A wind power photovoltaic grid-connected converter hybrid control method and system

Abstract

The present application relates to the technical field of new energy power generation control, and more particularly to a wind power and photovoltaic grid-connected converter hybrid control method and system, comprising: constructing a grid-following outer ring control strategy with a direct current voltage-reactive power outer ring, and introducing a GFL control participation coefficient; constructing a grid-following inner ring control strategy, and introducing a GFL control participation coefficient to obtain a GFL control voltage reference value; constructing a grid-forming control strategy with a direct current voltage-frequency droop added with a stability control strategy, and introducing a GFM control participation coefficient to obtain a GFM control reference value; and synthesizing the GFL control voltage reference value and the GFM control reference value to obtain a converter output three-phase voltage reference value. The present application mixes the GFL and GFM control modes, and realizes a converter hybrid control strategy with adjustable participation ratio by introducing a participation coefficient, thereby better coordinating the response speed and stability of the converter and ensuring stable operation of the converter.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of new energy power generation control, and particularly relates to a novel wind power photovoltaic grid-connected converter hybrid control method and system. BACKGROUND

[0002] With the continuous development of technology, the penetration rate of new energy, focusing on wind power photovoltaic, gradually increases, and power electronic devices are also massively connected to the power grid. However, the large number of power electronic devices connected to the grid makes the grid strength decrease, and the grid at the grid-connected point is prone to fluctuation, thereby affecting the stability of the converter.

[0003] At present, the new energy grid-connected converter mostly adopts a grid-following (GFL) control strategy. The GFL control strategy generally uses a phase-locked loop (PLL) to track the grid frequency and phase and perform maximum power point tracking (MPPT) on the new energy. The GFL converter has the characteristics of fast response speed, high power generation efficiency, adaptability to new energy output, randomness and volatility, and can quickly respond to power changes. However, in a weak grid condition, the grid voltage at the grid-connected point will be disturbed, thereby affecting the stability of the GFL converter. The grid-forming (GFM) control strategy does not have a phase-locked loop structure and has no negative impedance interval in the port frequency characteristic, and directly controls the voltage amplitude and frequency of the converter. Compared with the GFL control strategy, the GFM control strategy has stronger stability in a weak grid, but it has no inner current control structure, resulting in slow response speed.

[0004] In order to overcome the stability problem caused by the change of grid strength, current researches mostly improve the grid-following control strategy or use the grid-forming control strategy, but at the same time, the system response speed is reduced, and the new energy power generation efficiency is affected. At present, there is a lack of research on a control strategy that takes into account the response speed and stability. SUMMARY

[0005] The present application aims to provide a novel wind power photovoltaic grid-connected converter hybrid control method and system to provide a hybrid control strategy containing GFL and GFM control modes, and to better coordinate the response speed and stability of the converter by introducing a participation coefficient.

[0006] To solve the above technical problems, the present application provides a novel wind power photovoltaic grid-connected converter hybrid control method and system.

[0007] In a first aspect, the present application provides a novel wind power photovoltaic grid-connected converter hybrid control method, which comprises the following steps:

[0008] acquiring real-time converter grid-connection data; the converter grid-connection data comprises grid-connection point three-phase voltage and grid-connection point three-phase current;

[0009] constructing a grid-following outer loop control strategy of DC voltage-reactive power, and introducing a GFL control participation coefficient to obtain grid-side converter output current dq-axis component reference values according to the converter grid-connection data;

[0010] constructing a grid-following inner loop control strategy, and introducing a GFL control participation coefficient to obtain GFL control voltage reference values based on the grid-side converter output current dq-axis component reference values;

[0011] constructing a grid-forming control strategy of DC voltage-frequency droop with a stability control strategy, and introducing a GFM control participation coefficient to obtain GFM control reference values; the GFM control reference values comprise GFM control voltage amplitude and GFM control phase;

[0012] introducing the GFL control participation coefficient and the GFM control participation coefficient to synthesize the GFL control voltage reference values and the GFM control reference values to obtain converter output three-phase voltage reference values.

[0013] In further embodiments, the grid-following outer loop control strategy is specifically:

[0014]

[0015] wherein, are grid-side converter output current dq-axis component reference values; k pgd , k igd , k pgq , k igq are PI control parameters; is a DC voltage reference value; u dc is a DC voltage actual value; is a converter output reactive power reference value; Q g is a converter output reactive power; k GFL is a GFL control participation coefficient, and the value range is 0.5≤k GFL ≤1.

[0016] In further embodiments, the step of constructing a grid-following outer loop control strategy of DC voltage-reactive power and introducing a GFL control participation coefficient to obtain grid-side converter output current dq-axis component reference values according to the converter grid-connection data comprises:

[0017] the grid-connection point three-phase voltage and the grid-connection point three-phase current are obtained after phase-locked loops, and a grid phase is obtained;

[0018] Based on the grid phase, Park transform is performed on the three-phase voltage and the three-phase current at the grid connection point to obtain the dq-axis components of the grid connection point voltage and the dq-axis components of the grid connection point current.

[0019] The reactive power output of the converter is obtained based on the three-phase voltage and the three-phase current at the grid connection point.

[0020] Based on the reactive power output of the converter, a grid-following outer loop control strategy with DC voltage-reactive power as the outer loop is constructed, and the GFL control participation coefficient is introduced to obtain the reference value of the dq axis component of the grid-side converter output current.

[0021] In a further implementation, the step of constructing a grid-connected inner-loop control strategy, introducing a GFL control participation coefficient, and obtaining a GFL control voltage reference value based on the reference value of the dq-axis component of the grid-side converter output current includes:

[0022] Multiply the GFL control participation factor by the dq-axis component of the grid connection point current to obtain the dq-axis participation component of the grid connection point current.

[0023] The reference value of the dq-axis component of the grid-side converter output current, the dq-axis component of the grid connection point voltage, and the dq-axis component of the grid connection point current are incorporated into the component input inner loop, and the reference value of the GFL control voltage is obtained through the inner loop.

[0024] In a further implementation, the step of constructing a grid-type control strategy with DC voltage-frequency droop incorporating a stable control strategy, and introducing a GFM control participation coefficient to obtain a GFM control reference value includes:

[0025] A DC voltage-frequency droop control strategy is adopted for the GFM phase control section, and a GFM control participation coefficient is introduced to obtain the GFM control phase.

[0026] A stable control strategy is adopted for the GFM amplitude control section, and a GFM control participation coefficient is introduced to obtain the GFM control voltage amplitude.

[0027] The expression for the DC voltage-frequency droop control strategy is as follows:

[0028]

[0029] In the formula, k is the per-unit value of the GFM control frequency. dc k is the droop coefficient. GFM For GFM control participation factor; u dc This is the actual value of the DC voltage; This is a reference value for DC voltage. ω is the base value of the net-side angular velocity; GFMAngular velocity is obtained for GFM control; θ GFM For GFM-controlled phase; This is the per-unit value of the power grid frequency;

[0030] The expression for the stability control strategy is:

[0031]

[0032] In the formula, u GFM The voltage amplitude is the GFM control voltage; T is the high-pass filter time constant; k up k ui For PI control parameters; k pss For stability control coefficients; This is the expression of the high-pass filter in the s-domain after the Laplace transform; This refers to the rated amplitude of the power grid voltage.

[0033] In a further implementation, the step of introducing the GFL control participation factor and the GFM control participation factor, and synthesizing the GFL control voltage reference value and the GFM control reference value to obtain the converter output three-phase voltage reference value includes:

[0034] The GFL control voltage reference value is subjected to an inverse Parker transformation to obtain the GFL three-phase composite voltage;

[0035] The amplitude and phase of the GFM control voltage are transformed to the abc three-phase coordinate system to obtain the GFM three-phase composite voltage.

[0036] By introducing the GFL control participation coefficient and the GFM control participation coefficient, the reference value of the converter output three-phase voltage is obtained based on the GFL three-phase combined voltage and the GFM three-phase combined voltage.

[0037] In a further embodiment, the formula for calculating the reference value of the three-phase output voltage of the converter is as follows:

[0038] u cabc =k GFL u GFL-abc +k GFM u GFM-abc

[0039] In the formula, u cabc The reference value for the three-phase output voltage of the converter; k GFL For GFL control participation factor; u GFL-abc This refers to the three-phase combined voltage of the GFL, i.e., the reference value of the GFL control voltage in the three-phase stationary coordinate system; u GFM-abc This is the three-phase combined voltage of GFM.

[0040] Secondly, the present invention provides a novel hybrid control system for wind power and photovoltaic grid-connected converters, the system comprising:

[0041] The grid connection data acquisition module is used to acquire converter grid connection data in real time; the converter grid connection data includes the three-phase voltage and the three-phase current at the grid connection point.

[0042] The grid-following outer loop control module is used to construct a grid-following outer loop control strategy with DC voltage-reactive power as the outer loop, and introduces the GFL control participation coefficient to obtain the reference value of the dq axis component of the grid-side converter output current based on the converter grid connection data.

[0043] The grid-following inner loop control module is used to construct the grid-following inner loop control strategy and introduce the GFL control participation coefficient. The GFL control voltage reference value is obtained based on the reference value of the dq axis component of the grid-side converter output current.

[0044] A network-type control module is used to construct a network-type control strategy with added stable control strategy for DC voltage-frequency droop, and to introduce GFM control participation coefficient to obtain GFM control reference value; the GFM control reference value includes GFM control voltage amplitude and GFM control phase;

[0045] The three-phase voltage acquisition module is used to introduce the GFL control participation factor and the GFM control participation factor, and synthesize the GFL control voltage reference value and the GFM control reference value to obtain the converter output three-phase voltage reference value.

[0046] Thirdly, the present invention also provides a computer device, including a processor and a memory, the processor being connected to the memory, the memory being used to store a computer program, and the processor being used to execute the computer program stored in the memory, so that the computer device performs the steps of implementing the above-described method.

[0047] Fourthly, the present invention also provides a computer-readable storage medium storing a computer program that, when executed by a processor, implements the steps of the above-described method.

[0048] This invention provides a novel hybrid control method and system for wind power and photovoltaic grid-connected converters. The method balances the speed and stability of the control strategy. Under strong grid conditions, it increases the grid-connection participation coefficient to enhance the response speed of the control system, while retaining a certain degree of grid-connection participation to enhance system stability. Under weak grid conditions, it further increases the grid-connection participation coefficient to improve the stability of the control system, while also retaining a certain degree of grid-connection participation to improve the system response speed. This method effectively coordinates the converter's response speed and stability. Compared with existing technologies, this method balances response speed and stability, and enables a converter control strategy with adjustable participation ratios to flexibly adapt to changes in grid strength and fluctuations in renewable energy output. Attached Figure Description

[0049] Figure 1 This is a schematic flowchart of a novel hybrid control method for wind power and photovoltaic grid-connected converters provided in an embodiment of the present invention;

[0050] Figure 2 This is a schematic diagram illustrating the overall application of the hybrid control strategy for network-based / network-structured systems provided in this embodiment of the invention.

[0051] Figure 3 This is a schematic diagram of the specific structure of the hybrid control strategy for mesh-type / network-type control provided in the embodiments of the present invention;

[0052] Figure 4 This is a schematic diagram of the inner loop structure of the mesh-type control structure provided in an embodiment of the present invention;

[0053] Figure 5 These are the operation diagrams of the GFL and GFM control strategies provided in this embodiment of the invention in the converter.

[0054] Figure 6 The participation coefficient k for network-type control provided in this embodiment of the invention is... GFL Simulation waveform diagram when = 1;

[0055] Figure 7 The participation coefficient k for network-type control provided in this embodiment of the invention is... GFL Simulation waveform when ω = 0.75;

[0056] Figure 8 The participation coefficient k for network-type control provided in this embodiment of the invention is... GFL Simulation waveform when = 0.5;

[0057] Figure 9 The participation coefficient k for network-type control provided in this embodiment of the invention is... GFL Three-phase voltage waveforms at the grid connection point when the voltage values ​​are 1, 0.75, and 0.5.

[0058] Figure 10The participation coefficient k for network-type control provided in this embodiment of the invention is... GFL Three-phase current waveforms at the grid connection point when the current ratios are 1, 0.75, and 0.5.

[0059] Figure 11 The participation coefficient k for network-type control provided in this embodiment of the invention is... GFL Simulation waveform of the d-axis current of the mesh type under varying conditions;

[0060] Figure 12 The participation coefficient k for network-type control provided in this embodiment of the invention is... GFL Simulation waveform of the q-axis current of the mesh under varying conditions;

[0061] Figure 13 This is a block diagram of a novel hybrid control system for wind power and photovoltaic grid-connected converters provided in an embodiment of the present invention;

[0062] Figure 14 This is a schematic diagram of the structure of a computer device provided in an embodiment of the present invention. Detailed Implementation

[0063] The embodiments of the present invention are described in detail below with reference to the accompanying drawings. The embodiments are given for illustrative purposes only and should not be construed as limiting the present invention. The accompanying drawings are for reference and illustration only and do not constitute a limitation on the scope of patent protection of the present invention, because many changes can be made to the present invention without departing from the spirit and scope of the present invention.

[0064] refer to Figure 1 This invention provides a novel hybrid control method for wind power and photovoltaic grid-connected converters, such as... Figure 1 As shown, the method includes the following steps:

[0065] S1. Real-time acquisition of converter grid connection data; the converter grid connection data includes the three-phase voltage u at the grid connection point. a u b u c and the three-phase current i at the grid connection point a i b i c .

[0066] S2. Construct a grid-following outer loop control strategy with DC voltage-reactive power as the outer loop, and introduce the GFL control participation coefficient to obtain the reference value of the dq axis component of the grid-side converter output current based on the converter grid connection data.

[0067] In one embodiment, the step of constructing an outer loop based on a DC voltage-reactive power grid-following outer loop control strategy, and introducing a GFL control participation factor, and obtaining reference values ​​for the dq-axis components of the grid-side converter output current based on converter grid connection data includes:

[0068] S201. The three-phase voltage u at the grid connection point a u b u c and the three-phase current i at the grid connection point a i b i c After passing through a phase-locked loop (PLL), the grid phase θ is obtained. g ;

[0069] S202. Based on the grid phase, perform Park transformation on the three-phase voltage and the three-phase current at the grid connection point to obtain the dq-axis components of the grid connection point voltage and the dq-axis components of the grid connection point current;

[0070] The formula for calculating the dq-axis component of the grid connection point voltage is as follows:

[0071]

[0072] In the formula, u a u b u c The three-phase voltage at the grid connection point; u d u q These are the d-axis and q-axis components of the grid connection point voltage, respectively; θ g For grid phase;

[0073] The formula for calculating the dq-axis component of the grid connection point current is:

[0074]

[0075] In the formula, i a i b i c For the three-phase current at the grid connection point; i d i q The d-axis and q-axis components of the grid-connected current;

[0076] S203. Obtain the reactive power output of the converter based on the three-phase voltage and the three-phase current at the grid connection point;

[0077] It should be noted that there are many methods for measuring the reactive power output of the converter in this embodiment, and those skilled in the art can select the appropriate method to measure the reactive power θ according to the specific implementation. g The method described herein is not limited to this embodiment; this embodiment merely illustrates one measurement method.

[0078] S204. Based on the reactive power output of the converter, a grid-following outer loop control strategy with DC voltage-reactive power as the outer loop is constructed, and the GFL control participation coefficient is introduced to obtain the reference value of the dq axis component of the grid-side converter output current.

[0079] In one embodiment, the expression for the network-type outer loop control strategy is specifically as follows:

[0080]

[0081] In the formula, These are the reference values ​​for the dq-axis components of the grid-side converter output current; k pgd k igd k pgq k igq These are PI control parameters; This is the reference value for DC voltage; u dc This is the actual value of the DC voltage; Q is the reference value for the reactive power output of the converter; g To output reactive power to the converter; k GFL This is the GFL control participation factor, with a value ranging from 0.5 to k. GFL ≤1, GFL control participation factor k GFL The larger the value, the greater the control power and the higher the level of participation of the strategy.

[0082] In this embodiment, the GFL control participation factor k GFL The value is related to the grid short-circuit ratio. The specific expression for the grid short-circuit ratio (SCR) is as follows:

[0083]

[0084] In the formula, U N The rated voltage of the power grid; S g Z is the rated power of the power grid. g To determine the equivalent impedance of the grid from the grid connection point, a larger short-circuit ratio indicates a stronger grid, and vice versa.

[0085] If the grid short-circuit ratio (SCR) is below 3, it can be considered a weak grid. The weaker the grid, the worse the converter's stability. To balance the converter's speed and stability, enabling it to exhibit stronger stability under weak grid conditions, when the SCR is small, k... GFL The value is also relatively small, aiming to reduce the involvement of the GFL control strategy and increase the involvement of the more stable GFM control strategy under weak network conditions; when SCR is large, k GFL The value is also relatively large, with the aim of increasing the participation of the GFL control strategy, improving the converter response speed, enabling it to respond quickly to changes in new energy output, and improving economic efficiency.

[0086] It should be noted that the following explains the principle of the mesh-type outer loop control strategy. The expression of the mesh-type outer loop control strategy can be transformed to obtain:

[0087]

[0088] As can be seen from the modified outer-loop control strategy expression, the improved GFL controller can achieve the desired total output power Q of the converter. g k in GFL Q g To partially achieve zero-error control, the reactive power controlled by the GFL controller in steady state should be... Partial reactive power control was achieved; that is, only for DC voltage u dc The partial pressure is k GFL u dc The capacitor voltage is controlled to make it reach a value of In this way, the goal of the grid-type outer loop control strategy is achieved: to control only a portion of the voltage.

[0089] S3. Construct a grid-type inner-loop control strategy and introduce the GFL control participation coefficient. Obtain the GFL control voltage reference value based on the dq-axis component reference value of the grid-side converter output current.

[0090] In one embodiment, the step of constructing a grid-connected inner-loop control strategy, introducing a GFL control participation coefficient, and obtaining a GFL control voltage reference value based on the reference value of the dq-axis component of the grid-side converter output current includes:

[0091] Multiplying the GFL control participation factor by the dq-axis component of the grid connection point current yields the dq-axis participation component k of the grid connection point current. GFL i d k GFL i q ;

[0092] The reference value of the grid-side converter output current dq-axis component, the grid connection point voltage dq-axis component, and the grid connection point current dq-axis component are incorporated into the component input inner loop to obtain the GFL control voltage reference value.

[0093] S4. Construct a grid-type control strategy with DC voltage-frequency droop incorporating a stable control strategy, and introduce a GFM control participation coefficient to obtain a GFM control reference value; the GFM control reference value includes the GFM control voltage amplitude and the GFM control phase.

[0094] In one embodiment, the step of constructing a grid-type control strategy with DC voltage-frequency droop incorporating a stable control strategy, and introducing a GFM control participation coefficient to obtain a GFM control reference value includes:

[0095] A DC voltage-frequency droop control strategy is adopted for the GFM phase control section, and a GFM control participation coefficient is introduced to obtain the GFM control phase.

[0096] A stable control strategy is adopted for the GFM amplitude control section, and a GFM control participation coefficient is introduced to obtain the GFM control voltage amplitude.

[0097] The expression for the DC voltage-frequency droop control strategy is as follows:

[0098]

[0099] In the formula, k is the per-unit value of the GFM control frequency. dc k is the droop coefficient. GFM For GFM control participation factor; u dc This is the actual value of the DC voltage; This is a reference value for DC voltage. ω is the base value of the net-side angular velocity; GFM Angular velocity is obtained for GFM control; θ GFM For GFM-controlled phase; This is the per-unit value of the power grid frequency.

[0100] In this embodiment, the GFM control participation factor k GFM With GFL control participation factor k GFL The relationship is:

[0101] k GFM +k GFL =1

[0102] It should be noted that the following explains the principle of the grid-type DC voltage-frequency droop control strategy. The expression for the DC voltage-frequency droop control strategy can be transformed to obtain:

[0103]

[0104] As can be seen from the modified DC voltage-frequency droop control strategy, it only applies to DC voltages of u. dc The partial pressure is k GFM u dc The capacitor voltage is controlled to make it reach a value of In this way, the goal of the grid-type control strategy is achieved: to control only a portion of the voltage.

[0105] In one embodiment, the expression for the stability control strategy is:

[0106]

[0107] In the formula, u GFMThe voltage amplitude is the GFM control voltage; T is the high-pass filter time constant; k up k ui For PI control parameters; k pss For stability control coefficients; This is the expression of the high-pass filter in the s-domain after the Laplace transform; This refers to the rated amplitude of the power grid voltage.

[0108] In this embodiment, for the GFM amplitude control section, reactive power control with zero error is adopted by introducing the GFM control participation coefficient. At the same time, a stable control strategy is introduced so that the DC side voltage passes through a high-pass filter and the gain of the stable control coefficient, and is then added to the GFM control voltage modulation amplitude to obtain the GFM control voltage amplitude.

[0109] S5. Introduce the GFL control participation factor and the GFM control participation factor, and synthesize the GFL control voltage reference value and the GFM control reference value to obtain the converter output three-phase voltage reference value.

[0110] In one embodiment, the step of introducing the GFL control participation factor and the GFM control participation factor, and synthesizing the GFL control voltage reference value and the GFM control reference value to obtain the converter output three-phase voltage reference value includes:

[0111] S501. Perform an inverse Parker transformation on the GFL control voltage reference value to obtain the GFL three-phase composite voltage; wherein, the calculation formula for the GFL three-phase composite voltage is:

[0112]

[0113] In the formula, u GFL-abc This is the three-phase composite voltage of the GFL, which is the reference value of the GFL control voltage in the three-phase stationary coordinate system.

[0114] S502. Transform the amplitude of the GFM control voltage and the phase of the GFM control voltage to the abc three-phase coordinate system to obtain the GFM three-phase composite voltage; wherein, the calculation formula of the GFM three-phase composite voltage is:

[0115]

[0116] In the formula, u GFM-abc The three-phase combined voltage of GFM is given by u. GFM θ GFM The synthesized three-phase voltage.

[0117] S503. Introduce the GFL control participation coefficient and the GFM control participation coefficient, and obtain the converter output three-phase voltage reference value based on the GFL three-phase combined voltage and the GFM three-phase combined voltage.

[0118] The formula for calculating the reference value of the three-phase output voltage of the converter is as follows:

[0119] u cabc =k GFL u GFL-abc +k GFM u GFM-abc

[0120] In the formula, u cabc The reference value for the three-phase output voltage of the converter; k GFL For GFL control participation factor; u GFL-abc This refers to the three-phase combined voltage of the GFL, i.e., the reference value of the GFL control voltage in the three-phase stationary coordinate system; k GFM For GFM control participation factor; u GFM-abc This is the three-phase combined voltage of GFM.

[0121] like Figure 2 , 3 As shown in Figure 4, since GFL-type control has a faster response and can quickly adjust the system state, while GFM-type control has stronger stability and is less prone to instability under weak grid conditions, this embodiment introduces a participation coefficient and applies a hybrid control strategy containing both GFL and GFM control methods to the converter. This adjusts the converter's response speed and stability. Under strong grid conditions, the participation of GFL is increased, and the overall control is mainly based on the GFL control strategy, prioritizing response speed to ensure maximum utilization of new energy sources and guarantee rapid adjustment of the converter. Under weak grid conditions, the participation of GFM is increased to improve overall stability and ensure stable operation of the converter.

[0122] It should be noted that the following explanation of the principle of synthesizing the three-phase voltage reference value is as follows; the final output voltage of the converter is:

[0123]

[0124] In the formula, u cout The final output voltage of the converter is the three-phase voltage; This is the per-unit value of DC voltage.

[0125] like Figure 5 As shown, assuming that the two control strategies, namely grid-connected and network-connected, each operate in one converter, the final superimposed converter voltage value is:

[0126]

[0127] The above formula can be transformed into:

[0128]

[0129] Further order:

[0130] u cabc =k GFL u GFL-abc +k GFM u GFM-abc

[0131] This yields the superposition formula for the hybrid control strategy.

[0132] Figures 6-12 The different network-type control participation coefficients k are shown respectively. GFL The corresponding waveform simulation diagram.

[0133] This embodiment provides a novel hybrid control method for wind power and photovoltaic grid-connected converters. Based on the traditional method of outer-loop control of DC voltage and reactive power, and inner-loop control of dq-axis current with decoupling, this method introduces a control participation coefficient k. GFL The method incorporates a participation coefficient into both the inner loop setpoint and actual value, ensuring that the grid-following control strategy only controls a portion of the power. Furthermore, regarding the grid-building control strategy, in addition to employing a DC voltage-frequency droop control strategy and a stability control strategy, the method introduces a grid-building control participation coefficient k. GFM This allows the grid-type control to only participate in controlling a portion of the power, realizing a technical solution that adjusts the converter's response speed and stability by introducing a participation coefficient, thereby improving overall stability and ensuring stable operation of the converter.

[0134] It should be noted that the sequence number of each process does not imply the order of execution. The execution order of each process should be determined by its function and internal logic, and should not constitute any limitation on the implementation process of the embodiments of this application.

[0135] In one embodiment, such as Figure 13 As shown in the figure, this invention provides a novel hybrid control system for wind power and photovoltaic grid-connected converters, the system comprising:

[0136] Grid connection data acquisition module 61 is used to acquire converter grid connection data in real time; the converter grid connection data includes three-phase voltage and three-phase current at the grid connection point;

[0137] The grid-connected outer loop control module 62 is used to construct a grid-connected outer loop control strategy with DC voltage-reactive power as the outer loop, and introduces the GFL control participation coefficient to obtain the reference value of the dq axis component of the grid-side converter output current based on the converter grid connection data.

[0138] The grid-following inner loop control module 63 is used to construct the grid-following inner loop control strategy and introduce the GFL control participation coefficient. The GFL control voltage reference value is obtained based on the reference value of the dq axis component of the grid-side converter output current.

[0139] The network control module 64 is used to construct a network control strategy with DC voltage-frequency droop incorporating a stable control strategy, and to introduce a GFM control participation coefficient to obtain a GFM control reference value; the GFM control reference value includes the GFM control voltage amplitude and the GFM control phase.

[0140] The three-phase voltage acquisition module 65 is used to introduce the GFL control participation coefficient and the GFM control participation coefficient, and synthesize the GFL control voltage reference value and the GFM control reference value to obtain the converter output three-phase voltage reference value.

[0141] Specific limitations regarding the novel hybrid control system for wind power and photovoltaic grid-connected converters can be found in the above-described limitations of the novel hybrid control method for wind power and photovoltaic grid-connected converters, and will not be repeated here. Those skilled in the art will recognize that the various modules and steps described in conjunction with the embodiments disclosed in this application can be implemented in hardware, software, or a combination of both. Whether these functions are implemented in hardware or software depends on the specific application and design constraints of the technical solution. Those skilled in the art can use different methods to implement the described functions for each specific application, but such implementation should not be considered beyond the scope of this application.

[0142] This invention provides a novel hybrid control system for wind and solar grid-connected converters. The system implements a hybrid control strategy incorporating both GFL and GFM control modes through a grid-following outer loop control module, a grid-following inner loop control module, and a grid-building control module. Furthermore, it adjusts the converter's response speed and stability by introducing a participation coefficient. Compared to existing technologies, this invention balances the speed and stability of the control strategy. Under strong grid conditions, it increases the grid-following participation coefficient to enhance the control system's response speed while retaining a certain degree of grid-building participation to improve system stability. Under weak grid conditions, it further increases the grid-building participation coefficient to improve control system stability while still retaining a certain degree of grid-following participation to enhance system response speed.

[0143] Figure 14 This invention provides a computer device including a memory, a processor, and a transceiver, which are connected to each other via a bus. The memory is used to store a set of computer program instructions and data, and can transmit the stored data to the processor. The processor can execute the program instructions stored in the memory to perform the steps of the above method.

[0144] The memory may include volatile memory or non-volatile memory, or both; the processor may be a central processing unit, a microprocessor, an application-specific integrated circuit, a programmable logic device, or a combination thereof. By way of example, but not limitation, the programmable logic device described above may be a complex programmable logic device, a field-programmable gate array, a general-purpose array logic, or any combination thereof.

[0145] In addition, memory can be a physically independent unit or integrated with the processor.

[0146] Those skilled in the art will understand that Figure 14 The structure shown is merely a block diagram of a portion of the structure related to the present application and does not constitute a limitation on the computer device to which the present application is applied. Specific computer devices may include more or fewer components than those shown in the figure, or combine certain components, or have the same component arrangement.

[0147] In one embodiment, the present invention provides a computer-readable storage medium having a computer program stored thereon, which, when executed by a processor, implements the steps of the above-described method.

[0148] In the above embodiments, implementation can be achieved, in whole or in part, through software, hardware, firmware, or any combination thereof. When implemented in software, it can be implemented, in whole or in part, as a computer program product. The computer program product includes one or more computer instructions. When the computer program instructions are loaded and executed on a computer, all or part of the processes or functions described in the embodiments of the present invention are generated. The computer can be a general-purpose computer, a special-purpose computer, a computer network, or other programmable device. The computer instructions can be stored in a computer-readable storage medium or transmitted from one computer-readable storage medium to another. For example, the computer instructions can be transmitted from one website, computer, server, or data center to another website, computer, server, or data center via wired (e.g., coaxial cable, fiber optic, digital subscriber line) or wireless (e.g., infrared, wireless, microwave, etc.) means. The computer-readable storage medium can be any available medium accessible to a computer or a data storage device such as a server or data center that integrates one or more available media. The available medium can be a magnetic medium (e.g., floppy disk, hard disk, magnetic tape), an optical medium (e.g., DVD), or a semiconductor medium (e.g., SSD), etc.

[0149] Those skilled in the art will understand that all or part of the processes in the methods of the above embodiments can be implemented by a computer program instructing related hardware. The computer program can be stored in a computer-readable storage medium, and when the computer program is executed, it can include the processes of the embodiments of the above methods.

[0150] The embodiments described above are merely preferred embodiments of this application, and while the descriptions are specific and detailed, they should not be construed as limiting the scope of the invention patent. It should be noted that those skilled in the art can make various improvements and substitutions without departing from the technical principles of this invention, and these improvements and substitutions should also be considered within the scope of protection of this application. Therefore, the scope of protection of this patent application should be determined by the scope of the claims.

Claims

1. A hybrid control method for wind power and photovoltaic grid-connected converters, characterized in that, Includes the following steps: Real-time acquisition of converter grid connection data; the converter grid connection data includes three-phase voltage and three-phase current at the grid connection point; A grid-following outer loop control strategy with DC voltage-reactive power as the outer loop is constructed, and the GFL control participation factor is introduced. The reference value of the dq axis component of the grid-side converter output current is obtained based on the converter grid connection data. A grid-connected inner-loop control strategy is constructed, and a GFL control participation coefficient is introduced. The GFL control voltage reference value is obtained based on the reference value of the dq-axis component of the grid-side converter output current. A grid-type control strategy with DC voltage-frequency droop incorporated into a stable control strategy is constructed, and a GFM control participation coefficient is introduced to obtain a GFM control reference value; the GFM control reference value includes the GFM control voltage amplitude and the GFM control phase. By introducing the GFL control participation factor and the GFM control participation factor, the reference values ​​of the GFL control voltage and the GFM control voltage are synthesized to obtain the reference values ​​of the three-phase output voltage of the converter. The steps of constructing a grid-type control strategy with DC voltage-frequency droop incorporating a stable control strategy, and introducing a GFM control participation coefficient to obtain a GFM control reference value include: A DC voltage-frequency droop control strategy is adopted for the GFM phase control section, and a GFM control participation coefficient is introduced to obtain the GFM control phase. A stable control strategy is adopted for the GFM amplitude control section, and a GFM control participation coefficient is introduced to obtain the GFM control voltage amplitude. The expression for the DC voltage-frequency droop control strategy is as follows: In the formula, This is the per-unit value of the GFM control frequency; This is the droop coefficient; This is the participation factor for GFM control; This is the actual value of the DC voltage; This is a reference value for DC voltage. This is the baseline value of the net-side angular velocity; Angular velocity is obtained through GFM control; For GFM-controlled phase; This is the per-unit value of the power grid frequency; The expression for the stability control strategy is: In the formula, The voltage amplitude is controlled by GFM. The time constant of the high-pass filter; , These are PI control parameters; For stability control coefficients; This is the expression of the high-pass filter in the s-domain after the Laplace transform; This refers to the rated value of the grid voltage amplitude.

2. The hybrid control method for wind power and photovoltaic grid-connected converters as described in claim 1, characterized in that, The specific network-based outer loop control strategy is as follows: In the formula, , These are the reference values ​​for the dq-axis components of the grid-side converter output current, respectively. , , , These are PI control parameters; This is a reference value for DC voltage. This is the actual value of the DC voltage; This is a reference value for the reactive power output of the converter. The converter outputs reactive power; This is the GFL control participation factor, with a value range of [value range missing]. .

3. The hybrid control method for wind power and photovoltaic grid-connected converters as described in claim 1, characterized in that, The steps of constructing a grid-following outer loop control strategy with DC voltage-reactive power as the outer loop, and introducing the GFL control participation factor, to obtain the reference value of the dq-axis component of the grid-side converter output current based on the converter grid connection data include: The three-phase voltage and the three-phase current at the grid connection point are passed through a phase-locked loop to obtain the grid phase. Based on the grid phase, Park transform is performed on the three-phase voltage and the three-phase current at the grid connection point to obtain the dq-axis components of the grid connection point voltage and the dq-axis components of the grid connection point current. The reactive power output of the converter is obtained based on the three-phase voltage and the three-phase current at the grid connection point. Based on the reactive power output of the converter, a grid-following outer loop control strategy with DC voltage-reactive power as the outer loop is constructed, and the GFL control participation coefficient is introduced to obtain the reference value of the dq axis component of the grid-side converter output current.

4. The hybrid control method for wind power and photovoltaic grid-connected converters as described in claim 3, characterized in that, The steps of constructing a grid-connected inner-loop control strategy, introducing a GFL control participation coefficient, and obtaining a GFL control voltage reference value based on the dq-axis component reference value of the grid-side converter output current include: Multiply the GFL control participation factor by the dq-axis component of the grid connection point current to obtain the dq-axis participation component of the grid connection point current. The reference value of the dq-axis component of the grid-side converter output current, the dq-axis component of the grid connection point voltage, and the dq-axis component of the grid connection point current are incorporated into the component input inner loop, and the reference value of the GFL control voltage is obtained through the inner loop.

5. The hybrid control method for wind power and photovoltaic grid-connected converters as described in claim 1, characterized in that, The step of introducing the GFL control participation factor and the GFM control participation factor to synthesize the GFL control voltage reference value and the GFM control reference value to obtain the converter output three-phase voltage reference value includes: The GFL control voltage reference value is subjected to an inverse Parker transformation to obtain the GFL three-phase composite voltage; The amplitude and phase of the GFM control voltage are transformed to the abc three-phase coordinate system to obtain the GFM three-phase composite voltage. By introducing the GFL control participation coefficient and the GFM control participation coefficient, the reference value of the converter output three-phase voltage is obtained based on the GFL three-phase combined voltage and the GFM three-phase combined voltage.

6. The hybrid control method for wind power and photovoltaic grid-connected converters as described in claim 5, characterized in that, The formula for calculating the reference value of the three-phase output voltage of the converter is as follows: In the formula, This is the reference value for the three-phase output voltage of the converter; This is the GFL control participation factor; This refers to the three-phase composite voltage of the GFL, which is the reference value of the GFL control voltage in the three-phase stationary coordinate system. This is the three-phase combined voltage of GFM.

7. A hybrid control system for wind power and photovoltaic grid-connected converters, characterized in that, The system includes: The grid connection data acquisition module is used to acquire converter grid connection data in real time; the converter grid connection data includes the three-phase voltage and the three-phase current at the grid connection point. The grid-following outer loop control module is used to construct a grid-following outer loop control strategy with DC voltage-reactive power as the outer loop, and introduces the GFL control participation coefficient to obtain the reference value of the dq axis component of the grid-side converter output current based on the converter grid connection data. The grid-following inner loop control module is used to construct the grid-following inner loop control strategy and introduce the GFL control participation coefficient. The GFL control voltage reference value is obtained based on the reference value of the dq axis component of the grid-side converter output current. A network-type control module is used to construct a network-type control strategy with added stable control strategy for DC voltage-frequency droop, and to introduce GFM control participation coefficient to obtain GFM control reference value; the GFM control reference value includes GFM control voltage amplitude and GFM control phase; The three-phase voltage acquisition module is used to introduce the GFL control participation coefficient and the GFM control participation coefficient, and synthesize the GFL control voltage reference value and the GFM control reference value to obtain the converter output three-phase voltage reference value. The steps of constructing a grid-type control strategy with DC voltage-frequency droop incorporating a stable control strategy, and introducing a GFM control participation coefficient to obtain a GFM control reference value include: A DC voltage-frequency droop control strategy is adopted for the GFM phase control section, and a GFM control participation coefficient is introduced to obtain the GFM control phase. A stable control strategy is adopted for the GFM amplitude control section, and a GFM control participation coefficient is introduced to obtain the GFM control voltage amplitude. The expression for the DC voltage-frequency droop control strategy is as follows: In the formula, This is the per-unit value of the GFM control frequency; This is the droop coefficient; This is the participation factor for GFM control; This is the actual value of the DC voltage; This is a reference value for DC voltage. This is the baseline value of the net-side angular velocity; Angular velocity is obtained through GFM control; For GFM-controlled phase; This is the per-unit value of the power grid frequency; The expression for the stability control strategy is: In the formula, The voltage amplitude is controlled by GFM. The time constant of the high-pass filter; , These are PI control parameters; For stability control coefficients; This is the expression of the high-pass filter in the s-domain after the Laplace transform; This refers to the rated value of the grid voltage amplitude.

8. A computer device, characterized in that: The device includes a processor and a memory, the processor being connected to the memory for storing computer programs, and the processor for executing the computer programs stored in the memory to cause the computer device to perform the method as described in any one of claims 1 to 6.

9. A computer-readable storage medium, characterized in that: The computer-readable storage medium stores a computer program that, when executed, implements the method as described in any one of claims 1 to 6.

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