New energy follow / network converter capacity configuration method based on power angle stability boundary

Abstract

The application discloses a new energy follow / network converter capacity configuration method based on a power angle stability boundary, first, a new energy sending end system simulation model containing a network type converter is established, and a steady state operating point of the system is calculated; then, the network type converter is dynamically equivalent to a synchronous generator, equivalent machine parameters are obtained, and the original simulation system is simplified into an equivalent machine and a new energy sending end system of a follow network type; mechanical power and electromagnetic power of the equivalent machine before, during and after a fault are derived, and an equivalent machine power angle characteristic curve is obtained; acceleration area and maximum deceleration area of the equivalent machine under different network type converter proportions are calculated, and a proportion of the network type new energy under a critical power angle stability of the system is obtained by using a dichotomy; simulation is carried out based on a PSASP platform, and rationality of the proposed configuration principle is verified. The scheme can reduce network investment of the system while guaranteeing safety and stability of the system, and improve the power grid's accommodation capacity for new energy.

Description

Technical Field

[0001] This invention belongs to the field of power system safety and stability analysis and capacity configuration, and particularly relates to a method for capacity configuration of new energy grid converters based on power angle stability boundary. Background Technology

[0002] With the comprehensive advancement of the "dual carbon" target, the installed capacity of new energy sources such as wind power and photovoltaics has experienced explosive growth. Because new energy units are flexibly connected to the grid through power electronic equipment, their strong volatility, weak inertia, and low immunity pose new challenges to the safe and stable operation of the power system. New energy power generation generally connects to the grid through grid-connected converters, using phase-locked loops (PLLs) to track the grid voltage, but lacks active support capabilities for the grid. As the grid-connected capacity of new energy continues to increase, the power angle stability problem of high-proportion new energy sending-end systems is becoming increasingly prominent. Grid-connected converters, by simulating the external characteristics of synchronous generators, autonomously construct the grid voltage and frequency, and have become a breakthrough technology for improving system stability. Therefore, constructing a hybrid grid-connected / grid-connected new energy power generation system, enabling the system to possess both the voltage source characteristics (weak grid adaptability) of grid-connected converters and the current source characteristics (strong grid adaptability) of grid-connected converters, has become a key path for the coordinated development of large-scale grid connection of new energy and power electronic converters.

[0003] Existing capacity optimization configurations for grid-connected / integrated converters fall into three categories: First, to improve system voltage stability, a stability criterion is constructed based on short-circuit ratio constraints, deriving the optimal capacity ratio threshold for integrated / integrated converters. Second, to improve system oscillation stability, the dominant oscillation modes of the grid-connected / integrated hybrid system under different grid intensities are identified, and a multi-converter coordinated control strategy suitable for weak grids is proposed, starting from improving the mode damping ratio under multiple frequency bands. Third, to improve system frequency stability, based on damping ratio and norm indices, the coupling mechanism between the proportion of integrated / integrated converters and control parameters on the steady-state and dynamic characteristics of the system frequency is revealed. Current technologies lack grid-connected and integrated converter ratio schemes considering power angle stability, and also lack research on grid-connected / integrated converter ratios for power angle stability constraints. Against this backdrop, how to improve system power angle stability through grid-connected / integrated converter ratio methods has become an urgent problem to be solved in this field. Summary of the Invention

[0004] Objective: To address the shortcomings and deficiencies of existing technologies, this invention provides a method for configuring the capacity of grid-connected converters for new energy transmission systems based on the power angle stability boundary, specifically addressing the power angle stability problem in systems with a high proportion of renewable energy transmission. When configuring the capacity of grid-connected converters, the system's power angle stability boundary is determined based on the equal area rule. The proportion of grid-connected converter capacity under the critical power angle stability condition is obtained through a bisection method. This method can effectively reduce grid-connected investment in renewable energy while improving the power angle stability of the transmission system.

[0005] Technical solution: The present invention provides a method for configuring the capacity of new energy grid-connected converters based on the power angle stability boundary, comprising the following steps:

[0006] Step 1: Based on wind power renewable energy data and synchronous generator power, construct a simulation model of the renewable energy sending-end system, including grid-connected converters and grid-connected converters, and calculate the steady-state operating point of the renewable energy sending-end system;

[0007] Step 2: Based on the steady-state operating point, dynamically equivalence the grid-type converter and synchronous generator in the new energy transmission system to obtain the equivalent machine parameters;

[0008] Step 3: By measuring the mechanical and electromagnetic power of the equivalent machine before, during, and after the fault, obtain the power angle characteristic curve of the equivalent machine, calculate the acceleration area and maximum deceleration area of ​​the equivalent machine, and determine the power angle stability of the new energy transmission system.

[0009] Step 4: Use the bisection method to obtain the proportion of grid-type new energy sources under the critical power angle stability, and use it as the proportion of grid-type converters under the system power angle stability boundary to complete the configuration of new energy and grid-type converter capacity.

[0010] Further, step 1 specifically involves: establishing a wind power transmission system based on the Power System Analysis and Synthesis Program (PSASP) platform; connecting new wind power to the grid via grid-connected converters and grid-connected converters; and converging synchronous generators with the new wind power after voltage boosting via transformers, before connecting to the infinite power system via two transmission lines; and calculating the voltage at each node and the virtual internal potential of the grid-connected wind power based on the power flow equations, according to network parameters, the power of wind power and synchronous generators. and virtual angle steady-state value and internal electromotive force of synchronous generator Sum of steady-state values ​​of work angle .

[0011] Furthermore, step 2 specifically includes the following steps:

[0012] Step 2.1: Based on the voltage source characteristics of grid-connected wind power and synchronous generators, perform dynamic equivalence analysis on the grid-connected wind power and synchronous generators. The equivalence parameters are as follows:

[0013] (1)

[0014] (2)

[0015] in: and These represent the internal potential and power angle of the equivalent machine, respectively; x1 represents the equivalent reactance of the equivalent machine; x GFMThis represents the virtual reactance of grid-connected wind power. The transient reactance of a synchronous generator; x T and x L1 These are the transformers through which the synchronous generator passes and the reactance of single-circuit line 1, respectively; T G* and T GFM* The inertial time constants of synchronous generators and grid-connected wind power are respectively, and are given by the system reference capacity S. B As a benchmark; S G and S GFM Rated capacity for synchronous generators and grid-connected wind power; T G and T GFM Synchronous generators and grid-connected wind power, respectively, are represented by their respective capacities S. G and S GFM The inertia time constant is used as the reference, and the conversion relationship is as follows:

[0016] (3)

[0017] Step 2.2: Perform star-delta transformation on the equivalent machine grid-connected system to obtain the impedance of the grid-connected system, including the equivalent grounding impedance of the equivalent machine, the equivalent grounding impedance of the infinite power supply, and the equivalent impedance between the equivalent machine and the infinite power supply point.

[0018] Furthermore, step 3 specifically includes the following steps:

[0019] Step 3.1: When the system is running normally, the active power output of the grid-connected wind turbine is P. w The reactive power output is 0, and the port voltage is U. w Let the reactive power compensation capacity of the wind farm be Q. c The equivalent grounding impedance Z of grid-type wind power f for:

[0020] (4)

[0021] Among them, Z w This represents the equivalent impedance of the wind farm, and j represents the imaginary unit.

[0022] The electromagnetic power of the isobaric machine is:

[0023] (5)

[0024] Where x2 represents the total line reactance between the synchronous generator and the new energy grid connection point and the infinite power source; U is the voltage of the infinite power source; x2 = 0.5x L2 x L2 The line reactance between the synchronous generator and the new energy grid connection point and the infinite power source;

[0025] Step 3.2: During the fault period, the grid-connected wind power enters a low-voltage ride-through state, and the active power output P of the grid-connected wind turbine unit... w And no effort put in Q w Specifically:

[0026] (6)

[0027] Where, k q U is the reactive power support coefficient. in k is the threshold for new energy generating units to enter low-voltage ride-through. p I is the active current coefficient. p To keep pace with the active current of the grid-connected wind farm, I p0 This refers to the active current when the grid-connected wind farm is operating normally;

[0028] The equivalent grounding impedance of the grid-connected wind farm is:

[0029] (7)

[0030] Where, x e The grounding reactance at the fault point is given by j, which is the imaginary unit.

[0031] The electromagnetic power of the isobaric machine is expressed as:

[0032] (8)

[0033] Step 3.3: After the fault is cleared, the electromagnetic power expression of the equalization machine is consistent with formula (5), but x2=x L2 ;

[0034] Step 3.4: Let the steady-state output of the synchronous generator be P. G The total active power output of the new energy power station is P T Among them, the active power outputs of grid-connected wind turbines and grid-connected converters are respectively P w and P GFM And satisfy P w +P GFM =P T The capacity ratio λ of a grid-type converter is defined as λ = P. GFM / P T Then the mechanical power of the equivalent machine during normal operation, during a fault, and after the fault is cleared is:

[0035] (9)

[0036] Step 3.5: Calculate the acceleration and deceleration areas of the equivalent machine to determine the power angle stability of the system.

[0037] Furthermore, step 4 specifically includes the following steps:

[0038] Step 4.1: Based on the definition of the capacity ratio λ of the grid-type converter, the lower limit of λ is obtained as a0=0, and the upper limit is obtained as b0=1. Then, using the bisection method...

[0039] λ0 = (a0 + b0) / 2 = 0.5

[0040] Calculate the system power flow at λ0=0.5, and equate the synchronous generator with the grid-type converter;

[0041] Step 4.2: Calculate the mechanical and electromagnetic power of the equivalent machine before, during, and after the fault when λ0=0.5, and calculate the acceleration area S of the equivalent machine. + and maximum deceleration area S -max ;

[0042] Step 4.3, if S + >S -max Increase λ0; if S + -max Then decrease λ0; when λ0 increases or decreases, the dichotomy principle is used; when it increases: a n+1 =λ n b n+1 =b n When it decreases: a n+1 =a n b n+1 =λ n ;where λ n , a n , b n Let λ represent the capacity ratio of the grid-type converter and its lower and upper limits, respectively, in the nth iteration. n+1 , a n+1 , b n+1 These represent the capacity ratio of the grid-type converter and its lower and upper limits, respectively, in the (n+1)th iteration.

[0043] Step 4.4: Repeat steps 4.2-4.3, iterating until |S + -S -max |<ε, where ε is a set positive value; after the iteration is complete, output the result λ.

[0044] This invention also discloses a new energy grid-connected converter capacity configuration system based on the power angle stability boundary, comprising:

[0045] Equivalent unit: Dynamically equivalentize grid-connected wind power with synchronous generators to obtain equivalent machine parameters;

[0046] ​Calculation unit: Calculates the electromagnetic power and mechanical power of the equivalent machine before, during and after the fault, obtains the power angle characteristic curve of the equivalent machine, and calculates the acceleration area and the maximum deceleration area.

[0047] Search Unit: Using the bisection method, the search is performed to determine the capacity ratio of the grid-connected converter under the power angle stability boundary.

[0048] Simulation Unit: Based on the PSASP platform, a high-proportion renewable energy transmission system model with grid-connected wind power is established, and disturbance simulation analysis is performed to analyze the power angle stability of the system under different grid-connected converter capacity ratios.

[0049] The present invention also discloses a computer device, including a memory, a processor, and a computer program stored in the memory, wherein the processor executes the computer program to implement the steps of the method of the present invention.

[0050] The present invention also discloses a computer-readable storage medium having a computer program / instructions stored thereon, which, when executed by a processor, implements the steps of the method of the present invention.

[0051] The present invention also discloses a computer program product, including a computer program / instructions that, when executed by a processor, implement the steps of the method of the present invention.

[0052] Beneficial Effects: Compared with existing technologies, this invention has the following significant advantages: This invention proposes a method for configuring the capacity of grid-connected converters in a high-proportion renewable energy sending-end system, considering the power angle stability boundary. By establishing a simulation model and dynamically equipping grid-connected converters and synchronous generators, the system analysis is simplified and the power angle characteristic curve is derived. This allows for accurate calculation of the acceleration area and maximum deceleration area under different grid-connected converter proportions. Furthermore, a bisection method is used to determine the optimal grid-connected ratio under the critical power angle stability boundary. This method not only effectively improves the power angle stability of the power system and enhances the safety and reliability of renewable energy grid connection, but also reduces system investment costs by optimizing the configuration ratio of grid-connected converters. Simultaneously, it improves the grid's capacity to accommodate high-proportion renewable energy, providing key technical support for the coordinated development of large-scale renewable energy grid connection and power electronic converters. Attached Figure Description

[0053] Figure 1 This is a flowchart of the method of the present invention;

[0054] Figure 2 Diagram of a new energy transmission-end grid connection system;

[0055] Figure 3 This is a circuit diagram of a new energy transmission system; where (a) is... Figure 2 (a) is the system's circuit diagram; (b) is the equivalent circuit diagram.

[0056] Figure 4 Equivalent circuit diagram of star-delta conversion for new energy transmission system;

[0057] Figure 5 Equivalent power angle curves of grid converters with different proportions;

[0058] Figure 6 Power angle curves of the equivalent machine under different proportions of grid converters;

[0059] Figure 7 The diagram shows the power angle curves of synchronous generators and grid-connected wind power, where (a) represents the power angle instability of the equivalent generator and (b) represents the power angle stability of the equivalent generator. Detailed Implementation

[0060] The technical solution of the present invention will be further described below with reference to the accompanying drawings.

[0061] Example 1:

[0062] like Figure 1 As shown, the process of this invention is as follows:

[0063] Step 1: Establish a simulation model of the new energy sending-end system containing the grid converter and calculate the steady-state operating point of the system.

[0064] Built on the PSASP platform, such as Figure 2 The grid-connected system of the grid-connected new energy source shown in the figure has wind power connected to the grid through grid-connected converters and grid-connected converters respectively. The synchronous generator is stepped up by a transformer and then connected to the new energy source, and then connected to the infinite power system through two transmission lines. Figure 3 (a) in the middle is Figure 2 The system's circuit diagram, Figure 3 (b) in the table is the equivalent circuit, and the system parameters are shown in Table 1.

[0065] Table 1. Parameters of the Sending-End Grid Connection System for Grid-Connected Wind Power Projects

[0066]

[0067] in, and These are the internal electromotive force and power angle of the synchronous generator, respectively. and These are the internal potential and power angle of the grid converter, respectively. The transient reactance of a synchronous generator; For the internal reactance of the grid converter; and These are the voltages at the wind power grid connection point and the infinite power supply, respectively; I G and I wI0 represents the output current of the synchronous generator and the grid-connected wind farm, respectively; I2 represents the transmission line current; the grid-connected wind farm uses an impedance of Z0. w Impedance model; x T x L1 and x L2 The reactances of the transformer, single-circuit line 1, and single-circuit line 2 are respectively; x e This refers to the grounding reactance at the short-circuit point during the fault.

[0068] Step 2: Dynamically equivalence the grid-type converter and synchronous generator in the system to obtain the equivalent machine parameters. Based on this, simplify the original simulation system into an equivalent machine and a grid-connected new energy transmission system.

[0069] (1)

[0070] Where: x1 represents the equivalent reactance of the equivalent machine; and These are the internal electromotive force and power angle of the isoelectric machine, respectively; T G* and T GFM* The inertial time constants of synchronous generators and grid-connected wind power, respectively (based on the system reference capacity S). B (Based on); S G and S GFM Rated capacity for synchronous generators and grid-connected wind power; T G and T GFM Synchronous generators and grid-connected wind power, respectively, are represented by their respective capacities S. G and S GFM The inertia time constant is used as the reference; the conversion relationship between the two is:

[0071] (2)

[0072] Will Figure 3 Performing a star-triangular transformation on (b) in the equation, we can obtain... Figure 4 The equivalent impedance of the grid-connected system is shown. It includes: Z 10 and Z 20 The equivalent grounding impedances of the equivalent machine and the infinite power supply, respectively, Z eq This is the equivalent impedance between the equivalent machine and the infinite power supply point.

[0073] (3)

[0074] Where: x2 represents the reactance of line 2, Z f This indicates the equivalent grounding impedance of the wind farm connected to the grid.

[0075] Step 3: Derive the mechanical and electromagnetic power of the equivalent machine before, during, and after the fault to obtain the power angle characteristic curve of the equivalent machine; calculate the acceleration area and maximum deceleration area of ​​the equivalent machine to determine the power angle stability of the system.

[0076] When the system is running normally, the active power output of the grid-connected wind turbine is P. w The reactive power output is 0, and the port voltage is U. w Assume the reactive power compensation capacity of the wind farm is Q. c The equivalent grounding impedance Z of grid-type wind power f for:

[0077] (4)

[0078] The electromagnetic power of the isobaric machine is:

[0079] (5)

[0080] Where x2 represents the total line reactance between the synchronous generator and the new energy grid connection point and the infinite power source; U is the voltage of the infinite power source; x2 = 0.5x L2 x L2 This refers to the line reactance between the synchronous generator and the new energy grid connection point and the infinite power source.

[0081] During a system failure, assuming the grid-connected wind power enters a low-voltage ride-through state, the active power output P of the grid-connected wind turbine will... w And no effort put in Q w Specifically:

[0082] (6)

[0083] Where, k q U is the reactive power support coefficient. in k is the threshold for new energy generating units to enter low-voltage ride-through. p I is the active current coefficient. p0 This refers to the active current during normal operation of the grid-connected wind farm.

[0084] The equivalent grounding impedance of the grid-connected wind farm is:

[0085] (7)

[0086] The electromagnetic power of the isobaric machine is expressed as:

[0087] (8)

[0088] After the fault is cleared, the electromagnetic power expression of the equalization machine is consistent with equation (5), but x2=x L2 .

[0089] Mechanical power: Let the steady-state output of the synchronous generator be P. G The total active power output of the new energy power station is P T The output of the grid-connected wind power and the grid-connected converter are respectively P w and P GFM And satisfy P w +P GFM =P T The capacity ratio λ of a grid-type converter is defined as λ = P. GFM / P T Then the mechanical power of the equivalent unit during normal operation, during a fault, and after the fault is cleared is:

[0090] (9)

[0091] Based on the mechanical and electromagnetic power of the equivalent generator before, during, and after the fault, and taking λ as 0% and 15% respectively, the equivalent generator power angle curves of the grid converter under different percentages are obtained, such as... Figure 5 As shown in the figure, the solid line represents the power angle characteristic curve of the equivalent generator when the synchronous generator output is 300MW, the total output of new energy sources is 360MW, and the grid-connected new energy capacity is 0. In this case, ABCD represents the acceleration area of ​​the equivalent generator, and CEF represents the maximum deceleration area. When the proportion of grid-connected new energy sources is 15%, the dashed line af represents the mechanical power of the equivalent generator, the dashed line bc represents the electromagnetic power of the equivalent generator during a fault, and the dashed line df represents the electromagnetic power of the equivalent generator after the fault is cleared. In this case, abcd represents the acceleration area of ​​the equivalent generator, and cef represents the maximum deceleration area. It can be seen that as the proportion of grid-connected new energy sources increases, the acceleration area of ​​the equivalent generator decreases, the maximum deceleration area increases, and the system power angle stability improves.

[0092] Step 4: Use the bisection method to obtain the proportion of grid-type new energy sources with equivalent power machines under the critical power angle stability, and use it as the proportion of grid-type converters under the system power angle stability boundary;

[0093] Step 4.1: According to the definition of λ, the lower limit of λ is a0=0, and the upper limit of λ is b0=1. Using the bisection method λ0=(a0+b0) / 2=0.5, calculate the system power flow when λ0=0.5, and equate the synchronous generator with the grid-type converter.

[0094] Step 4.2: Calculate the mechanical and electromagnetic power of the equivalent machine before, during, and after the fault when λ0=0.5. Based on this, calculate the acceleration area S of the equivalent machine. + and maximum deceleration area S -max ;

[0095] Step 4.3, if S + >S -maxIncrease λ0; if S + -max Then decrease λ0. When λ0 increases or decreases, the dichotomy principle applies. When it increases: a n+1 =λ n b n+1 =b n When decreasing: a n+1 =a n b n+1 =λ n (n=0,1,2,…), where λ n , a n , b n Let λ represent the capacity ratio of the grid-type converter and its lower and upper limits, respectively, in the nth iteration. n+1 , a n+1 , b n+1 These represent the capacity ratio of the grid-type converter and its lower and upper limits, respectively, in the (n+1)th iteration.

[0096] Step 4.4: Return to step 4.1 and iterate until |S + -S -max |<ε (ε is a set small positive value). The iteration ends, and the result λ is output.

[0097] The acceleration area and maximum deceleration area of ​​the equivalent machine under different λ values ​​were calculated using the bisection method, as shown in Table 2.

[0098] Table 2. Acceleration area and maximum deceleration area of ​​the equivalent machine under different λ values.

[0099]

[0100] As shown in Table 2, when the grid-connected converter accounts for 10% of the total power, the difference between the acceleration area and the maximum deceleration area is 0.0083, indicating that the system is close to the critical power angle stability. When this proportion is increased, the maximum deceleration area is greater than the acceleration area, and the system's transient power angle stabilizes.

[0101] Step 5: Perform simulation based on the PSASP platform to verify the rationality of the proposed configuration principle.

[0102] Based on the PSASP platform, Figure 2 Taking the system shown as an example, the system base capacity is 250MVA, where the synchronous generator output power is 1.0+j0.5, and the active power output of the renewable energy power station is 300MW. The disturbance is set as a grounding event occurring at the beginning of one circuit of transmission line 2 at t=1s, with a reactance of x. e ​A three-phase short-circuit fault with a power output of 0.04 pu lasted for 1 second, after which the next circuit was disconnected. Simulation analysis of the equivalent turbine power angle curves under different grid wind power ratios is shown below. Figure 6 .

[0103] from Figure 6 It can be seen that when the proportion of grid-connected converters is 6.6% and 7%, the equivalent machine power angle becomes unstable, and the instability is more severe when the proportion of grid-connected converters is 6.6%. When the proportion of grid-connected converters is 10%, the critical power angle of the equivalent machine stabilizes. When the proportion of grid-connected converters increases to 50%, the system power angle stabilizes. This is consistent with the results calculated using the bisection method.

[0104] The power angle curves of the synchronous generator and the grid-connected converter under two operating conditions—equivalent power angle instability and critical power angle stability—are as follows: Figure 7 As shown. From Figure 7 It can be seen that the power angles of the synchronous generator and the grid converter change in a basically synchronous manner, indicating the feasibility of making them dynamically equal.

[0105] This invention also discloses a high-proportion renewable energy transmission-end system and grid converter capacity configuration system considering the power angle stability boundary, comprising:

[0106] Equivalent unit: Dynamically equivalentize grid-connected wind power with synchronous generators to obtain equivalent machine parameters;

[0107] Calculation unit: Calculates the electromagnetic power and mechanical power of the equivalent machine before, during and after the fault, and obtains the power angle characteristic curve of the equivalent machine accordingly, and further calculates the acceleration area and the maximum deceleration area.

[0108] Search Unit: Using the bisection method, the search is performed to determine the capacity ratio of the grid-connected converter under the power angle stability boundary.

[0109] Simulation Unit: Based on the PSASP platform, a high-proportion renewable energy transmission system model with grid-connected wind power is established, and disturbance simulation analysis is performed to analyze the power angle stability of the system under different grid-connected converter capacity ratios.

Claims

1. A method for configuring capacity of a new energy grid-connected / inverter based on a power angle stability boundary, characterized in that, Comprising the following steps: Step 1, based on wind power new energy data and synchronous generator power, a new energy sending end system simulation model including grid-connected type converter and grid-constructing type converter is constructed, and the steady-state operating point of the new energy sending end system is calculated; Step 2, based on the steady-state operating point, the grid-constructing type converter and the synchronous generator in the new energy sending end system are dynamically equivalent, and the equivalent machine parameters are obtained; Step 3, the mechanical power and electromagnetic power of the equivalent machine before, during and after the fault are obtained, the power angle characteristic curve of the equivalent machine is obtained, the acceleration area and the maximum deceleration area of the equivalent machine are calculated, and the power angle stability of the new energy sending end system is judged; Step 3 specifically comprises the following steps: Step 3.1, when the system is running normally, the active power of the grid-connected wind turbine is P w , the reactive power is 0, and the port voltage is U w ; assuming that the reactive power compensation capacity of the wind farm is Q c , and the equivalent ground impedance Z f of the grid-connected wind power is: (4) wherein Z w represents the equivalent impedance of the wind farm, and j represents the imaginary unit; The electromagnetic power of the equivalent machine is: (5) Wherein, x2 represents the total line reactance between the synchronous generator and the new energy grid connection point and the infinite power supply; U is the voltage of the infinite power supply; x2=0.5x L2 , x L2 is the line reactance between the synchronous generator and the new energy grid connection point and the infinite power supply; Step 3.2, during the fault, the grid-following wind power enters a low voltage ride through state, the active power P w and the reactive power Q w Specifically: (6) wherein k q is the reactive support coefficient, U in is the threshold for the low-voltage ride-through of new energy units, k p is the active current coefficient, I p is the active current of the grid-connected wind farm, I p0 is the active current of the grid-connected wind farm in normal operation; The equivalent ground impedance of the grid-connected wind farm is: (7) where x e is the fault point grounding reactance, and j is the imaginary unit. The electromagnetic power of the equivalent machine is expressed as: (8) Step 3.3, After the fault is removed, the electromagnetic power expression of the equivalent machine is consistent with formula (5), but x2=x L2 ; Step 3.4, set the steady-state output of the synchronous generator as P G , the total active power of the new energy station as P T , wherein the active power of the grid-connected wind turbine and the grid-forming converter is P w and P GFM , respectively, and P w + P GFM =P T , the capacity proportion of the grid-forming converter is defined as λ=P GFM / P T , and the mechanical power of the equivalent machine during normal operation, fault, and after fault elimination is: (9) Step 3.5, the acceleration area and the deceleration area of the equivalent machine are calculated, and the power angle stability of the system is judged; Step 4, the proportion of grid-constructing type new energy under the critical power angle stability of the equivalent machine is obtained by using the dichotomy method, which is taken as the proportion of the grid-constructing type converter under the power angle stability boundary, and the configuration of the new energy grid-connected / grid-constructing converter capacity is completed. 2.The method of claim 1, wherein, The step 1 is specifically: based on a power system analysis integrated program (PSASP) platform, a wind power sending system is established, wind power new energy is connected to the grid through a grid-following type converter and a grid-constructing type converter respectively, a synchronous generator is boosted through a transformer and is gathered with the wind power new energy, and then is connected to an infinite system through two transmission lines; according to network parameters, wind power and synchronous generator power, based on a power flow equation, steady-state values of each node voltage, virtual internal electric potential of the grid-constructing type wind power and virtual power angle, and steady-state values of the synchronous generator internal electric potential and power angle are calculated. .​​​ 3. The method of claim 2, wherein, Step 2 specifically comprises the following steps: Step 2.1, according to the voltage source characteristics of the grid-constructing type wind power and the synchronous generator, the grid-constructing type wind power and the synchronous generator are dynamically equivalent, and the equivalent parameters are: (1) (2) Wherein: and are the internal potential and power angle of the equivalent machine, respectively; x1 represents the equivalent reactance of the equivalent machine; x GFM represents the virtual reactance of the grid-connected wind power; is the transient reactance of the synchronous generator; x T and x L1 are the reactances of the transformer and the single-circuit line 1 passed by the synchronous generator, respectively; T G* and T GFM* are the inertia time constants of the synchronous generator and the grid-connected wind power, respectively, and are based on the system reference capacity S B ; S G and S GFM are the rated capacities of the synchronous generator and the grid-connected wind power; T G and T GFM are the inertia time constants of the synchronous generator and the grid-connected wind power based on their respective capacities S G and S GFM , and the conversion relationship is: (3) Step 2.2, the star-delta transformation is carried out on the equivalent machine grid-connected system to obtain the impedance of the grid-connected system, including the equivalent ground impedance of the equivalent machine, the equivalent ground impedance of the infinite power source and the equivalent impedance between the equivalent machine and the infinite power source. 4.The method of claim 1, wherein, Step 4 specifically comprises the following steps: Step 4.1, according to the definition of the capacity proportion of the grid-constructing type converter, the numerical lower limit a0=0 and the numerical upper limit b0=1 of λ are obtained, and according to the dichotomy method λ0=(a0+b0) / 2=0.5 The system power flow under λ0=0.5 is calculated, and the synchronous generator and the grid-constructing type converter are equivalent; Step 4.2, Calculate the mechanical power and electromagnetic power of the equivalent machine under λ0=0.5 before the fault, during the fault and after the fault, and calculate the accelerating area S of the equivalent machine + and the maximum decelerating area S -max ; Step 4.3, if S + > -max , increase λ0; if S + < S -max , decrease λ0; when λ0 increases or decreases, the bisection principle is adopted; when increasing: a n+1 = λ n , b n+1 = b n , when decreasing: a n+1 = a n , b n+1 = λ n ; wherein λ n 、 a n 、 b n respectively represent the capacity proportion of the grid-forming type converter and its lower limit and upper limit at the n th iteration, λ n+1 、 a n+1 、 b n+1 respectively represent the capacity proportion of the grid-forming type converter and its lower limit and upper limit at the n+1 th iteration; Step 4.

4. Repeat Step 4.2-4.3, loop iteration until |S + - S -max | < ε, ε is a positive value set; after iteration, output λ result.

5. A new energy follow / network converter capacity configuration system based on power angle stability boundary, for realizing the method of claim 1, characterized in that, It includes: Equivalent unit: dynamically equivalent grid-constructing type wind power and synchronous generator to obtain equivalent machine parameters; Calculation unit: calculate the electromagnetic power and mechanical power of the equivalent machine before, during and after the fault, obtain the power angle characteristic curve of the equivalent machine, and calculate the acceleration area and the maximum deceleration area; Search unit: using dichotomy method, search the proportion of grid-constructing type converter capacity under the power angle stability boundary of the equivalent machine; Simulation unit: based on PSASP platform, a high proportion of new energy sending out system model containing grid-constructing type wind power is established, and the power angle stability of the system under different grid-constructing type converter capacity proportion is analyzed by setting disturbance simulation.

6. A computer apparatus comprising a memory, a processor, and a computer program stored on the memory, wherein the computer program, when executed by the processor, causes the processor to perform the method of any one of claims 1 to 5. The processor executes the computer program to realize the steps of the method of claim 1.

7. A computer readable storage medium having stored thereon computer programs / instructions, characterized in that, The computer program / instructions are executed by the processor to realize the steps of the method of claim 1.

8. A computer program product comprising computer programs / instructions, characterized in that, The computer program / instructions are executed by the processor to realize the steps of the method of claim 1.

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