Self-synchronizing voltage source type new energy station control method suitable for extremely weak power grid

Abstract

The invention discloses a self-synchronizing voltage source type new energy station control method suitable for an extremely weak power grid, and relates to the technical field of power systems. The method comprises the steps that power grid operation parameters and station output parameters of a new energy station grid-connected point are collected, and the power grid operation parameters comprise the voltage amplitude, the voltage phase, the power grid frequency and the equivalent impedance of the grid-connected point; according to the method, grid-connected point grid operation parameters are collected in real time, grid equivalent impedance is identified based on a recursive least square method, parameters of steady-state virtual impedance and transient-state virtual impedance are dynamically adjusted, so that the virtual impedance and the grid equivalent impedance are matched in a self-adaptive mode, the steady-state virtual impedance can balance voltage and current control capacity, and the transient-state virtual impedance can balance the transient-state virtual impedance. The control unbalance caused by the fixed power grid impedance is avoided, the transient virtual impedance can quickly respond according to the change rate of the output current, the transient current impact is effectively inhibited, and the problem that the existing fixed virtual impedance parameter is poor in adaptability in the extremely weak power grid impedance dynamic change scene is solved.

Description

Technical Field

[0001] This invention relates to the field of power system technology, specifically to a control method for self-synchronizing voltage source type new energy power stations suitable for extremely weak power grids. Background Technology

[0002] With the rapid development of new energy power generation technology, the construction scale of new energy power stations such as wind power and solar power is constantly expanding. A large number of new energy power stations are concentrated in remote areas. The power grids in these areas usually exhibit extremely weak grid characteristics, namely low short-circuit ratio, large equivalent impedance, and poor voltage stability, which poses a severe challenge to the safe and stable grid-connected operation of new energy power stations.

[0003] Currently, renewable energy power plants mainly use grid-connected converters to achieve power conversion and grid connection control. Their control modes are mainly divided into two categories: grid-following and voltage-source. Among them, grid-following control relies on the grid voltage as a synchronization reference and achieves grid connection by controlling the output current to track the reference command. It has the advantages of simple control structure and low cost, and has been widely used in strong or medium-strength grid scenarios. However, in extremely weak grid scenarios, the low short-circuit ratio of the extremely weak grid makes the grid connection point voltage susceptible to fluctuations in the output power of renewable energy power plants. Grid-following control lacks active voltage support capability and is difficult to maintain grid connection point voltage stability. Moreover, the dynamic response of this control mode depends on the grid voltage phase, and in extremely weak grids, it is prone to phase locking instability or even loss of lock, causing system oscillations. In severe cases, it may cause renewable energy power plants to disconnect from the grid, affecting the safe operation of the grid.

[0004] Therefore, this application proposes a control method for self-synchronizing voltage source type new energy power stations applicable to extremely weak power grids. Summary of the Invention

[0005] The purpose of this invention is to provide a self-synchronizing voltage source type new energy power station control method suitable for extremely weak power grids, so as to solve the problems mentioned in the background art.

[0006] To achieve the above objectives, the present invention provides the following technical solution: a control method for self-synchronizing voltage source type renewable energy power stations suitable for extremely weak power grids, wherein the method includes: The system collects grid operation parameters and station output parameters at the grid connection point of the new energy power plant. The grid operation parameters include the voltage amplitude, voltage phase, grid frequency, and equivalent impedance at the grid connection point. The station output parameters include the output active power, output reactive power, and DC side voltage of the converter. The extremely weak grid is defined as a grid with a short circuit strength of no more than 1.33. Based on the power grid operating parameters, a self-synchronizing voltage source control reference is constructed. The control reference includes an internal potential amplitude reference and an internal potential phase reference. The internal potential amplitude reference is designed to match the voltage support requirements of the grid connection point, and the internal potential phase reference is generated by simulating the rotor rotation characteristics of a synchronous generator through virtual inertia control. Based on the equivalent impedance and station output parameters in the power grid operating parameters, the virtual impedance parameters are dynamically adjusted and impedance compensation commands are generated. The virtual impedance parameters are divided into steady-state virtual impedance and transient virtual impedance. The steady-state virtual impedance is used to balance the control capability of voltage and current, and the transient virtual impedance is used to suppress transient current surges. By integrating the self-synchronizing voltage source control reference and impedance compensation command, a converter modulation signal is generated to control the output characteristics of the converter in the new energy power station. Real-time monitoring of voltage fluctuations at the grid connection point; if a voltage drop or phase jump disturbance is detected, a multi-state following transient control strategy is initiated, prioritizing the output of reactive power support current to compensate for voltage amplitude and phase changes; once the grid operating parameters have recovered to the preset stable range, the transient control strategy is stopped and the system switches back to the conventional self-synchronizing voltage source control mode. The step of generating the converter modulation signal by fusing the self-synchronizing voltage source control reference and impedance compensation command specifically includes: The target internal potential amplitude is obtained by superimposing the internal potential amplitude reference with the amplitude compensation component in the impedance compensation command. The target internal potential phase is obtained by fusing the internal potential phase reference with the phase compensation component and the virtual inertia phase adjustment in the impedance compensation command. A target voltage vector is constructed based on the target internal potential amplitude and the target internal potential phase. The target voltage vector is converted into a converter modulation signal through space vector pulse width modulation technology to drive the converter switching action.

[0007] As a specific solution of the technical solution of this application, the method further includes: constructing a collaborative control coordinate system for new energy power stations in extremely weak power grids, wherein the origin of the collaborative control coordinate system is the grid connection point of the new energy power station, and it is a three-phase prohibited coordinate system, wherein its A-axis coincides with the initial phase of the A-phase voltage at the grid connection point, the B-axis lags behind the A-axis by 120°, and the C-axis lags behind the A-axis by 240°. Accordingly, the steps for collecting grid operation parameters and power plant output parameters at the grid connection point of the new energy power plant specifically include: Three-phase voltage and three-phase current signals are acquired by a synchronous phasor measurement device deployed at the grid connection point. Based on the cooperative control coordinate system, Clark transformation and Park transformation are sequentially performed on the acquired three-phase voltage and three-phase current signals to obtain the voltage dq-axis components and the current dq-axis components. The voltage amplitude and phase at the grid connection point are calculated based on the voltage dq-axis components, and the equivalent impedance of the power grid is estimated based on the coupling relationship between the current dq-axis components and the voltage dq-axis components. The power station energy management system collects the DC side voltage, output active power, and output reactive power of the converter, thus completing the collection of grid operation parameters and power station output parameters.

[0008] As a specific solution to the technical solution of this application, the step of constructing a self-synchronizing voltage source control reference based on power grid operating parameters specifically includes: An internal potential amplitude reference is constructed using a droop control algorithm, the expression of which is:

[0009] in, As a reference for internal potential amplitude, The rated voltage at the grid connection point, This is the reactive voltage droop factor. Q represents the rated output reactive power, and Q represents the actual output reactive power. An internal potential phase reference is constructed based on the principle of a virtual synchronizer. The operating equation of the virtual synchronizer is as follows:

[0010] Where J is the virtual moment of inertia, As the internal potential phase reference, For virtual mechanical torque, The electromagnetic torque is D, and the damping coefficient is D; the virtual mechanical torque is... Electromagnetic torque is associated with the output active power command. It is calculated from the output active power and the internal electromotive force angular velocity.

[0011] As a specific solution to the technical solution of this application, the step of dynamically adjusting the virtual impedance parameter and generating an impedance compensation command based on the equivalent impedance and station output parameters in the power grid operating parameters specifically includes: Real-time identification of the equivalent impedance of the power grid using the recursive least squares method. According to equivalent impedance Determine the steady-state virtual impedance The steady-state virtual impedance satisfy And with equivalent impedance The changes show a positive correlation; Monitoring station output current change rate ,like If the current change exceeds a preset threshold, then the transient virtual impedance is activated. adjust, The adjustment amount and They are directly proportional, and their expression is:

[0012] in, This is the transient impedance adjustment coefficient. The preset current change threshold is used; Fusion steady-state virtual impedance With transient virtual impedance Obtain the total virtual impedance Based on total virtual impedance The impedance compensation command is used to correct the reference value of the converter current inner loop, thereby achieving coordinated control of voltage and current.

[0013] As a specific solution to the technical solution of this application, the step of activating the multi-state following transient control strategy specifically includes: Calculate voltage drop magnitude And perform a classification judgment: if If the drop is deemed severe, the reactive power support current command will be increased to 1.5 pu and maintained for 2 seconds. The drop was determined to be minor, and the reactive power support current command was set to 1.2 pu. Calculate the phase jump angle for phase jump disturbance. Generate phase compensation amount:

[0014] in, The phase compensation coefficient is superimposed on the internal potential phase reference to suppress power surges caused by phase abrupt changes. During transient control, the DC-side voltage of the converter is monitored in real time. If the DC-side voltage exceeds the allowable fluctuation range, the virtual mechanical torque is adjusted. Adjust the output active power to ensure the stability of the DC side voltage.

[0015] As a specific solution to the technical solution of this application, the method further includes: A broadband damping control supplementary module is added. The supplementary module monitors the harmonic components of the grid connection point voltage in the frequency range of 0 to 300 Hz. By injecting a damping current that is opposite to the harmonic frequency, the new energy power station exhibits non-negative damping characteristics to suppress low-frequency oscillations. The starting condition of the broadband damping control supplementary module is that the amplitude of the voltage harmonic component is less than 3% of the rated voltage.

[0016] A self-synchronizing voltage source type new energy power station control device suitable for extremely weak power grids, the device comprising: The parameter acquisition module is used to collect the grid operation parameters and station output parameters of the grid connection point of the new energy power station. The grid operation parameters include the voltage amplitude, voltage phase, grid frequency and equivalent impedance of the grid connection point. The station output parameters include the output active power, output reactive power and DC side voltage of the converter. The extremely weak grid is defined as a grid with a short-circuit ratio of no more than 1.33. The control reference construction module is used to construct a self-synchronizing voltage source control reference based on the power grid operating parameters. The control reference includes an internal potential amplitude reference and an internal potential phase reference. The internal potential amplitude reference is designed to match the voltage support requirements of the grid connection point, and the internal voltage phase reference is generated by simulating the rotor motion characteristics of a synchronous generator through virtual inertia control. The virtual impedance adjustment module is used to dynamically adjust the virtual impedance parameters and generate impedance compensation commands based on the equivalent impedance and station output parameters in the power grid operation parameters. The damping impedance parameters are divided into steady-state virtual impedance and transient virtual impedance. The steady-state virtual impedance is used to balance the control capability of voltage and current, and the transient virtual impedance is used to suppress transient current surges. The modulation signal generation module is used to integrate the self-synchronizing voltage source control reference and impedance compensation command to generate a converter modulation signal to control the output characteristics of the converter in the new energy power station. The transient control module is used to monitor the voltage fluctuation status at the grid connection point in real time. If a voltage drop or phase jump disturbance is detected, the multi-state following transient control strategy is activated. The reactive power support current is output first to compensate for voltage amplitude and phase change. After the grid operating parameters are restored to the preset stable range, the transient control strategy is stopped and the mode of conventional self-synchronizing voltage source control is switched back. The modulation signal generation module includes an amplitude fusion unit, a phase fusion unit, and a suitable modulation unit. The amplitude fusion unit is used to superimpose the internal potential reference with the amplitude compensation component in the impedance compensation command to obtain the target internal potential amplitude. The phase fusion unit is used to fuse the internal potential phase reference with the phase compensation component and the virtual inertia phase adjustment in the impedance compensation quality to obtain the target internal potential phase. The vector modulation unit is used to construct a target voltage vector based on the target internal potential amplitude and the target internal potential phase, and convert the target voltage vector into a converter modulation signal through space vector pulse width modulation technology to drive the converter switching action.

[0017] An electronic device, the electronic device comprising: At least one processor, and a storage device communicatively connected to said at least one processor, wherein, The storage device stores a computer program that can be executed by the at least one processor. When the computer program is executed by the at least one processor, it enables the at least one processor to perform the self-synchronizing voltage source renewable energy power station control method applicable to extremely weak power grids as described in any of the above embodiments.

[0018] A computer-readable storage medium storing computer instructions, which, when executed by a processor, implement the self-synchronizing voltage source type new energy power station control method applicable to extremely weak electricity as described in any of the above embodiments.

[0019] Compared with the prior art, the beneficial effects of the present invention are: This invention collects grid operating parameters at the grid connection point in real time, identifies the grid's equivalent impedance based on the recursive least squares method, and dynamically adjusts the steady-state and transient virtual impedance parameters to adaptively match the virtual impedance with the grid's equivalent impedance. The steady-state virtual impedance balances voltage and current control capabilities, avoiding control imbalances caused by fixed grid impedance, while the transient virtual impedance responds quickly to the rate of change of output current, effectively suppressing transient current surges. This solves the problem of poor adaptability of existing fixed virtual impedance parameters in scenarios with dynamic changes in extremely weak grid impedance, thus improving the grid connection stability of new energy power plants in extremely weak grids.

[0020] Meanwhile, this invention constructs a collaborative control coordinate system between a very weak power grid and a renewable energy power station, and combines Clark and Park transformations to achieve accurate acquisition and calculation of power grid parameters. Based on droop control and the principle of a virtual synchronous machine, it constructs a self-synchronizing voltage source control benchmark, and integrates impedance compensation commands to generate converter modulation signals. The control logic is clear and hierarchical. All control algorithms used are mature and reliable in engineering. The required parameters can be obtained from existing equipment such as synchronous phasor measurement devices and power station energy management systems, eliminating the need for additional complex hardware and reducing engineering implementation costs.

[0021] This invention achieves a smooth switching between conventional self-synchronizing voltage source control mode and transient control mode. When the power grid is operating stably, the conventional control mode ensures power quality and operational efficiency. Upon detecting a grid disturbance, a transient control strategy is quickly activated. Once the grid stabilizes, it automatically switches back to the conventional mode. This approach caters to the control requirements of different operating scenarios, enhancing the flexibility and practicality of the control strategy. Attached Figure Description

[0022] Figure 1 This is a schematic diagram of the self-synchronizing voltage source type new energy power station control method applicable to extremely weak power grids according to the present invention; Figure 2 This is a schematic diagram of the self-synchronizing voltage source type new energy power station control device applicable to extremely weak power grids according to the present invention. Detailed Implementation

[0023] The technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, and not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0024] The terms "first," "second," etc., in the specification and accompanying drawings of this application are used to distinguish similar objects and are not necessarily used to describe a specific order or sequence. For example, the first cluster and the second cluster mentioned below belong to different clusters. It should be understood that such names can be used interchangeably where appropriate so that the embodiments described herein can be implemented in a sequence other than that illustrated or described herein. Furthermore, the terms "comprising" and "having," and any variations thereof, are intended to cover non-exclusive inclusion. For example, a process, method, system, product, or device that includes a series of steps or modules is not necessarily limited to those steps or modules explicitly listed, but may include other steps or modules not explicitly listed or inherent to these processes, methods, products, or devices. The division of modules in the embodiments of this application is merely a logical division. In actual applications, there may be other division methods. For example, multiple modules may be combined into or integrated into another system, or some features may be ignored or not performed. In addition, the shown or discussed mutual coupling or direct coupling or communication connection may be through some interface, and the indirect coupling or communication connection between modules may be electrical or other similar forms. None of these are limited in the embodiments of this application. Furthermore, the modules or sub-modules described as separate components may or may not be physically separated, may or may not be physical modules, or may be distributed among multiple circuit modules. Some or all of the modules may be selected according to actual needs to achieve the purpose of the embodiments of this application.

[0025] To address the technical problems mentioned in the background section regarding the lack of active voltage support and susceptibility to lockout in traditional grid-following control in extremely weak grid scenarios, and the transient overcurrent, lag in transient response, and insufficient suppression of broadband oscillations caused by fixed virtual impedance in existing self-synchronizing voltage source control, this application proposes an embodiment of a self-synchronizing voltage source type renewable energy power station control method suitable for extremely weak grids, as follows: Figure 1 As shown, the self-synchronizing voltage source type new energy power station control method applicable to extremely weak power grids includes steps S100 to S500.

[0026] Step S100: Collect grid operation parameters and station output parameters at the grid connection point of the new energy power station.

[0027] In this embodiment, the grid operating parameters include the voltage amplitude at the grid connection point, voltage phase, grid frequency, and equivalent impedance; the station output parameters include the output active power, output reactive power, and DC-side voltage of the converter; and the extremely weak grid is defined as a grid with a short-circuit ratio not greater than 1.33.

[0028] In this embodiment, the electrical quantities at the grid connection point can be collected in real time by a synchronous phasor measurement device (PMU) and transmitted to the station controller via a communication protocol (such as IEC61850) as the basis for subsequent control strategy adjustments.

[0029] Step S200: Construct a self-synchronizing voltage source control reference based on the power grid operating parameters.

[0030] In this embodiment, the control reference includes an internal potential amplitude reference and an internal potential phase reference. The internal potential amplitude reference is designed to match the grid connection point voltage support requirements, and the internal potential phase reference is generated by simulating the rotor motion characteristics of a synchronous generator through virtual inertia control.

[0031] Step S300: Based on the equivalent impedance and station output parameters in the power grid operating parameters, dynamically adjust the virtual impedance parameters and generate impedance compensation commands.

[0032] In this embodiment, the virtual impedance parameter is divided into steady-state virtual impedance and transient virtual impedance. The steady-state virtual impedance is used to balance the control capability of voltage and current, while the transient virtual impedance is used to suppress transient current surges.

[0033] Step S400: Integrate the self-synchronizing voltage source control reference and impedance compensation command to generate a converter modulation signal to control the output characteristics of the converter in the new energy power station.

[0034] Step S500: Monitor the voltage fluctuation status at the grid connection point in real time. If a voltage drop or phase change disturbance is detected, start the multi-state follower transient control strategy, prioritize the output of reactive power support current to compensate for voltage amplitude and phase change. After the grid operating parameters recover to the preset stable range, stop the transient control strategy and switch back to the conventional self-synchronizing voltage source control mode.

[0035] It should be noted that in extremely weak power grids, conventional voltage source control alone may not be able to cope with complex impedance changes and transient impacts. In order to achieve accurate control signal generation, in one embodiment of this example, step S400, the self-synchronizing voltage source control reference and impedance compensation command are fused to generate a converter modulation signal, including steps S410 to S430.

[0036] Step S410: Superimpose the internal potential amplitude reference with the amplitude compensation component in the impedance compensation parameter to obtain the target internal potential amplitude.

[0037] Step S420: The internal potential phase reference is fused with the phase compensation component of the impedance compensation command and the virtual inertia phase adjustment to obtain the target internal potential phase.

[0038] Step S430: Construct a target voltage vector based on the target internal potential amplitude and the target internal potential phase, and convert the target voltage vector into a converter modulation signal using space vector pulse width modulation technology to drive the converter switching action.

[0039] In this embodiment, by decoupling the control of amplitude and phase and introducing impedance compensation, the converter's tracking accuracy and anti-interference capability to the power grid can be effectively improved.

[0040] It should be noted that accurate parameter acquisition is a prerequisite for the implementation of the control strategy. In one embodiment of this application, the method further includes: constructing a collaborative control coordinate system for new energy power plants in extremely weak power grids. The origin of the collaborative control coordinate system is the grid connection point of the new energy power plant, and it is a three-phase stationary coordinate system. Its A-axis coincides with the initial phase of the A-phase voltage at the grid connection point, the B-axis lags the A-axis by 120°, and the C-axis lags the A-axis by 240°. Correspondingly, step S100 involves acquiring the power grid operation parameters and power plant output parameters at the grid connection point of the new energy power plant, including steps S110 to S130.

[0041] Step S110: Collect three-phase voltage signals and three-phase current signals through the synchronous phasor measurement device deployed at the grid connection point. Based on the cooperative control coordinate system, perform Clark transformation and Park transformation on the collected three-phase voltage signals and three-phase current signals in sequence to obtain the voltage dq-axis components and current dq-axis components.

[0042] Step S120: Calculate the voltage amplitude and phase at the grid connection point based on the voltage dq component, and estimate the equivalent impedance of the power grid based on the coupling relationship between the current dq axis component and the voltage dq axis component.

[0043] Step S130: Collect the DC side voltage, output active power and output reactive power of the converter through the power station energy management system to complete the collection of grid operation parameters and power station output parameters.

[0044] It should be noted that constructing a reasonable control reference is the key to simulating the characteristics of a synchronous machine. In one embodiment of this application, step S200, constructing a self-synchronizing voltage source control reference based on the power grid operating parameters, includes steps S210 to S220.

[0045] Step S210: Construct an internal potential amplitude reference using a droop control algorithm. The expression for the droop control algorithm is as follows:

[0046] in, As a reference for internal potential amplitude, The rated voltage at the grid connection point, This is the reactive voltage droop factor. Q represents the rated output reactive power, and Q represents the actual output reactive power.

[0047] Step S220: Construct an internal potential phase reference based on the principle of a virtual synchronizer. The equation of motion for the virtual synchronizer is:

[0048] Where J is the virtual moment of inertia, As the internal potential phase reference, For virtual mechanical torque, The electromagnetic torque is D, and the damping coefficient is D; the virtual mechanical torque is... Electromagnetic torque is associated with the output active power command. It is calculated from the output active power and the internal electromotive force angular velocity.

[0049] It should be noted that the dynamic change of the equivalent impedance in a very weak power grid can affect the system stability. In one embodiment of this application, step S300, based on the equivalent impedance in the power grid operating parameters and the station output parameters, dynamically adjusts the virtual impedance parameters and generates an impedance compensation command, including steps S310 to S330.

[0050] Step S310: Identify the equivalent impedance of the power grid in real time using the recursive least squares method. According to equivalent impedance Determine the steady-state virtual impedance The steady-state virtual impedance satisfy And with equivalent impedance They show a positive correlation.

[0051] Step S320: Monitor the rate of change of the station's output current ,like If the current change exceeds a preset threshold, then the transient virtual impedance is activated. adjust, The adjustment amount and They are directly proportional, and their expression is:

[0052] in, This is the transient impedance adjustment coefficient. This is a preset threshold for current variation.

[0053] Step S330: Integrate steady-state virtual impedance With transient virtual impedance Obtain the total virtual impedance Based on total virtual impedance The impedance compensation command is used to correct the reference value of the converter current inner loop, thereby achieving coordinated control of voltage and current.

[0054] It should be noted that, for voltage drops and phase jumps, a single control strategy is difficult to balance response speed and stability. In one embodiment of this application, step S500, a multi-state following transient control strategy is initiated, including steps S510 to S530.

[0055] Step S510: Calculate the voltage drop magnitude And perform a classification judgment: if If the drop is deemed severe, the reactive power support current command will be increased to 1.5 pu and maintained for 2 seconds. The drop was determined to be minor, and the reactive power support current command was set to 1.2 pu.

[0056] Step S520: Calculate the phase jump angle for the phase jump disturbance. Generate phase compensation amount:

[0057] in, The phase compensation coefficient is superimposed on the internal potential phase reference to suppress power surges caused by phase abrupt changes.

[0058] Step S530: During transient control, the DC-side voltage of the converter is monitored in real time. If the DC-side voltage exceeds the allowable fluctuation range, the virtual mechanical torque is adjusted. Adjust the output active power to ensure the stability of the DC side voltage.

[0059] It should be noted that broadband oscillations under extremely weak power grids may lead to system instability. In one embodiment of this application, the method further includes: adding a broadband damping control supplementary module. The supplementary module monitors the harmonic components of the grid connection point voltage in the frequency range of 0 to 300 Hz. By injecting a damping current opposite to the harmonic frequency, the new energy power station exhibits non-negative damping characteristics to suppress low-frequency oscillations. The starting condition of the broadband damping control supplementary module is that the amplitude of the voltage harmonic component is greater than 3% of the rated voltage.

[0060] The embodiment of the self-synchronizing voltage source type new energy power station control method proposed in this application for extremely weak power grids accurately acquires parameters by constructing a cooperative control coordinate system, establishes a control benchmark using droop control and virtual synchronous machine principles, and combines dynamic virtual impedance adjustment and multi-state transient control strategies. It effectively solves the technical problems of poor adaptability, slow transient response and easy oscillation of existing technologies under extremely weak power grids. In other words, this application can not only simulate the characteristics of synchronous generators to provide voltage support, but also dynamically adjust the virtual impedance according to the changes in grid impedance. At the same time, through hierarchical transient control and wideband damping injection, it realizes the safe and stable operation of new energy power stations under extremely weak power grids.

[0061] Based on the same inventive concept, this application also provides a self-synchronizing voltage source type new energy power station control device suitable for extremely weak power grids, such as... Figure 2 As shown, the device includes a parameter acquisition module 10, a control reference construction module 20, a virtual impedance adjustment module 30, a modulation signal generation module 40, and a transient control module 50.

[0062] The parameter acquisition module 10 is used to acquire the grid operation parameters and station output parameters of the grid connection point of the new energy power station. The grid operation parameters include the voltage amplitude, voltage phase, grid frequency and equivalent impedance of the grid connection point. The station output parameters include the output active power, output reactive power and DC side voltage of the converter. The extremely weak grid is defined as a grid with a short-circuit ratio of no more than 1.33.

[0063] The control reference construction module 20 is used to construct a self-synchronizing voltage source control reference based on the power grid operating parameters. The control reference includes an internal potential top view reference and an internal potential phase reference. The internal potential amplitude reference is designed to match the grid connection point voltage support requirements. The internal potential phase reference is generated by simulating the rotor operating characteristics of a synchronous generator through virtual inertia control.

[0064] The virtual impedance adjustment module 30 is used to dynamically adjust the virtual impedance parameters and generate impedance compensation commands based on the equivalent impedance and station output parameters in the power grid operating parameters. The virtual impedance parameters are divided into steady-state virtual impedance and transient virtual impedance. The steady-state virtual impedance is used to balance the control capability of voltage and current, and the transient virtual impedance is used to suppress transient current surges.

[0065] The modulation signal generation module 40 is used to integrate the self-synchronizing voltage source control reference and impedance compensation command to generate a converter modulation signal to control the output characteristics of the converter in the new energy power station.

[0066] The transient control module 50 is used to monitor the voltage fluctuation status at the grid connection point in real time. If a voltage drop or phase jump disturbance is detected, a multi-state following transient control strategy is initiated, and reactive power support current is output first to compensate for voltage amplitude and phase changes. After the grid operating parameters recover to the preset stable range, the transient control strategy is stopped and the module switches back to the conventional self-synchronizing voltage source control module.

[0067] The modulation signal generation module 40 includes an amplitude fusion unit 41, a phase fusion unit 42, and a vector adjustment jump 43. The amplitude fusion unit 41 is used to superimpose the internal potential amplitude reference with the amplitude compensation component in the impedance compensation command to obtain the target internal potential amplitude. The phase fusion unit 42 is used to fuse the internal potential phase reference with the phase compensation component and the virtual inertia phase adjustment amount in the impedance compensation command to obtain the target internal potential phase. The vector modulation unit 43 is used to construct a target voltage vector based on the target internal potential amplitude and the target internal potential phase, and convert the target voltage vector into a converter modulation signal through space vector pulse width modulation technology to drive the converter switching action.

[0068] Based on the same inventive concept, this application also provides an electronic device, which includes at least one processor and a memory communicatively connected to the at least one processor, wherein the memory stores a computer program executable by the at least one processor, and when the computer program is executed by the at least one processor, the at least one processor is able to execute the self-synchronizing voltage source type new energy power station control method applicable to extremely weak power grids as described in any of the above embodiments.

[0069] Based on the same inventive concept, this application also provides a computer-readable storage medium storing computer instructions, which, when executed by a processor, implement the self-synchronizing voltage source type new energy power station control method applicable to extremely weak power grids as described in any of the above embodiments.

[0070] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended embodiments and their equivalents.

Claims

1. A control method for self-synchronizing voltage source type renewable energy power stations suitable for extremely weak power grids, characterized in that: The method includes: The system collects grid operation parameters and station output parameters at the grid connection point of the new energy power plant. The grid operation parameters include the voltage amplitude, voltage phase, grid frequency, and equivalent impedance at the grid connection point. The station output parameters include the output active power, output reactive power, and DC side voltage of the converter. The extremely weak grid is defined as a grid with a short circuit strength of no more than 1.

33. Based on the power grid operating parameters, a self-synchronizing voltage source control reference is constructed. The control reference includes an internal potential amplitude reference and an internal potential phase reference. The internal potential amplitude reference is designed to match the voltage support requirements of the grid connection point, and the internal potential phase reference is generated by simulating the rotor rotation characteristics of a synchronous generator through virtual inertia control. Based on the equivalent impedance and station output parameters in the power grid operating parameters, the virtual impedance parameters are dynamically adjusted and impedance compensation commands are generated. The virtual impedance parameters are divided into steady-state virtual impedance and transient virtual impedance. The steady-state virtual impedance is used to balance the control capability of voltage and current, and the transient virtual impedance is used to suppress transient current surges. By integrating the self-synchronizing voltage source control reference and impedance compensation command, a converter modulation signal is generated to control the output characteristics of the converter in the new energy power station. Real-time monitoring of voltage fluctuations at the grid connection point; if a voltage drop or phase jump disturbance is detected, a multi-state following transient control strategy is initiated, prioritizing the output of reactive power support current to compensate for voltage amplitude and phase changes; once the grid operating parameters have recovered to the preset stable range, the transient control strategy is stopped and the system switches back to the conventional self-synchronizing voltage source control mode. The step of generating the converter modulation signal by fusing the self-synchronizing voltage source control reference and impedance compensation command specifically includes: The target internal potential amplitude is obtained by superimposing the internal potential amplitude reference with the amplitude compensation component in the impedance compensation command. The target internal potential phase is obtained by fusing the internal potential phase reference with the phase compensation component and the virtual inertia phase adjustment in the impedance compensation command. A target voltage vector is constructed based on the target internal potential amplitude and the target internal potential phase. The target voltage vector is converted into a converter modulation signal through space vector pulse width modulation technology to drive the converter switching action.

2. The control method for a self-synchronizing voltage source type new energy power station suitable for extremely weak power grids according to claim 1, characterized in that: The method further includes: constructing a collaborative control coordinate system for new energy power stations in extremely weak power grids. The origin of the collaborative control coordinate system is the grid connection point of the new energy power station, and it is a three-phase prohibited coordinate system. Its A-axis coincides with the initial phase of the A-phase voltage at the grid connection point, the B-axis lags behind the A-axis by 120°, and the C-axis lags behind the A-axis by 240°. Accordingly, the steps for collecting grid operation parameters and power plant output parameters at the grid connection point of the new energy power plant specifically include: Three-phase voltage and three-phase current signals are acquired by a synchronous phasor measurement device deployed at the grid connection point. Based on the cooperative control coordinate system, Clark transformation and Park transformation are sequentially performed on the acquired three-phase voltage and three-phase current signals to obtain the voltage dq-axis components and the current dq-axis components. The voltage amplitude and phase at the grid connection point are calculated based on the voltage dq-axis components, and the equivalent impedance of the power grid is estimated based on the coupling relationship between the current dq-axis components and the voltage dq-axis components. The power station energy management system collects the DC side voltage, output active power, and output reactive power of the converter, thus completing the collection of grid operation parameters and power station output parameters.

3. The control method for a self-synchronizing voltage source type new energy power station suitable for extremely weak power grids according to claim 2, characterized in that: The step of constructing a self-synchronizing voltage source control reference based on power grid operating parameters specifically includes: An internal potential amplitude reference is constructed using a droop control algorithm, the expression of which is: ； in, As a reference for internal potential amplitude, The rated voltage at the grid connection point, This is the reactive voltage droop factor. Q represents the rated output reactive power, and Q represents the actual output reactive power. An internal potential phase reference is constructed based on the principle of a virtual synchronizer. The operating equation of the virtual synchronizer is as follows: ； Where J is the virtual moment of inertia. As the internal potential phase reference, For virtual mechanical torque, The electromagnetic torque is D, and the damping coefficient is D; the virtual mechanical torque is... Electromagnetic torque is associated with the output active power command. It is calculated from the output active power and the internal electromotive force angular velocity.

4. The self-synchronizing voltage source type new energy power station control method applicable to extremely weak power grids according to claim 3, characterized in that: The step of dynamically adjusting the virtual impedance parameters and generating impedance compensation commands based on the equivalent impedance and station output parameters in the power grid operating parameters specifically includes: Real-time identification of the equivalent impedance of the power grid using the recursive least squares method. According to equivalent impedance Determine the steady-state virtual impedance The steady-state virtual impedance satisfy And with equivalent impedance The changes show a positive correlation; Monitoring station output current change rate ,like If the current change exceeds a preset threshold, then the transient virtual impedance is activated. adjust, The adjustment amount and They are directly proportional, and their expression is: ； in, This is the transient impedance adjustment coefficient. The preset current change threshold is used; Fusion steady-state virtual impedance With transient virtual impedance Obtain the total virtual impedance Based on total virtual impedance The impedance compensation command is used to correct the reference value of the converter current inner loop, thereby achieving coordinated control of voltage and current.

5. The control method for a self-synchronizing voltage source type new energy power station suitable for extremely weak power grids according to claim 1, characterized in that: The steps for initiating the multi-state following transient control strategy specifically include: Calculate voltage drop magnitude And perform a classification judgment: if If the drop is deemed severe, the reactive power support current command will be increased to 1.5 pu and maintained for 2 seconds. The drop was determined to be minor, and the reactive power support current command was set to 1.2 pu. Calculate the phase jump angle for phase jump disturbance. Generate phase compensation amount: ； in, The phase compensation coefficient is superimposed on the internal potential phase reference to suppress power surges caused by phase abrupt changes. During transient control, the DC-side voltage of the converter is monitored in real time. If the DC-side voltage exceeds the allowable fluctuation range, the virtual mechanical torque is adjusted. Adjust the output active power to ensure the stability of the DC side voltage.

6. A control method for a self-synchronizing voltage source type new energy power station suitable for extremely weak power grids according to any one of claims 1 to 5, characterized in that: The method further includes: A broadband damping control supplementary module is added. The supplementary module monitors the harmonic components of the grid connection point voltage in the frequency range of 0 to 300 Hz. By injecting a damping current that is opposite to the harmonic frequency, the new energy power station exhibits non-negative damping characteristics to suppress low-frequency oscillations. The starting condition of the broadband damping control supplementary module is that the amplitude of the voltage harmonic component is less than 3% of the rated voltage.

7. A self-synchronizing voltage source type new energy power station control device suitable for extremely weak power grids, characterized in that: The device includes: The parameter acquisition module is used to collect the grid operation parameters and station output parameters of the grid connection point of the new energy power station. The grid operation parameters include the voltage amplitude, voltage phase, grid frequency and equivalent impedance of the grid connection point. The station output parameters include the output active power, output reactive power and DC side voltage of the converter. The extremely weak grid is defined as a grid with a short-circuit ratio of no more than 1.

33. The control reference construction module is used to construct a self-synchronizing voltage source control reference based on the power grid operating parameters. The control reference includes an internal potential amplitude reference and an internal potential phase reference. The internal potential amplitude reference is designed to match the voltage support requirements of the grid connection point, and the internal voltage phase reference is generated by simulating the rotor motion characteristics of a synchronous generator through virtual inertia control. The virtual impedance adjustment module is used to dynamically adjust the virtual impedance parameters and generate impedance compensation commands based on the equivalent impedance and station output parameters in the power grid operation parameters. The damping impedance parameters are divided into steady-state virtual impedance and transient virtual impedance. The steady-state virtual impedance is used to balance the control capability of voltage and current, and the transient virtual impedance is used to suppress transient current surges. The modulation signal generation module is used to integrate the self-synchronizing voltage source control reference and impedance compensation command to generate a converter modulation signal to control the output characteristics of the converter in the new energy power station. The transient control module is used to monitor the voltage fluctuation status at the grid connection point in real time. If a voltage drop or phase jump disturbance is detected, the multi-state following transient control strategy is activated. The reactive power support current is output first to compensate for voltage amplitude and phase change. After the grid operating parameters are restored to the preset stable range, the transient control strategy is stopped and the mode of conventional self-synchronizing voltage source control is switched back. The modulation signal generation module includes an amplitude fusion unit, a phase fusion unit, and a suitable modulation unit. The amplitude fusion unit is used to superimpose the internal potential reference with the amplitude compensation component in the impedance compensation command to obtain the target internal potential amplitude. The phase fusion unit is used to fuse the internal potential phase reference with the phase compensation component and the virtual inertia phase adjustment in the impedance compensation quality to obtain the target internal potential phase. The vector modulation unit is used to construct a target voltage vector based on the target internal potential amplitude and the target internal potential phase, and convert the target voltage vector into a converter modulation signal through space vector pulse width modulation technology to drive the converter switching action.

8. An electronic device, characterized in that: The electronic device includes: At least one processor, and a storage device communicatively connected to said at least one processor, wherein, The storage device stores a computer program that can be executed by the at least one processor. When the computer program is executed by the at least one processor, it enables the at least one processor to perform the self-synchronizing voltage source renewable energy power station control method applicable to extremely weak power grids as described in any one of claims 1-6.

9. A computer-readable storage medium, characterized in that: The computer-readable storage medium stores computer instructions, which, when executed by a processor, implement the self-synchronizing voltage source type new energy power station control method applicable to extremely weak electricity as described in any one of claims 1-6.

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