11 results about "Grid synchronization" patented technology

The invention belongs to the technical field of power grids, and particularly relates to a hydrogen fuel cell grid-connected inverter fault test and ride-through method. Comprising the following steps: S1, simulating three-phase symmetrical voltage drop, inter-phase voltage drop and single-phase voltage drop of a power grid through a low-voltage fault generation device; s2, collecting the voltage of a power grid through a high-precision voltage sensor, and when the voltage of the power grid drops, judging whether the system needs to carry out low-voltage ride through at the moment according to a distributed energy low-voltage ride through curve; and S3, when the system needs to carry out low-voltage ride-through, a dual-second-order generalized integrator pre-filtering phase-locked loop (DSOGI-PLL) is combined with grid-connected point voltage full-feedback compensation, negative-sequence components generated by symmetric and asymmetric drop of the power grid voltage are eliminated, and current impact suppression and negative-sequence current elimination are realized. The problem of power grid synchronization under the condition of power grid voltage drop is finally solved.

The present application relates to the technical field of energy storage, and particularly relates to an energy storage black start system and a control method thereof, the system comprising a physical layer, a coordination control layer and a network communication layer; the physical layer comprises at least one black start power module, at least one load control module and at least one grid synchronization module, the coordination control layer comprises a centralized system management unit and a local autonomous controller, and the network communication layer is a star-shaped heterogeneous redundant network based on a time-sensitive network, and is used for realizing data interaction between the coordination control layer and the physical layer. The present application avoids the whole black start failure caused by single point failure and the start interruption caused by the mismatch between the preset plan and the actual situation, improves the success rate of black start, guarantees continuous high-quality power supply to sensitive loads, enhances the robustness under incomplete or delayed communication, ensures the completion of cross-layer instruction transmission and state synchronization within milliseconds, and prolongs the service life of equipment.

The invention relates to a VSG stability evaluation and grading current limiting method based on fault power angle characteristics. The method comprises the following steps: carrying out transient stability quantitative evaluation on current amplitude limiting control and transient virtual impedance based on an equal area criterion, and generating optimization design suggestions of the current amplitude limiting controller and the transient virtual impedance; generating a power grid fault judgment logic containing a buffer area as an intermediate state based on the optimization design suggestion; respectively generating power outer ring overcurrent limiting strategies under the condition of power overload and the condition of fault ride-through; internal current limiting strategies including transient virtual impedance current limiting control and apparent current amplitude limiting control are generated respectively; and designing and generating a current-limiting state machine based on a power grid fault judgment logic, a power outer ring overcurrent limiting strategy and an internal current-limiting strategy to realize graded current limiting. According to the invention, dynamic switching of the current limiting state is realized through the adaptive power reference and impedance adjustment mechanism, and the fault current is effectively suppressed without affecting the synchronization capability of the power grid.

The present application belongs to the field of large high-voltage transformer bushing voltage monitoring, and particularly relates to a novel electromagnetic bushing voltage divider, which comprises sequentially connected voltage input unit, step-down transformer T1, amplitude and phase modulation unit, double-winding output isolation transformer T2 and voltage output unit; the secondary coil of the step-down transformer T1, the output end of the amplitude and phase modulation unit and the output end of the voltage output unit are respectively connected with different terminals on terminal block P1. The present application is installed at the voltage tap part of the bushing, and through the adjustment of the switch state of the bushing voltage divider adjustment switch group, the secondary output voltage of the voltage divider is linearly proportional to the primary voltage borne by the bushing, the voltage division precision of 1 ‰ can be realized, the phase precision can be within 0.05° deviation, and further, the signal can be provided for grid synchronization, and the primary voltage can be monitored.

The application provides a grid synchronization control method, device, equipment and medium of a photovoltaic inverter, comprising: collecting three-phase voltage signals at a grid point of common connection in real time, and preprocessing the three-phase voltage signals to obtain q-axis voltage residuals; serializing sampling the q-axis voltage residuals to construct a short-time phase deviation time sequence; inputting the short-time phase deviation time sequence into a pre-trained recurrent neural network model to obtain a predicted phase angle increment; based on the predicted phase angle increment, combining a photovoltaic grid-connected working condition, and calculating a synchronization phase angle; and based on the synchronization phase angle, controlling the grid synchronization phase of the photovoltaic inverter. The phase deviation is predicted through the recurrent neural network, the phase error problem caused by the lag of the traditional PI control is overcome, and the accuracy and stability of the grid synchronization of the photovoltaic inverter are effectively improved.

This invention provides an integrated device and method for concrete 3D printing based on mesh-based synchronous reinforcement, relating to the field of concrete 3D printing equipment. It addresses the problems of low integration, discontinuous mechanical properties, and low automation levels caused by the separation of reinforcement and printing processes in existing concrete 3D printing. The device includes a concrete conveying and printing module and a mesh-based synchronous reinforcement module. The concrete conveying and printing module includes a material cylinder, a material transfer channel, and a diversion nozzle. The mesh-based synchronous reinforcement module is connected to the diversion nozzle. The diversion nozzle contains a mesh channel and symmetrical diversion channels. After being diverted, the concrete wraps around the flexible steel mesh conveyed by the mesh channel at the confluence printing port, achieving synchronous printing and reinforcement. The method achieves intra-layer and inter-layer mechanical continuity by controlling the cross-layer protrusion of the steel mesh to form overlaps. This invention achieves integrated automation of printing and reinforcement, improves the overall mechanical properties of concrete components, reduces post-processing, and adapts to complex bending printing paths.

The invention discloses a harmonic suppression method and system under a high background harmonic condition, and the method comprises the steps: carrying out the wavelet transformation of an input power grid voltage signal, and extracting the amplitude information of each harmonic in real time; dynamically determining a target harmonic set which needs to be suppressed at present through a preset threshold judgment mechanism according to the extracted amplitude information of each harmonic; for each harmonic in the target harmonic set, synchronously executing harmonic suppression and phase compensation operation; sending the signal subjected to harmonic suppression and phase compensation into a phase-locked loop to obtain a power grid synchronous phase; the system provided by the invention comprises an extraction module, a determination module, a compensation module and a suppression module, and provides a highly purified input signal for the phase-locked loop, so that the phase-locked loop can still maintain rapid and overshoot-free high-precision phase locking under serious harmonic pollution; and the operation stability and the electric energy quality of the grid-connected inverter in a complex power grid environment are remarkably improved.

The application discloses a grid-connected inverter stability analysis method and device, the method comprises the following steps: according to the circuit structure of the grid-connected inverter system in the dq domain, a small signal model of the grid-connected inverter system is established in the controller dq coordinate system; the latch voltage of the control loop of the grid-connected inverter system in the controller dq coordinate system is calculated; according to the conversion relationship between the latch voltage of the phase-locked loop control loop, the controller dq coordinate system and the grid dq coordinate system, the grid synchronization small signal model of the grid-connected inverter system in the control dq coordinate system is obtained; according to the grid synchronization small signal model, the loop gain is calculated and the synchronization stability of the grid-connected inverter system is obtained. By adopting the application, the stability margin of the system can be identified through the constructed single-input single-output grid synchronization small signal model, and the stability of the grid-connected inverter can be improved.

The invention discloses a common-bus photovoltaic energy storage AC micro-grid simulation model construction method, and the method comprises the steps: constructing a micro-grid system architecture through cooperation of four core modules, and defining a simulation target; according to the micro-grid system architecture, performing digital modeling on each functional module of the micro-grid, and constructing a simulation model; setting an initial parameter of the simulation model and a simulation scene for multi-experiment comparison; the simulation model is optimized according to the multi-experiment contrast result, the step S300 is repeated for the optimized simulation model, and a final micro-grid simulation model with qualified accuracy is obtained. And realizing accurate grid-connected synchronization through a PLL phase-locked loop according to the micro-grid simulation model. The model solves the problems of photovoltaic output fluctuation, bus voltage instability, inverter harmonic pollution and the like, is high in simulation precision and fast in dynamic response, can accurately simulate system operation characteristics under complex working conditions, provides reliable support for engineering design, parameter optimization and stability verification of a common-bus photovoltaic energy storage micro-grid, and has a wide application prospect. The method is suitable for distributed photovoltaic power stations and other scenes.

The application belongs to the technical field of power electronics and power grid synchronization, and discloses a frequency adaptive sliding mode observer phase-locked loop for power grid synchronization, which comprises a quadrature signal generator based on a sliding mode observer, a phase detector, a loop filter, a voltage-controlled oscillator and a frequency feedforward branch, and the loop filter is a PI controller; the proportional coefficient of the PI controller is Kp; the integral coefficient of the PI controller is Ki; and the frequency estimation value of the phase-locked loop is ω0; the frequency feedforward branch is used for returning the frequency reference of the quadrature signal generator to the quadrature signal generator; and the phase-locked loop can adapt to frequency changes and ensure high-precision power grid synchronization technology, so as to meet the strict demand of MEA power grid on real-time state estimation.

The invention provides a control method for synchronous grid connection of a thermal energy storage system and a power grid, belongs to the technical field of thermal energy storage systems, and realizes rapid synchronous tracking by constructing a self-adaptive phase-locked loop controller adopting a fuzzy control algorithm and combining with a feed-forward compensation mechanism. A heat storage power prediction model based on a heat transfer differential equation is established to provide a prospective control basis, a sliding mode variable structure power controller is designed, power fluctuation is eliminated by adopting a reaching law method, and a neural network control model based on progressive network growth and element gradient optimization is constructed to realize intelligent multi-target coordination optimization. Meanwhile, power factor compensation control and an electric energy quality comprehensive treatment strategy are established to guarantee grid-connected electric energy quality, and finally safe and reliable operation of the system is ensured through a system operation state evaluation mechanism and a standby control strategy, so that the technical problems of response lag and insufficient control precision during synchronous grid connection of the thermal energy storage system and the power grid are solved.