High-robustness performance control method and system of PMSG-PWM rectification system based on LCL filtering

Abstract

The invention discloses a high-robustness performance control method and system of a PMSG-PWM rectification system based on LCL filtering, and the method comprises the steps: collecting a DC side voltage udc of a PWM rectifier, carrying out the difference calculation of the DC side voltage udc and a given reference value # imgabs0 #, obtaining a first difference value, collecting a PMSG side terminal voltage signal, and calculating an effective value Urms of the PMSG side terminal voltage signal; inputting the first difference value and the Urms into an outer ring sliding mode controller, and obtaining an active current reference quantity based on an output equation of the outer ring sliding mode controller; inputting udc and Urms into an extended state observer to obtain an observation value z2 of the total disturbance d (t) of the system, and substituting the observation value z2 of the total disturbance d (t) of the system into an output equation of an outer ring sliding mode controller to obtain an active current reference quantity of a variable exponential reaching law based on the extended state observer; and inputting the active current reference quantity of the variable exponential reaching law based on the extended state observer, the PMSG side end voltage and the three-phase current signal into an inner loop prediction current control module to obtain a current inner loop final control model. According to the invention, the robust performance of the system is effectively improved, and the DC output quality is higher.

Description

Technical Field

[0001] The invention relates to the field of electric energy conversion controller design, and in particular to a high robust performance control method and system of a PMSG-PWM rectifier system based on LCL filtering. Background Art

[0002] The AC power generated by new energy power generation devices such as wind energy and tidal energy changes in real time with the changes in wind speed and tidal flow rate. The output AC voltage has the actual characteristics of a wide range of variations. Therefore, higher requirements are placed on the robust performance of the subsequent power conversion device. It is very important and necessary to design a three-phase PWM rectifier control strategy suitable for the wide range of output AC voltage variations.

[0003] The existing PWM rectifier control strategy is mainly focused on the study of the stable AC power supply on the AC side. There are few control strategies for PMSG-PWM rectifier systems based on LCL filtering with a generator as the front stage. The current PMSG-PWM rectifier system control strategy is mostly based on PI double closed-loop control with feedforward decoupling. Although this solution is mature in theory, the system has weak anti-interference ability and is not suitable for practical application scenarios. Summary of the invention

[0004] In view of the technical defects and disadvantages in the prior art, the embodiments of the present invention provide a high robustness performance control method and system for a PMSG-PWM rectifier system based on LCL filtering, which overcomes the above problems or at least partially solves the above problems. The specific scheme is as follows:

[0005] As a first aspect of the present invention, a high robustness performance control method of a PMSG-PWM rectifier system based on LCL filtering is provided, the method comprising:

[0006] Collect the DC side voltage u of the PWM rectifier dc and with the given reference value Perform difference calculation to obtain the first difference, collect the PMSG side terminal voltage signal, and calculate its effective value U rms ;

[0007] The first difference and the effective value U rms The active current reference is input into the outer loop sliding mode controller, and the active current reference is obtained based on the output equation of the outer loop sliding mode controller;

[0008] The DC side voltage u of the PWM rectifier dc and the effective value U rms Input into the extended state observer to obtain the observed value z2 of the total disturbance d(t) of the system

[0009] Substitute the observed value z2 of the total disturbance d(t) of the system into the output equation of the outer loop sliding mode controller to obtain the active current reference based on the variable exponential reaching law of the extended state observer;

[0010] The active current reference based on the variable exponential reaching law of the extended state observer, the PMSG side terminal voltage and the three-phase current signal are input into the inner loop predictive current control module to obtain the final control model of the current inner loop.

[0011] Furthermore, the first difference and the effective value U rms Input into the outer loop sliding mode controller, and obtain the active current reference based on the output equation of the outer loop sliding mode controller, including:

[0012] Establish a variable exponential reaching law function, as follows:

[0013]

[0014] Wherein, e is the difference between the reference voltage and the actual voltage on the DC side of the PWM rectifier, that is, the first difference, ε is the switching function coefficient, k is the exponential reaching law coefficient, s is the sliding mode equation,

[0015] The reaching law function is combined with the mathematical model of the PMSG-PWM rectifier system to obtain the output equation based on the outer loop sliding mode controller, which is expressed as follows:

[0016]

[0017] In the formula, Active current reference, C is the DC side filter capacitor, e d is the direct axis component of the voltage at the PMSG side terminal in the dq coordinate system, R is the PMSG equivalent resistance, R L is the load resistance, e2=s2=u dc * -u dc ,i d is the actual current active component, and the current reference is used in actual simulation replace.

[0018] Furthermore, the PWM rectifier DC side voltage u dc and the effective value U rms Input into the extended state observer, and obtain the observed value z2 of the total disturbance d(t) of the system, which specifically includes:

[0019] Define the external disturbance of the system as T(t), when the system is in steady-state operation at unity power factor, i q =0,i qis the reactive component of the PMSG side current, ignoring the PMSG equivalent resistance and the external inductor equivalent resistance, and rewriting the mathematical model of the PMSG-PWM rectifier system as follows:

[0020]

[0021] In order to improve the system's anti-interference ability, the total disturbance of the system is defined as:

[0022]

[0023] The total disturbance covers the DC side voltage, circuit parameters, AC side current tracking error and external disturbances. By observing the total disturbance, the impact of various disturbances on the system can be avoided in advance, thus improving the system robustness.

[0024] According to the definition of the total disturbance d(t) of the system, the mathematical model of the PMSG-PWM rectifier system is simplified as follows:

[0025]

[0026] In the formula,

[0027] Analysis shows that the voltage outer loop mathematical model is expanded to a second-order system, and the state equation is:

[0028]

[0029] Where x1(t) = u dc , x2(t)=d(t).

[0030] Finally, the second-order extended state observer is obtained as:

[0031]

[0032] Among them, z1 and z2 are u dc , d(t) are the observed quantities, β1 and β2 are the ESO design parameters;

[0033] Substituting the observed value z2 of the total disturbance d(t) of the system into the output equation of the outer loop sliding mode controller to obtain the active current reference based on the variable exponential reaching law of the extended state observer specifically includes:

[0034] Substitute the voltage outer loop comprehensive disturbance d(t) observation z2 obtained by the extended state observer into the output equation of the outer loop sliding mode controller to obtain the output equation of the variable exponential reaching law sliding mode controller based on the extended state observer, and obtain the output of the variable exponential reaching law sliding mode controller based on the extended state observer It is expressed as the following formula:

[0035]

[0036] Furthermore, the active current reference based on the variable exponential reaching law of the extended state observer, the PMSG side terminal voltage and the three-phase current signal are input into the inner loop predictive current control module to obtain the current inner loop final control model, which specifically includes:

[0037] Collect the PMSG side terminal voltage and three-phase current signals and transform the abc to (d, q) coordinate system, and input the transformed electromotive force and three-phase current signals into the inner loop predictive current control module;

[0038] Setting reactive current reference value The reactive current reference value is combined with the active current reference value based on the variable exponential reaching law of the extended state observer Transform the coordinate system from (α, β) to (d, q), and input the transformed reactive current reference value and the active current reference value based on the variable exponential reaching law of the extended state observer into the inner loop prediction current module;

[0039] The inner loop prediction current module obtains the voltage reference vector based on the transformed electromotive force, three-phase current signal, reactive current reference value and active current reference based on the variable exponential reaching law of the extended state observer through algorithm control. That is the final control model of the current inner loop.

[0040] Furthermore, the inner loop current prediction module obtains the voltage reference vector based on the transformed electromotive force, three-phase current signal, reactive current reference value and active current reference based on the variable exponential reaching law of the extended state observer through algorithm control. That is, the final control model of the current inner loop specifically includes:

[0041] Define the PWM rectifier AC side voltage u α and u β for:

[0042]

[0043] Among them, u α is the α-axis voltage on the AC side of the PWM rectifier, u α is the β-axis voltage on the AC side of the PWM rectifier;

[0044] Based on u α and u β Formula, the PMSG-PWM rectifier system current mathematical model is rewritten as:

[0045]

[0046] Among them, i α and i βare the α-axis and β-axis currents of the AC side of the PWM rectifier respectively; α and e β are the α-axis and β-axis voltages on the AC side of the PWM rectifier, respectively, and L is the sum of the PMSG equivalent inductance and the external inductance;

[0047] In a sampling period T s Within the time, take the average value of each variable in the rewritten mathematical model and transform the mathematical model into:

[0048]

[0049] Among them, T s =t k+1 -t k , t k and t k+1 Corresponding to the two moments before and after respectively;

[0050] When the system is stable, the actual current on the AC side quickly tracks the reference current, so there is i * (t k+1 )=i(t k+1 ), the average voltage of the AC side in one cycle Defined as reference voltage And perform an inverse transformation from (α, β) to the abc coordinate system, and the result is the input signal of the space vector pulse width modulation module, and the final control model of the current inner loop is:

[0051]

[0052] As a second aspect of the present invention, a high robustness performance control system of a PMSG-PWM rectifier system based on LCL filtering is also provided, the system comprising a data acquisition module, a first active current reference quantity calculation module, an observation value calculation module, a second active current reference quantity calculation module and a control model calculation module;

[0053] The data acquisition module is used to collect the DC side voltage u of the PWM rectifier dc and with the given reference value Perform difference calculation to obtain the first difference, collect the PMSG side terminal voltage signal, and calculate its effective value U rms ;

[0054] The first active current reference quantity calculation module is used to obtain the first difference and the effective value U rms The active current reference is input into the outer loop sliding mode controller, and the active current reference is obtained based on the output equation of the outer loop sliding mode controller;

[0055] The observation value calculation module is used to convert the DC side voltage u of the PWM rectifier dcand the effective value U rms Input into the extended state observer to obtain the observed value z2 of the total disturbance d(t) of the system;

[0056] The second active current reference calculation module is used to substitute the observed value z2 of the total system disturbance d(t) into the output equation of the outer loop sliding mode controller to obtain the active current reference based on the variable exponential reaching law of the extended state observer;

[0057] The control model calculation module is used to input the active current reference based on the variable exponential reaching law of the extended state observer, the PMSG side terminal voltage and the three-phase current signal into the inner loop predictive current control module to obtain the current inner loop final control model.

[0058] Furthermore, the first active current reference quantity calculation module is specifically used for:

[0059] Establish a variable exponential reaching law function, as follows:

[0060]

[0061] Wherein, e is the difference between the reference voltage and the actual voltage on the DC side of the PWM rectifier, that is, the first difference, ε is the switching function coefficient, and k is the exponential reaching law coefficient;

[0062] The reaching law function is combined with the mathematical model of the PMSG-PWM rectifier system to obtain the output equation based on the outer loop sliding mode controller, which is expressed as follows:

[0063]

[0064] In the formula, is the active current reference, C is the DC side filter capacitor, e d is the direct axis component of the voltage at the PMSG side terminal in the dq coordinate system, R is the PMSG equivalent resistance, R L is the load resistance.

[0065] Furthermore, the observation value calculation module is specifically used for:

[0066] Define the external disturbance of the system as T(t), when the system is in steady-state operation at unity power factor, i q =0,i q is the reactive component of the PMSG side current, ignoring the PMSG equivalent resistance and the external inductor equivalent resistance, and rewriting the mathematical model of the PMSG-PWM rectifier system as follows:

[0067]

[0068] In order to improve the system's anti-interference ability, the total disturbance of the system is defined as:

[0069]

[0070] The total disturbance covers the DC side voltage, circuit parameters, AC side current tracking error and external disturbances. By observing the total disturbance, the impact of various disturbances on the system can be avoided in advance, thus improving the system robustness.

[0071] According to the definition of the total disturbance d(t) of the system, the mathematical model of the PMSG-PWM rectifier system is simplified as follows:

[0072]

[0073] In the formula,

[0074] Analysis shows that the voltage outer loop mathematical model is expanded to a second-order system, and the state equation is:

[0075]

[0076] Where x1(t) = u dc , x2(t)=d(t).

[0077] Finally, the second-order extended state observer is obtained as:

[0078]

[0079] Among them, z1 and z2 are u dc , d(t) are the observed quantities, β1 and β2 are the ESO design parameters;

[0080] The second active current reference quantity calculation module is specifically used for:

[0081] Substitute the voltage outer loop comprehensive disturbance d(t) observation z2 obtained by the extended state observer into the output equation of the outer loop sliding mode controller to obtain the output equation of the variable exponential reaching law sliding mode controller based on the extended state observer, and obtain the output of the variable exponential reaching law sliding mode controller based on the extended state observer It is expressed as the following formula:

[0082]

[0083] Furthermore, the control model calculation module is specifically used for:

[0084] Collect the PMSG side terminal voltage and three-phase current signals and transform the abc to (d, q) coordinate system, and input the transformed electromotive force and three-phase current signals into the inner loop predictive current control module;

[0085] Setting reactive current reference value The reactive current reference value is combined with the active current reference value based on the variable exponential reaching law of the extended state observer Transform the coordinate system from (α, β) to (d, q), and input the transformed reactive current reference value and the active current reference value based on the variable exponential reaching law of the extended state observer into the inner loop prediction current module;

[0086] The inner loop prediction current module obtains the voltage reference vector based on the transformed electromotive force, three-phase current signal, reactive current reference value and active current reference based on the variable exponential reaching law of the extended state observer through algorithm control. That is the final control model of the current inner loop.

[0087] Furthermore, the inner loop current prediction module obtains the voltage reference vector based on the transformed electromotive force, three-phase current signal, reactive current reference value and active current reference based on the variable exponential reaching law of the extended state observer through algorithm control. That is, the final control model of the current inner loop specifically includes:

[0088] Define the PWM rectifier AC side voltage u α and u β for:

[0089]

[0090] Among them, u α is the α-axis voltage on the AC side of the PWM rectifier, u α is the β-axis voltage on the AC side of the PWM rectifier;

[0091] Based on u α and u β Formula, the PMSG-PWM rectifier system current mathematical model is rewritten as:

[0092]

[0093] Among them, i α and i β are the α-axis and β-axis currents of the AC side of the PWM rectifier respectively; α and e β are the voltages at the α-axis and β-axis terminals of the AC side of the PWM rectifier, respectively, and L is the sum of the PMSG equivalent inductance and the external inductance;

[0094] In a sampling period T s Within the time, take the average value of each variable in the rewritten mathematical model and transform the mathematical model into:

[0095]

[0096] Among them, Ts =t k+1 -t k , t k and t k+1 Corresponding to the two moments before and after respectively;

[0097] When the system is stable, the actual current on the AC side quickly tracks the reference current, so there is i * (t k+1 )=i(t k+1 ), the average value of the AC side voltage in one cycle Defined as reference voltage And perform an inverse transformation from (α, β) to the abc coordinate system, and the result is the input signal of the space vector pulse width modulation module, and the final control model of the current inner loop is:

[0098]

[0099] The present invention has the following beneficial effects:

[0100] 1) The invention designs an extended state observer to observe the total disturbance of the system and compensates it in advance to the sliding mode controller, which effectively improves the robust performance of the system and enables stable and high-quality operation under the condition of a wide range of PMSG output voltage changes;

[0101] 2) The present invention improves the sliding mode reaching law in the sliding mode controller and designs a variable exponential reaching law, which effectively improves the DC side voltage jitter phenomenon caused by the classic reaching law and makes the DC output quality higher. BRIEF DESCRIPTION OF THE DRAWINGS

[0102] Figure 1 A schematic diagram of the PMSG-PWM rectifier system structure provided in an embodiment of the present invention (the power source of the prime mover varies depending on the application scenario);

[0103] Figure 2 A schematic diagram of the topological structure of a PMSG-PWM rectifier system provided in an embodiment of the present invention;

[0104] Figure 3 A block diagram of a PMSG-PWM control system provided by an embodiment of the present invention;

[0105] Figure 4 A flow chart of a high robust performance control method for a PMSG-PWM rectifier system based on LCL filtering provided by an embodiment of the present invention. DETAILED DESCRIPTION

[0106] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0107] See also Figure 1-3 The above is a schematic diagram related to the PMSG-PWM rectification system provided by an embodiment of the present invention.

[0108] In order to improve the robust performance of the PMSG-PWM rectifier system so as to better adapt to the actual characteristics of renewable energy power generation such as wind energy and tidal energy, the present invention provides a novel PMSG-PWM rectifier system control strategy that combines "variable exponential reaching law sliding mode outer loop control based on extended state observer" and "predictive current inner loop control with introduction of phase-locked loop technology". While retaining the advantages of system unity power factor operation and low harmonic content of AC current measurement, its robust performance and response speed are greatly improved.

[0109] See also Figure 3 The embodiment of the present invention provides a high robustness performance control method for a PMSG-PWM rectifier system based on LCL filtering, the method comprising:

[0110] Collect the DC side voltage u of the PWM rectifier dc and with the given reference value Perform difference calculation to obtain the first difference, collect the PMSG side terminal voltage signal, and calculate its effective value U rms ;

[0111] The first difference and the effective value U rms The active current reference is input into the outer loop sliding mode controller, and the active current reference is obtained based on the output equation of the outer loop sliding mode controller;

[0112] The DC side voltage u of the PWM rectifier dc and the effective value U rms Input into the extended state observer to obtain the observed value z2 of the total disturbance d(t) of the system

[0113] Substitute the observed value z2 of the total disturbance d(t) of the system into the output equation of the outer loop sliding mode controller to obtain the active current reference based on the variable exponential reaching law of the extended state observer;

[0114] The active current reference based on the variable exponential reaching law of the extended state observer, the PMSG side terminal voltage and the three-phase current signal are input into the inner loop predictive current control module to obtain the final control model of the current inner loop.

[0115] The present invention designs an extended state observer to observe the total disturbance of the system and compensates it in advance to the sliding mode controller, which effectively improves the robust performance of the system and can operate stably and with high quality under the working conditions of a wide variation range of the PMSG output voltage; the present invention improves the sliding mode reaching law in the sliding mode controller and designs a variable exponential reaching law, which effectively improves the DC side voltage jitter phenomenon caused by the classical reaching law and makes the DC output quality higher.

[0116] In some embodiments, the first difference and the effective value U rms Input into the outer loop sliding mode controller, and obtain the active current reference based on the output equation of the outer loop sliding mode controller, including:

[0117] Establish a variable exponential reaching law function, as follows:

[0118]

[0119] Wherein, e is the difference between the reference voltage and the actual voltage on the DC side of the PWM rectifier, that is, the first difference, ε is the switching function coefficient, k is the exponential reaching law coefficient, s is the sliding mode equation,

[0120] The reaching law function is combined with the mathematical model of the PMSG-PWM rectifier system to obtain the output equation based on the outer loop sliding mode controller, which is expressed as follows:

[0121]

[0122] In the formula, is the active current reference, C is the DC side filter capacitor, e d is the direct axis component of the PMSG side voltage in the dq coordinate system, R is the PMSG equivalent resistance, R L is the load resistance, e2=s2=u dc * -u dc ,i d is the actual current active component, and the current reference is used in actual simulation replace.

[0123] In some embodiments, the

[0124] The DC side voltage u of the PWM rectifier dc and the effective value U rms Input into the extended state observer to obtain the observed value z2 of the total disturbance d(t) of the system. Substitute the observed value z2 of the total disturbance d(t) of the system into the output equation of the outer loop sliding mode controller to obtain the active current reference based on the variable exponential reaching law of the extended state observer. Specifically, it includes:

[0125] Define the external disturbance of the system as T(t), when the system is in steady-state operation at unity power factor, i q =0,i q is the reactive component of the PMSG side current, ignoring the PMSG equivalent resistance and the external inductor equivalent resistance, and rewriting the mathematical model of the PMSG-PWM rectifier system as follows:

[0126]

[0127] In order to improve the system's anti-interference ability, the total disturbance of the system is defined as:

[0128]

[0129] The total disturbance covers the DC side voltage, circuit parameters, AC side current tracking error and external disturbances. By observing the total disturbance, the impact of various disturbances on the system can be avoided in advance and the system robustness can be improved.

[0130] According to the definition of the total disturbance d(t) of the system, the mathematical model of the PMSG-PWM rectifier system is simplified as follows:

[0131]

[0132] In the formula,

[0133] Analysis shows that the voltage outer loop mathematical model is expanded to a second-order system, and the state equation is:

[0134]

[0135] Where x1(t) = u dc , x2(t)=d(t).

[0136] Finally, the second-order extended state observer is obtained as:

[0137]

[0138] Among them, x1 is the voltage parameter of the DC side of the PWM rectifier, which is equivalent to x1(t) in the above formula, and z1 and z2 are u dc , d(t) are the observed quantities, β1 and β2 are the ESO design parameters (parameter settings affect the observation effect);

[0139] Substitute the voltage outer loop comprehensive disturbance d(t) observation z2 obtained by the extended state observer into the output equation of the outer loop sliding mode controller to obtain the output equation of the variable exponential reaching law sliding mode controller based on the extended state observer, and obtain the output of the variable exponential reaching law sliding mode controller based on the extended state observer It is expressed as the following formula:

[0140]

[0141] In some embodiments, the active current reference based on the variable exponential reaching law of the extended state observer, the PMSG side terminal voltage and the three-phase current signal are input into the inner loop predictive current control module to obtain the current inner loop final control model, which specifically includes:

[0142] Collect the PMSG side terminal voltage and three-phase current signals and transform the abc to (d, q) coordinate system, and input the transformed electromotive force and three-phase current signals into the inner loop predictive current control module;

[0143] Setting reactive current reference value The reactive current reference value is combined with the active current reference value based on the variable exponential reaching law of the extended state observer Transform the coordinate system from (d, q) to (α, β), and input the transformed reactive current reference value and the active current reference value based on the variable exponential reaching law of the extended state observer into the inner loop prediction current module;

[0144] The inner loop prediction current module obtains the voltage reference vector based on the transformed electromotive force, three-phase current signal, reactive current reference value and active current reference based on the variable exponential reaching law of the extended state observer through algorithm control. That is the final control model of the current inner loop.

[0145] The inner loop current prediction module is based on the transformed electromotive force, three-phase current signal, reactive current reference value and active current reference based on the variable exponential reaching law of the extended state observer, and obtains the voltage reference vector through algorithm control. Specifically include:

[0146] Define the PWM rectifier AC side voltage u α and u β for:

[0147]

[0148] Among them, u α is the α-axis voltage on the AC side of the PWM rectifier, u α is the β-axis voltage on the AC side of the PWM rectifier;

[0149] Based on u α and u β Formula, the PMSG-PWM rectifier system current mathematical model is rewritten as:

[0150]

[0151] Among them, i α and i βare the α-axis and β-axis currents of the AC side of the PWM rectifier respectively; α and e β are the α-axis and β-axis voltages on the AC side of the PWM rectifier, respectively, and L is the sum of the PMSG equivalent inductance and the external inductance;

[0152] In a sampling period T s Within the time, take the average value of each variable in the rewritten mathematical model and transform the mathematical model into:

[0153]

[0154] Among them, T s =t k+1 -t k , t k and t k+1 Corresponding to the two moments before and after respectively;

[0155] When the system is stable, the actual current on the AC side quickly tracks the reference current, so there is i * (t k+1 )=i(t k+1 ), the average voltage of the AC side in one cycle Defined as reference voltage And perform an inverse transformation from (α, β) to the abc coordinate system, and the result is the input signal of the space vector pulse width modulation module, and the final control model of the current inner loop is:

[0156]

[0157] in, and i d *The reference current components corresponding to the α and β axes after the (d, q) to (α, β) coordinate system transformation.

[0158] In addition, when the active current reference quantity based on the variable exponential approaching law of the extended state observer, the PMSG side terminal voltage and the three-phase current signal are input into the inner loop prediction current control module for calculation, the present invention also adopts the PLL technology to lock the grid voltage phase angle in real time, avoiding the trigonometric function operation, so that the control link is further simplified, and at the same time, a lead angle (θ c =ω·T s ) method, which offsets the inherent phase static error of the traditional PCC and achieves unity power factor operation of the system.

[0159] The embodiment of the present invention also provides a high robust performance control system of a PMSG-PWM rectifier system based on LCL filtering, the system comprising a data acquisition module, a first active current reference quantity calculation module, an observation value calculation module, a second active current reference quantity calculation module and a control model calculation module;

[0160] The data acquisition module is used to collect the DC side voltage u of the PWM rectifier dc and with the given reference value Perform difference calculation to obtain the first difference, collect the PMSG side terminal voltage signal, and calculate its effective value U rms ;

[0161] The first active current reference quantity calculation module is used to obtain the first difference and the effective value U rms The active current reference is input into the outer loop sliding mode controller, and the active current reference is obtained based on the output equation of the outer loop sliding mode controller;

[0162] The observation value calculation module is used to convert the DC side voltage u of the PWM rectifier dc and the effective value U rms Input into the extended state observer to obtain the observed value z2 of the total disturbance d(t) of the system;

[0163] The second active current reference calculation module is used to substitute the observed value z2 of the total system disturbance d(t) into the output equation of the outer loop sliding mode controller to obtain the active current reference based on the variable exponential reaching law of the extended state observer;

[0164] The control model calculation module is used to input the active current reference based on the variable exponential reaching law of the extended state observer, the PMSG side terminal voltage and the three-phase current signal into the inner loop predictive current control module to obtain the current inner loop final control model.

[0165] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principle of the present invention should be included in the protection scope of the present invention.

Claims

1. A high robustness control method for a PMSG-PWM rectifier system based on LCL filtering, characterized in that: The method comprises: Collect the DC side voltage u of the PWM rectifier dc and with the given reference value Perform difference calculation to obtain the first difference, collect the PMSG side terminal voltage signal, and calculate its effective value U rms ; The first difference and the effective value U rms The active current reference is input into the outer loop sliding mode controller, and the active current reference is obtained based on the output equation of the outer loop sliding mode controller; The DC side voltage u of the PWM rectifier dc and the effective value U rms Input into the extended state observer to obtain the observed value z2 of the total disturbance d(t) of the system; Substitute the observed value z2 of the total disturbance d(t) of the system into the output equation of the outer loop sliding mode controller to obtain the active current reference based on the variable exponential reaching law of the extended state observer; The active current reference based on the variable exponential reaching law of the extended state observer, the PMSG side terminal voltage and the three-phase current signal are input into the inner loop predictive current control module to obtain the final control model of the current inner loop.

2. The high robustness performance control method of the PMSG-PWM rectifier system based on LCL filtering according to claim 1 is characterized in that: The first difference and the effective value U rms Input into the outer loop sliding mode controller, and obtain the active current reference based on the output equation of the outer loop sliding mode controller, including: Establish a variable exponential reaching law function, as follows: Wherein, e is the difference between the reference voltage and the actual voltage on the DC side of the PWM rectifier, that is, the first difference, ε is the switching function coefficient, k is the exponential reaching law coefficient, s is the sliding mode equation, The reaching law function is combined with the mathematical model of the PMSG-PWM rectifier system to obtain the output equation based on the outer loop sliding mode controller, which is expressed as follows: In the formula, is the active current reference, C is the DC side filter capacitor, e d is the direct axis component of the voltage at the PMSG side terminal in the dq coordinate system, R is the PMSG equivalent resistance, R L is the load resistance, e2=s2=u dc * -u dc ,i d is the actual active component of current.

3. The high robustness performance control method of the PMSG-PWM rectifier system based on LCL filtering according to claim 2 is characterized in that: The PWM rectifier DC side voltage u dc and the effective value U rms Input into the extended state observer, and obtain the observed value z2 of the total disturbance d(t) of the system, which specifically includes: Define the external disturbance of the system as T(t), when the system is in steady-state operation at unity power factor, i q =0,i q is the reactive component of the PMSG side current, ignoring the PMSG equivalent resistance and the external inductor equivalent resistance, and rewriting the mathematical model of the PMSG-PWM rectifier system as follows: In order to improve the system's anti-interference ability, the total disturbance of the system is defined as: The total disturbance covers the DC side voltage, circuit parameters, AC side current tracking error and external disturbances. By observing the total disturbance, the impact of various disturbances on the system can be avoided in advance, thus improving the system robustness. According to the definition of the total disturbance d(t) of the system, the mathematical model of the PMSG-PWM rectifier system is simplified as follows: In the formula, Analysis shows that the voltage outer loop mathematical model is expanded to a second-order system, and the state equation is: Where x1(t) = u dc , x2(t)=d(t). Finally, the second-order extended state observer is obtained as: Among them, z1 and z2 are u dc , d(t) are the observed quantities, β1 and β2 are the ESO design parameters; Substituting the observed value z2 of the total disturbance d(t) of the system into the output equation of the outer loop sliding mode controller to obtain the active current reference based on the variable exponential reaching law of the extended state observer specifically includes: Substitute the voltage outer loop comprehensive disturbance d(t) observation z2 obtained by the extended state observer into the output equation of the outer loop sliding mode controller to obtain the output equation of the variable exponential reaching law sliding mode controller based on the extended state observer, and obtain the output of the variable exponential reaching law sliding mode controller based on the extended state observer It is expressed as the following formula:

4. The high robustness performance control method of the PMSG-PWM rectifier system based on LCL filtering according to claim 3 is characterized in that: The active current reference quantity based on the variable exponential reaching law of the extended state observer, the PMSG side terminal voltage and the three-phase current signal are input into the inner loop predictive current control module to obtain the current inner loop final control model, which specifically includes: Collect the terminal voltage and three-phase current signals on the PMSG side and transform them from abc to (d, q) coordinate system, and input the transformed terminal voltage and three-phase current signals into the inner loop predictive current control module; Setting reactive current reference value The reactive current reference value is combined with the active current reference value based on the variable exponential reaching law of the extended state observer Transform the coordinate system from (d, q) to (α, β), and input the transformed reactive current reference value and the active current reference value based on the variable exponential reaching law of the extended state observer into the inner loop prediction current module; The inner loop prediction current module obtains the voltage reference vector based on the transformed terminal voltage, three-phase current signal, reactive current reference value and active current reference based on the variable exponential reaching law of the extended state observer through algorithm control. That is the final control model of the current inner loop.

5. The high robustness performance control method of the PMSG-PWM rectifier system based on LCL filtering according to claim 4 is characterized in that: The inner loop prediction current module is based on the transformed terminal voltage, three-phase current signal, reactive current reference value and active current reference based on the variable exponential reaching law of the extended state observer, and obtains the voltage reference vector through algorithm control. That is, the final control model of the current inner loop specifically includes: Define the PWM rectifier AC side voltage u α and u β for: Among them, u α is the α-axis voltage on the AC side of the PWM rectifier, u α is the β-axis voltage on the AC side of the PWM rectifier; Based on u α and u β Formula, the PMSG-PWM rectifier system current mathematical model is rewritten as: Among them, i α and i β are the α-axis and β-axis currents of the AC side of the PWM rectifier respectively; α and e β are the α-axis and β-axis voltages on the AC side of the PWM rectifier, respectively, and L is the sum of the external inductance and the PMSG equivalent inductance; In a sampling period T s Within the time, take the average value of each variable in the rewritten mathematical model and transform the mathematical model into: Among them, T s =t k+1 -t k , t k and t k+1 Corresponding to the two moments before and after respectively; When the system is stable, the actual current on the AC side quickly tracks the reference current, so there is i * (t k+1 )=i(t k+1 ), the average voltage of the AC side in one cycle Defined as reference voltage And perform an inverse transformation from (α, β) to the abc coordinate system, and the result is the input signal of the space vector pulse width modulation module, and the final control model of the current inner loop is: in, and i d *The reference current components corresponding to the α and β axes after the (d, q) to (α, β) coordinate system transformation.

6. A high robustness control system for a PMSG-PWM rectifier system based on LCL filtering, characterized in that: The system includes a data acquisition module, a first active current reference quantity calculation module, an observation value calculation module, a second active current reference quantity calculation module and a control model calculation module; The data acquisition module is used to collect the DC side voltage u of the PWM rectifier dc and with the given reference value Perform difference calculation to obtain the first difference, collect the PMSG side terminal voltage signal, and calculate its effective value U rms ; The first active current reference quantity calculation module is used to obtain the first difference and the effective value U rms The active current reference is input into the outer loop sliding mode controller, and the active current reference is obtained based on the output equation of the outer loop sliding mode controller; The observation value calculation module is used to convert the DC side voltage u of the PWM rectifier dc and the effective value U rms Input into the extended state observer to obtain the observed value z2 of the total disturbance d(t) of the system; The second active current reference calculation module is used to substitute the observed value z2 of the total system disturbance d(t) into the output equation of the outer loop sliding mode controller to obtain the active current reference based on the variable exponential reaching law of the extended state observer; The control model calculation module is used to input the active current reference based on the variable exponential reaching law of the extended state observer, the PMSG side terminal voltage and the three-phase current signal into the inner loop predictive current control module to obtain the current inner loop final control model.

7. The high robustness performance control system of the PMSG-PWM rectifier system based on LCL filtering according to claim 6, characterized in that: The first active current reference quantity calculation module is specifically used for: Establish a variable exponential reaching law function, as follows: Wherein, e is the difference between the reference voltage and the actual voltage on the DC side of the PWM rectifier, that is, the first difference, ε is the switching function coefficient, k is the exponential reaching law coefficient, s is the sliding mode equation, The reaching law function is combined with the mathematical model of the PMSG-PWM rectifier system to obtain the output equation based on the outer loop sliding mode controller, which is expressed as follows: In the formula, is the active current reference, C is the DC side filter capacitor, e d is the direct axis component of the voltage at the PMSG side terminal in the dq coordinate system, R is the PMSG equivalent resistance, R L is the load resistance, e2=s2=u dc * -u dc ,i d is the actual active component of current.

8. The high robustness performance control system of the PMSG-PWM rectifier system based on LCL filtering according to claim 7, characterized in that: The observation value calculation module is specifically used for: Define the external disturbance of the system as T(t), when the system is in steady-state operation at unity power factor, i q =0,i q is the reactive component of the PMSG side current, ignoring the PMSG equivalent resistance and the external inductor equivalent resistance, and rewriting the mathematical model of the PMSG-PWM rectifier system as follows: In order to improve the system's anti-interference ability, the total disturbance of the system is defined as: The total disturbance covers the DC side voltage, circuit parameters, AC side current tracking error and external disturbances. By observing the total disturbance, the impact of various disturbances on the system can be avoided in advance, thus improving the system robustness. According to the definition of the total disturbance d(t) of the system, the mathematical model of the PMSG-PWM rectifier system is simplified as follows: In the formula, Analysis shows that the voltage outer loop mathematical model is expanded to a second-order system, and the state equation is: Where x1(t) = u dc , x2(t)=d(t). Finally, the second-order extended state observer is obtained as: Among them, z1 and z2 are u dc , d(t) are the observed quantities, β1 and β2 are the ESO design parameters; The second active current reference quantity calculation module is specifically used for: Substitute the voltage outer loop comprehensive disturbance d(t) observation z2 obtained by the extended state observer into the output equation of the outer loop sliding mode controller to obtain the output equation of the variable exponential reaching law sliding mode controller based on the extended state observer, and obtain the output of the variable exponential reaching law sliding mode controller based on the extended state observer It is expressed as the following formula:

9. The high robustness performance control system of the PMSG-PWM rectifier system based on LCL filtering according to claim 8, characterized in that: The control model calculation module is specifically used for: Collect the PMSG side terminal voltage and three-phase current signals and transform the abc to (d, q) coordinate system, and input the transformed electromotive force and three-phase current signals into the inner loop predictive current control module; Setting reactive current reference value The reactive current reference value is combined with the active current reference value based on the variable exponential reaching law of the extended state observer Transform the coordinate system from (d, q) to (α, β), and input the transformed reactive current reference value and the active current reference value based on the variable exponential reaching law of the extended state observer into the inner loop prediction current module; The inner loop prediction current module obtains the voltage reference vector based on the transformed electromotive force, three-phase current signal, reactive current reference value and active current reference based on the variable exponential reaching law of the extended state observer through algorithm control. That is the final control model of the current inner loop.

10. The high robustness performance control system of the PMSG-PWM rectifier system based on LCL filtering according to claim 9, characterized in that: The inner loop prediction current module is based on the transformed electromotive force, three-phase current signal, reactive current reference value and active current reference based on the variable exponential reaching law of the extended state observer, and obtains the voltage reference vector through algorithm control. That is, the final control model of the current inner loop specifically includes: Define the PWM rectifier AC side voltage u α and u β for: Among them, u α is the α-axis voltage on the AC side of the PWM rectifier, u α is the β-axis voltage on the AC side of the PWM rectifier; Based on u α and u β Formula, the PMSG-PWM rectifier system current mathematical model is rewritten as: Among them, i α and i β are the α-axis and β-axis currents of the AC side of the PWM rectifier respectively; α and e β are the α-axis and β-axis voltages on the AC side of the PWM rectifier, respectively, and L is the sum of the PMSG equivalent inductance and the external inductance; In a sampling period T s Within the time, take the average value of each variable in the rewritten mathematical model and transform the mathematical model into: Among them, T s =t k+1 -t k , t k and t k+1 Corresponding to the two moments before and after respectively; When the system is stable, the actual current on the AC side quickly tracks the reference current, so there is i * (t k+1 )=i(t k+1 ), the average voltage of the AC side in one cycle Defined as reference voltage And perform an inverse transformation from (α, β) to the abc coordinate system, and the result is the input signal of the space vector pulse width modulation module, and the final control model of the current inner loop is: in, and i d *The reference current components corresponding to the α and β axes after the (d, q) to (α, β) coordinate system transformation.

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