A method and device for constructing a small interference stability parameter safety region of a hybrid station

Abstract

The present invention discloses a method and device for constructing a small-disturbance stability parameter safety domain for a hybrid station. The method includes: constructing an equivalent circuit diagram of the hybrid station based on the equivalent circuit of the sequence admittance model of N grid-following control power generation units and the equivalent circuit of the sequence impedance model of M grid-forming control power generation units; calculating the grid-connected current expression of the hybrid station based on the equivalent circuit diagram of the hybrid station; extracting the rate matrix of each grid-connected current component relative to the power grid in the grid-connected current expression; estimating the root locus distribution of the rate matrix, and based on preset stability judgment conditions, determining the safety domain of the first control parameter, the second control parameter, and the capacity ratio when each rate matrix meets the stability condition. The present invention can quickly and accurately determine the small-disturbance stability of a hybrid station.

Description

Technical Field

[0001] The present invention relates to the field of power system stability analysis, and in particular to a method and device for constructing a small-disturbance stability parameter safety domain of a hybrid station. Background Art

[0002] Existing renewable energy stations typically switch some grid-following control power generation units to grid-forming control power generation units, forming hybrid stations. This improves the station's stability in the event of a weak grid. However, the stability of such hybrid stations is closely related to both the control parameters of each power generation unit within the station and the capacity ratio of the grid-following / grid-forming control power generation units within the hybrid station. If these two parameters are not set appropriately, the risk of small-disturbance instability still exists.

[0003] The construction of the small disturbance parameter safety domain is based on the small disturbance stability evaluation results of the system under different parameter combinations. Therefore, an accurate and fast stability evaluation method is the core issue of constructing the small disturbance stability parameter safety domain. Utility Model Content

[0004] The present invention provides a method and device for constructing a small-disturbance stability parameter safety domain of a hybrid station, so as to quickly and accurately judge the small-disturbance stability of the hybrid station.

[0005] A first aspect of the present invention provides a method for constructing a small interference stability parameter safety region of a hybrid station, comprising:

[0006] Based on the equivalent circuit of the sequence admittance model of N grid-following control power generation units and the equivalent circuit of the sequence impedance model of M grid-forming control power generation units, an equivalent circuit diagram of the hybrid station is constructed; the sequence admittance model includes the first control parameter of the grid-following control power generation unit; the sequence impedance model

[0007] The second control parameter of the grid-type control power generation unit is included;

[0008] Calculating a grid-connected current expression of the hybrid station based on an equivalent circuit diagram of the hybrid station;

[0009] Extracting the return rate matrix of each grid-connected current component relative to the grid in the grid-connected current expression;

[0010] The root locus distribution of the rate of return matrix is ​​estimated, and based on a preset stability judgment condition, a safety domain of the first control parameter, the second control parameter, and the capacity ratio is determined when each rate of return matrix satisfies a stability condition; the capacity ratio is the ratio of the number of the grid-following type control power generation units to the power generation units of the hybrid station, or the ratio of the number of the grid-forming type control power generation units to the power generation units of the hybrid station.

[0011] Optionally, before constructing an equivalent circuit diagram of a hybrid station based on an equivalent circuit of a sequence admittance model of N grid-following controlled power generation units and an equivalent circuit of a sequence impedance model of M grid-forming controlled power generation units, the method further includes:

[0012] Establish the sequence admittance model of the grid-following control power generation unit and the sequence impedance model of the grid-forming control power generation unit;

[0013] An equivalent circuit of the sequence admittance model of the grid-following type controlled power generation unit and an equivalent circuit of the sequence impedance model of the grid-building type controlled power generation unit are respectively established.

[0014] Optionally, establishing a sequence admittance model of a grid-following type controlled power generation unit and a sequence impedance model of a grid-building type controlled power generation unit includes:

[0015] Injecting a positive-sequence disturbance voltage or a negative-sequence disturbance voltage into a grid-connected node of the grid-following controlled power generation unit to obtain a corresponding phase-sequence current; calculating at least two admittance values ​​based on the positive-sequence disturbance voltage, the phase-sequence current in response to the positive-sequence disturbance voltage, the negative-sequence disturbance voltage, and the phase-sequence current in response to the negative-sequence disturbance voltage, and forming a sequence admittance matrix model of the grid-following controlled power generation unit with the at least two admittance values;

[0016] A positive-sequence disturbance voltage or a negative-sequence disturbance voltage is injected into the grid-connected node of the grid-type controlled power generation unit to obtain a corresponding phase-sequence current; based on the positive-sequence disturbance voltage, the phase-sequence current in response to the positive-sequence disturbance voltage, the negative-sequence disturbance voltage, and the phase-sequence current in response to the negative-sequence disturbance voltage, at least two impedance values ​​are calculated, and a sequence impedance matrix model of the grid-type controlled power generation unit is formed by the at least two impedance values.

[0017] Optionally, the step of injecting a positive-sequence disturbance voltage or a negative-sequence disturbance voltage into the grid-connected node of the grid-following controlled power generation unit to obtain a corresponding phase-sequence current; calculating at least two admittance values ​​based on the positive-sequence disturbance voltage, the phase-sequence current in response to the positive-sequence disturbance voltage, the negative-sequence disturbance voltage, and the phase-sequence current in response to the negative-sequence disturbance voltage, and forming a sequence admittance matrix model of the grid-following controlled power generation unit with the at least two admittance values, including:

[0018] The positive / negative sequence disturbance voltage is injected into the grid-connected node of the grid-following controlled power generation unit, and the grid-connected voltage of phase A of the grid-following controlled power generation unit is obtained as follows:

[0019]

[0020] In the formula, the frequency is Positive / negative sequence small signal voltage The amplitude and initial phase of and ; and The amplitude and frequency of the fundamental voltage;

[0021] Convert the above formula into frequency domain expression:

[0022]

[0023] Where, , ;

[0024] The frequency domain expression of the grid-following control power generation unit phase A is derived as follows:

[0025]

[0026] Where, and Represent the fundamental frequency current component and positive / negative sequence current component respectively; represents the positive sequence coupled current component; Indicates the rated angular frequency of the power grid;

[0027] Then the positive sequence admittance and positive sequence coupling admittance for:

[0028]

[0029]

[0030] Negative sequence admittance and negative sequence coupling admittance The formulas for positive sequence admittance and positive sequence coupling admittance are the same; the output sequence admittance matrix model of the grid-following control power generation unit can be obtained as follows:

[0031]

[0032] The calculation formulas of the negative-sequence admittance, the negative-sequence coupled admittance, the positive-sequence admittance, and the positive-sequence coupled admittance all include the first control parameter.

[0033] Optionally, the step of injecting a positive-sequence disturbance voltage or a negative-sequence disturbance voltage into the grid-connected node of the grid-controlled power generation unit to obtain a corresponding phase-sequence current; and calculating at least two impedance values ​​based on the positive-sequence disturbance voltage, the phase-sequence current in response to the positive-sequence disturbance voltage, the negative-sequence disturbance voltage, and the phase-sequence current in response to the negative-sequence disturbance voltage. The sequence impedance matrix model of the grid-controlled power generation unit is formed by the at least two impedance values, including:

[0034] The positive sequence / negative sequence disturbance voltage is injected into the grid-connected node of the grid-controlled power generation unit to obtain the grid-connected voltage of phase A of the grid-controlled power generation unit:

[0035]

[0036] In the formula, the frequency is Positive / negative sequence small signal voltage The amplitude and initial phase of and ; and The amplitude and frequency of the fundamental voltage;

[0037] Convert the above formula into frequency domain expression:

[0038]

[0039] Where, , ;

[0040] The frequency domain expression of the grid-type controlled power generation unit phase A is derived as follows:

[0041]

[0042] Where, and Represent the fundamental frequency current component and positive / negative sequence current component respectively; represents the positive sequence coupled current component; Indicates the rated angular frequency of the power grid;

[0043] Then the positive sequence impedance and positive sequence coupling impedance for:

[0044]

[0045]

[0046] Negative sequence admittance and negative sequence coupling admittance The formulas for positive sequence admittance and positive sequence coupling admittance are the same; the output sequence admittance matrix model of the grid-following control power generation unit can be obtained as follows:

[0047]

[0048] The calculation formulas of the negative-sequence impedance, the negative-sequence coupling impedance, the positive-sequence impedance, and the positive-sequence coupling impedance all include the second control parameter.

[0049] Optionally, constructing an equivalent circuit diagram of a hybrid station based on an equivalent circuit of a sequence admittance model of the N grid-following controlled power generation units and an equivalent circuit of a sequence impedance model of the M grid-forming controlled power generation units includes:

[0050] The equivalent circuit diagram of the hybrid station includes: a grid-following circuit group formed by connecting the equivalent circuits of at least two grid-following control power generation units in parallel, and a grid-forming circuit group formed by the equivalent circuits of at least two grid-forming control power generation units;

[0051] The first end of the grid-following circuit group and the first end of the grid-forming circuit group are both electrically connected to the first end of the grid impedance, the second end of the grid impedance is connected to the first end of the grid power supply, and the second end of the grid power supply is grounded;

[0052] The second end of the network following circuit group and the second end of the network forming circuit group are both grounded.

[0053] Optionally, the calculating of the grid-connected current expression of the hybrid station based on the equivalent circuit diagram of the hybrid station includes:

[0054] For the grid-connected output current of the i-th grid-following control generating unit for:

[0055]

[0056] Where N is the number of grid-following control power generation units, , ; M is the number of grid-type control power generation units, ; 、 、 as well as Represents the grid power supply , its own equivalent current source , other grid-following controlled power generation units And the equivalent current source of the grid-type control power generation unit Grid-connected output current The contribution coefficients are as follows:

[0057]

[0058]

[0059]

[0060]

[0061] Where, is the equivalent admittance value of the i-th grid-following control generating unit; is the equivalent admittance of the power grid; , ; represents the equivalent output voltage and equivalent impedance of the j-th grid-type controlled power generation unit;

[0062] If the parameters of the control type power generation units in the hybrid station are the same, then:

[0063]

[0064] Then the grid-connected output current of the i-th grid-following control generating unit is Simplified to:

[0065]

[0066] Where, Indicates that the grid power supply is Contributing current components; Indicates the grid-following type control power generation unit pair Contributing current components; Represents the grid-type control power generation unit pair Contributing current components;

[0067] Similarly, the grid-connected output current of the i-th grid-controlled power generation unit Simplified to:

[0068]

[0069] Where, Indicates that the grid power supply is Contributing current components; Indicates the grid-following type control power generation unit pair Contributing current components; Represents the grid-type control power generation unit pair Contributing current components;

[0070] The grid current of the hybrid station is for:

[0071]

[0072] The grid-connected current expression is:

[0073]

[0074] Optionally, extracting a rate matrix of the grid-connected current expression relative to the grid includes:

[0075] Convert each component in the grid-connected current expression into the form of unit negative feedback transfer function*power factor:

[0076]

[0077] Where: Indicates current The j-th component of ; Indicates the power factor of this current; Represents the unit negative feedback open-loop transfer function, also defined as the rate matrix.

[0078] Optionally, estimating the root locus distribution of the rate of return matrix and determining, based on a preset stability judgment condition, a safety region of the first control parameter, the second control parameter, and the capacity ratio when each rate of return matrix satisfies a stability condition includes:

[0079] The eigenvalue estimation method based on the Gale disk theorem is used to estimate the return matrix , the i-th eigenvalue of the return matrix Circular domains distributed on the complex plane Inside:

[0080]

[0081] in, for:

[0082]

[0083] Where C represents a complex set; The radius of the circle representing the i-th eigenvalue; Represents the parameter of the i-th row and j-th column of the return rate matrix;

[0084] Estimate the root locus distribution of each of the rate matrices based on the above formula;

[0085] Comparing the root locus distribution with a preset forbidden space, if the root locus distribution does not enter the forbidden space, it indicates that the rate matrix meets the stability condition;

[0086] Calculate the feasible region of the first control parameter, the second control parameter, and the capacity ratio when the rate matrices of all the grid-connected current components meet the stability condition.

[0087] According to another aspect of the present invention, a small disturbance stability analysis device for a hybrid station is provided, comprising:

[0088] a model construction unit, configured to construct an equivalent circuit diagram of the hybrid station based on an equivalent circuit of a sequence admittance model of N grid-following controlled power generation units and an equivalent circuit of a sequence impedance model of M grid-forming controlled power generation units; the sequence admittance model includes a first control parameter of the grid-following controlled power generation unit; and the sequence impedance model includes a second control parameter of the grid-forming controlled power generation unit;

[0089] A calculation unit, configured to calculate a grid-connected current expression of the hybrid station based on an equivalent circuit diagram of the hybrid station;

[0090] An extraction unit, configured to extract a return matrix of each grid-connected current component relative to the grid in the grid-connected current expression;

[0091] A safety domain construction unit is used to estimate the root locus distribution of the rate of return matrix and determine, based on a preset stability judgment condition, a safety domain of the first control parameter, the second control parameter, and the capacity ratio when each rate of return matrix satisfies a stability condition; the capacity ratio is the ratio of the number of the grid-following type control power generation units to the power generation units of the hybrid station, or the ratio of the number of the grid-forming type control power generation units to the power generation units of the hybrid station.

[0092] The embodiment of the present invention constructs an equivalent circuit diagram of a hybrid station based on an equivalent circuit of a sequence admittance model of N grid-following control power generation units and an equivalent circuit of a sequence impedance model of M grid-forming control power generation units; calculates the grid-connected current expression of the hybrid station based on the equivalent circuit diagram of the hybrid station, thereby correlating each grid-connected current component in the grid-connected current expression with a capacity ratio parameter and the grid-following control power generation unit and the grid-forming control power generation unit; extracts the rate matrix of each grid-connected current component in the grid-connected current expression relative to the power grid; estimates the root locus distribution of the rate matrix, and based on preset stability judgment conditions, determines the safety domain of the first control parameter, the second control parameter, and the capacity ratio when each rate matrix meets the stability condition. The present invention can quickly and accurately determine the small-disturbance stability of a hybrid station.

[0093] It should be understood that the content described in this section is not intended to identify the key or important features of the embodiments of the present invention, nor is it intended to limit the scope of the present invention. Other features of the present invention will become readily understood through the following description. BRIEF DESCRIPTION OF THE DRAWINGS

[0094] In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the following briefly introduces the drawings required for use in the description of the embodiments. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work.

[0095] Figure 1 This is a flowchart of an embodiment of a method for constructing a small interference stability parameter safety domain of a hybrid station provided by the present invention;

[0096] Figure 2 A flowchart of a sub-embodiment of a method for constructing a small interference stability parameter safety region for a hybrid station provided by the present invention;

[0097] Figure 3 This is a structural diagram of the control system and main circuit of the grid-following controlled power generation unit provided by the present invention;

[0098] Figure 4 A structural diagram of the control system and main circuit of the grid-type control power generation unit provided by the present invention;

[0099] Figure 5 A flowchart of another sub-embodiment of a method for constructing a small interference stability parameter safety region for a hybrid station provided by the present invention;

[0100] Figure 6 An equivalent circuit diagram of a hybrid station in an embodiment of the present invention;

[0101] Figure 7 A schematic diagram of the distribution of root loci in an imaginary coordinate system according to an embodiment of the present invention;

[0102] Figure 8 The result of constructing the small interference stability parameter safety domain of the hybrid station in the present invention;

[0103] Figure 9 This is a device structure diagram of an embodiment of a device for constructing a small interference stability parameter safety domain for a hybrid station provided by the present invention. DETAILED DESCRIPTION

[0104] In order to enable those skilled in the art to better understand the solutions of the present invention, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the embodiments described are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts should fall within the scope of protection of the present invention.

[0105] It should be noted that the terms "first", "second", etc. in the description and claims of the present invention and the above-mentioned drawings are used to distinguish similar objects and are not necessarily used to describe a specific order or sequence. It should be understood that the numbers used in this way can be interchanged where appropriate, so that the embodiments of the present invention described herein can 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.

[0106] Example 1

[0107] Figure 1 A flowchart of a method for constructing a small interference stability parameter safety domain of a hybrid station is provided for the first embodiment of the present invention. Figure 1 As shown, the method includes:

[0108] S101. Construct an equivalent circuit diagram of a hybrid station based on an equivalent circuit of a sequence admittance model of N grid-following controlled power generation units and an equivalent circuit of a sequence impedance model of M grid-forming controlled power generation units; the sequence admittance model includes a first control parameter of the grid-following controlled power generation unit; and the sequence impedance model includes a second control parameter of the grid-forming controlled power generation unit.

[0109] The grid-type controlled power generation unit is usually equivalent to a current source, while the grid-type controlled power generation unit is usually equivalent to a voltage source. Therefore, in the present invention, the grid-type controlled power generation unit can be equivalent to an equivalent circuit in which an admittance is connected in parallel with a current source, and the grid-type controlled power generation unit can be equivalent to an equivalent circuit in which an impedance is connected in series with a voltage source. Of course, the present invention can also equate the grid-type controlled power generation unit to an equivalent circuit in which an impedance is connected in series with a voltage source, and the grid-type controlled power generation unit to an equivalent circuit in which an admittance is connected in parallel with a current source.

[0110] The sequence admittance model of the grid-following type control power generation unit includes the first control parameter of the grid-following type control power generation unit, and the sequence impedance model of the grid-forming type control power generation unit includes the second control parameter of the grid-forming type control power generation unit. The control parameters have a great correlation with the small disturbance stability of the hybrid station.

[0111] In this embodiment, the equivalent circuit of the sequence admittance model of N grid-following type control power generation units and the equivalent circuit of the sequence impedance model of M grid-forming type control power generation units are used to construct the equivalent circuit diagram of the hybrid station. The capacity ratio of each type of control power generation unit to the hybrid grid power generation unit, that is, N / N+M or M / N+M, also has a great correlation with the small disturbance stability of the hybrid station.

[0112] To construct the equivalent circuit of a hybrid station, the equivalent circuit of a grid-controlled power generation unit and the equivalent circuit of a grid-connected power generation unit can be converted into equivalent circuits of the same type, and then the equivalent circuit diagram of the hybrid station can be further constructed. For example, the equivalent circuit of a grid-controlled power generation unit with an admittance connected in parallel to a current source can be converted into an equivalent circuit of an impedance connected in series with a voltage source, and then the equivalent circuit of the grid-controlled power generation unit with an impedance connected in series with the voltage source and the equivalent circuit of the grid-connected power generation unit with an impedance connected in series with the voltage source can be constructed together to form the equivalent circuit diagram of the hybrid station. Alternatively, the equivalent circuit of a grid-controlled power generation unit with an impedance connected in series with the voltage source can be converted into an equivalent circuit of an admittance connected in parallel to a current source, and then the equivalent circuit of the grid-controlled power generation unit with an admittance connected in parallel to the current source and the equivalent circuit of the grid-connected power generation unit with an admittance connected in parallel to the current source can be constructed together to form the equivalent circuit diagram of the hybrid station. Since the hybrid station includes at least one grid-following type controlled power generation unit and at least one grid-forming type controlled power generation unit, this embodiment can convert the grid-following type controlled power generation unit and the grid-forming type controlled power generation unit into the same type of equivalent circuit, and then connect the equivalent circuit of at least one grid-following type controlled power generation unit and the equivalent circuit of at least one grid-forming type controlled power generation unit in parallel to form an equivalent circuit diagram of the hybrid station.

[0113] S102: Calculate a grid-connected current expression of the hybrid station based on the equivalent circuit diagram of the hybrid station.

[0114] After constructing the equivalent circuit diagram of the hybrid station, the grid-connected current expression or grid-connected voltage expression of the hybrid station can be calculated based on the equivalent circuit diagram. To facilitate the stability analysis of the grid-connected power grid, the grid-connected current expression of the hybrid station is usually calculated. The grid-connected current expression is related to the capacity ratio of the grid-following and grid-forming controlled power generation units, as well as the control parameters of the grid-following and grid-forming controlled power generation units.

[0115] S103: extracting the rate matrix of each grid-connected current component relative to the grid in the grid-connected current expression.

[0116] Each current component of the grid-connected current expression can be converted into the form of unit negative feedback transfer function * power coefficient, and the unit negative feedback open-loop transfer function can be used as the rate matrix, which is used to judge the stability performance of the system.

[0117] S104. Estimate the root locus distribution of the rate of return matrix, and based on a preset stability judgment condition, determine the safety domain of the first control parameter, the second control parameter, and the capacity ratio when each rate of return matrix satisfies the stability condition; the capacity ratio is the ratio of the number of the grid-following type control power generation units to the power generation units of the hybrid station, or the ratio of the number of the grid-forming type control power generation units to the power generation units of the hybrid station.

[0118] The present invention can use any method to estimate the eigenvalues ​​of the rate matrix to obtain the root locus distribution of the rate matrix. The stability can be judged based on the root locus distribution in the imaginary coordinate system based on the Nyquist criterion, or other preset stability judgment conditions can be used to judge whether the rate matrix meets the stability condition. When the rate matrices of all components in the grid-connected current expression of the hybrid station meet the stability condition, it means that the hybrid station has high small-disturbance stability. In this embodiment, it is necessary to determine that when the rate matrices of all components in the grid-connected current expression of the hybrid station meet the stability condition, the safety domain of the first control parameter, the second control parameter and the capacity ratio in the rate matrix are solved.

[0119] The embodiment of the present invention constructs an equivalent circuit diagram of a hybrid station based on an equivalent circuit of a sequence admittance model of N grid-following control power generation units and an equivalent circuit of a sequence impedance model of M grid-forming control power generation units; calculates the grid-connected current expression of the hybrid station based on the equivalent circuit diagram of the hybrid station, thereby correlating each grid-connected current component in the grid-connected current expression with a capacity ratio parameter and the grid-following control power generation unit and the grid-forming control power generation unit; extracts the rate matrix of each grid-connected current component in the grid-connected current expression relative to the power grid; estimates the root locus distribution of the rate matrix, and based on preset stability judgment conditions, determines the safety domain of the first control parameter, the second control parameter, and the capacity ratio when each rate matrix meets the stability condition. The present invention can quickly and accurately determine the small-disturbance stability of the hybrid station.

[0120] In one embodiment, before step S101, the method further includes:

[0121] S201. Establish a sequence admittance model of a grid-following type controlled power generation unit and a sequence impedance model of a grid-building type controlled power generation unit.

[0122] In one embodiment, the main circuit structure diagram of the grid-following power generation unit can be as follows: Figure 3 The circuit shown in FIG. 1 and the main circuit structure diagram of the grid-type control power generation unit can be as follows: Figure 4The circuit shown in the figure is of course different in practice. The main circuit structure diagram of a grid-controlled power generation unit and the main circuit structure of a grid-controlled power generation unit may differ. A sequence admittance model for the grid-controlled power generation unit and a sequence impedance model for the grid-controlled power generation unit can be established based on the actual main circuit structures of the grid-controlled power generation unit and the grid-controlled power generation unit, respectively. Alternatively, a sequence impedance model for the grid-controlled power generation unit and a sequence admittance model for the grid-controlled power generation unit can be established. In practice, since a grid-controlled power generation unit can typically be equivalent to a current source, while a grid-controlled power generation unit is typically equivalent to a voltage source, the grid-controlled power generation unit is generally equated to a sequence admittance model, and the grid-controlled power generation unit is generally equated to a sequence impedance model. The main circuit structure diagram of the grid-controlled power generation unit includes the control parameters of the PI controller, while the main circuit structure diagram of the grid-controlled power generation unit includes the control parameters corresponding to the reactive loop. That is, when the sequence admittance model and the sequence impedance model of the grid-controlled power generation unit are generated, the corresponding control parameters are already included in the models.

[0123] Step S201 specifically includes:

[0124] S2011. Injecting a positive-sequence disturbance voltage or a negative-sequence disturbance voltage into the grid-connected node of the grid-controlled power generation unit to obtain a corresponding phase-sequence current; calculating at least two admittance values ​​based on the positive-sequence disturbance voltage, the phase-sequence current in response to the positive-sequence disturbance voltage, the negative-sequence disturbance voltage, and the phase-sequence current in response to the negative-sequence disturbance voltage, and forming a sequence admittance matrix model of the grid-controlled power generation unit with the at least two admittance values;

[0125] In one embodiment, a frequency of Positive / negative sequence disturbance voltage , The amplitude and initial phase of and ; Then the grid-connected voltage of phase A of the grid-following controlled power generation unit is:

[0126] (1)

[0127] and The amplitude and frequency of the fundamental voltage.

[0128] Convert the above formula into frequency domain expression:

[0129] (2)

[0130] Where, , ;

[0131] The frequency domain expression of phase A of the grid-following control power generation unit is derived as follows:

[0132] (3)

[0133] Where, and Represent the fundamental frequency current component and positive / negative sequence current component respectively; represents the positive sequence coupled current component; Indicates the rated angular frequency of the power grid;

[0134] Then the positive sequence admittance and positive sequence coupling admittance for:

[0135]

[0136]

[0137] Negative sequence admittance and negative sequence coupling admittance The formulas for positive sequence admittance and positive sequence coupling admittance are the same; the output sequence admittance matrix model of the grid-following control power generation unit can be obtained as follows:

[0138] (4)

[0139] The calculation formulas of the negative-sequence admittance, the negative-sequence coupled admittance, the positive-sequence admittance and the positive-sequence coupled admittance all include the first control parameter.

[0140] If the output sequence impedance matrix model of the grid-following controlled power generation unit is calculated, after calculating the frequency domain expressions of the grid-connected voltage and grid-connected current of phase A of the grid-following controlled power generation unit, it is only necessary to calculate the positive sequence impedance, positive sequence coupling impedance, negative sequence impedance and negative sequence coupling impedance of the grid-following controlled power generation unit based on the ratio of the positive sequence / negative sequence current component of the voltage to the positive sequence / negative sequence current component of the current, and the ratio of the positive sequence / negative sequence current component of the voltage to the positive sequence / negative sequence coupled current component of the current.

[0141] S2012. Inject a positive-sequence disturbance voltage or a negative-sequence disturbance voltage into the grid-connected node of the grid-controlled power generation unit to obtain a corresponding phase-sequence current; based on the positive-sequence disturbance voltage, the phase-sequence current in response to the positive-sequence disturbance voltage, the negative-sequence disturbance voltage, and the phase-sequence current in response to the negative-sequence disturbance voltage, calculate at least two impedance values, and constitute a sequence impedance matrix model of the grid-controlled power generation unit by the at least two impedance values.

[0142] In one embodiment, a frequency of Positive / negative sequence small signal voltage , The amplitude and initial phase of and The grid-connected voltage of phase A of the grid-controlled power generation unit is obtained as follows:

[0143]

[0144] Where, and The amplitude and frequency of the fundamental voltage;

[0145] Convert the above formula into frequency domain expression:

[0146]

[0147] Where, , ;

[0148] The frequency domain expression of phase A of the grid-type controlled power generation unit is derived as follows:

[0149]

[0150] Where, and Represent the fundamental frequency current component and positive / negative sequence current component respectively; represents the positive sequence coupled current component; Indicates the rated angular frequency of the power grid;

[0151] Then the positive sequence impedance and positive sequence coupling impedance for:

[0152]

[0153]

[0154] Negative sequence admittance and negative sequence coupling admittance The formulas for positive sequence admittance and positive sequence coupling admittance are the same; the output sequence admittance matrix model of the grid-following control power generation unit can be obtained as follows:

[0155]

[0156] The calculation formulas of the negative-sequence impedance, the negative-sequence coupling impedance, the positive-sequence impedance and the positive-sequence coupling impedance all include the second control parameter.

[0157] If the output sequence admittance matrix model of the grid-controlled power generation unit is calculated, after calculating the frequency domain expressions of the grid-connected voltage and grid-connected current of phase A of the grid-controlled power generation unit, it is only necessary to calculate the positive-sequence impedance, positive-sequence coupling impedance, negative-sequence impedance and negative-sequence coupling impedance of the grid-controlled power generation unit based on the ratio of the positive-sequence / negative-sequence current component of the current to the positive-sequence / negative-sequence current component of the voltage, and the ratio of the positive-sequence / negative-sequence coupling current component of the current to the positive-sequence / negative-sequence current component of the voltage.

[0158] S202 , establishing an equivalent circuit of a sequence admittance model of the grid-following type controlled power generation unit and an equivalent circuit of a sequence impedance model of the grid-forming type controlled power generation unit respectively.

[0159] The grid-type controlled power generation unit is usually equivalent to a current source, while the grid-type controlled power generation unit is usually equivalent to a voltage source. Therefore, in the present invention, the grid-type controlled power generation unit can be equivalent to an equivalent circuit in which an admittance is connected in parallel with a current source, and the grid-type controlled power generation unit can be equivalent to an equivalent circuit in which an impedance is connected in series with a voltage source. Of course, the present invention can also equate the grid-type controlled power generation unit to an equivalent circuit in which an impedance is connected in series with a voltage source, and the grid-type controlled power generation unit to an equivalent circuit in which an admittance is connected in parallel with a current source.

[0160] In one embodiment, step S101 is specifically as follows:

[0161] The equivalent circuit diagram of the hybrid station includes: a grid-following circuit group formed by the equivalent circuits of at least two grid-following control power generation units connected in parallel, and a grid-forming circuit group formed by the equivalent circuits of at least two grid-forming control power generation units;

[0162] The first end of the grid-following circuit group and the first end of the grid-forming circuit group are both electrically connected to the first end of the grid impedance, the second end of the grid impedance is connected to the first end of the grid power supply, and the second end of the grid power supply is grounded;

[0163] The second end of the network circuit group and the second end of the network circuit group are both grounded. Figure 6 The circuit diagram is shown below.

[0164] In one embodiment, step S102 is specifically as follows:

[0165] For the grid-connected output current of the i-th grid-following control generating unit for:

[0166] (5)

[0167] Where N is the number of grid-following control power generation units, , ; M is the number of grid-type control power generation units, ; 、 、 as well as Represents the grid power supply , its own equivalent current source , other grid-following controlled power generation units And the equivalent current source of the grid-type control power generation unit Grid-connected output current The contribution coefficients are as follows:

[0168] (6)

[0169] (7)

[0170] (8)

[0171] (9)

[0172] Where, is the equivalent admittance value of the i-th grid-following control generating unit; is the equivalent admittance of the power grid; , ; represents the equivalent output voltage and equivalent impedance of the j-th grid-type controlled power generation unit;

[0173] If the parameters of the control type power generation units in the hybrid station are the same, then:

[0174] (10)

[0175] Then the grid-connected output current of the i-th grid-following control generating unit is Simplified to:

[0176] (11)

[0177] Where, Indicates that the grid power supply is Contributing current components; Indicates the grid-following type control power generation unit pair Contributing current components; Represents the grid-type control power generation unit pair Contributing current components;

[0178] Similarly, the grid-connected output current of the i-th grid-controlled power generation unit Simplified to:

[0179] (12)

[0180] Where, Indicates that the grid power supply is Contributing current components; Indicates the grid-following type control power generation unit pair Contributing current components; Represents the grid-type control power generation unit pair Contributing current components;

[0181] The grid current of the hybrid station is for:

[0182] (13)

[0183] The grid-connected current expression is:

[0184] (14)

[0185] It can be seen that each grid-connected current component of the grid-connected current expression contains N and M, that is, the grid-connected current component is related to the capacity ratio parameter; the grid-connected current component also includes as well as ,and Related to the first control parameter, It is related to the second control parameter, that is, the grid-connected current component is related to the first control parameter and the second control parameter.

[0186] In one embodiment, step S103 is specifically as follows:

[0187] Convert each component in the grid-connected current expression into the form of unit negative feedback transfer function*power factor:

[0188] (15)

[0189] Where: Indicates current The j-th component of ; Indicates the power factor of this current; Represents the unit negative feedback open-loop transfer function, also defined as the rate matrix.

[0190] For example, the first grid-connected current component in formula (11) can be Converted into the form of unit negative feedback transfer function * power coefficient, that is, The numerator and denominator of the expression are multiplied by the grid admittance to obtain:

[0191] (16)

[0192] Where, and Where are the power coefficient and the open-loop transfer function, that is, the rate matrix is , it can be seen that the rate matrix is ​​related to the first control parameter, the second control parameter and the capacity ratio.

[0193] Similarly, the other current components in formula (11) and formula (12) can be converted into the form of unit negative feedback transfer function*power coefficient, and the feedback matrix of each grid-connected current component in the grid-connected current can be obtained.

[0194] In one embodiment, step S105 is specifically as follows:

[0195] The eigenvalue estimation method based on the Gale disk theorem is used to estimate the return matrix , the i-th eigenvalue of the return matrix Circular domains distributed on the complex plane Inside:

[0196] (17)

[0197] in, for:

[0198] (18)

[0199] Where C represents a complex set; The radius of the circle representing the i-th eigenvalue; Represents the parameter of the i-th row and j-th column of the return rate matrix;

[0200] Estimate the root locus distribution of each rate matrix based on the above formula;

[0201] Compare the root locus distribution with the preset forbidden space. If the root locus distribution does not enter the forbidden space, it means that the rate matrix meets the stability condition.

[0202] The safety region of the first control parameter, the second control parameter and the capacity ratio is calculated when the rate matrices of all grid-connected current components meet the stability condition.

[0203] like Figure 7 As shown, Figure 7 The forbidden area is The feasible region is The two circles in the figure represent the root loci of the two eigenvalues. This means that when the root loci of the eigenvalues ​​of the rate matrices of all current components of the hybrid station's grid-connected current are within the feasible region, the hybrid station satisfies the stability conditions. Therefore, the distance from the center of the circle to the line Re = -1 can be calculated to be greater than the radius of the circle, which serves as the basis for determining stability. This allows us to determine the parameter ranges for the first control parameter, the second control parameter, and the capacity ratio when the rate matrices of all grid-connected current components meet the stability conditions. This parameter range is the safe region for the small-disturbance stability parameters of the hybrid station.

[0204] According to the Generalized Nyquist Criterion (GNC), a sufficient condition for the stability of the hybrid station with small interference is that the root loci of the eigenvalues ​​of the above-mentioned hysteresis matrices surround the point on the complex plane The number of circles is 0. The present invention can obtain the spatial distribution of the eigenvalue root locus based on the eigenvalue estimation method, without the need for Nyquist curve analysis, and can directly set constraints to ensure that it meets the generalized Nyquist criterion. Therefore, in the present invention, by setting a straight line forbidden region as the forbidden region of the root locus, the eigenvalue estimation method based on the Gale disk theorem is used to obtain the position of the root locus, and the stability condition of the generalized Nyquist criterion is satisfied by ensuring that the position of the root locus does not enter the forbidden region, thereby obtaining the feasible domain of the combination of the capacity ratio parameters of the power generation (energy storage) units of different control types and the control parameters in the hybrid station, so that the stability analysis results of the hybrid station can be quickly obtained.

[0205] In a specific embodiment, a hybrid station containing N grid-following type control power generation units and M grid-building type control power generation units of new energy power generation units may be set up.

[0206] In this hybrid station, the capacity (number) ratio parameters of the grid-following control power generation units are: , namely N / (N+M), is one of the leading parameters of small disturbance stability in this embodiment. In the hybrid station, the control system and main circuit structure of the grid-following control power generation unit can refer to Figure 3 The circuit diagram shown, the control system and main circuit structure of the grid-type control power generation unit can refer to Figure 4 The parameters and meanings of the controller and main circuit of each unit are shown in Tables 1 and 2 below.

[0207] Table 1 Parameters of grid-following control power generation unit

[0208]

[0209] Table 2 Parameters of grid-type control power generation unit

[0210]

[0211] Among them, the parameters in Table 1 And the parameters in Table 2 Also as the dominant parameter for small disturbance stability, it is similar to the capacity ratio parameter mentioned above. The set of parameters that together constitute the small disturbance stability parameter safety region of this example.

[0212] The solution of the present invention constructs its small-disturbance stability parameter safety region based on the combination of the disk theorem eigenvalue estimation method and the circle theory line forbidden region (CTLFR) criterion, and compares the results with those obtained by the method based on the generalized Nyquist criterion (GNC), such as Figure 8 As shown. Figure 8 It can be seen that the parameter safety domain obtained by the method of the present invention belongs to a subset of the results obtained based on the GNC criterion method, which proves the effectiveness of the method of the present invention, that is, the parameter combination range represented by the parameter safety domain constructed by the present invention meets the GNC small disturbance stability condition.

[0213] Furthermore, the time overhead of the CTLFR method and the GNC method is compared, as shown in Table 3 below.

[0214] Table 3 Comparison of time for constructing parameter safety domain between CTLFR and GNC methods

[0215]

[0216] Note: The simulation analysis hardware environment of this example is based on the Intel(R) Xeon(R) Platinum 8124M CPU @3.00GHz processor, and the simulation analysis software environment is Matlab R2022b.

[0217] As can be seen from the table above, the CTLFR method takes significantly less time than the GNC method, reducing time costs by approximately 53.5% and improving computational efficiency. This demonstrates the superior computational efficiency of the proposed method when constructing parameter safety domains. It is worth noting that with a significant increase in parameter dimensionality (currently, two types of three-dimensional parameters for controlling power generation units, with additional capacity ratio parameters and corresponding control parameters to be considered in the future), computational efficiency will increase exponentially, meeting the requirements of online applications.

[0218] Figure 9 This is a schematic diagram of the structure of a small disturbance stability analysis device for a hybrid station provided by the present invention. Figure 9 As shown, the device includes:

[0219] The model construction unit 301 is used to construct an equivalent circuit diagram of the hybrid station based on the equivalent circuit of the sequence admittance model of N grid-following type controlled power generation units and the equivalent circuit of the sequence impedance model of M grid-forming type controlled power generation units; the sequence admittance model includes the first control parameters of the grid-following type controlled power generation units; the sequence impedance model includes the second control parameters of the grid-forming type controlled power generation units.

[0220] The calculation unit 302 is configured to calculate a grid-connected current expression of the hybrid station based on the equivalent circuit diagram of the hybrid station.

[0221] The extraction unit 303 is configured to extract a rate matrix of each grid-connected current component relative to the grid in the grid-connected current expression.

[0222] The safety domain construction unit 304 is used to estimate the root locus distribution of the rate of return matrix and determine, based on preset stability judgment conditions, the safety domain of the first control parameter, the second control parameter, and the capacity ratio when each rate of return matrix meets the stability condition; the capacity ratio is the ratio of the number of the grid-following type control power generation units to the power generation units of the hybrid site, or the ratio of the number of the grid-forming type control power generation units to the power generation units of the hybrid site.

[0223] In one embodiment, the apparatus further comprises:

[0224] The model building unit 401 is used to build a sequence admittance model of a grid-following type control power generation unit and a sequence impedance model of a grid-building type control power generation unit;

[0225] The equivalent conversion unit 402 is used to respectively establish an equivalent circuit of the sequence admittance model of the grid-following type controlled power generation unit and an equivalent circuit of the sequence impedance model of the grid-forming type controlled power generation unit.

[0226] The small disturbance stability analysis device for a hybrid station provided in an embodiment of the present invention can execute the small disturbance stability analysis device for a hybrid station provided in any embodiment of the present invention, and has the corresponding functional modules and beneficial effects of the execution method.

[0227] It should be understood that the various forms of the processes shown above can be used to reorder, add, or delete steps. For example, the steps described in the present invention can be performed in parallel, sequentially, or in a different order, as long as the desired results of the technical solution of the present invention can be achieved. This is not limited herein.

[0228] The above specific embodiments do not limit the scope of protection of the present invention. Those skilled in the art will appreciate that various modifications, combinations, sub-combinations, and substitutions may be made based on design requirements and other factors. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention are intended to be included within the scope of protection of the present invention.

Claims

1. A method for constructing a small interference stability parameter safety region of a hybrid station, characterized in that: include: An equivalent circuit diagram of a hybrid station is constructed based on an equivalent circuit of a sequence admittance model of N grid-following controlled power generation units and an equivalent circuit of a sequence impedance model of M grid-forming controlled power generation units; the sequence admittance model includes a first control parameter of the grid-following controlled power generation unit; and the sequence impedance model includes a second control parameter of the grid-forming controlled power generation unit. Calculating a grid-connected current expression of the hybrid station based on an equivalent circuit diagram of the hybrid station; Extracting the return rate matrix of each grid-connected current component relative to the grid in the grid-connected current expression; estimating the root locus distribution of the rate of return matrix, and determining, based on a preset stability judgment condition, a safe region of the first control parameter, the second control parameter, and the capacity ratio when each rate of return matrix satisfies a stability condition; The capacity ratio is the ratio of the number of the grid-following type control power generation units to the number of the hybrid station power generation units, or the ratio of the number of the grid-forming type control power generation units to the number of the hybrid station power generation units.

2. The method for constructing a small interference stability parameter safety region of a hybrid station according to claim 1, characterized in that: The equivalent circuit diagram of the hybrid station is constructed based on the equivalent circuit of the sequence admittance model of the N grid-following type control power generation units and the equivalent circuit of the sequence impedance model of the M grid-forming type control power generation units, which also includes: Establishing a sequence admittance model of the grid-following type controlled power generation unit and a sequence impedance model of the grid-forming type controlled power generation unit; An equivalent circuit of the sequence admittance model of the grid-following type controlled power generation unit and an equivalent circuit of the sequence impedance model of the grid-building type controlled power generation unit are respectively established.

3. The method for constructing a small interference stability parameter safety region of a hybrid station according to claim 2, characterized in that: The establishment of the sequence admittance model of the grid-following control power generation unit, and the The sequence impedance model of the grid-type controlled power generation unit is described, including: Injecting a positive-sequence disturbance voltage or a negative-sequence disturbance voltage into a grid-connected node of the grid-following controlled power generation unit to obtain a corresponding phase-sequence current; calculating at least two admittance values ​​based on the positive-sequence disturbance voltage, the phase-sequence current in response to the positive-sequence disturbance voltage, the negative-sequence disturbance voltage, and the phase-sequence current in response to the negative-sequence disturbance voltage, and forming a sequence admittance matrix model of the grid-following controlled power generation unit with the at least two admittance values; A positive-sequence disturbance voltage or a negative-sequence disturbance voltage is injected into the grid-connected node of the grid-type controlled power generation unit to obtain a corresponding phase-sequence current; based on the positive-sequence disturbance voltage, the phase-sequence current in response to the positive-sequence disturbance voltage, the negative-sequence disturbance voltage, and the phase-sequence current in response to the negative-sequence disturbance voltage, at least two impedance values ​​are calculated, and a sequence impedance matrix model of the grid-type controlled power generation unit is formed by the at least two impedance values.

4. The method for constructing a small interference stability parameter safety region of a hybrid station according to claim 3 is characterized in that: The method includes injecting a positive-sequence disturbance voltage or a negative-sequence disturbance voltage into the grid-connected node of the grid-following controlled power generation unit to obtain a corresponding phase-sequence current; calculating at least two admittance values ​​based on the positive-sequence disturbance voltage, the phase-sequence current in response to the positive-sequence disturbance voltage, the negative-sequence disturbance voltage, and the phase-sequence current in response to the negative-sequence disturbance voltage, and forming a sequence admittance matrix model of the grid-following controlled power generation unit with the at least two admittance values, including: The positive / negative sequence disturbance voltage is injected into the grid-connected node of the grid-following controlled power generation unit, and the grid-connected voltage of phase A of the grid-following controlled power generation unit is obtained as follows: In the formula, the frequency is Positive / negative sequence small signal voltage The amplitude and initial phase of and ; and The amplitude and frequency of the fundamental voltage; Convert the above formula into frequency domain expression: Where, , ; The frequency domain expression of the grid-following control power generation unit phase A is derived as follows: Where, and Represent the fundamental frequency current component and positive / negative sequence current component respectively; represents the positive sequence coupled current component; Indicates the rated angular frequency of the power grid; Then the positive sequence admittance and positive sequence coupling admittance for: Negative sequence admittance and negative sequence coupling admittance The formulas for positive sequence admittance and positive sequence coupling admittance are the same; the output sequence admittance matrix model of the grid-following control power generation unit can be obtained as follows: The calculation formulas of the negative-sequence admittance, the negative-sequence coupled admittance, the positive-sequence admittance, and the positive-sequence coupled admittance all include the first control parameter.

5. The method for constructing a small interference stability parameter safety region of a hybrid station according to claim 3, characterized in that: The method includes injecting a positive-sequence disturbance voltage or a negative-sequence disturbance voltage into the grid-connected node of the grid-type controlled power generation unit to obtain a corresponding phase-sequence current; calculating at least two impedance values ​​based on the positive-sequence disturbance voltage, the phase-sequence current in response to the positive-sequence disturbance voltage, the negative-sequence disturbance voltage, and the phase-sequence current in response to the negative-sequence disturbance voltage, and forming a sequence impedance matrix model of the grid-type controlled power generation unit with the at least two impedance values, including: The positive sequence / negative sequence disturbance voltage is injected into the grid-connected node of the grid-controlled power generation unit to obtain the grid-connected voltage of phase A of the grid-controlled power generation unit: In the formula, the frequency is Positive / negative sequence small signal voltage The amplitude and initial phase of and ; and The amplitude and frequency of the fundamental voltage; Convert the above formula into frequency domain expression: Where, , ; The frequency domain expression of the grid-type controlled power generation unit phase A is derived as follows: Where, and Represent the fundamental frequency current component and positive / negative sequence current component respectively; represents the positive sequence coupled current component; Indicates the rated angular frequency of the power grid; Then the positive sequence impedance and positive sequence coupling impedance for: Negative sequence impedance and negative sequence coupling impedance The formulas for the positive sequence impedance and positive sequence coupling impedance are the same; the output sequence impedance matrix model of the grid-type controlled power generation unit can be obtained as follows: The calculation formulas of the negative-sequence impedance, the negative-sequence coupling impedance, the positive-sequence impedance, and the positive-sequence coupling impedance all include the second control parameter.

6. The method for constructing a small interference stability parameter safety region of a hybrid station according to claim 1, characterized in that: The equivalent circuit diagram of the hybrid station is constructed based on the equivalent circuit of the sequence admittance model of the N grid-following type controlled power generation units and the equivalent circuit of the sequence impedance model of the M grid-forming type controlled power generation units, including: The equivalent circuit diagram of the hybrid station includes: a grid-following circuit group formed by connecting the equivalent circuits of N grid-following control power generation units in parallel, and a grid-forming circuit group formed by the equivalent circuits of M grid-forming control power generation units; The first end of the grid-following circuit group and the first end of the grid-forming circuit group are both electrically connected to the first end of the grid impedance, the second end of the grid impedance is connected to the first end of the grid power supply, and the second end of the grid power supply is grounded; The second end of the network following circuit group and the second end of the network forming circuit group are both grounded.

7. The method for constructing a small interference stability parameter safety region of a hybrid station according to claim 6, characterized in that: The calculating of the grid-connected current expression of the hybrid station based on the equivalent circuit diagram of the hybrid station includes: For the grid-connected output current of the i-th grid-following control generating unit for: Where N is the number of grid-following control power generation units, , ; M is the number of grid-type control power generation units, ; 、 、 as well as Represents the grid power supply , its own equivalent current source , other grid-following controlled power generation units And the equivalent current source of the grid-type control power generation unit Grid-connected output current The contribution coefficients are as follows: Where, is the equivalent admittance value of the i-th grid-following control generating unit; is the equivalent admittance of the power grid; , ; represents the equivalent output voltage and equivalent impedance of the j-th grid-type controlled power generation unit; If the parameters of the control type power generation units in the hybrid station are the same, then: Then the grid-connected output current of the i-th grid-following control generating unit is Simplified to: Where, Indicates that the grid power supply is Contributing current components; Indicates the grid-following type control power generation unit pair Contributing current components; Represents the grid-type control power generation unit pair Contributing current components; Similarly, the grid-connected output current of the i-th grid-controlled power generation unit Simplified to: Where, Indicates that the grid power supply is Contributing current components; Indicates the grid-following type control power generation unit pair Contributing current components; Represents the grid-type control power generation unit pair Contributing current components; The grid current of the hybrid station is for: The grid-connected current expression is: 。 8. The method for constructing a small interference stability parameter safety region of a hybrid station according to claim 1, characterized in that: The step of extracting a return matrix of the grid-connected current expression relative to the grid includes: Convert each component in the grid-connected current expression into the form of unit negative feedback transfer function*power factor: Where: Indicates current The j-th component of ; Indicates the power factor of this current; Represents the unit negative feedback open-loop transfer function, also defined as the rate matrix.

9. The method for constructing a small interference stability parameter safety region of a hybrid station according to claim 8, characterized in that: The estimating the root locus distribution of the rate of return matrix and determining, based on a preset stability judgment condition, a safety region of the first control parameter, the second control parameter, and the capacity ratio when each rate of return matrix satisfies a stability condition, includes: The eigenvalue estimation method based on the Gale disk theorem is used to estimate the return matrix , the i-th eigenvalue of the return matrix Circular domains distributed on the complex plane Inside: in, for: Where C represents a complex set; The radius of the circle representing the i-th eigenvalue; Represents the parameter of the i-th row and j-th column of the return rate matrix; Estimate the root locus distribution of each of the rate matrices based on the above formula; Comparing the root locus distribution with a preset forbidden space, if the root locus distribution does not enter the forbidden space, it indicates that the rate matrix meets the stability condition; Calculate the feasible region of the first control parameter, the second control parameter, and the capacity ratio when the rate matrices of all the grid-connected current components meet the stability condition.

10. A device for constructing a small interference stability parameter safety region of a hybrid station, characterized in that: include: a model construction unit, configured to construct an equivalent circuit diagram of the hybrid station based on an equivalent circuit of a sequence admittance model of N grid-following controlled power generation units and an equivalent circuit of a sequence impedance model of M grid-forming controlled power generation units; the sequence admittance model includes a first control parameter of the grid-following controlled power generation unit; and the sequence impedance model includes a second control parameter of the grid-forming controlled power generation unit; A calculation unit, configured to calculate a grid-connected current expression of the hybrid station based on an equivalent circuit diagram of the hybrid station; An extraction unit, configured to extract a return matrix of each grid-connected current component relative to the grid in the grid-connected current expression; a safety domain construction unit, configured to estimate the root locus distribution of the rate of return matrix and, based on a preset stability judgment condition, determine a safety domain of the first control parameter, the second control parameter, and the capacity ratio when each rate of return matrix satisfies a stability condition; The capacity ratio is the ratio of the number of the grid-following type control power generation units to the number of the hybrid station power generation units, or the ratio of the number of the grid-forming type control power generation units to the number of the hybrid station power generation units.

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