Impedance-based new energy low-pass short-time power disturbance quantity calculation method and system

Abstract

The invention relates to the technical field of power systems and automation thereof, in particular to an impedance-based new energy low-pass short-time power disturbance quantity calculation method and system, and the method comprises the steps: collecting the operation mode data of a power grid, correcting the nodes, including a generator, new energy and a load, in a node admittance matrix of the power grid, and obtaining a new energy low-pass short-time power disturbance quantity; constructing to obtain a node impedance matrix used for calculating different node voltage drop degrees at the initial stage of the fault; and in combination with an active control strategy of the new energy during the low-voltage ride-through period, a calculation method of the short-time power disturbance quantity of the new energy during the low-voltage ride-through period is obtained. According to the method, the power disturbance quantity generated by the new energy entering low voltage ride through due to voltage drop at the initial stage of the short circuit fault in the power grid can be effectively calculated, and a basis is provided for subsequent on-line and off-line safe and stable control.

Description

Technical Field

[0001] The present invention relates to the field of power systems and automation technologies thereof, and in particular to an impedance-based new energy low-penetration short-term power disturbance calculation method and system. Background Art

[0002] We need to accelerate the energy revolution, improve the capacity to absorb new energy, accelerate green and low-carbon development, and build a new power system with new energy as the main body. It is foreseeable that in the next few years, new energy will usher in rapid development, and the proportion of new energy in power generation will also increase rapidly.

[0003] Unlike traditional power systems, the high proportion of renewable energy in new power systems has squeezed the power generation space of conventional power sources, and the rotational inertia and frequency regulation capabilities of the power grid have continued to decline. The transient response behavior of renewable energy units has increasingly affected the stability of the power grid, and has become an important factor affecting the stability of the power grid and its power transmission capacity. With the increasing proportion of renewable energy in new power systems, the short-term power disturbances generated during the low voltage ride-through of renewable energy will also cause rapid changes in the system frequency. At present, relevant studies on the maximum non-synchronous power penetration rate of a European power grid have pointed out that the impact of low voltage ride-through of wind turbines caused by power grid faults on frequency may be more serious than the tripping of large units. If the low frequency triggers the wind power rotation rate change (ROCOF) protection and the low frequency defense line of the power grid, it will cause more serious impacts. There are also studies that point out that the Northeast Power Grid has the risk of a large area of ​​renewable energy entering low voltage ride-through due to a single power grid fault, which in turn threatens the frequency security of the power grid.

[0004] If it is possible to calculate in advance the short-term power disturbance caused by the low-frequency penetration of renewable energy after a single power grid failure, it can be prevented and controlled through fast-response control resources such as electrochemical energy storage, greatly improving the system's ability to cope with low-frequency risks. At present, a lot of research has been done on the low-frequency penetration capability, low-frequency penetration characteristics and low-frequency penetration control strategies of renewable energy, but there is still a lack of corresponding calculation methods for the short-term power disturbance during the low-frequency penetration of renewable energy. Summary of the invention

[0005] In view of the above problems existing in the prior art, the present invention is proposed.

[0006] The present invention provides an impedance-based calculation method for the short-term power disturbance caused by the low penetration of new energy, which is used to solve the problem of how to calculate the short-term power disturbance caused by the low penetration of new energy in practical problems.

[0007] In order to solve the above technical problems, the present invention provides the following technical solutions: a method for calculating the short-term power disturbance of new energy low-penetration based on impedance, comprising: collecting grid operation mode data, and adjusting the data according to the actual operation conditions of the grid when an accident occurs;

[0008] Construct a node impedance matrix for calculating the voltage drop degree of different nodes at the initial stage of fault;

[0009] Combined with the active power control strategy of renewable energy during low voltage ride-through, the calculation method of short-term power disturbance of renewable energy during low voltage ride-through is derived;

[0010] Combined with the node impedance matrix used to calculate the voltage drop degree of different nodes at the initial stage of the fault and the active power control strategy of renewable energy during low voltage ride-through, a calculation formula for the disturbance power of renewable energy entering low voltage ride-through caused by short-circuit fault voltage disturbance is obtained.

[0011] As a preferred solution of the impedance-based new energy short-term power disturbance calculation method of the present invention, wherein: the power grid operation mode data includes a power flow file and a stability file;

[0012] The power flow file and stability file contain the impedance parameters of each branch, as well as the models and parameters of various components.

[0013] As a preferred solution of the impedance-based new energy short-term power disturbance calculation method of the present invention, the node impedance matrix constructed for calculating the voltage drop degree of different nodes at the initial stage of the fault includes:

[0014] Calculate the node admittance matrix of the system, ignore the admittance of the generator, new energy and load nodes, and obtain the node admittance matrix including the admittance of each branch;

[0015] Considering the admittance calculation method of the nodes where the generator, new energy and load are located, the elements of the three categories of rows and columns in the initial node admittance matrix are corrected to obtain the modified node admittance matrix, and the node impedance matrix used to calculate the voltage drop degree of different nodes in the initial fault period is obtained.

[0016] As a preferred solution of the impedance-based new energy low-penetration short-time power disturbance calculation method described in the present invention, wherein: the admittance calculation method of the nodes where the generator, new energy and load are located includes a node impedance matrix correction method considering the characteristics of the synchronous generator, a node impedance matrix correction method considering the characteristics of the new energy unit, and a node impedance matrix correction method considering the characteristics of the load;

[0017] The node impedance matrix correction method considering the characteristics of the synchronous generator obtains the node impedance matrix after considering the characteristics of the synchronous generator by modifying the corresponding elements in the node admittance matrix. The correction amount of the generator node in the initial node admittance matrix of the power grid is expressed as:

[0018]

[0019]

[0020] Among them, X d ' is the direct axis transient reactance, X d ” is the direct-axis subtransient reactance, S B is the operating capacity, S N is the rated capacity, Y eqG It is represented as the correction amount of the generator node in the initial node admittance matrix of the power grid, and j is represented as the imaginary part.

[0021] As a preferred solution of the impedance-based new energy short-term power disturbance calculation method described in the present invention, the node impedance matrix correction method considering the characteristics of the new energy unit includes taking into account the equivalent sub-transient reactance in the new energy equivalent model during a fault, transforming the new energy unit through Norton transformation, and transforming the sub-transient reactance into the ground branch impedance of the new energy node, and using the equivalent impedance simulation method to calculate the equivalent transient reactance, which is expressed as:

[0022]

[0023] in, is the voltage per unit value at the time of failure of the new energy grid connection point, P W|0| and Q W|0| are respectively the active and reactive power transmitted from the grid connection point to the grid at the time of fault, and Im represents the imaginary part;

[0024] By modifying the corresponding elements in the node admittance matrix, the node impedance matrix considering the characteristics of the new energy unit is obtained. When the voltage at the grid-connected point of the new energy unit is in the range of 0.2pu-0.9pu, the reactive output current value of the grid-side converter is:

[0025]

[0026] Where k is the reactive gain coefficient, is the voltage per unit value at the time of failure of the new energy grid connection point, I N is the rated current of the wind turbine;

[0027] The per unit value of reactive current is:

[0028]

[0029] The correction amount of the new energy node in the initial node admittance matrix of the power grid is:

[0030]

[0031] As a preferred solution of the impedance-based new energy short-term power disturbance calculation method of the present invention, wherein: the node impedance matrix correction method considering load characteristics includes a constant impedance characteristic load model, a static load characteristic model and a dynamic load characteristic model;

[0032] The constant impedance characteristic load model is expressed as:

[0033]

[0034] The static load characteristic model is expressed as,

[0035]

[0036] Among them, A P Indicates the constant impedance active load ratio; A Q Indicates the constant impedance reactive load ratio; B P Indicates the constant current active load ratio; B Q Indicates the constant current reactive load ratio; C P Indicates the constant power active load ratio; C Q Indicates the constant power reactive load ratio; L DP Indicates the percentage change in active power caused by a 1% change in frequency; L DQ Indicates the percentage change in reactive power caused by a 1% change in frequency, A P +B P +C P =1.0, A Q +B Q +C Q =1.0;

[0037] The dynamic load characteristic model is expressed as:

[0038]

[0039] Among them, R S Indicates the per-unit value of stator resistance; X S Indicates the per unit value of stator reactance; X M Indicates the per unit value of magnetizing reactance; X r Indicates the per unit value of rotor reactance; R r represents the per-unit value of rotor resistance; s represents the rotor slip rate.

[0040] As a preferred solution of the impedance-based new energy short-term power disturbance calculation method described in the present invention, the voltage drop degree of each node at the initial stage of the fault is calculated based on the corrected node impedance matrix, which is expressed as:

[0041]

[0042] In the formula, ΔU i is the voltage drop at node i under disturbance, ΔU j is the voltage drop at node j caused by the disturbance node i, Z ii is the self-impedance of the reactor node i, Z ij is the mutual impedance between node j and the disturbance node i;

[0043] The difference between the power of a single renewable energy unit when it enters low-breakthrough and the power during normal operation is the disturbance power, and the calculation formula is:

[0044] ΔP i =P 0i -P ti

[0045] Where: ΔP i represents the disturbance power generated by the low penetration of the i-th renewable energy unit; P 0i represents the power of the i-th renewable energy unit in normal operation; P ti It represents the power of the i-th renewable energy unit when it enters low-voltage breakout. By adding up all the disturbance powers, we can get the disturbance power ΔP generated by all renewable energy units in the system that enter low-voltage breakout. The calculation formula is:

[0046]

[0047] Where: i represents the i-th renewable energy unit; N represents the number of renewable energy units in the system.

[0048] As a preferred solution of the impedance-based new energy low-penetration short-time power disturbance calculation system described in the present invention, it includes: an information collection and adjustment module, which collects power grid operation mode data and adjusts the data according to the actual operating conditions of the power grid when an accident occurs;

[0049] The impedance matrix calculation module calculates the node impedance matrix of the system and corrects the matrix elements including the new energy, generator and load nodes according to the correction method;

[0050] The voltage calculation module calculates the voltage drop value of each node in the system at the initial stage of a single power grid fault based on the modified node impedance matrix obtained by the impedance matrix calculation module;

[0051] The disturbance power calculation module calculates the disturbance power caused by the low penetration of new energy in the system after a single power grid failure based on the voltage drop of each node in the system at the initial stage of the fault obtained by the voltage calculation module and the new energy low penetration strategy.

[0052] A computer device comprises a memory and a processor, wherein the memory stores a computer program, and is characterized in that when the processor executes the computer program, the steps of any one of the methods for calculating the short-time power disturbance amount of new energy low-penetration based on impedance are implemented.

[0053] A computer-readable storage medium having a computer program stored thereon, characterized in that when the computer program is executed by a processor, the steps of any one of the methods for calculating the short-time power disturbance amount of new energy low-penetration based on impedance are implemented.

[0054] Beneficial effects of the present invention: The present invention collects grid operation mode data and corrects the nodes containing generators, new energy and loads in the grid node admittance matrix to construct a node impedance matrix for calculating the voltage drop degree of different nodes at the initial stage of a fault; and combines the active power control strategy of new energy during low voltage ride-through to obtain a method for calculating the short-term power disturbance of new energy during low voltage ride-through. This method can effectively calculate the power disturbance generated by new energy due to voltage drop entering low voltage ride-through at the initial stage of a short circuit fault in the grid, providing a basis for subsequent online and offline safe and stable control. BRIEF DESCRIPTION OF THE DRAWINGS

[0055] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the accompanying drawings required for use in the description of the embodiments will be briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other accompanying drawings can be obtained based on these accompanying drawings without paying creative work.

[0056] Figure 1 A flowchart of a method for calculating short-term power disturbance of new energy based on impedance provided by an embodiment of the present invention.

[0057] Figure 2 The active power output of three wind farms when the voltage at the fault point drops sharply according to the impedance-based new energy short-term power disturbance calculation method described in an embodiment of the present invention.

[0058] Figure 3 The active power output of three wind farms when the voltage at the fault point drops slightly according to the impedance-based new energy short-term power disturbance calculation method described in an embodiment of the present invention. DETAILED DESCRIPTION

[0059] In order to make the above-mentioned purposes, features and advantages of the present invention more obvious and easy to understand, the specific implementation methods of the present invention are described in detail below in conjunction with the drawings of the specification. Obviously, the described embodiments are part of the embodiments of the present invention, but not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary persons in the art without creative work should fall within the scope of protection of the present invention.

[0060] Example 1

[0061] Reference Figure 1 The flowchart is a first embodiment of the present invention, which provides a method for calculating the short-term power disturbance of a new energy source based on impedance, including:

[0062] S1. Collect grid operation mode data and adjust the grid operation mode data according to the actual operation conditions of the grid when the accident occurs;

[0063] Furthermore, the grid operation mode data includes power flow files and stability files;

[0064] It should be noted that the power flow file and stability file contain the impedance parameters of each branch, as well as the models and parameters of various components;

[0065] S2, construct the initial node admittance matrix;

[0066] Furthermore, the node admittance matrix of the system is calculated, ignoring the admittance of the generator, new energy and load nodes, and the node admittance matrix including the admittance of each branch is obtained;

[0067] S3, constructing a node impedance matrix for calculating the voltage drop degree of different nodes at the initial stage of a fault;

[0068] Furthermore, the elements in the rows and columns containing generators, new energy sources and load nodes in the initial node admittance matrix are corrected to obtain a modified node admittance matrix, and the node impedance matrix used to calculate the voltage drop degree of different nodes at the initial fault stage is obtained by inversion.

[0069] The admittance correction method for the node where the generator is located. During a fault, it is necessary to consider the support influence of the transient process of the synchronous machine, taking into account the transient reactance effect of the generator. The synchronous machine is equivalent to a series connection of a voltage source and an impedance. After the Norton transformation, the transient reactance of the generator is transformed into the impedance of the ground branch of the generator node. By modifying the corresponding elements in the node admittance matrix, the node impedance matrix considering the characteristics of the synchronous generator is obtained. The correction amount of the generator node in the initial node admittance matrix of the power grid is: in X d ' is the direct axis transient reactance, X d” is the direct-axis subtransient reactance, S B is the operating capacity, S N is the rated capacity.

[0070] For the admittance correction method of the node where the new energy is located. During the fault, the equivalent subtransient reactance in the new energy equivalent model is taken into account. The new energy unit is transformed into the impedance of the branch line to the ground of the new energy node through Norton transformation, and the equivalent impedance simulation method is used to approximate its equivalent transient reactance x eqR , the calculation formula is: Where: k is the reactive gain coefficient, is the voltage per unit value at the time of failure of the new energy grid connection point, P W|0| and Q W|0| are respectively the active and reactive power transmitted from the grid connection point to the grid at the time of the fault; by modifying the corresponding elements in the node admittance matrix, the node impedance matrix considering the characteristics of the new energy unit is obtained. When the voltage at the grid connection point of the new energy unit is in the range of 0.2pu-0.9pu, the reactive output current value of the grid-side converter is: Where: k is the reactive gain coefficient, is the voltage per unit value at the time of failure of the new energy grid connection point, I N is the rated current of the wind turbine.

[0071] The admittance correction method for the node where the load is located can be divided into three categories according to the load type in the power grid: constant impedance characteristic load model, static load characteristic model and dynamic load characteristic model.

[0072] For the constant impedance characteristic load model, its characteristic is that the impedance does not change with the change of the power system operation mode, and the equivalent impedance simulation method can be used for calculation. The equivalent impedance is:

[0073] For the static load characteristic model, the whole model consists of three parts: constant impedance load, constant current load and constant power load. The equivalent impedance simulation method is used for calculation, and the equivalent impedance is:

[0074] Where: A P Indicates the constant impedance active load ratio; A Q Indicates the constant impedance reactive load ratio; B P Indicates the constant current active load ratio; B Q Indicates the constant current reactive load ratio; C P Indicates the constant power active load ratio; C Q Indicates the constant power reactive load ratio; L DPIndicates the percentage change in active power caused by a 1% change in frequency; L DQ Indicates the percentage change in reactive power caused by a 1% change in frequency. A P +B P +C P =1.0, A Q +B Q +C Q =1.0.

[0075] For the dynamic load model, the equivalent impedance is: Among them, R S Indicates stator resistance (per unit value); X S Indicates stator reactance (per unit value); X M represents the magnetizing reactance (unit value); X r Indicates rotor reactance (per unit value); R r Indicates rotor resistance (standard value); s indicates rotor slip rate. In the above three model calculation methods, the values ​​with "0" are rated values, and the values ​​with "L" are operating values.

[0076] S4. Combine the node impedance matrix used to calculate the voltage drop degree of different nodes at the initial stage of the fault with the low-breakthrough strategy of the new energy, and calculate the short-term power disturbance caused by the low-breakthrough of the new energy at the initial stage of the fault.

[0077] Furthermore, the voltage drop degree of each node at the initial stage of the fault is calculated based on the modified node impedance matrix, and the formula is: Where ΔUi is the voltage drop at node i under disturbance, ΔU j is the voltage drop at node j caused by the disturbance node i, Zii is the self-impedance of the reactor node i, and Z ij is the mutual impedance between node j and the disturbed node i. If the voltage drop degree of the faulty node is known, the voltage drop degree of any node in the power grid can be calculated by the above formula.

[0078] The power of a single new energy unit when it enters low-breakthrough mode, and the difference between it and the power during normal operation is the disturbance power, and the calculation formula is: ΔP i =P 0i -P ti , where: ΔP i represents the disturbance power generated by the low penetration of the i-th renewable energy unit; P 0i represents the power of the i-th renewable energy unit in normal operation; P ti It represents the power of the i-th renewable energy unit when it enters low-voltage breakout. By adding up all the disturbance powers, we can get the disturbance power ΔP generated by all renewable energy units in the system that enter low-voltage breakout. The calculation formula is: Where: i represents the i-th renewable energy unit; N represents the number of renewable energy units in the system.

[0079] It should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit the present invention. Although the present invention has been described in detail with reference to the preferred embodiments, those skilled in the art should understand that the technical solutions of the present invention may be modified or replaced by equivalents without departing from the spirit and scope of the technical solutions of the present invention, which should all be included in the scope of the claims of the present invention.

[0080] Example 2

[0081] refer to Figure 2 and Figure 3 , which is the second embodiment of the present invention, provides a method for calculating the short-term power disturbance of new energy based on impedance. In order to verify the beneficial effects of the present invention, scientific demonstration is carried out through experiments.

[0082] By setting experimental parameters, building the experimental environment and combining the experimental output results, we can further prove the beneficial effects and feasibility of our invention.

[0083] The simulation grid is modified from the IEEE10 machine 39-node system, and the operating conditions are: the total load of the system is 1000MW, the constant power model is adopted, the frequency factor L=2.0; the inertia time constant H=4s, including 7 synchronous machines; there are 3 wind farms, each with a rated power of 1.5MW, and the number of wind turbines is 100, 50, and 50 respectively, with an output of 100MW, 50MW, and 50MW respectively. The voltage threshold for entering the low-voltage breakthrough is 0.85pu, and the active power recovery process during the low-voltage breakthrough adopts the specified power control, the power control value is 0, and the initial value is restored according to the actual power control during the low voltage period, and is restored according to 45% of the rated active power.

[0084] Two short-circuit faults are set, both occurring at the same location, one with a large voltage drop and the other with a small voltage drop. Through simulation calculations performed by the scheme of the present invention, for the case of a large voltage drop at the fault point, it can be calculated that all three wind farms enter low voltage ride-through, and the power disturbance at the initial stage of the fault is 200MW; for the case of a small voltage drop at the fault point, it can be calculated that only the wind farm with an output of 100MW enters low voltage ride-through, and the power disturbance at the initial stage of the fault is 100MW.

[0085] Figure 2 This is the active power output of the three wind farms when the voltage at the fault point drops sharply. It can be seen that the simulation results show that all three wind farms enter low-voltage breakover, and the calculation results are the same as the simulation results.

[0086] Figure 3This is the active power output of the three wind farms when the voltage at the fault point drops slightly. It can be seen from the simulation result that only the wind farm with an output of 100MW enters low voltage ride-through. The power disturbance at the initial stage of the fault is 100MW. The calculation result is the same as the simulation result.

[0087] It should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention rather than to limit it. Although the present invention has been described in detail with reference to the preferred embodiments, those skilled in the art should understand that the technical solutions of the present invention may be modified or replaced by equivalents without departing from the spirit and scope of the technical solutions of the present invention, which should all be included in the scope of the claims of the present invention.

[0088] Example 3

[0089] The third embodiment of the present invention is different from the first two embodiments in that:

[0090] If the functions are implemented in the form of software functional units and sold or used as independent products, they can be stored in a computer-readable storage medium. Based on this understanding, the technical solution of the present invention, or the part that contributes to the prior art or the part of the technical solution, can be embodied in the form of a software product. The computer software product is stored in a storage medium, including several instructions for a computer device (which can be a personal computer, a server, or a network device, etc.) to perform all or part of the steps of the methods described in each embodiment of the present invention. The aforementioned storage medium includes: U disk, mobile hard disk, read-only memory (ROM, Read-Only Memory), random access memory (RAM, Random Access Memory), disk or optical disk, etc., which can store program codes.

[0091] The logic and / or steps represented in the flowchart or otherwise described herein, for example, can be considered as an ordered list of executable instructions for implementing logical functions, and can be embodied in any computer-readable medium for use by an instruction execution system, device or apparatus (such as a computer-based system, a system including a processor, or other system that can fetch instructions from an instruction execution system, device or apparatus and execute instructions), or in conjunction with such instruction execution systems, devices or apparatuses. For the purposes of this specification, "computer-readable medium" can be any device that can contain, store, communicate, propagate or transmit a program for use by an instruction execution system, device or apparatus, or in conjunction with such instruction execution systems, devices or apparatuses.

[0092] More specific examples of computer-readable media (a non-exhaustive list) include the following: an electrical connection with one or more wires (electronic device), a portable computer disk case (magnetic device), a random access memory (RAM), a read-only memory (ROM), an erasable and programmable read-only memory (EPROM or flash memory), an optical fiber device, and a portable compact disk read-only memory (CDROM). In addition, the computer-readable medium may even be a paper or other suitable medium on which the program is printed, since the program may be obtained electronically, for example, by optically scanning the paper or other medium, followed by editing, deciphering or, if necessary, processing in another suitable manner, and then stored in a computer memory.

[0093] It should be understood that the various parts of the present invention can be implemented by hardware, software, firmware or a combination thereof. In the above-mentioned embodiments, a plurality of steps or methods can be implemented by software or firmware stored in a memory and executed by a suitable instruction execution system. For example, if implemented by hardware, as in another embodiment, it can be implemented by any one of the following technologies known in the art or their combination: a discrete logic circuit having a logic gate circuit for implementing a logic function for a data signal, a dedicated integrated circuit having a suitable combination of logic gate circuits, a programmable gate array (PGA), a field programmable gate array (FPGA), etc.

[0094] Example 4

[0095] The fourth embodiment of the present invention provides a new energy low-penetration short-time power disturbance amount calculation system based on impedance, which is characterized by: comprising:

[0096] An information collection and adjustment module collects data on the operation mode of the power grid and adjusts the data according to the actual operation conditions of the power grid when an accident occurs;

[0097] The impedance matrix calculation module calculates the node impedance matrix of the system and corrects the matrix elements including the new energy, generator and load nodes according to the correction method;

[0098] The voltage calculation module calculates the voltage drop value of each node in the system at the initial stage of a single power grid fault based on the modified node impedance matrix obtained by the impedance matrix calculation module;

[0099] The disturbance power calculation module calculates the disturbance power caused by the low penetration of new energy in the system after a single power grid failure based on the voltage drop of each node in the system at the initial stage of the fault obtained by the voltage calculation module and the new energy low penetration strategy.

[0100] It should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit the present invention. Although the present invention has been described in detail with reference to the preferred embodiments, those skilled in the art should understand that the technical solutions of the present invention may be modified or replaced by equivalents without departing from the spirit and scope of the technical solutions of the present invention, which should all be included in the scope of the claims of the present invention.

Claims

1. A method for calculating short-term power disturbance of new energy based on impedance, characterized by: include, Collect data on the operation mode of the power grid and adjust the data according to the actual operating conditions of the power grid when the accident occurs; Construct a node impedance matrix for calculating the voltage drop degree of different nodes at the initial stage of fault; Combined with the active power control strategy of renewable energy during low voltage ride-through, the calculation method of short-term power disturbance of renewable energy during low voltage ride-through is derived; Combined with the node impedance matrix used to calculate the voltage drop degree of different nodes at the initial stage of the fault and the active power control strategy of renewable energy during low voltage ride-through, a calculation formula for the disturbance power of renewable energy entering low voltage ride-through caused by short-circuit fault voltage disturbance is obtained.

2. The impedance-based new energy short-term power disturbance calculation method according to claim 1 is characterized in that: The power grid operation mode data includes a power flow file and a stability file; The power flow file and stability file contain the impedance parameters of each branch, as well as the models and parameters of various components.

3. The impedance-based new energy short-term power disturbance calculation method according to claim 2 is characterized in that: The node impedance matrix constructed to calculate the voltage drop degree of different nodes at the initial stage of a fault includes: Calculate the node admittance matrix of the system, ignore the admittance of the generator, new energy and load nodes, and obtain the node admittance matrix including the admittance of each branch; Considering the admittance calculation method of the nodes where the generator, new energy and load are located, the elements of the three categories of rows and columns in the initial node admittance matrix are corrected to obtain the modified node admittance matrix, and the node impedance matrix used to calculate the voltage drop degree of different nodes in the initial fault period is obtained.

4. The impedance-based new energy short-term power disturbance calculation method according to claim 3 is characterized in that: The admittance calculation method of the nodes where the generator, new energy and load are located includes a node impedance matrix correction method considering the characteristics of the synchronous generator, a node impedance matrix correction method considering the characteristics of the new energy unit, and a node impedance matrix correction method considering the characteristics of the load; The node impedance matrix correction method considering the characteristics of the synchronous generator obtains the node impedance matrix after considering the characteristics of the synchronous generator by modifying the corresponding elements in the node admittance matrix. The correction amount of the generator node in the initial node admittance matrix of the power grid is expressed as: Among them, X d ' is the direct axis transient reactance, X d ” is the direct-axis subtransient reactance, S B is the operating capacity, S N is the rated capacity, Y eqG It is represented as the correction amount of the generator node in the initial node admittance matrix of the power grid, and j is represented as the imaginary part.

5. The impedance-based new energy short-term power disturbance calculation method according to claim 4 is characterized in that: The node impedance matrix correction method considering the characteristics of the new energy unit includes taking into account the equivalent subtransient reactance in the new energy equivalent model during a fault, transforming the subtransient reactance of the new energy unit into the ground branch impedance of the new energy node through Norton transformation, and using the equivalent impedance simulation method to calculate the equivalent transient reactance, which is expressed as: in, is the voltage per unit value at the time of failure of the new energy grid connection point, P W|0| and Q W|0| are respectively the active and reactive power transmitted from the grid connection point to the grid at the time of fault, and Im represents the imaginary part; By modifying the corresponding elements in the node admittance matrix, the node impedance matrix considering the characteristics of the new energy unit is obtained. When the voltage at the grid-connected point of the new energy unit is in the range of 0.2pu-0.9pu, the reactive output current value of the grid-side converter is: Where k is the reactive gain coefficient, is the voltage per unit value at the time of failure of the new energy grid connection point, I N is the rated current of the wind turbine; The per unit value of reactive current is: The correction amount of the new energy node in the initial node admittance matrix of the power grid is:

6. The impedance-based new energy short-term power disturbance calculation method according to claim 5 is characterized in that: The node impedance matrix correction method considering load characteristics includes a constant impedance characteristic load model, a static load characteristic model and a dynamic load characteristic model; The constant impedance characteristic load model is expressed as, Wherein, Z represents the impedance value in the constant impedance characteristic load model, the subscript L represents the operating value, 0 represents the rated value, U represents the voltage, P represents the active power, Q represents the reactive power, and j represents the imaginary part; The static load characteristic model is expressed as, Among them, A P Indicates the constant impedance active load ratio; A Q Indicates the constant impedance reactive load ratio; B P Indicates the constant current active load ratio; B Q Indicates the constant current reactive load ratio; C P Indicates the constant power active load ratio; C Q Indicates the constant power reactive load ratio; L DP Indicates the percentage change in active power caused by a 1% change in frequency; L DQ Indicates the percentage change in reactive power caused by a 1% change in frequency, A P +B P +C P =1.0, A Q +B Q +C Q =1.0; The dynamic load characteristic model is expressed as: Among them, R S Indicates the per-unit value of stator resistance; X S Indicates the per unit value of stator reactance; X M Indicates the unit value of magnetizing reactance; X r Indicates the per unit value of rotor reactance; R r represents the per unit value of rotor resistance; c represents the rotor slip rate.

7. The impedance-based new energy short-term power disturbance calculation method according to claim 6 is characterized in that: The voltage drop degree of each node at the initial stage of the fault is calculated based on the corrected node impedance matrix, which is expressed as: In the formula, ΔU i is the voltage drop at node i under disturbance, ΔU j is the voltage drop at node j caused by the disturbance node i, Z ii is the self-impedance of the reactor node i, Z ij is the mutual impedance between node j and the disturbance node i; The difference between the power of a single renewable energy unit when it enters low-breakthrough and the power during normal operation is the disturbance power, and the calculation formula is: ΔP i =P 0i -P ti Where: ΔP i represents the disturbance power generated by the low penetration of the i-th renewable energy unit; P 0i represents the power of the i-th renewable energy unit in normal operation; P ti It represents the power of the i-th renewable energy unit when it enters low-voltage breakout. All disturbance powers are added together to obtain the disturbance power ΔP generated by all renewable energy units in the system that enter low-voltage breakout. The calculation formula is: Where: i represents the i-th renewable energy unit; N represents the number of renewable energy units in the system.

8. A system based on the impedance-based new energy short-term power disturbance calculation method according to any one of claims 1 to 7, characterized in that: include, An information collection and adjustment module collects power grid operation mode data and adjusts the data according to the actual operation conditions of the power grid when an accident occurs; The impedance matrix calculation module calculates the node impedance matrix of the system and corrects the matrix elements including the new energy, generator and load nodes according to the correction method; The voltage calculation module calculates the voltage drop value of each node in the system at the initial stage of a single power grid failure based on the modified node impedance matrix obtained by the impedance matrix calculation module; The disturbance power calculation module calculates the disturbance power caused by the low penetration of new energy in the system after a single power grid failure based on the voltage drop of each node in the system at the initial stage of the fault obtained by the voltage calculation module and the new energy low penetration strategy.

9. A computer device comprising a memory and a processor, wherein the memory stores a computer program, wherein: When the processor executes the computer program, the steps of the method according to any one of claims 1 to 7 are implemented.

10. A computer-readable storage medium having a computer program stored thereon, characterized in that: When the computer program is executed by a processor, the steps of the method according to any one of claims 1 to 7 are implemented.

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