruptible power supply 15 includes an energy storage unit. The three-phase commutation chain 1 is connected in series with a three-phase reactor 16. The first voltage transformer 4 includes a first and a second secondary winding, and the second voltage transformer 5 includes a third and a fourth secondary winding. The second secondary winding and the fourth secondary winding are connected to the input end of the sampling unit 13, and the output end of the sampling unit 13 is connected to the control unit 6. In one embodiment, the input side of the control loop energy taking unit 8 is connected to the first secondary winding of the first voltage transformer 4; in another embodiment, the input side of the control loop energy taking unit 8 is connected to the third secondary winding of the second voltage transformer 5; in another embodiment, the input side of the control loop energy taking unit 8 is connected to the first secondary winding of the first voltage transformer 4 and the third secondary winding of the second voltage transformer 5. In one embodiment, the rectifier unit 12 is a three-phase half-bridge rectifier circuit composed of several groups of power semiconductor devices; in another embodiment, the rectifier unit 12 is a full-bridge rectifier circuit composed of several groups of power semiconductor devices.

[0039] The main circuit energy acquisition unit 7 includes a multi-winding transformer 11 and 3N rectifier units 12. The multi-winding transformer 11 includes 1 primary winding and at least 3N secondary windings. The primary side of the multi-winding transformer 11 is connected to the first AC system or the second AC system, and the secondary winding is connected to the rectifier unit 12. The rectifier unit 12 converts the AC into DC and then connects to the DC capacitor of the submodule 10. The rectifier unit 12 is a three-phase half-bridge rectifier circuit composed of 6 groups of power semiconductor devices or a full-bridge rectifier circuit composed of 4 groups of power semiconductor devices. The first voltage transformer 4 and the second voltage transformer 5 also include a second secondary winding, which is connected to the input end of the sampling unit 13, and the output end of the sampling unit 13 is connected to the control unit 6. The control circuit energy acquisition unit 8 includes an automatic switching switch 14 and an uninterruptible power supply 15. The automatic switching switch 14 is composed of two groups of switches. It can automatically select one to close according to the upper power supply, and it is not allowed to close at the same time; the uninterruptible power supply 15 UPS contains an energy storage unit, which can provide uninterruptible power supply to the control unit 6 for a certain period of time when the upper power supply loses power at the same time. In this embodiment, a battery is configured in the UPS, and the support time is not less than 30 minutes. The control circuit energy acquisition unit 8 also provides energy for the opening and closing operations of the first AC switch 2 and the second AC switch 3. The first voltage transformer 4 and the second voltage transformer 5 are placed in the same switch cabinet as the first AC switch 2 and the second AC switch 3, respectively, and the three-phase commutation chain 1 is also connected in series with a three-phase reactor 16. The system adopts a complex control loop energy acquisition unit 8, which improves the flexibility and reliability of the system and enables it to adapt to different working conditions and fault conditions; through the multi-winding transformer 11 and the rectifier unit 12, the system can efficiently convert AC energy into DC to supply the sub-module 10, thereby improving the energy extraction efficiency; through the voltage transformer and the sampling unit 13, the system can monitor the voltage of the AC system in real time, and adjust and control it through the control loop energy acquisition unit 8 to ensure the stable operation of the system; the control loop energy acquisition unit 8 with an automatic switching switch 14 and an uninterruptible power supply 15 is adopted, and the system can automatically switch to the backup power supply in the event of a fault, thereby improving the reliability and stability of the system.

[0040] like Figure 4 In one embodiment shown, Figure 4 A method for controlling a self-powered interconnection device includes the following steps: S1: Power on the first AC system and the second AC system; S2: The control circuit energy taking unit 8 starts to operate and supplies power to the control unit 6; S3: Detect whether the voltage transformer fails, and the control unit 6 automatically controls the first AC switch 2 and the second AC switch 3 to close or open, and selects the normally operating voltage transformer to take energy; S4: The main circuit energy taking unit 7 starts to operate and charges the DC capacitor in the commutation chain module 10; S5: unlocking the power semiconductor devices in the submodule 10 of the three-phase commutation chain 1. The step S2 comprises: S3.1: Detect whether the voltage transformer fails. If so, proceed to step S3.2. If not, the control unit 6 automatically selects one AC switch to close and another AC switch to open; S3.2: Detect whether the first voltage transformer 4 fails. If so, the control unit 6 automatically controls the first AC switch 2 to be disconnected and enters step S3.4. If not, the control unit 6 automatically controls the first AC switch 2 to be closed and enters step S3.3. S3.3: Detect whether the second voltage transformer 5 fails. If so, the control unit 6 automatically controls the second AC switch 3 to disconnect. If not, return to step S3.1; S3.4: Detect whether the second voltage transformer 5 fails. If so, the energy storage element provides short-term power supply, and the control unit 6 records the fault information and disconnects the AC switch. If not, the control unit 6 automatically controls the second AC switch 3 to close.

[0041] When a fault is detected in the first or second voltage transformer 5 , the automatic switching switch 14 in the control loop energy taking unit 8 automatically switches to select the normally operating voltage transformer for energy taking.

[0042] By detecting whether the voltage transformer fails and taking corresponding automatic control measures, the system can switch to a normally operating voltage transformer in time, thereby improving the reliability of the system, which helps to prevent system shutdown or failure caused by transformer failure; when the voltage transformer failure is detected, the method realizes automatic processing of the system failure through the automatic switching mechanism of the automatic switching switch 14, which reduces the dependence on manual intervention and improves the automation level of the system; through the startup operation of the main circuit energy extraction unit 7, the DC capacitor in the commutation chain submodule 10 is charged, and the power semiconductor device in the three-phase commutation chain 1 submodule 10 is unlocked, the system can use energy more effectively and improve energy efficiency, which is very important for energy management and sustainability; when the first or second voltage transformer 5 is detected to have a fault, the system provides short-term power supply through the energy storage element to ensure that the system can maintain basic operation when a fault occurs, and records the fault information at the same time, which is helpful for subsequent maintenance and fault diagnosis; the automatic control unit 6 and switch operation involved in the whole process enable the system to automatically take corresponding measures when a fault is detected without manual intervention, which improves the automation level of the system and reduces the operation and maintenance cost.

[0043] In summary, the present invention discloses a self-energy interconnection device, which includes a three-phase commutation chain 1, a first AC switch 2, a second AC switch 3, a first voltage transformer 4, a second voltage transformer 5, a control unit 6, a main circuit energy acquisition unit 7 and a control circuit energy acquisition unit 8; one end of the three-phase commutation chain 1 is connected to the first AC system through the first AC switch 2, and the other end is connected to the second AC system through the second AC switch 3; the primary sides of the first voltage transformer 4 and the second voltage transformer 5 are respectively connected to the first AC system and the second AC system; the input side of the control circuit energy acquisition unit 8 is connected to the first secondary winding of the first voltage transformer 4 and / or the second voltage transformer 5, and the output side is connected to the control unit 6 to provide energy for the normal operation of the control unit 6. The technical solution provided by the present invention has low cost and is applied to the hand-in-hand power supply mode of dual power supply. Self-energy starting can be achieved without an external secondary power supply. In view of the problems of large space occupation, high cost, difficulty in addressing and difficulty in self-energy starting described in the background technology, the present invention proposes a self-energy interconnection device and a control method thereof, which achieves the purposes of high reliability, low cost, small footprint and self-energy starting without an external secondary power supply.

[0044] The present invention is not limited to the above-mentioned embodiments. No matter any changes are made in the shape or material composition, any structural design provided by the present invention is a variation of the present invention and should be considered to be within the protection scope of the present invention.

Claims

1. A self-powered interconnection device, characterized in that: include: A three-phase commutation chain (1), an energy extraction system and a voltage transformer, wherein the three-phase commutation chain (1) is connected to an AC system via an AC switch, the primary side of the voltage transformer is connected to the AC system, each phase commutation chain in the three-phase commutation chain (1) comprises a plurality of submodules (10), each of the submodules (10) is connected in series, and the energy extraction system comprises a main circuit energy extraction unit (7) and a control circuit energy extraction unit (8), the main circuit energy extraction unit (7) is connected to the submodule (10), and the control circuit energy extraction unit (8) is connected to a control unit (6) and the voltage transformer.

2. A self-powered interconnection device according to claim 1, characterized in that: The main circuit energy acquisition unit (7) comprises a multi-winding transformer (11) and a plurality of rectifier units (12); the multi-winding transformer (11) comprises a primary winding and a plurality of secondary windings; the submodule (10) is an H-bridge circuit composed of a plurality of groups of power semiconductor devices and DC capacitors; the primary side of the multi-winding transformer (11) is connected to the AC system; the secondary winding is connected to the rectifier unit (12); the rectifier unit (12) converts the AC into DC and then connects to the DC capacitor of the submodule (10); the number of the rectifier units (12) is several times the number of the submodules (10); and the number of the secondary windings is greater than the number of the rectifier units (12).

3. A self-powered interconnection device according to claim 1 or 2, characterized in that: The AC system comprises a first AC system and a second AC system; one end of the three-phase commutation chain (1) is connected to the first AC system via a first AC switch (2), and the other end is connected to the second AC system via a second AC switch (3); the voltage transformer comprises a first voltage transformer (4) and a second voltage transformer (5); the primary side of the first voltage transformer (4) is connected to the first AC system, and the primary side of the second voltage transformer (5) is connected to the second AC system; the first voltage transformer (4) and the second voltage transformer (5) are respectively placed in the same switch cabinet as the first AC switch (2) and the second AC switch (3); and the control circuit energy acquisition unit (8) provides energy for the first AC switch (2) and the second AC switch (3).

4. A self-powered interconnection device according to claim 3, characterized in that: The control loop energy acquisition unit (8) comprises an automatic switching switch (14) and an uninterruptible power supply (15), wherein the automatic switching switch (14) is composed of a plurality of groups of switches that cannot be closed simultaneously, and the uninterruptible power supply (15) comprises an energy storage unit, and the three-phase commutation chain (1) is connected in series with a three-phase reactor (16).

5. A self-powered interconnection device according to claim 4, characterized in that: The first voltage transformer (4) comprises a first secondary winding and a second secondary winding, the second voltage transformer (5) comprises a third secondary winding and a fourth secondary winding, the second secondary winding and the fourth secondary winding are connected to an input end of the sampling unit (13), and an output end of the sampling unit (13) is connected to the control unit (6).

6. A self-powered interconnection device according to claim 4 or 5, characterized in that: The rectifier unit (12) is a three-phase half-bridge rectifier circuit composed of a plurality of groups of power semiconductor devices.

7. A self-powered interconnection device according to claim 4 or 5, characterized in that: The rectifier unit (12) is a full-bridge rectifier circuit composed of a plurality of groups of power semiconductor devices.

8. A self-powered interconnection device according to claim 4 or 5, characterized in that: The input side of the control loop energy acquisition unit (8) is connected to the first secondary winding of the first voltage transformer (4).

9. A self-powered interconnection device according to claim 4 or 5, characterized in that: The input side of the control loop energy acquisition unit (8) is connected to the first secondary winding of the first voltage transformer (4) and the third secondary winding of the second voltage transformer (5).

10. A self-powered interconnection device according to claim 4 or 5, characterized in that: The input side of the control loop energy acquisition unit (8) is connected to the third secondary winding of the second voltage transformer (5).

11. A control method for a self-powered interconnection device, using a self-powered interconnection device according to any one of claims 1 to 10, characterized in that: The following steps are involved: S1: Power on the first AC system and the second AC system; S2: the control circuit energy taking unit (8) starts to operate and supplies power to the control unit (6); S3: Detecting whether a voltage transformer has a fault, the control unit (6) automatically controls the first AC switch (2) and the second AC switch (3) to close or open, and selects the voltage transformer in normal operation to take energy; S4: the main circuit energy extraction unit (7) starts to operate and charges the DC capacitor in the commutation chain module (10); S5: The power semiconductor devices in the submodule (10) of the three-phase commutation chain (1) are unlocked.

12. A control method for a self-powered interconnection device according to claim 11, characterized in that: The step S2 comprises: S3.1: Detect whether the voltage transformer is faulty. If so, proceed to step S3.

2. If not, the control unit (6) automatically selects one AC switch to close and another AC switch to open; S3.2: Detect whether the first voltage transformer (4) has a fault. If so, the control unit (6) automatically controls the first AC switch (2) to open and enters step S3.

4. If not, the control unit (6) automatically controls the first AC switch (2) to close and enters step S3.

3. S3.3: Detect whether the second voltage transformer (5) is faulty. If so, the control unit (6) automatically controls the second AC switch (3) to disconnect. If not, return to step S3.

1. S3.4: Detect whether the second voltage transformer (5) has a fault. If so, the energy storage element provides short-term power supply, and the control unit (6) records the fault information and disconnects the AC switch. If not, the control unit (6) automatically controls the second AC switch (3) to close.

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