A PCS parallel and off-grid seamless switching control method and device

Abstract

This invention relates to the field of energy storage converter technology, and discloses a PCS grid-connected / off-grid seamless switching control method and device. By constructing an equivalent state mapping model of the grid connection point through preset virtual impedance parameters, the inconsistency in voltage amplitude and phase at the grid connection point can be accurately converted into a quantifiable state energy deviation within the system, avoiding synchronization deviations caused by ambiguous state perception in traditional control. This deviation is compared with the target equilibrium value to generate an error signal, which is then optimized by a dynamic adjustment unit to form a state compensation quantity. This compensation quantity is injected into the VSG state update equation in a state feedforward manner, maintaining the original inertia and power droop characteristics of the VSG while driving its internal state to naturally converge towards the grid connection side. When the state energy deviation meets the stability threshold, the grid connection switch is closed. At this point, the voltage, frequency, and phase on both sides of the grid connection point have achieved high-precision matching, eliminating the inrush current during switching transients at the source and ensuring the safety of the PCS and grid equipment.

Description

Technical Field

[0001] This invention relates to the field of energy storage converter technology, specifically to a PCS on-grid and off-grid seamless switching control method and device. Background Technology

[0002] With the widespread application of new energy storage systems, the energy storage converter (PCS), as the core of energy conversion, directly determines the system's operational reliability and power quality through its seamless switching performance between grid and off-grid. Currently, most mainstream switching control schemes rely on phase-locked loops (PLLs) to achieve grid synchronization. However, PLLs are prone to problems such as phase detection delay and phase-locking instability under grid voltage distortion, frequency fluctuations, or weak grid scenarios, resulting in large current surges at the moment of grid connection and even damage to power electronic devices.

[0003] Traditional control strategies often employ a hard-switching architecture combining grid-connected current control and off-grid voltage control. Sudden changes in control parameters during switching can easily lead to voltage sags and harmonic distortions. Furthermore, they lack a dynamic adaptation mechanism to ensure grid-connected point consistency, making it difficult to balance synchronization convergence speed and steady-state regulation accuracy. Simultaneously, existing current loop controls often use a fixed-gain design, failing to dynamically adjust execution capabilities based on system synchronization deviations. This further exacerbates transient impacts and waveform distortions during switching, making it difficult to meet the application requirements of high-reliability energy storage systems. Summary of the Invention

[0004] This invention provides a PCS parallel and offline seamless handover control method and apparatus to solve the problem of how to achieve PCS parallel and offline seamless handover.

[0005] In a first aspect, the present invention provides a PCS grid-connected / off-grid-connected seamless switching control method, comprising: constructing an equivalent state mapping model of the grid connection point based on preset virtual impedance parameters, mapping the grid connection point voltage inconsistency to the state energy deviation of the system; comparing the state energy deviation with its target balance value to generate a system state imbalance error signal; processing the error signal by a dynamic adjustment unit to generate a corresponding state compensation quantity; injecting the state compensation quantity into the state update equation of the virtual synchronous machine in a state feedforward manner, so that the internal state of the virtual synchronous machine naturally converges to be consistent with the state of the grid connection side while maintaining its original inertial characteristics and power droop characteristics; after the virtual synchronous machine state modulation is completed, controlling the PCS using a double closed-loop structure of voltage outer loop and current inner loop; when the state energy deviation simultaneously meets the stability threshold condition within a preset time window, determining that the states on both sides of the grid connection point are consistent, and controlling the grid connection switch to close.

[0006] In one optional implementation, the process of obtaining the state energy deviation includes: when the grid connection point is disconnected, acquiring the voltage state quantities of the PCS output side and the grid side respectively, and characterizing them in the same coordinate system to obtain the synchronization state energy deviation component and the equivalent potential state energy deviation component; the synchronization state energy deviation component is used to characterize the inconsistency of voltage phase and rotation state on both sides of the grid connection point; the equivalent potential state energy deviation component is used to characterize the inconsistency of voltage amplitude on both sides of the grid connection point.

[0007] In one optional implementation, the state compensation amount includes: angular velocity synchronization compensation amount and potential amplitude synchronization compensation amount; the calculation formula for the angular velocity synchronization compensation amount is:

[0008]

[0009] in, ω s This is the angular velocity synchronization compensation amount; k ωp This is the first adjustment parameter; E θ This refers to the energy deviation component in the synchronization state. k ωi This is the second adjustment parameter; The formula for calculating the synchronous compensation amount of potential amplitude is:

[0010] in, E s This is the amount of synchronous compensation for the potential amplitude; k ωp This is the third adjustment parameter; E θ This represents the energy deviation component of the equivalent potential state. k ωi This is the fourth adjustment parameter.

[0011] In one optional implementation, the state compensation amount is injected into the state update equation of the virtual synchronizer in a state feedforward manner to obtain the angular velocity state reconstruction equation and the equivalent potential amplitude state reconstruction equation; the angular velocity state reconstruction equation is:

[0012] in, ω Angular velocity; ω vsg The angular velocity of the virtual synchronizer; ω s This is the angular velocity synchronization compensation amount; The equivalent potential amplitude state reconstruction equation is:

[0013] in, E It is the equivalent potential amplitude; ω vsg This represents the equivalent potential amplitude of the virtual synchronous machine; E s This is the synchronous compensation amount for the potential amplitude.

[0014] In one alternative implementation, the voltage outer loop control includes: subtracting the voltage reference value output by the virtual synchronizer from the actual output voltage to obtain a voltage difference; and generating a current reference signal based on the voltage difference using a quasi-PR controller.

[0015] In one alternative implementation, the inner current loop control includes: obtaining a voltage reference signal based on a current reference signal using proportional control.

[0016] In one optional implementation, the stability threshold conditions are: the duration for which the absolute value of the synchronization state energy deviation component is less than a preset synchronization state energy threshold is greater than or equal to a preset time threshold; and the duration for which the absolute value of the equivalent potential state energy deviation component is less than a preset equivalent potential state energy threshold is greater than or equal to a preset time threshold.

[0017] Secondly, this invention provides a PCS grid-connected / off-grid seamless switching control device, comprising: a state energy deviation construction module, used to construct an equivalent state mapping model of the grid connection point based on preset virtual impedance parameters, mapping the voltage inconsistency of the grid connection point to the state energy deviation of the system; a state compensation generation module, used to compare the state energy deviation with its target balance value to generate a system state imbalance error signal; the error signal is processed by a dynamic adjustment unit to generate a corresponding state compensation quantity; a compensation module, used to inject the state compensation quantity into the state update equation of the virtual synchronous machine in a state feedforward manner, so that the internal state of the virtual synchronous machine naturally converges to be consistent with the state of the grid connection side while maintaining its original inertial characteristics and power droop characteristics; a closed-loop control module, used to control the PCS using a double closed-loop structure of voltage outer loop and current inner loop after the virtual synchronous machine state modulation is completed; and a grid connection module, used to determine that the states on both sides of the grid connection point have reached consistency when the state energy deviation simultaneously meets the stability threshold condition within a preset time window, and control the grid connection switch to close.

[0018] Thirdly, the present invention provides an electronic device, comprising: a memory and a processor, wherein the memory and the processor are communicatively connected to each other, the memory stores computer instructions, and the processor executes the computer instructions to perform the PCS and offline seamless handover control method of the first aspect or any corresponding embodiment described above.

[0019] Fourthly, the present invention provides a computer-readable storage medium storing computer instructions for causing a computer to execute the PCS and off-grid seamless handover control method of the first aspect or any corresponding embodiment described above.

[0020] Fifthly, the present invention provides a computer program product, including computer instructions, which are used to cause a computer to execute the PCS and off-grid seamless handover control method described in the first aspect or any corresponding embodiment above.

[0021] Beneficial effects: This invention constructs an equivalent state mapping model for the grid connection point by pre-setting virtual impedance parameters. This model accurately converts the inconsistencies in voltage amplitude and phase at the grid connection point into quantifiable state energy deviations within the system, avoiding synchronization deviations caused by ambiguous state perception in traditional control. The deviation is compared with the target equilibrium value to generate an error signal, which is then optimized by a dynamic adjustment unit to form a state compensation quantity. This compensation quantity is injected into the VSG state update equation via a state feedforward approach, maintaining the original inertia and power droop characteristics of the VSG while driving its internal states (power angle δ, angular velocity ω) to naturally converge towards the grid connection side. When the state energy deviation meets the stability threshold, the grid connection switch is closed. At this point, the voltage, frequency, and phase on both sides of the grid connection point have achieved high-precision matching, eliminating the inrush current during switching transients at the source and ensuring the safety of the PCS and grid equipment.

[0022] The introduction of virtual impedance in this invention allows for flexible adjustment of the PCS equivalent output impedance characteristics, effectively compensating for actual line impedance differences and avoiding power distribution imbalances and circulating current problems caused by grid impedance fluctuations in traditional control. In the dual closed-loop control structure, the outer voltage loop is responsible for maintaining a steady-state, error-free output voltage, while the inner current loop rapidly tracks reference commands. Combined with a state feedforward compensation mechanism, this forms a dual guarantee of "precise state synchronization + accurate output control." This design does not rely on a phase-locked loop (PLL), thus avoiding the risk of PLL instability in weak grids or voltage distortion scenarios. Furthermore, the dynamic adjustment unit adapts to state deviations under different operating conditions, enabling the system to maintain stable operation even with load fluctuations and changes in grid parameters, significantly improving the environmental adaptability and long-term reliability of the energy storage system.

[0023] The synergistic effect of state-energy deviation mapping and feedforward compensation in this invention ensures no voltage or frequency sags or abrupt changes during switching, reducing transient harmonic generation. The steady-state regulation capability of the outer voltage loop and the optimization of the equivalent output characteristics by the virtual impedance make the PCS output voltage closer to the characteristics of an ideal voltage source, enhancing the suppression of harmonic currents generated by nonlinear loads. Compared to traditional hard switching, this method avoids waveform distortion caused by abrupt changes in control parameters. Combined with the fast dynamic response of the dual closed loop, it can achieve wide-band harmonic suppression, significantly reducing the risk of power quality exceeding standards and meeting the power supply requirements of demanding energy storage applications. Attached Figure Description

[0024] To more clearly illustrate the specific embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the specific embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0025] Figure 1 This is a schematic diagram of the first type of PCS on-grid and off-grid seamless handover control method according to an embodiment of the present invention; Figure 2 This is a control block diagram of the PCS on-grid and off-grid seamless handover control method according to an embodiment of the present invention; Figure 3 These are the output voltage and current waveforms of the PCS during grid connection according to an embodiment of the present invention; Figure 4 The output voltage and current waveforms of the PCS when it is off-grid according to an embodiment of the present invention; Figure 5 These are the PCS output voltage and current waveforms when switching from off-grid to on-grid connection according to an embodiment of the present invention; Figure 6 The active and reactive power waveforms output by the PCS during off-grid to grid switching according to an embodiment of the present invention; Figure 7 These are the PCS output voltage and current waveforms before and after the off-grid to on-grid switching according to an embodiment of the present invention; Figure 8 These are the output voltage and current waveforms of the PCS during grid-connection and grid-off switching according to an embodiment of the present invention; Figure 9 These are the PCS output voltage and current waveforms before and after grid-connection to off-grid switching according to an embodiment of the present invention; Figure 10 The active and reactive power waveforms output by the PCS during grid connection and disconnection according to an embodiment of the present invention; Figure 11This is a schematic diagram of the hardware structure of an electronic device according to an embodiment of the present invention. Detailed Implementation

[0026] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0027] It is understood that before using the technical solutions disclosed in the various embodiments of the present invention, users should be informed of the types, scope of use, and usage scenarios of the personal information involved in the present invention and their authorization should be obtained in accordance with relevant laws and regulations through appropriate means.

[0028] According to an embodiment of the present invention, a PCS on-grid and off-grid seamless handover control method embodiment is provided. It should be noted that the steps shown in the flowchart in the accompanying drawings can be executed in a computer system such as a set of computer-executable instructions. Furthermore, although a logical order is shown in the flowchart, in some cases, the steps shown or described may be executed in a different order than that shown here.

[0029] This embodiment provides a PCS on-grid and off-grid seamless handover control method, such as Figure 1 As shown, it includes: Step S1: Construct an equivalent state mapping model of the grid connection point based on the preset virtual impedance parameters, and map the voltage inconsistency at the grid connection point into the state energy deviation within the system.

[0030] Specifically, refer to Figure 2 The state energy deviation includes at least: a first energy deviation component, used to characterize the synchronous state offset trend caused by the relative voltage changes on both sides of the grid connection point; and a second energy deviation component, used to characterize the equivalent potential deviation caused by the inconsistency in voltage amplitude on both sides of the grid connection point. These energy deviations do not directly correspond to actual physical power, but are only used as internal characterization variables for system state consistency.

[0031] Optionally, the process of obtaining the state energy deviation includes: when the grid connection point is disconnected, acquiring the voltage state quantities of the PCS output side and the grid side respectively, and characterizing them in the same coordinate system to obtain the synchronization state energy deviation component and the equivalent potential state energy deviation component; the synchronization state energy deviation component is used to characterize the inconsistency of voltage phase and rotation state on both sides of the grid connection point; the equivalent potential state energy deviation component is used to characterize the inconsistency of voltage amplitude on both sides of the grid connection point.

[0032] Based on the above, the output voltage vector on the PCS side is: (1) in, u inv This is the output voltage vector on the PCS side; u inv,α for α Output voltage on the PCS side of the shaft; u inv,β for β Output voltage on the PCS side of the shaft.

[0033] The grid-side voltage vector is: (2) in, u g The grid-side voltage vector; u g,α for α Axis grid side voltage; u g,β for β Axis grid side voltage.

[0034] Based on preset virtual impedance parameters Construct the state mapping relationship of the grid connection points and define the state energy deviation as: (1) Synchronization state energy deviation component, which is used to characterize the inconsistency of voltage phase and rotation state on both sides of the grid connection point. The synchronization state energy deviation component is: (3) in, E θ This represents the energy deviation component in the synchronization state.

[0035] The energy deviation component of the synchronization state reflects the relative rotation relationship between voltage vectors, and its magnitude characterizes the trend of the system's synchronization state deviation.

[0036] (2) Equivalent potential state energy deviation component, which is used to characterize the inconsistency of voltage amplitude on both sides of the grid connection point, is: (4) in, E θ This represents the energy deviation component of the equivalent potential state.

[0037] (3) The state energy deviation vector is obtained by combining equations (3) and (4) to obtain the system state energy deviation: (5) in, E state Let be the state energy deviation vector.

[0038] The state energy deviation vector does not correspond to the actual physical power or electromagnetic energy; it serves only as an internal control variable characterizing the consistency of the states on both sides of the grid connection point.

[0039] Step S2: Compare the state energy deviation with its target balance value to generate a system state imbalance error signal; after the error signal is processed by the dynamic adjustment unit, a corresponding state compensation quantity is generated.

[0040] Specifically, refer to Figure 2 The first state compensation is used to correct the instantaneous offset of the virtual synchronizer's angular velocity state, rather than directly changing its inertial or damping parameters; the second state compensation is used to correct the equivalent potential amplitude state inside the virtual synchronizer. The dynamic adjustment unit is a continuous adjustment structure, and its parameters are set independently of the virtual synchronizer's inertial parameters. The compensation components are injected into the virtual synchronizer's state update equation in a feedforward superposition manner, rather than acting directly on the modulation layer as external control commands.

[0041] The state energy deviation is compared with its target equilibrium value (zero) to obtain the state imbalance error signal: (6) in, e E This is the state imbalance error signal.

[0042] The error signal is processed by the dynamic adjustment unit to generate a synchronization compensation amount: (1) Angular velocity synchronization compensation amount (7) in, ω s This is the angular velocity synchronization compensation amount; k ωp This is the first adjustment parameter; E θ This refers to the energy deviation component in the synchronization state. k ωi This is the second adjustment parameter.

[0043] (2) Potential amplitude synchronization compensation amount (8) in, E s This is the amount of synchronous compensation for the potential amplitude; k ωpThis is the third adjustment parameter; E θ This represents the energy deviation component of the equivalent potential state. k ωi This is the fourth adjustment parameter. The adjustment parameter is set independently of the virtual synchronizer inertial parameters.

[0044] Step S3: Inject the state compensation amount into the state update equation of the virtual synchronous machine in a state feedforward manner, so that the internal state of the virtual synchronous machine naturally converges to be consistent with the state of the grid-connected side while maintaining the original inertial characteristics and power droop characteristics.

[0045] Specifically, refer to Figure 2 The state compensation amount is injected into the state update equation of the virtual synchronous machine in a state feedforward manner, so that the internal state of the virtual synchronous machine naturally converges to be consistent with the state of the grid-connected side while maintaining its original inertial characteristics and power droop characteristics. The synchronization compensation process does not introduce additional phase detection or phase-locked loop structures, nor does it change the original control mode of the virtual synchronous machine.

[0046] The original state equations inside the virtual synchronizer satisfy: (9) (10) in, ω vsg The angular velocity of the virtual synchronizer; T m For mechanical torque; T e Electromagnetic torque; ω 0 represents the rated angular velocity; δ vsg For the angle of attack.

[0047] This embodiment does not change the inertia and damping structure of the virtual synchronizer, but corrects its state variables through state feedforward: (1) The angular velocity state reconstruction equation is: (11) in, ω Angular velocity; ω vsg The angular velocity of the virtual synchronizer; ω s This is the angular velocity synchronization compensation amount; (2) The equivalent potential amplitude state reconstruction equation is: (12) in, E It is the equivalent potential amplitude; ω vsg This represents the equivalent potential amplitude of the virtual synchronous machine; E s This is the synchronous compensation amount for the potential amplitude.

[0048] Based on this, the synchronization compensation amount does not participate in the inertial integration process, nor does it change the physical equivalent parameters of the virtual synchronizer.

[0049] Step S4: After the virtual synchronous machine state modulation is completed, the PCS is controlled using a dual closed-loop structure of voltage outer loop and current inner loop.

[0050] Specifically, refer to Figure 2 After the virtual synchronizer's state modulation is completed, a voltage outer loop regulation structure is set up after the virtual synchronizer to achieve steady-state error-free control of the AC output voltage and improve waveform quality. The voltage outer loop uses a quasi-proportional resonant (PR) controller to adjust the deviation between the voltage command output by the virtual synchronizer and the actual output voltage, so as to suppress the fundamental steady-state error and reduce harmonic components. The quasi-PR voltage outer loop only serves as a voltage steady-state regulation and waveform optimization unit. Its control output is used to correct the voltage reference quantity after the virtual synchronizer's state modulation, and does not participate in the determination and regulation of the system synchronization state. The synchronization process is still dominated by the aforementioned state energy deviation mapping and virtual synchronizer state evolution mechanism, thereby avoiding interference from multiple control loops on the system's dynamic characteristics.

[0051] Optionally, after the virtual synchronizer state modulation is complete, a voltage outer loop control structure is constructed. The voltage reference value output by the virtual synchronizer is used. u With actual output voltage u The deviation between them is taken as the input, and a quasi-PR controller is used. The transfer function of the quasi-PR controller is: (13) Generate current reference signal: (13) in, i This is the current reference signal.

[0052] The voltage outer loop is only used for steady-state error-free regulation and waveform quality optimization, and does not participate in the determination and regulation of the system synchronization state.

[0053] Specifically, refer to Figure 2A current inner loop is set after the voltage outer loop to convert the virtual synchronizer state evolution results and voltage modulation results into actual current output. The current inner loop adopts a proportional control structure, and its proportional coefficient is adaptively adjusted according to the system state synchronization degree. Specifically, the proportional coefficient is related to the state energy deviation or the internal state variables of the virtual synchronizer, so that the current regulation capability changes dynamically with the system synchronization state: when the system state energy deviation is large, the proportional gain of the current loop is increased to enhance the current execution capability and accelerate state convergence; when the system state energy deviation decreases, the proportional gain of the current loop is decreased to weaken the transient regulation intensity and avoid current surges during grid connection. Since the current inner loop does not contain integral or resonant elements, its regulation process does not introduce additional energy storage effects, thereby ensuring the dominance of the virtual synchronizer's inertia and damping characteristics in the system dynamics, and realizing the decoupling between system state modulation and physical execution.

[0054] Optionally, a current inner loop control structure is set after the voltage outer loop. The current inner loop adopts proportional control, and its control law is: (14) Among them, proportional gain k p ( i Adaptive adjustment based on the degree of system state synchronization. k p ( i The calculation formula is as follows: (15) The state energy deviation is defined as follows: (16) The proportional gain can be expressed as: (17) When the system state energy deviation is large, the proportional gain of the current loop is increased to enhance the execution capability; when the state tends to be consistent, the proportional gain is reduced to suppress grid-connected transient impacts.

[0055] Since the inner current loop does not contain integral or resonant elements, its regulation process does not introduce additional energy storage effects, thus ensuring the dominant role of the virtual synchronous machine's inertial and damping characteristics in the system dynamics.

[0056] Step S5: When the state energy deviation simultaneously meets the stability threshold condition within the preset time window, it is determined that the states on both sides of the grid connection point have reached consistency, and the grid connection switch is closed.

[0057] Specifically, refer to Figure 2When the state energy deviation simultaneously meets the stability threshold condition within a preset time window, it is determined that the states on both sides of the grid connection point are consistent, and the grid connection switch is closed. After the switch is closed, the virtual synchronous machine continues to operate according to the existing control strategy to achieve a seamless switching between grid connection and disconnection. The stability threshold is set according to the system capacity level and grid connection standard.

[0058] Optionally, the stability threshold condition is: the absolute value of the synchronization state energy deviation component is less than a preset synchronization state energy threshold. ε θ The duration is greater than or equal to a preset time threshold; the absolute value of the equivalent potential state energy deviation component is less than the preset equivalent potential state energy threshold. ε U The duration is greater than or equal to a preset time threshold. Specifically: When the state energy deviation is within a preset time window T w (i.e., within the preset time threshold) it must meet: (18) (19) And duration t satisfy: (20) If the states on both sides of the grid connection point are consistent, the grid connection switch will be closed.

[0059] After the grid connection switch is closed, the virtual synchronous machine continues to operate according to the existing control strategy, realizing a seamless switching between grid connection and disconnection.

[0060] In a practical application scenario, simulation verification was performed based on the above method, and the simulation waveform is as follows. Figures 3-10 As shown, Figure 3 The output voltage and current waveforms of the PCS during grid connection are shown. Figure 4 The output voltage and current waveforms of the PCS when it is off-grid. Figure 5 The output voltage and current waveforms of the PCS when switching from off-grid to on-grid. Figure 6 The active and reactive power waveforms output by the PCS when switching from off-grid to grid-connected are shown. Figure 7 The output voltage and current waveforms of the PCS before and after the off-grid to on-grid switching are shown. Figure 8 The output voltage and current waveforms of the PCS during grid-connection and off-grid switching are shown. Figure 9 The output voltage and current waveforms of the PCS before and after the grid-connected to off-grid switching are shown. Figure 10 The active and reactive power waveforms output by the PCS when switching from grid connection to off-grid.

[0061] This embodiment also provides a PCS on-grid and off-grid seamless handover control device, which is used to implement the above embodiments and preferred embodiments, and will not be repeated as already described. As used below, the term "module" can be a combination of software and / or hardware that implements a predetermined function. Although the device described in the following embodiments is preferably implemented in software, hardware implementation, or a combination of software and hardware, is also possible and contemplated.

[0062] This embodiment provides a PCS (Prevention and Control System) on-grid / off-grid seamless handover control device, the device comprising: The State Energy Deviation Quantity Construction Module is used to construct an equivalent state mapping model of the grid connection point based on preset virtual impedance parameters, and to map the voltage inconsistency at the grid connection point into the state energy deviation quantity inside the system. The state compensation quantity generation module is used to compare the state energy deviation with its target balance value and generate a system state imbalance error signal; after the error signal is processed by the dynamic adjustment unit, the corresponding state compensation quantity is generated. The compensation module is used to inject the state compensation amount into the state update equation of the virtual synchronous machine in a state feedforward manner, so that the internal state of the virtual synchronous machine naturally converges to be consistent with the state of the grid-connected side while maintaining the original inertial characteristics and power droop characteristics. The closed-loop control module is used to control the PCS using a dual closed-loop structure of voltage outer loop and current inner loop after the virtual synchronous machine state modulation is completed. The grid connection module is used to determine that the states on both sides of the grid connection point are consistent when the state energy deviation meets the stability threshold condition simultaneously within a preset time window, and then control the grid connection switch to close.

[0063] The PCS on-grid / off-grid seamless handover control device provided in this embodiment of the invention can execute the PCS on-grid / off-grid seamless handover control method provided in any embodiment of the invention, and has the corresponding functional modules and beneficial effects of the method. Further functional descriptions of the above modules and units are the same as in the corresponding embodiments described above, and will not be repeated here.

[0064] Figure 11 This is a schematic diagram of the structure of an electronic device provided in an embodiment of the present invention.

[0065] The following is a detailed reference. Figure 11The diagram illustrates a structural schematic suitable for implementing an electronic device according to embodiments of the present invention. The electronic device may include a processor (e.g., a central processing unit, graphics processor, etc.) 001, which can perform various appropriate actions and processes according to a program stored in read-only memory (ROM) 002 or a program loaded from memory 008 into random access memory (RAM) 003. The RAM 003 also stores various programs and data required for the operation of the electronic device. The processor 001, ROM 002, and RAM 003 are interconnected via bus 004. An input / output (I / O) interface 005 is also connected to bus 004.

[0066] Typically, the following devices can be connected to I / O interface 005: input devices 006 including, for example, touchscreens, touchpads, keyboards, mice, cameras, microphones, accelerometers, gyroscopes, etc.; output devices 007 including, for example, liquid crystal displays (LCDs), speakers, vibrators, etc.; memory devices 008 including, for example, magnetic tapes, hard disks, etc.; and communication devices 009. Communication device 009 allows electronic devices to exchange data via wireless or wired communication with other devices. Although Figure 11 Electronic devices with various devices are shown, but it should be understood that it is not required to implement or have all of the devices shown, and more or fewer devices may be implemented or have instead.

[0067] In particular, according to embodiments of the present invention, the processes described above with reference to the flowcharts can be implemented as computer software programs. For example, embodiments of the present invention include a computer program product comprising a computer program carried on a non-transitory computer-readable medium, the computer program containing program code for performing the methods shown in the flowcharts. In such embodiments, the computer program can be downloaded and installed from a network via communication device 009, or installed from memory 008, or installed from ROM 002. When the computer program is executed by processor 001, it performs the functions defined in the PCS and off-network seamless handover control method of the embodiments of the present invention.

[0068] Figure 11 The electronic device shown is merely an example and should not be construed as limiting the functionality and scope of use of the embodiments of the present invention.

[0069] This invention also provides a computer-readable storage medium. The methods described above according to embodiments of the invention can be implemented in hardware or firmware, or implemented as computer code that can be recorded on a storage medium, or implemented as computer code downloaded via a network and originally stored on a remote storage medium or a non-transitory machine-readable storage medium and then stored on a local storage medium. Thus, the methods described herein can be processed by software stored on a storage medium using a general-purpose computer, a dedicated processor, or programmable or dedicated hardware. The storage medium can be a magnetic disk, optical disk, read-only memory, random access memory, flash memory, hard disk, or solid-state drive, etc.; further, the storage medium can also include combinations of the above types of memory. It is understood that computers, processors, microprocessor controllers, or programmable hardware include storage components capable of storing or receiving software or computer code. When the software or computer code is accessed and executed by the computer, processor, or hardware, the PCS and off-network seamless handover control method shown in the above embodiments is implemented.

[0070] A portion of this invention can be applied as a computer program product, such as computer program instructions, which, when executed by a computer, can invoke or provide the methods and / or technical solutions according to the invention through the operation of the computer. Those skilled in the art will understand that the forms in which computer program instructions exist in a computer-readable medium include, but are not limited to, source files, executable files, installation package files, etc. Correspondingly, the ways in which computer program instructions are executed by a computer include, but are not limited to: the computer directly executing the instructions, or the computer compiling the instructions and then executing the corresponding compiled program, or the computer reading and executing the instructions, or the computer reading and installing the instructions and then executing the corresponding installed program. Here, the computer-readable medium can be any available computer-readable storage medium or communication medium accessible to a computer.

[0071] Although embodiments of the invention have been described in conjunction with the accompanying drawings, those skilled in the art can make various modifications and variations without departing from the spirit and scope of the invention, and such modifications and variations all fall within the scope defined by the appended claims.

Claims

1. A PCS (Preinstallation Control System) on-grid and off-grid seamless handover control method, characterized in that, include: Based on preset virtual impedance parameters, an equivalent state mapping model of the grid connection point is constructed, which maps the voltage inconsistency at the grid connection point into the state energy deviation within the system. The state energy deviation is compared with its target equilibrium value to generate a system state imbalance error signal. After the error signal is processed by the dynamic adjustment unit, a corresponding state compensation quantity is generated; The state compensation amount is injected into the state update equation of the virtual synchronous machine in a state feedforward manner, so that the internal state of the virtual synchronous machine naturally converges to be consistent with the state of the grid-connected side while maintaining the original inertial characteristics and power droop characteristics. After the virtual synchronous machine state modulation is completed, the PCS is controlled using a dual closed-loop structure of voltage outer loop and current inner loop. When the state energy deviation simultaneously meets the stability threshold condition within a preset time window, it is determined that the states on both sides of the grid connection point have reached consistency, and the grid connection switch is controlled to close.

2. The PCS on-grid / off-grid seamless handover control method according to claim 1, characterized in that, The process of obtaining the state energy deviation includes: When the grid connection point is disconnected, the voltage state quantities of the PCS output side and the grid side are obtained respectively, and characterized in the same coordinate system to obtain the synchronization state energy deviation component and the equivalent potential state energy deviation component. The synchronous state energy deviation component is used to characterize the inconsistency of voltage phase and rotation state on both sides of the grid connection point. The equivalent potential state energy deviation component is used to characterize the inconsistency of voltage amplitude on both sides of the grid connection point.

3. The PCS on-grid / off-grid seamless handover control method according to claim 1, characterized in that, The state compensation amount includes: angular velocity synchronization compensation amount and potential amplitude synchronization compensation amount; The formula for calculating the angular velocity synchronization compensation is: in, ω s This is the angular velocity synchronization compensation amount; k ωp This is the first adjustment parameter; E θ This refers to the energy deviation component in the synchronization state. k ωi This is the second adjustment parameter; The formula for calculating the synchronous compensation amount of potential amplitude is: in, E s This is the amount of synchronous compensation for the potential amplitude; k ωp This is the third adjustment parameter; E θ This represents the energy deviation component of the equivalent potential state. k ωi This is the fourth adjustment parameter.

4. The PCS on-grid / off-grid seamless handover control method according to claim 1, characterized in that, After injecting the state compensation amount into the state update equation of the virtual synchronous machine in a state feedforward manner, the angular velocity state reconstruction equation and the equivalent potential amplitude state reconstruction equation are obtained. The angular velocity state reconstruction equation is: in, ω Angular velocity; ω vsg The angular velocity of the virtual synchronizer; ω s This is the angular velocity synchronization compensation amount; The equivalent potential amplitude state reconstruction equation is: in, E It is the equivalent potential amplitude; ω vsg This represents the equivalent potential amplitude of the virtual synchronous machine; E s This is the synchronous compensation amount for the potential amplitude.

5. The PCS on-grid / off-grid seamless handover control method according to claim 1, characterized in that, Voltage outer loop control includes: The voltage difference is obtained by subtracting the voltage reference value output by the virtual synchronizer from the actual output voltage. Based on the voltage difference, a quasi-PR controller is used to generate a current reference signal.

6. The PCS on-grid / off-grid seamless handover control method according to claim 5, characterized in that, Current inner loop control includes: Based on the current reference signal, a voltage reference signal is obtained using proportional control.

7. The PCS on-grid / off-grid seamless handover control method according to claim 2, characterized in that, The stability threshold condition is: The duration during which the absolute value of the synchronization state energy deviation component is less than the preset synchronization state energy threshold is greater than or equal to the preset time threshold. The duration during which the absolute value of the equivalent potential state energy deviation component is less than the preset equivalent potential state energy threshold is greater than or equal to the preset time threshold.

8. A PCS (Preinstallation Control System) on-grid / off-grid seamless switching control device, characterized in that, The device includes: The State Energy Deviation Quantity Construction Module is used to construct an equivalent state mapping model of the grid connection point based on preset virtual impedance parameters, and to map the voltage inconsistency at the grid connection point into the state energy deviation quantity inside the system. The state compensation quantity generation module is used to compare the state energy deviation with its target balance value to generate a system state imbalance error signal; after the error signal is processed by the dynamic adjustment unit, a corresponding state compensation quantity is generated. The compensation module is used to inject the state compensation amount into the state update equation of the virtual synchronous machine in a state feedforward manner, so that the internal state of the virtual synchronous machine naturally converges to be consistent with the state of the grid-connected side while maintaining the original inertial characteristics and power droop characteristics. The closed-loop control module is used to control the PCS using a dual closed-loop structure of voltage outer loop and current inner loop after the virtual synchronous machine state modulation is completed. The grid connection module is used to determine that the states on both sides of the grid connection point are consistent when the state energy deviation meets the stability threshold condition simultaneously within a preset time window, and then control the grid connection switch to close.

9. An electronic device, characterized in that, include: A memory and a processor are communicatively connected, the memory stores computer instructions, and the processor executes the computer instructions to perform the PCS and off-grid seamless handover control method as described in any one of claims 1 to 7.

10. A computer-readable storage medium, characterized in that, The computer-readable storage medium stores computer instructions for causing the computer to execute the PCS and off-grid seamless handover control method as described in any one of claims 1 to 7.

11. A computer program product, characterized in that, Includes computer instructions for causing a computer to execute the PCS and off-grid seamless handover control method as described in any one of claims 1 to 7.

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