Equal-capacity alternating-current energy consumption configuration method, switching method, device and equipment

Abstract

The invention discloses an equal-capacity alternating-current energy consumption configuration method and switching method, device and equipment, and the configuration method comprises the steps: obtaining the total capacity of alternating-current energy consumption needing to be configured; determining the total group number of AC energy consumption branches and the capacity of each group of AC energy consumption branches according to the rated AC voltage grade and the equipment parameters; a group of equal-capacity redundant alternating-current energy consumption branches are additionally configured; the capacity of the redundant alternating-current energy consumption branch is the same as that of the alternating-current energy consumption branch, and when a non-redundant group alternating-current energy consumption branch is damaged, a redundant group can be used for replacement, so that reliable suppression of surplus power is ensured; and simulating the operation state of the power system, and determining the resistance of each group of AC energy consumption branch by taking the condition that the AC energy consumption can absorb all surplus power when the AC voltage is reduced to the maximum as a standard. According to the invention, AC and DC overvoltage suppression after fault ride-through or locking of the modular multi-level converter is realized, and the operation requirement of a system for sending out new energy through a flexible DC island is met.

Description

Technical Field

[0001] This invention belongs to the field of power electronic converters, and specifically relates to an equal-capacity AC energy consumption configuration method and switching method, device and equipment. Background Technology

[0002] my country is facing a strategic adjustment of its energy structure and is currently promoting the large-scale development of new energy sources such as wind power and solar energy. my country's large-scale new energy bases are mainly distributed in the "Three Norths" region (Northeast, North, and Northwest China), generally located at the end of the power grid, where the grid is relatively weak and thousands of kilometers away from load centers in central and eastern China. While offshore wind power development potential is significant in central and eastern China, its distance from the coast is too great, and it lacks grid support. Due to the geographical location of new energy power plants, there is a trend of large-scale centralized access to wind and solar power. Utilizing the voltage source characteristics of flexible DC transmission, large-scale new energy sources can be connected to the grid in an islanded manner via flexible DC transmission. The feasibility of this has been proven by the implementation of the ±500 kV Zhangbei flexible DC grid pilot demonstration project.

[0003] However, during a fault in the flexible DC transmission system, a large amount of surplus power will be generated due to the reduced power transmission capacity of the flexible DC system and the difficulty in controlling the power of isolated renewable energy sources. If this surplus power is not controlled in a timely manner, it will seriously threaten the stability of the power grid and the safety of equipment. Currently, the main method for controlling surplus power during a fault in the flexible DC transmission system is from the perspective of energy dissipation. During a fault, AC / DC energy dissipation devices are used to consume the surplus power injected into the flexible DC system from isolated renewable energy sources.

[0004] There are two ways to configure energy-consuming resistors: one is to configure AC energy-consuming resistors at the sending end, and the other is to configure DC energy-consuming resistors at the receiving end. For the case of configuring DC energy-consuming resistors at the receiving end, it cannot effectively suppress surplus power during single-pole blocking at the sending end and DC line fault restarts. For the case of configuring AC energy-consuming resistors at the sending end, it can effectively suppress power surplus during periods including single-pole blocking at the sending end, DC line fault restarts, receiving end blocking, and AC system faults at the receiving end. Therefore, current true double-double topology islanded flexible DC transmission often uses the method of configuring equal-capacity AC energy-consuming resistors at the sending end to suppress power surplus. However, when islanded flexible DC transmission scenarios are applied to UHV large-capacity scenarios, in order to reduce the number of groups when equal-capacity groups are formed, the number of energy-consuming resistors is small, resulting in a large power per group. When the energy-consuming resistors are removed, it will cause a serious impact on the power system. In addition, the large capacity of a single energy-consuming group can easily lead to large fluctuations in DC voltage and power oscillations due to excessive connection. Current grouping design methods can only compensate for the negative impact (impact and excessive investment) of excessive power in a single energy-consuming resistor by reducing the capacity of a single energy-consuming resistor. However, reducing the capacity of a single energy-consuming resistor will lead to a significant increase in the number of energy-consuming resistors, the complexity of the energy-consuming control system, the floor space, and the engineering cost.

[0005] Therefore, there is an urgent need for a method for configuring and switching energy-consuming resistors that can reduce system impact and more closely approximate the required capacity, which led to this proposal. Summary of the Invention

[0006] The purpose of this invention is to provide an equal-capacity AC energy consumption configuration method and switching method, device and equipment, for suppressing AC and DC overvoltages after fault ride-through or blocking of modular multilevel converters, so as to meet the operation requirements of the new energy transmission system via flexible DC islanding.

[0007] To achieve the above objectives, the solution of the present invention is: A method for configuring AC power consumption with equal capacity, including, Obtain the total AC power consumption capacity to be configured; the total AC power consumption capacity is sufficient to reliably suppress the surplus power of the flexible DC system when all are in operation; The total AC power consumption capacity is allocated based on the rated AC voltage level and equipment parameters to determine the total number of AC power consumption branches and the capacity of each branch; the impact of the power consumption branches on the power system does not need to be considered. An additional set of redundant AC power consumption branches with equal capacity is configured; the capacity of the redundant AC power consumption branches is the same as that of the AC power consumption branches. When the non-redundant AC power consumption branches are damaged, the redundant group can be used to replace them to ensure reliable suppression of surplus power. The operating state of the simulated power system is used as the standard that the AC energy consumption can absorb all the surplus power when the AC voltage drops to its maximum, and the resistance of each AC energy consumption branch is determined. The AC system is configured with SVG, the capacity of which meets the harmonic suppression and reactive power compensation requirements of a single group of energy-consuming trigger angles.

[0008] Among them, the AC energy consumption is configured at the sending-end new energy station. Each AC energy consumption branch is composed of a series of delta-connected resistors and anti-parallel thyristors, and the parameters of the resistors and anti-parallel thyristors connected to the three delta-connected circuits are exactly the same.

[0009] This includes obtaining the total AC power consumption capacity to be configured, including: Obtain the surplus power P that the AC power grid can absorb gx ; According to the AC power grid, the surplus power P can be absorbed. gx The required total AC power consumption capacity PMAX = P mz -P gx , where P mz P represents the rated transmission capacity of the flexible DC transmission system; when the flexible DC system operates in islanded mode, i.e., without an AC power grid, P gx =0.

[0010] Specifically, the total AC power consumption capacity is allocated according to the rated AC voltage level and equipment parameters, determining the total number of AC power consumption branches and the capacity of each AC power consumption branch, including: Taking into account the rated AC voltage level of the secondary side of the energy-consuming transformer, the current withstand capability of the thyristors switching the AC energy-consuming branches, the short-time overload capacity of the energy-consuming transformer, and the rated capacity of the flexible DC system, the capacity of each group of AC energy-consuming branches is determined. P h Number of AC power dissipation branch groups that can be connected to each power dissipation transformer N h Then the total number of AC energy-consuming branches is N h * k , k The number of energy-consuming transformers should be such that the product of the capacity of each AC energy-consuming branch and the total number of AC energy-consuming branches equals the total AC energy-consuming capacity; the capacity of a single AC energy-consuming branch should be as large as possible to reduce the overall number of branches. N Z .

[0011] The simulation of the power system's operating state uses the maximum AC voltage drop and the ability of AC energy consumption to absorb all surplus power as a standard to determine the resistance of each AC energy consumption branch, including... Construct a power system simulation model; The simulation model operates at full power, with all AC power-consuming branches engaged, to obtain the power consumed by a single AC power-consuming branch. Adjust the resistance value of the AC power consumption branch so that the capacity of a single AC power consumption branch reaches the capacity of each AC power consumption branch determined above. The resistance value at this time is the required resistance value of the AC power consumption branch.

[0012] An equal-capacity AC power consumption configuration device includes, The AC total energy consumption capacity acquisition module is configured to acquire the total AC energy consumption capacity to be configured; the total AC energy consumption capacity is sufficient to reliably suppress the surplus power of the flexible DC system when all components are in operation; The AC power consumption branch total number and capacity allocation module is configured to allocate the total AC power consumption capacity according to the rated AC voltage level and equipment parameters, and determine the total number of AC power consumption branches and the capacity of each AC power consumption branch. The redundancy group configuration module is configured to configure a group of redundant AC power consumption branches; the redundant AC power consumption branches have the same capacity as the AC power consumption branches; and, The AC energy consumption branch resistance configuration module is configured to simulate the operating state of the power system. The standard is that the AC energy consumption can absorb all the surplus power when the AC voltage drops to its maximum, and the resistance of each AC energy consumption branch is determined.

[0013] Among them, the AC energy consumption is configured at the sending-end new energy station. Each AC energy consumption branch is composed of a series of delta-connected resistors and anti-parallel thyristors, and the parameters of the resistors and anti-parallel thyristors connected to the three delta-connected circuits are exactly the same.

[0014] The AC power consumption total capacity acquisition module acquires the total AC power consumption capacity that needs to be configured, including: Obtain the surplus power P that the AC power grid can absorb gx ; According to the AC power grid, the surplus power P can be absorbed. gx The required total AC power consumption capacity PMAX = P mz -P gx , where P mz This refers to the rated conveying capacity of the flexible straight conveyor.

[0015] The AC power consumption branch total number and capacity allocation module allocates the total AC power consumption capacity according to the rated AC voltage level and equipment parameters, determining the total number of AC power consumption branches and the capacity of each AC power consumption branch, including... Taking into account the rated AC voltage level of the secondary side of the energy-consuming transformer, the current withstand capability of the thyristors switching the AC energy-consuming branches, the short-time overload capacity of the energy-consuming transformer, and the rated capacity of the flexible DC system, the capacity of each group of AC energy-consuming branches is determined. P h Number of AC power dissipation branch groups that can be connected to each power dissipation transformer N h Then the total number of AC energy-consuming branches is N h * k , k The number of energy-consuming transformers is such that the product of the capacity of each AC energy-consuming branch and the total number of AC energy-consuming branches is equal to the total AC energy-consuming capacity.

[0016] The AC energy consumption branch resistance configuration module simulates the power system operating state. Using the maximum AC voltage drop as a standard, it determines the resistance of each AC energy consumption branch, including... Construct a power system simulation model; The simulation model operates at full power, with all AC power-consuming branches engaged, to obtain the power consumed by a single AC power-consuming branch. Adjust the resistance value of the AC power consumption branch so that the capacity of a single AC power consumption branch reaches the capacity of each AC power consumption branch determined above. The resistance value at this time is the required resistance value of the AC power consumption branch.

[0017] A switching method for AC power consumption includes, The number of AC energy-consuming branches to be put into operation and the initial phase shift angle of the phase-shifting switching group are determined based on the surplus power. The former and the latter are put into operation simultaneously, so that the total capacity of the AC energy-consuming branches and the power surplus capacity are within a set range. Among them, the AC energy-consuming branches use anti-parallel thyristors for switching resistors. The switching methods include overall switching without trigger angle and phase-shifting switching with trigger angle, and only one group is allowed to perform phase-shifting switching at the same time. Based on changes in electrical quantities, the AC energy consumption input capacity is adjusted by phase shifting. When disconnecting AC energy-consuming branches, each group sequentially switches phases to disconnect according to power system impact requirements or coordination with power stabilization and control switching requirements.

[0018] The number of groups of AC energy-consuming branches to be put into operation is determined based on the surplus power, including: The total number of input groups is determined by dividing the surplus power by the capacity of a single AC power-consuming branch and rounding down. N Z ,

[0019] in, PY Surplus power, P h This refers to the capacity of a single AC power consumption branch. The method for obtaining surplus power is as follows: When power is consumed due to overvoltage at the sending end, the surplus power is either the operating power of the flexible DC system or calculated based on the overvoltage level at the sending end. When an AC fault occurs at the sending-end converter station, the surplus power is equal to the total operating power of the flexible DC system. When the sending-end converter is locked, the surplus power is the total power of the locked converters in the flexible DC system, i.e., the single-valve operating power when a single valve is locked; the single-pole operating power when a single pole is locked; and the total operating power when a double pole is locked. When a DC line fault occurs, the surplus power is the operating power of the faulty pole. That is, when a single-pole fault occurs, it is the operating power of the faulty pole; when a double-pole fault occurs, it is the total operating power.

[0020] Among these steps, determining the initial phase shift angle of the phase-shifting switching group based on the surplus power includes, Based on the surplus power, the remaining surplus power is obtained. ,in, PY Surplus power, P h For the capacity of a single AC power consumption branch, N Z This refers to the total number of groups involved. Based on the remaining surplus power, the corresponding firing angle is obtained by looking up a table, which is the initial phase shift angle of the phase-shifting switching group; wherein, the two-dimensional table required for the lookup is obtained according to the following method. The surplus power of a single AC energy-consuming branch was obtained by simulation at different firing angles. The data of firing angle and surplus power of each group were fitted to obtain a two-dimensional table of firing angle and surplus power of a single AC energy-consuming branch.

[0021] Among them, the overall casting and cutting methods without trigger angle include, The AC power dissipation branch, based on the received unlock signal, immediately triggers the thyristor in the anti-parallel thyristor that is under positive voltage at the unlock moment; after unlocking, it triggers the thyristor that is under positive voltage after the zero crossing point, and the forward and reverse thyristor trigger pulses are 180° out of phase after unlocking. Phase-shifting switching methods with trigger angles include, The AC power dissipation branch, upon receiving the unlock signal, immediately triggers the thyristor in the anti-parallel thyristor that is under positive voltage at the unlock moment; after unlocking, a trigger pulse with a trigger angle is applied to the thyristor under positive voltage after the zero-crossing point, and the trigger pulses of the forward and reverse thyristors are 180° out of phase after unlocking.

[0022] The zero-crossing point is determined using the following method: Detect the zero-crossing point of the main grid AC voltage, and calculate the zero-crossing point of the energy-consuming resistor side of the energy-consuming transformer according to the wiring method of the AC energy-consuming branch transformer; Determine whether the device is under positive pressure after crossing zero using the following method. The AC voltage of the main grid is detected, and the AC voltage on the energy-consuming resistor side of the energy-consuming transformer is calculated according to the wiring method of the AC energy-consuming branch transformer, so as to determine whether it is subjected to positive voltage after the zero point.

[0023] This includes adjusting the AC energy consumption capacity based on changes in electrical quantities through phase shifting, including: The phase shift angle Δα is obtained by applying PI control to the DC voltage at the sending end and the setpoint of the energy dissipation voltage for switching on and off: When the phase shift angle Δα is negative, the trigger angle of the first phase shift group is changed from α to α-|Δα|; when the trigger angle of the phase shift group is reduced to zero, i.e., α-|Δα|=0, the second group is phase shifted with a phase shift angle of 180°-(|Δα|-α); when the trigger angle of the second group is reduced to zero, the third group is phase shifted with a phase shift angle of 180°-(|Δα|-α-180°); and so on, with subsequent phase shift angles being 180°-(|Δα|-α-n·180°), where n is the number of phase shift groups, until the phase shift angle Δα becomes positive and is reset to zero; When the phase shift angle Δα is positive, the trigger angle of the first phase shift group is changed from α to α+Δα; when the trigger angle of the phase shift group is fully added, i.e., α+Δα=180°, the second group is phase shifted, and the phase shift angle is Δα-(180°-α); when the trigger angle of the second group is fully added, the third group is phase shifted, and the phase shift angle is Δα-(180°+180°-α); and so on, the subsequent phase shift angle is Δα-(n·180°-α), where n is the number of phase shift groups, until the phase shift angle Δα becomes negative and is reset to zero; The energy consumption voltage setting for the supplementary switching is switched according to the overvoltage level. When the DC voltage at the sending end is greater than the energy consumption setting, the energy consumption voltage setting for the supplementary switching is equal to the energy consumption setting. When the DC voltage at the sending end is less than the energy consumption setting, the energy consumption voltage setting for the supplementary switching is equal to the energy consumption setting. The energy consumption setting is greater than the energy consumption setting, and the energy consumption setting is greater than the overvoltage setting when the energy consumption is applied during an overvoltage at the sending end.

[0024] When disconnecting an AC power-consuming branch, each group sequentially performs a phase shift, including: Determine the total power PTUI that needs to be withdrawn in the current control cycle based on the required rate of energy consumption cut-off; obtain the power PYTUI consumed by the currently engaged phase shifter group; Determine the phase shift angle based on the relationship between PTUI and PYTUI. When PTUI≤PYTUI, the phase shift angle that the phase shift group needs to be adjusted to in the current control cycle is determined according to PYTUI-PTUI; When PTUI > PYTUI, the current phase shift group is completely de-shifted. Then, based on PTUI and PYTUI+... P h A set of relationships is selected for phase shifting. When PTUI≤PYTUI+ P h At that time, according to PYTUI+ P h -PTUI determines the phase shift angle that the new phase shift group needs to be adjusted to in the current control cycle; When PTUI > PYTUI+ P h When the current phase shifting group has completely de-phased, another group is selected for phase shifting: when PTUI≤PYTUI+2· P h At that time, for PYTUI+2· P h -PTUI performs a table lookup to determine the phase shift angle that the new phase shift group needs to be adjusted to in the current control cycle; Similarly, when the newly selected phase shift group is the nth group, PTUI ≤ PYTUI + n· P hAt that time, for PYTUI+n· P h -PTUI performs a table lookup to determine the phase shift angle that the new phase shift group needs to be adjusted to in the current control cycle; This process continues until all energy consumption is eliminated.

[0025] An AC power switching device includes, The switching module is configured to determine the number of AC power consumption branches to be switched on and the initial phase shift angle of the phase-shifting switching group based on the surplus power, so that the total capacity of the switched AC power consumption branches and the surplus power capacity are within a set range. The AC power consumption branches use anti-parallel thyristors as switching resistors. The switching methods include overall switching without trigger angle and phase-shifting switching with trigger angle, and only one group is allowed to perform phase-shifting switching at the same time. The capacity adjustment module is configured to adjust the AC energy consumption capacity by phase shifting according to changes in electrical quantities; and, When the energy dissipation module is configured to exit the AC energy dissipation branch, each group will sequentially shift phases to disconnect according to the power system impact requirements or the need to coordinate with the power stabilization and control switch.

[0026] The switching module determines the number of AC power consumption branches to be switched on based on the surplus power, including: The total number of input groups is determined by dividing the surplus power by the capacity of a single AC power-consuming branch and rounding down. N Z ,

[0027] in, PY Surplus power, P h This refers to the capacity of a single AC power consumption branch. The method for obtaining surplus power is as follows: When power is consumed due to overvoltage at the sending end, the surplus power is either the operating power of the flexible DC system or calculated based on the overvoltage level at the sending end. When an AC fault occurs at the sending-end converter station, the surplus power is equal to the total operating power of the flexible DC system. When the sending-end converter is locked, the surplus power is the total power of the locked converters in the flexible DC system, i.e., the single-valve operating power when a single valve is locked; the single-pole operating power when a single pole is locked; and the total operating power when a double pole is locked. When a DC line fault occurs, the surplus power is the operating power of the faulty pole. That is, when a single-pole fault occurs, it is the operating power of the faulty pole; when a double-pole fault occurs, it is the total operating power.

[0028] The switching module determines the initial phase shift angle of the phase-shifting switching group based on the surplus power, including: Based on the surplus power, the remaining surplus power is obtained. ,in, PY Surplus power, P h For the capacity of a single AC power consumption branch, N Z This refers to the total number of groups involved. Based on the remaining surplus power, the corresponding firing angle is obtained by looking up a table, which is the initial phase shift angle of the phase-shifting switching group; wherein, the two-dimensional table required for the lookup is obtained according to the following method. The surplus power of a single AC energy-consuming branch was obtained by simulation at different firing angles. The data of firing angle and surplus power of each group were fitted to obtain a two-dimensional table of firing angle and surplus power of a single AC energy-consuming branch.

[0029] Among them, the overall casting and cutting methods without trigger angle include, The AC power dissipation branch, based on the received unlock signal, immediately triggers the thyristor in the anti-parallel thyristor that is under positive voltage at the unlock moment; after unlocking, it triggers the thyristor that is under positive voltage after the zero crossing point, and the forward and reverse thyristor trigger pulses are 180° out of phase after unlocking. Phase-shifting switching methods with trigger angles include, The AC power dissipation branch, upon receiving the unlock signal, immediately triggers the thyristor in the anti-parallel thyristor that is under positive voltage at the unlock moment; after unlocking, a trigger pulse with a trigger angle is applied to the thyristor under positive voltage after the zero-crossing point, and the trigger pulses of the forward and reverse thyristors are 180° out of phase after unlocking.

[0030] The zero-crossing point is determined using the following method: Detect the zero-crossing point of the main grid AC voltage, and calculate the zero-crossing point of the energy-consuming resistor side of the energy-consuming transformer according to the wiring method of the AC energy-consuming branch transformer; Determine whether the device is under positive pressure after crossing zero using the following method. The AC voltage of the main grid is detected, and the AC voltage on the energy-consuming resistor side of the energy-consuming transformer is calculated according to the wiring method of the AC energy-consuming branch transformer, so as to determine whether it is subjected to positive voltage after the zero point.

[0031] The capacity adjustment module adjusts the AC energy consumption capacity based on changes in electrical quantities through phase shifting, including: The phase shift angle Δα is obtained by applying PI control to the DC voltage at the sending end and the setpoint of the energy dissipation voltage for switching on and off: When the phase shift angle Δα is negative, the trigger angle of the first phase shift group is changed from α to α-|Δα|; when the trigger angle of the phase shift group is reduced to zero, i.e., α-|Δα|=0, the second group is phase shifted with a phase shift angle of 180°-(|Δα|-α); when the trigger angle of the second group is reduced to zero, the third group is phase shifted with a phase shift angle of 180°-(|Δα|-α-180°); and so on, with subsequent phase shift angles being 180°-(|Δα|-α-n·180°), where n is the number of phase shift groups, until the phase shift angle Δα becomes positive and is reset to zero; When the phase shift angle Δα is positive, the trigger angle of the first phase shift group is changed from α to α+Δα; when the trigger angle of the phase shift group is fully added, i.e., α+Δα=180°, the second group is phase shifted, and the phase shift angle is Δα-(180°-α); when the trigger angle of the second group is fully added, the third group is phase shifted, and the phase shift angle is Δα-(180°+180°-α); and so on, the subsequent phase shift angle is Δα-(n·180°-α), where n is the number of phase shift groups, until the phase shift angle Δα becomes negative and is reset to zero; The energy consumption voltage setting for the supplementary switching is switched according to the overvoltage level. When the DC voltage at the sending end is greater than the energy consumption setting, the energy consumption voltage setting for the supplementary switching is equal to the energy consumption setting. When the DC voltage at the sending end is less than the energy consumption setting, the energy consumption voltage setting for the supplementary switching is equal to the energy consumption setting. The energy consumption setting is greater than the energy consumption setting, and the energy consumption setting is greater than the overvoltage setting when the energy consumption is applied during an overvoltage at the sending end.

[0032] When the de-consuming module exits the AC energy consumption branch, each group sequentially performs a phase shift cutoff, including: Determine the total power PTUI that needs to be withdrawn in the current control cycle based on the required rate of energy consumption cut-off; obtain the power PYTUI consumed by the currently engaged phase shifter group; Determine the phase shift angle based on the relationship between PTUI and PYTUI. When PTUI≤PYTUI, the phase shift angle that the phase shift group needs to be adjusted to in the current control cycle is determined according to PYTUI-PTUI; When PTUI > PYTUI, the current phase shift group is completely de-shifted. Then, based on PTUI and PYTUI+... P h A set of relationships is selected for phase shifting. When PTUI≤PYTUI+ P h At that time, according to PYTUI+ P h -PTUI determines the phase shift angle that the new phase shift group needs to be adjusted to in the current control cycle; When PTUI > PYTUI+ Ph When the current phase shifting group has completely de-phased, another group is selected for phase shifting: when PTUI≤PYTUI+2· P h At that time, for PYTUI+2· P h -PTUI performs a table lookup to determine the phase shift angle that the new phase shift group needs to be adjusted to in the current control cycle; Similarly, when the newly selected phase shift group is the nth group, PTUI ≤ PYTUI + n· P h At that time, for PYTUI+n· P h -PTUI performs a table lookup to determine the phase shift angle that the new phase shift group needs to be adjusted to in the current control cycle; This process continues until all energy consumption is eliminated.

[0033] A computer device includes a memory, a processor, and a computer program stored in the memory and executable on the processor; the processor executes the computer program to implement the steps of the AC power consumption switching method as described above.

[0034] A computer-readable storage medium storing a computer program; when executed by a processor, the computer program implements the steps of the AC power switching method as described above.

[0035] After adopting the above scheme, the switching method of the large-capacity energy-consuming group combined with phase shifting designed in this invention is reliable in principle and simple to implement. On the one hand, it can realize the configuration of energy-consuming resistors according to the number of large-capacity groups and fine switching, so that the put-in energy-consuming capacity is closer to the power surplus capacity, avoiding the frequent switching and unswitching caused by excessive DC voltage drop, reducing the footprint and saving costs. On the other hand, when the energy-consuming group is withdrawn after the fault ends, the withdrawal speed can be controlled by phase shifting to reduce the system impact caused by the withdrawal of a single large-capacity energy-consuming group. Attached Figure Description

[0036] Figure 1 This is a schematic diagram of the equal-capacity AC energy consumption configuration method provided in an embodiment of the present invention; Figure 2 This is a schematic diagram of the overall casting and switching method without trigger angle provided in an embodiment of the present invention; Figure 3 This is a schematic diagram of a phase-shifting switching method with a trigger angle provided in an embodiment of the present invention. Detailed Implementation

[0037] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the invention. Furthermore, the technical features involved in the various embodiments of this invention described below can be combined with each other as long as they do not conflict with each other.

[0038] The invention will now be further explained with reference to the accompanying drawings.

[0039] Figure 1 In the case of main grid 103 operating in islanded mode (i.e., without a main grid), the AC power grid can absorb the surplus power P. gx =0; the rated capacity of the flexible DC system 104 is 8000MW, i.e., P mz =8000MW; the rated capacity of the new energy system 102 is 8000MW; the AC system is also equipped with an SVG system 101; the main grid level is 525kV, the secondary voltage level of the energy-consuming transformer is 69kV; the capacity of the energy-consuming transformer is 800MW, the connection method is y0d, and the energy-consuming transformer can be overloaded by 3 times within 1 second; the maximum current carrying capacity of thyristors on the market is 6500A.

[0040] Based on this parameter, the design process for configuring the AC energy-dissipating resistor is as follows: a) Determine the total energy consumption capacity requirement: The total AC power consumption capacity satisfies the requirement of reliably suppressing the surplus power of the flexible DC system when all components are in operation, PMAX = P mz -P gx =8000MW.

[0041] b) Determine the capacity of a single group and the total number of groups: Based on the secondary voltage level of the energy-consuming transformer being 69kV; the transformer capacity being 800MW; the transformer being able to withstand a short-term overload of 3 times its rated capacity within 1 second; and considering the current market maximum current-carrying capacity of thyristors at 6500A, the maximum designable capacity for a single energy-consuming transformer group, which facilitates equal distribution, is determined to be 1000MW. P h =1000MW, total number of groups N h =8, the number of branches that can be connected to a single transformer is: N h =2, such as Figure 1 The non-redundant group 106 is shown.

[0042] c) Configure redundancy groups: An additional 1000MW branch line is configured as a redundancy group, such as... Figure 1 The redundant group 107 is shown in the diagram. When the AC power consumption branch of the non-redundant group is damaged, it can be replaced by the redundant group to ensure reliable suppression of surplus power. d) Using simulation, obtain the resistance of the AC power-consuming branch in each group: The method for determining the resistance using simulation is as follows: Simulate the power system so that when the AC voltage drops to its maximum, the AC energy consumption can absorb all surplus power, ensuring that when operating at full power, the full deployment of AC energy consumption can suppress all power loss. A system model is built and operates at full power. Simulations are performed to deploy all AC energy consumption branches, at which point the AC voltage drops to its maximum. The power consumed by each AC energy consumption branch is observed, and the resistance values ​​of each branch are adjusted to achieve the capacity of each AC energy consumption branch as described in section a), ensuring that all AC energy consumption can suppress all surplus power. This determines the resistance of each AC energy consumption branch. R m =57.89Ω.

[0043] e) Configure SVG: The AC system is configured with SVG, whose capacity meets the requirements for harmonic suppression and reactive power compensation under different firing angles of a single group of energy consumption. According to engineering experience, the SVG configuration capacity is generally 60% of the active power capacity, i.e., 600MW.

[0044] Based on the above parameters and configuration, the AC energy consumption control method is as follows: f) The AC power consumption branch uses anti-parallel thyristors to switch the resistors. The switching method is divided into two types: overall switching without trigger angle and phase-shift switching with trigger angle. Only one group is allowed to perform phase-shift switching at the same time. Specifically, the overall casting method without trigger angle is as follows: After the AC power dissipation branch receives the unlock signal from the flexible DC control, the unlocking triggering method is as follows: immediately and directly trigger the thyristor in the anti-parallel thyristor that is subjected to positive voltage, such as... Figure 2 At time t0, the positive thyristor under positive pressure is immediately triggered; after unlocking, the triggering method is: the thyristor under positive pressure after zero crossing is triggered at zero crossing, as shown in the figure. Figure 2 The reverse thyristor, triggered at time t1, is subjected to positive pressure after crossing zero; the forward thyristor, triggered at time t2, is subjected to positive pressure after crossing zero. After unlocking, the trigger pulses of the forward and reverse thyristors are 180° out of phase.

[0045] Specifically, the phase-shifting switching method with firing angle α is as follows: After the AC power dissipation branch receives the unlock signal from the flexible DC control, the unlocking triggering method is as follows: immediately and directly trigger the thyristor in the anti-parallel thyristor that is subjected to positive voltage, such as... Figure 3 At time t0, the positive thyristor under positive pressure is immediately triggered; after unlocking, the triggering method is as follows: a trigger pulse with a trigger angle α is applied to the thyristor under positive pressure after the zero-crossing point, such as... Figure 3As shown, a trigger pulse is applied at time t2, which is a delay of the trigger angle α, to the reverse thyristor subjected to positive pressure after the zero-crossing point t1. A trigger pulse is applied at time t4, which is a delay of the trigger angle α, to the forward thyristor subjected to positive pressure after the zero-crossing point t3. After unlocking, the trigger pulses of the forward and reverse thyristors are 180° out of phase.

[0046] Furthermore, the method for determining zero crossings is as follows: No new measuring points are needed. The DC control system is used to detect the zero-crossing point of the AC voltage of the main grid, and the zero-crossing point of the energy-consuming resistor side of the energy-consuming branch transformer is calculated according to the wiring method of the energy-consuming branch transformer.

[0047] The voltage conversion method for the y0d wiring method in the embodiment is as follows: UAR = UAG - UAB; UBR = UBG - UCG; UCR = UCG - UAG; UAR, UBR, and UCR are the AC voltages on the energy-consuming resistor side of the energy-consuming transformer, while UAG, UBG, and UCG are the AC voltages of the main grid. The zero-crossing point is determined based on UAR, UBR, and UCR.

[0048] Furthermore, the method for determining whether positive pressure is applied after crossing zero is as follows: No new measuring points are needed. The DC control system is used to detect the AC voltage of the main grid, and the AC voltage on the energy-consuming resistor side of the energy-consuming branch transformer is calculated according to the wiring method of the energy-consuming branch transformer. The calculation method is the same as above. UAR, UBR, and UCR are used to determine whether the voltage is positive after crossing the zero point.

[0049] g) When the AC energy-consuming branch is put into operation, the total number of groups put into operation and the initial phase shift angle of the phase shift switching group are determined according to the surplus power. The former and the latter are put into operation at the same time to ensure that the total capacity of the AC energy-consuming branch put into operation is approximately equal to the power surplus capacity. Specifically, the method for determining the total number of throwing groups is as follows: The total number of connected groups is determined by dividing the surplus power by the floor function of the single AC power-consuming branch capacity. When the sending end experiences overvoltage and energy consumption, the surplus power PY is either the operating power of the flexible DC system or calculated based on the sending end overvoltage level. Furthermore, the method for calculating based on the overvoltage level at the sending end is as follows:

[0050] in: N This refers to the number of sub-modules in a single bridge arm. C The capacitance value of the submodule; U dov1 The overpressure start-up calculation setpoint, U dov1 <U over , U over This is the overvoltage setting value; U dov2 The overvoltage termination calculation setpoint is set, and U dov2 > U dov1 , usually take U dov2 = U over ,or U dov2 Slightly smaller U over ; T i DC voltage from U dov1 Rise to U dov2 The time elapsed; U dcN < U dov1 , U dcN Rated DC voltage; shilling P Y min( P yc , P m ),in, P m The maximum capacity that can be deployed for energy consumption; When an AC fault occurs at the sending-end converter station, the surplus power PY is the total operating power of the flexible DC system. When the sending-end converter is locked, the surplus power PY is the total power of the locked converter in the flexible DC system, i.e., the single-valve operating power when locked by a single valve; the single-pole operating power when locked by a single pole; and the total operating power when locked by a double pole. When a DC line fault occurs, the surplus power PY is the operating power of the faulty pole, that is, the operating power of the faulty pole during single-pole fault ride-through; and the total operating power during double-pole fault ride-through.

[0051] This embodiment assumes a surplus power PY = 3125MW.

[0052] Total number of input groups N Z for:

[0053] Specifically, the method for determining the initial phase shift angle of the phase-shifting switch group based on the remaining surplus power is as follows: The firing angle α is obtained by looking up a table, and a phase-shift control is then implemented. The trigger angle α is obtained as follows: The surplus power consumption capacity of a single energy-consuming branch was obtained through simulation at different trigger angles α. A large number of points were selected during the simulation for the different trigger angles α. Finally, the relationship between the trigger angle α and the surplus power consumption capacity of a single energy-consuming branch was fitted, thereby obtaining a two-dimensional table of the trigger angle α and the surplus power consumption capacity of a single energy-consuming branch. Based on the remaining surplus power to be consumed, 3125-3*1000=125MW, the trigger angle α was obtained by looking up the table and performing linear interpolation: α=140-(125-116.98) / (178.61-116.98)×(140-130)=138.7°. The calculation method was linear interpolation.

[0054] The resulting two-dimensional table can be found in Table 1.

[0055]

[0056] h) After the energy-consuming branch is put into operation, the AC energy-consuming capacity can be flexibly adjusted by phase shifting according to the changes in electrical quantities; Specifically, the DC voltage at the sending end and the setpoint for the supplementary switching energy consumption voltage are controlled by a PI controller. The result of the PI control is the phase shift angle Δα. The supplementary switching energy consumption voltage setting is switched according to the overvoltage level. When the DC voltage at the sending end is greater than the supplementary switching energy consumption setting, the supplementary switching energy consumption voltage setting is equal to the supplementary switching energy consumption setting; when the DC voltage at the sending end is less than the supplementary switching energy consumption setting, the supplementary switching energy consumption voltage setting is equal to the supplementary switching energy consumption setting; wherein, the supplementary switching setting is greater than the supplementary switching setting, and the supplementary switching setting is greater than the overvoltage setting when the sending end overvoltages and energy consumption is applied.

[0057] The result of the PI control is the phase shift angle, which is the angle by which the initial firing angle of the phase shift group needs to change. When the angle Δα is negative, it means that additional energy consumption needs to be consumed, and the firing angle of the phase shifting group becomes α-|Δα|. When the firing angle of the phase shifting group is reduced to zero (α-|Δα|=0), another group is selected for phase shifting, and the phase shift angle is 180°-(|Δα|-α). When the firing angle of this group is reduced to zero, another group is selected for phase shifting, and the phase shift angle is 180°-(|Δα|-α-180°). And so on, the subsequent phase shift angle is 180°-(|Δα|-α-n·180°), where n is the number of groups selected as phase shifting groups. When the angle Δα becomes positive, it is reset to zero. When the angle Δα is positive, additional energy needs to be supplied, and the trigger angle of the phase shifting group becomes α + Δα. When the trigger angle of the phase shifting group is fully added (α + Δα = 180°), another group is selected for phase shifting, and the phase shift angle is Δα - (180° - α). When the trigger angle of this group is fully added, another group is selected for phase shifting, and the phase shift angle is Δα - (180° + 180° - α). And so on, the subsequent phase shift angle is Δα - (n·180° - α), where n is the number of groups selected as phase shifting groups. When the angle Δα becomes negative, it is reset to zero.

[0058] i) When the AC energy-consuming branch is disconnected, each group is disconnected in sequence according to the power system impact requirements or the need to coordinate with the power stabilization and control switch.

[0059] Specifically, when a blocking fault occurs, it needs to be coordinated with the stability control switch; for other faults, the power system impact requirements need to be considered to perform phase shifting and disconnection at a certain speed.

[0060] Specifically, the energy consumption reduction method is as follows: i1) Determine the total power PTUI that needs to be withdrawn in the current control cycle based on the system's energy consumption rate requirements; i2) Look up the table to determine the power consumption PYTUI of the currently activated phase shifter; execute step i3) or step i4) according to the relationship between PTUI and PYTUI. i3) When PTUI≤PYTUI, look up PYTUI-PTUI in the table to determine the phase shift angle that the phase shift group needs to be adjusted to in the current control cycle; i4) When PTUI > PYTUI, the current phase shifting group is completely de-energized, and another group is selected for phase shifting: then based on PTUI and PYTUI+ P h The size relationship determines whether to proceed to step i5 or step i6). i5) When PTUI ≤ PYTUI + P h At that time, for PYTUI+ P h -PTUI performs a table lookup to determine the phase shift angle that the new phase shift group needs to be adjusted to in the current control cycle, and completes the energy dissipation process; i6) When PTUI > PYTUI+ P h When the current phase shifting group has completely de-phased, another group is selected for phase shifting: when PTUI≤PYTUI+2· P h At that time, for PYTUI+2· P h -PTUI performs a table lookup to determine the phase shift angle that the new phase shift group needs to be adjusted to in the current control cycle; Similarly, when the newly selected phase shift group is the nth group, PTUI ≤ PYTUI + n· P h At that time, for PYTUI+n· P h -PTUI performs a table lookup to determine the phase shift angle that the new phase shift group needs to be adjusted to in the current control cycle; This process continues until all energy consumption is eliminated.

[0061] After adopting the above scheme, the switching method of the large-capacity energy-consuming group combined with phase shifting designed in this invention can, on the one hand, better make the input energy-consuming capacity close to the power surplus capacity, and avoid the frequent switching phenomenon caused by excessive DC voltage drop due to excessive switching. On the other hand, when the energy-consuming group is withdrawn after the fault ends, the withdrawal speed can be controlled by phase shifting to reduce the system impact caused by the withdrawal of a single large-capacity energy-consuming group.

[0062] Those skilled in the art will understand that embodiments of the present invention can be provided as methods, systems, or computer program products. Therefore, the present invention can take the form of a completely hardware embodiment, a completely software embodiment, or an embodiment combining software and hardware aspects. Furthermore, the present invention can 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. The solutions in the embodiments of the present invention can be implemented using various computer languages, such as the object-oriented programming language Java and the interpreted scripting language JavaScript.

[0063] This invention is described with reference to flowchart illustrations and / or block diagrams of methods, apparatus (systems), and computer program products according to embodiments of the invention. It will be understood that each block of the flowchart illustrations and / or block diagrams, and combinations of blocks in the flowchart illustrations and / or block diagrams, can be implemented by computer program instructions. These computer program instructions can be provided to a processor of a general-purpose computer, special-purpose computer, embedded processor, or other programmable data processing apparatus to produce a machine, such that the instructions, which execute via the processor of the computer or other programmable data processing apparatus, generate instructions for implementing the flowchart illustrations and / or block diagrams. Figure 1 One or more processes and / or boxes Figure 1 A device that provides the functions specified in one or more boxes.

[0064] These computer program instructions may also be stored in a computer-readable storage medium that can direct a computer or other programmable data processing device to function in a particular manner, such that the instructions stored in the computer-readable storage medium produce an article of manufacture including instruction means, which are implemented in a process Figure 1 One or more processes and / or boxes Figure 1The function specified in one or more boxes.

[0065] These computer program instructions may also be loaded onto a computer or other programmable data processing equipment to cause a series of operational steps to be performed on the computer or other programmable equipment to produce a computer-implemented process, thereby providing instructions that execute on the computer or other programmable equipment for implementing the process. Figure 1 One or more processes and / or boxes Figure 1 The steps of the function specified in one or more boxes.

[0066] Although preferred embodiments of the invention have been described, those skilled in the art, upon learning the basic inventive concept, can make other changes and modifications to these embodiments. Therefore, the appended claims are intended to be interpreted as including both the preferred embodiments and all changes and modifications falling within the scope of the invention.

[0067] Obviously, those skilled in the art can make various modifications and variations to this invention without departing from its spirit and scope. Therefore, if these modifications and variations fall within the scope of the claims of this invention and their equivalents, this invention also intends to include these modifications and variations.

Claims

1. A method for configuring AC energy consumption with equal capacity, characterized in that: include, Obtain the total AC power consumption capacity to be configured; the total AC power consumption capacity is sufficient to reliably suppress the surplus power of the flexible DC system when all are in operation; The total AC energy consumption capacity is allocated according to the rated AC voltage level and equipment parameters to determine the total number of AC energy consumption branches and the capacity of each AC energy consumption branch. Configure a set of redundant AC power consumption branches; the capacity of the redundant AC power consumption branches is the same as that of the AC power consumption branches. The operating state of the simulated power system is used as the standard that the AC energy consumption can absorb all the surplus power when the AC voltage drops to its maximum, and the resistance of each AC energy consumption branch is determined.

2. The configuration method as described in claim 1, characterized in that: The AC energy consumption configuration is located at the sending-end new energy station. Each AC energy consumption branch is composed of a series connection of a delta-connected resistor and an anti-parallel thyristor. The parameters of the resistor and anti-parallel thyristor connected to the three delta-connected circuits are exactly the same.

3. The configuration method as described in claim 1, characterized in that: Obtain the total AC power consumption capacity that needs to be configured. include, Obtain the surplus power P that the AC power grid can absorb gx ; According to the AC power grid, the surplus power P can be absorbed. gx The required total AC power consumption capacity PMAX = P mz -P gx , where P mz This refers to the rated conveying capacity of the flexible straight conveyor.

4. The configuration method as described in claim 1, characterized in that: The total AC power consumption capacity is allocated according to the rated AC voltage level and equipment parameters, determining the total number of AC power consumption branches and the capacity of each AC power consumption branch, including... Taking into account the rated AC voltage level of the secondary side of the energy-consuming transformer, the current withstand capability of the thyristors switching the AC energy-consuming branches, the short-time overload capacity of the energy-consuming transformer, and the rated capacity of the flexible DC system, the capacity P of each group of AC energy-consuming branches is determined. h The number of AC power dissipation branch groups that can be connected to each power dissipation transformer, N h Then the total number of AC power-consuming branches is N. h *k, where k is the number of energy-consuming transformers, such that the product of the capacity of each AC energy-consuming branch and the total number of AC energy-consuming branches is equal to the total AC energy-consuming capacity.

5. The configuration method as described in claim 1, characterized in that: The operating conditions of the simulated power system are used as a standard to determine the resistance of each AC energy-consuming branch when the AC voltage drops to its maximum, so that the AC energy consumption can absorb all the surplus power. include, Construct a power system simulation model; The simulation model operates at full power, with all AC power-consuming branches engaged, to obtain the power consumed by a single AC power-consuming branch. Adjust the resistance value of the AC power consumption branch so that the capacity of a single AC power consumption branch reaches the capacity of each AC power consumption branch determined above. The resistance value at this time is the required resistance value of the AC power consumption branch.

6. An equal-capacity AC energy dissipation configuration device, characterized in that: include, The AC total energy consumption capacity acquisition module is configured to acquire the total AC energy consumption capacity to be configured; the total AC energy consumption capacity is sufficient to reliably suppress the surplus power of the flexible DC system when all components are in operation; The AC power consumption branch total number and capacity allocation module is configured to allocate the total AC power consumption capacity according to the rated AC voltage level and equipment parameters, and determine the total number of AC power consumption branches and the capacity of each AC power consumption branch. The redundancy group configuration module is configured to configure a group of redundant AC power consumption branches; the redundant AC power consumption branches have the same capacity as the AC power consumption branches; and, The AC energy consumption branch resistance configuration module is configured to simulate the operating state of the power system. The standard is that the AC energy consumption can absorb all the surplus power when the AC voltage drops to its maximum, and the resistance of each AC energy consumption branch is determined.

7. The configuration device as described in claim 6, characterized in that: The AC energy consumption configuration is located at the sending-end new energy station. Each AC energy consumption branch is composed of a series connection of a delta-connected resistor and an anti-parallel thyristor. The parameters of the resistor and anti-parallel thyristor connected to the three delta-connected circuits are exactly the same.

8. The configuration device as described in claim 6, characterized in that: The AC power consumption total capacity acquisition module obtains the total AC power consumption capacity that needs to be configured. include, Obtain the surplus power P that the AC power grid can absorb gx ; According to the AC power grid, the surplus power P can be absorbed. gx The required total AC power consumption capacity PMAX = P mz -P gx , where P mz This refers to the rated conveying capacity of the flexible straight conveyor.

9. The configuration device as claimed in claim 6, characterized in that: The AC power consumption branch total number and capacity allocation module allocates the total AC power consumption capacity according to the rated AC voltage level and equipment parameters, determining the total number of AC power consumption branches and the capacity of each AC power consumption branch, including: Taking into account the rated AC voltage level of the secondary side of the energy-consuming transformer, the current withstand capability of the thyristors switching the AC energy-consuming branches, the short-time overload capacity of the energy-consuming transformer, and the rated capacity of the flexible DC system, the capacity P of each group of AC energy-consuming branches is determined. h The number of AC power dissipation branch groups that can be connected to each power dissipation transformer, N h Then the total number of AC power-consuming branches is N. h *k, where k is the number of energy-consuming transformers, such that the product of the capacity of each AC energy-consuming branch and the total number of AC energy-consuming branches is equal to the total AC energy-consuming capacity.

10. The configuration device as claimed in claim 6, characterized in that: The AC energy dissipation branch resistance configuration module simulates the power system's operating state. It determines the resistance of each AC energy dissipation branch based on the standard that the AC energy dissipation can absorb all surplus power when the AC voltage drops to its maximum. include, Construct a power system simulation model; The simulation model operates at full power, with all AC power-consuming branches engaged, to obtain the power consumed by a single AC power-consuming branch. Adjust the resistance value of the AC power consumption branch so that the capacity of a single AC power consumption branch reaches the capacity of each AC power consumption branch determined above. The resistance value at this time is the required resistance value of the AC power consumption branch.

11. A switching method for AC power consumption, characterized in that: include, The number of AC power consumption branches to be put into operation and the initial phase shift angle of the phase shift switching group are determined based on the surplus power, so that the total capacity of the AC power consumption branches and the power surplus capacity are within a set range. Among them, the AC power consumption branches use anti-parallel thyristors to switch the resistors. The switching methods include overall switching without trigger angle and phase shift switching with trigger angle, and only one group is allowed to perform phase shift switching at the same time. Based on changes in electrical quantities, the AC energy consumption input capacity is adjusted by phase shifting. When disconnecting AC energy-consuming branches, each group sequentially switches phases to disconnect according to power system impact requirements or coordination with power stabilization and control switching requirements.

12. The cutting method as described in claim 11, characterized in that: The number of groups of AC energy-consuming branches to be connected to the overall system is determined based on the surplus power, including: The total number of input groups N is determined by dividing the surplus power by the floor function of the single AC power-consuming branch capacity. Z , ， Where PY is the surplus power, P h This refers to the capacity of a single AC power consumption branch. The method for obtaining surplus power is as follows: When power is consumed due to overvoltage at the sending end, the surplus power is either the operating power of the flexible DC system or calculated based on the overvoltage level at the sending end. When an AC fault occurs at the sending-end converter station, the surplus power is equal to the total operating power of the flexible DC system. When the sending-end converter is locked, the surplus power is the total power of the locked converters in the flexible DC system, i.e., the single-valve operating power when a single valve is locked; the single-pole operating power when a single pole is locked; and the total operating power when a double pole is locked. When a DC line fault occurs, the surplus power is the operating power of the faulty pole. That is, when a single-pole fault occurs, it is the operating power of the faulty pole; when a double-pole fault occurs, it is the total operating power.

13. The cutting method as described in claim 11, characterized in that: The initial phase shift angle of the phase-shifting switch group is determined based on the surplus power, including: Based on the surplus power, the remaining surplus power is obtained. Where PY is the surplus power, P h For the capacity of a single AC power consumption branch, N Z This refers to the total number of groups involved. Based on the remaining surplus power, the corresponding firing angle is obtained by looking up a table, which is the initial phase shift angle of the phase-shifting switching group; wherein, the two-dimensional table required for the lookup is obtained according to the following method. The surplus power of a single AC energy-consuming branch was obtained by simulation at different firing angles. The data of firing angle and surplus power of each group were fitted to obtain a two-dimensional table of firing angle and surplus power of a single AC energy-consuming branch.

14. The cutting method as described in claim 11, characterized in that: The overall casting and switching methods without trigger angle include, The AC power dissipation branch, based on the received unlock signal, immediately triggers the thyristor in the anti-parallel thyristor that is under positive voltage at the unlock moment; after unlocking, it triggers the thyristor that is under positive voltage after the zero crossing point, and the forward and reverse thyristor trigger pulses are 180° out of phase after unlocking. Phase-shifting switching methods with trigger angles include, The AC power dissipation branch, upon receiving the unlock signal, immediately triggers the thyristor in the anti-parallel thyristor that is under positive voltage at the unlock moment; after unlocking, a trigger pulse with a trigger angle is applied to the thyristor under positive voltage after the zero-crossing point, and the trigger pulses of the forward and reverse thyristors are 180° out of phase after unlocking.

15. The cutting method as described in claim 14, characterized in that: Determine the zero-crossing point using the following method. Detect the zero-crossing point of the main grid AC voltage, and calculate the zero-crossing point of the energy-consuming resistor side of the energy-consuming transformer according to the wiring method of the AC energy-consuming branch transformer; Determine whether the device is under positive pressure after crossing zero using the following method. The AC voltage of the main grid is detected, and the AC voltage on the energy-consuming resistor side of the energy-consuming transformer is calculated according to the wiring method of the AC energy-consuming branch transformer, so as to determine whether it is subjected to positive voltage after the zero point.

16. The cutting method as described in claim 11, characterized in that: Based on changes in electrical quantities, the AC energy consumption input capacity is adjusted through phase shifting, including: The phase shift angle Δα is obtained by applying PI control to the DC voltage at the sending end and the setpoint of the energy dissipation voltage for switching on and off: When the phase shift angle Δα is negative, the trigger angle of the first phase shift group is changed from α to α-|Δα|; when the trigger angle of the phase shift group is reduced to zero, i.e., α-|Δα|=0, the second group is phase shifted with a phase shift angle of 180°-(|Δα|-α); when the trigger angle of the second group is reduced to zero, the third group is phase shifted with a phase shift angle of 180°-(|Δα|-α-180°); and so on, with subsequent phase shift angles being 180°-(|Δα|-α-n·180°), where n is the number of phase shift groups, until the phase shift angle Δα becomes positive and is reset to zero; When the phase shift angle Δα is positive, the trigger angle of the first phase shift group is changed from α to α+Δα; when the trigger angle of the phase shift group is fully added, i.e., α+Δα=180°, the second group is phase shifted, and the phase shift angle is Δα-(180°-α); when the trigger angle of the second group is fully added, the third group is phase shifted, and the phase shift angle is Δα-(180°+180°-α); and so on, the subsequent phase shift angle is Δα-(n·180°-α), where n is the number of phase shift groups, until the phase shift angle Δα becomes negative and is reset to zero; The energy consumption voltage setting for the supplementary switching is switched according to the overvoltage level. When the DC voltage at the sending end is greater than the energy consumption setting, the energy consumption voltage setting for the supplementary switching is equal to the energy consumption setting. When the DC voltage at the sending end is less than the energy consumption setting, the energy consumption voltage setting for the supplementary switching is equal to the energy consumption setting. The energy consumption setting is greater than the energy consumption setting, and the energy consumption setting is greater than the overvoltage setting when the energy consumption is applied during an overvoltage at the sending end.

17. The cutting method as described in claim 11, characterized in that: When disconnecting from the AC power-consuming branch, each group sequentially switches phases, including: Determine the total power PTUI that needs to be withdrawn in the current control cycle based on the required rate of energy consumption cut-off; obtain the power PYTUI consumed by the currently engaged phase shifter group; Determine the phase shift angle based on the relationship between PTUI and PYTUI. When PTUI≤PYTUI, the phase shift angle that the phase shift group needs to be adjusted to in the current control cycle is determined according to PYTUI-PTUI; When PTUI > PYTUI, the current phase shift group is completely de-shifted. Then, based on PTUI and PYTUI + P... h A set of relationships is selected for phase shifting. When PTUI≤PYTUI+P h At that time, according to PYTUI+P h -PTUI determines the phase shift angle that the new phase shift group needs to be adjusted to in the current control cycle; When PTUI > PYTUI + P h When the current phase shifting group has completely de-phased, another group is selected for phase shifting: when PTUI≤PYTUI+2·P h At that time, for PYTUI+2·P h -PTUI performs a table lookup to determine the phase shift angle that the new phase shift group needs to be adjusted to in the current control cycle; Similarly, when the newly selected phase shift group is the nth group, PTUI≤PYTUI+n·P h At that time, for PYTUI+n·P h -PTUI performs a table lookup to determine the phase shift angle that the new phase shift group needs to be adjusted to in the current control cycle; This process continues until all energy consumption is eliminated.

18. An AC power-dissipating switching device, characterized in that: include, The switching module is configured to determine the number of AC power consumption branches to be switched on and the initial phase shift angle of the phase-shifting switching group based on the surplus power, so that the total capacity of the switched AC power consumption branches and the surplus power capacity are within a set range. The AC power consumption branches use anti-parallel thyristors as switching resistors. The switching methods include overall switching without trigger angle and phase-shifting switching with trigger angle, and only one group is allowed to perform phase-shifting switching at the same time. The capacity adjustment module is configured to adjust the AC energy consumption capacity by phase shifting according to changes in electrical quantities; and, When the energy dissipation module is configured to exit the AC energy dissipation branch, each group will sequentially shift phases to disconnect according to the power system impact requirements or the need to coordinate with the power stabilization and control switch.

19. The cutting device as described in claim 18, characterized in that: The switching module determines the total number of AC power-consuming branches to be switched on based on the surplus power, including: The total number of input groups N is determined by dividing the surplus power by the floor function of the single AC power-consuming branch capacity. Z , ， Where PY is the surplus power, P h This refers to the capacity of a single AC power consumption branch. The method for obtaining surplus power is as follows: When power is consumed due to overvoltage at the sending end, the surplus power is either the operating power of the flexible DC system or calculated based on the overvoltage level at the sending end. When an AC fault occurs at the sending-end converter station, the surplus power is equal to the total operating power of the flexible DC system. When the sending-end converter is locked, the surplus power is the total power of the locked converters in the flexible DC system, i.e., the single-valve operating power when a single valve is locked; the single-pole operating power when a single pole is locked; and the total operating power when a double pole is locked. When a DC line fault occurs, the surplus power is the operating power of the faulty pole. That is, when a single-pole fault occurs, it is the operating power of the faulty pole; when a double-pole fault occurs, it is the total operating power.

20. The cutting device as described in claim 18, characterized in that: The switching module determines the initial phase shift angle of the phase-shifting switching group based on the surplus power, including: Based on the surplus power, the remaining surplus power is obtained. Where PY is the surplus power, P h For the capacity of a single AC power consumption branch, N Z This refers to the total number of groups involved. Based on the remaining surplus power, the corresponding firing angle is obtained by looking up a table, which is the initial phase shift angle of the phase-shifting switching group; wherein, the two-dimensional table required for the lookup is obtained according to the following method. The surplus power of a single AC energy-consuming branch was obtained by simulation at different firing angles. The data of firing angle and surplus power of each group were fitted to obtain a two-dimensional table of firing angle and surplus power of a single AC energy-consuming branch.

21. The cutting device as described in claim 18, characterized in that: The overall casting and switching methods without trigger angle include, The AC power dissipation branch, based on the received unlock signal, immediately triggers the thyristor in the anti-parallel thyristor that is under positive voltage at the unlock moment; after unlocking, it triggers the thyristor that is under positive voltage after the zero crossing point, and the forward and reverse thyristor trigger pulses are 180° out of phase after unlocking. Phase-shifting switching methods with trigger angles include, The AC power dissipation branch, upon receiving the unlock signal, immediately triggers the thyristor in the anti-parallel thyristor that is under positive voltage at the unlock moment; after unlocking, a trigger pulse with a trigger angle is applied to the thyristor under positive voltage after the zero-crossing point, and the trigger pulses of the forward and reverse thyristors are 180° out of phase after unlocking.

22. The cutting device as described in claim 21, characterized in that: Determine the zero-crossing point using the following method. Detect the zero-crossing point of the main grid AC voltage, and calculate the zero-crossing point of the energy-consuming resistor side of the energy-consuming transformer according to the wiring method of the AC energy-consuming branch transformer; Determine whether the device is under positive pressure after crossing zero using the following method. The AC voltage of the main grid is detected, and the AC voltage on the energy-consuming resistor side of the energy-consuming transformer is calculated according to the wiring method of the AC energy-consuming branch transformer, so as to determine whether it is subjected to positive voltage after the zero point.

23. The cutting device as described in claim 18, characterized in that: The capacity adjustment module adjusts the AC power consumption capacity based on changes in electrical quantities through phase shifting, including: The phase shift angle Δα is obtained by applying PI control to the DC voltage at the sending end and the setpoint of the energy dissipation voltage for switching on and off: When the phase shift angle Δα is negative, the trigger angle of the first phase shift group is changed from α to α-|Δα|; when the trigger angle of the phase shift group is reduced to zero, i.e., α-|Δα|=0, the second group is phase shifted with a phase shift angle of 180°-(|Δα|-α); when the trigger angle of the second group is reduced to zero, the third group is phase shifted with a phase shift angle of 180°-(|Δα|-α-180°); and so on, with subsequent phase shift angles being 180°-(|Δα|-α-n·180°), where n is the number of phase shift groups, until the phase shift angle Δα becomes positive and is reset to zero; When the phase shift angle Δα is positive, the trigger angle of the first phase shift group is changed from α to α+Δα; when the trigger angle of the phase shift group is fully added, i.e., α+Δα=180°, the second group is phase shifted, and the phase shift angle is Δα-(180°-α); when the trigger angle of the second group is fully added, the third group is phase shifted, and the phase shift angle is Δα-(180°+180°-α); and so on, the subsequent phase shift angle is Δα-(n·180°-α), where n is the number of phase shift groups, until the phase shift angle Δα becomes negative and is reset to zero; The energy consumption voltage setting for the supplementary switching is switched according to the overvoltage level. When the DC voltage at the sending end is greater than the energy consumption setting, the energy consumption voltage setting for the supplementary switching is equal to the energy consumption setting. When the DC voltage at the sending end is less than the energy consumption setting, the energy consumption voltage setting for the supplementary switching is equal to the energy consumption setting. The energy consumption setting is greater than the energy consumption setting, and the energy consumption setting is greater than the overvoltage setting when the energy consumption is applied during an overvoltage at the sending end.

24. The cutting device as described in claim 18, characterized in that: When the de-consumption module exits the AC power consumption branch, each group sequentially switches phases, including: Determine the total power PTUI that needs to be withdrawn in the current control cycle based on the required rate of energy consumption cut-off; obtain the power PYTUI consumed by the currently engaged phase shifter group; Determine the phase shift angle based on the relationship between PTUI and PYTUI. When PTUI≤PYTUI, the phase shift angle that the phase shift group needs to be adjusted to in the current control cycle is determined according to PYTUI-PTUI; When PTUI > PYTUI, the current phase shift group is completely de-shifted. Then, based on PTUI and PYTUI + P... h A set of relationships is selected for phase shifting. When PTUI≤PYTUI+P h At that time, according to PYTUI+P h -PTUI determines the phase shift angle that the new phase shift group needs to be adjusted to in the current control cycle; When PTUI > PYTUI + P h When the current phase shifting group has completely de-phased, another group is selected for phase shifting: when PTUI≤PYTUI+2·P h At that time, for PYTUI+2·P h -PTUI performs a table lookup to determine the phase shift angle that the new phase shift group needs to be adjusted to in the current control cycle; Similarly, when the newly selected phase shift group is the nth group, PTUI≤PYTUI+n·P h At that time, for PYTUI+n·P h -PTUI performs a table lookup to determine the phase shift angle that the new phase shift group needs to be adjusted to in the current control cycle; This process continues until all energy consumption is eliminated.

25. A computer device comprising a memory, a processor, and a computer program stored in the memory and executable on the processor; characterized in that: When the processor executes the computer program, it implements the steps of the equal-capacity AC power consumption configuration method as described in any one of claims 1 to 5 or the AC power consumption switching method as described in any one of claims 6 to 12.

26. A computer-readable storage medium storing a computer program; characterized in that: When the computer program is executed by the processor, it implements the steps of the equal-capacity AC power consumption configuration method as described in any one of claims 1 to 5 or the AC power consumption switching method as described in any one of claims 6 to 12.

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