A control method for subsynchronous oscillation based on instantaneous active power of power grid lines

Abstract

The present invention relates to the technical field of subsynchronous oscillation control, specifically a control method for subsynchronous oscillation based on instantaneous active power of power grid lines, comprising: constructing a grid-side converter mathematical model of a target power grid in a subsynchronous oscillation state, the grid-side converter mathematical model comprising a grid-side voltage model, a grid-side current model, a grid-side converter circuit topology model and a grid-side converter circuit topology model under the d-q axis; based on the grid-side converter mathematical model of the target power grid in a subsynchronous oscillation state, obtaining a functional relationship of the DC bus voltage oscillation frequency of the target power grid in a subsynchronous oscillation state. The present invention can effectively identify and respond to stability problems caused by subsynchronous oscillations and prevent the negative impact of oscillations on power grid stability by accurately modeling the behavior of the power grid in a subsynchronous oscillation state.

Description

Technical Field

[0001] The present invention relates to the technical field of subsynchronous oscillation control, and in particular to a control method for subsynchronous oscillation based on instantaneous active power of power grid lines. Background Art

[0002] The instantaneous active power of power grid lines is a key indicator of power grid operation. It directly affects the stability and power quality of the power grid. In the subsynchronous oscillation state, the instantaneous active power of the power grid may be affected by disturbances and fluctuations, which requires compensation and adjustment through accurate models and control strategies.

[0003] Traditional methods may not be able to respond quickly to instantaneous disturbances in the system, resulting in a lag in the control of subsynchronous oscillations, and thus unable to effectively suppress oscillations and maintain grid stability; and the modeling in traditional methods may not accurately reflect the actual behavior of the grid under subsynchronous oscillations, resulting in the control strategy being unable to accurately combat the actual oscillation phenomenon; and traditional methods usually rely on fixed control strategies, which may not be able to be flexibly adjusted to adapt to different oscillation frequencies and amplitudes, thereby limiting their effectiveness in complex grid environments; and traditional methods may lack real-time state observation and disturbance compensation mechanisms, resulting in the inability to dynamically adjust control inputs to cope with changing disturbances, thereby affecting the real-time stability of the system. Summary of the invention

[0004] The purpose of the present invention is to address the problems existing in the background technology and to propose a control method for subsynchronous oscillation based on instantaneous active power of power grid lines.

[0005] The technical solution of the present invention is a control method for subsynchronous oscillation based on instantaneous active power of power grid lines, comprising:

[0006] Constructing a grid-side converter mathematical model of a target power grid in a subsynchronous oscillation state, wherein the grid-side converter mathematical model includes a grid-side voltage model, a grid-side current model, a grid-side converter circuit topology model, and a grid-side converter circuit topology model under a dq axis;

[0007] Obtaining a functional relationship of a DC bus voltage oscillation frequency of the target power grid in a sub-synchronous oscillation state based on a grid-side converter mathematical model of the target power grid in a sub-synchronous oscillation state;

[0008] Constructing a mathematical model of a doubly-fed wind turbine generator of the target power grid in a normal state, wherein the mathematical model of the doubly-fed wind turbine generator includes a flux linkage model, a power model and a rotor control model;

[0009] A state observer is constructed based on a mathematical model of a doubly-fed wind turbine generator of the target power grid in a normal state, a state estimation and disturbance information of the doubly-fed wind turbine generator is obtained based on the state observer, and a control input is adjusted in real time using the state estimation and the disturbance information to compensate for a total disturbance of the doubly-fed wind turbine generator in real time;

[0010] A quasi-resonant controller and a backstepping controller are constructed based on a functional relationship of the DC bus voltage oscillation frequency of the target power grid in a subsynchronous oscillation state. The oscillation component of the target power grid is tracked and controlled by the quasi-resonant controller, and the fundamental component of the target power grid is tracked and controlled by the backstepping controller.

[0011] Preferably, the grid-side voltage model is as follows:

[0012] ;

[0013] in, , and Respectively represent the three-phase voltage of the grid-side converter, , and They represent the three-phase voltages of the target power grid under ideal conditions, , and They represent the sub-synchronous voltage components of the target power grid respectively;

[0014] The grid-side current model is as follows:

[0015] ;

[0016] in, , and Respectively represent the three-phase current of the grid-side converter, , and They represent the three-phase currents of the target power grid under ideal conditions, , and They respectively represent the sub-synchronous current components of the target power grid.

[0017] Preferably, the grid-side converter circuit topology model is as follows:

[0018] ;

[0019] in, Represents the line resistance, , and They represent the phase voltages of the three-phase bridge arms of the grid-side converter respectively, Represents the capacitor voltage value, , and They represent the switch function, represents the load current, Indicates the DC bus side capacitance.

[0020] Preferably, the grid-side converter circuit topology model under the dq axis is as follows:

[0021] ;

[0022] in, and They represent the fundamental wave value of the grid-side voltage in the dq coordinate system, and They represent the fundamental wave value of the grid-side current in the dq coordinate system, represents the ideal grid voltage vector angular frequency, Indicates the occurrence frequency of synchronous voltage in the target power grid, and They represent the values ​​of the phase voltage of the bridge arm of the grid-side converter in the dq coordinate system, and They represent the switching functions in the dq coordinate system respectively.

[0023] Preferably, the function relationship of the DC bus voltage oscillation frequency of the target power grid in the subsynchronous oscillation state is as follows:

[0024] ;

[0025] in, Indicates the DC bus voltage oscillation value of the target power grid in the subsynchronous oscillation state. and They represent the synchronous oscillation component values ​​of the grid-side current in the dq coordinate system, Indicates the initial phase angle of the fundamental current on the grid side, Indicates the initial phase angle of the grid-side subsynchronous current, express The amplitude of .

[0026] Preferably, the magnetic linkage model is as follows:

[0027] ;

[0028] in, and They represent the components of the stator flux of the doubly-fed wind turbine generator in the dq coordinate system, and They represent the components of the rotor flux of the doubly-fed wind turbine generator in the dq coordinate system, and They represent the components of the stator current of the doubly-fed wind turbine generator in the dq coordinate system, and They represent the components of the rotor current of the doubly-fed wind generator in the dq coordinate system, and They represent the stator and rotor winding self-inductance of the doubly-fed wind turbine generator, respectively, and , represents the rotor leakage inductance of the doubly-fed wind turbine generator, and , represents the stator leakage inductance of the doubly-fed wind turbine generator, represents the mutual inductance of the stator and rotor windings of the doubly-fed wind turbine generator;

[0029] The power model is as follows:

[0030] ;

[0031] in, and They represent the active power and reactive power output on the stator side of the doubly-fed wind turbine generator, and They represent the active power and reactive power output on the rotor side of the doubly-fed wind turbine generator, and They represent the components of the stator voltage of the doubly-fed wind generator in the dq coordinate system, and They respectively represent the components of the rotor voltage of the doubly-fed wind generator in the dq coordinate system.

[0032] Preferably, the rotor control model is as follows:

[0033] ;

[0034] in, represents the magnitude of the stator voltage vector of the doubly-fed wind turbine generator, and They represent the resistance and inductance of the rotor of the doubly-fed wind turbine generator, represents the slip electrical angular velocity of the doubly-fed wind turbine generator, represents the target grid voltage angular velocity, Represents the magnetic leakage coefficient.

[0035] Preferably, a state observer is constructed based on a mathematical model of a doubly-fed wind turbine generator of the target power grid in a normal state, comprising:

[0036] Based on the mathematical model of the double-fed wind turbine generator in the target power grid under normal conditions, a rotor current d-axis control model for outputting active power is constructed. The rotor current d-axis control model for outputting active power is as follows:

[0037] ;

[0038] in, The second derivative of the rotor current d-axis representing the output active power;

[0039] A control object model is constructed based on the output active rotor current d-axis control model, and the control object model is as follows:

[0040] ;

[0041] in, represents the controller gain, represents the state variable and is equivalent to the total disturbance;

[0042] A state space is constructed based on the control object model, and the state space expression is as follows:

[0043] ;

[0044] in, represents the state vector, and , The total disturbance ,and The derivative of , Represents an external disturbance.

[0045] Preferably, the quasi-resonant controller is expressed as follows:

[0046] ;

[0047] in, represents the transfer function of the quasi-resonant controller, represents the gain factor of the quasi-resonant controller, represents the resonant bandwidth, represents the resonant frequency, Represents the input variable.

[0048] Preferably, the backstepping controller expression is as follows:

[0049] ;

[0050] in, , , and They represent the adaptive variables of the backstepping controller, , and They represent the Lyapunov derivative coefficients, , and represent the external backstepping tracking error, and , Indicates the DC bus voltage target value, , It represents the target value of the fundamental wave value of the d-axis of the grid-side current in the dq coordinate system. , represents the target value of the fundamental wave value of the grid-side current on the q-axis in the dq coordinate system, and , express The first-order derivative of , express The first-order derivative of , express The first derivative of .

[0051] Compared with the prior art, the above technical solution of the present invention has the following beneficial technical effects:

[0052] 1. The present invention can effectively identify and respond to stability problems caused by subsynchronous oscillations by accurately modeling the behavior of the power grid under subsynchronous oscillations, prevent the negative impact of oscillations on power grid stability, and obtain state estimation and disturbance information of the doubly fed wind turbine by constructing a state observer. It can adjust the control input in real time, thereby quickly responding to and compensating for disturbances caused by the wind turbine, improving the dynamic response capability of the system, and using a quasi-resonant controller and a backstepping controller to track and control the oscillation component and the fundamental component respectively, which helps to accurately control the voltage and current of the power grid when subsynchronous oscillations occur in the power grid, thereby reducing system fluctuations and improving system stability.

[0053] 2. The present invention controls the oscillation component and the fundamental component separately, so as to optimize the control strategy of each component and improve the performance of the overall system. This separate control helps to solve the subsynchronous oscillation problem more accurately and improve the performance of the system under normal working conditions. Combined with the design of quasi-resonant controller and backstepping controller, it can cope with various control challenges, including oscillation problems of different frequencies and amplitudes. This flexibility makes the control strategy more adaptable to complex power grid operating environments. BRIEF DESCRIPTION OF THE DRAWINGS

[0054] Figure 1 The present invention is a flowchart of an embodiment of the present invention. DETAILED DESCRIPTION

[0055] Embodiment 1, as Figure 1 As shown, the present invention proposes a control method for subsynchronous oscillation based on instantaneous active power of power grid lines, comprising:

[0056] S1. constructing a mathematical model of a grid-side converter of a target power grid in a subsynchronous oscillation state, wherein the mathematical model of the grid-side converter includes a grid-side voltage model, a grid-side current model, a grid-side converter circuit topology model, and a grid-side converter circuit topology model under a dq axis;

[0057] S2. obtaining a functional relationship of a DC bus voltage oscillation frequency of the target power grid in a subsynchronous oscillation state based on a grid-side converter mathematical model of the target power grid in a subsynchronous oscillation state;

[0058] S3, constructing a mathematical model of a doubly-fed wind turbine generator of a target power grid in a normal state, wherein the mathematical model of the doubly-fed wind turbine generator includes a flux linkage model, a power model and a rotor control model;

[0059] S4. constructing a state observer based on the mathematical model of the doubly-fed wind turbine generator in the target power grid under normal conditions, obtaining state estimation and disturbance information of the doubly-fed wind turbine generator based on the state observer, and adjusting the control input in real time using the state estimation and disturbance information to compensate for the total disturbance of the doubly-fed wind turbine generator in real time;

[0060] S5. A quasi-resonant controller and a backstepping controller are constructed based on the functional relationship of the DC bus voltage oscillation frequency of the target power grid in the subsynchronous oscillation state. The oscillation component of the target power grid is tracked and controlled by the quasi-resonant controller, and the fundamental component of the target power grid is tracked and controlled by the backstepping controller.

[0061] In the present invention, the grid-side converter mathematical model describes the electrical characteristics of the grid-side converter; the grid-side voltage model describes the voltage change of the converter connected to the grid; the grid-side current model describes the current change flowing through the converter; the grid-side converter circuit topology model describes the circuit structure of the converter; the grid-side converter circuit topology model under the dq axis describes the model for decomposing the current and voltage into the DC axis (d axis) and the alternating axis (q axis) in the coordinate transformation; the functional relationship of the DC bus voltage oscillation frequency describes the relationship between the DC bus voltage oscillation frequency and other system parameters of the grid in the sub-synchronous oscillation state. Used to predict and control the oscillation characteristics of voltage; the mathematical model of the doubly fed wind turbine describes the dynamic behavior of the wind turbine; the flux model describes the relationship between the magnetic flux and current of the generator; the power model calculates the electric power generated by the generator; the rotor control model controls the dynamics of the generator rotor to optimize power output and stability; the state observer is used to estimate the internal state of the system and external disturbances in real time; the quasi-resonant controller is specially designed to track and control the oscillation frequency in the system to reduce the impact of oscillation; the backstepping controller is a control strategy that handles the control problems of complex systems through step-by-step design, and is usually used to stabilize the system and control its response.

[0062] Embodiment 2, the present invention proposes a control method for subsynchronous oscillation based on instantaneous active power of a power grid line. Compared with embodiment 1, this embodiment further includes: a grid-side voltage model is as follows:

[0063] ;

[0064] in, , and Respectively represent the three-phase voltage of the grid-side converter, , and They represent the three-phase voltages of the target power grid under ideal conditions, , and They represent the sub-synchronous voltage components of the target power grid respectively;

[0065] The grid-side current model is as follows:

[0066] ;

[0067] in, , and Respectively represent the three-phase current of the grid-side converter, , and They represent the three-phase currents of the target power grid under ideal conditions, , and They respectively represent the sub-synchronous current components of the target power grid.

[0068] In an optional embodiment, the grid-side converter circuit topology model is as follows:

[0069] ;

[0070] in, Represents the line resistance, , and They represent the phase voltages of the three-phase bridge arms of the grid-side converter respectively, Represents the capacitor voltage value, , and They represent the switch function, represents the load current, Indicates the DC bus side capacitance.

[0071] It should be noted that line resistance is the resistance of the wires in the power grid, which causes the loss of electric energy during transmission; the phase voltage of the three-phase bridge arm of the grid-side converter is the voltage value of each phase bridge arm of the converter. The converter usually consists of three bridge arms, which correspond to the three-phase voltage in the power grid, and their voltage controls the output of the converter; the switching function is the state function that controls the switching element of the converter. The value of each switching function (S) is 0 or 1, indicating the on or off state of the switching element. Through these switching functions, the direction of current flow and the output characteristics of the converter can be controlled; the DC bus side capacitor is a capacitor connected to the DC bus.

[0072] In an optional embodiment, the grid-side converter circuit topology model under the dq axis is as follows:

[0073] ;

[0074] in, and They represent the fundamental wave value of the grid-side voltage in the dq coordinate system, and They represent the fundamental wave value of the grid-side current in the dq coordinate system, represents the ideal grid voltage vector angular frequency, Indicates the occurrence frequency of synchronous voltage in the target power grid, and They represent the values ​​of the phase voltage of the bridge arm of the grid-side converter in the dq coordinate system, and They represent the switching functions in the dq coordinate system respectively.

[0075] In an optional embodiment, the function relationship of the DC bus voltage oscillation frequency of the target power grid in the subsynchronous oscillation state is as follows:

[0076] ;

[0077] in, Indicates the DC bus voltage oscillation value of the target power grid in the subsynchronous oscillation state. and They represent the synchronous oscillation component values ​​of the grid-side current in the dq coordinate system, Indicates the initial phase angle of the fundamental current on the grid side, Indicates the initial phase angle of the grid-side subsynchronous current, express The amplitude of .

[0078] In an optional embodiment, the magnetic linkage model is as follows:

[0079] ;

[0080] in, and They represent the components of the stator flux of the doubly-fed wind turbine generator in the dq coordinate system, and They represent the components of the rotor flux of the doubly-fed wind turbine generator in the dq coordinate system, and They represent the components of the stator current of the doubly-fed wind turbine generator in the dq coordinate system, and They represent the components of the rotor current of the doubly-fed wind generator in the dq coordinate system, and They represent the stator and rotor winding self-inductance of the doubly-fed wind turbine generator, respectively, and , represents the rotor leakage inductance of the doubly-fed wind turbine generator, and , represents the stator leakage inductance of the doubly-fed wind turbine generator, represents the mutual inductance of the stator and rotor windings of the doubly-fed wind turbine generator;

[0081] The power model is as follows:

[0082] ;

[0083] in, and They represent the active power and reactive power output on the stator side of the doubly-fed wind turbine generator, and They represent the active power and reactive power output on the rotor side of the doubly-fed wind turbine generator, and They represent the components of the stator voltage of the doubly-fed wind generator in the dq coordinate system, and They respectively represent the components of the rotor voltage of the doubly-fed wind generator in the dq coordinate system.

[0084] In an optional embodiment, the rotor control model is as follows:

[0085] ;

[0086] in, represents the magnitude of the stator voltage vector of the doubly-fed wind turbine generator, and They represent the resistance and inductance of the rotor of the doubly-fed wind turbine generator, represents the slip electrical angular velocity of the doubly-fed wind turbine generator, represents the target grid voltage angular velocity, Represents the magnetic leakage coefficient.

[0087] In an optional embodiment, a state observer is constructed based on a mathematical model of a double-fed wind turbine generator of a target power grid in a normal state, including:

[0088] A1. Based on the mathematical model of the double-fed wind turbine generator in the target power grid under normal conditions, a rotor current d-axis control model for outputting active power is constructed. The rotor current d-axis control model for outputting active power is as follows:

[0089] ;

[0090] in, The second derivative of the rotor current d-axis representing the output active power;

[0091] A2. Construct a control object model based on the output active rotor current d-axis control model. The control object model is as follows:

[0092] ;

[0093] in, represents the controller gain, represents the state variable and is equivalent to the total disturbance;

[0094] A3. Construct the state space based on the control object model. The state space expression is as follows:

[0095] ;

[0096] in, represents the state vector, and , The total disturbance ,and The derivative of , Represents an external disturbance.

[0097] It should be noted that the second-order derivative of the active rotor current d-axis describes the acceleration of the rotor current in the d-axis direction, and is usually used to analyze the rate of dynamic change of the current; the controller gain is a parameter used in the control system to adjust the controller response speed and stability, which affects the control effect of the system; external disturbances: factors outside the system, such as wind speed changes, etc., have an impact on system performance.

[0098] In an optional embodiment, the quasi-resonant controller expression is as follows:

[0099] ;

[0100] in, represents the transfer function of the quasi-resonant controller, represents the gain factor of the quasi-resonant controller, represents the resonant bandwidth, represents the resonant frequency, Represents the input variable.

[0101] It should be noted that the transfer function of the quasi-resonant controller describes the processing characteristics of the controller for the input signal; the gain coefficient of the quasi-resonant controller is used to adjust the response amplitude of the controller; the resonant frequency is used to indicate that the controller is particularly sensitive to the signal response of this frequency.

[0102] In an optional embodiment, the backstepping controller expression is as follows:

[0103] ;

[0104] in, , , and They represent the adaptive variables of the backstepping controller, , and They represent the Lyapunov derivative coefficients, , and represent the external backstepping tracking error, and , Indicates the DC bus voltage target value, , It represents the target value of the fundamental wave value of the d-axis of the grid-side current in the dq coordinate system. , represents the target value of the fundamental wave value of the grid-side current on the q-axis in the dq coordinate system, and , express The first-order derivative of , express The first-order derivative of , express The first derivative of .

[0105] It should be noted that the adaptive variable of the backstepping controller is an adaptive variable related to the system parameters in the controller, which is used to adjust the behavior of the controller; the external backstepping tracking error represents the tracking error of the fundamental wave value of the d-axis and q-axis of the grid-side current in the dq coordinate system. These errors represent the gap between the actual value and the target value.

[0106] The embodiments of the present invention are described in detail above with reference to the accompanying drawings, but the present invention is not limited thereto, and various changes can be made within the knowledge scope of technicians in the relevant technical field without departing from the purpose of the present invention.

Claims

1. A control method for subsynchronous oscillation based on instantaneous active power of power grid lines, characterized in that: include: Constructing a grid-side converter mathematical model of a target power grid in a subsynchronous oscillation state, wherein the grid-side converter mathematical model includes a grid-side voltage model, a grid-side current model, a grid-side converter circuit topology model, and a grid-side converter circuit topology model under a dq axis; Obtaining a functional relationship of a DC bus voltage oscillation frequency of the target power grid in a sub-synchronous oscillation state based on a grid-side converter mathematical model of the target power grid in a sub-synchronous oscillation state; Constructing a mathematical model of a doubly-fed wind turbine generator of the target power grid in a normal state, wherein the mathematical model of the doubly-fed wind turbine generator includes a flux linkage model, a power model and a rotor control model; A state observer is constructed based on a mathematical model of a doubly-fed wind turbine generator of the target power grid in a normal state, a state estimation and disturbance information of the doubly-fed wind turbine generator is obtained based on the state observer, and a control input is adjusted in real time using the state estimation and the disturbance information to compensate for a total disturbance of the doubly-fed wind turbine generator in real time; A quasi-resonant controller and a backstepping controller are constructed based on a functional relationship of the DC bus voltage oscillation frequency of the target power grid in a subsynchronous oscillation state, the oscillation component of the target power grid is tracked and controlled by the quasi-resonant controller, and the fundamental wave component of the target power grid is tracked and controlled by the backstepping controller; The grid-side voltage model is as follows: ； in, , and Respectively represent the three-phase voltage of the grid-side converter, , and They represent the three-phase voltages of the target power grid under ideal conditions, , and They represent the sub-synchronous voltage components of the target power grid respectively; The grid-side current model is as follows: ； in, , and Respectively represent the three-phase current of the grid-side converter, , and They represent the three-phase currents of the target power grid under ideal conditions, , and They represent the sub-synchronous current components of the target power grid respectively; The grid-side converter circuit topology model is as follows: ； in, Represents the line resistance, , and They represent the phase voltages of the three-phase bridge arms of the grid-side converter respectively, Represents the capacitor voltage value, , and They represent the switch function, represents the load current, Indicates the DC bus side capacitance; The grid-side converter circuit topology model under the dq axis is as follows: ； in, and They represent the fundamental wave value of the grid-side voltage in the dq coordinate system, and They represent the fundamental wave value of the grid-side current in the dq coordinate system, represents the ideal grid voltage vector angular frequency, Indicates the occurrence frequency of synchronous voltage in the target power grid, and They represent the values ​​of the phase voltage of the bridge arm of the grid-side converter in the dq coordinate system, and They represent the switching functions in the dq coordinate system respectively; The function relationship of the DC bus voltage oscillation frequency of the target power grid in the subsynchronous oscillation state is as follows: ； in, Indicates the DC bus voltage oscillation value of the target power grid in the subsynchronous oscillation state, and They represent the synchronous oscillation component values ​​of the grid-side current in the dq coordinate system, Indicates the initial phase angle of the fundamental current on the grid side, Indicates the initial phase angle of the grid-side subsynchronous current, express The amplitude of The magnetic linkage model is as follows: ； in, and They represent the components of the stator flux of the doubly-fed wind turbine generator in the dq coordinate system, and They represent the components of the rotor flux of the doubly-fed wind turbine generator in the dq coordinate system, and They represent the components of the stator current of the doubly-fed wind turbine generator in the dq coordinate system, and They represent the components of the rotor current of the doubly-fed wind generator in the dq coordinate system, and They represent the stator and rotor winding self-inductance of the doubly-fed wind turbine generator, respectively, and , represents the rotor leakage inductance of the doubly-fed wind turbine generator, and , represents the stator leakage inductance of the doubly-fed wind turbine generator, represents the mutual inductance of the stator and rotor windings of the doubly-fed wind turbine generator; The power model is as follows: ； in, and They represent the active power and reactive power output on the stator side of the doubly-fed wind turbine generator, and They represent the active power and reactive power output on the rotor side of the doubly-fed wind turbine generator, and They represent the components of the stator voltage of the doubly-fed wind generator in the dq coordinate system, and They represent the components of the rotor voltage of the doubly-fed wind generator in the dq coordinate system respectively; The rotor control model is as follows: ； in, represents the magnitude of the stator voltage vector of the doubly-fed wind turbine generator, and They represent the resistance and inductance of the rotor of the doubly-fed wind turbine generator, represents the slip electrical angular velocity of the doubly-fed wind turbine generator, represents the target grid voltage angular velocity, It represents the magnetic flux leakage coefficient; A state observer is constructed based on a mathematical model of a double-fed wind turbine generator of the target power grid in a normal state, including: Based on the mathematical model of the double-fed wind turbine generator in the target power grid under normal conditions, a rotor current d-axis control model for outputting active power is constructed. The rotor current d-axis control model for outputting active power is as follows: ； in, The second derivative of the rotor current d-axis representing the output active power; A control object model is constructed based on the output active rotor current d-axis control model, and the control object model is as follows: ； in, represents the controller gain, represents the state variable and is equivalent to the total disturbance; A state space is constructed based on the control object model, and the state space expression is as follows: ； in, represents the state vector, and , The total disturbance ,and The derivative of , represents external disturbance; The quasi-resonant controller expression is as follows: ； in, represents the transfer function of the quasi-resonant controller, represents the gain factor of the quasi-resonant controller, represents the resonant bandwidth, represents the resonant frequency, represents input variables; The backstepping controller expression is as follows: ； in, , , and They represent the adaptive variables of the backstepping controller, , and They represent the Lyapunov derivative coefficients, , and represent the external backstepping tracking error, and , Indicates the DC bus voltage target value, , It represents the target value of the fundamental wave value of the d-axis of the grid-side current in the dq coordinate system. , represents the target value of the fundamental wave value of the grid-side current on the q-axis in the dq coordinate system, and , express The first-order derivative of , express The first-order derivative of , express The first derivative of .

Images