New energy power system frequency minimum inertia calculation method and device and storage medium

Abstract

The invention belongs to the technical field of new energy power system frequency stability analysis, and particularly relates to a new energy power system frequency minimum inertia calculation method and device and a storage medium. The method comprises the following steps: constructing a new energy power system frequency response model, and deducing a time domain expression of frequency deviation; the occurrence time and size of the maximum offset of the frequency are deduced based on a time domain expression of the frequency deviation, and system frequency stability influence factors are determined; establishing an objective function, and determining constraint conditions; solving the minimum inertia of the frequency of the new energy power system, and performing optimization according to constraint conditions; and performing example analysis on the optimized frequency minimum inertia of the new energy power system, and judging the accuracy of the system frequency response model. According to the method, the inertia situation sensing capability of the power system in a high-proportion new energy access scene is enhanced, the frequency adaptability of the power system under active disturbance is improved, frequency response simulation considering virtual inertia is realized, and the contribution to the stability of the new energy system is huge.

Description

Technical Field

[0001] This invention belongs to the field of frequency stability analysis technology for new energy power systems, and particularly relates to a method, device and storage medium for calculating the minimum frequency inertia of a new energy power system. Furthermore, it relates to a method for calculating the minimum inertia of a new energy power system based on a simulated annealing algorithm. Background Technology

[0002] With the grid connection of large-scale new energy sources such as wind power and photovoltaics, the power system exhibits the "dual high" characteristics of high-proportion new energy access and high-proportion application of power electronic equipment. However, the inertia provided to the power system by new energy sources connected to the grid using power electronic interfaces is called "virtual inertia," which cannot provide reliable primary frequency regulation support for the system like synchronous generator units such as thermal power and hydropower. In addition, the rate of change of frequency (RoCoF) and the frequency minimum point of the system deteriorate significantly under power disturbances, leading to extreme accidents such as large-scale blackouts. To ensure the safe and stable operation of the high-proportion new energy power system, effective inertia estimation has become an important means of predicting power system frequency instability.

[0003] Current research on minimum inertia requirement assessment generally uses the system frequency change rate and the system maximum frequency deviation index to estimate the critical value of power system inertia. This paper establishes a minimum inertia requirement assessment model that maintains frequency stability under both islanded and grid-connected modes, taking into account both RoCoF and frequency deviation constraints. Based on frequency stability constraints, a rapid inertia safety domain assessment model and method are constructed to meet the actual grid dispatching and operation requirements.

[0004] However, none of the above methods take into account the effect of the virtual inertia of new energy generator units on the power generation side, and the constraints set in the evaluation model do not take into account the processing constraints of generator units. Therefore, it is essential to construct a complete and accurate minimum inertia evaluation model for the power system. Summary of the Invention

[0005] To address the shortcomings of the existing technologies, this invention provides a method, apparatus, and storage medium for calculating the minimum frequency inertia of a new energy power system. The purpose is to construct a complete and accurate minimum inertia assessment model for the power system, thereby improving the frequency adaptability of the power system under active power disturbances and achieving the invention's objective of frequency response simulation considering virtual inertia.

[0006] The technical solution adopted by the present invention to achieve the above objectives is as follows:

[0007] Methods for calculating the minimum frequency inertia of new energy power systems include:

[0008] A frequency response model for a new energy power system is constructed, and the time-domain expression for frequency deviation is derived.

[0009] Based on the time-domain expression of frequency deviation, the timing and magnitude of the maximum frequency offset are derived, and the factors affecting system frequency stability are identified.

[0010] Establish an objective function and determine constraints based on the factors affecting system frequency stability.

[0011] Solve for the minimum frequency inertia of the new energy power system and optimize it based on the constraints;

[0012] A case study analysis was conducted on the minimum frequency inertia of the optimized new energy power system to determine the accuracy of the system frequency response model.

[0013] Furthermore, the construction of the frequency response model of the new energy power system, the derivation of the time-domain expression of the frequency deviation, and the derivation of the time-domain expression of the frequency deviation through inverse Laplace transform include:

[0014] For power systems that include new energy sources, an equivalent method is used to construct a system frequency response model;

[0015] The system accesses the frequency response model of a primary frequency regulation system;

[0016] In frequency response model analysis, the change in load power is considered to simplify the frequency response model;

[0017] The time-domain expression for the frequency deviation is derived using the inverse Laplace transform.

[0018] Furthermore, the frequency response model of the system connected to the primary frequency regulation system is expressed as follows:

[0019]

[0020] in:

[0021]

[0022] In the above formula, H is the inertial time constant of the generator. new Let be the virtual inertia constant of the new energy generator set, D be the equivalent damping coefficient of the generator, and R be the droop coefficient of the speed governor. F is the reheat time constant of the prime mover. H The power ratio of the high-pressure cylinder of the prime mover, g n P is a coefficient related to the generator power factor and reserve capacity. m P is the output power of the prime mover. e For load power, P sp To increase the generator's output power, Δ zLet be the system average speed deviation, s be the rated capacity of the unit, Z1 be an intermediate variable for simplified calculation, and T be... q r H is the reheat time constant of the prime mover. all It is the sum of the inertial time constant of the generator and the virtual inertial constant of the new energy generator set;

[0023] In the frequency response model analysis, only the load power P is considered. e The change, without considering the increase in generator power P sp The change in , so the simplified formula (1) is:

[0024]

[0025] In the above formula, P d This is the load power P at this location. e H all z1 is the sum of the inertial time constant of the motor and the virtual inertial constant of the new energy generator set. The formula is shown below.

[0026] The time-domain expression for the frequency deviation derived through the inverse Laplace transform is as follows:

[0027]

[0028] In the above formula, △z (t) For the time domain of frequency deviation, δz1 is the damping ratio of Z1;

[0029] in:

[0030]

[0031] Furthermore, the time and magnitude of the maximum frequency offset are derived from the time-domain expression based on the frequency deviation, clarifying the factors affecting system frequency stability, including:

[0032] Assume the magnitude of the disturbance is Δ P Then the frequency-time domain expression of the system under disturbance is:

[0033] Δf(t)=Δ P ·h(t)

[0034] In the above formula, Δf(t) is the rate-time domain expression, and h(t) is the inertia-time expression;

[0035] Derivation of the time t when the maximum frequency offset occurs n And the magnitude of the maximum frequency offset Δf n They are respectively:

[0036]

[0037] In the above formula, t n Ω represents the time when the maximum frequency shift occurs, and Ω represents the damping characteristic of the system. r For the damping characteristics of thermal power, Ω n For the damping characteristics of other systems, Δf(n) is the time-domain expression of the corrected rate;

[0038] Maximum value of the rate of change of frequency The frequency deviation was 0 and the system output was 0 when the value was obtained at t=0. The size is:

[0039]

[0040] In the above formula, H s Let Ω be the inertial time constant of the unit, d be the damping characteristic of the system, and t be the Δt. f The derivative with respect to time;

[0041] The maximum frequency offset of the system is an important indicator for evaluating the frequency stability of the system.

[0042] Furthermore, the establishment of the objective function based on the factors affecting system frequency stability and the determination of constraints include:

[0043] The objective function is defined as follows:

[0044]

[0045] In the above formula, E sts S represents the minimum total inertia requirement of the system, including the rotational inertia of the synchronous machine and the virtual inertia of the new energy generator set. i S is the rated capacity of conventional unit i. j Where M is the rated capacity of conventional unit j, W is the number of synchronous generators, and x is the number of new energy units. i H is the symbol required for integration. i Let y be the inertial time constant of conventional unit i. j H′ is the symbol required for integration. j Let be the inertial time constant of conventional unit i;

[0046] The constraints of the model include: maximum system frequency offset constraint, frequency change rate RoCoF constraint, and capacity constraint;

[0047] The constraints for the system's maximum frequency offset and the rate of change of frequency (RoCoF) are as follows:

[0048]

[0049] In the above formula, RoCoF max and Δfmax To maintain the stability of the power system frequency, the maximum allowable rate of frequency change and the maximum allowable frequency change amount, αω n This is the natural oscillation frequency;

[0050] Maximum frequency deviation Δf max and maximum frequency change rate RoCoF max Used as a trigger signal for protective components and control devices in power systems;

[0051] Set a power reserve capacity constraint, as shown in the following expression:

[0052]

[0053] ΔP gi,min ≤ΔP gi,t ≤ΔP gi,max

[0054] In the above formula, △P gi,t Let Ri be the power regulation of the primary frequency regulation equipment for a single generator, and Ri be the speed regulation coefficient of the governor of the i-th generator set. Hi The high-voltage turbine component coefficient of the i-th generator set, T Ri Let Δf be the reheat time constant of the i-th generator unit. t For the rate-time domain expression, ΔP gi,min and ΔP gi,max These are the minimum and maximum values ​​of the regulating power of a single generator's primary frequency regulation equipment.

[0055] Furthermore, the process of solving for the minimum frequency inertia of the new energy power system and optimizing it based on constraints includes:

[0056] The calculation of the minimum inertia global search method for new energy power systems based on simulated annealing algorithm is as follows:

[0057] Step 41. Initialize system parameters;

[0058] Step 42. Determine the upper and lower limits of the frequency deviation to be optimized based on the standards and constraints set in electrical engineering disciplines;

[0059] Step 43. Select the initial temperature T0 = T for the simulated annealing algorithm. max The annealing coefficient is α;

[0060] Step 44. Randomly select a set of parameters X to be optimized from the feasible solution region. j Calculate the frequency deviation f(X) j ) and its variable Δf ij (X)=f(X j )-f(X i If fij If (X) ≤ 0, accept state j; otherwise, reject state j; where X i For the frequency deviation to be optimized in the i-th state, f ij For containing f(X) j ) and f(X i X is a variable of the system, where X is the system inertia;

[0061] Step 45. If the internal circulation criterion is met at the initial temperature T0, proceed to step 46; otherwise, return to step 44.

[0062] Step 46. Execute the convergence criterion. If the convergence criterion is met, the optimization ends; otherwise, reduce the temperature. k+1 =t k ,k:=k+1, return to step 44.

[0063] A frequency minimum inertia calculation device for new energy power systems, comprising:

[0064] The module for constructing and deriving is used to construct the frequency response model of the new energy power system and derive the time-domain expression of the frequency deviation.

[0065] The derivation module is used to derive the time and magnitude of the maximum frequency offset based on the time-domain expression of the frequency deviation, and to clarify the factors affecting the stability of the system frequency.

[0066] The objective function establishment module is used to establish an objective function and determine constraints based on factors affecting system frequency stability.

[0067] The solution module is used to solve for the minimum frequency inertia of the new energy power system and optimize it according to the constraints.

[0068] The judgment module is used to perform a calculation analysis on the minimum frequency inertia of the optimized new energy power system and to determine the accuracy of the system frequency response model.

[0069] Furthermore, the solution module is specifically used to calculate the global search method for minimum inertia in new energy power systems based on the simulated annealing algorithm, and the steps are as follows:

[0070] Step 41. Initialize system parameters;

[0071] Step 42. Determine the upper and lower limits of the frequency deviation to be optimized based on the standards and constraints set in electrical engineering disciplines;

[0072] Step 43. Select the initial temperature T0 = T for the simulated annealing algorithm. max The annealing coefficient is α;

[0073] Step 44. Randomly select a set of parameters X to be optimized from the feasible solution region. jCalculate the frequency deviation f(X) j ) and its variable Δf ij (X)=f(X j )-f(X i If f ij If (X) ≤ 0, accept state j; otherwise, reject state j; where X i For the frequency deviation to be optimized in the i-th state, f ij For containing f(X) j ) and f(X i X is a variable of the system, where X is the system inertia;

[0074] Step 45. If the internal circulation criterion is met at the initial temperature T0, proceed to step 46; otherwise, return to step 44.

[0075] Step 46. Execute the convergence criterion. If the convergence criterion is met, the optimization ends; otherwise, reduce the temperature. k+1 =t k ,k:=k+1, return to step 44.

[0076] A computer device includes a storage medium, a processor, and a computer program stored on the storage medium and executable on the processor. When the processor executes the computer program, it implements the steps of the method for calculating the minimum frequency inertia of a new energy power system as described in any one of the claims.

[0077] A computer storage medium storing a computer program, wherein when the computer program is executed by a processor, the steps of the method for calculating the minimum frequency inertia of a new energy power system as described in any one of the claims are implemented.

[0078] The present invention has the following beneficial effects and advantages:

[0079] Compared with existing technologies, this invention enhances the power system's inertia situational awareness capability in scenarios with a high proportion of renewable energy integration, improves the power system's frequency adaptability under active power disturbances, and realizes frequency response simulation considering virtual inertia. By analyzing the power system's frequency response process on a time scale, a multi-machine frequency response model of the power system including the virtual inertia of renewable energy is established. The frequency response expression of the system connected to the primary frequency regulation system under this model is derived, and a simulated annealing algorithm is introduced to calculate the system's minimum inertia, making a significant contribution to the stability of renewable energy systems. Attached Figure Description

[0080] The above and / or additional aspects and advantages of the present invention will become apparent and readily understood from the description of the embodiments taken in conjunction with the following drawings, in which:

[0081] Figure 1 This is a power system frequency response model diagram of the present invention;

[0082] Figure 2 This is a flowchart of the simulated annealing algorithm of the present invention;

[0083] Figure 3 This is the IEEE 14-node topology diagram of this invention;

[0084] Figure 4 This is the frequency response curve of the system of the present invention. Detailed Implementation

[0085] To better understand the above-mentioned objectives, features, and advantages of the present invention, the present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments. It should be noted that, unless otherwise specified, the embodiments of the present invention and the features thereof can be combined with each other.

[0086] Many specific details are set forth in the following description in order to provide a full understanding of the invention. However, the invention may also be practiced in other ways different from those described herein, and therefore the scope of protection of the invention is not limited to the specific embodiments disclosed below.

[0087] The following reference Figures 1-4 The technical solutions of some embodiments of the present invention are described below.

[0088] Example 1

[0089] This invention provides an embodiment of a method for calculating the minimum frequency inertia of a new energy power system, specifically including the following steps:

[0090] Step 1. Establish a frequency response model, derive the frequency response expression, and derive the time-domain expression of the frequency deviation through the inverse Laplace transform.

[0091] Step 1.1. Construct a system frequency response model for a power system including new energy sources using the equivalent method, such as... Figure 1 As shown, Figure 1 This is a power system frequency response model diagram of the present invention;

[0092] Step 1.2. From Figure 1 As can be seen from the model, the frequency response model expression of the system connected to the primary frequency regulation system is:

[0093]

[0094] in:

[0095]

[0096] In the above formula, H is the inertial time constant of the generator. newLet be the virtual inertia constant of the new energy generator set, D be the equivalent damping coefficient of the generator, and R be the droop coefficient of the speed governor. F is the reheat time constant of the prime mover. H The power ratio of the high-pressure cylinder of the prime mover, g n P is a coefficient related to the generator power factor and reserve capacity. m P is the output power of the prime mover. e For load power, P sp To increase the generator's output power. Δ z Let be the system average speed deviation, s be the rated capacity of the unit, Z1 be an intermediate variable for simplified calculation, and T be... q r H is the reheat time constant of the prime mover. all It is the sum of the inertial time constant of the generator and the virtual inertial constant of the new energy generator set.

[0097] Step 1.3. In the frequency response model analysis, only the load power P is considered. e The change, without considering the increase in generator power P sp The change in , so the simplified formula (1) is:

[0098]

[0099] In the above formula, P d This is the load power P at this location. e H all It is the sum of the inertial time constant of the motor and the virtual inertial constant of the new energy generator set;

[0100] Step 1.4. Using the inverse Laplace transform, derive the time-domain expression for the frequency deviation as follows:

[0101]

[0102] In the above formula, △z (t) Let be the time-domain expression for the frequency deviation, and δz1 be the damping ratio of Z1. Where:

[0103]

[0104] Step 2. Based on the "time domain expression of frequency deviation" in Step 1, derive the time of occurrence of the maximum frequency offset and the magnitude of the maximum frequency offset, and identify the factors affecting the stability of the system frequency.

[0105] Step 2.1. Assume the magnitude of the disturbance is Δ P Then the frequency-time domain expression of the system under disturbance is:

[0106] Δf(t)=Δ P ·h(t)

[0107] In the above formula, Δf(t) is the rate-time domain expression, and h(t) is the inertia-time expression;

[0108] And the time t at which the maximum frequency offset occurs can be derived. n And the magnitude of the maximum frequency offset Δf n They are respectively:

[0109]

[0110] In the above formula, t n Ω represents the time when the maximum frequency shift occurs, and Ω represents the damping characteristic of the system. r For the damping characteristics of thermal power, Ω n For the damping characteristics of other systems, Δf(n) is the time-domain expression of the corrected rate;

[0111] Due to the maximum value of the rate of change of frequency The value is obtained at t=0, at which point the frequency deviation is 0, therefore the system output is also 0. The size is:

[0112]

[0113] In the above formula, H s Let Ω be the inertial time constant of the unit, d be the damping characteristic of the system, and t be the Δt. f The derivative with respect to time.

[0114] This analysis reveals that the maximum rate of change of the system frequency is only related to the system's inertia level, and the quasi-steady-state frequency deviation after the first frequency regulation is only related to the system's damping characteristics and the droop characteristics of the synchronous generator speed regulation system within the system. The latter two are unrelated to the dynamic characteristics of the synchronous generator's turbine and speed regulation system within the system.

[0115] The conclusion is that the maximum frequency offset of the system is an important indicator for evaluating the frequency stability of the system.

[0116] Step 3. Establish the objective function and determine the constraints based on the factors affecting system frequency stability in Step 2.

[0117] The objective function is established as follows: The model aims to achieve system frequency stability, with the minimum inertia of the power system as the objective function. The model's objective function is shown in the following equation:

[0118]

[0119] In the above formula, E sts This represents the minimum total inertia requirement of the system, including the rotational inertia of the synchronous machine and the virtual inertia of the new energy generator set, S. iS is the rated capacity of conventional unit i. j Where M is the rated capacity of conventional unit j, W is the number of synchronous generators, and x is the number of new energy units. i H is the symbol required for integration. i Let y be the inertial time constant of conventional unit i. j H′ is the symbol required for integration. j Let be the inertial time constant of conventional unit i;

[0120] The model is set with three constraints: maximum system frequency offset constraint, frequency change rate RoCoF constraint, and capacity constraint.

[0121] Among them, the system frequency maximum offset constraint and frequency change rate RoCoF constraint are the constraints set in the model in step 1.2, and the capacity constraint is the constraint set in the model in step 2.1.

[0122] Based on equations (2) and (3), the constraints for the system's maximum frequency offset index and the frequency change rate RoCoF index can be obtained as follows:

[0123]

[0124] In the above formula, RoCoF max and Δf max To maintain the stability of the power system frequency, the maximum allowable rate of frequency change and the maximum allowable frequency change amount, αω n This is the natural oscillation frequency.

[0125] Maximum frequency deviation Δf max and maximum frequency change rate RoCoF max Typically used as a trigger signal for protective components and control devices in power systems, my country requires Δf... max No more than 0.2Hz.

[0126] The regulation capacity of a single generator frequency regulation system is limited by its own capacity. Therefore, a power reserve capacity constraint should be set, as shown in the following expression:

[0127]

[0128] ΔP gi,min ≤ΔP gi,t ≤ΔP gi,max

[0129] In the above formula, △P gi,t Let Ri be the power regulation of the primary frequency regulation equipment for a single generator, and Ri be the speed regulation coefficient of the governor of the i-th generator set. Hi The high-voltage turbine component coefficient of the i-th generator set, T RiLet Δf be the reheat time constant of the i-th generator unit. t For the rate-time domain expression, ΔP gi,min and ΔP gi,max These are the minimum and maximum values ​​of the regulating power of a single generator's primary frequency regulation equipment.

[0130] Step 4. Use the simulated annealing algorithm to solve for the minimum frequency inertia of the new energy power system.

[0131] Simulated annealing is similar to local search algorithms, but it allows a certain probability of transitioning from a lower value to a higher value during the search process, thus avoiding getting trapped in local minima.

[0132] The basic idea of ​​the simulated annealing algorithm for global search of minimum inertia in new energy power systems is to treat the model parameters to be optimized as each molecule of a molten object, and the system inertia as the energy function of the molten object. Iterative optimization is performed by slowly reducing the simulated temperature, so that the output value eventually reaches a minimum.

[0133] The calculation steps of the global search method for minimum inertia in new energy power systems based on simulated annealing algorithm are as follows:

[0134] Step 41. Initialize system parameters.

[0135] Step 42. Determine the upper and lower limits of the frequency deviation to be optimized based on the electrical engineering discipline standards and the constraints set in Step 2.

[0136] Step 43. Select the initial temperature T0 = T for the simulated annealing algorithm. max The annealing coefficient is α; in this invention, the initial temperature of the simulated annealing algorithm is the initial frequency deviation of the system, T0 = 0.2, and α = 0.0001.

[0137] Step 44. Randomly select a set of parameters X to be optimized from the feasible solution region. j And calculate the frequency deviation f(X) j ) and its variable Δf ij (X)=f(X j )-f(X i If f ij If (X) ≤ 0, accept state j; otherwise, reject state j; where X i For the frequency deviation to be optimized in the i-th state, f ij For containing f(X) j ) and f(X i X is a variable of the system, where X is the system inertia.

[0138] Step 45. If the internal circulation criterion is met at the initial temperature T0, proceed to step 46; otherwise, return to step 44.

[0139] Step 46. Execute the convergence criterion. If the convergence criterion is met, the optimization ends; otherwise, reduce the temperature. k+1 =t k ,k:=k+1, return to step 44.

[0140] The simulated annealing algorithm includes an inner loop, namely steps 44 and 45, which indicate that at the same temperature t... k Under certain conditions, the algorithm searches for intermediate solutions through randomized searches. Simulated annealing performs large-scale searches at high temperatures, while at low temperatures it searches only around the current model parameters.

[0141] Optimizing the minimum frequency inertia of a new energy power system using constraints can make the minimum frequency inertia value more accurate.

[0142] Step 5. Perform a case study analysis to determine the accuracy of the system frequency response model.

[0143] The accuracy of the model was verified using the IEEE-14 node system. The system network topology is shown in the figure. A simulation model of the IEEE-14 node system was built using the Matlab / Simulink and PSASP platforms. One wind farm and one photovoltaic (PV) farm were added, located at nodes 1 and 3. To maximize the absorption of renewable energy, it was assumed that both the wind farm and the PV power station used Maximum Power Point Tracking (MPPT) control. The parameters of each unit and the newly added wind turbine are shown in Tables 1 and 2.

[0144] Table 1

[0145] Unit serial number Rated power / MW Inertial time constant / s G1 632 4.7 G2 592 4.9 G3 730 4.8

[0146] Table 2

[0147] Unit serial number Rated power / MW Inertial time constant / s W1 190 4.8 PV1 99 4.9

[0148] System frequency response curve:

[0149] At time t0, a ΔP is applied to the same node in the PSASP simulation model of the system. d A load disturbance of 0.03 pu is used to determine the accuracy of the system frequency response model by monitoring the change in frequency variation Δf in the model. Figure 4 As can be seen from the curve, after the combined regulation of the inertial response and the primary frequency regulation system, the system frequency gradually recovers to a stable state after passing the point of maximum frequency deviation. At t = 9.67241s, the system reaches the point of maximum frequency deviation, with the maximum frequency deviation Δf. max =0.0688.

[0150] Example 2

[0151] The present invention provides another embodiment of a frequency minimum inertia calculation device for a new energy power system, comprising:

[0152] The module for constructing and deriving is used to construct the frequency response model of the new energy power system and derive the time-domain expression of the frequency deviation.

[0153] The derivation module is used to derive the time and magnitude of the maximum frequency offset based on the time-domain expression of the frequency deviation, and to clarify the factors affecting the stability of the system frequency.

[0154] The objective function establishment module is used to establish an objective function and determine constraints based on factors affecting system frequency stability.

[0155] The solution module is used to solve for the minimum frequency inertia of the new energy power system and optimize it according to the constraints.

[0156] The judgment module is used to perform a calculation analysis on the minimum frequency inertia of the optimized new energy power system and to determine the accuracy of the system frequency response model.

[0157] The device described in this embodiment is used to implement the steps of the method for calculating the minimum frequency inertia of a new energy power system as described in Embodiment 1.

[0158] Specifically, the solution module is used to calculate the global search method for minimum inertia in new energy power systems based on the simulated annealing algorithm, and the steps are as follows:

[0159] Step 41. Initialize system parameters;

[0160] Step 42. Determine the upper and lower limits of the frequency deviation to be optimized based on the standards and constraints set in electrical engineering disciplines;

[0161] Step 43. Select the initial temperature T0 = T for the simulated annealing algorithm. max The annealing coefficient is α;

[0162] Step 44. Randomly select a set of parameters X to be optimized from the feasible solution region. j Calculate the frequency deviation f(X) j ) and its variable Δf ij (X)=f(X j )-f(X i If f ij If (X) ≤ 0, accept state j; otherwise, reject state j; where X i For the frequency deviation to be optimized in the i-th state, f ij For containing f(X) j ) and f(X iX is a variable of the system, where X is the system inertia;

[0163] Step 45. If the internal circulation criterion is met at the initial temperature T0, proceed to step 46; otherwise, return to step 44.

[0164] Step 46. Execute the convergence criterion. If the convergence criterion is met, the optimization ends; otherwise, reduce the temperature. k+1 =t k ,k:=k+1, return to step 44.

[0165] Example 3

[0166] Based on the same inventive concept, embodiments of the present invention also provide a computer device, including a storage medium, a processor, and a computer program stored on the storage medium and executable on the processor. When the processor executes the computer program, it implements the steps of any of the methods for calculating the minimum frequency inertia of a new energy power system described in Embodiment 1 or 2.

[0167] Example 4

[0168] Based on the same inventive concept, this embodiment of the invention also provides a computer storage medium storing a computer program, which, when executed by a processor, implements the steps of any of the new energy power system frequency minimum inertia calculation methods described in Embodiment 1 or 2.

[0169] Those skilled in the art will understand that embodiments of the present invention can be provided as methods, systems, or computer program products. Therefore, the present invention can take the form of a completely hardware embodiment, a completely software embodiment, or an embodiment combining software and hardware aspects. Furthermore, the present invention can take the form of a computer program product embodied on one or more computer-usable storage media (including, but not limited to, disk storage, CD-ROM, optical storage, etc.) containing computer-usable program code.

[0170] This invention is described with reference to flowchart illustrations and / or block diagrams of methods, apparatus (systems), and computer program products according to embodiments of the invention. It will be understood that each block of the flowchart illustrations and / or block diagrams, and combinations of blocks in the flowchart illustrations and / or block diagrams, can be implemented by computer program instructions. These computer program instructions can be provided to a processor of a general-purpose computer, special-purpose computer, embedded processor, or other programmable data processing apparatus to produce a machine, such that the instructions, which execute via the processor of the computer or other programmable data processing apparatus, generate instructions for implementing the flowchart illustrations and / or block diagrams. Figure 1 One or more processes and / or boxes Figure 1 A device that provides the functions specified in one or more boxes.

[0171] These computer program instructions may also be stored in a computer-readable storage medium that can direct a computer or other programmable data processing device to function in a particular manner, such that the instructions stored in the computer-readable storage medium produce an article of manufacture including instruction means, which are implemented in a process Figure 1 One or more processes and / or boxes Figure 1 The function specified in one or more boxes.

[0172] These computer program instructions may also be loaded onto a computer or other programmable data processing equipment to cause a series of operational steps to be performed on the computer or other programmable equipment to produce a computer-implemented process, thereby providing instructions that execute on the computer or other programmable equipment for implementing the process. Figure 1 One or more processes and / or boxes Figure 1 The steps of the function specified in one or more boxes.

[0173] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and not to limit it. Although the present invention has been described in detail with reference to the above embodiments, those skilled in the art should understand that modifications or equivalent substitutions can still be made to the specific implementation of the present invention. Any modifications or equivalent substitutions that do not depart from the spirit and scope of the present invention should be covered within the scope of protection of the claims of the present invention.

Claims

1. A method for calculating the minimum frequency inertia of a new energy power system, characterized by: include: A frequency response model for a new energy power system is constructed, and the time-domain expression for frequency deviation is derived. Based on the time-domain expression of frequency deviation, the timing and magnitude of the maximum frequency offset are derived, and the factors affecting system frequency stability are identified. Establish an objective function and determine constraints based on the factors affecting system frequency stability. Solve for the minimum frequency inertia of the new energy power system and optimize it based on the constraints; A case study analysis was conducted on the minimum frequency inertia of the optimized new energy power system to determine the accuracy of the system frequency response model.

2. The method for calculating the minimum frequency inertia of a new energy power system according to claim 1, characterized in that: The construction of the frequency response model of the new energy power system, and the derivation of the time-domain expression of the frequency deviation, including the inverse Laplace transform, include: For power systems that include new energy sources, an equivalent method is used to construct a system frequency response model; The system accesses the frequency response model of a primary frequency regulation system; In frequency response model analysis, the change in load power is considered to simplify the frequency response model; The time-domain expression for the frequency deviation is derived using the inverse Laplace transform.

3. The method for calculating the minimum frequency inertia of a new energy power system according to claim 2, characterized in that: The frequency response model of the system connected to the primary frequency regulation system is expressed as follows: in: H all =H+H new In the above formula, H is the inertial time constant of the generator. new Let be the virtual inertia constant of the new energy generator set, D be the equivalent damping coefficient of the generator, and R be the droop coefficient of the speed governor. F is the reheat time constant of the prime mover. H The power ratio of the high-pressure cylinder of the prime mover, g n P is a coefficient related to the generator power factor and reserve capacity. m P is the output power of the prime mover. e For load power, P sp To increase the generator's output power, Δ z Let be the system average speed deviation, s be the rated capacity of the unit, Z1 be an intermediate variable for simplified calculation, and T be... q r H is the reheat time constant of the prime mover. all It is the sum of the inertial time constant of the generator and the virtual inertial constant of the new energy generator set; In the frequency response model analysis, the load power P is considered. e The change, simplified to equation (1): In the above formula, P d This is the load power P at this location. e H all It is the sum of the inertial time constant of the motor and the virtual inertial constant of the new energy generator set; The time-domain expression for the frequency deviation derived through the inverse Laplace transform is as follows: In the above formula, △z (t) For the time domain of frequency deviation, δz1 is the damping ratio of Z1; in:

4. The method for calculating the minimum frequency inertia of a new energy power system according to claim 1, characterized in that: The time-domain expression based on frequency deviation is used to derive the time and magnitude of the maximum frequency offset, clarifying the factors affecting system frequency stability, including: Assume the magnitude of the disturbance is Δ P Then the frequency-time domain expression of the system under disturbance is: Δf(t)=Δ P ·h(t) In the above formula, Δf(t) is the rate-time domain expression, and h(t) is the inertia-time expression; Derivation of the time t when the maximum frequency offset occurs n And the magnitude of the maximum frequency offset Δf n They are respectively: Δf n =Δf(t n ) (2) In the above formula, t n Ω represents the time when the maximum frequency shift occurs, and Ω represents the damping characteristic of the system. r For the damping characteristics of thermal power, Ω n For the damping characteristics of other systems, Δf(n) is the time-domain expression of the corrected rate; Maximum value of the rate of change of frequency The frequency deviation was 0 and the system output was 0 when the value was obtained at t=0. The size is: In the above formula, H s Let Ω be the inertial time constant of the unit, d be the damping characteristic of the system, and t be the Δt. f The derivative with respect to time; The maximum frequency offset of the system is an important indicator for evaluating the frequency stability of the system.

5. The method for calculating the minimum frequency inertia of a new energy power system according to claim 1, characterized in that: The objective function established based on the factors affecting system frequency stability, and the constraints determined, include: The objective function is defined as follows: In the above formula, E sts S represents the minimum total inertia requirement of the system, including the rotational inertia of the synchronous machine and the virtual inertia of the new energy generator set. i S is the rated capacity of conventional unit i. j Where M is the rated capacity of conventional unit j, W is the number of synchronous generators, and x is the number of new energy units. i H is the symbol required for integration. i Let y be the inertial time constant of conventional unit i. j H′ is the symbol required for integration. j Let be the inertial time constant of conventional unit i; The constraints of the model include: maximum system frequency offset constraint, frequency change rate RoCoF constraint, and capacity constraint; The constraints for the system's maximum frequency offset and the rate of change of frequency (RoCoF) are as follows: -RoCoF max ≤RoCoF0≤RoCoF max -Δf max ≤Δf≤Δf max (3) In the above formula, RoCoF max and Δf max To maintain the stability of the power system frequency, the maximum allowable rate of frequency change and the maximum allowable frequency change amount, αω n This is the natural oscillation frequency; Maximum frequency deviation Δf max and maximum frequency change rate RoCoF max Used as a trigger signal for protective components and control devices in power systems; Set a power reserve capacity constraint, as shown in the following expression: ΔP gi,min ≤ΔP gi,t ≤ΔP gi,max In the above formula, △P gi,t Let Ri be the power regulation of the primary frequency regulation equipment for a single generator, and Ri be the speed regulation coefficient of the governor of the i-th generator set. Hi The high-voltage turbine component coefficient of the i-th generator set, T Ri Let Δf be the reheat time constant of the i-th generator unit. t For the rate-time domain expression, ΔP gi,min and ΔP gi,max These are the minimum and maximum values ​​of the regulating power of a single generator's primary frequency regulation equipment.

6. The method for calculating the minimum frequency inertia of a new energy power system according to claim 1, characterized in that: The process of solving for the minimum frequency inertia of the new energy power system and optimizing it based on constraints includes: calculating the global search method for the minimum inertia of the new energy power system based on the simulated annealing algorithm, with the following steps: Step 41. Initialize system parameters; Step 42. Determine the upper and lower limits of the frequency deviation to be optimized based on the standards and constraints set in electrical engineering disciplines; Step 43. Select the initial temperature T0 = T for the simulated annealing algorithm. max The annealing coefficient is α; Step 44. Randomly select a set of parameters X to be optimized from the feasible solution region. j Calculate the frequency deviation f(X) j ) and its variable Δf ij (X)=f(X j )-f(X i If f ij If (X) ≤ 0, accept state j; otherwise, reject state j; where X i For the frequency deviation to be optimized in the i-th state, f ij For containing f(X) j ) and f(X i X is a variable of the system, where X is the system inertia; Step 45. If the internal circulation criterion is met at the initial temperature T0, proceed to step 46; otherwise, return to step 44. Step 46. Execute the convergence criterion. If the convergence criterion is met, the optimization ends; otherwise, reduce the temperature. k+1 =t k ,k:=k+1, return to step 44.

7. A frequency minimum inertia calculation device for new energy power systems, characterized by: include: The module for constructing and deriving is used to construct the frequency response model of the new energy power system and derive the time-domain expression of the frequency deviation. The derivation module is used to derive the time and magnitude of the maximum frequency offset based on the time-domain expression of the frequency deviation, and to clarify the factors affecting the stability of the system frequency. The objective function establishment module is used to establish an objective function and determine constraints based on factors affecting system frequency stability. The solution module is used to solve for the minimum frequency inertia of the new energy power system and optimize it according to the constraints. The judgment module is used to perform a calculation analysis on the minimum frequency inertia of the optimized new energy power system and to determine the accuracy of the system frequency response model.

8. The frequency minimum inertia calculation device for new energy power systems according to claim 7, characterized in that: The solution module is specifically used to calculate the global search method for minimum inertia in new energy power systems based on the simulated annealing algorithm. The steps are as follows: Step 41. Initialize system parameters; Step 42. Determine the upper and lower limits of the frequency deviation to be optimized based on the standards and constraints set in electrical engineering disciplines; Step 43. Select the initial temperature T0 = T for the simulated annealing algorithm. max The annealing coefficient is α; Step 44. Randomly select a set of parameters X to be optimized from the feasible solution region. j Calculate the frequency deviation f(X) j ) and its variable Δf ij (X)=f(X j )-f(X i If f ij If (X) ≤ 0, accept state j; otherwise, reject state j; where X i For the frequency deviation to be optimized in the i-th state, f ij For containing f(X) j ) and f(X i X is a variable of the system, where X is the system inertia; Step 45. If the internal circulation criterion is met at the initial temperature T0, proceed to step 46; otherwise, return to step 44. Step 46. Execute the convergence criterion. If the convergence criterion is met, the optimization ends; otherwise, reduce the temperature. k+1 =t k ,k:=k+1, return to step 44.

9. A computer device, comprising a storage medium, a processor, and a computer program stored on the storage medium and executable on the processor, characterized in that, When the processor executes the computer program, it implements the steps of the method for calculating the minimum frequency inertia of a new energy power system as described in any one of claims 1-6.

10. A computer storage medium, characterized in that: The computer storage medium contains a computer program, which, when executed by a processor, implements the steps of the method for calculating the minimum frequency inertia of a new energy power system as described in any one of claims 1-6.

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