Self-adaptive compensation photovoltaic integrated unified power quality regulator and control method thereof

Abstract

The invention relates to the technical field of electric energy quality optimization, in particular to a self-adaptive compensation photovoltaic integrated unified electric energy quality regulator and a control method thereof, and the self-adaptive compensation photovoltaic integrated unified electric energy quality regulator comprises a series compensator, a parallel compensator, a direct current bus, a photovoltaic module and a controller; the photovoltaic module is connected to the direct current bus through a reverse blocking diode, and is provided with a maximum power point tracking module for providing active power support for the system; the series compensator and the parallel compensator are connected to a direct current bus in a back-to-back manner; the series compensator is connected to a power grid side in series through the three-phase series injection transformer. A self-adaptive weight updating mechanism of the ALFMS algorithm is utilized, fundamental wave active and reactive components are directly extracted from distorted voltage and current signals, a low-pass filter is completely abandoned, phase delay caused by the filter is eliminated, a controller can make instantaneous response to sudden rising and sudden dropping of the voltage of a power grid or load fluctuation, and therefore the power grid voltage can be effectively controlled. And the dynamic tracking performance of the system is greatly improved.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of power quality optimization, in particular to a photovoltaic integrated unified power quality conditioner with adaptive compensation and a control method thereof. BACKGROUND

[0002] With the rapid development of power electronics technology, the penetration rate of nonlinear loads in distribution networks is increasing, leading to increasingly serious power quality problems. On the one hand, the harmonic current and reactive power demand generated by nonlinear loads pollute the power grid; on the other hand, the sudden rise, sudden drop and voltage distortion of the grid side voltage seriously affect the normal operation of sensitive loads. In order to solve these problems, the unified power quality conditioner emerges as the times require. The unified power quality conditioner can simultaneously solve voltage and current related power quality problems through integrated series compensator and parallel compensator. In addition, with the popularity of renewable energy, integrating photovoltaic power generation system into the unified power quality conditioner not only can utilize clean energy to power the load, but also can provide continuous active power support for the DC bus of the unified power quality conditioner, thereby maintaining system operation in long-term voltage interruption or deep drop, which has become an important development trend of microgrid and modern distribution network.

[0003] However, the performance of the photovoltaic power integrated unified power quality conditioner system is highly dependent on the accuracy and response speed of its control strategy. Existing traditional control methods, such as control strategies based on synchronous reference frame theory or instantaneous reactive power theory, are mature in theory, but have significant limitations in practical application.

[0004] Firstly, these methods usually rely heavily on the performance of the phase-locked loop, and when extracting the fundamental component, a low-pass filter or moving average filter must be used to filter out harmonic interference, increasing the computational complexity of the system, while also causing amplitude attenuation and phase delay, leading to poor tracking performance of the controller under dynamic conditions such as load mutation or rapid fluctuations in grid voltage, making it difficult to achieve real-time accurate compensation. Secondly, for adaptive control schemes based on conventional least mean square algorithm, although the weights are iteratively optimized, a fixed step size is usually used, making it difficult to balance between convergence speed and steady-state error: a large step size leads to steady-state oscillation, and a small step size results in slow dynamic response. Finally, when operating under high distortion power supply voltage, the stability and performance of the system may be affected; under different load and photovoltaic power generation conditions, power balance and power quality optimization of the system are difficult to achieve. SUMMARY

[0005] In view of the problems of slow dynamic response caused by filter dependence, difficulty in balancing convergence and stability of traditional algorithm, and insufficient robustness in photovoltaic power fluctuation and high-distortion power grid environment in the prior art, the present application provides the following technical solution: a photovoltaic integrated unified power quality conditioner with adaptive compensation, comprising: a series compensator, a parallel compensator, a DC bus, a photovoltaic assembly, and a controller; The photovoltaic assembly is connected to the DC bus through a reverse blocking diode and is configured with a maximum power point tracking module for providing active power support for the system; The series compensator and the parallel compensator are connected to the DC bus in a back-to-back form; The series compensator is connected to the power grid side in series through a three-phase series injection transformer for injecting compensation voltage to the power grid to regulate sudden rise, sudden drop, and harmonics of the grid voltage; The parallel compensator is connected to the load side in parallel through an interface inductor for compensating load current harmonics, reactive power, and maintaining stability of the DC bus voltage; The controller is connected to the series compensator, the parallel compensator, the photovoltaic assembly, and system sensor signals, and the controller is configured to run an adaptive leakage factor least mean square (ALFMS) algorithm, and generate control reference signals for the series compensator and the parallel compensator by extracting fundamental components from the collected voltage and current signals.

[0006] Preferably, the capacity setting of the series compensator is based on the following logic: The capacity setting value of the series compensator is its apparent power rating, which is determined by the product of the effective voltage injected by the series voltage source compensator in each phase, the current rating in each phase, and the number of phases; wherein the calculation of the current rating in each phase includes the sum of the power of the photovoltaic at the maximum power point and the minimum load demand, and is inversely proportional to the system rated voltage considering the voltage sag depth.

[0007] Preferably, the capacity setting of the parallel compensator is based on the following logic: The capacity setting value of the parallel compensator is its power rating, which is determined by the square root of the sum of the square of the power of the photovoltaic at the maximum power point, the square of the maximum reactive power of the load, and the square of the maximum load corresponding harmonic power.

[0008] Preferably, the control reference signals generated by the controller include a reference source current signal for driving the parallel compensator and a reference injection voltage signal for driving the series compensator.

[0009] Preferably, the series compensator and the parallel compensator are both equipped with a hysteresis current controller for receiving the control reference signals and comparing them with actual measurement values to generate pulse signals for driving switching devices.

[0010] Preferably, the maximum power point tracking module adopts a perturb and observe algorithm, adjusts the working point voltage by periodically perturbing the output voltage of the photovoltaic module and observing the change direction of the output power, to ensure that the photovoltaic module always outputs the maximum power under the current illumination condition.

[0011] The application further provides a photovoltaic integrated unified power quality conditioner with adaptive compensation, which is applied to the photovoltaic integrated unified power quality conditioner mentioned above and comprises the following steps of: The three-phase instantaneous voltages, three-phase load currents, three-phase grid currents, DC bus voltage, real-time output power of the photovoltaic module and three-phase actual injection voltages of the series compensator at the point of common coupling are collected in real time through sensors; the voltage amplitudes are calculated based on the three-phase instantaneous voltages, and the in-phase unit template and the quadrature unit template of the source voltage are calculated based on the voltage amplitudes; The in-phase unit template is taken as an input vector, and the three-phase load currents are taken as expected responses, which are input into the ALFMS algorithm model to perform iterative operation, so that the basic active component amplitudes of the three-phase load currents are obtained; the DC bus voltage is compared with the reference voltage to obtain an active power loss component for maintaining the stability of the DC bus voltage; Based on the average value of the basic active component amplitudes, the active power loss component and the real-time output power of the photovoltaic module, the active component of the reference source current is constructed in combination with the in-phase unit template; the reactive component of the reference source current is set to zero or is set according to the demand of the grid, and the total reference source current is obtained through superposition; The in-phase unit template and the quadrature unit template are taken as input vectors, and the three-phase instantaneous voltages are taken as expected responses, which are input into the ALFMS algorithm model to perform iterative operation, so that the basic in-phase component amplitudes and the basic quadrature component amplitudes of the three-phase instantaneous voltages are obtained; Based on the basic in-phase component amplitudes and the quadrature component amplitudes, the total amplitude of the basic components of the reference load voltage is calculated; the ideal reference load voltage is constructed, and the difference between the reference load voltage and the three-phase instantaneous voltages is calculated to obtain the reference injection voltage; The total reference source current is compared with the three-phase grid currents, and the reference injection voltage is compared with the three-phase actual injection voltages, so that the control signals of the shunt compensator and the series compensator are generated through the hysteresis current controller.

[0012] Preferably, the ALFMS algorithm model sets a step factor to update the weight during the iterative operation process; the step factor is nonlinearly adjusted through a Sigmoid function, so as to provide a large step to speed up the convergence when the error is large, and to provide a small step to reduce the steady-state oscillation when the error is small.

[0013] Preferably, the ALFMS algorithm model sets a leakage factor to update the weight in the iterative operation process; the leakage factor is adaptively adjusted based on the energy of the error signal; when the system changes dynamically to cause the error energy to increase, the leakage factor is adjusted to track the system change; when the system is in a steady state, the leakage factor is adjusted to prevent the weight from drifting.

[0014] Preferably, in the step of constructing the active component of the reference source current, the following power balance-based operation mode management is included: When the real-time output power of the photovoltaic assembly is zero, it is determined as a night mode, the parallel compensator is controlled to absorb the active power required for maintaining the DC bus voltage from the power grid, at this time, the active component amplitude of the reference source current is equal to the sum of the average value of the basic active component amplitude and the active power loss component; When the real-time output power of the photovoltaic assembly is greater than zero and less than the sum of the active power consumed by the three-phase load current and the system loss, it is determined as a photovoltaic auxiliary mode, at this time, the active component amplitude of the reference source current is the sum of the average value of the basic active component amplitude and the active power loss component minus the real-time output power of the photovoltaic assembly, and the insufficient power is supplemented by the power grid; When the real-time output power of the photovoltaic assembly is greater than the sum of the active power consumed by the three-phase load current and the system loss, it is determined as a photovoltaic grid feeding mode, at this time, the active component amplitude of the reference source current takes a negative value, and the parallel compensator is controlled to adjust the current phase to reversely inject the excess active power into the power grid.

[0015] Compared with the prior art, the application has the following beneficial effects: The application directly extracts the fundamental active and reactive components from the distorted voltage and current signals by using the adaptive weight updating mechanism of the ALFMS algorithm, completely discards the low-pass filter, eliminates the phase delay caused by the filter, enables the controller to respond instantaneously to the sudden rise or drop of the grid voltage or load fluctuation, and greatly improves the dynamic tracking performance of the system. The application adopts the Sigmoid function variable step length and the adaptive leakage factor based on the error signal energy, the leakage factor and the step length are automatically increased when the system is subjected to severe disturbance, the algorithm can quickly track the new state, the leakage factor and the step length are automatically reduced when the system tends to be stable, so as to reduce the steady-state error, and this mechanism ensures that the system can still maintain high control precision and stability under adverse working conditions such as high distortion of the grid voltage or severe fluctuation of the photovoltaic power. The photovoltaic power generation system is deeply integrated, power flow management logic is designed, active power can be flexibly distributed according to illumination conditions and load demand, the system can not only manage power quality, but also can provide continuous energy support through a DC bus to maintain the operation of critical loads and improve the reliability and economy of power supply when the grid voltage deeply drops or even interrupts when the illumination is sufficient, and the excess energy can be sent back to the power grid; The application realizes decoupling control of the series and parallel compensators by calculating the in-phase unit template and the orthogonal unit template of the source voltage respectively, extracting the fundamental components of the load current and the source voltage by using the ALFMS algorithm, the parallel compensator not only compensates the harmonics and reactive power on the load side, but also maintains the DC bus voltage, and the series compensator effectively isolates the voltage surge, sudden drop and harmonic interference on the grid side, and the two work together to ensure the pure sinusoidal characteristics of the load end voltage and the unity power factor operation of the grid side current, and completely solve the comprehensive power quality problem in the distribution network. BRIEF DESCRIPTION OF DRAWINGS

[0016] Figure 1 It is a system structure schematic diagram of the overall system in an embodiment of the application. Figure 2 It is a step flow schematic diagram of the overall method in an embodiment of the application. DETAILED DESCRIPTION

[0017] The technical solutions in the embodiments of the application will be clearly and completely described below with reference to the drawings in the embodiments of the application. Obviously, the described embodiments are only part of the embodiments of the application, rather than all the embodiments of the application. Based on the embodiments in the application, all other embodiments obtained by those skilled in the art without creative labor fall within the protection scope of the application.

[0018] Embodiment one, please refer to Figure 1 The application provides a technical solution: a self-adaptive compensation photovoltaic integrated unified power quality conditioner, comprising: a series compensator, a parallel compensator, a DC bus, a photovoltaic module and a controller. The photovoltaic module is connected to the DC bus through a reverse blocking diode and is configured with a maximum power point tracking module for providing active power support for the system. The series compensator and the parallel compensator are connected to the DC bus in a back-to-back form. The series compensator is connected to the grid side in series through a three-phase series injection transformer, and is used for injecting compensation voltage to the grid to adjust the voltage surge, sudden drop and harmonic of the grid. The parallel compensator is connected to the load side in parallel through an interface inductor, and is used for compensating the load current harmonic, reactive power and maintaining the stability of the DC bus voltage. The controller is connected with the series compensator, the parallel compensator, the photovoltaic module and a system sensor signal, and the controller is configured to run an adaptive leakage factor least mean square (ALFMS) algorithm, and generate control reference signals for the series compensator and the parallel compensator respectively by extracting fundamental components from the collected voltage and current signals.

[0019] It should be noted that the specific role of the reverse blocking diode is to prevent the power grid or the DC bus from pouring current into the photovoltaic module in the case of abnormal voltage fluctuation, thereby protecting the photovoltaic cell panel; the back-to-back connection structure enables the series compensator and the parallel compensator to exchange active power through the common DC bus, which not only realizes the traditional unified power quality conditioner function, but more importantly, in the case of deep voltage sag or even short-time interruption of the power grid, the power generated by the photovoltaic module can be directly supplied to the load or support the series compensator to inject voltage through the DC bus, thereby improving the survival ability of the system and the load power supply reliability in extreme power grid operating conditions.

[0020] In an optional embodiment, the capacity setting of the series compensator is based on the following logic: The capacity setting value of the series compensator is its apparent power rating, which is determined by the product of the effective voltage injected by the series voltage source compensator per phase, the per-phase current rating and the number of phases; wherein the calculation of the per-phase current rating is based on the sum of the power of the photovoltaic at the maximum power point and the minimum load demand, and is inversely proportional to the system rated voltage considering the voltage sag depth.

[0021] Specifically, the apparent power rating of the series compensator The specific calculation formula is as follows: ; Wherein, is the effective voltage injected per phase, is the per-phase rated current of the series compensator; The design of the apparent power rating of the series compensator must consider the power maintenance requirement when the grid voltage sags, and its value is determined according to the following logic: ; Wherein, is the maximum power of the photovoltaic, is the minimum load demand, is the system rated voltage, is the preset maximum voltage sag depth, for example, 0.4 represents a sag of 40%, and the formula shows that in the case of deeper voltage sag, the larger the compensation current required by the system to maintain power balance, thereby determining the capacity selection of the series compensator.

[0022] It should be noted that this capacity design logic fully considers the worst case, that is, when the grid voltage drops to the maximum extent, the system must extract more current from the grid in order to maintain the power constant at the load end, so the design of the rated current must be inversely proportional to the remaining voltage after voltage drop; At the same time, the maximum power of photovoltaic is taken into account to ensure that when the photovoltaic is full and the grid voltage drops, the series compensator still has enough capacity margin to handle the total power flow through the transformer, preventing the inverter from being overloaded and damaged.

[0023] In an alternative embodiment, the capacity of the parallel compensator is set according to the following logic: The capacity of the parallel compensator is its power rating, which is determined by the square root of the sum of the squares of the maximum power of the photovoltaic at the maximum power point, the maximum reactive power of the load, and the square of the corresponding harmonic power of the maximum load.

[0024] Specifically, the capacity of the parallel compensator is calculated according to the principle of vector synthesis, and the specific formula is: ; Among them, represents the maximum output power of the photovoltaic module under standard test conditions, which needs to be transmitted through the parallel inverter in the grid-connected mode; represents the maximum reactive power demand that the load may have; represents the corresponding harmonic apparent power under the maximum load condition, which ensures that the rated capacity of the parallel inverter is sufficient to cover the extreme condition when the three reach the peak value.

[0025] It should be noted that this calculation formula follows the principle of vector synthesis of apparent power, because the parallel compensator needs to perform multiple tasks when it is running: transmitting active power generated by photovoltaic, compensating reactive power of load, and canceling harmonic components. The three are orthogonal or non-co-phase in the phasor domain, so they cannot be simply added algebraically. This design ensures that the rated capacity of the parallel inverter is sufficient to cover the extreme case when the photovoltaic is full and the load reactive and harmonic demand reaches the peak value, ensuring the simultaneous performance of high-efficiency photovoltaic energy feeding and power quality management.

[0026] In an alternative embodiment, the control reference signal generated by the controller includes a reference source current signal for driving the parallel compensator and a reference injection voltage signal for driving the series compensator; The series compensator and the parallel compensator are both equipped with a hysteresis current controller, which is used to receive the control reference signal and compare it with the actual measurement value, and then generate a pulse signal to drive the switching device.

[0027] It should be noted that the hysteresis current controller is used instead of the traditional PWM controller because the hysteresis current controller has very fast dynamic response speed and intrinsic current limiting capability, and it directly generates the pulse for driving the IGBT by limiting the actual collected signal within the hysteresis width around the reference signal, without complex carrier modulation, which is crucial for the application to deal with transient disturbances such as voltage surges and drops, and can ensure that the compensator acts within microseconds to achieve immediate tracking and correction of distorted waveforms.

[0028] Specifically, the control logic of the hysteresis current controller limits the actual signal within the hysteresis width of the reference signal , and the generation logic of the switching signal is as follows: ; When the actual value falls outside the lower limit of the hysteresis width from the reference value , the controller sends an on signal; when the actual value rises above the upper limit of the hysteresis width from the reference value , the controller sends an off signal; when the actual value is between and , the switching state remains the last signal until the next boundary is triggered.

[0029] In an alternative embodiment, the maximum power point tracking module uses the perturb and observe algorithm to adjust the operating voltage by periodically perturbing the output voltage of the photovoltaic assembly and observing the change direction of the output power, to ensure that the photovoltaic assembly always outputs the maximum power under the current lighting conditions.

[0030] It should be noted that the perturb and observe method applies a small perturbation increase or decrease to the operating voltage of the photovoltaic array and detects the change in output power; if the power increases, continue the same direction perturbation, otherwise reverse the perturbation. This algorithm structure is simple, low in implementation cost and robust, and can ensure that the photovoltaic assembly always operates at the peak point of the P-V curve in an environment where the lighting intensity and temperature are constantly changing, thereby maximizing the energy output efficiency of the system.

[0031] Specifically, the core logic of the perturb and observe method is to judge the sign of the derivative of power to voltage , if , it means that the maximum power point is on the right, and the maximum power point tracking module increases the operating voltage reference value ; if ​, indicating that the maximum power point is on the left, and the maximum power point tracking module reduces the operating voltage reference value ; the system will eventually operate at oscillation, thereby locking the maximum power point.

[0032] Example two, please refer to Figure 2 , the application provides a technical scheme: a kind of adaptive compensation photovoltaic integrated unified power quality conditioner control method, it is suitable for the above photovoltaic integrated unified power quality conditioner, comprising: S1, by real-time acquisition of three-phase instantaneous voltage of public coupling point, three-phase load current, three-phase grid current, DC bus voltage, real-time output power of photovoltaic module and three-phase actual injection voltage of series compensator;Voltage amplitude is calculated based on three-phase instantaneous voltage, and in-phase unit template and quadrature unit template of source voltage are calculated based on voltage amplitude; S2, the in-phase unit template is used as input vector, and three-phase load current is used as expected response, and is input into ALFMS algorithm model to carry out iterative operation, to obtain the basic active component amplitude of three-phase load current;DC bus voltage is compared with reference voltage, and active power loss component for maintaining DC bus voltage stability is obtained; S3, based on the average value of basic active component amplitude, active power loss component and real-time output power of photovoltaic module, the active component of reference source current is constructed with in-phase unit template;The reactive component of reference source current is set to zero or set according to grid demand, and the total reference source current is obtained by superposition; S4, the in-phase unit template and quadrature unit template are used as input vector, and three-phase instantaneous voltage is used as expected response, and is input into ALFMS algorithm model to carry out iterative operation, to obtain the basic in-phase component amplitude and basic quadrature component amplitude of three-phase instantaneous voltage; S5, based on basic in-phase component amplitude and quadrature component amplitude, the total amplitude of basic component of reference load voltage is calculated;Ideal reference load voltage is constructed, and the difference between the reference load voltage and three-phase instantaneous voltage is calculated to obtain the reference injection voltage; S6, total reference source current is compared with three-phase grid current, and reference injection voltage is compared with three-phase actual injection voltage, and control signal of shunt compensator and series compensator is generated by hysteresis current controller.

[0033] It should be noted that the core advantage of the control method is that the low-pass filter used to extract the fundamental component in the traditional method is completely abandoned, and by respectively processing the current signal with the load current as the expected response and the voltage signal with the grid voltage as the expected response using the ALFMS algorithm, the fundamental amplitude can be directly separated from the distorted signal containing high-order harmonics and noise, the phase delay and amplitude attenuation caused by the filter are eliminated, and the system can realize zero-delay signal detection when the load suddenly changes or the grid fails, thereby greatly improving the overall dynamic tracking performance and compensation accuracy.

[0034] Specifically, the generation of the unit template in the control method is the basis of the algorithm, and based on the collected three-phase instantaneous voltage , the voltage amplitude is first calculated ;

[0035] ; ; Using these pure unit templates as inputs of the ALFMS algorithm, the fundamental amplitude can be accurately extracted from the distorted load current or grid voltage, and the low-pass filter which causes phase delay is completely abandoned.

[0036] In an optional embodiment, the ALFMS algorithm model sets a step factor to update the weight during the iteration operation process; the step factor is nonlinearly adjusted by a Sigmoid function to provide a large step to speed up convergence when the error is large, and to provide a small step to reduce steady-state oscillation when the error is small; the ALFMS algorithm model sets a leakage factor to update the weight during the iteration operation process; the leakage factor is adaptively adjusted based on the energy of the error signal, when the system changes dynamically to increase the error energy, the leakage factor is adjusted to track the system changes; when the system is in a steady state, the leakage factor is adjusted to prevent weight drift.

[0037] It should be noted that the traditional LMS algorithm often has a contradiction between convergence speed and steady-state error, that is, the larger the step, the faster the convergence but the larger the oscillation, and the weight drift is easy to occur, the Sigmoid variable step function introduced in the present scheme can automatically increase the step when the error is large to quickly capture dynamic changes, and reduce the step when the error is small to achieve high-precision steady-state tracking; at the same time, the adaptive leakage factor based on error energy adjustment can enhance the robustness of the algorithm when the system parameters change, such as photovoltaic power fluctuation, prevent weight parameter divergence when signal is missing or continuous excitation is insufficient, thereby ensuring the long-term operation stability of the controller.

[0038] Specifically, the weight update formula of the ALFMS algorithm is as follows: ; Wherein, is an input template, is an error signal, the core innovation of the present application is to introduce a Sigmoid function variable step size : ; The formula makes the step size change nonlinearly with the error modulus value, and when the error is large, the step size increases rapidly to speed up the convergence, and when the error is small, the step size tends to a minimum value to suppress oscillation; At the same time, the adaptive leakage factor Based on the error energy Adjustment: ; ; This mechanism ensures that when the system is dynamically changing, that is The leakage factor increases, and the robustness and suppression ability of the algorithm to parameter drift are enhanced.

[0039] In an optional embodiment, in the step of constructing the active component of the reference source current, the following power balance-based operation mode management is included: When the real-time output power of the photovoltaic assembly is zero, it is determined to be night mode, and the parallel compensator is controlled to absorb the active power required to maintain the DC bus voltage from the power grid, at this time The amplitude of the active component of the reference source current is equal to the sum of the average value of the basic active component amplitude and the active power loss component; When the real-time output power of the photovoltaic assembly is greater than zero and less than the sum of the active power consumed by the three-phase load current and the system loss, it is determined to be a photovoltaic auxiliary mode, at this time The amplitude of the active component of the reference source current is the average value of the basic active component amplitude and the active power loss component minus the real-time output power of the photovoltaic assembly, and the insufficient power is supplemented by the power grid; When the real-time output power of the photovoltaic assembly is greater than the sum of the active power consumed by the three-phase load current and the system loss, it is determined to be a photovoltaic grid-connected mode, at this time The amplitude of the active component of the reference source current is negative, and the parallel compensator is controlled to adjust the current phase to inject the excess active power into the power grid in the opposite direction.

[0040] It should be noted that the calculation logic of the reference source current amplitude Directly reflects the automatic switching of the above three modes, and the specific mathematical expression is: ; Wherein, is the average value of the load active current, is the loss current required to maintain the DC bus, equivalent active current provided for the photovoltaic; i.e. in night mode, at this time positive, grid powered; in photovoltaic assisted mode, reduced but still positive, grid less powered; in photovoltaic grid fed mode, becomes negative.

[0041] The embodiments of the present application are described in detail above with reference to the accompanying drawings, but the present application is not limited thereto, and various changes can be made within the knowledge of those skilled in the art without departing from the spirit of the present application.

Claims

1. An adaptive compensation photovoltaic integrated unified power quality conditioner, characterized in that, include: Series compensators, parallel compensators, DC buses, photovoltaic modules and controllers; The photovoltaic modules are connected to the DC bus via reverse blocking diodes and are equipped with a maximum power point tracking module to provide active power support for the system. Series compensators and parallel compensators are connected to the DC bus in a back-to-back configuration. The series compensator is connected to the grid side through a three-phase series injection transformer to inject compensation voltage into the grid to regulate the sudden rise, fall and harmonics of the grid voltage. Parallel compensators are connected to the load side in parallel via interface inductors to compensate for load current harmonics, reactive power, and maintain DC bus voltage stability. The controller is connected to the series compensator, parallel compensator, photovoltaic module and system sensor signals. The controller is configured to run the Adaptive Leakage Factor Minimum Mean Square (ALFMS) algorithm, which extracts the fundamental component from the acquired voltage and current signals to generate control reference signals for the series compensator and parallel compensator respectively.

2. The adaptive compensation photovoltaic integrated unified power quality conditioner according to claim 1, characterized in that, The capacity setting of the series compensator is based on the following logic: The capacity setting of the series compensator is its apparent power rating, which is determined by the product of the effective voltage of each phase injected by the series voltage source compensator, the rated current of each phase, and the number of phases. The rated current of each phase is calculated based on the sum of the photovoltaic power at the maximum power point and the minimum load requirement, and is inversely proportional to the rated voltage of the system after taking into account the voltage sag.

3. The adaptive compensation photovoltaic integrated unified power quality conditioner according to claim 1, characterized in that, The capacity setting of the parallel compensator is based on the following logic: The capacity setting of the parallel compensator is its power rating, which is determined by the square root of the sum of the square of the photovoltaic power at the maximum power point, the square of the maximum reactive power of the load, and the square of the harmonic power corresponding to the maximum load.

4. The adaptive compensation photovoltaic integrated unified power quality conditioner according to claim 1, characterized in that, The control reference signals generated by the controller include a reference source current signal for driving the parallel compensator and a reference injection voltage signal for driving the series compensator.

5. The adaptive compensation photovoltaic integrated unified power quality conditioner according to claim 1, characterized in that, Both the series compensator and the parallel compensator are equipped with a hysteresis current controller. The hysteresis current controller is used to receive the control reference signal and compare it with the actual measured value, thereby generating a pulse signal to drive the switching device.

6. The adaptive compensation photovoltaic integrated unified power quality conditioner according to claim 1, characterized in that, The maximum power point tracking module uses a perturbation-observation algorithm to adjust the operating point voltage by periodically perturbing the output voltage of the photovoltaic module and observing the direction of change in output power, so as to ensure that the photovoltaic module always outputs the maximum power under the current illumination conditions.

7. A control method for an adaptive compensation photovoltaic integrated unified power quality regulator, applied to the photovoltaic integrated unified power quality regulator according to any one of claims 1-6, characterized in that, include: The system collects real-time data on the three-phase instantaneous voltage at the common coupling point, the three-phase load current, the three-phase grid current, the DC bus voltage, the real-time output power of the photovoltaic modules, and the actual three-phase injection voltage of the series compensator. Based on the three-phase instantaneous voltage, the voltage amplitude is calculated, and based on the voltage amplitude, the in-phase unit template and the orthogonal unit template of the source voltage are derived. Using the in-phase unit template as the input vector and the three-phase load current as the desired response, the input is fed into the ALFMS algorithm model for iterative calculation to obtain the basic active component amplitude of the three-phase load current; the DC bus voltage is compared with the reference voltage to obtain the active power loss component used to maintain the stability of the DC bus voltage. Based on the average value of the basic active component amplitude, the active power loss component, and the real-time output power of the photovoltaic module, the active component of the reference source current is constructed by combining the in-phase unit template; the reactive component of the reference source current is set to zero or set according to the grid demand, and the total reference source current is obtained by superimposing them. Using the in-phase unit template and the orthogonal unit template as input vectors, and the three-phase instantaneous voltage as the desired response, the input is fed into the ALFMS algorithm model for iterative calculation to obtain the basic in-phase component amplitude and the basic orthogonal component amplitude of the three-phase instantaneous voltage. Calculate the total amplitude of the basic components of the reference load voltage based on the amplitudes of the basic in-phase components and the quadrature components; Construct an ideal reference load voltage and calculate the difference between this reference load voltage and the three-phase instantaneous voltage to obtain the reference injection voltage; The total reference source current is compared with the three-phase grid current, and the reference injection voltage is compared with the actual three-phase injection voltage. The control signals for the parallel compensator and the series compensator are generated by the hysteresis current controller.

8. The adaptive compensation photovoltaic integrated unified power quality regulator control method according to claim 7, characterized in that, The ALFMS algorithm model sets a step size factor to update the weights during the iterative operation. The step size factor is nonlinearly adjusted through the Sigmoid function to provide a large step size to accelerate convergence when the error is large, and a small step size to reduce steady-state oscillations when the error is small.

9. The adaptive compensation photovoltaic integrated unified power quality regulator control method according to claim 8, characterized in that, The ALFMS algorithm model sets a leakage factor to update the weights during iterative computation. The leakage factor is adaptively adjusted based on the energy of the error signal. When the system undergoes dynamic changes that cause the error energy to increase, the leakage factor is adjusted to track the system changes. When the system is in a steady state, the leakage factor is adjusted to prevent weight drift.

10. The adaptive compensation photovoltaic integrated unified power quality regulator control method according to claim 7, characterized in that, The steps for constructing the active component of the reference source current include the following power balance-based operating mode management: When the real-time output power of the photovoltaic module is zero, it is determined to be night mode. The parallel compensator is controlled to absorb the active power required to maintain the DC bus voltage from the grid. At this time, the active component amplitude of the reference source current is equal to the sum of the average value of the basic active component amplitude and the active power loss component. When the real-time output power of the photovoltaic module is greater than zero and less than the sum of the active power consumed by the three-phase load current and the system loss, it is determined to be in photovoltaic auxiliary mode. At this time, the active component amplitude of the reference source current is the sum of the average value of the basic active component amplitude and the active power loss component minus the real-time output power of the photovoltaic module. The insufficient power is supplemented by the grid. When the real-time output power of the photovoltaic module is greater than the sum of the active power consumed by the three-phase load current and the system loss, it is determined to be a photovoltaic grid-feed mode. At this time, the active component amplitude of the reference source current takes a negative value, and the parallel compensator is controlled to adjust the current phase, so that the excess active power is injected into the grid in reverse.

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