Power grid inertia online evaluation method, system, computer device and storage medium

Abstract

This invention belongs to the field of power system automation and discloses a method, system, computer equipment, and storage medium for online assessment of power grid inertia. The method includes: obtaining the average inertia per unit load of the power grid based on the system inertia, synchronous machine type inertia, new energy inertia, and load level during several historical disturbance events within a set time range; obtaining the current load level of the power grid and obtaining the current load inertia based on the average inertia per unit load; obtaining the current synchronous machine type inertia and new energy inertia of the power grid, and superimposing the current load inertia, synchronous machine type inertia, and new energy inertia to obtain the current system inertia of the power grid. By assessing the average inertia per unit load within a set time range using multiple disturbance events, the method can assess load inertia based on the actual load level during steady-state operation, thereby achieving online assessment of the system inertia of the power grid during steady-state operation and improving the accuracy of inertia monitoring.

Description

Technical Field

[0001] This invention belongs to the field of power system automation and relates to an online assessment method, system, computer equipment, and storage medium for power grid inertia. Background Technology

[0002] The development and construction of new power systems have promoted the large-scale application of high-proportion renewable energy and high-proportion power electronic equipment in the power grid. A large number of synchronous generator units have been replaced by renewable energy, leading to a gradual decrease in the grid's inertia. Inertia is a crucial guarantee for the grid's frequency resistance to disturbances, helping to reduce frequency changes and avoid large-scale grid fluctuations after disturbances occur. However, with the replacement of many synchronous generator units by renewable energy, the rotational inertia of the synchronous AC grid continues to decrease, reducing the power system's dynamic regulation capability. This weakens the system's ability to withstand disturbances and reduces its capacity to withstand frequency fluctuations and active power surges, increasing the grid's operational risks and affecting its safe and stable operation.

[0003] To address the issue of gradually decreasing inertia, the industry has conducted research on inertia assessment technology. Currently, inertia assessment primarily employs two methods: offline statistical methods and online disturbance monitoring. Offline statistical methods mainly involve calculating the inertia of operating synchronous generator units and summing the rotational inertia of each unit to obtain the total system inertia. However, with the large-scale grid connection of new energy sources, especially the application of power electronic equipment such as inverters, wind power, photovoltaics, and energy storage can achieve virtual inertia support through parameter settings. Simultaneously, numerous synchronous motors and other loads on the load side can also provide inertia support after frequency changes. Therefore, the current method of only statistically analyzing synchronous generator units cannot accurately reflect the true level of inertia.

[0004] To address this, the industry has proposed online inertia monitoring and assessment methods based on disturbance events. Currently, while disturbance events can accurately assess the inertia level of the power grid system, these disturbances must be large-scale to cause frequency fluctuations across the entire network, thus supporting online inertia assessment. However, disturbance events, especially large-scale ones, are infrequent during daily operation, limiting the online assessment and application of inertia. Furthermore, methods based on small disturbances such as switchovers have been proposed. However, these small disturbances cause relatively small changes in power and frequency, and the changes in PMU (Phasor Measurement Unit) measurement data are not significant, leading to substantial errors in online monitoring and assessment results. Additionally, because small disturbances affect a very small area, they cannot truly reflect the frequency changes and fluctuations caused by power imbalances across the entire network; therefore, power grid inertia assessment based on small disturbances is difficult to apply in engineering. Therefore, during the daily operation of the power grid, it operates in a steady state for the vast majority of the time, with neither minor nor major disturbances. How to achieve online assessment of inertia levels to support the dispatch and operation of the power grid has become an urgent problem to be solved. Summary of the Invention

[0005] The purpose of this invention is to overcome the shortcomings of the prior art and provide a method, system, computer equipment, and storage medium for online evaluation of power grid inertia.

[0006] To achieve the above objectives, the present invention employs the following technical solution:

[0007] In a first aspect, the present invention provides an online assessment method for power grid inertia, comprising: obtaining the average inertia per unit load of the power grid based on the system inertia, synchronous machine type inertia, new energy inertia, and load level of the power grid during several historical disturbance events within a set time range; obtaining the current load level of the power grid and obtaining the current load inertia of the power grid based on the average inertia per unit load of the power grid; obtaining the current synchronous machine type inertia and new energy inertia of the power grid, and superimposing the current load inertia, synchronous machine type inertia, and new energy inertia of the power grid to obtain the current system inertia of the power grid.

[0008] Optionally, it also includes: obtaining the system inertia of the power grid during several historical disturbance events within a set time range using the following formula:

[0009]

[0010] Among them, H sd Let f be the system inertia of the power grid during historical disturbance events, ΔP be the active power lost by the power grid during historical disturbance events, and f be the system inertia of the power grid during historical disturbance events. Ndf / ft is the rated frequency of the power grid during historical disturbance events, and df / ft is the rate of change of the system center point frequency of the power grid during historical disturbance events.

[0011] Optionally, it also includes: obtaining the synchronous machine type inertia of the power grid during several historical disturbance events within a set time range using the following formula:

[0012]

[0013] H ssdall =H ssd +H scd +H spd

[0014] Among them, H ssd H represents the inertia of the synchronous generators in the power grid during historical disturbance events. si S is the inertial constant of the i-th synchronous generator; si The rated capacity of the i-th synchronous generator is given by Nssd; the number of synchronous generators in operation during historical disturbance events in the power grid is given by H. scd H represents the inertia of the synchronous condenser during historical disturbance events in the power grid. ci S is the inertial constant of the i-th synchronous camera; ci Let i be the rated capacity of the i-th synchronous camera; Nscd H represents the number of synchronous condensers in operation during historical disturbance events in the power grid. spd H represents the inertia of the pumped-storage power station during historical disturbance events in the power grid. pi S is the inertial constant of the i-th pumped storage power station; pi Let be the rated capacity of the i-th pumped storage power station; Nspd H represents the number of pumped-storage hydroelectric power stations in operation during historical disturbance events; ssdall This represents the inertia of the synchronous machine type in the power grid during historical disturbance events.

[0015] The inertia of new energy sources during several historical disturbance events within a set time range can be obtained using the following formula:

[0016]

[0017] Among them, H rsd H represents the inertia of renewable energy power plants during historical disturbance events; ri S is the inertial constant of the i-th renewable energy power plant; ri denoted as the actual output of the i-th renewable energy power plant; Nrsd represents the number of renewable energy power plants that meet the preset requirements during historical disturbance events; where the preset requirements are renewable energy power plants whose actual output to rated capacity ratio exceeds a preset threshold.

[0018] Optionally, obtaining the average inertia per unit load of the power grid based on the system inertia, synchronous machine type inertia, new energy inertia, and load level of the power grid during several historical disturbance events within a set time range includes: obtaining the load inertia of the power grid during several historical disturbance events within a set time range using the following formula:

[0019]

[0020] Among them, H ld This represents the load inertia of the power grid during historical disturbance events.

[0021] The inertia per unit load of the power grid during several historical disturbance events within a set time range is obtained using the following formula:

[0022]

[0023] in, P represents the inertia of the power grid per unit load during historical disturbance events. LD This represents the load level of the power grid during historical disturbance events.

[0024] The average inertia per unit load of the power grid is obtained using the following formula.

[0025]

[0026] Where N represents the number of historical disturbance events. Let be the unit load inertia of the power grid at the i-th historical disturbance event.

[0027] Optionally, it also includes: acquiring the current system inertia of the power grid at each preset time interval, obtaining several evaluation power grid system inertia, and constructing a curve of the evaluation power grid system inertia changing over time based on the several evaluation power grid system inertia.

[0028] Optionally, it also includes: when the current time exceeds the currently set time range and no new disturbance event occurs, continuing to use the average inertia value of the power grid corresponding to the unit load within the currently set time range; when the current time exceeds the currently set time range and a new disturbance event occurs, updating the average inertia value of the power grid corresponding to the unit load based on the system inertia, synchronous machine type inertia, new energy inertia, and load level at several historical disturbance events in the next set time range.

[0029] In a second aspect, the present invention provides an online power grid inertia assessment system, comprising: a unit load corresponding inertia assessment module, used to obtain the average unit load corresponding inertia of the power grid based on the system inertia, synchronous machine type inertia, new energy inertia, and load level of the power grid during several historical disturbance events within a set time range; a load inertia assessment module, used to obtain the current load level of the power grid and obtain the current load inertia of the power grid based on the average unit load corresponding inertia of the power grid; and a system inertia assessment module, used to obtain the current synchronous machine type inertia and new energy inertia of the power grid, and superimpose the current load inertia, synchronous machine type inertia, and new energy inertia of the power grid to obtain the current system inertia of the power grid.

[0030] Optionally, it also includes a historical system inertia acquisition module, which is used to acquire the system inertia of the power grid during several historical disturbance events within a set time range using the following formula:

[0031]

[0032] Among them, H sd Let f be the system inertia of the power grid during historical disturbance events, ΔP be the active power of the power grid during historical disturbance events, and f be the system inertia of the power grid during historical disturbance events. N df / ft is the rated frequency of the power grid during historical disturbance events, and df / ft is the rate of change of the system center point frequency of the power grid during historical disturbance events.

[0033] Optionally, it also includes a historical synchronous machine type inertia acquisition module and a historical new energy inertia acquisition module; the historical synchronous machine type inertia acquisition module is used to obtain the synchronous machine type inertia of the power grid during several historical disturbance events within a set time range using the following formula:

[0034]

[0035]

[0036]

[0037] Among them, H ssd H represents the inertia of the synchronous generators in the power grid during historical disturbance events. si S is the inertial constant of the i-th synchronous generator; si The rated capacity of the i-th synchronous generator is given by Nssd; the number of synchronous generators in operation during historical disturbance events in the power grid is given by H. scd H represents the inertia of the synchronous condenser during historical disturbance events in the power grid. ci S is the inertial constant of the i-th synchronous camera; ci Let i be the rated capacity of the i-th synchronous camera; Nscd H represents the number of synchronous condensers in operation during historical disturbance events in the power grid.spd H represents the inertia of the pumped-storage power station during historical disturbance events in the power grid. pi S is the inertial constant of the i-th pumped storage power station; pi Let be the rated capacity of the i-th pumped storage power station; Nspd The number of pumped storage power stations in operation during historical disturbance events in the power grid; This represents the inertia of the synchronous machine type in the power grid during historical disturbance events.

[0038] The historical renewable energy inertia acquisition module is used to obtain the renewable energy inertia of the power grid during several historical disturbance events within a set time range using the following formula:

[0039]

[0040] Among them, H rsd H represents the inertia of renewable energy power plants during historical disturbance events; ri S is the inertial constant of the i-th renewable energy power plant; ri denoted as the actual output of the i-th renewable energy power plant; Nrsd represents the number of renewable energy power plants that meet the preset requirements during historical disturbance events; where the preset requirements are renewable energy power plants whose actual output to rated capacity ratio exceeds a preset threshold.

[0041] Optionally, obtaining the average inertia per unit load of the power grid based on the system inertia, synchronous machine type inertia, new energy inertia, and load level of the power grid during several historical disturbance events within a set time range includes: obtaining the load inertia of the power grid during several historical disturbance events within a set time range using the following formula:

[0042]

[0043] Among them, H ld This represents the load inertia of the power grid during historical disturbance events.

[0044] The inertia per unit load of the power grid during several historical disturbance events within a set time range is obtained using the following formula:

[0045]

[0046] in, P represents the inertia of the power grid per unit load during historical disturbance events. LD This represents the load level of the power grid during historical disturbance events.

[0047] The average inertia per unit load of the power grid is obtained using the following formula.

[0048]

[0049] Where N represents the number of historical disturbance events. Let be the unit load inertia of the power grid at the i-th historical disturbance event.

[0050] Optionally, it also includes a curve construction module, which is used to obtain the current system inertia of the power grid at preset time intervals, obtain several evaluation power grid system inertia, and construct a curve of the evaluation power grid system inertia changing with time based on the several evaluation power grid system inertia.

[0051] Optionally, an update module is also included. The update module is used to continue using the average inertia value per unit load of the power grid in the next set time range when the current time exceeds the current set time range and no new disturbance event occurs; when the current time exceeds the current set time range and a new disturbance event occurs, the average inertia value per unit load of the power grid in the next set time range is obtained based on the system inertia, synchronous machine type inertia, new energy inertia and load level at several historical disturbance events in the next set time range.

[0052] In a third aspect, the present invention provides a computer device including a memory, a processor, and a computer program stored in the memory and executable on the processor, wherein the processor executes the computer program to implement the steps of the above-described online power grid inertia assessment method.

[0053] In a fourth aspect, the present invention provides a computer-readable storage medium storing a computer program that, when executed by a processor, implements the steps of the above-described online power grid inertia assessment method.

[0054] Compared with the prior art, the present invention has the following beneficial effects:

[0055] This invention provides an online power grid inertia assessment method. First, based on the system inertia, synchronous machine type inertia, new energy inertia, and load level of the power grid during several historical disturbance events within a set time range, the average inertia per unit load of the power grid is obtained. Then, the current load level of the power grid is acquired, and based on the average inertia per unit load, the current load inertia of the power grid is obtained. Finally, the current load inertia, synchronous machine type inertia, and new energy inertia are superimposed to obtain the current system inertia of the power grid. This invention is based on online inertia assessment under disturbance events, using the average inertia per unit load within a set time range assessed by multiple disturbance events. It can assess load inertia based on the actual load level during steady-state operation. Combined with online statistics of synchronous machine type inertia and new energy inertia, it achieves online assessment of the system inertia of the power grid during steady-state operation, improving the accuracy of inertia monitoring, providing a new technical means for power grid operation monitoring, and ensuring the safe and stable operation of the power grid. Attached Figure Description

[0056] Figure 1 This is a flowchart of the online power grid inertia assessment method according to an embodiment of the present invention.

[0057] Figure 2 This is a schematic diagram illustrating the principle of new energy inertia calculation in an embodiment of the present invention.

[0058] Figure 3 This is a schematic diagram of the system inertia composition according to an embodiment of the present invention.

[0059] Figure 4 This is a schematic diagram illustrating the principle of updating the average inertia value corresponding to a unit load in an embodiment of the present invention.

[0060] Figure 5 This is a block diagram of the online power grid inertia assessment system according to an embodiment of the present invention. Detailed Implementation

[0061] To enable those skilled in the art to better understand the present invention, the technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings of the embodiments of the present invention. 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 should fall within the scope of protection of the present invention.

[0062] It should be noted that the terms "first," "second," etc., in the specification, claims, and accompanying drawings of this invention are used to distinguish similar objects and are not necessarily used to describe a specific order or sequence. It should be understood that such data can be interchanged where appropriate so that the embodiments of the invention described herein can be implemented in orders other than those illustrated or described herein. Furthermore, the terms "comprising" and "having," and any variations thereof, are intended to cover a non-exclusive inclusion; for example, a process, method, system, product, or apparatus that comprises a series of steps or units is not necessarily limited to those steps or units explicitly listed, but may include other steps or units not explicitly listed or inherent to such processes, methods, products, or apparatus.

[0063] The present invention will now be described in further detail with reference to the accompanying drawings:

[0064] See Figure 1 In one embodiment of the present invention, an online evaluation method for power grid inertia is provided, which can accurately evaluate the system inertia of the power grid under steady-state operation.

[0065] Specifically, the online power grid inertia assessment method of the present invention includes the following steps:

[0066] S1: Based on the system inertia, synchronous machine type inertia, new energy inertia, and load level of the power grid during several historical disturbance events within a set time range, the average inertia value corresponding to the unit load of the power grid is obtained.

[0067] S2: Obtain the current load level of the power grid, and based on the average inertia per unit load of the power grid, obtain the current load inertia of the power grid.

[0068] S3: Obtain the current inertia of the synchronous machine type and the new energy inertia of the power grid, and superimpose the current load inertia, synchronous machine type inertia and new energy inertia of the power grid to obtain the current system inertia of the power grid.

[0069] This invention provides an online power grid inertia assessment method. First, based on the system inertia, synchronous machine type inertia, new energy inertia, and load level of the power grid during several historical disturbance events within a set time range, the average inertia per unit load of the power grid is obtained. Then, the current load level of the power grid is acquired, and based on the average inertia per unit load, the current load inertia of the power grid is obtained. Finally, the current load inertia, synchronous machine type inertia, and new energy inertia are superimposed to obtain the current system inertia of the power grid. This invention is based on online inertia assessment under disturbance events, using the average inertia per unit load within a set time range assessed by multiple disturbance events. It can assess load inertia based on the actual load level during steady-state operation. Combined with online statistics of synchronous machine type inertia and new energy inertia, it achieves online assessment of the system inertia of the power grid during steady-state operation, improving the accuracy of inertia monitoring, providing a new technical means for power grid operation monitoring, and ensuring the safe and stable operation of the power grid.

[0070] In one possible implementation, the online power grid inertia assessment method further includes: obtaining the system inertia of the power grid during several historical disturbance events within a set time range using the following formula:

[0071]

[0072] Among them, H sd Let f be the system inertia of the power grid during historical disturbance events, ΔP be the active power of the power grid during historical disturbance events, and f be the system inertia of the power grid during historical disturbance events. N df / ft is the rated frequency of the power grid during historical disturbance events, and df / ft is the rate of change of the system center point frequency of the power grid during historical disturbance events.

[0073] Explanatory, several historical disturbance events specifically refer to major disturbance events that have occurred in history, such as DC station commutation failures, DC blocking, and other disturbance events that result in significant active power loss.

[0074] Specifically, the change in total active power of the entire power grid system before and after a disturbance event, or the imbalance between active power and load, is statistically analyzed. This represents the active power loss ΔP of the power grid during historical disturbance events. Then, the frequency values ​​measured by the PMU monitoring points of all power plants in the network after the disturbance are aggregated to form the system center frequency f. COI Through the system center point frequency f COI The frequency change rate df / ft is calculated from the change value, and then combined with the rated frequency f. N ,pass Calculate the system inertia H of the power grid during a disturbance event. sd .

[0075] In one possible implementation, the online power grid inertia assessment method further includes: obtaining the synchronous machine-type inertia of the power grid during several historical disturbance events within a set time range using the following formula:

[0076]

[0077] H ssdall =H ssd +H scd +H spd

[0078] Among them, H ssd H represents the inertia of the synchronous generators in the power grid during historical disturbance events. si S is the inertial constant of the i-th synchronous generator; si The rated capacity of the i-th synchronous generator is given by Nssd; the number of synchronous generators in operation during historical disturbance events in the power grid is given by H. scd H represents the inertia of the synchronous condenser during historical disturbance events in the power grid. ci S is the inertial constant of the i-th synchronous camera; ci Let i be the rated capacity of the i-th synchronous camera; Nscd H represents the number of synchronous condensers in operation during historical disturbance events in the power grid. spd H represents the inertia of the pumped-storage power station during historical disturbance events in the power grid. pi S is the inertial constant of the i-th pumped storage power station; pi is the rated capacity of the i-th pumped storage power station; Nspd is the number of pumped storage power stations in operation during the historical disturbance event; This represents the inertia of the synchronous machine type in the power grid during historical disturbance events.

[0079] Explanatoryly, the inertia of synchronous machines mainly refers to resources with the rotational inertia of synchronous generators, including synchronous generators, synchronous condensers, and pumped storage power stations.

[0080] For the inertia of synchronous generators, an offline inertia statistics method is adopted. Based on the commissioning status of all synchronous generator units, the inertia of the synchronous generator units in operation are selected for statistical analysis.

[0081] Regarding the inertia of synchronous condensers, since a large number of synchronous condensers are deployed in the power grid, although these devices do not provide active power, they are still a type of synchronous motor and possess rotational kinetic energy. When frequency disturbances occur, their selective kinetic energy can provide inertial support, therefore, the inertia of synchronous condensers needs to be considered. Similar to the inertia of synchronous generators, the inertia of a synchronous condenser is calculated based on its rotational kinetic energy using its own inertial constant and rated capacity.

[0082] Regarding the inertia of pumped storage power stations, since pumped storage power stations also operate as synchronous generators, although they have two different states—generating power or consuming power—they provide inertial support to the grid as long as they are connected to it. Therefore, the inertia of pumped storage power stations must also be included. The inertia is calculated according to the state of the pumped storage power station connected to the grid at the time of the disturbance, using the same method as for synchronous generators.

[0083] By summarizing the inertia of synchronous generators, synchronous condensers, and pumped storage power stations, the synchronous machine type inertia of the entire power grid at the time of a disturbance event can be formed.

[0084] In one possible implementation, the online grid inertia assessment method further includes: obtaining the renewable energy inertia of the grid during several historical disturbance events within a set time range using the following formula:

[0085]

[0086] Among them, H rsd H represents the inertia of renewable energy power plants during historical disturbance events; ri S is the inertial constant of the i-th renewable energy power plant; ri denoted as the actual output of the i-th renewable energy power plant; Nrsd represents the number of renewable energy power plants that meet the preset requirements during historical disturbance events; where the preset requirements are renewable energy power plants whose actual output to rated capacity ratio exceeds a preset threshold.

[0087] Explaining the implications, both wind and solar power, due to their grid connection via inverters, require wind and solar power plants to provide inertia support capabilities, i.e., virtual inertia, according to relevant requirements for new energy grid connection. The virtual inertia provided by each new energy plant also has an inertia constant, the specific value of which can be flexibly set according to the project. If the virtual inertia constant of the new energy plant is H... ri Then, based on its actual output S riThe inertia of the new energy provided by the new energy power plant can be calculated.

[0088] See Figure 2 It should be noted here that a prerequisite for including the inertia of new energy sources in the assessment is that their actual power output S ri The ratio of the new energy power plant's output to its rated capacity exceeds a threshold value M, which can be flexibly set. For example, if M = 20%, then the new energy power plant's inertia will only be considered when its output reaches 20% or more of its rated capacity. If the actual output of the new energy power plant is less than 20%, then even if the power plant is connected to the grid, it will not be included in the statistical calculation of the new energy inertia due to its small output.

[0089] Furthermore, for new energy power plants whose actual output exceeds the threshold value M, since current grid-connected new energy plants operate at their maximum output, disturbances at this operating state make it difficult for them to provide inertia support. Therefore, if new energy power plants are to have new energy inertia support capabilities, they need to sacrifice some economic efficiency, i.e., they cannot operate at maximum power. Only in this way can frequency support be achieved by increasing active power output after an active power shortage, thus achieving a similar effect to inertia support.

[0090] In one possible implementation, obtaining the average inertia per unit load of the power grid based on the system inertia, synchronous machine type inertia, new energy inertia, and load level of the power grid during several historical disturbance events within a set time range includes: obtaining the load inertia of the power grid during several historical disturbance events within a set time range using the following formula:

[0091]

[0092] Among them, H ld This represents the load inertia of the power grid during historical disturbance events.

[0093] The inertia per unit load of the power grid during several historical disturbance events within a set time range is obtained using the following formula:

[0094]

[0095] in, P represents the inertia of the power grid per unit load during historical disturbance events. LD This represents the load level of the power grid during historical disturbance events.

[0096] The average inertia per unit load of the power grid is obtained using the following formula.

[0097]

[0098] Where N represents the number of historical disturbance events. Let be the unit load inertia of the power grid at the i-th historical disturbance event.

[0099] Explanatoryly, the load side theoretically involves parameters such as resistance, capacitance, and inductance, while in actual operation, it involves equipment such as synchronous motors, asynchronous motors, and power electronic devices. Currently, there is a lack of research on the assessment of load inertia, and how to accurately assess load inertia online is a challenge for research both domestically and internationally. For this reason, this invention integrates load inertia and approximates its assessment as a whole.

[0100] When a disturbance occurs, the total load P at the time of the disturbance can be obtained through power grid dispatch and operation monitoring data. LD See also Figure 3 Because the system inertia H obtained through online identification after the disturbance occurs sd The total inertia of the system is given by the fact that it is mainly composed of three parts: the inertia of the synchronous machine type, the inertia of the new energy source, and the inertia of the load. Therefore, after obtaining the inertia of the synchronous machine type and the inertia of the new energy source, the inertia of the load can be obtained.

[0101] The total power consumed by the load after the disturbance event is P LD Its corresponding inertia is H ld Therefore, the inertia that a unit load can provide can be estimated, i.e. The above calculation To avoid errors in the calculation of the unit load corresponding inertia caused by the error in the calculation results, the unit load corresponding inertia of multiple disturbance events over a period of time can be summarized and averaged to obtain the average unit load corresponding inertia, thereby improving the accuracy of the assessment.

[0102] It should be noted that the reason for averaging the unit load inertia values ​​from multiple disturbance events over a period of time is primarily to account for the inherent volatility and error in single calculations. Using values ​​obtained from multiple disturbance events improves the accuracy of the unit load inertia calculation. The reason for selecting a period of disturbance events is to ensure that the proportion of different types of loads on the load side does not change significantly during this time.

[0103] In one possible implementation, the online power grid inertia assessment method further includes: when the current time exceeds the currently set time range and no new disturbance events occur, continuing to use the average inertia per unit load of the power grid within the currently set time range; when the current time exceeds the currently set time range and new disturbance events occur, updating the average inertia per unit load of the power grid based on the system inertia, synchronous machine type inertia, new energy inertia, and load level at several historical disturbance events within the next set time range.

[0104] Explanatory, see Figure 4 The time range can be flexibly set, such as 1 year or 15 months. If the time range is exceeded, the average inertia per unit load within the new time range needs to be selected for calculation. If there are no new disturbance events, the calculation can be performed temporarily based on the previous average inertia per unit load. When a new disturbance event occurs, the average inertia per unit load calculated based on the new disturbance event should be used immediately for calculation.

[0105] In one possible implementation, obtaining the current load level of the power grid and deriving the current load inertia of the power grid based on the average inertia per unit load includes obtaining the current load inertia of the power grid using the following formula:

[0106]

[0107] Among them, H L Let P be the current load inertia of the power grid. L Given the current load level of the power grid, This represents the average inertia per unit load of the power grid.

[0108] Explanatoryly, during steady-state operation, the power generation and consumption of the entire power grid are dynamically balanced. Power generation increases with the increase in power load. When assessing the load inertia under steady-state conditions, the current load level P is first obtained. L Then, based on the average inertia per unit load of the power grid obtained from the assessment... Calculate the current load inertia of the power grid

[0109] For the current inertia of the synchronous machine type and the new energy inertia of the power grid, the acquisition method is consistent with the inertia of the synchronous machine type and the new energy inertia during historical disturbance events.

[0110] Specifically, based on the current operating status of the synchronous generator units in the power grid, the current inertia of the synchronous generators in the power grid is calculated. At the same time, synchronous condensers and pumped storage power stations are also calculated in the same way, based on their operating status, the inertial constants and rated capacities of each unit, to obtain the current inertia of the synchronous generator type in the power grid.

[0111] Since renewable energy power plants can also calculate their inertia values ​​based on their current operating status, for renewable energy power plants where the ratio of actual output to rated capacity is greater than a threshold value M, the current renewable energy inertia of the power grid is calculated based on the inertial constant of each renewable energy power plant and its actual output. This calculation method is the same as the method for summarizing renewable energy inertia when a disturbance event occurs.

[0112] Combining the above inertia calculation results—namely, the current load inertia, synchronous machine type inertia, and new energy inertia—we obtain the current system inertia of the power grid, which is the sum of the current load inertia, synchronous machine type inertia, and new energy inertia.

[0113] In one possible implementation, the online power grid inertia assessment method further includes: acquiring the current system inertia of the power grid at preset time intervals, obtaining several assessed power grid system inertias, and constructing a curve of the assessed power grid system inertia changing over time based on the several assessed power grid system inertias.

[0114] Explanatoryly, since the operating status of generating units, the output of new energy sources, and the load do not change rapidly during steady-state operation, the system inertia can be evaluated at regular intervals, such as every 5 minutes or 15 minutes. This allows us to obtain the curve of the power grid's system inertia changing over time.

[0115] The following are system embodiments of the present invention, which can be used to execute the method embodiments of the present invention. For details not disclosed in the system embodiments, please refer to the method embodiments of the present invention.

[0116] See Figure 5 In another embodiment of the present invention, an online power grid inertia assessment system is provided, which can be used to implement the above-mentioned online power grid inertia assessment method. Specifically, the online power grid inertia assessment system includes a unit load corresponding inertia assessment module, a load inertia assessment module, and a system inertia assessment module.

[0117] The unit load corresponding inertia assessment module is used to obtain the average unit load corresponding inertia of the power grid based on the system inertia, synchronous machine type inertia, new energy inertia, and load level of the power grid during several historical disturbance events within a set time range; the load inertia assessment module is used to obtain the current load level of the power grid and obtain the current load inertia of the power grid based on the average unit load corresponding inertia of the power grid; the system inertia assessment module is used to obtain the current synchronous machine type inertia and new energy inertia of the power grid, and superimpose the current load inertia, synchronous machine type inertia, and new energy inertia of the power grid to obtain the current system inertia of the power grid.

[0118] In one possible implementation, the online power grid inertia assessment system further includes a historical system inertia acquisition module, which is used to acquire the system inertia of the power grid during several historical disturbance events within a set time range using the following formula:

[0119]

[0120] Among them, H sd Let f be the system inertia of the power grid during historical disturbance events, ΔP be the active power of the power grid during historical disturbance events, and f be the system inertia of the power grid during historical disturbance events.N df / ft is the rated frequency of the power grid during historical disturbance events, and df / ft is the rate of change of the system center point frequency of the power grid during historical disturbance events.

[0121] In one possible implementation, the online power grid inertia assessment system further includes a historical synchronous machine type inertia acquisition module and a historical new energy source inertia acquisition module.

[0122] The historical synchro type inertia acquisition module is used to obtain the synchro type inertia of the power grid during several historical disturbance events within a set time range using the following formula:

[0123]

[0124] Among them, H ssd H represents the inertia of the synchronous generators in the power grid during historical disturbance events. si S is the inertial constant of the i-th synchronous generator; si The rated capacity of the i-th synchronous generator is given by Nssd; the number of synchronous generators in operation during historical disturbance events in the power grid is given by H. scd H represents the inertia of the synchronous condenser during historical disturbance events in the power grid. ci S is the inertial constant of the i-th synchronous camera; ci Let i be the rated capacity of the i-th synchronous camera; Nscd H represents the number of synchronous condensers in operation during historical disturbance events in the power grid. spd H represents the inertia of the pumped-storage power station during historical disturbance events in the power grid. pi S is the inertial constant of the i-th pumped storage power station; pi Let be the rated capacity of the i-th pumped storage power station; Nspd The number of pumped storage power stations in operation during historical disturbance events in the power grid; This represents the inertia of the synchronous machine type in the power grid during historical disturbance events.

[0125] The historical renewable energy inertia acquisition module is used to obtain the renewable energy inertia of the power grid during several historical disturbance events within a set time range using the following formula:

[0126]

[0127] Among them, H rsd H represents the inertia of renewable energy power plants during historical disturbance events; ri S is the inertial constant of the i-th renewable energy power plant; ri denoted as the actual output of the i-th renewable energy power plant; Nrsd represents the number of renewable energy power plants that meet the preset requirements during historical disturbance events; where the preset requirements are renewable energy power plants whose actual output to rated capacity ratio exceeds a preset threshold.

[0128] In one possible implementation, obtaining the average inertia per unit load of the power grid based on the system inertia, synchronous machine type inertia, new energy inertia, and load level of the power grid during several historical disturbance events within a set time range includes: obtaining the load inertia of the power grid during several historical disturbance events within a set time range using the following formula:

[0129]

[0130] Among them, H ld This represents the load inertia of the power grid during historical disturbance events.

[0131] The inertia per unit load of the power grid during several historical disturbance events within a set time range is obtained using the following formula:

[0132]

[0133] in, P represents the inertia of the power grid per unit load during historical disturbance events. LD This represents the load level of the power grid during historical disturbance events.

[0134] The average inertia per unit load of the power grid is obtained using the following formula.

[0135]

[0136] Where N represents the number of historical disturbance events. Let be the unit load inertia of the power grid at the i-th historical disturbance event.

[0137] In one possible implementation, the online power grid inertia assessment system further includes a curve construction module, which is used to acquire the current system inertia of the power grid at preset time intervals, obtain several assessed power grid system inertia, and construct a curve of the assessed power grid system inertia changing over time based on the several assessed power grid system inertia.

[0138] In one possible implementation, the online power grid inertia assessment system further includes an update module. This update module is used to continue using the average inertia per unit load of the power grid for the next set time range when the current time exceeds the current set time range and no new disturbance events occur; and when the current time exceeds the current set time range and new disturbance events occur, to obtain the average inertia per unit load of the power grid for the next set time range based on the system inertia, synchronous machine type inertia, new energy inertia, and load level at several historical disturbance events within the next set time range.

[0139] All relevant content of each step involved in the aforementioned embodiments of the online power grid inertia assessment method can be referenced to the functional description of the corresponding functional module of the online power grid inertia assessment system in the embodiments of the present invention, and will not be repeated here.

[0140] The module division in this embodiment of the invention is illustrative and represents only one logical functional division. In actual implementation, other division methods may be used. Furthermore, the functional modules in the various embodiments of the invention can be integrated into a single processor, exist as separate physical entities, or be integrated into a single module. The integrated modules described above can be implemented in hardware or as software functional modules.

[0141] In another embodiment of the present invention, a computer device is provided, comprising a processor and a memory. The memory stores a computer program, which includes program instructions. The processor executes the program instructions stored in the computer storage medium. The processor may be a Central Processing Unit (CPU), or other general-purpose processors, digital signal processors (DSPs), application-specific integrated circuits (ASICs), field-programmable gate arrays (FPGAs), or other programmable logic devices, discrete gate or transistor logic devices, discrete hardware components, etc. It is the computing and control core of the terminal, suitable for implementing one or more instructions, specifically suitable for loading and executing one or more instructions from the computer storage medium to achieve a corresponding method flow or function. The processor described in this embodiment of the present invention can be used for the operation of an online power grid inertia assessment method.

[0142] In another embodiment of the present invention, a storage medium is provided, specifically a computer-readable storage medium (Memory), which is a memory device in a computer device used to store programs and data. It is understood that the computer-readable storage medium here can include both the built-in storage medium in the computer device and extended storage media supported by the computer device. The computer-readable storage medium provides storage space that stores the terminal's operating system. Furthermore, the storage space also stores one or more instructions suitable for loading and execution by a processor. These instructions can be one or more computer programs (including program code). It should be noted that the computer-readable storage medium here can be high-speed RAM or non-volatile memory, such as at least one disk storage device. The processor can load and execute one or more instructions stored in the computer-readable storage medium to implement the corresponding steps of the online power grid inertia assessment method in the above embodiments.

[0143] Those skilled in the art will understand that embodiments of the present invention can be provided as methods, systems, or computer program products. Therefore, the present invention can take the form of a completely hardware embodiment, a completely software embodiment, or an embodiment combining software and hardware aspects. Furthermore, the present invention can take the form of a computer program product embodied on one or more computer-usable storage media (including, but not limited to, disk storage, CD-ROM, optical storage, etc.) containing computer-usable program code.

[0144] This invention is described with reference to flowchart illustrations and / or block diagrams of methods, apparatus (systems), and computer program products according to embodiments of the invention. It will be understood that each block of the flowchart illustrations and / or block diagrams, and combinations of blocks in the flowchart illustrations and / or block diagrams, can be implemented by computer program instructions. These computer program instructions can be provided to a processor of a general-purpose computer, special-purpose computer, embedded processor, or other programmable data processing apparatus to produce a machine, such that the instructions, which execute via the processor of the computer or other programmable data processing apparatus, generate instructions for implementing the flowchart illustrations and / or block diagrams. Figure 1 One or more processes and / or boxes Figure 1 A device that provides the functions specified in one or more boxes.

[0145] These computer program instructions may also be stored in a computer-readable storage medium that can direct a computer or other programmable data processing device to function in a particular manner, such that the instructions stored in the computer-readable storage medium produce an article of manufacture including instruction means, which are implemented in a process Figure 1 One or more processes and / or boxes Figure 1The function specified in one or more boxes.

[0146] These computer program instructions may also be loaded onto a computer or other programmable data processing equipment to cause a series of operational steps to be performed on the computer or other programmable equipment to produce a computer-implemented process, thereby providing instructions that execute on the computer or other programmable equipment for implementing the process. Figure 1 One or more processes and / or boxes Figure 1 The steps of the function specified in one or more boxes.

[0147] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and not to limit it. Although the present invention has been described in detail with reference to the above embodiments, those skilled in the art should understand that modifications or equivalent substitutions can still be made to the specific implementation of the present invention. Any modifications or equivalent substitutions that do not depart from the spirit and scope of the present invention should be covered within the scope of protection of the claims of the present invention.

Claims

1. A method for online assessment of power grid inertia, characterized in that, include: Based on the system inertia, synchronous machine type inertia, new energy inertia, and load level of the power grid during several historical disturbance events within a set time range, the average inertia per unit load of the power grid is obtained; the average inertia per unit load of the power grid is obtained through the following formula. : in, This represents the load inertia of the power grid during historical disturbance events. This represents the inertia of the power grid per unit load during historical disturbance events; This refers to the load level of the power grid during historical disturbance events; N This represents the number of historical disturbance events. For the power grid in the first i Inertia corresponding to a unit load during a historical disturbance event; Obtain the current load level of the power grid, and based on the average inertia per unit load of the power grid, obtain the current load inertia of the power grid; Obtain the current inertia of the synchronous machine type and the new energy inertia of the power grid, and superimpose the current load inertia, synchronous machine type inertia and new energy inertia of the power grid to obtain the current system inertia of the power grid; For the inertia of new energy sources, only new energy power plants whose actual output exceeds the threshold value are considered in the calculation. Synchronous machine inertia includes synchronous generator inertia, synchronous condenser inertia, and pumped storage power station inertia; It also includes: when the current time exceeds the currently set time range and no new disturbance events occur, continue to use the average inertia value of the power grid per unit load within the currently set time range; When the current time exceeds the currently set time range and a new disturbance event occurs, the average inertia value per unit load of the power grid is updated based on the system inertia, synchronous machine type inertia, new energy inertia, and load level at several historical disturbance events within the next set time range.

2. The online power grid inertia assessment method according to claim 1, characterized in that, Also includes: The system inertia of the power grid during several historical disturbance events within a set time range is obtained by the following formula: in, This represents the system inertia of the power grid during historical disturbance events. This represents the active power lost by the power grid during historical disturbance events. The rated frequency of the power grid during historical disturbance events. This represents the rate of change of the system center point frequency of the power grid during historical disturbance events.

3. The online power grid inertia assessment method according to claim 2, characterized in that, Also includes: The synchronous machine type inertia of the power grid during several historical disturbance events within a set time range is obtained by the following formula: in, This represents the inertia of the synchronous generators in the power grid during historical disturbance events. For the first i The inertial constant of a synchronous generator; For the first i The rated capacity of each synchronous generator; This refers to the number of synchronous generators in operation on the power grid during historical disturbance events. The inertia of the synchronous condenser during historical disturbance events in the power grid; For the first i The inertial constant of a synchronous modulator; For the first i The rated capacity of each synchronous synchrotron; The number of synchronous condensers in operation during historical disturbance events in the power grid; The inertia of pumped storage power stations during historical disturbance events in the power grid; For the first i The inertial constant of a pumped storage power station; For the first i The rated capacity of a pumped storage power station; The number of pumped storage power stations in operation during historical disturbance events in the power grid; The inertia of the synchronous machine type of the power grid during historical disturbance events; The inertia of new energy sources during several historical disturbance events within a set time range can be obtained using the following formula: in, The inertia of new energy power plants during historical disturbance events; For the first i The inertial constant of a new energy power plant; For the first i The actual output of each new energy plant; This refers to the number of renewable energy power plants that meet preset requirements during historical disturbance events; the preset requirements are renewable energy power plants whose actual output to rated capacity ratio exceeds a preset threshold.

4. The online power grid inertia assessment method according to claim 3, characterized in that, The process of obtaining the average inertia per unit load of the power grid based on the system inertia, synchronous machine type inertia, new energy inertia, and load level during several historical disturbance events within a set time range includes: The load inertia of the power grid during several historical disturbance events within a set time range is obtained using the following formula: = - - 。 5. The online power grid inertia assessment method according to claim 1, characterized in that, Also includes: The current system inertia of the power grid is acquired at each preset time interval, and several evaluation power grid system inertia are obtained. Based on these evaluation power grid system inertia, a curve of the evaluation power grid system inertia changing over time is constructed.

6. An online power grid inertia assessment system, characterized in that, include: The unit load corresponding inertia assessment module is used to obtain the average unit load corresponding inertia of the power grid based on the system inertia, synchronous machine type inertia, new energy inertia, and load level of the power grid during several historical disturbance events within a set time range. The average unit load corresponding inertia of the power grid is obtained through the following formula. : in, This represents the load inertia of the power grid during historical disturbance events. This represents the inertia of the power grid per unit load during historical disturbance events; This refers to the load level of the power grid during historical disturbance events; N This represents the number of historical disturbance events. For the power grid in the first i Inertia corresponding to a unit load during a historical disturbance event; The load inertia assessment module is used to obtain the current load level of the power grid and, based on the average inertia per unit load of the power grid, to obtain the current load inertia of the power grid. The system inertia assessment module is used to obtain the current synchronous machine type inertia and new energy inertia of the power grid, and to superimpose the current load inertia, synchronous machine type inertia and new energy inertia of the power grid to obtain the current system inertia of the power grid; For the inertia of new energy sources, only new energy power plants whose actual output exceeds the threshold value are considered in the calculation. Synchronous machine inertia includes synchronous generator inertia, synchronous condenser inertia, and pumped storage power station inertia; It also includes an update module, which is used to continue using the average inertia per unit load of the power grid in the next set time range when the current time exceeds the current set time range and no new disturbance event occurs; when the current time exceeds the current set time range and a new disturbance event occurs, it obtains the average inertia per unit load of the power grid in the next set time range based on the system inertia, synchronous machine type inertia, new energy inertia and load level at several historical disturbance events in the next set time range.

7. The online power grid inertia assessment system according to claim 6, characterized in that, It also includes a historical system inertia acquisition module, which is used to obtain the system inertia of the power grid during several historical disturbance events within a set time range using the following formula: in, This represents the system inertia of the power grid during historical disturbance events. This refers to the active power of the power grid during historical disturbance events. The rated frequency of the power grid during historical disturbance events. This represents the rate of change of the system center point frequency of the power grid during historical disturbance events.

8. The online power grid inertia assessment system according to claim 7, characterized in that, It also includes a historical synchronous machine type inertia acquisition module and a historical new energy inertia acquisition module; The historical synchro type inertia acquisition module is used to obtain the synchro type inertia of the power grid during several historical disturbance events within a set time range using the following formula: in, This represents the inertia of the synchronous generators in the power grid during historical disturbance events. For the first i The inertial constant of a synchronous generator; For the first i The rated capacity of each synchronous generator; This refers to the number of synchronous generators in operation on the power grid during historical disturbance events. The inertia of the synchronous condenser during historical disturbance events in the power grid; For the first i The inertial constant of a synchronous modulator; For the first i The rated capacity of each synchronous synchrotron; The number of synchronous condensers in operation during historical disturbance events in the power grid; The inertia of pumped storage power stations during historical disturbance events in the power grid; For the first i The inertial constant of a pumped storage power station; For the first i The rated capacity of a pumped storage power station; The number of pumped storage power stations in operation during historical disturbance events in the power grid; The inertia of the synchronous machine type of the power grid during historical disturbance events; The historical renewable energy inertia acquisition module is used to obtain the renewable energy inertia of the power grid during several historical disturbance events within a set time range using the following formula: in, The inertia of new energy power plants during historical disturbance events; For the first i The inertial constant of a new energy power plant; For the first i The actual output of each new energy plant; This refers to the number of renewable energy power plants that meet preset requirements during historical disturbance events; the preset requirements are renewable energy power plants whose actual output to rated capacity ratio exceeds a preset threshold.

9. The online power grid inertia assessment system according to claim 8, characterized in that, The process of obtaining the average inertia per unit load of the power grid based on the system inertia, synchronous machine type inertia, new energy inertia, and load level during several historical disturbance events within a set time range includes: The load inertia of the power grid during several historical disturbance events within a set time range is obtained using the following formula: = - - 。 10. The online power grid inertia assessment system according to claim 6, characterized in that, It also includes a curve construction module, which is used to obtain the current system inertia of the power grid at preset time intervals, obtain several evaluation power grid system inertia, and construct a curve of the evaluation power grid system inertia changing with time based on the several evaluation power grid system inertia.

11. A computer device comprising a memory, a processor, and a computer program stored in the memory and executable on the processor, characterized in that, When the processor executes the computer program, it implements the steps of the online power grid inertia assessment method as described in any one of claims 1 to 5.

12. A computer-readable storage medium storing a computer program, characterized in that, When the computer program is executed by the processor, it implements the steps of the online power grid inertia assessment method as described in any one of claims 1 to 5.

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