Hybrid active amplitude-phase correction device and control method thereof

Abstract

The invention discloses a hybrid active amplitude-phase correction device and a control method thereof, and the device is characterized in that the device comprises a passive amplitude-phase correction module and an active amplitude-phase correction module which are connected with each other; the passive amplitude-phase correction module comprises a high-voltage capacitor, a first reactor, a low-voltage capacitor, a resistor and a first circuit breaker, and is used for switching the device to a passive amplitude-phase correction mode by closing / opening a first target circuit breaker and a first target switch to perform impedance adjustment; the active amplitude-phase correction module comprises a first switch, a second switch, a first grounding switch, a second grounding switch, a second circuit breaker, a third circuit breaker, a current conversion chain, a second reactor and a voltage dividing capacitor; the current conversion chain is formed by cascading a plurality of power units; and the active amplitude-phase correction module is used for switching the device to an active amplitude-phase correction mode by closing / opening a second target circuit breaker and a second target switch to perform impedance adjustment. Impedance characteristics of a power transmission system can be efficiently adjusted, and oscillation risks are reduced.

Description

Technical Field

[0001] The present invention relates to the technical field of direct current power transmission, and in particular to a hybrid active amplitude-phase correction device and a control method thereof. Background Art

[0002] In the context of a high proportion of new energy power electronic grids, the coupling relationship between new energy and DC systems, and between DC systems and AC grids is complex. The entire interconnected system may have multiple resonance points in a wide frequency band, and the risk of system harmonic amplification or oscillation is huge, which seriously affects the safe and stable operation of the DC transmission system.

[0003] Without limiting the system operation mode, there are currently two main solutions: resonance software suppression and hardware suppression. Among them, hardware suppression is to configure an additional amplitude and phase corrector to change the amplitude-frequency and phase-frequency characteristics of the converter output impedance, which can effectively improve the reliability of the project. However, there are many limitations on the adjustment capabilities of a simple passive amplitude and phase corrector or an active amplitude and phase corrector, and it is impossible to effectively adjust the impedance of the power system, resulting in poor harmonic suppression of the transmission system and affecting the stability of the transmission system operation.

[0004] It can be seen that how to improve the amplitude and phase correction device to achieve effective adjustment of the impedance characteristics has become a technical problem that needs to be urgently solved by those skilled in the art. Summary of the invention

[0005] The present invention provides a hybrid active amplitude-phase correction device and a control method thereof, so as to solve the problem of how to improve the amplitude-phase correction device, realize accurate regulation of the impedance of a direct current transmission system, and improve the harmonic suppression effect of the system.

[0006] In order to solve the above technical problems, an embodiment of the present invention provides a hybrid active amplitude-phase correction device, which includes a passive amplitude-phase correction module and an active amplitude-phase correction module connected to each other, wherein:

[0007] The passive amplitude-phase correction module includes a high-voltage capacitor, a first reactance, a low-voltage capacitor, a resistor and a first circuit breaker; the passive amplitude-phase correction module is used to switch the device to a passive amplitude-phase correction mode by closing / opening a first target circuit breaker and a first target switch to perform impedance adjustment;

[0008] The active amplitude-phase correction module includes a first switch, a second switch, a first grounding switch, a second grounding switch, a second circuit breaker, a third circuit breaker, a commutation chain, a second reactance and a voltage-dividing capacitor; the commutation chain is composed of a plurality of power units in cascade; the active amplitude-phase correction module is used to switch the device to an active amplitude-phase correction mode for impedance adjustment by closing / opening a second target circuit breaker and a second target switch.

[0009] Further, when the device is in the passive amplitude and phase correction mode, the first circuit breaker is closed, and the first switch, the first grounding switch and the second circuit breaker are opened.

[0010] Further, when the device is in the active amplitude and phase correction mode, the first circuit breaker, the first switch, the second circuit breaker, the second switch, the first grounding switch, the second grounding switch and the third circuit breaker are all disconnected.

[0011] Furthermore, the passive amplitude-phase correction mode and the active amplitude-phase correction mode can be switched online.

[0012] Furthermore, the switching time of the first circuit breaker is less than 40 ms.

[0013] Furthermore, the active amplitude and phase correction module adjusts the output voltage according to the detected current of the commutation chain to perform impedance regulation of each harmonic.

[0014] Another embodiment of the present invention provides a hybrid active amplitude-phase correction circuit, which is applied to the above hybrid active amplitude-phase correction device, including:

[0015] One end of the high-voltage capacitor is connected to the first end of the first reactor, the second end of the first reactor is connected to the first end of the low-voltage capacitor, the second end of the low-voltage capacitor is connected to the first end of the first circuit breaker, and the second end of the first circuit breaker is grounded; the first end of the resistor is connected between the high-voltage capacitor and the first reactor, and the second end of the resistor is connected between the low-voltage capacitor and the first circuit breaker;

[0016] The first end of the first switch is connected between the resistor and the first circuit breaker, the second end of the first switch is connected to the first end of the second circuit breaker, the first grounding switch is provided between the first switch and the second circuit breaker, the second end of the second circuit breaker is connected to one end of the commutation chain, the other end of the commutation chain and the first end of the second reactance are both grounded, the second end of the second reactance is connected to the first end of the voltage-dividing capacitor, the second end of the voltage-dividing capacitor is connected to the first end of the third circuit breaker, the second end of the third circuit breaker is connected to the first end of the second switch, the second grounding switch is provided between the third circuit breaker and the second switch, and the second end of the second switch is connected between the second circuit breaker and the commutation chain.

[0017] Another embodiment of the present invention provides a control method for a hybrid active amplitude-phase correction device, which is applied to the above hybrid active amplitude-phase correction device, comprising:

[0018] When the first circuit breaker is closed and the device is in the passive amplitude and phase correction mode, the second grounding switch is disconnected, the second switch and the third circuit breaker are closed, and the voltage dividing capacitor is put into operation;

[0019] After the voltage-dividing capacitor is put into operation, the first grounding switch is opened, the first switch and the second circuit breaker are closed, and the commutation chain is put into operation;

[0020] Based on the switched-in commutation chain, disconnecting the first circuit breaker, and controlling the power unit to charge under a preset charging condition;

[0021] When the charging of the power unit is completed, the third circuit breaker is disconnected, and the device is controlled to switch from the passive amplitude and phase correction mode to the active amplitude and phase correction mode.

[0022] Furthermore, the method further comprises:

[0023] After controlling the voltage of the commutation chain to reach a target voltage value, closing the first circuit breaker and opening the second circuit breaker, and controlling the device to switch from the active amplitude-phase correction mode to the passive amplitude-phase correction mode.

[0024] Furthermore, the method further comprises:

[0025] When the active amplitude and phase correction module fails, closing the first circuit breaker to control the power unit to discharge energy;

[0026] When the energy of the power unit is discharged to a preset condition, the second circuit breaker, the first grounding switch, the third circuit breaker and the second grounding switch are closed to perform fault processing.

[0027] Compared with the prior art, the embodiments of the present invention have the following advantages:

[0028] (1) The hybrid active amplitude-phase correction device of the embodiment of the present invention consists of two parts, a passive area and an active area, and can realize flexible conversion between the passive mode and the active mode of the correction device, so as to efficiently adjust the impedance characteristics of the power system and reduce the oscillation risk of the AC and DC systems.

[0029] (2) The circuit structure of the amplitude and phase correction device of the embodiment of the present invention is composed of high-voltage capacitors, low-voltage capacitors, reactors, resistors, circuit breakers, isolating switches and grounding switches, as well as starting resistors, bypass switches and other devices, and a commutation chain formed by cascading multiple power units is arranged in the circuit of the active area part, which can realize the regulation of each harmonic impedance by controlling the voltage output of the commutation chain. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] Figure 1It is a schematic structural diagram of a hybrid active amplitude-phase correction device in one embodiment of the present invention;

[0031] Figure 2 It is a schematic diagram of the impedance control mode structure of an amplitude and phase corrector in an embodiment provided by the present invention;

[0032] Figure 3 It is a schematic flow chart of a control method of a hybrid active amplitude-phase correction device in one embodiment of the present invention. DETAILED DESCRIPTION

[0033] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. The purpose of providing these embodiments is to make the disclosure of the present invention more thorough and comprehensive. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0034] In the description of this application, the terms "first", "second", "third", etc. are used for descriptive purposes only and are not to be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Thus, a feature defined as "first", "second", "third", etc. may explicitly or implicitly include one or more of the feature. In the description of this application, unless otherwise specified, "plurality" means two or more.

[0035] In the description of the present application, it should be noted that, unless otherwise clearly specified and limited, the terms "installed", "connected", and "connected" should be understood in a broad sense. For example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection, or it can be indirectly connected through an intermediate medium, or it can be a connection between the two elements. The terms "vertical", "horizontal", "left", "right", "upper", "lower" and similar expressions used herein are only for illustrative purposes, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation on the present invention. The term "and / or" used herein includes any and all combinations of one or more related listed items. For those of ordinary skill in the art, the specific meanings of the above terms in this application can be understood according to specific circumstances.

[0036] In the description of this application, it should be noted that, unless otherwise defined, all technical and scientific terms used in the present invention have the same meaning as those commonly understood by those skilled in the art. The terms used in the specification of the present invention are only for the purpose of describing specific embodiments and are not intended to limit the present invention. For those of ordinary skill in the art, the specific meanings of the above terms in this application can be understood by specific circumstances.

[0037] An embodiment of the present invention provides a hybrid active amplitude-phase correction device. For details, see Figure 1 , Figure 1 The figure shows a schematic structural diagram of a hybrid active amplitude-phase correction device in one embodiment of the present invention, comprising:

[0038] from Figure 1 It can be seen from the figure that the hybrid active amplitude-phase correction device of this embodiment includes a passive amplitude-phase correction module and an active amplitude-phase correction module connected to each other, namely, a passive region A and an active region B.

[0039] The passive amplitude and phase correction module includes a high voltage capacitor C1, a first reactance L1, a low voltage capacitor C2, a resistor and a first circuit breaker Q1. In some embodiments of the device of the present invention, the first circuit breaker Q1 is a fast circuit breaker.

[0040] The active amplitude and phase correction module includes a first switch Q11, a second switch Q12, a first grounding switch Q21, a second grounding switch Q22, a second circuit breaker Q2, a third circuit breaker Q3, a commutation chain C, a second reactor L2 and a voltage-dividing capacitor C3. In some embodiments of the device of the present invention, Q11 and Q12 can be respectively configured as an isolating switch and a bypass switch, and the second reactor L2 can be designed as a bridge arm reactor.

[0041] It can be seen that the commutation chain C is composed of a plurality of cascaded power units, and the active amplitude-phase correction module adjusts the output voltage of the commutation chain according to the detected commutation chain current generated in the commutation chain to adjust the impedance of each harmonic. Figure 2 , Figure 2 A schematic diagram of the impedance control mode structure of an amplitude and phase corrector in an embodiment provided by the present invention is shown.

[0042] It is understandable that in some embodiments of the present invention, the active amplitude-phase correction module detects the current change in the commutation chain circuit in real time through sensors and other components, and the active amplitude-phase correction module calculates the required output voltage adjustment amount based on the detected current data. Based on this, the active amplitude-phase corrector adjusts the internal power electronic components (such as IGBT, MOSFET, etc.) to adjust the amplitude and phase of the output voltage to achieve precise control of the circuit characteristics.

[0043] By adjusting the output voltage, the active phase-amplitude corrector can change the impedance characteristics of the commutation chain at different frequencies. This means that it can perform targeted impedance adjustment for each harmonic in the transmission system, thereby optimizing the power quality and stability of the transmission system.

[0044] It can be understood that the hybrid active amplitude-phase correction device of this embodiment can realize online conversion between the passive amplitude-phase correction mode and the active amplitude-phase correction mode. Specifically,

[0045] The passive amplitude-phase correction module is used to switch the device to the passive amplitude-phase correction mode by closing / opening the first target circuit breaker and the first target switch to perform impedance adjustment. When the device is in the passive amplitude-phase correction mode, the first circuit breaker Q1 is closed, the first switch Q11, the first grounding switch Q21 and the second circuit breaker Q2 are disconnected, and the device is a C-type passive amplitude-phase corrector, which can provide amplitude-phase correction capability in the medium and high frequency bands.

[0046] Correspondingly, the active amplitude-phase correction module is used to switch the device to the active amplitude-phase correction mode by closing / opening the second target circuit breaker and the second target switch to perform impedance adjustment. When the device is in the active amplitude-phase correction mode, the first circuit breaker Q1, the first switch Q11, the second circuit breaker Q2, the second switch Q12, the first grounding switch Q21, the second grounding switch Q22 and the third circuit breaker Q3 are all in the disconnected state.

[0047] It is worth noting that when opening or closing the circuit breaker Q1, attention should be paid to the switching time, which refers to the time required from receiving the operation instruction to the circuit breaker being fully opened or closed. For example, in some embodiments of the device of the present invention, the switching time of the first circuit breaker is set to be less than 40ms. The time limit can enable the circuit breaker to cut off the fault current or quickly restore power supply in a very short time, which helps to prevent the fault from expanding, reduce the time and scope of power outages, and improve the stability and reliability of the power system.

[0048] In summary, the hybrid active amplitude-phase correction device of the embodiment of the present invention integrates the passive amplitude-phase correction module and the active amplitude-phase correction module, and realizes the impedance adjustment function in the power system through mutual connection and coordination. The device can switch to the passive amplitude-phase correction mode or the active amplitude-phase correction mode as needed. These two modes are respectively realized by closing / opening specific circuit breakers and switches. The passive amplitude-phase correction module uses high-voltage capacitors, reactances and other components to perform impedance adjustment, which is suitable for correction needs under specific conditions, while the active amplitude-phase correction module uses active components such as the commutation chain to perform more precise impedance adjustment, providing higher flexibility and accuracy.

[0049] Based on the above device, an embodiment of the present invention provides a circuit of a hybrid active amplitude-phase correction device. The following is a detailed description of the hybrid active amplitude-phase corrector circuit:

[0050] One end of the high-voltage capacitor is connected to the first end of the first reactance, the second end of the first reactance is connected to the first end of the low-voltage capacitor, the second end of the low-voltage capacitor is connected to the first end of the first circuit breaker, and the second end of the first circuit breaker is grounded; the first end of the resistor is connected between the high-voltage capacitor and the first reactance, and the second end of the resistor is connected between the low-voltage capacitor and the first circuit breaker.

[0051] The first end of the first switch is connected between the resistor and the first circuit breaker, the second end of the first switch is connected to the first end of the second circuit breaker, the first grounding switch is provided between the first switch and the second circuit breaker, the second end of the second circuit breaker is connected to one end of the commutation chain, the other end of the commutation chain and the first end of the second reactance are both grounded, the second end of the second reactance is connected to the first end of the voltage-dividing capacitor, the second end of the voltage-dividing capacitor is connected to the first end of the third circuit breaker, the second end of the third circuit breaker is connected to the first end of the second switch, the second grounding switch is provided between the third circuit breaker and the second switch, and the second end of the second switch is connected between the second circuit breaker and the commutation chain.

[0052] The circuit structure of this embodiment is simple and easy to operate. By turning off the switch and the circuit breaker, the amplitude and phase correction device can be flexibly switched to the passive correction mode and the active correction mode, thereby reducing the oscillation risk of the AC and DC systems.

[0053] An embodiment of the present invention further provides a control method for a hybrid active amplitude-phase correction device, which is applied to the above hybrid active amplitude-phase correction device. For details, see Figure 3 , Figure 3 The flowchart of the control method of the hybrid active amplitude-phase correction device in one embodiment of the present invention is shown, which includes the following steps:

[0054] S1. When the first circuit breaker is closed and the device is in the passive amplitude and phase correction mode, the second grounding switch is disconnected, the second switch and the third circuit breaker are closed, and the voltage dividing capacitor is put into operation.

[0055] This step is to close the circuit breaker Q1 to make the amplitude and phase corrector work in passive mode as the initial state or safe state. Then the grounding switch Q22 will be opened, the bypass switch Q12 and the circuit breaker Q3 will be closed, and the voltage dividing capacitor C3 will be connected to the circuit to prepare for the subsequent commutation chain input.

[0056] S2. After the voltage-dividing capacitor is put into operation, the first grounding switch is opened, the first switch and the second circuit breaker are closed, and the commutation chain is put into operation.

[0057] This step is to connect the commutation link into the circuit and prepare for power conversion.

[0058] S3. Based on the switched-on commutation chain, disconnect the first circuit breaker, and control the power unit to charge under a preset charging condition.

[0059] This step disconnects the circuit breaker Q1 to make the commutation chain enter the uncontrolled charging stage, allowing the power unit capacitor to charge naturally. When the power unit capacitor is charged to the set value, the commutation chain enters the controlled charging stage. Disconnecting Q1 is to switch the amplitude and phase corrector from the passive mode to the active mode charging stage.

[0060] S4. When the charging of the power unit is completed, disconnect the third circuit breaker and control the device to switch from the passive amplitude and phase correction mode to the active amplitude and phase correction mode.

[0061] In this step, the commutation chain enters the normal operation mode and starts active amplitude and phase correction.

[0062] It can be seen that the order of inputting the hybrid active amplitude and phase correction device in this embodiment enables the device to switch from the passive mode to the active mode to adjust the impedance.

[0063] In this embodiment, if the device is to enter the passive amplitude and phase correction mode from the active amplitude and phase correction mode, that is, the hybrid active amplitude and phase correction device is to exit normally, the exit sequence is:

[0064] After controlling the voltage of the commutation chain to reach the target voltage value, in this embodiment, the commutation chain voltage is controlled to be 0 to ensure safe shutdown, the first circuit breaker is closed and the second circuit breaker is opened, and the device is controlled to switch from the active amplitude-phase correction mode to the passive amplitude-phase correction mode.

[0065] Furthermore, in some embodiments of the present invention, when the active amplitude-phase correction module fails, the first circuit breaker is closed to control the power unit to discharge energy;

[0066] When the energy of the power unit is discharged to a preset condition, the second circuit breaker, the first grounding switch, the third circuit breaker and the second grounding switch are closed to perform reliable grounding and then perform subsequent fault processing.

[0067] The above-mentioned embodiments only express several implementation methods of the present invention, and the description thereof is relatively specific and detailed, but it cannot be understood as limiting the scope of the patent of the present invention. It should be pointed out that, for ordinary technicians in this field, several variations and improvements can be made without departing from the concept of the present invention, which all belong to the protection scope of the present invention. Therefore, the protection scope of the patent of the present invention shall be subject to the attached claims.

Claims

1. A hybrid active amplitude-phase correction device, characterized in that: The device comprises a passive amplitude-phase correction module and an active amplitude-phase correction module connected to each other, wherein: The passive amplitude-phase correction module includes a high-voltage capacitor, a first reactance, a low-voltage capacitor, a resistor and a first circuit breaker; the passive amplitude-phase correction module is used to switch the device to a passive amplitude-phase correction mode by closing / opening a first target circuit breaker and a first target switch to perform impedance adjustment; The active amplitude-phase correction module includes a first switch, a second switch, a first grounding switch, a second grounding switch, a second circuit breaker, a third circuit breaker, a commutation chain, a second reactance and a voltage-dividing capacitor; the commutation chain is composed of a plurality of power units in cascade; the active amplitude-phase correction module is used to switch the device to an active amplitude-phase correction mode for impedance adjustment by closing / opening a second target circuit breaker and a second target switch.

2. The hybrid active amplitude-phase correction device according to claim 1, characterized in that: When the device is in the passive amplitude and phase correction mode, the first circuit breaker is closed, and the first switch, the first grounding switch and the second circuit breaker are opened.

3. The hybrid active amplitude-phase correction device according to claim 1, characterized in that: When the device is in the active amplitude and phase correction mode, the first circuit breaker, the first switch, the second circuit breaker, the second switch, the first grounding switch, the second grounding switch and the third circuit breaker are all disconnected.

4. The hybrid active amplitude-phase correction device according to claim 1, characterized in that: The passive amplitude-phase correction mode and the active amplitude-phase correction mode can be switched online.

5. The hybrid active amplitude-phase correction device according to claim 1, characterized in that: The switching time of the first circuit breaker is less than 40 ms.

6. The hybrid active amplitude-phase correction device according to claim 1, characterized in that: The active amplitude and phase correction module adjusts the output voltage according to the detected current of the commutation chain to adjust the impedance of each harmonic.

7. A circuit of a hybrid active amplitude-phase correction device, applied to the hybrid active amplitude-phase correction device according to claims 1 to 6, characterized in that: One end of the high-voltage capacitor is connected to the first end of the first reactor, the second end of the first reactor is connected to the first end of the low-voltage capacitor, the second end of the low-voltage capacitor is connected to the first end of the first circuit breaker, and the second end of the first circuit breaker is grounded; the first end of the resistor is connected between the high-voltage capacitor and the first reactor, and the second end of the resistor is connected between the low-voltage capacitor and the first circuit breaker; The first end of the first switch is connected between the resistor and the first circuit breaker, the second end of the first switch is connected to the first end of the second circuit breaker, the first grounding switch is provided between the first switch and the second circuit breaker, the second end of the second circuit breaker is connected to one end of the commutation chain, the other end of the commutation chain and the first end of the second reactance are both grounded, the second end of the second reactance is connected to the first end of the voltage-dividing capacitor, the second end of the voltage-dividing capacitor is connected to the first end of the third circuit breaker, the second end of the third circuit breaker is connected to the first end of the second switch, the second grounding switch is provided between the third circuit breaker and the second switch, and the second end of the second switch is connected between the second circuit breaker and the commutation chain.

8. A control method for a hybrid active amplitude-phase correction device, applied to the hybrid active amplitude-phase correction device according to claims 1 to 6, characterized in that: include: When the first circuit breaker is closed and the device is in the passive amplitude and phase correction mode, the second grounding switch is disconnected, the second switch and the third circuit breaker are closed, and the voltage dividing capacitor is put into operation; After the voltage-dividing capacitor is put into operation, the first grounding switch is opened, the first switch and the second circuit breaker are closed, and the commutation chain is put into operation; Based on the switched-in commutation chain, disconnecting the first circuit breaker, and controlling the power unit to charge under a preset charging condition; When the charging of the power unit is completed, the third circuit breaker is disconnected, and the device is controlled to switch from the passive amplitude and phase correction mode to the active amplitude and phase correction mode.

9. The control method of the hybrid active amplitude-phase correction device according to claim 8, characterized in that: The method further comprises: After controlling the voltage of the commutation chain to reach a target voltage value, closing the first circuit breaker and opening the second circuit breaker, and controlling the device to switch from the active amplitude-phase correction mode to the passive amplitude-phase correction mode.

10. The control method of the hybrid active amplitude-phase correction device according to claim 8, characterized in that: The method further comprises: When the active amplitude and phase correction module fails, closing the first circuit breaker to control the power unit to discharge energy; When the energy of the power unit is discharged to a preset condition, the second circuit breaker, the first grounding switch, the third circuit breaker and the second grounding switch are closed to perform fault processing.

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