Method and system for power system sending end overvoltage quantification

Abstract

The invention discloses a method and system for power system sending end overvoltage quantification, and belongs to the technical field of power system simulation machine analysis. The method comprises the following steps: acquiring equivalent parameters of a sending end direct current near region of a to-be-analyzed power system; establishing an analysis model based on the equivalent parameters; and constructing a quantitative analysis index, and substituting the quantitative analysis index into the analysis model for solving so as to quantify the sending end overvoltage of the to-be-analyzed power system. According to the method, the influence of new energy output is considered, the overvoltage condition after bipolar locking of the system is effectively estimated and calculated, and the method has good precision under different new energy output proportions.

Description

Technical Field

[0001] The present invention relates to the technical field of power system simulation and analysis, and more specifically, to a method and system for quantifying overvoltage at the sending end of a power system. Background Art

[0002] With the increasing maturity of UHV DC transmission technology in China, new energy sources represented by wind power and photovoltaic power can be efficiently transmitted to load centers.

[0003] However, the converter stations of the externally transmitted DC and various new energy bases are usually located in remote areas, with a large electrical distance from the main grid, and the dynamic reactive power support capacity provided by the grid is weak. When a large power disturbance occurs in the DC, an obvious power frequency temporary overvoltage (abbreviated as overvoltage) phenomenon will occur.

[0004] To ensure the safe and stable operation of the new energy externally transmitted through the DC system, a certain amount of conventional power sources are usually configured in the near area of the DC sending end. However, under different operating modes, the starting and output ratios of the conventional power sources and the new energy power sources are different, and the overvoltage levels will also have certain differences.

[0005] In response to the overvoltage phenomenon caused by a large-capacity DC fault in the DC sending end system, the overvoltage situation after bipolar blocking at the DC sending end can be analyzed from the perspectives of surplus reactive power and short-circuit capacity of the converter bus. Taking the transient voltage rise at the wind turbine terminal as an index, the mechanism and countermeasures for the disconnection of wind power after bipolar blocking of the DC system can also be studied.

[0006] Although the existing analysis methods consider the influencing factors of new energy power sources on temporary overvoltage, they only stay at qualitative analysis and do not give the expression of quantitative calculation, and there is still a certain distance from engineering practical applications. Summary of the Invention

[0007] In view of the above problems, the present invention proposes a method for quantifying overvoltage at the sending end of a power system, including:

[0008] Obtaining the equivalent parameters of the near area of the DC at the sending end of the power system to be analyzed;

[0009] Based on the equivalent parameters, establishing an analysis model;

[0010] Constructing a quantitative analysis index, and substituting the quantitative analysis index into the analysis model for solution to quantify the overvoltage at the sending end of the power system to be analyzed.

[0011] Optionally, the equivalent parameters include:

[0012] Equivalent new energy bus voltage U W , equivalent system bus voltage U S , converter bus steady-state voltage U P, the impedance X between the equivalent new energy busbar and the converter busbar W , the impedance X between the equivalent system busbar and the converter busbar S , the power flow power P flowing from the equivalent new energy busbar to the converter busbar W +jQ W , the power flow power P flowing from the equivalent system busbar to the converter busbar AC +jQ AC , the shunt capacitance branch jQ generated after the π-type equivalent of the line connecting the equivalent system busbar and the converter busbar L , the reactive power of the equivalent filter of the converter busbar is denoted as jQ C , the power P flowing into the converter valve from the DC system DC +jQ DC , the proportion η of the new energy power source output in the DC system RE , then:

[0013] P W =η RE P DC。 (1)

[0014] Optionally, based on the equivalent parameters, an analysis model is established, including:

[0015] After the bipolar blocking fault occurs in the DC, determine the relationship between the reactive power of the filter and the line before and after the bipolar blocking fault in the DC, as follows:

[0016]

[0017] Based on the forward-backward substitution method of power flow calculation, determine the relationship between the converter busbar and the reactive power flowing into the AC system, as follows:

[0018]

[0019] Ignoring the resistance in each transmission line, then P WF =P ACF , determine the relationship between the converter busbar voltage U PF and U S , as follows:

[0020]

[0021] Substitute (4) into (5) to obtain the analytical solution of the quartic equation of U PF , where (3) is approximated as:

[0022]

[0023] If we denote A = Q C +Q L , Simplify (4) to:

[0024]

[0025] If U P ≈ 1, then a quartic equation of U PF is obtained, and (6) can be analytically solved by the root formula, where Then the calculation formula of U PF is as follows:

[0026]

[0027] Substitute the equivalent parameters into (8) to construct an analysis model.

[0028] Optionally, the calculation formula of the quantitative analysis index is as follows:

[0029]

[0030] where k SCR is the quantitative analysis index.

[0031] On the other hand, the present invention also proposes a system for quantifying the sending - end over - voltage of a power system, including:

[0032] An acquisition unit for obtaining the equivalent parameters of the DC near - zone of the sending - end of the power system to be analyzed;

[0033] A modeling unit for establishing an analysis model based on the equivalent parameters;

[0034] A quantification unit for constructing a quantitative analysis index, substituting the quantitative analysis index into the analysis model for solution to quantify the sending - end over - voltage of the power system to be analyzed.

[0035] Optionally, the equivalent parameters include:

[0036] The equivalent new - energy bus voltage U W , the equivalent system bus voltage U S , the converter bus steady - state voltage U P , the impedance X W from the equivalent new - energy bus to the converter bus, the impedance X S from the equivalent system bus to the converter bus, the power flow P W +jQ W flowing from the equivalent new - energy bus to the converter bus, the power flow P AC +jQ AC flowing from the equivalent system bus to the converter bus, the shunt capacitance branch jQ L generated after the π - type equivalent of the line connecting the equivalent system bus and the converter bus, and the reactive power of the equivalent filter of the converter bus is denoted as jQC The power \(P\) flowing into the converter valve of the DC system DC +\(jQ\) DC The output power ratio \(\eta\) of new energy sources in the DC system RE Then:

[0037] \(P\) W =\(\eta\) RE \(P\) DC . (1)

[0038] Optionally, based on the equivalent parameters, an analysis model is established, including:

[0039] After a bipolar blocking fault occurs in the DC system, determine the relationship between the reactive power of the filter and the line before and after the bipolar blocking fault in the DC system, as follows:

[0040]

[0041] Based on the forward-backward substitution method of power flow calculation, determine the relationship between the converter bus and the reactive power flowing into the AC system, as follows:

[0042]

[0043] Ignoring the resistance in each transmission line, then \(P\) WF =\(P\) ACF , determine the relationship between the converter bus voltage \(U\) PF and \(U\) S after the bipolar blocking fault in the DC system, as follows:

[0044]

[0045] Substitute (4) into (5) to obtain the analytical solution of the quartic equation of \(U\) PF , where (3) is approximated as:

[0046]

[0047] If we denote \(A = Q\) C +\(Q\) L , Simplify (4) to:

[0048]

[0049] If \(U\) P ≈1, then a quartic equation of \(U\) PF is obtained, and the analytical solution of (6) can be obtained through the root formula, where, Then the calculation formula of \(U\) PF is as follows:

[0050]

[0051] Substitute the equivalent parameters into (8) to construct an analysis model.

[0052] Optionally, the calculation formula of the quantitative analysis index is as follows:

[0053]

[0054] where k SCR is the quantitative analysis index.

[0055] On the other hand, the present invention also provides a computing device, including: one or more processors;

[0056] The processor is configured to execute one or more programs;

[0057] When the one or more programs are executed by the one or more processors, the method as described above is implemented.

[0058] On the other hand, the present invention also provides a computer-readable storage medium, on which a computer program is stored, and when the computer program is executed, the method as described above is implemented.

[0059] Compared with the prior art, the beneficial effects of the present invention are:

[0060] The present invention provides a method for quantifying the overvoltage at the sending end of a power system, including: obtaining the equivalent parameters of the DC near area at the sending end of the power system to be analyzed; establishing an analysis model based on the equivalent parameters; constructing a quantitative analysis index, and substituting the quantitative analysis index into the analysis model for solution to quantify the overvoltage at the sending end of the power system to be analyzed. Due to considering the influence of new energy output, the present invention effectively estimates and calculates the overvoltage situation after bipolar blocking of the system, and has good accuracy under different new energy output ratios. BRIEF DESCRIPTION OF THE DRAWINGS

[0061] Figure 1 is a flowchart of the method of the present invention;

[0062] Figure 2 is a typical working condition diagram of new energy transmitted through DC in an embodiment of the method of the present invention;

[0063] Figure 3 is a diagram of the power flow situation after a bipolar blocking fault occurs in the new energy transmitted through DC system in an embodiment of the method of the present invention;

[0064] Figure 4 is a diagram of the overvoltage distribution situation in an embodiment of the method of the present invention;

[0065] Figure 5 is a projection diagram in an embodiment of the method of the present invention;

[0066] Figure 6 This is the diagram of the commutation bus voltage after bipolar blocking under different new energy output ratios with different power reduction methods in the method embodiment of the present invention;

[0067] Figure 7 This is the diagram of the commutation bus voltage after bipolar blocking under different new energy output ratios with different unit shutdown methods in the method embodiment of the present invention;

[0068] Figure 8 This is the structure diagram of the system of the present invention. Detailed implementation manners

[0069] Now, the exemplary embodiments of the present invention will be introduced with reference to the accompanying drawings. However, the present invention can be implemented in many different forms and is not limited to the embodiments described herein. These embodiments are provided to disclose the present invention in detail and completely, and to fully convey the scope of the present invention to those skilled in the art. The terms in the exemplary embodiments shown in the drawings are not limitations on the present invention. In the drawings, the same unit / element is denoted by the same reference numeral.

[0070] Unless otherwise specified, the terms (including scientific and technical terms) used herein have the ordinary meaning understood by those skilled in the art. In addition, it can be understood that the terms defined in the commonly used dictionary should be understood as having a meaning consistent with the context of their related fields, and should not be understood as having an idealized or overly formal meaning.

[0071] Embodiment 1:

[0072] The present invention proposes a method for quantifying the overvoltage at the sending end of a power system, as Figure 1 shown, including:

[0073] Step 1, obtaining the equivalent parameters of the DC near area at the sending end of the power system to be analyzed;

[0074] Step 2, establishing an analysis model based on the equivalent parameters;

[0075] Step 3, constructing a quantification analysis index, and substituting the quantification analysis index into the analysis model for solution to quantify the overvoltage at the sending end of the power system to be analyzed.

[0076] Among them, the equivalent parameters include:

[0077] Equivalent new energy bus voltage U W , equivalent system bus voltage U S , commutation bus steady-state voltage U P , impedance X W between the equivalent new energy bus and the commutation bus, and impedance X S, the power flow power P flowing from the equivalent new energy bus to the converter bus W +jQ W , the power flow power P flowing from the equivalent system bus to the converter bus AC +jQ AC , the shunt capacitance branch jQ generated after the π-equivalent of the line connecting the equivalent system bus and the converter bus L , the reactive power of the equivalent filter of the converter bus is denoted as jQ C , the power P flowing from the DC system into the converter valve DC +jQ DC , the output proportion η of the new energy power source in the DC system RE , then:

[0078] P W = η RE P DC . (1)

[0079] Among them, based on the above equivalent parameters, an analysis model is established, including:

[0080] After the bipolar blocking fault occurs in the DC system, determine the relationship between the reactive power of the filter and the line before and after the bipolar blocking fault in the DC system, as follows:

[0081]

[0082] Based on the forward-backward substitution method of power flow calculation, determine the relationship between the converter bus and the reactive power flowing into the AC system, as follows:

[0083]

[0084] Ignoring the resistance in each transmission line, then P WF = P ACF , determine the relationship between the converter bus voltage U PF and U S , as follows:

[0085]

[0086] Substitute (4) into (5) to obtain the analytical solution of the quartic equation of U PF , among which, approximate (3) as:

[0087]

[0088] If it is denoted that A = Q C + Q L , Simplify (4) to:

[0089]

[0090] If U P ≈ 1, a quartic equation of one variable about U PF is obtained, and equation (6) can be analytically solved by the root formula, where Then the calculation formula of U PF is as follows:

[0091]

[0092] Substitute the equivalent parameters into (8) to construct an analysis model.

[0093] Among them, the calculation formula of the quantitative analysis index is as follows:

[0094]

[0095] Among them, k SCR is the quantitative analysis index.

[0096] The present invention will be further described below with reference to examples:

[0097] The example steps include:

[0098] Step1: Based on Figure 2 , obtain the sending - end DC near - zone of the power system to be analyzed and its corresponding equivalent parameters. Among them, the equivalent new - energy bus voltage is U W , the equivalent system bus voltage is U S , the steady - state voltage of the converter bus is U P , the impedance between the equivalent new - energy bus and the converter bus is X W , the impedance between the equivalent system bus and the converter bus is X S , the power flow from the equivalent new - energy bus to the converter bus is P W +jQ W , the power flow from the equivalent system bus to the converter bus is P AC +jQ AC , the shunt capacitance branch generated after the π - type equivalent of the line connecting the equivalent system bus and the converter bus is denoted as jQ L , the reactive power of the equivalent filter of the converter bus is denoted as jQ C , the power flowing into the converter valve of the DC system is P DC +jQ DC , denote the proportion of new - energy power generation in the DC system as η RE , then:

[0099] P W = η RE P DC (1)

[0100] Step 2: When a bipolar blocking fault occurs in the DC system, it is assumed that the equivalent AC system voltage U S remains unchanged before and after the fault. After bipolar blocking, the converter bus voltage is U PF , the power flow from the equivalent new energy bus to the converter bus becomes P WF +jQ WF , the power flow from the converter bus to the equivalent system bus is P ACF +jQ ACF , the line-to-ground capacitance branch becomes jQ LF , the reactive power of the equivalent filter at the converter bus becomes jQ CF , and the power flowing into the converter valves from the DC system is 0, as shown in Figure 3 ;

[0101] Step 3: After bipolar blocking occurs, considering that the capacitive reactive power is proportional to the square of the voltage, the relationship between the reactive power of the filter and the line before and after the fault is:

[0102]

[0103] Step 4: Combining the forward-backward substitution method of power flow calculation, the relationship between the injection at the converter bus and the reactive power flowing into the AC system is:

[0104]

[0105] Step 5: If the resistance in each transmission line is ignored, then P WF =P ACF , and further the relationship between the converter bus voltage U PF after the fault and U S is:

[0106]

[0107] Step 6: Substituting (4) into (5), the analytical solution of the quartic equation about U PF can be obtained. However, considering the large computational amount in engineering calculations and that X S is usually small, (3) can be approximated within the allowable error range as:

[0108]

[0109] Step 7: If we denote A = Q C +Q L , (4) can be simplified to:

[0110]

[0111] Step 8: Approximately assume U P≈ 1, a quartic equation about U can be obtained, and (6) can be analytically solved by the quadratic formula, where PF : :

[0112]

[0113] Step9: Substitute the system equivalent parameters into (8), and an analysis model considering the dynamic characteristics of new energy can be constructed, and the quantitative calculation of the overvoltage of the sending-end system can be realized based on the analysis model;

[0114] Step10: The DC short-circuit ratio is a commonly used quantitative analysis index in engineering. If the DC short-circuit ratio k SCR of the sending end is considered, it is:

[0115]

[0116] (9) can be substituted into (8) to obtain a quantitative analysis method for the overvoltage of the sending end with stronger engineering practical applicability.

[0117] The best embodiments of the present invention are described as follows.

[0118] The new energy output ratio, DC short-circuit ratio, and system overvoltage level are three indicators that are relatively concerned in the field of power grid planning. The large-scale access of new energy will affect the system short-circuit ratio and overvoltage level. The equivalent wiring diagrams of the system under steady state and after bipolar blocking fault are as shown in Figure 2 and 3 .

[0119] By using equations (8) and (9), the calculation formula for the system overvoltage expressed in terms of the short-circuit ratio can be obtained, and the minimum short-circuit ratio requirements corresponding to different new energy output ratios or the maximum new energy output ratio under different short-circuit ratio conditions can be calculated when the overvoltage level does not exceed the limit value. Considering the typical parameters of bipolar blocking as: Q C +Q L = 0.5, the overvoltage conditions of the sending-end converter busbar under different new energy output ratios η RE and different short-circuit ratios k SCR can be plotted, as shown in Figure 4 and 5 .

[0120] In engineering, the voltage of the converter busbar after bipolar blocking should generally not be greater than 1.3 p.u. as a restrictive factor. With the help of the Figure 4 calculation results, the overvoltage conditions of the converter busbar under different short-circuit ratios and new energy access ratios can be obtained analytically and intuitively.

[0121] Taking Figure 2 and 3Taking a system as an example, a simplified system model is constructed based on a ±800kV UHV DC photovoltaic and thermal power bundled external transmission system in the northwest of China.

[0122] When the DC transmission power remains unchanged, usually two methods of reducing the number of operating units and reducing the output are adopted to accommodate the output of renewable energy. The following two methods are used to explore the overvoltage conditions under different working conditions.

[0123] When accommodating new energy in the way of reducing the output, while keeping the synchronous generator running, the active output is reduced. Therefore, at different η RE s, the k SCR of the converter busbar remains almost unchanged, but the overvoltage phenomenon changes significantly. The relevant simulation data and the waveforms of the converter busbar are shown in Table 1 and Figure 6 as follows:

[0124] Table 1

[0125]

[0126] For the method of reducing the number of operating units, on the premise that neither the synchronous unit nor the new energy power supply reserves standby, by adjusting the output ratio of the two types of power supplies, operating conditions with different new energy output ratios and short-circuit ratios are obtained. When there is no new energy access, the system short-circuit ratio is 3.5323. The relevant simulation data and the overvoltage waveforms of the converter busbar are shown in Table 2 and Figure 7 as follows.

[0127] Table 2

[0128]

[0129] Embodiment 2:

[0130] The present invention also proposes a system 200 for quantifying the overvoltage at the sending end of a power system, as Figure 8 shown, including:

[0131] An acquisition unit 201 for obtaining the equivalent parameters of the DC near area at the sending end of the power system to be analyzed;

[0132] A modeling unit 202 for establishing an analysis model based on the equivalent parameters;

[0133] A quantification unit 203 for constructing a quantification analysis index, substituting the quantification analysis index into the analysis model for solution, so as to quantify the overvoltage at the sending end of the power system to be analyzed.

[0134] Among them, the equivalent parameters include:

[0135] The equivalent new energy busbar voltage U W , the equivalent system busbar voltage U S , and the steady-state voltage U P of the converter busbar, the impedance X between the equivalent new energy busbar and the converter busbar W , the impedance X between the equivalent system busbar and the converter busbar S , the power flow power P flowing from the equivalent new energy busbar to the converter busbar W +jQ W , the power flow power P flowing from the equivalent system busbar to the converter busbar AC +jQ AC , the shunt capacitance branch jQ generated after the π - type equivalent of the line connecting the equivalent system busbar and the converter busbar L , the reactive power of the equivalent filter of the converter busbar is denoted as jQ C , the power P flowing from the DC system into the converter valve DC +jQ DC , the output proportion η of the new energy power source in the DC system RE , then:

[0136] P W =η RE P DC . (1)

[0137] Among them, based on the above - mentioned equivalent parameters, an analysis model is established, including:

[0138] After the bipolar blocking fault occurs in the DC system, determine the relationship between the reactive power of the filter and the line before and after the bipolar blocking fault of the DC, as follows:

[0139]

[0140] Based on the forward - backward substitution method of power flow calculation, determine the relationship between the converter busbar and the reactive power flowing into the AC system, as follows:

[0141]

[0142] Ignoring the resistance in each transmission line, then P WF =P ACF , determine the relationship between the converter busbar voltage U PF and U S after the bipolar blocking fault of the DC occurs, as follows:

[0143]

[0144] Substitute (4) into (5) to obtain the analytical solution of the quartic equation of U PF , among which, approximate (3) as:

[0145]

[0146] If it is denoted that A = Q C +Q L , Simplify (4) to:

[0147]

[0148] If U P ≈ 1, then a quartic equation of U PF is obtained, and (6) can be analytically solved by the quadratic formula, where then the calculation formula of U PF is as follows:

[0149]

[0150] Substitute the equivalent parameters into (8) to construct an analysis model.

[0151] Among them, the calculation formula of the quantitative analysis index is as follows:

[0152]

[0153] Among them, k SCR is the quantitative analysis index.

[0154] The calculation method proposed in the present invention effectively predicts and calculates the overvoltage situation after bipolar blocking of the system by considering the influence of new energy output. Under different new energy output ratios, the calculation method proposed in the present invention has good accuracy.

[0155] Example 3:

[0156] Based on the same inventive concept, the present invention also provides a computer device, which includes a processor and a memory. The memory is used to store a computer program, and the computer program includes program instructions. The processor is used to execute the program instructions stored in the computer storage medium. The processor may be a central processing unit (CPU), or may also be other general-purpose processors, digital signal processors (DSP), application specific integrated circuits (ASIC), field-programmable gate arrays (FPGA), or other programmable logic devices, discrete gate or transistor logic devices, discrete hardware components, etc. It is the computing core and control core of the terminal, and is suitable for implementing one or more instructions, specifically suitable for loading and executing one or more instructions in the computer storage medium to implement the corresponding method flow or corresponding function, so as to implement the steps of the method in the above embodiment.

[0157] Example 4:

[0158] Based on the same inventive concept, the present invention also provides a storage medium, specifically a computer-readable storage medium (Memory). The computer-readable storage medium is a memory device in a computer device, used to store programs and data. It can be understood that the computer-readable storage medium here can include both the built-in storage medium in the computer device and, of course, the extended storage medium supported by the computer device. The computer-readable storage medium provides a storage space, and this storage space stores the operating system of the terminal. And, in this storage space, there are also stored one or more instructions suitable for being loaded and executed by the processor. These instructions can be one or more computer programs (including program codes). It should be noted that the computer-readable storage medium here can be a high-speed RAM memory or a non-volatile memory, such as at least one disk memory. One or more instructions stored in the computer-readable storage medium can be loaded and executed by the processor to implement the steps of the method in the above embodiments.

[0159] Those skilled in the art should understand that the embodiments of the present invention can be provided as a method, a system, or a computer program product. Therefore, the present invention can take the form of a complete hardware embodiment, a complete software embodiment, or an embodiment combining software and hardware aspects. Moreover, the present invention can take the form of a computer program product implemented on one or more computer-usable storage media (including but not limited to disk memories, CD-ROMs, optical memories, etc.) containing computer-usable program codes. The solutions in the embodiments of the present invention can be implemented using various computer languages. For example, object-oriented programming languages such as Java and interpreted scripting languages such as JavaScript.

[0160] The present invention is described with reference to the flowcharts and / or block diagrams of methods, devices (systems), and computer program products according to the embodiments of the present invention. It should be understood that each flow and / or block in the flowchart and / or block diagram, and the combination of flows and / or blocks in the flowchart and / or block diagram, can be implemented by computer program instructions. These computer program instructions can be provided to the processor of a general-purpose computer, a special-purpose computer, an embedded processor, or other programmable data processing devices to generate a machine, such that the instructions executed by the processor of the computer or other programmable data processing devices generate a device for implementing the specified functions in Figure 1 one flow or multiple flows and / or blocks Figure 1 one block or multiple blocks.

[0161] These computer program instructions may also be stored in a computer-readable memory that can direct a computer or other programmable data processing apparatus to function in a particular manner, such that the instructions stored in the computer-readable memory produce an article of manufacture including instruction means embodying the function specified in the flowchart Figure 1 a flowchart or multiple flowcharts and / or block Figure 1 a block or multiple blocks.

[0162] These computer program instructions may also be loaded onto a computer or other programmable data processing apparatus to cause a series of operational steps to be performed on the computer or other programmable apparatus to produce a computer-implemented process, whereby the instructions executed on the computer or other programmable apparatus provide steps for implementing the function specified in the flowchart Figure 1 a flowchart or multiple flowcharts and / or block Figure 1 a block or multiple blocks.

[0163] Although the preferred embodiments of the present invention have been described, additional changes and modifications can be made by those skilled in the art once they learn of the basic inventive concept. Therefore, the appended claims are intended to be construed to cover the preferred embodiments as well as all changes and modifications falling within the scope of the present invention.

[0164] Obviously, those skilled in the art can make various changes and modifications to the present invention without departing from the spirit and scope of the present invention. Thus, if these modifications and variations of the present invention fall within the scope of the claims of the present invention and their equivalent technologies, the present invention is also intended to include these modifications and variations.

Claims

1. A method for quantifying overvoltage at the sending end of a power system, characterized in that, Including: Obtain the equivalent parameters of the near area of the sending-end DC of the power system to be analyzed; Based on the equivalent parameters, establish an analysis model; Construct a quantitative analysis index, and substitute the quantitative analysis index into the analysis model for solution to quantify the overvoltage at the sending end of the power system to be analyzed.

2. The method according to claim 1, characterized in that The equivalent parameters include: Equivalent new energy bus voltage U W , equivalent system bus voltage U S , converter bus steady-state voltage U P , impedance X between equivalent new energy bus and converter bus W , impedance X between equivalent system bus and converter bus S , power flow P from equivalent new energy bus to converter bus W +jQ W , power flow P from equivalent system bus to converter bus AC +jQ AC , shunt capacitance branch jQ generated after π-type equivalent of the line connecting equivalent system bus and converter bus L , reactive power of the equivalent filter of converter bus is denoted as jQ C , power P flowing into converter valve from DC system DC +jQ DC , proportion η of new energy power output in DC system RE , then: P W = η RE P DC (1).

3. The method according to claim 1, characterized in that, Based on the equivalent parameters, establishing an analysis model includes: After a bipolar blocking fault occurs in the DC, determine the relationship between the reactive power of the filter and the line before and after the bipolar blocking fault of the DC, as follows: Based on the forward-backward substitution method of power flow calculation, determine the relationship between the converter bus and the reactive power flowing into the AC system, as follows: Ignoring the resistance in each transmission line, then P WF = P ACF . After determining that a bipolar blocking fault occurs in the DC system, the relationship between the converter bus voltage U PF and U S is as follows: Substitute (4) into (5) to obtain U PF The analytical solution of the quartic equation of one variable, where (3) is approximated as: If we denote A = Q C + Q L , Simplify (4) to get: If U P ≈ 1, then a quartic equation of U PF is obtained, and it can be analytically solved for (6) through the root formula, where, then the calculation formula of U PF is as follows: Substitute the equivalent parameters into (8) to construct an analysis model.

4. The method according to claim 1, wherein The calculation formula of the quantitative analysis index is as follows: Among them, k SCR is a quantitative analysis index.

5. A system for quantifying overvoltage at the sending end of a power system, characterized in that, Including: An acquisition unit for obtaining the equivalent parameters of the near area of the sending-end DC of the power system to be analyzed; A modeling unit for establishing an analysis model based on the equivalent parameters; A quantification unit for constructing a quantitative analysis index and substituting the quantitative analysis index into the analysis model for solution to quantify the overvoltage at the sending end of the power system to be analyzed.

6. The system according to claim 5, characterized in that The equivalent parameters include: Equivalent new energy bus voltage U W , equivalent system bus voltage U S , converter bus steady-state voltage U P , impedance X between equivalent new energy bus and converter bus W , impedance X between equivalent system bus and converter bus S , power flow P from equivalent new energy bus to converter bus W +jQ W , power flow P from equivalent system bus to converter bus AC +jQ AC , shunt capacitance branch jQ generated after π-type equivalent of the line connecting equivalent system bus and converter bus L , reactive power of equivalent filter of converter bus is denoted as jQ C , power P flowing into converter valve from DC system DC +jQ DC , output proportion η of new energy power source in DC system RE , then: P W = η RE P DC (1).

7. The system according to claim 5, wherein Based on the equivalent parameters, establishing an analysis model includes: After a bipolar blocking fault occurs in the DC, determine the relationship between the reactive power of the filter and the line before and after the bipolar blocking fault of the DC, as follows: Based on the forward-backward substitution method of power flow calculation, determine the relationship between the converter bus and the reactive power flowing into the AC system, as follows: Ignoring the resistance in each transmission line, then P WF = P ACF . After determining that a bipolar blocking fault occurs in the DC system, the relationship between the converter bus voltage U PF and U S is as follows: Substitute (4) into (5) to obtain the analytical solution of the quartic equation of one variable for U PF where (3) is approximated as: If we denote A = Q C + Q L , Simplify (4) to get: If U P ≈ 1, then a quartic equation of one variable for U PF is obtained, and (6) can be analytically solved by using the quadratic formula, where, then the calculation formula for U PF is as follows: Substitute the equivalent parameters into (8) to construct an analysis model.

8. The system according to claim 5, characterized in that, The calculation formula of the quantitative analysis index is as follows: Among them, k SCR is a quantitative analysis index.

9. A computer device, characterized in that, Including: One or more processors; The processor is used to execute one or more programs; When the one or more programs are executed by the one or more processors, the method described in any one of claims 1-4 is implemented.

10. A computer-readable storage medium, characterized in that, A computer program is stored thereon, and when the computer program is executed, the method described in any one of claims 1-4 is implemented.

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