Power distribution system and control method thereof
By sharing active filtering devices among multiple transformer groups and using circuit breaker groups to achieve dynamic switching, the problem of low equipment utilization in multi-transformer distribution systems is solved, and efficient equipment utilization and safe and stable operation of the power system are achieved.
Patent Information
- Application Number
- CN202510848257.0
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-06-24
- Publication Date
- 2025-09-05
AI Technical Summary
In the prior art, the independent configuration of active filtering devices in multi-transformer distribution systems results in low equipment utilization, hardware resource redundancy, and an inability to effectively control harmonic pollution, affecting the safe and stable operation of the power system.
Multiple transformers are divided into multiple groups, each group shares an active filter device, and dynamic switching of the active filter device is achieved through the circuit breaker group. The control unit is used to control the opening and closing operations of the circuit breaker group to achieve automatic switching of the active filter device and synchronous switching of the current sampling point and harmonic injection point.
The number of active filtering devices used is reduced, equipment utilization is improved, equipment redundancy and resource waste are reduced, and equipment operation and maintenance efficiency and power system reliability are improved.
Smart Images
Figure CN120601431A_ABST
Abstract
Description
Technical Field
[0001] The embodiments of the present application relate to the field of power electronics technology, and in particular to a power distribution system and a control method thereof. Background Art
[0002] In the field of industrial power systems, with the large-scale application of variable frequency speed regulation devices and intelligent power electronic equipment, the problem of power grid harmonic pollution has become increasingly prominent. During operation, such equipment will generate a large number of harmonic currents with characteristic frequencies such as 3rd and 5th orders, which will not only cause the heating of electrical equipment to increase, the aging of insulation to accelerate, and the loss of electric energy to increase, but may also cause the relay protection device to malfunction, seriously threatening the safe and stable operation of the power supply and distribution system.
[0003] In related technologies, harmonic control in multi-transformer distribution systems typically employs a "one transformer, one active filter" configuration. This involves connecting each transformer to its low-voltage side to filter out the harmonics generated by its load in real time. However, in actual operation, the multiple transformers in a distribution room are operated in alternating groups. Using this configuration, some active filters remain idle for extended periods, resulting in low equipment utilization and significant hardware resource redundancy. Summary of the Invention
[0004] Based on this, the embodiments of the present application provide a power distribution system and a control method thereof, which can reduce equipment redundancy and resource waste, improve equipment utilization, and ensure the safe and stable operation of the power system.
[0005] In a first aspect, an embodiment of the present application provides a power distribution system, comprising:
[0006] at least one transformer group, the transformer group comprising a first transformer and a second transformer, the first transformer and the second transformer operating alternately;
[0007] an active filter device corresponding one-to-one to the transformer group;
[0008] a circuit breaker group corresponding one-to-one to the transformer group, the circuit breaker group comprising a first circuit breaker, a second circuit breaker, a third circuit breaker, and a fourth circuit breaker, the active filter device being connected to the low-voltage side of the first transformer via the first circuit breaker and to the low-voltage side of the second transformer via the second circuit breaker, the third circuit breaker and the active filter device being connected in parallel to the secondary side of the current transformer (CT) of the first transformer, and the fourth circuit breaker and the active filter device being connected in parallel to the secondary side of the CT of the second transformer;
[0009] A control unit is used to control the opening and closing operations of the circuit breaker group according to the switching status of the transformer group.
[0010] In one embodiment, the control unit is further configured to close the fourth circuit breaker and the first circuit breaker, and open the second circuit breaker and the third circuit breaker when detecting that the first transformer is put into operation.
[0011] In one embodiment, the operating sequence of the circuit breakers in the circuit breaker group includes:
[0012] The fourth circuit breaker is closed first, and then the first circuit breaker is closed, and the second circuit breaker and the third circuit breaker are opened at the same time.
[0013] In one embodiment, the control unit is further configured to close the third circuit breaker and the second circuit breaker, and open the first circuit breaker and the fourth circuit breaker when detecting that the second transformer is put into operation.
[0014] In one embodiment, the operating sequence of the circuit breakers in the circuit breaker group includes:
[0015] The third circuit breaker is closed first, and then the second circuit breaker is closed, and the first circuit breaker and the fourth circuit breaker are opened at the same time.
[0016] In one embodiment, the control unit is further configured to control the third circuit breaker or the fourth circuit breaker to close and trigger a corresponding alarm signal if it is detected that the secondary side of the CT of the first transformer or the second transformer is abnormally open during the operation of the transformer group.
[0017] In a second aspect, an embodiment of the present application provides a control method for a power distribution system, which is applied to the power distribution system provided in the first aspect of the embodiment of the present application, and the method includes:
[0018] Determine the currently operating transformer in the transformer group;
[0019] Short-circuit the CT secondary circuit of the original operating transformer through the circuit breaker group;
[0020] Switching the current sampling point of the active filter device to the CT secondary side of the currently operating transformer through the circuit breaker group;
[0021] The harmonic injection point of the active filter device is switched to the low-voltage side of the currently operating transformer through a circuit breaker group.
[0022] In one embodiment, when the currently operating transformer is the first transformer, the control operation on the circuit breaker group is performed through the following process:
[0023] Close the fourth circuit breaker and the first circuit breaker, and open the second circuit breaker and the third circuit breaker.
[0024] In one embodiment, when the currently operating transformer is the second transformer, the control operation on the circuit breaker group is performed through the following process:
[0025] The third circuit breaker and the second circuit breaker are closed, and the first circuit breaker and the fourth circuit breaker are opened.
[0026] In one embodiment, the method further includes: when it is detected that the CT secondary side of the first transformer or the second transformer in the transformer group is abnormally open, controlling the third circuit breaker or the fourth circuit breaker to close and triggering a corresponding alarm signal.
[0027] The technical solution provided by the embodiment of the present application divides multiple transformers into multiple groups, each group sharing an active filter device, and uses a circuit breaker group to realize dynamic switching of the active filter device, thereby reducing the number of active filter devices used, reducing equipment redundancy and resource waste, and improving equipment utilization. In addition, the control unit triggers the opening and closing operations of the circuit breaker group based on the switching status of the transformer group to realize automatic switching of the active filter device, reducing manual intervention operations, and improving operation and maintenance efficiency and power system reliability. BRIEF DESCRIPTION OF THE DRAWINGS
[0028] Figure 1 A schematic diagram of the structure of the power distribution system provided in an embodiment of the present application;
[0029] Figure 2 Another structural diagram of the power distribution system provided in an embodiment of the present application;
[0030] Figure 3 A flow chart of a control method for a power distribution system provided in an embodiment of the present application. DETAILED DESCRIPTION
[0031] In order to make the objectives, technical solutions, and advantages of this application more clearly understood, the technical solutions in the embodiments of this application are further described in detail through the following embodiments and in conjunction with the accompanying drawings. It should be understood that the specific embodiments described herein are only used to illustrate this application and are not intended to limit this application. It should also be noted that, for ease of description, the accompanying drawings only show parts relevant to this application, not all structures.
[0032] The power distribution system and control method thereof provided in the embodiments of the present application are suitable for scenarios involving alternating switching of multiple transformers and requiring harmonic control.
[0033] See also Figure 1 and Figure 2 The power distribution system provided in the embodiment of the present application may include: at least one transformer group 10, an active filter device 11 corresponding to the transformer group 10, a circuit breaker group 12 corresponding to the transformer group 10, and a control unit 13.
[0034] Specifically, each transformer group 10 includes two transformers, namely a first transformer 101 and a second transformer 102. The first transformer 101 and the second transformer 102 operate alternately based on operating time and equipment status. Each active filter device 11 corresponds to a transformer group 10 one-to-one, that is, each transformer group 10 is configured with an independent active filter device 11. In other words, the first transformer 101 and the second transformer 102 share the same active filter device 11, and switching of the active filter device 11 is achieved through the circuit breaker group 12.
[0035] The circuit breaker group 12 includes four circuit breakers: a first circuit breaker 121, a second circuit breaker 122, a third circuit breaker 123, and a fourth circuit breaker 124. These circuit breakers are used to switch the current sampling point and harmonic injection point of the active filter device 11. The active filter device 11 is connected to the low-voltage side of the first transformer 101 via the first circuit breaker 121, and to the low-voltage side of the second transformer 102 via the second circuit breaker 122. When the first circuit breaker 121 is closed, the compensation current output terminal of the active filter device 11 is connected to the low-voltage side busbar of the first transformer 101, forming a harmonic injection path for the first transformer 101. When the second circuit breaker 122 is closed, the compensation current output terminal of the active filter device 11 is connected to the low-voltage side busbar of the second transformer 102, forming a harmonic injection path for the second transformer 102. In addition, the third circuit breaker 123 and the active filter device 11 are connected in parallel to the secondary side of the current transformer (CT) of the first transformer 101, and the fourth circuit breaker 124 and the active filter device 11 are connected in parallel to the secondary side of the CT of the second transformer 102. When the third circuit breaker 123 is closed, the secondary side circuit of the CT of the first transformer 101 is short-circuited, eliminating the risk of an open circuit. When the third circuit breaker 123 is open, the active filter device 11 and the secondary side circuit of the CT of the first transformer 101 are connected, allowing the active filter device 11 to measure the real-time current signal on the low-voltage side of the first transformer 101 and determine the harmonic compensation current value for the first transformer 101 based on the measured real-time current signal. When the fourth circuit breaker 124 is closed, the CT secondary side circuit of the second transformer 102 is short-circuited to eliminate the risk of an open circuit. When the fourth circuit breaker 124 is open, the active filter device 11 and the CT secondary side circuit of the second transformer 102 are connected, so that the active filter device 11 can measure the real-time current signal on the low-voltage side of the second transformer 102 and determine the harmonic compensation current value for the second transformer 102 based on the measured real-time current signal.
[0036] The control unit 13 collects current, voltage, and switching signals from each transformer in the transformer group 10 and determines the currently operating transformer in the transformer group 10 based on the collected current, voltage, and switching signals. Upon detecting a change in the switching state of the transformer group 10, the control unit 13 controls the opening and closing of the circuit breaker group 12 using preset logic to switch the current sampling point and harmonic injection point of the active filter device 11. For example, when it is monitored that the second transformer 102 stops operating and the first transformer 101 is put into operation, the control unit 13 controls the opening and closing operations of each circuit breaker in the circuit breaker group 12 through a preset logic, and connects the active filter device 11 to the current sampling point and harmonic injection point of the first transformer 101. When it is monitored that the first transformer 101 stops operating and the second transformer 102 is put into operation, the control unit 13 controls the opening and closing operations of each circuit breaker in the circuit breaker group 12 through a preset logic, and connects the active filter device 11 to the current sampling point and harmonic injection point of the second transformer 102, thereby achieving seamless connection of harmonic compensation, reducing the number of active filter devices 11 configured, improving equipment utilization, and saving costs.
[0037] Optionally, the control unit 13 is further configured to, upon detecting that the first transformer 101 is in operation, close the fourth circuit breaker 124 and the first circuit breaker 121, and open the second circuit breaker 122 and the third circuit breaker 123. Specifically, the control unit 13 may first close the fourth circuit breaker 124, then close the first circuit breaker 121, and simultaneously open the second circuit breaker 122 and the third circuit breaker 123. Of course, the control unit 13 may also simultaneously close the fourth circuit breaker 124 and the first circuit breaker 121, and simultaneously open the second circuit breaker 122 and the third circuit breaker 123. By closing the fourth circuit breaker 124 to short-circuit the CT secondary side circuit of the second transformer 102, the risk of high voltage damage caused by an open circuit on the CT secondary side is eliminated. At the same time, by closing the first circuit breaker 121 and opening the second circuit breaker 122, the harmonic injection point of the active filter device 11 is switched from the second transformer 102 to the low-voltage side bus of the first transformer 101, so that the harmonic compensation current of the active filter device 11 is injected into the low-voltage side bus of the first transformer 101. By opening the third circuit breaker 123, the current sampling point of the active filter device 11 is switched from the second transformer 102 to the CT secondary side of the first transformer 101, so that the active filter device 11 collects the real-time current signal of the CT secondary side of the first transformer 101 and determines the harmonic compensation current value for the first transformer 101 based on the real-time current signal.
[0038] Optionally, the control unit 13 is further configured to, upon detecting that the second transformer 102 is in operation, close the third circuit breaker 123 and the second circuit breaker 122, and open the first circuit breaker 121 and the fourth circuit breaker 124. Specifically, the control unit 13 may first close the third circuit breaker 123, then close the second circuit breaker 122, and simultaneously open the first circuit breaker 121 and the fourth circuit breaker 124. Of course, the control unit 13 may also simultaneously close the third circuit breaker 123 and the second circuit breaker 122, and simultaneously open the first circuit breaker 121 and the fourth circuit breaker 124. By closing the third circuit breaker 123 to short-circuit the CT secondary circuit of the first transformer 101, the risk of high voltage damage caused by an open circuit on the CT secondary side is eliminated. At the same time, by closing the second circuit breaker 122 and opening the first circuit breaker 121, the harmonic injection point of the active filter device 11 is switched from the first transformer 101 to the low-voltage side bus of the second transformer 102, so that the harmonic compensation current of the active filter device 11 is injected into the low-voltage side bus of the second transformer 102. By opening the fourth circuit breaker 124, the current sampling point of the active filter device 11 is switched from the first transformer 101 to the CT secondary side of the second transformer 102, so that the active filter device 11 collects the real-time current signal of the CT secondary side of the second transformer 102 and determines the harmonic compensation current value for the second transformer 102 based on the real-time current signal.
[0039] In this embodiment, the control unit monitors the operating status of the transformer in real time and triggers the opening and closing operations of the corresponding circuit breaker according to preset logic to ensure that there is no open circuit on the secondary side of the transformer's CT during the switching process. In addition, by controlling the opening and closing operations of the corresponding circuit breaker, the harmonic injection point and current sampling point of the active filter device are switched along with the transformer, ensuring that the filtering function covers the low-voltage side harmonics of the currently operating transformer.
[0040] For the active filter device, its harmonic injection point and current sampling point are switched synchronously through the opening and closing operations of the corresponding circuit breakers. When the current sampling point is switched to the CT secondary side of the currently operating transformer (such as the second transformer 102), its harmonic injection point is also synchronously switched to the low-voltage busbar of the currently operating transformer through the corresponding circuit breaker (such as closing the second circuit breaker 122). This enables the active filter device to obtain the current signal of the currently operating transformer in real time and accurately inject the compensation current into the low-voltage busbar of the currently operating transformer, thereby ensuring that the filtering function fully covers the low-voltage side harmonics of the currently operating transformer and achieving effective harmonic control.
[0041] Optionally, the control unit 13 is further configured to, during the operation of the transformer group 10, control the third circuit breaker 123 or the fourth circuit breaker 124 to close if it is detected that the CT secondary side of the first transformer 101 or the second transformer 102 is abnormally open, thereby eliminating the risk of the CT secondary side being open, and triggering a corresponding alarm signal. The alarm signal may include, but is not limited to, audible and visual alarms, sending an alarm email or SMS to a designated terminal, and making a voice call to a designated terminal. Specifically, during the operation of the second transformer 102, if it is detected that the CT secondary side of the first transformer 101 changes from a short circuit to an open circuit, the CT secondary side of the first transformer 101 is determined to be abnormally open, the third circuit breaker 123 is controlled to close, and an alarm signal is triggered. During the operation of the first transformer 101, if it is detected that the CT secondary side of the second transformer 102 changes from a short circuit to an open circuit, the CT secondary side of the second transformer 102 is determined to be abnormally open, the fourth circuit breaker 124 is controlled to close, and an alarm signal is triggered.
[0042] During the operation of the transformer group, if the CT secondary side of the first transformer 101 or the second transformer 102 is detected to be abnormally open, the third circuit breaker 123 or the fourth circuit breaker 124 is controlled to be closed to eliminate the risk of the CT secondary side open circuit; and the corresponding alarm signal is triggered to promptly remind relevant personnel to ensure the reliability of the distribution system operation.
[0043] In one example, a power distribution system includes four transformers, with two transformers grouped together. The two transformers are put into operation alternately based on operating time and equipment status. Each group is equipped with an active filter device and a circuit breaker group. After the transformer is replaced, the active filter device can be switched via the circuit breaker group, reducing the number of active filter devices from four to two. Furthermore, during the operation of the transformer, the active filter device is not idle for a long time, thereby improving equipment utilization and saving costs.
[0044] Figure 3 A flow chart of a control method for a power distribution system provided in an embodiment of the present application. The method is applied to the power distribution system provided in any of the above embodiments, such as Figure 3 As shown, the method may include:
[0045] S301. Determine the currently operating transformer in the transformer group.
[0046] The power distribution system includes at least one transformer group, each of which includes two transformers: a first transformer and a second transformer. The first transformer and the second transformer operate alternately based on operating time and equipment status. That is, only one transformer in a transformer group is in operation. The current, voltage, and switching signals of each transformer in transformer group 10 are collected, and the currently operating transformer in transformer group 10 is determined based on the collected current, voltage, and switching signals. The currently operating transformer refers to the transformer currently in operation.
[0047] S302. Short-circuit the CT secondary circuit of the original operating transformer through the circuit breaker group.
[0048] By controlling the opening and closing operations of the corresponding circuit breakers in the circuit breaker group, the CT secondary circuit of the original operating transformer is short-circuited, eliminating the open circuit risk and improving the safety of the distribution system operation.
[0049] S303: Switch the current sampling point of the active filter device to the secondary side of the CT of the currently operating transformer through the circuit breaker group.
[0050] S304: Switch the harmonic injection point of the active filter device to the low-voltage side of the currently operating transformer through the circuit breaker group.
[0051] When the transformer is switched, the current sampling point and harmonic injection point of the active filter device are synchronously switched from the original operating transformer to the current operating transformer by controlling the opening and closing operations of the corresponding circuit breakers in the circuit breaker group. This allows the active filter device to determine the harmonic compensation current value based on the sampled current signal and inject the compensation current into the current operating transformer, thereby achieving harmonic control of the current operating transformer.
[0052] Optionally, when the currently operating transformer is the first transformer, the control operation on the circuit breaker group is performed through the following process: closing the fourth circuit breaker and the first circuit breaker, and opening the second circuit breaker and the third circuit breaker.
[0053] Optionally, when the currently operating transformer is the second transformer, the control operation on the circuit breaker group is performed through the following process: closing the third circuit breaker and the second circuit breaker, and opening the first circuit breaker and the fourth circuit breaker.
[0054] Optionally, it also includes: when it is detected that the CT secondary side of the first transformer or the second transformer in the transformer group is abnormally open (for example, the corresponding circuit breaker fails to operate and the CT secondary side circuit is broken, etc., which will cause the CT secondary side of the transformer to be abnormally open), controlling the third circuit breaker or the fourth circuit breaker to close, and triggering a corresponding alarm signal to promptly remind maintenance personnel to ensure safe and reliable operation of the system and realize unmanned harmonic control in industrial power distribution scenarios.
[0055] As the transformers in the power distribution system alternate, the above steps S301-S304 are repeatedly executed to achieve automatic follow-up switching of the active filter device during the switching process of the transformers. That is, no matter how the transformers are switched, the active filter device can be synchronously switched to the low-voltage side of the currently operating transformer, achieving dynamic tracking and precise compensation of harmonics. The entire process reduces manual operation, reduces the operational risks caused by manual intervention, and improves operation and maintenance efficiency and system reliability.
[0056] It should be noted that the control principle of each circuit breaker in the circuit breaker group can refer to the description in the above embodiment, and this embodiment will not be repeated here.
[0057] The technical features of the above-mentioned embodiments can be combined arbitrarily. In order to make the description concise, not all possible combinations of the technical features in the above-mentioned embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.
[0058] The above-described embodiments merely represent several implementation methods of the present application. While the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the present invention. It should be noted that a person of ordinary skill in the art may make various modifications and improvements without departing from the spirit of the present invention, all of which fall within the scope of protection of the present invention. Therefore, the scope of protection of the present invention shall be determined by the appended claims.
Claims
1. A power distribution system, characterized in that: include: at least one transformer group, the transformer group comprising a first transformer and a second transformer, the first transformer and the second transformer operating alternately; an active filter device corresponding one-to-one to the transformer group; a circuit breaker group corresponding one-to-one to the transformer group, the circuit breaker group comprising a first circuit breaker, a second circuit breaker, a third circuit breaker, and a fourth circuit breaker, the active filter device being connected to the low-voltage side of the first transformer via the first circuit breaker and to the low-voltage side of the second transformer via the second circuit breaker, the third circuit breaker and the active filter device being connected in parallel to the secondary side of the current transformer (CT) of the first transformer, and the fourth circuit breaker and the active filter device being connected in parallel to the secondary side of the CT of the second transformer; A control unit is used to control the opening and closing operations of the circuit breaker group according to the switching status of the transformer group.
2. The power distribution system according to claim 1, characterized in that The control unit is further configured to close the fourth circuit breaker and the first circuit breaker, and open the second circuit breaker and the third circuit breaker when monitoring that the first transformer is put into operation.
3. The power distribution system according to claim 2, characterized in that: The operating sequence of the circuit breakers in the circuit breaker group includes: The fourth circuit breaker is closed first, and then the first circuit breaker is closed, and the second circuit breaker and the third circuit breaker are opened at the same time.
4. The power distribution system according to claim 1, wherein: The control unit is further configured to close the third circuit breaker and the second circuit breaker, and open the first circuit breaker and the fourth circuit breaker when monitoring that the second transformer is put into operation.
5. The power distribution system according to claim 4, characterized in that: The operating sequence of the circuit breakers in the circuit breaker group includes: The third circuit breaker is closed first, and then the second circuit breaker is closed, and the first circuit breaker and the fourth circuit breaker are opened at the same time.
6. The power distribution system according to claim 1, wherein: The control unit is further configured to control the third circuit breaker or the fourth circuit breaker to close and trigger a corresponding alarm signal if it is detected that the secondary side of the CT of the first transformer or the second transformer is abnormally open during the operation of the transformer group.
7. A control method for a power distribution system, characterized in that: Applied to the power distribution system according to any one of claims 1 to 6, the method comprises: Determine the currently operating transformer in the transformer group; Short-circuit the CT secondary circuit of the original operating transformer through the circuit breaker group; Switching the current sampling point of the active filter device to the CT secondary side of the currently operating transformer through the circuit breaker group; The harmonic injection point of the active filter device is switched to the low-voltage side of the currently operating transformer through a circuit breaker group.
8. The method according to claim 7, characterized in that When the currently operating transformer is the first transformer, the control operation on the circuit breaker group is performed through the following process: Close the fourth circuit breaker and the first circuit breaker, and open the second circuit breaker and the third circuit breaker.
9. The method according to claim 7, characterized in that When the currently operating transformer is the second transformer, the control operation on the circuit breaker group is performed through the following process: The third circuit breaker and the second circuit breaker are closed, and the first circuit breaker and the fourth circuit breaker are opened.
10. The method according to claim 7, characterized in that Also includes: When it is monitored that the CT secondary side of the first transformer or the second transformer in the transformer group is abnormally open, the third circuit breaker or the fourth circuit breaker is controlled to be closed, and a corresponding alarm signal is triggered.