57 results about "Lcl filter" patented technology

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 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 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.

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.

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 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.

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.

This invention discloses a one-stop intelligent megawatt box system based on TE-SVM modulation and its intelligent controller and control method, including an MPPT controller for tracking the maximum power of a DC / DC converter, a positive and negative sequence voltage decomposition module, a phase-locked loop, and a C-type control for the LCL filter. f With R f A current correction module that corrects the three-phase average current output from the component; a positive-sequence theoretical active power reference current conversion module; a positive-sequence theoretical reactive power reference current conversion module; and an output voltage U. α +、U β + Two-phase positive sequence static voltage converter module, output voltage U α -, U β A two-phase negative-sequence static voltage converter module, a TE-SVM waveform generation module based on the TLS-ESPRIT algorithm for estimating smart grid frequencies, and the TE-SVM waveform generation module utilizing voltage U α +、U β + and U α -, U β - Synthesize a reference voltage and generate a waveform based on the estimated smart grid frequency to control the inverter to perform inversion.

The invention discloses a virtual impedance adjusting system for a three-phase four-wire converter, and the system comprises a T-type three-level three-bridge arm main circuit which is used for controlling the state of a bridge arm power switch tube of a current conversion part, and achieving the energy exchange of a DC side and an AC side; the LCL filter is used for suppressing harmonic components in the output current of the inverter; and the control unit is used for independently controlling each bridge arm or each phase so as to adjust the virtual impedance. The invention further discloses a virtual impedance adjusting method of the three-phase four-wire converter. According to the invention, through mathematical model derivation and control strategy design, wide-range accurate control of virtual impedance is realized.

The utility model relates to active power electronic filter and power electronic technical field discloses a kind of active power filter based on high-power IGBT single tube parallel driving, including multisignal fusion detection module, DSP control module, drive control module, IGBT power bridge arm module, auxiliary power module, support module and LCL filter module, the DSP control module is electrically connected with drive control module and support module respectively, the drive control module is electrically connected with IGBT power bridge arm module, the output end of switching power supply is electrically connected with the input end of multisignal fusion detection module, the IGBT power bridge arm module is electrically connected with LCL filter module.The utility model in, by adopting the design of IGBT single tube parallel, unnecessary intermediate connecting piece is reduced, equipment volume is effectively reduced, the problem such as the space occupancy big and installation inconvenience caused by complex structure is solved.

The present application relates to the field of power electronics, in particular to a common-mode voltage suppression three-phase four-wire converter LCL filter parameter determination method, wherein the method comprises: using double Fourier decomposition, analyzing the entire frequency spectrum of the common-mode voltage suppression PWM of the two-level four-bridge arm converter, obtaining the frequency domain distribution of the PWM modulation voltage; based on the frequency domain distribution of the PWM modulation voltage, according to the differential mode transfer function and the common mode transfer function of the equivalent circuit of the three-phase four-wire system, establishing the functional relationship of the filter parameters to the circuit characteristic output parameters; based on the preset constraint condition, solving the functional relationship to obtain the filter parameter feasible region, and determining the final LCL filter parameter according to the filter parameter feasible region. Therefore, the problems of parameter design depending on artificial experience, circuit simulation, and time-consuming and laborious design process are solved, and the efficiency and reliability of parameter design are improved.

The invention provides a virtual synchronous machine over-current capability enhancing system and method, and relates to the technical field of power electronics and new energy power generation grid-connected control, the system comprises a main power channel, a transient over-current channel, an energy regulation and control unit and a control driving unit, the main power channel comprises a three-phase inverter and an LCL filter; the transient overcurrent channel comprises a thyristor, a current-limiting inductor and a current-limiting reactor; the energy regulation and control unit comprises a chopping resistance circuit and a super capacitor module, the chopping resistance circuit and the super capacitor module are connected in parallel to a direct current bus of the virtual synchronous machine, and the chopping resistance circuit comprises a chopping IGBT and a braking resistor which are connected in series; and the control driving unit is used for performing staged control on the virtual synchronous machine, the thyristor and the chopper IGBT according to the system operation state. According to the invention, the defects that the current amplitude limiting is too strict and the transient energy cannot be fully released when an existing virtual synchronous machine is overloaded can be overcome, so that the transient overcurrent capability of the virtual synchronous machine is improved.

The utility model discloses a device for measuring system capacitance current by using an injection method. The device comprises a measurement and signal generator and an integrated injection transformer, the measurement and signal generator internally comprises an H-bridge inversion unit, an LCL filter circuit, a power supply and a controller; the integrated injection transformer comprises a boosting transformer, a voltage transformer and a current transformer; the output end of the controller is connected with the controlled end of the H-bridge inverter unit; the power supply, the H-bridge inverter unit and the LCL filter circuit are sequentially connected in series, the output end of the H-bridge inverter unit is connected to the boosting transformer through the LCL filter circuit, and the other end of the boosting transformer is a signal output end X. According to the utility model, signals with different frequencies are injected into the system, and the capacitance current of the system is calculated by establishing a loop equation according to different zero sequence loop impedances of the system under different frequencies; as the measurement and signal generator and the boosting transformer are large in capacity, the requirement for accurate back measurement after signal injection is met, and therefore the measurement accuracy is high.

The invention relates to a method for testing the capacity of a drive rescue battery. The method comprises the following steps: - disconnecting an LCL filter from an AC power supply; - using the inductors and capacitors of the LCL filter as a test load for testing the capacity of the drive rescue battery, each of the inductors and capacitors of the LCL filter being connected to a first phase or to a second phase, wherein the inductor of the LCL filter connected to the first phase and connected downstream of the capacitor of the LCL filter connected to the first phase to a rectifier circuit, the capacitors of the LCL filter connected to the first phase and to the second phase, and the inductor of the LCL filter connected to the second phase and connected downstream of the capacitor of the LCL filter connected to the second phase to the rectifier circuit form a series connection as a test load; and - determining at least one value of the voltage or of the current of the drive rescue battery generated by the test load.

The application discloses a non-isolated three-level flexible interconnection device and a common-mode current suppression method. The non-isolated three-level flexible interconnection device comprises a controller, a back-to-back power conversion circuit, a first LCL filter, a second LCL filter, a first DC bus capacitor, a second DC bus capacitor, a first common-mode inductor, a second common-mode inductor, a grounding equivalent resistor, a current sensor, a voltage sensor, a first low-voltage area and a second low-voltage area. The back-to-back power conversion circuit controls the size and direction of the power flow transfer between the first low-voltage area and the second low-voltage area by controlling the DC voltage on the DC bus and the size and direction of the output current of the back-to-back power conversion circuit. The controller is used for DC voltage control, power control, common-mode current suppression control and DC midpoint potential balance control, and the DC midpoint potential balance control and the common-mode current suppression control are mutually decoupled. The application realizes the control target of giving consideration to DC voltage balance and common-mode leakage current suppression.

The application discloses a modular LCL filter structure and relates to the technical field of engineering, comprising at least one LCL filter basic unit; the basic unit comprises an inverter side input port, a grid side output port, an N line port, a PCB board, a filter capacitor, a passive damping device, a contactor and a soft starting circuit, and a filter circuit arranged between the inverter side input port and the grid side output port; the filter circuit at least comprises an inductor L1 and an inductor L2 connected in sequence. The modular structure provided by the application can quickly realize the construction of a multi-bridge-arm LCL filter, avoids the customized design of a "large integration" scheme, and saves manpower and time cost.

The invention discloses an integrated magnetic element, a power factor correction circuit and an air conditioner. The integrated magnetic element comprises a first magnet and a second magnet, the plurality of magnetic columns are arranged between the first magnet and the second magnet and are connected with the first magnet and the second magnet; wherein each magnetic column is wound with a coil, a first port, a second port and a third port are led out from each coil, the first port, the second port and the third port are used for connecting the integrated magnetic element with an external circuit, when the integrated magnetic element is used in a PFC circuit, the first port can be connected with a three-phase power supply port of the PFC circuit, and the third port can be connected with a three-phase power supply port of the PFC circuit. According to the power factor correction circuit, the third port is connected with the PFC module, and the second port is connected with the capacitor, so that an LCL filter structure can be formed, current ripples can be effectively suppressed, the current ripple suppression effect of the power factor correction circuit can be effectively improved, and the equipment cost can be reduced.

The invention discloses an energy storage grid-connected system parameter optimization method based on a multi-objective genetic algorithm and related equipment. The method comprises the steps of obtaining an energy storage grid-connected system simulation model; determining transient stability parameter items; constructing a multi-target parameter optimization model by taking the maximum steady-state duration, the dynamic performance of the power grid and the stability margin as targets; solving the multi-target parameter optimization model in combination with the simulation model to generate a preferred parameter combination; judging whether the resonant frequency of the LCL filter of each optimal parameter combination is matched with the switching frequency or not, and if yes, deleting the corresponding optimal parameter combination; and taking a combination, which enables the degree of instability of the simulation model to be the lowest, in the remaining optimal parameter combinations as an optimal parameter combination. It can be seen that according to the method, efficient and low-risk setting of the control parameters can be achieved through simulation-driven multi-target optimization and targeted screening, the transient stability of the energy storage grid-connected system is remarkably improved, and the problems that in the prior art, manual setting is low in efficiency and high in risk are solved.

The invention discloses a power converter and a modulation control method and a controller thereof, by adding a three-level Buck / Boost converter and the modulation control method, a capacitor with higher voltage in a three-phase three-level rectifier direct current bus split capacitor releases more charges, and voltage fluctuation between the capacitor and the capacitor is reduced, so that the direct current bus split capacitor is reduced; furthermore, the capacitor midpoint of the LCL filter is connected with the midpoint of the split capacitor of the direct-current bus through a midpoint clamping wire, so that electromagnetic interference, caused by common-mode voltage fluctuation, of the alternating-current side of the three-phase three-level rectifier can be eliminated, and a filter inductor of the three-level Buck / Boost converter can be configured into two independent split inductors with the same inductance value. And direct-current side common-mode electromagnetic interference is suppressed, and a direct-current side common-mode EMI filter is reduced, so that lightness and miniaturization of passive elements are further realized.

The embodiment of the invention provides a zero-crossing distortion suppression method and system of an inverter, and relates to the technical field of voltage control. Comprising the steps of obtaining a current reference value and a current feedback value at a current moment; acquiring a current difference value according to the current reference value and the current feedback value; inputting the current difference value into a PR controller to obtain a voltage reference value; the state observer obtains bridge arm output voltage according to the current feedback value; extracting a low-frequency component from the bridge arm output voltage through an LPF low-pass filter, and taking the low-frequency component as an output voltage; and acquiring a voltage difference value between the voltage reference value and the output voltage. The zero-crossing distortion harmonic wave can be accurately extracted, the zero-crossing distortion caused by a dead zone can be completely compensated theoretically, the state observer can derive the bridge arm output voltage through the output current of the inverter, the bridge arm output voltage does not need to be sampled, the circuit cost is saved, and when an LCL filter is adopted, the output voltage of the bridge arm is not required to be sampled. The gain coefficient of the current loop has little influence on the gain at the resonant frequency, and the system stability is high.

The invention discloses an LCL integrated filter based on transformer leakage inductance multiplexing. The LCL integrated filter comprises a discrete inductor, a transformer side inductor and a filtering branch, the transformer side inductor is the inherent leakage inductor of the transformer, and the filter branch comprises a filter capacitor C. According to the LCL filter, the inherent leakage inductor of the transformer is multiplexed to serve as topological optimization of the power grid side inductor and the filtering branch, and the technical problems that a traditional LCL filter needs to be independently provided with the power grid side inductor, so that the size is large, cost is high, the inherent leakage inductor of the transformer is idle and wasted, instability is likely to happen under a weak power grid, and harmonic suppression cannot meet the grid connection standard easily are solved.

This invention discloses an adaptive oscillation suppression control method for grid-connected doubly-fed induction generator (DFIG) wind turbines operating under weak power grid conditions. Addressing the stability issues caused by grid impedance variations in existing dual-loop current control strategies, this method enhances system robustness by adding an adaptive controller. First, a main circuit is established, comprising the wind turbine, asynchronous motor, rotor-side controller, grid-side controller, and LCL filter, along with a stable dual-loop current control system under strong power grid conditions. Then, voltage and current measurements are taken in the circuit to construct an oscillation suppressor that adapts to grid impedance variations. Finally, the effectiveness of this strategy in enhancing system damping, suppressing oscillations, and responding to wind speed changes under weak power grid conditions is verified using the MATLAB / SIMULINK platform. Starting from the grid-connected DFIG system and the dual-loop current strategy, this invention introduces an adaptive controller to compensate for grid impedance variations, providing a reliable solution for DFIG systems to cope with grid impedance changes.

The utility model relates to a common direct current bus topology circuit which comprises an LCL filtering module, an active rectification module, a current transformation module and a common direct current bus. The input end of the LCL filtering module is used for being connected with an alternating current power supply input port, and the output end of the LCL filtering module is connected with the input end of the active rectification module; the output end of the active rectifier module is connected with the input end of the converter module through the common direct current bus, and the output end of the converter module is used for being connected with external target equipment; compared with the prior art, the technical scheme of the utility model can effectively suppress the harmonic component in the DC bus, and ensures the safe and stable operation of the frequency conversion system.

The invention discloses a hybrid active damping method and device based on filter capacitor state variable compensation. The method comprises the steps that basic parameters of a system are initialized; establishing a virtual impedance model equivalent to hybrid active damping, and obtaining a critical condition expression for evaluating the minimum phase characteristic of the system and an expression of an LCL filter transfer function damping ratio with respect to resonant frequency based on the model; establishing a plurality of constraint conditions about a system resonant frequency range, a minimum phase characteristic and an LCL filter transfer function damping ratio; the constraint condition is mapped to a three-dimensional parameter plane formed by the filter capacitor current feedback coefficient, the filter capacitor voltage feed-forward coefficient and the frequency to form a constraint region, and a feasible region is determined according to an effective intersection existing in the constraint region; and a group of optimal filter capacitor current feedback coefficients and filter capacitor voltage feed-forward coefficients are determined by taking minimization of the influence of power grid voltage disturbance on inverter current as an optimization target, so that the setting of the hybrid active damping coefficient is realized.

The disclosure relates to a rectifier (1) for rectifying alternating current from a power source (80) with N phases (PA, PB, PC), wherein N is at least two. It includes a power input (2) for connection with the power source (80), an LCL filter (30) connected to the power input (2) via an interruption unit (40), an active front end (10) with at least two levels that includes a direct current bus (11) and is connected to the power input (2) via the LCL filter (30) and the interruption unit (40). The interruption unit (40) is switchable to an interrupting state in which it disconnects the LCL filter (30) and hence the active front end (10) from the power input (2) for N-1 phases (PA, PB), said N-1 phases (PA, PB) including a first phase (PA). The rectifier (1) has an inrush protection bypass (50) for bypassing the interruption unit (40) for the first phase (PA). In order to provide reliable and cheap protection from excessive inrush currents for the rectifier (1) while allowing for particularly high efficiency of the rectifier (1) in normal operation, the inrush protection bypass (50) is conductive only for current flow in one specific direction.

The present invention relates to the technical field of smart grids, and discloses a wide-band impedance modeling and dominant parameter identification method, system and medium for an offshore direct-drive wind turbine. Based on the grid-side converter structure of a direct-drive permanent magnet synchronous wind turbine generator set, by establishing a unified small-signal model considering the PLL, dq current control loop, sampling and modulation delay, and LCL filter link, the positive-sequence and negative-sequence impedance analytical expressions of the unit within a wide frequency band are obtained. And a comparative analysis is carried out on the influence of typical parameters such as the PLL bandwidth, grid-connected voltage, LCL filter inductance, and filter capacitance, and their influence on the impedance response is analyzed, and it is identified that the main influence sources of the wide-band impedance of the unit are concentrated on the dynamic process inside the control system. Through the method of the present invention, accurate modeling of the wide-band impedance of a direct-drive wind turbine and identification of the dominant factors can be achieved, providing a theoretical basis and engineering reference for the analysis of the grid-connected stability of the unit, the judgment of the oscillation mechanism, and the setting of control parameters.

The application discloses a grid-connected converter active damping control method and belongs to the field of converter control. The control method is characterized in that a first-order unstable digital filter is connected in series on a positive and negative feedback path of a capacitor voltage, a reasonable parameter is used for design, and a phase compensation characteristic of the filter is fully utilized to compensate for a phase lag introduced by digital control. The filter can guarantee the stability of the system and improve the robustness of the system in the case of nonlinear change of grid impedance inductance and weak grid, and the filter has few design parameters and a simple design process. The converter loop structure adopting the control method is simple, convenient to design, large in system stability margin, and suitable for three-phase LCL filter grid-connected / following grid type converter occasions.

The utility model discloses an LCL type multi-photovoltaic compatible grid-connected inverter which comprises a photovoltaic array, a DC / DC module, a DC bus, a DC / AC inversion module, an LCL filter and a power grid which are connected in sequence, the DC / AC inversion module is sequentially connected with a PWM generator and an adder, two paths of input of the adder are connected with a first multiplier and a second multiplier respectively, and the first multiplier and the second multiplier are connected with a power grid. Two paths of input of the first multiplier are respectively connected with a PI controller and a first analog-to-digital converter, and two paths of input of the second multiplier are respectively connected with an RC repetitive controller and a second analog-to-digital converter; the first comparison circuit generates a first output level according to the current error signal, and the second comparison circuit generates a second output level according to the harmonic signal. According to the utility model, a pure hardware circuit is constructed to realize weight switching, the fusion proportion of the PI controller and the RC repetitive controller can be switched according to the working condition of the system, the output of the inverter is adjusted according to the reference and the electric energy quality requirement, and the use effect is good.