Power grid commutation converter inverter station steady-state commutation voltage control method and system based on IGCT

Abstract

The invention discloses a steady-state commutation voltage control method and system for a power grid commutation converter inverter station based on IGCT, and the method comprises the steps: 1, detecting the parameter variable quantity of a power grid commutation converter DC power transmission system based on an IGCT device in a set sampling period, and inputting an additional angle controller when the variable quantity meets a preset condition; step 2, superposing the additional angle controller to a fixed turn-off angle controller of an inverter station converter control system, and controlling a steady-state commutation voltage by adjusting a turn-off angle control output value; 3, when it is detected that the controller meets an exit condition, the additional angle controller is exited. According to the method, the active turn-off capability of the converter valve in the IGCT-based power grid commutation converter and the flexible and adjustable characteristic of the turn-off angle instruction value of the inverter station are considered, and the control precision of the AC voltage of the converter station during the steady-state operation period is improved based on the dynamic adjustment and control of the turn-off angle of the converter; and frequent switching of the filter caused by alternating-current commutation voltage fluctuation during steady-state operation of the direct-current system is avoided.

Description

Technical Field

[0001] The present invention belongs to the technical field of high voltage direct current transmission systems, and more specifically, relates to a method and system for controlling steady-state commutation voltage of an inverter station of a power grid commutation converter based on IGCT. Background Art

[0002] High-voltage direct current transmission mainly uses LCC (Line Commutated Converter) based on half-controlled thyristor devices. Due to the inherent characteristics of thyristor devices, it is difficult to effectively avoid the risk of DC commutation failure through existing conventional methods. In contrast, IGCT (Integrated Gate-Commutated Thyristor) is a fully controlled device with the advantages of high withstand voltage, large current, low conduction voltage drop, high reliability and low manufacturing cost. Its low switching frequency operation characteristics are well matched with LCC commutation technology. Building LCC converter valves based on IGCT devices can effectively avoid commutation failure problems and their impact on the power grid.

[0003] The AC commutation voltage of the converter station fluctuates due to the influence of the AC system. In order to avoid the AC commutation voltage exceeding the limit, the DC transmission electric control system is equipped with reactive power control functions, including AC overvoltage control, maximum / minimum voltage limit, reactive power exchange control / voltage control, etc. The above AC voltage control controls the voltage to the target value through AC filter switching. Since the filter control is a step-type switching control and there is a large control delay, it is impossible to achieve the purpose of accurate AC voltage control.

[0004] The steady-state commutation voltage control method used in the prior art is: in order to avoid AC commutation voltage exceeding the limit, the DC transmission electric control system is equipped with reactive power control functions, including AC overvoltage control, maximum / minimum voltage limit, reactive power exchange control / voltage control, etc. The technical problems include: the above AC voltage control controls the voltage to the target value through AC filter switching, and since the filter control adjustment step is large and there is a large control delay, the fast and accurate control goal of steady-state commutation cannot be achieved. Summary of the invention

[0005] In order to solve the deficiencies in the prior art, the present invention provides a steady-state commutation voltage control method for an inverter station of a grid-commutated converter based on IGCT, which utilizes the fast reverse recovery capability of the IGCT device and the fast angle adjustment characteristics of the converter to achieve precise control of the steady-state commutation voltage of the inverter station of a DC transmission system of a grid-commutated converter based on IGCT.

[0006] The present invention adopts the following technical solution.

[0007] A method for controlling steady-state commutation voltage of an inverter station of a power grid commutation converter based on IGCT comprises the following steps:

[0008] Step 1, detecting a parameter change of a grid-commutated converter DC transmission system based on an IGCT device within a set sampling period, and when the change meets a preset condition, putting an additional angle controller into operation;

[0009] Step 2, superimposing the additional angle controller to the fixed cut-off angle controller of the inverter station converter control system, and controlling the steady-state commutation voltage by adjusting the cut-off angle control output value;

[0010] Step 3: When it is detected that the controller meets the exit condition, exit the additional angle controller.

[0011] Preferably, in step 1, the parameter variation includes:

[0012] The IGCT-based grid-commutated converter DC transmission system detects the change in active power transmitted and the change in three-phase AC commutation voltage on the inverter side within a set sampling period.

[0013] Preferably, the preset conditions in step 1 include:

[0014] The grid-commutated converter DC transmission system based on IGCT devices transmits active power variation less than a set value within a set sampling period, and the three-phase AC commutation voltage variation on the inverter side exceeds a set control dead zone.

[0015] Preferably, the sampling period is 3 seconds and the set value is 20 MW.

[0016] Preferably, in step 2, the additional angle controller is connected to the fixed shut-off angle controller, and the additional angle controller includes: a throw-in / out control module and an accessory angle output module;

[0017] Among them, the additional angle output module obtains the shutdown angle adjustment amount after processing the difference between the three-phase AC voltage effective value measurement value and the command value through the PI controller, and uses the AC voltage as the input of the PI controller and the additional angle as the output of the PI controller; the on / off control module performs the on / off control of the additional angle controller according to step 1.

[0018] Preferably, the connection between the additional angle controller and the fixed turn-off angle controller is as follows: the input end of the constant current controller in the IGCT-based grid commutation converter control system is connected to the output end of the additional angle controller.

[0019] Preferably, the additional angle output module obtains the turn-off angle adjustment value Δγ according to the difference between the three-phase AC voltage effective value measurement value and the command value through the PI control link;

[0020] The input and output control module controls the input and output of the additional angle controller according to the preset conditions in step 1.

[0021] Preferably, the cut-off angle control output value γ′ of the fixed cut-off angle controller satisfies:

[0022] y′=γ+Δy

[0023] Among them, γ represents the shutdown angle command, and Δγ represents the shutdown angle adjustment amount;

[0024] After throwing in the additional angle controller:

[0025] If the three-phase AC voltage component on the inverter side increases, the cut-off angle control output value γ′ of the fixed cut-off angle controller will increase, increasing the reactive power absorbed by the converter, thereby reducing the AC voltage;

[0026] If the three-phase AC voltage component on the inverter side decreases, the turn-off angle control output value γ′ of the fixed turn-off angle controller will decrease, reducing the reactive power absorbed by the converter, thereby increasing the AC voltage.

[0027] Preferably, the adjusted turn-off angle control output value γ′ of the fixed turn-off angle controller satisfies γ′≥2.

[0028] Preferably, in step 3, when it is detected that the change in the three-phase AC commutation voltage on the inverter side is less than a set control dead zone, the additional angle controller is exited.

[0029] The present invention also provides a steady-state commutation voltage control system for a grid commutation converter inverter station based on IGCT, which is used to implement the steady-state commutation voltage control method for a grid commutation converter inverter station based on IGCT. The system comprises:

[0030] A detection module, used to detect the parameter change amount of the grid commutation converter DC transmission system based on the IGCT device within a set sampling period;

[0031] A condition judgment module is used to judge whether the input or output conditions of the additional angle controller are met according to the parameter change amount obtained by the detection module;

[0032] The control module is used to control the input and output of the additional angle controller, and to control the steady-state commutation voltage by adjusting the turn-off angle control output value.

[0033] The present invention also provides a terminal, including a processor and a storage medium;

[0034] The storage medium is used to store instructions;

[0035] The processor is used to operate according to the instructions to execute the steps of the IGCT-based grid-commutated converter inverter station steady-state commutation voltage control method.

[0036] The present invention also provides a computer-readable storage medium having a computer program stored thereon, which, when executed by a processor, implements the steps of the steady-state commutation voltage control method of the IGCT-based grid commutation converter inverter station.

[0037] The beneficial effect of the present invention lies in that, compared with the prior art, the present invention constructs an additional angle controller, sets the conditions for the additional angle controller to be put into and out of the DC transmission system, dynamically adjusts the turn-off angle according to the change of the commutation voltage through the additional angle controller, takes the AC voltage as the input of the PI controller and the additional angle as the output of the PI controller, thereby realizing the control of reactive power and AC voltage, and can give full play to the fast reverse recovery capability of the IGCT device. By detecting the change of the AC commutation voltage amplitude of the inverter station, the turn-off angle is dynamically adjusted, and the steady-state commutation voltage control accuracy of the DC transmission system of the grid commutation converter based on IGCT is improved. BRIEF DESCRIPTION OF THE DRAWINGS

[0038] Figure 1 It is a flow chart of a steady-state commutation voltage control method of an IGCT-based grid commutation converter inverter station in the present invention;

[0039] Figure 2 is a structural block diagram of the additional angle controller of the present invention;

[0040] Figure 3 It is a circuit structure block diagram of the additional angle controller and the IGCT-based grid commutation converter DC transmission system of the present invention;

[0041] Figure 4 It is the inverter station commutation voltage waveform under the conventional voltage control strategy;

[0042] Figure 5 is the inverter station commutation voltage waveform under the proposed voltage control strategy;

[0043] Figure 6 It is a schematic structural diagram of a steady-state commutation voltage control system of an IGCT-based grid commutation converter inverter station in the present invention. DETAILED DESCRIPTION

[0044] In order to make the purpose, technical scheme and advantages of the present invention clearer, the technical scheme of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. The embodiments described in this application are only part of the embodiments of the present invention, not all of them. Based on the spirit of the present invention, other embodiments obtained by ordinary technicians in this field without creative work are all within the scope of protection of the present invention.

[0045] like Figure 1 As shown, the present invention proposes a steady-state commutation voltage control method for a grid commutation converter inverter station based on IGCT, and the method specifically includes the following steps:

[0046] Step 1, detecting the transmission active power change amount and the inverter side three-phase AC commutation voltage change amount of the IGCT device-based grid-commutated converter (IGCT-LCC) DC transmission system within a set sampling period, and when the transmission active power change amount and the inverter side three-phase AC commutation voltage change amount meet the preset conditions for the additional angle controller to be put into use, the additional angle controller is put into use;

[0047] The topology of the IGCT-based grid-commutated converter is a 12-pulse or 6-pulse bridge, and the commutation device is an IGCT device.

[0048] The transmission active power variation of the IGCT-based grid-commutated converter DC transmission system, the variation of the three-phase AC voltage component on the inverter side, and the zero-sequence voltage component are collected. When it is detected that the transmission active power variation of the IGCT-based grid-commutated converter DC transmission system within a set sampling period is less than a set value and the variation of the three-phase AC commutated voltage on the inverter side exceeds a set control dead zone, an additional angle controller is put into operation in the inverter station of the DC transmission system;

[0049] Among them, the change in DC active power within the set sampling period should be less than the normal power rise and fall rate set by the operator, and the active power change within 3 seconds should not exceed 20MW as the set value.

[0050] Among them, if the change amount of the three-phase AC voltage component on the inverter side is greater than the set value and the zero-sequence voltage component is less than the set value, it means that the change amount of the three-phase AC commutation voltage on the inverter side exceeds the set control dead zone;

[0051] In order to avoid the controller being put into operation due to single-phase or two-phase voltage drops, the three-phase AC commutation voltage on the inverter side is collected for real-time comparison and judgment. If the change in the αβ component of the three-phase AC voltage Δu αβ Greater than the set value Δu αβ_set And the zero-sequence voltage component u0 is less than the set value Δu 0_set The controller is enabled only when the following relationship is satisfied:

[0052]

[0053] Among them, u a 、u b 、u c are the three-phase voltages on the AC side; u α and u β The two corresponding voltage components on the αβ plane are obtained through abc / αβ transformation.

[0054] The control dead zone of commutation voltage change is mainly considered to avoid frequent action of the controller and to reduce the AC commutation voltage fluctuation. At the same time, it should be smaller than the voltage control dead zone value of the fixed voltage control of the converter station.

[0055] If the change in the three-phase AC commutation voltage on the inverter side is less than the set control dead zone, the additional angle controller will exit.

[0056] Step 2: superimpose the additional angle controller on the fixed shut-off angle controller of the inverter control system of the inverter station for control.

[0057] Among them, Figure 4 As shown, the additional angle controller is connected to the fixed cut-off angle controller. The structure of the additional angle controller is as follows: Figure 2 As shown, the additional angle controller includes the following elements: a throw-in / out control module and an accessory angle output module; wherein the additional angle output module obtains a turn-off angle adjustment value according to a difference between a three-phase AC voltage effective value measurement value and a command value through a PI controller; and the throw-in / out control module performs throw-in / out according to the conditions in step 1.

[0058] The connection between the additional angle controller and the fixed cut-off angle controller is as follows: the output end of the additional angle controller is superimposed on the input end of the fixed cut-off angle controller.

[0059] The cut-off angle control output value γ′ of the fixed cut-off angle controller satisfies:

[0060] γ′=γ+Δγ

[0061] Among them, y represents the shutdown angle command, and Δγ represents the shutdown angle adjustment amount.

[0062] Furthermore, after adding the additional angle controller:

[0063] If the three-phase AC voltage component on the inverter side increases, the cut-off angle control output value γ′ of the fixed cut-off angle controller will increase, increasing the reactive power absorbed by the converter, thereby achieving the purpose of reducing the AC voltage;

[0064] If the three-phase AC voltage component on the inverter side decreases, the cut-off angle control output value γ′ of the fixed cut-off angle controller will decrease, reducing the reactive power absorbed by the converter, thereby achieving the purpose of increasing the AC voltage;

[0065] Furthermore, considering the turn-off recovery time, since the turn-off recovery time of the IGCT device is about 50μs, that is, the minimum turn-off angle is 1°, the turn-off angle control output value γ′ of the adjusted fixed turn-off angle controller should satisfy γ′≥2, such as Figure 4 shown.

[0066] The input of the additional angle controller is the deviation between the effective value of the rated commutation voltage on the inverter side and the measured effective value.

[0067] Step 3: when it is detected that the change in the three-phase AC commutation voltage on the inverter side is less than the set control dead zone, exit the additional angle controller.

[0068] like Figure 6 As shown, the present invention also proposes a steady-state commutation voltage control system for a grid commutation converter inverter station based on IGCT, which is used to implement the above-mentioned steady-state commutation voltage control method for a grid commutation converter inverter station based on IGCT. The system includes:

[0069] A detection module, used to detect the parameter change amount of the grid commutation converter DC transmission system based on the IGCT device within a set sampling period;

[0070] A condition judgment module is used to judge whether the input or output conditions of the additional angle controller are met according to the parameter change amount obtained by the detection module;

[0071] The control module is used to control the input and output of the additional angle controller, and to control the steady-state commutation voltage by adjusting the turn-off angle control output value.

[0072] In order to verify the effect of the present invention in practical applications, the following is a specific simulation verification example of the present invention:

[0073] In order to verify the effectiveness of the steady-state commutation voltage control method of the grid-commutated converter inverter station based on IGCT, a simulation model was built in PSCAD software for verification.

[0074] The implementation process of the control strategy proposed by the present invention is as follows: Figure 1 As shown in the figure, in order to verify the control effect of the control method proposed in the present invention, the conventional thyristor commutator reactive voltage control strategy and the control method proposed in the present invention are selected for simulation comparison. At 5.0s, the simulated inverter side AC voltage fluctuates. The commutation voltage using the reactive voltage control strategy is shown in Figure 4 As shown, the commutation voltage under the control method of the present invention is as follows Figure 5 shown.

[0075] Depend on Figure 4It can be seen that when the commutation voltage of the inverter station changes, the commutation voltage cannot be controlled near the rated value because the conventional DC reactive voltage control threshold is not met.

[0076] Depend on Figure 5 It can be seen that when the control method proposed in the present invention is adopted, the shutdown angle controller can adjust the shutdown angle command according to the change of the commutation voltage, realize the precise control of the reactive power of the converter valve, and significantly reduce the range of change of the steady-state commutation voltage.

[0077] The beneficial effect of the present invention is that, compared with the prior art, the present invention improves the control accuracy of the AC voltage of the converter station during steady-state operation based on the dynamic adjustment control of the converter shut-off angle, thereby avoiding frequent switching of the filter caused by AC commutation voltage fluctuations during steady-state operation of the DC system.

[0078] The present disclosure may be a system, a method and / or a computer program product. The computer program product may include a computer-readable storage medium carrying computer-readable program instructions for causing a processor to implement various aspects of the present disclosure.

[0079] Computer readable storage medium can be a tangible device that can hold and store instructions used by an instruction execution device. Computer readable storage medium can be, for example, but not limited to, an electrical storage device, a magnetic storage device, an optical storage device, an electromagnetic storage device, a semiconductor storage device, or any suitable combination thereof. More specific examples (non-exhaustive lists) of computer readable storage medium include: portable computer disks, hard disks, random access memories (RAM), read-only memories (ROM), erasable programmable read-only memories (EPROM or flash memory), static random access memories (SRAM), portable compact disk read-only memories (CD-ROM), digital versatile disks (DVD), memory sticks, floppy disks, mechanical encoding devices, such as punch cards or convex structures in grooves on which instructions are stored, and any suitable combination thereof. Computer readable storage medium used here is not interpreted as a transient signal itself, such as radio waves or other freely propagating electromagnetic waves, electromagnetic waves propagated by waveguides or other transmission media (e.g., light pulses by optical fiber cables), or electrical signals transmitted by wires.

[0080] The computer-readable program instructions described herein can be downloaded from a computer-readable storage medium to each computing / processing device, or downloaded to an external computer or external storage device via a network, such as the Internet, a local area network, a wide area network, and / or a wireless network. The network can include copper transmission cables, optical fiber transmissions, wireless transmissions, routers, firewalls, switches, gateway computers, and / or edge servers. The network adapter card or network interface in each computing / processing device receives the computer-readable program instructions from the network and forwards the computer-readable program instructions for storage in the computer-readable storage medium in each computing / processing device.

[0081] The computer program instructions for performing the disclosed operation may be assembly instructions, instruction set architecture (ISA) instructions, machine instructions, machine-related instructions, microcode, firmware instructions, state setting data, or source code or object code written in any combination of one or more programming languages, including object-oriented programming languages, such as Smalltalk, C++, etc., and conventional procedural programming languages, such as "C" language or similar programming languages. Computer-readable program instructions may be executed completely on a user's computer, partially on a user's computer, as an independent software package, partially on a user's computer, partially on a remote computer, or completely on a remote computer or server. In the case of a remote computer, the remote computer may be connected to the user's computer via any type of network, including a local area network (LAN) or a wide area network (WAN), or may be connected to an external computer (e.g., using an Internet service provider to connect via the Internet). In some embodiments, an electronic circuit, such as a programmable logic circuit, a field programmable gate array (FPGA), or a programmable logic array (PLA), may be customized by utilizing the state information of the computer-readable program instructions, and the electronic circuit may execute the computer-readable program instructions, thereby realizing various aspects of the disclosed invention.

[0082] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention rather than to limit it. Although the present invention has been described in detail with reference to the above embodiments, ordinary technicians in the relevant field should understand that the specific implementation methods of the present invention can still be modified or replaced by equivalents, and any modifications or equivalent replacements that do not depart from the spirit and scope of the present invention should be covered within the scope of protection of the claims of the present invention.

Claims

1. A method for controlling steady-state commutation voltage of an inverter station of a power grid commutation converter based on IGCT, characterized in that: The following steps are involved: Step 1, detecting a parameter change of a grid-commutated converter DC transmission system based on an IGCT device within a set sampling period, and when the change meets a preset condition, putting an additional angle controller into operation; Step 2, superimposing the additional angle controller to the fixed cut-off angle controller of the inverter station converter control system, and controlling the steady-state commutation voltage by adjusting the cut-off angle control output value; Step 3: When it is detected that the controller meets the exit condition, exit the additional angle controller.

2. The method for controlling steady-state commutation voltage of a converter station of a IGCT-based grid-commutated converter DC transmission system according to claim 1, characterized in that: In step 1, the parameter variation includes: The IGCT-based grid-commutated converter DC transmission system detects the change in active power transmitted and the change in three-phase AC commutation voltage on the inverter side within a set sampling period.

3. The method for controlling steady-state commutation voltage of a converter station of a IGCT-based grid-commutated converter DC transmission system according to claim 2, characterized in that: The preset conditions in step 1 include: The grid-commutated converter DC transmission system based on IGCT devices transmits active power variation less than a set value within a set sampling period, and the three-phase AC commutation voltage variation on the inverter side exceeds a set control dead zone.

4. The method for controlling steady-state commutation voltage of an inverter station of a power grid commutation converter based on IGCT according to claim 3, characterized in that: The sampling period is preferably 3 seconds, and the set value is preferably 20 MW.

5. The method for controlling steady-state commutation voltage of an inverter station of a power grid commutation converter based on IGCT according to claim 1, characterized in that: In step 2, the additional angle controller is connected to the fixed shut-off angle controller, and the additional angle controller includes: a throw-in / out control module and an accessory angle output module; Among them, the additional angle output module obtains the shutdown angle adjustment amount after processing the difference between the three-phase AC voltage effective value measurement value and the command value through the PI controller, and uses the AC voltage as the input of the PI controller and the additional angle as the output of the PI controller; the on / off control module performs the on / off control of the additional angle controller according to step 1.

6. The method for controlling steady-state commutation voltage of an inverter station of a power grid commutation converter based on IGCT according to claim 1, characterized in that: The connection between the additional angle controller and the fixed turn-off angle controller is as follows: the input end of the constant current controller in the IGCT-based grid commutation converter control system is connected to the output end of the additional angle controller.

7. The method for controlling steady-state commutation voltage of an inverter station of a power grid commutation converter based on IGCT according to claim 6, characterized in that: The additional angle output module obtains the turn-off angle adjustment value Δγ according to the difference between the three-phase AC voltage effective value measurement value and the command value through the PI controller; The input and output control module controls the input and output of the additional angle controller according to the preset conditions in step 1.

8. The method for controlling steady-state commutation voltage of an inverter station of a power grid commutation converter based on IGCT according to claim 7, characterized in that: The turn-off angle control output value γ' of the fixed turn-off angle controller satisfies: γ=γ+Δγ Among them, γ represents the shutdown angle command, and Δγ represents the shutdown angle adjustment amount; After throwing in the additional angle controller: If the three-phase AC voltage component on the inverter side increases, the cut-off angle control output value γ' of the fixed cut-off angle controller will increase, increasing the reactive power absorbed by the converter and reducing the AC voltage; If the three-phase AC voltage component on the inverter side decreases, the turn-off angle control output value γ' of the fixed turn-off angle controller will decrease, reducing the reactive power absorbed by the converter and increasing the AC voltage.

9. The method for controlling steady-state commutation voltage of an inverter station of a power grid commutation converter based on IGCT according to claim 8, characterized in that: The adjusted turn-off angle control output value γ' of the fixed turn-off angle controller satisfies γ'≥2.

10. The method for controlling steady-state commutation voltage of an inverter station of a power grid commutation converter based on IGCT according to claim 1, characterized in that: In the step 3, when it is detected that the change in the three-phase AC commutation voltage on the inverter side is less than the set control dead zone, the additional angle controller is exited.

11. A steady-state commutation voltage control system for a grid-commutated converter inverter station based on IGCT, used to implement the steady-state commutation voltage control method for a grid-commutated converter inverter station based on IGCT as claimed in any one of claims 1 to 10, characterized in that: include: A detection module, used to detect the parameter change amount of the grid commutation converter DC transmission system based on the IGCT device within a set sampling period; A condition judgment module is used to judge whether the input or output conditions of the additional angle controller are met according to the parameter change amount obtained by the detection module; The control module is used to control the input and output of the additional angle controller, and to control the steady-state commutation voltage by adjusting the turn-off angle control output value.

12. A terminal comprising a processor and a storage medium; characterized in that: The storage medium is used to store instructions; The processor is configured to operate according to the instructions to execute the steps of the method according to any one of claims 1-10.

13. A computer-readable storage medium having a computer program stored thereon, characterized in that: When the program is executed by a processor, the steps of the method according to any one of claims 1 to 10 are implemented.

Images