A Power System Inertia Assessment Method Based on Energy Function

Abstract

This invention discloses a power system inertia assessment method based on energy function, comprising the following steps: collecting system port data and preprocessing the data; calculating the magnitude of port energy flow using measurement and calculating each component; calculating the dissipated energy at each generator port, performing linear fitting on the dissipated energy flow to obtain the damping term, calculating the inertial time constant H, comparing it with the true value, and selecting an appropriate time window.

Description

Technical Field

[0001] This invention relates to the analysis of inertia levels after disturbances in power systems, specifically a power system inertia assessment method based on energy functions. Background Technology

[0002] In recent years, new energy systems have become the development direction of power systems. In power systems with a high proportion of new energy sources, the increased penetration rate of wind farms and photovoltaic power stations with low or even zero inertia has reduced the overall inertia of the power system, which seriously affects the stability and reliability of the power system. The inertia of the power system is crucial for its stable operation, and it is not static. Shutdown disturbances and the integration of new energy sources can cause changes in the inertia of the power system, which can have a significant impact on its stability. Therefore, researching methods for estimating the inertia of power systems is of great significance. Summary of the Invention

[0003] The purpose of this invention is to provide a method that, based on a power system synchronous machine model, uses signal analysis tools to process random response data and uses port energy flow to evaluate generator inertia. This method has wide applications, strong adaptability, and high practical application value in power system inertia estimation.

[0004] A method for evaluating the inertia of a power system based on an energy function includes the following steps:

[0005] S1. Collect system port data and preprocess the data;

[0006] S2. Calculate the magnitude of the energy flow at the port using measurement and calculate each component;

[0007] S3. Calculate the energy dissipation at each generator port, and perform linear fitting on the dissipated energy flow to obtain the damping term;

[0008] S4. Calculate the inertial time constant H, compare it with the true value, and select an appropriate time window.

[0009] Further, step S1 specifically includes:

[0010] S11. Monitor the active power P, reactive power Q, voltage U, and phase angle θ of the generator in the power system under random disturbances, and collect relevant electrical quantity data windows for more than ten minutes.

[0011] S12. Perform filtering preprocessing on the generator's active power P, reactive power Q, voltage U, and phase angle θ within the time window.

[0012] Further, step S12 specifically includes:

[0013] Calculate the changes in the generator's active power P, reactive power Q, voltage U, and phase angle θ relative to the steady-state values ​​within the calculation time window;

[0014] Calculate the natural logarithm of voltage U, lnU, and apply bandpass filtering to P, Q, lnU, and θ. Then perform detrending and normalization processing to obtain the changes ΔP, ΔQ, ΔlnU, and Δθ.

[0015] Further, step S2 specifically includes:

[0016] S21. Calculate port energy using port quantity measurements;

[0017] S22. Calculate the components of the port energy.

[0018] Further, step S3 includes:

[0019] The energy flow from the power grid into the generator is: W D =∫(ΔP) i dθ i +ΔQ i d(ln U i ))

[0020] The dissipation is processed using an envelope, and the generator damping term is compared.

[0021] Furthermore, step S4 specifically includes: representing the kinetic energy term separately to obtain the inertial time constant H, comparing and analyzing the results, and selecting an appropriate time window.

[0022] Beneficial effects

[0023] This invention proposes an inertia assessment method based on electromechanical response characteristics. Compared with existing methods, this invention, based on the frequency domain perspective, utilizes electromechanical response feature extraction to provide a novel approach for system inertia assessment. This invention eliminates the need for system model identification and extracts electromechanical features through a random subspace algorithm. Attached Figure Description

[0024] To more clearly illustrate the technical solutions in this invention or the prior art, the accompanying drawings involved in the embodiments or the prior art are briefly described below. Obviously, these drawings illustrate several embodiments of the present invention, and those skilled in the art can derive other possible drawings based on these drawings without creative effort. The purpose of the drawings is limited to illustrating specific embodiments and does not limit the scope of the present invention.

[0025] Figure 1 This is a schematic diagram of the WSCC9 node system.

[0026] Figure 2This is a flowchart of inertia evaluation based on energy function provided in an embodiment of the present invention;

[0027] Figure 3 It is a WSCC9 node system quantity measurement;

[0028] Figure 4 It is a diagram of dissipated energy and its envelope;

[0029] Figure 5 It is the energy dissipation envelope and damping term;

[0030] Figure 6 This is a schematic diagram of the time window for inertia assessment measurement data. Detailed Implementation

[0031] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the protection scope of the present invention.

[0032] 1. Port Measurement and Acquisition

[0033] To determine whether the system is under random data conditions, obtain the port measurement data of each unit during the operation of the power system, including the active power P, reactive power Q, voltage U, and phase angle θ of each unit.

[0034] S11. Monitor the active power P, reactive power Q, voltage U, and phase angle θ of the generator in the power system under random disturbances, and collect relevant electrical quantity data windows for more than ten minutes.

[0035] S12. Perform filtering preprocessing on the generator's active power P, reactive power Q, voltage U, and phase angle θ within the time window.

[0036] S12 specifically includes: calculating the changes in the generator's active power P, reactive power Q, voltage U, and phase angle θ relative to their steady-state values ​​within the calculation time window; calculating the natural logarithm of voltage U, lnU; performing bandpass filtering on P, Q, lnU, and θ; and performing detrending and normalization processing to obtain the changes ΔP, ΔQ, ΔlnU, and Δθ.

[0037] 2. Measurement Preprocessing

[0038] If the system is running normally, the electrical quantity data of each generator obtained in step 1 will be preprocessed to obtain the steady-state value and steady-state change of each variable, including the electrical quantities during steady-state operation of the system, and then used for subsequent analysis of the data of electrical quantity changes relative to steady-state value.

[0039] 3. Calculation of energy dissipation at generator ports

[0040] The port dissipation energy of each generator in the system is calculated using the following formula:

[0041] W D =∫(ΔP) i dθ i +ΔQ i d(ln U i ))

[0042] Among them, P i Q i U represents the active and reactive power at the generator port. i θ i For generator terminal voltage amplitude and phase angle

[0043] 4. Result Evaluation

[0044] Based on the energy at each generator port in the power system obtained above, as well as the internal components, the inertial time constant H is calculated, and the error between it and the true value is calculated, as shown in Table 1.

[0045] Table 1. Estimation results of synchronous generator unit inertia

[0046]

[0047] The above technical solutions only embody the preferred technical solutions of the present invention. Any modifications that may be made by those skilled in the art to certain parts therein embody the principles of the present invention and fall within the protection scope of the present invention.

Claims

1. A method for evaluating the inertia of a power system based on an energy function, characterized in that, Includes the following steps: S1. Collect system port data and preprocess the data; S2. Calculate the magnitude of the energy flow at the port using measurement and calculate each component; S3. Calculate the energy dissipation at each generator port, and perform linear fitting on the dissipated energy flow to obtain the damping term; S4. Calculate the inertial time constant H, compare it with the true value, and select an appropriate time window.

2. The power system inertia assessment method based on energy function according to claim 1, characterized in that, Step S1 specifically includes: S11. Monitor the active power P, reactive power Q, voltage U, and phase angle θ of the generator in the power system under random disturbances, and collect relevant electrical quantity data windows for more than ten minutes. S12. Perform filtering preprocessing on the generator's active power P, reactive power Q, voltage U, and phase angle θ within the time window.

3. The method for evaluating the damping of local components in a power system based on random response signals according to claim 2, characterized in that, Step S12 specifically includes: Calculate the changes in the generator's active power P, reactive power Q, voltage U, and phase angle θ relative to the steady-state values ​​within the calculation time window; Calculate the natural logarithm of voltage U, lnU, and apply bandpass filtering to P, Q, lnU, and θ. Then perform detrending and normalization processing to obtain the changes ΔP, ΔQ, ΔlnU, and Δθ.

4. The power system inertia evaluation method based on energy function according to claim 3, characterized in that, Step S2 specifically includes: S21. Calculate port energy using port quantity measurements; S22. Calculate the components of the port energy.

5. The power system inertia evaluation method based on energy function according to claim 4, characterized in that, Step S3 includes: The energy flow from the power grid into the generator is: W D =∫(ΔP) i dθ i +ΔQ i d(lnU i )) The dissipation is processed using an envelope, and the generator damping term is compared.

6. The power system inertia evaluation method based on energy function according to claim 5, characterized in that, Step S4 specifically includes: representing the kinetic energy term separately to obtain the inertial time constant H, comparing and analyzing the results, and selecting an appropriate time window.

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