An inertia support judgment method for an alternating current excited variable speed pumped storage unit

Abstract

The application discloses an inertia support judgment method for an alternating current excitation variable-speed pumped storage unit, and relates to the technical field of variable-speed pumped storage. The method comprises the following steps: determining a first relationship, a second relationship and a third relationship according to the actual grid frequency, the actual rotor speed and the actual active power, the rated grid frequency and the rated power, and the minimum and maximum rotor speed; judging whether the variable-speed pumped storage unit can provide inertia support based on the first relationship, the second relationship and the third relationship; and through a series of judgment logics, the boundary conditions for the variable-speed pumped storage unit to provide inertia support are determined, the safe and stable operation of the unit itself is ensured, and therefore, when the grid frequency suddenly changes, the instantaneous power support can be provided for the grid, so as to delay the frequency change rate and stabilize the grid frequency.

Description

Technical Field

[0001] This invention relates to the field of variable speed pumped storage technology, and in particular to a method for determining the inertia support of an AC-excited variable speed pumped storage unit. Background Technology

[0002] With the development and application of new energy technologies, building a new power system based on new energy sources is an inevitable trend in energy development. However, the high proportion of new energy grid connection greatly weakens the inertia and stability of the power system, resulting in more frequent and severe fluctuations in grid frequency and voltage. Pumped storage power stations are an important component of the power system. Variable-speed pumped storage units can convert the enormous kinetic energy of rotating bodies into a fast, adjustable, and stable resource, improving the dynamic response of the system frequency and gaining a time window for the initiation of primary frequency regulation. Furthermore, it overcomes the limitation of traditional synchronous machines in providing inertia support during power generation, achieving support under all operating conditions. This addresses the inertia deficiency and weak inertia characteristics of high-proportion new energy grids, thereby improving the power angle stability and frequency stability of the power system.

[0003] Variable-speed pumped storage units include full-power variable-speed pumped storage units and AC-excited variable-speed pumped storage units. Full-power variable-speed pumped storage units use synchronous motors with salient-pole rotors and DC excitation. The generator motor is directly connected to the grid via a full-power AC-DC-AC frequency converter of the same capacity. AC-excited variable-speed pumped storage units use doubly-fed induction motors with three-phase wound rotors and salient-pole rotors. They are connected to the grid via an AC excitation frequency converter. In contrast, pumped storage units using AC excitation technology not only achieve continuous adjustment of power and speed, quickly responding to the grid's peak-shaving and frequency regulation needs, but also have the ability to adapt to wider head conditions and achieve self-starting under pump operation.

[0004] Furthermore, AC-excited variable-speed pumped-storage units can provide inertial support, meaning that when the grid frequency changes abruptly, they can quickly release or absorb the kinetic energy stored in the rotor to provide instantaneous power support to the grid, thus slowing down the rate of frequency change and stabilizing the grid frequency. However, the inertial support capability of AC-excited variable-speed pumped-storage units has physical and safety limitations. Exceeding these limits will prevent the unit from providing effective support, or threaten its own safe and stable operation. Therefore, the inertial support boundary can be understood as a dynamic range consisting of the maximum instantaneous power support capability and the maximum total energy release that the unit can provide without jeopardizing its own safety under the current operating conditions (speed, power). This boundary is not fixed and changes in real time with the unit's operating point. Determining and strictly adhering to the inertial support boundary is the lifeline for ensuring the unit's own safety and effective grid support. Therefore, establishing a method for determining the inertial support boundary of AC-excited variable-speed pumped-storage units is of great significance. Summary of the Invention

[0005] In order to solve the problems existing in the prior art, the present invention provides the following technical solution.

[0006] The first aspect of this invention provides a method for determining the inertia support of an AC-excited variable-speed pumped storage unit, comprising: Obtain the actual power grid frequency f Actual rotor speed oh and actual active power P The value of the rated power grid frequency f 0 and rated power P The value of 0, and the minimum rotor speed. oh 1 and the maximum rotor speed oh 2; Determine the first, second, and third relationships; the first relationship is the relationship between the actual grid frequency and the rated grid frequency; the second relationship is the actual active power. P With rated power P The relationship between 0; the third relationship is the actual rotor speed. oh With the minimum rotor speed oh 1 and the maximum rotor speed oh The relationship between 2; Based on the first, second, and third relationships, determine whether a variable-speed pumped-storage unit can provide inertia support, including: like Then the variable-speed pumped-storage unit cannot provide inertia support; where Δ f 0 is the preset value Frequency dead zone threshold; Otherwise, determine whether the following conditions are met: or , If the conditions are met, the variable-speed pumped-storage unit can provide inertia support; if not, the variable-speed pumped-storage unit cannot provide inertia support.

[0007] Preferably, the variable-speed pumped-storage unit can provide inertia support including: like Then determine whether it satisfies If satisfied, then determine whether the condition is satisfied. If this condition is met, the variable-speed pumped-storage unit can provide inertia support. like Then determine whether it satisfies If satisfied, then determine whether the condition is satisfied. If this condition is met, the variable-speed pumped-storage unit can provide inertia support.

[0008] Preferably, the determination method further includes: if the variable-speed pumped-storage unit can provide inertial support, the provided inertial support power is calculated according to the following formula: in, P iner For inertial support power, J This refers to the rotational inertia of the rotor of the variable speed pumped storage unit. Rocof For the rate of change of power grid frequency, Rocof 0 represents the dead zone threshold for the rate of change of frequency.

[0009] Preferably, the determination method further includes: if the variable-speed pumped-storage unit can provide inertial support, the provided inertial support power is calculated according to the following formula: in, P iner For inertial support power, J This refers to the rotational inertia of the rotor of the variable speed pumped storage unit. Rocof For the rate of change of power grid frequency, Rocof 0 represents the dead zone threshold for the rate of change of frequency.

[0010] Preferably, the rate of change of the power grid frequency is calculated according to the following formula: Where, δ( k ) for in k The change in frequency at any given time d ( k -1) is in k The frequency change at time -1 T The sampling period.

[0011] A second aspect of the present invention provides an inertia support judgment device for an AC-excited variable-speed pumped storage unit, comprising: The data acquisition module is used to acquire the actual power grid frequency. f Actual rotor speed oh and actual active power P The value of the rated power grid frequency f 0 and rated power P The value of 0, and the minimum rotor speed. oh 1 and the maximum rotor speed oh 2; The relationship determination module is used for the first relationship, the second relationship, and the third relationship; the first relationship is the relationship between the actual grid frequency and the rated grid frequency; the second relationship is the actual active power. P With rated power P The relationship between 0; the third relationship is the actual rotor speed. oh With the minimum rotor speed oh 1 and the maximum rotor speed oh The relationship between 2; The judgment module is used to determine whether the variable-speed pumped-storage unit can provide inertia support based on the first, second, and third relationships, including: like Then the variable-speed pumped-storage unit cannot provide inertia support; where Δ f 0 is the preset value Frequency dead zone threshold; Otherwise, determine whether the following conditions are met: or , If the conditions are met, the variable-speed pumped-storage unit can provide inertia support; if not, the variable-speed pumped-storage unit cannot provide inertia support.

[0012] Preferably, the judgment module uses the following method to determine whether the variable-speed pumped-storage unit can provide inertia support: like Then determine whether it satisfies If satisfied, then determine whether the condition is satisfied. If this condition is met, the variable-speed pumped-storage unit can provide inertia support. like Then determine whether it satisfies If satisfied, then determine whether the condition is satisfied. If this condition is met, the variable-speed pumped-storage unit can provide inertia support.

[0013] Preferably, the determining device further includes a first calculation module, used to calculate the provided inertial support power according to the following formula if the variable-speed pumped-storage unit can provide inertial support: in, P iner For inertial support power, J This refers to the rotational inertia of the rotor of the variable speed pumped storage unit. Rocof For the rate of change of power grid frequency, Rocof 0 represents the dead zone threshold for the rate of change of frequency.

[0014] Preferably, the determining device further includes a second calculation module, used to calculate the provided inertial support power according to the following formula if the variable-speed pumped-storage unit can provide inertial support: in, P iner For inertial support power, J This refers to the rotational inertia of the rotor of the variable speed pumped storage unit. Rocof For the rate of change of power grid frequency, Rocof 0 represents the dead zone threshold for the rate of change of frequency.

[0015] Preferably, the first calculation module or the second calculation module calculates the power grid frequency change rate according to the following formula: Where, δ( k ) for in k The change in frequency at any given time d ( k -1) is in k The frequency change at time -1 T The sampling period.

[0016] The beneficial effects of the present invention are as follows: The inertia support judgment method of the AC excitation variable speed pumped storage unit provided by the present invention clarifies the boundary conditions for the variable speed pumped storage unit to provide inertia support through a series of judgment logics, ensuring the safe and stable operation of the unit itself, thereby ensuring that instantaneous power support is provided to the power grid when the grid frequency changes abruptly, so as to delay the rate of frequency change and stabilize the grid frequency. Attached Figure Description

[0017] Figure 1 This is a flowchart illustrating the inertia support judgment method for AC-excited variable-speed pumped storage units described in this invention. Figure 2 This is a schematic diagram of the inertia support judgment process of the AC excitation variable speed pumped storage unit described in this invention; Figure 3 This is a functional structural diagram of the inertia support judgment device for the AC excitation variable speed pumped storage unit described in this invention. Detailed Implementation

[0018] To better understand the above technical solutions, the following will provide a detailed explanation of the technical solutions in conjunction with the accompanying drawings and specific implementation methods.

[0019] The method provided by this invention can be implemented in a terminal environment that may include one or more of the following components: a processor, a memory, and a display screen. The memory stores at least one instruction, which is loaded and executed by the processor to implement the method described in the following embodiments.

[0020] A processor may include one or more processing cores. The processor uses various interfaces and lines to connect various parts of the terminal, and performs various functions and processes data by running or executing instructions, programs, code sets or instruction sets stored in memory, and by calling data stored in memory.

[0021] Memory can include random access memory (RAM) or read-only memory (ROM). Memory can be used to store instructions, programs, code, code sets, or instructions.

[0022] The display screen is used to show the user interface of each application.

[0023] In addition, those skilled in the art will understand that the structure of the terminal described above does not constitute a limitation on the terminal. The terminal may include more or fewer components, or combine certain components, or have different component arrangements. For example, the terminal may also include radio frequency circuits, input units, sensors, audio circuits, power supplies, and other components, which will not be described in detail here.

[0024] Example 1 like Figure 1 As shown in the figure, this embodiment of the invention provides a method for determining the inertia support of an AC-excited variable-speed pumped storage unit, which may include the following steps: S101, Obtain the actual power grid frequency f Actual rotor speed oh and actual active power P The value of the rated power grid frequency f 0. Rated power P The value of 0, and the minimum rotor speed. oh 1 and the maximum rotor speed oh 2. Among them, the actual power grid frequency f Actual rotor speed oh and actual active power P The value can be obtained through testing. Rated grid frequency. f 0. Rated power P The value of 0 can be preset. In some specific embodiments, the rotor speed of the variable-speed pumped storage unit is adjustable within the range of -7.5% to +7.5%, and to ensure the stable operation of the pump turbine under pumping conditions, the minimum safe speed can be determined using the following formula. oh 1: in, oh 0 is the rated speed of the rotor. Q For traffic, A , B , C For the head-flow characteristic curve H = Oh 2 + BωQ + CQ 2 The constant, lThis is the friction coefficient. v The average velocity of the fluid. L For the length of the pipeline, D For the pipe diameter, g It is the acceleration due to gravity. oh This is the actual rotor speed. ΔH This represents the difference in water levels between the upper and lower reservoirs.

[0025] The maximum rotor speed can be determined using the following formula. oh 2: .

[0026] S102, determine the first relationship, the second relationship, and the third relationship; the first relationship is the relationship between the actual grid frequency and the rated grid frequency; the second relationship is the actual active power... P With rated power P The relationship between 0; the third relationship is the actual rotor speed. oh With the minimum rotor speed oh 1 and the maximum rotor speed oh The relationship between 2.

[0027] The first relationship generally includes the following cases: Actual power grid frequency f Less than the rated power grid frequency f 0, or actual power grid frequency f Greater than the rated power grid frequency f 0. or .

[0028] Second and third relationships generally include the following situations: Actual active power P Less than the rated active power P At 0, the actual rotor speed oh Greater than or equal to the minimum rotor speed oh 1 and less than the maximum rotor speed oh 2, or the actual rotor speed oh Equal to the maximum rotor speed oh 2, or the actual rotor speed oh Greater than the minimum rotor speed oh 1 and less than or equal to the maximum rotor speed oh 2, or the actual rotor speed oh Equal to the minimum rotor speed oh 1; Actual active power P Greater than or equal to rated active power P At 0, the actual rotor speed oh Greater than or equal to the minimum rotor speed oh1 and less than the maximum rotor speed oh 2, or the actual rotor speed oh Equal to the maximum rotor speed oh 2, or the actual rotor speed oh Equal to the minimum rotor speed oh 1, or the actual rotor speed oh Equal to the minimum rotor speed oh 1.

[0029] S103, based on the first, second, and third relationships, determines whether the variable-speed pumped-storage unit can provide inertia support, including: like Then the variable-speed pumped-storage unit cannot provide inertia support; where Δ f 0 is the preset value Frequency dead zone threshold; Otherwise, determine whether the following conditions are met: or , If the conditions are met, the variable-speed pumped-storage unit can provide inertia support; if not, the variable-speed pumped-storage unit cannot provide inertia support.

[0030] Understandably, only when the following conditions are met: or One of the conditions is that only variable-speed pumped-storage units can provide inertia support. Otherwise, variable-speed pumped-storage units cannot provide inertia support.

[0031] In one embodiment of the present invention, such as Figure 2 As shown, the following method is used to determine whether a variable-speed pumped-storage unit can provide inertia support: like Then determine whether it satisfies If satisfied, then determine whether the condition is satisfied. If this condition is met, the variable-speed pumped-storage unit can provide inertia support. like Then determine whether it satisfies If satisfied, then determine whether the condition is satisfied. If this condition is met, the variable-speed pumped-storage unit can provide inertia support.

[0032] When determining the conditions under which a variable-speed pumped-storage unit can provide inertia support, we can first determine the first relationship, then, based on the first relationship, determine the second relationship. Next, based on the second relationship, determine the third relationship. Finally, we obtain the conditions under which the variable-speed pumped-storage unit can provide inertia support. Among these, At that time, the unit was not at full load.

[0033] Specifically, if Then determine whether it satisfies If not satisfied If so, the variable-speed pumped-storage unit cannot provide inertia support. If the following conditions are met... Then determine whether it satisfies If not satisfied If so, the variable-speed pumped-storage unit cannot provide inertia support. If the following conditions are met... Then, the variable speed pumped storage unit can provide inertia support.

[0034] like Then determine whether it satisfies If not satisfied If so, the variable-speed pumped-storage unit cannot provide inertia support. If the following conditions are met... Then determine whether it satisfies If not satisfied If so, the variable-speed pumped-storage unit cannot provide inertia support. If the following conditions are met... Then, the variable speed pumped storage unit can provide inertia support.

[0035] In one embodiment of the present invention, the determination method may further include: if the variable-speed pumped-storage unit can provide inertial support, the provided inertial support power is calculated according to the following formula: in, P iner For inertial support power, J This refers to the rotational inertia of the rotor of the variable speed pumped storage unit. Rocof For the rate of change of power grid frequency, Rocof 0 represents the dead zone threshold for the rate of change of frequency.

[0036] In another embodiment of the present invention, the determination method further includes: if the variable-speed pumped-storage unit can provide inertial support, the provided inertial support power is calculated according to the following formula: in, P iner For inertial support power, J This refers to the rotational inertia of the rotor of the variable speed pumped storage unit. Rocof For the rate of change of power grid frequency, Rocof 0 represents the dead zone threshold for the rate of change of frequency.

[0037] Specifically, if the following conditions are met: or If the variable-speed pumped-storage unit can provide inertia support, then based on this, the relationship between the grid frequency change rate and the frequency change rate dead zone threshold can be determined. ,but .otherwise, .

[0038] In one embodiment of the present invention, the power grid frequency change rate can be calculated according to the following formula: Where, δ( k ) for in k The change in frequency at any given time d ( k -1) is in k The frequency change at time -1 T The sampling period is defined as the frequency change and the rate of frequency change of the system frequency signal after passing through the high-pass filter, assuming a constant sampling period. Rocof One-to-one correspondence, the sampling period is generally taken as T =0.1. Preset frequency dead zone threshold Δ f 0 needs to be moderate. Too small a value will cause the unit to make unnecessary and frequent adjustments to small random fluctuations, accelerating the wear and tear on mechanical parts. Too large a value will cause the frequency to fluctuate within a wide range for a long time, which is not conducive to the stable operation of equipment and the power grid. Generally, Δ is chosen. f 0 = 0.03Hz.

[0039] Example 2 like Figure 3 As shown, another aspect of the present invention also includes a functional module architecture that is completely consistent with the aforementioned method flow. That is, the embodiments of the present invention also provide an inertia support judgment device for an AC excitation variable speed pumped storage unit, including: Data acquisition module 301 is used to acquire the actual power grid frequency. f Actual rotor speed oh and actual active power P The value of the rated power grid frequency f 0 and rated power P The value of 0, and the minimum rotor speed. oh 1 and the maximum rotor speed oh 2; The relationship determination module 302 is used for a first relationship, a second relationship, and a third relationship; the first relationship is the relationship between the actual grid frequency and the rated grid frequency; the second relationship is the actual active power. P With rated power P The relationship between 0; the third relationship is the actual rotor speed. oh With the minimum rotor speed oh 1 and the maximum rotor speed oh The relationship between 2; The judgment module 303 is used to determine whether the variable-speed pumped-storage unit can provide inertia support based on the first relationship, the second relationship, and the third relationship, including: like Then the variable-speed pumped-storage unit cannot provide inertia support; where Δf 0 is the preset value Frequency dead zone threshold; Otherwise, determine whether the following conditions are met: or , If the conditions are met, the variable-speed pumped-storage unit can provide inertia support; if not, the variable-speed pumped-storage unit cannot provide inertia support.

[0040] Furthermore, the judgment module uses the following method to determine whether the variable-speed pumped-storage unit can provide inertia support: like Then determine whether it satisfies If satisfied, then determine whether the condition is satisfied. If this condition is met, the variable-speed pumped-storage unit can provide inertia support. like Then determine whether it satisfies If satisfied, then determine whether the condition is satisfied. If this condition is met, the variable-speed pumped-storage unit can provide inertia support.

[0041] Furthermore, the determining device also includes a first calculation module, used to calculate the provided inertial support power according to the following formula if the variable-speed pumped-storage unit can provide inertial support: in, P iner For inertial support power, J This refers to the rotational inertia of the rotor of the variable speed pumped storage unit. Rocof For the rate of change of power grid frequency, Rocof 0 represents the dead zone threshold for the rate of change of frequency.

[0042] Furthermore, the determining device also includes a second calculation module, used to calculate the provided inertial support power according to the following formula if the variable-speed pumped-storage unit can provide inertial support: in, P iner For inertial support power, J This refers to the rotational inertia of the rotor of the variable speed pumped storage unit. Rocof For the rate of change of power grid frequency, Rocof 0 represents the dead zone threshold for the rate of change of frequency.

[0043] Furthermore, the first calculation module or the second calculation module calculates the power grid frequency change rate according to the following formula: Where, δ( k ) for in k The change in frequency at any given time d ( k -1) is in k The frequency change at time -1 T The sampling period.

[0044] This device can be implemented using the inertia support judgment method for AC excitation variable speed pumped storage units provided in Embodiment 1 above. For the specific implementation method, please refer to the description in Embodiment 1, which will not be repeated here.

[0045] Although preferred embodiments of the invention have been described, those skilled in the art, upon learning the basic inventive concept, can make other changes and modifications to these embodiments. Therefore, the appended claims are intended to be interpreted as including both the preferred embodiments and all changes and modifications falling within the scope of the invention. Clearly, those skilled in the art can make various alterations and modifications to the invention without departing from its spirit and scope. Thus, if these modifications and modifications of the invention fall within the scope of the claims and their equivalents, the invention is also intended to include these modifications and modifications.

Claims

1. A method for determining the inertia support of an AC-excited variable-speed pumped-storage unit, characterized in that, include: Obtain the actual power grid frequency f Actual rotor speed ω and actual active power P The value of the rated power grid frequency f 0 and rated power P The value of 0, and the minimum rotor speed. ω 1 and the maximum rotor speed ω 2; Determine the first relationship, the second relationship, and the third relationship; the first relationship is the relationship between the actual power grid frequency and the rated power grid frequency. The second relationship is the actual active power. P With rated power P The relationship between 0; The third relationship is the actual rotor speed. ω With the minimum rotor speed ω 1 and the maximum rotor speed ω The relationship between 2; Based on the first, second, and third relationships, determine whether a variable-speed pumped-storage unit can provide inertia support, including: like Then the variable-speed pumped-storage unit cannot provide inertia support; where Δ f 0 is the preset value Frequency dead zone threshold; Otherwise, determine whether the following conditions are met: or , If the conditions are met, the variable-speed pumped-storage unit can provide inertia support; if the conditions are not met, the variable-speed pumped-storage unit cannot provide inertia support. The following method is used to determine whether a variable-speed pumped-storage unit can provide inertia support: like Then determine whether it satisfies If satisfied, then determine whether the condition is satisfied. If this condition is met, the variable-speed pumped-storage unit can provide inertia support. like Then determine whether it satisfies If satisfied, then determine whether the condition is satisfied. If this condition is met, the variable-speed pumped-storage unit can provide inertia support.

2. The inertia support determination method according to claim 1, characterized in that, The judgment method further includes: if the variable-speed pumped-storage unit can provide inertial support, the power of the provided inertial support is calculated according to the following formula: in, P iner For inertial support power, J This refers to the rotational inertia of the rotor of the variable speed pumped storage unit. Rocof For the rate of change of power grid frequency, Rocof 0 represents the dead zone threshold for the rate of change of frequency.

3. The inertia support determination method according to claim 1, characterized in that, The judgment method further includes: if the variable-speed pumped-storage unit can provide inertial support, the power of the provided inertial support is calculated according to the following formula: in, P iner For inertial support power, J This refers to the rotational inertia of the rotor of the variable-speed pumped-storage unit. Rocof For the rate of change of power grid frequency, Rocof 0 represents the dead zone threshold for the rate of change of frequency.

4. The inertia support determination method according to claim 2 or 3, characterized in that, The rate of change of the power grid frequency is calculated according to the following formula: Where, δ( k ) for in k The change in frequency at any given time δ ( k -1) is in k The frequency change at time -1 T The sampling period.

5. An inertia support judgment device for an AC-excited variable-speed pumped storage unit, characterized in that, include: The data acquisition module is used to acquire the actual power grid frequency. f Actual rotor speed ω and actual active power P The value of the rated power grid frequency f 0 and rated power P The value of 0, and the minimum rotor speed. ω 1 and the maximum rotor speed ω 2; The relationship determination module is used for the first relationship, the second relationship, and the third relationship; the first relationship is the relationship between the actual power grid frequency and the rated power grid frequency. The second relationship is the actual active power. P With rated power P The relationship between 0; The third relationship is the actual rotor speed. ω With the minimum rotor speed ω 1 and the maximum rotor speed ω The relationship between 2; The judgment module is used to determine whether the variable-speed pumped-storage unit can provide inertia support based on the first, second, and third relationships, including: like Then the variable-speed pumped-storage unit cannot provide inertia support; where Δ f 0 is the preset value Frequency dead zone threshold; Otherwise, determine whether the following conditions are met: or , If the conditions are met, the variable-speed pumped-storage unit can provide inertia support; if the conditions are not met, the variable-speed pumped-storage unit cannot provide inertia support. The judgment module uses the following method to determine whether the variable-speed pumped-storage unit can provide inertia support: like Then determine whether it satisfies If satisfied, then determine whether the condition is satisfied. If this condition is met, the variable-speed pumped-storage unit can provide inertia support. like Then determine whether it satisfies If satisfied, then determine whether the condition is satisfied. If this condition is met, the variable-speed pumped-storage unit can provide inertia support.

6. The inertia support judgment device according to claim 5, characterized in that, The determining device further includes a first calculation module, used to calculate the provided inertial support power according to the following formula if the variable-speed pumped-storage unit can provide inertial support: in, P iner For inertial support power, J This refers to the rotational inertia of the rotor of the variable speed pumped storage unit. Rocof For the rate of change of power grid frequency, Rocof 0 represents the dead zone threshold for the rate of change of frequency.

7. The inertia support judgment device according to claim 5, characterized in that, The judgment device further includes a second calculation module, used to calculate the provided inertial support power according to the following formula if the variable-speed pumped-storage unit can provide inertial support: in, P iner For inertial support power, J This refers to the rotational inertia of the rotor of the variable speed pumped storage unit. Rocof For the rate of change of power grid frequency, Rocof 0 represents the dead zone threshold for the rate of change of frequency.

8. The inertia support determination device according to claim 6 or 7, characterized in that, The first calculation module or the second calculation module calculates the power grid frequency change rate according to the following formula: Where, δ( k ) for in k The change in frequency at any given time δ ( k -1) is in k The frequency change at time -1 T The sampling period.

Images