Rotational inertia optimization method and system based on new energy plant station

Abstract

The invention relates to the technical field of new energy, in particular to a rotational inertia optimization method and system based on a new energy plant station, and the method comprises the steps: evaluating the total inertia supporting capability of a new energy system and an energy storage system, and obtaining an output total active power range; the inertia of the alternating current system is evaluated, and the evaluated inertia of the alternating current system is obtained; and obtaining the rotational inertia coefficient of the new energy plant station according to the output total active power range and the evaluation inertia of the alternating current system. According to the method, the actual power capacity of each new energy inverter and the energy storage inverter is fully considered, the actual output power range of the PCC point is determined, and the inertia supporting capacity of the new energy plant station can be accurately determined; according to the network condition of the alternating current system, the active power range output by the new energy system and the energy storage system and the determined inertia parameters, the inertia support can be adapted to various different operation modes, the inertia support is efficiently and accurately output, and the adaptability of the inertia support is improved.

Description

Technical Field

[0001] The present invention relates to the field of new energy technology, and in particular to a method and system for optimizing the moment of inertia of a new energy plant. Background Art

[0002] With the proposal of the dual carbon goals, the development of large-scale new energy bases has accelerated, and countries around the world are committed to developing new energy represented by wind and solar. However, the output of wind turbines and photovoltaic units is largely affected by the weather, and there are large random fluctuations in their power output, which often leads to the phenomenon of "abandoning wind" and "abandoning solar" on the power generation side. Therefore, in order to avoid the occurrence of this phenomenon, it is necessary to conduct research on it, make it a high-quality frequency regulation resource, alleviate the frequency regulation pressure of traditional hydro-thermal power plants, and accelerate the dynamic response performance of system frequency regulation.

[0003] In recent years, in order to make new energy systems also have the characteristics of inertia and damping, scholars have found that virtual synchronous machine control can simulate the advantages of inertia and damping of traditional power systems. At the same time, it can realize multiple functions such as frequency regulation, voltage regulation, power distribution, etc., which greatly improves the stability of the system. At present, microgrid systems generally use multiple units in parallel to connect, but if the connection impedance and equivalent output impedance value between each VSG are different, there will be problems such as circulating reactive power and difficulty in sharing reactive power, which will reduce the stability of the system and damage the power electronic devices.

[0004] The biggest problem with inertia support for new energy plants is that it is impossible to effectively evaluate the inertia support capability of new energy plants and stations, and it is impossible to effectively coordinate with the AC system, resulting in no basis for inertia support calculation and control, and poor inertia implementation effects. Summary of the invention

[0005] (I) Purpose of the invention

[0006] The object of the present invention is to provide a method and system for optimizing the moment of inertia of a new energy power station, which can improve the implementation effect of the moment of inertia and the accuracy of the moment of inertia coefficient.

[0007] (II) Technical solution

[0008] To solve the above problems, the present invention provides a method for optimizing the moment of inertia of a new energy plant, wherein the new energy plant includes a new energy system, an energy storage system and an AC system, and the method includes:

[0009] Using a preset first algorithm, the total inertia support capacity of the new energy system and the energy storage system is evaluated to obtain the outputtable total active power range of the new energy system and the energy storage system;

[0010] Using a preset second algorithm, the inertia of the AC system is evaluated to obtain an evaluated inertia of the AC system;

[0011] The preset third algorithm is used to obtain the rotation inertia coefficient of the new energy plant according to the outputtable total active power range and the evaluated inertia of the AC system.

[0012] In another aspect of the present invention, preferably,

[0013] The new energy system includes a number of energy storage inverters;

[0014] The energy storage system includes a plurality of new energy inverters;

[0015] The energy storage inverter, the new energy inverter and the AC system exchange power at a common coupling point.

[0016] In another aspect of the present invention, preferably, the preset first algorithm calculates the outputtable total active power range using the following formula:

[0017] ΔP=P so +P o

[0018] Among them, ΔP represents the total output active power range, P so Represents the output power range of all energy storage inverters at the common coupling point, P o Indicates the output power range of all new energy inverters at the common coupling point.

[0019] In another aspect of the present invention, preferably, the output power range of all energy storage inverters at the common coupling point is calculated using the following formula:

[0020]

[0021] Among them, P so represents the output power range of all energy storage inverters at the common coupling point, n represents the number of the energy storage inverter, P sn represents the output power range of the nth energy storage inverter, x represents the number of branches from the nth energy storage inverter to the common coupling point, i represents the branch number from the nth energy storage inverter to the common coupling point, S i represents the capacity of the i-th branch, X i represents the impedance of the i-th branch, R i represents the resistance of the i-th branch, U s is the nominal voltage of the AC system.

[0022] In another aspect of the present invention, preferably, the output power range of all the new energy inverters at the common coupling point is calculated using the following formula:

[0023]

[0024] Among them, P o represents the output power range of all new energy inverters at the common coupling point, m represents the number of the new energy inverter, P m represents the output power range of the mth new energy inverter, y represents the number of branches from the mth new energy inverter to the common coupling point, j represents the branch number from the mth new energy inverter to the common coupling point, S j represents the capacity of the j-th branch, Y j represents the impedance of the jth branch, R j represents the resistance of the jth branch, U s is the nominal voltage of the AC system.

[0025] In another aspect of the present invention, preferably, the output power range of the nth energy storage inverter is expressed by the following formula:

[0026] P sn =[-P smaxn +P sqn ,P smaxn -P sqn ]

[0027] Among them, P sn Represents the output power range of the nth energy storage inverter, P smaxn Represents the maximum active power output by the nth energy storage inverter, P sqn It indicates the active power output by the nth energy storage inverter when inertia support is required.

[0028] In another aspect of the present invention, preferably, the output power range of the m-th new energy inverter is expressed by the following formula:

[0029] P m =[0,P maxm -P qm ]

[0030] Among them, P m represents the output power range of the mth new energy inverter, P maxm represents the maximum active power output of the mth new energy inverter, P qm It indicates the active power output by the mth new energy inverter when inertia support is required.

[0031] In another aspect of the present invention, preferably, the preset second algorithm calculates the estimated inertia of the AC system using the following formula:

[0032]

[0033] Where J represents the evaluation inertia of the AC system, P represents the total active power of the AC system, f represents the operating frequency of the AC system, and Δf represents the frequency change rate of the AC system.

[0034] In another aspect of the present invention, preferably, the preset third algorithm calculates the moment of inertia coefficient of the new energy plant using the following formula:

[0035]

[0036] Among them, J s represents the rotation inertia coefficient of the new energy plant, J represents the evaluation inertia of the AC system, ΔP represents the output active power range of the new energy system, P represents the total active power of the AC system, Δf represents the frequency change rate of the AC system, and Δf0 is the target frequency change rate.

[0037] In another aspect of the present invention, preferably, a rotation inertia optimization system based on a new energy plant, the new energy plant comprising a new energy system, an energy storage system and an AC system;

[0038] The optimization system comprises:

[0039] A new energy system inertia support capability evaluation module is used to evaluate the total inertia support capability of the new energy system and the energy storage system by using a preset first algorithm to obtain the outputtable total active power range of the new energy system and the energy storage system;

[0040] An inertia evaluation module for an AC system: using a preset second algorithm to evaluate the inertia of the AC system to obtain an evaluation inertia of the AC system;

[0041] Inertia coefficient calculation module: using the preset third algorithm, according to the output total active power range and the evaluated inertia of the AC system, the rotational inertia coefficient of the new energy plant is obtained.

[0042] (III) Beneficial effects

[0043] The above technical solution of the present invention has the following beneficial technical effects:

[0044] The present invention evaluates the inertia of the new energy system, energy storage system and AC system separately, and comprehensively considers the evaluation results of the two to calculate the moment of inertia coefficient of the new energy plant, which can more accurately reflect the dynamic response capability and stability of the entire system. This is of great significance for ensuring that the power grid can quickly restore stability when facing emergencies such as load fluctuations and failures, and reducing the risk of system oscillations and power outages. The present invention fully considers the actual power capacity of each new energy inverter and energy storage inverter, determines the actual output power range of the PCC point, and can accurately determine the inertia support capacity of the new energy plant; according to the AC system network conditions and the active power range output by the new energy system and energy storage system, the inertia parameters determined can adapt to various different operating modes, efficiently and accurately output inertia support, and improve the adaptability of inertia support. BRIEF DESCRIPTION OF THE DRAWINGS

[0045] Figure 1 An overall flow chart of an embodiment of the present invention is shown;

[0046] Figure 2 A schematic diagram of a new energy plant configuration according to an embodiment of the present invention is shown;

[0047] Figure 3 A schematic diagram of the connection structure of an energy storage inverter according to an embodiment of the present invention is shown. DETAILED DESCRIPTION

[0048] In order to make the purpose, technical scheme and advantages of the present invention clearer, the present invention is further described in detail below in conjunction with specific embodiments and with reference to the accompanying drawings. It should be understood that these descriptions are only exemplary and are not intended to limit the scope of the present invention. In addition, in the following description, the description of well-known structures and technologies is omitted to avoid unnecessary confusion of the concept of the present invention.

[0049] Obviously, the described embodiments are only some embodiments of the present invention, but not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0050] In addition, the technical features involved in the different embodiments of the present invention described below can be combined with each other as long as they do not conflict with each other.

[0051] The present invention will be described in more detail below with reference to the accompanying drawings. In each of the accompanying drawings, the same elements are represented by similar reference numerals. For the sake of clarity, the various parts in the accompanying drawings are not drawn to scale.

[0052] Embodiment 1

[0053] A method for optimizing the moment of inertia of new energy plants. Figure 1 FIG. 1 shows an overall flow chart of an embodiment of the present invention, as shown in FIG. Figure 1 As shown, including:

[0054] Figure 2 FIG. 1 shows a schematic diagram of a new energy plant configuration according to an embodiment of the present invention. Figure 2 As shown, the new energy plant includes a new energy system, an energy storage system and an AC system; the type and quantity of the new energy system are not limited here. The new energy system refers to a system that generates electricity using renewable energy (such as solar energy, wind energy, etc.); the new energy system is connected to the power grid through a new energy inverter; the energy storage system is used to store and release electrical energy to balance the supply and demand differences in the power grid. In the new energy plant, the energy storage system includes a battery energy storage system, a supercapacitor, etc. The AC system refers to the part of the traditional power grid connected to the new energy system and the energy storage system.

[0055] Using the preset first algorithm, the total inertia support capacity of the new energy system and the energy storage system is evaluated to obtain the total output active power range of the new energy system and the energy storage system; First, using the preset first algorithm, the inertia support capacity of new energy systems, such as wind power, photovoltaics, etc. and energy storage systems, such as battery energy storage, pumped storage, etc. is evaluated. The total output active power range of the new energy system and the energy storage system can be obtained through a comprehensive analysis of the physical characteristics, control strategies and operating status of each device in the system. This range reflects the inertia support capacity that the system can provide under different working conditions, that is, the system's ability to respond to changes in grid frequency and output or absorb active power.

[0056] The inertia of the AC system is evaluated by using a preset second algorithm to obtain an evaluated inertia of the AC system. The inertia of the AC system is evaluated by using a preset second algorithm. This may include analyzing the inertia characteristics of components such as generators and loads in the AC power grid, and considering the influence of factors such as the power grid structure and operation mode on the inertia. The evaluated inertia of the AC system is obtained; this inertia value reflects the stability and regulation capability of the AC system itself in response to changes in the power grid frequency.

[0057] Using the preset third algorithm, the rotation inertia coefficient of the new energy plant is obtained according to the output total active power range and the evaluated inertia of the AC system. This coefficient is an important indicator to measure the inertia support capability of the new energy plant in the power grid. This ensures that the new energy plant can provide appropriate inertia support under different working conditions.

[0058] Further, in this embodiment, the new energy system includes several energy storage inverters; the energy storage system includes several new energy inverters; the energy storage inverter, the new energy inverter and the AC system exchange power at a common coupling point. The energy storage inverter is mainly responsible for converting the DC power stored in the energy storage system (such as a battery pack, a supercapacitor, etc.) into AC power so as to exchange energy with the power grid or other AC loads. They also have the function of controlling the charging and discharging of the energy storage device, and can adjust the output power according to the needs of the power grid and the state of the energy storage system. In the new energy plant, the energy storage inverter can not only provide emergency backup power, but also respond quickly when the power grid frequency fluctuates, and stabilize the power grid frequency by charging and discharging. The new energy inverter is mainly responsible for converting the DC power generated by the new energy system (such as photovoltaic panels and wind turbines) into AC power and connecting it to the power grid. These inverters also have a maximum power point tracking (MPPT) function, which can automatically adjust the working point to maximize the power extracted from the new energy system. In addition, the new energy inverter also participates in the inertia support and frequency regulation of the power grid, responding to the needs of the power grid by controlling the output power. In a renewable energy plant, energy storage inverters, renewable energy inverters, and AC systems exchange power at the point of common coupling (PCC). PCC is the interface between renewable energy plants and the grid, which allows the power generated by renewable energy and energy storage systems to be injected into the grid, while also allowing the grid's power to flow back to renewable energy plants when needed. At the PCC, the inverter needs to precisely control its output power and current to ensure synchronous operation with the grid and stable power exchange. During the power exchange process, energy storage inverters and renewable energy inverters respond to the needs of the grid by adjusting their output power. When the grid frequency drops, they can increase their output power to provide additional inertia support; when the grid frequency rises, they can reduce their output power or absorb excess power in the grid. This rapid response capability is critical to maintaining the stability and reliability of the grid.

[0059] Further, in this embodiment, the preset first algorithm calculates the outputtable total active power range using the following formula:

[0060] ΔP=P so +P o

[0061] Among them, ΔP represents the total output active power range, P so Represents the output power range of all energy storage inverters at the common coupling point, P o Indicates the output power range of all new energy inverters at the common coupling point. The total output active power range is the superposition of the output power range of the energy storage inverter and the output power range of the new energy inverter. This is because both can provide active power support when the grid needs it.

[0062] Figure 3FIG. 1 shows a schematic diagram of a connection structure of an energy storage inverter according to an embodiment of the present invention. Figure 3 As shown, the output power range of all energy storage inverters at the common coupling point is calculated using the following formula:

[0063]

[0064] Among them, P so represents the output power range of all energy storage inverters at the common coupling point, n represents the number of the energy storage inverter, P sn represents the output power range of the nth energy storage inverter, x represents the number of branches from the nth energy storage inverter to the common coupling point, i represents the branch number from the nth energy storage inverter to the common coupling point, S i represents the capacity of the i-th branch, X i represents the impedance of the i-th branch, R i represents the resistance of the i-th branch, U s is the nominal voltage of the AC system. The output power range of the energy storage inverter is affected by multiple factors, including the number of energy storage inverters, the output power range of each inverter, and the characteristics of the branches from which they reach the PCC. Specifically, there may be multiple branches from each energy storage inverter to the PCC, and each branch has its capacity, impedance, and resistance. These factors together determine the power range that the energy storage inverter can actually output to the PCC.

[0065] The output power range of all new energy inverters at the common coupling point is calculated using the following formula:

[0066]

[0067] Among them, P o represents the output power range of all new energy inverters at the common coupling point, m represents the number of the new energy inverter, P m represents the output power range of the mth new energy inverter, y represents the number of branches from the mth new energy inverter to the common coupling point, j represents the branch number from the mth new energy inverter to the common coupling point, S j represents the capacity of the j-th branch, Y j represents the impedance of the jth branch, R j represents the resistance of the jth branch, U s is the nominal voltage of the AC system.

[0068] Furthermore, in this embodiment, the output power range of the nth energy storage inverter is expressed by the following formula:

[0069] P sn =[-P smaxn +P sqn ,Psmaxn -P sqn ]

[0070] Among them, P sn Represents the output power range of the nth energy storage inverter, P smaxn Represents the maximum active power output by the nth energy storage inverter, P sqn It indicates the active power output by the nth energy storage inverter when inertia support is required.

[0071] Furthermore, in this embodiment, the output power range of the mth new energy inverter is expressed by the following formula:

[0072] P m =[0,P maxm -P qm ]

[0073] Among them, P m represents the output power range of the mth new energy inverter, P maxm represents the maximum active power output of the mth new energy inverter, P qm It indicates the active power output by the mth new energy inverter when inertia support is required.

[0074] Furthermore, in this embodiment, the preset second algorithm calculates the evaluation inertia of the AC system using the following formula:

[0075]

[0076] Where J represents the estimated inertia of the AC system, P represents the total active power of the AC system, f represents the operating frequency of the AC system, and Δf represents the frequency change rate of the AC system. When a system fault occurs, the frequency begins to change. By detecting the change in frequency, the total inertia of the AC system can be determined in real time.

[0077] Furthermore, in this embodiment, the preset third algorithm calculates the moment of inertia coefficient of the new energy plant using the following formula:

[0078]

[0079] Among them, J s It represents the rotation inertia coefficient of the new energy plant, J represents the evaluation inertia of the AC system, ΔP represents the output active power range of the new energy system, P represents the total active power of the AC system, Δf represents the frequency change rate of the AC system, and Δf0 is the target frequency change rate. Δf0 can be set according to system requirements, and the typical value is 1Hz / min.

[0080] The present invention evaluates the inertia of the new energy system, energy storage system and AC system separately, and comprehensively considers the evaluation results of the two to calculate the moment of inertia coefficient of the new energy plant, which can more accurately reflect the dynamic response capability and stability of the entire system. This is of great significance for ensuring that the power grid can quickly restore stability when facing emergencies such as load fluctuations and failures, and reducing the risk of system oscillations and power outages. The present invention fully considers the actual power capacity of each new energy inverter and energy storage inverter, determines the actual output power range of the PCC point, and can accurately determine the inertia support capacity of the new energy plant; according to the AC system network conditions and the active power range output by the new energy system and energy storage system, the inertia parameters determined can adapt to various different operating modes, efficiently and accurately output inertia support, and improve the adaptability of inertia support.

[0081] Embodiment 2

[0082] A rotation inertia optimization system based on new energy plants.

[0083] The new energy plant station includes a new energy system, an energy storage system and an AC system;

[0084] The optimization system comprises:

[0085] A new energy system inertia support capability evaluation module is used to evaluate the total inertia support capability of the new energy system and the energy storage system by using a preset first algorithm to obtain the outputtable total active power range of the new energy system and the energy storage system;

[0086] An inertia evaluation module for an AC system: using a preset second algorithm to evaluate the inertia of the AC system to obtain an evaluation inertia of the AC system;

[0087] Inertia coefficient calculation module: using the preset third algorithm, according to the output total active power range and the evaluated inertia of the AC system, the rotational inertia coefficient of the new energy plant is obtained.

[0088] It should be understood that the above specific embodiments of the present invention are only used to illustrate or explain the principles of the present invention, and do not constitute a limitation of the present invention. Therefore, any modifications, equivalent substitutions, improvements, etc. made without departing from the spirit and scope of the present invention should be included in the protection scope of the present invention. In addition, the appended claims of the present invention are intended to cover all changes and modifications that fall within the scope and boundaries of the appended claims, or the equivalent forms of such scope and boundaries.

[0089] The present invention has been described above with reference to the embodiments of the present invention. However, these embodiments are for illustrative purposes only and are not intended to limit the scope of the present invention. The scope of the present invention is defined by the appended claims and their equivalents. Without departing from the scope of the present invention, a person skilled in the art may make various substitutions and modifications, which should all fall within the scope of the present invention.

[0090] Although the embodiments of the present invention have been described in detail, it should be understood that the various changes, substitutions, and alterations could be made hereto without departing from the spirit and scope of the invention.

[0091] Obviously, the above embodiments are merely examples for the purpose of clear explanation, and are not intended to limit the implementation methods. For those skilled in the art, other different forms of changes or modifications can be made based on the above description. It is not necessary and impossible to list all the implementation methods here. The obvious changes or modifications derived therefrom are still within the scope of protection of the invention.

Claims

1. A method for optimizing the moment of inertia of a new energy plant, characterized in that: The new energy plant station includes a new energy system, an energy storage system and an AC system, and the method includes: Using a preset first algorithm, the total inertia support capacity of the new energy system and the energy storage system is evaluated to obtain the outputtable total active power range of the new energy system and the energy storage system; Using a preset second algorithm, the inertia of the AC system is evaluated to obtain an evaluated inertia of the AC system; The preset third algorithm is used to obtain the rotation inertia coefficient of the new energy plant according to the outputtable total active power range and the evaluated inertia of the AC system.

2. The method according to claim 1, characterized in that: The new energy system includes a number of energy storage inverters; The energy storage system includes a plurality of new energy inverters; The energy storage inverter, the new energy inverter and the AC system exchange power at a common coupling point.

3. The method according to claim 2, characterized in that The preset first algorithm calculates the outputtable total active power range using the following formula: ΔP=P so +P o Among them, ΔP represents the total output active power range, P so Represents the output power range of all energy storage inverters at the common coupling point, P o Indicates the output power range of all new energy inverters at the common coupling point.

4. The method according to claim 3, characterized in that The output power range of all energy storage inverters at the common coupling point is calculated using the following formula: Among them, P so represents the output power range of all energy storage inverters at the common coupling point, n represents the number of the energy storage inverter, P sn represents the output power range of the nth energy storage inverter, x represents the number of branches from the nth energy storage inverter to the common coupling point, i represents the branch number from the nth energy storage inverter to the common coupling point, S i represents the capacity of the i-th branch, X i represents the impedance of the i-th branch, R i represents the resistance of the i-th branch, U s is the nominal voltage of the AC system.

5. The method according to claim 3, characterized in that: The output power range of all new energy inverters at the common coupling point is calculated using the following formula: Among them, P o represents the output power range of all new energy inverters at the common coupling point, m represents the number of the new energy inverter, P m represents the output power range of the mth new energy inverter, y represents the number of branches from the mth new energy inverter to the common coupling point, j represents the branch number from the mth new energy inverter to the common coupling point, S j represents the capacity of the j-th branch, Y j represents the impedance of the jth branch, R j represents the resistance of the jth branch, U s is the nominal voltage of the AC system.

6. The method according to claim 4, characterized in that The output power range of the nth energy storage inverter is expressed by the following formula: P sn =[-P smaxn +P sqn ,P smaxn -P sqn ] Among them, P sn Represents the output power range of the nth energy storage inverter, P smaxn Represents the maximum active power output by the nth energy storage inverter, P sqn It indicates the active power output by the nth energy storage inverter when inertia support is required.

7. The method according to claim 5, characterized in that The output power range of the mth new energy inverter is expressed by the following formula: P m =[0,P maxm -P qm ] Among them, P m represents the output power range of the mth new energy inverter, P maxm represents the maximum active power output of the mth new energy inverter, P qm It indicates the active power output by the mth new energy inverter when inertia support is required.

8. The method according to claim 7, characterized in that The preset second algorithm calculates the estimated inertia of the AC system using the following formula: Where J represents the evaluation inertia of the AC system, P represents the total active power of the AC system, f represents the operating frequency of the AC system, and Δf represents the frequency change rate of the AC system.

9. The method according to claim 8, characterized in that The preset third algorithm uses the following formula to calculate the moment of inertia coefficient of the new energy plant: Among them, J s represents the rotation inertia coefficient of the new energy plant, J represents the evaluation inertia of the AC system, ΔP represents the output active power range of the new energy system, P represents the total active power of the AC system, Δf represents the frequency change rate of the AC system, and Δf0 is the target frequency change rate.

10. A rotation inertia optimization system based on a new energy plant, characterized in that: The new energy plant station includes a new energy system, an energy storage system and an AC system; The optimization system comprises: A new energy system inertia support capability evaluation module is used to evaluate the total inertia support capability of the new energy system and the energy storage system by using a preset first algorithm to obtain the outputtable total active power range of the new energy system and the energy storage system; An inertia evaluation module for an AC system: using a preset second algorithm to evaluate the inertia of the AC system to obtain an evaluation inertia of the AC system; Inertia coefficient calculation module: using the preset third algorithm, according to the output total active power range and the evaluated inertia of the AC system, the rotational inertia coefficient of the new energy plant is obtained.

Images