Compressed air energy storage excitation side control system and control method thereof

Abstract

The present invention relates to the technical field of stable control of electric energy storage technology, and specifically to a control system for the excitation side of compressed air energy storage. It includes a flexible excitation system power unit, an upper control unit and a bottom control unit. An output signal that can reflect the stability of the system is selected; the mathematical model of the system to be studied is accurately feedback linearized; the order of the extended state observer is determined; the output of the extended state observer and the output of the tracking differentiator are used as input signals, and the intermediate control variables are obtained through optimal control or pole configuration; the control command values ​​of the excitation voltage and the injected reactive power are obtained according to the matrix determined by the accurate feedback linearization and the disturbance signal observed by the extended state observer; the actual output of the system tracks the command value through chopping control and dq decoupling control. It can effectively improve the anti-disturbance capability, robustness and stable control capability of the compressed air energy storage excitation system, and can effectively enhance its competitive advantage in the auxiliary service market of the new energy grid-connected system.

Description

Technical Field

[0001] The present invention relates to the technical field of stable control of electric energy storage technology, and in particular to a compressed air energy storage excitation side control system. Background Art

[0002] In recent years, with the increase in electricity demand, the scale of grid connection of new energy such as photovoltaic and wind power has increased. On the one hand, new energy such as photovoltaic and wind power has inherent characteristics such as intermittent and volatile, and the problem of new energy consumption is prominent. Energy storage is an effective means to solve the time and space imbalance of electricity supply and demand and realize energy space-time transfer. On the other hand, large-scale renewable energy is connected to the power system with the help of power electronic devices, which changes the structure of the power grid, affects the electromechanical oscillation mode of the power system, and also weakens the system damping and reduces the system stability.

[0003] In the field of energy storage systems, compressed air energy storage (CAES) has attracted widespread attention due to its large storage scale, strong flexibility, and development and utilization not restricted by geographical location. The compressed air energy storage system can not only smooth out the fluctuations in the output of new energy, and comprehensively absorb new energy in the form of multiple energy flows (electricity, heat, and cold), but also has the potential to provide various auxiliary services for the power system. At present, the research on compressed air energy storage systems involves system structure improvement, heat recovery and utilization, improvement of multi-energy flow utilization efficiency, control and application in power systems, compressed air energy storage system power generation mode and operation control. In the field of power generation and operation control of compressed air energy storage systems, some studies have proposed that the compressed air energy storage system based on synchronous generators adopts a flexible excitation system based on high-power power electronic devices to improve the compressed air energy storage system's strong excitation capability, ms-level fast reactive voltage support capability, stable control margin and other auxiliary control capabilities, and further enhance its competitive advantage in the auxiliary service market.

[0004] For the control of flexible excitation system, some studies have proposed to use linear optimal control algorithm, lead-lag phase compensation method, nonlinear control based on multivariable feedback linearization and other methods to control the excitation voltage and reactive power injected into the generator. In the existing methods, the lead-lag phase compensation algorithm is designed for dual channels separately, and the coordination between the dual controllers is poor. Both linear optimal control and nonlinear control based on multivariable feedback linearization can achieve natural coordination of dual damping controllers to make the power system have good dynamic characteristics, but the robustness of linear optimal control is relatively poor. Nonlinear control takes into account the nonlinear characteristics of the power system, and the robustness is improved. However, for the compressed air energy storage system that is dedicated to improving the new energy consumption capacity and matching the setting, it is necessary to consider the impact of new energy fluctuations, load disturbances and other system disturbances.

[0005] Based on this, it is necessary to study a stable control method for the flexible excitation system in a compressed air energy storage system that can improve anti-disturbance capability and has strong robustness and stable control capabilities, so as to enhance its competitive advantage in the new energy grid-connected auxiliary service market. Summary of the invention

[0006] The purpose of the present invention is to address the defects of the prior art and provide a compressed air energy storage excitation side control system, which can improve the anti-disturbance capability, robustness and stable control capability of the compressed air energy storage excitation system, and enhance its competitive advantage in the auxiliary service market of new energy grid-connected systems.

[0007] The present invention provides a compressed air energy storage excitation side control system for a compressed air energy storage system, comprising a flexible excitation system power unit, an upper control unit and a lower control unit;

[0008] The flexible excitation system power unit includes an AC LC filter, a rectifier, a voltage stabilizing capacitor and a chopper which are sequentially connected between the excitation transformer and the excitation winding. The control variable of the flexible excitation system power unit is the excitation voltage E fd The reactive power Q injected into the generator by the excitation system C ;

[0009] The upper control unit includes a first control channel and a second control channel for controlling the excitation voltage and reactive power injected by the excitation system, respectively. The first control channel and the second control channel both include a tracking differentiator, a nonlinear controller and an extended state observer. The first control channel outputs a control variable command value E fdref To the chopper controller of the bottom control unit, the second control channel outputs the reactive current command value I sqref A dq decoupling controller to the bottom control unit;

[0010] The bottom control unit includes a chopper controller, a dq decoupling controller and a PI regulator;

[0011] The chopper controller is used to control the variable command value E according to the fdref Generate a switching signal to control the chopper to obtain the required excitation voltage E fd ;

[0012] The PI regulator is used to perform PI regulation according to a given voltage to obtain a current command value I sdref ;

[0013] The dq decoupling controller is used to input the reactive current command value I sqref and active current command value I sdref Realize double closed-loop control of the rectifier.

[0014] Preferably, the dual closed-loop control includes a voltage outer loop control and a current inner loop control, wherein the voltage outer loop control is used to provide a stable DC power supply for the chopper, and the given voltage input to the PI regulator in the voltage outer loop control is a reference voltage U dcref .

[0015] Preferably, the current inner loop control in the double closed-loop control is a direct current control based on a dq synchronous rotating coordinate system, and the DC current control includes: sdref Perform active current control and follow the reactive current command value I sqref Perform reactive current control.

[0016] More preferably, the first control channel includes a first tracking differentiator, a first linear control module and a first extended state observer; the second control channel includes a second tracking differentiator, a second linear control module and a second extended state observer.

[0017] The present invention also provides a control method for a compressed air energy storage excitation side control system, comprising performing upper-level control based on an active disturbance rejection control algorithm, wherein the upper-level control comprises:

[0018] Select the output signals y1 and y2 of the control and determine the reference value y of the two output signals 1ref and 2ref , as input signals of the first tracking differentiator and the second tracking differentiator respectively;

[0019] Establish a mathematical model of compressed air energy storage system based on flexible excitation system;

[0020] Based on the selected output signal and the mathematical model of the compressed air energy storage system, an accurate feedback linearization model of the system is established, and the relative orders r1 and r2 of the output signals y1 and y2 are determined;

[0021] According to the relative orders r1 and r2, determining the orders of the output signals y1 and y2 corresponding to the first extended state observer and the second extended state observer;

[0022] The output of the extended state observer and the output of the tracking differentiator are used as input signals, and the intermediate control variables v1 and v2 are obtained through optimal control or pole configuration;

[0023] Subtract the intermediate control variables v1 and v2 from the output disturbance signals of the first extended state observer and the second extended state observer respectively, and then transform them into -1 , get the control variable command value E fdref and Q′ Cref .

[0024] Preferably, the control variable command value Q′ is obtained CrefAfter that, select the reference axis direction, u q =0,u d =1, through the formula Q′ Cref Calculate and get the reactive current command value I sqref .

[0025] Preferably, the mathematical model of the compressed air energy storage system is:

[0026]

[0027] in,

[0028] x TL =x T +x L

[0029] x′ dv = x′ d +x TL

[0030] x d∑ =x d +x TL

[0031] x q∑ =x q +x TL

[0032]

[0033] In the formula, x T is the transformer reactance, x L is the transmission line reactance, P m is the mechanical power, D is the damping coefficient, x q is the quadrature-axis synchronous reactance, x' d is the direct-axis transient reactance, x d is the synchronous reactance of the generator d axis, δ is the voltage between the q axis and the infinite busbar U s The angle of is the differential of δ, ω is the generator speed, is the differential of ω, U t is the generator terminal voltage, Q′ C is the reactive power control quantity, Q C is the actual value of injected reactive power, Q C The differential of U t is the generator terminal voltage, U s is the infinite bus voltage, E′ q is the generator q-axis transient potential, E′ qThe differential of d0 is the time constant of the field winding, T J is the rotor inertia time constant, T Q It is the equivalent time constant of reactive power injection link.

[0034] Preferably, the method of establishing an accurate feedback linearization model of the system based on the selected output signal and the mathematical model of the compressed air energy storage system, and determining the relative orders r1 and r2 of the output signals y1 and y2 includes:

[0035] Select the state variable as X = [δ ω E' q Q C ], E fd , Q′ C For the control variables, the output signals y1 and y2 are selected as variables that can reflect the stable operation state of the system, and the analysis system is systematized as follows:

[0036]

[0037] in,

[0038] The relative orders r1 and r2 of the outputs y1 and y2 are calculated.

[0039] Preferably, the output signals y1 and y2 correspond to the orders of the first extended state observer and the second extended state observer, respectively r1+1 and r2+1. The above formula can be transformed into the following standard form:

[0040]

[0041] Among them, f1(t) and f2(t) represent the disturbance signal and the response of the unmodeled characteristics of the system to the total disturbance.

[0042]

[0043] In the above formula, B(t) can be calculated by the common formula of the automatic disturbance rejection algorithm.

[0044] Preferably, the intermediate control variables v1 and v2 are respectively:

[0045]

[0046] e 11 =y 1ref -y1,e 21 =y 2ref -y2;

[0047] in, is the controller proportional coefficient, which can be obtained by linear optimal control or pole configuration method. for e11 The r1-1 order differential of for e 21 The r2-1 order differential of .

[0048] The command value E of the system control variable fdref , Q′ Cref It can be calculated by the following formula:

[0049]

[0050] Among them, f1(t) and f2(t) can be obtained by the state observer.

[0051] The beneficial effects of the present invention are:

[0052] 1. The system of the present invention includes a flexible excitation system power unit, an upper control unit and a bottom control unit, wherein the upper control unit includes a first control channel and a second control channel for controlling the excitation voltage and the reactive power injected by the excitation system, respectively, and the first control channel and the second control channel both include a tracking differentiator, a nonlinear controller and an extended state observer, and the bottom control unit includes a chopper controller, a dq decoupling controller and a PI regulator. By selecting an output signal that can reflect the stability of the system; performing precise feedback linearization on the mathematical model of the system to be studied; determining the order of the extended state observer; using the output of the extended state observer and the output of the tracking differentiator as input signals, and obtaining intermediate control variables through optimal control or pole configuration; obtaining the control command value of the excitation voltage and the reactive power injection according to the matrix determined by the precise feedback linearization and the disturbance signal observed by the extended state observer; and making the system actually output the tracking command value through chopper control and dq decoupling control. The present invention can effectively improve the anti-disturbance capability, robustness and stable control capability of the compressed air energy storage excitation system, and can effectively improve its competitive advantage in the auxiliary service market of the new energy grid-connected system.

[0053] 2. The compressed air energy storage system adopts a flexible excitation system based on fully controlled devices, which has stronger excitation capability, ms-level fast reactive voltage support capability, and stable control margin, which helps to enhance its competitive advantage in the new energy grid-connected auxiliary service market.

[0054] 3. The use of the anti-disturbance control algorithm can effectively suppress system disturbances and oscillations caused by new energy output, load changes, etc. BRIEF DESCRIPTION OF THE DRAWINGS

[0055] Figure 1 It is a schematic diagram of the connection principle of the present invention;

[0056] Figure 2 A schematic diagram of the connection principle of a preferred embodiment provided by the present invention.

[0057] In the figure: 1. flexible excitation system power unit, 2. upper control unit, 3. bottom control unit, 4. synchronous generator; 10. AC LC filter, 11. rectifier, 12. voltage stabilizing capacitor, 13. chopper; 21. first tracking differentiator, 22. second tracking differentiator, 23. nonlinear controller, 230-first linear control module, 231-second linear control module, 24. first extended state observer, 25. second extended state observer, 30. chopper controller, 31. dq decoupling controller, 32. PI regulator. DETAILED DESCRIPTION

[0058] In order to make the technical problems, technical solutions and beneficial effects to be solved by the present application more clearly understood, the present application is further described in detail below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present application and are not used to limit the present application.

[0059] In addition, the terms "first" and "second" are used for descriptive purposes only and should not be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of the features. In the description of this application, the meaning of "plurality" is two or more, unless otherwise clearly and specifically defined.

[0060] References to "one embodiment" or "some embodiments" etc. described in the specification of this application mean that one or more embodiments of the present application include specific features, structures or characteristics described in conjunction with the embodiment. Therefore, the statements "in one embodiment", "in some embodiments", "in some other embodiments", "in some other embodiments", etc. that appear in different places in this specification do not necessarily refer to the same embodiment, but mean "one or more but not all embodiments", unless otherwise specifically emphasized in other ways. The terms "including", "comprising", "having" and their variations all mean "including but not limited to", unless otherwise specifically emphasized in other ways. "Multiple" means "two or more".

[0061] A compressed air energy storage excitation side control system provided by the present invention aims to improve the auxiliary control capability of a compressed air energy storage system in a new energy grid-connected system through a compressed air energy storage system excitation controller.

[0062] In order to achieve the above-mentioned purpose, the technical solution adopted by the method for improving the auxiliary control capability of the compressed air energy storage system is:

[0063] like Figure 1As shown, the compressed air energy storage system adopts a structure based on a flexible excitation system (i.e., a compressed air energy storage system based on a flexible excitation system), and the control includes an upper-level control based on an anti-disturbance control algorithm and a lower-level control for converter control to achieve control of the system's dual control variables.

[0064] The compressed air energy storage system based on the flexible excitation system comprises:

[0065] The electric motor is powered by surplus electricity such as wind and solar power and is used to drive the compressor to compress the air;

[0066] The compressor is used to compress the air and convert the surplus electrical energy into pressure energy for storage;

[0067] Cold and heat storage equipment is used to store the heat energy generated during compression and the cold energy generated during expansion;

[0068] The expander expands the compressed air to do work and drives the generator to generate electricity;

[0069] Generator, the present invention adopts a synchronous generator, and its excitation system adopts a flexible excitation system based on a fully controlled device to realize the power generation process of the compressed air energy storage system;

[0070] The flexible excitation system power unit 1 includes an AC LC filter 10, a rectifier 11 based on a fully controlled device, a voltage-stabilizing capacitor 12, and a chopper 13 based on a fully controlled device. The flexible excitation system power unit 1 is powered by the generator end via the excitation transformer, and is connected in sequence via the excitation transformer, the AC LC filter 11, the rectifier 11, the voltage-stabilizing capacitor 12, the chopper 13, and the excitation winding. Since the flexible excitation system power unit 1 is used, while realizing conventional excitation control, it can control the reactive power injected into the generator end by the flexible excitation system power unit 1 to realize functions such as voltage support and auxiliary stability control. Therefore, the system control variables include the excitation voltage E fd , the reactive power Q injected into the generator end by the excitation system C .

[0071] The upper control unit based on the active disturbance rejection control algorithm comprises:

[0072] Tracking differentiator TD: Its input signal is the given output variable reference value, and the output tracks the input signal and the first-order, second-order and multi-order differential signals of the input signal respectively;

[0073] Extended State Observer (ESO): tracks the state and disturbance of the system using the system’s output signal y and input u.

[0074] The upper control unit 2 includes a first control channel and a second control channel for controlling the excitation voltage and reactive power injection of the excitation system, respectively. The first control channel and the second control channel both include a tracking differentiator, a nonlinear controller 23 and an extended state observer. The first control channel outputs a control variable command value E fdref To the chopper controller 30 of the bottom control unit, the second control channel outputs the reactive current command value I sqref The first control channel includes a first tracking differentiator 21, a first linear control module 230 and a first extended state observer 24; the second control channel includes a second tracking differentiator 22, a second linear control module 231 and a second extended state observer 25.

[0075] Nonlinear controller 23: Its input signal is the output signal of the tracking differentiator and the extended state observer.

[0076] The bottom control unit 3 of the control converter is used to realize the rectifier of the flexible excitation system using double closed-loop control. Among them, the voltage outer loop control is used to maintain the stability of the DC side capacitor voltage and provide a stable DC power supply for the chopper 13. The chopper 13 controls the generator excitation voltage according to the command value given by the self-disturbance rejection controller; the current inner loop adopts the direct current control method based on the dq synchronous rotating coordinate system to control the active power to maintain the stability of the DC side capacitor voltage, and control the reactive power to provide damping or voltage support for the power system. The active current control is performed according to the current command given by the voltage outer loop, and the reactive current control is performed according to the current command given by the self-disturbance rejection controller, so as to realize the decoupling control of the transmission of active power and reactive power between the flexible excitation system and the power system.

[0077] The steps of the upper control algorithm based on the active disturbance rejection control algorithm are:

[0078] 1) Select the output signals y1 and y2 of the control and determine the reference value y of the two output signals 1ref and 2ref , as the input signals of tracking differentiators TD1 and TD2 respectively;

[0079] 2) Establish a mathematical model of compressed air energy storage system based on flexible excitation system;

[0080] 3) Based on the selected output signal and the mathematical model of the system under study, an accurate feedback linearization model of the system is established, and the relative orders r1 and r2 of the outputs y1 and y2 are determined;

[0081] 4) According to the relative orders r1 and r2, determine the orders of the output signals y1 and y2 corresponding to the extended state observers 1 and 2;

[0082] 5) Taking the output of the extended state observer and the output of the tracking differentiator as input signals, the intermediate control variables v1 and v2 are obtained through optimal control or pole configuration;

[0083] 6) The intermediate control variables v1 and v2 are subtracted from the disturbance signals output by the extended state observers 1 and 2 respectively, and then transformed by the transformation matrix B -1 , get the excitation voltage E fd And the injected reactive conversion expression Q′ C The control command value.

[0084] Later, Q′ C Calculate the injected reactive current reference value I sqref , E fdref Generates switching signal to control chopper, I sqref and I obtained by stable DC voltage sdref The switching signal is generated through dq decoupling control to control the rectifier.

[0085] The mathematical model of the compressed air energy storage system based on the flexible excitation system is:

[0086]

[0087]

[0088] Select the state variable as X = [δ ω E' q Q C ], E fd , Q′ C To control the input, systematize it into a standard form, namely

[0089]

[0090] In the formula,

[0091]

[0092] Among them, x T is the main transformer reactance, x L is the transmission line reactance, x q is the quadrature-axis synchronous reactance, x' d is the direct-axis transient reactance, x d is the synchronous reactance of the generator d axis, δ is the voltage between the q axis and the infinite busbar U s The angle, U t is the generator terminal voltage, Q′ C is the reactive power control quantity, Q C is the actual value of injected reactive power, U t is the generator terminal voltage, U s is the infinite bus voltage, E′q is the transient potential of the generator q axis, T′ d0 is the time constant of the field winding, T J is the rotor inertia time constant, T Q It is the equivalent time constant of reactive power injection link.

[0093] The precise feedback linearization model of the system is established. On the basis of selecting the output variables as y1 and y2 and determining the relative orders as r1 and r2, equation (1) is transformed into the following standard form:

[0094]

[0095] Among them, f1(t) and f2(t) represent the disturbance signal and the response of the unmodeled characteristics of the system to the total disturbance.

[0096]

[0097] B(t) in the formula (5) can be calculated using the common formula of the ADAS algorithm.

[0098] The v1 and v2 can be obtained by pole configuration or optimal control design.

[0099] e 11 =y 1ref -y1,e 21 =y 2ref -y2 (6)

[0100] but,

[0101]

[0102] As described above, the output signals y1 and y2 correspond to the orders of the extended state observer, which are r1+1 and r2+1, respectively.

[0103] The first tracking differentiator 21 uses the reference value y of the system output y1 1ref As input signal, output y 1ref The tracking signal c 11 ,y 1ref Differentiated tracking signal c 12 , ..., y 1ref The tracking signal c of the r1-1 order differential 1r1 .

[0104] The second tracking differentiator 22 uses the reference value y of the system output y2 2ref As input signal, output y 2ref The tracking signal c 21 ,y 2ref Differentiated tracking signal c 22 , ..., y 2refThe tracking signal c of the r2-1 order differential 2r2 .

[0105] The first extended state observer 24 takes the output signal y1 as an input signal and outputs the signal z 11 is the observed value of y1, and the output signal is z 1r1 is the observed value of the r1-1 order differential signal of y1, z 1(r1+1) is the observed value of the disturbance signal f1(t).

[0106] The second extended state observer 25 takes the output signal y2 as an input signal and outputs the signal z 21 is the observed value of y2, and the output signal is z 2r2 is the observed value of the r2-1 order differential signal of y2, z 2(r2+1) is the observed value of the disturbance signal f2(t).

[0107] The deviation signal e in equation (7) is 11 ,......,e 1r1 The output signal c of the first tracking differentiator 21 can be 11 ,......,c 1r1 The output signal z of the first extended state observer 24 11 ,......,z 1r1 Subtract the error signal e 21 ,......,e 2r2 The output signal c of the second tracking differentiator 22 can be 21 ,......,c 2r2 The output signal z of the second extended state observer 25 21 ,......,z 2r2 Subtract and get.

[0108] The deviation signal e 11 ,......,e 1r1 The intermediate control variable v1 is obtained through the first linear control of the first linear control module 230 .

[0109] The deviation signal e 21 ,......,e 2r2 The intermediate control variable v2 is obtained through the second linear control of the second linear control module 231 .

[0110] The proportional coefficient of the linear control can be obtained by linear optimal control or pole configuration method.

[0111] The intermediate control variables v1 and v2 are respectively subtracted from the disturbance signal z obtained by the extended state observer. 1(1+r1) 、z 2(2+r2) , through the transformation matrix B-1 , get the control variable command value E fdref , Q′ Cref .

[0112] The bottom control unit 3 for controlling the converter includes a chopper controller 30 , a dq decoupling controller 31 , and a PI regulator 32 .

[0113] The chopper controller 30 is configured to generate a signal according to the command value E fdref Controls the generator excitation voltage.

[0114] The dq decoupling control of the dq decoupling controller 31, that is, the rectifier 11 adopts double closed-loop control, wherein the voltage outer loop control maintains the stability of the DC side capacitor voltage and provides a stable DC power supply for the chopper 13; the current inner loop adopts a direct current control method based on the dq synchronous rotating coordinate system, according to the current command value I given by the voltage outer loop sdref Perform active current control according to the reactive current command value I sqref Reactive current control is carried out to achieve decoupling control of active power and reactive power transmission between the flexible excitation system and the power system.

[0115] Among them, when the reference axis direction is selected, so that u q =0,u d =1,I sqref The reference value is calculated by the following formula.

[0116]

[0117] Embodiment 1

[0118] Figure 2 Shows a preferred embodiment of the present application ( Figure 2 FIG. 1 shows a schematic diagram of the connection principle of a compressed air energy storage excitation side control system provided in the first embodiment of the present application. For the sake of convenience, only the part related to the present embodiment is shown, which is described in detail as follows:

[0119] A compressed air energy storage excitation side control system of this embodiment includes a compressed air energy storage system, a flexible excitation system power unit and a control structure.

[0120] The power unit 1 of the flexible excitation system includes an AC LC filter 10, a rectifier 11 based on a fully controlled device, a voltage stabilizing capacitor 12, and a chopper 13 based on a fully controlled device. The control structure includes an upper-level control based on an active disturbance rejection control algorithm and a lower-level control for controlling the converter. The active disturbance rejection control structure has two control channels for controlling the excitation voltage and the reactive power injected by the excitation system, and mainly includes: a tracking differentiator, a nonlinear controller 23, and an extended state observer.

[0121] A compressed air energy storage system based on a flexible excitation system is characterized by comprising:

[0122] The mechanical power P output by the expander m The synchronous generator 4 is driven to operate.

[0123] The excitation system of the synchronous generator 4 adopts a flexible excitation system based on fully controlled devices.

[0124] The flexible excitation system, wherein the flexible excitation system power unit 1 is composed of an AC LC filter 10 , a rectifier 11 , a voltage stabilizing capacitor 12 , and a chopper 13 .

[0125] The control variables of the flexible excitation system include the excitation voltage E fd The reactive power Q injected into the generator by the excitation system C .

[0126] The control structure of the flexible excitation system includes an upper-level control based on an anti-disturbance control algorithm and a lower-level control for controlling the converter.

[0127] The upper control unit 1 based on the active disturbance rejection control algorithm comprises:

[0128] A first tracking differentiator 21, a second tracking differentiator 22, a nonlinear controller 23, a first extended state observer 24, a second extended state observer 25 and a conversion link.

[0129] The nonlinear controller 23 includes a first linear control module 230, a second linear control module 231 and a transformation matrix B -1 232.

[0130] The state space equation of the upper control based on the active disturbance rejection control algorithm is:

[0131]

[0132] In the formula,

[0133]

[0134] Among them, x T is the main transformer reactance, x L is the transmission line reactance, x q is the quadrature-axis synchronous reactance, x' d is the direct-axis transient reactance, x d is the synchronous reactance of the generator d axis, δ is the voltage between the q axis and the infinite busbar U s The angle, U t is the generator terminal voltage, Q′ C is the reactive power control quantity, Q Cis the actual value of injected reactive power, U t is the generator terminal voltage, U s is the infinite bus voltage, E′ q is the transient potential of the generator q axis, T′ d0 is the time constant of the field winding, T J is the rotor inertia time constant, T Q It is the equivalent time constant of reactive power injection link.

[0135] Select the state variable as X = [δ ω E' q Q C ], E fd , Q′ C is the control input, and the output signal is the generator terminal voltage U t and power angle δ, the analysis system is transformed into the following formula:

[0136]

[0137] in,

[0138]

[0139] The relative orders of the outputs y1 and y2 are calculated to be r1=1 and r2=3.

[0140] According to the exact feedback linearization of nonlinear systems, the above expression is converted into a standard form, and we can get:

[0141]

[0142] Among them, f1(t) and f2(t) represent the disturbance signal and the response of the unmodeled characteristics of the system to the total disturbance.

[0143]

[0144] For the transformed system:

[0145]

[0146] In the formula (14), B(t) can be calculated using the common formula of the active disturbance rejection control algorithm.

[0147] The first tracking differentiator 21 uses the system output U t Reference value U tref As input signal, output U tref The tracking signal c 11 .

[0148] The second tracking differentiator 22 uses the reference value δ of the system output δ ref As input signal, the output δ refThe tracking signal c 21 , δ ref differential The tracking signal c 22 , δ ref The second-order differential The tracking signal c 23 .

[0149] The first extended state observer 24 outputs a signal U t As input signal, the output signal z 11 For U t The observed value, z 12 is the observed value of the disturbance signal.

[0150] The second extended state observer 25 takes the output signal δ as an input signal and outputs the signal z 21 is the observed value of δ, and the output signal z 22 for The observed value, output signal z 23 for The observed value, z 24 is the observed value of the disturbance signal.

[0151] The output signal c of the first tracking differentiator 21 11 The output signal z of the first extended state observer 24 11 Subtract and obtain the deviation signal e 11 .

[0152] The output signal c of the second tracking differentiator 22 21 , c 22 , c 23 The output signal z of the second extended state observer 25 21 , z 22 , z 23 Subtract and obtain the deviation signal e 21 , e 22 , e 23 .

[0153] The deviation signal e 11 The intermediate control variable v1 and the deviation signal e are obtained through the first linear control module 230. 21 , e 22 , e 23 The intermediate control variable v2 is obtained through the second linear control module 231, as shown below:

[0154] e 11 =U tref -U t ,e 21 =δ ref -δ (16)

[0155] but,

[0156]

[0157] The proportional coefficient of the linear control can be obtained by linear optimal control or pole configuration method.

[0158] The intermediate control variables v1 and v2 are respectively subtracted from the disturbance signal z obtained by the extended state observer. 12 、z 24 , through the transformation matrix B -1 , get the control variable command value E fdref , Q′ Cref .

[0159] Select the reference axis direction, u q =0,u d =1, and the reference value of the injected reactive current component is obtained according to the following formula.

[0160]

[0161] The rectifier adopts double closed-loop control, in which the voltage outer loop control is used to maintain the stability of the DC side capacitor voltage and provide a stable DC power supply for the chopper. The chopper fdref Control the generator excitation voltage; the current inner loop adopts the direct current control method based on the dq synchronous rotating coordinate system, according to the current command value I given by the voltage outer loop sdref Perform active current control according to the reactive current command value I sqref Reactive current control is carried out to achieve decoupling control of active power and reactive power transmission between the flexible excitation system and the power system.

[0162] It should be understood that the specific order or hierarchy of steps in the disclosed process is an example of an exemplary method. Based on design preferences, it should be understood that the specific order or hierarchy of steps in the process can be rearranged without departing from the scope of protection of the present disclosure. The attached method claims present the elements of the various steps in an exemplary order and are not intended to be limited to the specific order or hierarchy described.

[0163] In the above detailed description, various features are grouped together in a single embodiment to simplify the disclosure. This method of disclosure should not be interpreted as reflecting an intention that the embodiments of the claimed subject matter require more features than are clearly stated in each claim. On the contrary, as reflected in the appended claims, the invention is in a state of having less than all the features of the disclosed individual embodiments. Therefore, the appended claims are hereby expressly incorporated into the detailed description, with each claim standing on its own as a separate preferred embodiment of the invention.

[0164] The disclosed embodiments are described above to enable any person skilled in the art to implement or use the present invention. Various modifications of these embodiments are obvious to those skilled in the art, and the general principles defined herein may also be applied to other embodiments without departing from the spirit and scope of the present disclosure. Therefore, the present disclosure is not limited to the embodiments given herein, but is consistent with the broadest scope of the principles and novel features disclosed in this application.

[0165] The above description includes examples of one or more embodiments. Of course, it is impossible to describe all possible combinations of components or methods for the purpose of describing the above embodiments, but it should be recognized by those skilled in the art that the various embodiments may be further combined and arranged. Therefore, the embodiments described herein are intended to cover all such changes, modifications and variations that fall within the scope of protection of the appended claims. In addition, with respect to the term "comprising" used in the specification or claims, the word is covered in a manner similar to the term "including", just as "including," is explained as a transitional word in the claims. In addition, any term "or" used in the specification of the claims is intended to mean "non-exclusive or".

[0166] The embodiments described above are only used to illustrate the technical solutions of the present application, rather than to limit them. Although the present application has been described in detail with reference to the aforementioned embodiments, a person skilled in the art should understand that the technical solutions described in the aforementioned embodiments may still be modified, or some of the technical features may be replaced by equivalents. Such modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the embodiments of the present application, and should all be included in the protection scope of the present application.

Claims

1. A compressed air energy storage excitation side control system, used in a compressed air energy storage system, characterized in that: It includes a flexible excitation system power unit, an upper control unit and a lower control unit; The flexible excitation system power unit includes an AC LC filter, a rectifier, a voltage stabilizing capacitor and a chopper which are sequentially connected between the excitation transformer and the excitation winding. The control variable of the flexible excitation system power unit is the excitation voltage E fd The reactive power Q injected into the generator by the excitation system C ; The upper control unit includes a first control channel and a second control channel for controlling the excitation voltage and reactive power injected by the excitation system, respectively. The first control channel and the second control channel both include a tracking differentiator, a nonlinear controller and an extended state observer. The first control channel outputs a control variable command value E fdref To the chopper controller of the bottom control unit, the second control channel outputs the reactive current command value I sqref A dq decoupling controller to the bottom control unit; The bottom control unit includes a chopper controller, a dq decoupling controller and a PI regulator; The chopper controller is used to control the variable command value E according to the fdref Generate a switching signal to control the chopper to obtain the required excitation voltage E fd ; The PI regulator is used to perform PI regulation according to a given voltage to obtain a current command value I sdref ; The dq decoupling controller is used to input the reactive current command value I sqref and active current command value I sdref Realize double closed-loop control of rectifier; The dual closed-loop control includes a voltage outer loop control and a current inner loop control. The voltage outer loop control is used to provide a stable DC power supply for the chopper. The given voltage input to the PI regulator in the voltage outer loop control is the reference voltage U dcref ; The current inner loop control in the double closed-loop control is a direct current control based on the dq synchronous rotating coordinate system. The DC current control includes: sdref Perform active current control and follow the reactive current command value I sqref Perform reactive current control; The first control channel includes a first tracking differentiator, a first linear control module and a first extended state observer; the second control channel includes a second tracking differentiator, a second linear control module and a second extended state observer.

2. A control method for the compressed air energy storage excitation side control system according to claim 1, characterized in that: The method includes performing upper-level control based on an active disturbance rejection control algorithm, wherein the upper-level control includes: Select the output signals y1 and y2 of the control and determine the reference value y of the two output signals 1ref and 2ref , as input signals of the first tracking differentiator and the second tracking differentiator respectively; Establish a mathematical model of compressed air energy storage system based on flexible excitation system; Based on the selected output signal and the mathematical model of the compressed air energy storage system, an accurate feedback linearization model of the system is established, and the relative orders r1 and r2 of the output signals y1 and y2 are determined; According to the relative orders r1 and r2, determining the orders of the output signals y1 and y2 corresponding to the first extended state observer and the second extended state observer; The output of the extended state observer and the output of the tracking differentiator are used as input signals, and the intermediate control variables v1 and v2 are obtained through optimal control or pole configuration; Subtract the intermediate control variables v1 and v2 from the output disturbance signals of the first extended state observer and the second extended state observer respectively, and then transform them into -1 , get the control variable command value E fdref and Q′ Cref .

3. The control method according to claim 2, characterized in that: Get the control variable command value Q′ Cref After that, select the reference axis direction, u q =0,u d =1, through the formula Q′ Cref Calculate and get the reactive current command value I sqref .

4. The control method according to claim 2, characterized in that: The mathematical model of the compressed air energy storage system is: in, x TL =x T +x L x′ d∑ =x′ d +x TL x d∑ =x d +x TL x q∑ =x q +x TL In the formula, x T is the transformer reactance, x L is the transmission line reactance, P m is the mechanical power, D is the damping coefficient, ω is the generator speed, is the differential of ω, x q is the quadrature-axis synchronous reactance, x' d is the direct-axis transient reactance, x d is the synchronous reactance of the generator d axis, δ is the voltage between the q axis and the infinite busbar U s The angle of is the differential of δ, U t is the generator terminal voltage, Q′ C is the reactive power control quantity, Q C is the actual value of injected reactive power, Q C The differential of U t is the generator terminal voltage, U s is the infinite bus voltage, E q ′ is the transient potential of the generator q axis, For E q The differential of ′, T d ′0 is the time constant of the excitation winding, T J is the rotor inertia time constant, T Q It is the equivalent time constant of reactive power injection link.

5. The control method according to claim 2, characterized in that: The method of establishing an accurate feedback linearization model of the system based on the selected output signal and the mathematical model of the compressed air energy storage system and determining the relative orders r1 and r2 of the output signals y1 and y2 includes: Select the state variable as X = [δ ω E' q Q C ], E fd , Q′ C is the control variable, and the output signal is the variable y1, y2 that can reflect the operating status of the system. The analysis system is systematized as follows: in, Calculate the relative orders r1 and r2 of the outputs y1 and y2; The output signals y1 and y2 correspond to the orders of the first extended state observer and the second extended state observer, respectively, r1+1 and r2+1; Among them, P m is the mechanical power, D is the damping coefficient, ω is the generator speed, is the differential of ω, x q is the quadrature-axis synchronous reactance, x' d is the direct-axis transient reactance, x d is the synchronous reactance of the generator d axis, δ is the voltage between the q axis and the infinite busbar U s The angle of is the differential of δ, U t is the generator terminal voltage, Q′ C is the reactive power control quantity, Q C is the actual value of injected reactive power, Q C The differential of U s is the infinite bus voltage, E q ′ is the transient potential of the generator q axis, For E q The differential of ′, T d ′0 is the time constant of the excitation winding, T J is the rotor inertia time constant, T Q It is the equivalent time constant of reactive power injection link.

6. The control method according to claim 2, characterized in that: The transformation matrix B -1 Obtained by the following method: The precise feedback linearization model of the system is established. On the basis of selecting the output variables as y1 and y2 and determining the relative orders as r1 and r2, the mathematical model of the compressed air energy storage system is transformed into the following standard form: Among them, f1(t) and f2(t) represent the disturbance signal and the response of the unmodeled characteristics of the system to the total disturbance; The formula B(t) is calculated by the common formula of the ADRS algorithm; Among them, u1 and u2 are intermediate variables, E fd , Q′ C is the control variable, Q C Differentiation of Q C is the actual value of injected reactive power.

7. The control method according to claim 2, characterized in that: The intermediate control variables v1 and v2 are: e 11 =y 1ref -y1,e 21 =y 2ref -y2; in, is the controller proportional coefficient, obtained by linear optimal control or pole configuration method, for e 11 The r1-1 order differential of for e 21 The r2-1 order differential of .

8. The control method according to claim 2, characterized in that: Control variable command value E fdref and Q′ Cref Calculated by the following formula: Among them, f1(t) and f2(t) are the output signals of the extended state observer.

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