Photovoltaic micro-grid energy storage system based on improved active disturbance rejection control

Abstract

The application discloses a photovoltaic microgrid energy storage system based on improved active disturbance rejection control, which comprises a photovoltaic microgrid power generation unit, a super capacitor energy storage unit, a storage battery energy storage unit, a direct current load unit, a bidirectional DC-DC converter and a direct current bus; the super capacitor energy storage unit and the storage battery energy storage unit are connected to the direct current bus through the bidirectional DC-DC converter to form a hybrid energy storage system; the photovoltaic microgrid power generation unit, the storage battery energy storage unit, the super capacitor energy storage unit and the direct current load unit are connected to the direct current bus through a common access point PCC; and the bidirectional DC-DC converter comprises an energy storage device, an inductor coil, a bridge arm and a support capacitor; one end of the energy storage device is electrically connected with the inductor coil; one end of the inductor coil is electrically connected with two bridge arms; and the two ends of the two bridge arms are commonly connected with the support capacitor. The application has the characteristics of high practicability.

Description

Technical Field

[0001] This invention relates to the field of photovoltaic energy storage system control technology, specifically a photovoltaic microgrid energy storage system based on improved active disturbance rejection control. Background Technology

[0002] Active Disturbance Rejection Control (ADRC) is a novel control technology proposed by scholar Han Jingqing based on the essence of error feedback in PID control theory. It is a new and practical digital control technology that does not rely on an accurate model of the controlled object and can replace PID control technology.

[0003] The core idea of ​​Active Disturbance Rejection Control (ADRC) technology is to use an extended state observer to estimate and compensate for the total disturbance of the system (the sum of external and internal disturbances) in real time, thereby constructing a control system with "active disturbance rejection capability". ADRC control systems typically consist of three parts: a tracking differentiator (TD), an extended state observer (ESO), and nonlinear state error feedback (NLSEF).

[0004] Linear Active Disturbance Rejection Control (LADRC) is a design method based on ADRC, which combines a tracking differentiator, a nonlinear PD controller, and a linear extended observer (LESO) to compensate for system disturbances.

[0005] Traditional active disturbance rejection includes differentiators (TDs) for acquiring differential signals and tracking transient process configurations, extended state observers (ESOs) for observing total disturbances, and nonlinear error feedback control laws (NLSEFs) for generating control variables. Linear ADRC simplification is primarily geared towards engineering applications in factories, and existing factories generally have relatively mature and comprehensive methods for configuring transient processes.

[0006] ESO: Extended State Observer. ESO is the core component of ADRC's operating controller. ESO can estimate the total disturbances of the system in real time (including "external disturbances" such as noise and "internal disturbances" such as changes in internal system parameters), thereby enabling the modification of the original system.

[0007] NLSEF: Non-linear state error feedback is a non-linear error feedback control law designed based on the damped fastest feedback function.

[0008] In existing photovoltaic microgrid energy storage systems, in order to enable energy storage devices in the photovoltaic microgrid system to quickly perform power frequency distribution to meet the requirements of effective operation of the photovoltaic microgrid, the current technology mostly adopts traditional PID control in the control of energy storage converters to obtain DC side voltage control; however, in actual production, there is a large overshoot phenomenon and the system has large fluctuations.

[0009] Meanwhile, when existing solar panels are in use, birds perch on them, not only blocking the solar panels but also sometimes defecating on them, bringing in branches and other debris, which affects the solar conversion efficiency.

[0010] Therefore, it is necessary to design a practical photovoltaic microgrid energy storage system based on improved active disturbance rejection control. Summary of the Invention

[0011] The purpose of this invention is to provide a photovoltaic microgrid energy storage system based on improved active disturbance rejection control to solve the problems mentioned in the background art.

[0012] To solve the above-mentioned technical problems, the present invention provides the following technical solution: a photovoltaic microgrid energy storage system based on improved active disturbance rejection control, comprising a photovoltaic microgrid power generation unit, a supercapacitor energy storage unit, a battery energy storage unit, a DC load unit, a bidirectional DC-DC converter, and a DC bus;

[0013] The supercapacitor energy storage unit and the battery energy storage unit are respectively connected to the DC bus through a bidirectional DC-DC converter to form a hybrid energy storage system. The photovoltaic microgrid power generation unit, the battery energy storage unit, the supercapacitor energy storage unit and the DC load unit are connected to the DC bus through a common access point PCC.

[0014] According to the above technical solution, the bidirectional DC-DC converter includes an energy storage device, an inductor coil, bridge arms, and a supporting capacitor. One end of the energy storage device is electrically connected to the inductor coil, and one end of the inductor coil is electrically connected to two bridge arms. The two ends of the two bridge arms are connected to the supporting capacitor.

[0015] According to the above technical solution, the system also includes a working method comprising configuring the transition process in the linearized, simplified tracking differentiator TD, linearizing the extended state observer ESO, and simplifying the connection between the extended state observer ESO parameters and the observer bandwidth; employing a PD controller combination, and simplifying the controller tuning by connecting Kp, Kd and the controller bandwidth; the tracking differentiator TD is used for differentiating signal acquisition and the transition process, and the linearized extended state observer ESO is used for observing the total disturbance, which includes external noise disturbance and internal disturbance of system parameter changes.

[0016] According to the above technical solution, the system adopts a hybrid energy storage control method. The constant power control power reference value is divided by frequency to obtain the reference power that the supercapacitor and battery need to balance. This is used in actual microgrid systems where the power supply and load power are constantly changing, and the reference power is also constantly changing accordingly. Both the battery and the supercapacitor adopt dual closed-loop control with voltage outer loop and current inner loop. The outer loop adopts improved FLADRC feedforward linear active disturbance rejection control, and the inner loop adopts LADRC linear active disturbance rejection control.

[0017] According to the above technical solution, the specific method of LADRC linear active disturbance rejection is as follows: the improved ADRC adds a feedforward controller to the ADRC part to form FLADRC feedforward linear active disturbance rejection control. The feedforward controller introduces a positive feedback channel at the input signal position of the tracking differentiator, calculates the difference between the sampled voltage signal and the given voltage signal, and cancels the disturbance signal through the feedforward coefficient to achieve zero steady-state error tracking and disturbance compensation, while reducing the overshoot and settling time of the hybrid energy storage control system.

[0018] According to the above technical solution, the two-layer dual closed-loop control structure includes a battery dual-loop structure formed by external voltage loop control and battery current loop control, and a supercapacitor dual-loop structure formed by external voltage loop control and supercapacitor current loop control.

[0019] In the voltage loop control, feedforward active disturbance rejection control is adopted, and low-pass filtering is combined to convert the current component into a high-frequency component of the supercapacitor output reference current signal and a low-frequency component of the battery output reference current signal. Linear active disturbance rejection control is introduced into the battery current loop control and the supercapacitor current loop control respectively. The inductor current of the bidirectional DC-DC converter of the battery and the supercapacitor is controlled by two double closed-loop structures, thereby controlling the charging and discharging current of the hybrid energy storage system, which is used to improve the dynamic response speed and anti-interference capability of the hybrid energy storage system.

[0020] According to the above technical solution, the battery current loop adopts an improved linear active disturbance rejection controller. Compared with the traditional active disturbance rejection controller, the tracking differentiator stage is eliminated. Since the battery current loop needs to quickly track command changes, the battery current loop control mainly consists of two parts: a linear extended state observer and a proportional-derivative controller.

[0021] The voltage loop control section, combined with the ADRC with added feedforward controller, forms a FLADRC control loop. The battery section also uses ADRC to realize the battery current loop control, and the supercapacitor section also uses ADRC to realize the battery current loop control. Overall, two double closed-loop structures are formed to realize comprehensive control of the energy storage system.

[0022] According to the above technical solution, the working method of the photovoltaic microgrid power generation unit is as follows:

[0023] S1-1. When a bird lands on a photovoltaic cell, the light sensor obtains the outline of the covered area through sensing imaging, and obtains the area m of the thermal image of the covered area. The outline analysis module calculates the size of the bird.

[0024] S1-2, The calculated area is transmitted to the current boosting module of the photovoltaic cell, and the current regulating module in other normal operating areas supplies boosting current I to the current boosting module on the photovoltaic cell in the bird-staying area. k Among them, the current I increases k I is directly proportional to the area m of the thermal image of the covered region. k The thermal imaging area m needs to satisfy the formula Where M is the current parameter, which is selected according to actual needs, and I0 is the normal output current of the photovoltaic cell;

[0025] S1-3, after the focusing drive module receives the increased current, it operates in a high-power state.

[0026] According to the above technical solution, the boost current in the boosting module is supplied to the focusing drive module. The system is set to a high-power operating range, and the focusing drive module within this range operates in a high-power state through the boost current. The operating current I of the focusing drive module satisfies the formula:

[0027]

[0028] Where d is the distance between the illumination module and the bird imaging projection, μ is the current stabilization parameter, n is the total number of focusing drive modules, and i is the number of focusing drive modules in the high-power operating range.

[0029] Outside this range, the focusing drive module outputs current at low power based on the output current of the current regulation module, and its operating current is I = I0 - I k .

[0030] Compared with the prior art, the beneficial effects achieved by the present invention are as follows: The present invention provides a photovoltaic microgrid hybrid energy storage system scheme based on improved active disturbance rejection control to address the shortcomings of the prior art. The control method has good effect, strong robustness, and strong anti-interference ability, enabling the hybrid energy storage device to better balance power fluctuations.

[0031] By performing power self-division frequency allocation on different energy storage devices in a hybrid energy storage system, the stability of power on the grid-connected side can be improved, enabling rapid power response of energy storage devices in photovoltaic microgrid systems and providing good suppression of disturbances.

[0032] The solar panels can be used to scare away birds that are perched on them by concentrating sunlight. The intensity of the sunlight can be adjusted according to the size of the birds, thus preventing them from staying on the panels and improving their efficiency. Attached Figure Description

[0033] The accompanying drawings are provided to further illustrate the invention and form part of the specification. They are used in conjunction with embodiments of the invention to explain the invention and do not constitute a limitation thereof. In the drawings:

[0034] Figure 1 This is a schematic diagram of the photovoltaic microgrid system framework of the present invention;

[0035] Figure 2 This is a schematic diagram of the bidirectional DC-DC converter structure of the present invention;

[0036] Figure 3 This is a schematic diagram of the basic structure of the ADRC of the present invention;

[0037] Figure 4 This is a schematic diagram of the overall control strategy for hybrid energy storage control according to the present invention;

[0038] Figure 5 This is a schematic diagram of the feedforward self-rejection voltage loop control structure of the present invention;

[0039] Figure 6 This is a schematic diagram of the linear self-disruption rejection battery current loop control structure of the present invention;

[0040] Figure 7 This is a schematic diagram of the linear self-disturbance rejection supercapacitor current loop control structure of the present invention;

[0041] Figure 8 This is a schematic diagram of the photovoltaic microgrid hybrid energy storage system of the present invention;

[0042] Figure 9 This is a block diagram of the dual closed-loop control of the power outer loop and the current inner loop of the present invention. Detailed Implementation

[0043] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0044] Please see Figure 1-9The present invention provides a technical solution: a photovoltaic microgrid energy storage system based on improved active disturbance rejection control, comprising a photovoltaic microgrid power generation unit, a supercapacitor energy storage unit, a battery energy storage unit, a DC load unit, a bidirectional DC-DC converter, and a DC bus;

[0045] The supercapacitor energy storage unit and the battery energy storage unit are connected to the DC bus through bidirectional DC-DC converters to form a hybrid energy storage system. The photovoltaic microgrid power generation unit, the battery energy storage unit, the supercapacitor energy storage unit and the DC load unit are connected to the DC bus through a common access point PCC.

[0046] The bidirectional DC-DC converter includes an energy storage device, an inductor coil, bridge arms, and a supporting capacitor. One end of the energy storage device is electrically connected to the inductor coil, and one end of the inductor coil is electrically connected to two bridge arms. The two ends of the two bridge arms are connected to the supporting capacitor.

[0047] The system's operating method also includes the configuration of the transition process in the linearized, simplified tracking differentiator TD, the linearized extended state observer ESO, which simplifies the relationship between the extended state observer ESO parameters and the observer's bandwidth; a PD controller combination is used, which simplifies the controller tuning by relating Kp, Kd and the controller bandwidth; the tracking differentiator TD is used for differentiating signal acquisition and the transition process; and the linearized extended state observer ESO is used to observe the total disturbance, which includes external noise disturbances and internal disturbances caused by changes in system parameters.

[0048] The system employs a hybrid energy storage control method. The constant power control power reference value is divided by frequency to obtain the reference power that the supercapacitor and battery need to balance. This is used in actual microgrid systems where the power supply and load power are constantly changing, and the reference power is also constantly changing accordingly. Both the battery and the supercapacitor adopt dual closed-loop control with voltage outer loop and current inner loop. The outer loop adopts improved FLADRC feedforward linear active disturbance rejection control, and the inner loop adopts LADRC linear active disturbance rejection control.

[0049] The specific method of LADRC linear active disturbance rejection is as follows: the improved ADRC adds a feedforward controller to the ADRC part to form FLADRC feedforward linear active disturbance rejection control. The feedforward controller introduces a positive feedback channel at the input signal position of the tracking differentiator, calculates the difference between the sampled voltage signal and the given voltage signal, and cancels the disturbance signal through the feedforward coefficient to achieve zero steady-state error tracking and disturbance compensation, while reducing the overshoot and settling time of the hybrid energy storage control system.

[0050] The two-layer dual closed-loop control structure includes a battery dual-loop structure formed by external voltage loop control and battery current loop control, and a supercapacitor dual-loop structure formed by external voltage loop control and supercapacitor current loop control.

[0051] In the voltage loop control, feedforward active disturbance rejection control is adopted, and low-pass filtering is combined to convert the current component into a high-frequency component of the supercapacitor output reference current signal and a low-frequency component of the battery output reference current signal. Linear active disturbance rejection control is introduced in the battery current loop control and the supercapacitor current loop control respectively. The inductor current of the bidirectional DC-DC converter of the battery and the supercapacitor is controlled by two double closed-loop structures respectively, thereby controlling the charging and discharging current of the hybrid energy storage system, which is used to improve the dynamic response speed and anti-interference capability of the hybrid energy storage system.

[0052] The battery current loop adopts an improved linear active disturbance rejection controller. Compared with the traditional active disturbance rejection controller, the tracking differentiator is eliminated. Since the battery current loop needs to quickly track command changes, the battery current loop control mainly consists of two parts: a linear extended state observer and a proportional-derivative controller.

[0053] The voltage loop control section, combined with the ADRC with added feedforward controller, forms a FLADRC control loop. The battery section also uses ADRC to realize the battery current loop control, and the supercapacitor section also uses ADRC to realize the battery current loop control. Overall, two double closed-loop structures are formed to realize comprehensive control of the energy storage system.

[0054] The working method of the photovoltaic microgrid power generation unit is as follows:

[0055] S1-1. When a bird lands on a photovoltaic cell, the light sensor obtains the outline of the covered area through sensing imaging, and obtains the area m of the thermal image of the covered area. The outline analysis module calculates the size of the bird.

[0056] S1-2, The calculated area is transmitted to the current boosting module of the photovoltaic cell, and the current regulating module in other normal operating areas supplies boosting current I to the current boosting module on the photovoltaic cell in the bird-staying area. k Among them, the current I increases k I is directly proportional to the area m of the thermal image of the covered region. k The thermal imaging area m needs to satisfy the formula Where M is the current parameter, which is selected according to actual needs, and I0 is the normal output current of the photovoltaic cell;

[0057] S1-3, After the focusing drive module receives the increased current, it operates in a high-power state;

[0058] The boost current from the boost module is supplied to the focusing drive module. The system is set to a high-power operating range. Within this range, the focusing drive module operates at high power through the boost current. The operating current I of the focusing drive module satisfies the formula:

[0059]

[0060] Where d is the distance between the illumination module and the bird imaging projection, μ is the current stabilization parameter, n is the total number of focusing drive modules, and i is the number of focusing drive modules in the high-power operating range.

[0061] Outside this range, the focusing drive module outputs current at low power based on the output current of the current regulation module, and its operating current is I = I0 - I k .

[0062] To address the shortcomings of existing technologies, a photovoltaic microgrid hybrid energy storage system based on improved active disturbance rejection control is proposed. The control method has good performance, strong robustness, and strong anti-interference ability, enabling the hybrid energy storage device to better balance power fluctuations.

[0063] By performing power self-division frequency allocation on different energy storage devices in a hybrid energy storage system, the stability of power on the grid-connected side can be improved, enabling rapid power response of energy storage devices in photovoltaic microgrid systems and providing good suppression of disturbances.

[0064] The solar panels can be used to scare away birds that are perched on them by concentrating sunlight. The intensity of the sunlight can be adjusted according to the size of the birds, thus preventing them from staying on the panels and improving their efficiency.

[0065] It should be noted that, in this document, relational terms such as "first" and "second" are used only to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Furthermore, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such process, method, article, or apparatus.

[0066] Finally, it should be noted that the above descriptions are merely preferred embodiments of the present invention and are not intended to limit the present invention. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art can still modify the technical solutions described in the foregoing embodiments or make equivalent substitutions for some of the technical features. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A photovoltaic microgrid energy storage system based on improved active disturbance rejection control, characterized in that: The photovoltaic micro-grid power generation unit, the super capacitor energy storage unit, the battery energy storage unit, the DC load unit, the bidirectional DC-DC bidirectional converter and the DC bus are connected to form a hybrid energy storage system. The photovoltaic micro-grid power generation unit, the super capacitor energy storage unit, the battery energy storage unit and the DC load unit are connected to the DC bus through a common access point PCC. The bidirectional DC-DC bidirectional converter comprises an energy storage device, an inductor coil, two bridge arms and a support capacitor. The working method of the system comprises a transition process configuration part in a linearized simplified tracking differentiator TD, a linearized extended state observer ESO, and a connection of the extended state observer ESO parameters and the bandwidth of the observer. A PD controller combination is adopted to connect Kp and Kd with the controller bandwidth to simplify the setting of the controller. The tracking differentiator TD is used for differential signal acquisition and transition process, and the linearized extended state observer ESO is used for observing total disturbance. The working method of the system adopts hybrid energy storage control.

2. The photovoltaic microgrid energy storage system based on improved active disturbance rejection control according to claim 1, characterized in that: The specific mode of the LADRC linear active disturbance rejection is as follows: an improved ADRC, an FLADRC feedforward linear active disturbance rejection control is formed by adding a feedforward controller in the ADRC part. The photovoltaic micro-grid energy storage system adopts a two-layer double closed-loop control structure. The two-layer double closed-loop control structure comprises a battery double-loop structure formed by an outer voltage loop control and a battery current loop control, and a super capacitor double-loop structure formed by an outer voltage loop control and a super capacitor current loop control. In the voltage loop control, feedforward active disturbance rejection control is adopted, and the current component is converted into the super capacitor output reference current signal of high frequency component and the battery output reference current signal of low frequency component by combining low pass filtering, linear active disturbance rejection control is introduced in the battery current loop control and the super capacitor current loop control respectively, the inductor current of the bidirectional DC-DC converter of the battery and the super capacitor is controlled through two double closed loop structures respectively, and then the charging and discharging current of the hybrid energy storage system is controlled, so as to improve the dynamic response speed and anti-interference ability of the hybrid energy storage system.

3. The photovoltaic microgrid energy storage system based on improved active disturbance rejection control according to claim 2, characterized in that: Compared with the traditional active disturbance rejection controller, the improved linear active disturbance rejection controller cancels the tracking differentiator link, and the battery current loop needs to track the instruction change quickly, and the battery current loop comprises a linear extended state observer and a proportional differential controller. The voltage loop control part combines the ADRC with the added feedforward controller to form the FLADRC control loop, the battery part adopts the ADRC to realize the battery current loop control, the super capacitor part also adopts the ADRC to realize the battery current loop control, and two double closed loop structures are formed as a whole to realize the comprehensive control of the energy storage system.

4. The photovoltaic microgrid energy storage system based on improved active disturbance rejection control according to claim 3, characterized in that: The working method of the photovoltaic micro-grid power generation unit is: S1-1, when the bird stays on the photovoltaic cell, the light sensor obtains the profile of the area covered by the bird through the sensing imaging, and obtains the area of the thermal imaging of the covered area , the profile analysis module calculates the size of the bird; S1-2, the calculated area is transmitted to the current raising module of the photovoltaic cell, and the current raising module of the photovoltaic cell in the bird staying area is supplied with raised current by the current adjusting module of other normal working area , wherein the raised current is proportional to the area of the thermal imaging of the covered area , is proportional to the area of the thermal imaging , and the formula needs to be met, wherein M is a current parameter, which is selected according to actual needs, is the output current of the normal photovoltaic cell S1-3, the light concentration driving module works in a high-power working state after obtaining the elevated current.

5. The photovoltaic microgrid energy storage system based on improved active disturbance rejection control according to claim 4, characterized in that: The elevated current in the elevated module is delivered to the light concentration driving module, the system sets a high-power working range, the light concentration driving module in the range works in a high-power working state through the elevated current, and the working current I of the light concentration driving module satisfies the formula: wherein is the distance between the illumination module and the bird imaging projection, is the steady flow parameter, n is the total number of light-concentrating driving modules, and i is the number of light-concentrating driving modules in the high-power working range. The light condensing and expelling module outside the range outputs current according to the current adjusting module to output current in a low power state, and its working current .

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