A method and device for calculating an optimal release strategy of energy storage emergency control

Abstract

The application discloses a kind of energy storage emergency control optimal release strategy calculation methods, comprising: collecting power grid operation mode data, and according to the operation condition of actual accident occurrence of power grid adjustment power grid simulation data, determine the new energy low wear interference curve after single power grid failure, obtain the target data of new energy into low voltage ride through;Based on target data, combined with the power of energy storage emergency control and the short-time impact power of new energy low wear process to build power system frequency response model, and the time domain model corresponding to power system frequency is obtained by using power system frequency response model;The energy storage emergency control release strategy is obtained by calculating time domain model;Energy storage emergency control release strategy includes energy storage release power and energy storage duration release time.The application can effectively solve the known condition of energy storage releasable energy, effectively control new energy low voltage ride through, expand the emergency control method of energy storage participation in power system.

Description

Technical Field

[0001] This invention relates to the technical field of power systems and their automation, and in particular to a method and apparatus for calculating the optimal release strategy for emergency control of energy storage. Background Technology

[0002] In recent years, the high proportion of renewable energy in new power systems has squeezed the generation space of conventional power sources, resulting in a decrease in grid rotational inertia and frequency regulation capabilities. Transient frequency security has become a bottleneck restricting the development of new power systems. Low-frequency problems threatening the stable operation of the grid in new power systems are not limited to faults such as wind power disconnection and DC blocking that cause active power step disturbances. For new power systems with an increasing proportion of renewable energy, rapid frequency changes will also occur after being subjected to short-term power surges such as low-voltage ride-throughs from renewable energy sources. The system frequency may have already breached the defenses before frequency regulation measures can take effect.

[0003] Current research indicates that the impact of wind turbine low-voltage ride-through caused by grid faults on frequency may be more severe than that of large turbine tripping. If low-frequency triggers wind turbine speed change rate protection and the grid's low-frequency defense line, the impact will be even more serious. Furthermore, a single grid fault can also lead to a large-scale risk of new energy sources entering low-voltage ride-through, thereby threatening grid frequency security. Summary of the Invention

[0004] The purpose of this section is to outline some aspects of embodiments of the present invention and to briefly describe some preferred embodiments. Simplifications or omissions may be made in this section, as well as in the abstract and title of this application, to avoid obscuring the purpose of these documents; however, such simplifications or omissions should not be construed as limiting the scope of the invention.

[0005] In view of the aforementioned existing problems, the present invention is proposed.

[0006] Therefore, this invention provides a method and apparatus for calculating the optimal release strategy for emergency control of energy storage to address the problem that a large area of ​​new energy sources enters the low-voltage ride-through due to a single short-circuit fault in the power system, causing a short-term power surge and the risk of excessively deep drops in transient frequency.

[0007] To solve the above-mentioned technical problems, the present invention provides the following technical solution:

[0008] In a first aspect, embodiments of the present invention provide a method for calculating the optimal release strategy for emergency control of energy storage, including: collecting grid operation mode data, adjusting grid simulation data according to the actual operating conditions of the grid when an actual accident occurs, determining the low voltage ride-through disturbance curve of new energy after a single grid fault occurs, and obtaining target data for new energy to enter low voltage ride-through.

[0009] Based on the target data, a power system frequency response model is constructed by combining the emergency control power of energy storage and the short-term impact power of new energy low-voltage process, and the time domain model corresponding to the power system frequency is obtained by using the power system frequency response model.

[0010] An emergency control release strategy for energy storage is obtained by calculating the time-domain model; the emergency control release strategy for energy storage includes the energy release power and the continuous release time of energy storage.

[0011] As a preferred embodiment of the energy storage emergency control optimal release strategy calculation method described in this invention, the energy storage emergency control release strategy obtained by calculating the time-domain model includes:

[0012] If the frequency deviation of the system at the first moment is not greater than 0, and the rate of change of the frequency at the second moment is greater than 0, the system frequency response curve has two minimum points.

[0013] When the energy that can be released from the energy storage meets the first threshold and the two minimum points are equal, the optimal control release strategy for the energy storage release power and the energy storage continuous release time is implemented.

[0014] When the optimal control strategy is released, the energy storage release power is greater than 0 and not greater than the rated energy storage release power; the energy storage continuous release time is greater than 0 and less than the low voltage ride-through recovery time.

[0015] As a preferred embodiment of the energy storage emergency control optimal release strategy calculation method described in this invention, it further includes: a single-objective optimization function for the energy storage emergency control release strategy, expressed as:

[0016]

[0017] Among them, P s To store energy and release power, P sN t1 is the rated release power of the energy storage, t2 is the low voltage ride-through time, t3 is the low voltage ride-through recovery time, C is the total energy that can be released from the energy storage, and ω is the total energy that can be released from the energy storage. B1 Let ω be the value at the first minimum point. B2 Let ω be the value at the second minimum point, t be time, and Δω(t1+t3) be the frequency deviation at time (t1+t3).

[0018] As a preferred embodiment of the energy storage emergency control optimal release strategy calculation method described in this invention, the power system frequency response model is expressed as:

[0019]

[0020] Where s is the Laplace operator, ΔG(s) is the system's frequency-active transfer function, M is the rotor time constant related to the moment of inertia, L is the load's active frequency response coefficient, and P... s P represents the power released from energy storage, P represents the active power deficit of new energy sources during low voltage ride-through, t1 represents the low voltage ride-through time, t2 represents the low voltage ride-through recovery time, and t3 represents the duration of energy storage release.

[0021] As a preferred embodiment of the energy storage emergency control optimal release strategy calculation method described in this invention, the time-domain model corresponding to the power system frequency obtained through inverse Laplace transform is expressed as follows:

[0022]

[0023] As a preferred embodiment of the energy storage emergency control optimal release strategy calculation method described in this invention, the time of the first minimum point is expressed as:

[0024]

[0025] Where, k = L / M;

[0026] The value of the first minimum point is expressed as:

[0027]

[0028] The time representation of the second minimum point is:

[0029]

[0030] The value of the second minimum point is expressed as:

[0031]

[0032] As a preferred embodiment of the energy storage emergency control optimal release strategy calculation method described in this invention, the target data for obtaining new energy sources entering low voltage ride-through includes: the active power deficit of new energy sources entering low voltage ride-through, the low voltage ride-through time, and the low voltage ride-through recovery time.

[0033] Secondly, the present invention provides a calculation device for an optimal release strategy for emergency control of energy storage, comprising,

[0034] The fault information confirmation module is used to collect power grid operation mode data, adjust power grid simulation data according to the actual operating conditions of the power grid when a fault occurs, determine the low voltage ride-through disturbance curve of new energy after a single power grid fault occurs, and obtain the target data for new energy to enter low voltage ride-through.

[0035] The model building module is used to construct a power system frequency response model based on the target data, combined with the emergency control power of energy storage and the short-term impact power of the low-voltage process of new energy, and to obtain the time domain model corresponding to the power system frequency using the power system frequency response model.

[0036] The strategy calculation module is used to obtain the energy storage emergency control release strategy by calculating the time domain model; the energy storage emergency control release strategy includes the energy storage release power and the energy storage continuous release time.

[0037] Thirdly, the present invention provides a computing device, comprising:

[0038] Memory and processor;

[0039] The memory is used to store computer-executable instructions, and the processor is used to execute the computer-executable instructions. When the computer-executable instructions are executed by the processor, the steps of the energy storage emergency control optimal release strategy calculation method are implemented.

[0040] Fourthly, the present invention provides a computer-readable storage medium storing computer-executable instructions that, when executed by a processor, implement the steps of the energy storage emergency control optimal release strategy calculation method.

[0041] Compared with the prior art, the beneficial effects of the present invention are as follows: The present invention addresses the risk in new power systems where a single short-circuit fault can cause a large area of ​​new energy sources to enter low-voltage ride-through, resulting in a short-term power surge and a significant drop in transient frequency. It proposes a simplified analysis method, deriving a time-domain expression for the system frequency characteristics under the superposition of emergency control power from energy storage and the short-term surge power generated by new energy low-voltage ride-through. Based on this time-domain expression, the number, timing, and values ​​of the minimum points on the system frequency response curve are calculated, providing a basis for subsequent strategy development.

[0042] A single-objective optimization function was developed to address risk issues. Under the condition that the energy storage release capacity is confirmed, an emergency control strategy for energy storage with good control effect on transient frequency drops of the system can be calculated. A reliable calculation model is provided for online and offline safety and stability calculations. It can provide effective solutions for risk issues and support the formulation of corresponding frequency emergency control measures for large power grids. Attached Figure Description

[0043] To more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings used in the following description of the embodiments will be briefly introduced. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort. Wherein:

[0044] Figure 1 This is a flowchart illustrating a method and apparatus for calculating the optimal release strategy for emergency control of energy storage according to an embodiment of the present invention.

[0045] Figure 2 This is a system frequency response curve before the energy storage participates in control, according to an embodiment of the energy storage emergency control optimal release strategy calculation method and device of the present invention.

[0046] Figure 3 This is a system frequency response curve after energy storage participates in control, according to an embodiment of the energy storage emergency control optimal release strategy calculation method and device described in this invention.

[0047] Figure 4 The figure shows the verification results of a method and device for calculating the optimal release strategy for emergency control of energy storage according to an embodiment of the present invention. Detailed Implementation

[0048] To make the above-mentioned objects, features, and advantages of the present invention more apparent and understandable, specific embodiments of the present invention will be described in detail below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of the present invention, and not all of them. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort should fall within the protection scope of the present invention.

[0049] Many specific details are set forth in the following description in order to provide a full understanding of the invention. However, the invention may also be practiced in other ways different from those described herein, and those skilled in the art can make similar extensions without departing from the spirit of the invention. Therefore, the invention is not limited to the specific embodiments disclosed below.

[0050] Secondly, the term "one embodiment" or "embodiment" as used herein refers to a specific feature, structure, or characteristic that may be included in at least one implementation of the present invention. The phrase "in one embodiment" appearing in different places in this specification does not necessarily refer to the same embodiment, nor is it a single or selective embodiment that is mutually exclusive with other embodiments.

[0051] This invention is described in detail with reference to the schematic diagrams. When detailing the embodiments of this invention, for ease of explanation, the cross-sectional views illustrating the device structure may be partially enlarged, not adhering to the usual scale. Furthermore, the schematic diagrams are merely examples and should not be construed as limiting the scope of protection of this invention. In actual fabrication, the three-dimensional spatial dimensions of length, width, and depth should be included.

[0052] Furthermore, in the description of this invention, it should be noted that the terms "upper," "lower," "inner," and "outer," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. These terms are used solely for the convenience of describing the invention and for simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on the invention. In addition, the terms "first," "second," or "third" are used for descriptive purposes only and should not be construed as indicating or implying relative importance.

[0053] Unless otherwise explicitly specified and limited, the terms "installation," "connection," and "joining" in this invention should be interpreted broadly. For example, they can refer to fixed connections, detachable connections, or integral connections; similarly, they can refer to mechanical connections, electrical connections, or direct connections, or indirect connections through an intermediate medium, or internal connections between two components. Those skilled in the art can understand the specific meaning of the above terms in this invention based on the specific circumstances.

[0054] Example 1

[0055] Reference Figure 1 As one embodiment of the present invention, this embodiment provides a method for calculating the optimal release strategy for emergency control of energy storage, including:

[0056] S1: Collect power grid operation mode data, adjust power grid simulation data according to the actual operating conditions when a power grid accident occurs, determine the low voltage ride-through disturbance curve of new energy after a single power grid fault occurs, and obtain the target data for new energy to enter low voltage ride-through.

[0057] Furthermore, the power grid simulation data includes power flow files and stability files. The stability files include load models related to frequency simulation, as well as models and parameters of various components.

[0058] Furthermore, the target data for obtaining new energy sources to enter low voltage ride-through include: the active power deficit of new energy sources entering low voltage ride-through, the low voltage ride-through time, and the low voltage ride-through recovery time.

[0059] S2: Based on the target data, a power system frequency response model is constructed by combining the emergency control power of energy storage and the short-term impact power of new energy low-voltage process, and the time domain model corresponding to the power system frequency is obtained by using the power system frequency response model.

[0060] Furthermore, the power system frequency response model can be expressed as:

[0061]

[0062] Where s is the Laplace operator, ΔG(s) is the system's frequency-active transfer function, M is the rotor time constant related to the moment of inertia, L is the load's active frequency response coefficient, and P... s P represents the power released from energy storage, P represents the active power deficit of new energy sources during low voltage ride-through, t1 represents the low voltage ride-through time, t2 represents the low voltage ride-through recovery time, and t3 represents the duration of energy storage release.

[0063] Furthermore, the time-domain model corresponding to the power system frequency is obtained through the inverse Laplace transform as follows:

[0064]

[0065] Furthermore, written as a piecewise function related to t, it is expressed as:

[0066]

[0067] Further differentiation yields a piecewise function of the system's rate of change of frequency with respect to t, expressed as:

[0068]

[0069] Furthermore, the condition for the existence of two local minima in the system's frequency response is to simultaneously satisfy Δω(t1+t3)≤0, Right now At that time, the system's frequency response curve has two minimum points.

[0070] Specifically, the time representation of the first minimum point is as follows:

[0071]

[0072] Where, k = L / M;

[0073] The value of the first minimum point is expressed as:

[0074]

[0075] The time representation of the second minimum point is:

[0076]

[0077] The value of the second minimum point is expressed as:

[0078]

[0079] S3: Obtain the emergency control and release strategy for energy storage by calculating the time-domain model;

[0080] Specifically, the emergency control and release strategy for energy storage includes the energy storage release power and the duration of energy storage release.

[0081] Furthermore, the emergency control and release strategies for energy storage, obtained through time-domain model calculations, include:

[0082] If the frequency deviation of the system at the first moment is not greater than 0, and the rate of change of the frequency at the second moment is greater than 0, the system frequency response curve has two minimum points.

[0083] When the energy that can be released from the energy storage meets the first threshold and the two minimum points are equal, the optimal control release strategy for the energy storage release power and the energy storage continuous release time is implemented.

[0084] When the optimal control strategy is released, the energy storage release power is greater than 0 and not greater than the rated energy storage release power; the energy storage continuous release time is greater than 0 and less than the low voltage ride-through recovery time.

[0085] It should be noted that in the embodiments of this application, the first time is time (t1+t3), the second time is time (t1+t3)-, and the value of the first threshold can be specifically selected according to the total energy that can be released from the energy storage of a specific fault.

[0086] Furthermore, it also includes: a single-objective optimization function for the emergency control and release strategy of energy storage, expressed as:

[0087]

[0088] Among them, P s To store energy and release power, P sN t1 is the rated release power of the energy storage, t2 is the low voltage ride-through time, t3 is the low voltage ride-through recovery time, C is the total energy that can be released from the energy storage, and ω is the total energy that can be released from the energy storage. B1 Let ω be the value at the first minimum point. B2 Let ω be the value at the second minimum point, t be time, and Δω(t1+t3) be the frequency deviation at time (t1+t3).

[0089] The above is an illustrative scheme of a method for calculating the optimal release strategy for emergency energy storage control according to this embodiment. It should be noted that the technical solution of this energy storage emergency control optimal release strategy calculation device belongs to the same concept as the above-described energy storage emergency control optimal release strategy calculation method. Details not described in detail in the technical solution of the energy storage emergency control optimal release strategy calculation device in this embodiment can be found in the description of the above-described energy storage emergency control optimal release strategy calculation method.

[0090] This embodiment provides a calculation device for an optimal release strategy in emergency control of energy storage, comprising:

[0091] The fault information confirmation module is used to collect power grid operation mode data, adjust power grid simulation data according to the actual operating conditions of the power grid when a fault occurs, determine the low voltage ride-through disturbance curve of new energy after a single power grid fault occurs, and obtain the target data for new energy to enter low voltage ride-through.

[0092] The model building module is used to construct a power system frequency response model based on target data, combined with the emergency control power of energy storage and the short-term impact power of new energy low-voltage process, and to obtain the time domain model corresponding to the power system frequency using the power system frequency response model.

[0093] The strategy calculation module is used to obtain the energy storage emergency control release strategy by calculating the time domain model; the energy storage emergency control release strategy includes the energy storage release power and the energy storage continuous release time.

[0094] This embodiment also provides a computing device applicable to a method for calculating the optimal release strategy for emergency control of energy storage, including:

[0095] The system includes a memory and a processor. The memory stores computer-executable instructions, and the processor executes these instructions to implement the calculation method for the optimal release strategy of emergency energy storage control as proposed in the above embodiments.

[0096] This embodiment also provides a storage medium storing a computer program that, when executed by a processor, implements the calculation method for the optimal release strategy of emergency control of energy storage as proposed in the above embodiment.

[0097] The storage medium proposed in this embodiment and the calculation method for the optimal release strategy of emergency control of energy storage proposed in the above embodiments belong to the same inventive concept. Technical details not described in detail in this embodiment can be found in the above embodiments, and this embodiment has the same beneficial effects as the above embodiments.

[0098] Based on the above description of the implementation methods, those skilled in the art can clearly understand that the present invention can be implemented using software and necessary general-purpose hardware, and of course, it can also be implemented using hardware, but in many cases the former is a better implementation method. Based on this understanding, the technical solution of the present invention, or the part that contributes to the prior art, can be embodied in the form of a software product. This computer software product can be stored in a computer-readable storage medium, such as a computer floppy disk, read-only memory (ROM), random access memory (RAM), flash memory, hard disk, or optical disk, etc., including several instructions to cause a computer device (which may be a personal computer, server, or network device, etc.) to execute the methods of the various embodiments of the present invention.

[0099] Example 2

[0100] Reference Figures 2-4 This is one embodiment of the present invention. Through specific testing, the beneficial effects of our invention have been verified.

[0101] This application uses an IEEE 10-machine 39-node system network as the simulation framework. The operating conditions are as follows: the total load is 1000MW, a constant power model is adopted, and the frequency factor L = 2.0; it includes 7 synchronous machines with an inertial time constant H of 4s, and 3 wind farms with rated capacities of 100MW, 50MW and 50MW respectively.

[0102] The low-voltage ride-through time of the renewable energy source is t1 = 0.1s, and the low-voltage recovery time is t2 = 1.5s. After the fault occurs, all renewable energy sources enter the low-voltage ride-through mode, and no renewable energy source disconnects from the grid. The total energy that can be released from the energy storage is 40MWs.

[0103] Based on the simulation calculations performed in the above embodiments, the results show that, for one of the known faults, after the energy storage releases all 40MWs of energy, the strategy with the best effect on controlling the maximum frequency deviation of the system is: the release power is 33.778MW, the release duration is 1.1842s, and the maximum frequency deviation of the system is -0.6327Hz.

[0104] Reference Figure 2 and Figure 3 The system frequency response curves before and after energy storage participation in control are compared with those before energy storage participation in emergency control. The maximum frequency deviation of the system is significantly improved after energy storage participation in emergency control.

[0105] like Figure 4It can be seen from the verification results shown that when the energy released by the energy storage is 40MWs, on the premise of t3<t2, the energy storage release strategy with the best control effect is to control the maximum frequency deviation at -0.6327Hz.

[0106] It should be noted that the above embodiments are only used to illustrate the technical solution of the present invention rather than to limit it. Although the present invention has been described in detail with reference to the preferred embodiments, those of ordinary skill in the art should understand that modifications or equivalent substitutions can be made to the technical solution of the present invention without departing from the spirit and scope of the technical solution of the present invention, all of which shall be encompassed within the scope of the claims of the present invention.

Claims

1. A method for calculating the optimal release strategy for emergency control of energy storage, characterized in that, include: Collect power grid operation mode data, and adjust power grid simulation data according to the actual operating conditions when a power grid accident occurs, determine the low voltage ride-through disturbance curve of new energy after a single power grid fault, and obtain the target data for new energy to enter low voltage ride-through. Based on the target data, a power system frequency response model is constructed by combining the emergency control power of energy storage and the short-term impact power of new energy low-voltage process, and the time domain model corresponding to the power system frequency is obtained by using the power system frequency response model. An emergency control release strategy for energy storage is obtained by calculating the time-domain model; the emergency control release strategy for energy storage includes the energy storage release power and the energy storage continuous release time. The single-objective optimization function of the energy storage emergency control release strategy is expressed as: in, To release power for energy storage, For the rated release power of energy storage, For low voltage ride-through time, For low voltage ride-through recovery time, For the duration of energy storage release, The total energy that can be released from energy storage. The value at the first minimum point. The value at the second minimum point. For time, ( )for( Frequency deviation at time ( ).

2. The method for calculating the optimal release strategy for emergency control of energy storage as described in claim 1, characterized in that, The emergency control and release strategy for energy storage, obtained by calculating the time-domain model, includes: If the frequency deviation of the system at the first moment is not greater than 0, and the rate of change of the frequency at the second moment is greater than 0, the system frequency response curve has two minimum points. When the energy that can be released from the energy storage meets the first threshold and the two minimum points are equal, the optimal control release strategy for the energy storage release power and the energy storage continuous release time is implemented. When the optimal control strategy is released, the energy storage release power is greater than 0 and not greater than the rated energy storage release power; the energy storage continuous release time is greater than 0 and less than the low voltage ride-through recovery time.

3. The method for calculating the optimal release strategy for emergency control of energy storage as described in claim 2, characterized in that, The frequency response model of a power system is expressed as follows: in, For the Laplace operator, Let M be the frequency-active power transfer function of the system, M be the rotor time constant related to the moment of inertia, and L be the active frequency response coefficient of the load. P represents the active power deficit of new energy sources during low-voltage ride-through, where P is the power released from energy storage. For low voltage ride-through time, For low voltage ride-through recovery time, This refers to the duration of energy storage release.

4. The method for calculating the optimal release strategy for emergency control of energy storage as described in claim 3, characterized in that, The time-domain model of the power system frequency obtained by inverse Laplace transform is as follows: 。 5. The method for calculating the optimal release strategy for emergency control of energy storage as described in claim 4, characterized in that, include: The time representation of the first minimum point is: in, ; The value of the first minimum point is expressed as: The time representation of the second minimum point is: The value of the second minimum point is expressed as: 。 6. The method for calculating the optimal release strategy for emergency control of energy storage as described in claim 5, characterized in that, The target data for obtaining new energy sources to enter low voltage ride-through include: the active power deficit of new energy sources entering low voltage ride-through, the low voltage ride-through time, and the low voltage ride-through recovery time.

7. A calculation device for optimal release strategy in emergency control of energy storage, characterized in that, The method of claim 1 is used, comprising: The fault information confirmation module is used to collect power grid operation mode data, adjust power grid simulation data according to the actual operating conditions of the power grid when a fault occurs, determine the low voltage ride-through disturbance curve of new energy after a single power grid fault occurs, and obtain the target data for new energy to enter low voltage ride-through. The model building module is used to construct a power system frequency response model based on the target data, combined with the emergency control power of energy storage and the short-term impact power of the low-voltage process of new energy, and to obtain the time domain model corresponding to the power system frequency using the power system frequency response model. The strategy calculation module is used to obtain the energy storage emergency control release strategy by calculating the time domain model; the energy storage emergency control release strategy includes the energy storage release power and the energy storage continuous release time.

8. An electronic device, comprising: Memory and processor; The memory is used to store computer-executable instructions, and the processor is used to execute the computer-executable instructions. When the computer-executable instructions are executed by the processor, they implement the steps of the energy storage emergency control optimal release strategy calculation method according to any one of claims 1 to 6.

9. A computer-readable storage medium storing computer-executable instructions that, when executed by a processor, implement the steps of the energy storage emergency control optimal release strategy calculation method according to any one of claims 1 to 6.

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