A Wide-Range Operation Control Method and System for a New Energy Power Generation System

Abstract

A wide-range operation control method and system for a new energy power generation system, belonging to the technical field of new energy grid connection. The method includes the following steps: Collect the voltage and current at the new energy grid connection point, obtain the grid impedance through grid impedance identification, and calculate the short-circuit ratio of the external grid impedance of the grid-connected converter based on the grid impedance; Based on the obtained short-circuit ratio, generate a converter control mode switching value T. If the control mode switching value T is set to 1, enter the weak grid control mode; If the control mode switching value T is set to 2, enter the strong grid control mode; In the strong grid control mode, the converter switches to execute power loop control; In the weak grid control mode, the converter switches to execute torque damping control; Both the strong grid control mode and the weak grid control mode continuously monitor the voltage and current at the new energy grid connection point, continuously generate the converter control mode switching value T; And switch the control mode according to the jump of the converter control mode switching value T.

Description

Technical Field

[0001] The present invention belongs to the technical field of new energy grid connection, and relates to a wide-area operation control method and system for a new energy power generation system. More specifically, it relates to a control mode adaptive switching technology and device for a new energy grid-connected converter under different grid strengths, especially extremely low grid strengths. Background Art

[0002] Traditional new energy power generation system equipment selects control strategies on the premise of limited changes in the external grid impedance to improve or compensate for the system stability margin, and adjusts parameters according to the installation scenario of the grid-connected converter to cope with the system stability problems caused by the grid impedance. However, there are no countermeasures for the situation brought about by large-scale changes in the equivalent grid impedance at the same location. With the widespread installation of new energy power generation equipment on both sides of the power grid for power generation and distribution, related products must face the factor of large-scale changes in the external equivalent grid impedance caused by frequent changes in the grid and substation operation modes, and corresponding countermeasures are relatively lacking.

[0003] The prior art document 1 (CN111030174B) discloses a control method for seamless switching between the VSG mode and the current source mode of a grid-connected inverter. Its disadvantage is that it only focuses on the seamless switching between the two converter control modes in a single machine system, and does not involve the switching conditions of the grid-connected converter control mode; the corresponding VSG control mode cannot ensure the stable operation of the grid-connected converter under the condition of extremely low source impedance (near 1.0). Summary of the Invention

[0004] To solve the deficiencies in the prior art, the present invention provides a control mode adaptive switching method and system for a new energy power generation system, which uses various methods to detect effective information such as the equivalent grid impedance or voltage harmonic components of the grid-connected converter, and makes a comprehensive judgment based on relevant information to dynamically adjust the control strategy of the grid-connected converter / group to ensure the stable operation requirements of the system under changing external operating conditions.

[0005] The present invention adopts the following technical solutions.

[0006] The first aspect of the present invention provides a wide-area operation control method for a new energy power generation system, including the following steps:

[0007] Collect the voltage and current at the new energy grid connection point, obtain the grid impedance through grid impedance identification, and calculate the short-circuit ratio of the external grid impedance of the grid-connected converter based on the grid impedance;

[0008] Based on the obtained short-circuit ratio, generate a converter control mode switching value T. If the control mode switching value T is set to 1, enter the weak grid control mode; if the control mode switching value T is set to 2, enter the strong grid control mode;

[0009] In the strong grid control mode, the converter switches to execute power loop control; in the weak grid control mode, the converter switches to execute torque damping control; both the strong grid control mode and the weak grid control mode continuously monitor the voltage and current of the new energy grid connection point, continuously generate the converter control mode switching value T; and switch the control mode according to the jump of the converter control mode switching value T.

[0010] Preferably, the grid impedance identification adopts a passive detection method, uses the inherent switching characteristics of the grid-connected converter to stimulate the grid response, measures the voltage and current harmonic information of the converter grid connection point, and directly calculates the fundamental wave grid impedance.

[0011] Preferably, the short-circuit ratio for calculating the external grid impedance of the grid-connected converter based on the grid impedance includes:

[0012] Dividing the square of the grid rated voltage by the product of the rated capacity of the power generation system, the grid rated angular frequency and the inductive component of the grid impedance to obtain the short-circuit ratio of the external grid impedance of the grid-connected converter.

[0013] Preferably, compare the obtained short-circuit ratio with the short-circuit ratio reference value. If the short-circuit ratio increases to be greater than the short-circuit ratio reference value, set the converter control mode switching value T to 2 in a jump manner and enter the strong grid control mode; if the short-circuit ratio decreases to be less than the short-circuit ratio reference value, set the converter control mode switching value T to 1 in a jump manner and enter the weak grid control mode.

[0014] Preferably, set multiple short-circuit ratio reference values, compare the obtained short-circuit ratio with the multiple short-circuit ratio reference values, and use hysteresis logic to achieve the jump of the T value.

[0015] Preferably, set a wide-area control link based on the port voltage and current of the single-machine grid-connected converter, including: an upper branch and a lower branch;

[0016] Among them, the upper branch calculates the short-circuit ratio based on the voltage and current to generate the converter control mode switching value T according to the value of the short-circuit ratio, which is used for the normal switching of the converter operation mode;

[0017] The lower branch calculates the harmonic content of the port voltage based on the voltage for initializing the converter control mode switching value.

[0018] Preferably, the lower branch selects the converter operation mode before startup according to the harmonic content limit value of the port voltage, including:

[0019] When it is greater than the root mean square upper limit value of the harmonic voltage at the converter grid connection point set the converter control mode switching value T to 1;

[0020] Less than the upper limit of the root mean square of harmonics of the converter connection point voltage When the control mode switching value T is set to 2; and,

[0021] When the harmonic content is greater than the lower limit of the root mean square of harmonics of the converter connection point voltage In this case, the control mode switching value T is set to 1 to force the selection of the weak grid operation mode.

[0022] Preferably, the operating condition of the lower branch is that the lower limit of the root mean square of harmonics of the converter connection point voltage is greater than the upper limit of the root mean square of harmonics of the converter connection point voltage .

[0023] Preferably, each controller individually selects the control mode according to the observed grid impedance; or

[0024] The coordinated controller observes the grid impedance based on the voltage and current at the centralized connection point and selects the cluster control mode; or

[0025] Both of the above two grid impedance measurement methods are configured in the same new energy power station.

[0026] The second aspect of the present invention provides a wide - area operation control system for a new energy power generation system, which operates the wide - area operation control method of the new energy power generation system described in the first aspect, including:

[0027] Voltage and current acquisition devices for acquiring the voltage and current at the new energy connection point;

[0028] A grid impedance identification module for obtaining the grid impedance based on the connection point voltage and current and calculating the short - circuit ratio;

[0029] A mode switching controller for generating a converter control mode switching value T based on the obtained short - circuit ratio. If the control mode switching value T is set to 1, the converter is controlled to enter the weak grid control mode; if the control mode switching value T is set to 2, the converter is controlled to enter the strong grid control mode.

[0030] The third aspect of the present invention provides an electronic device, including a memory, a processor, and a computer program stored on the memory and executable on the processor. When the computer program is loaded into the processor, it implements a wide - area operation control method for a new energy power generation system according to the first aspect.

[0031] The fourth aspect of the present invention provides a computer - readable storage medium, which stores a computer program. When the computer program is executed by a processor, it implements a wide - area operation control method for a new energy power generation system according to the first aspect.

[0032] Compared with the prior art, the beneficial effects of the present invention at least include:

[0033] 1. The present invention determines the strength of the external power grid based on the observed power grid impedance, and dynamically selects the core control algorithm module of the grid-connected converter applicable to different power grid strengths.

[0034] 2. The present invention adopts a composite method as the basis for selecting the grid-connected converter control strategy. One is to directly observe the power grid impedance based on the external voltage and current of the passive filter on the AC side of the converter; the other is to use the harmonic components of the grid-connected point voltage of the converter as an auxiliary basis for judging the system stability state, providing the initial working mode when the grid-connected converter starts. The two methods can be used alone or combined through a fuzzy algorithm as the basis for selecting the converter control strategy.

[0035] 3. The corresponding measurement and control strategy selection of the present invention can be carried out in two ways. One is to place it in a single grid-connected converter to directly observe the external power grid impedance from the converter port to provide control reference for this device; the other is to place it in an independent measurement device to observe the external power grid impedance of the centralized grid-connected point to provide control reference for the cluster devices.

[0036] The present invention establishes a composite technical basis for the converter control method and device suitable for wide-range operation, enabling the new energy grid-connected converter to dynamically select the control strategy according to the external power grid conditions, being able to maintain the system transmission efficiency under strong power grid conditions and maintain a reliable stability margin under weak power grid conditions, with good flexibility. BRIEF DESCRIPTION OF THE DRAWINGS

[0037] Figure 1 It is the basic control diagram of the new energy grid-connected converter described in the present invention;

[0038] Figure 2 It is the control mode switching logic of the new energy converter based on the external equivalent short-circuit ratio;

[0039] Figure 3 It is the functional diagram of the power grid impedance identification module;

[0040] Figure 4 It is the wide-range control structure diagram of the grid-connected converter based on in-situ measurement;

[0041] Figure 5 It is the wide-range control structure diagram of the grid-connected converter group based on substation measurement. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0042] To make the objectives, technical solutions, and advantages of the present invention clearer, the technical solutions of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. The described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. Based on the spirit of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the protection scope of the present invention.

[0043] Specifically, as Figure 1 shown, Embodiment 1 of the present invention discloses a wide - range operation control method for a new - energy power generation system, including the following steps:

[0044] Step 1: Collect the voltage and current at the new - energy grid connection point, obtain the grid impedance with a grid impedance identification module, and calculate the short - circuit ratio (SCR). Preferably but not restrictively, Step 1 specifically includes:

[0045] Step 1.1: Obtain the grid impedance in a grid impedance identification manner.

[0046] It can be understood that the grid impedance identification can adopt active detection or passive detection. Among them, active detection includes: injecting non - specific - order harmonic currents or voltages into the grid, and converting the grid impedance obtained from the voltage and current responses to the grid impedance corresponding to the fundamental frequency through extrapolation; or injecting wide - frequency signals to obtain the wide - frequency - domain grid impedance; or adopting methods such as increasing the control gain to excite resonance and obtaining the grid impedance according to the frequency of the resonance peak; or applying active - power and reactive - power perturbations to obtain the perturbation response by causing changes in the active power and reactive power output by the grid - connected inverter, so as to detect the grid impedance information.

[0047] Preferably but not restrictively, the present invention adopts the passive detection method, uses the inherent switching characteristics of the grid - connected converter to excite the grid response, measures the voltage and current harmonic information at the converter grid connection point, and directly calculates the fundamental - wave grid impedance. For example but not limited to, using a grid impedance observer; further preferably, the harmonic information of multiple frequency - doubling points can be used for calculation.

[0048] Specifically, by injecting harmonic current with a harmonic order of , the voltage response and current response of the PCC response can be obtained. The voltage response and current response of the PCC response are expressed by the following formula:

[0049]

[0050]

[0051] In the formula:

[0052] is the amplitude of the voltage response at the PCC when injecting harmonic current with a harmonic order of , is the phase of the voltage response at the PCC;

[0053] When injecting harmonic current with a harmonic order of the current response at the PCC, the amplitude, is the current response at the PCC the phase;

[0054] are the voltage response and the current response expansion coefficients respectively.

[0055] When injecting harmonic current with a harmonic order of the grid impedance is expressed by the following formula:

[0056]

[0057] Where:

[0058] is the amplitude of the grid impedance when injecting harmonic current with a harmonic order of the phase of the grid impedance, is the resistive component of the grid impedance, is the inductive component of the grid impedance.

[0059] As can be seen from the above formula, as long as the voltage and current harmonic information at the point of common coupling of the converter is measured, calculate the voltage response and the current response expansion coefficients, and substitute them into the above formula to complete the identification of the grid impedance.

[0060] Further preferably but not restrictively, calculate the voltage response and the current response expansion coefficients in an iterative manner, which are expressed by the following formula:

[0061]

[0062]

[0063] Where:

[0064] is the sampling period, is the number of sampling points in the sampling period, is the current real-time sampling point;

[0065] and are the calculated values at the th sampling moment and the th sampling moment respectively.

[0066] Step 1.2: Based on the grid impedance obtained in Step 1.1, calculate the short-circuit ratio of the external grid impedance of the grid-connected converter, which is expressed by the following formula:

[0067]

[0068] In the formula:

[0069] is the short-circuit ratio of the external grid impedance of the grid-connected converter;

[0070] is the rated grid voltage;

[0071] is the rated capacity of the power generation system;

[0072] is the rated angular frequency of the grid;

[0073] is the inductive component of the grid impedance.

[0074] It should be noted that the grid-connected converter is the main component of the new energy power generation system. The factors affecting the stable operation of the grid-connected converter include grid strength, control strategy, equipment performance (such as response speed, harmonic control ability, overload capacity, etc.), prime mover power, etc. The inventors of the present invention recognize that the change of grid strength (usually expressed as equivalent grid impedance or grid short-circuit capacity) has an important impact on the dynamic response characteristics of the new energy grid-connected converter. Under different grid impedance conditions, the output characteristics of the converter will change significantly, which will further lead to a large change in the system stability region.

[0075] The inventors of the present invention further recognize that on the power generation side of centralized grid connection of new energy and the distribution network side of distributed access of new energy, the grid impedance (or grid short-circuit ratio) fluctuates greatly due to the influence of local grid operation mode, volatility and intermittency of new energy prime mover power. On the power generation side of centralized grid connection, due to the volatility and intermittency of the prime mover, it is easy to have an operation scenario where the grid short-circuit ratio fluctuates greatly for the station capacity due to the single-unit connection and disconnection; on the distribution network side of distributed access, due to the limited grid capacity, the grid-connected converter is more likely to have an operation scenario where the grid short-circuit ratio drops to around 1. The power generation equipment is connected and disconnected according to the energy volatility and intermittency of the prime mover, and it is more likely to have a situation where the external equivalent grid impedance of the grid-connected converter fluctuates greatly. Therefore, as one of the prominent substantive features of the present invention, the core control algorithm of the grid-connected converter suitable for different grid strengths is dynamically selected by judging the external grid strength based on the observed grid impedance.

[0076] Step 2: Based on the short - circuit ratio obtained in Step 1, generate a converter control mode switching value T. If the control mode switching value T is set to 1, enter the weak grid control mode and execute Step 3; if the control mode switching value T is set to 2, enter the strong grid control mode and execute Step 4. It can be understood that setting the control mode switching value T to 1 or 2 is just a number given for the convenience of explaining the technical solution, and using any different numbers corresponding to the weak grid control mode and the strong grid control mode fall within the scope of the present invention.

[0077] Compare the short - circuit ratio obtained in Step 1 with the short - circuit ratio reference value. If the short - circuit ratio increases to be greater than the short - circuit ratio reference value, jump - set the control mode switching value T to 2, enter the strong grid control mode, and execute Step 4; if the short - circuit ratio decreases to be less than the short - circuit ratio reference value, jump - set the control mode switching value T to 1, enter the weak grid control mode, and execute Step 3.

[0078] Preferably but not restrictively, as Figure 2 shown, a control logic for avoiding jittery switching of the control mode is provided. Figure 2 According to the short - circuit ratio SCR corresponding to the external grid impedance of the grid - connected converter, give the switching value T corresponding to the ordinate, and use hysteresis logic to achieve the jump of the T value. In the figure, the abscissa SCR is the grid - side short - circuit ratio based on the rated capacity of the grid - connected converter. Figure 2 In it, K1 - K6 represent 6 different switching values, and the arrows represent the switching directions.

[0079] Further preferably but not restrictively, dividing into 6 different switching values is a preferred but non - restrictive implementation manner. More or fewer different switching values can be used to design the hysteresis logic to avoid jitter. The position of the switching point can be calculated according to specific algorithm analysis. The representation of K1 - K6 is intended to have not only switching based on the reference value but also delay retention after switching.

[0080] Preferably but not restrictively, as Figure 3 shown, a wide - area control logic based on the port voltage and current of a single - machine grid - connected converter is provided as an auxiliary method for determining the initial value of the control mode switching value T; it includes: an upper branch and a lower branch.

[0081] Among them, the upper branch sends the voltage and current through a band - pass filter into a grid impedance observer to obtain the short - circuit ratio, that is, in Step 1, obtain the grid impedance by the grid impedance identification module and calculate the short - circuit ratio, and generate the converter control mode switching value T according to the value of the short - circuit ratio, which is mainly used for the normal switching of the converter operation mode.

[0082] The lower branch sends the voltage The port voltage harmonic content is obtained through filters, such as but not limited to, band-stop filters and low-pass filters; before the converter is connected to the grid, the lower branch selects the operating mode of the converter before startup according to the port voltage harmonic content limit, including: when it is greater than the upper limit of the root mean square of the grid-connected point voltage harmonics of the converter the control mode switching value T is set to 1, that is, the weak grid operation mode is selected; when it is less than the upper limit of the root mean square of the grid-connected point voltage harmonics of the converter the control mode switching value T is set to 2, that is, the strong grid operation mode is selected; and when the harmonic content is relatively large, that is, greater than the lower limit of the root mean square of the grid-connected point voltage harmonics of the converter the control mode switching value T is set to 1 to force the selection of the weak grid operation mode.

[0083] The operating conditions of the lower branch are expressed by the following formula:

[0084]

[0085] In the formula:

[0086] is the upper limit of the root mean square of the grid-connected point voltage harmonics of the converter;

[0087] is the lower limit of the root mean square of the grid-connected point voltage harmonics of the converter.

[0088] It can be understood that the difference between the two branches is that the upper branch provides the basis for the control mode selection before the converter open pulse; the lower branch provides the control mode for forcing the converter to operate in support of weak grid operation when it is found that the grid-connected point harmonic component reaches a higher amplitude.

[0089] That is to say, as one of the prominent substantive features of the present invention, the present invention provides a composite method as the basis for the selection of the grid-connected converter control strategy in Figure 3 One is to directly observe the grid impedance according to the external voltage and current of the passive filter on the AC side of the converter (voltage and current are required); the other is to use the harmonic components of the grid-connected point voltage of the converter as an auxiliary basis for judging the system stability state (only voltage signal is required). The two methods can be used alone or combined through a fuzzy algorithm as the basis for the selection of the converter control strategy.

[0090] Preferably but not restrictively, Figure 4 is the control structure diagram of the new energy grid-connected converter for selecting a wide-area control mode based on the local grid-connected point voltage and current. "Based on the local grid-connected point voltage and current" means that each controller selects the control mode separately according to the grid impedance it observes; Figure 5 is the control structure diagram of the new energy grid-connected converter for selecting a wide-area control mode based on the centralized grid-connected point voltage and current. "Centralized grid-connected point voltage and current" means that the coordinated controller observes the grid-side impedance according to the voltage and current of the centralized grid-connected point and selects the cluster control mode.Figure 4 and Figure 5 The two operation modes shown in Figure 5 can be used alone or in combination in the same new energy power station. "Combined use" means that both of the above grid impedance measurement methods are configured in the same new energy power station.

[0091] Step 3: In the strong grid control mode, the converter switches to execute the power loop control. During the execution of the power loop control, return to Step 1, continuously monitor the voltage and current at the new energy grid connection point, and enter Step 2 to generate the converter control mode switching value T, and switch the control mode according to the jump of the converter control mode switching value T.

[0092] In a strong power grid, the grid impedance is small, and the converter can respond to system changes faster. This fast response ability helps to expand the system stability region, enabling the system to maintain stability under a wider range of conditions. The energy transfer efficiency of the converter under a strong power grid can be improved by optimizing the control algorithm, preferably but not limited to, the method based on power loop control, while enhancing the robustness and stability of the system.

[0093] Step 4: In the weak grid control mode, the converter switches to execute the torque damping control. During the execution of the torque damping control, return to Step 1, continuously monitor the voltage and current at the new energy grid connection point, and enter Step 2 to generate the converter control mode switching value T, and switch the control mode according to the jump of the converter control mode switching value T.

[0094] It should be noted that the change of the grid impedance (equivalent short-circuit ratio) is an uncontrollable factor that must be faced in the design of grid-connected converters, and the converter product can only be compensated by adjusting the control strategy to cope with the large-scale change of the grid impedance due to various factors. Specifically, in a weak power grid, the grid impedance is large, and the response speed of the converter to system disturbances decreases. The output characteristics of the converter will show obvious hysteresis, resulting in the inability to adjust the output in time to cope with grid fluctuations. This hysteresis effect compresses the system stability region, making the system prone to oscillation when disturbed. As the grid impedance increases, the phase margin of the converter system gradually decreases and crosses the critical value, resulting in obvious oscillation or even instability of the grid-connected current. In addition, problems such as harmonic interference and sub-synchronous oscillation that may be caused in a high-impedance environment will further limit the system stability region.

[0095] The inventor of the present invention realizes that under weak grid conditions, the converter needs to adopt a more cautious control strategy. Compared with the current common impedance reshaping technology, the damping torque technology can ensure that the system operates within a safe and stable region with sufficient amplitude margin and phase margin under lower grid short-circuit ratio conditions.

[0096] Embodiment 2 of the present invention provides a wide-area operation control system for a new energy power generation system, which operates the wide-area operation control method for a new energy power generation system described in Embodiment 1, including:

[0097] A voltage and current acquisition device for acquiring the voltage and current at the new energy grid connection point;

[0098] A grid impedance identification module that obtains the grid impedance based on the grid connection point voltage and current and calculates the short-circuit ratio;

[0099] A mode switching controller that generates a converter control mode switching value T based on the obtained short-circuit ratio. If the control mode switching value T is set to 1, the converter is controlled to enter the weak grid control mode; if the control mode switching value T is set to 2, the converter is controlled to enter the strong grid control mode.

[0100] Embodiment 3 of the present invention provides an electronic device, including a memory, a processor, and a computer program stored on the memory and executable on the processor. When the computer program is loaded into the processor, it implements a wide-area operation control method for a new energy power generation system according to Embodiment 1.

[0101] Embodiment 4 of the present invention provides a computer-readable storage medium. The computer-readable storage medium stores a computer program, and when the computer program is executed by a processor, it implements a wide-area operation control method for a new energy power generation system according to Embodiment 1.

[0102] After the above detailed introduction of the specific embodiments, those skilled in the art can know that the present invention relates to a wide-area operation control technology applicable to new energy power generation systems. By detecting the grid connection point voltage and current of the grid-connected converter, the grid impedance or the equivalent short-circuit ratio of the power source is observed, and the core control algorithm of the converter is dynamically selected according to the observed value. Generally speaking, the basic control block diagram of the wide-area control technology of the new energy power generation system described in the present invention is as shown in the figure, especially Figure 1 In part (a), it is a converter algorithm using torque damping control technology suitable for extremely low short-circuit ratio conditions in a weak grid, and in part (b), it is a converter control algorithm under strong grid conditions. In the figure, the grid impedance identification module samples the voltage and current at the external grid connection point of the grid-connected converter to observe the equivalent grid impedance and switch the core algorithm of the converter according to the grid impedance value.

[0103] Compared with the prior art, the significant differences of the present invention at least include: proposing to use the power impedance estimated by a new energy single machine or cluster system as the basis for switching the control mode of the grid-connected converter system / cluster. This method is used in the new energy power station for both the control mode switching of the single machine system and the overall dynamic selection of the control mode of the grid-connected converter cluster system, taking into account the complex situation in the new energy power station where there are differences between the local power impedance and the power impedance at the centralized grid connection point due to the decentralized layout of the power generation system; the present invention also proposes to use the harmonic content of the grid connection point voltage to select the initial control mode of the converter and constructs a complete cluster control system; at the same time, a converter control mode suitable for extremely low short-circuit ratio conditions is selected. Based on these prominent substantive features, the significant progress brought by the present invention to the prior art at least includes: building a control mode selection system that takes into account individuals / parts / wholes for the grid-connected converter cluster in the new energy power station, providing a basis for selecting the initial control mode of the grid-connected converter, and enabling the new energy power station to operate under extremely low short-circuit ratio conditions.

[0104] The present disclosure may be a system, method, and / or computer program product. The computer program product may include a computer-readable storage medium having computer-readable program instructions thereon for causing a processor to implement various aspects of the present disclosure.

[0105] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit them. Although the present invention has been described in detail with reference to the above embodiments, those of ordinary skill in the art should understand that: the specific implementation manners of the present invention can still be modified or equivalently replaced, and any modification or equivalent replacement that does not depart from the spirit and scope of the present invention shall be covered by the protection scope of the claims of the present invention.

Claims

1. A wide - area operation control method for a new - energy power generation system, characterized in that, It includes the following steps: Collect the voltage and current at the new energy grid connection point, obtain the grid impedance through grid impedance identification, and calculate the short-circuit ratio of the external grid impedance of the grid-connected converter based on the grid impedance. Based on the obtained short-circuit ratio, generate the converter control mode switching value T. If the control mode switching value T is set to 1, enter the weak grid control mode. If the control mode switching value T is set to 2, enter the strong grid control mode. Set the wide-area control link based on the port voltage and current of the single-machine grid-connected converter and current The wide-area control link includes: an upper branch and a lower branch; among them, the upper branch calculates the short-circuit ratio based on the voltage and current to obtain the short-circuit ratio, and generate the converter control mode switching value T according to the value of the short-circuit ratio for the normal switching of the converter operation mode; the lower branch calculates the harmonic content of the port voltage based on the voltage for the initialization of the converter control mode switching value The lower branch selects the operating mode of the converter before startup according to the harmonic content limit of the port voltage, including: when it is greater than the upper limit of the root mean square of the harmonic voltage at the grid connection point of the converter the control mode switching value T is set to 1; when it is less than the upper limit of the root mean square of the harmonic voltage at the grid connection point of the converter the control mode switching value T is set to 2; and, when the harmonic content is greater than the lower limit of the root mean square of the harmonic voltage at the grid connection point of the converter the control mode switching value T is forcibly set to 1 to select the weak grid operation mode. Among them, the operating condition of the lower branch is: the lower limit of the root mean square of the harmonic voltage at the grid connection point of the converter is greater than the upper limit of the root mean square of the harmonic voltage at the grid connection point of the converter ; In the strong grid control mode, the converter switches to execute power loop control; in the weak grid control mode, the converter switches to execute torque damping control. Both the strong grid control mode and the weak grid control mode continuously monitor the voltage and current at the new energy grid connection point, continuously generate the converter control mode switching value T; and switch the control mode according to the jump of the converter control mode switching value T.

2. A wide-area operation control method for a new energy power generation system according to claim 1, characterized in that: The grid impedance identification adopts a passive detection method, uses the inherent switching characteristics of the grid-connected converter to stimulate the grid response, measures the voltage and current harmonic information at the converter grid connection point, and directly calculates the fundamental wave grid impedance.

3. A wide-area operation control method for a new energy power generation system according to claim 1, characterized in that: The calculation of the short-circuit ratio of the external grid impedance of the grid-connected converter based on the grid impedance includes: Dividing the square of the grid rated voltage by the product of the rated capacity of the power generation system, the grid rated angular frequency and the inductive component of the grid impedance to obtain the short-circuit ratio of the external grid impedance of the grid-connected converter.

4. A wide-area operation control method for a new energy power generation system according to claim 1, characterized in that: Compare the obtained short-circuit ratio with the short-circuit ratio reference value. If the short-circuit ratio increases to be greater than the short-circuit ratio reference value, set the control mode switching value T to 2 in a jump manner and enter the strong grid control mode; if the short-circuit ratio decreases to be less than the short-circuit ratio reference value, set the control mode switching value T to 1 in a jump manner and enter the weak grid control mode.

5. A wide-area operation control method for a new energy power generation system according to claim 1 or 4, characterized in that: Set multiple short-circuit ratio reference values, compare the obtained short-circuit ratio with the multiple short-circuit ratio reference values, and use hysteresis logic to achieve the jump of the T value.

6. A wide-area operation control method for a new energy power generation system according to claim 1, characterized in that: Each controller separately selects a control mode according to the grid impedance it observes; or The coordinated controller selects a cluster control mode according to the voltage and current at the centralized grid connection point to observe the grid impedance; or In the same new energy power station, each controller separately selects a control mode according to the grid impedance it observes and the coordinated controller selects a cluster control mode according to the voltage and current at the centralized grid connection point to observe the grid impedance are mixedly configured.

7. A wide - range operation control system for a new - energy power generation system, which operates the wide - range operation control method of the new - energy power generation system described in any one of claims 1 to 6, characterized in that, It includes: A voltage and current acquisition device for collecting the voltage and current at the new energy grid connection point; A grid impedance identification module for obtaining the grid impedance based on the voltage and current at the grid connection point and calculating the short-circuit ratio; A mode switching controller for generating the converter control mode switching value T based on the obtained short-circuit ratio. If the control mode switching value T is set to 1, control the converter to enter the weak grid control mode; If the control mode switching value T is set to 2, the control converter enters the strong grid control mode.

8. An electronic device, comprising a memory, a processor, and a computer program stored on the memory and executable on the processor, wherein when the computer program is loaded onto the processor, it implements a wide-area operation control method for a new energy power generation system according to any one of claims 1 to 6.

9. A computer-readable storage medium storing a computer program, wherein when the computer program is executed by a processor, it implements a wide-area operation control method for a new energy power generation system according to any one of claims 1 to 6.

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