Frequency modulation method and system based on virtual power plant

Abstract

An embodiment of the present invention provides a frequency regulation method and system based on a virtual power plant. The method includes: obtaining the sensitivity of multiple frequency regulation devices in the virtual power plant to the frequency stability margin in response to a frequency default fault; determining the contribution of multiple frequency regulation devices to the frequency regulation effect based on the sensitivity of the frequency regulation devices to the frequency stability margin, and the controllable active power and the controllable active power cost, and obtaining a contribution ranking; determining the frequency regulation points and control quantities corresponding to the frequency default fault based on the contribution ranking. The present invention calculates the contribution of the frequency regulation device to the frequency regulation effect and obtains the priority of participating in the frequency regulation accordingly, which can facilitate accurate frequency regulation and avoid the occurrence of over-control or under-control problems.

Description

Technical Field

[0001] The present invention relates to the technical field of power systems, and in particular to a frequency regulation method and system based on a virtual power plant. Background Art

[0002] Frequency reflects the balance of active power in the power grid. Compensating for power shortfalls during disturbances and faults is a key task in frequency stability control. After a large power grid shortfall event, frequency regulation is used to compensate for the power shortfall and transition the grid frequency from transient to steady state.

[0003] As thermal power units are replaced by renewable energy and conventional frequency regulation resources are declining, new frequency regulation resources such as distributed power sources, flexible loads, and energy storage are increasingly available. Virtual power plants (VPPs) aggregate flexible sources, loads, and storage to stabilize frequency, making them highly grid-friendly. However, when VPPs participate in system frequency regulation, focusing solely on economic considerations can lead to over- or under-control, failing to achieve optimal frequency regulation effectiveness. Therefore, optimizing the transient frequency regulation capabilities of each VPP's frequency regulation resources is a pressing issue. Summary of the Invention

[0004] The purpose of the embodiments of the present invention is to provide a frequency regulation method and system based on a virtual power plant, which can avoid the occurrence of over-control or under-control problems. The specific technical solution is as follows:

[0005] The present invention provides a frequency modulation method based on a virtual power plant, comprising:

[0006] For frequency default faults, the sensitivity of multiple frequency regulation devices in the virtual power plant to the frequency stability margin is obtained; wherein the frequency default fault is a fault in which the frequency of the power grid node exceeds the limit for a preset period of time;

[0007] Determining the contribution of the plurality of frequency modulation devices to the frequency modulation effect according to the sensitivity of the frequency modulation device to the frequency stability margin, the controllable active power, and the controllable active power cost, and obtaining a contribution ranking;

[0008] The frequency regulation points and control amount corresponding to the frequency default fault are determined according to the contribution ranking; wherein the frequency regulation points are the points of the frequency regulation devices that adjust the active power to restore the frequency to within the dead zone range, and the control amount is the active power adjustment amount of the frequency regulation device.

[0009] Optionally, after obtaining the contribution ranking, the method further includes:

[0010] According to the contribution ranking, the frequency modulation device with the largest contribution is selected to apply all controllable active power;

[0011] If the frequency violation still exists, determine the contribution ranking of the frequency modulation devices that have not applied all the controllable active power, and then return to the step of "selecting the frequency modulation device with the largest contribution to apply all the controllable active power according to the contribution ranking";

[0012] If there is no frequency default, the final contribution ranking is obtained.

[0013] Optionally, before obtaining the sensitivity of multiple frequency regulation devices in the virtual power plant to the frequency stability margin for a frequency default fault, the method further includes:

[0014] Comparing the frequency stability margins of the frequency default faults in the frequency default fault set; wherein the frequency stability margins represent the degree of frequency limit violations;

[0015] A frequency default fault corresponding to the lowest frequency stability margin is selected, and the method of "obtaining the sensitivity of multiple frequency regulation devices in the virtual power plant to the frequency stability margin for the frequency default fault" is executed.

[0016] Optionally, also include:

[0017] For other frequency default faults in the frequency default fault set except the frequency default fault corresponding to the lowest frequency stability margin, all controllable active powers of the corresponding frequency regulation devices are applied in sequence according to the contribution ranking until there is no frequency default, and the frequency regulation points and control quantities corresponding to the other frequency default faults are obtained.

[0018] Optionally, before comparing the frequency stability margin of each frequency default fault in the frequency default fault set, the method further includes:

[0019] Performing time domain simulation on each frequency default fault in the frequency default fault set, and classifying each frequency default fault into two types according to the simulation results: a frequency greater than an upper limit value and a frequency less than a lower limit value;

[0020] The “comparing the frequency stability margins of each frequency default fault in a frequency default fault set” is performed on two types of frequency default fault sets respectively.

[0021] Optionally, before performing time domain simulation on each frequency default fault in the frequency default fault set, the method further includes:

[0022] The grid topology and frequency default fault set are updated periodically.

[0023] Optionally, determining the contribution of the plurality of frequency modulation devices to the frequency modulation effect based on the sensitivity of the frequency modulation device to the frequency stability margin, the controllable active power, and the controllable active power cost includes:

[0024] Calculating a change in the frequency stability margin of the frequency default fault before and after the frequency modulation device performs active power perturbation to obtain a first change; wherein the first change reflects the sensitivity of the frequency modulation device to the frequency stability margin;

[0025] Contributions of the plurality of frequency modulation devices to the frequency modulation effect are determined according to the first variation, the controllable active power of the frequency modulation device, the controllable active power cost, and the variation of the active power.

[0026] Optionally, the method for calculating the first variation includes:

[0027] determining whether the signs of the frequency stability margin of the frequency default fault are consistent before and after the frequency modulation device performs active power perturbation;

[0028] If the signs are consistent, calculating the first variation according to the two frequency stability margins before and after the active power perturbation;

[0029] If the signs are inconsistent, the first variation is calculated according to the frequency stability margin before the perturbation.

[0030] Optionally, determining the contribution ranking of the frequency modulation devices that have not applied all controllable active power includes:

[0031] re-perturbing the active power of the frequency modulation device that has not applied all the controllable active power, calculating the change in the frequency stability margin before and after the perturbation, and obtaining a second change; wherein the second change reflects the sensitivity of the frequency modulation device to the frequency stability margin;

[0032] The contribution of each frequency modulation device to the frequency modulation effect is determined based on the second change, the controllable active power of the frequency modulation device that has re-perturbed active power, the controllable active power cost and the change in active power, and the contribution ranking of the frequency modulation devices that have not applied all the controllable active power is obtained.

[0033] Optionally, determining the frequency regulation points and control amount corresponding to the frequency default fault according to the contribution ranking includes:

[0034] Selecting, in descending order of contribution, a target frequency modulation device that needs to apply all controllable active power when the frequency is restored to within the dead zone range from the contribution ranking;

[0035] The grid node to which the target frequency regulation device belongs is used as the frequency regulation distribution point;

[0036] The total controllable active power of the target frequency modulation device is used as the control variable.

[0037] The present invention also provides a frequency regulation system based on a virtual power plant, comprising:

[0038] control means and at least one frequency modulation means;

[0039] The frequency modulation device is controlled by the control device;

[0040] The control device is used to execute the frequency regulation method based on the virtual power plant as described above.

[0041] Optionally, each of the frequency regulation devices includes one or more of a distributed power source, a flexible load and an energy storage device.

[0042] Embodiments of the present invention provide a frequency regulation method and system based on a virtual power plant. For frequency default failures, the method calculates the sensitivity of multiple frequency regulation devices within the virtual power plant to the frequency stability margin. Based on the sensitivity of the frequency regulation devices to the frequency stability margin, as well as the controllable active power and controllable active power cost, the contributions of the multiple frequency regulation devices to the frequency regulation effect are determined. A contribution ranking is then obtained, and the frequency regulation points and control quantities corresponding to the frequency default failure are determined based on the contribution ranking. By calculating the contribution of the frequency regulation devices to the frequency regulation effect and determining the priority of participating in frequency regulation based on this contribution, the present invention facilitates precise frequency regulation and avoids over-control or under-control issues.

[0043] Of course, any product implementing the present invention does not necessarily need to achieve all of the advantages described above at the same time. BRIEF DESCRIPTION OF THE DRAWINGS

[0044] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0045] Figure 1 A flow chart of a frequency regulation method based on a virtual power plant provided in an embodiment of the present invention;

[0046] Figure 2 A flow chart of another frequency regulation method based on a virtual power plant provided by an embodiment of the present invention;

[0047] Figure 3 A flow chart of another frequency regulation method based on a virtual power plant provided by an embodiment of the present invention;

[0048] Figure 4 A flow chart of another frequency regulation method based on a virtual power plant provided in an embodiment of the present invention. DETAILED DESCRIPTION

[0049] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0050] The present invention provides a frequency modulation method based on a virtual power plant, such as Figure 1 As shown, the method includes:

[0051] Step 101: For a frequency default fault, obtain the sensitivity of multiple frequency regulation devices in the virtual power plant to the frequency stability margin; wherein the frequency default fault is a fault in which the frequency of each node of the power grid exceeds the limit for a period exceeding a preset period.

[0052] To ensure grid frequency stability, the virtual power plant is equipped with multiple frequency regulation devices. These devices can include one or more of distributed power sources, flexible loads, and energy storage devices, with one or more of each type of frequency regulation device. Under normal circumstances, the grid node frequency should be within a normal frequency range. When a fault occurs, causing the frequency to drop or exceed a threshold, a frequency default occurs if the grid node frequency exceeds the limit for a predetermined duration. In the event of a frequency default fault, the frequency regulation devices within the virtual power plant can be used to restore the frequency to a normal range.

[0053] For frequency default failures, the sensitivity of multiple frequency regulators within the virtual power plant to their impact on frequency stability margin can be determined. Specifically, an active power perturbation can be applied to each of these frequency regulators sequentially, adjusting their active power. For frequency drops, the frequency regulators can be instructed to increase their active power by a certain amount; for frequencies exceeding a threshold, the frequency regulators can be instructed to decrease their active power by a certain amount.

[0054] Optionally, the sensitivity of the frequency modulation device to the frequency stability margin can be obtained by performing active power perturbation simulation on the frequency modulation device. Specifically, active power perturbation simulation can be performed on the frequency modulation device to obtain simulation results reflecting the degree of change of the grid frequency caused by the frequency modulation device after the active power perturbation. Different frequency modulation devices may reflect different degrees of frequency change after active power perturbation simulation, that is, different frequency modulation devices have different sensitivities to the frequency stability margin.

[0055] Step 102: Determine the contribution of multiple frequency modulation devices to the frequency modulation effect based on the sensitivity of the frequency modulation device to the frequency stability margin, the controllable active power, and the controllable active power cost, and obtain a contribution ranking.

[0056] The controllable active power of the frequency modulation device is the active power that the frequency modulation device can increase or decrease. The cost of the controllable active power of the frequency modulation device is the economic cost of increasing or reducing the active output when using the frequency modulation device for frequency control. For example, increasing the source side output requires a cost, and shedding the load also requires a cost.

[0057] Different frequency modulation devices may have different controllable active powers, different frequency modulation devices may have different controllable active power costs, and different frequency modulation devices may have different degrees of frequency change after active power perturbations. These can all cause different frequency modulation devices to produce different frequency modulation effects. The controllable active power of the frequency modulation device, the controllable active power cost, and the sensitivity of the frequency modulation device to the frequency stability margin are used to determine the contribution of the frequency modulation device to the frequency modulation effect. The present invention takes into account the dynamic characteristics of the frequency modulation device when participating in frequency modulation, and can determine the contribution of the frequency modulation device to the frequency modulation effect to obtain a contribution ranking. In practical applications, the contribution ranking can be sorted in descending order of contribution.

[0058] Step 103: Determine the frequency modulation points and control amount corresponding to the frequency default fault according to the contribution ranking; wherein the frequency modulation points are the frequency modulation device points that adjust the active power to restore the frequency to within the dead zone range, and the control amount is the active power adjustment amount of the frequency modulation device.

[0059] The frequency modulation contribution ranking reflects the contribution of the frequency modulation device to the frequency modulation effect. This contribution ranking can be used to determine the priority of the frequency modulation devices participating in the frequency modulation. Active power adjustment operations can be performed sequentially in descending order of contribution until the frequency returns to the dead zone. When transitioning from a frequency default state to a normal frequency state, a frequency modulation device may be required to adjust the active power. A frequency modulation device can be selected based on the contribution ranking. In this case, the frequency modulation location is the location of the selected frequency modulation device, and the control amount is the active power adjustment amount of the selected frequency modulation device. Of course, when transitioning from a frequency default state to a normal frequency state, multiple frequency modulation devices may also be required to adjust the active power. Similarly, multiple frequency modulation devices can be selected based on the contribution ranking. In this case, the frequency modulation location is the location of the selected frequency modulation devices, and the control amount is the active power adjustment amount of the selected frequency modulation devices.

[0060] As an optional implementation, the frequency regulation method based on virtual power plant provided by the present invention, after obtaining the frequency regulation points and control quantities corresponding to the frequency default fault, further includes: using the frequency regulation points and control quantities to adjust the grid node frequency.

[0061] The present invention calculates the contribution of frequency modulation devices to the frequency modulation effect at the same cost and obtains the priority of participating in frequency modulation accordingly, which can facilitate accurate frequency modulation and avoid the occurrence of frequency over-control or under-control problems.

[0062] In an optional embodiment, the frequency regulation method based on virtual power plant provided by the present invention is as follows: Figure 2 As shown, the method includes:

[0063] Step 201: For a frequency default fault, obtain the sensitivity of multiple frequency regulation devices in the virtual power plant to the frequency stability margin; wherein the frequency default fault is a fault in which the frequency of a grid node exceeds the limit for a period exceeding a preset period.

[0064] Step 201 and Figure 1 The step 101 shown is similar and will not be described again here.

[0065] Step 202: Determine the contribution of multiple frequency modulation devices to the frequency modulation effect based on the sensitivity of the frequency modulation device to the frequency stability margin, the controllable active power, and the controllable active power cost, and obtain a contribution ranking.

[0066] Step 202 and Figure 1 The step 102 shown is similar and will not be described again here.

[0067] Step 203: Sorting by contribution, selecting the frequency modulation device with the greatest contribution to apply all controllable active power.

[0068] In the contribution ranking, the frequency modulation device corresponding to the maximum contribution has the best frequency modulation effect, and the frequency modulation device corresponding to the maximum contribution is selected to apply its entire controllable active power.

[0069] Of course, the frequency modulation device corresponding to the maximum contribution can be selected to apply part of the controllable active power, and there is no limitation here.

[0070] Step 204: Determine whether there is a frequency default.

[0071] Optionally, active power perturbation simulation can be performed on the frequency modulation device through time domain simulation to obtain simulation results, and the simulation results can be used to determine whether frequency default still exists.

[0072] Step 205: If the frequency violation still exists, determine the contribution ranking of the frequency modulation devices that have not applied all the controllable active power, and then return to step 203.

[0073] After the frequency modulation device corresponding to the maximum contribution applies all controllable active power, if frequency default still exists, it means that the frequency default fault cannot be restored to the dead zone range by only one frequency modulation device. At this time, other frequency modulation devices can be used to adjust the active power to restore the frequency to normal.

[0074] When selecting other frequency modulation devices, the contribution ranking obtained in step 202 can be used, or the contribution ranking can be re-performed. Because the contributions of the other frequency modulation devices to the frequency modulation effect may change after the frequency modulation device corresponding to the maximum contribution applies all controllable active power, the present invention re-performs active power perturbations on the other frequency modulation devices to obtain a contribution ranking for these frequency modulation devices.

[0075] It should be noted that the "other FM devices" refer to FM devices other than the FM device corresponding to the maximum contribution selected in step 203, and the newly obtained contribution ranking is the contribution ranking of the other FM devices. Of course, after re-ranking the contribution, an overall contribution ranking can be obtained, i.e., the ranking of the other FM devices plus the FM device corresponding to the maximum contribution selected in step 203. For the overall contribution ranking, if ranked in descending order of contribution, the FM device ranked first is the FM device corresponding to the maximum contribution selected in step 203, and the FM device ranked second is the FM device corresponding to the maximum contribution in the contribution ranking newly obtained in step 205.

[0076] After the contribution ranking is regained, the frequency modulation device corresponding to the maximum contribution is selected according to the regained contribution ranking to apply all controllable active power, and then it is determined whether a frequency default still exists. If a frequency default still exists, step 205 is executed; if no frequency default exists, step 206 is executed.

[0077] Step 206: If there is no frequency default, obtain the final contribution ranking.

[0078] The final contribution ranking is the contribution ranking of all frequency modulation devices in the virtual power plant, and the final contribution ranking is the contribution ranking after repeating steps 203-205 until there is no frequency default. Each time steps 203-205 are executed, what changes is the contribution ranking of the frequency modulation devices that have not applied all controllable active power, and the order of the frequency modulation devices corresponding to the maximum contribution remains unchanged, that is, the order of the frequency modulation devices that apply all controllable active power remains unchanged, and each time steps 203-205 are repeated, a frequency modulation device corresponding to the maximum contribution will be obtained. These frequency modulation devices are sorted in order, and the frequency modulation device with the maximum contribution in the final contribution ranking is the frequency modulation device corresponding to the maximum contribution selected in step 203.

[0079] Step 207: Determine the frequency modulation points and control amount corresponding to the frequency default fault according to the contribution ranking; wherein the frequency modulation points are the frequency modulation device points that adjust the active power to restore the frequency to within the dead zone range, and the control amount is the active power adjustment amount of the frequency modulation device.

[0080] In practical applications, the method for determining the frequency regulation distribution point and control quantity corresponding to the frequency default fault according to the contribution ranking can be: in descending order of contribution, select the target frequency regulation device that needs to apply all controllable active power to restore the frequency to within the dead zone range from the contribution ranking; use the grid node to which the target frequency regulation device belongs as the frequency regulation distribution point; and use the total controllable active power of the target frequency regulation device as the control quantity.

[0081] As an optional implementation, the frequency regulation method based on virtual power plant provided by the present invention, after obtaining the frequency regulation points and control quantities corresponding to the frequency default fault, further includes: using the frequency regulation points and control quantities to adjust the grid node frequency.

[0082] The present invention dynamically updates the contribution of the frequency modulation device and selects the frequency modulation device with the highest contribution. Because the controllable active power of the frequency modulation device, the controllable active power cost, and the influence of the perturbation active power on the frequency modulation effect are taken into consideration when determining the contribution, the frequency modulation effect with a high contribution is cost-effective and can ensure control effectiveness.

[0083] In an optional embodiment, the frequency regulation method based on virtual power plant provided by the present invention is as follows: Figure 3 As shown, the method includes:

[0084] Step 301: Compare the frequency stability margins of the frequency default faults in the frequency default fault set; wherein the frequency stability margin represents the degree of frequency limit violation.

[0085] Depending on the fault location, fault type, and fault time, multiple frequency default faults may exist. These frequency default faults can be grouped together in a frequency default fault set, which can be derived based on fault probability and manual experience. For multiple frequency default faults in a frequency default fault set, their frequency stability margins can be determined to reflect the degree of overshooting of different frequency default faults.

[0086] Step 302: Select the frequency default fault corresponding to the lowest frequency stability margin.

[0087] The frequency stability margin reflects the severity of the frequency overshoot: a lower frequency stability margin indicates a greater overshoot, while a higher frequency stability margin indicates a smaller overshoot. The present invention selects the frequency default fault with the lowest frequency stability margin, i.e., the frequency default fault with the greatest frequency overshoot, and performs active power perturbations on multiple frequency regulation devices within the virtual power plant to find the contribution ranking, frequency regulation point distribution, and control quantity corresponding to the frequency default fault with the highest severity. This can ensure control effectiveness for frequency default faults of other frequency severities and avoid the problem of being unable to restore the frequency to within the dead zone.

[0088] Step 303: For frequency default faults, obtain the sensitivity of multiple frequency regulation devices in the virtual power plant to the frequency stability margin; wherein the frequency default fault is a fault in which the frequency of the grid node exceeds the limit for a period exceeding a preset period.

[0089] Step 304: Determine the contribution of multiple frequency modulation devices to the frequency modulation effect based on the sensitivity of the frequency modulation device to the frequency stability margin, the controllable active power, and the controllable active power cost, and obtain a contribution ranking.

[0090] Step 305: sorting by contribution, selecting the frequency modulation device with the largest contribution to apply all controllable active power.

[0091] Step 306: Determine whether there is a frequency default.

[0092] Step 307 : If the frequency violation still exists, determine the contribution ranking of the frequency modulation devices that have not applied all the controllable active power, and then return to step 305 .

[0093] Step 308: If there is no frequency default, obtain the final contribution ranking.

[0094] Step 309: Determine the frequency modulation points and control amount corresponding to the frequency default fault according to the contribution ranking; wherein the frequency modulation points are the frequency modulation device points that adjust the active power to restore the frequency to within the dead zone range, and the control amount is the active power adjustment amount of the frequency modulation device.

[0095] Steps 303-309 and Figure 2 Steps 201 to 207 are similar and will not be described again here.

[0096] As an optional implementation, the frequency regulation method based on virtual power plant provided by the present invention, after obtaining the frequency regulation points and control quantities corresponding to the frequency default fault, further includes: using the frequency regulation points and control quantities to adjust the grid node frequency.

[0097] In another optional embodiment, the frequency regulation method based on virtual power plant provided by the present invention is Figure 1 Before step 101 shown, the following steps may also be included: Figure 3 Steps 301 and 302 are shown and will not be described again in detail.

[0098] As an optional implementation, after obtaining the final contribution ranking in step 307, the frequency regulation method based on a virtual power plant provided by the present invention further includes:

[0099] For other frequency default faults in the frequency default fault set except the frequency default fault corresponding to the lowest frequency stability margin, all controllable active powers of the corresponding frequency regulation devices are applied in sequence according to the contribution degree until there is no frequency default, and the frequency regulation points and control quantities corresponding to other frequency default faults are obtained.

[0100] Other frequency default faults in the frequency default fault set are frequency default faults other than the frequency default fault corresponding to the lowest frequency stability margin. After the contribution ranking is obtained in step 307, it is not necessary to perform an iterative operation of active power perturbation for the other frequency default faults. Instead, frequency modulation devices need only be selected in descending order of contribution, and all controllable active power is applied to the selected frequency modulation devices. In the event of a frequency default, another frequency modulation device is selected again according to the contribution ranking, and all controllable active power is applied to the selected frequency modulation device until there is no frequency default. The grid node to which the selected frequency modulation device that applies all controllable active power belongs is used as the frequency modulation point, and the all controllable active power of each selected frequency modulation device is used as the control quantity of each frequency modulation device, so that after the corresponding frequency fault occurs, the frequency modulation point and the control quantity are used to perform a frequency adjustment operation so that the frequency is restored to within the dead zone range.

[0101] As an optional implementation, before comparing the frequency stability margin of each frequency default fault in the frequency default fault set in step 301, the frequency regulation method based on a virtual power plant provided by the present invention further includes:

[0102] Time domain simulation is performed on each frequency default fault in the frequency default fault set. According to the simulation results, each frequency default fault is divided into two types: frequency greater than the upper limit and frequency less than the lower limit; frequency default faults with a frequency greater than the upper limit can be grouped in one frequency default fault set, and frequency default faults with a frequency less than the lower limit can be grouped in another frequency default fault set.

[0103] The “comparison of frequency stability margins of each frequency default fault in a frequency default fault set” is performed for two types of frequency default fault sets respectively.

[0104] Frequency default can be divided into two situations: low frequency and high frequency. The frequency-time curve obtained by time domain simulation of frequency default fault can distinguish the above two situations, namely faults with a frequency greater than the upper limit and faults with a frequency less than the lower limit. Faults of the same type are grouped together to obtain a frequency default fault set, which is divided into two types. One frequency default fault set includes frequency default faults with a frequency greater than the upper limit, and the other frequency default fault set includes frequency default faults with a frequency less than the lower limit. The "comparison of frequency stability margins of each frequency default fault in the frequency default fault set" is performed on the two types of frequency default fault sets respectively, and finally the frequency modulation points and control quantities corresponding to each frequency default fault are obtained.

[0105] The present invention obtains frequency default faults corresponding to the lowest frequency stability margin for the two situations of high frequency and low frequency respectively, and performs simulation on the frequency default faults corresponding to the lowest frequency stability margin in the two situations to obtain the frequency modulation contribution ranking. For the remaining frequency default faults, no iterative operation of active power perturbation is required, which can save the calculation amount of iterative perturbation to obtain the frequency modulation contribution ranking.

[0106] Optionally, before performing time domain simulation on each frequency default fault in the frequency default fault set, the frequency regulation method based on a virtual power plant provided by the present invention further includes:

[0107] The grid topology and frequency default fault set are updated periodically.

[0108] The grid topology may change in different grid operation cycles, and the corresponding frequency default fault set will also change. Updating the grid topology and frequency default fault set on a periodic basis can ensure the timeliness of frequency regulation and facilitate accurate frequency regulation.

[0109] In practical applications, 5 minutes can be used as the grid operation cycle, and the frequency default fault set can be periodically updated to obtain the frequency regulation points and frequency regulation amounts corresponding to each frequency default fault under each grid operation cycle.

[0110] In an optional embodiment, the frequency regulation method based on virtual power plant provided by the present invention is as follows: Figure 4 As shown, the following steps are included:

[0111] Step 401: Update the power grid topology and frequency default fault set periodically.

[0112] Step 402: Perform time domain simulation on each frequency default fault in the frequency default fault set, and classify each frequency default fault into two types according to the simulation results: the frequency is greater than the upper limit value and the frequency is less than the lower limit value.

[0113] Step 403: Comparing the frequency stability margins of the two types of frequency default fault sets respectively. The frequency stability margins represent the degree of frequency limit violations.

[0114] Step 404: Select the frequency default fault corresponding to the lowest frequency stability margin.

[0115] Step 405: For frequency default faults, obtain the sensitivity of multiple frequency regulation devices in the virtual power plant to the frequency stability margin; wherein the frequency default fault is a fault in which the frequency of the grid node exceeds the limit for a period exceeding a preset period.

[0116] Step 406: Determine the contribution of multiple frequency modulation devices to the frequency modulation effect based on the sensitivity of the frequency modulation device to the frequency stability margin, the controllable active power, and the controllable active power cost, and obtain a contribution ranking.

[0117] As an optional implementation, the contribution of multiple frequency modulation devices to the frequency modulation effect is determined based on the sensitivity of the frequency modulation device to the frequency stability margin, the controllable active power, and the controllable active power cost, including:

[0118] Calculating a change in the frequency stability margin of the frequency default fault before and after the frequency modulation device performs active power perturbation to obtain a first change; wherein the first change reflects the sensitivity of the frequency modulation device to the frequency stability margin;

[0119] Contributions of the multiple frequency modulation devices to the frequency modulation effect are determined according to the first variation, the controllable active power of the frequency modulation device, the controllable active power cost, and the variation of the active power.

[0120] Optionally, the method for calculating the first variation includes:

[0121] Determine whether the signs of the frequency stability margin of the frequency default fault are consistent before and after the active power perturbation of the frequency modulation device;

[0122] If the signs are consistent, a first variation is calculated based on the two frequency stability margins before and after the active power perturbation;

[0123] If the signs are inconsistent, the first variation is calculated based on the frequency stability margin before the perturbation.

[0124] In practical applications, the formula Calculate the contribution, where D k,i is the contribution of frequency regulation device k to frequency default fault i, Δη i is the first variation, P k is the controllable active power of frequency modulation device k, ΔP kis the active power perturbation of frequency modulation device k, that is, the active power increased or decreased by frequency modulation device k during perturbation simulation, C k k is the controllable active power cost of the frequency modulation device.

[0125] You can use Calculate the first change Δη i , where η i.0 is the frequency stability margin before perturbation, η i.p is the frequency stability margin after perturbation. When the frequency stability margin of the frequency default fault has the same sign before and after the frequency modulation device performs active power perturbation, the first change is η i.p -η i.0 When the signs of the frequency stability margin of the frequency default fault are inconsistent before and after the frequency modulation device performs active power perturbation, the first change is -η i.0 .

[0126] Step 407: sorting by contribution, selecting the frequency modulation device with the largest contribution to apply all controllable active power.

[0127] Step 408: Determine whether there is a frequency default. If there is still a frequency default, execute step 409; if there is no frequency default, execute step 410.

[0128] Step 409 : Determine the contribution ranking of the frequency modulation devices that have not applied all the controllable active power, and then return to step 407 .

[0129] As an optional implementation, determining the contribution ranking of the frequency modulation devices that have not applied all controllable active power includes:

[0130] re-perturbing the active power of the frequency modulation device that has not applied all the controllable active power, calculating the change in the frequency stability margin before and after the perturbation, and obtaining a second change; wherein the second change reflects the sensitivity of the frequency modulation device to the frequency stability margin;

[0131] The contribution of each frequency modulation device to the frequency modulation effect is determined based on the second change, the controllable active power of the frequency modulation device that is re-simulated with active power perturbation, the controllable active power cost, and the change in active power, and the contribution ranking of the frequency modulation devices that have not applied all the controllable active power is obtained.

[0132] The contribution calculation formula based on the second change amount can also refer to the contribution calculation formula in step 406. The specific calculation formula of the second change amount can refer to the calculation formula of the first change amount in step 406. The values of the second change amount and the first change amount may be different, so they will not be repeated here.

[0133] Step 410: Obtain the final contribution ranking.

[0134] Step 411: Determine the frequency modulation points and control amount corresponding to the frequency default fault according to the contribution ranking; wherein the frequency modulation points are the frequency modulation device points that adjust the active power to restore the frequency to within the dead zone range, and the control amount is the active power adjustment amount of the frequency modulation device.

[0135] Step 412: For other frequency default faults in the frequency default fault set except the frequency default fault corresponding to the lowest frequency stability margin, apply all controllable active powers of the corresponding frequency regulation devices in sequence according to the contribution order until there is no frequency default, and obtain the frequency regulation points and control quantities corresponding to the other frequency default faults.

[0136] As an optional implementation, the frequency regulation method based on virtual power plant provided by the present invention, after obtaining the frequency regulation points and control quantities corresponding to the frequency default fault, further includes: using the frequency regulation points and control quantities to adjust the grid node frequency.

[0137] The present invention also provides a frequency regulation system based on a virtual power plant, comprising: a control device and at least one frequency regulation device. The frequency regulation device is controlled by the control device; the control device is used to execute the above-mentioned frequency regulation method based on a virtual power plant.

[0138] Optionally, each frequency regulation device includes one or more of a distributed power source, a flexible load and an energy storage device.

[0139] It should be noted that, in this document, relational terms such as first and second, etc., are used only to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any actual relationship or order between these entities or operations. It should also be noted that the terms "comprises," "comprising," or any other variations thereof are intended to cover non-exclusive inclusion, so that a process, method, commodity, or device comprising a series of elements includes not only those elements, but also other elements not explicitly listed, or elements inherent to such process, method, commodity, or device. In the absence of further limitations, an element defined by the phrase "comprising a ..." does not exclude the presence of other identical elements in the process, method, commodity, or device comprising the element.

[0140] Each embodiment in this specification is described in a progressive manner. The same or similar parts between the embodiments can be referred to each other. Each embodiment focuses on the differences from other embodiments. In particular, for system or system embodiments, since they are basically similar to method embodiments, the description is relatively simple. For relevant parts, refer to the partial description of the method embodiment. The system and system embodiments described above are merely schematic, wherein the units described as separate components may or may not be physically separated, and the components displayed as units may or may not be physical units, that is, they may be located in one place, or they may be distributed on multiple network units. Some or all of the modules can be selected according to actual needs to achieve the purpose of the solution of this embodiment. A person of ordinary skill in the art can understand and implement it without expending creative work.

[0141] Professionals may further appreciate that the units and algorithm steps of each example described in conjunction with the embodiments disclosed herein can be implemented in electronic hardware, computer software, or a combination of the two. In order to clearly illustrate the interchangeability of hardware and software, the above description has generally described the components and steps of each example according to their functions. Whether these functions are performed in hardware or software depends on the specific application and design constraints of the technical solution. Professionals and technicians may use different methods to implement the described functions for each specific application, but such implementation should not be considered beyond the scope of the present invention.

[0142] The above description of the disclosed embodiments is intended to enable one skilled in the art to implement or use the present invention. Various modifications to these embodiments will be readily apparent to one skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the present invention. Therefore, the present invention is not limited to the embodiments shown herein but is intended to conform to the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A frequency modulation method based on a virtual power plant, characterized in that: include: For frequency default faults, the sensitivity of multiple frequency regulation devices in the virtual power plant to the frequency stability margin is obtained; wherein the frequency default fault is a fault in which the frequency of the power grid node exceeds the limit for a preset period of time; Determining the contribution of the plurality of frequency modulation devices to the frequency modulation effect according to the sensitivity of the frequency modulation device to the frequency stability margin, the controllable active power, and the controllable active power cost, and obtaining a contribution ranking; The frequency regulation points and control amount corresponding to the frequency default fault are determined according to the contribution ranking; wherein the frequency regulation points are the points of the frequency regulation devices that adjust the active power to restore the frequency to within the dead zone range, and the control amount is the active power adjustment amount of the frequency regulation device.

2. The frequency modulation method based on virtual power plant according to claim 1, characterized in that: After obtaining the contribution ranking, the method further includes: According to the contribution ranking, the frequency modulation device with the largest contribution is selected to apply all controllable active power; If the frequency violation still exists, determine the contribution ranking of the frequency modulation devices that have not applied the full controllable active power, and then return to step "selecting the frequency modulation device with the largest contribution to apply the full controllable active power according to the contribution ranking"; If there is no frequency default, the final contribution ranking is obtained.

3. The frequency modulation method based on virtual power plant according to claim 1 or 2, characterized in that: Before obtaining the sensitivity of multiple frequency regulation devices in the virtual power plant to the frequency stability margin for a frequency default fault, the method further includes: Comparing the frequency stability margins of the frequency default faults in the frequency default fault set; wherein the frequency stability margins represent the degree of frequency limit violations; A frequency default fault corresponding to the lowest frequency stability margin is selected, and the method of "obtaining the sensitivity of multiple frequency regulation devices in the virtual power plant to the frequency stability margin for the frequency default fault" is executed.

4. The frequency modulation method based on virtual power plant according to claim 3, characterized in that: Also includes: For other frequency default faults in the frequency default fault set except the frequency default fault corresponding to the lowest frequency stability margin, all controllable active powers of the corresponding frequency regulation devices are applied in sequence according to the contribution ranking until there is no frequency default, and the frequency regulation points and control quantities corresponding to the other frequency default faults are obtained.

5. The frequency modulation method based on virtual power plant according to claim 3, characterized in that: Before comparing the frequency stability margin of each frequency default fault in the frequency default fault set, the method further includes: Performing time domain simulation on each frequency default fault in the frequency default fault set, and classifying each frequency default fault into two types according to the simulation results: a frequency greater than an upper limit value and a frequency less than a lower limit value; The “comparing the frequency stability margin of each frequency default fault in a frequency default fault set” is performed on two types of frequency default fault sets respectively.

6. The frequency modulation method based on virtual power plant according to claim 5, characterized in that: Before performing time domain simulation on each frequency default fault in the frequency default fault set, the method further includes: The grid topology and frequency default fault set are updated periodically.

7. The frequency modulation method based on a virtual power plant according to any one of claims 1, 2, 4-6, characterized in that: Determining the contribution of the plurality of frequency modulation devices to the frequency modulation effect according to the sensitivity of the frequency modulation device to the frequency stability margin, the controllable active power, and the controllable active power cost includes: Calculating a change in the frequency stability margin of the frequency default fault before and after the frequency modulation device performs active power perturbation to obtain a first change; wherein the first change reflects the sensitivity of the frequency modulation device to the frequency stability margin; Contributions of the plurality of frequency modulation devices to the frequency modulation effect are determined according to the first variation, the controllable active power of the frequency modulation device, the controllable active power cost, and the variation of the active power.

8. The frequency modulation method based on virtual power plant according to claim 7, characterized in that: The method for calculating the first variation includes: determining whether the signs of the frequency stability margin of the frequency default fault are consistent before and after the frequency modulation device performs active power perturbation; If the signs are consistent, calculating the first variation according to the two frequency stability margins before and after the active power perturbation; If the signs are inconsistent, the first variation is calculated according to the frequency stability margin before the perturbation.

9. The frequency modulation method based on virtual power plant according to claim 2, characterized in that: The determining of the contribution ranking of the frequency modulation devices that have not applied all the controllable active power includes: re-perturbing the active power of the frequency modulation device that has not applied all the controllable active power, calculating the change in the frequency stability margin before and after the perturbation, and obtaining a second change; wherein the second change reflects the sensitivity of the frequency modulation device to the frequency stability margin; The contribution of each frequency modulation device to the frequency modulation effect is determined based on the second change, the controllable active power of the frequency modulation device that has re-perturbed active power, the controllable active power cost and the change in active power, and the contribution ranking of the frequency modulation devices that have not applied all the controllable active power is obtained.

10. The frequency modulation method based on a virtual power plant according to any one of claims 1-2, 4-6, 8-9, characterized in that: The determining of the frequency regulation points and control amounts corresponding to the frequency default fault according to the contribution ranking includes: Selecting, in descending order of contribution, a target frequency modulation device that needs to apply all controllable active power when the frequency is restored to within the dead zone range from the contribution ranking; The grid node to which the target frequency regulation device belongs is used as the frequency regulation distribution point; The total controllable active power of the target frequency modulation device is used as the control variable.

11. A frequency modulation system based on a virtual power plant, characterized in that: include: control means and at least one frequency modulation means; The frequency modulation device is controlled by the control device; The control device is used to execute the frequency regulation method based on a virtual power plant as described in any one of claims 1-10.

12. The frequency regulation system based on virtual power plant according to claim 11, characterized in that: Each of the frequency modulation devices includes one or more of a distributed power source, a flexible load and an energy storage device.

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