Method for evaluating multi-region hierarchical rotational inertia of high-permeability new energy large power grid

Abstract

The invention belongs to the technical field of rotational inertia evaluation, and relates to a high-permeability new energy large power grid multi-region hierarchical rotational inertia evaluation method, which comprises the following steps: reading power grid operation data, unit model parameters and configuration files; calling a model parameter file and a power grid configuration file of a started unit or a pre-started unit as basic data for evaluation and calculation; calculating the rotational inertia margin, the maximum perturbation capable of being borne by the system, the inertia perturbation ratio and the critical inertia perturbation ratio; and according to different index levels, setting the alarm area to be red, setting the qualified area to be blue, setting the excellent area to be green, and displaying a calculation result through a visual map interface. According to the evaluation method, the frequency deviation constraint and the frequency change rate constraint in the dispatching system are comprehensively considered, the rotational inertia level of the power system containing the high-proportion new energy is evaluated for different areas, reference and early warning can be provided for actual operation of a power grid, and safety and stability of the system are guaranteed.

Description

Technical Field

[0001] The present invention belongs to the technical field of moment of inertia assessment in power grid planning and operation, and specifically relates to a multi-region hierarchical and graded moment of inertia assessment method for a large power grid under high-penetration new energy. Background Art

[0002] With the commissioning of UHV DC supporting wind power and new energy projects in key areas, the future large power grid will continue to present the characteristics of "high proportion of DC transmission, large-scale centralized access to new energy, and high penetration of new energy grid connection". Due to the intermittent and uncertain output of new energy, the operation mode is highly random and the control strategy is highly real-time. In addition, the unit itself has a small moment of inertia and small adjustable capacity, so an external synchronous generator set is required to provide inertia support during operation.

[0003] Affected by the distribution of energy resources, the distribution of rotational inertia in most regions is inversely distributed with new energy. Regions with a high penetration rate of stable power sources have higher rotational inertia. The centralized connection of a large number of new energy sources to the grid will aggravate the reduction of the system inertia support capacity in weak areas, change the spatial distribution characteristics of the inertia of the large power grid, and seriously affect the safe and stable operation of the large power grid. Therefore, it is very necessary to evaluate the rotational inertia level of different regions under high penetration rates of new energy sources, which can provide reference and early warning for the actual operation of the power grid and ensure the safety and stability of the system.

[0004] At present, the impact of new energy on the system's rotational inertia is mostly at the qualitative or small system level, and there is a lack of relevant quantitative or more intuitive representation methods. Based on this, it is urgent to develop a new power system rotational inertia assessment method that is quantitative and intuitive for the operation mode of large power grids, so as to actually guide the dispatching and operation of power grids. Summary of the invention

[0005] The purpose of the present invention is to provide a method for evaluating the moment of inertia of multiple regions in a large power grid under high penetration of new energy, so as to solve the problem of evaluating the level of moment of inertia of each region and each level under different operating modes of the power grid, providing reference and early warning for the actual operation of the power grid, and ensuring the safety and stability of the system.

[0006] The objective of the present invention is achieved through the following technical solutions:

[0007] A multi-region hierarchical and graded moment of inertia assessment method for a large power grid with high penetration rate of new energy comprises the following steps:

[0008] A. Reading grid operation data, unit model parameters and configuration files: Reading the real-time or predicted operation mode of the grid, retrieving the model parameter files of the started units or the units to be started and the grid configuration files as the basic data for evaluation and calculation;

[0009] B. Calculate the rotational inertia margin, the maximum disturbance that the system can withstand, the inertia disturbance ratio and the critical inertia disturbance ratio: First, perform online or offline data integration through the unit model parameters to determine the type of each unit, determine the grid zone to which the unit belongs through the grid configuration file, and calculate the rotational inertia value of each area of ​​the grid; second, according to the preset disturbance set, call the evaluation algorithm and frequency constraints to calculate the evaluation index value of each area within the grid; finally, form a set of rotational inertia evaluation indicators for each area of ​​the grid under this operation mode;

[0010] C. According to different indicator levels, the warning area is set to red, the qualified area is set to blue, and the excellent area is set to green, and the calculation results are displayed through a visual map interface.

[0011] Furthermore, in step B, the minimum inertia requirement under the preset disturbance is evaluated and the rotational inertia margin is calculated by considering the frequency deviation and the rate of change constraint.

[0012] Furthermore, the specific steps for calculating the moment of inertia margin are:

[0013] a. Consider low-frequency constraints

[0014] Based on the real-time operation status of the power grid, the equivalent parameters of the system frequency response model in the current state are obtained, the frequency modulation gain of new energy is ignored, and a simplified frequency analysis model is established, considering the low-frequency limit H in the actual operation process. low , evaluate the minimum inertia requirement under low frequency constraints;

[0015] b. Consider high frequency constraints

[0016] For the case of increased frequency, according to the generator rotor swing equation, the frequency deviation Δf(t) considering the inertia and load damping effects can be expressed as follows:

[0017]

[0018] Among them, H sys is the system equivalent inertia constant, ΔP is the active disturbance power;

[0019] Minimum inertia requirement H considering high frequency constraints high The expression is:

[0020]

[0021] in, is the high frequency threshold, f0 is the rated frequency, ΔP is the active disturbance power;

[0022] c. Consider frequency change constraints

[0023] At the moment of disturbance, the frequency deviation has not yet occurred, the generator speed regulator has not acted, and the load frequency regulation effect has not yet taken effect. At this time, the frequency change rate is the largest. The system frequency change depends on the inertia and the disturbance power. Considering the minimum inertia requirement H constrained by the frequency change rate R The expression is:

[0024]

[0025] Among them, f R,limit is the system frequency change rate, ΔP is the active disturbance power;

[0026] d. Moment of inertia margin

[0027] The expression of the system minimum inertia requirement Hmin that meets the grid frequency deviation and change rate constraints is as follows:

[0028] H min =max(H low , H high , H R )

[0029] Moment of inertia margin K m Reflects the relative distance between the current inertia level J and the minimum inertia Jmin requirement:

[0030]

[0031] Furthermore, in step B, the specific steps of calculating the maximum disturbance that the region can withstand are:

[0032] Considering the frequency deviation and change rate constraints, under the current operation mode, the maximum disturbance power ΔP that the system can withstand is max for:

[0033] ΔP max =min(ΔP low , ΔP high , ΔP R )

[0034] In the formula, ΔP low , ΔP high , ΔP R They are the maximum disturbance that can be tolerated under low-frequency constraints, high-frequency constraints and frequency change constraints.

[0035] Furthermore, in step B, the specific steps of calculating the inertia disturbance ratio are:

[0036] When the preset disturbance is ΔP, the inertia disturbance ratio K sys for:

[0037]

[0038] Online calculation and monitoring can be realized according to the above formula.

[0039] Among them, J sys is the moment of inertia of the system, ω0 is the rated electrical angular velocity, S ∑ is the system power generation capacity, H sys is the system equivalent inertia constant, ΔP is the active disturbance power.

[0040] Furthermore, in step B, the specific steps of calculating the critical inertia disturbance ratio are:

[0041] When ΔP is taken as the maximum disturbance ΔP that the system can withstand max According to the index definition, the inertia disturbance ratio under this disturbance is the critical inertia disturbance ratio K sys，min :

[0042]

[0043] Among them, J sys is the moment of inertia of the system, ω0 is the rated electrical angular velocity, S ∑ is the system power generation capacity, H sys is the system equivalent inertia constant, ΔP is the active disturbance power;

[0044] The minimum inertia requirement index H evaluated when the preset disturbance is ΔP min , when the system power structure changes and the system inertia level is reduced to H min When K sys，min The indicator expression is:

[0045]

[0046] Among them, the inertia disturbance ratio index K sys Used to characterize the strength of the power grid frequency support capability under the current disturbance, critical inertia disturbance ratio index K sys，min It is used to characterize the minimum frequency support strength required to maintain the frequency stability of the power grid. sys，min It's K sys The lower bound of K provides a reference standard for measuring the frequency support capability level, and when the inertia can be monitored, the dispatcher can sys，min Quickly estimate the maximum disturbance power that the power grid can withstand.

[0047] Further, in step C, the area with poor indicators is preferentially set to red and a warning signal is issued.

[0048] Furthermore, if the operation mode changes significantly, the calculation cycle needs to be repeated.

[0049] Compared with the prior art, the present invention has the following beneficial effects:

[0050] The multi-regional hierarchical and graded moment of inertia assessment method for a large power grid with high penetration rate of new energy of the present invention comprehensively considers the frequency deviation constraint and the frequency change rate constraint in the dispatching system, and assesses the moment of inertia level of the power system containing a high proportion of new energy for different regions, which can provide reference and early warning for the actual operation of the power grid and ensure the safety and stability of the system. BRIEF DESCRIPTION OF THE DRAWINGS

[0051] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings required for use in the embodiments are briefly introduced below. It should be understood that the following drawings only show certain embodiments of the present invention and therefore should not be regarded as limiting the scope. For ordinary technicians in this field, other related drawings can be obtained based on these drawings without creative work.

[0052] Figure 1 The present invention is a flow chart of the multi-region hierarchical and graded moment of inertia assessment method for a large high-penetration new energy power grid. DETAILED DESCRIPTION

[0053] The present invention will be further described below in conjunction with embodiments:

[0054] Research has found that new energy units are generally connected to the system through power electronic components and contain almost no effective rotational inertia. As the proportion of new energy in the power grid increases, the displacement effect on conventional units causes the overall inertia of the system to decrease, making the response process of the system frequency after being hit by a power shortage more intense. Based on this, the present invention proposes a multi-region hierarchical and graded rotational inertia assessment method for large power grids under high-penetration new energy, so as to assess the rotational inertia level of each region and each level under different operation modes of the power grid, which can provide reference and early warning for the actual operation of the power grid and ensure the safety and stability of the system. The assessment method of the present invention can be applied to the rotational inertia assessment of each region and each level of a large power grid.

[0055] The present invention first determines the evaluation index, considers the frequency deviation and frequency change rate constraints in the actual dispatching operation of the power grid, and adopts four indicators, namely, the moment of inertia margin, the maximum disturbance that the region can bear, the inertia disturbance ratio and the critical inertia disturbance ratio, to comprehensively measure the moment of inertia levels of different regions. Secondly, the above four evaluation indicators are calculated, and then the calculated evaluation indicators are used for evaluation, and the real-time nature of the startup mode during the actual operation of the power grid is fully considered during the evaluation. Finally, the evaluation results are graded, and areas with poor indicators are warned and marked in red, areas with excellent indicators are marked in green, and areas with average indicators are marked in blue, which intuitively represent the moment of inertia levels of each region.

[0056] like Figure 1 As shown, the multi-region hierarchical and graded moment of inertia assessment method for a large high-penetration new energy power grid of the present invention comprises the following steps:

[0057] 1. Read the grid operation data, unit model parameters and configuration files:

[0058] Read the real-time or predicted operation mode of the power grid, retrieve the model parameter files and power grid configuration files of the started units or the units to be started, and provide basic data for evaluation and calculation.

[0059] 2. Calculate the rotational inertia margin, the maximum disturbance that the system can withstand, the inertia disturbance ratio and the critical inertia disturbance ratio:

[0060] First, the online or offline data integration is performed through the unit model parameters to determine the type of each unit, and the grid zone to which the unit belongs is determined through the grid configuration file, and the rotational inertia value of each grid zone is calculated under the current situation;

[0061] Secondly, based on the preset disturbance set, the evaluation algorithm and frequency constraints are called to calculate the evaluation index values ​​of each area within the power grid;

[0062] Finally, a set of rotational inertia evaluation indicators for each area of ​​the power grid under this operating mode is formed.

[0063] 3. According to different indicator levels, the warning area is set to red, the qualified area is set to blue, and the excellent area is set to green, and the calculation results are displayed through a visual map interface.

[0064] In this step, areas with poor indicators are set to red and warning signals are issued, so that relevant operation personnel can be alerted to weak areas first.

[0065] The method for evaluating the moment of inertia of each level in each region of a large power grid provided by the embodiment of the present invention integrates and innovates existing theories, and characterizes the inertia level of each region through several calculation indicators.

[0066] Example 1

[0067] At present, the frequency support capability of the power system is mainly evaluated by the method of evaluating the minimum inertia requirement. The strength of the power grids in different regions of the large power grid is different, and the magnitude of the possible fault disturbances is different. The inertia level and frequency support capability of each region can be measured by the rotational inertia margin, the maximum disturbance that the region can withstand, the inertia disturbance ratio and the critical inertia disturbance ratio.

[0068] The assessment process includes the following steps:

[0069] 1. Read the grid operation data, unit model parameters and configuration files:

[0070] The real-time or predicted operation mode of the power grid is read according to the calculation software, and the model parameter files of the started-up units or the units to be started-up and the power grid configuration files are retrieved as the basic data for evaluation and calculation.

[0071] 2. Input the preset disturbance fault set, and calculate the moment of inertia margin, the maximum disturbance that the system can withstand, the inertia disturbance ratio, and the critical inertia disturbance ratio through the moment of inertia level assessment model:

[0072] Through the online or offline data integration of unit model parameters, the type of each unit is determined, and the grid zone to which the unit belongs is determined through the grid configuration file. The moment of inertia value of each area of ​​the grid is calculated under the current situation. According to the preset disturbance set, the evaluation algorithm and frequency constraints are called to calculate the evaluation index value of each area within the grid.

[0073] 21. Moment of inertia margin:

[0074] Considering the frequency deviation and rate of change constraints, the minimum inertia requirement under the preset disturbance is evaluated and the rotational inertia margin is calculated.

[0075] a. Consider low-frequency constraints

[0076] Based on the real-time operation status of the power grid, the equivalent parameters of the system frequency response model in the current state are obtained, the frequency modulation gain of new energy is ignored, and a simplified frequency analysis model is established, considering the low-frequency limit H in the actual operation process. low , evaluate the minimum inertia requirement under low-frequency constraints.

[0077] b. Consider high frequency constraints

[0078] For the case of increased frequency, according to the generator rotor swing equation, the frequency deviation Δf(t) considering the inertia and load damping effects can be expressed as follows:

[0079]

[0080] Where: H sys is the system equivalent inertia constant, ΔP is the active disturbance power.

[0081] Therefore, the minimum inertia requirement H considering high-frequency constraints is high The expression is:

[0082]

[0083] Where: is the high frequency threshold, f0 is the rated frequency, and ΔP is the active disturbance power.

[0084] c. Consider frequency change constraints

[0085] At the moment of disturbance, the frequency deviation has not yet occurred, the generator speed regulator has not acted, and the load frequency regulation effect has not yet taken effect. At this time, the frequency change rate is the largest, and the system frequency change depends on the inertia and the disturbance power. Therefore, the minimum inertia requirement H considering the frequency change rate constraint is R The expression is:

[0086]

[0087] Where: f R,limit is the system frequency change rate, ΔP is the active disturbance power.

[0088] d. Moment of inertia margin

[0089] In summary, the expression of the minimum inertia requirement Hmin of the system that meets the grid frequency deviation and change rate constraints is as follows:

[0090] H min =max(H low , H high , H R )

[0091] Moment of inertia margin K m Reflects the relative distance between the current inertia level J and the minimum inertia Jmin requirement:

[0092]

[0093] 22. Maximum disturbance that the region can withstand:

[0094] Considering the frequency deviation and change rate constraints, under the current operation mode, the maximum disturbance power ΔP that the system can withstand is max for:

[0095] ΔP max =min(ΔP low , ΔP high , ΔP R )

[0096] In the formula, ΔP low , ΔP high , ΔP R They are the maximum disturbance that can be tolerated under low-frequency constraints, high-frequency constraints and frequency change constraints.

[0097] 23. Inertia disturbance ratio:

[0098] When the preset disturbance is ΔP, the inertia disturbance ratio K sys for:

[0099]

[0100] Online calculation and monitoring can be achieved according to the above formula.

[0101] Where: J sys is the moment of inertia of the system, ω0 is the rated electrical angular velocity, S ∑ is the system power generation capacity, H sysis the system equivalent inertia constant, ΔP is the active disturbance power.

[0102] 24. Critical inertia disturbance ratio: When ΔP is the maximum disturbance ΔP that the system can withstand max According to the index definition, the inertia disturbance ratio under this disturbance is the critical inertia disturbance ratio K sys，min :

[0103]

[0104] Where: J sys is the moment of inertia of the system, ω0 is the rated electrical angular velocity, S ∑ is the system power generation capacity, H sys is the system equivalent inertia constant, ΔP is the active disturbance power.

[0105] The minimum inertia requirement index H evaluated when the preset disturbance is ΔP min , when the system power structure changes and the system inertia level is reduced to H min When K sys，min The indicator expression is:

[0106]

[0107] Where: ω0 is the rated electrical angular velocity, S ∑ is the system power generation capacity, ΔP is the active disturbance power.

[0108] Inertia disturbance ratio index K sys Used to characterize the strength of the power grid frequency support capability under the current disturbance, critical inertia disturbance ratio index K sys，min It is used to characterize the minimum frequency support strength required to maintain the frequency stability of the power grid. sys，min It's K sys The lower bound of K provides a reference standard for measuring the frequency support capability level, and when the inertia can be monitored, the dispatcher can sys，min Quickly estimate the maximum disturbance power that the power grid can withstand.

[0109] A set of rotational inertia evaluation indicators for each area of ​​the power grid under this operating mode is formed.

[0110] 3. Analyze the calculation results, refer to relevant experience in dispatching operation, and according to different indicator levels, for example, the moment of inertia margin <100% is a poor area, 100%≤moment of inertia margin <200% is a general area, and moment of inertia margin ≥200% is an excellent area; the maximum tolerable disturbance <2.5% of the current load is a poor area, 2.5% of the current load≤the maximum tolerable disturbance <3.5% of the current load is a general area, and the maximum tolerable disturbance ≥3.5% of the current load is an excellent area; the moment of inertia disturbance ratio <100 is a poor area, 100≤inertia disturbance ratio <200 is a general area, and inertia disturbance ratio ≥200 is an excellent area; areas with poor indicators will be warned and set to red, areas with general indicators, that is, qualified areas will be set to blue, and areas with excellent indicators will be set to green, and the calculation results will be displayed through a visual map interface. If there is a major change in the operating mode, such as the transition between peak and trough periods of electricity consumption resulting in a major change in the startup capacity of the regional power grid, or if the output fluctuation of new energy sources causes a major change in the startup structure of the regional power grid, the calculation cycle needs to be repeated.

[0111] Note that the above are only preferred embodiments of the present invention and the technical principles used. Those skilled in the art will understand that the present invention is not limited to the specific embodiments described herein, and that various obvious changes, readjustments and substitutions can be made by those skilled in the art without departing from the scope of protection of the present invention. Therefore, although the present invention has been described in more detail through the above embodiments, the present invention is not limited to the above embodiments, and may include more other equivalent embodiments without departing from the concept of the present invention, and the scope of the present invention is determined by the scope of the appended claims.

Claims

1. A multi-region hierarchical and graded moment of inertia assessment method for a large power grid with high penetration rate of new energy, characterized in that: The following steps are involved: A. Reading grid operation data, unit model parameters and configuration files: Reading the real-time or predicted operation mode of the grid, retrieving the model parameter files of the started units or the units to be started and the grid configuration files as the basic data for evaluation and calculation; B. Calculate the rotational inertia margin, the maximum disturbance that the system can withstand, the inertia disturbance ratio and the critical inertia disturbance ratio: First, perform online or offline data integration through the unit model parameters to determine the type of each unit, determine the grid zone to which the unit belongs through the grid configuration file, and calculate the rotational inertia value of each area of ​​the grid; second, according to the preset disturbance set, call the evaluation algorithm and frequency constraints to calculate the evaluation index value of each area within the grid; finally, form a set of rotational inertia evaluation indicators for each area of ​​the grid under this operation mode; C. According to different indicator levels, the warning area is set to red, the qualified area is set to blue, and the excellent area is set to green, and the calculation results are displayed through a visual map interface.

2. According to claim 1, a multi-region hierarchical and graded moment of inertia assessment method for a high-penetration new energy large power grid is characterized by: Step B, considering the frequency deviation and change rate constraints, evaluates the minimum inertia requirement under the preset disturbance and calculates the rotational inertia margin.

3. The method for evaluating the moment of inertia of multi-regional hierarchical and graded large-scale high-penetration new energy power grid according to claim 2 is characterized in that: The specific steps to calculate the moment of inertia margin are: a. Consider low-frequency constraints Based on the real-time operation status of the power grid, the equivalent parameters of the system frequency response model in the current state are obtained, the frequency modulation gain of new energy is ignored, and a simplified frequency analysis model is established, considering the low-frequency limit H in the actual operation process. low , evaluate the minimum inertia requirement under low frequency constraints; b. Consider high frequency constraints For the case of increased frequency, according to the generator rotor swing equation, the frequency deviation Δf(t) considering the inertia and load damping effects can be expressed as follows: Among them, H sys is the system equivalent inertia constant, ΔP is the active disturbance power; Minimum inertia requirement H considering high frequency constraints high The expression is: in, is the high frequency threshold, f0 is the rated frequency, ΔP is the active disturbance power; c. Consider frequency change constraints At the moment of disturbance, the frequency deviation has not yet occurred, the generator speed regulator has not acted, and the load frequency regulation effect has not yet taken effect. At this time, the frequency change rate is the largest. The system frequency change depends on the inertia and the disturbance power. Considering the minimum inertia requirement H constrained by the frequency change rate R The expression is: Among them, f R,limit is the system frequency change rate, ΔP is the active disturbance power; d. Moment of inertia margin The expression of the system minimum inertia requirement Hmin that meets the grid frequency deviation and change rate constraints is as follows: H min =max(H low H high H R ) Moment of inertia margin K m Reflects the relative distance between the current inertia level J and the minimum inertia Jmin requirement:

4. The method for evaluating the moment of inertia of a multi-regional hierarchical and graded high-penetration new energy large power grid according to claim 1 is characterized in that: Step B: The specific steps for calculating the maximum disturbance that the region can withstand are: Considering the frequency deviation and change rate constraints, under the current operation mode, the maximum disturbance power ΔP that the system can withstand is max for: ΔP max =min(ΔP low ,ΔP high ,ΔP R ) Where ΔP low , ΔP high , ΔP R They are the maximum disturbance that can be tolerated under low-frequency constraints, high-frequency constraints and frequency change constraints.

5. The method for evaluating the moment of inertia of multi-regional hierarchical and graded high-penetration new energy large power grid according to claim 1 is characterized in that: Step B: The specific steps for calculating the inertia disturbance ratio are: When the preset disturbance is ΔP, the inertia disturbance ratio K sys for: Online calculation and monitoring can be realized according to the above formula. Among them, J sys is the moment of inertia of the system, ω0 is the rated electrical angular velocity, S ∑ is the system power generation capacity, H sys is the system equivalent inertia constant, ΔP is the active disturbance power.

6. The method for evaluating the moment of inertia of multi-regional hierarchical and graded high-penetration new energy large power grid according to claim 1 is characterized in that: Step B, the specific steps of calculating the critical inertia disturbance ratio are: When ΔP is taken as the maximum disturbance ΔP that the system can withstand max According to the index definition, the inertia disturbance ratio under this disturbance is the critical inertia disturbance ratio K sys，min : Among them, J sys is the moment of inertia of the system, ω0 is the rated electrical angular velocity, S ∑ is the system power generation capacity, H sys is the system equivalent inertia constant, ΔP is the active disturbance power; The minimum inertia requirement index H evaluated when the preset disturbance is ΔP min , when the system power structure changes and the system inertia level is reduced to H min When K sys，min The indicator expression is: Among them, the inertia disturbance ratio index K sys Used to characterize the strength of the power grid frequency support capability under the current disturbance, critical inertia disturbance ratio index K sys，min It is used to characterize the minimum frequency support strength required to maintain the frequency stability of the power grid. sys，min It's K sys The lower bound of K provides a reference standard for measuring the frequency support capability level, and when the inertia can be monitored, the dispatcher can sys，min Quickly estimate the maximum disturbance power that the power grid can withstand.

7. The method for evaluating the moment of inertia of a multi-regional hierarchical and graded high-penetration new energy large power grid according to claim 1 is characterized by: Step C, prioritize setting the indicator areas with poor performance to red and issuing a warning signal.

8. The method for evaluating the moment of inertia of a multi-regional hierarchical and graded high-penetration new energy large power grid according to claim 7 is characterized by: If the operation mode changes significantly, the calculation cycle needs to be repeated.

Images