Photovoltaic power generation grid-connected control method and device based on hybrid network construction strategy

Abstract

The invention discloses a photovoltaic power generation grid-connected control method and device based on a hybrid network construction strategy. The method comprises the steps of performing virtual frequency modulation control based on acquired real-time operation data of a power grid and a photovoltaic power generation system, and outputting additional reference power; performing power synchronization control based on the additional reference power and the real-time operation data, outputting a first internal potential virtual angular velocity, performing phase-locked loop control based on the real-time operation data, and outputting a second internal potential virtual angular velocity; performing hybrid synchronous control based on the first internal potential virtual angular velocity and the second internal potential virtual angular velocity, and outputting an internal potential virtual phase angle; performing virtual excitation control based on the real-time operation data, and outputting a virtual internal potential amplitude; and carrying out voltage phasor amplitude limiting based on the internal potential virtual phase angle and the virtual internal potential amplitude, outputting a voltage reference value, carrying out virtual impedance amplitude limiting based on the voltage reference value, and outputting a final generation value of a dq-axis component of the virtual internal potential to realize grid-connected control.

Description

Technical Field

[0001] The present invention relates to the technical field of new energy grid-connected control, and more specifically, to a photovoltaic power generation grid-connected control method and device based on a hybrid grid construction strategy. Background Art

[0002] Photovoltaic power generation, one of the most mature and promising renewable energy technologies, has maintained strong growth momentum in recent years. However, the randomness, intermittency, and volatility of photovoltaic power generation, coupled with the weak support, low damping, and low inertia associated with large-scale grid integration of renewable energy, pose challenges for the safe and stable operation of power systems. Therefore, efficient and reliable grid-connected control strategies are crucial for improving the efficiency of photovoltaic power generation.

[0003] Traditional photovoltaic converter control strategies rely on a phase-locked loop (PLL) to measure grid phase information for synchronization, using the Park transform to decouple active and reactive power. Power output is controlled by manipulating the amplitude and phase of the injected current, resulting in a current source-like behavior. With the advancement of grid-connected technologies, integrated photovoltaic and energy storage devices, which exhibit voltage source characteristics, have also been researched. To accommodate the rapid growth of new energy photovoltaic power generation equipment, addressing the stability challenges of both strong and weak grids has become a pressing technical challenge. Summary of the Invention

[0004] In view of the deficiencies in the prior art, the present invention provides a photovoltaic power generation grid-connected control method and device based on a hybrid grid construction strategy.

[0005] According to one aspect of the present invention, a photovoltaic power generation grid-connected control method based on a hybrid grid construction strategy is provided, comprising:

[0006] Based on the real-time operating data of the power grid and photovoltaic power generation system, virtual frequency regulation control is performed to output additional reference power;

[0007] Performing power synchronization control based on the additional reference power and the real-time operation data to output a first internal potential virtual angular velocity, and performing phase-locked loop control based on the real-time operation data to output a second internal potential virtual angular velocity;

[0008] Perform hybrid synchronous control based on the first internal potential virtual angular velocity and the second internal potential virtual angular velocity, and output the internal potential virtual phase angle;

[0009] Perform virtual excitation control based on real-time operating data and output virtual internal potential amplitude;

[0010] The voltage phasor is limited based on the virtual phase angle and amplitude of the internal potential, and a voltage reference value is output. The virtual impedance is limited based on the voltage reference value, and the final generated value of the dq axis component of the virtual internal potential is output to achieve grid-connected control.

[0011] Optionally, the real-time operation data includes: the three-phase current I output by the inverter gabc With the three-phase terminal voltage U gabc , the measured frequency of the power grid ω g , the inverter actually outputs active power P.

[0012] Optionally, the additional reference power is calculated as follows:

[0013]

[0014] Where ΔP ref is the additional reference power; ω0 is the reference frequency; ω g is the measured frequency calculated by the phase-locked loop; ω deadzone To set the frequency dead zone; K p is the frequency modulation coefficient.

[0015] Optionally, the expression for power synchronization control is:

[0016]

[0017] Among them, T j is the virtual inertia time constant; Δω PC Output the first internal potential virtual angular velocity for the converter power synchronization control link; P m is the input mechanical power corresponding to the traditional synchronous machine; P is the actual output active power of the converter, which is determined by the active reference instruction P ref and additional reference power ΔP ref Composition; K D is the deviation magnification, T w is the time constant of the DC isolation link, T3 and T4 are the time constants of the phase shift link, D is the damping coefficient, and s is the Laplace operator.

[0018] Optionally, the expression for the phase-locked loop control is:

[0019]

[0020] Among them, Δω PLL Output the second internal potential virtual angular velocity for the converter phase-locked synchronous control link; T PLL K is the phase-locked synchronization delay time constant; pPLL is the proportional control coefficient of the phase-locked loop; K iPLL is the integral control coefficient of the phase-locked loop; U gq is the q-axis component of the grid-connected point voltage.

[0021] Optionally, the expression of virtual excitation control is:

[0022]

[0023] Where, E m is the virtual internal potential amplitude of the converter output; K is the regulator gain; K v is the proportional integral selection factor; T1 and T2 are the time constants of the voltage regulator; V * is the reference voltage of the excitation voltage regulator; V is the calculated actual voltage signal of the excitation voltage regulator; i gd The d-axis current component injected into the grid by the converter; T' d0 is the time constant of the simulated generator excitation link; s is the Laplace operator; X d and X' d They simulate the direct-axis synchronous reactance and transient reactance of the generator respectively.

[0024] Optionally, the virtual internal potential constraint condition for voltage phasor limiting is:

[0025]

[0026] Where U cd 、U cq are the dq axis components of the virtual internal potential respectively; U gd 、U gq are the dq axis components of the grid connection point voltage respectively; L is the filter inductance; I dLim , I qLim are the dq axis component amplitude limits of the converter output current respectively; ω is the grid frequency.

[0027] Optionally, the expression of the virtual impedance limit is:

[0028]

[0029] Where, The final generated value of the virtual internal potential dq axis component, U cdqref is the intermediate reference value of the virtual internal potential dq axis component; I gdq is the dq axis component of the converter output current, I dqLim deadzone K is the setting value of the converter virtual impedance switching dead zone; pILim K is the proportional coefficient of the virtual impedance limiting link; iILim is the integral coefficient of the virtual impedance limiting link; s is the Laplace operator.

[0030] According to another aspect of the present invention, a photovoltaic power generation grid-connected control device based on a hybrid grid construction strategy is provided, comprising:

[0031] A first control module is configured to perform virtual frequency modulation control based on the acquired real-time operating data of the power grid and the photovoltaic power generation system, and output additional reference power;

[0032] a second control module, configured to perform power synchronization control based on the additional reference power and the real-time operation data to output a first internal potential virtual angular velocity, and perform phase-locked loop control based on the real-time operation data to output a second internal potential virtual angular velocity;

[0033] a third control module, configured to perform hybrid synchronous control based on the first internal potential virtual angular velocity and the second internal potential virtual angular velocity, and output an internal potential virtual phase angle;

[0034] a fourth control module, configured to perform virtual excitation control based on real-time operating data and output a virtual internal potential amplitude;

[0035] The limiting module is used to limit the voltage phasor based on the virtual phase angle and amplitude of the internal potential, output the voltage reference value, and limit the virtual impedance based on the voltage reference value, output the final generated value of the dq axis component of the virtual internal potential, and realize grid-connected control.

[0036] According to another aspect of the present invention, a computer-readable storage medium is provided, wherein the storage medium stores a computer program, and the computer program is used to execute the method according to any one of the above aspects of the present invention.

[0037] According to another aspect of the present invention, an electronic device is provided, comprising: a processor; a memory for storing instructions executable by the processor; and the processor for reading the executable instructions from the memory and executing the instructions to implement the method described in any one of the above aspects of the present invention.

[0038] Therefore, the present invention proposes a photovoltaic power generation grid-connected control method based on a hybrid grid construction strategy, which performs control modeling based on the third-order model of the synchronous generator, adopts virtual excitation control to generate the virtual internal potential amplitude, and adopts a hybrid synchronization method of phase-locked loop and power synchronization control to generate the virtual internal potential phase angle; at the same time, direct voltage control is realized by combining virtual impedance and voltage phasor limitation, which can avoid dependence on the phase-locked loop, meet the flexible adjustment requirements of frequency and voltage in a multi-short-circuit ratio access environment, and effectively improve the stability of the "dual-high" power system. BRIEF DESCRIPTION OF THE DRAWINGS

[0039] A more complete understanding of exemplary embodiments of the present invention may be obtained by referring to the following drawings:

[0040] Figure 1 1 is a flow chart of a photovoltaic power generation grid-connected control method based on a hybrid grid construction strategy provided by an exemplary embodiment of the present invention;

[0041] Figure 2 is a control block diagram of a photovoltaic power generation system converter provided by an exemplary embodiment of the present invention;

[0042] Figure 3 1 is a schematic structural diagram of a photovoltaic power generation grid-connected control device based on a hybrid grid-connecting strategy provided by an exemplary embodiment of the present invention;

[0043] Figure 4 This is a structure of an electronic device provided by an exemplary embodiment of the present invention. DETAILED DESCRIPTION

[0044] Below, the exemplary embodiments according to the present invention will be described in detail with reference to the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, rather than all the embodiments of the present invention, and it should be understood that the present invention is not limited to the exemplary embodiments described herein.

[0045] It should be noted that the relative arrangement of components and steps, the numerical expressions and numerical values set forth in these embodiments do not limit the scope of the present invention unless specifically stated otherwise.

[0046] Those skilled in the art will understand that the terms "first" and "second" in the embodiments of the present invention are only used to distinguish different steps, devices or modules, and neither represent any specific technical meaning nor indicate the necessary logical order between them.

[0047] It should also be understood that, in the embodiments of the present invention, “a plurality of” may refer to two or more than two, and “at least one” may refer to one, two or more than two.

[0048] It should also be understood that any component, data or structure mentioned in the embodiments of the present invention can generally be understood as one or more, unless explicitly limited or otherwise indicated in the context.

[0049] In addition, the term "and / or" in this invention merely describes an association relationship between related objects, indicating that three possible relationships exist. For example, A and / or B can represent: A exists alone, A and B exist simultaneously, and B exists alone. Furthermore, the character " / " in this invention generally indicates that the related objects are in an "or" relationship.

[0050] It should also be understood that the description of the various embodiments of the present invention focuses on the differences between the various embodiments, and the same or similar aspects thereof can be referenced with each other. For the sake of brevity, they will not be described one by one.

[0051] At the same time, it should be understood that for the convenience of description, the sizes of the various parts shown in the drawings are not drawn according to the actual proportional relationship.

[0052] The following description of at least one exemplary embodiment is merely illustrative in nature and is in no way intended to limit the invention, its application, or uses.

[0053] Technologies, methods, and equipment known to ordinary technicians in the relevant art may not be discussed in detail, but where appropriate, the technologies, methods, and equipment should be considered part of the specification.

[0054] It should be noted that like reference numerals and letters refer to like items in the following figures, and therefore, once an item is defined in one figure, it need not be further discussed in subsequent figures.

[0055] Embodiments of the present invention can be applied to electronic devices such as terminal devices, computer systems, and servers, and can operate in conjunction with numerous other general-purpose or specialized computing system environments or configurations. Examples of well-known terminal devices, computing systems, environments, and / or configurations suitable for use with terminal devices, computer systems, servers, and other electronic devices include, but are not limited to, personal computer systems, server computer systems, thin clients, thick clients, handheld or laptop devices, microprocessor-based systems, set-top boxes, programmable consumer electronics, network personal computers, minicomputer systems, mainframe computer systems, and distributed cloud computing technology environments including any of the above.

[0056] Electronic devices such as terminal devices, computer systems, and servers can be described in the general context of computer system-executable instructions (such as program modules) executed by a computer system. Generally, program modules can include routines, programs, object programs, components, logic, data structures, etc., which perform specific tasks or implement specific abstract data types. Computer systems / servers can be implemented in a distributed cloud computing environment, where tasks are performed by remote processing devices linked via a communication network. In a distributed cloud computing environment, program modules can be located on local or remote computing system storage media, including storage devices.

[0057] Exemplary Methods

[0058] Figure 1 This is a flow chart of a photovoltaic power generation grid-connected control method based on a hybrid grid-connected strategy provided by an exemplary embodiment of the present invention. This embodiment can be applied to electronic devices, such as Figure 1 As shown, the photovoltaic power generation grid-connected control method 100 based on the hybrid grid construction strategy includes the following steps:

[0059] Step 101: Perform virtual frequency modulation control based on the acquired real-time operating data of the power grid and photovoltaic power generation system, and output additional reference power;

[0060] Step 102: Perform power synchronization control based on the additional reference power and the real-time operation data to output a first internal potential virtual angular velocity, and perform phase-locked loop control based on the real-time operation data to output a second internal potential virtual angular velocity.

[0061] Step 103, performing hybrid synchronous control based on the first internal potential virtual angular velocity and the second internal potential virtual angular velocity, and outputting the internal potential virtual phase angle;

[0062] Step 104 , performing virtual excitation control based on real-time operation data and outputting a virtual internal potential amplitude;

[0063] Step 105 , performing voltage phasor limiting based on the virtual phase angle and amplitude of the internal potential, outputting a voltage reference value, performing virtual impedance limiting based on the voltage reference value, outputting a final generated value of the virtual internal potential dq axis component, and realizing grid-connected control.

[0064] Specifically, to address the shortcomings of existing technologies, the present invention proposes a photovoltaic power generation grid-connected control method based on a hybrid grid-connected strategy. Control modeling is performed based on a third-order model of a synchronous generator, using virtual excitation control to generate the virtual internal potential amplitude, and a hybrid synchronization method combining phase-locked loop (PLL) and power synchronization control to generate the virtual internal potential phase angle. Direct voltage control is achieved by combining virtual impedance and voltage phasor limiting, avoiding reliance on the PLL, meeting the requirements for flexible frequency and voltage regulation in a multi-short-circuit ratio access environment, and effectively improving the stability of the "double-high" power system.

[0065] refer to Figure 2 As shown, the control strategy includes the following steps:

[0066] (1) Detect the real-time operating status and operating data of the power grid and photovoltaic power generation system: the three-phase current I output by the inverter gabc With the three-phase terminal voltage U gabc , the measured frequency of the power grid ω g , the actual output active power P of the inverter. Collect the three-phase current I output by the inverter gabc With the three-phase terminal voltage U gabc And perform Park transformation based on the internal potential virtual phase angle θ to obtain the current I in the dq rotating coordinate system gdq With voltage U gdq The actual output active power P of the photovoltaic inverter is obtained through the power calculation module, which is calculated as follows:

[0067]

[0068] Among them, U gd 、U gq is the dq axis component of the inverter terminal voltage; I gd , I gq They are the d and q axis components of the inverter output current respectively.

[0069] (2) Virtual frequency regulation control link. Simulate the speed regulator characteristics of the synchronous generator set prime mover and simplify its active power-frequency characteristics. The converter detects the actual frequency of the power grid through the phase-locked loop, compares it with the reference frequency, and passes through the dead zone control module. If the speed deviation exceeds the set dead zone, the output is the deviation amount exceeding the dead zone; otherwise, the output is 0. The output frequency deviation is multiplied by the frequency modulation coefficient to obtain the additional reference power. The virtual frequency regulation control model is expressed as follows:

[0070]

[0071] Where ΔP ref is the additional reference power; ω0 is the reference frequency; ω g is the measured frequency calculated by the phase-locked loop; ω deadzone To set the frequency dead zone; K p is the frequency modulation coefficient, which can be flexibly selected to meet system requirements.

[0072] (3) Power synchronization control link. Simulate the synchronous generator rotor motion equation, introduce inertia and damping links in the control, and enhance the active support capability of the converter. The sum of the additional reference power obtained by the virtual frequency modulation control link and the active reference instruction is used as the converter virtual mechanical power, and the actual output active power of the converter is used as the virtual electromagnetic power. The difference between the two is obtained after passing through the power synchronization control link to obtain the converter virtual speed. The control model is expressed as follows:

[0073]

[0074] Among them, T j is the virtual inertia time constant, which can be flexibly selected to meet system requirements and equipment operating conditions; Δω PC Output the first internal potential virtual angular velocity for the converter power synchronization control link; P m is the input mechanical power corresponding to the traditional synchronous machine; P is the actual output active power of the converter, which is determined by the active reference instruction P ref and additional reference power ΔP ref The damping feedback consists of two parts. The first part consists of an amplification link, which feeds back the steady-state frequency deviation. D is the damping coefficient. The second part consists of an amplification link, a DC isolation link, and a lead-lag link in series, which only feeds back the transient frequency deviation. K D is the deviation magnification, T w is the time constant of the DC isolation link, T3 and T4 are the time constants of the phase shift link.

[0075] Since photovoltaic power generation systems are often operated in maximum power point tracking (MPPT) mode, the virtual mechanical power P of photovoltaic power generation systems with or without energy storage is mThere are different values. When the photovoltaic power generation system is equipped with energy storage devices and has active backup, the active reference value is the photovoltaic MPPT power (P ref =P MPPT ), the photovoltaic power generation system participates in the primary frequency modulation of the system through energy storage charge and discharge control, and the output virtual mechanical power is:

[0076] P m =P MPPT +ΔP ref

[0077] When the photovoltaic power generation system has no energy storage device and no active backup link, the photovoltaic system power reduction control is set, that is, P ref =P MPPT -ΔP, ΔP is the power reduction quota. At this time, the photovoltaic system output virtual mechanical power is:

[0078]

[0079] (4) Phase-locked synchronization control link. The phase-locked loop collects the grid connection point voltage, locks and tracks the grid connection point phase, and realizes the synchronous operation of the unit and the grid. The control model is expressed as follows:

[0080]

[0081] Among them, Δω PLL Output the second internal potential virtual angular velocity for the converter phase-locked synchronous control link; T PLL K is the phase-locked synchronization delay time constant; pPLL is the proportional control coefficient of the phase-locked loop; K iPLL is the integral control coefficient of the phase-locked loop; U gq is the q-axis component of the grid-connected point voltage.

[0082] (5) Hybrid synchronous control link. Based on the difference between the power synchronous control link and the phase-locked synchronous control link, a hybrid coefficient is introduced to fuse the output angular velocity of the power synchronous link with the output angular velocity of the phase-locked synchronous link to achieve hybrid synchronous control. The control model is expressed as follows:

[0083]

[0084] Where θ is the virtual phase angle of the internal potential; C PLL is the phase-locked synchronous control mixing coefficient; C PC The power synchronization control mixing coefficient should be able to be adaptively adjusted according to the short-circuit ratio of the access system, and the value range of the mixing coefficient under different short-circuit ratios can be determined by combining various oscillation risk instability criteria.

[0085] (6) Virtual excitation control link. Simulate the characteristics of the synchronous generator excitation system and introduce the electromagnetic equations in the third-order practical model of the synchronous generator to accurately simulate the excitation dynamic characteristics:

[0086]

[0087] Among them, T' d0 is the time constant of the excitation winding; E' q is the transient potential; E qe is the forced no-load electromotive force that is linearly related to the excitation voltage; i d is the d-axis current component; x d is the synchronous reactance; x' d is the d-axis transient reactance.

[0088] First, the voltage and current at the output of the converter are collected, and after the difference adjustment link, the actual voltage signal of the virtual excitation voltage regulator is obtained:

[0089]

[0090] Where V is the calculated actual voltage signal of the virtual excitation voltage regulator; T R is the filter time constant; U g is the grid connection point voltage; I g is the converter output current; R C is the differential resistance, X C The differential reactance is adjusted to give the virtual control system an appropriate differential characteristic. The introduction of this differential adjustment link can prevent oscillation caused by the simultaneous adjustment of the bus voltage by parallel-operating generating equipment.

[0091] The actual value of the voltage signal is then compared with the reference value, and the series PID control method is used to adjust the gain and dynamic characteristics of the virtual excitation control link. The control model is expressed as follows:

[0092]

[0093] Among them, E m is the virtual internal potential amplitude of the converter output, corresponding to the transient potential E' q ; K is the regulator gain; K v is the proportional integral selection factor; T1 and T2 are the time constants of the voltage regulator; V * is the reference voltage of the excitation voltage regulator; V is the calculated actual voltage signal of the excitation voltage regulator; i gd The d-axis current component injected into the grid by the converter corresponds to i d .

[0094] (7) Voltage phasor limiting link. The fault current is suppressed by limiting the voltage amplitude and phase difference between the virtual internal potential and the grid connection point voltage. Taking the self-generated phase of the converter as the reference coordinate system, the grid connection point voltage, virtual internal potential, and converter output current are projected onto the reference coordinate system to obtain the converter output current constraint condition:

[0095]

[0096] Among them, I gd , I gq are the dq axis components of the converter output current respectively; I dLim , I qLim are the dq axis component amplitude limits of the converter output current respectively; I max is the total current limit value.

[0097] From this we can get the virtual internal potential constraint condition:

[0098]

[0099] Among them, U cd 、U cq are the dq axis components of the virtual internal potential respectively; U gd 、U gq are the dq axis components of the grid connection point voltage respectively; L is the filter inductance, and the filter resistance is ignored here. Figure 2 As shown, the virtual inner potential phasor E generated by the outer loop m ∠θ should be kept within the inner potential constraint circle, and the output voltage reference value is U cdref 、U cqref .

[0100] (7) Virtual impedance limiting link. The virtual impedance switching method is used to increase the output impedance of the converter and limit the transient impact current component during the fault. The virtual impedance control model is expressed as follows:

[0101]

[0102] in, The final value of the virtual internal potential dq axis component is generated, U cdqref is the intermediate reference value of the virtual internal potential dq axis component; I gdq is the dq axis component of the converter output current, I dqLim deadzone K is the setting value of the converter virtual impedance switching dead zone; pILim K is the proportional coefficient of the virtual impedance limiting link; iILim is the integral coefficient of the virtual impedance limiting link.

[0103] Then the output signal is controlled by the internal potential according to the virtual phase angle θ An inverse Park transform is performed to obtain a voltage reference wave in the three-phase stationary coordinate system. This wave is then used to generate trigger pulses that meet control requirements through a PWM generator, completing overall output control. Because this overall control system lacks an inner current loop, the converter's high-frequency output impedance is dominated by the filter, reducing the risk of broadband oscillations introduced by the control characteristics.

[0104] Therefore, the present invention proposes a photovoltaic power generation grid-connected control method based on a hybrid grid construction strategy, which performs control modeling based on the third-order model of the synchronous generator, adopts virtual excitation control to generate the virtual internal potential amplitude, and adopts a hybrid synchronization method of phase-locked loop and power synchronization control to generate the virtual internal potential phase angle; at the same time, direct voltage control is realized by combining virtual impedance and voltage phasor limitation, which can avoid dependence on the phase-locked loop, meet the flexible adjustment requirements of frequency and voltage in a multi-short-circuit ratio access environment, and effectively improve the stability of the "dual-high" power system.

[0105] Exemplary devices

[0106] Figure 3 FIG is a schematic diagram of a photovoltaic power generation grid-connected control device based on a hybrid grid-connected strategy provided by an exemplary embodiment of the present invention. Figure 3 As shown, the apparatus 300 includes:

[0107] A first control module 310 is configured to perform virtual frequency modulation control based on the acquired real-time operating data of the power grid and the photovoltaic power generation system, and output additional reference power;

[0108] A second control module 320 is configured to perform power synchronization control based on the additional reference power and the real-time operation data to output a first internal potential virtual angular velocity, and to perform phase-locked loop control based on the real-time operation data to output a second internal potential virtual angular velocity;

[0109] A third control module 330 is configured to perform hybrid synchronous control based on the first internal potential virtual angular velocity and the second internal potential virtual angular velocity, and output an internal potential virtual phase angle;

[0110] A fourth control module 340 is configured to perform virtual excitation control based on real-time operation data and output a virtual internal potential amplitude;

[0111] The limiting module 350 is used to limit the voltage phasor based on the virtual phase angle and amplitude of the internal potential, output a voltage reference value, and limit the virtual impedance based on the voltage reference value, output the final generated value of the virtual internal potential dq axis component, and realize grid-connected control.

[0112] Optionally, the real-time operation data includes: the three-phase current I output by the inverter gabc With the three-phase terminal voltage U gabc , the measured frequency of the power grid ω g, the inverter actually outputs active power P.

[0113] Optionally, the additional reference power is calculated as follows:

[0114]

[0115] Where ΔP ref is the additional reference power; ω0 is the reference frequency; ω g is the measured frequency calculated by the phase-locked loop; ω deadzone To set the frequency dead zone; K p is the frequency modulation coefficient.

[0116] Optionally, the expression for power synchronization control is:

[0117]

[0118] Among them, T j is the virtual inertia time constant; Δω PC Output the first internal potential virtual angular velocity for the converter power synchronization control link; P m is the input mechanical power corresponding to the traditional synchronous machine; P is the actual output active power of the converter, which is determined by the active reference instruction P ref and additional reference power ΔP ref Composition; K D is the deviation magnification, T w is the time constant of the DC isolation link, T3 and T4 are the time constants of the phase shift link, D is the damping coefficient, and s is the Laplace operator.

[0119] Optionally, the expression for the phase-locked loop control is:

[0120]

[0121] Among them, Δω PLL Output the second internal potential virtual angular velocity for the converter phase-locked synchronous control link; T PLL K is the phase-locked synchronization delay time constant; pPLL is the proportional control coefficient of the phase-locked loop; K iPLL is the phase-locked loop integral control coefficient; U gq is the q-axis component of the grid-connected point voltage.

[0122] Optionally, the expression of virtual excitation control is:

[0123]

[0124] Where, E m is the virtual internal potential amplitude of the converter output; K is the regulator gain; K vis the proportional integral selection factor; T1 and T2 are the time constants of the voltage regulator; V * is the reference voltage of the excitation voltage regulator; V is the calculated actual voltage signal of the excitation voltage regulator; i gd The d-axis current component injected into the grid by the converter; T' d0 is the time constant of the simulated generator excitation link; s is the Laplace operator; X d and X' d They simulate the direct-axis synchronous reactance and transient reactance of the generator respectively.

[0125] Optionally, the virtual internal potential constraint condition for voltage phasor limiting is:

[0126]

[0127] Where U cd 、U cq are the dq axis components of the virtual internal potential respectively; U gd 、U gq are the dq axis components of the grid connection point voltage respectively; L is the filter inductance; I dLim , I qLim are the dq axis component amplitude limits of the converter output current respectively; ω is the grid frequency.

[0128] Optionally, the expression of the virtual impedance limit is:

[0129]

[0130] Where, The final generated value of the virtual internal potential dq axis component, U cdqref is the intermediate reference value of the virtual internal potential dq axis component; I gdq is the dq axis component of the converter output current, I dqLim deadzone K is the setting value of the converter virtual impedance switching dead zone; pILim K is the proportional coefficient of the virtual impedance limiting link; iILim is the integral coefficient of the virtual impedance limiting link; s is the Laplace operator.

[0131] Exemplary electronic devices

[0132] Figure 4 This is the structure of an electronic device provided by an exemplary embodiment of the present invention. Figure 4 As shown, the electronic device 40 includes one or more processors 41 and a memory 42 .

[0133] The processor 41 may be a central processing unit (CPU) or other forms of processing units having data processing capabilities and / or instruction execution capabilities, and may control other components in the electronic device to perform desired functions.

[0134] The memory 42 may include one or more computer program products, which may include various forms of computer-readable storage media, such as volatile memory and / or non-volatile memory. The volatile memory may, for example, include random access memory (RAM) and / or cache memory (cache), etc. The non-volatile memory may, for example, include read-only memory (ROM), a hard disk, a flash memory, etc. One or more computer program instructions may be stored on the computer-readable storage medium, and the processor 41 may execute the program instructions to implement the methods of the software programs of the various embodiments of the present invention described above and / or other desired functions. In one example, the electronic device may further include: an input device 43 and an output device 44, which are interconnected via a bus system and / or other forms of connection mechanisms (not shown).

[0135] In addition, the input device 43 may also include, for example, a keyboard, a mouse, and the like.

[0136] The output device 44 can output various information to the outside. The output device 44 can include, for example, a display, a speaker, a printer, a communication network and a remote output device connected thereto.

[0137] Of course, to simplify, Figure 4 Only some of the components related to the present invention in the electronic device are shown, and components such as a bus, an input / output interface, etc. are omitted. In addition, the electronic device may further include any other appropriate components according to specific application conditions.

[0138] Exemplary computer program products and computer-readable storage media

[0139] In addition to the above-mentioned methods and devices, an embodiment of the present invention may also be a computer program product, which includes computer program instructions, which, when executed by a processor, enable the processor to perform the steps of the method according to various embodiments of the present invention described in the above "Exemplary Method" section of this specification.

[0140] The computer program product may be written in any combination of one or more programming languages to implement the operations of embodiments of the present invention, including object-oriented programming languages such as Java, C++, and conventional procedural programming languages such as C or similar programming languages. The program code may be executed entirely on the user's computing device, partially on the user's computing device, as a stand-alone software package, partially on the user's computing device and partially on a remote computing device, or entirely on a remote computing device or server.

[0141] In addition, an embodiment of the present invention may also be a computer-readable storage medium having computer program instructions stored thereon, which, when executed by a processor, enable the processor to execute the steps of the method according to various embodiments of the present invention described in the above "Exemplary Method" section of this specification.

[0142] The computer-readable storage medium can adopt any combination of one or more readable media. The readable medium can be a readable signal medium or a readable storage medium. The readable storage medium can, for example, include but is not limited to a system, system or device of electricity, magnetism, light, electromagnetic, infrared, or semiconductor, or any combination thereof. More specific examples (non-exhaustive list) of readable storage media include: an electrical connection with one or more wires, a portable disk, a hard disk, a random access memory (RAM), a read-only memory (ROM), an erasable programmable read-only memory (EPROM or flash memory), an optical fiber, a portable compact disk read-only memory (CD-ROM), an optical storage device, a magnetic storage device, or any suitable combination thereof.

[0143] The basic principles of the present invention have been described above in conjunction with specific embodiments. However, it should be noted that the advantages, strengths, and effects mentioned in the present invention are merely illustrative and non-limiting, and should not be construed as necessarily possessed by each embodiment of the present invention. Furthermore, the specific details disclosed above are provided for illustrative purposes and to facilitate understanding, and are not intended to be limiting. These details do not necessarily limit the present invention to being implemented using these specific details.

[0144] Each embodiment in this specification is described in a progressive manner, with each embodiment focusing on its differences from the other embodiments. References to the same or similar parts between the various embodiments are sufficient. For system embodiments, since they largely correspond to method embodiments, their description is relatively simple. For relevant parts, references to the description of the method embodiments are sufficient.

[0145] The block diagrams of the devices, systems, equipment, and systems involved in the present invention are merely illustrative examples and are not intended to require or imply that they must be connected, arranged, or configured in the manner shown in the block diagrams. As will be appreciated by those skilled in the art, these devices, systems, equipment, and systems can be connected, arranged, or configured in any manner. Words such as "including," "comprising," "having," and the like are open-ended words, meaning "including but not limited to," and can be used interchangeably therewith. The words "or" and "and" used herein refer to the words "and / or" and can be used interchangeably therewith, unless the context clearly indicates otherwise. The word "such as" used herein refers to the phrase "such as but not limited to," and can be used interchangeably therewith.

[0146] The method and system of the present invention may be implemented in many ways. For example, the method and system of the present invention may be implemented by software, hardware, firmware, or any combination of software, hardware, and firmware. The above sequence of steps for the method is for illustration only, and the steps of the method of the present invention are not limited to the sequence specifically described above, unless otherwise specified. In addition, in some embodiments, the present invention may also be implemented as a program recorded in a recording medium, which includes machine-readable instructions for implementing the method according to the present invention. Thus, the present invention also covers recording media that store programs for executing the method according to the present invention.

[0147] It should also be noted that, in the system, device and method of the present invention, each component or each step can be decomposed and / or recombined. These decompositions and / or recombinations should be regarded as equivalent schemes of the present invention. The above description of the disclosed aspects is provided to enable any technician in this field to make or use the present invention. Various modifications to these aspects will be very obvious to those skilled in the art, and the general principles defined here can be applied to other aspects without departing from the scope of the present invention. Therefore, the present invention is not intended to be limited to the aspects shown here, but according to the widest scope consistent with the principles disclosed here and novel features.

[0148] The above description has been presented for purposes of illustration and description. Furthermore, this description is not intended to limit the embodiments of the present invention to the forms disclosed herein. Although a number of example aspects and embodiments have been discussed above, those skilled in the art will recognize certain variations, modifications, alterations, additions, and sub-combinations thereof.

Claims

1. A photovoltaic power generation grid-connected control method based on a hybrid grid construction strategy, characterized in that: include: Based on the real-time operating data of the power grid and photovoltaic power generation system, virtual frequency regulation control is performed to output additional reference power; Performing power synchronization control based on the additional reference power and the real-time operation data to output a first internal potential virtual angular velocity, and performing phase-locked loop control based on the real-time operation data to output a second internal potential virtual angular velocity; Perform hybrid synchronous control based on the first internal potential virtual angular velocity and the second internal potential virtual angular velocity, and output an internal potential virtual phase angle; Performing virtual excitation control based on the real-time operating data and outputting a virtual internal potential amplitude; Voltage phasor limiting is performed based on the virtual phase angle of the internal potential and the virtual internal potential amplitude, and a voltage reference value is output. Virtual impedance limiting is performed based on the voltage reference value, and a final generated value of the virtual internal potential dq axis component is output to achieve grid connection control.

2. The method according to claim 1, characterized in that The real-time operation data includes: the three-phase current I output by the inverter gabc With the three-phase terminal voltage U gabc , the measured frequency of the power grid ω g , the inverter actually outputs active power P.

3. The method according to claim 1, characterized in that The calculation formula of the additional reference power is: Where ΔP ref is the additional reference power; ω0 is the reference frequency; ω g is the measured frequency calculated by the phase-locked loop; ω deadzone To set the frequency dead zone; K p is the frequency modulation coefficient.

4. The method according to claim 1, wherein The expression of the power synchronization control is: Among them, T j is the virtual inertia time constant; Δω PC Output the first internal potential virtual angular velocity for the converter power synchronization control link; P m is the input mechanical power corresponding to the traditional synchronous machine; P is the actual output active power of the converter, which is determined by the active reference instruction P ref and additional reference power ΔP ref Composition; K D is the deviation magnification, T w is the time constant of the DC isolation link, T3 and T4 are the time constants of the phase shift link, D is the damping coefficient, and s is the Laplace operator.

5. The method according to claim 1, wherein The expression of the phase-locked loop control is: Among them, Δω PLL Output the second internal potential virtual angular velocity for the converter phase-locked synchronous control link; T PLL K is the phase-locked synchronization delay time constant; pPLL is the proportional control coefficient of the phase-locked loop; K iPLL is the phase-locked loop integral control coefficient; U gq is the q-axis component of the grid-connected point voltage.

6. The method according to claim 1, characterized in that The expression of the virtual excitation control is: Where, E m is the virtual internal potential amplitude of the converter output; K is the regulator gain; K v is the proportional integral selection factor; T1 and T2 are the time constants of the voltage regulator; V * is the reference voltage of the excitation voltage regulator; V is the calculated actual voltage signal of the excitation voltage regulator; i gd The d-axis current component injected into the grid by the converter; T′ d0 is the time constant of the simulated generator excitation link; s is the Laplace operator; X d and X' d They simulate the direct-axis synchronous reactance and transient reactance of the generator respectively.

7. The method according to claim 1, characterized in that The virtual internal potential constraint condition of the voltage phasor limitation is: Where U cd 、U cq are the dq axis components of the virtual internal potential respectively; U gd 、U gq are the dq axis components of the grid connection point voltage respectively; L is the filter inductance; I dLim , I qLim are the dq axis component amplitude limits of the converter output current respectively; ω is the grid frequency.

8. The method according to claim 1, characterized in that The expression of the virtual impedance limit is: Where, The final value of the virtual internal potential dq axis component is generated, U cdqref is the intermediate reference value of the virtual internal potential dq axis component; I gdq is the dq axis component of the converter output current, I dqLimdeadzone K is the setting value of the converter virtual impedance switching dead zone; pILim K is the proportional coefficient of the virtual impedance limiting link; iILim is the integral coefficient of the virtual impedance limiting link; s is the Laplace operator.

9. A photovoltaic power generation grid-connected control device based on a hybrid grid construction strategy, characterized in that: include: A first control module is configured to perform virtual frequency modulation control based on the acquired real-time operating data of the power grid and the photovoltaic power generation system, and output additional reference power; a second control module, configured to perform power synchronization control based on the additional reference power and the real-time operation data to output a first internal potential virtual angular velocity, and perform phase-locked loop control based on the real-time operation data to output a second internal potential virtual angular velocity; a third control module, configured to perform hybrid synchronous control based on the first internal potential virtual angular velocity and the second internal potential virtual angular velocity, and output an internal potential virtual phase angle; a fourth control module, configured to perform virtual excitation control based on the real-time operation data and output a virtual internal potential amplitude; A limiting module is used to perform voltage phasor limiting based on the virtual phase angle of the internal potential and the virtual internal potential amplitude, output a voltage reference value, and perform virtual impedance limiting based on the voltage reference value, output a final generated value of the virtual internal potential dq axis component, and realize grid-connected control.

10. A computer-readable storage medium, characterized in that The storage medium stores a computer program, and the computer program is used to execute the method according to any one of claims 1 to 8.

11. An electronic device, characterized in that: The electronic device comprises: processor; a memory for storing instructions executable by the processor; The processor is configured to read the executable instructions from the memory and execute the instructions to implement the method according to any one of claims 1 to 8.

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