Equivalent circuit of controllable phase commutated converter and control method thereof

Abstract

The application provides an equivalent circuit of a controllable phase commutated converter and a control method thereof, comprising a first simulation module, a second simulation module, a saturated reactor and a power component, the power component comprising a semiconductor device, the first simulation module comprising a first charging unit and a first discharging unit, the first charging unit being configured to charge the first discharging unit, and the first discharging unit being configured to discharge to the second simulation module through the saturated reactor to simulate the discharge of a lightning arrester connected in parallel across a single converter valve in the controllable phase commutated converter; the second simulation module comprising a second charging unit and a second discharging unit, the second charging unit being configured to charge the second discharging unit, and the second discharging unit being configured to discharge to the semiconductor device to simulate the discharge of a lightning arrester connected in parallel across the semiconductor device in the converter valve, thereby solving the problem that the non-periodic triggering working condition of simultaneous discharge of the two types of lightning arrester in the hybrid controllable phase commutated converter cannot be accurately simulated.

Description

Technical Field

[0001] This application relates to the field of power electronics technology, and more specifically, to an equivalent circuit of a controllable commutated converter and its control method. Background Technology

[0002] The hybrid controllable commutator incorporates two types of surge arresters. On the power electronic device side, device-level surge arresters are connected in parallel across the device to achieve amplitude limiting and voltage equalization. On the single valve side, valve surge arresters are connected in parallel across the valve to protect the entire valve. During non-periodic triggering, both the valve surge arrester and the device-level surge arrester discharge current simultaneously. The surge arresters connected in parallel across the device do not discharge current through a saturated reactor but directly to the power electronic device, failing to simulate the process of surge arresters connected in parallel across the power electronic device directly discharging current to the power electronic device. Summary of the Invention

[0003] The main objective of this application is to provide an equivalent circuit and control method for a controllable commutator, so as to at least solve the problem in the related art that it is impossible to accurately simulate the non-periodic triggering condition of two surge arresters simultaneously discharging in a hybrid controllable commutator.

[0004] To achieve the above objectives, according to one aspect of this application, an equivalent circuit of a controllable commutation converter is provided, comprising: a first analog module, a second analog module, a saturated reactor, and a power component, wherein the power component includes semiconductor devices, wherein the first analog module includes a first charging unit and a first discharging unit, a first terminal of the first charging unit is electrically connected to the first discharging unit, a first terminal of the first charging unit is electrically connected to a second terminal of the first discharging unit, and a first terminal of the first discharging unit is electrically connected to a first terminal of the saturated reactor, the first charging unit is used to charge the first discharging unit, and the first discharging unit is used to discharge to the second analog module through the saturated reactor, to simulate a single commutation valve connected in parallel across the controllable commutation converter. The surge arrester discharges current; the second simulation module includes a second charging unit and a second discharging unit, wherein the power component is connected in parallel with the second charging unit, the power component is connected in parallel with the second discharging unit, the first end of the power component is electrically connected to the first end of the second discharging unit and the second end of the saturated reactor, the second end of the power component is electrically connected to the second end of the first discharging unit, the second end of the second discharging unit and the second end of the second charging unit, the first end of the second charging unit is electrically connected to the second discharging unit, the second charging unit is used to charge the second discharging unit, and the second discharging unit is used to discharge to the semiconductor device to simulate the surge arrester discharges current of the semiconductor device connected in parallel in the converter valve.

[0005] Optionally, the first charging unit includes a first charging device and a first switch, wherein the two ends of the first charging device are electrically connected to the first end of the first switch and the second end of the first discharging unit, respectively, and the second end of the first switch is connected to the first end of the first discharging unit.

[0006] Optionally, the first discharge unit includes a first charging capacitor, a second switch, and a first discharge resistor. The first end of the first charging capacitor is connected to the first end of the first charging unit and the first end of the first discharge resistor, respectively. The second end of the first charging capacitor is electrically connected to the second end of the first charging unit, the second end of the power component, and the second end of the second discharge unit, respectively. The second end of the second switch is electrically connected to the first end of the saturated reactor.

[0007] Optionally, the second discharge unit includes a second energy replenishing capacitor, a third switch, and a second discharge resistor, wherein the first end of the second discharge resistor is electrically connected to the first end of the power component and the second end of the saturated reactor, the second end of the second discharge resistor is connected to the first end of the third switch, the second end of the third switch is connected to the first end of the second energy replenishing capacitor and the first end of the second charging unit, and the second end of the second energy replenishing capacitor is electrically connected to the second end of the power component and the second end of the second charging unit.

[0008] Optionally, the second charging unit includes a second charging device and a fourth switch, wherein the two ends of the fourth switch are electrically connected to the second discharging unit and the first end of the second charging device, respectively, and the second end of the second charging device is electrically connected to the second end of the second discharging unit and the second end of the power component, respectively.

[0009] Optionally, the equivalent circuit further includes a current establishment module, which includes a third charging unit and a third discharging unit. The first end of the third discharging unit is electrically connected to the first end of the saturated reactor and the first end of the first discharging unit, respectively. The second end of the third discharging unit is electrically connected to the second end of the saturated reactor and the second end of the third charging unit, respectively. The first end of the third charging unit is electrically connected to the third discharging unit.

[0010] Optionally, the third charging unit includes a third charging device and a fifth switch. The two ends of the fifth switch are respectively connected to the first end of the third charging device and the third discharging unit, and the second end of the third charging device is electrically connected to the second end of the third discharging unit and the second end of the saturated reactor.

[0011] Optionally, the third discharge unit includes: a third energy-replenishing capacitor, a third discharge resistor, a sixth switch, a first inductor, a fourth discharge resistor, and a seventh switch, wherein the third discharge resistor and the sixth switch are connected in series, the branch of the third discharge resistor and the sixth switch connected in series is connected in parallel with the third energy-replenishing capacitor, the first end of the first inductor is electrically connected to the first end of the saturated reactor and the first end of the first discharge unit, the second end of the first inductor is electrically connected to the first end of the fourth discharge resistor, and the two ends of the seventh switch are electrically connected to the second end of the fourth discharge resistor and the first end of the third energy-replenishing capacitor, respectively.

[0012] According to another aspect of this application, a control method for the equivalent circuit of a controllable commutation converter is provided, for controlling the equivalent circuit of the controllable commutation converter, the control method comprising: controlling the first charging unit of the first analog module of the equivalent circuit to turn on, so that the first charging unit charges the first discharging unit of the first analog module; controlling the second charging unit of the second analog module of the equivalent circuit to turn on, so that the second charging unit charges the second discharging unit of the second analog module; controlling the first discharging unit and the second discharging unit to turn on simultaneously, so that the first discharging unit discharges to the power component through the saturated reactor of the equivalent circuit to simulate the leakage of the surge arrester connected in parallel across a single converter valve in the controllable commutation converter, and causing the second discharging unit to discharge to the power component of the second analog module to simulate the leakage of the surge arrester connected in parallel across the semiconductor device in the controllable commutation converter.

[0013] By applying the technical solution of this application, a first simulation module and a second simulation module are set in the equivalent circuit. When the power component of the second simulation module is not triggered, the first charging unit of the first simulation module is used to charge the first discharging unit of the first simulation module. After charging is completed, when the power component is turned on, the first discharging unit of the first simulation module discharges current to the power component, simulating the discharge of a valve-type surge arrester. The second simulation module includes a second charging unit and a second discharging unit connected in parallel with the power component, which can independently control the charging and discharging of the device-level surge arrester, providing accurate simulation of the device-level surge arrester. This allows the discharge process of the device-level surge arrester to be synchronized with and independent of the process of the valve-type surge arrester, improving the overall controllability and accuracy of the test. Through two independent and cooperative modules, the discharge characteristics of the device-level surge arrester and the discharge characteristics of the valve-type surge arrester are simulated, ensuring that each module can accurately match the actual working conditions, avoiding the test result deviation caused by the mutual influence between modules in traditional test methods, effectively reproducing the actual stress conditions of the hybrid controllable commutation converter in the non-periodic triggering process, and significantly improving the fidelity and reliability of the test results. Attached Figure Description

[0014] The accompanying drawings, which form part of this application, are used to provide a further understanding of this application. The illustrative embodiments and descriptions of this application are used to explain this application and do not constitute an undue limitation of this application. In the drawings:

[0015] Figure 1 An equivalent circuit block diagram of a controllable commutator provided in an embodiment of this application is shown;

[0016] Figure 2 A schematic diagram of a controllable commutation converter provided in an embodiment of this application is shown;

[0017] Figure 3 An equivalent circuit block diagram of another controllable commutated converter provided in an embodiment of this application is shown;

[0018] Figure 4 An equivalent circuit block diagram of a controllable commutation converter provided in an embodiment of this application is shown.

[0019] Figure 5 A schematic diagram of the equivalent circuit simulating current leakage of a controllable commutator provided in an embodiment of this application is shown;

[0020] Figure 6 A flowchart illustrating a control method for an equivalent circuit of a controllable commutated converter provided in an embodiment of this application is shown.

[0021] The above figures include the following reference numerals:

[0022] 1. Voltage surge source; 2. Commutation inductor; 3. Stray capacitance; 4. Preset saturation reactor; 5. Device assembly; 6. Valve-type surge arrester; 7. Power device; 8. Buffer circuit resistor; 9. Buffer circuit capacitor; 10. First analog module; 11. First charging unit; 111. First charging device; 112. First switch; 12. First discharging unit; 121. First energy replenishment capacitor; 122. Second switch; 123. First discharge resistor; 13. DC resistor; 14. Device-level surge arrester; 20. Second analog module; 30. Saturation reactor ; 40. Power component; 21. Second charging unit; 211. Second charging device; 212. Fourth switch; 22. Second discharging unit; 221. Second energy replenishing capacitor; 222. Third switch; 223. Second discharging resistor; 50. Current establishment module; 51. Third charging unit; 511. Third charging device; 512. Fifth switch; 52. Third discharging unit; 521. Third energy replenishing capacitor; 522. Third discharging resistor; 523. Sixth switch; 524. First inductor; 525. Fourth discharging resistor; 526. Seventh switch. Detailed Implementation

[0023] It should be noted that, unless otherwise specified, the embodiments and features described in this application can be combined with each other. This application will now be described in detail with reference to the accompanying drawings and embodiments.

[0024] To enable those skilled in the art to better understand the present application, the technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present application, and not all embodiments. Based on the embodiments in the present application, all other embodiments obtained by those of ordinary skill in the art without creative effort should fall within the scope of protection of the present application.

[0025] It should be noted that the terms "first," "second," etc., in the specification, claims, and accompanying drawings of this application are used to distinguish similar objects and are not necessarily used to describe a specific order or sequence. It should be understood that such data can be interchanged where appropriate for the embodiments of this application described herein. Furthermore, the terms "comprising" and "having," and any variations thereof, are intended to cover non-exclusive inclusion; for example, a process, method, system, product, or apparatus that comprises a series of steps or units is not necessarily limited to those steps or units explicitly listed, but may include other steps or units not explicitly listed or inherent to such processes, methods, products, or apparatus.

[0026] As described in the background section, in related technologies, during non-periodic triggering, both the valve arrester and the device-level arrester discharge current simultaneously. The arrester connected in parallel across the device does not discharge current through a saturated reactor, but directly discharges current to the power electronic device. This cannot simulate the process of the arrester connected in parallel across the power electronic device directly discharging current to the power electronic device. To solve the problem of not being able to accurately simulate the non-periodic triggering condition where both types of arresters discharge current simultaneously in a hybrid controllable commutator, the embodiments of this application provide an equivalent circuit of a controllable commutator and its control method.

[0027] The technical solutions in the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings.

[0028] According to one aspect of the embodiments of this application, such as Figure 1As shown, an equivalent circuit of a controllable commutation converter is provided, including: a first simulation module 10, a second simulation module 20, a saturated reactor 30, and a power component 40. The first simulation module 10 includes a first charging unit 11 and a first discharging unit 12. A first terminal of the first charging unit 11 is electrically connected to the first discharging unit 12, and a second terminal of the first charging unit 11 is electrically connected to the second terminal of the first discharging unit 12. A first terminal of the first discharging unit 12 is electrically connected to the first terminal of the saturated reactor 30. The first charging unit 11 charges the first discharging unit 12, and the first discharging unit 12 discharges through the saturated reactor 30 to the second simulation module 20, simulating the leakage current of a surge arrester connected in parallel across a single converter valve in the controllable commutation converter. The simulation module 20 includes a second charging unit 21 and a second discharging unit 22. The power component 40 is connected in parallel with the second charging unit 21 and the second discharging unit 22. The first end of the power component 40 is electrically connected to the first end of the second discharging unit 22 and the second end of the saturated reactor 30, respectively. The second end of the power component 40 is electrically connected to the second end of the first discharging unit 12, the second end of the second discharging unit 22, and the second end of the second charging unit 21, respectively. The first end of the second charging unit 21 is electrically connected to the second discharging unit 22. The second charging unit 21 is used to charge the second discharging unit 22, and the second discharging unit 22 is used to discharge to the power component 40 to simulate the leakage of the surge arrester connected in parallel across the semiconductor device in the converter valve.

[0029] By setting up a first simulation module and a second simulation module in the equivalent circuit, when the power component of the second simulation module is not triggered, the first charging unit of the first simulation module charges the first discharging unit of the first simulation module. After charging is completed, when the power component is turned on, the first discharging unit of the first simulation module discharges current to the power component, simulating the discharge of a valve-type surge arrester. The second simulation module includes a second charging unit and a second discharging unit connected in parallel with the power component, which can independently control the charging and discharging of the device-level surge arrester, providing accurate simulation of the device-level surge arrester. This allows the discharge process of the device-level surge arrester to be synchronized and independent with the process of the valve-type surge arrester, improving the overall controllability and accuracy of the test. Through two independent and coordinated modules, the discharge characteristics of the device-level surge arrester and the discharge characteristics of the valve-type surge arrester are simulated, ensuring that each module can accurately match the actual operating conditions, avoiding the test result deviation caused by the mutual influence between modules in traditional test methods, effectively reproducing the actual stress conditions of the hybrid controllable commutation converter in the non-periodic triggering process, and significantly improving the fidelity and reliability of the test results.

[0030] In the above embodiments, the non-periodic triggering condition refers to the situation where, during an operational shock to a hybrid controllable commutator, the power devices are in an off-state and subjected to excessively high voltage. To prevent damage to the power devices, it is necessary to trigger them to turn on to protect them. For example... Figure 2 As shown, the hybrid controllable commutation converter mainly includes an operating voltage impulse source 1, a commutation inductor 2, a stray capacitor 3, a preset saturated reactor 4, a device assembly 5, and a valve-type surge arrester 6. The device assembly 5 includes a power device 7, a buffer circuit resistor 8, a buffer circuit capacitor 9, a DC resistor 13, and a device-level surge arrester 14. When the operating voltage impulse source 1 discharges, the valve-type surge arrester 6 and the device-level surge arrester 14 establish a large current. After meeting the power electronic triggering conditions, the power device 7 (in this application, a semiconductor device in the power assembly) is triggered. The valve-type surge arrester 6 and the device-level surge arrester 14 simultaneously discharge current to the power device 7. The device-level surge arrester connected in parallel across the power device 7 does not discharge current through the saturated reactor, but directly discharges current to the semiconductor device. However, in previous equivalent test circuits, the capacitor discharge was entirely through the saturated reactor, and the current rise rate was limited by the saturated reactor, making it impossible to simulate the process of the surge arrester connected in parallel across the power electronic device directly discharging current to the power electronic device. The equivalent circuit of this application enables both valve-type surge arresters and device-level surge arresters to simultaneously discharge current to semiconductor devices, while accurately simulating the inductance state of the saturated reactor and its role in limiting the current rise rate when the device is triggered. This allows for reliable simulation of the discharge characteristics of valve-type surge arresters and device-level surge arresters.

[0031] In some alternative implementations, such as Figure 3 and Figure 4 As shown, the first charging unit includes a first charging device 111 and a first switch 112. The two ends of the first charging device 111 are electrically connected to the first end of the first switch 112 and the second end of the first discharging unit 12, respectively. The second end of the first switch 112 is electrically connected to the first discharging unit 12. The first charging device 111 provides the required high voltage, while the first switch 112 controls the charging current and process. The first charging device 111 charges the first discharging unit 12 through the first switch 112. After charging is complete, the first discharging unit 12 discharges through the saturated reactor 30 to the power component 40 by triggering the discharge switch, simulating the current discharge process of the surge arrester to the power electronic device. By adjusting the voltage output of the first charging device 111, the surge arrester response under actual operating conditions can be accurately replicated.

[0032] In some alternative implementations, such as Figure 3 and Figure 4As shown, the first discharge unit includes a first charging capacitor 121, a second switch 122, and a first discharge resistor 123. The first terminal of the first charging capacitor 121 is connected to the first terminal of the first charging unit and the first terminal of the first discharge resistor 123. The second terminal of the first discharge resistor 123 is connected to the first terminal of the second switch 122. The second terminal of the first charging capacitor 121 is electrically connected to the second terminal of the first charging unit 11, the second terminal of the power component 40, and the second terminal of the second discharge unit 22. The second terminal of the second switch 122 is electrically connected to the first terminal of the saturated reactor 30. After charging, the first charging capacitor 121 can rapidly release its stored energy through the first discharge resistor 123 and the control switch 122, effectively simulating and controlling the non-periodic current discharge of the valve arrester, thus mimicking the current discharge of the valve arrester. This structure ensures that the current flows along the correct path, simulating the current distribution under actual operating conditions.

[0033] In some alternative implementations, such as Figure 3 and Figure 4 As shown, the second charging unit includes a second charging device 211 and a fourth switch 212. The two ends of the fourth switch 212 are electrically connected to the second discharging unit and the first end of the second charging device 211, respectively. The second end of the second charging device 211 is electrically connected to the second end of the second discharging unit and the second end of the power component, respectively. The second charging device 211 charges the second discharging unit through the fourth switch 212. After charging is complete, the second discharging unit directly discharges to the power component through the device's discharge resistor. This second charging unit ensures that the second discharging unit can be charged to a specific voltage to simulate the current leakage of a device-level surge arrester. The second charging device 211 provides the required voltage, and the fourth switch 212 is used to regulate the charging current and process, achieving a high degree of simulation of the current leakage characteristics of a device-level surge arrester.

[0034] In some alternative implementations, such as Figure 3 and Figure 4As shown, the second discharge unit includes a second energy-replenishing capacitor 221, a third switch 222, and a second discharge resistor 223. The first terminal of the second discharge resistor 223 is electrically connected to the first terminal of the power component and the second terminal of the saturated reactor 30, respectively. The second terminal of the second discharge resistor 223 is connected to the first terminal of the third switch 222. The second terminal of the third switch 222 is connected to the first terminal of the second energy-replenishing capacitor 221 and the first terminal of the second charging unit, respectively. The second energy-replenishing capacitor 221, by controlling the opening of the third switch 222, simulates the current leakage of a device-level surge arrester, directly discharging current to the power component. The second discharge resistor 223 is used to adjust the current steepness and peak value of the leakage current, ensuring that the response of the device-level surge arrester under different operating conditions can be accurately reproduced.

[0035] In cases where it is still necessary to simulate the current of the saturated reactor, in some alternative implementations, such as Figure 4 As shown, the equivalent circuit also includes a current establishment module 50, which includes a third charging unit 51 and a third discharging unit 52. The first end of the third discharging unit 52 is electrically connected to the first end of the saturated reactor 30 and the first end of the first discharging unit, respectively. The second end of the third discharging unit 52 is electrically connected to the second end of the saturated reactor 30 and the second end of the third charging unit 51, respectively. The first end of the third charging unit 51 is electrically connected to the third discharging unit 52. The current establishment module 50 can establish the current in the equivalent circuit before the power component 40 is triggered. This allows for accurate simulation of the current established by the saturated reactor 30 in the hybrid controllable commutator under different insulation coordination strategies for the device surge arrester and the inductance state it exhibits when turned on. Under different insulation coordination strategies for the surge arrester and the valve surge arrester, the current on the saturated reactor is different when the device is triggered. The inductance of the saturated reactor 30 changes with the current magnitude. The larger the current, the smaller the inductance of the saturated reactor 30. When a certain value is exceeded, the inductance of the saturated reactor 30 becomes only an air core inductance. Therefore, based on the insulation coordination of the two surge arresters, the current established by the saturated reactor 30 when the device is triggered can be determined. The corresponding current can be applied to the saturated reactor 30 through the current establishment loop.

[0036] The arrangement of the third charging unit 51, the third discharging unit 52, and the saturated reactor 30 ensures that the required preset current of the saturated reactor 30 can be established and maintained before the semiconductor device is triggered, and that energy can be released along a predetermined path after triggering. After setting the preset current, the inductance of the saturated reactor 30 changes according to the actual situation, thus simulating the operation of the converter valve under different inductance conditions. If the operating condition of the converter valve is that the saturated reactor 30 hardly establishes any current, the preset current can be omitted during the simulation, allowing the saturated reactor 30 to operate under a large inductance condition. The current establishment module enables the equivalent circuit to simulate the inductance of the saturated reactor under different insulation coordination strategies of the surge arrester and the valve surge arrester, and under different current conditions on the saturated reactor when the device is triggered. This broadens the application scenarios and makes the application of the equivalent circuit more flexible.

[0037] In some alternative implementations, such as Figure 4 As shown, the third charging unit 51 includes a third charging device 511 and a fifth switch 512. The two ends of the fifth switch 512 are connected to the first end of the third charging device 511 and the third discharging unit, respectively. The second end of the third charging device 511 is electrically connected to the second end of the third discharging unit and the second end of the saturated reactor 30, respectively. The third charging device 511 charges the third replenishing capacitor 521 through the fifth switch 512. After charging is complete, the third replenishing capacitor 521 discharges into the saturated reactor 30 through an inductor and a current-carrying switch, thereby establishing the required preset current before the power component is triggered. By adjusting the voltage of the third charging device 511, the charging voltage of the saturated reactor can be precisely adjusted, and by controlling the fifth switch 512, current leakage can be controlled.

[0038] In some alternative implementations, such as Figure 4As shown, the third discharge unit 52 includes: a third energy replenishing capacitor 521, a third discharge resistor 522, a sixth switch 523, a first inductor 524, a fourth discharge resistor 525, and a seventh switch 526. The third discharge resistor 522 and the sixth switch 523 are connected in series, and the branch formed by the series connection of the third discharge resistor 522 and the sixth switch 523 is connected in parallel with the third energy replenishing capacitor 521. The first terminal of the first inductor 524 is electrically connected to the first terminal of the saturated reactor 30 and the first terminal of the first discharge unit 12, respectively. The second terminal of the first inductor 524 is electrically connected to the first terminal of the fourth discharge resistor 525, respectively. The two terminals of the seventh switch 526 are connected to the second terminal of the fourth discharge resistor 525 and the first terminal of the third energy replenishing capacitor 521, respectively. Through the combined use of the third energy replenishing capacitor 521 and the first inductor 524, a stable preset current can be established in the saturated reactor 30, ensuring the energy release path when the power component is triggered. This achieves the establishment and maintenance of the reactor's preset current, as well as the rapid release of the current after triggering, improving the overall accuracy and reliability of the test.

[0039] The charging devices mentioned above can be selected as constant current sources at low voltages and impulse voltage generators at high and ultra-high voltages.

[0040] The equivalent circuit described above can be decomposed into three stages:

[0041] Phase 1 is the pre-charging phase: the power component is not triggered, the first charging device charges the first energy replenishment capacitor, the second charging device charges the second energy replenishment capacitor, and the third charging device charges the third energy replenishment capacitor.

[0042] Phase 2 is the saturated reactor current establishment phase: the sixth switch is turned on, and the third energy-replenishing capacitor discharges to the saturated reactor through the first inductor to establish and maintain the required preset current before the power component is triggered;

[0043] Phase 3 is the trigger discharge phase: the power component is triggered to turn on, and the first energy-replenishing capacitor connected in parallel across the single valve discharges to the power electronic device through the saturated reactor, simulating the discharge process of the valve-type surge arrester; at the same time, the second energy-replenishing capacitor connected in parallel across the power component discharges directly to the power component through the second discharge resistor, simulating the discharge process of the device-level surge arrester.

[0044] Taking a 120kV hybrid controllable phase converter as an example, the current shunting curves of device-level surge arresters and valve-type surge arresters are obtained through simulation or calculation, such as... Figure 5As shown, the device-level surge arrester establishes a current of 2000A, the valve-level surge arrester establishes a current of 1000A, and the saturated reactor has the same current as the device-level surge arrester, also establishing a current of 2000A. This has brought the saturated reactor to saturation, exhibiting a small inductance, approximately the value of an air-core inductance. Subsequently, the protective semiconductor device is triggered to turn on. The device-level surge arrester will directly transfer 2000A of current to the semiconductor device, while the valve-type surge arrester will transfer current to the semiconductor device through the saturated reactor. The current of the semiconductor device (power electronic device) receives the leakage current from both the device-level surge arrester and the valve-type surge arrester. The above fully illustrates the non-periodic triggering process of the controllable commutation valve. As can be seen from the above analysis, this process is completely different from that of a conventional commutation valve, mainly in that: the current is not entirely established on the valve-level surge arrester; there will be a current shunting between the device-level and valve-type surge arresters, and the current distribution is related to the parameters of the valve-type and device-type surge arresters. Before the semiconductor device is turned on, the saturated reactor has already established the same current as the device's surge arrester. The magnitude of this current affects the effectiveness of the saturated reactor in limiting the rate of current rise. Since the device's surge arrester is directly connected in parallel across the device, the saturated reactor can only limit the current transfer of the valve surge arrester, but cannot affect the current transfer of the device's surge arrester.

[0045] Before the power components are turned on, the saturated reactor has already established current; this part is simulated by the current establishment module. First, the third charging device charges the third replenishing capacitor through the fifth switch. After charging is complete, the sixth switch is turned on, and the third replenishing capacitor discharges to the saturated reactor through the fourth discharge resistor and the first inductor, allowing the saturated reactor to maintain its current level. Figure 5 The current established by the device-level surge arrester is shown. Finally, the discharge of the third energy-replenishing capacitor can be completed through the third discharge resistor and the sixth switch.

[0046] By adjusting the charging voltages of the first and second charging devices and controlling the charging current, the first and second charging capacitors are ensured to be charged to the target voltage. After the third charging capacitor is fully charged, the power component is triggered to turn on, and the second and third switches are simultaneously turned on, ensuring that the first charging capacitor discharges to the power component through the saturated reactor, and the second charging capacitor discharges directly to the power component through the second discharge resistor.

[0047] Device-level surge arresters are typically directly connected across expensive devices such as IGCTs to protect them from overvoltage damage. This application utilizes a second replenishing capacitor and a second discharge resistor connected in series to independently adjust the peak current, steepness, and energy discharged to the device. Furthermore, the current establishment module in the circuit can simulate the current already present in the saturated reactor before the device is turned on, thus enabling the equivalent circuit to accurately reproduce the operating characteristics of the device's surge arrester and its stress effects on the device.

[0048] In some embodiments, to further improve the safety and operational stability of the non-periodic triggering test circuit, a temperature sensor is installed at the energy replenishment capacitor or discharge resistor to monitor temperature changes in critical components in real time. The temperature sensor can be a thermocouple, thermistor, or fiber optic temperature sensor, capable of reliable operation in high-voltage, high-electromagnetic environments. To achieve closed-loop temperature control, a cooling system and a protection system are provided in the equivalent circuit. The cooling system may include a forced air cooling device or a liquid cooling circulation device, used to automatically adjust the flow rate or air velocity of the cooling medium based on the detected temperature signal. When the temperature sensor detects that the local temperature exceeds a preset threshold, the control unit automatically increases the operating power of the cooling system to quickly remove local heat and maintain the system temperature within the set range. If the temperature continues to rise and reaches a safety threshold, the protection system will be triggered. The protection system may include a fast circuit breaker, a bypass circuit, or a controllable switching unit. When the protection system is activated, the control unit issues a command based on the temperature signal to rapidly transfer the main circuit current to the protection branch or directly disconnect it, thereby preventing damage to the capacitor, discharge resistor, and power electronic devices due to overheating. By introducing an integrated design of temperature monitoring, cooling and protection into the test circuit, this application can achieve thermal management and over-temperature protection for key components such as the energy replenishment capacitor and discharge resistor. This not only improves the safety and repeatability of non-periodic triggering tests, but also ensures the accuracy of test results and the long-term reliable operation of the circuit system.

[0049] In some embodiments, to accommodate different test voltage levels and safety isolation requirements, the non-periodic triggering test circuit of this application can add isolating switches at relevant isolation locations. The isolating switches can be in the form of mechanical high-voltage isolating switches, vacuum circuit breakers, gas-insulated isolating devices, or solid-state isolating switches, etc., used to achieve electrical isolation between different parts of the test circuit, preventing interference from high-voltage circuits to low-voltage measurement, control, and triggering systems, and improving the operational safety and reliability of the test system. Although the specific locations of the isolating switches are not explicitly shown in the accompanying drawings, based on the circuit topology of this application, isolation devices can be set as needed according to different test voltage levels, test modes, and control strategies. For example, an isolating switch can be set between the energy replenishment capacitor and the main discharge circuit to cut off the energy storage branch before and after the test, preventing accidental triggering of discharge; an isolating switch can be set between the impulse capacitor generator and the resistor circuit to control the discharge path and discharge rate; an isolating device can also be arranged between the power input terminal and the control module to achieve rapid disconnection protection under live maintenance, test switching, or abnormal conditions. Furthermore, the control method of the isolating switches can adopt manual operation, remote electrical control, or automatic interlocking linkage according to system requirements. When overvoltage, abnormal temperature, or short-circuit risk is detected, the disconnecting switch can be automatically activated by the protection system to isolate the faulty branch from the main circuit, thereby preventing the spread of local faults and ensuring the safety of personnel and equipment. Through the above design, this application achieves hierarchical isolation and flexible configuration of the test circuit, significantly improving the electrical safety and maintenance convenience of the system.

[0050] In another extended embodiment, to adapt to different test current amplitudes, energy levels, and equivalent discharge requirements, the discharge branch of this application can adopt a multi-capacitor discharge circuit in parallel to achieve current expansion. By connecting two or more sets of capacitor discharge units in parallel on the main discharge branch, the required simulated current waveform, discharge duration, or energy level can be flexibly configured to meet the parameter requirements of different converter valve non-periodic triggering tests. Each parallel discharge unit can include an independent discharge capacitor, discharge resistor, and trigger switch. Multiple discharge units can achieve equalization and synchronization of the discharge process through equalizing resistors or synchronous trigger control circuits, avoiding voltage imbalance or current concentration caused by parameter deviations. Furthermore, the parallel discharge circuit can be configured as an optional modular structure, and the discharge current can be finely graded and adjusted by adjusting the number of modules or the conduction state of the control switch. This application not only flexibly adapts to the test requirements of different voltage and energy levels but also significantly improves the scalability and repeatability of the test circuit. In different test scenarios, users can parameterize the capacitor capacity, the number of parallel branches, and the triggering method according to the test requirements to achieve precise current simulation and energy release control. Whether it is adding a disconnecting switch to the existing single discharge circuit structure or achieving controllable current output through capacity expansion and parallel connection, both fall within the protection scope of this application.

[0051] In some embodiments, the non-periodic triggering test circuit of this application is not only applicable to the testing scenarios of hybrid controllable commutator converters, but can also be extended to the non-periodic triggering test of conventional converter valves by controlling the switching states of each module in the circuit. Specifically, by controlling the switching states of the current establishment module and the second simulation module (e.g., not activating the charging and discharging units in the current establishment module and the second simulation module), different operating modes can be flexibly switched. When only the first simulation module is activated, the circuit can be equivalent to the non-periodic triggering test structure of a conventional converter valve; when the saturated reactor does not establish a preset current at the non-periodic triggering moment, only the first simulation module and the second simulation module can be controlled, and both modules can be put into operation simultaneously, satisfying the non-periodic triggering test structure under different operating parameters of the hybrid converter valve. This method realizes compatible testing of different converter valve topologies and different parameter settings on the same test platform, significantly improving the reusability and adaptability of the test equipment. Therefore, the test circuit of this application has a highly modular and versatile structure, and can realize non-periodic triggering tests on various converter valve topologies (including conventional LCC converter valves and hybrid converter valves) through control logic switching, which not only meets diverse experimental needs, but also reduces the cost of repeated equipment construction.

[0052] According to another aspect of the embodiments of this application, a control method for the equivalent circuit of a controllable commutator is proposed, for controlling the equivalent circuit of the controllable commutator, such as... Figure 6 As shown, the control methods include:

[0053] Step S1: The first charging unit of the first analog module of the control equivalent circuit is turned on so that the first charging unit charges the first discharging unit of the first analog module.

[0054] Specifically, the first charging unit consists of a first charging device, a first charging resistor, and a first switch. By controlling the first switch, the high voltage generated by the first charging device can be applied to the first energy-replenishing capacitor to complete the charging process. The opening control of the second charging unit ensures that the second energy-replenishing capacitor of the second discharge unit can be charged to a specific voltage to simulate the current leakage process of the device's surge arrester under non-periodic triggering conditions.

[0055] Step S2: The second charging unit of the second analog module of the control equivalent circuit is turned on so that the second charging unit charges the second discharging unit of the second analog module.

[0056] Specifically, the second charging unit consists of a second charging device, a fourth switch, and a second charging resistor. By controlling the fourth switch, the high voltage generated by the second charging device can be applied to the second charging capacitor to complete the charging process. The specific order of the above charging process is not limited.

[0057] Step S3: Control the first discharge unit and the second discharge unit to be turned on simultaneously, so that the first discharge unit discharges to the power component through the saturated reactor of the equivalent circuit to simulate the leakage current of the surge arrester connected in parallel across a single converter valve in the controllable commutation converter, and the second discharge unit discharges to the power component of the second simulation module to simulate the leakage current of the surge arrester connected in parallel across the semiconductor device in the controllable commutation converter.

[0058] Specifically, the first discharge unit consists of a first energy-replenishing capacitor and a second switch. By controlling the opening of the second switch, the energy stored in the first energy-replenishing capacitor is released to the power component through the saturated reactor, simulating the discharge process of the valve arrester. The opening control of the second discharge unit realizes the simulation of the discharge process of the device arrester. Specifically, the second discharge unit consists of a second energy-replenishing capacitor, a third switch, and a second discharge resistor. By controlling the opening of the third switch, the energy stored in the second energy-replenishing capacitor is directly released to the semiconductor device through the second discharge resistor, simulating the discharge process of the device arrester. The discharge processes of the device arrester and the valve arrester occur simultaneously, simulating the non-periodic triggering discharge condition. This coordinated control enables the test results to truly reflect the process of current transfer simultaneously in the valve arrester and the device arrester when the hybrid controllable commutation converter is subjected to non-periodic triggering.

[0059] By controlling the equivalent circuit using the above control method, when the power component of the second simulation module is not triggered, the first charging unit of the first simulation module charges the first discharging unit of the first simulation module. After charging is completed, when the power component is turned on, the first discharging unit of the first simulation module discharges current to the power component, simulating the discharge of a valve-type surge arrester. The second simulation module includes a second charging unit and a second discharging unit connected in parallel with the power component, which can independently control the charging and discharging of the device-level surge arrester, providing accurate simulation of the device-level surge arrester. This allows the discharge process of the device-level surge arrester to be synchronized with and independent of the process of the valve-type surge arrester, improving the overall controllability and accuracy of the test. Through two independent and collaborative modules, the discharge characteristics of the device-level surge arrester and the discharge characteristics of the valve-type surge arrester are simulated, ensuring that each module can accurately match the actual operating conditions, avoiding the test result deviation caused by the mutual influence between modules in traditional test methods, effectively reproducing the actual stress conditions of the hybrid controllable commutation converter in the non-periodic triggering process, and significantly improving the fidelity and reliability of the test results.

[0060] Step S4: After completing the current transfer simulation in non-periodic triggering, if the discharge unit in the second simulation module has not been completely discharged, the discharge capacitor of the second simulation module can be directly discharged through the third discharge resistor by turning on the sixth switch of the current establishment module.

[0061] By using the voltage and current established by the saturated reactor, device-type surge arrester, and valve-type surge arrester under the non-periodic triggering condition of the converter valve, and the discharge rate during the discharge process, the calculation of various parameters in the experimental circuit can be completed (including but not limited to the saturation time of the saturated reactor, the value of the first energy-replenishing capacitor, the value of the second energy-replenishing capacitor, and the second discharge resistance). This enables accurate simulation of different current transfer rates, current amplitudes, current transfer times, and discharge energy distribution of valve-type surge arresters and device-level surge arresters in controllable commutation converters.

[0062] In some optional embodiments, the equivalent circuit further includes a current establishment module, which includes a third charging unit and a third discharging unit. The first terminal of the third discharging unit is electrically connected to the first terminal of the saturated reactor and the first terminal of the first discharging unit, respectively. The second terminal of the third discharging unit is electrically connected to the second terminal of the saturated reactor and the second terminal of the third charging unit, respectively. The first terminal of the third charging unit is electrically connected to the third discharging unit. The control method further includes:

[0063] The third charging unit is turned on so that it charges the third discharging unit. The charged third discharging unit is used to establish a preset current for the saturated reactor when it is turned on.

[0064] Specifically, the activation control of the third charging unit ensures that the third replenishing capacitor of the third discharging unit can be charged to a specific voltage to simulate the actual operating condition where the reactor has already established a preset current before the device is triggered. Specifically, the third charging unit consists of a third charging device, a fifth switch, and a third charging resistor. By controlling the fifth switch, the voltage generated by the third charging device can be applied to the third replenishing capacitor to complete the charging process. Each charging unit can be controlled independently, which can more accurately reproduce the residual voltage characteristics of the surge arrester and the current control characteristics of the reactor under actual operating conditions, significantly enhancing the simulation accuracy of the test circuit.

[0065] Before the first discharge unit of the first analog module of the equivalent circuit and the second discharge unit of the second analog module of the equivalent circuit are turned on, the third discharge unit is turned on so that the third discharge unit discharges to the saturated reactor and establishes a preset current for the controllable commutator.

[0066] Specifically, the third discharge unit consists of a third discharge capacitor, a third discharge resistor, a sixth switch, and a first inductor. By controlling the opening of the sixth switch, the energy stored in the third discharge capacitor is released through the first inductor and the saturated reactor to establish a preset current.

[0067] Activating the aforementioned current establishment module ensures that a preset current is pre-set in the equivalent circuit before the power electronic device (semiconductor device in the power component in this application) is triggered. This can simulate the pre-charging state of the reactor of the controllable commutator in actual operating conditions, thereby improving the accuracy and realism of the test.

[0068] The technical features of the above embodiments can be combined in any way. For the sake of brevity, not all possible combinations of the technical features in the above 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.

[0069] It should also be noted that the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such process, method, article, or apparatus. Unless otherwise specified, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes that element.

[0070] The above are merely preferred embodiments of this application and are not intended to limit this application. Various modifications and variations can be made to this application by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this application should be included within the protection scope of this application.

Claims

1. An equivalent circuit of a controllable commutated converter, characterized in that, include: The system comprises a first analog module, a second analog module, a saturated reactor, and a power component, wherein the power component includes semiconductor devices. The first simulation module includes a first charging unit and a first discharging unit. A first end of the first charging unit is electrically connected to the first discharging unit, and a second end of the first charging unit is electrically connected to the second end of the first discharging unit. A first end of the first discharging unit is electrically connected to the first end of the saturated reactor. The first charging unit is used to charge the first discharging unit, and the first discharging unit is used to discharge to the semiconductor device through the saturated reactor to simulate the leakage current of a surge arrester connected in parallel across a single converter valve in a controllable commutation converter. The second simulation module includes a second charging unit and a second discharging unit. The power component is connected in parallel with the second charging unit and the second discharging unit. The first end of the power component is electrically connected to the first end of the second discharging unit and the second end of the saturated reactor, respectively. The second end of the power component is electrically connected to the second end of the first discharging unit, the second end of the second discharging unit, and the second end of the second charging unit, respectively. The first end of the second charging unit is electrically connected to the second discharging unit. The second charging unit is used to charge the second discharging unit, and the second discharging unit is used to discharge to the semiconductor device to simulate the leakage of the surge arrester connected in parallel across the semiconductor device in the converter valve.

2. The equivalent circuit according to claim 1, characterized in that, The first charging unit includes a first charging device and a first switch. The two ends of the first charging device are electrically connected to the first end of the first switch and the second end of the first discharging unit, respectively. The second end of the first switch is connected to the first end of the first discharging unit.

3. The equivalent circuit according to claim 1, characterized in that, The first discharge unit includes a first energy replenishing capacitor, a second switch, and a first discharge resistor. The first end of the first energy replenishing capacitor is connected to the first end of the first charging unit and the first end of the first discharge resistor, respectively. The second end of the first energy replenishing capacitor is electrically connected to the second end of the first charging unit, the second end of the power component, and the second end of the second discharge unit, respectively. The second end of the second switch is electrically connected to the first end of the saturated reactor.

4. The equivalent circuit according to claim 1, characterized in that, The second discharge unit includes a second energy replenishing capacitor, a third switch, and a second discharge resistor. The first end of the second discharge resistor is electrically connected to the first end of the power component and the second end of the saturated reactor, respectively. The second end of the second discharge resistor is connected to the first end of the third switch. The second end of the third switch is connected to the first end of the second energy replenishing capacitor and the first end of the second charging unit, respectively. The second end of the second energy replenishing capacitor is electrically connected to the second end of the power component and the second end of the second charging unit, respectively.

5. The equivalent circuit according to claim 1, characterized in that, The second charging unit includes a second charging device and a fourth switch, wherein the two ends of the fourth switch are electrically connected to the second discharging unit and the first end of the second charging device, respectively, and the second end of the second charging device is electrically connected to the second end of the second discharging unit and the second end of the power component, respectively.

6. The equivalent circuit according to claim 1, characterized in that, The equivalent circuit further includes a current establishment module, which includes a third charging unit and a third discharging unit. The first end of the third discharging unit is electrically connected to the first end of the saturated reactor and the first end of the first discharging unit, respectively. The second end of the third discharging unit is electrically connected to the second end of the saturated reactor and the second end of the third charging unit, respectively. The first end of the third charging unit is electrically connected to the third discharging unit.

7. The equivalent circuit according to claim 6, characterized in that, The third charging unit includes a third charging device and a fifth switch. The two ends of the fifth switch are respectively connected to the first end of the third charging device and the third discharging unit. The second end of the third charging device is electrically connected to the second end of the third discharging unit and the second end of the saturated reactor.

8. The equivalent circuit according to claim 6, characterized in that, The third discharge unit includes: a third energy-replenishing capacitor, a third discharge resistor, a sixth switch, a first inductor, a fourth discharge resistor, and a seventh switch. The third discharge resistor and the sixth switch are connected in series, and the branch formed by the series connection of the third discharge resistor and the sixth switch is connected in parallel with the third energy-replenishing capacitor. The first end of the first inductor is electrically connected to the first end of the saturated reactor and the first end of the first discharge unit, respectively. The second end of the first inductor is electrically connected to the first end of the fourth discharge resistor, respectively. The two ends of the seventh switch are electrically connected to the second end of the fourth discharge resistor and the first end of the third energy-replenishing capacitor, respectively.

9. A control method for the equivalent circuit of a controllable commutated converter, characterized in that, The control method for controlling the equivalent circuit of the controllable commutated converter according to any one of claims 1 to 8 includes: The first charging unit of the first analog module of the equivalent circuit is turned on so that the first charging unit charges the first discharging unit of the first analog module. The second charging unit of the second analog module of the equivalent circuit is turned on, so that the second charging unit charges the second discharging unit of the second analog module. The first discharge unit and the second discharge unit are controlled to be turned on simultaneously, so that the first discharge unit discharges to the semiconductor device through the saturated reactor of the equivalent circuit to simulate the leakage of the surge arrester connected in parallel across a single converter valve in the controllable commutation converter, and the second discharge unit discharges to the semiconductor device to simulate the leakage of the surge arrester connected in parallel across the semiconductor device in the controllable commutation converter.

10. The control method according to claim 9, characterized in that, The equivalent circuit further includes a current establishment module, which includes a third charging unit and a third discharging unit. The first terminal of the third discharging unit is electrically connected to both the first terminal of the saturated reactor and the first terminal of the first discharging unit. The second terminal of the third discharging unit is electrically connected to both the second terminal of the saturated reactor and the second terminal of the third charging unit. The first terminal of the third charging unit is electrically connected to the third discharging unit. The control method further includes: The third charging unit is controlled to turn on so that it charges the third discharging unit. After being charged, the third discharging unit is used to establish a preset current for the saturated reactor when it is turned on. Before the first discharge unit of the first analog module of the equivalent circuit and the second discharge unit of the second analog module of the equivalent circuit are turned on, the third discharge unit is turned on so that the third discharge unit discharges to the saturated reactor and establishes a preset current for the controllable commutator.

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