152 results about "Lcl filter" patented technology

A control system to regulate frequency of an islanded microgrid that includes at least one grid-tied renewable energy source. The system includes a centralized ∞ controller, a multi-agent system, and a distributed control. The centralized ∞ controller generates active and reactive power setpoints. The multi-agent system is integrated into the grid through a grid-tied inverter coupled with an LCL filter. The distributed control controls the multi-agent system and the grid-tied inverter to adjust output power of a multi-agent microgrid storage cooperatively so that they achieve consensus in the energy while providing inertial support.

The invention relates to the technical field of hybrid inverters, and discloses a hybrid inverter supporting reactive compensation and a control method thereof, and the hybrid inverter comprises a DC input unit, a three-phase full-bridge inversion unit, a grid-connected switching unit, a signal acquisition unit and a digital control unit. The direct current input unit comprises a photovoltaic interface, a battery interface and a direct current bus and is used for converging photovoltaic and energy storage electric energy; the three-phase full-bridge inversion unit is composed of a power device and an LCL filter and converts direct current into alternating current. The grid-connected switching unit comprises a static switch and an isolation transformer and is used for controlling power grid connection; the signal acquisition unit detects voltage and current signals; and the digital control unit judges a grid-connected mode or an off-grid mode according to the signal, calculates a reactive current reference value and generates a PWM (Pulse Width Modulation) control signal so as to realize reactive compensation control in the grid-connected mode and the off-grid mode. According to the invention, reactive power compensation capability is provided in both grid-connected and off-grid operation modes, and stable operation of the inverter in various working conditions is ensured.

The invention discloses a control method and system for improving a transient stability area of a grid-connected inverter. It includes performing park coordinate transformation on a three-phase voltage and a three-phase output current of a connection point of a grid-connected inverter to obtain an actual voltage input value and an actual current input value required for current control; obtaining the grid-connected voltage phase through phase-locked loop processing; generating, by the power control module, the current command value required by the current control module; using the sliding mode current control method, by the current control module, to generate a dq voltage signal, and obtaining PWM modulated voltage control signals through inverse park transformation; using a LCL filter to filter out high-order harmonics to achieve grid-connected control. The present invention effectively improves the transient stability of the grid-connected inverter by using the sliding mode control method in the current controller.

The invention relates to a general network construction control method for a converter, the converter is connected to a common connection point through an LCL filter, the control link comprises an active outer ring, a reactive outer ring, a virtual impedance ring and a voltage and current control ring, and in the reactive voltage control link, a voltage amplitude difference value and a reactive power difference value are obtained through calculation; multiplying and superposing with a voltage feedback coefficient and a reactive power regulation coefficient, and generating a voltage amplitude reference of a converter voltage loop through a proportional-integral regulator; in the active frequency control link, a frequency difference value and an active power difference value are obtained through calculation, are multiplied by a frequency feedback coefficient and an active adjustment coefficient respectively and then are superposed, and a frequency reference of a voltage inner loop is generated through a proportional-integral regulator; in the general networking control process, outer loop control parameters are changed according to different application scenes, and different active loop and reactive loop control is achieved.

The invention discloses a two-degree-of-freedom prediction control method of an LCL filtering type three-phase grid-connected inverter system, and belongs to the field of power electronic converter control. A prediction control reference instruction is obtained by sampling parameters of inverter side current, capacitor voltage, network side current and power grid voltage at the moment k, and a continuous and discrete model of an LCL filtering type three-phase grid-connected inverter system is established; designing a control function based on a grid-side current reference tracking error and a gradient thereof, and establishing a prediction model; constructing a prediction cost function based on a control function, and obtaining a prediction control reference instruction by using a minimum value of the prediction cost function; and determining an optimal voltage vector and an action duty ratio according to the prediction control reference instruction, generating a control pulse signal according to a symmetrical five-section pulse mode, and acting on each switching tube in the inverter to realize prediction control of the LCL filtering type three-phase grid-connected inverter system. The method is simple in step, convenient to use, constant in switching frequency and good in stability.

The invention relates to the technical field of voltage source type grid-connected inverter control, and particularly discloses a voltage source type inverter active damping control strategy based on power grid voltage feed-forward, which comprises an LCL filter module, an inductance voltage differential feedback active damping loop, a power grid voltage feed-forward compensation loop and a proportion-resonance controller. By introducing a grid-side inductive voltage first-order differential feedback link, the damping characteristic of the system is enhanced, and LCL resonance is suppressed; and meanwhile, a power grid voltage feed-forward loop is designed, so that the interference of power grid disturbance on grid-connected current is eliminated. According to the virtual resistance parameter design method based on the optimal damping ratio and the feed-forward loop transfer function optimization strategy, the dynamic response capability, the resonance suppression effect and the weak power grid adaptability of the voltage source type inverter can be effectively improved, and the system stability and the electric energy quality are remarkably improved.

The invention discloses a control method, a control device and a switching power supply, the control method is applied to an N-phase converter, and the control method comprises the following steps: calculating an electrical parameter output by the N-phase converter and a modulation wave required by each phase bridge arm switching tube when a common-mode voltage reaches an expected value through voltage loop and current loop double closed-loop control; adjusting the current modulation wave of each phase of bridge arm switch tube so as to obtain N first modulation waves; calculating a second frequency required by a modulation wave of each phase of bridge arm switch tube when each phase of bridge arm switch tube realizes ZVS by predicting the magnitude of bridge arm side inductive current pulsation in each phase of LCL filter, taking the second frequency as the frequency of a carrier wave, and generating N carrier waves; and comparing the first modulation wave of each phase of bridge arm switch tube with the corresponding carrier wave to obtain a driving signal for controlling the on and off of each phase of bridge arm switch tube. According to the invention, good harmonic performance can be obtained while low common-mode voltage is realized.

The invention relates to the technical field of electric vehicles, in particular to an electric vehicle V2G charging pile stability control method and system and electronic equipment. According to the method, after a state variable and a control variable are obtained, the state variable and the control variable are input into a passive controller to obtain a switching function, and on-off of a three-phase four-wire bidirectional converter of the electric vehicle V2G charging pile based on the LCL filter is controlled based on the switching function; the passive controller is obtained based on an improved electric vehicle V2G charging pile three-phase four-wire bidirectional converter port controlled dissipation Hamilton equation and a state variable expected trajectory equation, and the state variable expected trajectory equation is used for dynamically adjusting injection damping parameters of the passive controller. Compared with the prior art, the device has the advantages of simple structure, quick response, good stability, easiness in solving engineering practical problems and the like.

The invention belongs to the technical field of electronic power, and particularly relates to an LCL grid-connected inverter model-free predictive current control system and method based on sampling noise compensation, and the system comprises an inverter main circuit, an LCL filter and a controller. The controller is configured to firstly calculate a current gradient and a voltage gradient according to a collected system operation signal; then, a second-order generalized integrator is used for conducting accurate compensation on sampling noise contained in the gradient; and finally, executing a model-free predictive control algorithm based on the compensated gradient, and preferably selecting an optimal voltage vector through a multi-objective value function integrating inverter side current, capacitor voltage and network side current. According to the method, sampling noise interference is effectively suppressed, the control precision and the anti-interference capability of the system are improved, and stable and efficient operation of the LCL grid-connected inverter can be realized without additional damping.

The invention relates to the technical field of microgrids, in particular to an integrated light storage and charging grid-connected direct-current microgrid system and a control strategy thereof, and the system comprises a plurality of groups of photovoltaic arrays, a direct-current bus, an energy storage battery pack, a supercapacitor bank, a large power grid, a charging pile, a bidirectional DC-AC converter, a DC-DC converter and a power distribution unit, the photovoltaic array is connected with the direct current bus through a Boost circuit; the direct current bus is connected with the energy storage battery pack and the super capacitor bank through a DC-DC converter; the DC bus is connected with the large power grid through a bidirectional DC-AC converter and an LCL filter. The DC bus is electrically connected with the plurality of charging piles, and the outputs of the plurality of charging piles are connected in parallel through a controllable high-voltage DC contactor; and the power distribution unit is used for dynamically controlling the number of parallel output paths of the charging piles according to load requirements.

The invention relates to the technical field of data center energy storage, and discloses a data center flywheel energy storage system and method based on an LCL filter, and the method comprises the steps: collecting a power grid side current signal, decomposing a harmonic component, and dynamically adjusting the parameters of the LCL filter to suppress harmonic waves; determining and executing a charging and discharging control strategy according to the direct-current bus voltage and the flywheel rotating speed; flywheel vibration and acceleration are monitored in real time, operation stability is evaluated, and a control strategy is corrected; and the harmonic suppression effect is optimized by combining rotating speed feedback and voltage data compensation filter parameters. The system comprises a harmonic suppression module, a charge and discharge control module, a stability evaluation module and a filtering parameter optimization module. Through multi-parameter dynamic adjustment and multi-module cooperative control, composite suppression of power grid harmonics and accurate adjustment of the flywheel energy storage state are achieved, the system operation stability and the filtering effect are improved, and the method is suitable for a data center energy storage scene.

The invention provides a resonance suppression method for a three-phase PWM (Pulse Width Modulation) rectifier with an LCL (Lower Control Limit) filter, which relates to a three-phase PWM rectifier control technology, and is characterized in that on the basis of vector control of power grid voltage orientation, voltage and current sampling is carried out at fixed time intervals, inner loop control is implemented, and on the premise of ensuring volt-second balance in a pulse width modulation process, namely, a PWM process, the voltage and current are sampled at fixed time intervals, so that the resonance suppression efficiency is improved. And the sampling period is minimized. According to the method, the sampling frequency is increased, the system bandwidth is improved, and resonance suppression can be achieved under the low carrier frequency when main circuit parameters are not matched.

The application discloses a kind of LCL grid-connected current feedback active damping control method and system, belong to power filter control technical field, including the grid-connected current i2 of the acquisition inverter net side;Grid-connected current i2 flows through negative low-pass-high-pass filter and is handled, obtains feedback current;Feedback current and the output of inverter current controller are superposed, as the control signal of LCL filter.The application will not amplify high-frequency harmonic current, and the control system still has good robustness when LCL filter parameter changes.

The invention discloses a large-capacity energy storage converter based on a DAB-ANPC cascade architecture, which comprises a pre-stage DC-DC converter and a post-stage DC-AC inverter which are cascaded, the pre-stage DC-DC converter adopts a dual active bridge (DAB) circuit and comprises a primary and secondary full bridge, a high-frequency isolation transformer, a series inductor and a blocking capacitor, and electrical isolation and wide voltage input are realized; the back-stage DC-AC inverter is a three-phase three-level active neutral point clamp (ANPC) topology, each phase of bridge arm comprises six full-control switches, loss is balanced through the clamp switches, and the output end of the back-stage DC-AC inverter is connected with the LCL filter. According to the invention, DAB power transmission is controlled and adjusted through single phase shift, and an ANPC switch tube conduction time sequence is dynamically allocated by adopting stacked carrier SPWM modulation, so that the problems of electrical isolation and wide voltage can be solved, and a new energy fluctuation scene is compatible; the device loss is balanced, local overheating is avoided, and the system efficiency and reliability are improved; soft switching and LCL filtering are cooperated, so that the switching loss and harmonic interference are reduced, and the cost is reduced; bidirectional energy flow is supported, and the charging and discharging requirements of an energy storage power station are met.

The invention relates to a grid-connected inverter switching tube open-circuit fault diagnosis method. The method comprises the following steps: step 1, analyzing abnormal influence factors of electric energy quality of a photovoltaic power station; 2, analyzing a resonance mechanism of a parallel inverter LCL filter circuit; 3, analyzing a common mode interference mechanism of the grid-connected inverter; 4, grid-connected inverter switching tube open-circuit fault diagnosis is carried out; the method has the advantages of current characteristic analysis, resonance phenomenon analysis and common mode interference consideration.

The invention relates to an equivalent modeling method and device for a lithium battery energy storage power station, computer equipment, a readable storage medium and a program product, and relates to the technical field of simulation modeling. The accuracy of the equivalent model obtained through simulation can be improved. The method comprises the following steps: determining a plurality of lithium battery energy storage power stations needing equivalence in a power system, constructing single body models of lithium batteries, and carrying out equivalence modeling by adopting an arrangement mode of connecting in series and then connecting in parallel on the basis of the single body models to obtain an equivalence model of a lithium battery pack; performing parameter aggregation on the LCL filter according to the equivalent circuit diagram of the LCL filter in the lithium battery energy storage power station to obtain equivalent reactance values respectively corresponding to two inductors and one capacitor in the LCL filter; simulating a rotor motion equation of the virtual synchronous generator by adopting a VSG control strategy, and performing controller parameter aggregation based on the rotor motion equation to obtain a parameter aggregation result; and performing equivalent modeling on the plurality of lithium battery energy storage power stations based on the equivalent model, the equivalent reactance value and the parameter aggregation result.

The invention discloses a multipath parallel current-sharing high-frequency auxiliary power supply system based on ADRC-PI double closed loops, which comprises an LCL filter and a power supply system, and is characterized in that the LCL filter is connected with the power supply system, and the power supply system comprises a plurality of devices arranged in parallel; wherein each device comprises a boost chopping module, an inversion module, a diode uncontrolled rectification module and a Buck module, and the system adopts double-loop control of voltage outer loop-current inner loop combination for the boost chopping module of each device. An ADRC is designed as a voltage outer ring and a PI is designed as a current inner ring, and an automatic current sharing strategy is added to control the output voltage of the boost module and the current sharing condition between multiple paths of equipment; and the inverter module and the Buck module adopt a fixed duty ratio to control the output power of the power supply to be matched with the power required by the load. According to the invention, the output power quality and transient performance of the multi-path parallel current-sharing high-frequency auxiliary system are improved.

The present invention relates to an energy storage converter system with adaptive function and an off-grid starting method thereof, the system comprising: a user power grid, a battery energy storage device and an energy management system, the battery energy storage device comprising a battery and an energy storage converter, the energy storage converter comprising a supporting capacitor, a power unit, an LCL filter, an AC contactor, and an energy storage converter controller; the energy storage converter controller comprising a DSP module and an FPGA module, the FPGA module being connected to the power unit, the AC contactor, and the energy management system, and the FPGA module being connected to the DSP module to realize a coordinated control function. The present invention can adaptively judge the voltage amplitude of the power grid and send an off-grid enabling signal to the energy storage converter controller, and can realize the off-grid starting and operation of hundreds of energy storage converters. No matter what state the current off-grid power grid is in, the energy storage converter can be adaptively started, and finally an off-grid power grid is established, meeting the off-grid operation requirements of high-power loads.

A common mode choke device is provided with a first common mode choke and a second common mode choke, the first common mode choke and the second common mode choke are arranged in parallel such that annular iron cores are coaxial, and a pair of opposing metal rings formed as annular metal plates are attached to opposing annular surfaces of the first common mode choke and the second common mode choke. A pair of opposed metal rings is connected to a reference potential. The pair of opposing metal rings function as a capacitance of a parasitic capacitance corresponding to the area of the opposing surfaces and the distance between the opposing surfaces, and thus the common mode choke device functions as an LCL filter.

The application discloses a control method of an LCL type grid-connected inverter based on capacitor voltage feedforward compensation and composite active damping, which comprises the following steps: collecting a coupling point voltage from a common coupling point of an LCL type grid-connected inverter, processing the coupling point voltage to obtain phase angle information; collecting a grid current, calculating a first damping signal based on the grid current, and calculating an original reference current based on the grid current and the phase angle information; calculating an error signal based on the grid current and the original reference current, generating an original reference voltage based on the error signal; collecting a capacitor voltage of an LCL filter circuit in the LCL type grid-connected inverter, calculating a second damping signal based on the capacitor voltage; calculating an optimized reference voltage based on the original reference voltage, the first damping signal and the second damping signal; generating a PWM driving signal based on the optimized reference voltage, and controlling the LCL type grid-connected inverter by using the PWM driving signal. The application not only has good economic efficiency and resonance peak suppression effect, but also can suppress background harmonics while maintaining stable operation of the grid-connected inverter under a weak grid.

To address the problem that conventional grid-connected renewable energy sources, when connected to the grid at a high rate, effectively reduce grid inertia and are prone to abnormal interactions with the grid, leading to problems such as low-frequency oscillations, subsynchronous oscillations, and harmonic oscillations, the present invention proposes a grid-connected control system for wind power and photovoltaic power generation, comprising: a wind turbine, a synchronous generator, a wind turbine-side converter, a capacitor, a grid-side converter, an LCL filter, a grid, a photovoltaic power generation unit, a photovoltaic converter, a control loop for the wind turbine-side converter, a control loop for the grid-side converter, and a control loop for the photovoltaic converter. This invention enables wind power and photovoltaic power generation to be connected to the grid through the same grid-side converter, reducing costs. It also presents a voltage source-like characteristic to the grid, similar to that of a synchronous generator, providing inertia and frequency support to the grid, while enhancing the stability of their interaction with the grid and suppressing oscillations.

The invention discloses a self-adaptive control architecture method for improving the stability of a weak power grid photovoltaic grid-connected system, and belongs to the technical field of inverter control. In order to solve the stability problem of a following grid type inverter caused by power grid impedance change under an existing current double-closed-loop control strategy, the method realizes robustness improvement of a system through an additional controller, and comprises the following steps: firstly, establishing a main circuit comprising a two-level inverter and an LCL filter and a stable traditional current double-closed-loop control system under a strong power grid; and then voltage and current in the circuit are measured to construct an oscillation suppressor adaptive to the impedance change of the power grid. Starting from a photovoltaic grid-connected system based on a grid-following inverter and a traditional current double-closed-loop strategy, damping compensation for the impedance change of the power grid is realized by introducing an additional controller, and a reliable scheme is provided for a new energy grid-connected system to cope with the impedance change of the power grid.

The invention relates to the technical field of grid-connected inverters, in particular to a method for correcting positive virtual impedance of an LCL type inverter in a Nyquist frequency, which comprises the following steps of: accurately determining parameters of capacitor voltage feedback branches in an LCL filter, establishing an equivalent formula of virtual impedance, and adjusting parameters in primary differential feedback so as to correct the positive virtual impedance of the LCL type inverter in the Nyquist frequency. The method successfully widens the positive damping frequency range, optimizes the impedance characteristics of the inverter through the virtual impedance of the parallel proportional term, the primary differential term and the secondary differential term and the calculation of the total parallel impedance formula, and obtains the impedance characteristics of the inverter by drawing various impedance-frequency curves. Comprising a virtual impedance-frequency curve, a parallel impedance-frequency curve and a primary differential impedance-frequency curve, and an intuitive impedance characteristic analysis tool is provided for a system designer and an engineer; and finally, by drawing a total impedance-frequency curve and verifying whether the system maintains the positive resistance characteristic in the Nyquist frequency range, the stability of the system is ensured.

The goal is to miniaturize and lighten common mode choke coil devices. [Solution] A first common mode choke coil and a second common mode choke coil are arranged parallel to each other so that their annular cores are coaxial. A pair of opposing metal rings, formed as annular metal plates, are attached to the opposing annular surfaces of the first and second common mode choke coils, and the pair of opposing metal rings are connected to a reference potential. Since the pair of opposing metal rings function as capacitances with parasitic capacitances corresponding to the area of ​​the opposing surfaces and the distance between the opposing surfaces, the common mode choke coil device functions as an LCL filter.

The embodiment of the utility model provides a magnetic integrated inductor assembly for an LCL filter and the LCL filter. The magnetic integrated inductor assembly comprises: a magnetic core having at least one magnetic circuit; the first winding and the second winding are wound at different magnetic circuit positions of the magnetic core respectively and are magnetically coupled and superposed through at least one magnetic circuit of the magnetic core, and the first winding and the second winding are arranged to enable the first winding to form machine-side inductance and enable the second winding to form resonant inductance. Therefore, the inductance value and the filtering performance can be improved, the ripple current and the magnetic core loss are reduced, and the copper wire consumption and the magnetic core size are reduced.

The utility model discloses a novel nine-level H-type inverter device, which comprises a direct-current power supply, a load, five resistors, six capacitors, twelve diodes, nine switch tubes and two inductors, four diodes and one switch tube form a secondary loop, and two inductors and one capacitor form an LCL filter circuit. The four switch tubes form an H-type inverter bridge connection mode, compared with other nine-level inverters, the novel nine-level H-type inverter is simpler in structure, and a secondary loop and a tertiary loop do not influence each other, that is, two levels emitted by the secondary loop and four levels emitted by the tertiary loop do not influence each other. A current and voltage loop is provided through a secondary loop, and the distortion rate of output voltage and current is reduced through an LCL filter circuit. The circuit provided by the utility model guarantees the normal operation of the inverter in an AC power supply system, and reduces the failure rate of electrical equipment and unnecessary loss.

This invention relates to a Kalman filter active damping iterative learning model predictive control method for grid-connected inverters. First, by using only measured signals of inverter-side current and grid-side voltage through a Kalman filter, the state variables of the LCL filter are estimated in real time, replacing physical sensors and reducing hardware costs. Second, based on the estimated capacitor voltage, the active damping current is calculated, and a composite current reference value for the inverter side is generated to actively suppress resonance. Then, an iterative learning control outer loop is introduced to compensate for periodic disturbances such as dead-zone effects, generating a compensation current using historical error data to improve current quality. Finally, finite set model predictive control is used to optimize the switching state, achieving high-precision tracking. This invention reduces the number of sensors, enhances anti-interference capability and robustness, and significantly reduces the total harmonic distortion of the output current. It is suitable for distributed renewable energy generation systems, ensuring the stable and efficient operation of grid-connected inverters.

The invention relates to the technical field of electronic circuits, in particular to a method and device for calculating active damping in a wind power generation system, and the method comprises the steps: constructing an active damping transfer function suitable for a single-ring network construction type permanent magnet synchronous wind power generation system based on a control strategy of a single-ring network construction type inverter and a control strategy of the permanent magnet synchronous wind power generation system; calculating a proportionality coefficient and a time constant based on a system parameter meeting a first preset condition, a system characteristic quantity meeting a second preset condition and a stability index meeting a third preset condition in the single-ring network construction type permanent magnet synchronous wind power generation system; and quantifying the active damping transfer function according to the proportionality coefficient and the time constant to obtain an active damping compensation transfer function. Therefore, the problems that in the prior art, due to the fact that the resonance dynamic and non-minimum phase characteristics of the LCL filter and the influence of RAP control on the LCL resonance mode are not considered, the high-frequency resonance dominant instability phenomenon is likely to occur, and in addition, necessary theoretical support is lacked are solved.

The invention discloses an AC / DC converter DC bus capacitor capacitance value reduction system under an unbalanced power grid, which comprises a three-phase power grid, an LCL filter, a DC bus capacitor, a load, a three-phase two-level converter main circuit and a Buck power decoupling circuit, wherein the main circuit is used for power conversion; the Buck decoupling circuit is used for absorbing double frequency pulse power formed by a product of positive sequence voltage and negative sequence current on an alternating current side, so that the capacitance value of a direct current bus capacitor is reduced. The Buck decoupling circuit is added to the DC bus of the AC / DC converter under the unbalanced power grid, the double-frequency power pulsation on the DC side is effectively filtered out, the capacitance value of the DC bus capacitor is reduced, meanwhile, the thin-film capacitor with the small capacitance value and the long service life is used for replacing a traditional electrolytic capacitor, the reliability and stability of the system are improved, and the service life of the system is prolonged. The grid-side current balance positive sequence and the direct-current side voltage stability are realized, and the new energy power generation utilization rate and the overall efficiency of a power system are remarkably improved.

The invention belongs to the technical field of power equipment, and provides a bidirectional inverter system for a high-altitude power grid and an implementation method of the bidirectional inverter system. The system comprises an STM32F474 main control chip, a six-switch three-phase half-bridge inverter circuit based on gallium nitride, an LCL filter circuit, a harmonic detection and control subsystem, a current inner loop controller, a drive circuit, a wireless communication module and a sampling resistor. The method comprises the steps of direct current conversion, high-frequency filtering, signal acquisition, harmonic detection and optimization and controller regulation and control. According to the invention, through the second-order generalized integrator, the synchronous reference coordinate transformation and the low-pass filter, synchronous detection of signals is realized, and the purity of the signals is ensured; by combining a PI controller and an RC repetitive controller, harmonic suppression is optimized; through SPWM wave control, the problem of three-phase imbalance is solved, and the performance and the stability of the system are improved; and through the wireless communication module, remote control is realized, and the complexity of field maintenance is reduced.