Rectifier transformer low-voltage side additional winding elimination circuit

Abstract

This utility model relates to the field of circuit technology, specifically to a harmonic suppression circuit for an auxiliary winding on the low-voltage side of a rectifier transformer. It includes a current and voltage detection component installed on the incoming power grid line on the high-voltage side of the rectifier transformer, and a reactive power compensation and harmonic mitigation device installed on the low-voltage side of the rectifier transformer. The reactive power compensation and harmonic mitigation device comprises a control module, a reactive power compensation component, and a harmonic suppression device, all connected to the auxiliary winding on the low-voltage side of the rectifier transformer. The current and voltage detection component sends the current and voltage detection signals from the incoming power grid line to the control module, which controls the operation of the reactive power compensation component and the harmonic suppression device based on the current and voltage detection signals. This circuit design is simple, combining the advantages of LC passive filtering and APF (Automatic Power Filter), thus saving design costs.

Description

Technical Field

[0001] This utility model relates to the field of circuit technology, specifically to a harmonic suppression circuit for an additional winding on the low-voltage side of a rectifier transformer. Background Technology

[0002] Rectifier transformers are widely used in industrial metallurgy, providing a stable power supply for smelting equipment. With the development of modern industry, the requirements for power quality and energy efficiency are constantly increasing. Conventional passive LC filter circuits can eliminate harmonics generated by the rectifier power supply and perform reactive power compensation. However, to effectively match the characteristic harmonics generated by the rectifier power supply, it is necessary to accurately design the LC resonant frequency and perform impedance matching according to the transformer parameters to achieve the desired harmonic mitigation effect.

[0003] Precise resonant frequency places high demands on the accuracy of reactors and capacitors, resulting in high manufacturing costs. Secondly, rectified power supplies typically contain multiple characteristic harmonics (for example, the harmonic orders of a 24-pulse rectified power supply, from low to high, are typically 4, 5, 6, 7, 9, 11, 13, 17, 19, 23, 25, etc.). This necessitates setting up separate LC circuits for each harmonic, thus forming multiple LC filter branches. In actual operation, the switching of each LC branch must follow the principle of "starting from low to high order and switching from high to low order" to prevent the amplification effect that higher-order LC filter branches might have on lower-order harmonics. The problem this leads to is that often, reactive power compensation exceeds the limit before the higher-order harmonic LC filter branches have even been activated.

[0004] Therefore, passive LC filter circuits often fail to simultaneously meet the requirements of reactive power compensation and harmonic mitigation in actual operation, especially in terms of poor mitigation of high-order harmonics. Dynamic active power filters (APFs) can effectively solve high- and low-order harmonic problems and also provide reactive power compensation, but they are usually very expensive and lack economic viability in high-power, high-harmonic-content applications. Utility Model Content

[0005] The purpose of this invention is to overcome the shortcomings of the above-mentioned background technology and provide a harmonic elimination circuit for the low-voltage side additional winding of a rectifier transformer. This circuit is simple to design and combines the advantages of LC passive filtering and APF to save design costs.

[0006] The technical solution adopted in this utility model is as follows: A harmonic suppression circuit for an auxiliary winding on the low-voltage side of a rectifier transformer includes a current and voltage detection component installed on the incoming power grid line on the high-voltage side of the rectifier transformer, and a reactive power compensation and harmonic mitigation device installed on the low-voltage side of the rectifier transformer. The reactive power compensation and harmonic mitigation device has a control module, a reactive power compensation component, and a harmonic suppression device, all of which are connected to the auxiliary winding on the low-voltage side of the rectifier transformer. The current and voltage detection component sends the current and voltage detection signals of the incoming power grid line to the control module, and the control module controls the operation of the reactive power compensation component and the harmonic suppression device according to the current and voltage detection signals.

[0007] In a further embodiment, the reactive power compensation component is a multi-channel LC loop used for reactive power compensation.

[0008] In a further embodiment, in the LC circuit, one end of the switch is connected to the output terminal of the incoming switch cabinet, the other end of the switch is connected to one end of the capacitor cabinet, the other end of the capacitor cabinet is connected to the reactor, and the switch is controlled by the control module to open and close.

[0009] In a further embodiment, the harmonic suppression device is an active power filter used for dynamic harmonic mitigation.

[0010] In a further embodiment, the wiring method of the high-voltage side of the rectifier transformer is the same as that of the low-voltage side additional winding, which is either a star connection or a delta connection.

[0011] In a further embodiment, the remaining windings on the low-voltage side of the rectifier transformer are connected to a rectifier.

[0012] In a further embodiment, the current and voltage detection component includes a current transformer and a voltage transformer.

[0013] In a further embodiment, an incoming line switchgear controlled by a control module is provided between the additional winding, the reactive power compensation component, and the harmonic suppression device.

[0014] The beneficial effects of this utility model are as follows: The reactive power compensation component (LC circuit) of this utility model is only used for reactive power compensation and does not need to participate in the work of harmonic elimination, which reduces the design difficulty of LC parameter matching and gives full play to its advantages of large capacity, high reliability and low cost in reactive power compensation; The harmonic elimination device (active power filter) is only used to eliminate harmonics and does not need to participate in the work of reactive power compensation, thereby reducing the design capacity of the APF, giving full play to its harmonic control capability (especially high-order harmonics), reducing the overall cost, and the method has a simple circuit, is easy to implement and is economical and practical. Attached Figure Description

[0015] Figure 1 This is one of the circuit structure diagrams of this utility model.

[0016] Figure 2This is the second schematic diagram of the circuit structure of this utility model.

[0017] Figure reference numerals: 1. Current and voltage detection component; 2. Rectifier transformer; 3. Rectifier; 4. Additional winding; 5. Reactive power compensation and harmonic mitigation device; 6. Incoming line switch cabinet; 7. Reactive power compensation component; 7-1 LC circuit; 8. Harmonic suppression device; 9. Switch; 10. Capacitor cabinet; 11. Reactor. Detailed Implementation

[0018] The present invention will be further described below with reference to the accompanying drawings, but the present invention is not limited to the following embodiments.

[0019] like Figure 1 As shown, this embodiment provides a harmonic suppression circuit for an additional winding on the low-voltage side of a rectifier transformer, including a current and voltage detection component 1 installed on the high-voltage side of the rectifier transformer 2 and a reactive power compensation and harmonic mitigation device 5 installed on the low-voltage side of the rectifier transformer 2. The current and voltage detection component 1 includes a current transformer and a voltage transformer, used to detect the three-phase current and voltage of the grid input line. Its wiring method is existing technology and will not be described in detail here.

[0020] The reactive power compensation and harmonic mitigation device 5 includes a control module (omitted in the figure), a reactive power compensation component 7, and a harmonic suppression device 8. Both the reactive power compensation component 7 and the harmonic suppression device 8 are connected to the additional winding 4 on the low-voltage side of the rectifier transformer 2 through the switch cabinet 6. The current and voltage detection component 1 sends the current and voltage detection signals of the incoming power grid line to the control module. The control module controls the operation of the switch cabinet 6, the reactive power compensation component 7, and the harmonic suppression device 8 according to the current and voltage detection signals.

[0021] In one embodiment, the harmonic suppression device 8 is an active power filter for dynamic harmonic control. In another embodiment, the reactive power compensation component 7 is a multi-channel LC circuit 7-1 for reactive power compensation. In the LC circuit 7-1, one end of the switch 9 is connected to the output terminal of the incoming switch cabinet 6, the other end of the switch 9 is connected to one end of the capacitor cabinet 10, the other end of the capacitor cabinet 10 is connected to the reactor 11, and the other end of the reactor 11 is grounded. The switch 9 is controlled by the control module to open and close. In this embodiment, the remaining windings on the low-voltage side of the rectifier transformer 2 are connected to the rectifier 3. The wiring method of the high-voltage side of the rectifier transformer 2 is the same as the wiring method of the low-voltage side additional winding 4, which is either a star connection (i.e., a Y-type connection) or a delta connection. The remaining windings on the low-voltage side are either a star connection, a delta connection, or an extended delta connection.

[0022] The working principle of this utility model is as follows: Figure 2As shown, the three-phase grid voltage is connected to the high-voltage side of the rectifier transformer. The high-voltage side of the rectifier transformer is a three-phase Y-connection. The first winding of the low-voltage side is delta-connected to the rectifier, and the second winding of the low-voltage side is Y-connected to the rectifier, forming a 12-pulse rectification mode. The additional winding (third winding) is connected to the control module of the three-phase reactive power compensation and harmonic mitigation device. The control module selects which LC circuit to connect to for reactive power compensation by reading the current data of the current transformer and the voltage data of the voltage transformer on the high-voltage side of the rectifier transformer. The active power filter dynamically eliminates harmonics from the rectifier transformer.

[0023] The above description is merely a preferred embodiment of this utility model. For those skilled in the art, various modifications and variations are possible. Any modifications, equivalent substitutions, or improvements made within the spirit and principles of this utility model should be included within the protection scope of this utility model.

Claims

1. A rectifier transformer low voltage side additional winding elimination circuit, characterized by: It includes a current and voltage detection component (1) installed on the high-voltage side of the rectifier transformer (2) and a reactive power compensation and harmonic mitigation device (5) installed on the low-voltage side of the rectifier transformer (2); the reactive power compensation and harmonic mitigation device (5) has a control module, a reactive power compensation component (7) and a harmonic elimination device (8), all of which are connected to the additional winding (4) on the low-voltage side of the rectifier transformer (2). The current and voltage detection component (1) sends the current and voltage detection signals of the grid input line to the control module. The control module controls the operation of the reactive power compensation component (7) and the harmonic elimination device (8) according to the current and voltage detection signals.

2. The rectifier transformer low voltage side additional winding chokes circuit according to claim 1, characterized in that: The reactive power compensation component (7) consists of multiple LC loops (7-1) for reactive power compensation.

3. The rectifier transformer low voltage side additional winding chokes circuit according to claim 2, characterized in that: In the LC circuit (7-1), one end of the switch (9) is connected to the output end of the incoming switch cabinet (6), and the other end of the switch (9) is connected to one end of the capacitor cabinet (10). The other end of the capacitor cabinet (10) is connected to the reactor (11). The switch (9) is controlled by the control module to open and close.

4. The rectifier transformer low voltage side additional winding chokes circuit according to claim 1, characterized in that: The harmonic suppression device (8) is an active power filter used for dynamic harmonic control.

5. The harmonic suppression circuit for the low-voltage side additional winding of a rectifier transformer according to claim 1, characterized in that: The high-voltage side wiring method of the rectifier transformer (2) is the same as the low-voltage side additional winding (4) wiring method, which is either star connection or delta connection.

6. The harmonic suppression circuit for the low-voltage side additional winding of a rectifier transformer according to claim 1, characterized in that: The remaining windings on the low-voltage side of the rectifier transformer (2) are connected to the rectifier (3).

7. A harmonic suppression circuit for an additional winding on the low-voltage side of a rectifier transformer according to claim 1, characterized in that: The current and voltage detection component (1) includes a current transformer and a voltage transformer.

8. A rectifier transformer low voltage side additional winding chokes circuit according to any of claims 1-7, characterized in that: An incoming line switch cabinet (6) controlled by a control module is provided between the additional winding (4), the reactive power compensation component, and the harmonic elimination device (8).

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