Overvoltage risk assessment method, device and equipment for non-full-phase operation of new energy access weak grid system

Abstract

The invention relates to an overvoltage risk assessment method, device and equipment for non-full-phase operation of a new energy access weak power grid system. The method comprises the following steps: acquiring electrical quantity data of the new energy access weak power grid system, and a voltage source, grid-connected equivalent impedance, series equivalent impedance and non-full-phase operation line impedance of a power transmission line of the new energy access weak power grid system with a single-phase fault; calculating n positive sequence current vectors and negative sequence current vectors according to each piece of electrical quantity data; calculating n positive sequence port voltage vectors and negative sequence port voltage vectors according to the fault data, each positive sequence current vector and each negative sequence current vector; according to the positive sequence voltage component rated value, each positive sequence port voltage vector and each negative sequence port voltage vector, actual positive sequence voltage and actual negative sequence voltage are obtained through calculation; and according to the actual positive sequence voltage, the actual negative sequence voltage and the positive sequence voltage component rated value, calculating to obtain a single-phase voltage maximum value, and according to the single-phase voltage maximum value, judging whether the system has an overvoltage risk in a non-full-phase operation state.

Description

Technical Field

[0001] This application relates to the field of risk assessment technology for power systems, and in particular to a method, apparatus and equipment for assessing overvoltage risk in a weak grid system with new energy access and non-full-phase operation. Background Technology

[0002] Large-scale renewable energy sources are mostly located at the end of the power system, requiring long-distance AC transmission. Non-full-phase operation after an asymmetrical fault in the power system is a common fault condition. However, the flexible positive and negative sequence current control of renewable energy sources leads to close coupling between positive and negative sequence currents and voltages, making single-phase overvoltages more likely.

[0003] Currently, overvoltage risk is mainly assessed through electromagnetic simulation, which simulates the dynamic characteristics of three-phase voltage to obtain the maximum voltage value, thereby determining the overvoltage risk of the power system. However, this method cannot quantify the influencing factors and parameter change trends, resulting in low accuracy in judging single-phase overvoltage in the power system. Summary of the Invention

[0004] This application provides a method, apparatus, and equipment for assessing overvoltage risk in a non-full-phase operation of a new energy grid connected to a weak power grid. It addresses the technical problem that existing methods for judging single-phase overvoltage in power systems cannot quantify influencing factors and parameter change trends, resulting in low accuracy in judging single-phase overvoltage in power systems.

[0005] To achieve the above objectives, this application provides the following technical solution:

[0006] On the one hand, a method for assessing overvoltage risk in non-full-phase operation of new energy sources connected to a weak power grid system is provided, including the following steps:

[0007] Acquire positive and negative sequence electrical quantity data of n new energy access weak grid systems, and acquire voltage sources, grid-connected equivalent impedance, series equivalent impedance, and non-full-phase operation line impedance of transmission lines in the new energy access weak grid systems when a single-phase fault occurs; the electrical quantity data includes d-axis positive sequence current component, d-axis negative sequence current component, positive sequence voltage component, positive sequence reactive power injection coefficient, negative sequence reactive power injection coefficient, negative sequence voltage component, and rated value of positive sequence voltage component;

[0008] Based on each of the electrical quantity data, n positive sequence current vectors and n negative sequence current vectors are calculated;

[0009] Based on the voltage source, the grid-connected equivalent impedance, the series equivalent impedance, the non-full-phase operating line impedance, each of the positive-sequence current vectors, and each of the negative-sequence current vectors, n positive-sequence port voltage vectors and n negative-sequence port voltage vectors are calculated.

[0010] The actual positive-sequence voltage and the actual negative-sequence voltage are calculated based on the rated values ​​of the positive-sequence voltage components, the voltage vector of each positive-sequence port, and the voltage vector of each negative-sequence port; the maximum value of the single-phase voltage is calculated based on the actual positive-sequence voltage, the actual negative-sequence voltage, and the rated values ​​of the positive-sequence voltage components.

[0011] Based on the maximum value of the single-phase voltage, it can be determined whether there is an overvoltage risk when the new energy access to the weak grid system is in a non-full-phase operation state.

[0012] Preferably, the calculation of n positive-sequence current vectors and n negative-sequence current vectors based on each of the electrical quantity data includes:

[0013] Based on the rated value of the positive sequence voltage component, each of the positive sequence voltage components, the positive sequence reactive power injection coefficient, and each of the d-axis positive sequence current components, n positive sequence current vectors are obtained;

[0014] Based on each of the d-axis negative sequence current components, the negative sequence reactive power injection coefficient, and each of the negative sequence voltage components, n negative sequence current vectors are obtained.

[0015] Preferably, the calculation of n positive-sequence port voltage vectors and n negative-sequence port voltage vectors based on the voltage source, the grid-connected equivalent impedance, the series equivalent impedance, the non-full-phase operating line impedance, each positive-sequence current vector, and each negative-sequence current vector includes:

[0016] The negative sequence impedance variable is calculated based on the non-full-phase operating line impedance, the zero-sequence impedance of the grid-connected equivalent impedance, and the zero-sequence impedance of the series equivalent impedance.

[0017] The positive sequence impedance variable is calculated based on the non-full-phase operating line impedance, the zero-sequence impedance of the grid-connected equivalent impedance, the positive sequence impedance of the grid-connected equivalent impedance, the zero-sequence impedance of the series equivalent impedance, and the positive sequence impedance of the series equivalent impedance.

[0018] Based on the negative sequence impedance variable, the positive sequence impedance variable, each positive sequence current vector, and each negative sequence current vector, n negative sequence port voltage vectors are calculated;

[0019] Based on the voltage source, the negative sequence impedance variable, the positive sequence impedance variable, each positive sequence current vector, and each negative sequence current vector, n positive sequence port voltage vectors are obtained.

[0020] Preferably, the calculation of the actual positive-sequence voltage and the actual negative-sequence voltage based on the rated values ​​of the positive-sequence voltage components, each positive-sequence port voltage vector, and each negative-sequence port voltage vector includes:

[0021] Based on the rated values ​​of the positive sequence voltage components and each positive sequence port voltage vector, n positive sequence voltage vector deviations are calculated; each negative sequence port voltage vector is used as a negative sequence voltage vector deviation to obtain n negative sequence voltage vector deviations.

[0022] Based on the deviation of each positive-sequence voltage vector, n positive-sequence voltage amplitudes are obtained; based on the deviation of each negative-sequence voltage vector, n negative-sequence voltage amplitudes are obtained.

[0023] In the same coordinate system, curves are plotted based on the n positive sequence voltage vector deviations and the n positive sequence voltage amplitudes to obtain the positive sequence deviation curve and the positive sequence amplitude curve; in the same coordinate system, curves are plotted based on the n negative sequence voltage vector deviations and the n negative sequence voltage amplitudes to obtain the negative sequence deviation curve and the negative sequence amplitude curve.

[0024] The voltage at the intersection point between the positive sequence deviation curve and the positive sequence amplitude curve is taken as the actual positive sequence voltage; the voltage at the intersection point between the negative sequence deviation curve and the negative sequence amplitude curve is taken as the actual negative sequence voltage.

[0025] Preferably, determining whether there is an overvoltage risk in the new energy grid connection system under non-full-phase operation based on the maximum single-phase voltage value includes:

[0026] If the maximum value of the single-phase voltage is greater than the phase voltage overvoltage setting value, it is determined that the new energy access to the weak grid system is in a non-full-phase operation state and there is an overvoltage risk.

[0027] If the maximum value of the single-phase voltage is not greater than the phase voltage overvoltage setting value, it is determined that the new energy access to the weak grid system is in a non-full-phase operation state and there is no risk of overvoltage.

[0028] Obtaining the phase voltage overvoltage setting value includes:

[0029] Obtain the safety factor;

[0030] The phase voltage overvoltage threshold is calculated based on the rated value of the positive sequence voltage component.

[0031] The phase voltage overvoltage setting value is calculated based on the phase voltage overvoltage threshold and the safety factor.

[0032] On the other hand, an overvoltage risk assessment device for non-full-phase operation of a new energy access weak grid system is provided, including a data acquisition module, a current vector calculation module, a voltage vector calculation module, a single-phase voltage calculation module, and a risk assessment module;

[0033] The data acquisition module is used to acquire positive and negative sequence electrical quantity data of the new energy access weak grid system, as well as the voltage source, grid-connected equivalent impedance, series equivalent impedance, and non-full-phase operation line impedance of the transmission line in the new energy access weak grid system when a single-phase fault occurs; the electrical quantity data includes n d-axis positive sequence current components, n d-axis negative sequence current components, n positive sequence voltage components, positive sequence reactive power injection coefficient, negative sequence reactive power injection coefficient, n negative sequence voltage components, and rated values ​​of positive sequence voltage components;

[0034] The current vector calculation module is used to calculate n positive-sequence current vectors and n negative-sequence current vectors based on each electrical quantity data.

[0035] The voltage vector calculation module is used to calculate n positive-sequence port voltage vectors and n negative-sequence port voltage vectors based on the voltage source, the grid-connected equivalent impedance, the series equivalent impedance, the non-full-phase operating line impedance, each positive-sequence current vector, and each negative-sequence current vector.

[0036] The single-phase voltage calculation module is used to calculate the actual positive-sequence voltage and the actual negative-sequence voltage based on the rated value of the positive-sequence voltage component, the voltage vector of each positive-sequence port, and the voltage vector of each negative-sequence port; and to calculate the maximum value of the single-phase voltage based on the actual positive-sequence voltage, the actual negative-sequence voltage, and the rated value of the positive-sequence voltage component.

[0037] The risk assessment module is used to determine whether there is an overvoltage risk when the new energy access to the weak grid system is in a non-full-phase operation state based on the maximum value of the single-phase voltage.

[0038] Preferably, the current vector calculation module includes a positive sequence current calculation submodule and a negative sequence current calculation submodule;

[0039] The positive sequence current calculation submodule is used to calculate n positive sequence current vectors based on the rated value of the positive sequence voltage component, each of the positive sequence voltage components, the positive sequence reactive power injection coefficient, and each of the d-axis positive sequence current components.

[0040] The negative sequence current calculation submodule is used to calculate n negative sequence current vectors based on each of the d-axis negative sequence current components, the negative sequence reactive power injection coefficient, and each of the negative sequence voltage components.

[0041] Preferably, the voltage vector calculation module includes a positive sequence variable calculation submodule, a negative sequence variable calculation submodule, a positive sequence voltage calculation submodule, and a negative sequence voltage calculation submodule;

[0042] The positive sequence variable calculation submodule is used to calculate and obtain the positive sequence impedance variable based on the non-full-phase operating line impedance, the zero sequence impedance of the grid-connected equivalent impedance, the positive sequence impedance of the grid-connected equivalent impedance, the zero sequence impedance of the series equivalent impedance, and the positive sequence impedance of the series equivalent impedance.

[0043] The negative sequence variable calculation submodule is used to calculate and obtain the negative sequence impedance variable based on the impedance of the non-full-phase operating line, the zero sequence impedance of the grid-connected equivalent impedance, and the zero sequence impedance of the series equivalent impedance.

[0044] The positive-sequence voltage calculation submodule is used to calculate n positive-sequence port voltage vectors based on the voltage source, the negative-sequence impedance variable, the positive-sequence impedance variable, each positive-sequence current vector, and each negative-sequence current vector.

[0045] The negative sequence voltage calculation submodule is used to calculate n negative sequence port voltage vectors based on the negative sequence impedance variable, the positive sequence impedance variable, each positive sequence current vector, and each negative sequence current vector.

[0046] Preferably, the single-phase voltage calculation module includes a deviation calculation submodule, an amplitude calculation submodule, a curve plotting submodule, and an actual voltage determination submodule;

[0047] The deviation calculation submodule is used to calculate n positive sequence voltage vector deviations based on the rated values ​​of the positive sequence voltage components and each positive sequence port voltage vector; and to obtain n negative sequence voltage vector deviations by taking each negative sequence port voltage vector as a negative sequence voltage vector deviation.

[0048] The amplitude calculation submodule is used to calculate n positive-sequence voltage amplitudes based on each positive-sequence voltage vector deviation; and to calculate n negative-sequence voltage amplitudes based on each negative-sequence voltage vector deviation.

[0049] The curve plotting submodule is used to plot curves based on n positive-sequence voltage vector deviations and n positive-sequence voltage amplitudes in the same coordinate system, to obtain a positive-sequence deviation curve and a positive-sequence amplitude curve; and to plot curves based on n negative-sequence voltage vector deviations and n negative-sequence voltage amplitudes in the same coordinate system, to obtain a negative-sequence deviation curve and a negative-sequence amplitude curve.

[0050] The actual voltage determination submodule is used to take the voltage at the intersection point between the positive sequence deviation curve and the positive sequence amplitude curve as the actual positive sequence voltage; and to take the voltage at the intersection point between the negative sequence deviation curve and the negative sequence amplitude curve as the actual negative sequence voltage.

[0051] On the other hand, a terminal device is provided, including a processor and a memory;

[0052] The memory is used to store program code and transmit the program code to the processor;

[0053] The processor is used to execute the above-described overvoltage risk assessment method for non-full-phase operation of a new energy access weak grid system according to the instructions in the program code.

[0054] This invention discloses an overvoltage risk assessment method, apparatus, and equipment for non-full-phase operation of a renewable energy-connected weak grid system. The overvoltage risk assessment method includes acquiring positive-sequence and negative-sequence electrical quantity data of the renewable energy-connected weak grid system output, and acquiring the voltage source, grid-connected equivalent impedance, series equivalent impedance, and non-full-phase operation line impedance of the transmission line in the renewable energy-connected weak grid system experiencing a single-phase fault. The electrical quantity data includes n d-axis positive-sequence current components, n d-axis negative-sequence current components, n positive-sequence voltage components, positive-sequence reactive power injection coefficient, negative-sequence reactive power injection coefficient, n negative-sequence voltage components, and rated values ​​of the positive-sequence voltage components. Based on each electrical quantity data, an overvoltage risk assessment is performed... Calculate n positive-sequence current vectors and n negative-sequence current vectors; calculate n positive-sequence port voltage vectors and n negative-sequence port voltage vectors based on voltage source, grid equivalent impedance, series equivalent impedance, non-full-phase operation line impedance, each positive-sequence current vector, and each negative-sequence current vector; calculate the actual positive-sequence voltage and actual negative-sequence voltage based on the rated values ​​of the positive-sequence voltage components, each positive-sequence port voltage vector, and each negative-sequence port voltage vector; calculate the maximum single-phase voltage based on the actual positive-sequence voltage, actual negative-sequence voltage, and the rated values ​​of the positive-sequence voltage components; determine whether there is an overvoltage risk when the new energy access to the weak grid system is in a non-full-phase operation state based on the maximum single-phase voltage.

[0055] As can be seen from the above technical solutions, this application has the following advantages: The overvoltage risk assessment method for new energy access to weak grid systems in non-full-phase operation obtains the maximum value of single-phase voltage by processing n positive and negative sequence electrical quantity data, as well as the voltage source, grid equivalent impedance, series equivalent impedance, and non-full-phase operation line impedance of the single-phase fault through a series of processes. This quantifies the overvoltage risk data in new energy access to weak grid systems and assesses the overvoltage risk of new energy access to weak grid systems in non-full-phase operation based on the maximum value of single-phase voltage. This improves the accuracy and precision of assessing the overvoltage risk of new energy access to weak grid systems in non-full-phase operation and solves the technical problem that existing methods for judging single-phase overvoltage in power systems cannot quantify influencing factors and parameter change trends, resulting in low accuracy of single-phase overvoltage judgment in power systems.

[0056] This overvoltage risk assessment device for new energy access to weak grid systems operating in non-full-phase mode quantifies overvoltage risk data in such systems through a data acquisition module, a current vector calculation module, a voltage vector calculation module, a single-phase voltage calculation module, and a risk assessment module. This enables the assessment of overvoltage risk in non-full-phase operation of new energy access to weak grid systems, improving the accuracy and precision of overvoltage risk assessment in such systems. Attached Figure Description

[0057] To more clearly illustrate the technical solutions in the embodiments of this application or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0058] Figure 1 This is a flowchart illustrating the steps of the overvoltage risk assessment method for non-full-phase operation of a new energy access weak grid system as described in the embodiments of this application;

[0059] Figure 2 This is a topology diagram of a single-phase fault occurring in a transmission line of a new energy access weak grid system, as described in the overvoltage risk assessment method for non-full-phase operation of a new energy access weak grid system according to an embodiment of this application.

[0060] Figure 3 This is a schematic diagram of the equivalent circuit for a single-phase fault occurring in the transmission line of a new energy access weak grid system, as described in the overvoltage risk assessment method for non-full-phase operation of a new energy access weak grid system in this application embodiment.

[0061] Figure 4 This is a schematic diagram of the overvoltage risk assessment device for non-full-phase operation of a new energy access weak grid system as described in the embodiments of this application;

[0062] Figure 5 This is a schematic diagram of the terminal device described in an embodiment of this application. Detailed Implementation

[0063] To make the inventive objectives, features, and advantages of this application more apparent and understandable, the technical solutions in the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the embodiments described below are only some embodiments of this application, and not all embodiments. Based on the embodiments in this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0064] In the description of the embodiments of this application, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of indicated technical features. Therefore, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of the embodiments of this application, "multiple" means two or more, unless otherwise explicitly specified.

[0065] In the embodiments of this application, unless otherwise explicitly specified and limited, the terms "installation," "connection," "linking," "fixing," etc., should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral part; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication of two components or the interaction between two components. Those skilled in the art can understand the specific meaning of the above terms in the embodiments of this application according to the specific circumstances.

[0066] This application provides a method, apparatus, and equipment for assessing overvoltage risk in a non-full-phase operation of a new energy access weak grid system. It solves the technical problem that existing methods for judging single-phase overvoltage in power systems cannot quantify influencing factors and parameter change trends, resulting in low accuracy of single-phase overvoltage judgment in power systems.

[0067] Example 1:

[0068] Figure 1 This is a flowchart illustrating the steps of the overvoltage risk assessment method for non-full-phase operation of a new energy source connected to a weak grid system, as described in an embodiment of this application. Figure 2 This is a topology diagram illustrating a single-phase fault in a transmission line of a renewable energy-connected weak grid system, as described in the overvoltage risk assessment method for non-full-phase operation of a renewable energy-connected weak grid system according to an embodiment of this application. Figure 3 This is a schematic diagram of the equivalent circuit for a single-phase fault in a transmission line of a new energy access weak grid system, as described in the overvoltage risk assessment method for non-full-phase operation of a new energy access weak grid system according to an embodiment of this application.

[0069] like Figure 1 As shown in the figure, this application provides an overvoltage risk assessment method for non-full-phase operation of a new energy source connected to a weak grid system, including the following steps:

[0070] S1. Obtain positive and negative sequence electrical quantity data of the new energy access weak grid system, and obtain the voltage source, grid-connected equivalent impedance, series equivalent impedance and non-full-phase operation line impedance of the transmission line in the new energy access weak grid system when a single-phase fault occurs.

[0071] It should be noted that, given the positive sequence current component I along the d-axis of the new energy source connected to the weak grid system...d In step S1, n electrical quantity data points representing the positive and negative sequences of the renewable energy-connected weak grid system can be acquired at equal numerical intervals to provide data for subsequent calculations of the actual positive and negative sequence voltages. Additionally, data on voltage sources, grid-connected equivalent impedances, series equivalent impedances, and impedances of non-full-phase operation lines experiencing single-phase faults in the renewable energy-connected weak grid system can be acquired to provide data for subsequent steps. In this embodiment, the electrical quantity data includes n d-axis positive sequence current components, n d-axis negative sequence current components, n positive sequence voltage components, positive sequence reactive power injection coefficients, negative sequence reactive power injection coefficients, n negative sequence voltage components, and rated values ​​of the positive sequence voltage components. Here, "renewable energy-connected weak grid system" refers to a power system where renewable energy is connected to a weak grid. The data points are acquired at equal numerical intervals between 0 and 1; these intervals can also be set according to requirements and are not specifically limited here. n is a natural number greater than 0.

[0072] In the embodiments of this application, such as Figure 2 and Figure 3 As shown, a single-phase fault occurs on the transmission line of the renewable energy grid connected to a weak grid at point O. Subsequently, a single-phase disconnection occurs on the transmission line of AOB, and the renewable energy grid connected to the weak grid is in a non-full-phase operation state. Point B is closer to the photovoltaic side, and point A is closer to the grid side. The equivalent impedance of the line from the renewable energy grid connection point to the disconnection point is measured and taken as the grid-connected equivalent impedance Z. s The circuit from the external power grid to the point of disconnection is equivalent to a voltage source U. g With series equivalent impedance Z G The impedance of a series, non-full-phase operating line is denoted as Z. qk .

[0073] S2. Based on each electrical quantity data, calculate n positive sequence current vectors and n negative sequence current vectors.

[0074] It should be noted that in step S2, n positive-sequence current vectors and n negative-sequence current vectors are determined based on the electrical quantity data obtained in step S1, providing data for subsequent steps. For example, n positive-sequence current vectors are obtained by calculating based on the rated value of the positive-sequence voltage component, each positive-sequence voltage component, the positive-sequence reactive power injection coefficient, and each d-axis positive-sequence current component; n negative-sequence current vectors are obtained by calculating based on each d-axis negative-sequence current component, the negative-sequence reactive power injection coefficient, and each negative-sequence voltage component.

[0075] S3. Based on the voltage source, grid equivalent impedance, series equivalent impedance, non-full-phase line impedance, each positive sequence current vector and each negative sequence current vector, calculate to obtain n positive sequence port voltage vectors and n negative sequence port voltage vectors.

[0076] It should be noted that in step S3, the corresponding n positive sequence port voltage vectors and n negative sequence port voltage vectors are calculated based on the n positive sequence current vectors and n negative sequence current vectors obtained in step S2, as well as the voltage source, grid equivalent impedance, series equivalent impedance, and non-full-phase operating line impedance obtained in step S1, so as to provide data for subsequent steps.

[0077] S4. Calculate the actual positive sequence voltage and actual negative sequence voltage based on the rated values ​​of the positive sequence voltage components, the voltage vector of each positive sequence port, and the voltage vector of each negative sequence port; calculate the maximum value of the single-phase voltage based on the actual positive sequence voltage, the actual negative sequence voltage, and the rated values ​​of the positive sequence voltage components.

[0078] It should be noted that in step S4, the actual positive sequence voltage and actual negative sequence voltage are first calculated based on the rated values ​​of the positive sequence voltage components obtained in step S1 and the n positive sequence port voltage vectors and n negative sequence port voltage vectors calculated in step S3. Then, the maximum value of the single-phase voltage is calculated based on the actual positive sequence voltage, the actual negative sequence voltage and the rated values ​​of the positive sequence voltage components, so as to provide data for subsequent judgment on whether there is an overvoltage risk when the new energy access weak grid system operates in a non-full-phase operation state.

[0079] In this embodiment, the maximum single-phase voltage is calculated using the single-phase voltage formula based on the actual positive-sequence voltage, the actual negative-sequence voltage, and the rated values ​​of the positive-sequence voltage component. The single-phase voltage formula is:

[0080]

[0081] In the formula, U vsc_pha The maximum value of a single-phase voltage, ΔU vsc+ For the actual positive sequence voltage, ΔU vsc- U is the actual negative sequence voltage. n This is the rated value for the positive sequence voltage component.

[0082] S5. Determine whether there is an overvoltage risk when the new energy grid is connected to the weak grid system in a non-full-phase operation state based on the maximum value of the single-phase voltage.

[0083] It should be noted that in step S5, the maximum value of the single-phase voltage calculated in step S4 is used to determine whether there is an overvoltage risk in the new energy access weak grid system under non-full-phase operation, thereby realizing the assessment of the overvoltage risk of the new energy access weak grid system under non-full-phase operation.

[0084] In this embodiment, the overvoltage risk assessment method for non-full-phase operation of a new energy grid connected to a weak grid system processes the obtained electrical quantity data, voltage source, grid-connected equivalent impedance, series equivalent impedance, and non-full-phase operation line impedance to obtain the maximum single-phase voltage value, quantifies the overvoltage risk data in the new energy grid connected to the weak grid system, and assesses the overvoltage risk of the new energy grid connected to the weak grid system under non-full-phase operation based on the maximum single-phase voltage value, thereby improving the accuracy and precision of assessing the overvoltage risk of the new energy grid connected to the weak grid system under non-full-phase operation.

[0085] This application provides a method for assessing overvoltage risk in a non-full-phase operation of a renewable energy-connected weak grid system. The method includes acquiring positive-sequence and negative-sequence electrical quantity data of the renewable energy-connected weak grid system, as well as acquiring the voltage source, grid-connected equivalent impedance, series equivalent impedance, and non-full-phase operation line impedance of the transmission line in the renewable energy-connected weak grid system during a single-phase fault. The electrical quantity data includes n d-axis positive-sequence current components, n d-axis negative-sequence current components, n positive-sequence voltage components, positive-sequence reactive power injection coefficient, negative-sequence reactive power injection coefficient, n negative-sequence voltage components, and rated values ​​of the positive-sequence voltage components. Based on each electrical quantity data, n positive-sequence current vectors are calculated. n negative-sequence current vectors are used. Based on the voltage source, grid-connected equivalent impedance, series equivalent impedance, non-full-phase operation line impedance, each positive-sequence current vector, and each negative-sequence current vector, n positive-sequence port voltage vectors and n negative-sequence port voltage vectors are calculated. Based on the rated values ​​of the positive-sequence voltage components, each positive-sequence port voltage vector, and each negative-sequence port voltage vector, the actual positive-sequence voltage and actual negative-sequence voltage are calculated. Based on the actual positive-sequence voltage, actual negative-sequence voltage, and the rated values ​​of the positive-sequence voltage components, the maximum single-phase voltage is calculated. Based on the maximum single-phase voltage, it is determined whether there is an overvoltage risk in the non-full-phase operation of the renewable energy-connected weak grid system. This overvoltage risk assessment method for non-full-phase operation of renewable energy-connected weak grid systems quantifies the overvoltage risk data in renewable energy-connected weak grid systems, realizes the assessment of overvoltage risk in non-full-phase operation of renewable energy-connected weak grid systems, improves the accuracy and precision of the assessment of overvoltage risk in non-full-phase operation of renewable energy-connected weak grid systems, and solves the technical problem that the existing single-phase overvoltage judgment methods of power systems cannot quantify the influencing factors and parameter change trends, resulting in low accuracy of single-phase overvoltage judgment in power systems.

[0086] In one embodiment of this application, calculating n positive-sequence current vectors and n negative-sequence current vectors based on each electrical quantity data includes:

[0087] Based on the rated values ​​of the positive sequence voltage components, each positive sequence voltage component, the positive sequence reactive power injection coefficient, and each d-axis positive sequence current component, n positive sequence current vectors are obtained.

[0088] Based on each d-axis negative sequence current component, negative sequence reactive power injection coefficient, and each negative sequence voltage component, n negative sequence current vectors are obtained.

[0089] It should be noted that, in the process of calculating the positive sequence current vector, the difference between each positive sequence voltage component and its rated value is first used as the corresponding positive sequence voltage component deviation ΔU. vsc_test+ Then, based on the positive sequence voltage component deviation ΔU vsc_test+ Positive sequence reactive power injection coefficient k q+ and d-axis positive sequence current component I d+ The corresponding positive sequence current vector I is obtained by using the positive sequence current vector formula. vsc_test+ In calculating the negative sequence current vector, the negative sequence voltage component is first treated as the negative sequence voltage component deviation ΔU. vsc_test- Then, based on the negative sequence voltage component deviation ΔU vsc_test- Negative-order reactive power injection coefficient k q- and d-axis negative sequence current component I d- The corresponding negative sequence current vector I is obtained by calculating using the negative sequence current vector formula. vsc_test- .

[0090] In this embodiment, the positive sequence current vector formula is:

[0091]

[0092] The formula for the negative sequence current vector is:

[0093]

[0094] In the formula, j is the imaginary unit, and i is the i-th data. .

[0095] In one embodiment of this application, n positive-sequence port voltage vectors and n negative-sequence port voltage vectors are calculated based on the voltage source, grid equivalent impedance, series equivalent impedance, non-full-phase operating line impedance, each positive-sequence current vector, and each negative-sequence current vector, including:

[0096] The negative sequence impedance variable is obtained by calculating the zero-sequence impedance of the non-full-phase operating line impedance, the grid-connected equivalent impedance, and the series equivalent impedance.

[0097] The positive sequence impedance variable is obtained by calculating the zero-sequence impedance of the non-full-phase operating line impedance, the positive sequence impedance of the grid-connected equivalent impedance, the zero-sequence impedance of the series equivalent impedance, and the positive sequence impedance of the series equivalent impedance.

[0098] Based on the negative sequence impedance variable, the positive sequence impedance variable, each positive sequence current vector, and each negative sequence current vector, n negative sequence port voltage vectors are obtained.

[0099] Based on the voltage source, negative sequence impedance variable, positive sequence impedance variable, each positive sequence current vector, and each negative sequence current vector, n positive sequence port voltage vectors are obtained.

[0100] It should be noted that, as Figure 3 As shown, based on the impedance Z of the non-full-phase operating line... qk The zero-sequence impedance Z of the grid-connected equivalent impedance s（0） The zero-sequence impedance Z of the series equivalent impedance G（0） The negative sequence impedance variable Z is obtained by using the formula for negative sequence impedance variable. O2 Based on the impedance Z of the non-full-phase operating line. qk The zero-sequence impedance Z of the grid-connected equivalent impedance s（0） The positive sequence impedance Z of the grid-connected equivalent impedance s（1） The zero-sequence impedance Z of the series equivalent impedance G（0） The positive sequence impedance Z of the series equivalent impedance G（1） The positive sequence impedance variable Z is obtained by using the formula for positive sequence impedance variable. O1 . According to the negative sequence impedance variable Z O2 Positive sequence impedance variable Z O1 Each positive sequence current vector I vsc_test+i and each negative sequence current vector I vsc_test-i The corresponding negative-sequence port voltage vector U is calculated using the negative-sequence voltage vector formula. vsc_test-i According to voltage source U g Negative sequence impedance variable Z O2 Positive sequence impedance variable Z O1 Each positive sequence current vector I vsc_test+i and each negative sequence current vector I vsc_test-i The corresponding positive sequence port voltage vector U is calculated using the positive sequence voltage vector formula. vsc_test+i '.

[0101] In this embodiment, the formula for the negative sequence impedance variable is:

[0102]

[0103] The formula for positive sequence impedance variable is:

[0104]

[0105] The formula for the negative sequence voltage vector is:

[0106]

[0107] The formula for the positive sequence voltage vector is:

[0108]

[0109] In the formula, j is the imaginary unit, and the subscript i is the i-th data.

[0110] In one embodiment of this application, the actual positive-sequence voltage and the actual negative-sequence voltage are calculated based on the rated values ​​of the positive-sequence voltage components, the voltage vector of each positive-sequence port, and the voltage vector of each negative-sequence port, including:

[0111] Based on the rated values ​​of the positive sequence voltage components and the voltage vector of each positive sequence port, n positive sequence voltage vector deviations are obtained; each negative sequence port voltage vector is taken as the negative sequence voltage vector deviation, resulting in n negative sequence voltage vector deviations.

[0112] Based on the deviation of each positive-sequence voltage vector, n positive-sequence voltage amplitudes are obtained; based on the deviation of each negative-sequence voltage vector, n negative-sequence voltage amplitudes are obtained.

[0113] In the same coordinate system, curves are plotted based on the deviations of n positive-sequence voltage vectors and the magnitudes of n positive-sequence voltages to obtain the positive-sequence deviation curve and the positive-sequence magnitude curve; in the same coordinate system, curves are plotted based on the deviations of n negative-sequence voltage vectors and the magnitudes of n negative-sequence voltages to obtain the negative-sequence deviation curve and the negative-sequence magnitude curve.

[0114] The voltage at the intersection of the positive sequence deviation curve and the positive sequence amplitude curve is taken as the actual positive sequence voltage; the voltage at the intersection of the negative sequence deviation curve and the negative sequence amplitude curve is taken as the actual negative sequence voltage.

[0115] It should be noted that the positive sequence voltage vector deviation ΔU vsc_test+i '=U vsc_test+i '-U set In the formula, U set This represents the rated value for the positive sequence voltage component. The negative sequence port voltage vector U... vsc_test-i 'As negative sequence voltage vector deviation ΔU vsc_test-i ', that is U vsc_test-i '=△U vsc_test-i According to the positive sequence voltage vector deviation ΔU vsc_test+i 'and negative sequence voltage vector deviation △U vsc_test-i The corresponding positive sequence voltage amplitude ΔU is obtained by calculating using the voltage amplitude formula. vsc_cal+i and negative sequence voltage amplitude ΔU vsc_cal-i The formula for voltage amplitude is:

[0116]

[0117] Among them, the deviation ΔU of each positive sequence voltage vector vsc_test+i 'and the corresponding positive sequence voltage amplitude ΔU vsc_cal+iThe magnitudes are compared one by one, and the deviation ΔU of each negative sequence voltage vector is also compared. vsc_test-i 'and the corresponding negative sequence voltage amplitude ΔU vsc_cal-i By comparing the magnitudes one by one and finding the equal values, the actual positive sequence voltage ΔU is obtained. vsc+ and the actual negative sequence voltage ΔUv sc- .

[0118] In one embodiment of this application, determining whether there is an overvoltage risk in a new energy grid system operating under non-full-phase conditions based on the maximum single-phase voltage value includes:

[0119] If the maximum value of a single-phase voltage is greater than the overvoltage setting value of the phase voltage, it is determined that the new energy connected to the weak grid system is in a non-full-phase operation state and there is an overvoltage risk.

[0120] If the maximum value of a single-phase voltage is not greater than the overvoltage setting value of the phase voltage, it is determined that there is no overvoltage risk when the new energy is connected to the weak grid system in a non-full-phase operation state;

[0121] The obtained phase voltage overvoltage setting values ​​include:

[0122] Obtain the safety factor;

[0123] The phase voltage overvoltage threshold is calculated based on the rated value of the positive sequence voltage component.

[0124] The phase voltage overvoltage setting value is obtained by calculating the phase voltage overvoltage threshold and safety factor.

[0125] It should be noted that the rated value of the positive sequence voltage component U is known. n The overvoltage is typically 1.3U. n The phase voltage overvoltage threshold is U vsc_th =sqrt(2 / 3)*1.3U n . WhenU vsc_pha >α*U vsc_th When new energy sources are connected to a weak power grid system, there is a risk of overvoltage when the system is in a non-full-phase operation state. α is a safety factor, which can be taken as 0.8~0.9.

[0126] Example 2:

[0127] Figure 4 This is a schematic diagram of the overvoltage risk assessment device for non-full-phase operation of a new energy access weak grid system as described in the embodiments of this application.

[0128] like Figure 4As shown, this application embodiment provides an overvoltage risk assessment device for non-full-phase operation of a new energy access weak grid system, including a data acquisition module 10, a current vector calculation module 20, a voltage vector calculation module 30, a single-phase voltage calculation module 40, and a risk assessment module 50.

[0129] The data acquisition module 10 is used to acquire positive and negative sequence electrical quantity data of the new energy access weak grid system, as well as the voltage source, grid-connected equivalent impedance, series equivalent impedance and non-full-phase operation line impedance of the transmission line in the new energy access weak grid system when a single-phase fault occurs; the electrical quantity data includes n d-axis positive sequence current components, n d-axis negative sequence current components, n positive sequence voltage components, positive sequence reactive power injection coefficient, negative sequence reactive power injection coefficient, n negative sequence voltage components and positive sequence voltage component rated values;

[0130] The current vector calculation module 20 is used to calculate n positive-sequence current vectors and n negative-sequence current vectors based on each electrical quantity data;

[0131] The voltage vector calculation module 30 is used to calculate n positive sequence port voltage vectors and n negative sequence port voltage vectors based on the voltage source, grid equivalent impedance, series equivalent impedance, non-full-phase operation line impedance, each positive sequence current vector and each negative sequence current vector;

[0132] The single-phase voltage calculation module 40 is used to calculate the actual positive-sequence voltage and the actual negative-sequence voltage based on the rated values ​​of the positive-sequence voltage components, the voltage vector of each positive-sequence port, and the voltage vector of each negative-sequence port; and to calculate the maximum value of the single-phase voltage based on the actual positive-sequence voltage, the actual negative-sequence voltage, and the rated values ​​of the positive-sequence voltage components.

[0133] Risk assessment module 50 is used to determine whether there is an overvoltage risk when the new energy access to the weak grid system is in a non-full-phase operation state based on the maximum value of the single-phase voltage.

[0134] It should be noted that the content of the modules in the device of Embodiment 2 has already been described in the steps of the method of Embodiment 1. Therefore, the content of the overvoltage risk assessment device module for non-full-phase operation of a renewable energy-connected weak grid system will not be repeated in this embodiment. In this embodiment, the overvoltage risk assessment device for non-full-phase operation of a renewable energy-connected weak grid system quantifies the overvoltage risk data in the renewable energy-connected weak grid system through a data acquisition module, a current vector calculation module, a voltage vector calculation module, a single-phase voltage calculation module, and a risk assessment module. This enables the assessment of overvoltage risk in the non-full-phase operation state of the renewable energy-connected weak grid system, improving the accuracy and precision of the assessment.

[0135] In this embodiment of the application, the current vector calculation module 20 includes a positive sequence current calculation submodule and a negative sequence current calculation submodule;

[0136] The positive sequence current calculation submodule is used to calculate n positive sequence current vectors based on the rated value of the positive sequence voltage component, each positive sequence voltage component, the positive sequence reactive power injection coefficient, and each d-axis positive sequence current component.

[0137] The negative sequence current calculation submodule is used to calculate n negative sequence current vectors based on each d-axis negative sequence current component, negative sequence reactive power injection coefficient, and each negative sequence voltage component.

[0138] In this embodiment, the voltage vector calculation module 30 includes a positive sequence variable calculation submodule, a negative sequence variable calculation submodule, a positive sequence voltage calculation submodule, and a negative sequence voltage calculation submodule;

[0139] The positive sequence variable calculation submodule is used to calculate and obtain the positive sequence impedance variable based on the line impedance of non-full-phase operation, the zero sequence impedance of grid-connected equivalent impedance, the positive sequence impedance of grid-connected equivalent impedance, the zero sequence impedance of series equivalent impedance, and the positive sequence impedance of series equivalent impedance.

[0140] The negative sequence variable calculation submodule is used to calculate the negative sequence impedance variable based on the zero sequence impedance of the non-full-phase operating line impedance, the grid-connected equivalent impedance, and the series equivalent impedance.

[0141] The positive sequence voltage calculation submodule is used to calculate n positive sequence port voltage vectors based on the voltage source, negative sequence impedance variable, positive sequence impedance variable, each positive sequence current vector and each negative sequence current vector.

[0142] The negative sequence voltage calculation submodule is used to calculate n negative sequence port voltage vectors based on the negative sequence impedance variable, the positive sequence impedance variable, each positive sequence current vector, and each negative sequence current vector.

[0143] In this embodiment, the single-phase voltage calculation module 40 includes a deviation calculation submodule, an amplitude calculation submodule, a curve plotting submodule, and an actual voltage determination submodule;

[0144] The deviation calculation submodule is used to calculate n positive sequence voltage vector deviations based on the rated values ​​of the positive sequence voltage components and the voltage vector of each positive sequence port; and to calculate n negative sequence voltage vector deviations by taking each negative sequence port voltage vector as the negative sequence voltage vector deviation.

[0145] The amplitude calculation submodule is used to calculate n positive-sequence voltage amplitudes based on the deviation of each positive-sequence voltage vector; and to calculate n negative-sequence voltage amplitudes based on the deviation of each negative-sequence voltage vector.

[0146] The curve plotting submodule is used to plot curves based on n positive-sequence voltage vector deviations and n positive-sequence voltage amplitudes in the same coordinate system, obtaining positive-sequence deviation curves and positive-sequence amplitude curves; and to plot curves based on n negative-sequence voltage vector deviations and n negative-sequence voltage amplitudes in the same coordinate system, obtaining negative-sequence deviation curves and negative-sequence amplitude curves.

[0147] The actual voltage determination submodule is used to take the voltage at the intersection point between the positive sequence deviation curve and the positive sequence amplitude curve as the actual positive sequence voltage; and to take the voltage at the intersection point between the negative sequence deviation curve and the negative sequence amplitude curve as the actual negative sequence voltage.

[0148] Example 3:

[0149] Figure 5 This is a schematic diagram of the terminal device described in an embodiment of this application.

[0150] like Figure 5 As shown, this application provides a terminal device, including a processor and a memory;

[0151] Memory is used to store program code and transfer the program code to the processor;

[0152] The processor is used to execute the above-mentioned overvoltage risk assessment method for non-full-phase operation of new energy access weak grid system according to the instructions in the program code.

[0153] It should be noted that the processor is used to execute the steps in the above-described embodiment of an overvoltage risk assessment method for non-full-phase operation of a new energy access weak grid system according to the instructions in the program code. Alternatively, when the processor executes the computer program, it implements the functions of each module / unit in the above-described system / device embodiments.

[0154] For example, a computer program can be divided into one or more modules / units, one or more of which are stored in memory and executed by a processor to complete this application. One or more modules / units can be a series of computer program instruction segments capable of performing a specific function, which describe the execution process of the computer program in a terminal device.

[0155] Terminal devices can be computing devices such as desktop computers, laptops, handheld computers, and cloud servers. Terminal devices may include, but are not limited to, processors and memory. Those skilled in the art will understand that this does not constitute a limitation on the terminal device, which may include more or fewer components than illustrated, or combinations of certain components, or different components. For example, a terminal device may also include input / output devices, network access devices, buses, etc.

[0156] The processor can be a Central Processing Unit (CPU), or other general-purpose processors, digital signal processors (DSPs), application-specific integrated circuits (ASICs), field-programmable gate arrays (FPGAs), or other programmable logic devices, discrete gate or transistor logic devices, discrete hardware components, etc. A general-purpose processor can be a microprocessor or any conventional processor.

[0157] Memory can be an internal storage unit of a terminal device, such as a hard drive or RAM. Memory can also be an external storage device, such as a plug-in hard drive, SmartMedia Card (SMC), Secure Digital (SD) card, or Flash Card. Furthermore, memory can include both internal and external storage units. Memory is used to store computer programs and other programs and data required by the terminal device. Memory can also be used to temporarily store data that has been output or will be output.

[0158] Those skilled in the art will clearly understand that, for the sake of convenience and brevity, the specific working processes of the systems, devices, and units described above can be referred to the corresponding processes in the foregoing method embodiments, and will not be repeated here.

[0159] In the several embodiments provided in this application, it should be understood that the disclosed systems, apparatuses, and methods can be implemented in other ways. For example, the apparatus embodiments described above are merely illustrative; for instance, the division of units is only a logical functional division, and in actual implementation, there may be other division methods. For example, multiple units or components may be combined or integrated into another system, or some features may be ignored or not executed. Furthermore, the coupling or direct coupling or communication connection shown or discussed may be an indirect coupling or communication connection between apparatuses or units through some interfaces, and may be electrical, mechanical, or other forms.

[0160] The units described as separate components may or may not be physically separate. 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 the units can be selected to achieve the purpose of this embodiment according to actual needs.

[0161] Furthermore, the functional units in the various embodiments of the present invention can be integrated into one processing unit, or each unit can exist physically separately, or two or more units can be integrated into one unit. The integrated unit can be implemented in hardware or as a software functional unit.

[0162] If the integrated unit is implemented as 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, in essence, 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. This computer software product is stored in a storage medium and includes several instructions to cause a computer device (which may be a personal computer, server, or network device, etc.) to execute all or part of the steps of the methods described in the various embodiments of the present invention. The aforementioned storage medium includes various media capable of storing program code, such as USB flash drives, portable hard drives, read-only memory (ROM), random access memory (RAM), magnetic disks, or optical disks.

[0163] The above-described embodiments are only used to illustrate the technical solutions of this application, and are not intended to limit them. Although this application has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of this application.

Claims

1. A method for assessing overvoltage risk in a weak grid system with new energy sources operating in non-full-phase mode, characterized in that, Includes the following steps: Obtain positive and negative sequence electrical quantity data of n new energy access weak grid systems, and obtain the voltage source, grid-connected equivalent impedance, series equivalent impedance and non-full-phase operation line impedance of the transmission line in the new energy access weak grid system when a single-phase fault occurs; Based on each of the electrical quantity data, n positive sequence current vectors and n negative sequence current vectors are calculated; Based on the voltage source, the grid-connected equivalent impedance, the series equivalent impedance, the non-full-phase operating line impedance, each of the positive-sequence current vectors, and each of the negative-sequence current vectors, n positive-sequence port voltage vectors and n negative-sequence port voltage vectors are calculated. The actual positive-sequence voltage and the actual negative-sequence voltage are calculated based on the rated values ​​of the positive-sequence voltage components, the voltage vector of each positive-sequence port, and the voltage vector of each negative-sequence port. The maximum value of the single-phase voltage is calculated based on the actual positive-sequence voltage, the actual negative-sequence voltage, and the rated value of the positive-sequence voltage component. Based on the maximum value of the single-phase voltage, it can be determined whether there is an overvoltage risk when the new energy access to the weak grid system is in a non-full-phase operation state.

2. The overvoltage risk assessment method for non-full-phase operation of a new energy grid connected to a weak power grid system according to claim 1, characterized in that, The electrical quantity data includes the d-axis positive sequence current component, the d-axis negative sequence current component, the positive sequence voltage component, the positive sequence reactive power injection coefficient, the negative sequence reactive power injection coefficient, the negative sequence voltage component, and the rated value of the positive sequence voltage component. Based on each of the aforementioned electrical quantity data, n positive-sequence current vectors and n negative-sequence current vectors are calculated, including: Based on the rated value of the positive sequence voltage component, each of the positive sequence voltage components, the positive sequence reactive power injection coefficient, and each of the d-axis positive sequence current components, n positive sequence current vectors are obtained; Based on each of the d-axis negative sequence current components, the negative sequence reactive power injection coefficient, and each of the negative sequence voltage components, n negative sequence current vectors are obtained.

3. The overvoltage risk assessment method for non-full-phase operation of a new energy grid connected to a weak power grid according to claim 1, characterized in that, Based on the voltage source, the grid-connected equivalent impedance, the series equivalent impedance, the non-full-phase operating line impedance, each of the positive-sequence current vectors, and each of the negative-sequence current vectors, n positive-sequence port voltage vectors and n negative-sequence port voltage vectors are calculated, including: The negative sequence impedance variable is calculated based on the non-full-phase operating line impedance, the zero-sequence impedance of the grid-connected equivalent impedance, and the zero-sequence impedance of the series equivalent impedance. The positive sequence impedance variable is calculated based on the non-full-phase operating line impedance, the zero-sequence impedance of the grid-connected equivalent impedance, the positive sequence impedance of the grid-connected equivalent impedance, the zero-sequence impedance of the series equivalent impedance, and the positive sequence impedance of the series equivalent impedance. Based on the negative sequence impedance variable, the positive sequence impedance variable, each positive sequence current vector, and each negative sequence current vector, n negative sequence port voltage vectors are calculated; Based on the voltage source, the negative sequence impedance variable, the positive sequence impedance variable, each positive sequence current vector, and each negative sequence current vector, n positive sequence port voltage vectors are obtained.

4. The overvoltage risk assessment method for non-full-phase operation of a new energy grid connected to a weak power grid according to claim 1, characterized in that, The actual positive-sequence voltage and actual negative-sequence voltage are calculated based on the rated values ​​of the positive-sequence voltage components, each positive-sequence port voltage vector, and each negative-sequence port voltage vector, including: Based on the rated values ​​of the positive sequence voltage components and each positive sequence port voltage vector, n positive sequence voltage vector deviations are calculated; each negative sequence port voltage vector is used as a negative sequence voltage vector deviation to obtain n negative sequence voltage vector deviations. Based on the deviation of each positive-sequence voltage vector, n positive-sequence voltage amplitudes are obtained; based on the deviation of each negative-sequence voltage vector, n negative-sequence voltage amplitudes are obtained. In the same coordinate system, curves are plotted based on the n positive sequence voltage vector deviations and the n positive sequence voltage amplitudes to obtain the positive sequence deviation curve and the positive sequence amplitude curve; in the same coordinate system, curves are plotted based on the n negative sequence voltage vector deviations and the n negative sequence voltage amplitudes to obtain the negative sequence deviation curve and the negative sequence amplitude curve. The voltage at the intersection point between the positive sequence deviation curve and the positive sequence amplitude curve is taken as the actual positive sequence voltage; the voltage at the intersection point between the negative sequence deviation curve and the negative sequence amplitude curve is taken as the actual negative sequence voltage.

5. The overvoltage risk assessment method for non-full-phase operation of a new energy source connected to a weak grid system according to any one of claims 1-4, characterized in that, Determining whether there is an overvoltage risk in the new energy grid connection system under non-full-phase operation based on the maximum single-phase voltage includes: If the maximum value of the single-phase voltage is greater than the phase voltage overvoltage setting value, it is determined that the new energy access to the weak grid system is in a non-full-phase operation state and there is an overvoltage risk. If the maximum value of the single-phase voltage is not greater than the phase voltage overvoltage setting value, it is determined that the new energy access to the weak grid system is in a non-full-phase operation state and there is no risk of overvoltage. Obtaining the phase voltage overvoltage setting value includes: Obtain the safety factor; The phase voltage overvoltage threshold is calculated based on the rated value of the positive sequence voltage component. The phase voltage overvoltage setting value is calculated based on the phase voltage overvoltage threshold and the safety factor.

6. An overvoltage risk assessment device for non-full-phase operation of a new energy source connected to a weak power grid system, characterized in that, include: The system includes a data acquisition module, a current vector calculation module, a voltage vector calculation module, a single-phase voltage calculation module, and a risk assessment module. The data acquisition module is used to acquire positive and negative sequence electrical quantity data of the new energy access weak grid system, as well as the voltage source, grid-connected equivalent impedance, series equivalent impedance and non-full-phase operation line impedance of the transmission line in the new energy access weak grid system when a single-phase fault occurs. The current vector calculation module is used to calculate n positive-sequence current vectors and n negative-sequence current vectors based on each electrical quantity data. The voltage vector calculation module is used to calculate n positive-sequence port voltage vectors and n negative-sequence port voltage vectors based on the voltage source, the grid-connected equivalent impedance, the series equivalent impedance, the non-full-phase operating line impedance, each positive-sequence current vector, and each negative-sequence current vector. The single-phase voltage calculation module is used to calculate the actual positive-sequence voltage and the actual negative-sequence voltage based on the rated value of the positive-sequence voltage component, the voltage vector of each positive-sequence port, and the voltage vector of each negative-sequence port. The maximum value of the single-phase voltage is calculated based on the actual positive-sequence voltage, the actual negative-sequence voltage, and the rated value of the positive-sequence voltage component. The risk assessment module is used to determine whether there is an overvoltage risk when the new energy access to the weak grid system is in a non-full-phase operation state based on the maximum value of the single-phase voltage.

7. The overvoltage risk assessment device for non-full-phase operation of a new energy grid connected to a weak power grid according to claim 6, characterized in that, The electrical quantity data includes n d-axis positive sequence current components, n d-axis negative sequence current components, n positive sequence voltage components, positive sequence reactive power injection coefficient, negative sequence reactive power injection coefficient, n negative sequence voltage components, and rated values ​​of positive sequence voltage components. The current vector calculation module includes a positive sequence current calculation submodule and a negative sequence current calculation submodule; The positive sequence current calculation submodule is used to calculate n positive sequence current vectors based on the rated value of the positive sequence voltage component, each of the positive sequence voltage components, the positive sequence reactive power injection coefficient, and each of the d-axis positive sequence current components. The negative sequence current calculation submodule is used to calculate n negative sequence current vectors based on each of the d-axis negative sequence current components, the negative sequence reactive power injection coefficient, and each of the negative sequence voltage components.

8. The overvoltage risk assessment device for non-full-phase operation of a new energy grid connected to a weak power grid according to claim 6, characterized in that, The voltage vector calculation module includes a positive sequence variable calculation submodule, a negative sequence variable calculation submodule, a positive sequence voltage calculation submodule, and a negative sequence voltage calculation submodule; The positive sequence variable calculation submodule is used to calculate and obtain the positive sequence impedance variable based on the non-full-phase operating line impedance, the zero sequence impedance of the grid-connected equivalent impedance, the positive sequence impedance of the grid-connected equivalent impedance, the zero sequence impedance of the series equivalent impedance, and the positive sequence impedance of the series equivalent impedance. The negative sequence variable calculation submodule is used to calculate and obtain the negative sequence impedance variable based on the impedance of the non-full-phase operating line, the zero sequence impedance of the grid-connected equivalent impedance, and the zero sequence impedance of the series equivalent impedance. The positive-sequence voltage calculation submodule is used to calculate n positive-sequence port voltage vectors based on the voltage source, the negative-sequence impedance variable, the positive-sequence impedance variable, each positive-sequence current vector, and each negative-sequence current vector. The negative sequence voltage calculation submodule is used to calculate n negative sequence port voltage vectors based on the negative sequence impedance variable, the positive sequence impedance variable, each positive sequence current vector, and each negative sequence current vector.

9. The overvoltage risk assessment device for non-full-phase operation of a new energy grid connected to a weak power grid according to claim 6, characterized in that, The single-phase voltage calculation module includes a deviation calculation submodule, an amplitude calculation submodule, a curve plotting submodule, and an actual voltage determination submodule; The deviation calculation submodule is used to calculate n positive sequence voltage vector deviations based on the rated values ​​of the positive sequence voltage components and each positive sequence port voltage vector; and to obtain n negative sequence voltage vector deviations by taking each negative sequence port voltage vector as a negative sequence voltage vector deviation. The amplitude calculation submodule is used to calculate n positive sequence voltage amplitudes based on each positive sequence voltage vector deviation. Based on the deviation of each negative sequence voltage vector, n negative sequence voltage amplitudes are obtained; The curve plotting submodule is used to plot curves based on the n positive sequence voltage vector deviations and the n positive sequence voltage amplitudes in the same coordinate system, thereby obtaining the positive sequence deviation curve and the positive sequence amplitude curve. In the same coordinate system, curves are plotted based on the n negative sequence voltage vector deviations and the n negative sequence voltage amplitudes to obtain the negative sequence deviation curve and the negative sequence amplitude curve; The actual voltage determination submodule is used to take the voltage at the intersection point between the positive sequence deviation curve and the positive sequence amplitude curve as the actual positive sequence voltage. The voltage at the intersection point between the negative sequence deviation curve and the negative sequence amplitude curve is taken as the actual negative sequence voltage.

10. A terminal device, characterized in that, Including the processor and memory; The memory is used to store program code and transmit the program code to the processor; The processor is configured to execute, according to the instructions in the program code, the overvoltage risk assessment method for non-full-phase operation of a new energy access weak grid system as described in any one of claims 1-5.

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