Method for estimating virtual inertia and primary frequency modulation parameter of new energy station

Abstract

The invention discloses a method for estimating virtual inertia and primary frequency modulation parameters of a new energy station, and the method comprises the steps: obtaining the active power at a frequency modulation moment on the basis of filtering the electrical quantity data of the new energy station, and solving the frequency modulation active power of a grid-connected point of the new energy station in a frequency modulation time period; calculating a primary frequency modulation parameter based on a moving average window; then, extracting virtual inertia active power in station frequency modulation active power; and finally, calculating an equivalent virtual inertia coefficient of a new energy station grid-connected point based on the virtual inertia active power. According to the method, the primary frequency modulation control parameter and the virtual inertia control parameter of the new energy station can be evaluated more accurately and meticulously, and the method is of great significance in checking the virtual inertia and the primary frequency modulation control capability of the new energy station.

Description

Technical Field

[0001] The present invention relates to the technical field of new energy frequency regulation parameter evaluation, and in particular to a method for estimating virtual inertia and primary frequency regulation parameters of a new energy station. Background Art

[0002] Against the backdrop of increasingly severe global energy situations and increasingly prominent environmental issues, my country has proposed the strategic goal of "carbon peak and carbon neutrality", which has enabled the application of renewable energy and power electronic equipment in power systems to achieve rapid development. However, with the rapid development of new energy generation technologies such as wind power and photovoltaics, the inertia and primary frequency regulation capabilities of power systems have continued to decline, and the frequency indicators of power systems have deteriorated after disturbances. In order to solve the frequency stability problem of power systems after a high proportion of new energy is connected, it is urgently required that new energy stations adopt virtual inertia control and primary frequency regulation control to provide system frequency support capabilities.

[0003] At present, the control strategies for new energy stations to participate in grid frequency regulation are mainly primary frequency regulation control and virtual inertia control. Primary frequency regulation control and virtual inertia control use frequency deviation and frequency change rate as input signals respectively. By adding frequency regulation power to the original power command, the power reference value of the new energy station is changed, aiming to simulate the primary frequency regulation and inertia response function of the synchronous generator. In order to verify whether the frequency regulation control equipped with new energy stations meets the national standards, it is necessary to evaluate the primary frequency regulation control parameters and virtual inertia frequency regulation control parameters of the new energy stations respectively. However, in the existing technology, the frequency regulation power of the grid-connected point of the new energy station is the combined effect of the primary frequency regulation control active power and virtual inertia control. The active power measured based on the PMU at the grid-connected point cannot fully distinguish the active power of the primary frequency regulation control and virtual inertia control. Summary of the invention

[0004] The purpose of the present invention is to provide a method for estimating the virtual inertia and primary frequency regulation parameters of a new energy station. The method can perform a more accurate and detailed evaluation of the primary frequency regulation control parameters and virtual inertia control parameters of the new energy station, which is of great significance for verifying the virtual inertia and primary frequency regulation control capabilities of the new energy station.

[0005] The objective of the present invention is achieved through the following technical solutions:

[0006] A method for estimating virtual inertia and primary frequency modulation parameters of a new energy station, the method comprising:

[0007] Step 1: Obtain the frequency, frequency change rate and active power data of the frequency modulation of the renewable energy based on the PMU installed at the renewable energy station grid connection point;

[0008] Step 2: Filter the acquired frequency, frequency change rate and active power data using a mean filter algorithm and normalize them;

[0009] Step 3: Obtain the time to enter the frequency modulation control evaluation according to the frequency deviation value, and take the average active power 1 second before the frequency modulation time as the active power reference value for the frequency modulation evaluation;

[0010] Step 4: According to the active power value at the time of entering the frequency modulation control evaluation, the frequency modulation active power of the new energy station during the evaluation period is calculated;

[0011] Step 5: Calculate the primary frequency regulation control parameters of the new energy station grid connection point based on the sliding average window according to the grid connection point frequency regulation active power and the time scale of entering the evaluation frequency regulation control moment;

[0012] Step 6: Fit the power external characteristics of the new energy station according to the step experimental power response of the new energy station, calculate the primary frequency modulation additional power based on the primary frequency modulation control parameters obtained in step 5, and strip off the virtual inertia frequency modulation power;

[0013] Step 7: According to the desired virtual inertia frequency modulation power, combined with the frequency change rate filtering data of the grid-connected point PMU, the virtual inertia frequency modulation parameters are calculated based on the identification algorithm.

[0014] It can be seen from the technical solution provided by the present invention that the above method can perform a more accurate and detailed evaluation of the primary frequency regulation control parameters and virtual inertia control parameters of the new energy station, which is of great significance for verifying the virtual inertia and primary frequency regulation control capabilities of the new energy station. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the accompanying drawings required for use in the description of the embodiments will be briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other accompanying drawings can be obtained based on these accompanying drawings without paying creative work.

[0016] Figure 1 A schematic flow chart of a method for estimating virtual inertia and primary frequency modulation parameters of a new energy station provided by an embodiment of the present invention;

[0017] Figure 2 This is the virtual inertia and primary frequency modulation control active power diagram of the new energy station in the example of the present invention;

[0018] Figure 3 This is a graph of the evaluation results of the primary frequency regulation control parameters of the new energy station in the example of the present invention;

[0019] Figure 4 This is a diagram of the evaluation results of the virtual inertia frequency modulation control parameters of the new energy station in the example of the present invention;

[0020] Figure 5This is a comparison chart of the virtual inertia frequency modulation power increase and fitting data of the new energy station example given in the present invention. DETAILED DESCRIPTION

[0021] The following is a clear and complete description of the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings 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, which does not constitute a limitation of the present invention. 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.

[0022] The following will further describe the embodiments of the present invention in detail in conjunction with the accompanying drawings. The contents not described in detail in the embodiments of the present invention belong to the prior art known to professionals in the field. In the embodiments of the present invention, if specific conditions are not specified, they are carried out according to the conditions of normal conditions in the field or the manufacturer's recommendations. If the manufacturer is not specified in the reagents or instruments in the embodiments of the present invention, they are all conventional products that can be purchased commercially.

[0023] like Figure 1 The figure shows a flow chart of a method for estimating virtual inertia and primary frequency modulation parameters of a new energy station provided by an embodiment of the present invention, the method comprising:

[0024] Step 1: Obtain the frequency, frequency change rate and active power data of the frequency modulation of the renewable energy based on the PMU installed at the renewable energy station grid connection point;

[0025] Step 2: Filter the acquired frequency, frequency change rate and active power data using a mean filter algorithm and normalize them;

[0026] In this step, the acquired frequency, frequency change rate and active power are filtered using a mean filtering algorithm, as shown in the following formula:

[0027]

[0028] Wherein: f is the frequency of the grid-connected point of the new energy station; f(n) is the frequency value of the grid-connected point at the nth moment; df / dt is the frequency change rate of the grid-connected point of the new energy station; df(n) / dt is the frequency change rate value of the grid-connected point at the nth moment; P is the active power of the grid-connected point of the new energy station; P(n) is the active value of the grid-connected point at the nth moment; f(n)' is the mean filtered value of the grid-connected point frequency at the nth moment; df(n)' / dt is the mean filtered value of the frequency change rate of the grid-connected point at the nth moment; P(n)' is the mean filtered value of the active power of the grid-connected point at the nth moment; W is the number of mean filter windows, ranging from 5 to 20, and the value in this application is 15;

[0029] The filtered data is normalized as shown below:

[0030]

[0031] Where P N is the rated power of the new energy unit, which is determined according to the rated power of the units participating in the frequency regulation; f0 is the standard frequency of the power grid, which is 50Hz in my country; f filter is the frequency data after filtering; df / dt filter is the frequency change rate data after filtering; P filter is the active power of the new energy unit after filtering; f, df / dt, and P are the normalized frequency, frequency change rate, and active power data of the new energy unit, respectively.

[0032] Step 3: Obtain the time to enter the frequency modulation control evaluation according to the frequency deviation value, and take the average active power 1 second before the frequency modulation time as the active power reference value for the frequency modulation evaluation;

[0033] In this step, the frequency control entry time t0 is obtained from the frequency deviation value, and the active power average value 1 second before the frequency control entry time is calculated as the active power reference value at the evaluation time, as shown in the following formula:

[0034] |△f(t0)|=|f(t0)-f0|=△f db

[0035] Where: Δf(t0) is the deviation of the grid connection point frequency relative to the nominal frequency. When the frequency deviation is the dead zone of the new energy station frequency control, the time is recorded as t0, and the frequency value at this time is f(t0); Δf db It is the dead zone of frequency control for new energy stations;

[0036]

[0037] Where: P0 is the active power reference value for evaluating frequency modulation control; T s is the power sampling time interval, and the PMU sampling interval is 20ms.

[0038] Step 4: According to the active power value at the time of entering the frequency modulation control evaluation, the frequency modulation active power of the new energy station during the evaluation period is calculated;

[0039] In this step, according to the active power value at the time of entering the frequency modulation control, the difference between the measured active power during the evaluation period and the active power at the time of entering the evaluation is calculated, which is the frequency modulation active power of the new energy station, expressed as:

[0040] AP(t)=P(t)-P0

[0041] Where: ΔP(t) is the frequency regulation active power of the new energy station grid connection point; P(t) is the active power of the new energy station grid connection point; P0 is the active power reference value for evaluating the frequency regulation control moment.

[0042] Step 5: Calculate the primary frequency regulation control parameters of the new energy station grid connection point based on the sliding average window according to the grid connection point frequency regulation active power and the time scale of entering the evaluation frequency regulation control moment;

[0043] In this step, according to the frequency modulation active power of the new energy station and the time scale of entering the frequency modulation control, the primary frequency modulation control parameters of the new energy station grid connection point are calculated based on the sliding average window, which is expressed as:

[0044]

[0045] Where: f db The dead zone of frequency modulation control is 0.033Hz~0.05Hz according to the current standard; t w is the window length of the sliding average evaluation method, which can be selected manually. Here, t w 99; K REU (t n ) is the frequency modulation coefficient evaluation value of the nth sampling point.

[0046] Step 6: Fit the power external characteristics of the new energy station according to the step experimental power response of the new energy station, calculate the primary frequency modulation additional power based on the primary frequency modulation control parameters obtained in step 5, and strip off the virtual inertia frequency modulation power;

[0047] In this step, the specific calculation formula is:

[0048]

[0049] Where: G REU (s) is the dynamic transfer function of the power of the new energy unit; T REU is the comprehensive response time constant of the new energy unit, which is obtained by fitting the time constant of the new energy frequency modulation power step response; s is the Laplace operator;

[0050]

[0051] Where: ΔP v.p (t n+1 ) is the additional power generated by the frequency modulation of the new energy station at time n+1; T s is the power sampling time interval; ΔP v.p (t n ) is the additional power generated by the primary frequency regulation of the new energy station at time n; Δf(t n ) is the frequency deviation of the new energy station at time n;

[0052] AP v.i (t) = AP (t) - AP v.p (t)

[0053] In the formula, ΔP v.i (t) is the virtual inertia frequency modulation power added by the new energy station; ΔP v.p (t) is the primary frequency modulation power increase.

[0054] Step 7: According to the desired virtual inertia frequency modulation power, combined with the frequency change rate filtering data of the grid-connected point PMU, the virtual inertia frequency modulation parameters are calculated based on the identification algorithm.

[0055] In this step, the specific process is as follows:

[0056]

[0057] Where: ΔP v.i (t n+1 ) is the virtual inertia frequency modulation power increase of the new energy station at time n+1; ΔP v.i (t n ) is the virtual inertia frequency modulation power increase of the new energy station at time n; df / dt(t n ) is the frequency change rate of the new energy station at time n;

[0058]

[0059] Where: minL[ΔPv.i,ΔP ～ REU (H REU_est )] is the minimum objective function between the fitting value and the actual value of the virtual inertia frequency modulation power of the new energy station; H REU_est is the evaluation value of the virtual inertia frequency modulation control coefficient; ΔP ～ REU (H REU_est ) is the virtual inertia frequency modulation power fitting value; ΔP ～ REU (H REU_est )(i) is the fitting value of the virtual inertia frequency modulation power at the i-th moment.

[0060] In the following, a real-time digital simulation system (RTDS) is used to build a regional power grid model containing a new energy station, and a semi-physical closed-loop real-time simulation system is constructed through a new energy station frequency controller, PMU equipment, and an evaluation system. A sudden load increase disturbance is applied to the RTDS model, and the built-in control parameters of the frequency controller are used to set the new energy station energy storage in the model for frequency modulation response, simulating actual engineering application scenarios, and explaining the method of the present invention.

[0061] like Figure 2 The figure shows the virtual inertia and primary frequency modulation control active power diagram of the new energy station in the example of the present invention. Figure 3 The figure shows the result of the primary frequency regulation control parameter evaluation of the new energy station in the present invention. Figure 4 The figure shows the evaluation result of the virtual inertia frequency modulation control parameters of the new energy station in the example of the present invention. Figure 5 The figure shows the comparison of the virtual inertia frequency modulation power increase and the fitting data of the new energy station in the example of the present invention. The steps of estimating the control parameters of the primary frequency modulation and virtual inertia frequency modulation of the new energy station by using the frequency, frequency change rate and active power of the grid-connected point after filtering are as follows:

[0062] 1. Obtain the active power value and frequency value at the time of evaluation based on the frequency change rate and the frequency deviation value, and perform evaluation data preprocessing;

[0063] 2. Calculate the primary frequency regulation control parameters of the new energy station based on the filtered active power deviation and frequency change rate;

[0064] 3. According to the calculation results of primary frequency modulation control parameters and the external characteristics of new energy power response, the virtual inertia frequency modulation power is stripped off and the virtual inertia frequency modulation parameters are evaluated.

[0065] Depend on Figure 3 , 4 It can be seen that, using the method proposed in the present invention, the frequency, frequency change rate and active power of the new energy station can be analyzed, and the primary frequency regulation and virtual inertia frequency regulation control parameters of the new energy station can be extracted using the measured data.

[0066] Depend on Figure 2 , 5 It can be seen that the analysis of the active power response of the present invention and the proposed method for evaluating the frequency regulation control parameters of the new energy station can correctly decouple the additional power generated by the primary frequency regulation control of the new energy station and the additional power generated by the virtual inertia, which can prove that the present invention can calculate the frequency regulation control parameters of the new energy station more accurately.

[0067] It can be seen from the above embodiments that the method proposed in the present invention can make a reasonable and accurate estimate of the frequency modulation control parameters of the new energy station. According to the frequency, frequency change rate and active power data collected by the new energy station grid connection point, there is no need to identify the size of the disturbance power. The frequency modulation control parameters of the new energy station can be estimated by processing the measured data using the method proposed in the present invention.

[0068] It is worth noting that the contents not described in detail in the embodiments of the present invention belong to the prior art known to professional and technical personnel in the field.

[0069] In summary, the method described in the embodiment of the present invention has the following advantages:

[0070] 1. The method of the present invention can be based on the measured active power and frequency data of the PMU at the grid connection point of the new energy station. On the basis of filtering the measured data, the disturbance data can be used to theoretically evaluate the primary frequency modulation control parameters of the new energy station;

[0071] 2. By considering the new energy power response, the primary frequency regulation active power and virtual inertia frequency regulation active power of the new energy station are decoupled. The virtual inertia frequency regulation parameters are evaluated in combination with the frequency change rate data of the new energy station grid connection point. This is of great significance for verifying the frequency active support grid capability of the new energy station configuration.

[0072] In addition, a person skilled in the art can understand that all or part of the steps in the above-mentioned embodiment method can be implemented by instructing related hardware through a program, and the corresponding program can be stored in a computer-readable storage medium. The above-mentioned storage medium can be a read-only memory, a disk or an optical disk, etc.

[0073] The above is only a preferred specific embodiment of the present invention, but the protection scope of the present invention is not limited thereto. Any changes or substitutions that can be easily thought of by any technician familiar with the technical field within the technical scope disclosed in the present invention should be included in the protection scope of the present invention. Therefore, the protection scope of the present invention should be based on the protection scope of the claims. The information disclosed in the background technology section of this article is only intended to deepen the understanding of the overall background technology of the present invention, and should not be regarded as an admission or in any form that the information constitutes prior art known to those skilled in the art.

Claims

1. A method for estimating virtual inertia and primary frequency modulation parameters of a new energy station, characterized in that: The method comprises: Step 1: Obtain the frequency, frequency change rate and active power data of the frequency modulation of the renewable energy based on the PMU installed at the renewable energy station grid connection point; Step 2: Filter the acquired frequency, frequency change rate and active power data using a mean filter algorithm and normalize them; Step 3: Obtain the time to enter the frequency modulation control evaluation according to the frequency deviation value, and take the average active power 1 second before the frequency modulation time as the active power reference value for the frequency modulation evaluation; Step 4: According to the active power value at the time of entering the frequency modulation control evaluation, the frequency modulation active power of the new energy station during the evaluation period is calculated; Step 5: Calculate the primary frequency regulation control parameters of the new energy station grid connection point based on the sliding average window according to the grid connection point frequency regulation active power and the time scale of entering the evaluation frequency regulation control moment; Step 6: Fit the power external characteristics of the new energy station according to the step experimental power response of the new energy station, calculate the primary frequency modulation additional power based on the primary frequency modulation control parameters obtained in step 5, and strip off the virtual inertia frequency modulation power; Step 7: According to the desired virtual inertia frequency modulation power, combined with the frequency change rate filtering data of the grid-connected point PMU, the virtual inertia frequency modulation parameters are calculated based on the identification algorithm.

2. The method for estimating virtual inertia and primary frequency modulation parameters of a new energy station according to claim 1, characterized in that: In step 2, the obtained frequency, frequency change rate and active power are filtered using a mean filtering algorithm, as shown in the following formula: Where: f is the frequency of the grid-connected point of the new energy station; f(n) is the frequency value of the grid-connected point at the nth moment; df / dt is the frequency change rate of the grid-connected point of the new energy station; df(n) / dt is the frequency change rate value of the grid-connected point at the nth moment; P is the active power of the grid-connected point of the new energy station; P(n) is the active value of the grid-connected point at the nth moment; f(n)' is the mean filtered value of the grid-connected point frequency at the nth moment; df(n)' / dt is the mean filter value of the frequency change rate of the grid connection point at the nth moment; P(n)' is the mean filter value of the active power of the grid connection point at the nth moment; W is the number of mean filter windows; The filtered data is normalized as shown below: Where P N is the rated power of the new energy unit, which is determined according to the rated power of the units participating in the frequency regulation; f0 is the standard frequency of the power grid; f filter is the frequency data after filtering; df / dt filter is the frequency change rate data after filtering; P filter is the active power of the new energy unit after filtering; f, df / dt, and P are the normalized frequency, frequency change rate, and active power data of the new energy unit, respectively.

3. The method for estimating virtual inertia and primary frequency modulation parameters of a new energy station according to claim 1 is characterized in that: In step 3, the frequency control entry time t0 is obtained from the frequency deviation value, and the active power average value 1 second before the frequency control entry time is calculated as the active power reference value at the evaluation time, as shown in the following formula: |Δf(t0)|=|f(t0)-f0|=Δf db Where: Δf(t0) is the deviation of the grid connection point frequency relative to the nominal frequency. When the frequency deviation is the dead zone of the new energy station frequency control, the time is recorded as t0, and the frequency value at this time is f(t0); Δf db It is the dead zone of frequency control for new energy stations; Where: P0 is the active power reference value for evaluating frequency modulation control; T s is the power sampling time interval.

4. The method for estimating virtual inertia and primary frequency modulation parameters of a new energy station according to claim 3 is characterized in that: In step 4, according to the active power value at the time of entering the frequency modulation control, the difference between the measured active power during the evaluation period and the active power at the time of entering the evaluation is calculated, which is the frequency modulation active power of the new energy station, expressed as: ΔP(t)=P(t)-P0 Where: ΔP(t) is the frequency regulation active power of the new energy station grid connection point; P(t) is the active power of the new energy station grid connection point; P0 is the active power reference value for evaluating the frequency regulation control moment.

5. The method for estimating virtual inertia and primary frequency modulation parameters of a new energy station according to claim 1 is characterized in that: In step 5, according to the frequency regulation active power of the new energy station and the time scale of entering the frequency regulation control, the primary frequency regulation control parameters of the new energy station grid connection point are calculated based on the sliding average window, which is expressed as: Where: f db is the frequency modulation control dead zone; t w is the window length of the moving average evaluation method; K REU (t n ) is the frequency modulation coefficient evaluation value of the nth sampling point.

6. The method for estimating virtual inertia and primary frequency modulation parameters of a new energy station according to claim 1 is characterized in that: In step 6, the specific calculation formula is: Where: G REU (s) is the dynamic transfer function of the power of the new energy unit; T REU is the comprehensive response time constant of the new energy unit, which is obtained by fitting the time constant of the new energy frequency modulation power step response; s is the Laplace operator; Where: ΔP v.p (t n+1 ) is the additional power generated by the frequency modulation of the new energy station at time n+1; T s is the power sampling time interval; ΔP v.p (t n ) is the additional power generated by the primary frequency regulation of the new energy station at time n; Δf(t n ) is the frequency deviation of the new energy station at time n; ΔP v.i (t)=ΔP(t)-ΔP vp (t) In the formula, ΔP v.i (t) is the virtual inertia frequency modulation power added by the new energy station; ΔP v.p (t) is the primary frequency modulation power increase.

7. The method for estimating virtual inertia and primary frequency modulation parameters of a new energy station according to claim 6 is characterized in that: In step 7, the specific process is: Where: ΔP v.i (t n+1 ) is the virtual inertia frequency modulation power increase of the new energy station at time n+1; ΔP v.i (t n ) is the virtual inertia frequency modulation power increase of the new energy station at time n; df / dt(t n ) is the frequency change rate of the new energy station at time n; Where: minL[ΔPv.i,ΔP ～ REU (H REU_est )] is the minimum objective function between the fitting value and the actual value of the virtual inertia frequency modulation power of the new energy station; H REU_est is the evaluation value of the virtual inertia frequency modulation control coefficient; ΔP ～ REU (H REU_est ) is the virtual inertia frequency modulation power fitting value; ΔP ～ REU (H REU_est )(i) is the fitting value of the virtual inertia frequency modulation power at the i-th moment.

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