A new energy station virtual inertia and primary frequency modulation parameter estimation method

Abstract

The application discloses a kind of new energy field station virtual inertia and primary frequency modulation parameter estimation method, this method is based on the electrical quantity data of new energy field station filtering, obtains the active power of entering frequency modulation time and obtains the frequency modulation active of new energy field station grid-connected point in frequency modulation period, and then based on the calculation of primary frequency modulation parameter of sliding average window;Then extract the virtual inertia active power in station frequency modulation active, finally based on virtual inertia active calculation new energy field station grid-connected point equivalent virtual inertia coefficient.The above-mentioned method can be more accurate and detailed evaluation to the primary frequency modulation control parameter and virtual inertia control parameter of new energy field station, and it is of great significance to check the virtual inertia and primary frequency modulation control capability of new energy field station.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of new energy frequency modulation parameter evaluation, and particularly relates to a method for estimating virtual inertia and primary frequency modulation parameters of a new energy station. BACKGROUND

[0002] Under the background of increasingly severe global energy situation and increasingly prominent environmental problems, with the rapid development of new energy power generation technologies such as wind power and photovoltaic power, the inertia and primary frequency modulation capacity of the power system are continuously declining, and the frequency index of the power system after disturbance is deteriorating. In order to solve the frequency stability problem of the power system after high proportion of new energy access, it is urgently required that the new energy station adopts virtual inertia control and primary frequency modulation control to provide the ability of system frequency support.

[0003] At present, the control strategy of the new energy station participating in the grid frequency modulation mainly includes primary frequency modulation control and virtual inertia control. The primary frequency modulation control and the virtual inertia control respectively take the frequency deviation and the frequency change rate as the input signals, change the power reference value of the new energy station by adding the frequency modulation power to the original power instruction, and aim to simulate the primary frequency modulation and inertia response function of the synchronous generator. In order to check whether the frequency modulation control provided by the new energy station meets the national standard, it is necessary to evaluate the primary frequency modulation control parameters and the virtual inertia frequency modulation control parameters of the new energy station respectively. However, in the prior art, the grid-connected point frequency modulation power is the comprehensive effect of the primary frequency modulation control active power and the virtual inertia control, and based on the PMU measurement active power, the active power of the primary frequency modulation control and the virtual inertia control cannot be fully distinguished. SUMMARY

[0004] The purpose of the present application is to provide a method for estimating virtual inertia and primary frequency modulation parameters of a new energy station, which can more accurately and meticulously evaluate the primary frequency modulation control parameters and the virtual inertia control parameters of the new energy station, and has important significance for verifying the virtual inertia and primary frequency modulation control capacity of the new energy station.

[0005] The purpose of the present application is achieved by 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, obtaining frequency, frequency change rate and active power data of new energy frequency modulation based on PMU installed at the grid-connected point of the new energy station;

[0008] Step 2, filtering the obtained frequency, frequency change rate and active power data using the mean filtering algorithm, and performing per-unit processing;

[0009] Step 3, obtain the entering evaluation frequency modulation control time according to the deviation value of the frequency, and take the active average value of 1s before the frequency modulation time as the active power reference value for the evaluation of the frequency modulation;

[0010] Step 4, obtain the frequency modulation active power of the new energy station in the evaluation period according to the active power value at the entering evaluation frequency modulation control time;

[0011] Step 5, calculate the primary frequency modulation control parameter of the new energy station grid connection point based on the sliding average window according to the frequency modulation active power of the grid connection point and the time scale at the entering evaluation frequency modulation control time;

[0012] Step 6, fit the power external characteristic of the new energy station according to the step response power of the new energy station step experiment, and calculate the primary frequency modulation power based on the primary frequency modulation control parameter obtained in step 5 to strip out the virtual inertia frequency modulation power;

[0013] Step 7, calculate the virtual inertia frequency modulation parameter based on the identification algorithm according to the virtual inertia frequency modulation power and the frequency change rate filter data of the grid connection point PMU.

[0014] It can be seen from the technical scheme provided by the above-mentioned application that the above-mentioned method can more accurately and meticulously evaluate the primary frequency modulation control parameter and the virtual inertia control parameter of the new energy station, and has important significance for verifying the virtual inertia and primary frequency modulation control capability of the new energy station. BRIEF DESCRIPTION OF DRAWINGS

[0015] In order to more clearly illustrate the technical scheme of the embodiments of the present application, the drawings needed in the embodiment description will be briefly introduced. Obviously, the drawings in the following description are only some embodiments of the present application, and other drawings can be obtained by those skilled in the art without creative labor.

[0016] Figure 1 The flowchart of the estimation method of the virtual inertia and primary frequency modulation parameter of the new energy station provided by the embodiments of the present application;

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

[0018] Figure 3 The primary frequency modulation control parameter evaluation result diagram of the new energy station in the example of the present application;

[0019] Figure 4 The virtual inertia frequency modulation control parameter evaluation result diagram of the new energy station in the example of the present application;

[0020] Figure 5A new energy station virtual inertia frequency modulation power and fitting data comparison chart of the example of the present application. DETAILED DESCRIPTION

[0021] The technical solutions in the embodiments of the present application will be apparently and completely described below with reference to the drawings in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, rather than all the embodiments of the present application, which does not constitute a limitation to the present application. Based on the embodiments of the present application, all other embodiments obtained by those skilled in the art without creative labor fall within the protection scope of the present application.

[0022] The embodiments of the present application will be further described in detail below with reference to the drawings. The contents not described in detail in the embodiments of the present application belong to the prior art known to those skilled in the art. The specific conditions not noted in the embodiments of the present application are carried out according to the conventional conditions in the art or the suggested conditions of the manufacturer. The reagents or instruments used in the embodiments of the present application are not noted the manufacturer, which are all conventional products that can be obtained by market purchase.

[0023] As Figure 1 shown is a flowchart of an estimation method of virtual inertia and primary frequency modulation parameters of a new energy station provided by the embodiments of the present application, the method comprises:

[0024] Step 1, obtaining frequency, frequency rate of change and active power data of new energy frequency modulation based on PMU installed at the grid-connected point of the new energy station;

[0025] Step 2, filtering the obtained frequency, frequency rate of change and active power data by using mean filtering algorithm, and performing per-unit processing;

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

[0027]

[0028] In the formula, 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 rate of change of the grid-connected point of the new energy station; df(n) / dt is the frequency rate of change 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 power value of the grid-connected point at the nth moment; f(n)' is the mean filtering value of the frequency of the grid-connected point at the nth moment; df(n)' / dt is the mean filtering value of the frequency rate of change of the grid-connected point at the nth moment; P(n)' is the mean filtering value of the active power of the grid-connected point at the nth moment; and W is the mean filtering window number, the value range of which is 5-20, and the value in the present application is 15.

[0029] The filtered data is processed by per-unit, as shown in the following formula:

[0030]

[0031] In the formula, P N is the rated power of new energy units, which is valued according to the rated power of units participating in frequency modulation; f0 is the standard frequency of the power grid, which is 50 Hz in China; f filter is the filtered frequency data; df / dt filter is the filtered frequency change rate data; P filter is the filtered active power of new energy units; f, df / dt and P are the unitized frequency, frequency change rate and active power data of new energy units, respectively.

[0032] Step 3: According to the deviation value of the frequency, the time of entering the evaluation frequency modulation control is obtained, and the average value of the active power 1 s before the frequency modulation time is taken as the active power reference value of the frequency modulation evaluation;

[0033] In this step, the time t0 of entering the frequency modulation control is obtained from the deviation value of the frequency, and the average value of the active power 1 s before the time of entering the frequency modulation 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] In the formula, Δf(t0) is the deviation value of the frequency of the grid connection point relative to the nominal frequency, and when the frequency deviation is the frequency control dead zone of the new energy station, the time is recorded as t0, and the frequency value at this time is f(t0); Δf db is the frequency control dead zone of the new energy station;

[0036]

[0037] In the formula, P0 is the active power reference value at the time of evaluating the frequency modulation control; T s is the power sampling time interval, and the PMU sampling interval is 20 ms.

[0038] Step 4: According to the active power value at the time of entering the evaluation frequency modulation control, the active power of the new energy station in 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 in the evaluation period and the active power at the time of entering the evaluation is calculated, that is, the active power of the new energy station for frequency modulation, which is expressed as:

[0040] ΔP(t)=P(t)-P0

[0041] ΔP(t) is the active power of the new energy station grid-connected point for frequency modulation; P(t) is the active power of the new energy station grid-connected point; P0 is the active power reference value at the time of evaluating the frequency modulation control.

[0042] Step 5, based on the active power of the grid-connected point for frequency modulation and the time scale at the time of evaluating the frequency modulation control, the primary frequency modulation control parameter of the new energy station grid-connected point is calculated based on a sliding average window.

[0043] In this step, based on the active power of the new energy station for frequency modulation and the time scale at the time of evaluating the frequency modulation control, the primary frequency modulation control parameter of the new energy station grid-connected point is calculated based on a sliding average window, which is expressed as:

[0044]

[0045] In the formula, f db is the frequency modulation control dead zone, which is 0.033 Hz to 0.05 Hz according to the current standard; t w is the window length of the sliding average evaluation method, which can be artificially selected, and here t w is taken as 99; K REU (t n ) is the frequency modulation coefficient evaluation value of the nth sampling point.

[0046] Step 6, the power external characteristic of the new energy station is fitted according to the power response of the step experiment of the new energy station, and the primary frequency modulation power is calculated based on the primary frequency modulation control parameter obtained in step 5, and the virtual inertia frequency modulation power is stripped out.

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

[0048]

[0049] In the formula, G REU (s) is the power dynamic transfer function 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 from the step response of the new energy frequency modulation power; s is the Laplace operator.

[0050]

[0051] In the formula, ΔP v.p (t n+1 ) is the primary frequency modulation power of the new energy station at time n+1; T s is the power sampling time interval; ΔP v.p (t n ) is the primary frequency modulation power 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, AP v.i (t) is the virtual inertia frequency modulation power of the new energy station stripped out; AP v.p (t) is the primary frequency modulation power.

[0054] Step 7, according to the virtual inertia frequency modulation power obtained, combining 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] In the formula, AP v.i (t n+1 ) is the virtual inertia frequency modulation power of the new energy station at n+1 time; AP v.i (t n ) is the virtual inertia frequency modulation power of the new energy station at n time; df / dt(t n ) is the frequency change rate of the new energy station at n time.

[0058]

[0059] In the formula, minL[APv.i, AP ～ REU (H REU_est )] is the minimum target function between the virtual inertia frequency modulation power fitting value and the actual value of the new energy station; H REU_est is the virtual inertia frequency modulation control coefficient evaluation value; AP ～ REU (H REU_est ) is the virtual inertia frequency modulation power fitting value; AP ～ REU (H REU_est )(i) is the virtual inertia frequency modulation power fitting value at the i time.

[0060] In the following, by adopting a real-time digital simulation system (RTDS), a certain regional power grid model containing a new energy station is built, a semi-physical closed-loop real-time simulation system is constructed through a new energy station frequency controller, a PMU device and an evaluation system. A load sudden increase disturbance is applied in the RTDS model, the built-in control parameters of the frequency controller are used, the new energy station energy storage in the model is set to respond to frequency modulation, the actual engineering application scene is simulated, and the method described in the application is explained.

[0061] As Figure 2 Fig. 1 is a diagram of active power of a new energy station according to an example of the present application, as Figure 3 Fig. 2 is a diagram of a primary frequency modulation control parameter evaluation result of a new energy station according to an example of the present application, as Figure 4 Fig. 3 is a diagram of a virtual inertia frequency modulation control parameter evaluation result of a new energy station according to an example of the present application, as Figure 5 Fig. 4 is a diagram of a virtual inertia frequency modulation control parameter evaluation result of a new energy station according to an example of the present application. The steps of estimating the primary frequency modulation and virtual inertia frequency modulation control parameters of the new energy station by using the filtered frequency, frequency change rate and active power of the grid-connected point are as follows:

[0062] 1. The active power value and frequency value at the evaluation time are obtained from the frequency change rate and frequency deviation value, and the evaluation data is preprocessed;

[0063] 2. The primary frequency modulation control parameters of the new energy station are calculated according to the filtered active power deviation and frequency change rate;

[0064] 3. The virtual inertia frequency modulation power is stripped according to the primary frequency modulation control parameter calculation result and the new energy power response external characteristic, and the virtual inertia frequency modulation parameters are evaluated.

[0065] As Figure 3 , 4 It can be seen that, by using the method proposed in the present application, the primary frequency modulation and virtual inertia frequency modulation control parameters of the new energy station can be extracted by analyzing the frequency, frequency change rate and active power of the new energy station, and using the measurement data.

[0066] As Figure 2 , 5 It can be seen that, by using the method proposed in the present application, the primary frequency modulation and virtual inertia frequency modulation control parameters of the new energy station can be extracted by analyzing the frequency, frequency change rate and active power of the new energy station, and using the measurement data.

[0067] As can be seen from the above examples, the method proposed in the present application can reasonably and accurately estimate the frequency modulation control parameters of the new energy station. According to the frequency, frequency change rate and active power data collected at the grid-connected point of the new energy station, without identifying the disturbance power size, the measurement data is processed by using the method proposed in the present application, and the frequency modulation control parameters of the new energy station can be estimated.

[0068] It is worth noting that the contents not described in detail in the embodiments of the present application belong to the prior art known to those skilled in the art.

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

[0070] 1、The method can evaluate the primary frequency modulation control parameter of the new energy station based on the measured active power and frequency data of the new energy station grid-connected point, and theoretically evaluate the primary frequency modulation control parameter of the new energy station based on the filtered data and the data after disturbance;

[0071] 2、The active power of the primary frequency modulation of the new energy station and the active power of the virtual inertia frequency modulation are decoupled by considering the power response of the new energy, and the virtual inertia frequency modulation parameter is evaluated combined with the frequency change rate data of the new energy station grid-connected point, which is of great significance for checking and verifying the active power grid support capability of the frequency of the new energy station.

[0072] In addition, those skilled in the art can understand that all or part of the steps in the foregoing method embodiments can be completed by using programs instructing related hardware, and the corresponding programs can be stored in a computer readable storage medium, such as a read-only memory, a magnetic disk or an optical disk.

[0073] The above description is only the preferred embodiment of the present application, but the protection scope of the present application is not limited to this. Any changes or replacements within the technical scope disclosed by the present application can be easily thought by those skilled in the art, and should be covered within the protection scope of the present application. Therefore, the protection scope of the present application should be subject to the protection scope of the claims. The information disclosed in the background section of the present application is only intended to deepen the understanding of the general background of the present application, and should not be regarded as acknowledging or implying in any form that the information constitutes the prior art known by those skilled in the art.

Claims

1. A method for estimating virtual inertia and primary frequency modulation parameters of a new energy plant station, characterized in that, The method comprises: Step 1, obtaining frequency, frequency change rate and active power data of new energy frequency regulation based on PMU installed at a new energy station grid-connected point; Step 2, filtering the obtained frequency, frequency change rate and active power data by using a mean filtering algorithm, and performing per-unit processing; Step 3, obtaining an entering evaluation frequency regulation control time according to a frequency deviation value, and taking an active average value of 1 s before the frequency regulation time as an active power reference value for evaluation of frequency regulation; Step 4, obtaining frequency regulation active power of the new energy station in an evaluation period according to an active power value at the entering evaluation frequency regulation control time; Step 5, calculating primary frequency regulation control parameters of the new energy station grid-connected point based on a sliding average window according to the grid-connected point frequency regulation active and the entering evaluation frequency regulation control time; Step 6, fitting power external characteristics of the new energy station according to a step experiment power response of the new energy station, and calculating primary frequency regulation power based on the primary frequency regulation control parameters obtained in Step 5, and stripping out virtual inertia frequency regulation power; Step 7, calculating virtual inertia frequency regulation parameters based on an identification algorithm according to the obtained virtual inertia frequency regulation power and combined with frequency change rate filtering data of the grid-connected point PMU.

2. The method of claim 1, wherein, In Step 2, the obtained frequency, frequency change rate and active power are filtered by using a mean filtering algorithm, as shown in the following formula: In the formula, f is the frequency of the new energy station grid-connected point, f(n) is the frequency value of the grid-connected point at the nth time, df / dt is the frequency change rate of the new energy station grid-connected point, df(n) / dt is the frequency change rate value of the grid-connected point at the nth time, P is the active power of the new energy station grid-connected point, P(n) is the active value of the grid-connected point at the nth time, f(n)' is the mean filtering value of the frequency of the grid-connected point at the nth time, df(n)' / dt is the mean filtering value of the frequency change rate of the grid-connected point at the nth time, and P(n)' is the mean filtering value of the active power of the grid-connected point at the nth time; W is the number of mean filtering windows; The filtering data is processed by per-unit, as shown in the following formula: In the formula, P N is the rated power of new energy units, which is valued according to the rated power of units participating in frequency modulation; f0 is the standard frequency of the power grid; f filter is the filtered frequency data; df / dt filter is the filtered frequency change rate data; P filter is the filtered active power of new energy units; f, df / dt and P are the unitized frequency, frequency change rate and active power data of new energy units, respectively.

3. The method of claim 1, wherein, In Step 3, the entering frequency regulation control time t0 is obtained from the frequency deviation value, and the active average value of 1 s before the entering frequency regulation 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 In the formula, Δf(t0) is the deviation value of the grid-connected point frequency from the nominal frequency, when the frequency deviation is the frequency control dead zone of the new energy station, the time is recorded as t0, and the frequency value at this time is f(t0); Δf db is the frequency control dead zone of the new energy station. wherein: P0 is the active power reference value at the moment of evaluation of the frequency control; T s is the power sampling time interval.

4. The method of claim 3, wherein, In Step 4, the difference between the measured active power in the evaluation period and the active power at the entering evaluation time is calculated as the frequency regulation active power of the new energy station, that is, ΔP(t) = P(t) - P0 In the formula, ΔP(t) is the frequency regulation active power of the new energy station grid-connected point, P(t) is the active power of the new energy station grid-connected point, and P0 is the active power reference value at the evaluation frequency regulation control time. In Step 5, the primary frequency regulation control parameters of the new energy station grid-connected point are calculated based on a sliding average window according to the new energy station frequency regulation active power and the entering frequency regulation control time, as shown in the following formula:

5. The method of claim 1, wherein, In Step 6, the specific calculation formula is as follows: In the formula: f db For frequency modulation control dead zone; t w K represents the window length for the moving average evaluation method. REU (t n ) is the frequency modulation coefficient evaluation value of the nth sampling point.

6. The method of claim 1, wherein, s is the Laplace operator; In the formula, G REU (s) is a power dynamic transfer function of the new energy unit; T REU is a comprehensive response time constant of the new energy unit, which is obtained by fitting a time constant of a new energy frequency modulation power step response. In Step 7, the specific process is as follows: wherein: ΔP v.p (t n+1 ) is the new energy station primary frequency modulation incremental power at the n+1 moment; T s is the power sampling time interval; ΔP v.p (t n ) is the new energy station primary frequency modulation incremental power at the n moment; Δf(t n ) is the new energy station frequency deviation at the n moment. ΔP v.i (t) = ΔP(t) - ΔP vp (t) In the formula, ΔP v.i (t) is the virtual inertia frequency modulation power of the new energy power station stripped out; ΔP v.p (t) is the primary frequency modulation power.

7. The method of claim 6, wherein, ​ wherein: ΔP v.i (t n+1 ) is the new energy station virtual inertia frequency modulation incremental power at the n+1 moment; ΔP v.i (t n ) is the new energy station virtual inertia frequency modulation incremental power at the n moment; df / dt(t n ) is the frequency change rate of the new energy station at the n moment; wherein: minL[ΔPv.i, ΔP ～ REU (H REU_est ) is the minimum objective function between the virtual inertia frequency modulation power fitting value and the actual value of the new energy station; H REU_est is the virtual inertia frequency modulation control coefficient evaluation value; ΔP ～ REU (H REU_est ) is the virtual inertia frequency modulation power fitting value; ΔP ～ REU (H REU_est )(i) is the virtual inertia frequency modulation power fitting value at the i-th moment.

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