Improved Active Disturbance Rejection Control Method for Solar Storage Converter Based on Fractional-Order Integral Sliding Mode

Abstract

The invention discloses an improved anti-disturbance control method for a photovoltaic power converter based on a fractional-order integral sliding mode. By introducing fractional-order calculus into a sliding mode model, a proposed fractional-order sliding mode speed controller is designed to have a sliding mode surface composed of a fractional-order differential. The chattering phenomenon of the sliding mode is improved by introducing a traditional exponential reaching law. A finite-time observer is adopted to ensure the homogeneity of the observation error system, thereby making the stability stronger and ensuring a stable trajectory tracking effect. A fractional-order integral sliding mode controller is adopted to obtain a current in a two-phase rotating coordinate system by subjecting a three-phase output current to d-q coordinate transformation. The current error is taken as input and introduced into a sliding mode surface parameter, and is mutually corrected with the reaching law, so that the system is continuously corrected in a stable direction.

Description

Technical Field

[0001] The invention belongs to the technical field of power electronics, and in particular relates to an improved auto-disturbance rejection control method for a photovoltaic storage converter based on a fractional-order integral sliding mode. Background Art

[0002] With the gradual development of society, people's demand for energy is gradually expanding. However, the non-renewable and unclean nature of traditional energy such as coal, oil and natural gas has led to an increasing shortage of energy. Therefore, the replacement of traditional energy with new energy is imminent. Clean energy includes light energy, wind energy, tidal energy, etc., and the research on solar clean energy is also gradually deepening. However, due to the influence of uncontrollable factors such as temperature and light intensity, the output power of the photovoltaic power generation system will have a large fluctuation, which will cause damage to the equipment in the system or reduce the service life. In addition, the photovoltaic power generation system directly connected to the large power grid will reduce the point power quality and cause large fluctuations in the DC bus, affecting the power supply and distribution efficiency and quality. Therefore, incorporating energy storage systems into photovoltaic systems is a favorable method to improve the stability of the power grid.

[0003] In the photovoltaic and energy storage grid-connected system, the photovoltaic and energy storage converter coupled by the DC bus is an important part of the energy storage system. Traditional PI control is difficult to control due to its nonlinearity, strong coupling and multi-input and multi-output characteristics, making it difficult to meet the control requirements. In the face of the high-precision and fast-response control requirements of photovoltaic and energy storage converters, domestic and foreign researchers have proposed control methods such as sliding mode control, anti-disturbance control, fuzzy control and model predictive control. Although fuzzy control is simple to control and does not require a mathematical model of the controlled object, its lack of systematicity and difficulty in parameter adjustment have some impact on the stable control of photovoltaic and energy storage converters. Although model predictive control is good at handling multi-input and multi-output systems, it cannot have sufficient control over photovoltaic and energy storage converters due to its complex calculations and the influence of model errors. Summary of the invention

[0004] The purpose of the present invention is to provide an improved auto-disturbance rejection control method for a photovoltaic storage converter based on a fractional-order integral sliding mode, which solves the problems of poor vibration suppression effect and slow convergence speed of the traditional sliding mode.

[0005] The technical solution adopted by the present invention is to improve the anti-disturbance control method of the photovoltaic storage converter based on the fractional-order integral sliding mode, which is used to control the subsequent converter of the photovoltaic storage converter, and the subsequent converter is a three-phase full-bridge inverter, which is specifically implemented according to the following steps:

[0006] Step 1: Construct the spatial state equation of the three-phase full-bridge inverter;

[0007] Step 2: Convert the spatial state equation of the three-phase full-bridge inverter into a mathematical model in the dq axis rotating coordinate system through dq transformation;

[0008] Step 3: Construct the ADRC paradigm and design the finite-time observer;

[0009] Step 4: The given active power and reactive power are passed through the power outer loop to obtain the current reference value of the dq axis of the current inner loop;

[0010] Step 5: Construct a fractional-order integral sliding mode surface and improve the system chattering phenomenon by using the exponential reaching law, thereby constructing a fractional-order integral sliding mode controller;

[0011] Step 6: Obtain the control output through the fractional-order integral sliding mode controller, use SPWM modulation to obtain the duty cycle, and apply the duty cycle to the control of the three-phase full-bridge inverter switch tube, thereby realizing signal control of the full-bridge switch.

[0012] The present invention is also characterized in that:

[0013] Step 1 is as follows:

[0014] The mathematical model of the three-phase full-bridge inverter in the three-phase coordinate system is:

[0015]

[0016] In formula (1), U ao , U bo , U co are the sum of the voltage of the filter part of the three-phase inverter a, b, c phases and the voltage on the distribution network side, R is the equivalent resistance, i a 、i b 、i c They are the three-phase output currents of a, b, and c of the three-phase full-bridge inverter, L is the AC filter inductance of the three-phase full-bridge inverter, and e is the AC filter inductance of the three-phase full-bridge inverter. a 、e b 、e c They are the three-phase voltages a, b, and c on the grid-connected side respectively.

[0017] Step 2 is as follows:

[0018] Convert equation (1) from the three-phase coordinate system to the two-phase rotating dq coordinate system, and the mathematical model in the two-phase coordinate system is:

[0019]

[0020] In formula (2), R is the filter resistance of the three-phase full-bridge inverter, ω is the grid voltage angular frequency; u d 、u q are the output voltages on the d and q axes, u d =s d u dc 、uq =s q u dc ;s d 、s q are the d and q axis switching functions respectively; u dc is the bus voltage on the DC side; e d 、e q are the components of the grid voltage on the d and q axes respectively; i Ld 、i Lq are the components of the grid-side current on the d and q axes respectively;

[0021] Deriving equation (2) transforms it into a paradigm that satisfies the second-order auto-disturbance rejection:

[0022]

[0023] Step 3 is as follows:

[0024] Define the control object:

[0025]

[0026] In formula (4), y is the output of the three-phase inverter system, u is the input control of the system, b is the gain of the control quantity u, and b d , b q That is, the control amount u of the d and q axes d 、u q The gain of F is the sum of all disturbances in the system, where y = [y1y2] T ; b = [b d b q ] T ; u=[u d u q ] T ; F=[F d F q ] T , define F d 、F q is the lumped disturbance of d and q axes; define y1=i Ld , y2=i Lq ,y ref is the output target value, and the output target values ​​on the d and q axes are defined as i and Ldref ,i Lqref ;

[0027] Express equation (4) in matrix form:

[0028]

[0029] In formula (5), b d , b q 、F d、F q It is expressed as:

[0030]

[0031] Define the d-axis state variable x d1 =e1, x d3 =F d , the q-axis state variable is x q1 =e2, x q3 =F q , then the spatial state equation of the system shown in formula (4) is:

[0032]

[0033] According to the spatial state expression of formula (7), the form of designing the finite time observer is:

[0034]

[0035] In formula (9), k1, k2, k3, k4, k5, k6 are observer gains, 0.5<α1<1, α i =iα-(i-1),α=α1, where i=1,2,3,4...;z d1 、z d2 、z d3 、z q1 、z q2 、z q3 x d1 、x d2 、x d3 、x q1 、x q2 、x q3 Observed value of .

[0036] Step 4 is as follows:

[0037] Assume that the active power and reactive power reference values ​​of the photovoltaic power converter are P ref , Q ref When the solar storage converter is running, the inner loop d and q axis current reference values ​​i Ldref 、i Lqref Respectively expressed as:

[0038]

[0039] Step 5 is as follows:

[0040] Assume i Ld 、i Lq The deviations e1 and e2 from the corresponding current reference values ​​are:

[0041]

[0042] The operator representing fractional calculus is defined as:

[0043]

[0044] In formula (11), R(λ) is the real part of λ, λ is a real number and the order of calculus; α and t are the upper and lower limits of the operator respectively;

[0045] The sliding surface adopts fractional integral sliding mode, and defines the fractional integral sliding surface s of the d-axis and q-axis d 、s q for:

[0046]

[0047] In formula (12), p1, p2, p3, p4 are positive constants, λ+1 is the order of the fractional integral, and λ>0;

[0048] Derivation of formula (12) yields:

[0049]

[0050] The exponential approaching laws of the d and q axes are introduced as y1 and y2:

[0051]

[0052] In formula (13), ε1, ε2, p5, p6 are positive constants;

[0053] Combining equation (13) and equation (14), we can get the control law u of d and q axes: d 、u q for:

[0054]

[0055] The beneficial effects of the present invention are:

[0056] 1) The improved anti-disturbance control method for photovoltaic power converter based on fractional-order integral sliding mode of the present invention aims at the shortcomings of traditional sliding mode. By introducing fractional-order calculus into the sliding mode model, the proposed fractional-order sliding mode speed controller is designed with a sliding mode surface composed of a fractional-order differential. The chattering phenomenon of the sliding mode is improved by introducing the traditional exponential reaching law. It has the characteristics of fast convergence speed, high tracking accuracy and better anti-interference suppression performance. Compared with the traditional sliding mode control, the chattering effect is smaller.

[0057] 2) The finite time observer is used, which not only has the characteristics of observing disturbances like the traditional observer, but also does not need to establish an accurate mathematical model of the grid-connected inverter. It also has the characteristics of finite time convergence. The finite time observer ensures the homogeneity of the observation error system by designing the parameters of the observer, making it more stable and ensuring a stable trajectory tracking effect.

[0058] 3) A fractional-order integral sliding mode controller is used to convert the three-phase output current into a two-phase rotating coordinate system through dq coordinate transformation. The current error is used as input, introduced into the sliding surface parameters, and corrected with the reaching law, so that the system is continuously corrected in a stable direction. BRIEF DESCRIPTION OF THE DRAWINGS

[0059] Figure 1 It is a general control block diagram of the improved auto-disturbance rejection control method of the photovoltaic storage converter based on fractional-order integral sliding mode of the present invention;

[0060] Figure 2 It is the main circuit topology diagram of the photovoltaic storage converter;

[0061] Figure 3 It is a simplified control block diagram of the post-stage converter of the photovoltaic storage converter according to the improved auto-disturbance rejection control method of the photovoltaic storage converter based on fractional-order integral sliding mode of the present invention;

[0062] FIG4 is a dynamic response diagram of the output power of the AC side of the three-phase full-bridge inverter when the load power is suddenly reduced from 40 kW to -40 kW under different control conditions, wherein FIG4(a) is a transient response diagram of the three-phase current b-phase, the voltage b-phase and the DC bus voltage, and FIG4(b) is a transient response diagram of the three-phase current b-phase, the voltage b-phase and the DC bus voltage under the control of the present invention;

[0063] FIG5 is a diagram showing the dynamic response of the output power of the AC side of the three-phase full-bridge inverter when the load power suddenly increases from -40 kW to 40 kW under different control conditions, wherein FIG5(a) is a diagram showing the transient response of the three-phase current b-phase, the voltage b-phase and the DC bus voltage, and FIG5(b) is a diagram showing the transient response of the three-phase current b-phase, the voltage b-phase and the DC bus voltage under the control of the present invention;

[0064] Figure 6 This is the three-phase current waveform output by the three-phase full-bridge inverter;

[0065] Figure 7 This is the harmonic analysis diagram of grid-connected current under PI control strategy;

[0066] Figure 8 This is a harmonic analysis diagram of the grid-connected current under the control of the present invention. DETAILED DESCRIPTION

[0067] The present invention is described in detail below with reference to the accompanying drawings and specific embodiments.

[0068] Example 1

[0069] This embodiment provides an improved auto-disturbance rejection control method for a photovoltaic storage converter based on a fractional-order integral sliding mode, which is used to control a subsequent converter of the photovoltaic storage converter. The subsequent converter is a three-phase full-bridge inverter. The overall structure of the photovoltaic storage converter is as follows: Figure 1 As shown, it is mainly composed of a bidirectional DC-DC converter, a photovoltaic array, an energy storage battery, a three-phase full-bridge inverter, a filter, an AC load and a distribution network. Among them, MPPT is the maximum power tracking technology. It is connected to the bus through the MPPT algorithm to achieve the maximum power tracking of the bus voltage. The energy storage system can generate a bidirectional flow of energy with the bus through the DC converter. The back-stage converter is composed of a three-phase full-bridge inverter, a filter and a distribution network. The photovoltaic storage converter is composed of a bidirectional chopper and a three-phase full-bridge inverter. Among them, S1~S6 are the switch tubes of the three-phase converter; S7 and S8 are the switch tubes of the DC chopper, e a 、e b 、e c is the phase voltage on the grid side; C dc is the DC side capacitance; L bat is the DC chopper filter inductor; u bat is the battery output voltage; i L is the battery output current, which flows through the inductor L bat The current; i out is the current input from the DC bus to the converter; i pv It is the current output by the photovoltaic array after MPPT;

[0070] S j Indicates the on / off status of the switch tubes in each bridge arm of the converter:

[0071]

[0072] like Figure 2 As shown, the method is specifically implemented according to the following steps:

[0073] Step 1: Construct the spatial state equation of the three-phase full-bridge inverter;

[0074] The mathematical model of the three-phase full-bridge inverter in the three-phase coordinate system is:

[0075]

[0076] In formula (1), U ao , U bo , U co are the sum of the voltage of the filter part of the three-phase inverter a, b, c phases and the voltage on the distribution network side, R is the equivalent resistance, i a 、ib 、i c They are the three-phase output currents of a, b, and c of the three-phase full-bridge inverter, L is the AC filter inductance of the three-phase full-bridge inverter, and e is the AC filter inductance of the three-phase full-bridge inverter. a 、e b 、e c They are the three-phase voltages a, b, and c on the grid-connected side;

[0077] Step 2: Convert the spatial state equation of the three-phase full-bridge inverter into a mathematical model in the dq axis rotating coordinate system through dq transformation;

[0078] Convert equation (1) from the three-phase coordinate system to the two-phase rotating dq coordinate system, and the mathematical model in the two-phase coordinate system is:

[0079]

[0080] In formula (2), R is the filter resistance of the three-phase full-bridge inverter, ω is the grid voltage angular frequency; u d 、u q are the output voltages on the d and q axes, u d =s d u dc 、u q =s q u dc ;s d 、s q are the d and q axis switching functions respectively; u dc is the bus voltage on the DC side; e d 、e q are the components of the grid voltage on the d and q axes respectively; i Ld 、i Lq are the components of the grid-side current on the d and q axes respectively;

[0081] Deriving equation (2) transforms it into a paradigm that satisfies the second-order auto-disturbance rejection:

[0082]

[0083] Step 3: Construct the ADRC paradigm and design the finite-time observer;

[0084] Step 4: The given active power and reactive power are passed through the power outer loop to obtain the current reference value of the dq axis of the current inner loop;

[0085] Step 5: Construct a fractional-order integral sliding mode surface and improve the system chattering phenomenon by using the exponential reaching law, thereby constructing a fractional-order integral sliding mode controller;

[0086] Step 6: Obtain the control output through the fractional-order integral sliding mode controller, use SPWM modulation to obtain the duty cycle, and apply the duty cycle to the control of the three-phase full-bridge inverter switch tube, thereby realizing signal control of the full-bridge switch.

[0087] Example 2

[0088] This embodiment provides an improved active disturbance rejection control method for a photovoltaic storage converter based on a fractional-order integral sliding mode. Based on Embodiment 1, step 3 is specifically as follows:

[0089] Define the control object:

[0090]

[0091] In formula (4), y is the output of the three-phase inverter system, u is the input control of the system, b is the gain of the control quantity u, and b d , b q That is, the control amount u of the d and q axes d 、u q The gain of F is the sum of all disturbances in the system, where y = [y1y2] T ; b = [b d b q ] T ; u=[u d u q ] T ; F=[F d F q ] T , define F d 、F q is the lumped disturbance of d and q axes; define y1=i Ld , y2=i Lq ,y ref is the output target value, and the output target values ​​on the d and q axes are defined as i and Ldref ,i Lqref ;

[0092] Express equation (4) in matrix form:

[0093]

[0094] In formula (5), b d , b q 、F d 、F q It is expressed as:

[0095]

[0096] Define the d-axis state variable x d1 =e1, xd3 =F d , the q-axis state variable is x q1 =e2, x q3 =F q , then the spatial state equation of the system shown in formula (4) is:

[0097]

[0098] According to the spatial state expression of formula (7), the form of designing the finite time observer is:

[0099]

[0100] In formula (9), k1, k2, k3, k4, k5, k6 are observer gains, 0.5<α1<1, α i =iα-(i-1),α=α1, where i=1,2,3,4...;z d1 、z d2 、z d3 、z q1 、z q2 、z q3 x d1 、x d2 、x d3 、x q1 、x q2 、x q3 Observed value of .

[0101] Example 3

[0102] This embodiment provides an improved active disturbance rejection control method for a photovoltaic storage converter based on a fractional-order integral sliding mode. Based on Embodiment 1-2, step 4 is specifically as follows:

[0103] Assume that the active power and reactive power reference values ​​of the photovoltaic power converter are P ref , Q ref When the solar storage converter is running, the inner loop d and q axis current reference values ​​i Ldref 、i Lqref Respectively expressed as:

[0104]

[0105] Step 5 is as follows:

[0106] Assume i Ld 、i Lq The deviations e1 and e2 from the corresponding current reference values ​​are:

[0107]

[0108] The operator representing fractional calculus is defined as:

[0109]

[0110] In formula (11), R(λ) is the real part of λ, λ is a real number and the order of calculus; α and t are the upper and lower limits of the operator respectively;

[0111] The sliding surface adopts fractional integral sliding mode, and defines the fractional integral sliding surface s of the d-axis and q-axis d 、s q for:

[0112]

[0113] In formula (12), p1, p2, p3, and p4 are positive constants, λ+1 is the order of the fractional integral, and λ>0; the sliding surface adopts a fractional integral sliding mode, and the integral sliding mode control makes the system state converge quickly to the predetermined trajectory within a finite time, so that the dynamic response speed and accuracy are improved. The integral operator in the fractional order has the characteristics of gradual forgetting and slow energy conversion. Introducing it into the sliding mode control can not only weaken the chattering phenomenon of the sliding mode control, but also enable the control method to obtain more degrees of freedom, which has a significant effect on improving the control performance;

[0114] Derivation of formula (12) yields:

[0115]

[0116] The exponential approaching laws of the d and q axes are introduced as y1 and y2:

[0117]

[0118] In formula (14), ε1, ε2, p5, and p6 are positive constants. The approach speed of the exponential approach law gradually decreases from a large value to 0, which not only shortens the approach time, but also makes the speed of the moving point when it reaches the switching surface very small. An equal-speed approach term is added to ensure that it arrives in a limited time. In order to ensure rapid approach and weaken chattering, ε should be reduced while increasing p;

[0119] Combining equation (13) and equation (14), we can get the control law u of d and q axes: d 、u q for:

[0120]

[0121] In summary, the control block diagram of the post-stage converter of the photovoltaic storage converter of the present invention is as follows: Figure 3 shown.

[0122] Simulation and experimental analysis

[0123] In order to verify the effectiveness of the control method designed by the present invention, a simulation circuit was built in MATLAB / Simulink simulation software, and a comparative analysis was performed with the traditional PI control strategy. Here, the power is defined as positive when the voltage and current directions are consistent. The simulation parameter settings are shown in Table 1. During the simulation process, the same simulation environment and parameter settings were used to ensure the fairness and accuracy of the comparison results.

[0124] Table 1 Circuit parameters

[0125] parameter Numeric <![CDATA[Grid voltage amplitude e a 、e b 、e c > 311V <![CDATA[DC bus voltage U dc > 800V Filter inductor L 5mH Filter capacitor C 50μF Inductor parasitic resistance R 0.01Ω <![CDATA[DC regulated capacitor C dc > 2.2mF Load power 10kW-90kW <![CDATA[Battery terminal voltage v bat > 400V Battery initial state of charge SOC 50％

[0126] As shown in Figure 4, under the two control methods, when the load power suddenly changes, the output of 40kw in stable operation drops to -40kw, causing the dynamic response of the output power on the AC side of the three-phase full-bridge inverter. As shown in Figure 4 (a), the transition time under PI control is 44ms, and as shown in Figure 4 (b), the transition time of the control method of the present invention is extremely small, and the convergence speed is improved compared with PI control.

[0127] As shown in Figure 5, under the two control methods, when the load power suddenly changes from the stable output -40kw to 40kw, the output power of the three-phase full-bridge inverter on the AC side responds dynamically. As shown in Figure 5(a), the transition time under PI control is 34ms, and as shown in Figure 5(b), the transition time of the control method of the present invention is 12ms, and the convergence speed is improved compared with PI control.

[0128] Figure 6 The grid-side current waveform under the control method of the present invention when the load power suddenly increases from 30kw to 70kw and then suddenly decreases from 70kw to -10kw. It can be seen that the current waveform is stable without waveform distortion, and the AC current under the desired power can be achieved, which verifies the feasibility of the control of the present invention.

[0129] like Figure 7 As shown, it is the harmonic analysis of the grid-connected current of the energy storage converter under the traditional PI control, and the THD is 6.68%. Figure 8 The figure shows the harmonic analysis of the grid-connected current of the energy storage converter under the control of the present invention, and the THD is 1.42%. By comparison, it can be seen that the control of the present invention has a stronger harmonic suppression capability and improves the quality of grid-connected power.

Claims

1. An improved auto-disturbance rejection control method for a photovoltaic storage converter based on fractional-order integral sliding mode is used to control a subsequent converter of the photovoltaic storage converter, wherein the subsequent converter is a three-phase full-bridge inverter, and is characterized in that: Follow the steps below to implement it: Step 1: Construct the spatial state equation of the three-phase full-bridge inverter; The step 1 is specifically as follows: The mathematical model of the three-phase full-bridge inverter in the three-phase coordinate system is: （1） In formula (1), U ao , U bo , U co They are the sum of the voltage of the filter part of the three-phase inverter a, b, c phases and the voltage on the distribution network side. R is the equivalent resistance, i a , i b , i c They are the three-phase output currents of a, b, and c of the three-phase full-bridge inverter, L For the three-phase full-bridge inverter AC measurement filter inductor, e a , e b , e c They are the three-phase voltages a, b, and c on the grid-connected side; Step 2: Convert the spatial state equation of the three-phase full-bridge inverter into a mathematical model in the dq axis rotating coordinate system through dq transformation; The step 2 is specifically as follows: Convert equation (1) from the three-phase coordinate system to the two-phase rotating dq coordinate system, and the mathematical model in the two-phase coordinate system is: （2） In formula (2), R is the filter resistor of the three-phase full-bridge inverter, ω is the grid voltage angular frequency; u d , u q are the output voltages on the d and q axes respectively, u d =s d u dc , u q =s q u dc ;s d 、s q They are the d and q axis switching functions respectively; u dc is the bus voltage on the DC side; e d , e q are the components of the grid voltage on the d and q axes respectively; i Ld , i Lq are the components of the grid-side current on the d and q axes respectively; Deriving equation (2) transforms it into a paradigm that satisfies the second-order auto-disturbance rejection: （3）； Step 3: Construct the ADRC paradigm and design the finite-time observer; The step 3 is specifically as follows: Define the control object: （4） In formula (4), y is the output of the three-phase inverter system, u is the input control of the system, b For control u The gain, b d , b q That is, the control amount of the d and q axes u d , u q The gain, F is the sum of all disturbances in the system, where y =[ y 1 y 2] T ; b =[ b d b q ] T ; u =[ u d u q ] T ; F =[ F d F q ] T ,definition F d , F q is the lumped disturbance of d and q axes; definition y 1 =i Ld , y 2 =i Lq , y ref is the output target value, and the output target values ​​on the d and q axes are defined as i Ldref , i Lqref ; Express equation (4) in matrix form: （5） In formula (5), b d , b q , F d , F q It is expressed as: （6） Define the d-axis state variable , , , the q-axis state variable is , , , then the spatial state equation of the system shown in formula (4) is: （7） According to the spatial state expression of formula (7), the form of designing the finite time observer is: （8） In formula (8), k1, k2, k3, k4, k5, k6 are observer gains, , ,in i = 1,2,3,4…; z d1 , z d2 , z d3 , z q1 , z q2 , z q3 They are x d1 , x d2 , x d3 , x q1 , x q2 , x q3 Observed value of Step 4: The given active power and reactive power are passed through the power outer loop to obtain the current reference value of the dq axis of the current inner loop; Step 5: Construct a fractional-order integral sliding mode surface and improve the system chattering phenomenon by using the exponential reaching law, thereby constructing a fractional-order integral sliding mode controller; Step 6: Obtain the control output through the fractional-order integral sliding mode controller, use SPWM modulation to obtain the duty cycle, and apply the duty cycle to the control of the three-phase full-bridge inverter switch tube, thereby realizing signal control of the full-bridge switch.

2. The improved active disturbance rejection control method for photovoltaic power storage converter based on fractional-order integral sliding mode according to claim 1 is characterized in that: The step 4 is specifically as follows: Assume that the active power and reactive power reference values ​​of the photovoltaic power converter are P ref , Q ref When the solar storage converter is running, the inner ring d and q axis current reference values ​​are i Ldref , i Lqref Respectively expressed as: （9）。 3. The improved active disturbance rejection control method for photovoltaic power converter based on fractional-order integral sliding mode according to claim 2 is characterized in that: The step 5 is specifically as follows: set up i Ld , i Lq Deviation from the corresponding current reference value e 1. e 2 is: （10） The operator representing fractional calculus is defined as: （11） In formula (11), for The real part of is a real number, the order of calculus; and t are the upper and lower limits of the operator respectively; The sliding surface adopts fractional integral sliding mode, and defines the fractional integral sliding surface of the d-axis and q-axis s d , s q for: （12） In formula (12), p 1. p 2. p 3. p 4 is a positive constant. λ +1 is the order of the fractional integral, and λ >0; Derivative of formula (12) yields: （13） Introducing the exponential reaching law of d and q axes, we have y 1. y 2: （14） In formula (14), is a positive constant; Combining equation (13) and equation (14), we can get the control law of d and q axes: u d , u q for: （15）。

Images