A CT mounting circuit with an APF containing a capacitor and a method for determining the CT position.

Abstract

This invention relates to a current transformer (CT) installation circuit with an active power filter (APF) and a method for determining the CT position. The circuit includes a load terminal, a power supply terminal, an active power filter (APF), a capacitor, and a current transformer. A first circuit connects the load terminal and the power supply terminal, and a second circuit extends from the first circuit, connecting to the active power filter. A capacitor circuit is connected in parallel to the first circuit, with the parallel connection positions of the capacitor circuit including the power supply side and the load side. The current transformer is installed on the first circuit relative to the parallel connection positions of the capacitor circuit. This invention considers the CT installation position in conjunction with the capacitor circuit installation. Since the capacitor circuit generates reactive power, connecting it in parallel in the circuit can compensate for the reactive power consumed by the inductive load, thereby increasing voltage and improving the power factor. Combining the CT installation position with the capacitor circuit effectively ensures the overall reactive power compensation effect of the circuit under different conditions.

Description

Technical Field

[0001] This invention belongs to the field of power system technology and relates to a CT installation circuit with an APF containing a capacitor and a method for determining the CT position. Background Technology

[0002] With the development of power electronics technology and the large-scale use of various nonlinear and time-varying electronic devices, the requirements for power supply systems are becoming increasingly stringent. Traditional parallel capacitor circuit compensation methods are no longer sufficient to meet the requirements of power distribution systems with impact loads (such as welding machines, rolling mills, and internal mixers). As a core device and technology of flexible AC transmission systems, the Active Power Filter (APF) is a new type of power electronic device used for dynamically suppressing harmonics and compensating for reactive power. It can quickly track and compensate for harmonics of different magnitudes and frequencies. The term "active" refers to its ability to compensate for harmonics of fixed frequencies and magnitudes, as opposed to passive filters that can only passively absorb harmonics. The APF can sample the load current and separate harmonics and reactive power, controlling and actively outputting the magnitude, frequency, and phase of the current, and responding quickly to offset the corresponding current in the load, achieving dynamic tracking compensation. Furthermore, it can compensate for both harmonics and reactive power imbalances, making it the preferred solution in the field of reactive power control.

[0003] Current transformers (CTs) are used to convert large currents in AC circuits into smaller currents for measurement and relay protection. They also ensure the accuracy of measurement, the reliability of relay protection devices, and the safety of high-voltage circuits, and are widely used in power systems, especially when installing SVG (Static Var Generator) equipment. The circuitry of the CT is particularly important during SVG installation, as wiring errors and incorrect placement of the current transformer are common problems.

[0004] In existing current transformer (CT) installation circuits, when determining whether the CT installation position is incorrect, if even-order harmonics appear in the load-side harmonic components of the circuit, the CT is considered to be installed incorrectly. This method is too rigid, resulting in poor output current detection of harmonic circuits. Therefore, the inventors have improved the circuit by addressing how to arrange large capacitors and determine the CT position to better improve the overall compensation and filtering effect of the circuit. Summary of the Invention

[0005] This invention provides an APF CT installation circuit and CT position determination method that diversifies CT installation methods, amplifies harmonics on the load side, enables more accurate determination of CT installation position, and improves harmonic compensation effect.

[0006] A current transformer (CT) mounting circuit with an APF (Active Power Filter) includes a load terminal, a power supply terminal, an active power filter, a capacitor, and a current transformer. A first circuit is connected between the load terminal and the power supply terminal. A second circuit extends from the first circuit and is connected to the active power filter. A capacitor circuit is connected in parallel to the first circuit. The parallel connection positions of the capacitor circuit include the second terminal being connected to the power supply side of the power supply terminal and the second terminal being connected to the load side of the load terminal. The current transformer is mounted on the first circuit relative to the parallel connection positions of the capacitor circuit.

[0007] Furthermore, when the capacitor circuit is connected in parallel to the load side, the power transformer is installed as follows: there is one power transformer, the power transformer is electrically connected to the active filter, and the power transformer is located between the capacitor circuit and the load side.

[0008] Furthermore, when the capacitor circuit is connected in parallel on the load side, the power transformer is installed as follows: there are two power transformers, including a first power transformer and a second power transformer. One of the first power transformers is connected in series with the capacitor circuit, and the second power sensor is located between the capacitor circuit and the active filter. The first power sensor and the second power sensor are electrically connected, and the second power sensor is directly electrically connected to the active filter.

[0009] Furthermore, when the capacitor circuit is connected in parallel on the load side, the power transformer is installed as follows: there are three power transformers, including a first power transformer, a second power transformer, and a third power transformer. The first power transformer is connected in series with the capacitor circuit, the second power transformer is connected in series with the second circuit of the active filter, and the third power transformer is located between the active filter and the power supply terminal. The three power transformers are connected in series with each other, and the second power transformer is directly electrically connected to the active filter.

[0010] Furthermore, when the capacitor circuit is connected in parallel on the power supply side, the power transformer is installed as follows: there is one power transformer, the power transformer is electrically connected to the active filter, and the power transformer is located between the capacitor circuit and the load terminal.

[0011] Furthermore, when the capacitor circuit is connected in parallel on the power supply side, the power transformer is installed as follows: there are two power transformers, including a first power transformer and a second power transformer. One of the first power transformers is connected in series with the active filter, and the second power sensor is located between the capacitor circuit and the active filter. The first power sensor and the second power sensor are electrically connected, and the first power sensor is directly electrically connected to the active filter.

[0012] Furthermore, when the capacitor circuit is connected in parallel to the power supply side, the power transformer is installed as follows: there are three power transformers, including a first power transformer, a second power transformer, and a third power transformer. The first power transformer is connected in series with the capacitor circuit, the second power transformer is connected in series with the second circuit of the active filter, and the third power transformer is located between the active filter and the power supply terminal. The three power transformers are connected in series with each other, and the second power transformer is directly electrically connected to the active filter.

[0013] Furthermore, it also includes a dual busbar installation method, wherein the installation method is configured as follows: it includes two identical busbar structures, each of which includes a power supply end, a load end, an active filter, a first power transformer, and a second power transformer; the first active filter and the second active filter are respectively located at the two ends of the load end, and the first circuits of the two busbar structures are connected by a switch.

[0014] Preferably, a capacitor-free circuit installation method is also included, wherein the installation method is configured such that: when there is one power transformer, the power transformer is installed on the first circuit; when there are two power transformers, the power transformers are installed on the first circuit and the second circuit respectively, and the first power transformer is electrically connected to the active filter.

[0015] Preferably, the installation direction of any of the power transformers is towards the load end.

[0016] A method for determining the CT position using the CT mounting circuit of the APF as described in the above claim includes the following steps:

[0017] S1: Collect the active output harmonics of the active filter and the output current harmonics of the external power supply.

[0018] S2: Identify the harmonic components of the active output harmonics and the harmonic components of the external output current harmonics, and analyze and generate harmonic component information;

[0019] S3: Compare the harmonic components of the active output harmonics with the harmonic components of the external output current harmonics;

[0020] S4: Analyze the difference harmonic between the two harmonics, and then compare the component proportion of the difference harmonic relative to the harmonic component of the active output harmonic to generate a harmonic component comparison result.

[0021] S5: Determine whether the position of the current transformer in the first circuit is accurate;

[0022] S6: Determine whether the position of the current transformer in the capacitor circuit is accurate;

[0023] S7: Feedback position information. The control circuit runs when the position is accurate and stops when the position is incorrect.

[0024] In some optional implementations, the specific steps of S5 above further include:

[0025] S5.1: Compare the comparison results with the preset interval;

[0026] S5.2: If the comparison result exceeds the preset range and it is determined that the installation position of the current transformer is located on the power supply side between the second terminal and the power supply terminal, then it is determined that the position of the current transformer on the first circuit is incorrect.

[0027] S5.2: When the power transformer is installed on the load side between the second terminal and the load terminal, and an even harmonic occurs on the load side between the second terminal and the load terminal, it is determined that the position of the current transformer on the first circuit is incorrect.

[0028] In some optional implementations, the specific steps of S6 above further include:

[0029] S6.1: Compare the comparison results with the preset interval;

[0030] S6.2: If the comparison result exceeds the preset range and the first terminal of the capacitor circuit is located between the second terminal and the power supply terminal, it is determined that the position of the current transformer on the capacitor is incorrectly installed.

[0031] S6.3.1: When the first terminal of the capacitor circuit is located between the second terminal and the load terminal, the harmonic component information on the load side is detected. If even harmonics are detected between the first terminal and the second terminal, it is not determined that the position of the current transformer on the capacitor circuit is incorrectly installed.

[0032] S6.3.2: If the harmonic components detected between the first terminal and the load terminal include even harmonics, and the power transformer is installed on the load side, then the current transformer on the capacitor circuit is determined to be installed incorrectly.

[0033] The advantages of the technical solution of the present invention over the prior art are as follows:

[0034] The CT mounting circuit and CT position determination method with capacitor-equipped APF provided by this invention consider the installation position of the CT in combination with the installation of the capacitor circuit, and has multiple CT installation methods. By adding a capacitor circuit to the existing circuit, the characteristics of passing low frequencies and blocking high frequencies are utilized, and harmonics on the load side can be amplified. This greatly improves the fault tolerance when determining the CT installation position, and plays a role in improving voltage and power factor. Combining the CT installation position with the capacitor circuit can effectively ensure the overall reactive power compensation effect of the circuit under different conditions. Attached Figure Description

[0035] Figure 1 This is a wiring diagram of the capacitor circuit of the SVG of the present invention mounted on the load side and with a single CT.

[0036] Figure 2 This is a wiring diagram of the SVG capacitor circuit of the present invention mounted on the load side with dual CTs;

[0037] Figure 3 This is a diagram showing the wiring effect of the capacitor circuit of the SVG of the present invention mounted on the load side and the three CTs.

[0038] Figure 4 This is a wiring diagram of the capacitor circuit of the SVG of the present invention mounted on the load side and with a single CT.

[0039] Figure 5 This is a wiring diagram of the SVG capacitor circuit of the present invention mounted on the power supply side with dual CTs.

[0040] Figure 6 This is a diagram showing the wiring effect of the capacitor circuit of the SVG of the present invention mounted on the power supply side and the three CTs.

[0041] Figure 7 This is a wiring diagram of the dual busbar dual CT of the present invention;

[0042] Figure 8 This is a schematic diagram of the CT installation system of the present invention.

[0043] Figure 9 This is a schematic diagram illustrating the principle of the CT position determination method of the present invention.

[0044] Explanation of reference numerals in the attached diagram: 1. Load end, 2. Power supply end, 3. Active filter, 4. Capacitor circuit, 5. Current transformer, 6. First circuit, 7. Second circuit, 51. First power transformer, 52. Second power transformer, 53. Third power transformer, 21. Power supply side, 11. Load side, 41. First terminal, 42. Capacitor, 71. Second terminal. Detailed Implementation

[0045] The following detailed description, in conjunction with the accompanying drawings and the following embodiments, further illustrates the CT mounting circuit with a capacitor-equipped APF and the CT position determination method of the present invention; wherein CT represents a current transformer and SVG represents an active filter.

[0046] Example

[0047] The accompanying drawings illustrate a current transformer (CT) mounting circuit with an APF (Active Power Filter) and a capacitor, comprising a load terminal 1, a power supply terminal 2, an active power filter 3, a capacitor circuit 4, and at least one current transformer 5. A first circuit 6 connects the load terminal 1 and the power supply terminal 2. The capacitor circuit 4 is mounted on the first circuit 6, and a second circuit 7 extends from the first circuit 6. The second terminal 71 of the second circuit 7 is connected to the first circuit 6. The second circuit 7 is connected to the active power filter 3. The capacitor circuit 4 is connected in parallel to the first circuit 6, and the first terminal 41 of the capacitor circuit 4 is connected to the first circuit 6. The parallel connection positions of the capacitor circuit 4 include the power supply side 21 and the load side 11. The current transformer 5 is mounted on the first circuit 6 relative to the parallel connection positions of the capacitor circuit 4.

[0048] The power supply side is represented as the area between the second terminal 71 and the power supply terminal 2, and the load side is represented as the area between the second terminal 71 and the load terminal 1.

[0049] The active power filter (SVG) is connected to the power grid in parallel, monitoring the current and voltage of the object being compensated in real time. An internal command current calculation circuit calculates the command signal for the compensation current, which is then processed by a compensation current generation circuit (PWM current conversion) to produce the compensation current. This compensation current cancels out the reactive current in the load current, ultimately achieving the desired power factor. Employing real-time data acquisition and dynamic differential control tracking technologies, it monitors the voltage and current of the power grid and system in real time. While rapidly and continuously compensating for reactive power in the system, it also significantly improves the power quality at the connection point between the load and the public power grid, including improving the power factor, overcoming three-phase imbalance, and suppressing voltage flicker and fluctuations.

[0050] Current transformers can be either open-type or closed-type. Open-type current transformers are easier to install, while closed-type current transformers must be installed with the load de-energized. The accuracy requirements for current transformers are 0.2 class or higher for closed-type and 0.5 class or higher for open-type. Using lower accuracy will reduce the compensation effect of the static var compensator (SVC).

[0051] In a three-phase four-wire system, three current transformers (CTs) must be used, installed on phases A, B, and C respectively.

[0052] In a three-phase three-wire system, at least two current transformers (CTs) are required, one for phase A and one for phase C.

[0053] For power grids without capacitor circuits, it is recommended that external current transformers (CTs) be installed on the load side, i.e., between the SVG and the load. With this installation, only one set of three CTs needs to be installed on phases A, B, and C of the load side to meet the requirements (for a three-phase three-wire system, two CTs are required, and only phases A and C need to be installed).

[0054] In some embodiments, when there is a large capacitor circuit on the load side, the current transformer (CT) for the capacitor circuit can be installed in one of three ways: the power transformer is located on the load side, the detection signal is sent to the SVG, and for a 3-phase 4-wire system, one set (3) of power transformers must be used to detect harmonic source currents. The installation direction of the power transformers must face the load end, and the installation direction of any power transformer must be towards the load end. The phase sequence of the detection signals of the power transformers cannot be interchanged.

[0055] Reference Figure 1-Figure 3 As shown, when multiple current transformers (CTs) are installed, according to Kirchhoff's current law, the sum of the currents collected by two CTs is the load current. Adding more capacitor circuit current transformers can more accurately collect the load current.

[0056] Combination Figure 1 As shown, the capacitor circuit is connected in parallel on the load side. The power transformer is installed as follows: there is one power transformer, which is electrically connected to the active filter. The power transformer is located between the capacitor circuit and the load.

[0057] Combination Figure 2 As shown, the capacitor circuit is connected in parallel on the load side. The power transformer is installed as follows: there are two power transformers, including a first power transformer and a second power transformer. The first power transformer is connected in series with the capacitor circuit, and the second power sensor is located between the capacitor circuit and the active filter. The first power sensor and the second power sensor are electrically connected, and the second power sensor is directly electrically connected to the active filter.

[0058] Combination Figure 3 As shown, the capacitor circuit is connected in parallel on the load side. The power transformers are installed as follows: there are three power transformers, including a first power transformer, a second power transformer, and a third power transformer. The first power transformer is connected in series with the capacitor circuit, the second power transformer is connected in series with the second circuit of the active filter, and the third power transformer is located between the active filter and the power supply terminal. The three power transformers are connected in series with each other, and the second power transformer is directly electrically connected to the active filter.

[0059] In some embodiments, if it is inconvenient to connect a power transformer or capacitor circuit to the load side, an equivalent method is adopted to collect the load current. Similarly, according to Kirchhoff's current law, at any given moment, the current flowing into the node of the circuit is equal to the current flowing out of the node. Therefore, for power transformers and capacitor circuits installed on the power supply side, it is actually an equivalent method to collect the load current.

[0060] The power transformers are installed on the power supply side. At least two sets (six in total for a 3-phase 4-wire system) of power transformers are required at the load end. These are installed on the A / B / C phase lines and the output power cable, respectively, with the two sets connected in parallel. If the current transformer (CT) is to be installed on the power supply side and there is a large capacitor circuit on the power supply side, then... Figure 5 and Figure 6 In this installation method, the installation direction of any power transformer is towards the load end.

[0061] Combination Figure 4 As shown, the capacitor circuit is connected in parallel on the power supply side. The power transformer is installed as follows: there is one power transformer, the power transformer is electrically connected to the active filter, and the power transformer is connected between the capacitor circuit and the load end.

[0062] Combination Figure 5 As shown, the capacitor circuit is connected in parallel on the power supply side. The power transformer is installed as follows: there are two power transformers, including a first power transformer and a second power transformer. The first power transformer is connected in series with the active filter, and the second power sensor is located between the capacitor circuit and the active filter. The first power sensor and the second power sensor are electrically connected, and the first power sensor is directly electrically connected to the active filter.

[0063] Combination Figure 6 As shown, the capacitor circuit is connected in parallel on the power supply side. The power transformers are installed as follows: there are three power transformers, including a first power transformer, a second power transformer, and a third power transformer. The first power transformer is connected in series with the capacitor circuit, the second power transformer is connected in series with the second circuit of the active filter, and the third power transformer is located between the active filter and the power supply terminal. The three power transformers are connected in series with each other, and the second power transformer is directly electrically connected to the active filter.

[0064] In some embodiments, according to Kirchhoff's current law, the sum of the currents collected by the two current transformers is the load current. Adding a capacitor circuit transformer can more accurately collect the load current.

[0065] In some optional embodiments, when the current harmonics output from the power supply are low and the harmonic compensation of the active harmonic filter is low, the active filter is controlled by the control system to actively output large current harmonics, thereby determining the position of the current transformer.

[0066] In some embodiments, a dual-bus, dual-CT power supply installation method is also provided. This installation method is as follows: Figure 7 As shown, it includes two identical bus structures. Both bus structures include a power supply end, a load end, an active filter, a first power transformer, and a second power transformer. The first and second active filters are respectively located at the two ends of the load end. The first circuits of the two bus structures are connected by a switch.

[0067] In some embodiments, combined Figure 8 As shown, it also includes a CT installation system that applies the above-mentioned CT installation circuit, including an acquisition and processing module, an acquisition and processing module and an alarm module; the acquisition and processing module is used to acquire the active output harmonics and external output current harmonics of the active filter;

[0068] The acquisition and processing module includes a harmonic comparison unit and a position detection unit. The harmonic comparison unit is used to identify the harmonic components of the actively output harmonic and the external output current harmonic, then compare the harmonic components of the actively output harmonic and the external output current harmonic to analyze the difference between the two harmonics, and then compare the proportion of the difference harmonic relative to the harmonic components of the actively output harmonic to generate a harmonic component comparison result. The acquisition and processing module is used to analyze and process the comparison result to determine whether the comparison result is within a preset range. If the comparison result exceeds the preset range, the installation position of the corresponding current transformer is considered to be incorrect, and the acquisition and processing module will then issue a position error signal. Upon receiving the error signal, the alarm module will issue an alarm signal, and the system will stop operating.

[0069] Furthermore, when there is only one power transformer, the acquisition and processing module determines that the comparison result is not within the preset range, and the current transformer installed between the load end and the power supply end is determined to be in the wrong position; when there are at least two power transformers, the acquisition and processing module acquires the current harmonic components of each power transformer respectively, compares and analyzes the current harmonic components on each power transformer side, generates harmonic component comparison results one by one, and the power transformer whose comparison result exceeds the preset range is in the wrong position, and then a separate power transformer position error signal is generated below.

[0070] Among them, the following points should be noted when using different installation methods for CT scanners:

[0071] 1. When the CT is installed on the power supply side and there is only one APF module, it is not necessary to collect the current of the APF module itself;

[0072] 2. Determination of whether the CT is installed on the power supply side or the load side: When the CT is installed before the APF injection point, it is defined as the CT being installed on the power supply side; when the CT is installed after the APF injection point, it is positioned on the load side.

[0073] 3. The CT should be selected on the load side first and only the load current should be collected. If the system cannot be installed on the load side to collect only the load current, it can only be placed on the source side. If there are multiple modules in parallel, the total current of the APF device needs to be collected.

[0074] 4. The installation location of the APF CT should avoid collecting the current of the capacitor circuit cabinet as much as possible. If it is collected, it needs to be handled as described above.

[0075] In some alternative embodiments, combined with Figure 9 As shown, a method for determining the CT position using the CT mounting circuit of the APF as described in the above claim includes the following steps:

[0076] S1: Collect the active output harmonics of the active filter and the output current harmonics of the external power supply.

[0077] S2: Identify the harmonic components of the active output harmonics and the harmonic components of the external output current harmonics, and analyze and generate harmonic component information;

[0078] S3: Compare the harmonic components of the active output harmonics with the harmonic components of the external output current harmonics;

[0079] S4: Analyze the difference harmonic between the two harmonics, and then compare the component proportion of the difference harmonic relative to the harmonic component of the active output harmonic to generate a harmonic component comparison result.

[0080] S5: Determine whether the position of the current transformer in the first circuit is accurate;

[0081] S6: Determine whether the position of the current transformer in the capacitor circuit is accurate;

[0082] S7: Feedback position information. The control circuit runs when the position is accurate and stops when the position is incorrect.

[0083] In some optional implementations, the specific steps of S5 above further include:

[0084] S5.1: Compare the comparison results with the preset interval;

[0085] S5.2: If the comparison result exceeds the preset range and it is determined that the installation position of the current transformer is located on the power supply side between the second terminal and the power supply terminal, then it is determined that the position of the current transformer on the first circuit is incorrect.

[0086] S5.2: When the power transformer is installed on the load side between the second terminal and the load terminal, and an even harmonic occurs on the load side between the second terminal and the load terminal, it is determined that the position of the current transformer on the first circuit is incorrect.

[0087] In some optional implementations, the specific steps of S6 above further include:

[0088] S6.1: Compare the comparison results with the preset interval;

[0089] S6.2: If the comparison result exceeds the preset range and the first terminal of the capacitor circuit is located between the second terminal and the power supply terminal, it is determined that the position of the current transformer on the capacitor is incorrectly installed.

[0090] S6.3.1: When the first terminal of the capacitor circuit is located between the second terminal and the load terminal, the harmonic component information on the load side is detected. If even harmonics are detected between the first terminal and the second terminal, it is not determined that the position of the current transformer on the capacitor circuit is incorrectly installed.

[0091] S6.3.2: If the harmonic components detected between the first terminal and the load terminal include even harmonics, and the power transformer is installed on the load side, then the current transformer on the capacitor circuit is determined to be installed incorrectly.

[0092] This invention considers the installation location of the CT in conjunction with the installation of the capacitor circuit. Since the capacitor circuit can generate reactive power, connecting the capacitor circuit in parallel in the line can compensate for the reactive power consumed by the inductive load, thereby improving the voltage and power factor. Combining the installation location of the CT with the capacitor circuit can effectively ensure the optimal reactive power compensation effect of the circuit as a whole under various conditions.

[0093] The above-described embodiments are merely preferred embodiments of the present invention and are not intended to limit the scope of the present invention. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without creative effort are within the scope of protection of the present invention. Various modifications and improvements made by those skilled in the art to the technical solutions of the present invention without departing from the concept of the present invention should fall within the scope of protection defined by the claims of the present invention.

Claims

1. A method for determining the position of a CT using a CT mounting circuit with an APF containing a capacitor, characterized in that: The CT mounting circuit of the APF with capacitor includes a load terminal, a power supply terminal, an active filter, a capacitor, and a current transformer. A first circuit is connected between the load end and the power supply end. A second circuit extends from the first circuit. The second circuit is connected to the active filter. The second terminal of the second circuit is connected to the first circuit. The first circuit has a capacitor circuit connected in parallel. The first terminal of the capacitor circuit is connected to the first circuit. The parallel connection position of the capacitor circuit includes the power supply side between the second terminal and the power supply terminal and the load side between the second terminal and the load terminal. The current transformer is installed on the first circuit relative to the parallel connection position of the capacitor circuit. The method for determining the CT position using the CT mounting circuit with APF includes the following steps: S1: Collect the active output harmonics of the active filter and the output current harmonics of the external power supply. S2: Identify the harmonic components of the actively output harmonics and the harmonic components of the external power supply, and analyze and generate harmonic component information; S3: Compare the harmonic components of the actively output harmonics with the harmonic components of the external power supply. S4: Analyze the difference harmonic between the two harmonics, and then compare the component proportion of the difference harmonic relative to the harmonic component of the active output harmonic to generate a harmonic component comparison result. S5: Determine whether the position of the current transformer in the first circuit is accurate; S6: Determine whether the position of the current transformer in the capacitor circuit is accurate; S7: Feeds back position information. The control circuit runs when the position is accurate and stops when the position is incorrect. The specific steps of step S5 also include: S5.1: Compare the comparison results with the preset interval; S5.2: If the comparison result exceeds the preset range and it is determined that the current transformer is installed on the power supply side between the second terminal and the power supply terminal, then it is determined that the current transformer in the first circuit is installed incorrectly. S5.3: When the current transformer is installed on the load side between the second terminal and the load terminal, and an even harmonic appears on the load side between the second terminal and the load terminal, it is determined that the current transformer on the first circuit is installed incorrectly. The specific steps of step S6 also include: S6.1: Compare the comparison results with the preset interval; S6.2: If the comparison result exceeds the preset range and the first terminal of the capacitor circuit is located between the second terminal and the power supply terminal, it is determined that the position of the current transformer on the capacitor is incorrectly installed. S6.3.1: When the first terminal of the capacitor circuit is located between the second terminal and the load terminal, the harmonic component information on the load side is detected. If even harmonics are detected between the first terminal and the second terminal, it is not determined that the position of the current transformer on the capacitor circuit is incorrectly installed. S6.3.2: If the harmonic components detected between the first terminal and the load terminal include even harmonics, and the current transformer is installed on the load side, then it is determined that the current transformer on the capacitor circuit is installed incorrectly.

2. The CT position determination method using a CT mounting circuit with an APF containing a capacitor, as described in claim 1, is characterized in that... When the capacitor circuit is connected in parallel on the load side, the current transformer is installed as follows: The current transformer is provided in two parts, including a first current transformer and a second current transformer. The first current transformer is installed on the capacitor circuit, and the second current transformer is located between the capacitor circuit and the active filter. The first current transformer is electrically connected to the second current transformer, and the second current transformer is directly electrically connected to the active filter.

3. The CT position determination method using a CT mounting circuit with an APF containing a capacitor, as described in claim 1, is characterized in that... When the capacitor circuit is connected in parallel on the load side, the current transformer is installed as follows: The current transformer is provided in three parts, including a first current transformer, a second current transformer and a third current transformer. The first current transformer is installed on the capacitor circuit, the second current transformer is installed on the second circuit of the active filter, and the third current transformer is located between the active filter and the power supply terminal. The three current transformers are connected in series, and the second current transformer is directly electrically connected to the active filter.

4. The CT position determination method using a CT mounting circuit with an APF containing a capacitor as described in claim 1, characterized in that, When the capacitor circuit is connected in parallel on the power supply side, the current transformer is installed as follows: The current transformer is provided in two parts, including a first current transformer and a second current transformer. The first current transformer is connected in series with the active filter, and the second current transformer is located between the capacitor circuit and the active filter. The first current transformer is electrically connected to the second current transformer, and the first current transformer is directly electrically connected to the active filter.

5. The CT position determination method using a CT mounting circuit with an APF containing a capacitor, as described in claim 1, is characterized in that... When the capacitor circuit is connected in parallel on the power supply side, the current transformer is installed as follows: The current transformer is provided in three parts, including a first current transformer, a second current transformer and a third current transformer. The first current transformer is connected in series in the capacitor circuit, the second current transformer is connected in series in the second circuit of the active filter, and the third current transformer is located between the active filter and the power supply terminal. The three current transformers are connected in series, and the second current transformer is directly electrically connected to the active filter.

6. The CT position determination method using a CT mounting circuit with an APF containing a capacitor, as described in claim 1, is characterized in that... It also includes a dual busbar installation method, which is configured as follows: It includes two identical bus structures, each of which includes a power supply end, a load end, an active filter, a first current transformer, and a second current transformer; The first active filter and the second active filter are respectively placed at both ends of the load terminal, and the first circuits of the two bus structures are connected by a switch.

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