Method, apparatus and terminal for evaluating impedance characteristics of energy storage power station

Abstract

A method, apparatus and terminal for evaluating the impedance characteristics of an energy storage power station, which method, apparatus and terminal relate to the technical field of energy storage power stations. The technical solution provided in the present application involves: firstly, on the basis of topological information of an energy storage power station requiring evaluation, determining the number of energy storage converters of the power station, and when the number of energy storage converters of the power station reaches a certain level, performing parallel equivalence on impedance characteristic data of the energy storage converters on the same low-voltage side of the same step-up transformer, then, on the basis of the topology of the energy storage power station after equivalent simplification of the energy storage converters, constructing an energy storage power station model, reducing a workload increased when the scale of the energy storage power station is excessively large, so as to use the equated energy storage power station model to calculate positive-sequence and negative-sequence grid-side impedance characteristic data and power-station-side impedance characteristic data of the energy storage power station, and finally, on the basis of the grid-side impedance characteristic data and the power-station-side impedance characteristic data, obtaining positive-sequence and negative-sequence impedance characteristic evaluation results of the energy storage power station, thereby reducing the modeling workload for the impedance characteristics of the energy storage power station.

Description

A method, device and terminal for evaluating impedance characteristics of energy storage power station

[0001] This application claims priority to the Chinese patent application filed with the China Patent Office on December 19, 2023, with application number 202311755108.7 and invention name “A method, device and terminal for evaluating impedance characteristics of energy storage power stations”, the entire contents of which are incorporated by reference into this application. Technical Field

[0002] The present application relates to the technical field of energy storage power stations, and in particular to a method, device, and terminal for evaluating impedance characteristics of energy storage power stations. Background Art

[0003] In recent years, new energy projects such as wind power and photovoltaics have been connected to the power grid on a large scale. Against this backdrop of new energy storage, the prospects for electrochemical energy storage are even brighter. At the same time, the scale of energy storage power station construction is gradually expanding.

[0004] Given the rapid development of electrochemical energy storage power stations, assessing the impedance characteristics of the systems connected to these power stations and their associated oscillation risks is crucial for the stable operation of both the power station and the power system. While there are currently no standards specifically for evaluating the impedance characteristics of energy storage power stations, relevant work can be conducted with reference to standards for evaluating wind farm impedance characteristics. These standards define the scope, points, modeling requirements, and stability assessment methods for wind farms. However, as the scale of energy storage power stations increases, the number of energy storage PCSs increases, significantly increasing the workload for modeling the impedance characteristics of the power station, impacting the efficiency of impedance evaluation.

[0005] Summary of the Invention

[0006] The present application provides a method, device and terminal for evaluating the impedance characteristics of an energy storage power station, which are used to solve the technical problem that the existing evaluation scheme for the impedance characteristics of an energy storage power station has a large workload for modeling the impedance characteristics of the energy storage power station, resulting in low evaluation efficiency.

[0007] To solve the above technical problems, the first aspect of the present application provides a method for evaluating the impedance characteristics of an energy storage power station, comprising:

[0008] Counting the number of energy storage converters in the energy storage power station according to the topology of the energy storage power station;

[0009] If the number of the energy storage converters is greater than a preset threshold, the impedance characteristic data of the energy storage converters on the same low-voltage side of the same step-up transformer are connected in parallel to obtain equal values;

[0010] Based on the energy storage power station topology after the energy storage converter is equalized, the energy storage power station model is constructed;

[0011] Based on the energy storage power station model, grid-side impedance characteristic data and power station-side impedance characteristic data of the energy storage power station are calculated, so as to obtain positive-sequence and negative-sequence impedance characteristic assessment results of the energy storage power station based on the grid-side impedance characteristic data and the power station-side impedance characteristic data in combination with a preset oscillation risk assessment logic.

[0012] Preferably, after counting the number of energy storage converters in the energy storage power station, the method further includes:

[0013] According to the number of the energy storage converters, if the number of the energy storage converters is not greater than a preset number threshold, a detailed model of the energy storage power station is constructed according to a detailed model construction method.

[0014] Preferably, based on the energy storage power station topology after the energy storage converter is equalized, before building the energy storage power station model, the following steps are further included:

[0015] The number of energy storage converters after equalization is counted. If the number of energy storage converters after equalization is not greater than a preset number threshold, an energy storage power station model is constructed based on the energy storage power station topology after the energy storage converters are equalized. If the number of energy storage converters after equalization is greater than the preset number threshold, the impedance characteristic data of energy storage units with the same structure and under the same low-voltage side of the same main transformer are connected in parallel and equalized in units of energy storage units. Each energy storage unit includes a group of step-up transformers and an energy storage converter connected to the step-up transformer.

[0016] Preferably, the calculating of the grid-side impedance characteristic data and the power station-side impedance characteristic data of the energy storage power station based on the energy storage power station model specifically includes:

[0017] Based on the energy storage power station model, combined with a preset frequency scanning interval and scanning step size, positive-sequence and negative-sequence disturbance signals of specific frequencies are applied to the grid side and the power station side of the energy storage power station at the grid connection point of the energy storage power station in turn, to obtain a grid-side response current and a power station-side response current, wherein the frequency of the disturbance signal does not exceed the range of the frequency scanning interval;

[0018] The positive-sequence and negative-sequence grid-side impedance characteristic data and the power station-side impedance characteristic data of the energy storage power station are calculated according to the grid-side response current, the power station-side response current and the disturbance signal.

[0019] Preferably, obtaining the impedance characteristic evaluation result of the energy storage power station based on the grid-side impedance characteristic data and the power station-side impedance characteristic data in combination with a preset oscillation risk evaluation logic specifically includes:

[0020] A Nyquist curve is generated according to the grid-side impedance characteristic data and the power station-side impedance characteristic data, and a positive-sequence and negative-sequence impedance characteristic assessment result of the energy storage power station is obtained according to the Nyquist curve and a preset oscillation risk assessment logic.

[0021] At the same time, the second aspect of the present application also provides an energy storage power station impedance characteristic evaluation device, including:

[0022] A converter quantity counting unit, configured to count the number of energy storage converters in the energy storage power station according to the topology of the energy storage power station;

[0023] A converter parallel equivalent unit, configured to perform parallel equivalent connection of the impedance characteristic data of the energy storage converters on the same low-voltage side of the same step-up transformer if the number of the energy storage converters is greater than a preset threshold value;

[0024] A power station model building unit, used to build an energy storage power station model based on the energy storage power station topology after the energy storage converter is equalized;

[0025] An evaluation result output unit is configured to calculate, based on the energy storage power station model, the positive-sequence and negative-sequence grid-side impedance characteristic data and the power station-side impedance characteristic data of the energy storage power station, so as to obtain, based on the grid-side impedance characteristic data and the power station-side impedance characteristic data, a positive-sequence and negative-sequence impedance characteristic evaluation result of the energy storage power station in combination with a preset oscillation risk assessment logic.

[0026] Preferably, it also includes:

[0027] The detailed model building unit is configured to build a detailed model of the energy storage power station according to the number of the energy storage converters, if the number of the energy storage converters is not greater than a preset number threshold, in accordance with a detailed model building method.

[0028] Preferably, it also includes:

[0029] An equivalent converter quantity statistics unit is used to count the number of energy storage converters after equalization. If the number of energy storage converters after equalization is not greater than a preset quantity threshold, an energy storage power station model is constructed based on the energy storage power station topology after the energy storage converters are equalized. If the number of energy storage converters after equalization is greater than the preset quantity threshold, the impedance characteristic data of energy storage units with the same structure and under the same low-voltage side of the same main transformer are connected in parallel and equalized, with each energy storage unit including a group of step-up transformers and an energy storage converter connected to the step-up transformer.

[0030] Preferably, the evaluation result output unit is specifically used to:

[0031] Based on the energy storage power station model, combined with a preset frequency scanning interval and scanning step size, positive-sequence and negative-sequence disturbance signals of specific frequencies are applied to the grid side and the power station side of the energy storage power station at the grid connection point of the energy storage power station in turn, to obtain a grid-side response current and a power station-side response current, wherein the frequency of the disturbance signal does not exceed the range of the frequency scanning interval;

[0032] Calculating positive-sequence and negative-sequence grid-side impedance characteristic data and power station-side impedance characteristic data of the energy storage power station based on the grid-side response current, the power station-side response current, and the disturbance signal;

[0033] A Nyquist curve is generated according to the grid-side impedance characteristic data and the power station-side impedance characteristic data, and a positive-sequence and negative-sequence impedance characteristic assessment result of the energy storage power station is obtained according to the Nyquist curve and a preset oscillation risk assessment logic.

[0034] A third aspect of the present application provides an energy storage power station impedance characteristic evaluation terminal, comprising: a memory and a processor;

[0035] The memory is used to store program codes corresponding to the energy storage power station impedance characteristic evaluation method provided in the first aspect of the present application;

[0036] The processor is used to execute the program code in the memory to implement the energy storage power station impedance characteristic evaluation method provided in the first aspect of the present application.

[0037] It can be seen from the above technical solutions that the embodiments of the present application have the following advantages:

[0038] The technical solution provided in this application first determines the number of energy storage converters in the energy storage power station based on the topological information of the energy storage power station to be evaluated. When the number of energy storage converters in the power station reaches a certain level, the impedance characteristic data of the energy storage converters on the same low-voltage side of the same step-up transformer are connected in parallel and equalized. Then, based on the simplified energy storage power station topology after the energy storage converter is equalized, an energy storage power station model is constructed to reduce the workload that increases when the energy storage power station is too large. The positive-sequence and negative-sequence grid-side impedance characteristic data and the power station-side impedance characteristic data of the energy storage power station can be calculated using the equalized energy storage power station model. Finally, based on the grid-side impedance characteristic data and the power station-side impedance characteristic data, the positive-sequence and negative-sequence impedance characteristic evaluation results of the energy storage power station are obtained, thereby reducing the workload of energy storage power station impedance characteristic modeling and improving the efficiency of the evaluation work. BRIEF DESCRIPTION OF THE DRAWINGS

[0039] In order to more clearly illustrate the embodiments of the present application or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative labor.

[0040] FIG1 is a flow chart of an embodiment of a method for evaluating impedance characteristics of an energy storage power station provided in the present application.

[0041] FIG2 is a flow chart of another embodiment of a method for evaluating impedance characteristics of an energy storage power station provided in the present application.

[0042] FIG3 is a schematic diagram of a topology of an energy storage power station.

[0043] FIG4 is a flow chart of a scanning process of broadband impedance characteristics of an energy storage power station in a method for evaluating impedance characteristics of an energy storage power station provided in the present application.

[0044] Figure 5 is an equivalent circuit diagram when the energy storage power station is connected to the system.

[0045] FIG6 is a Nyquist diagram of a model constructed based on a method for evaluating impedance characteristics of an energy storage power station provided in this application.

[0046] FIG7 is a waveform diagram of the amplitude and phase-frequency characteristics of a model constructed based on a method for evaluating impedance characteristics of an energy storage power station provided in this application.

[0047] FIG8 is a schematic structural diagram of an energy storage power station impedance characteristic evaluation device provided in this application.

[0048] FIG9 is a schematic structural diagram of an energy storage power station impedance characteristic evaluation terminal provided in this application. DETAILED DESCRIPTION

[0049] The embodiments of the present application provide a method, device, and terminal for evaluating the impedance characteristics of an energy storage power station, which are used to solve the technical problem that the existing energy storage power station impedance characteristics evaluation scheme has a large workload of energy storage power station impedance characteristics modeling, resulting in low evaluation efficiency.

[0050] In order to make the purpose, features, and advantages of the invention of this application more obvious and easy to understand, the technical solutions in the embodiments of this application will be clearly and completely described below in conjunction with the drawings in the embodiments of this application. Obviously, the embodiments described below are only part of the embodiments of this application, not all of the embodiments. Based on the embodiments in this application, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of this application.

[0051] First, a detailed description of an embodiment of a method for evaluating impedance characteristics of an energy storage power station provided by this application is as follows:

[0052] Referring to FIG. 1 , this embodiment provides a method for evaluating impedance characteristics of an energy storage power station, including:

[0053] Step 101: Count the number of energy storage converters in the energy storage power station according to the topology of the energy storage power station.

[0054] Step 102: If the number of energy storage converters is greater than a preset threshold, the impedance characteristic data of the energy storage converters on the same low-voltage side of the same step-up transformer are connected in parallel to be equal.

[0055] It should be noted that according to the actual electrical structure of the energy storage power station, the number of energy storage converters is obtained, and whether the model needs to be calculated using equivalent values ​​is determined based on the number of energy storage converters. If the number of energy storage converters is greater than the preset number threshold, the impedance characteristic data of the energy storage converters on the same low-voltage side of the same step-up transformer are connected in parallel for equivalent values.

[0056] According to the topology after equalization, an energy storage power station model including transformers, cable lines, energy storage converters, reactive compensation devices and other components is established. The energy storage converters and reactive compensation devices are equalized to variable impedance models, and the reactive compensation device model can be defaulted to an impedance model Z that changes with frequency f. svg (f) This embodiment mainly processes the impedance characteristic data of the energy storage converter, and processes the initial value Z of the impedance characteristic data of the energy storage converter. pcs0 (f) Perform equivalent calculation. If n energy storage converters are connected in parallel, the impedance after equivalent calculation is Z pcs (f) = Z pcs0 (f) / n, where the initial value of the impedance characteristic of the energy storage converter is Z pcs0 (f) Impedance characteristics Z of reactive power compensation device svg (f) can be obtained through various means such as hardware-in-the-loop simulation or scanning based on a verified digital model, including positive-sequence and negative-sequence impedance characteristic data.

[0057] Step 103: construct an energy storage power station model based on the energy storage power station topology after the energy storage converter is equalized.

[0058] Step 104: Based on the energy storage power station model, the positive-sequence and negative-sequence grid-side impedance characteristic data and the power station-side impedance characteristic data of the energy storage power station are calculated, so as to obtain the positive-sequence and negative-sequence impedance characteristic assessment results of the energy storage power station based on the grid-side impedance characteristic data and the power station-side impedance characteristic data in combination with the preset oscillation risk assessment logic.

[0059] It should be noted that steps 103 and 104 of this embodiment are steps for constructing an energy storage power station model and evaluating impedance characteristics. This step constructs an energy storage power station model based on the simplified energy storage power station topology after equivalent energy storage converters, thereby reducing the workload that increases when the energy storage power station is too large. The equivalent energy storage power station model is then used to calculate the grid-side impedance characteristic data and the power station-side impedance characteristic data of the energy storage power station's positive and negative sequences. Finally, based on the grid-side impedance characteristic data and the power station-side impedance characteristic data, an evaluation result of the positive and negative sequence impedance characteristics of the energy storage power station is obtained, thereby reducing the workload of modeling the impedance characteristics of the energy storage power station and improving the efficiency of the evaluation work.

[0060] Based on the above embodiments, this embodiment provides a method for evaluating impedance characteristics of an energy storage power station for further explanation.

[0061] Please refer to FIG2 . Further, after counting the number of energy storage converters in the energy storage power station in step 101 , the following steps are further included:

[0062] Step 1001: Based on the number of energy storage converters, if the number of energy storage converters is not greater than a preset threshold, a detailed model of the energy storage power station is constructed according to a detailed model construction method.

[0063] It should be noted that if the number of energy storage converters in the statistical energy storage power station is not greater than the preset number threshold, which is preferably 40 to 80 and generally defaults to 60, a detailed energy storage power station model including components such as transformers, cable lines, energy storage converters, and reactive compensation devices is established according to the actual topology of the energy storage power station, wherein the energy storage converter is equivalent to an impedance model Z that changes with frequency f. pcs (f) The reactive compensation device model is equivalent to the impedance model Z that changes with frequency f. svg (f).

[0064] In some embodiments, based on the energy storage power station topology after the energy storage converter is equalized, before building the energy storage power station model, the following steps are further included:

[0065] Step 1002: Count the number of energy storage converters after equalization. If the number of energy storage converters after equalization is not greater than the preset number threshold, jump to step 103; if the number of energy storage converters after equalization is greater than the preset number threshold, first execute step 1003 and then jump to step 103.

[0066] Step 1003: Taking energy storage units as units, the impedance characteristic data of energy storage units with the same structure and the same low-voltage side of the same main transformer are connected in parallel to be equal. Each energy storage unit includes a set of step-up transformers and an energy storage converter connected to the step-up transformer.

[0067] It should be noted that if the number of energy storage converters after equalization is not greater than the preset number threshold, an energy storage power station model including components such as transformers, cable lines, energy storage converters, and reactive compensation devices is established according to the topology after equalization, wherein the energy storage converter and reactive compensation device are equalized as variable impedance models, and the specific impedance change characteristics are obtained by converting the energy storage converter impedance characteristic data Z obtained by the energy storage converter impedance characteristic data after equalization calculation. pcs0 (f) Perform equivalent calculation. If n energy storage converters are connected in parallel, the impedance after equivalent calculation is Z pcs (f) = Z pcs0 (f) / n.

[0068] If the number of energy storage converters after equalization is greater than the preset number threshold, the impedance characteristic data of the energy storage units with the same structure and the same low-voltage side of the same main transformer are connected in parallel and equalized, with the energy storage unit as the unit. The composition of the energy storage unit is shown in Figure 3. The equalization method can refer to the following example: First, the initial value Z of the impedance characteristic data of a single energy storage unit is obtained by scanning or in-loop simulation. unit0 (f) Taking the energy storage unit as the unit, the impedance characteristic data of the energy storage units connected on the same low-voltage side of the transformer are connected in parallel and equalized. If m energy storage units are connected in parallel, the impedance after equalization is Z unit (f) = Z unit0 (f) / m; Similarly, the energy storage unit is equivalent to an impedance model Z whose size changes with frequency f unit (f) The reactive compensation device model is equivalent to the impedance model Z whose size changes with frequency f. svg (f) According to the equalized topology, an energy storage power station model including transformers, cable lines, energy storage units and other components is established.

[0069] In some embodiments, calculating the grid-side impedance characteristic data and the power station-side impedance characteristic data of the energy storage power station based on the energy storage power station model in step 104 specifically includes:

[0070] Step 1041: Based on the energy storage power station model, combined with the preset frequency scanning interval and scanning step size, positive-sequence and negative-sequence disturbance signals of specific frequencies are applied to the grid side and the power station side of the energy storage power station at the grid connection point of the energy storage power station in turn to obtain the grid-side response current and the power station-side response current.

[0071] The frequency of the disturbance signal does not exceed the range of the frequency scanning interval;

[0072] Step 1042: Calculate the positive-sequence and negative-sequence grid-side impedance characteristic data and the power station-side impedance characteristic data of the energy storage power station based on the grid-side response current, the power station-side response current, and the disturbance signal.

[0073] It should be noted that, as shown in FIG4 , the frequency scanning range f0 to f n , scanning step d, starting from f = f0 to f = f n , the positive-sequence and negative-sequence disturbance signals △U(f) of frequency f are added to the grid side and the energy storage station side at the grid connection point of the energy storage station, respectively, to obtain the corresponding current responses △I1(f) and △I2(f);

[0074] Calculate the grid-side impedance Z1(f) = △U(f) / △I1(f) and the energy storage impedance Z2(f) = △U(f) / △I2(f).

[0075] In some embodiments, the steps of obtaining the positive-sequence and negative-sequence impedance characteristic assessment results of the energy storage power station in step 104 based on the grid-side impedance characteristic data and the power station-side impedance characteristic data, combined with a preset oscillation risk assessment logic, specifically include:

[0076] Step 1043: Generate a Nyquist curve based on the grid-side impedance characteristic data and the power station-side impedance characteristic data, and obtain the positive-sequence and negative-sequence impedance characteristic assessment results of the energy storage power station based on the Nyquist curve and the preset oscillation risk assessment logic.

[0077] It should be noted that the equivalent circuit diagram of the energy storage power station access system is shown in FIG5 . The impedance characteristic scan results Z1(f) and Z2(f) on both sides of the energy storage power station grid connection point obtained in step 1042 are imported into the oscillation risk assessment program to assess the oscillation risk of the energy storage power station.

[0078] The expression of the grid-connected current of the energy storage power station is as follows:

[0079] Perform numerical calculations on Z1(f) / Z2(f), convert the amplitude and phase into real and imaginary parts, and draw the corresponding Nyquist curve in polar coordinates. The resulting Nyquist curve is shown in Figure 6. As shown in Figure 6, when the Nyquist curve (line segment) of Z1(f) / Z2(f) passes through (-1,0), 1+Z1(f) / Z2(f) in formula (1) is 0. At this time, I pcc (f) is maximum. Further accounting for factors such as simulation calculation errors requires a comprehensive consideration of both the amplitude and phase margins. This stability margin circle is defined as a circle centered at (-1, j0) with a radius of Rmin. When the Nyquist curve (line segment) of Z1(f) / Z2(f) falls within this stability margin circle, the phase or amplitude margin is considered insufficient, indicating a risk of oscillation.

[0080] More specifically, the real part Re and imaginary part Im data corresponding to the point of the line segment within the stability margin circle are read and converted into amplitude |Z| and phase θ. Combined with the amplitude-frequency characteristic and phase-frequency characteristic curves of Z1(f) / Z2(f), the frequency band with risk can be determined. The conversion formula of amplitude |Z| and phase θ is as follows:

[0081] As shown in FIG7 , when the intersection of the Z1(f) / Z2(f) curve and the unit circle falls outside the margin circle, it is considered that there is no oscillation risk in this embodiment, as shown by the dotted line (Z 12 / Z2) working condition; otherwise, it means there is an oscillation risk, as shown by the dotted line (Z 11 / Z2) working condition, the oscillation risk frequency band needs to be further evaluated.

[0082] Furthermore, based on the assessment of oscillation risk in step 1042, it is necessary to accurately locate the risk frequency. A pipeline algorithm is used to traverse the data set where the Z1 / Z2 Nyquist curve (line segment) enters the threshold range (small circle). The data set contains the real and imaginary parts of the point. By calculating the amplitude and phase angle corresponding to each data point, the frequency points with corresponding amplitude and phase are retrieved from the amplitude-frequency and phase-frequency characteristic data of Z1(f) / Z2(f), thereby obtaining the frequency band with oscillation risk.

[0083] The evaluation method provided in this embodiment is applicable to energy storage power stations of varying sizes, and the equivalence and modeling methods can be selected based on the size of the power station. Prioritizing accuracy, when the power station is small, the number of energy storage converters is small, and detailed modeling is performed according to the actual topology. When the power station is slightly larger, modeling is performed by connecting energy storage converters in parallel. When the power station is large, a segmented scanning method and parallel equivalence of energy storage units are used to significantly reduce the modeling workload for large-scale energy storage power stations.

[0084] The above is a detailed description of a specific embodiment of a method for evaluating impedance characteristics of an energy storage power station provided by the present application. The following is a detailed description of an embodiment of a device for evaluating impedance characteristics of an energy storage power station provided by the present application.

[0085] Referring to FIG8 , this embodiment further provides an energy storage power station impedance characteristic evaluation device, including:

[0086] The converter quantity counting unit 201 is configured to count the number of energy storage converters in the energy storage power station according to the topology of the energy storage power station;

[0087] The converter parallel equivalent unit 202 is used to perform parallel equivalent on the impedance characteristic data of the energy storage converters on the same low-voltage side of the same step-up transformer if the number of the energy storage converters is greater than a preset number threshold;

[0088] The power station model construction unit 203 is used to construct an energy storage power station model based on the energy storage power station topology after the energy storage converter is equalized;

[0089] The evaluation result output unit 204 is used to calculate the positive-sequence and negative-sequence grid-side impedance characteristic data and the power station-side impedance characteristic data of the energy storage power station based on the energy storage power station model, so as to obtain the positive-sequence and negative-sequence impedance characteristic evaluation results of the energy storage power station based on the grid-side impedance characteristic data and the power station-side impedance characteristic data in combination with the preset oscillation risk assessment logic.

[0090] Furthermore, it also includes:

[0091] The detailed model building unit 2001 is configured to build a detailed model of the energy storage power station according to the number of energy storage converters, if the number of energy storage converters is not greater than a preset threshold, in accordance with a detailed model building method.

[0092] Furthermore, it also includes:

[0093] The equivalent converter quantity statistics unit 2002 is used to count the number of energy storage converters after equalization. If the number of energy storage converters after equalization is not greater than a preset quantity threshold, an energy storage power station model is constructed based on the energy storage power station topology after the energy storage converters are equalized. If the number of energy storage converters after equalization is greater than the preset quantity threshold, the impedance characteristic data of energy storage units with the same structure and under the same low-voltage side of the same main transformer are connected in parallel and equalized, with each energy storage unit including a group of step-up transformers and energy storage converters connected to the step-up transformer.

[0094] Furthermore, the evaluation result output unit 204 is specifically configured to include:

[0095] Based on the energy storage power station model, combined with the preset frequency scanning interval and scanning step size, positive-sequence and negative-sequence disturbance signals of specific frequencies are applied to the grid side and power station side of the energy storage power station at the grid connection point of the energy storage power station in turn. The grid-side response current and the power station-side response current are obtained. The frequency of the disturbance signal does not exceed the range of the frequency scanning interval.

[0096] According to the grid-side response current, the power station-side response current and the disturbance signal, the positive-sequence and negative-sequence grid-side impedance characteristic data and the power station-side impedance characteristic data of the energy storage power station are calculated.

[0097] Based on the grid-side impedance characteristic data and the power station-side impedance characteristic data, a Nyquist curve is generated. Based on the Nyquist curve and the preset oscillation risk assessment logic, the positive-sequence and negative-sequence impedance characteristic assessment results of the energy storage power station are obtained.

[0098] In addition, the present application also provides an embodiment of an energy storage power station impedance characteristic evaluation terminal as follows:

[0099] As shown in FIG9 , the present application provides a terminal for evaluating impedance characteristics of an energy storage power station. The terminal types include, but are not limited to, personal computers, industrial computers, servers, and / or embedded intelligent terminals. The terminal of this embodiment includes a memory 33 and a processor 31 , wherein the memory 33 and the processor 31 may be connected via a bus 34 .

[0100] The memory is used to store program codes corresponding to the energy storage power station impedance characteristic evaluation method provided in the above embodiment;

[0101] The processor is used to execute the program code in the memory to implement the energy storage power station impedance characteristic evaluation method provided in the above embodiment.

[0102] Those skilled in the art will clearly understand that, for the convenience and brevity of description, the specific working processes of the above-described devices and units can refer to the corresponding processes in the aforementioned method embodiments and will not be repeated here.

[0103] In the several embodiments provided in this application, it should be understood that the disclosed devices and methods can be implemented in other ways. For example, the device embodiments described above are merely schematic. For example, the division of the units is merely a logical function division. In actual implementation, there may be other division methods, such as multiple units or components can be combined or integrated into another system, or some features can be ignored or not executed. Another point is that the mutual coupling or direct coupling or communication connection shown or discussed can be through some interfaces, indirect coupling or communication connection of devices or units, which can be electrical, mechanical or other forms.

[0104] The terms "first", "second", "third", "fourth", etc. (if any) in the specification of the present application and the above-mentioned drawings are used to distinguish similar objects and are not necessarily used to describe a specific order or sequential order. It should be understood that the numbers used in this way can be interchanged where appropriate, so that the embodiments of the present application described herein can, for example, be implemented in an order other than those illustrated or described herein. In addition, the terms "including" and "having" and any variations thereof are intended to cover non-exclusive inclusions, for example, a process, method, system, product or device that includes a series of steps or units is not necessarily limited to those steps or units clearly listed, but may include other steps or units that are not clearly listed or inherent to these processes, methods, products or devices.

[0105] It should be understood that in this application, "at least one (item)" means one or more, and "plurality" means two or more. "And / or" is used to describe the association relationship of associated objects, indicating that three relationships may exist. For example, "A and / or B" can mean: only A exists, only B exists, and A and B exist at the same time, where A and B can be singular or plural. The character " / " generally indicates that the previous and next associated objects are in an "or" relationship. "At least one of the following items" or similar expressions refers to any combination of these items, including any combination of single items or plural items. For example, at least one of a, b or c can mean: a, b, c, "a and b", "a and c", "b and c", or "a and b and c", where a, b, c can be single or multiple.

[0106] The units described as separate components may or may not be physically separate, and the components shown as units may or may not be physical units, that is, they may be located in one place or distributed across multiple network units. Some or all of these units may be selected to achieve the purpose of this embodiment according to actual needs.

[0107] In addition, the functional units in the various embodiments of the present invention may be integrated into a single processing unit, each unit may exist physically separately, or two or more units may be integrated into a single unit. The aforementioned integrated units may be implemented in the form of hardware or software functional units.

[0108] If the integrated unit is implemented in the form of a software functional unit and sold or used as an independent product, it can be stored in a computer-readable storage medium. Based on this understanding, the technical solution of the present invention, or the part that contributes to the prior art, or all or part of the technical solution can be embodied in the form of a software product. The computer software product is stored in a storage medium and includes several instructions for enabling a computer device (which can be a personal computer, server, or network device, etc.) to execute all or part of the steps of the method described in each embodiment of the present invention. The aforementioned storage medium includes: various media that can store program codes, such as a USB flash drive, a mobile hard disk, a read-only memory (ROM), a random access memory (RAM), a magnetic disk or an optical disk.

[0109] As described above, the above embodiments are only used to illustrate the technical solutions of the present application, rather than to limit them. Although the present application has been described in detail with reference to the above embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the above embodiments, or make equivalent replacements for some of the technical features therein. However, these modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the embodiments of the present application.

Claims

1. A method for evaluating impedance characteristics of an energy storage power station, characterized in that: include: According to the topological structure of the energy storage power station, counting the number of energy storage converters in the energy storage power station; If the number of the energy storage converters is greater than a preset number threshold, the impedance characteristic data of the energy storage converters under the same low-voltage side of the same step-up transformer are connected in parallel to be equal; Based on the energy storage power station topology after the energy storage converter is equalized, the energy storage power station model is constructed; Based on the energy storage power station model, the positive-sequence and negative-sequence grid-side impedance characteristic data and the power station-side impedance characteristic data of the energy storage power station are calculated, so as to obtain the positive-sequence and negative-sequence impedance characteristic evaluation results of the energy storage power station according to the grid-side impedance characteristic data and the power station-side impedance characteristic data in combination with a preset oscillation risk evaluation logic.

2. A method for evaluating impedance characteristics of an energy storage power station according to claim 1, characterized in that: After counting the number of energy storage converters in the energy storage power station, the method further includes: According to the number of the energy storage converters, if the number of the energy storage converters is not greater than a preset number threshold, a detailed model of the energy storage power station is constructed in accordance with a detailed model construction method.

3. The method for evaluating impedance characteristics of an energy storage power station according to claim 1, characterized in that: Based on the energy storage power station topology after the energy storage converter is equivalent, the energy storage power station model is also constructed before: The number of energy storage converters after being equalized is counted. If the number of energy storage converters after being equalized is not greater than a preset number threshold, an energy storage power station model is constructed based on the energy storage power station topology after the energy storage converters are equalized. If the number of energy storage converters after being equalized is greater than the preset number threshold, the impedance characteristic data of energy storage units with the same structure and under the same low-voltage side of the same main transformer are connected in parallel and equalized in units of energy storage units. Each energy storage unit includes a group of step-up transformers and an energy storage converter connected to the step-up transformer.

4. The method for evaluating impedance characteristics of an energy storage power station according to claim 1, characterized in that: The calculating of the grid-side impedance characteristic data and the power station-side impedance characteristic data of the energy storage power station based on the energy storage power station model specifically includes: Based on the energy storage power station model, combined with the preset frequency scanning interval and scanning step length, positive-sequence and negative-sequence disturbance signals of specific frequencies are applied to the grid side and the power station side of the energy storage power station at the grid connection point of the energy storage power station in turn, to obtain the grid side response current and the power station side response current, The frequency of the disturbance signal does not exceed the range of the frequency scanning interval; The positive-sequence and negative-sequence grid-side impedance characteristic data and the power station-side impedance characteristic data of the energy storage power station are calculated according to the grid-side response current, the power station-side response current and the disturbance signal.

5. A method for evaluating impedance characteristics of an energy storage power station according to claim 4, characterized in that: The impedance characteristic evaluation result of the energy storage power station obtained according to the grid-side impedance characteristic data and the power station-side impedance characteristic data, combined with a preset oscillation risk evaluation logic, specifically includes: A Nyquist curve is generated according to the grid-side impedance characteristic data and the power station-side impedance characteristic data, and a positive-sequence and negative-sequence impedance characteristic evaluation result of the energy storage power station is obtained according to the Nyquist curve and a preset oscillation risk evaluation logic.

6. An impedance characteristic evaluation device for an energy storage power station, characterized in that: include: A converter quantity counting unit, used for counting the number of energy storage converters in the energy storage power station according to the topological structure of the energy storage power station; A converter parallel equivalent unit, used for parallel equivalent connection of impedance characteristic data of the energy storage converters on the same low-voltage side of the same step-up transformer if the number of the energy storage converters is greater than a preset number threshold; A power station model building unit, used to build an energy storage power station model based on the energy storage power station topology after the energy storage converter is equalized; An evaluation result output unit is used to calculate the positive-sequence and negative-sequence grid-side impedance characteristic data and the power station-side impedance characteristic data of the energy storage power station based on the energy storage power station model, so as to obtain the positive-sequence and negative-sequence impedance characteristic evaluation results of the energy storage power station according to the grid-side impedance characteristic data and the power station-side impedance characteristic data in combination with a preset oscillation risk evaluation logic.

7. The impedance characteristic evaluation device of an energy storage power station according to claim 6, characterized in that: Also includes: The detailed model building unit is used to build a detailed model of the energy storage power station according to the number of the energy storage converters, if the number of the energy storage converters is not greater than a preset number threshold, according to the detailed model building method.

8. The impedance characteristic evaluation device of an energy storage power station according to claim 6, characterized in that: Also includes: The equivalent converter quantity statistical unit is used to count the number of energy storage converters after being equivalent. If the number of energy storage converters after being equivalent is not greater than a preset quantity threshold, an energy storage power station model is constructed based on the energy storage power station topology after the energy storage converters are equivalent. If the number of energy storage converters after being equivalent is greater than the preset quantity threshold, the impedance characteristic data of energy storage units with the same structure and under the same low-voltage side of the same main transformer are connected in parallel and equivalently, with each energy storage unit comprising a group of step-up transformers and an energy storage converter connected to the step-up transformer.

9. The impedance characteristic evaluation device of an energy storage power station according to claim 6, characterized in that: The evaluation result output unit is specifically used for: Based on the energy storage power station model, combined with the preset frequency scanning interval and scanning step length, positive-sequence and negative-sequence disturbance signals of specific frequencies are applied to the grid side and the power station side of the energy storage power station at the grid connection point of the energy storage power station in turn, to obtain the grid side response current and the power station side response current, and the frequency of the disturbance signal does not exceed the range of the frequency scanning interval; Calculating the positive-sequence and negative-sequence grid-side impedance characteristic data and the power station-side impedance characteristic data of the energy storage power station according to the grid-side response current, the power station-side response current and the disturbance signal; A Nyquist curve is generated according to the grid-side impedance characteristic data and the power station-side impedance characteristic data, and a positive-sequence and negative-sequence impedance characteristic evaluation result of the energy storage power station is obtained according to the Nyquist curve and a preset oscillation risk evaluation logic.

10. An energy storage power station impedance characteristic evaluation terminal, characterized in that: include: Memory and processor; The memory is used to store a program code corresponding to the energy storage power station impedance characteristic evaluation method according to any one of claims 1 to 5; The processor is used to execute the program code in the memory to implement the impedance characteristic evaluation method of the energy storage power station according to any one of claims 1 to 5.

Images