A method and system for detecting stability of a regional power grid

Abstract

The present application belongs to the field of electric power, and particularly relates to a regional power grid stability detection method and system. The method comprises determining a first time for a grid-connected power supply to access a regional power grid to a stable state of the regional power grid; obtaining a first output value of the grid-connected power supply; and calculating a power grid stability value according to the first output value and the first time. By determining the stable state of the regional power grid, it can be shown that the grid-connected power supply will not have a destructive impact on the regional power grid. By the access time, the time when the grid-connected power supply has an impact can be determined. By the first output value of the grid-connected power supply and the first time, the change generated by the grid-connected power supply within a specific time and the feedback received can be determined to evaluate the stability of the regional power grid.

Description

Technical Field

[0001] This invention belongs to the field of power, and in particular relates to a method and system for detecting the stability of a regional power grid. Background Technology

[0002] Electricity, as an essential energy source for the operation of society, is supplied to specific areas through the power grid. Social development is a dynamic process; therefore, the construction and operation of the power grid are not static.

[0003] As electricity demand increases or new power sources are added, the newly connected power source will impact the operation of the power grid itself. This change will not only affect the new power source but may also affect other parts of the grid. Therefore, when a new power source is connected to a regional power grid, it is necessary to monitor the connected power source and determine its impact on the grid.

[0004] Current detection technologies are mainly designed for power plants with high stability, but lack the ability to detect the impact of smaller, relatively isolated power sources on the power grid. Summary of the Invention

[0005] To address or improve the above problems, this invention provides a method and system for detecting the stability of a regional power grid, the specific technical solution of which is as follows:

[0006] This invention provides a method for detecting the stability of a regional power grid, comprising:

[0007] The first time from when a grid-connected power source with uncertain output is connected to the regional power grid until the regional power grid reaches a stable state;

[0008] Obtain the first output value of the grid-connected power source;

[0009] The power grid stability value is calculated based on the first output value and the first time.

[0010] Preferably, the first output value includes a first output sequence obtained by processing the output curve of the grid-connected power source based on a preset time interval; correspondingly, the grid stability value is calculated based on the first output sequence and the first time.

[0011] Preferably, the regional power grid stability detection method includes: processing the first output sequence by multiplying coefficients to obtain a second output sequence;

[0012] Correspondingly, the power grid stability value is calculated based on the second output sequence and the first time.

[0013] Preferably, the regional power grid stability detection method includes: determining the preset time interval and / or the coefficient multiplied by the coefficient based on at least one of the power supply increase value, load simultaneity rate and regional correction value of the regional power grid.

[0014] Preferably, the coefficients multiplied by the coefficients include (1+p)*q, where p is the power increase value determined based on the number of grid-connected power sources and the original number of power sources when the regional power grid is not connected to the grid-connected power sources; and q is the load simultaneity rate of the regional power grid after the grid-connected power sources are connected.

[0015] Preferably, the coefficients multiplied include (1+p)*q*k, where k is a regional correction value used to represent the power stability requirements of different regions.

[0016] Preferably, the step of calculating the power grid stability value based on the first output value and the first time includes: determining a first time period in which the maximum rate of change occurs from the output data for a first time length; filtering second output data including the first time period from the output data for a second time length; and calculating the power grid stability value based on the second output data and the first time.

[0017] Preferably, the grid-connected power source is a power source based on wind energy and / or solar energy.

[0018] Preferably, the power grid stability value is calculated based on the first output value and the first time using commercial data processing software.

[0019] This invention provides a regional power grid stability detection system, comprising: a time recording unit for determining the first time from when the grid-connected power source connects to the regional power grid until the regional power grid reaches a stable state; a data acquisition unit for acquiring the first output value of the grid-connected power source; and a data processing unit for calculating a power grid stability value based on the first output value and the first time.

[0020] The beneficial effects of this invention are as follows: by determining the stable state of the regional power grid, it can be shown that the grid-connected power source will not have a destructive impact on the regional power grid; the connection time can be used to determine the time when the grid-connected power source has an impact; by using the first output value and the first time of the grid-connected power source, the changes generated by the grid-connected power source within a specific time period and the feedback received can be determined to assess the stability of the regional power grid. Attached Figure Description

[0021] Figure 1 This is a schematic diagram of the regional power grid stability detection method according to the present invention;

[0022] Figure 2This is a schematic diagram of the regional power grid stability detection system according to the present invention.

[0023] Explanation of key figure labels:

[0024] 1-Time recording unit, 2-Data acquisition unit, 3-Data processing unit. Detailed Implementation

[0025] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0026] It should be understood that, when used in this specification and the appended claims, the terms "comprising" and "including" indicate the presence of the described features, integrals, steps, operations, elements and / or components, but do not exclude the presence or addition of one or more other features, integrals, steps, operations, elements, components and / or collections thereof.

[0027] It should also be understood that the terminology used in this specification is for the purpose of describing particular embodiments only and is not intended to limit the invention. As used in this specification and the appended claims, the singular forms “a,” “an,” and “the” are intended to include the plural forms unless the context clearly indicates otherwise.

[0028] It should also be further understood that the term "and / or" as used in this specification and the appended claims refers to any combination of one or more of the associated listed items and all possible combinations, and includes such combinations.

[0029] To address or improve the problem of power grid stability monitoring, the following proposals are put forward: Figure 1 The method for detecting the stability of a regional power grid, as shown, includes:

[0030] S1. Determine the first time from when the grid-connected power source connects to the regional power grid until the regional power grid reaches a stable state;

[0031] S2. Obtain the first output value of the grid-connected power source;

[0032] S3. Calculate the power grid stability value based on the first output value and the first time.

[0033] For safety reasons, power grids often form a radial structure within a certain area. For example, ultra-high-voltage electricity from a distant source might be input into the local area, and then local substations would output high-voltage electricity for factories within the region and mains power for residents; or local power plants might supply electricity to the local area. The working mechanism of a power grid is exceptionally complex; the more loads and power sources connected, the more likely it is to generate difficult-to-resolve anomalies during actual operation. Therefore, a radial structure, interconnected with surrounding areas through a few regional tie lines, is a common power grid configuration, forming a regional power grid.

[0034] Large, resource-rich cities can easily secure large, stable power sources. Even so, these cities experience diverse electricity demands, such as factories requiring specific voltages or needing backup power. Smaller cities, on the other hand, may experience aging power infrastructure or urban development leading to abnormal or insufficient power output, necessitating replacement or addition of power sources. Due to the complexity of power grid mechanisms, in practice, new power sources rarely adapt perfectly to the regional grid upon connection; instead, numerous problems arise. Furthermore, simply replacing power source A with power source B after a grid connection failure is not always a solution. Therefore, after a power source A experiences grid connection failure, it is necessary to investigate and analyze power source A before deciding whether to adjust power source A and the grid, or replace it with power source B.

[0035] It is essential to ensure that the grid-connected power source will not experience problems in a given area's power grid after being connected to it. In Chinese regulations, standards, and literature, power system stability is generally categorized into the following two types:

[0036] 1) Static stability: Static stability of a power system mainly refers to the ability of a power system to maintain its original state or continue to operate in a state close to its original state after being subjected to a small disturbance. This operating condition is called static stability or small disturbance stability.

[0037] 2) Transient stability: If a power system reaches a state different from the original state after a disturbance, but can still operate stably, this operating state is called transient stability.

[0038] Generally speaking, meeting the conditions for transient stability contributes to the static stability of the system. Conversely, maintaining static stability is a prerequisite for transient stability. In practice, maintaining a certain static stability margin can help ensure transient stability in the event of a severe fault.

[0039] Once it is confirmed that the grid-connected power source has been connected to the regional power grid, and the regional power grid has achieved a stable state (i.e., static and transient stability as described above), the grid-connected power source has the foundation for safe and stable operation. The time of grid-connected power source connection to the regional power grid and the time when the regional power grid achieves a stable state (i.e., the first moment) are recorded as time data for analyzing the impact of the grid-connected power source on the regional power grid.

[0040] The function of a grid-connected power source is to output electricity. The output value is a parameter that specifically evaluates the power output capability of the power source, including electromagnetic power, mechanical power, active power, and reactive power.

[0041] In the initial stage of grid connection, the connected power source will interact with the regional power grid and will not immediately operate at its rated output. Green new energy sources, primarily wind and solar power, are the main forms of energy structure transformation, and their output is random and uncertain. It requires interaction between the connected power source and the regional power grid until a certain stable state is reached. By obtaining the output values ​​during this process, filtering the output values ​​for a specific time period, and processing them according to a set formula, a grid stability value is obtained to evaluate the stability of the regional power grid after the connection of the power source.

[0042] The first output value includes a first output sequence obtained by processing the output curve of the grid-connected power source based on a preset time interval; correspondingly, the grid stability value is calculated based on the first output sequence and the first time.

[0043] The working mechanism of a power grid is complex, and in many cases, the changes occurring at a particular moment cannot be perfectly explained by explicit theories and formulas. Therefore, compared to continuous data curves, data sequences can be better explained by existing theories and calculation formulas. Even if the explanation is not perfect, it can still provide some assistance in solving problems in practice.

[0044] Record the output of one or more power sources with uncertain output within a certain time period, i.e., grid-connected power sources, and convert the corresponding output curves into a discrete time sequence. The time interval of the sequence can be several milliseconds, seconds, minutes, hours, etc., as needed.

[0045] Using computational software such as BPA, PSASP, PSS / E, and MATLAB, at the point of connection of power sources with uncertain output, the output in the sequence is read in the time order listed in the sequence to calculate the transient process of the power grid and obtain the judgment results of frequency and power angle stability. Parameters such as frequency and power angle stability are commonly used parameters for evaluating the state of the power grid. Through these parameters or the values ​​calculated based on these parameters, the state of the regional power grid can be evaluated, that is, the power grid stability value.

[0046] The regional power grid stability detection method includes: processing the first output sequence by multiplying coefficients to obtain a second output sequence; correspondingly, calculating the power grid stability value based on the second output sequence and the first time.

[0047] In the actual calculation of power grid stability, the growth of the power grid can be predicted in advance, and the raw data can be preprocessed. By multiplying the first output sequence by coefficients, the grid's ability to absorb green new energy sources, mainly wind and solar power, can be assessed. Therefore, the first output sequence can be processed by multiplying coefficients to obtain the second output sequence, and then the corresponding power grid stability value can be calculated using the second output sequence.

[0048] The regional power grid stability detection method includes: determining the preset time interval and / or the coefficient multiplied by the coefficient based on at least one of the power supply increase value, load simultaneity rate and regional correction value of the regional power grid.

[0049] The increase or decrease of power supply and load in the power grid fluctuates with the growth or decline of the socio-economic situation. Therefore, by introducing the increase in power supply, load simultaneity rate, and regional correction value of the regional power grid as parameters to improve the calculation of the corresponding power grid stability value, it is possible to adapt to different development situations. Of course, in practice, other factors may also affect the calculation of the corresponding power grid stability value.

[0050] The coefficients multiplied by the coefficients include (1+p)*q, where p is the power increase value determined based on the number of grid-connected power sources and the original number of power sources when the regional power grid was not connected to the grid-connected power sources; q is the load simultaneity rate of the regional power grid after the grid-connected power sources are connected.

[0051] The coefficients multiplied by the coefficients include (1+p)*q*k, where k is a regional correction value used to represent the power stability requirements of different regions.

[0052] The working mechanism of a power grid is complex, and there are not always perfect explanations for the causes and solutions to anomalies. Sometimes, we can only roughly infer that a certain factor caused a certain impact. Therefore, by introducing the power supply increase value, simultaneous load factor, and regional correction value of the regional power grid as parameters to improve the accuracy of the calculated power grid stability value, we can improve the accuracy. Of course, in practice, other factors may also have an impact. There are no restrictions on how to use the power supply increase value, simultaneous load factor, and regional correction value to increase the accuracy of the calculated power grid stability value. The main approach is to set the corresponding formulas based on experience and existing theories. For example, the coefficients multiplied include (1+p)*q, where p is the power supply increase value determined based on the number of grid-connected power sources and the original number of power sources in the regional power grid before grid-connected power sources were connected; q is the simultaneous load factor of the regional power grid after grid-connected power sources were connected. The coefficients multiplied by the coefficients include (1+p)*q*k, where k is a regional correction value used to represent the power stability requirements of different regions. For example, industrial areas have higher power stability requirements, while residential areas have relatively lower power stability requirements. Based on this difference, corresponding regional correction values ​​can be assigned, so the final calculated power grid stability value can more reasonably evaluate the regional power grid stability of different regions.

[0053] The step of calculating the power grid stability value based on the first output value and the first time includes: determining a first time period in which the maximum rate of change occurs from the output data, with a first time length; filtering second output data including the first time period from the output data, with a second time length; and calculating the power grid stability value based on the second output data and the first time.

[0054] Power systems inherently prioritize stability and are designed to mitigate anomalies. Furthermore, they are particularly sensitive to sudden changes. Therefore, when analyzing the stability of power grid operation, data exhibiting the greatest variation can be selected as the primary analytical material. For instance, the highest rate of change in output data poses the greatest threat to grid stability.

[0055] To determine the rate of change, it's necessary to identify both the changing numerical value and the time period of change. A first time length, such as 1 hour, 1 day, or 1 week, can be set as a time frame. The difference between the lowest and highest values ​​within this time frame is taken as the changing numerical value, the time frame length as the time period of change, and the ratio of the changing numerical value to the time period as the rate of change. The largest rate of change is then identified among all output data, and the time frame including this largest rate of change is the first time period. After determining the largest rate of change, it's necessary to select and add continuous data. Analyzing why there is a largest rate of change requires considering nearby time points, not just a single isolated time point. Therefore, a second time length, not less than the first time length, is set as a new time frame, including the first time period. This second time frame is used to identify the anomaly points and nearby time points within the continuous time frame.

[0056] The grid-connected power source is a power source with uncertain output, including new energy sources such as wind power and photovoltaic power, as well as other energy sources affected by the environment, such as tidal power generation; even relatively mature thermal power and hydropower may have unstable output due to various reasons, and in this case, such thermal power and hydropower power sources also belong to power sources with uncertain output.

[0057] The power source with uncertain output is a power source based on wind and solar energy.

[0058] To address or improve the problem of power grid stability monitoring, the following proposals are put forward: Figure 2 A regional power grid stability detection system includes: a time recording unit 1, used to determine the first time from when the grid-connected power source connects to the regional power grid until the regional power grid reaches a stable state; a data acquisition unit 2, used to acquire the first output value of the grid-connected power source; and a data processing unit 3, used to calculate a power grid stability value based on the first output value and the first time.

[0059] Those skilled in the art will recognize that the units of the various examples described in connection with the embodiments disclosed herein can be implemented in electronic hardware, computer software, or a combination of both. To clearly illustrate the interchangeability of hardware and software, the components of the various examples have been generally described in terms of functionality in the foregoing description. Whether these functions are implemented in hardware or software depends on the specific application and design constraints of the technical solution. Those skilled in the art can use different methods to implement the described functions for each specific application, but such implementations should not be considered beyond the scope of the invention.

[0060] In the embodiments provided in this application, it should be understood that the division of units is only a logical functional division. In actual implementation, there may be other division methods, such as multiple units can be combined into one unit, one unit can be split into multiple units, or some features can be ignored.

[0061] 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 them. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features therein. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention, and they should all be covered within the scope of the claims and specification of the present invention.

Claims

1. A method for detecting the stability of a regional power grid, characterized in that, include: The first time from when a grid-connected power source with uncertain output is connected to the regional power grid until the regional power grid reaches a stable state; Obtain the first output value of the grid-connected power source, the first output value including a first output sequence obtained by processing the output curve of the grid-connected power source based on a preset time interval; The coefficient for multiplication is determined based on at least one of the power supply increase, load simultaneity rate, and regional correction value of the regional power grid. The first output sequence is processed by multiplying the coefficients to obtain the second output sequence; specifically, the first output sequence is processed by multiplying the coefficients to obtain the second output sequence. Using the second output sequence as input, the power system transient stability simulation program is used to perform simulation calculations to obtain a power grid stability value that characterizes the judgment results of frequency stability and / or power angle stability during the power grid transient process.

2. The regional power grid stability detection method according to claim 1, characterized in that, The coefficients multiplied include (1+p). q, where, p is the power increase value determined based on the number of grid-connected power sources and the original number of power sources when the regional power grid was not connected to the grid-connected power sources; q is the load simultaneity rate of the regional power grid after the grid-connected power source is connected.

3. The regional power grid stability detection method according to claim 2, characterized in that, The coefficients multiplied by the coefficients include (1+p)qk, where, k is a regional correction value used to represent the power stability requirements of different regions.

4. The regional power grid stability detection method according to claim 2, characterized in that, The calculation of the power grid stability value based on the first output value and the first time includes: Based on the first time length, determine the first time period in which the maximum rate of change occurs from the output data; Using a second time length, filter the output data to include the second output data from the first time period; The power grid stability value is calculated based on the second output data and the first time.

5. The regional power grid stability detection method according to any one of claims 1 to 4, characterized in that, The grid-connected power source is a power source based on wind energy and / or solar energy.

6. The regional power grid stability detection method according to claim 5, characterized in that, The power grid stability value is calculated based on the first output value and the first time using commercial data processing software.

7. A regional power grid stability detection system, characterized in that, include: A time recording unit is used to determine the first time from when a grid-connected power source with uncertain output connects to the regional power grid until the regional power grid reaches a stable state. The data acquisition unit is used to acquire the first output value of the grid-connected power source; The data processing unit, based on the method as described in any one of claims 1-6, is used to calculate a power grid stability value based on the first output value and the first time.

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