Flexible direct current converter valve energy self-balancing power module maintenance device, method and equipment

Abstract

The invention relates to the technical field of flexible direct-current converter valves, and discloses a flexible direct-current converter valve energy self-balancing power module overhauling device, method and equipment. By controlling the input of an energy release branch, the discharging function in two functions of an original voltage-sharing resistor is replaced by the energy release resistor, the voltage-sharing resistor only plays a voltage-sharing role, and the energy self-balancing power module overhauling device has the advantages that the discharging function in the two functions of the original voltage-sharing resistor is replaced by the energy release resistor; therefore, the purpose of reducing loss can be achieved through optimization, the discharge speed of a direct-current capacitor of the energy self-balancing power module is increased, the discharge time of the direct-current capacitor is shortened, the maintenance waiting time of the flexible direct-current converter valve is shortened, the maintenance efficiency of the converter valve is improved, reference significance is achieved for the operation and maintenance method of the flexible direct-current converter valve, and meanwhile, the method is suitable for popularization and application. A voltage-sharing resistor is connected in parallel with an equivalent resistor of the energy-taking power supply, and the loss of the energy self-balancing power module is further reduced by increasing the resistance value of the voltage-sharing resistor.

Description

Technical Field

[0001] The present invention relates to the technical field of flexible direct current (DC) converter valves, and in particular to a device, method and equipment for overhauling a flexible DC converter valve energy self-balancing power module. Background Art

[0002] When large-scale renewable energy is transmitted through the island of the flexible DC system, there is a risk of power surplus. If the DC system or the receiving AC power grid fails, a large amount of renewable energy surplus power will have no dissipation channel, and the surplus power will be directly injected into the converter station and stored in the MMC submodule capacitor of the converter station. The surplus power will directly threaten the operation safety of the converter valve, and may cause dangerous accidents such as equipment burning and project shutdown. Therefore, the converter valve needs to be shut down for maintenance to ensure the normal operation of the converter valve.

[0003] At present, the existing flexible direct current converter valve energy self-balancing power module has a built-in equalizing resistor, which is connected in parallel at both ends of the DC capacitor. Its function is to realize the equalization of the power module during the start-up process of the converter valve, and to discharge the DC capacitor after the converter valve is shut down. The equalizing resistor parameters directly affect the equalization effect and discharge time of the capacitor. Usually, its resistance value is often tens of kilo-ohms, and the discharge time constant is large. During steady-state operation, the equalizing resistor is in the input state, and it generates a certain amount of power consumption. The power consumption is inversely proportional to the resistance value of the equalizing resistor. Therefore, when the converter valve is shut down and needs to be repaired, it is necessary to wait for a long time for the DC capacitor voltage to drop below the safe voltage before starting the inspection or maintenance.

[0004] In summary, when the existing flexible DC converter valve energy self-balancing power module is overhauled, it still needs to be discharged through a relatively large resistance equalizing resistor, which makes it difficult to meet the purpose of rapid discharge of the DC capacitor during converter valve maintenance. At the same time, losses are generated on the equalizing resistor during steady-state operation, making it difficult to meet the requirements for power module loss reduction. Summary of the invention

[0005] The present invention provides a flexible direct current converter valve energy self-balancing power module maintenance device, method and equipment, which solves the technical problem of how to increase the discharge speed when the power module is being repaired and reduce the steady-state operation loss of the converter valve.

[0006] A first aspect of the present invention provides a flexible direct current converter valve energy self-balancing power module maintenance device, comprising an energy self-balancing power module, a main control unit and a valve control unit;

[0007] The main control unit is used to generate a power module control instruction according to the received converter valve maintenance information and circuit breaker disconnection information;

[0008] The valve control unit is used to receive the power module control instruction and send it to the energy self-balancing power module;

[0009] The energy self-balancing power module is used to respond to the power module control instruction and perform maintenance and regulation.

[0010] Optionally, the energy self-balancing power module includes a module control board, a full-bridge power conversion module and a half-bridge power conversion module;

[0011] The full-bridge power conversion module and the half-bridge power conversion module are both communicatively connected to the module control board;

[0012] The full-bridge power conversion module and the half-bridge power conversion module are both used to perform discharge operations according to the power module control instructions.

[0013] Optionally, the full-bridge power conversion module includes a full-bridge power unit, an energy dissipation branch, a full-bridge DC capacitor, a full-bridge energy extraction unit, a full-bridge voltage-equalizing resistor and a full-bridge diode;

[0014] The full-bridge diode is connected in reverse parallel to the full-bridge power unit, and the full-bridge diode is used to provide a freewheeling channel for the reverse current to prevent the full-bridge power unit from overvoltage breakdown;

[0015] The full-bridge power unit is connected in parallel with the full-bridge voltage-sharing resistor;

[0016] The full-bridge voltage-equalizing resistor is connected in parallel with the full-bridge DC capacitor;

[0017] The full-bridge voltage-equalizing resistor is connected in parallel with the full-bridge energy-taking unit, and is used to increase the resistance of the full-bridge voltage-equalizing resistor and reduce the steady-state loss of the energy self-balancing power module when the full-bridge energy-taking unit is in a working state;

[0018] The energy dissipation branch and the full-bridge energy extraction unit are both connected in parallel with the full-bridge DC capacitor.

[0019] Optionally, the full-bridge power unit includes a plurality of cascaded full-bridge IGBT devices.

[0020] Optionally, the half-bridge power conversion module includes a half-bridge power unit, an energy dissipation branch, a half-bridge DC capacitor, a half-bridge energy extraction unit, a half-bridge voltage balancing resistor and a half-bridge diode;

[0021] The half-bridge diode is connected in reverse parallel to the half-bridge power unit, and the half-bridge diode is used to provide a freewheeling channel for the reverse current to prevent the half-bridge power unit from overvoltage breakdown;

[0022] The half-bridge power unit is connected in parallel with the half-bridge voltage-sharing resistor;

[0023] The half-bridge voltage-sharing resistor is connected in parallel with the half-bridge DC capacitor;

[0024] The half-bridge voltage-equalizing resistor is connected in parallel with the half-bridge energy extraction unit, and is used to increase the resistance of the half-bridge voltage-equalizing resistor and reduce the steady-state loss of the energy self-balancing power module when the half-bridge energy extraction unit is in a working state;

[0025] The energy dissipation branch and the half-bridge energy extraction unit are both connected in parallel with the half-bridge DC capacitor.

[0026] Optionally, the half-bridge power unit includes a plurality of cascaded half-bridge IGBT devices.

[0027] Optionally, the energy dissipation branch includes an energy dissipation resistor and an energy dissipation switch;

[0028] The energy dissipation resistor is connected in series with the energy dissipation switch;

[0029] The energy dissipation switch is used to respond to the power module control instruction and control the input and output of the energy dissipation branch;

[0030] The energy dissipation resistor is used to consume the electric energy stored in the capacitor when the energy dissipation branch is in the on state.

[0031] A second aspect of the present invention provides a maintenance method applied to the maintenance device for the energy self-balancing power module of a flexible direct current converter valve, comprising:

[0032] Generate power module control instructions according to the received converter valve maintenance information and circuit breaker disconnection information;

[0033] Receive power module control instructions, respond to power module control instructions, and perform maintenance and regulation on the energy self-balancing power module.

[0034] Optionally, the step of performing maintenance and regulation on the energy self-balancing power module in response to the power module control instruction includes:

[0035] When the power module control instruction is the first preset instruction, the full-bridge power unit and the half-bridge power unit are controlled to exit, the energy discharge branch is controlled to be put into operation, and the energy self-balancing power module is discharged;

[0036] When the power module control instruction is the second preset instruction, the full-bridge power unit and the half-bridge power unit are controlled to exit, the energy discharge branch is controlled to exit, the resistance of the full-bridge equalizing resistor and the half-bridge equalizing resistor is increased, and the steady-state loss of the energy self-balancing power module is reduced.

[0037] A third aspect of the present invention provides an electronic device, comprising a memory and a processor, wherein the memory stores a computer program, and when the computer program is executed by the processor, the processor executes the steps of the maintenance method described in any one of the above items.

[0038] It can be seen from the above technical solutions that the present invention has the following advantages:

[0039] The present invention controls the input of the energy discharge branch, and replaces the discharge function of the two functions of the original equalizing resistor with the energy discharge resistor. The equalizing resistor only plays a role of equalizing, and then the purpose of reducing losses can be achieved through optimization, thereby improving the discharge speed of the DC capacitor of the energy self-balancing power module, shortening the DC capacitor discharge time, reducing the waiting time for the maintenance of the flexible direct current converter valve, and improving the maintenance efficiency of the converter valve. It has reference significance for the operation and maintenance method of the flexible direct current converter valve. At the same time, the equalizing resistor is connected in parallel with the equivalent resistance of the energy-taking power source, and the resistance value of the equalizing resistor is increased, so as to further reduce the loss of the energy self-balancing power module. BRIEF DESCRIPTION OF THE DRAWINGS

[0040] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative labor.

[0041] Figure 1 It is the connection topology diagram of the full-bridge power conversion module and the module control board;

[0042] Figure 2 is a schematic diagram of an equivalent circuit of a full-bridge power conversion module;

[0043] Figure 3 It is the connection topology diagram of the half-bridge power conversion module and the module control board;

[0044] Figure 4 is a schematic diagram of an equivalent circuit of a half-bridge power conversion module;

[0045] Figure 5 A discharge control logic diagram of a full-bridge power conversion module provided by the present invention;

[0046] Figure 6 A discharge control logic diagram of a half-bridge power conversion module provided by the present invention;

[0047] Figure 7 A schematic diagram of the control logic of the converter valve provided by the present invention;

[0048] Figure 8 A flowchart of the steps of a maintenance method for a flexible direct current converter valve energy self-balancing power module maintenance device according to an embodiment of the present invention;

[0049] Fig. 9 This is a structural block diagram of a computer device provided in Embodiment 4 of the present invention. DETAILED DESCRIPTION

[0050] The embodiments of the present invention provide a flexible direct current valve energy self-balancing power module maintenance device, method and equipment for solving the technical problem of how to increase the discharge speed and reduce the steady-state operation loss of the converter valve when the power module is under maintenance.

[0051] In order to make the purpose, features and advantages of the present invention more obvious and easy to understand, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the embodiments described below are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0052] The present invention provides a maintenance device for a flexible DC converter valve energy self-balancing power module, which reduces the operating loss of the flexible DC converter valve and improves the DC voltage discharge speed of the flexible DC converter valve power module, so as to solve the problem of slow DC capacitor discharge of the energy self-balancing power module when the converter valve is shut down for maintenance and reduce the steady-state operating loss of the converter valve.

[0053] The present invention provides a flexible direct current converter valve energy self-balancing power module maintenance device, comprising an energy self-balancing power module, a main control unit and a valve control unit;

[0054] A main control unit, used for generating a power module control instruction according to the received converter valve maintenance information and circuit breaker disconnection information;

[0055] A valve control unit, used for receiving a power module control instruction and sending it to an energy self-balancing power module;

[0056] The energy self-balancing power module is used to respond to the power module control instructions and perform maintenance and regulation.

[0057] It should be noted that the main control unit, as the control and protection device of the converter valve, is connected and communicated with the valve control unit through optical fiber, and is used to send various control instructions such as start-up, shutdown, and maintenance of the converter valve to the valve control unit. The valve control unit is used to receive the instructions sent by the main control unit and distribute them to the module control board of the energy self-balancing power module of the converter valve through optical fiber. The energy self-balancing power module is divided into a full-bridge power conversion module and a half-bridge power conversion module. As the core unit of the converter valve, it is cascaded to form a bridge arm power unit, which is used for power conversion on the AC side and the DC side. When power is cut off for maintenance, it responds to the power module control instructions issued by the valve control unit and performs maintenance and regulation.

[0058] It should be noted that the converter valve maintenance information refers to the maintenance information generated according to the state of the maintenance switch button. When the maintenance switch button is pressed to start, the converter valve maintenance information is 1. When the maintenance switch button is not pressed to start, the converter valve maintenance information is 0.

[0059] It is worth mentioning that the maintenance switch trigger is set to manual trigger. The maintenance switch button is only activated when the maintenance personnel need to enter the valve hall of the converter valve. This can reduce the discharge times of the DC capacitor, avoid unnecessary discharge process, and reduce the active power loss of the DC capacitor. At this time, the maintenance switch button of the main control unit is manually triggered to send a fast discharge signal. At the same time, when the main circuit breaker is also in the disconnected state, the first preset instruction generated is sent to the module control board of the power module through the valve control, and the energy discharge switch receives the trigger pulse and turns on.

[0060] The circuit breaker opening information refers to the opening information of the main circuit breaker installed between the converter valve and the power supply in the transmission system. When the main circuit breaker is in the off state, the circuit breaker opening information is 1, and when the main circuit breaker is in the closed state, the circuit breaker opening information is 0.

[0061] When the converter valve maintenance information is 1 and the circuit breaker disconnection information is 1, the power module control instruction is the first preset instruction, and the first preset instruction is specifically to control the full-bridge power unit and the half-bridge power unit to exit and control the energy discharge branch to be put into operation;

[0062] When the converter valve maintenance information is 1 and the circuit breaker opening information is 0, or when the converter valve maintenance information is 0 and the circuit breaker opening information is 1, or when the converter valve maintenance information is 0 and the circuit breaker opening information is 0, the power module control instruction is the second preset instruction, and the second preset instruction is specifically to control the exit of the full-bridge power unit and the half-bridge power unit, control the exit of the energy dissipation branch, and increase the resistance of the full-bridge equalizing resistor and the half-bridge equalizing resistor.

[0063] The present invention provides a maintenance device for a flexible direct current converter valve energy self-balancing power module, wherein the energy self-balancing power module comprises a module control board, a full-bridge power conversion module and a half-bridge power conversion module;

[0064] The full-bridge power conversion module and the half-bridge power conversion module are both communicatively connected to the module control board;

[0065] Both the full-bridge power conversion module and the half-bridge power conversion module are used to perform discharge operations according to power module control instructions.

[0066] It should be noted that the energy self-balancing power module includes a module control board, a full-bridge power conversion module and a half-bridge power conversion module; the full-bridge power conversion module and the half-bridge power conversion module are both communicated with the module control board, and the module control board is used to control the opening and closing of each unit component in the full-bridge power conversion module and the half-bridge power conversion module according to the power module control instructions; the full-bridge power conversion module and the half-bridge power conversion module are both used to perform discharge operations according to the power module control instructions.

[0067] See also Figure 1-Figure 2 The present invention provides a flexible DC converter valve energy self-balancing power module maintenance device, the full-bridge power conversion module includes a full-bridge power unit, an energy dissipation branch, a full-bridge DC capacitor, a full-bridge energy taking unit, a full-bridge voltage equalizing resistor and a full-bridge diode;

[0068] The full-bridge diode is reverse-connected in parallel with the full-bridge power unit. The full-bridge diode is used to provide a freewheeling channel for the reverse current to prevent the full-bridge power unit from overvoltage breakdown.

[0069] The full-bridge power unit is connected in parallel with the full-bridge voltage-equalizing resistor;

[0070] The full-bridge voltage-equalizing resistor is connected in parallel with the full-bridge DC capacitor;

[0071] The full-bridge voltage-equalizing resistor is connected in parallel with the full-bridge energy-taking unit, and is used to increase the resistance of the full-bridge voltage-equalizing resistor when the full-bridge energy-taking unit is in a working state, thereby reducing the steady-state loss of the energy self-balancing power module;

[0072] The energy dissipation branch and the full-bridge energy taking unit are both connected in parallel with the full-bridge DC capacitor.

[0073] The full-bridge power unit includes multiple cascaded full-bridge IGBT devices.

[0074] The energy dissipation branch includes an energy dissipation resistor and an energy dissipation switch;

[0075] The energy dissipation resistor and the energy dissipation switch are connected in series;

[0076] The energy-discharging switch is used to respond to the control command of the power module and control the input and output of the energy-discharging branch;

[0077] The energy dissipation resistor is used to consume the electric energy stored in the capacitor when the energy dissipation branch is in the on state.

[0078] Please note that Figure 1 , Figure 1 This is the connection topology diagram of the full-bridge power conversion module and the module control board. Figure 2 This is the equivalent circuit diagram of the full-bridge power conversion module.

[0079] The full-bridge power unit includes a plurality of cascaded full-bridge IGBT devices. In the present invention, the full-bridge IGBT devices are preferably 4, the first full-bridge IGBT device T1 and the second full-bridge IGBT device T2 are connected in series to form a first IGBT device branch, the third full-bridge IGBT device T3 and the fourth full-bridge IGBT device T4 are connected in series to form a second IGBT device branch, and the first IGBT device branch is connected in parallel with the second IGBT device branch. The full-bridge power conversion module is composed of a full-bridge power unit, an energy dissipation branch, a full-bridge DC capacitor C, a full-bridge energy extraction unit, a full-bridge voltage-equalizing resistor R1 and a full-bridge diode. The full-bridge DC capacitor C is a DC capacitor, the energy dissipation branch is connected in parallel with the full-bridge DC capacitor C, the energy dissipation branch is composed of an energy dissipation switch T5 and an energy dissipation resistor R2 in series, the full-bridge voltage-equalizing resistor R1 is connected in parallel at both ends of the full-bridge DC capacitor C, the full-bridge energy extraction unit is an energy extraction power supply, the full-bridge energy extraction unit is connected in parallel at both ends of the full-bridge DC capacitor C, and the energy extraction equivalent resistance of the full-bridge energy extraction unit is very large, usually hundreds of kΩ. When the full-bridge energy acquisition unit is turned off, its resistance is fixed, usually in the MΩ level; when the full-bridge energy acquisition unit is working, its equivalent resistance is not fixed, usually hundreds of kΩ.

[0080] In the embodiment of the present invention, when a fault causes the full-bridge power unit to lock out, the energy discharge switch T5 is locked and turned off; during steady-state operation, the energy discharge switch T5 is turned off and the energy discharge branch exits; during the transient period, when the DC capacitor voltage is greater than the energy discharge branch input setting value, the energy discharge switch is turned on and the energy discharge branch is input; when the DC capacitor voltage is less than the energy discharge branch exit setting value, the energy discharge switch is turned off and the energy discharge branch exits.

[0081] See also Figure 3-Figure 4 The present invention provides a flexible DC converter valve energy self-balancing power module maintenance device, wherein the half-bridge power conversion module includes a half-bridge power unit, an energy dissipation branch, a half-bridge DC capacitor, a half-bridge energy taking unit, a half-bridge voltage equalizing resistor and a half-bridge diode;

[0082] The half-bridge diode is connected in reverse parallel to the half-bridge power unit. The half-bridge diode is used to provide a freewheeling channel for the reverse current to prevent the half-bridge power unit from overvoltage breakdown.

[0083] The half-bridge power unit is connected in parallel with the half-bridge voltage-equalizing resistor;

[0084] The half-bridge voltage-equalizing resistor is connected in parallel with the half-bridge DC capacitor;

[0085] The half-bridge voltage-equalizing resistor is connected in parallel with the half-bridge energy-taking unit, and is used to increase the resistance of the half-bridge voltage-equalizing resistor when the half-bridge energy-taking unit is in a working state, thereby reducing the steady-state loss of the energy self-balancing power module;

[0086] The energy dissipation branch and the half-bridge energy taking unit are both connected in parallel with the half-bridge DC capacitor.

[0087] The half-bridge power unit includes a plurality of cascaded half-bridge IGBT devices.

[0088] The energy dissipation branch includes an energy dissipation resistor and an energy dissipation switch;

[0089] The energy dissipation resistor and the energy dissipation switch are connected in series;

[0090] The energy-discharging switch is used to respond to the control command of the power module and control the input and output of the energy-discharging branch;

[0091] The energy dissipation resistor is used to consume the electric energy stored in the capacitor when the energy dissipation branch is in the on state.

[0092] It should be noted that please refer to Figure 3 , Figure 3 This is the connection topology diagram between the half-bridge power conversion module and the module control board. Figure 4 This is a schematic diagram of the equivalent circuit of a half-bridge power conversion module.

[0093] The half-bridge power unit includes a plurality of cascaded half-bridge IGBT devices. In the present invention, the half-bridge IGBT devices are preferably 4, the first half-bridge IGBT device T1 and the second half-bridge IGBT device T2 are connected in series to form a first IGBT device branch, and the first IGBT device branch is connected in parallel with the energy dissipation branch. The half-bridge power conversion module is composed of a half-bridge power unit, an energy dissipation branch, a half-bridge DC capacitor C, a half-bridge energy extraction unit, a half-bridge voltage-equalizing resistor R1 and a half-bridge diode. The half-bridge DC capacitor C is a DC capacitor, the energy dissipation branch is connected in parallel with the half-bridge DC capacitor C, the energy dissipation branch is composed of an energy dissipation switch T5 and an energy dissipation resistor R2 in series, the half-bridge voltage-equalizing resistor R1 is connected in parallel at both ends of the half-bridge DC capacitor C, the half-bridge energy extraction unit is an energy extraction power supply, the half-bridge energy extraction unit is connected in parallel at both ends of the half-bridge DC capacitor C, and the energy extraction equivalent resistance of the half-bridge energy extraction unit is very large, usually hundreds of kΩ. When the half-bridge energy acquisition unit is turned off, its resistance is fixed, usually in the MΩ level; when the half-bridge energy acquisition unit is working, its equivalent resistance is not fixed, usually hundreds of kΩ.

[0094] In the embodiment of the present invention, when a fault causes the half-bridge power unit to lock out, the energy discharge switch T3 is locked and turned off; during steady-state operation, the energy discharge switch T3 is turned off and the energy discharge branch exits; during the transient period, when the DC capacitor voltage is greater than the energy discharge branch input setting value, the energy discharge switch is turned on and the energy discharge branch is input; when the DC capacitor voltage is less than the energy discharge branch exit setting value, the energy discharge switch is turned off and the energy discharge branch exits.

[0095] See also Figure 5-Figure 7 , Figure 5 A discharge control logic diagram of a full-bridge power conversion module provided by the present invention;

[0096] Figure 6A discharge control logic diagram of a half-bridge power conversion module provided by the present invention;

[0097] Figure 7 A schematic diagram of the control logic of the converter valve provided by the present invention.

[0098] When the flexible direct current converter valve fails or is abnormal, causing shutdown, the main control unit will first send the power module locking instructions FB5 and FB3 to the valve control unit through the optical fiber. At this time, FB5 and FB3 are both 0. The module control board receives the locking instructions FB5 and FB3, controls the full-bridge power units IGBT1, IGBT2, IGBT3, and IGBT4 in the energy self-balancing power module to turn off, and the associated energy dissipation switch IGBT5 is turned off, the energy dissipation branch exits, the half-bridge power units IGBT1 and IGBT2 are turned off, the energy dissipation switch IGBT3 is turned off, and the energy dissipation branch exits;

[0099] Before the energy source is turned off, the equalizing resistor R1 is connected in parallel with the equivalent resistor Re of the energy source and then in series with the DC capacitor voltage to form a discharge loop. Since R1 < Re, most of the discharge current flows through the equalizing resistor, and a small part flows through the equivalent resistance loop of the energy source.

[0100] When the converter valve maintenance information is 1 and the circuit breaker disconnection information is 1, the main control unit will first send the power module unlocking instructions FB5 and FB3 to the valve control unit through the optical fiber. At this time, FB5 and FB3 are both 1. The module control board receives the unlocking instructions FB5 and FB3, keeps the full-bridge power units IGBT1, IGBT2, IGBT3, and IGBT4 turned off, and the half-bridge power units IGBT1 and IGBT2 turned off, and controls the energy discharge branch to be put into operation, that is, the energy discharge switches IGBT5 and IGBT3 are closed. At this time, the energy discharge switch is turned on and the energy discharge branch is put into operation. Since the energy discharge resistance is much smaller than the voltage equalization resistance, the discharge current changes the flow path and is shunted through the energy discharge branch.

[0101] See also Figure 8 The present invention provides a maintenance method for a flexible direct current converter valve energy self-balancing power module maintenance device, comprising:

[0102] Step 101: Generate a power module control instruction according to the received converter valve maintenance information and circuit breaker disconnection information.

[0103] Step 102: Receive a power module control instruction, respond to the power module control instruction, and perform maintenance and regulation on the energy self-balancing power module.

[0104] Further, step 102 may include the following sub-steps:

[0105] S11, when the power module control instruction is the first preset instruction, the full-bridge power unit and the half-bridge power unit are controlled to exit, and the energy discharge branch is controlled to be put into operation to discharge the energy self-balancing power module.

[0106] S12. When the power module control instruction is the second preset instruction, the full-bridge power unit and the half-bridge power unit are controlled to exit, the energy discharge branch is controlled to exit, the resistance of the full-bridge equalizing resistor and the half-bridge equalizing resistor is increased, and the steady-state loss of the energy self-balancing power module is reduced.

[0107] In an embodiment of the present invention, when the flexible direct current converter valve fails or abnormally causes shutdown, the main control unit will first send a power module locking command to the valve control unit through the optical fiber. The module control board receives the locking command, controls the full-bridge power units IGBT1, IGBT2, IGBT3, and IGBT4 in the energy self-balancing power module to be turned off, and the associated energy dissipation switch IGBT5 is turned off, the energy dissipation branch exits, the half-bridge power units IGBT1 and IGBT2 are turned off, the energy dissipation switch IGBT3 is turned off, and the energy dissipation branch exits. When the power module control instruction is the first preset instruction, it means that the main circuit breaker is in the disconnected state. The main circuit breaker is in the disconnected state to ensure the safety of the maintenance work, and the maintenance switch button is manually triggered by the external maintenance personnel to control the full-bridge power unit and the half-bridge power unit to exit, that is, keep the full-bridge power units IGBT1, IGBT2, IGBT3, IGBT4 turned off, and the half-bridge power units IGBT1 and IGBT2 turned off, and control the energy discharge branch to be put into use, that is, the energy discharge switches IGBT5 and IGBT3 are closed, the discharge current is shunted through the energy discharge branch, the large current is quickly discharged through the energy discharge resistor, and the small current is discharged through the voltage equalizing resistor; with the participation of the energy discharge resistor, the DC capacitor voltage quickly drops to the safety voltage threshold, realizing the functional expansion of the energy discharge branch, in addition to meeting the surplus power dissipation during the transient fault, it also meets the function of manual rapid discharge of the DC capacitor after shutdown or testing, realizing the multi-purpose application of low-cost energy discharge branches.

[0108] When the power module control instruction is the second preset instruction, it means that the converter valve does not need to discharge at this time, and the full-bridge power units IGBT1, IGBT2, IGBT3, and IGBT4 in the energy self-balancing power module are controlled to be turned off, and the associated energy discharge switch IGBT5 is turned off, the energy discharge branch exits, the half-bridge power units IGBT1 and IGBT2 are turned off, the energy discharge switch IGBT3 is turned off, and the energy discharge branch exits; at this time, the DC capacitor discharges naturally through the equalizing resistor and the equivalent resistance of the energy supply, the equivalent resistance of the energy supply is determined by the operating state of the energy supply, and the operating state of the energy supply (including working and shutdown states) is determined by the DC capacitor voltage.

[0109] When the DC capacitor voltage is greater than the energy source starting voltage Ustart When the voltage is set to 300V (usually 300V), the energy source is in working state, and its equivalent resistance is hundreds of kiloohms (usually 150kΩ), which is greater than the voltage-equalizing resistor. The voltage-equalizing resistor is connected in parallel with the equivalent resistance of the energy source, and the resistance after parallel connection is R eq During steady-state operation, both the voltage-equalizing resistor and the equivalent resistance of the energy-taking power supply will produce certain steady-state losses. Since the voltage-equalizing resistor is smaller than the equivalent resistance of the energy-taking power supply, a large discharge current flows through the voltage-equalizing resistor. Increasing the voltage-equalizing resistor value can increase the parallel resistance R eq , thereby reducing the steady-state loss of the energy self-balancing power module.

[0110] When the DC capacitor voltage is less than the energy source shutdown voltage U cut (usually set to 250V), the energy source is turned off, and its equivalent resistance is more than MΩ, which is much larger than the voltage balancing resistance. The parallel resistance R eq Approximately equal to the voltage-equalizing resistor. The loss on the parallel resistor during steady-state operation is mainly determined by the value of the voltage-equalizing resistor. By increasing the value of the voltage-equalizing resistor, the steady-state loss of the energy self-balancing power module can be further reduced.

[0111] Therefore, when the power module control instruction is the second preset instruction, by controlling the exit of the full-bridge power unit and the half-bridge power unit, controlling the exit of the energy discharge branch, and increasing the resistance of the full-bridge equalizing resistor and the half-bridge equalizing resistor, the steady-state loss of the energy self-balancing power module is reduced, providing a new loss reduction technical path for the energy self-balancing power module.

[0112] It is worth mentioning that when the converter valve is operating normally, that is, when the converter valve maintenance information is 0 and the circuit breaker opening information is 0, when the converter valve is started, in the uncontrolled charging stage, the equalizing resistor and the equivalent resistance of the energy source play the role of equalizing the DC voltage of the energy self-balancing power module. The equalizing resistor is usually smaller than the equivalent resistance of the energy source. Since the equalizing resistor is a fixed value, it can play a good equalizing role.

[0113] In the present invention, based on the existing energy self-balancing power module of the converter valve, the present invention proposes a function expansion control of an energy discharge branch and a parallel resistor (the equalizing resistor is connected in parallel with the equivalent resistor of the energy source), by controlling the input of the energy discharge branch, the discharge function of the two functions of the original equalizing resistor (start-up equalization and shutdown discharge) is replaced by the energy discharge resistor, and the equalizing resistor only plays the role of equalization, and then the purpose of reducing the loss can be achieved through optimization, the discharge speed of the DC capacitor of the energy self-balancing power module is improved, the discharge time of the DC capacitor is shortened, the waiting time for the maintenance of the flexible direct current converter valve is reduced, and the maintenance efficiency of the converter valve is improved, which has reference significance for the operation and maintenance method of the flexible direct current converter valve, and at the same time, the equalizing resistor is connected in parallel with the equivalent resistor of the energy source, and the loss of the energy self-balancing power module is further reduced by increasing the resistance value of the equalizing resistor.

[0114] In order to reflect the advantages of the present invention, the following is a verification example provided by the present invention:

[0115] See also Figure 2 and Figure 4 When the converter valve is operating normally, the voltage-equalizing resistor R1 and the energy-taking power supply equivalent resistor Re are both put into operation, R1 is connected in parallel with Re, and its loss is P. The loss is calculated as follows:

[0116]

[0117] Where:

[0118] ——DC capacitor voltage

[0119] ——voltage balancing resistor and energy source parallel resistor, where , and satisfies R1 is a voltage-equalizing resistor, for example, 15 kΩ, and Re is an equivalent resistance of an energy-taking power source, for example, 150 kΩ.

[0120] From the above formula, we can know that the active power loss of the voltage-equalizing resistor and the equivalent resistance of the energy-taking power supply in steady-state operation is inversely proportional to the equivalent resistance. By increasing the equivalent resistance, the active power loss of the existing power module can be further reduced. Therefore, it is necessary to increase the voltage-equalizing resistor to achieve the purpose of increasing the equivalent resistance. For example, if the voltage-equalizing resistor R1 is increased to 30kΩ, the voltage-equalizing resistor and the energy-taking power supply equivalent resistance will consume a total of active power Pnew=0.5P, and the loss is reduced by 1 times.

[0121] Substituting actual parameters into the example, for example, the voltage equalizing resistor R1 is 15kΩ, the equivalent resistance Re of the energy source is 150kΩ, the energy dissipation resistor R2 is 2Ω, 99% of the discharge current flows through the energy dissipation resistor and discharges the DC voltage to below the safety threshold of 15V in a short time of 0.1s.

[0122] The voltage value of a DC capacitor is:

[0123]

[0124] Where:

[0125] ——DC capacitor voltage residual pressure

[0126] ——DC capacitor rated voltage

[0127] ——Discharge time

[0128] ——Discharge time constant

[0129] Discharge time constant before energy dissipation branch is put into operation

[0130] Discharge time constant after energy release branch is put into operation

[0131] Where:

[0132] After the energy-discharging branch is put into use, the discharge time constant is greatly reduced, which greatly reduces the discharge time of the DC capacitor. The DC capacitor voltage quickly drops to the safe voltage threshold, realizing the functional expansion of the energy-discharging branch. In addition to satisfying the surplus power dissipation during transient faults, it also satisfies the function of manual rapid discharge of the DC capacitor after shutdown or testing, realizing low-cost and multi-purpose applications. In summary, by reducing the discharge time constant, the discharge speed is increased, and at the same time, optimization space is provided for the parameters of the discharge resistor, providing a new design path for reducing the loss of energy self-balancing power modules.

[0133] See also Fig. 9 , Fig. 9 This is a structural block diagram of a computer device provided in Embodiment 4 of the present invention.

[0134] An electronic device according to an embodiment of the present invention comprises: a memory 401 and a processor 402, wherein the memory 402 stores a computer program; when the computer program is executed by the processor 402, the processor 402 executes the maintenance method according to any of the above embodiments.

[0135] The memory 401 may be an electronic memory such as a flash memory, an EEPROM (electrically erasable programmable read-only memory), an EPROM, a hard disk or a ROM. The memory 401 has a storage space 403 for a program code 413 for executing any method step in the above method. For example, the storage space 403 for the program code may include individual program codes 413 for implementing the various steps in the above method, respectively. These program codes may be read from or written to one or more computer program products. These computer program products include program code carriers such as hard disks, compact disks (CDs), memory cards or floppy disks. The program code may be compressed, for example, in an appropriate form. When these codes are run by a computing and processing device, the computing and processing device performs the various steps in the method described above. These program codes may be read from or written to one or more computer program products. These computer program products include program code carriers such as hard disks, compact disks (CDs), memory cards or floppy disks. The program code may be compressed, for example, in an appropriate form. When these codes are executed by a computing and processing device, the computing and processing device is caused to execute the various steps in the virtual impedance control parameter optimization method described above.

[0136] Those skilled in the art can clearly understand that, for the convenience and brevity of description, the specific working processes of the systems, devices and units described above can refer to the corresponding processes in the aforementioned method embodiments and will not be repeated here.

[0137] In the several embodiments provided in the present application, it should be understood that the disclosed systems, devices and methods can be implemented in other ways. For example, the device embodiments described above are only schematic. For example, the division of the units is only a logical function division. There may be other division methods in actual implementation, such as multiple units or components can be combined or integrated into another system, or some features can be ignored or not executed. Another point is that the mutual coupling or direct coupling or communication connection shown or discussed can be an indirect coupling or communication connection through some interfaces, devices or units, which can be electrical, mechanical or other forms.

[0138] As described above, the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit the same. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that the technical solutions described in the aforementioned embodiments may still be modified, or some of the technical features thereof may be replaced by equivalents. However, these modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A flexible direct current converter valve energy self-balancing power module maintenance device, characterized in that: It includes an energy self-balancing power module, a main control unit and a valve control unit; The main control unit is used to generate a power module control instruction according to the received converter valve maintenance information and circuit breaker disconnection information; The valve control unit is used to receive the power module control instruction and send it to the energy self-balancing power module; The energy self-balancing power module is used to respond to the power module control instruction and perform maintenance and regulation.

2. The flexible direct current valve energy self-balancing power module maintenance device according to claim 1 is characterized in that: The energy self-balancing power module includes a module control board, a full-bridge power conversion module and a half-bridge power conversion module; The full-bridge power conversion module and the half-bridge power conversion module are both communicatively connected to the module control board; The full-bridge power conversion module and the half-bridge power conversion module are both used to perform discharge operations according to the power module control instructions.

3. The flexible direct current valve energy self-balancing power module maintenance device according to claim 2 is characterized in that: The full-bridge power conversion module includes a full-bridge power unit, an energy dissipation branch, a full-bridge DC capacitor, a full-bridge energy extraction unit, a full-bridge voltage-equalizing resistor and a full-bridge diode; The full-bridge diode is connected in reverse parallel to the full-bridge power unit, and the full-bridge diode is used to provide a freewheeling channel for the reverse current to prevent the full-bridge power unit from overvoltage breakdown; The full-bridge power unit is connected in parallel with the full-bridge voltage-sharing resistor; The full-bridge voltage-equalizing resistor is connected in parallel with the full-bridge DC capacitor; The full-bridge voltage-equalizing resistor is connected in parallel with the full-bridge energy-taking unit, and is used to increase the resistance of the full-bridge voltage-equalizing resistor and reduce the steady-state loss of the energy self-balancing power module when the full-bridge energy-taking unit is in a working state; The energy dissipation branch and the full-bridge energy extraction unit are both connected in parallel with the full-bridge DC capacitor.

4. The flexible direct current valve energy self-balancing power module maintenance device according to claim 3 is characterized in that: The full-bridge power unit includes a plurality of cascaded full-bridge IGBT devices.

5. The flexible direct current valve energy self-balancing power module maintenance device according to claim 2 is characterized in that: The half-bridge power conversion module includes a half-bridge power unit, an energy dissipation branch, a half-bridge DC capacitor, a half-bridge energy extraction unit, a half-bridge voltage balancing resistor and a half-bridge diode; The half-bridge diode is connected in reverse parallel to the half-bridge power unit, and the half-bridge diode is used to provide a freewheeling channel for the reverse current to prevent the half-bridge power unit from overvoltage breakdown; The half-bridge power unit is connected in parallel with the half-bridge voltage-sharing resistor; The half-bridge voltage-sharing resistor is connected in parallel with the half-bridge DC capacitor; The half-bridge voltage-equalizing resistor is connected in parallel with the half-bridge energy extraction unit, and is used to increase the resistance of the half-bridge voltage-equalizing resistor and reduce the steady-state loss of the energy self-balancing power module when the half-bridge energy extraction unit is in a working state; The energy dissipation branch and the half-bridge energy extraction unit are both connected in parallel with the half-bridge DC capacitor.

6. The flexible direct current valve energy self-balancing power module maintenance device according to claim 5 is characterized in that: The half-bridge power unit includes a plurality of cascaded half-bridge IGBT devices.

7. The flexible direct current valve energy self-balancing power module maintenance device according to any one of claims 3 or 5, characterized in that: The energy dissipation branch includes an energy dissipation resistor and an energy dissipation switch; The energy dissipation resistor is connected in series with the energy dissipation switch; The energy dissipation switch is used to respond to the power module control instruction and control the input and output of the energy dissipation branch; The energy dissipation resistor is used to consume the electric energy stored in the capacitor when the energy dissipation branch is in the on state.

8. A maintenance method for the maintenance device for the energy self-balancing power module of a flexible direct current converter valve according to any one of claims 1 to 7, characterized in that: include: Generate power module control instructions according to the received converter valve maintenance information and circuit breaker disconnection information; Receive power module control instructions, respond to power module control instructions, and perform maintenance and regulation on the energy self-balancing power module.

9. The maintenance method according to claim 8, characterized in that: The step of responding to the power module control instruction and performing maintenance and regulation on the energy self-balancing power module comprises: When the power module control instruction is the first preset instruction, the full-bridge power unit and the half-bridge power unit are controlled to exit, the energy discharge branch is controlled to be put into operation, and the energy self-balancing power module is discharged; When the power module control instruction is the second preset instruction, the full-bridge power unit and the half-bridge power unit are controlled to exit, the energy discharge branch is controlled to exit, the resistance of the full-bridge equalizing resistor and the half-bridge equalizing resistor is increased, and the steady-state loss of the energy self-balancing power module is reduced.

10. An electronic device, characterized in that: It comprises a memory and a processor, wherein the memory stores a computer program, and when the computer program is executed by the processor, the processor executes the steps of the maintenance method according to any one of claims 8 to 9.

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