Method and system for evaluating and quantifying influence of wind power plant access on power grid harmonic waves

Abstract

The invention discloses a method and a system for evaluating and quantifying the influence of wind power plant access on power grid harmonic waves, and the method comprises the steps: building a wind power plant model, setting corresponding harmonic emission characteristics for all new energy equipment, and sequentially accessing all harmonic sources according to different operation conditions of a wind power plant; and carrying out harmonic power flow calculation and recording the amplitude of each harmonic current injected to the power grid common connection point after each harmonic source is independently connected. Considering the unknown phase angle of each harmonic injected into the power grid by each new energy device, overlay analysis is carried out based on a set phase angle coefficient value, and the current of each harmonic injected into the power grid by the wind power plant is obtained. And finally, quantitatively analyzing the harmonic influence on the power grid in the operation process of the wind power plant according to a set harmonic standard. The method can accurately evaluate the harmonic influence of the wind power plant on the power grid, provides a scientific basis for the planning and operation of the wind power plant, and has a wide application prospect.

Description

Technical Field

[0001] The present invention belongs to the technical field of harmonic impact assessment, and more specifically, relates to a quantitative method and system for assessing the harmonic impact of wind farm access on a power grid. Background Art

[0002] With the transformation of the global energy structure, clean and renewable energy, such as wind power and solar energy, has gradually become one of the main forms of power generation. The large-scale access of wind farms has gradually led to the development of traditional power systems in the direction of distributed, intelligent and green. This transformation not only promotes the efficient use of energy, reduces greenhouse gas emissions, but also reduces dependence on fossil fuels. However, the access of wind farms has brought new challenges to the stability of the power grid.

[0003] Renewable energy generation (especially photovoltaic power generation, wind power, etc.) usually uses power electronic devices (such as inverters) to connect to the power grid. These power electronic devices operate at high frequencies and may generate a large amount of nonlinear current, thereby causing the generation of harmonic currents. Harmonics are a non-ideal phenomenon in power grid operation, usually caused by nonlinear loads or power electronic devices. When a wind farm is connected to the power grid, the harmonics it generates may cause the power quality of the power grid to deteriorate and even affect the operating stability of the equipment.

[0004] The presence of harmonic currents can cause a series of adverse effects, including:

[0005] (1) Deterioration of power quality: Harmonic distortion will affect the quality of the voltage waveform, causing voltage distortion, which in turn affects the normal operation of other electrical equipment.

[0006] (2) Shortened equipment life: High-frequency harmonic components can cause equipment to heat up, shortening the service life of transformers, cables and other equipment in the power grid.

[0007] (3) Reduced system stability: The accumulation of a large amount of harmonics will cause malfunction of relay protection and automation devices, reducing the safety and reliability of power grid operation.

[0008] In order to ensure the safe operation of the power grid, the evaluation and monitoring of power quality has become one of the important tasks of the power industry. After the wind farm is connected to the grid, how to effectively evaluate its impact on the grid harmonics has become an issue that cannot be ignored in the process of grid planning and operation.

[0009] The patent with the publication number CN118117601A discloses a method for calculating the harmonic source of an offshore wind farm AC access system, including: collecting funds from the offshore wind farm and the public connection point of the power grid; calculating the resonance point and analyzing the resonance characteristics; calculating the harmonic current injected by the offshore wind farm wind turbine into the grid connection point and the harmonic current amplification factor; calculating the background voltage distortion rate on the grid side to stimulate the harmonic current at the grid connection point; calculating the harmonic contribution ratio of the grid side harmonic current source at the grid connection point; calculating the voltage distortion rate at the public connection point of the power grid after the offshore wind farm is connected; calculating the increase ratio of the voltage distortion rate at the public connection point of the power grid. However, the harmonic model constructed by the patent for each component on the grid side is relatively rough, and the description of the background harmonics is not accurate enough. In actual application, the error is large.

[0010] The patent with publication number CN108879759A discloses a harmonic analysis and control method for grid-connected doubly-fed wind turbines. Based on the mathematical model of doubly-fed wind turbines, an electromagnetic transient model of doubly-fed wind turbines is constructed; the electromagnetic transient simulation calculation of the wind farm is performed using the ADPSS simulation system to obtain the harmonic current and harmonic voltage injected into the grid by the wind farm; the obtained harmonic current and harmonic voltage input into the grid by the wind farm are compared with the limit values ​​to determine whether the harmonic current or harmonic voltage input into the grid by the wind farm exceeds the standard; if the harmonic current input into the grid by the wind farm exceeds the standard, an active filter is designed to establish an electromagnetic transient model of the wind farm containing the active filter, and the harmonic current in the grid is compensated. However, this patent focuses on harmonic modeling of doubly-fed wind turbines, and is not universal for different wind farms. In addition, the harmonic models of various components on the grid side and the characterization of background harmonics are relatively vague, and cannot accurately reflect the impact after considering background harmonics.

[0011] Moreover, the above patents do not take into account the differences in wind farms and grid access conditions (such as access points, access power, geographical locations, etc.), and the different degrees and manifestations of harmonic impact. Summary of the invention

[0012] In order to solve the deficiencies in the prior art, the present invention provides a method and system for quantifying the harmonic impact assessment of wind farm access on the power grid. By building a wind farm model, connecting each harmonic source in turn, and performing harmonic flow calculation, the harmonic current injected into the common connection point by each harmonic source is superimposed and analyzed, and the harmonic impact on the power grid during the operation of the wind farm is quantitatively analyzed.

[0013] The present invention adopts the following technical solution.

[0014] The first aspect of the present invention provides a method for quantifying the impact of wind farm access on power grid harmonics, comprising:

[0015] Build a wind farm harmonic model and set corresponding harmonic emission characteristics for wind turbines;

[0016] Connect each harmonic source to the wind farm harmonic model, perform harmonic power flow calculation for different operating conditions of the wind farm, and record the amplitude of each harmonic current injected by each harmonic source to the common connection point of the power grid. The harmonic source is a nonlinear element in the wind farm, and the operating conditions include wind speed, wind direction, and the operating status of the wind turbine.

[0017] Based on the set harmonic phase coefficient value, the harmonic currents injected into the public connection point by each harmonic source are superimposed and analyzed to obtain the magnitude of each harmonic current injected into the power grid by the wind farm;

[0018] Combined with the pre-set harmonic standards, the harmonic impact on the power grid caused by the operation of the wind farm is quantitatively analyzed.

[0019] Preferably, the wind farm harmonic model is constructed by: constructing the model according to the topological structure of the wind farm, the topological structure of the wind farm including a step-up transformer, a reactive power compensation device, a collector line, a box transformer, and a wind turbine;

[0020] Determine the type, quantity and distribution of wind turbines installed in the wind farm, wherein the wind turbines include permanent magnet direct drive type and double-fed type;

[0021] Record the electrical connection relationship of each wind turbine, including the connection method between the generator and the inverter, the layout of the collector line, the configuration of the step-up transformer, and the location of the connection point between the wind farm and the power grid;

[0022] Determine the total installed capacity of the wind farm and the rated power of each wind turbine, and record the output power changes of the wind farm under different wind speed conditions;

[0023] The wind turbines in the wind farm harmonic model are configured according to the types, quantity and distribution of wind turbines determined and recorded above, the electrical connection relationship of each wind turbine, the total installed capacity of the wind farm and the rated power of each wind turbine, and the output power changes of the wind farm under different wind speed conditions.

[0024] Preferably, the corresponding harmonic emission characteristics are set for the wind turbine generator set, specifically:

[0025] Based on the harmonic emission data provided by the manufacturer, relevant standards or actual measurement data, the harmonic emission characteristics under different operating conditions are set for each wind turbine set, and the harmonic emission characteristics are the current or voltage distortion rate of each harmonic.

[0026] Preferably, each harmonic source is connected to the wind farm harmonic model, harmonic power flow calculation is performed for different operating conditions of the wind farm, and the amplitude of each harmonic current injected by each harmonic source to the common connection point of the power grid is recorded, specifically:

[0027] Identify the harmonic sources of the wind farm, simulate the wind farm harmonic model under actual operating conditions according to the set simulation conditions and the set order and method of connecting the harmonic sources to the power grid, obtain the proportion of the amplitude of each harmonic current emitted by the wind farm to the amplitude of the fundamental current, as well as the node admittance matrix and transfer impedance matrix characterized by each harmonic of the wind farm. These two matrices are inverse matrices of each other. The node admittance matrix characterized by a certain harmonic is obtained by dividing the harmonic voltage of the harmonic by the node current; the wind turbine inputs the proportion of the amplitude of each harmonic current emitted by the wind farm to the amplitude of the fundamental current, as well as the node admittance matrix and transfer impedance matrix characterized by each harmonic of the wind farm into the harmonic power flow calculation software, performs harmonic power flow calculation, and outputs and records the amplitude of each harmonic current.

[0028] Preferably, the set simulation conditions and the set order and method of connecting harmonic sources to the power grid are specifically:

[0029] The simulation conditions include the structure, impedance parameters, and load conditions of the power grid, which are the same as the actual conditions of the power grid;

[0030] The order and method of setting the harmonic sources to access the power grid are as follows: each harmonic source is connected in turn. In each calculation, only the effect of one harmonic source is considered, and the other harmonic sources are regarded as ideal elements that do not generate harmonics.

[0031] Preferably, based on the set harmonic phase coefficient value, the harmonic currents injected into the common connection point by each harmonic source are superimposed and analyzed to obtain the magnitudes of each harmonic current injected into the power grid by the wind farm, specifically:

[0032] The same harmonic currents of two harmonic sources are superimposed on the same phase of a line, and the phase angle is uncertain. The calculation formula for the harmonic current after superposition is:

[0033]

[0034] In the formula, K h is the phase angle coefficient value of the set harmonic; I h1 is the hth harmonic current of the first harmonic source; I h2 is the hth harmonic current of the second harmonic source; θ h is the phase angle between the hth harmonic currents of the first harmonic source and the second harmonic source;

[0035] When n harmonic currents of the same order are superimposed, where n is greater than 2, the harmonic currents of the first and second harmonic sources are superimposed first, and then the result is superimposed with the harmonic current of the third harmonic source, and the result is superimposed with the harmonic current of the fourth harmonic source, until the harmonic current of the nth harmonic source is superimposed.

[0036] Preferably, in combination with a preset harmonic standard, a quantitative analysis is performed on the harmonic impact on the power grid during the operation of the wind farm, specifically:

[0037] Combined with the pre-set harmonic standards, the allowable harmonic value of the wind farm is calculated, and the calculated results of the magnitude of each harmonic current injected by the wind farm into the power grid are compared with the corresponding allowable harmonic value. If the calculated results of the magnitude of each harmonic current injected by the wind farm into the power grid are greater than the corresponding allowable harmonic value, it means that the wind farm has a large harmonic impact on the power grid. Otherwise, it means that the wind farm has a small harmonic impact on the power grid.

[0038] Preferably, the harmonic allowable value of the wind farm is calculated in combination with a preset harmonic standard, specifically: the minimum short-circuit capacity of the common connection point is compared with the set reference short-circuit capacity. If the two are the same, the harmonic allowable value of the wind farm is the set harmonic allowable value. Otherwise, the set harmonic current allowable value is corrected according to the following formula:

[0039]

[0040] Where: S k1 is the minimum short-circuit capacity of the common connection point, S k2 is the benchmark short-circuit capacity; I hp is the set hth harmonic current allowable value; I h The short-circuit capacity is S k1 The allowable value of the hth harmonic current when

[0041] The hth harmonic current allowable value I of the i-th harmonic source at the common connection point hi Calculated as follows:

[0042]

[0043] Where: S i is the power consumption agreement capacity of the i-th user; S t is the capacity of the power supply equipment at the public connection point; α is the phase superposition coefficient.

[0044] The second aspect of the present invention proposes a quantitative system for evaluating the harmonic impact of wind farm access on the power grid using the quantitative analysis method described in the first aspect of the present invention, including a harmonic model building module, a harmonic current calculation module of a harmonic source, a harmonic superposition calculation module and a quantitative analysis module, specifically:

[0045] Harmonic model building module: build a wind farm harmonic model and set corresponding harmonic emission characteristics for wind turbines;

[0046] Harmonic current calculation module of harmonic source: connect each harmonic source to the wind farm harmonic model, perform harmonic power flow calculation for different operating conditions of the wind farm, and record the amplitude of each harmonic current injected by each harmonic source to the public connection point of the power grid. The harmonic source is a nonlinear element in the wind farm, and the operating conditions include wind speed, wind direction, and the operating status of the wind turbine;

[0047] Harmonic superposition calculation module: Based on the set phase angle coefficient value, the harmonic current injected into the public connection point by each harmonic source is superimposed and analyzed to obtain the magnitude of each harmonic current injected into the power grid by the wind farm;

[0048] Quantitative analysis module: Combined with the pre-set harmonic standards, quantitative analysis is performed on the harmonic impact on the power grid during the operation of the wind farm.

[0049] The third aspect of the present invention proposes an electronic device, comprising a memory, a processor, and a computer program stored in the memory and executable on the processor. When the computer program is loaded into the processor, the method for quantitatively assessing the harmonic impact of wind farm access on the power grid according to the first aspect of the present invention is implemented.

[0050] A fourth aspect of the present invention provides a computer-readable storage medium storing a computer program, which, when executed by a processor, implements the method for quantifying the impact of wind farm access on power grid harmonics according to the first aspect of the present invention.

[0051] The beneficial effect of the present invention is that, compared with the prior art, by establishing a wind farm model and setting corresponding harmonic emission characteristics, the impact of new energy equipment on grid harmonics under different operating conditions can be simulated more accurately. By calculating the harmonic flow after each harmonic source is connected separately, the harmonic currents injected into the grid by each device can be effectively quantified. Furthermore, based on the typical value of the set harmonic phase angle coefficient, the harmonic currents injected into the common connection point of the grid by each harmonic source are superimposed and analyzed, so that even when the phase angle is unknown, a relatively accurate total amount of harmonic current can be obtained. Finally, quantitative analysis combined with the set harmonic standard can comprehensively evaluate the impact of wind farms on grid harmonics, improve the operational stability and safety of the grid, and have strong practical value and engineering application prospects. BRIEF DESCRIPTION OF THE DRAWINGS

[0052] Figure 1 is the wind farm topology model;

[0053] Figure 2 Flowchart of the quantitative method for evaluating the harmonic impact of wind farm access on the power grid. DETAILED DESCRIPTION

[0054] In order to make the purpose, technical scheme and advantages of the present invention clearer, the technical scheme of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. The embodiments described in this application are only part of the embodiments of the present invention, not all of them. Based on the spirit of the present invention, other embodiments obtained by ordinary technicians in this field without creative work are all within the scope of protection of the present invention.

[0055] The present invention adopts the following technical solution.

[0056] like Figure 2 As shown, Embodiment 1 of the present invention proposes a method for quantifying the impact of wind farm access on power grid harmonics, including:

[0057] Build a wind farm harmonic model and set corresponding harmonic emission characteristics for wind turbines.

[0058] Preferably, the wind farm harmonic model is constructed by: constructing the model according to the topological structure of the wind farm, the topological structure of the wind farm including a step-up transformer, a reactive power compensation device, a collector line, a box transformer, and a wind turbine;

[0059] Determine the type, quantity and distribution of wind turbines installed in the wind farm, wherein the wind turbines include permanent magnet direct drive type and double-fed type;

[0060] Record the electrical connection relationship of each wind turbine, including the connection method between the generator and the inverter, the layout of the collector line, the configuration of the step-up transformer, and the location of the connection point between the wind farm and the power grid;

[0061] Determine the total installed capacity of the wind farm and the rated power of each wind turbine, and record the output power changes of the wind farm under different wind speed conditions;

[0062] The wind turbines in the wind farm harmonic model are configured according to the types, quantity and distribution of wind turbines determined and recorded above, the electrical connection relationship of each wind turbine, the total installed capacity of the wind farm and the rated power of each wind turbine, and the output power changes of the wind farm under different wind speed conditions.

[0063] Preferably, the corresponding harmonic emission characteristics are set for the wind turbine generator set, specifically:

[0064] Based on the harmonic emission data provided by the manufacturer, relevant standards or actual measurement data, the harmonic emission characteristics under different operating conditions are set for each wind turbine set, and the harmonic emission characteristics are the current or voltage distortion rate of each harmonic.

[0065] Specifically, the relevant standards include IEC 61400-21 and IEEE Std 519.

[0066] Each harmonic source is connected to the wind farm harmonic model, and harmonic power flow calculation is performed for different operating conditions of the wind farm. The amplitude of each harmonic current injected by each harmonic source into the common connection point of the power grid is recorded. The harmonic source is a nonlinear element in the wind farm, and the operating conditions include wind speed, wind direction, and the operating status of the wind turbine.

[0067] Preferably, each harmonic source is connected to the wind farm harmonic model, harmonic power flow calculation is performed for different operating conditions of the wind farm, and the amplitude of each harmonic current injected by each harmonic source to the common connection point of the power grid is recorded, specifically:

[0068] Identify the harmonic sources of the wind farm, simulate the wind farm harmonic model under actual operating conditions according to the set simulation conditions and the set order and method of connecting the harmonic sources to the power grid, obtain the proportion of the amplitude of each harmonic current emitted by the wind farm to the amplitude of the fundamental current, as well as the node admittance matrix and transfer impedance matrix characterized by each harmonic of the wind farm. These two matrices are inverse matrices of each other. The node admittance matrix characterized by a certain harmonic is obtained by dividing the harmonic voltage of the harmonic by the node current; the wind turbine inputs the proportion of the amplitude of each harmonic current emitted by the wind farm to the amplitude of the fundamental current, as well as the node admittance matrix and transfer impedance matrix characterized by each harmonic of the wind farm into the harmonic power flow calculation software, performs harmonic power flow calculation, and outputs and records the amplitude of each harmonic current.

[0069] Preferably, the set simulation conditions and the set order and method of connecting harmonic sources to the power grid are specifically:

[0070] The simulation conditions include the structure, impedance parameters, and load conditions of the power grid, which are the same as the actual conditions of the power grid;

[0071] The order and method of setting the harmonic sources to access the power grid are as follows: each harmonic source is connected in turn. In each calculation, only the effect of one harmonic source is considered, and the other harmonic sources are regarded as ideal elements that do not generate harmonics.

[0072] Based on the set harmonic phase coefficient value, the harmonic currents injected into the public connection point by each harmonic source are superimposed and analyzed to obtain the magnitude of each harmonic current injected into the power grid by the wind farm.

[0073] Preferably, based on the set harmonic phase coefficient value, the harmonic currents injected into the common connection point by each harmonic source are superimposed and analyzed to obtain the magnitudes of each harmonic current injected into the power grid by the wind farm, specifically:

[0074] The same harmonic currents of two harmonic sources are superimposed on the same phase of a line, and the phase angle is uncertain. The calculation formula for the harmonic current after superposition is:

[0075]

[0076] In the formula, K h is the phase angle coefficient value of the set harmonic; I h1 is the hth harmonic current of the first harmonic source; I h2 is the hth harmonic current of the second harmonic source; θ h is the phase angle between the hth harmonic currents of the first harmonic source and the second harmonic source;

[0077] When n harmonic currents of the same order are superimposed, where n is greater than 2, the harmonic currents of the first and second harmonic sources are superimposed first, and then the result is superimposed with the harmonic current of the third harmonic source, and the result is superimposed with the harmonic current of the fourth harmonic source, until the harmonic current of the nth harmonic source is superimposed.

[0078] Specifically, K h The coefficients are selected according to Table 1.

[0079] Table 1K h Coefficient value

[0080]

[0081] Combined with the pre-set harmonic standards, the harmonic impact on the power grid caused by the operation of the wind farm is quantitatively analyzed.

[0082] Preferably, in combination with a preset harmonic standard, a quantitative analysis is performed on the harmonic impact on the power grid during the operation of the wind farm, specifically:

[0083] Combined with the pre-set harmonic standards, the allowable harmonic value of the wind farm is calculated, and the calculated results of the magnitude of each harmonic current injected by the wind farm into the power grid are compared with the corresponding allowable harmonic value. If the calculated results of the magnitude of each harmonic current injected by the wind farm into the power grid are greater than the corresponding allowable harmonic value, it means that the wind farm has a large harmonic impact on the power grid. Otherwise, it means that the wind farm has a small harmonic impact on the power grid.

[0084] Preferably, the harmonic allowable value of the wind farm is calculated in combination with a preset harmonic standard, specifically: the minimum short-circuit capacity of the common connection point is compared with the set reference short-circuit capacity. If the two are the same, the harmonic allowable value of the wind farm is the set harmonic allowable value. Otherwise, the set harmonic current allowable value is corrected according to the following formula:

[0085]

[0086] Where: S k1 is the minimum short-circuit capacity of the common connection point, S k2 is the benchmark short-circuit capacity; I hp is the set hth harmonic current allowable value; Ih The short-circuit capacity is S k1 The allowable value of the hth harmonic current when

[0087] The hth harmonic current allowable value I of the i-th harmonic source at the common connection point hi Calculated as follows:

[0088]

[0089] Where: S i is the power consumption agreement capacity of the i-th user; S t is the capacity of the power supply equipment at the public connection point; α is the phase superposition coefficient.

[0090] The harmonic standard set in the present invention is set according to the harmonic value specified in the relevant national standards, as shown in Table 2;

[0091] Table 2 Harmonic order and allowable value of harmonic current

[0092]

[0093] Specifically, the phase superposition coefficient values ​​are shown in Table 3;

[0094] Table 3 Phase superposition coefficient values

[0095] H 3 5 7 9 11 Alpha 1.1 1.2 1.4 2.0 1.8

[0096] Embodiment 2 of the present invention proposes a quantitative system for evaluating the harmonic impact of wind farm access on the power grid using the quantitative analysis method described in Embodiment 1 of the present invention, including a harmonic model building module, a harmonic current calculation module of a harmonic source, a harmonic superposition calculation module and a quantitative analysis module, specifically:

[0097] Harmonic model building module: build a wind farm harmonic model and set corresponding harmonic emission characteristics for wind turbines;

[0098] Harmonic current calculation module of harmonic source: connect each harmonic source to the wind farm harmonic model, perform harmonic power flow calculation for different operating conditions of the wind farm, and record the amplitude of each harmonic current injected by each harmonic source to the public connection point of the power grid. The harmonic source is a nonlinear element in the wind farm, and the operating conditions include wind speed, wind direction, and the operating status of the wind turbine;

[0099] Harmonic superposition calculation module: Based on the set phase angle coefficient value, the harmonic current injected into the public connection point by each harmonic source is superimposed and analyzed to obtain the magnitude of each harmonic current injected into the power grid by the wind farm;

[0100] Quantitative analysis module: Combined with the pre-set harmonic standards, quantitative analysis is performed on the harmonic impact on the power grid during the operation of the wind farm.

[0101] Embodiment 3 of the present invention proposes an electronic device, comprising a memory, a processor, and a computer program stored in the memory and executable on the processor. When the computer program is loaded into the processor, the method for quantitatively evaluating the harmonic impact of wind farm access on the power grid according to Embodiment 1 of the present invention is implemented.

[0102] Embodiment 4 of the present invention proposes a computer-readable storage medium, which stores a computer program. When the computer program is executed by a processor, the method for quantifying the impact of wind farm access on power grid harmonics according to Embodiment 1 of the present invention is implemented.

[0103] The present disclosure may be a system, a method and / or a computer program product. The computer program product may include a computer-readable storage medium carrying computer-readable program instructions for causing a processor to implement various aspects of the present disclosure.

[0104] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention rather than to limit it. Although the present invention has been described in detail with reference to the above embodiments, ordinary technicians in the relevant field should understand that the specific implementation methods of the present invention can still be modified or replaced by equivalents, and any modifications or equivalent replacements that do not depart from the spirit and scope of the present invention should be covered within the scope of protection of the claims of the present invention.

Claims

1. A quantitative method for evaluating the impact of wind farm access on power grid harmonics, characterized in that: include: Build a wind farm harmonic model and set corresponding harmonic emission characteristics for wind turbines; Connect each harmonic source to the wind farm harmonic model, perform harmonic power flow calculation for different operating conditions of the wind farm, and record the amplitude of each harmonic current injected by each harmonic source to the common connection point of the power grid. The harmonic source is a nonlinear element in the wind farm, and the operating conditions include wind speed, wind direction, and the operating status of the wind turbine. Based on the set harmonic phase coefficient value, the harmonic currents injected into the public connection point by each harmonic source are superimposed and analyzed to obtain the magnitude of each harmonic current injected into the power grid by the wind farm; Combined with the pre-set harmonic standards, the harmonic impact on the power grid caused by the operation of the wind farm is quantitatively analyzed.

2. A method for quantifying the impact of wind farm access on power grid harmonics according to claim 1, characterized in that: include: The wind farm harmonic model is constructed by: constructing the model according to the topological structure of the wind farm, where the topological structure of the wind farm includes a step-up transformer, a reactive power compensation device, a collector line, a box transformer, and a wind turbine; Determine the type, quantity and distribution of wind turbines installed in the wind farm, wherein the wind turbines include permanent magnet direct drive type and double-fed type; Record the electrical connection relationship of each wind turbine, including the connection method between the generator and the inverter, the layout of the collector line, the configuration of the step-up transformer, and the location of the connection point between the wind farm and the power grid; Determine the total installed capacity of the wind farm and the rated power of each wind turbine, and record the output power changes of the wind farm under different wind speed conditions; The wind turbines in the wind farm harmonic model are configured according to the types, quantity and distribution of wind turbines determined and recorded above, the electrical connection relationship of each wind turbine, the total installed capacity of the wind farm and the rated power of each wind turbine, and the output power changes of the wind farm under different wind speed conditions.

3. A method for quantifying the impact of wind farm access on power grid harmonics according to claim 2, characterized in that: The corresponding harmonic emission characteristics are set for the wind turbine, specifically: Based on the harmonic emission data provided by the manufacturer, relevant standards or actual measurement data, the harmonic emission characteristics under different operating conditions are set for each wind turbine set, and the harmonic emission characteristics are the current or voltage distortion rate of each harmonic.

4. A method for quantifying the impact of wind farm access on power grid harmonics according to claim 3, characterized in that: include: The harmonic sources are connected to the wind farm harmonic model, harmonic power flow calculation is performed for different operating conditions of the wind farm, and the amplitude of each harmonic current injected by each harmonic source to the public connection point of the power grid is recorded, specifically: Identify the harmonic sources of the wind farm, simulate the wind farm harmonic model under actual operating conditions according to the set simulation conditions and the set order and method of connecting the harmonic sources to the power grid, obtain the proportion of the amplitude of each harmonic current emitted by the wind farm to the amplitude of the fundamental current, as well as the node admittance matrix and transfer impedance matrix characterized by each harmonic of the wind farm. These two matrices are inverse matrices of each other. The node admittance matrix characterized by a certain harmonic is obtained by dividing the harmonic voltage of the harmonic by the node current. The wind turbine group inputs the proportion of the amplitude of each harmonic current emitted by the wind farm to the amplitude of the fundamental current, as well as the node admittance matrix and transfer impedance matrix characterized by each harmonic of the wind farm into the harmonic power flow calculation software, performs harmonic power flow calculation, and outputs and records the amplitude of each harmonic current.

5. A method for quantifying the impact of wind farm access on power grid harmonics according to claim 4, characterized in that: include: The simulation conditions and the order and method of connecting the harmonic sources to the power grid are specifically as follows: The simulation conditions include the structure, impedance parameters, and load conditions of the power grid, which are the same as the actual conditions of the power grid; The order and method of setting the harmonic sources to access the power grid are as follows: each harmonic source is connected in turn. In each calculation, only the effect of one harmonic source is considered, and the other harmonic sources are regarded as ideal elements that do not generate harmonics.

6. A method for quantifying the impact of wind farm access on power grid harmonics according to claim 1, characterized in that: include: Based on the set harmonic phase coefficient value, the harmonic currents injected into the common connection point by each harmonic source are superimposed and analyzed to obtain the magnitude of each harmonic current injected into the power grid by the wind farm, specifically: The same harmonic currents of two harmonic sources are superimposed on the same phase of a line, and the phase angle is uncertain. The calculation formula for the harmonic current after superposition is: In the formula, K h is the phase angle coefficient value of the set harmonic; I h1 is the hth harmonic current of the first harmonic source; I h2 is the hth harmonic current of the second harmonic source; θ h is the phase angle between the hth harmonic currents of the first harmonic source and the second harmonic source; When n harmonic currents of the same order are superimposed, where n is greater than 2, the harmonic currents of the first and second harmonic sources are superimposed first, and then the result is superimposed with the harmonic current of the third harmonic source, and the result is superimposed with the harmonic current of the fourth harmonic source, until the harmonic current of the nth harmonic source is superimposed.

7. A method for quantifying the impact of wind farm access on power grid harmonics according to claim 1, characterized in that: include: Combined with the pre-set harmonic standards, the harmonic impact of wind farms on the power grid during operation is quantitatively analyzed, specifically: Combined with the pre-set harmonic standards, the allowable harmonic value of the wind farm is calculated, and the calculated results of the magnitude of each harmonic current injected by the wind farm into the power grid are compared with the corresponding allowable harmonic value. If the calculated results of the magnitude of each harmonic current injected by the wind farm into the power grid are greater than the corresponding allowable harmonic value, it means that the wind farm has a large harmonic impact on the power grid. Otherwise, it means that the wind farm has a small harmonic impact on the power grid.

8. A method for quantifying the impact of wind farm access on power grid harmonics according to claim 7, characterized in that: include: Combined with the preset harmonic standard, the permissible harmonic value of the wind farm is calculated. Specifically, the minimum short-circuit capacity of the common connection point is compared with the set benchmark short-circuit capacity. If the two are the same, the permissible harmonic value of the wind farm is the set permissible harmonic value. Otherwise, the set permissible harmonic current value is corrected according to the following formula: Where: S k1 is the minimum short-circuit capacity of the common connection point, S k2 is the benchmark short-circuit capacity; I hp is the set hth harmonic current allowable value; I h The short-circuit capacity is S k1 The allowable value of the hth harmonic current when The hth harmonic current allowable value I of the i-th harmonic source at the common connection point hi Calculated as follows: Where: S i is the power consumption agreement capacity of the i-th user; S t is the capacity of the power supply equipment at the public connection point; α is the phase superposition coefficient.

9. A quantitative system for evaluating the harmonic impact of wind farm access on the power grid using the quantitative analysis method described in claims 1-8, comprising a harmonic model building module, a harmonic current calculation module of a harmonic source, a harmonic superposition calculation module and a quantitative analysis module; characterized in that: Specifically: Harmonic model building module: build a wind farm harmonic model and set corresponding harmonic emission characteristics for wind turbines; Harmonic current calculation module of harmonic source: connect each harmonic source to the wind farm harmonic model, perform harmonic power flow calculation for different operating conditions of the wind farm, and record the amplitude of each harmonic current injected by each harmonic source to the public connection point of the power grid. The harmonic source is a nonlinear element in the wind farm, and the operating conditions include wind speed, wind direction, and the operating status of the wind turbine; Harmonic superposition calculation module: Based on the set phase angle coefficient value, the harmonic current injected into the public connection point by each harmonic source is superimposed and analyzed to obtain the magnitude of each harmonic current injected into the power grid by the wind farm; Quantitative analysis module: Combined with the pre-set harmonic standards, quantitative analysis is performed on the harmonic impact on the power grid during the operation of the wind farm.

10. An electronic device comprising a memory, a processor, and a computer program stored in the memory and executable on the processor, characterized in that: When the computer program is loaded into a processor, the method for quantifying the impact of wind farm access on power grid harmonics according to any one of claims 1 to 8 is implemented.

11. A computer-readable storage medium storing a computer program, characterized in that: When the computer program is executed by a processor, the method for quantifying the impact of wind farm access on power grid harmonics according to any one of claims 1 to 8 is implemented.

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