Starting method, system, medium and equipment of alternating current converter

Abstract

The invention provides a starting method and system of an alternating current converter, a medium and equipment, and the method comprises the steps: enabling a second frequency voltage generation module in each phase of circuit of the alternating current converter to be activated, maintaining the conduction of a cascade circuit composed of switching devices in the second frequency voltage generation module, and constructing a charging loop of a second voltage conversion module; carrying out uncontrolled charging and controllable charging on capacitors of sub-modules in the first voltage conversion module and the second voltage conversion module to set voltage by utilizing an alternating current power transmission system based on a charging loop; performing unlocking control on the alternating current converter, and starting the alternating current converter; by activating the second frequency voltage generation module, the charging loop of the second voltage conversion module can be autonomously constructed in the alternating current converter, and the defect that the second voltage conversion module has no charging loop due to the inherent characteristics of the topological circuit of the alternating current converter is overcome; and a guarantee is provided for normal starting of the alternating current converter by charging the capacitors of the sub-modules in the converter to the set voltage.

Description

Technical Field

[0001] The present invention relates to the technical field of power system transmission, and in particular to a method, system, medium and equipment for starting an alternating current converter. Background Art

[0002] As a new type of power transmission method, flexible low-frequency AC transmission uses power electronics technology to select a transmission frequency lower than the industrial frequency, greatly improving the transmission capacity of the line and reducing the electrical distance of the AC line. It has unique advantages in scenarios such as medium and long-distance offshore wind power collection and transmission. The AC converter is a key device in the flexible low-frequency AC transmission system. Among the AC converters, the traditional M3C (Modular Multilevel Matrix Converter) has a complex structure. Each bridge arm needs to bear the sum of the AC full-wave voltage peaks of the two AC frequencies on the input and output sides. There are many power modules with low utilization and large losses.

[0003] To solve the above problems, a sparse AC converter topology is proposed, which has a reduced topology complexity, fewer modules and fewer devices, can improve the technical and economic efficiency of the system, and reduce losses. Converter startup is a key issue that must be faced and urgently solved in the engineering application of flexible low-frequency AC transmission systems. Different converter topologies need to match corresponding startup strategies. Appropriate converter startup methods can help mitigate the impact of the system on itself and the power grid when it starts. Charging the capacitor of the converter valve module is the first step in the commissioning of the converter, and it is also the guarantee for the stable operation of the system control strategy.

[0004] However, due to the inherent characteristics of the topological circuit of the sparse AC converter, it is difficult to charge the capacitor of the valve module, so the conventional converter startup strategy is not applicable. Conventional converters are generally started at no-load, but when the sparse AC converter is started at no-load, one side of the IGBT series link in each phase of the circuit structure is suspended and in an open circuit state, and the circuit lacks a closed loop. The conventional startup strategy cannot charge the capacitor of the valve module, so the converter cannot be started. Summary of the invention

[0005] In order to overcome the above-mentioned deficiencies of the prior art, the present invention proposes a method for starting an AC converter, comprising:

[0006] By activating the second frequency voltage generating module in each phase circuit of the AC converter, the cascade circuit composed of the switching devices in the second frequency voltage generating module is kept turned on;

[0007] The charging circuit of the second voltage conversion module is constructed by the first frequency AC system of the AC power transmission system where the AC converter is located, the second voltage conversion module in each phase circuit and the second frequency voltage generation module connected by the cascade circuit;

[0008] By using the AC power transmission system, based on the charging circuit of the first voltage conversion module itself and the charging circuit of the second voltage conversion module in each phase circuit, the capacitors of the submodules in the first voltage conversion module and the second voltage conversion module are both uncontrolledly charged and controllably charged to a set voltage to complete the charging; the first voltage conversion module and the second voltage conversion module are respectively connected to the two ends of the second frequency voltage generating module;

[0009] The AC converter that has completed charging is unlocked and controlled to complete the startup of the AC converter.

[0010] Optionally, activating the second frequency voltage generating module in each phase circuit of the AC converter to keep the cascade circuit composed of switch devices in the second frequency voltage generating module turned on includes:

[0011] By triggering the input pulse of the second frequency voltage generating module in each phase circuit of the AC converter to be set to 1, the switch device in the second frequency voltage generating module is closed, so that the cascade circuit composed of the switch devices in the second frequency voltage generating module remains conductive.

[0012] Optionally, the using of the AC power transmission system, based on the charging circuit of the first voltage conversion module itself and the charging circuit of the second voltage conversion module in each phase circuit, performs uncontrolled charging and controllable charging to a set voltage on the capacitors of the submodules in the first voltage conversion module and the second voltage conversion module, including:

[0013] Locking the first voltage conversion module and the second voltage conversion module in each phase circuit, and using the AC power transmission system to uncontrollably charge the capacitors of the submodules in the first voltage conversion module and the second voltage conversion module to a preset voltage respectively;

[0014] The first voltage conversion module and the second voltage conversion module are unlocked alternately in sequence, and the capacitors of the submodules in the unlocked first voltage conversion module and the second voltage conversion module are controllably charged to a set voltage.

[0015] Optionally, the using the AC power transmission system to uncontrollably charge the capacitors of the submodules in the first voltage conversion module and the second voltage conversion module to preset voltages respectively includes:

[0016] Putting a starting resistor into the charging circuit of the first voltage conversion module and the second voltage conversion module;

[0017] Using the AC power transmission system, based on the charging circuit of the first voltage conversion module itself and the charging circuit of the second voltage conversion module into which the starting resistor is put, the capacitors of the submodules in the first voltage conversion module and the second voltage conversion module are charged to a first preset voltage respectively;

[0018] After the capacitors of the submodules in the first voltage conversion module and the second voltage conversion module are charged to the first preset voltage, based on the rotation charging instructions issued by the control and protection systems of the first voltage conversion module and the second voltage conversion module, several submodules in the first voltage conversion module and the second voltage conversion module are rotated to bypass at every set time interval, and the capacitors of the submodules in the first voltage conversion module and the second voltage conversion module that are not bypassed are charged to the second preset voltage by using the AC power transmission system;

[0019] After the capacitors of the submodules in the first voltage conversion module and the second voltage conversion module are charged to reach a second preset voltage, the startup resistor is bypassed;

[0020] Utilizing the AC power transmission system, based on the charging circuit of the first voltage conversion module itself and the charging circuit of the second voltage conversion module that bypasses the starting resistor, the capacitors of the submodules in the first voltage conversion module and the second voltage conversion module are charged to a final preset voltage.

[0021] Optionally, the specification of the starting resistor is determined based on the energy of the starting resistor and the overload current of each device in each phase circuit of the AC converter.

[0022] Optionally, the sequentially alternately unlocking the first voltage conversion module and the second voltage conversion module, and controllably charging the capacitors of the submodules in the unlocked first voltage conversion module and the second voltage conversion module to a set voltage, comprises:

[0023] Unlocking the second voltage conversion module and the corresponding controllable charging strategy, using the controllable charging strategy of the AC power transmission system based on the second voltage conversion module to charge the capacitor of the submodule in the unlocked second voltage conversion module to the set voltage of the second voltage conversion module; meanwhile, the first voltage conversion module is in a locked state;

[0024] Locking the second voltage conversion module and turning off the trigger mechanism of the second frequency voltage generation module;

[0025] Unlock the first voltage conversion module and the corresponding controllable charging strategy, and use the AC power transmission system to charge the capacitor of the submodule in the unlocked first voltage conversion module based on the controllable charging strategy of the first voltage conversion module to the set voltage of the first voltage conversion module.

[0026] Optionally, the set voltage of the first voltage conversion module is determined based on an average rated voltage of capacitors of submodules in the first voltage conversion module;

[0027] The set voltage of the second voltage conversion module is determined based on an average rated voltage of capacitors of submodules in the second voltage conversion module.

[0028] Optionally, the unlocking control of the AC converter that has completed charging to complete the startup of the AC converter includes:

[0029] unlocking the control strategy on both sides of the AC converter, and adjusting various startup indicators of the AC converter and the AC power transmission system that have completed charging to reach rated values ​​based on the control instructions determined by the control strategy, thereby completing the startup of the AC converter;

[0030] The startup index includes at least one of the following: an average capacitor voltage value of submodules in the first voltage conversion module, an average capacitor voltage value of submodules in the second voltage conversion module, and a voltage and power of the AC power transmission system.

[0031] Optionally, each phase circuit of the AC converter further includes: a first frequency voltage generating module;

[0032] The first end of the first voltage conversion module and the second voltage conversion module are connected to the first end of the first frequency voltage generation module; the second end of the second voltage conversion module is connected to the first end of the second frequency voltage generation module; the second end of the second frequency voltage generation module and the first voltage conversion module are connected to the second end of the first frequency voltage generation module;

[0033] The first voltage conversion module is used to generate a first AC voltage;

[0034] The second voltage conversion module is used to generate a difference between a second AC voltage and the first AC voltage;

[0035] The first frequency voltage generating module is used to reverse the polarity of the first AC voltage according to the first preset frequency and the first preset interval to generate a first frequency voltage with alternating positive and negative voltages;

[0036] The second frequency voltage generating module is used to reverse the polarity of the second AC voltage according to the second preset frequency and the second preset interval to generate a second frequency voltage with alternating positive and negative polarity.

[0037] Based on the same inventive concept, the present invention proposes a starting system for an AC converter, comprising:

[0038] A line conduction module, used to keep the cascade circuit composed of switch devices in the second frequency voltage generating module conducting by activating the second frequency voltage generating module in each phase circuit of the AC converter;

[0039] Constructing a charging circuit module, which is used to construct a charging circuit of the second voltage conversion module by using the first frequency AC system of the AC power transmission system where the AC converter is located, the second voltage conversion module in each phase circuit and the second frequency voltage generation module connected by the cascade circuit;

[0040] A charging module, used to use the AC power transmission system to perform uncontrolled and controllable charging of the capacitors of the submodules in the first voltage conversion module and the second voltage conversion module to a set voltage based on the charging circuit of the first voltage conversion module itself and the charging circuit of the second voltage conversion module in each phase circuit, so as to complete the charging; the first voltage conversion module and the second voltage conversion module are respectively connected to the two ends of the second frequency voltage generating module;

[0041] The unlocking and starting module performs unlocking control on the AC converter that has completed charging, thereby completing the starting of the AC converter.

[0042] Optionally, the line conduction module is specifically used to:

[0043] By triggering the input pulse of the second frequency voltage generating module in each phase circuit of the AC converter to be set to 1, the switch device in the second frequency voltage generating module is closed, so that the cascade circuit composed of the switch devices in the second frequency voltage generating module remains conductive.

[0044] Optionally, the charging module includes:

[0045] An uncontrolled charging unit, used to lock the first voltage conversion module and the second voltage conversion module in each phase circuit, and use the AC power transmission system to uncontrollably charge the capacitors of the submodules in the first voltage conversion module and the second voltage conversion module to a preset voltage respectively;

[0046] A controllable charging unit is used to alternately unlock the first voltage conversion module and the second voltage conversion module in sequence, and controllably charge the capacitors of the submodules in the unlocked first voltage conversion module and the second voltage conversion module to a set voltage.

[0047] Optionally, the uncontrolled charging unit is specifically used for:

[0048] Locking the first voltage conversion module and the second voltage conversion module in each phase circuit;

[0049] Putting a starting resistor into the charging circuit of the first voltage conversion module and the second voltage conversion module;

[0050] Using the AC power transmission system, based on the charging circuit of the first voltage conversion module itself and the charging circuit of the second voltage conversion module into which the starting resistor is put, the capacitors of the submodules in the first voltage conversion module and the second voltage conversion module are charged to a first preset voltage respectively;

[0051] After the capacitors of the submodules in the first voltage conversion module and the second voltage conversion module are charged to the first preset voltage, based on the rotation charging instructions issued by the control and protection systems of the first voltage conversion module and the second voltage conversion module, several submodules in the first voltage conversion module and the second voltage conversion module are rotated to bypass at every set time interval, and the capacitors of the submodules in the first voltage conversion module and the second voltage conversion module that are not bypassed are charged to the second preset voltage by using the AC power transmission system;

[0052] After the capacitors of the submodules in the first voltage conversion module and the second voltage conversion module are charged to reach a second preset voltage, the startup resistor is bypassed;

[0053] Utilizing the AC power transmission system, based on the charging circuit of the first voltage conversion module itself and the charging circuit of the second voltage conversion module that bypasses the starting resistor, the capacitors of the submodules in the first voltage conversion module and the second voltage conversion module are charged to a final preset voltage.

[0054] Optionally, the specification of the starting resistor is determined based on the energy of the starting resistor and the overload current of each device in each phase circuit of the AC converter.

[0055] Optionally, the controllable charging unit is specifically used for:

[0056] Unlocking the second voltage conversion module and the corresponding controllable charging strategy, using the controllable charging strategy of the AC power transmission system based on the second voltage conversion module to charge the capacitor of the submodule in the unlocked second voltage conversion module to the set voltage of the second voltage conversion module; meanwhile, the first voltage conversion module is in a locked state;

[0057] Locking the second voltage conversion module and turning off the trigger mechanism of the second frequency voltage generation module;

[0058] Unlock the first voltage conversion module and the corresponding controllable charging strategy, and use the AC power transmission system to charge the capacitor of the submodule in the unlocked first voltage conversion module based on the controllable charging strategy of the first voltage conversion module to the set voltage of the first voltage conversion module.

[0059] Optionally, in the controllable charging unit:

[0060] The set voltage of the first voltage conversion module is determined based on the average rated voltage of the capacitors of the submodules in the first voltage conversion module;

[0061] The set voltage of the second voltage conversion module is determined based on an average rated voltage of capacitors of submodules in the second voltage conversion module.

[0062] Optionally, the unlocking startup module is specifically used to:

[0063] unlocking the control strategy on both sides of the AC converter, and adjusting various startup indicators of the AC converter and the AC power transmission system that have completed charging to reach rated values ​​based on the control instructions determined by the control strategy, thereby completing the startup of the AC converter;

[0064] The startup index includes at least one of the following: an average capacitor voltage value of submodules in the first voltage conversion module, an average capacitor voltage value of submodules in the second voltage conversion module, and a voltage and power of the AC power transmission system.

[0065] Optionally, each phase circuit of the AC converter further includes: a first frequency voltage generating module;

[0066] The first end of the first voltage conversion module and the second voltage conversion module are connected to the first end of the first frequency voltage generation module; the second end of the second voltage conversion module is connected to the first end of the second frequency voltage generation module; the second end of the second frequency voltage generation module and the first voltage conversion module are connected to the second end of the first frequency voltage generation module;

[0067] The first voltage conversion module is used to generate a first AC voltage;

[0068] The second voltage conversion module is used to generate a difference between a second AC voltage and the first AC voltage;

[0069] The first frequency voltage generating module is used to reverse the polarity of the first AC voltage according to the first preset frequency and the first preset interval to generate a first frequency voltage with alternating positive and negative voltages;

[0070] The second frequency voltage generating module is used to reverse the polarity of the second AC voltage according to the second preset frequency and the second preset interval to generate a second frequency voltage with alternating positive and negative polarity.

[0071] In another aspect, the present application further provides an electronic device, comprising: at least one processor and a memory; the memory and the processor are connected via a bus;

[0072] The memory is used to store one or more programs;

[0073] When the one or more programs are executed by the at least one processor, the method for starting an AC switch as described above is implemented.

[0074] On the other hand, the present application further provides a computer-readable storage medium having an execution program stored thereon, and when the execution program is executed, the method for starting an alternating current switch as described above is implemented.

[0075] Compared with the closest prior art, the present invention has the following beneficial effects:

[0076] The present invention provides a method, system, medium and device for starting an AC converter, comprising: by activating a second frequency voltage generating module in each phase circuit of the AC converter, keeping the cascade circuit composed of switch devices in the second frequency voltage generating module turned on; constructing a charging circuit of the second voltage conversion module by using the first frequency AC system of the AC power transmission system where the AC converter is located, the second voltage conversion module in each phase circuit and the second frequency voltage generating module whose cascade circuit is turned on; using the AC power transmission system, based on the charging circuit of the first voltage conversion module itself in each phase circuit and the charging circuit of the second voltage conversion module The circuit is used to perform uncontrolled charging and controllable charging of the capacitors of the submodules in the first voltage conversion module and the second voltage conversion module to the set voltage in sequence to complete the charging; the AC converter that has completed the charging is unlocked and controlled to complete the startup of the AC converter; in the present application, by activating the second frequency voltage generation module, the charging circuit of the second voltage conversion module can be autonomously constructed in the AC converter, thereby overcoming the defect that the second voltage conversion module has no charging circuit due to the inherent characteristics of the AC converter topology circuit; after the charging circuit is constructed, the capacitors of the submodules in the converter are charged to the set voltage to provide a guarantee for the normal startup of the converter. BRIEF DESCRIPTION OF THE DRAWINGS

[0077] Figure 1 A schematic diagram of the topological structure of one phase of the AC converter provided by the present invention Figure 1 ;

[0078] Figure 2A schematic diagram of a method for starting an AC converter provided by the present invention Figure 1 ;

[0079] Figure 3 A schematic diagram of the topological structure of one phase of the AC converter provided by the present invention Figure 2 ;

[0080] Figure 4 A schematic diagram of the structure of the AC power transmission system provided by the present invention;

[0081] Figure 5 A schematic diagram of a method for starting an AC converter provided by the present invention Figure 2 ;

[0082] Figure 6 A schematic diagram of the process of charging and unlocking during the startup process of the AC converter provided by the present invention;

[0083] Figure 7 A schematic diagram of the structure of a starting system for an AC converter provided by the present invention;

[0084] Figure 8 The present invention provides a schematic structural diagram of an electronic device. DETAILED DESCRIPTION

[0085] The inherent characteristics of the AC converter topology circuit above lead to the defect that the valve module capacitor is difficult to charge, which is explained in combination with the topological structure of the AC converter (this embodiment is explained for the sparse AC converter), as shown in FIG. Figure 1 As shown, in each phase circuit of the AC converter, link ① and link ② are submodule cascade links, and link ③ and link ④ are IGBT (Insulated Gate Bipolar Transistor) cascade links; one side of the topological link ① of the AC converter is connected to the industrial frequency power supply, and one side of link ④ is suspended. Since the converter is started at no-load, that is, one side of link ④ is not connected to the load and is in an open circuit state, a closed loop cannot be formed, and conventional converter starting strategies are not applicable. In order to overcome the defect that the inherent characteristics of the AC converter topological circuit lead to difficulty in charging the valve module capacitor, the present invention provides a starting method and system for an AC converter, which is applied to the occasion of realizing the starting of the AC converter.

[0086] The specific implementation modes of the present invention are further described in detail below with reference to the accompanying drawings.

[0087] Embodiment 1:

[0088] The present invention provides a method for starting an AC converter, such as Figure 2 As shown, including:

[0089] S1, by activating the second frequency voltage generating module in each phase circuit of the AC converter, keeping the cascade circuit composed of the switching devices in the second frequency voltage generating module turned on;

[0090] S2, constructing a charging circuit of the second voltage conversion module by using the first frequency AC system of the AC power transmission system where the AC converter is located, the second voltage conversion module in each phase circuit and the second frequency voltage generating module connected by the cascade circuit;

[0091] S3, using the AC power transmission system, based on the charging circuit of the first voltage conversion module itself and the charging circuit of the second voltage conversion module in each phase circuit, the capacitors of the submodules in the first voltage conversion module and the second voltage conversion module are both uncontrolledly charged and controllably charged to a set voltage to complete the charging; the first voltage conversion module and the second voltage conversion module are respectively connected to the two ends of the second frequency voltage generating module;

[0092] S4. Unlocking and controlling the AC converter that has completed charging to start the AC converter.

[0093] The specific topological structure of each phase circuit of the AC converter in this embodiment is as follows: Figure 3 As shown (optionally, the AC converter provided by the present invention may be a multi-level converter), combined with Figure 1 To explain in detail, the topology of each phase circuit of the AC converter includes 4 links:

[0094] Link ①( Figure 3 The HBSM cascade part includes: a plurality of first voltage conversion submodules connected in cascade. In this embodiment, the first voltage conversion submodule is a half-bridge submodule (HBSM), but it can also be a full-bridge submodule (FBSM) or other voltage conversion submodules. The link ① of each phase circuit is recorded as the first voltage conversion module;

[0095] Link ②( Figure 3 The FBSM cascade part) includes: a plurality of second voltage conversion submodules connected in cascade. In this embodiment, the second voltage conversion submodule is a full-bridge submodule, but it can also be other voltage conversion submodules. The link ② of each phase circuit is recorded as the second voltage conversion module;

[0096] Link ③( Figure 3 The leftmost part of the controllable device cascade is composed of controllable switch devices connected in cascade, and the number of cascades is determined according to demand. Since link ③ is used to generate the first frequency voltage alternating between positive and negative, link ③ of each phase circuit is recorded as the first frequency voltage generation module;

[0097] Link ④( Figure 3 The rightmost controllable device cascade part is composed of controllable switch devices connected in cascade, and the number of cascades is determined according to demand. Since link ④ is used to generate a second frequency voltage with alternating positive and negative frequencies, link ④ of each phase circuit is recorded as a second frequency voltage generation module.

[0098] like Figure 1 and Figure 3 As shown, the first end of the first voltage conversion module and the second voltage conversion module are connected to the first end of the first frequency voltage generation module; the second end of the second voltage conversion module is connected to the first end of the second frequency voltage generation module; the second end of the second frequency voltage generation module and the first voltage conversion module are connected to the second end of the first frequency voltage generation module, and the second end of the first voltage conversion module is connected to the second end of the second frequency voltage generation module;

[0099] Wherein, the first voltage conversion module is used to generate a first AC voltage U1, and the first AC voltage is a half-wave voltage;

[0100] The second voltage conversion module is used to generate a difference between a second AC voltage U2 and the first AC voltage U1, and the second AC voltage may be a voltage with a specific amplitude and frequency;

[0101] The first frequency voltage generating module is used to reverse the polarity of the first AC voltage according to the first preset frequency and the first preset interval to generate a first frequency voltage with alternating positive and negative frequencies, and the first frequency voltage may be an industrial frequency voltage;

[0102] The second frequency voltage generating module is used to reverse the polarity of the second AC voltage according to the second preset frequency and the second preset interval to generate a second frequency voltage with alternating positive and negative polarity. The second frequency voltage can be a low frequency voltage.

[0103] The AC converter uses the idea of ​​half-cycle voltage frequency conversion and three bridge arms (each phase in the AC converter topology is independent and each phase is considered to be a bridge arm. Because the frequencies on both sides are different, the voltage superimposed by different frequencies on both sides is output by link ②. The control target of this topology is the voltage and current amplitude and frequency of the different frequency systems on both sides) to achieve AC-AC frequency conversion, reduce the complexity of the converter topology, and greatly reduce the number of modules and devices used.

[0104] like Figure 4 As shown, it is an AC power transmission system for charging the submodule of the AC converter in the present invention, and the AC power transmission system includes a first frequency AC system, a starting resistor R and a switch ( Figure 4The circuit breaker QF1 in the circuit breaker is used to bypass the starting resistor), the AC converter (AC / AC converter, AC=Alternating Current represents alternating current), the second frequency power transmission line and the second frequency AC system;

[0105] Optionally, the first frequency AC system is a power grid or a power supply;

[0106] Optionally, the second frequency AC system is a power grid, a power source or a load.

[0107] In this embodiment, the first frequency AC system is a power source, and the second frequency system is a load.

[0108] In this embodiment, the first frequency voltage is an industrial frequency voltage, and the second frequency voltage is a low frequency voltage. Figure 2 as well as Figure 5 The specific implementation process in the above-mentioned AC converter startup process is described.

[0109] In step S1, the second frequency voltage generating module (link ④) in each phase circuit of the AC converter is activated to keep the cascade circuit composed of the switching devices in the second frequency voltage generating module turned on.

[0110] Specifically, by triggering the input pulse of the second frequency voltage generating module in each phase circuit of the AC converter to be set to 1, the switch device in the second frequency voltage generating module is closed, so that the cascade circuit composed of the switch devices in the second frequency voltage generating module remains conductive.

[0111] In step S2, by always triggering the input pulse of link ④ to be set to 1, the charging circuit of the second voltage conversion module is constructed by the first frequency AC system of the AC power transmission system where the AC converter is located, the second voltage conversion module (link ②) in each phase circuit and the second frequency voltage generation module.

[0112] That is, by activating the second frequency voltage generating module, the charging circuit of the second voltage conversion module can be autonomously constructed in the AC converter, thereby overcoming the defect that the second voltage conversion module has no charging circuit due to the inherent characteristics of the AC converter topology circuit.

[0113] The startup process of the AC converter is divided into three processes: uncontrolled charging, controllable charging, and unlocking control. For example, in the above step S3, using the AC power transmission system where the AC converter is located, based on the charging circuit of the first voltage conversion module itself and the charging circuit of the second voltage conversion module, the capacitors of the sub-modules in the first voltage conversion module and the second voltage conversion module are both uncontrolled charged and controllably charged to the set voltage to complete the charging.

[0114] S31, locking the first voltage conversion module (link ①) and the second voltage conversion module (link ②) in each phase circuit, and entering the initial startup state of the AC converter; using the AC power transmission system where the AC converter is located, uncontrolled charging the capacitors of the submodules in the first voltage conversion module and the second voltage conversion module to a preset voltage, specifically:

[0115] S311. After determining that the trigger input pulse of the second frequency generating module is set to 1, a starting resistor is inserted into the charging circuit of the first voltage conversion module and the second voltage conversion module; the specification of the inserted starting resistor is determined based on the energy of the starting resistor and the overload current of each device in each phase circuit of the AC converter, in order to avoid damage to the device caused by excessive starting current.

[0116] S312, entering the first stage of uncontrolled charging: using the AC power transmission system, based on the charging circuit of the first voltage conversion module itself and the charging circuit of the second voltage conversion module with the starting resistor, respectively charging the capacitors of the submodules in the first voltage conversion module and the second voltage conversion module to a first preset voltage, that is, judging whether the average capacitor voltage value of the submodules in step ① and step ② reaches the first preset voltage U Cmax1 , and maintain stability;

[0117] S313, after the capacitor charging of the submodules in the first voltage conversion module and the second voltage conversion module stably reaches the first preset voltage, the first stage of uncontrolled charging ends and enters the second stage of uncontrolled charging: based on the rotation charging instructions (controllable charging instructions of the valve control module) issued by the control and protection systems of the first voltage conversion module and the second voltage conversion module, at each set time interval, several submodules in the first voltage conversion module and the second voltage conversion module are bypassed in rotation (that is, the bridge arms of link ① and link ② bypass n submodules every time t until each bridge arm keeps M submodules locked, and the remaining NM submodules are in a bypass state, n<M<N, N is the total number of submodules in a single bridge arm / link), and the capacitors of the submodules that are not bypassed in the first voltage conversion module and the second voltage conversion module are charged to the second preset voltage U by using the AC power transmission system. Cmax2 ;

[0118] By bypassing several submodules at set intervals to charge them in rotation, the impact on the converter itself and the power grid during startup can be mitigated.

[0119] After the capacitances of the submodules in the first voltage conversion module and the second voltage conversion module both reach a second preset voltage, the startup resistor is bypassed;

[0120] By using the AC power transmission system, based on the charging circuit of the first voltage conversion module itself and the charging circuit of the second voltage conversion module which bypass the starting resistor, the capacitors of the submodules in the first voltage conversion module and the second voltage conversion module are charged to a final preset voltage U Cmax3 , and maintain stability, the charging process is completed without control.

[0121] S32, sequentially and alternately unlocking the first voltage conversion module and the second voltage conversion module, and controllably charging the capacitors of the submodules in the unlocked first voltage conversion module and the second voltage conversion module to a set voltage, specifically:

[0122] S321, the first stage of controllable charging: unlocking the second voltage conversion module and the corresponding controllable charging strategy, using the controllable charging strategy of the AC power transmission system based on the second voltage conversion module to charge the capacitor of the submodule in the unlocked second voltage conversion module to the set voltage of the second voltage conversion module; meanwhile, the first voltage conversion module is in a locked state;

[0123] That is, the control quantity of the controllable charging strategy of link ② is the average capacitance voltage of the capacitor of the neutron module of link ②;

[0124] The set voltage of the second voltage conversion module is determined based on the average rated voltage of the capacitors of the submodules in the second voltage conversion module. In this embodiment, the set value 1 of the set voltage of the second voltage conversion module is the average rated voltage of the capacitors of the submodules in the second voltage conversion module.

[0125] The average capacitor voltage value of the submodule in the judgment link ② reaches the set value 1 and remains stable, completing the first stage of controllable charging.

[0126] S322, the first stage of controllable charging ends, the second voltage conversion module is locked, and the trigger mechanism of the second frequency voltage generation module is turned off, that is, the instruction of setting the trigger pulse to 1 in step ④ is released;

[0127] S323, controllable charging second stage: unlocking the first voltage conversion module and the corresponding controllable charging strategy, and using the controllable charging strategy of the first voltage conversion module based on the AC power transmission system to charge the capacitor of the submodule in the unlocked first voltage conversion module to the set voltage of the first voltage conversion module;

[0128] That is, the control quantity of the controllable charging strategy of link ① is the average capacitance voltage of the capacitors of the neutron modules in link ①;

[0129] The set voltage of the first voltage conversion module is determined based on the average rated voltage of the capacitors of the submodules in the first voltage conversion module. In this embodiment, the set value 2 of the set voltage of the first voltage conversion module is the average rated voltage of the capacitors of the submodules in the first voltage conversion module.

[0130] The average capacitor voltage value of the submodule in the judgment link ① reaches the set value 1 and remains stable, completing the second stage of controllable charging.

[0131] The order of the first stage of controllable charging and the second stage of controllable charging can be interchanged.

[0132] The unlocking and charging strategy is generally that the system operator sends an unlocking command to the control and protection system, and issues the command by observing the capacitor voltage charging status, or by obtaining the module voltage value to determine whether it reaches the preset value.

[0133] In step S4, the AC converter that has completed charging is unlocked and started.

[0134] Specifically, the control strategies on both sides of the AC converter are unlocked, the control targets on one side of the converter are the DC voltage and the reactive power / AC voltage of the AC system (first frequency system) on this side; the control target on the other side is the voltage or output power of the AC system (second frequency system) on this side; based on the control instructions determined by the control strategy (i.e., the control and protection system issues a normal DC voltage and AC voltage instruction), the various startup indicators of the AC converter and the AC power transmission system that have been charged are adjusted to reach the rated values, and the startup of the AC converter is completed;

[0135] The startup index includes: the average capacitor voltage value of the submodules in the first voltage conversion module, the average capacitor voltage value of the submodules in the second voltage conversion module, and the voltage and power of the AC power transmission system;

[0136] That is, it is determined that the average capacitor voltage value of the submodule in link ① and link ② and the voltage / power of the AC power transmission system reach the rated value, the unlocking control process is completed, and the AC converter is started.

[0137] In the present invention, by activating the second frequency voltage generating module, the charging circuit of the second voltage conversion module can be autonomously constructed in the AC converter, thereby overcoming the defect that the second voltage conversion module has no charging circuit due to the inherent characteristics of the AC converter topology circuit; after the charging circuit is constructed, the process of uncontrolled charging, controllable charging and unlocking control is performed in the AC converter, such as Figure 6 As shown, the controllable charging stage: based on the autonomously constructed charging circuit, the AC power transmission system ( Figure 6The AC system in the process) charges the capacitors of the submodules in links ① and ②, and the capacitor voltage of the submodules rises to a stable level; the uncontrolled charging stage: sequentially unlocks the relevant links (i.e., links ① and ②) and their charging strategies, and successively charges the capacitors of the submodules; the unlocking control stage: after charging is completed, the control strategies on both sides of the converter are unlocked, and the system indicators gradually reach the rated values, completing the startup of the AC converter.

[0138] In the present invention, after constructing the charging circuit, modules with different functions are charged in sequence, that is, the capacitors of the submodules in the AC converter are charged to the set voltage, so as to provide guarantee for the normal startup of the converter; and considering the problem that there are many control targets and cannot be decoupled when multiple links are controlled to charge at the same time, in the controllable charging stage, the capacitors of the submodules in different links are charged successively by sequentially unlocking the relevant links and the corresponding charging strategies, so as to solve the problem of complex control when multiple links are charged at the same time; at the same time, a suitable starting resistor is selected, and the submodules are equipped to charge in rotation, so as to reduce the impact on the converter valve itself and the power grid during startup.

[0139] Example 2

[0140] Based on the same inventive concept, the present invention also provides a starting system for an AC converter, such as Figure 7 As shown, including:

[0141] A line conduction module, used to keep the cascade circuit composed of switch devices in the second frequency voltage generating module conducting by activating the second frequency voltage generating module in each phase circuit of the AC converter;

[0142] Constructing a charging circuit module, which is used to construct a charging circuit of the second voltage conversion module by using the first frequency AC system of the AC power transmission system where the AC converter is located, the second voltage conversion module in each phase circuit and the second frequency voltage generation module connected by the cascade circuit;

[0143] A charging module, used to use the AC power transmission system to perform uncontrolled and controllable charging of the capacitors of the submodules in the first voltage conversion module and the second voltage conversion module to a set voltage based on the charging circuit of the first voltage conversion module itself and the charging circuit of the second voltage conversion module in each phase circuit, so as to complete the charging; the first voltage conversion module and the second voltage conversion module are respectively connected to the two ends of the second frequency voltage generating module;

[0144] The unlocking and starting module performs unlocking control on the AC converter that has completed charging, thereby completing the starting of the AC converter.

[0145] In a possible implementation, the line conduction module is specifically used to:

[0146] By triggering the input pulse of the second frequency voltage generating module in each phase circuit of the AC converter to be set to 1, the switch device in the second frequency voltage generating module is closed, so that the cascade circuit composed of the switch devices in the second frequency voltage generating module remains conductive.

[0147] In a possible implementation, the charging module includes:

[0148] An uncontrolled charging unit, used to lock the first voltage conversion module and the second voltage conversion module in each phase circuit, and use the AC power transmission system to uncontrollably charge the capacitors of the submodules in the first voltage conversion module and the second voltage conversion module to a preset voltage respectively;

[0149] A controllable charging unit is used to alternately unlock the first voltage conversion module and the second voltage conversion module in sequence, and controllably charge the capacitors of the submodules in the unlocked first voltage conversion module and the second voltage conversion module to a set voltage.

[0150] In a possible implementation, the above-mentioned uncontrolled charging unit is specifically used to:

[0151] Locking the first voltage conversion module and the second voltage conversion module in each phase circuit;

[0152] Putting a starting resistor into the charging circuit of the first voltage conversion module and the second voltage conversion module;

[0153] Using the AC power transmission system, based on the charging circuit of the first voltage conversion module itself and the charging circuit of the second voltage conversion module into which the starting resistor is put, the capacitors of the submodules in the first voltage conversion module and the second voltage conversion module are charged to a first preset voltage respectively;

[0154] After the capacitors of the submodules in the first voltage conversion module and the second voltage conversion module are charged to the first preset voltage, based on the rotation charging instructions issued by the control and protection systems of the first voltage conversion module and the second voltage conversion module, several submodules in the first voltage conversion module and the second voltage conversion module are rotated to bypass at every set time interval, and the capacitors of the submodules in the first voltage conversion module and the second voltage conversion module that are not bypassed are charged to the second preset voltage by using the AC power transmission system;

[0155] After the capacitors of the submodules in the first voltage conversion module and the second voltage conversion module are charged to reach a second preset voltage, the startup resistor is bypassed;

[0156] Utilizing the AC power transmission system, based on the charging circuit of the first voltage conversion module itself and the charging circuit of the second voltage conversion module that bypasses the starting resistor, the capacitors of the submodules in the first voltage conversion module and the second voltage conversion module are charged to a final preset voltage.

[0157] The specification of the starting resistor is determined based on the energy of the starting resistor and the overload current of each device in each phase circuit of the AC converter.

[0158] In a possible implementation, the controllable charging unit is specifically used to:

[0159] Unlocking the second voltage conversion module and the corresponding controllable charging strategy, using the controllable charging strategy of the AC power transmission system based on the second voltage conversion module to charge the capacitor of the submodule in the unlocked second voltage conversion module to the set voltage of the second voltage conversion module; meanwhile, the first voltage conversion module is in a locked state;

[0160] Locking the second voltage conversion module and turning off the trigger mechanism of the second frequency voltage generation module;

[0161] Unlock the first voltage conversion module and the corresponding controllable charging strategy, and use the AC power transmission system to charge the capacitor of the submodule in the unlocked first voltage conversion module based on the controllable charging strategy of the first voltage conversion module to the set voltage of the first voltage conversion module.

[0162] In a possible implementation, in the controllable charging unit:

[0163] The set voltage of the first voltage conversion module is determined based on the average rated voltage of the capacitors of the submodules in the first voltage conversion module;

[0164] The set voltage of the second voltage conversion module is determined based on an average rated voltage of capacitors of submodules in the second voltage conversion module.

[0165] In a possible implementation, the unlocking start module is specifically used to:

[0166] unlocking the control strategy on both sides of the AC converter, and adjusting various startup indicators of the AC converter and the AC power transmission system that have completed charging to reach rated values ​​based on the control instructions determined by the control strategy, thereby completing the startup of the AC converter;

[0167] The startup index includes at least one of the following: an average capacitor voltage value of submodules in the first voltage conversion module, an average capacitor voltage value of submodules in the second voltage conversion module, and a voltage and power of the AC power transmission system.

[0168] Each phase circuit of the above-mentioned AC converter also includes: a first frequency voltage generating module;

[0169] The first end of the first voltage conversion module and the second voltage conversion module are connected to the first end of the first frequency voltage generation module; the second end of the second voltage conversion module is connected to the first end of the second frequency voltage generation module; the second end of the second frequency voltage generation module and the first voltage conversion module are connected to the second end of the first frequency voltage generation module;

[0170] The first voltage conversion module is used to generate a first AC voltage;

[0171] The second voltage conversion module is used to generate a difference between a second AC voltage and the first AC voltage;

[0172] The first frequency voltage generating module is used to reverse the polarity of the first AC voltage according to the first preset frequency and the first preset interval to generate a first frequency voltage with alternating positive and negative voltages;

[0173] The second frequency voltage generating module is used to reverse the polarity of the second AC voltage according to the second preset frequency and the second preset interval to generate a second frequency voltage with alternating positive and negative polarity.

[0174] Example 3

[0175] like Figure 8 As shown, the present invention also provides an electronic device, which may be a computer device, a single-chip device, an intelligent mobile device, etc. The electronic device in this embodiment may include a processor, a memory, a transceiver component, etc. The memory, the processor, and the transceiver component are connected via a bus; the memory may be used to store an execution program, and an exemplary execution program may include instructions; the processor is used to execute the instructions stored in the memory. The memory may also be used to store data, which may be called and / or modified when the instructions are executed.

[0176] The processor may be a central processing unit (CPU), or other general-purpose processors, digital signal processors (DSP), application-specific integrated circuits (ASIC), field-programmable gate arrays (FPGA) or other programmable logic devices, discrete gates or transistor logic devices, discrete hardware components, etc. It is the computing core and control core of the terminal, which is suitable for implementing one or more instructions, specifically suitable for loading and executing one or more instructions in a storage medium to implement a corresponding method flow or corresponding function, so as to implement the steps of a method for starting an alternator in the above-mentioned embodiment.

[0177] Example 4

[0178] Based on the same inventive concept, the present invention also provides a readable storage medium, specifically an electronic device readable storage medium (Memory), which is a memory device in the electronic device for storing programs and data. It can be understood that the storage medium here can include both the built-in storage medium in the electronic device and the extended storage medium supported by the electronic device. The storage medium provides a storage space, which stores the operating system of the terminal. In addition, one or more instructions suitable for being loaded and executed by the processor are also stored in the storage space, and these instructions can be one or more execution programs (including program codes). It should be noted that the storage medium here can be a high-speed RAM memory or a non-volatile memory, such as at least one disk memory. The processor loads and executes one or more instructions stored in the storage medium, which can implement the steps of a method for starting an alternator in the above embodiment.

[0179] Those skilled in the art will appreciate that embodiments of the present invention may be provided as methods, systems, or computer program products. Therefore, the present invention may take the form of a complete hardware embodiment, a complete software embodiment, or an embodiment combining software and hardware. Moreover, the present invention may take the form of a computer program product implemented on one or more computer-usable storage media (including but not limited to disk storage, CD-ROM, optical storage, etc.) containing computer-usable program code.

[0180] The present invention is described with reference to flowcharts and / or block diagrams of methods, devices (systems), and computer program products according to embodiments of the present invention. It should be understood that each process and / or block in the flowchart and / or block diagram, as well as the combination of processes and / or blocks in the flowchart and / or block diagram, can be implemented by computer program instructions. These computer program instructions can be provided to a processor of a general-purpose computer, a special-purpose computer, an embedded processor, or other programmable data processing device to produce a machine, so that the instructions executed by the processor of the computer or other programmable data processing device generate instructions for implementing the processes in the flowchart and / or block diagram. Figure 1 A process or multiple processes and / or boxes Figure 1 A device that provides the functions specified in a block or multiple blocks.

[0181] These computer program instructions may also be stored in a computer-readable memory capable of directing a computer or other programmable data processing device to operate in a specific manner, so that the instructions stored in the computer-readable memory produce an article of manufacture comprising an instruction device, which implements the process Figure 1 A process or multiple processes and / or boxes Figure 1 A function specified in one or more boxes.

[0182] These computer program instructions can also be loaded onto a computer or other programmable data processing device so that a series of operating steps are executed on the computer or other programmable device to produce a computer-implemented process, thereby providing instructions for implementing the process. Figure 1 A process or multiple processes and / or boxes Figure 1 A step that specifies a function in one or more boxes.

[0183] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention rather than to limit its protection scope. Although the present invention has been described in detail with reference to the above embodiments, ordinary technicians in the relevant field should understand that after reading the present invention, those skilled in the art can still make various changes, modifications or equivalent substitutions to the specific implementation methods of the application, but these changes, modifications or equivalent substitutions are all within the protection scope of the claims to be approved.

Claims

1. A method for starting an AC converter, characterized in that: include: By activating the second frequency voltage generating module in each phase circuit of the AC converter, the cascade circuit composed of the switching devices in the second frequency voltage generating module is kept turned on; The charging circuit of the second voltage conversion module is constructed by the first frequency AC system of the AC power transmission system where the AC converter is located, the second voltage conversion module in each phase circuit and the second frequency voltage generation module connected by the cascade circuit; By using the AC power transmission system, based on the charging circuit of the first voltage conversion module itself and the charging circuit of the second voltage conversion module in each phase circuit, the capacitors of the submodules in the first voltage conversion module and the second voltage conversion module are both uncontrolledly charged and controllably charged to a set voltage to complete the charging; the first voltage conversion module and the second voltage conversion module are respectively connected to the two ends of the second frequency voltage generating module; The AC converter that has completed charging is unlocked and controlled to complete the startup of the AC converter.

2. The method according to claim 1, characterized in that The method of activating the second frequency voltage generating module in each phase circuit of the AC converter to keep the cascade circuit composed of switch devices in the second frequency voltage generating module turned on includes: By triggering the input pulse of the second frequency voltage generating module in each phase circuit of the AC converter to be set to 1, the switch device in the second frequency voltage generating module is closed, so that the cascade circuit composed of the switch devices in the second frequency voltage generating module remains conductive.

3. The method according to claim 1, characterized in that The method of utilizing the AC power transmission system to charge the capacitors of the submodules of the first voltage conversion module and the second voltage conversion module to a set voltage in an uncontrolled manner and in a controllable manner based on the charging circuit of the first voltage conversion module and the charging circuit of the second voltage conversion module in each phase circuit includes: Locking the first voltage conversion module and the second voltage conversion module in each phase circuit, and using the AC power transmission system to uncontrollably charge the capacitors of the submodules in the first voltage conversion module and the second voltage conversion module to a preset voltage respectively; The first voltage conversion module and the second voltage conversion module are unlocked alternately in sequence, and the capacitors of the submodules in the unlocked first voltage conversion module and the second voltage conversion module are controllably charged to a set voltage.

4. The method according to claim 3, characterized in that The method of using the AC power transmission system to uncontrollably charge the capacitors of the submodules in the first voltage conversion module and the second voltage conversion module to a preset voltage respectively includes: Putting a starting resistor into the charging circuit of the first voltage conversion module and the second voltage conversion module; Using the AC power transmission system, based on the charging circuit of the first voltage conversion module itself and the charging circuit of the second voltage conversion module into which the starting resistor is put, the capacitors of the submodules in the first voltage conversion module and the second voltage conversion module are charged to a first preset voltage respectively; After the capacitors of the submodules in the first voltage conversion module and the second voltage conversion module are charged to the first preset voltage, based on the rotation charging instructions issued by the control and protection systems of the first voltage conversion module and the second voltage conversion module, several submodules in the first voltage conversion module and the second voltage conversion module are rotated to bypass at every set time interval, and the capacitors of the submodules in the first voltage conversion module and the second voltage conversion module that are not bypassed are charged to the second preset voltage by using the AC power transmission system; After the capacitors of the submodules in the first voltage conversion module and the second voltage conversion module are charged to reach a second preset voltage, the startup resistor is bypassed; Utilizing the AC power transmission system, based on the charging circuit of the first voltage conversion module itself and the charging circuit of the second voltage conversion module that bypasses the starting resistor, the capacitors of the submodules in the first voltage conversion module and the second voltage conversion module are charged to a final preset voltage.

5. The method according to claim 4, characterized in that The specification of the starting resistor is determined based on the energy of the starting resistor and the overload current of each device in each phase circuit of the AC converter.

6. The method according to claim 3, characterized in that The sequentially alternately unlocking the first voltage conversion module and the second voltage conversion module, and controllably charging the capacitors of the submodules in the unlocked first voltage conversion module and the second voltage conversion module to a set voltage, comprises: Unlocking the second voltage conversion module and the corresponding controllable charging strategy, using the controllable charging strategy of the AC power transmission system based on the second voltage conversion module to charge the capacitor of the submodule in the unlocked second voltage conversion module to the set voltage of the second voltage conversion module; meanwhile, the first voltage conversion module is in a locked state; Locking the second voltage conversion module and turning off the trigger mechanism of the second frequency voltage generation module; Unlock the first voltage conversion module and the corresponding controllable charging strategy, and use the AC power transmission system to charge the capacitor of the submodule in the unlocked first voltage conversion module based on the controllable charging strategy of the first voltage conversion module to the set voltage of the first voltage conversion module.

7. The method according to claim 6, characterized in that The set voltage of the first voltage conversion module is determined based on the average rated voltage of the capacitors of the submodules in the first voltage conversion module; The set voltage of the second voltage conversion module is determined based on an average rated voltage of capacitors of submodules in the second voltage conversion module.

8. The method according to claim 1, characterized in that The unlocking control of the AC switch that has completed charging to start the AC switch includes: unlocking the control strategy on both sides of the AC converter, and adjusting various startup indicators of the AC converter and the AC power transmission system that have completed charging to reach rated values ​​based on the control instructions determined by the control strategy, thereby completing the startup of the AC converter; The startup index includes at least one of the following: an average capacitor voltage value of submodules in the first voltage conversion module, an average capacitor voltage value of submodules in the second voltage conversion module, and a voltage and power of the AC power transmission system.

9. The method according to any one of claims 1 to 8, characterized in that Each phase circuit of the AC converter also includes: a first frequency voltage generating module; The first end of the first voltage conversion module and the second voltage conversion module are connected to the first end of the first frequency voltage generation module; the second end of the second voltage conversion module is connected to the first end of the second frequency voltage generation module; the second end of the second frequency voltage generation module and the first voltage conversion module are connected to the second end of the first frequency voltage generation module; The first voltage conversion module is used to generate a first AC voltage; The second voltage conversion module is used to generate a difference between a second AC voltage and the first AC voltage; The first frequency voltage generating module is used to reverse the polarity of the first AC voltage according to the first preset frequency and the first preset interval to generate a first frequency voltage with alternating positive and negative voltages; The second frequency voltage generating module is used to reverse the polarity of the second AC voltage according to the second preset frequency and the second preset interval to generate a second frequency voltage with alternating positive and negative polarity.

10. A starting system for an AC converter, characterized in that: include: A line conduction module, used to keep the cascade circuit composed of switch devices in the second frequency voltage generating module conducting by activating the second frequency voltage generating module in each phase circuit of the AC converter; Constructing a charging circuit module, which is used to construct a charging circuit of the second voltage conversion module by using the first frequency AC system of the AC power transmission system where the AC converter is located, the second voltage conversion module in each phase circuit and the second frequency voltage generation module connected by the cascade circuit; A charging module, used to use the AC power transmission system to perform uncontrolled and controllable charging of the capacitors of the submodules in the first voltage conversion module and the second voltage conversion module to a set voltage based on the charging circuit of the first voltage conversion module itself and the charging circuit of the second voltage conversion module in each phase circuit, so as to complete the charging; the first voltage conversion module and the second voltage conversion module are respectively connected to the two ends of the second frequency voltage generating module; The unlocking and starting module performs unlocking control on the AC converter that has completed charging, thereby completing the starting of the AC converter.

11. The system according to claim 10, characterized in that The line conduction module is specifically used for: By triggering the input pulse of the second frequency voltage generating module in each phase circuit of the AC converter to be set to 1, the switch device in the second frequency voltage generating module is closed, so that the cascade circuit composed of the switch devices in the second frequency voltage generating module remains conductive.

12. The system according to claim 10, characterized in that The charging module comprises: An uncontrolled charging unit, used to lock the first voltage conversion module and the second voltage conversion module in each phase circuit, and use the AC power transmission system to uncontrollably charge the capacitors of the submodules in the first voltage conversion module and the second voltage conversion module to a preset voltage respectively; A controllable charging unit is used to alternately unlock the first voltage conversion module and the second voltage conversion module in sequence, and controllably charge the capacitors of the submodules in the unlocked first voltage conversion module and the second voltage conversion module to a set voltage.

13. The system of claim 12, wherein: The uncontrolled charging unit is specifically used for: Locking the first voltage conversion module and the second voltage conversion module in each phase circuit; Putting a starting resistor into the charging circuit of the first voltage conversion module and the second voltage conversion module; Using the AC power transmission system, based on the charging circuit of the first voltage conversion module itself and the charging circuit of the second voltage conversion module into which the starting resistor is put, the capacitors of the submodules in the first voltage conversion module and the second voltage conversion module are charged to a first preset voltage respectively; After the capacitors of the submodules in the first voltage conversion module and the second voltage conversion module are charged to the first preset voltage, based on the rotation charging instructions issued by the control and protection systems of the first voltage conversion module and the second voltage conversion module, several submodules in the first voltage conversion module and the second voltage conversion module are rotated to bypass at every set time interval, and the capacitors of the submodules in the first voltage conversion module and the second voltage conversion module that are not bypassed are charged to the second preset voltage by using the AC power transmission system; After the capacitors of the submodules in the first voltage conversion module and the second voltage conversion module are charged to reach a second preset voltage, the startup resistor is bypassed; Utilizing the AC power transmission system, based on the charging circuit of the first voltage conversion module itself and the charging circuit of the second voltage conversion module that bypasses the starting resistor, the capacitors of the submodules in the first voltage conversion module and the second voltage conversion module are charged to a final preset voltage.

14. The system of claim 13, wherein: The specification of the starting resistor is determined based on the energy of the starting resistor and the overload current of each device in each phase circuit of the AC converter.

15. The system of claim 12, wherein: The controllable charging unit is specifically used for: Unlocking the second voltage conversion module and the corresponding controllable charging strategy, using the controllable charging strategy of the AC power transmission system based on the second voltage conversion module to charge the capacitor of the submodule in the unlocked second voltage conversion module to the set voltage of the second voltage conversion module; meanwhile, the first voltage conversion module is in a locked state; Locking the second voltage conversion module and turning off the trigger mechanism of the second frequency voltage generation module; Unlock the first voltage conversion module and the corresponding controllable charging strategy, and use the AC power transmission system to charge the capacitor of the submodule in the unlocked first voltage conversion module based on the controllable charging strategy of the first voltage conversion module to the set voltage of the first voltage conversion module.

16. The system of claim 15, wherein: In the controllable charging unit: The set voltage of the first voltage conversion module is determined based on the average rated voltage of the capacitors of the submodules in the first voltage conversion module; The set voltage of the second voltage conversion module is determined based on an average rated voltage of capacitors of submodules in the second voltage conversion module.

17. The system of claim 10, wherein: The unlocking startup module is specifically used for: unlocking the control strategy on both sides of the AC converter, and adjusting various startup indicators of the AC converter and the AC power transmission system that have completed charging to reach rated values ​​based on the control instructions determined by the control strategy, thereby completing the startup of the AC converter; The startup index includes at least one of the following: an average capacitor voltage value of submodules in the first voltage conversion module, an average capacitor voltage value of submodules in the second voltage conversion module, and a voltage and power of the AC power transmission system.

18. The system according to any one of claims 10 to 17, characterized in that: Each phase circuit of the AC converter also includes: a first frequency voltage generating module; The first end of the first voltage conversion module and the second voltage conversion module are connected to the first end of the first frequency voltage generation module; the second end of the second voltage conversion module is connected to the first end of the second frequency voltage generation module; the second end of the second frequency voltage generation module and the first voltage conversion module are connected to the second end of the first frequency voltage generation module; The first voltage conversion module is used to generate a first AC voltage; The second voltage conversion module is used to generate a difference between a second AC voltage and the first AC voltage; The first frequency voltage generating module is used to reverse the polarity of the first AC voltage according to the first preset frequency and the first preset interval to generate a first frequency voltage with alternating positive and negative voltages; The second frequency voltage generating module is used to reverse the polarity of the second AC voltage according to the second preset frequency and the second preset interval to generate a second frequency voltage with alternating positive and negative polarity.

19. An electronic device, characterized in that: include: at least one processor and memory; The memory and the processor are connected via a bus; The memory is used to store one or more programs; When the one or more programs are executed by the at least one processor, a method for starting an AC switch according to any one of claims 1 to 9 is implemented.

20. A computing device readable storage medium, characterized in that: An execution program is stored thereon, and when the execution program is executed, a method for starting an AC switch as claimed in any one of claims 1 to 9 is implemented.

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