Frequency response time correction calculation method of variable inertia new energy power generation system

Abstract

The invention discloses a frequency response time correction calculation method of a variable inertia new energy power generation system. The method comprises the following steps: step 1, constructing a frequency response model of the constant inertia fan grid-connected system and obtaining a system frequency response expression; 2, calculating the frequency reduction duration of the constant inertia fan system, and determining the relationship between the time and the system parameters; 3, calculating the equivalent inertia of the variable inertia fan grid-connected system according to the inertia response capability of the system; and step 4, in combination with frequency safety constraints and error analysis requirements, through iterative correction calculation, realizing and proposing a system inertia and frequency response time correction calculation method based on the system load and the fan rotating speed. According to the frequency response time calculation method of the variable inertia new energy power generation system, the frequency dynamic characteristics of the variable inertia wind turbine grid-connected system can be accurately evaluated, and a key parameter calculation method can be provided for the duration of the wind turbine participating in frequency support.

Description

Technical Field

[0001] The present invention relates to the field of inertia demand assessment of new power systems with high penetration of new energy, and in particular to a frequency response time correction calculation method for a variable inertia new energy power generation system. Background Art

[0002] In power generation systems, frequency response time is an important indicator for measuring system stability and regulation capabilities. When a disturbance occurs in the system, the rate of frequency decrease and the time required to reach the minimum value are closely related to the inertia of the system. With the rapid development of new energy power generation technology, especially the widespread application of intermittent energy represented by wind energy, changes in system inertia have a significant impact on frequency response. Traditional frequency response time calculation methods are often based on fixed system inertia and cannot accurately reflect the dynamic characteristics of the system under variable inertia conditions. Therefore, accurate calculation of frequency response time is of great significance for evaluating the inertia characteristics of the system, predicting the dynamic behavior of the system, and formulating effective control strategies. Summary of the invention

[0003] The present invention provides a frequency response time correction calculation method for a variable inertia new energy power generation system. First, a frequency response model of a constant inertia wind turbine grid-connected system is constructed and a system frequency response expression is obtained; second, the frequency drop duration of the constant inertia wind turbine system is calculated to clarify the relationship between time and system parameters; then, according to the system inertia response capability, the equivalent inertia of the variable inertia wind turbine grid-connected system is calculated; finally, combined with frequency safety constraints and error analysis requirements, through iterative correction calculation, a correction calculation method for system inertia and frequency response time based on system load and wind turbine speed is realized and proposed.

[0004] To achieve the above object, the present invention provides the following solutions:

[0005] A frequency response time correction calculation method for a variable inertia new energy power generation system comprises the following steps:

[0006] Step 1: Construct a frequency response model of a constant inertia wind turbine grid-connected system and obtain the system frequency response expression;

[0007] Step 2: Calculate the frequency drop duration of the constant inertia fan system and clarify the relationship between time and system parameters;

[0008] Step 3: Calculate the equivalent inertia of the variable inertia wind turbine grid-connected system based on the system inertia response capability;

[0009] Step 4: Combined with the frequency safety constraints and error analysis requirements, through iterative correction calculation, a correction calculation method for system inertia and frequency response time based on system load and fan speed is implemented and proposed.

[0010] Optionally, the step 1: constructing a frequency response model of a constant inertia wind turbine grid-connected system and obtaining a system frequency response expression specifically includes:

[0011] In order to analyze the dynamic frequency characteristics of the wind turbine grid-connected system, the present invention constructs a frequency response model of a high-permeability wind turbine grid-connected system in the complex domain as follows:

[0012]

[0013] In the formula, H S is the system inertia; R is the synchronous machine adjustment coefficient; K L is the load adjustment factor; D sys is the system damping; T G is the time constant of the reheating process; F G is the power ratio of high-pressure turbine; w is the wind power penetration rate of the system.

[0014] Further, the frequency response model of the fan system in the complex domain can be used to obtain the time domain expression of the system frequency response:

[0015]

[0016] Assume that a load disturbance occurs in the system at time 0. The general initial condition at the time of load disturbance is:

[0017]

[0018] Substituting the initial conditions, we can obtain the analytical solution of the differential equation of Δf and time t:

[0019]

[0020] In the formula,

[0021]

[0022] K s =K m +D sys +K L

[0023] Optionally, the step 2: calculating the frequency drop duration of the constant inertia fan system and clarifying the relationship between time and system parameters specifically includes:

[0024] The frequency change Δf and time t in step 1 are derived to obtain the duration t of the system frequency drop. low for:

[0025]

[0026] Calculate A 2 We can get:

[0027]

[0028] A 2 Substituting the expression into coefficient B and simplifying B, we can get:

[0029]

[0030] Substituting the expressions of A and C1 into the coefficient C2 and simplifying, we can obtain:

[0031]

[0032] Combining the obtained C2 with the known expressions of C1 and A, we can get:

[0033]

[0034] From the above formula, we can get:

[0035]

[0036] Substitute expression B into the above formula and simplify it. The analytical expression of the duration of system frequency drop can be expressed as:

[0037]

[0038] Since -arctan(x) = arctan(-x), the above equation can be rearranged as:

[0039]

[0040] From the above formula, we can know that the system frequency decrease duration t low Depends on K s , Synchronous machine reheating process time constant T G And the system inertia H s In addition, in a constant inertia fan system, K s , T G With H s It can be determined at the beginning of the system establishment. Therefore, when other parameters are determined, the system frequency drop duration t low It is also unchanging.

[0041] Optionally, the step 3: calculating the equivalent inertia of the variable inertia wind turbine grid-connected system according to the system inertia response capability, specifically includes:

[0042] After adopting differential control, the fan has the inertial response capability equivalent to that of the synchronous machine, and its virtual inertia can be combined with the inertia of the synchronous machine. sExpressed as:

[0043] H s =H g1 (1-λ w )+H vw λ w

[0044] In the formula, H g1 , H vw They are the synchronous machine inertia and the fan virtual inertia respectively.

[0045] Referring to the definition of synchronous machine inertia time constant, the virtual inertia of the fan can be expressed as:

[0046]

[0047] In the formula, Δω r is the speed change of the wind turbine; Δω e is the synchronous speed change; ω r0 is the initial speed of the fan; ω e is the synchronous speed; H w is the inherent inertia time constant of the fan.

[0048] To ensure the safe operation of the fan, the output power must be limited within the constraint range. When the fan participates in the inertial response, its rotor motion equation can be expressed as:

[0049] ΔP w =P mw -P ew =2H w ω r dω r / dt

[0050] Where ΔP w , P mw , P ew They are the power change, mechanical power and output power of the fan respectively.

[0051] By integrating both sides of the above equation under power constraints, we can get the maximum speed change Δω of the fan during the inertial response time. r , expressed as:

[0052]

[0053] In the formula, k opt is the maximum power tracking proportionality coefficient, P n is the rated power of the fan.

[0054] Taking frequency drop as an example, combined with the above standards and formulas, the equivalent inertia expression of the variable inertia wind turbine grid-connected system can be obtained, which can be expressed as:

[0055]

[0056] Where:

[0057]

[0058] Optionally, the step 4: combining the frequency safety constraint and the error analysis requirement, implementing and proposing a correction calculation method for the system inertia and frequency response time based on the system load and the fan speed through iterative correction calculation, specifically includes:

[0059] Considering that the disturbance power of the load is random, impactful and intermittent in the actual operation of the power grid system, and taking into account the frequency regulation requirements of the system, the present invention uses the historical maximum disturbance power ΔP encountered by the power grid dmax Conservatively evaluate the frequency drop limit of the system, and take ΔP based on the actual operation data of the regional power grid. dmax =0.1P N , this parameter setting can be adjusted according to the actual grid operation status; in addition, when the per-unit value is taken, the system frequency change is consistent with the system speed change, so it can be considered that Δf=Δω e The algorithm of the present invention comprehensively considers the system load disturbance size and the fan speed size, and has the functions of correcting inertia evaluation and frequency reduction duration. The function implementation process is as follows:

[0060] First, the constraints of the frequency change index of the wind turbine grid-connected system are analyzed:

[0061] For Δf max my country has set limits on the frequency fluctuation extremes of the power system. When a large power disturbance occurs, the frequency deviation of the power system shall not exceed 0.5 Hz. st my country's GB / T15945-2008 "Power Quality Power System Frequency Deviation" stipulates that the frequency steady-state deviation limit under normal operating conditions of the power system is ±0.2Hz. Therefore, the present invention takes the steady-state frequency deviation value not higher than ±0.2Hz as a constraint condition.

[0062] Secondly, the initial value of the correction method is calculated. The present invention uses the system inertia H when the fan has no inertial response s Take H s0 And use it as the initial value of the corrected calculation system inertia, and then according to the expression of the system frequency drop duration and the fan speed change, the initial value of the system drop duration t can be obtained low0 , initial value of system speed change Δω e0 and the initial value of the fan speed change Δω r0 .

[0063] Next, combined with the initial value of the system drop duration tlow0 , initial value of system speed change Δω e0 and the initial value of the fan speed change Δω r0 The system inertia H after correction can be obtained s1 , using the new system inertia H s1 , we can get the system drop duration t after correction low1 , System speed change Δω e1 and the fan speed change Δω r1 .

[0064] Finally, repeat the above process to calculate the system frequency change Δf each time. e , at this time, it is necessary to determine whether it meets the frequency steady-state deviation constraint; when Δf e When Δf >0.2Hz, further correction calculation is required until the frequency steady-state deviation constraint is met; when Δf e When ≤0.2Hz, it is considered that the frequency safety requirement can be met. On the basis of meeting the frequency safety requirement, error analysis is performed. This article takes the error of two times less than 5% as a constraint condition. If you want to get a more accurate value, you can actually adjust it. So far, the key points of the present invention have been mentioned.

[0065] Compared with the existing technology, this technology has the following beneficial effects:

[0066] The present invention provides a frequency response time correction calculation method for a variable inertia new energy power generation system. The more accurate inertia of the system can be evaluated by the correction calculation method, and based on the inertia, the response time of the system frequency dropping to the lowest point after the system is disturbed by power can be obtained. Compared with the calculation error caused by the fixed inertia assumption of the traditional method, this method can more accurately reflect the dynamic inertia characteristics of the wind turbine in actual operation, which helps the power grid to maintain frequency stability when the wind speed changes suddenly or the load fluctuates, and enhances the stability of the entire power system.

[0067] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative labor.

[0068] Figure 1 is a flow chart of a frequency response time correction calculation method of a variable inertia new energy power generation system according to an embodiment of the present invention;

[0069] Figure 2 It is a flow chart of a method for calculating the correction of virtual inertia and frequency response time of a variable inertia new energy power generation system according to an embodiment of the present invention;

[0070] Figure 3 It is the evaluation result of the system frequency response time under variable inertia according to the embodiment of the present invention. DETAILED DESCRIPTION

[0071] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0072] The present invention provides a method for evaluating virtual inertia of a wind turbine based on measuring wind speed changes. In order to make the above-mentioned objects, features and advantages of the present invention more obvious and understandable through calculation, the present invention is further described in detail below in conjunction with the accompanying drawings and specific implementation methods.

[0073] Figure 1 : is a flow chart of a frequency response time correction calculation method for a variable inertia new energy power generation system according to an embodiment of the present invention. Figure 1 As shown, the following steps are included:

[0074] Step 1: Construct a frequency response model of a constant inertia wind turbine grid-connected system and obtain the system frequency response expression;

[0075] Step 2: Calculate the frequency drop duration of the constant inertia fan system and clarify the relationship between time and system parameters;

[0076] Step 3: Calculate the equivalent inertia of the variable inertia wind turbine grid-connected system based on the system inertia response capability;

[0077] Step 4: Combined with the frequency safety constraints and error analysis requirements, through iterative correction calculation, a correction calculation method for system inertia and frequency response time based on system load and fan speed is implemented and proposed.

[0078] Firstly, the frequency response model of the high penetration wind turbine grid-connected system in the complex domain is constructed, which can be expressed as:

[0079]

[0080] In the formula, H S is the system inertia; R is the synchronous machine adjustment coefficient; K L is the load adjustment factor; D sys is the system damping; T G is the time constant of the reheating process; F G is the power ratio of high-pressure turbine; w is the wind power penetration rate of the system.

[0081] Further, the frequency response model of the fan system in the complex domain can be used to obtain the time domain expression of the system frequency response:

[0082]

[0083] Assume that a load disturbance occurs in the system at time 0. The general initial condition at the time of load disturbance is:

[0084]

[0085] Substituting the initial conditions, we can obtain the analytical solution of the differential equation of Δf and time t:

[0086]

[0087] In the formula,

[0088]

[0089] By taking the derivative of equation (4), we can calculate the system frequency drop duration t low for:

[0090]

[0091] Calculate A 2 We can get:

[0092]

[0093] Substituting equation (7) into coefficient B and simplifying B, we can obtain:

[0094]

[0095] Substituting the expressions of A and C1 into the coefficient C2 and simplifying, we get:

[0096]

[0097] Combining the obtained C2 with the known expressions of C1 and A, we can get:

[0098]

[0099] From formula (10), we can get:

[0100]

[0101] Substituting expression B into equation (11) and simplifying it, the analytical expression of the duration of system frequency drop can be expressed as:

[0102]

[0103] Since -arctan(x) = arctan(-x), the above equation can be rearranged as:

[0104]

[0105] From formula (13), we can know that the system frequency drop duration t low Depends on K s , Synchronous machine reheating process time constant T G And the system inertia H s In addition, in a constant inertia fan system, K s , T G With H s It can be determined at the beginning of the system establishment. Therefore, when other parameters are determined, the system frequency drop duration t low It is also unchanging.

[0106] After adopting differential control, the fan has the inertial response capability equivalent to that of the synchronous machine, and its virtual inertia can be combined with the inertia of the synchronous machine. s Expressed as:

[0107] H s =H g1 (1-λ w )+H vw λ w (14)

[0108] In the formula, H g1 , H vw They are the synchronous machine inertia and the fan virtual inertia respectively.

[0109] Referring to the definition of synchronous machine inertia time constant, the virtual inertia of the fan can be expressed as:

[0110]

[0111] In the formula, Δω r is the speed change of the wind turbine; Δω e is the synchronous speed change; ω r0 is the initial speed of the fan; ω e is the synchronous speed; H w is the inherent inertia time constant of the fan.

[0112] To ensure the safe operation of the fan, the output power must be limited within the constraint range. When the fan participates in the inertial response, its rotor motion equation can be expressed as:

[0113] ΔP w =P mw -P ew =2Hw ω r dω r / dt (16)

[0114] In the formula, ΔP w , P mw , P ew They are the power change, mechanical power and output power of the fan respectively.

[0115] By integrating both sides of the above equation under power constraints, we can get the maximum speed change Δω of the fan during the inertial response time. r , expressed as:

[0116]

[0117] In the formula, k opt is the maximum power tracking proportionality coefficient, P n is the rated power of the fan.

[0118] Taking frequency drop as an example, combined with the above formula, the equivalent inertia expression of the variable inertia wind turbine grid-connected system can be obtained, which can be expressed as:

[0119]

[0120] Where:

[0121]

[0122] Figure 2 This is a flow chart of the virtual inertia and frequency response time correction calculation method based on the variable inertia new energy power generation system of the present invention. Considering that the load disturbance power is random, impactful and intermittent in the actual operation of the power grid system, and taking into account the frequency regulation requirements of the system, the present invention takes the historical maximum disturbance power ΔP encountered by the power grid as dmax Conservatively evaluate the frequency drop limit of the system, and take ΔP based on the actual operation data of the regional power grid. dmax =0.1P N , this parameter setting can be adjusted according to the actual grid operation status; in addition, when the per-unit value is taken, the system frequency change is consistent with the system speed change, so it can be considered that Δf=Δω e The algorithm of the present invention comprehensively considers the system load disturbance size and the fan speed size, and has the functions of correcting inertia evaluation and frequency reduction duration. The function implementation process is as follows:

[0123] First, the constraints of the frequency change index of the wind turbine grid-connected system are analyzed:

[0124] For Δf maxmy country has set limits on the frequency fluctuation extremes of the power system. When a large power disturbance occurs, the frequency deviation of the power system shall not exceed 0.5 Hz. st my country's GB / T15945-2008 "Power Quality Power System Frequency Deviation" stipulates that the frequency steady-state deviation limit under normal operating conditions of the power system is ±0.2Hz. Therefore, the present invention takes the steady-state frequency deviation value not higher than ±0.2Hz as a constraint condition.

[0125] Secondly, the initial value of the correction method is calculated. The present invention uses the system inertia H when the fan has no inertial response s Take H s0 And use it as the initial value of the corrected calculation system inertia, and then according to the expression of the system frequency drop duration and the fan speed change, the initial value of the system drop duration t can be obtained low0 , initial value of system speed change Δω e0 and the initial value of the fan speed change Δω r0 .

[0126] Next, combined with the initial value of the system drop duration t low0 , initial value of system speed change Δω e0 and the initial value of the fan speed change Δω r0 The system inertia H after correction can be obtained s1 , using the new system inertia H s1 , we can get the system drop duration t after correction low1 , System speed change Δω e1 and the fan speed change Δω r1 .

[0127] Finally, repeat the above process to calculate the system frequency change Δf each time. e , at this time, it is necessary to determine whether it meets the frequency steady-state deviation constraint; when Δf e When Δf >0.2Hz, further correction calculation is required until the frequency steady-state deviation constraint is met; when Δf e When the value is ≤0.2Hz, it is considered that the frequency safety requirement can be met. On the basis of meeting the frequency safety requirement, error analysis is performed. This paper takes the error of two times less than 5% as a constraint condition. If you want to get a more accurate value, you can adjust it according to the actual situation.

[0128] Figure 3 This is the evaluation result of the system frequency response time under variable inertia according to the embodiment of the present invention, wherein the specific parameters are shown in Table 1 below.

[0129] Table 1 Specific values ​​of fan system parameters

[0130]

Claims

1. The present invention discloses a frequency response time correction calculation method for a variable inertia new energy power generation system, characterized in that: The following steps are involved: Step 1: Construct a frequency response model of a constant inertia wind turbine grid-connected system and obtain the system frequency response expression; Step 2: Calculate the frequency drop duration of the constant inertia fan system and clarify the relationship between time and system parameters; Step 3: Calculate the equivalent inertia of the variable inertia wind turbine grid-connected system based on the system inertia response capability; Step 4: Combined with the frequency safety constraints and error analysis requirements, through iterative correction calculation, a correction calculation method for system inertia and frequency response time based on system load and fan speed is implemented and proposed.

2. The frequency response time correction calculation method of a variable inertia new energy power generation system according to claim 1 is characterized in that: The step 1: constructing a frequency response model of a constant inertia wind turbine grid-connected system and obtaining a system frequency response expression, specifically includes: In order to analyze the dynamic frequency characteristics of the wind turbine grid-connected system, the present invention constructs a frequency response model of a high-permeability wind turbine grid-connected system in the complex domain as follows: In the formula, H S is the system inertia; R is the synchronous machine adjustment coefficient; K L is the load adjustment factor; D sys is the system damping; T G is the time constant of the reheating process; F G is the power ratio of high-pressure turbine; w is the wind power penetration rate of the system. Further, the frequency response model of the fan system in the complex domain can be used to obtain the time domain expression of the system frequency response: Assume that a load disturbance occurs in the system at time 0. The general initial condition at the time of load disturbance is: Substituting the initial conditions, we can obtain the analytical solution of the differential equation of Δf and time t: In the formula, K s =K m +D sys +K L 3. A frequency response time correction calculation method for a variable inertia new energy power generation system according to claim 1. Characterized in that: The step 2: calculating the frequency drop duration of the constant inertia fan system and clarifying the relationship between the time and the system parameters, specifically includes: By taking the derivative of the above time domain expression, we can calculate the duration of system frequency drop t low for: Calculate A 2 We can get: A 2 Substituting the expression into coefficient B and simplifying B, we can get: Substituting the expressions of A and C1 into the coefficient C2 and simplifying, we can obtain: Combining the obtained C2 with the known expressions of C1 and A, we can get: From the above formula, we can get: Substitute expression B into the above formula and simplify it. The analytical expression of the duration of system frequency drop can be expressed as: Since -arctan(x) = arctan(-x), the above equation can be rearranged as: From the above formula, we can know that the system frequency decrease duration t low Depends on K s , Synchronous machine reheating process time constant T G And the system inertia H s In addition, in a constant inertia fan system, K s , T G With H s It can be determined at the beginning of the system establishment. Therefore, when other parameters are determined, the system frequency drop duration t low It is also unchanging.

4. The frequency response time correction calculation method of a variable inertia new energy power generation system according to claim 1 is characterized in that: The step 3: combining the inertial response capability of the wind turbine and the output power constraint of the wind turbine, calculating the equivalent inertia of the variable inertia wind turbine grid-connected system, specifically includes: After adopting differential control, the fan has the inertial response capability equivalent to that of the synchronous machine, and its virtual inertia can be combined with the inertia of the synchronous machine. s Expressed as: H s =H g1 (1-l w )+H vw l w In the formula, H g1 , H vw They are the synchronous machine inertia and the fan virtual inertia respectively. Referring to the definition of synchronous machine inertia time constant, the virtual inertia of the fan can be expressed as: In the formula, Δω r is the speed change of the wind turbine; Δω e is the synchronous speed change; ω r0 is the initial speed of the fan; ω e is the synchronous speed; H w is the inherent inertia time constant of the fan. To ensure the safe operation of the fan, the output power must be limited within the constraint range. When the fan participates in the inertial response, its rotor motion equation can be expressed as: ΔP w =P mw -P ew =2H w ω r dω r / dt Where ΔP w , P mw , P ew They are the power change, mechanical power and output power of the fan respectively. By integrating both sides of the above equation under power constraints, we can get the maximum speed change Δω of the fan during the inertial response time. r , expressed as: In the formula, k opt is the maximum power tracking proportionality coefficient, P n is the rated power of the fan. Taking frequency drop as an example, combined with the above content, the equivalent inertia expression of the variable inertia wind turbine grid-connected system can be obtained, which can be expressed as: Where:

5. The frequency response time correction calculation method of a variable inertia new energy power generation system according to claim 1 is characterized in that: Step 4: combining frequency safety constraints and error analysis requirements, through iterative correction calculation, a correction calculation method for system inertia and frequency response time based on system load and fan speed is implemented and proposed, specifically including: Considering that the disturbance power of the load is random, impactful and intermittent in the actual operation of the power grid system, and taking into account the frequency regulation requirements of the system, the present invention uses the historical maximum disturbance power ΔP encountered by the power grid dmax Conservatively evaluate the frequency drop limit of the system, and take ΔP based on the actual operation data of the regional power grid. dmax =0.1P N , this parameter setting can be adjusted according to the actual grid operation status; in addition, when the per-unit value is taken, the system frequency change is consistent with the system speed change, so it can be considered that Δf=Δω e The algorithm of the present invention comprehensively considers the system load disturbance size and the fan speed size, and has the functions of correcting inertia evaluation and frequency reduction duration. The function implementation process is as follows: First, the constraints of the frequency change index of the wind turbine grid-connected system are analyzed: For Δf max my country has set limits on the frequency fluctuation extremes of the power system. When a large power disturbance occurs, the frequency deviation of the power system shall not exceed 0.5 Hz. st my country's GB / T15945-2008 "Power Quality Power System Frequency Deviation" stipulates that the frequency steady-state deviation limit under normal operating conditions of the power system is ±0.2Hz. Therefore, the present invention takes the steady-state frequency deviation value not higher than ±0.2Hz as a constraint condition. Secondly, the initial value of the correction method is calculated. The present invention uses the system inertia H when the fan has no inertial response s Take H s0 And use it as the initial value of the corrected calculation system inertia, and then according to the expression of the system frequency drop duration and the fan speed change, the initial value of the system drop duration t can be obtained low0 , initial value of system speed change Δω e0 and the initial value of the fan speed change Δω r0 . Next, combined with the initial value of the system drop duration t low0 , initial value of system speed change Δω e0 and the initial value of the fan speed change Δω r0 The system inertia H after correction can be obtained s1 , using the new system inertia H s1 , we can get the system drop duration t after correction low1 , System speed change Δω e1 and the fan speed change Δω r1 . Finally, repeat the above process to calculate the system frequency change Δf each time. e , at this time, it is necessary to determine whether it meets the frequency steady-state deviation constraint; when Δf e When Δf >0.2Hz, further correction calculation is required until the frequency steady-state deviation constraint is met; when Δf e When ≤0.2Hz, it is considered that the frequency safety requirement can be met. On the basis of meeting the frequency safety requirement, error analysis is performed. This article takes the error of two times less than 5% as a constraint condition. If you want to get a more accurate value, you can actually adjust it. So far, the key points of the present invention have been mentioned.

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