Method, device and equipment for suppressing low-frequency oscillation by million-kilowatt compressed air energy storage

Abstract

The invention relates to the technical field of electric power control, in particular to a million-kilowatt compressed air energy storage low-frequency oscillation restraining method, device and equipment, and the method comprises the steps that the rotating speed difference increment of a compressor during low-frequency oscillation of the frequency of an electric power system is obtained, an additional damping control model is input to generate an adjusting instruction of the mass flow rate of a gas storage, and the adjusting instruction is calculated; and the target opening degree of the regulating valve is determined by using an opening degree valve control model in combination with the rated mass flow rate, so that the actual mass flow rate of the gas storage is accurately controlled, and compressed air with the actual mass flow rate after being regulated in the gas storage enters a heater to be heated and then enters a turbine to do work. And adjusting the power of the turbine based on the output power and the mass flow of the turbine, thereby realizing self-adaptive adjustment of the mass flow through real-time estimation and compensation of system disturbance, further controlling the output power of compressed air energy storage, realizing effective suppression of low-frequency oscillation of a power grid, enhancing damping of a power system, and improving the stability of the power system.

Description

Technical Field

[0001] This application relates to the field of power control technology, and in particular to a method, apparatus and equipment for suppressing low-frequency oscillations in megawatt compressed air energy storage. Background Technology

[0002] With the large-scale integration of new energy sources into the power system, the problem of low-frequency oscillations in the power grid is becoming increasingly prominent. CAES (Compressed Air Energy Storage) systems have fast response characteristics and the potential to improve system damping, which can effectively suppress low-frequency oscillations in the power grid. However, a megawatt-level CAES system is a complex system with a complex internal structure, significant nonlinearity in thermodynamic processes, and strong coupling relationships between subsystems. The PI (Proportional-Integral) control strategy used in related technologies to handle the control problem of CAES systems is difficult to cope with nonlinear disturbances under complex operating conditions. Summary of the Invention

[0003] This application provides a method, apparatus, and equipment for suppressing low-frequency oscillations in megawatt compressed air energy storage, in order to solve the problems that related technologies using a single proportional-integral control strategy perform poorly when facing nonlinear disturbances under complex operating conditions, and cannot effectively suppress low-frequency oscillations in the power grid.

[0004] The first aspect of this application provides a method for suppressing low-frequency oscillations in a megawatt compressed air energy storage system. The megawatt compressed air energy storage system includes a compressor, a turbine, a heat exchanger, an air storage tank, and a regulating valve for the air storage tank. The method includes the following steps: acquiring the speed difference increment of the compressor when low-frequency oscillations occur in the power system frequency; inputting the speed difference increment into an additional damping control model; the additional damping control model outputs a regulation command for the mass flow rate of the air storage tank; acquiring the rated mass flow rate when the megawatt compressed air energy storage system outputs rated power; and inputting the mass flow rate regulation command and the rated command flow rate into the opening valve control. The model controls the target opening degree of the regulating valve, and adjusts the actual mass flow rate of the gas storage tank according to the target opening degree. The compressed air with the actual mass flow rate after adjustment enters the heater for heating. The opening valve control model includes a tracking differentiator, a linear expansion state observer, a linear state error feedback controller, an inertial element, and a limiting element. Based on the relationship between the turbine's output power and the mass flow rate, the power increment corresponding to the actual mass flow rate is determined. The turbine power is adjusted based on the power increment, and the turbine drives the compressor to output active power based on the heated compressed air.

[0005] Optionally, the additional damping control model includes an additional damping controller, which performs additional damping control on the speed difference increment through a gain circuit, a filtering circuit, a phase compensation circuit, and a limiting circuit.

[0006] Optionally, the transfer function expression of the additional damping controller is:

[0007]

[0008] Among them, K QS T WQS T 1QS T 2QS Here are the controller parameters; ΔQ is the mass flow rate adjustment command; ΔQ max Δω represents the maximum amplitude of the additional damping control output command, and Δω represents the speed difference increment.

[0009] Optionally, the valve opening control model includes a tracking differentiator, a linear expansion state observer, a linear state error feedback controller, an inertial element, and a limiting element. The control flow of the valve opening control model includes: adding the mass flow rate corresponding to the adjustment command to the rated command flow rate to obtain the desired output mass flow rate; dynamically filtering the signal of the desired output mass flow rate through the tracking differentiator to generate a smooth transient process signal; inputting the actual mass flow rate into the linear expansion state observer, which estimates the total disturbance of the megawatt-scale compressed air energy storage; inputting the transient process signal and the total disturbance into the linear state error feedback controller, which outputs a virtual control quantity; calculating the total control quantity based on the compensation coefficient of the total disturbance and the virtual control quantity; and adjusting the total control quantity through the inertial element and the limiting element to obtain the target opening of the regulating valve.

[0010] Optionally, the control algorithm for the opening valve control model is as follows:

[0011]

[0012] Where r is the transient signal generated by the tracking differentiator, and k p k d β1, β2, and β3 are the gain of the linear state error feedback; β1, β2, and β3 are the parameters of the linear extended state observer error feedback gain matrix; z is the state vector of the linear extended state observer; y is the actual mass flow rate of the output; u is the total control quantity; and u0 is the virtual control quantity.

[0013] Optionally, the relationship between the output power and mass flow rate of a megawatt compressed air energy storage system is as follows:

[0014]

[0015] Among them, w allThe output power of the megawatt compressed air energy storage system is given by η, where Q is the mass flow rate at the regulating valve opening. e Let k be the turbine's output efficiency, k be the ideal air specific heat capacity, and w be the output efficiency. e,j Let i be the output power of the j-th stage turbine, i be the turbine stage number, and c be the output power of the j-th stage turbine. p The specific heat ratio at constant pressure Let β be the inlet temperature of the j-th stage heater. e,j The expansion ratio of the jth order.

[0016] Optionally, before determining the power increment corresponding to the actual mass flow rate in relation to the output power and mass flow rate of the megawatt compressed air energy storage system, the following steps are also included: establishing a mathematical model of the megawatt compressed air energy storage system, wherein the mathematical model includes a model of pressure and temperature changes within the gas storage tank, a model of the relationship between the opening of the regulating valve and the mass flow rate, and a model of temperature changes in the heat exchanger; determining the relationship between the turbine inlet air temperature and the work done by a unit mass of air through the turbine based on the mathematical model; and determining the relationship between the output power and mass flow rate of the megawatt compressed air energy storage system based on the relationship between the turbine outlet air temperature and the work done by a unit mass of air through the turbine.

[0017] A second aspect of this application provides a device for suppressing low-frequency oscillations in a megawatt compressed air energy storage system. The megawatt compressed air energy storage system includes a compressor, a turbine, a heat exchanger, an air storage tank, and a regulating valve for the air storage tank. The device includes: an acquisition module for acquiring the speed difference increment of the compressor when low-frequency oscillations occur in the power system frequency, inputting the speed difference increment into an additional damping control model, and the additional damping control model outputting a regulation command for the mass flow rate of the air storage tank; and a control module for acquiring the rated mass flow rate when the megawatt compressed air energy storage system outputs rated power, and inputting the mass flow rate regulation command and the rated command flow rate into an opening valve control module. The system employs a control model that outputs the target opening degree of the regulating valve. Based on this target opening degree, the regulating valve adjusts the actual mass flow rate of the gas storage tank. The compressed air with the adjusted actual mass flow rate from the gas storage tank then enters the heater for heating. The control model includes a tracking differentiator, a linear expansion state observer, a linear state error feedback controller, an inertial element, and a limiting element. A processing module is used to determine the power increment corresponding to the actual mass flow rate based on the relationship between the output power and mass flow rate of the megawatt compressed air energy storage system. Based on this power increment, the turbine power is adjusted, and the turbine drives the compressor to output active power based on the heated compressed air.

[0018] Optionally, the additional damping control model includes an additional damping controller, which performs additional damping control on the speed difference increment through a gain circuit, a filtering circuit, a phase compensation circuit, and a limiting circuit.

[0019] Optionally, the transfer function expression of the additional damping controller is:

[0020]

[0021] Among them, K QS T WQS T 1QS T 2QS Here are the controller parameters; ΔQ is the mass flow rate adjustment command; ΔQ max Δω represents the maximum amplitude of the additional damping control output command, and Δω represents the speed difference increment.

[0022] Optionally, the valve opening control model includes a tracking differentiator, a linear expansion state observer, a linear state error feedback controller, an inertial element, and a limiting element. The control flow of the valve opening control model includes: adding the mass flow rate corresponding to the adjustment command to the rated command flow rate to obtain the desired output mass flow rate; dynamically filtering the signal of the desired output mass flow rate through the tracking differentiator to generate a smooth transient process signal; inputting the actual mass flow rate into the linear expansion state observer, which estimates the total disturbance of the megawatt-scale compressed air energy storage; inputting the transient process signal and the total disturbance into the linear state error feedback controller, which outputs a virtual control quantity; calculating the total control quantity based on the compensation coefficient of the total disturbance and the virtual control quantity; and adjusting the total control quantity through the inertial element and the limiting element to obtain the target opening of the regulating valve.

[0023] Optionally, the control algorithm for the opening valve control model is as follows:

[0024]

[0025] Where r is the transient signal generated by the tracking differentiator, and k p k d β1, β2, and β3 are the gain of the linear state error feedback; β1, β2, and β3 are the parameters of the linear extended state observer error feedback gain matrix; z is the state vector of the linear extended state observer; y is the actual mass flow rate of the output; u is the total control quantity; and u0 is the virtual control quantity.

[0026] Optionally, the relationship between the output power and mass flow rate of a megawatt compressed air energy storage system is as follows:

[0027]

[0028] Among them, w all The output power of the megawatt compressed air energy storage system is given by η, where Q is the mass flow rate at the regulating valve opening. e Let k be the turbine's output efficiency, k be the ideal air specific heat capacity, and w be the output efficiency. e,jLet i be the output power of the j-th stage turbine, i be the turbine stage number, and c be the output power of the j-th stage turbine. p The specific heat ratio at constant pressure Let β be the inlet temperature of the j-th stage heater. e,j The expansion ratio of the jth order.

[0029] Optionally, the megawatt compressed air energy storage device for suppressing low-frequency oscillations further includes: a modeling module, used to establish a mathematical model of the megawatt compressed air energy storage system before determining the power increment corresponding to the actual mass flow rate based on the relationship between the output power and mass flow rate of the megawatt compressed air energy storage system. The mathematical model includes a pressure and temperature change model within the gas storage tank, a relationship between the regulating valve opening and mass flow rate, and a heat exchanger temperature change model. A determination module is used to determine the relationship between the turbine inlet air temperature and the work done per unit mass of air through the turbine based on the mathematical model, and to determine the relationship between the output power and mass flow rate of the megawatt compressed air energy storage system based on the turbine outlet air temperature and the work done per unit mass of air through the turbine.

[0030] A third aspect of this application provides an electronic device, including: a memory, a processor, and a computer program stored in the memory and executable on the processor. The processor executes the program to implement the method for suppressing low-frequency oscillations in megawatt compressed air energy storage as described in the above embodiments.

[0031] A fourth aspect of this application provides a computer-readable storage medium having a computer program stored thereon, which is executed by a processor to implement the method for suppressing low-frequency oscillations in megawatt compressed air energy storage as described in the above embodiments.

[0032] Therefore, this application has the following beneficial effects:

[0033] This application embodiment can obtain the compressor speed difference increment when the power system experiences low-frequency oscillations, and input it into an additional damping control model to generate an adjustment command for the gas storage mass flow rate. Combined with the rated mass flow rate, an opening valve control model is used to determine the target opening of the regulating valve, thereby accurately controlling the actual mass flow rate of the gas storage. The compressed air with the adjusted actual mass flow rate from the gas storage is then heated by a heater before entering the turbine to perform work. The turbine power is adjusted based on the turbine's output power and mass flow rate. Thus, by estimating and compensating for system disturbances in real time, adaptive adjustment of the mass flow rate is achieved, thereby controlling the output power of compressed air energy storage. This improves the low-frequency oscillation problem of the power system, effectively suppresses low-frequency oscillations of the power grid, enhances power system damping, and improves the stability of the power system.

[0034] Additional aspects and advantages of this application will be set forth in part in the description which follows, and in part will be obvious from the description, or may be learned by practice of this application. Attached Figure Description

[0035] The above and / or additional aspects and advantages of this application will become apparent and readily understood from the following description of the embodiments taken in conjunction with the accompanying drawings, wherein:

[0036] Figure 1 This is a schematic diagram of the energy release process of a megawatt compressed air energy storage system according to an embodiment of this application;

[0037] Figure 2 This is a flowchart of a method for suppressing low-frequency oscillations in megawatt compressed air energy storage according to an embodiment of this application;

[0038] Figure 3 A block diagram of additional damping control for a megawatt compressed air energy storage system according to an embodiment of this application;

[0039] Figure 4 This is a diagram showing the relationship between the opening degree of a control valve and the mass flow rate according to an embodiment of this application.

[0040] Figure 5 This is an example diagram of a megawatt compressed air energy storage device for suppressing low-frequency oscillations according to an embodiment of this application;

[0041] Figure 6 This is a schematic diagram of the structure of an electronic device according to an embodiment of this application. Detailed Implementation

[0042] The embodiments of this application are described in detail below. Examples of the embodiments are shown in the accompanying drawings, wherein the same or similar reference numerals denote the same or similar elements or elements having the same or similar functions throughout. The embodiments described below with reference to the accompanying drawings are exemplary and intended to explain this application, and should not be construed as limiting this application.

[0043] The following describes a method, apparatus, and device for suppressing low-frequency oscillations in a megawatt-class compressed air energy storage system, with reference to the accompanying drawings. Addressing the problems mentioned in the background section, this application provides a method for suppressing low-frequency oscillations in a megawatt-class compressed air energy storage system. In this method, the incremental speed difference of the compressor during low-frequency oscillations in the power system is monitored and input into an additional damping control model to generate an adjustment command for the mass flow rate of the gas storage tank. Combined with the rated mass flow rate, an opening valve control model is used to determine the target opening of the regulating valve, thereby precisely controlling the actual mass flow rate of the gas storage tank. The compressed air with the adjusted actual mass flow rate from the gas storage tank is then heated by a heater before entering the turbine to perform work. The turbine power is adjusted based on the turbine's output power and mass flow rate. Thus, by estimating and compensating for system disturbances in real time, adaptive adjustment of the mass flow rate is achieved, thereby controlling the output power of the compressed air energy storage system. This improves the low-frequency oscillation problem in the power system, effectively suppresses low-frequency oscillations in the power grid, enhances power system damping, and improves the stability of the power system.

[0044] Before introducing this application, the megawatt-class compressed air energy storage system involved will be described, such as... Figure 1 As shown, the system mainly includes a compressor, a turbine, a heat exchanger, an air storage tank, and a regulating valve for the air storage tank. Energy conversion and utilization are achieved through multiple turbines and heat exchangers. When the megawatt-scale CAES releases energy, the flow rate of compressed air in the air storage tank is controlled by adjusting the opening degree L of the regulating valve. The compressed air then enters the heat exchanger for heating and generates electricity through the turbine.

[0045] Specifically, Figure 2 This is a schematic flowchart illustrating a method for suppressing low-frequency oscillations in megawatt compressed air energy storage, provided as an embodiment of this application.

[0046] like Figure 2 As shown, the method for suppressing low-frequency oscillations in a megawatt compressed air energy storage system includes the following steps:

[0047] In step S101, the speed difference increment of the compressor is obtained when the power system frequency oscillates at low frequency. The speed difference increment is input into the additional damping control model, and the additional damping control model outputs the adjustment command of the mass flow rate of the gas storage tank.

[0048] The additional damping control model includes an additional damping controller, which performs additional damping control on the speed difference increment through a gain circuit, a filtering circuit, a phase compensation circuit, and a limiting circuit.

[0049] It is understandable that when the power system frequency experiences low-frequency oscillations, the speed difference increment Δω is processed by additional damping control to obtain the regulation command ΔQ, dynamically adjusting the mass flow rate. The transfer function expression of the additional damping controller is as follows:

[0050]

[0051] Among them, K QS T WQS T 1QS T 2QS For the parameters of the additional damping controller, ΔQ is the adjustment command for the mass flow rate; ΔQ max Δω represents the maximum amplitude of the additional damping control output command, and Δω represents the speed difference increment.

[0052] In step S102, the rated mass flow rate when the megawatt compressed air energy storage system outputs rated power is obtained. The adjustment command of the mass flow rate and the rated command flow rate are input into the opening valve control model. The opening valve controls the target opening of the output regulating valve. According to the target opening, the regulating valve is controlled to adjust the actual mass flow rate of the gas storage tank. The compressed air with the actual mass flow rate after adjustment in the gas storage tank enters the heater for heating.

[0053] The valve opening control model includes a tracking differentiator, a linear expansion state observer, a linear state error feedback controller, an inertial element, and a limiting element. The control flow of the valve opening control model includes: adding the mass flow rate corresponding to the adjustment command to the rated command flow rate to obtain the desired output mass flow rate; dynamically filtering the signal of the desired output mass flow rate through the tracking differentiator to generate a smooth transient process signal; inputting the actual mass flow rate into the linear expansion state observer, which estimates the total disturbance of the megawatt-scale compressed air energy storage; inputting the transient process signal and the total disturbance into the linear state error feedback controller, which outputs a virtual control quantity; calculating the total control quantity based on the compensation coefficient of the total disturbance and the virtual control quantity; and adjusting the total control quantity through the inertial element and the limiting element to obtain the target opening of the regulating valve.

[0054] It is understood that the valve control model in this application uses LADRC (Linear Active Disturbance Rejection Control) technology to effectively suppress low-frequency oscillations in the system. For example... Figure 3 As shown, additional damping control and linear active disturbance rejection control technologies are combined to achieve precise control of valve opening. By adjusting the mass flow rate through the valve, the output power of compressed air energy storage is controlled, thereby suppressing low-frequency oscillations in the power grid.

[0055] Specifically, such as Figure 3 As shown in the embodiment of this application, the mass flow rate Q can be obtained when the CAES outputs a rated power of one megawatt. * The desired output mass flow rate Q is obtained by adding it to the mass flow rate adjustment command ΔQ. ref And the expected output mass flow rate Qref The signal is dynamically filtered by a tracking differentiator (TD controller) to generate a smooth transition signal r.

[0056] Furthermore, embodiments of this application can convert the actual mass flow rate Q... m As input, the total disturbances of the megawatt compressed air energy storage system (such as mass flow fluctuations caused by pressure fluctuations in the gas storage tank and changes in valve friction coefficients) are estimated in real time using LESO (Linear Extended State Observer), and unknown disturbances and nonlinear factors in the system are compensated.

[0057] Furthermore, in this embodiment, the transient process signal r generated by the TD controller and the system states estimated by LESO can be linearly combined through a linear state error feedback controller (LSEF controller) to obtain a virtual control quantity u0. This virtual control quantity u is then obtained by combining the compensation coefficient b0 of the total system disturbance. The total control quantity u needs to be adjusted through inertial and limiting elements to adapt to the dynamic characteristics and operational limitations of the physical actuator (such as a regulating valve). The processed total control quantity determines the target opening of the regulating valve, achieving precise control of the mass flow rate in the compressed air energy storage system, thereby suppressing low-frequency oscillations in the power grid.

[0058] Therefore, the control method of the opening valve control model in this application utilizes a topologically simple tracking differentiator and a linearly extended state observer to achieve real-time decoupled estimation of the total system disturbance. Furthermore, the control architecture based on a linear state error feedback rate possesses both strong robustness and decoupling capability, effectively addressing the dynamic characteristics of nonlinear, strongly coupled, time-varying, and uncertain systems. This not only improves the adaptability to nonlinear disturbances under complex operating conditions but also provides a strong guarantee for the safe and reliable operation of power systems.

[0059] In this embodiment, the control algorithm of the valve opening control model is as follows:

[0060]

[0061] Where r is the transient signal generated by the tracking differentiator, and k p k d β1, β2, and β3 are the gain of the linear state error feedback; β1, β2, and β3 are the parameters of the linear extended state observer error feedback gain matrix; z is the state vector of the linear extended state observer; y is the actual mass flow rate of the output; u is the total control quantity; and u0 is the virtual control quantity.

[0062] In step S103, based on the relationship between the output power and mass flow rate of the megawatt compressed air energy storage system, the power increment corresponding to the actual mass flow rate is determined, and the turbine power is adjusted based on the power increment. The turbine drives the compressor to output active power based on the heated compressed air.

[0063] It is understood that the embodiments of this application obtain the power increment ΔP through the relationship between the turbine's output power P and mass flow rate Q, adjust the turbine's output power, drive the synchronous generator of the megawatt CAES to output active power, suppress low-frequency oscillations in the power system, enhance power system damping, and improve the stability of the power system.

[0064] The relationship between the turbine's output power and mass flow rate is as follows:

[0065]

[0066] In one embodiment of this application, before determining the power increment corresponding to the actual mass flow rate based on the relationship between the output power and mass flow rate of the megawatt compressed air energy storage system, the method further includes: establishing a mathematical model of the megawatt compressed air energy storage system, wherein the mathematical model includes a pressure and temperature change model in the gas storage tank, a relationship between the opening degree of the regulating valve and the mass flow rate, and a heat exchanger temperature change model; determining the relationship between the turbine inlet air temperature and the work done by a unit mass of air through the turbine based on the mathematical model; and determining the relationship between the output power and mass flow rate of the megawatt compressed air energy storage system based on the turbine outlet air temperature and the work done by a unit mass of air through the turbine.

[0067] It is understood that the mathematical model of the megawatt-class CAES system in this application includes a pressure and temperature change model within the gas storage tank, a relationship between the regulating valve opening and mass flow rate, and a heat exchanger temperature change model. The pressure and temperature change model within the gas storage tank, based on the laws of conservation of mass and energy, establishes a model of pressure and temperature changes within the gas storage tank during the energy release phase, which helps ensure the safe and stable operation of the gas storage tank while suppressing low-frequency oscillations in the power grid. The relationship between the regulating valve opening and mass flow rate is crucial for accurately controlling the mass flow rate entering the turbine, thus affecting the output characteristics of the entire system. The heat exchanger temperature change model considers the change in air temperature after reheating at each stage of the heat exchanger during the energy release process, ensuring that the turbine can stably output the required power and improve overall efficiency. Specifically:

[0068] 1) Establish a model of pressure and temperature changes inside the gas storage facility to ensure the safety and stability of the gas storage facility when the megawatt CAES suppresses low-frequency oscillations in the power grid.

[0069] In this embodiment, the storage of high-pressure gas in the gas storage tank is assumed to be a constant-volume process, and the air is considered to be in an ideal state. According to the laws of conservation of mass and energy, the expressions for the pressure and temperature changes within the gas storage tank during the energy release phase are as follows:

[0070]

[0071] Among them, T ac P is the temperature inside the gas storage facility. ac V represents the pressure inside the gas storage facility. ac The volume of the gas storage facility is m. ac The air quality inside the gas storage facility; c p For the specific heat ratio at constant pressure, c v For constant volume heat ratio, R g U is the ideal gas constant; ac T is the heat transfer coefficient between the gas storage facility and the environment. en A represents the ambient temperature; Q represents the mass flow rate at the valve opening; A represents the mass flow rate at the control valve opening. ac This refers to the heat exchange area.

[0072] 2) Establish the relationship between the control valve opening and the mass flow rate, such as... Figure 4 As shown.

[0073] Assuming that the mass flow rate Q at the rated output power of a 1,000 kW CAES is only related to the valve opening L, and the valve opening is expressed as a percentage, the relationship between the valve opening and the mass flow rate can be approximated as an exponential function. The expression for the mass flow rate Q and the valve opening L is as follows:

[0074]

[0075] In the formula, Q(L) is the mass flow rate corresponding to the opening degree L of the regulating valve; Q max L represents the maximum mass flow rate of the control valve. max R represents the maximum opening of the regulating valve; R is the ratio of the maximum mass flow rate to the minimum mass flow rate.

[0076] 3) Establish a model of heat exchanger temperature changes to ensure the turbine can output the required power stably.

[0077] During energy release, the air temperature after reheating in each heat exchanger stage is:

[0078]

[0079] In the formula, i represents the turbine series; The input temperature for each stage of the heater; ε is the output temperature of the turbine; e Let be the heat exchange efficiency of the heat exchanger, which is a constant.

[0080] The expressions for the turbine outlet air temperature and the work done per unit mass of air through the turbine are:

[0081]

[0082] In the formula, k is the specific heat capacity of ideal air; c p β is the specific heat capacity ratio of air at constant pressure; e,i η represents the expansion ratio at each stage. e For turbine efficiency; This refers to the inlet temperature of each turbine stage.

[0083] The output power expression for a megawatt CAES is:

[0084]

[0085] When c p , k、η e When constant, the output power of a megawatt CAES is w all It has a linear relationship with the mass flow rate Q, that is, the mass flow rate Q is adjusted by regulating the valve opening L, and thus the total power of the turbine is adjusted.

[0086] In summary, the LADRC-based method for suppressing low-frequency oscillations in a megawatt-scale compressed air energy storage system (CAES) of this application establishes a mathematical model of compressed air energy storage and analyzes the impact of mass flow rate on its output power. Secondly, it analyzes the feasibility of using compressed air energy storage to suppress low-frequency oscillations and proposes a LADRC-based method for suppressing low-frequency oscillations in a megawatt-scale CAES system. This method adjusts the mass flow rate through the LADRC control algorithm, thereby controlling the output power of the compressed air energy storage system and suppressing low-frequency oscillations in the power grid. Compared to traditional PI control, the LADRC control strategy has superior dynamic response characteristics, improving the stability of the megawatt-scale CAES system. A specific application of this method is described in detail below, with the following steps:

[0087] (1) Build a classic 4-machine two-area power system model and connect it to the megawatt CAES system.

[0088] (2) Set up a low-frequency oscillation fault, compare the traditional PI control and LADRC control strategies, analyze the duration and amplitude of active power oscillation in the inter-regional transmission line under the two control strategies, and verify that the LADRC control strategy has better dynamic response characteristics.

[0089] (3) After the low-frequency oscillation occurs, the output active power curve and rotor speed characteristic curve of the megawatt CAES generator under the two control strategies are analyzed to verify that the LADRC control strategy has better output characteristics than the PI control strategy, which effectively improves the stability of the megawatt CAES system.

[0090] The method for suppressing low-frequency oscillations in megawatt compressed air energy storage proposed in this application involves monitoring the incremental difference in compressor speed during low-frequency oscillations in the power system and inputting it into an additional damping control model to generate an adjustment command for the mass flow rate of the gas storage tank. Combined with the rated mass flow rate, an opening valve control model is used to determine the target opening of the regulating valve, thereby precisely controlling the actual mass flow rate of the gas storage tank. The compressed air with the adjusted actual mass flow rate from the gas storage tank is then heated by a heater before entering the turbine to perform work. The turbine power is adjusted based on the turbine's output power and mass flow rate. Thus, by estimating and compensating for system disturbances in real time, adaptive adjustment of the mass flow rate is achieved, thereby controlling the output power of the compressed air energy storage to improve the low-frequency oscillation problem in the power system, effectively suppressing low-frequency oscillations in the power grid, enhancing power system damping, and improving power system stability.

[0091] Next, referring to the accompanying drawings, a megawatt compressed air energy storage device for suppressing low-frequency oscillations according to an embodiment of this application is described.

[0092] Figure 5 This is a block diagram of a megawatt compressed air energy storage device for suppressing low-frequency oscillations according to an embodiment of this application.

[0093] like Figure 5 As shown, the megawatt compressed air energy storage device 10 for suppressing low-frequency oscillations includes: an acquisition module 100, a control module 200, and a processing module 300.

[0094] The acquisition module 100 is used to acquire the speed difference increment of the compressor when the power system frequency oscillates at low frequency. The speed difference increment is input into the additional damping control model, and the additional damping control model outputs the adjustment command of the mass flow rate of the gas storage tank. The control module 200 is used to acquire the rated mass flow rate when the megawatt compressed air energy storage system outputs rated power. The adjustment command of the mass flow rate and the rated command flow rate are input into the opening valve control model. The opening valve control outputs the target opening of the regulating valve. According to the target opening, the regulating valve controls the actual mass flow rate of the gas storage tank. The compressed air with the actual mass flow rate after adjustment in the gas storage tank enters the heater for heating. The processing module 300 is used to determine the power increment corresponding to the actual mass flow rate based on the relationship between the turbine's output power and the mass flow rate. The turbine power is adjusted based on the power increment. The turbine drives the compressor to output active power based on the heated compressed air.

[0095] In one embodiment of this application, the additional damping control model includes an additional damping controller, which performs additional damping control on the speed difference increment through a gain circuit, a filtering circuit, a phase compensation circuit, and a limiting circuit.

[0096] In one embodiment of this application, the transfer function expression of the additional damping controller is:

[0097]

[0098] Among them, K QS T WQS T 1QS T 2QS Here are the controller parameters; ΔQ is the mass flow rate adjustment command; ΔQ max Δω represents the maximum amplitude of the additional damping control output command, and Δω represents the speed difference increment.

[0099] In one embodiment of this application, the valve opening control model includes a tracking differentiator, a linear expansion state observer, a linear state error feedback controller, an inertial element, and a limiting element. The control flow of the valve opening control model includes: adding the mass flow rate corresponding to the adjustment command to the rated command flow rate to obtain the desired output mass flow rate; dynamically filtering the signal of the desired output mass flow rate through the tracking differentiator to generate a smooth transition process signal; inputting the actual mass flow rate into the linear expansion state observer, which estimates the total disturbance of the megawatt-scale compressed air energy storage; inputting the transition process signal and the total disturbance into the linear state error feedback controller, which outputs a virtual control quantity; calculating the total control quantity based on the compensation coefficient of the total disturbance and the virtual control quantity; and adjusting the total control quantity through the inertial element and the limiting element to obtain the target opening of the regulating valve.

[0100] In one embodiment of this application, the control algorithm of the opening valve control model is as follows:

[0101]

[0102] Where r is the transient signal generated by the tracking differentiator, and k p k d β1, β2, and β3 are the gain of the linear state error feedback; β1, β2, and β3 are the parameters of the linear extended state observer error feedback gain matrix; z is the state vector of the linear extended state observer; y is the actual mass flow rate of the output; u is the total control quantity; and u0 is the virtual control quantity.

[0103] In one embodiment of this application, the relationship between the output power and mass flow rate of the megawatt compressed air energy storage system is as follows:

[0104]

[0105] Among them, w all The output power of the megawatt compressed air energy storage system is given by η, where Q is the mass flow rate at the regulating valve opening. e Let k be the turbine's output efficiency, k be the ideal air specific heat capacity, and w be the output efficiency. e,j Let i be the output power of the j-th stage turbine, i be the turbine stage number, and c be the output power of the j-th stage turbine. p The specific heat ratio at constant pressure Let β be the inlet temperature of the j-th stage heater. e,j The expansion ratio of the jth order.

[0106] In one embodiment of this application, the megawatt compressed air energy storage device 10 for suppressing low-frequency oscillations further includes: a modeling module, used to establish a mathematical model of the megawatt compressed air energy storage system before determining the power increment corresponding to the actual mass flow rate based on the relationship between the output power and mass flow rate of the megawatt compressed air energy storage system, wherein the mathematical model includes a pressure and temperature change model in the gas storage tank, a relationship between the opening degree of the regulating valve and the mass flow rate, and a heat exchanger temperature change model; and a determination module, used to determine the relationship between the turbine inlet air temperature and the work done by a unit mass of air through the turbine based on the mathematical model, and to determine the relationship between the output power and mass flow rate of the megawatt compressed air energy storage system based on the turbine outlet air temperature and the work done by a unit mass of air through the turbine.

[0107] It should be noted that the foregoing explanation of the embodiment of the method for suppressing low-frequency oscillations in megawatt compressed air energy storage also applies to the megawatt compressed air energy storage device for suppressing low-frequency oscillations in this embodiment, and will not be repeated here.

[0108] According to the embodiment of this application, the megawatt compressed air energy storage device for suppressing low-frequency oscillations acquires the incremental difference in compressor speed when the power system experiences low-frequency oscillations, and inputs this information into an additional damping control model to generate an adjustment command for the mass flow rate of the gas storage tank. Combined with the rated mass flow rate, an opening valve control model is used to determine the target opening of the regulating valve, thereby precisely controlling the actual mass flow rate of the gas storage tank. The compressed air with the adjusted actual mass flow rate from the gas storage tank is then heated by a heater before entering the turbine to perform work. The turbine power is adjusted based on the turbine's output power and mass flow rate. Thus, by estimating and compensating for system disturbances in real time, adaptive adjustment of the mass flow rate is achieved, thereby controlling the output power of the compressed air energy storage to improve the low-frequency oscillation problem in the power system, effectively suppressing low-frequency oscillations in the power grid, enhancing power system damping, and improving power system stability.

[0109] Figure 6 A schematic diagram of the structure of an electronic device provided in an embodiment of this application. The electronic device may include:

[0110] The memory 601, the processor 602, and the computer program stored on the memory 601 and capable of running on the processor 602.

[0111] When the processor 602 executes the program, it implements the method for suppressing low-frequency oscillations in megawatt compressed air energy storage provided in the above embodiments.

[0112] Furthermore, electronic devices also include:

[0113] Communication interface 603 is used for communication between memory 601 and processor 602.

[0114] The memory 601 is used to store computer programs that can run on the processor 602.

[0115] The memory 601 may include high-speed RAM (Random Access Memory) memory, and may also include non-volatile memory, such as at least one disk storage.

[0116] If the memory 601, processor 602, and communication interface 603 are implemented independently, then the communication interface 603, memory 601, and processor 602 can be interconnected via a bus to complete communication between them. The bus can be an ISA (Industry Standard Architecture) bus, a PCI (Peripheral Component Interconnect) bus, or an EISA (Extended Industry Standard Architecture) bus, etc. The bus can be divided into address bus, data bus, control bus, etc. For ease of representation, Figure 6 The bus is represented by a single thick line, but this does not mean that there is only one bus or one type of bus.

[0117] Optionally, in a specific implementation, if the memory 601, processor 602, and communication interface 603 are integrated on a single chip, then the memory 601, processor 602, and communication interface 603 can communicate with each other through an internal interface.

[0118] The processor 602 may be a CPU (Central Processing Unit), an ASIC (Application Specific Integrated Circuit), or one or more integrated circuits configured to implement the embodiments of this application.

[0119] This application also provides a computer-readable storage medium storing a computer program thereon, which, when executed by a processor, implements the above-described method for suppressing low-frequency oscillations in megawatt compressed air energy storage.

[0120] In the description of this specification, the references to terms such as "one embodiment," "some embodiments," "example," "specific example," or "some examples," etc., indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of this application. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples. Moreover, without contradiction, those skilled in the art can combine and integrate the different embodiments or examples described in this specification, as well as the features of different embodiments or examples.

[0121] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include at least one of that feature. In the description of this application, "N" means at least two, such as two, three, etc., unless otherwise explicitly specified.

[0122] Any process or method described in the flowchart or otherwise herein can be understood as representing a module, segment, or portion of code comprising one or N executable instructions for implementing custom logic functions or processes, and the scope of the preferred embodiments of this application includes additional implementations in which functions may be performed not in the order shown or discussed, including substantially simultaneously or in reverse order depending on the functions involved, as should be understood by those skilled in the art to which embodiments of this application pertain.

[0123] It should be understood that various parts of this application can be implemented using hardware, software, firmware, or a combination thereof. In the above embodiments, steps or methods can be implemented using software or firmware stored in memory and executed by a suitable instruction execution system. For example, if implemented in hardware, as in another embodiment, it can be implemented using any of the following techniques known in the art, or a combination thereof: discrete logic circuits having logic gates for implementing logical functions on data signals, application-specific integrated circuits (ASICs) having suitable combinational logic gates, programmable gate arrays (FPGAs), field-programmable gate arrays (FPGAs), etc.

[0124] Those skilled in the art will understand that all or part of the steps of the methods implementing the above embodiments can be implemented by a program instructing related hardware. The program can be stored in a computer-readable storage medium, and when executed, the program includes one or a combination of the steps of the method embodiments.

[0125] Although embodiments of this application have been shown and described above, it is understood that the above embodiments are exemplary and should not be construed as limiting this application. Those skilled in the art can make changes, modifications, substitutions and variations to the above embodiments within the scope of this application.

Claims

1. A method for suppressing low-frequency oscillations in megawatt compressed air energy storage, characterized in that, A megawatt-class compressed air energy storage system includes a compressor, a turbine, a heat exchanger, an air storage tank, and a regulating valve for the air storage tank. The method includes the following steps: The speed difference increment of the compressor is obtained when the power system frequency oscillates at a low frequency. The speed difference increment is input into the additional damping control model, and the additional damping control model outputs the adjustment command of the mass flow rate of the gas storage tank. The rated mass flow rate when the megawatt compressed air energy storage system outputs rated power is obtained. The adjustment command of the mass flow rate and the rated command flow rate are input into the opening valve control model. The opening valve control model outputs the target opening of the regulating valve. According to the target opening, the regulating valve is controlled to adjust the actual mass flow rate of the gas storage tank. The compressed air with the actual mass flow rate after adjustment by the gas storage tank enters the heater for heating. The opening valve control model includes a tracking differentiator, a linear expansion state observer, a linear state error feedback controller, an inertial element, and a limiting element. Based on the relationship between the output power and mass flow rate of the megawatt compressed air energy storage system, the power increment corresponding to the actual mass flow rate is determined, and the turbine power is adjusted based on the power increment. The turbine drives the compressor to output active power based on the heated compressed air.

2. The method for suppressing low-frequency oscillations in megawatt compressed air energy storage according to claim 1, characterized in that, The control flow of the valve opening control model includes: The desired output mass flow rate is obtained by adding the mass flow rate corresponding to the adjustment command and the rated command flow rate. The signal of the desired output mass flow rate is then dynamically filtered through a tracking differentiator to generate a smooth transition process signal. The actual mass flow rate is input into the linear expansion state observer, which estimates the total disturbance of the megawatt compressed air energy storage. The transient process signal and the total disturbance are input into the linear state error feedback controller, which outputs a virtual control quantity. The total control quantity is calculated based on the compensation coefficient of the total disturbance and the virtual control quantity. The total control quantity is then adjusted by the inertial element and the limiting element to obtain the target opening degree of the regulating valve.

3. The method for suppressing low-frequency oscillations in megawatt compressed air energy storage according to claim 1 or 2, characterized in that, The control algorithm for the valve opening control model is as follows: Where r is the transient signal generated by the tracking differentiator, and k p k d β1, β2, and β3 are the gain of the linear state error feedback; β1, β2, and β3 are the parameters of the linear extended state observer error feedback gain matrix; z is the state vector of the linear extended state observer; y is the actual mass flow rate of the output; u is the total control quantity; and u0 is the virtual control quantity.

4. The method for suppressing low-frequency oscillations in megawatt compressed air energy storage according to claim 1, characterized in that, The additional damping control model includes an additional damping controller, which performs additional damping control on the speed difference increment through a gain circuit, a filtering circuit, a phase compensation circuit, and a limiting circuit.

5. The method for suppressing low-frequency oscillations in megawatt compressed air energy storage according to claim 4, characterized in that, The transfer function expression of the additional damping controller is: Among them, K QS T WQS T 1QS T 2QS For the additional damping controller parameters, ΔQ is the adjustment command for the mass flow rate. max Δω represents the maximum amplitude of the additional damping control output command, and Δω represents the speed difference increment.

6. The method for suppressing low-frequency oscillations in megawatt compressed air energy storage according to claim 1, characterized in that, The relationship between the output power and mass flow rate of the turbine is as follows: Among them, w all The output power of the megawatt compressed air energy storage system is given by η, where Q is the mass flow rate at the regulating valve opening. e Let k be the turbine's output efficiency, k be the ideal air specific heat capacity, and w be the output efficiency. e,j Let i be the output power of the j-th stage turbine, i be the turbine stage number, and c be the output power of the j-th stage turbine. p The specific heat ratio at constant pressure Let β be the inlet temperature of the j-th stage heater. e,j The expansion ratio of the jth order.

7. The method for suppressing low-frequency oscillations in megawatt compressed air energy storage according to claim 1, characterized in that, Before determining the power increment corresponding to the actual mass flow rate based on the relationship between the output power and mass flow rate of the megawatt compressed air energy storage system, the process also includes: A mathematical model of the megawatt compressed air energy storage system is established, wherein the mathematical model includes a pressure and temperature change model in the gas storage tank, a relationship between the opening degree of the regulating valve and the mass flow rate, and a heat exchanger temperature change model. Based on the mathematical model, the relationship between the turbine inlet air temperature and the work done by a unit mass of air through the turbine is determined. Based on the relationship between the turbine outlet air temperature and the work done by a unit mass of air through the turbine, the relationship between the turbine output power and the mass flow rate is determined.

8. A megawatt compressed air energy storage device for suppressing low-frequency oscillations, characterized in that, A megawatt-class compressed air energy storage system includes a compressor, a turbine, a heat exchanger, an air storage tank, and a regulating valve for the air storage tank, wherein the device includes: The acquisition module is used to acquire the speed difference increment of the compressor when the power system frequency experiences low-frequency oscillations, input the speed difference increment into the additional damping control model, and the additional damping control model outputs an adjustment command for the mass flow rate of the gas storage tank. The control module is used to obtain the rated mass flow rate when the megawatt compressed air energy storage system outputs rated power, input the adjustment command of the mass flow rate and the rated command flow rate into the opening valve control model, the opening valve control outputs the target opening of the regulating valve, and controls the regulating valve to adjust the actual mass flow rate of the gas storage tank according to the target opening, and the compressed air with the actual mass flow rate after adjustment by the gas storage tank enters the heater for heating; The processing module is used to determine the power increment corresponding to the actual mass flow rate based on the relationship between the output power and mass flow rate of the turbine, and to adjust the power of the turbine based on the power increment. The turbine drives the compressor to output active power based on the heated compressed air.

9. An electronic device, characterized in that, include: A memory, a processor, and a computer program stored in the memory and executable on the processor, the processor executing the program to implement the method for suppressing low-frequency oscillations in megawatt compressed air energy storage as described in any one of claims 1-7.

10. A computer-readable storage medium having a computer program or instructions stored thereon, characterized in that, When the computer program or instructions are executed, they implement the method for suppressing low-frequency oscillations in megawatt compressed air energy storage as described in any one of claims 1-7.

Images