AC voltage control method and device based on adaptive PI controller

Abstract

The invention relates to the technical field of direct-current power transmission control, and particularly provides an alternating-current voltage control method and device based on a self-adaptive PI controller. Comprising the steps of determining a coefficient corresponding to a deviation between an actual voltage value of the flexible direct current transmission VSC-HVDC system and a voltage reference value of the flexible direct current transmission VSC-HVDC system based on the deviation between the actual voltage value of the flexible direct current transmission VSC-HVDC system and the voltage reference value of the flexible direct current transmission VSC-HVDC system; and flexible direct current transmission VSC-HVDC flexible direct current transmission VSC-HVDC corrects the alternating current voltage value of the flexible direct current transmission VSC-HVDC system based on a coefficient corresponding to the deviation between the actual voltage value of the flexible direct current transmission VSC-HVDC system and the voltage reference value of the flexible direct current transmission VSC-HVDC system. According to the technical scheme provided by the invention, the integral response speed and the AC voltage deviation are optimized. The method has a remarkable effect on improving the voltage outer loop control response speed based on the three-phase PWM rectifier, and can guide the actual operation of a project.

Description

Technical Field

[0001] The present invention relates to the technical field of direct current transmission control, and in particular to an alternating current voltage control method and device based on an adaptive PI controller. Background Art

[0002] High Voltage Direct Current Transmission (HVDC) systems generally include Line Commutated Converter Based HVDC (LCC-HVDC, also known as traditional DC transmission) and Voltage Source Converter Based HVDC (VSC-HVDC, also known as flexible DC transmission). The voltage source converter type DC transmission system has many technical advantages such as no commutation fault, dynamic reactive power compensation, self-commutation, low harmonic level, and suitable for forming a multi-terminal DC system. Therefore, it is widely used in the fields of transmission and distribution, such as grid interconnection, connection of weak AC systems, island power supply, renewable energy grid connection, urban power grid power supply, etc.

[0003] At present, the flexible direct current transmission VSC-HVDC adopts a dual closed-loop control structure, and the control system of the flexible direct current transmission VSC-HVDC is modeled through the d / q axis decoupling control method. The function of the outer loop controller is to generate the reference value of the current d / q axis, and the inner loop controller realizes the tracking control of the current reference value and generates the reference voltage of the converter.

[0004] The voltage outer loop of the PWM rectifier generally adopts a PI controller. Since the integral coefficient ki is a constant, the integral increment remains unchanged during the entire control process. However, when a voltage drop occurs on the inverter side of the VSC, the power fluctuation of the entire system is large, which will cause a large fluctuation in the DC bus voltage. At this time, the voltage outer loop controller of the PWM rectifier will produce a large system deviation. Because the system requires the integral term, the integral effect should be weakened or even eliminated when the system deviation is large, because at this time, a large deviation in the system output will cause the integral accumulation of the PI operation, causing the control amount to exceed the limit control amount corresponding to the maximum action range that the actuator may allow, causing a large overshoot or even a large oscillation in the system, and unable to quickly restore the controlled amount to the set value. Taking this measure can achieve rapid adjustment and ensure that the system quickly enters a stable state; and when the deviation is small, the integral effect should be strengthened.

[0005] Therefore, further research is still needed on the control of flexible DC transmission systems in special application scenarios to improve the response speed of the system. Summary of the invention

[0006] In order to overcome the above defects, the present invention proposes an AC voltage control method and device based on an adaptive PI controller.

[0007] In a first aspect, an AC voltage control method based on an adaptive PI controller is provided, the AC voltage control method based on an adaptive PI controller comprising:

[0008] Determine a coefficient corresponding to a deviation between the actual voltage value of the flexible direct current transmission VSC-HVDC system and the voltage reference value of the flexible direct current transmission VSC-HVDC system based on a deviation between the actual voltage value of the flexible direct current transmission VSC-HVDC system and the voltage reference value of the flexible direct current transmission VSC-HVDC system;

[0009] The flexible direct current transmission VSC-HVDC flexible direct current transmission VSC-HVDC flexible direct current transmission VSC-HVDC corrects the AC voltage value of the flexible direct current transmission VSC-HVDC system based on a coefficient corresponding to a deviation between an actual voltage value of the flexible direct current transmission VSC-HVDC system and a voltage reference value of the flexible direct current transmission VSC-HVDC system.

[0010] Preferably, the calculation formula for the deviation between the actual voltage value of the flexible direct current transmission VSC-HVDC system and the voltage reference value of the flexible direct current transmission VSC-HVDC system is as follows:

[0011] e(k)=u0-u(k)

[0012] In the above formula, e(k) is the deviation between the actual voltage value of the flexible direct current transmission VSC-HVDC system at the kth moment and the voltage reference value of the flexible direct current transmission VSC-HVDC system, u0 is the voltage reference value of the flexible direct current transmission VSC-HVDC system, and u(k) is the actual voltage value of the flexible direct current transmission VSC-HVDC system at the kth moment.

[0013] Preferably, the calculation formula of the coefficient corresponding to the deviation between the actual voltage value of the flexible direct current transmission VSC-HVDC system and the voltage reference value of the flexible direct current transmission VSC-HVDC system is as follows:

[0014]

[0015] In the above formula, f(e(k)) is the coefficient corresponding to the deviation between the actual voltage value of the flexible direct current transmission VSC-HVDC system at the kth moment and the voltage reference value of the flexible direct current transmission VSC-HVDC system, M is the first integration interval, N is the second integration interval, and e(k) is the deviation between the actual voltage value of the flexible direct current transmission VSC-HVDC system at the kth moment and the voltage reference value of the flexible direct current transmission VSC-HVDC system.

[0016] Further, the first integral interval M is smaller than the second integral interval N.

[0017] Furthermore, the AC voltage value of the flexible direct current transmission VSC-HVDC system is corrected according to the following formula:

[0018]

[0019] In the above formula, u(k) is the correction value of the AC voltage value of the flexible direct current transmission VSC-HVDC system at the kth moment, k p is the proportional coefficient of the PI controller in the VSC-HVDC system, k i is the integral coefficient of the PI controller in the VSC-HVDC system, e(j) is the deviation between the actual voltage value of the VSC-HVDC system and the voltage reference value of the VSC-HVDC system at the jth moment, and T is the integration time constant.

[0020] In a second aspect, an adaptive PI controller is provided, wherein the adaptive PI controller includes a proportional link module and an integral link module respectively connected to an adder.

[0021] Preferably, the mathematical model of the proportional link module is: p e(k), the mathematical model of the integral link module is: Among them, k p is the proportional coefficient of the PI controller in the VSC-HVDC system, k i is the integral coefficient of the PI controller in the flexible direct current transmission VSC-HVDC system, e(j) is the deviation between the actual voltage value of the flexible direct current transmission VSC-HVDC system and the voltage reference value of the flexible direct current transmission VSC-HVDC system at the jth moment, T is the integral time constant, f(e(k)) is the coefficient corresponding to the deviation between the actual voltage value of the flexible direct current transmission VSC-HVDC system and the voltage reference value of the flexible direct current transmission VSC-HVDC system at the kth moment, and e(k) is the deviation between the actual voltage value of the flexible direct current transmission VSC-HVDC system and the voltage reference value of the flexible direct current transmission VSC-HVDC system at the kth moment.

[0022] Preferably, the calculation formula of the coefficient corresponding to the deviation between the actual voltage value of the flexible direct current transmission VSC-HVDC system and the voltage reference value of the flexible direct current transmission VSC-HVDC system is as follows:

[0023]

[0024] In the above formula, M is the first integration interval, and N is the second integration interval.

[0025] Further, the first integral interval M is smaller than the second integral interval N.

[0026] Preferably, the calculation formula for the deviation between the actual voltage value of the flexible direct current transmission VSC-HVDC system and the voltage reference value of the flexible direct current transmission VSC-HVDC system is as follows:

[0027] e(k)=u0-u(k)

[0028] In the above formula, u0 is the voltage reference value of the flexible direct current transmission VSC-HVDC system, and u(k) is the actual voltage value of the flexible direct current transmission VSC-HVDC system at the kth moment.

[0029] In a third aspect, an AC voltage control device based on an adaptive PI controller is provided, wherein the AC voltage control device based on the adaptive PI controller comprises:

[0030] A first determination module is used to determine a coefficient corresponding to a deviation between an actual voltage value of the flexible direct current transmission VSC-HVDC system and a voltage reference value of the flexible direct current transmission VSC-HVDC system based on a deviation between an actual voltage value of the flexible direct current transmission VSC-HVDC system and a voltage reference value of the flexible direct current transmission VSC-HVDC system;

[0031] The second determination module is used to determine the voltage correction value of the flexible direct current transmission VSC-HVDC system based on a coefficient corresponding to a deviation between an actual voltage value of the flexible direct current transmission VSC-HVDC system and a voltage reference value of the flexible direct current transmission VSC-HVDC system.

[0032] Preferably, the calculation formula for the deviation between the actual voltage value of the flexible direct current transmission VSC-HVDC system and the voltage reference value of the flexible direct current transmission VSC-HVDC system is as follows:

[0033] e(k)=u0-u(k)

[0034] In the above formula, e(k) is the deviation between the actual voltage value of the flexible direct current transmission VSC-HVDC system at the kth moment and the voltage reference value of the flexible direct current transmission VSC-HVDC system, u0 is the voltage reference value of the flexible direct current transmission VSC-HVDC system, and u(k) is the actual voltage value of the flexible direct current transmission VSC-HVDC system at the kth moment.

[0035] Preferably, the calculation formula of the coefficient corresponding to the deviation between the actual voltage value of the flexible direct current transmission VSC-HVDC system and the voltage reference value of the flexible direct current transmission VSC-HVDC system is as follows:

[0036]

[0037] In the above formula, f(e(k)) is the coefficient corresponding to the deviation between the actual voltage value of the flexible direct current transmission VSC-HVDC system at the kth moment and the voltage reference value of the flexible direct current transmission VSC-HVDC system, M is the first integration interval, N is the second integration interval, and e(k) is the deviation between the actual voltage value of the flexible direct current transmission VSC-HVDC system at the kth moment and the voltage reference value of the flexible direct current transmission VSC-HVDC system.

[0038] Further, the first integral interval M is smaller than the second integral interval N.

[0039] Furthermore, the AC voltage value of the flexible direct current transmission VSC-HVDC system is corrected according to the following formula:

[0040]

[0041] In the above formula, u(k) is the correction value of the AC voltage value of the flexible direct current transmission VSC-HVDC system at the kth moment, k p is the proportional coefficient of the PI controller in the VSC-HVDC system, k i is the integral coefficient of the PI controller in the VSC-HVDC system, e(j) is the deviation between the actual voltage value of the VSC-HVDC system and the voltage reference value of the VSC-HVDC system at the jth moment, and T is the integration time constant.

[0042] In a fourth aspect, a computer device is provided, comprising: one or more processors;

[0043] The processor is used to store one or more programs;

[0044] When the one or more programs are executed by the one or more processors, the AC voltage control method based on the adaptive PI controller is implemented.

[0045] In a fifth aspect, a computer-readable storage medium is provided, on which a computer program is stored. When the computer program is executed, the AC voltage control method based on the adaptive PI controller is implemented.

[0046] The above one or more technical solutions of the present invention have at least one or more of the following beneficial effects:

[0047] The present invention provides an AC voltage control method and device based on an adaptive PI controller, including: determining a coefficient corresponding to the deviation between the actual voltage value of the flexible direct current transmission VSC-HVDC system and the voltage reference value of the flexible direct current transmission VSC-HVDC system based on the deviation between the actual voltage value of the flexible direct current transmission VSC-HVDC system and the voltage reference value of the flexible direct current transmission VSC-HVDC system; and correcting the AC voltage value of the flexible direct current transmission VSC-HVDC system based on the coefficient corresponding to the deviation between the actual voltage value of the flexible direct current transmission VSC-HVDC system and the voltage reference value of the flexible direct current transmission VSC-HVDC system. The technical solution provided by the present invention optimizes the integral response speed and the AC voltage deviation. It has a significant effect on improving the voltage outer loop control response speed based on the three-phase PWM rectifier and can guide the actual operation of the project.

[0048] Specifically, the voltage outer loop controller is implemented by a PI controller based on adaptive PI controller parameters, and the PI controller integral coefficient is adaptively adjusted with the voltage deviation, which can shorten the response time and reduce the voltage deviation value. BRIEF DESCRIPTION OF THE DRAWINGS

[0049] Figure 1 1 is a schematic flow chart of main steps of an AC voltage control method based on an adaptive PI controller according to an embodiment of the present invention;

[0050] Figure 2 is a main structural block diagram of an adaptive PI controller according to an embodiment of the present invention;

[0051] Figure 3 This is a topological diagram of the interconnection between a 500kV four-terminal flexible DC and a conventional DC according to an embodiment of the present invention;

[0052] Figure 4 is a VSC steady-state operating characteristic curve diagram of an embodiment of the present invention;

[0053] Figure 5 is a comparison diagram of the variable speed integral voltage control results of an embodiment of the present invention;

[0054] Figure 6 It is a main structural block diagram of an AC voltage control device based on an adaptive PI controller according to an embodiment of the present invention. DETAILED DESCRIPTION

[0055] The specific implementation modes of the present invention will be further described in detail below in conjunction with the accompanying drawings.

[0056] In order to make the purpose, technical solution and advantages of the embodiments of the present invention clearer, the technical solution in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0057] As disclosed in the background technology, the high voltage direct current transmission system (HVDC) generally includes line commutated converter based HVDC (LCC-HVDC, also known as traditional DC transmission) and voltage source converter based HVDC (VSC-HVDC, also known as flexible DC transmission). The voltage source converter based DC transmission system has many technical advantages such as no commutation fault, dynamic reactive power compensation, self-commutation, low harmonic level, and suitable for forming a multi-terminal DC system. Therefore, it is widely used in the fields of power transmission and distribution, such as grid interconnection, connection of weak AC systems, island power supply, renewable energy grid connection, urban power grid power supply, etc.

[0058] At present, the flexible direct current transmission VSC-HVDC adopts a dual closed-loop control structure, and the control system of the flexible direct current transmission VSC-HVDC is modeled through the d / q axis decoupling control method. The function of the outer loop controller is to generate the reference value of the current d / q axis, and the inner loop controller realizes the tracking control of the current reference value and generates the reference voltage of the converter.

[0059] The voltage outer loop of the PWM rectifier generally adopts a PI controller. Since the integral coefficient ki is a constant, the integral increment remains unchanged during the entire control process. However, when a voltage drop occurs on the inverter side of the VSC, the power fluctuation of the entire system is large, which will cause a large fluctuation in the DC bus voltage. At this time, the voltage outer loop controller of the PWM rectifier will produce a large system deviation. Because the system requires the integral term, the integral effect should be weakened or even eliminated when the system deviation is large, because at this time, a large deviation in the system output will cause the integral accumulation of the PI operation, causing the control amount to exceed the limit control amount corresponding to the maximum action range that the actuator may allow, causing a large overshoot or even a large oscillation in the system, and unable to quickly restore the controlled amount to the set value. Taking this measure can achieve rapid adjustment and ensure that the system quickly enters a stable state; and when the deviation is small, the integral effect should be strengthened.

[0060] Therefore, further research is still needed on the control of flexible DC transmission systems in special application scenarios to improve the response speed of the system.

[0061] In order to improve the above-mentioned problems, the present invention provides an AC voltage control method and device based on an adaptive PI controller, including: determining a coefficient corresponding to the deviation between the actual voltage value of the flexible direct current transmission VSC-HVDC system and the voltage reference value of the flexible direct current transmission VSC-HVDC system based on the deviation between the actual voltage value of the flexible direct current transmission VSC-HVDC system and the voltage reference value of the flexible direct current transmission VSC-HVDC system; and correcting the AC voltage value of the flexible direct current transmission VSC-HVDC system based on the coefficient corresponding to the deviation between the actual voltage value of the flexible direct current transmission VSC-HVDC system and the voltage reference value of the flexible direct current transmission VSC-HVDC system. The technical solution provided by the present invention optimizes the integral response speed and the AC voltage deviation. It has a significant effect on improving the voltage outer loop control response speed based on the three-phase PWM rectifier, and can guide the actual operation of the project.

[0062] Specifically, the voltage outer loop controller is implemented by a PI controller based on adaptive PI controller parameters, and the PI controller integral coefficient is adaptively adjusted with the voltage deviation, which can shorten the response time and reduce the voltage deviation value.

[0063] The above scheme is described in detail below.

[0064] Example 1

[0065] See attached Figure 1 , Figure 1 FIG. 1 is a flow chart showing the main steps of an AC voltage control method based on an adaptive PI controller according to an embodiment of the present invention. Figure 1 As shown, the AC voltage control method based on the adaptive PI controller in the embodiment of the present invention mainly includes the following steps:

[0066] Step S101: determining a coefficient corresponding to a deviation between an actual voltage value of the VSC-HVDC system and a voltage reference value of the VSC-HVDC system based on a deviation between an actual voltage value of the VSC-HVDC system and a voltage reference value of the VSC-HVDC system;

[0067] Step S102: the VSC-HVDC flexible direct current transmission VSC-HVDC flexible direct current transmission VSC-HVDC corrects the AC voltage value of the VSC-HVDC system based on a coefficient corresponding to a deviation between an actual voltage value of the VSC-HVDC system and a voltage reference value of the VSC-HVDC system.

[0068] In this embodiment, the calculation formula for the deviation between the actual voltage value of the flexible direct current transmission VSC-HVDC system and the voltage reference value of the flexible direct current transmission VSC-HVDC system is as follows:

[0069] e(k)=u0-u(k)

[0070] In the above formula, e(k) is the deviation between the actual voltage value of the flexible direct current transmission VSC-HVDC system at the kth moment and the voltage reference value of the flexible direct current transmission VSC-HVDC system, u0 is the voltage reference value of the flexible direct current transmission VSC-HVDC system, and u(k) is the actual voltage value of the flexible direct current transmission VSC-HVDC system at the kth moment.

[0071] In this embodiment, the calculation formula of the coefficient corresponding to the deviation between the actual voltage value of the flexible direct current transmission VSC-HVDC system and the voltage reference value of the flexible direct current transmission VSC-HVDC system is as follows:

[0072]

[0073] In the above formula, f(e(k)) is the coefficient corresponding to the deviation between the actual voltage value of the flexible direct current transmission VSC-HVDC system at the kth moment and the voltage reference value of the flexible direct current transmission VSC-HVDC system, M is the first integration interval, N is the second integration interval, and e(k) is the deviation between the actual voltage value of the flexible direct current transmission VSC-HVDC system at the kth moment and the voltage reference value of the flexible direct current transmission VSC-HVDC system.

[0074] The first integral interval M is smaller than the second integral interval N.

[0075] In one embodiment, the AC voltage value of the flexible direct current transmission VSC-HVDC system is corrected according to the following formula:

[0076]

[0077] In the above formula, u(k) is the correction value of the AC voltage value of the flexible direct current transmission VSC-HVDC system at the kth moment, k p is the proportional coefficient of the PI controller in the VSC-HVDC system, k iis the integral coefficient of the PI controller in the flexible direct current transmission VSC-HVDC system, e(j) is the deviation between the actual voltage value of the flexible direct current transmission VSC-HVDC system and the voltage reference value of the flexible direct current transmission VSC-HVDC system at the jth moment, and T is the integral time constant. The flexible direct current transmission VSC-HVDC adopts a dual closed-loop control structure, and the control system of the flexible direct current transmission VSC-HVDC is modeled by the d / q axis decoupling control method. The function of the outer loop controller is to generate the reference value of the current d / q axis, and the inner loop controller realizes the tracking control of the current reference value and generates the reference voltage of the converter.

[0078] The voltage outer loop of the PWM rectifier generally adopts a PI controller. i is a constant, and the integral increment remains unchanged during the entire control process. However, when a voltage drop occurs on the inverter side of the VSC, the power fluctuation of the entire system is large, which will cause a large fluctuation in the DC bus voltage. At this time, the voltage outer loop controller of the PWM rectifier will produce a large system deviation. In addition, because the system requires the integral term that the integral effect should be weakened or even eliminated when the system deviation is large, because at this time a large deviation in the system output will cause the integral accumulation of the PI operation, causing the control amount to exceed the limit control amount corresponding to the maximum action range that the actuator may allow, causing the system to overshoot or even oscillate, and unable to restore the controlled amount to the set value quickly. Taking this measure can achieve rapid adjustment and ensure that the system quickly enters a stable state; and when the deviation is small, the integral effect should be strengthened. Therefore, in order to improve the response speed of the VSC system, the idea of ​​variable speed integration is used, and based on the same inventive concept, the present invention designs an adaptive PI controller for the voltage outer loop control of the PWM rectifier, such as Figure 2 As shown, the adaptive PI controller includes a proportional link module and an integral link module respectively connected to the adder.

[0079] Among them, the mathematical model of the proportional link module is: p e(k), the mathematical model of the integral link module is: The mathematical model of the adaptive PI controller is as follows:

[0080]

[0081] In the above formula, u(k) is the voltage correction value of the flexible direct current transmission VSC-HVDC system at the kth moment, k p is the proportional coefficient of the PI controller in the VSC-HVDC system, k iis the integral coefficient of the PI controller in the flexible direct current transmission VSC-HVDC system, e(j) is the deviation between the actual voltage value of the flexible direct current transmission VSC-HVDC system and the voltage reference value of the flexible direct current transmission VSC-HVDC system at the jth moment, T is the integral time constant, f(e(k)) is the coefficient corresponding to the deviation between the actual voltage value of the flexible direct current transmission VSC-HVDC system and the voltage reference value of the flexible direct current transmission VSC-HVDC system at the kth moment, and e(k) is the deviation between the actual voltage value of the flexible direct current transmission VSC-HVDC system and the voltage reference value of the flexible direct current transmission VSC-HVDC system at the kth moment.

[0082] Preferably, the calculation formula of the coefficient corresponding to the deviation between the actual voltage value of the flexible direct current transmission VSC-HVDC system and the voltage reference value of the flexible direct current transmission VSC-HVDC system is as follows:

[0083]

[0084] In the above formula, M is the first integration interval, and N is the second integration interval.

[0085] Further, the first integral interval M is smaller than the second integral interval N.

[0086] Preferably, the calculation formula for the deviation between the actual voltage value of the flexible direct current transmission VSC-HVDC system and the voltage reference value of the flexible direct current transmission VSC-HVDC system is as follows:

[0087] e(k)=u0-u(k)

[0088] In the above formula, u0 is the voltage reference value of the flexible direct current transmission VSC-HVDC system, and u(k) is the actual voltage value of the flexible direct current transmission VSC-HVDC system at the kth moment.

[0089] In a specific implementation, based on the above control strategy, a 500kV dual flexible DC power supply is constructed using MATLAB simulation software. The topology structure is as follows: Figure 3 The rated voltage of the two AC systems is 220kV, and the DC voltage of the flexible direct current transmission VSC-HVDC system is ±500kV.

[0090] The VSCs in the simulation model are all controlled by the above-mentioned adaptive PI controller parameters. Figure 4 This is the VSC steady-state operation characteristic diagram. It can be seen that after entering the steady state at 1s, the various performance indicators are P = 0.6pu, Q = 0. At 2.2s, the power decreases from 0.6pu to 0.2pu. The effect of constant AC voltage control is as follows Figure 5When the power at the constant power end changes in a step, the adaptive PI control system has an obvious advantage over the fixed PI control in improving the response speed of the voltage, and the AC voltage fluctuation becomes smaller.

[0091] Example 2

[0092] Based on the same inventive concept, the present invention also provides an AC voltage control device based on an adaptive PI controller, such as Figure 6 As shown, the AC voltage control device based on the adaptive PI controller includes:

[0093] A first determination module is used to determine a coefficient corresponding to a deviation between an actual voltage value of the flexible direct current transmission VSC-HVDC system and a voltage reference value of the flexible direct current transmission VSC-HVDC system based on a deviation between an actual voltage value of the flexible direct current transmission VSC-HVDC system and a voltage reference value of the flexible direct current transmission VSC-HVDC system;

[0094] The second determination module is used to determine the voltage correction value of the flexible direct current transmission VSC-HVDC system based on a coefficient corresponding to a deviation between an actual voltage value of the flexible direct current transmission VSC-HVDC system and a voltage reference value of the flexible direct current transmission VSC-HVDC system.

[0095] Preferably, the calculation formula for the deviation between the actual voltage value of the flexible direct current transmission VSC-HVDC system and the voltage reference value of the flexible direct current transmission VSC-HVDC system is as follows:

[0096] e(k)=u0-u(k)

[0097] In the above formula, e(k) is the deviation between the actual voltage value of the flexible direct current transmission VSC-HVDC system at the kth moment and the voltage reference value of the flexible direct current transmission VSC-HVDC system, u0 is the voltage reference value of the flexible direct current transmission VSC-HVDC system, and u(k) is the actual voltage value of the flexible direct current transmission VSC-HVDC system at the kth moment.

[0098] Preferably, the calculation formula of the coefficient corresponding to the deviation between the actual voltage value of the flexible direct current transmission VSC-HVDC system and the voltage reference value of the flexible direct current transmission VSC-HVDC system is as follows:

[0099]

[0100] In the above formula, f(e(k)) is the coefficient corresponding to the deviation between the actual voltage value of the flexible direct current transmission VSC-HVDC system at the kth moment and the voltage reference value of the flexible direct current transmission VSC-HVDC system, M is the first integration interval, N is the second integration interval, and e(k) is the deviation between the actual voltage value of the flexible direct current transmission VSC-HVDC system at the kth moment and the voltage reference value of the flexible direct current transmission VSC-HVDC system.

[0101] Further, the first integral interval M is smaller than the second integral interval N.

[0102] Furthermore, the AC voltage value of the flexible direct current transmission VSC-HVDC system is corrected according to the following formula:

[0103]

[0104] In the above formula, u(k) is the correction value of the AC voltage value of the flexible direct current transmission VSC-HVDC system at the kth moment, k p is the proportional coefficient of the PI controller in the VSC-HVDC system, k i is the integral coefficient of the PI controller in the VSC-HVDC system, e(j) is the deviation between the actual voltage value of the VSC-HVDC system and the voltage reference value of the VSC-HVDC system at the jth moment, and T is the integration time constant.

[0105] Example 3

[0106] Based on the same inventive concept, the present invention also provides a computer device, which includes a processor and a memory, wherein the memory is used to store a computer program, wherein the computer program includes program instructions, and the processor is used to execute the program instructions stored in the computer storage medium. The processor may be a central processing unit (CPU), or may be other general-purpose processors, digital signal processors (DSP), application-specific integrated circuits (ASIC), field-programmable gate arrays (FPGA) or other programmable logic devices, discrete gates or transistor logic devices, discrete hardware components, etc. It is the computing core and control core of the terminal, which is suitable for implementing one or more instructions, and is specifically suitable for loading and executing one or more instructions in the computer storage medium to implement the corresponding method flow or corresponding function, so as to implement the steps of an AC voltage control method based on an adaptive PI controller in the above embodiment.

[0107] Example 4

[0108] Based on the same inventive concept, the present invention also provides a storage medium, specifically a computer-readable storage medium (Memory), which is a memory device in a computer device for storing programs and data. It can be understood that the computer-readable storage medium here can include both built-in storage media in the computer device and, of course, extended storage media supported by the computer device. The computer-readable storage medium provides a storage space, which stores the operating system of the terminal. In addition, one or more instructions suitable for being loaded and executed by the processor are also stored in the storage space, and these instructions can be one or more computer programs (including program codes). It should be noted that the computer-readable storage medium here can be a high-speed RAM memory or a non-volatile memory, such as at least one disk memory. The processor can load and execute one or more instructions stored in the computer-readable storage medium to implement the steps of an AC voltage control method based on an adaptive PI controller in the above embodiment.

[0109] Those skilled in the art will appreciate that embodiments of the present invention may be provided as methods, systems, or computer program products. Therefore, the present invention may take the form of a complete hardware embodiment, a complete software embodiment, or an embodiment combining software and hardware. Moreover, the present invention may take the form of a computer program product implemented on one or more computer-usable storage media (including but not limited to disk storage, CD-ROM, optical storage, etc.) containing computer-usable program code.

[0110] The present invention is described with reference to flowcharts and / or block diagrams of methods, devices (systems), and computer program products according to embodiments of the present invention. It should be understood that each process and / or block in the flowchart and / or block diagram, as well as the combination of processes and / or blocks in the flowchart and / or block diagram, can be implemented by computer program instructions. These computer program instructions can be provided to a processor of a general-purpose computer, a special-purpose computer, an embedded processor, or other programmable data processing device to produce a machine, so that the instructions executed by the processor of the computer or other programmable data processing device generate instructions for implementing the processes in the flowchart and / or block diagram. Figure 1 A process or multiple processes and / or boxes Figure 1 A device that provides the functions specified in a block or multiple blocks.

[0111] These computer program instructions may also be stored in a computer-readable memory capable of directing a computer or other programmable data processing device to operate in a specific manner, so that the instructions stored in the computer-readable memory produce an article of manufacture comprising an instruction device, which implements the process Figure 1 A process or multiple processes and / or boxes Figure 1 A function specified in one or more boxes.

[0112] These computer program instructions can also be loaded onto a computer or other programmable data processing device so that a series of operating steps are executed on the computer or other programmable device to produce a computer-implemented process, thereby providing instructions for implementing the process. Figure 1 A process or multiple processes and / or boxes Figure 1 The steps for the functions specified in one or more boxes.

[0113] 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. Any modification or equivalent replacement that does 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. An AC voltage control method based on an adaptive PI controller, characterized in that: The method comprises: Determine a coefficient corresponding to a deviation between the actual voltage value of the flexible direct current transmission VSC-HVDC system and the voltage reference value of the flexible direct current transmission VSC-HVDC system based on a deviation between the actual voltage value of the flexible direct current transmission VSC-HVDC system and the voltage reference value of the flexible direct current transmission VSC-HVDC system; The flexible direct current transmission VSC-HVDC flexible direct current transmission VSC-HVDC flexible direct current transmission VSC-HVDC corrects the AC voltage value of the flexible direct current transmission VSC-HVDC system based on a coefficient corresponding to a deviation between an actual voltage value of the flexible direct current transmission VSC-HVDC system and a voltage reference value of the flexible direct current transmission VSC-HVDC system.

2. The method according to claim 1, characterized in that The calculation formula for the deviation between the actual voltage value of the flexible direct current transmission VSC-HVDC system and the voltage reference value of the flexible direct current transmission VSC-HVDC system is as follows: e(k)=u0-u(k) In the above formula, e(k) is the deviation between the actual voltage value of the flexible direct current transmission VSC-HVDC system at the kth moment and the voltage reference value of the flexible direct current transmission VSC-HVDC system, u0 is the voltage reference value of the flexible direct current transmission VSC-HVDC system, and u(k) is the actual voltage value of the flexible direct current transmission VSC-HVDC system at the kth moment.

3. The method according to claim 1, characterized in that The calculation formula of the coefficient corresponding to the deviation between the actual voltage value of the flexible direct current transmission VSC-HVDC system and the voltage reference value of the flexible direct current transmission VSC-HVDC system is as follows: In the above formula, f(e(k)) is the coefficient corresponding to the deviation between the actual voltage value of the flexible direct current transmission VSC-HVDC system at the kth moment and the voltage reference value of the flexible direct current transmission VSC-HVDC system, M is the first integration interval, N is the second integration interval, and e(k) is the deviation between the actual voltage value of the flexible direct current transmission VSC-HVDC system at the kth moment and the voltage reference value of the flexible direct current transmission VSC-HVDC system.

4. The method according to claim 3, characterized in that The first integration interval M is smaller than the second integration interval N.

5. The method according to claim 3, characterized in that Correct the AC voltage value of the flexible direct current transmission VSC-HVDC system according to the following formula: In the above formula, u(k) is the correction value of the AC voltage value of the flexible direct current transmission VSC-HVDC system at the kth moment, k p is the proportional coefficient of the PI controller in the VSC-HVDC system, k i is the integral coefficient of the PI controller in the VSC-HVDC system, e(j) is the deviation between the actual voltage value of the VSC-HVDC system and the voltage reference value of the VSC-HVDC system at the jth moment, and T is the integration time constant.

6. An adaptive PI controller, characterized in that: The adaptive PI controller comprises a proportional link module and an integral link module respectively connected to the adder.

7. The adaptive PI controller according to claim 6, characterized in that The mathematical model of the proportional link module is: p e(k), the mathematical model of the integral link module is: Among them, k p is the proportional coefficient of the PI controller in the VSC-HVDC system, k i is the integral coefficient of the PI controller in the flexible direct current transmission VSC-HVDC system, e(j) is the deviation between the actual voltage value of the flexible direct current transmission VSC-HVDC system and the voltage reference value of the flexible direct current transmission VSC-HVDC system at the jth moment, T is the integral time constant, f(e(k)) is the coefficient corresponding to the deviation between the actual voltage value of the flexible direct current transmission VSC-HVDC system and the voltage reference value of the flexible direct current transmission VSC-HVDC system at the kth moment, and e(k) is the deviation between the actual voltage value of the flexible direct current transmission VSC-HVDC system and the voltage reference value of the flexible direct current transmission VSC-HVDC system at the kth moment.

8. The adaptive PI controller according to claim 7, characterized in that The calculation formula of the coefficient corresponding to the deviation between the actual voltage value of the flexible direct current transmission VSC-HVDC system and the voltage reference value of the flexible direct current transmission VSC-HVDC system is as follows: In the above formula, M is the first integration interval, and N is the second integration interval.

9. The adaptive PI controller according to claim 8, characterized in that The first integration interval M is smaller than the second integration interval N.

10. The adaptive PI controller according to claim 7, characterized in that: The calculation formula for the deviation between the actual voltage value of the flexible direct current transmission VSC-HVDC system and the voltage reference value of the flexible direct current transmission VSC-HVDC system is as follows: e(k)=u0-u(k) In the above formula, u0 is the voltage reference value of the flexible direct current transmission VSC-HVDC system, and u(k) is the actual voltage value of the flexible direct current transmission VSC-HVDC system at the kth moment.

11. An AC voltage control device based on an adaptive PI controller, characterized in that: The device comprises: A first determination module is used to determine a coefficient corresponding to a deviation between an actual voltage value of the flexible direct current transmission VSC-HVDC system and a voltage reference value of the flexible direct current transmission VSC-HVDC system based on a deviation between an actual voltage value of the flexible direct current transmission VSC-HVDC system and a voltage reference value of the flexible direct current transmission VSC-HVDC system; The second determination module is used to determine the voltage correction value of the flexible direct current transmission VSC-HVDC system based on a coefficient corresponding to a deviation between an actual voltage value of the flexible direct current transmission VSC-HVDC system and a voltage reference value of the flexible direct current transmission VSC-HVDC system.

12. The device according to claim 11, characterized in that The calculation formula for the deviation between the actual voltage value of the flexible direct current transmission VSC-HVDC system and the voltage reference value of the flexible direct current transmission VSC-HVDC system is as follows: e(k)=u0-u(k) In the above formula, e(k) is the deviation between the actual voltage value of the flexible direct current transmission VSC-HVDC system at the kth moment and the voltage reference value of the flexible direct current transmission VSC-HVDC system, u0 is the voltage reference value of the flexible direct current transmission VSC-HVDC system, and u(k) is the actual voltage value of the flexible direct current transmission VSC-HVDC system at the kth moment.

13. The device according to claim 11, characterized in that The calculation formula of the coefficient corresponding to the deviation between the actual voltage value of the flexible direct current transmission VSC-HVDC system and the voltage reference value of the flexible direct current transmission VSC-HVDC system is as follows: In the above formula, f(e(k)) is the coefficient corresponding to the deviation between the actual voltage value of the flexible direct current transmission VSC-HVDC system at the kth moment and the voltage reference value of the flexible direct current transmission VSC-HVDC system, M is the first integration interval, N is the second integration interval, and e(k) is the deviation between the actual voltage value of the flexible direct current transmission VSC-HVDC system at the kth moment and the voltage reference value of the flexible direct current transmission VSC-HVDC system.

14. The device according to claim 13, characterized in that The first integration interval M is smaller than the second integration interval N.

15. The device according to claim 13, characterized in that Correct the AC voltage value of the flexible direct current transmission VSC-HVDC system according to the following formula: In the above formula, u(k) is the correction value of the AC voltage value of the flexible direct current transmission VSC-HVDC system at the kth moment, k p is the proportional coefficient of the PI controller in the VSC-HVDC system, k i is the integral coefficient of the PI controller in the VSC-HVDC system, e(j) is the deviation between the actual voltage value of the VSC-HVDC system and the voltage reference value of the VSC-HVDC system at the jth moment, and T is the integration time constant.

16. A computer device, characterized in that: include: one or more processors; The processor is used to store one or more programs; When the one or more programs are executed by the one or more processors, the AC voltage control method based on the adaptive PI controller as described in any one of claims 1 to 5 is implemented.

17. A computer-readable storage medium, characterized in that: A computer program is stored thereon, and when the computer program is executed, the AC voltage control method based on the adaptive PI controller as claimed in any one of claims 1 to 5 is implemented.

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