A power system frequency control method based on wind-storage combined frequency regulation

Abstract

This invention relates to the field of power system frequency control technology, and particularly to a power system frequency control method based on wind and energy storage joint frequency regulation. The method includes: real-time acquisition of frequency data and quantification of frequency disturbance intensity; calculation of energy storage frequency regulation weighting coefficients and wind power frequency regulation weighting coefficients based on the frequency disturbance intensity; frequency regulation by the energy storage system based on the energy storage frequency regulation weighting coefficients to obtain the energy storage frequency regulation output power; wind turbines participating in frequency regulation through rotor inertia frequency regulation channels and backup channels based on the wind power frequency regulation weighting coefficients to obtain the wind power inertia frequency regulation output power and the response power of the wind power backup channel; and obtaining the total frequency regulation output power based on the energy storage frequency regulation output power and the various frequency regulation power components of the wind power, thus achieving multi-source coordinated staged frequency control. This method solves problems such as unclear frequency regulation priority, fixed response signal paths, frequency regulation channel conflicts, and the lack of a recursive self-stabilizing modulation mechanism in traditional power system frequency control methods.

Description

Technical Field

[0001] This invention relates to the field of power system frequency control technology, and in particular to a power system frequency control method based on wind-storage combined frequency regulation. Background Technology

[0002] With the large-scale grid connection of renewable energy sources such as wind power, the frequency stability of the power system faces severe challenges. Due to the physical characteristics of their converter interfaces, wind turbines lack inherent inertia support, making it difficult to respond quickly to frequency deviations when the power system experiences disturbances. Furthermore, the strong fluctuations in wind power output limit its participation in conventional frequency regulation strategies. In contrast, energy storage systems offer advantages such as rapid response and high regulation accuracy, and have been used in primary and secondary frequency regulation applications in the power system.

[0003] In traditional power system frequency control methods, wind power frequency regulation mainly involves simulating the inertial response through rotor kinetic energy release and active power regulation through power reserves created by load shedding. Energy storage systems typically participate in frequency regulation as linear response units. The mainstream method for joint wind power and energy storage frequency regulation often employs a linear superposition model, where the inertial response, power reserve response, and energy storage response are modeled independently, and then simply summed to obtain a unified response frequency deviation signal. This method suffers from problems such as unclear frequency regulation priorities, fixed response signal paths, frequency regulation channel conflicts, and the lack of a recursive self-stabilizing modulation mechanism, making it difficult to meet the dynamic frequency control requirements of high-proportion wind power systems.

[0004] Therefore, there is an urgent need for a wind-storage joint frequency regulation control strategy with recursive logic, dynamic weight allocation, and frequency modulation feedback functions, which can more effectively coordinate different frequency regulation resources, realize behavioral coupling and dynamic dominance switching between multi-source heterogeneous frequency regulation units, and thus enhance the frequency stability and frequency regulation control accuracy of the power system. Summary of the Invention

[0005] This invention provides a power system frequency control method based on wind-storage joint frequency regulation, which solves the problems of unclear frequency regulation priority, fixed response signal path, frequency regulation channel conflict and lack of recursive self-stabilizing modulation mechanism in traditional power system frequency control methods.

[0006] The present invention provides a power system frequency control method based on wind-storage combined frequency regulation, which specifically includes the following technical solutions:

[0007] A power system frequency control method based on wind-storage joint frequency regulation includes the following steps:

[0008] S1. Collect frequency data in real time and quantify the degree of frequency disturbance to obtain the frequency disturbance intensity; based on the frequency disturbance intensity, calculate the energy storage frequency regulation weight coefficient and the wind power frequency regulation weight coefficient.

[0009] S2. The energy storage system performs frequency regulation based on the energy storage frequency regulation weighting coefficient to obtain the energy storage frequency regulation output power; the wind turbine participates in frequency regulation through the rotor inertia frequency regulation channel and the backup channel based on the wind power frequency regulation weighting coefficient to obtain the wind power inertia frequency regulation output power and the response power of the wind power backup channel; based on the energy storage frequency regulation output power, the wind power inertia frequency regulation output power and the response power of the wind power backup channel, the total frequency regulation output power is obtained, realizing multi-source coordinated staged frequency control.

[0010] Preferably, S1 specifically includes:

[0011] Based on frequency data and the system's rated frequency, the frequency deviation is calculated; based on the absolute amplitude of the frequency deviation and the rate of change of the frequency deviation, a frequency disturbance intensity function is constructed to obtain the frequency disturbance intensity.

[0012] Preferably, S1 specifically includes:

[0013] The frequency disturbance intensity is compared with the preset threshold parameter, and the energy storage frequency regulation weight coefficient is generated through nonlinear mapping, thus obtaining the wind power frequency regulation weight coefficient.

[0014] Preferably, S2 specifically includes:

[0015] By using the energy storage system as the first execution unit to intervene in the control process, and based on the energy storage frequency regulation weighting coefficient, the energy storage frequency regulation gain coefficient and the response time constant of the energy storage system are introduced to compensate for the frequency deviation and obtain the energy storage frequency regulation output power.

[0016] Preferably, S2 specifically includes:

[0017] A rotor inertia frequency regulation channel for wind turbines is established. Based on the wind power frequency regulation weighting coefficient, the rotor inertia response coefficient and the rotor inertia response time constant of the wind turbines are introduced. Combined with the inertia response suppression function, the frequency deviation is compensated to obtain the wind power inertia frequency regulation output power.

[0018] Preferably, S2 specifically includes:

[0019] The inertia response suppression function is constructed based on the frequency modulation output power of the energy storage system and the rated power of the energy storage system.

[0020] Preferably, S2 specifically includes:

[0021] Based on the wind power frequency regulation weighting coefficient, the frequency regulation gain coefficient of the wind turbine standby power and the pitch response time constant of the wind turbine are introduced. Combined with the inertia response suppression function, the frequency deviation is compensated, and the response power of the wind power standby channel is calculated.

[0022] Preferably, S2 specifically includes:

[0023] The frequency regulation output power of energy storage, the frequency regulation output power of wind power inertia, and the response power of wind power backup channels are converted from the frequency domain response back to the time domain power signal and then weighted and synthesized to obtain the total frequency regulation output power. The total frequency regulation output power is used as the final control command to jointly regulate the frequency of the power system.

[0024] The beneficial effects of the technical solution of the present invention are:

[0025] 1. By constructing a frequency disturbance intensity function, and comprehensively considering the absolute amplitude and rate of change of frequency deviation, the degree of frequency disturbance in the power system can be fully quantified, providing a scientific basis for subsequent frequency regulation control. The frequency regulation weight coefficients of the energy storage system and the wind turbine are dynamically allocated according to the frequency disturbance intensity, which ensures that the participation ratio of the two is complementary and the sum is always one, while avoiding overlapping or missing regulation, thus improving coordination and system stability.

[0026] 2. The energy storage system is the first to respond quickly to frequency disturbances, while the wind turbine provides phased supplementary support through rotor kinetic energy release and reserve capacity adjustment, forming a multi-level, phased frequency suppression and repair mechanism, which significantly enhances the power system's anti-disturbance capability. By introducing an inertia response suppression function, the frequency regulation intensity of wind power inertia is dynamically suppressed according to the frequency regulation output power of the energy storage system, avoiding excessive power superposition that could lead to secondary frequency fluctuations, and improving the stability and reliability of the control process.

[0027] 3. All input variables are actual measurable physical quantities, and the threshold parameters are obtained based on the actual system characteristics. The structure is clear and easy to implement, making it suitable for the scheduling and control applications of actual power systems. Through the multi-source frequency regulation mechanism of wind and energy storage collaboration, the power system can quickly mobilize the energy storage system to respond at high speed when frequency disturbances occur, and connect the kinetic energy and backup support of wind turbine units to achieve effective suppression and rapid recovery of frequency fluctuations, thereby comprehensively improving the frequency stability and operational safety of the power system. Attached Figure Description

[0028] Figure 1 This is a flowchart of a power system frequency control method based on wind and energy storage combined frequency regulation as described in this invention. Detailed Implementation

[0029] To further illustrate the technical means and effects adopted by the present invention to achieve its intended purpose, the technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings of the embodiments. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0030] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains.

[0031] The following description, in conjunction with the accompanying drawings, details a specific scheme for a power system frequency control method based on wind and energy storage combined frequency regulation provided by the present invention.

[0032] See attached document Figure 1 The diagram illustrates a flowchart of a power system frequency control method based on wind-storage joint frequency regulation according to an embodiment of the present invention. The method includes the following steps:

[0033] S1. Collect frequency data in real time and quantify the degree of frequency disturbance to obtain the frequency disturbance intensity; based on the frequency disturbance intensity, calculate the energy storage frequency regulation weight coefficient and the wind power frequency regulation weight coefficient.

[0034] Frequency data is collected by the frequency measurement unit located at the main bus of the power system dispatch center through wind and energy storage frequency regulation, and high-precision PLL (phase-locked loop) module is used to extract frequency data in real time. The sampling period of frequency data is within 20ms.

[0035] The frequency deviation is calculated by the local controller based on the measured frequency data, and the frequency deviation change rate is obtained by the first-order difference method; the first-order difference method is a well-known technique and will not be described in detail here. The current output power of the energy storage system is provided by the real-time operation data interface of the energy storage converter, which is used to control the wind power frequency regulation response threshold and the system frequency regulation power synthesis to ensure that the input variables are all physically measurable and real-time effective system operating quantities.

[0036] To accurately quantify the frequency deviation of a power system under combined wind and energy storage frequency regulation, it is necessary to define the deviation between the current frequency data of the power system and its rated frequency. This deviation is then used as the original input signal for the entire frequency regulation control link. The rated frequency is the baseline value required for stable operation of the power system, determined by system design parameters, and does not change with time or load fluctuations. The frequency deviation expression can be given as:

[0037] ,

[0038] in, At any moment Frequency deviation; The system's rated frequency (e.g., 50Hz); For the current moment The measured values ​​of the frequency data are obtained by the frequency measurement unit at the main bus of the system.

[0039] To construct a quantitative expression that conforms to the characteristics of power system frequency disturbances, the degree of system frequency disturbance needs to be formally defined. Frequency disturbances are not only reflected in the absolute amplitude of frequency deviation, but the rate of change of frequency deviation also affects the real-time judgment and adjustment intensity of frequency regulation control. Therefore, to achieve a comprehensive quantification of the degree of frequency disturbance, a frequency disturbance intensity function is defined:

[0040] ,

[0041] in, At any moment The frequency disturbance intensity function represents the overall disturbance level of the power system at a certain moment; The disturbance rate sensitivity coefficient is used to control the weight of the frequency change rate in the total disturbance perception. Its value ranges from [0.2, 0.8] and is in seconds. It is obtained by regression fitting of the disturbance response process, which is a well-known technique in the art and will not be described in detail here. It is the rate of change of frequency deviation;

[0042] Based on the frequency disturbance intensity, a frequency regulation priority allocation logic is constructed to obtain the energy storage frequency regulation weight coefficient and the wind power frequency regulation weight coefficient, which are used to describe the participation ratio of the energy storage system and wind turbine in the overall frequency regulation process under different disturbance intensities. Specifically, the frequency disturbance intensity is compared with the threshold parameter obtained by calibration from operating data (i.e., frequency deviation and its rate of change), and a weight coefficient with a value between 0 and 1 is generated through nonlinear mapping. After determining the energy storage frequency regulation weight coefficient, the wind power frequency regulation weight coefficient needs to maintain a complementary relationship with it to ensure that the sum of the participation ratios of wind turbine and energy storage system in system frequency regulation is one, and that there is no overlap or gap between the two. The specific calculation formulas for the energy storage frequency regulation weight coefficient and the wind power frequency regulation weight coefficient are as follows:

[0043] ,

[0044] ,

[0045] in, It is the energy storage system at all times The frequency regulation response weighting coefficient, i.e., the energy storage frequency regulation weighting coefficient; It is the wind turbine unit at all times The frequency regulation response weighting coefficient, i.e., the wind power frequency regulation weighting coefficient; This is the disturbance response steepness coefficient, used to control the steepness of the function shape. Its value ranges from [1, 10], and its unit is _____. The method of obtaining this through simulation fitting is well-known to those skilled in the art and will not be elaborated here. This is the energy storage response threshold. When the frequency disturbance intensity exceeds the energy storage response threshold, the energy storage system quickly intervenes to regulate the frequency. The energy storage response threshold is set according to the grid frequency safety operation standard, and the unit is 1200 ppm. .

[0046] S2. The energy storage system performs frequency regulation based on the energy storage frequency regulation weighting coefficient to obtain the energy storage frequency regulation output power; the wind turbine participates in frequency regulation through the rotor inertia frequency regulation channel and the backup channel based on the wind power frequency regulation weighting coefficient to obtain the wind power inertia frequency regulation output power and the response power of the wind power backup channel; based on the energy storage frequency regulation output power, the wind power inertia frequency regulation output power and the response power of the wind power backup channel, the total frequency regulation output power is obtained, realizing multi-source coordinated staged frequency control;

[0047] After the frequency regulation weighting coefficient is calculated, the energy storage system needs to be involved in the control process as the first execution unit. The energy storage system plays a rapid support role in power system frequency control; its power regulation characteristics can be characterized by a first-order inertial element. Its mechanism is to quickly compensate for frequency deviations with a finite response time constant after detecting frequency disturbances. The frequency deviation is used as input, adjusted by the energy storage frequency regulation weighting coefficient, and then transmitted to the energy storage system's power response stage. This reflects the real-time impact of the frequency disturbance intensity on the energy storage's participation ratio in frequency regulation during the response process, yielding the energy storage frequency regulation output power. The specific formula for the energy storage frequency regulation output power is:

[0048] ,

[0049] in, It is an energy storage system in the Laplace domain The frequency modulation power output in the system is the frequency modulation output power of the energy storage system; The frequency regulation gain coefficient for energy storage is calculated as the ratio of the rated power of the energy storage system to its maximum frequency response capability, and the unit is 1. ; It is the Laplace operator, with units of 1. That is, the reciprocal of a second; The response time constant of the energy storage system represents the response time from detecting a disturbance to completing the adjustment. It is provided by the energy storage converter controller manufacturer and is expressed in seconds. It is the representation of frequency deviation in the Laplace domain; It is the power response function;

[0050] After the frequency disturbance is partially absorbed by the energy storage system, a rotor inertia frequency regulation channel for the wind turbine needs to be established. The frequency deviation is used as input, and the system is simultaneously constrained by the energy storage frequency regulation power to obtain the wind power inertia frequency regulation output power. This constraint is characterized by an inertia response suppression function. When the energy storage frequency regulation output power increases, the participation of inertia frequency regulation decreases to avoid excessive superposition between the two, which could lead to frequency regulation conflicts. Conversely, when the energy storage frequency regulation output power decreases, the participation of inertia frequency regulation increases to provide rapid but short-term kinetic energy support when energy storage is insufficient. The calculation expression for the wind power inertia frequency regulation output power is:

[0051] ,

[0052] in, Under frequency disturbance, the rotor inertia frequency modulation channel of the wind turbine in the Laplace domain The active power response in the wind power inertia frequency regulation output power; At any moment The rated power of the energy storage system; Indicates at time The energy storage frequency modulation output power, through the The method of obtaining the result by performing an inverse Laplace transform is well-known to those skilled in the art and will not be elaborated here. It is the inertia response suppression function used to suppress the inertia frequency regulation channel of the wind turbine. It reflects that the stronger the output of the energy storage system, the lower the regulation capability of the inertia frequency regulation channel of the wind turbine should be. The rotor inertia response coefficient of a wind turbine is obtained through dynamic characteristic testing of wind turbines, a technique well-known to those skilled in the art and will not be elaborated upon here. The unit is 1. ; The rotor inertia response time constant of the wind turbine represents the dynamic delay in which the rotor kinetic energy is released to the grid through the converter. It is provided by the wind turbine controller manufacturer and is measured in seconds.

[0053] After the output power of wind turbine frequency regulation is amplitude-limited by the inertia response suppression function, the wind turbine still possesses a portion of reserve power capacity that can be used to continuously support the system frequency. To ensure that the wind turbine can effectively compensate for frequency deviations when the dominant role of energy storage response weakens, the response power of the wind turbine reserve channel needs to be used as a supplement to the rotor inertia frequency regulation channel. Therefore, the wind turbine reserve channel response function is constructed as follows:

[0054] ,

[0055] in, It is a backup channel for wind turbines in the Laplace domain. The active power output response function under the given conditions, i.e. the response power of the wind power backup channel; This refers to the frequency regulation gain coefficient of the wind turbine's reserve power, representing the wind turbine's ability to regulate frequency deviations using its reserved reserve capacity. It is calculated based on the ratio of the wind farm's reserve active power capacity to the target frequency difference, and is measured in units of... ; The pitch response time constant of the wind turbine represents the response delay caused by the mechanical actuator (pitch adjustment) during the standby channel adjustment of the wind turbine. It is set according to the mechanical execution characteristics of the wind turbine's electronic control system and is measured in seconds.

[0056] The frequency modulation output power of energy storage, the frequency modulation output power of wind power inertia, and the response power of wind power backup channels are converted from the frequency domain response back to the time domain power signal through inverse Laplace transform, and then uniformly weighted and synthesized to obtain the total frequency modulation output power. The inverse Laplace transform is a technique well known to those skilled in the art and will not be described in detail here. The specific formula for calculating the total frequency modulation output power is as follows:

[0057] ,

[0058] in, At any moment The total frequency regulation output power is directly input into the power system dispatch and control module as the final control command; , and They represent the times respectively. The energy storage frequency regulation output power, wind power inertia frequency regulation output power, and wind power backup channel response power;

[0059] In the above scheme, all data involving power are expressed in units of 1. To eliminate dimensional issues and ensure that all physical quantities have a consistent numerical scale in subsequent analysis or modeling, thus maintaining dimensional uniformity;

[0060] In practical applications, wind-storage combined frequency regulation power systems allocate the charging and discharging power of the energy storage system and adjust the output level of wind turbines according to the final control commands, thereby achieving a joint frequency regulation process under the coordinated action of multiple sources. Therefore, wind-storage combined frequency regulation power systems can quickly mobilize the high-speed response characteristics of the energy storage system when frequency disturbances occur. At the same time, combined with the rotor kinetic energy support and active power reserve regulation functions of wind turbines, multi-level suppression and phased repair of frequency fluctuations are achieved, effectively improving the frequency stability and security of the power system.

[0061] In summary, a power system frequency control method based on wind and energy storage joint frequency regulation has been developed.

[0062] The order of the embodiments is for illustrative purposes only and does not represent the superiority or inferiority of the embodiments. The processes depicted in the drawings do not necessarily require a specific or sequential order to achieve the desired result. In some embodiments, multitasking and parallel processing are possible or may be advantageous.

[0063] The various embodiments in this specification are described in a progressive manner. The same or similar parts between the various embodiments can be referred to each other. Each embodiment focuses on describing the differences from other embodiments.

[0064] The above embodiments are only used to illustrate the technical solutions of the present invention, and are not intended to limit it. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention, and should all be included within the protection scope of the present invention.

Claims

1. A power system frequency control method based on wind-storage combined frequency regulation, characterized in that, Includes the following steps: S1. Collect frequency data in real time and calculate the frequency deviation in combination with the system's rated frequency; Based on the frequency deviation, the degree of frequency disturbance is quantified to obtain the frequency disturbance intensity; Based on the frequency disturbance intensity, calculate the frequency regulation weighting coefficients for energy storage and wind power. S2. The energy storage system performs frequency regulation based on the energy storage frequency regulation weighting coefficient to obtain the energy storage frequency regulation output power; Based on the frequency regulation output power of energy storage and combined with the rated power of the energy storage system, an inertial response suppression function is constructed; the wind turbine participates in frequency regulation through the rotor inertial frequency regulation channel based on the wind power frequency regulation weighting coefficient to obtain the wind power inertial frequency regulation output power; based on the wind power frequency regulation weighting coefficient, it participates in frequency regulation through the backup channel, and the backup power frequency regulation gain coefficient of the wind turbine and the pitch response time constant of the wind turbine are introduced. Combined with the inertial response suppression function, the frequency deviation is compensated, and the response power of the wind power backup channel is calculated. Based on the frequency regulation output power of energy storage, the frequency regulation output power of wind power inertia, and the response power of wind power backup channels, the total frequency regulation output power is obtained, realizing multi-source coordinated staged frequency control.

2. The power system frequency control method based on wind-storage joint frequency regulation according to claim 1, characterized in that, Specifically, it includes: Based on the absolute amplitude of the frequency deviation and combined with the rate of change of the frequency deviation, a frequency disturbance intensity function is constructed to obtain the frequency disturbance intensity.

3. The power system frequency control method based on wind-storage joint frequency regulation according to claim 2, characterized in that, Specifically, it includes: The frequency disturbance intensity is compared with the preset threshold parameter, and the energy storage frequency regulation weight coefficient is generated through nonlinear mapping, thus obtaining the wind power frequency regulation weight coefficient.

4. The power system frequency control method based on wind-storage joint frequency regulation according to claim 3, characterized in that, Specifically, it includes: By using the energy storage system as the first execution unit to intervene in the control process, and based on the energy storage frequency regulation weighting coefficient, the energy storage frequency regulation gain coefficient and the response time constant of the energy storage system are introduced to compensate for the frequency deviation and obtain the energy storage frequency regulation output power.

5. A power system frequency control method based on wind-storage joint frequency regulation according to claim 4, characterized in that, Specifically, it includes: A rotor inertia frequency regulation channel for wind turbines is established. Based on the wind power frequency regulation weighting coefficient, the rotor inertia response coefficient and the rotor inertia response time constant of the wind turbines are introduced. Combined with the inertia response suppression function, the frequency deviation is compensated to obtain the wind power inertia frequency regulation output power.

6. The power system frequency control method based on wind-storage joint frequency regulation according to claim 1, characterized in that, Specifically, it includes: The frequency regulation output power of energy storage, the frequency regulation output power of wind power inertia, and the response power of wind power backup channels are converted from the frequency domain response back to the time domain power signal and then weighted and synthesized to obtain the total frequency regulation output power. The total frequency regulation output power is used as the final control command to jointly regulate the frequency of the power system.

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